Publications by year
In Press
Armstrong-James D, Bicanic T, Brown GD, Hoving JC, Meintjes G, Nielsen K, Workshop WGFTEMBO-AIDSRM (In Press). AIDS-Related Mycoses: Current Progress in the Field and Future Priorities.
Trends in Microbiology,
25, 428-430.
Abstract:
AIDS-Related Mycoses: Current Progress in the Field and Future Priorities
Opportunistic fungal infections continue to take an unacceptably heavy toll on the most disadvantaged living with HIV-AIDS, and are a major driver for HIV-related deaths. At the second EMBO Workshop on AIDS-Related Mycoses, clinicians and scientists from around the world reported current progress and key priorities for improving outcomes from HIV-related mycoses.
Abstract.
Hadebe S, Brombacher F, Brown GD (In Press). C-Type Lectin Receptors in Asthma.
Frontiers in Immunology,
9, 1-11.
Abstract:
C-Type Lectin Receptors in Asthma
Asthma is a heterogeneous disease that affects approximately 300 million people worldwide, largely in developed countries. The aetiology of the disease is poorly understood but is likely to involve specific innate and adaptive responses to inhaled microbial components that are found in allergens. Fungal derived allergens represent a major contributing factor in the initiation, persistence, exacerbation and severity of allergic asthma. C-type lectin like receptors such as Dectin-1, Dectin-2, DC-SIGN and Mannose receptor, recognise many fungal derived allergens and other structurally similar allergens derived from house dust mites (HDM). In some cases, the fungal derived allergens have been structurally and functionally identified alongside their respective receptors in both humans and mice. In this review, we discuss recent understanding on how selected fungal and HDM derived allergens as well as their known or unknown receptors shape allergic airway diseases.
Abstract.
Drummond RA, Swamydas M, Oikonomou V, Zhai B, Dambuza I, Schaefer BC, Bohrer AC, Mayer-Barber KD, Lira SA, Iwakura Y, et al (In Press). CARD9+ microglia promote antifungal immunity via IL-1β- and CXCL1-mediated neutrophil recruitment.
Nature Immunology,
20, 559-570.
Abstract:
CARD9+ microglia promote antifungal immunity via IL-1β- and CXCL1-mediated neutrophil recruitment
The C-type lectin receptor/Syk adaptor CARD9 facilitates protective antifungal immunity within the central nervous system (CNS), as human CARD9-deficiency causes fungal-specific CNS-targeted infection susceptibility. We previously showed that CARD9 is required for neutrophil recruitment to the fungal-infected CNS, which mediates fungal clearance. Here, we investigated host and pathogen factors that promote protective neutrophil recruitment during Candida albicans CNS invasion and examined their dependence on CARD9 for in vivo induction. We show that IL-1b is essential for CNS antifungal immunity by driving CXCL1 production, which recruits CXCR2-expressing neutrophils. Neutrophil-recruiting IL-1b and CXCL1 production is induced in microglia by the fungal-secreted peptide toxin Candidalysin, in a p38-cFos-dependent manner. Importantly, microglia rely on CARD9 for production of IL-1b, via both pro-IL-1b transcriptional regulation and inflammasome activation, and of CXCL1 in the fungal-infected CNS, and we show that microglia-specific CARD9 deletion impairs IL40 1b and CXCL1 production and neutrophil recruitment, and increases CNS fungal proliferation. Our data reveals an intricate network of host-pathogen interactions that promotes CNS antifungal immunity and provides novel mechanistic insights into how human CARD9-deficiency causes CNS fungal disease.
Abstract.
Drummond RA, Dambuza IM, Vautier S, Taylor JA, Reid DM, Bain CC, Underhill DM, Masopust D, Kaplan DH, Brown GD, et al (In Press). CD4+ T-cell survival in the GI tract requires dectin-1 during fungal infection.
Mucosal Immunology,
9, 492-502.
Abstract:
CD4+ T-cell survival in the GI tract requires dectin-1 during fungal infection
Dectin-1 is an innate antifungal C-type lectin receptor necessary for protective antifungal immunity. We recently discovered that Dectin-1 is involved in controlling fungal infections of the gastrointestinal (GI) tract, but how this C-type lectin receptor mediates these activities is unknown. Here, we show that Dectin-1 is essential for driving fungal-specific CD4+ T-cell responses in the GI tract. Loss of Dectin-1 resulted in abrogated dendritic cell responses in the mesenteric lymph nodes (mLNs) and defective T-cell co-stimulation, causing substantial increases in CD4+ T-cell apoptosis and reductions in the cellularity of GI-associated lymphoid tissues. CD8+ T-cell responses were unaffected by Dectin-1 deficiency. These functions of Dectin-1 have significant implications for our understanding of intestinal immunity and susceptibility to fungal infections.
Abstract.
Huang J-H, Lin C-Y, Wu S-Y, Chen W-Y, Chu C-L, Brown GD, Chuu C-P, Wu-Hsieh BA (In Press). CR3 and Dectin-1 Collaborate in Macrophage Cytokine Response through Association on Lipid Rafts and Activation of Syk-JNK-AP-1 Pathway.
PLoS Pathogens,
11Abstract:
CR3 and Dectin-1 Collaborate in Macrophage Cytokine Response through Association on Lipid Rafts and Activation of Syk-JNK-AP-1 Pathway
Collaboration between heterogeneous pattern recognition receptors (PRRs) leading to synergistic coordination of immune response is important for the host to fight against invading pathogens. Although complement receptor 3 (CR3) and Dectin-1 are major PRRs to detect fungi, crosstalk between these two receptors in antifungal immunity is largely undefined. Here we took advantage of Histoplasma capsulatum which is known to interact with both CR3 and Dectin-1 and specific particulate ligands to study the collaboration of CR3 and Dectin-1 in macrophage cytokine response. By employing Micro-Western Array (MWA), genetic approach, and pharmacological inhibitors, we demonstrated that CR3 and Dectin-1 act collaboratively to trigger macrophage TNF and IL-6 response through signaling integration at Syk kinase, allowing subsequent enhanced activation of Syk-JNK-AP-1 pathway. Upon engagement, CR3 and Dectin-1 colocalize and form clusters on lipid raft microdomains which serve as a platform facilitating their cooperation in signaling activation and cytokine production. Furthermore, in vivo studies showed that CR3 and Dectin-1 cooperatively participate in host defense against disseminated histoplasmosis and instruct adaptive immune response. Taken together, our findings define the mechanism of receptor crosstalk between CR3 and Dectin-1 and demonstrate the importance of their collaboration in host defense against fungal infection.
Abstract.
Hatinguais R, Leaves I, Brown GD, Brown AJP, Brock M, da Silva RP (In Press). CRISPR-based tools for genetic manipulation in pathogenic<i>Sporothrix</i>species.
Abstract:
CRISPR-based tools for genetic manipulation in pathogenicSporothrixspecies
SummarySporothrix brasiliensisis an emerging fungal pathogen frequently associated with zoonotic transmission of sporotrichosis. Although certain virulence factors have been proposed as potential sporotrichosis determinants, the scarcity of molecular tools for reverse genetics studies onSporothrixhas significantly impeded the dissection of mechanisms underlying the disease. Here, we demonstrate that PEG-mediated protoplast transformation is a powerful method for heterologous expression inS. brasiliensis, S. schenckiiandS. chilensis. Combined with CRISPR/Cas9 gene editing, this transformation protocol allowed the deletion of the putative DHN-melanin synthase genepks1, which is a proposed virulence factor ofSporothrixspecies. To improve in locus integration of deletion constructs, we deleted the KU80homologue that is critical for non-homologous end-joining DNA repair. The use ofS. brasiliensisΔku80strains enhanced homologous-directed repair during transformation resulting in increased targeted gene deletion. In conclusion, our CRISPR/Cas9-based transformation protocol provides an efficient tool for targeted gene manipulation inSporothrixspecies.
Abstract.
Lim J, Coates CJ, Denicola PS, Garelnabi M, Smith LM, Monteith P, Macleod CL, Escaron C, Brown GD, Hall RA, et al (In Press). Characterizing the Mechanisms of Nonopsonic Uptake of Cryptococci by Macrophages.
The Journal of Immunology,
200, 3539-3546.
Abstract:
Characterizing the Mechanisms of Nonopsonic Uptake of Cryptococci by Macrophages
The pathogenic fungus Cryptococcus enters the human host via inhalation into the lung and is able to reside in a niche environment that is serum- (opsonin) limiting. Little is known about the mechanism by which nonopsonic phagocytosis occurs via phagocytes in such situations. Using a combination of soluble inhibitors of phagocytic receptors and macrophages derived from knockout mice and human volunteers, we show that uptake of nonopsonized Cryptococcus neoformans and C. gattii via the mannose receptor is dependent on macrophage activation by cytokines. However, although uptake of C. neoformans is via both dectin-1 and dectin-2, C. gattii uptake occurs largely via dectin-1. Interestingly, dectin inhibitors also blocked phagocytosis of unopsonized Cryptococci in wax moth (Galleria mellonella) larvae and partially protected the larvae from infection by both fungi, supporting a key role for host phagocytes in augmenting early disease establishment. Finally, we demonstrated that internalization of nonopsonized Cryptococci is not accompanied by the nuclear translocation of NF-κB or its concomitant production of proinflammatory cytokines such as TNF-α. Thus, nonopsonized Cryptococci are recognized by mammalian phagocytes in a manner that minimizes proinflammatory cytokine production and potentially facilitates fungal pathogenesis.
Abstract.
Wagener J, Malireddi RKS, Lenardon MD, Koeberle M, Vautier S, MacCallum DM, Biedermann T, Schaller M, Netea MG, Kanneganti T-D, et al (In Press). Chitin recognition in fungal infections and its impact on the immune response. Mycoses, 56, 7-7.
Castoldi A, Andrade-Oliveira V, Aguiar CF, Amano MT, Lee J, Miyagi MT, Latância MT, Braga TT, da Silva MB, Ignácio A, et al (In Press). Dectin-1 Activation Exacerbates Obesity and Insulin Resistance in the Absence of MyD88.
Cell Reports,
19, 2272-2288.
Abstract:
Dectin-1 Activation Exacerbates Obesity and Insulin Resistance in the Absence of MyD88
Highlights•MyD88 absence upregulates Dectin-1 in adipose tissue (AT) and AT macrophages (ATMs)•Dectin-1 inhibition decreases CD11c+ ATMs and protects mice from insulin resistance (IR)•Dectin-1 activation increases CD11c+ ATMs and worsens IR•Obese humans have increased Dectin-1 expression in ATSummaryThe underlying mechanism by which MyD88 regulates the development of obesity, metainflammation, and insulin resistance (IR) remains unknown. Global deletion of MyD88 in high-fat diet (HFD)-fed mice resulted in increased weight gain, impaired glucose homeostasis, elevated Dectin-1 expression in adipose tissue (AT), and proinflammatory CD11c+ AT macrophages (ATMs). Dectin-1 KO mice were protected from diet-induced obesity (DIO) and IR and had reduced CD11c+ AT macrophages. Dectin-1 antagonist improved glucose homeostasis and decreased CD11c+ AT macrophages in chow- and HFD-fed MyD88 KO mice. Dectin-1 agonist worsened glucose homeostasis in MyD88 KO mice. Dectin-1 expression is increased in AT from obese individuals. Together, our data indicate that Dectin-1 regulates AT inflammation by promoting CD11c+ AT macrophages in the absence of MyD88 and identify a role for Dectin-1 in chronic inflammatory states, such as obesity. This suggests that Dectin-1 may have therapeutic implications as a biomarker for metabolic dysregulation in humans.
Abstract.
Rochereau N, Drocourt D, Perouzel E, Pavot V, Redelinghuys P, Brown GD, Tiraby G, Roblin X, Verrier B, Genin C, et al (In Press). Dectin-1 is Essential for Reverse Transcytosis of Glycosylated SIgA-Antigen Complexes by Intestinal M Cells.
PLoS Biology,
11, 1-18.
Abstract:
Dectin-1 is Essential for Reverse Transcytosis of Glycosylated SIgA-Antigen Complexes by Intestinal M Cells
Intestinal microfold (M) cells possess a high transcytosis capacity and are able to transport a broad range of materials including particulate antigens, soluble macromolecules, and pathogens from the intestinal lumen to inductive sites of the mucosal immune system. M cells are also the primary pathway for delivery of secretory IgA (SIgA) to the gut-associated lymphoid tissue. However, although the consequences of SIgA uptake by M cells are now well known and described, the mechanisms whereby SIgA is selectively bound and taken up remain poorly understood. Here we first demonstrate that both the Cα1 region and glycosylation, more particularly sialic acid residues, are involved in M cell-mediated reverse transcytosis. Second, we found that SIgA is taken up by M cells via the Dectin-1 receptor, with the possible involvement of Siglec-5 acting as a co-receptor. Third, we establish that transcytosed SIgA is taken up by mucosal CX3CR1+ dendritic cells (DCs) via the DC-SIGN receptor. Fourth, we show that mucosal and systemic antibody responses against the HIV p24-SIgA complexes administered orally is strictly dependent on the expression of Dectin-1. Having deciphered the mechanisms leading to specific targeting of SIgA-based Ag complexes paves the way to the use of such a vehicle for mucosal vaccination against various infectious diseases.
Abstract.
Zimara N, Chanyalew M, Aseffa A, van Zandbergen G, Lepenies B, Schmid M, Weiss R, Rascle A, Wege AK, Brown GD, et al (In Press). Dectin-1 Positive Dendritic Cells Expand after Infection with Leishmania major Parasites and Represent Promising Targets for Vaccine Development.
Frontiers in Immunology,
9Abstract:
Dectin-1 Positive Dendritic Cells Expand after Infection with Leishmania major Parasites and Represent Promising Targets for Vaccine Development
Resistant mouse strains mount a protective T cell-mediated immune response upon infection with Leishmania (L.) parasites. Healing correlates with a T helper (Th) cell-type 1 response characterized by a pronounced IFN-γ production, while susceptibility is associated with an IL-4-dependent Th2-type response. It has been shown that dermal dendritic cells are crucial for inducing protective Th1-mediated immunity. Additionally, there is growing evidence that C-type lectin receptor (CLR)-mediated signaling is involved in directing adaptive immunity against pathogens. However, little is known about the function of the CLR Dectin-1 in modulating Th1- or Th2-type immune responses by DC subsets in leishmaniasis. We characterized the expression of Dectin-1 on CD11c+ DCs in peripheral blood, at the site of infection, and skin-draining lymph nodes of L. major-infected C57BL/6 and BALB/c mice and in peripheral blood of patients suffering from cutaneous leishmaniasis (CL). Both mouse strains responded with an expansion of Dectin-1+ DCs within the analyzed tissues. In accordance with the experimental model, Dectin-1+ DCs expanded as well in the peripheral blood of CL patients. To study the role of Dectin-1+ DCs in adaptive immunity against L. major, we analyzed the T cell stimulating potential of bone marrow-derived dendritic cells (BMDCs) in the presence of the Dectin-1 agonist Curdlan. These experiments revealed that Curdlan induces the maturation of BMDCs and the expansion of Leishmania-specific CD4+ T cells. Based on these findings, we evaluated the impact of Curdlan/Dectin-1 interactions in experimental leishmaniasis and were able to demonstrate that the presence of Curdlan at the site of infection modulates the course of disease in BALB/c mice: wild-type BALB/c mice treated intradermally with Curdlan developed a protective immune response against L. major whereas Dectin-1−/− BALB/c mice still developed the fatal course of disease after Curdlan treatment. Furthermore, the vaccination of BALB/c mice with a combination of soluble L. major antigens and Curdlan was able to provide a partial protection from severe leishmaniasis. These findings indicate that the ligation of Dectin-1 on DCs acts as an important checkpoint in adaptive immunity against L. major and should therefore be considered in future whole-organism vaccination strategies.
Abstract.
Elcombe SE, Naqvi S, Van Den Bosch MWM, Mackenzie KF, Cianfanelli F, Brown GD, Arthur JSC (In Press). Dectin-1 regulates IL-10 production via a MSK1/2 and CREB dependent pathway and promotes the induction of regulatory macrophage markers.
PloS ONE,
8Abstract:
Dectin-1 regulates IL-10 production via a MSK1/2 and CREB dependent pathway and promotes the induction of regulatory macrophage markers
In response to infection by fungal pathogens, the innate immune system recognises specific fungal pathogen associated molecular patterns (PAMPs) via pattern recognition receptors including the C-type lectin dectin-1 and members of the Toll like Receptor (TLR) family. Stimulation of these receptors leads to the induction of both pro- and anti-inflammatory cytokines. The protein kinases MSK1 and 2 are known to be important in limiting inflammatory cytokine production by macrophages in response to the TLR4 agonist LPS. In this study we show that MSKs are also activated in macrophages by the fungal derived ligand zymosan, as well as the dectin-1 specific agonists curdlan and depleted zymosan, via the ERK1/2 and p38a MAPK pathways. Furthermore, we show that MSKs regulate dectin-1 induced IL-10 production, and that this regulation is dependent on the ability of MSKs to phosphorylate the transcription factor CREB. IL-10 secreted in response to zymosan was able to promote STAT3 phosphorylation via an autocrine feedback loop. Consistent with the decreased IL-10 secretion in MSK1/2 knockout macrophages, these cells also had decreased STAT3 tyrosine phosphorylation relative to wild type controls after stimulation with zymosan. We further show that the reduction in IL-10 production in the MSK1/2 macrophages results in increased secretion of IL-12p40 in response to zymosan relative to wild type controls. The production of high levels of IL-10 but low levels of IL-12 has previously been associated with an M2b or ’regulatory’ macrophage phenotype, which was initially described in macrophages stimulated with a combination of immune complexes and LPS. We found that zymosan, via dectin-1 activation, also leads to the expression of SphK1 and LIGHT, markers of a regulatory like phenotype in mouse macrophages. The expression of these makers was further reinforced by the high level of IL-10 secreted in response to zymosan stimulation.
Abstract.
Willment JA, Brown GD (In Press). Dectin-1: Basis Sequence - Mouse.
Abstract:
Dectin-1: Basis Sequence - Mouse
The predominantly myeloid cell–expressed C-type lectin-like receptor dectin-1 is a pattern-recognition receptor that recognizes ß1,3-linked glucans found in fungi, plants and some bacteria, as well as an unidentified ligand on Mycobacteria sp. There is a further uncharacterized endogenous ligand on T lymphocytes and apoptotic cells. Dectin-1 is a type II transmembrane-spanning molecule with a cytoplasmic tail, containing a nonclassical immunoreceptor tyrosine activation-like (ITAM-like) motif, and a single extracellular carbohydrate recognition domain. Two major isoforms exist—dectin-1A and dectin-1B—the difference being the presence or absence, respectively, of a stalk region that separates the carbohydrate recognition domain from the transmembrane domain. The mouse dectin-1 expression profile is restricted to myeloid cells and subsets of T lymphocytes, whereas the human homolog is also expressed on B lymphocytes and eosinophils. Expression levels are modulated by a variety of cytokines and other immune response modifiers, and isoform expression profiles differ according to cell type and mouse genetic background. Interaction of dectin-1 with its exogenous ligand results in the triggering, through its cytoplasmic ITAM-like motif, of respiratory burst, phagocytosis, production of various cytokines and chemokines, arachidonate metabolism, and dendritic cell maturation. Dectin-1 is able to function independently, as well as collaboratively with the Toll-like receptors, to modulate immune responses. Dectin-1 mediates signaling through spleen tyrosine kinase, Raf-1 kinase and other undefined pathways. The generation of a dectin-1 knockout mouse has indicated a role for this receptor in the recognition and control of fungal pathogens, although the full extent of its importance in antifungal immunity is unclear. Triggering of dectin-1 on dendritic cells can induce strong CD4+ and CD8+ T-cell responses and skew the adaptive response toward T-helper type 1 and type 17 profiles. Dectin-1 therefore functions as a classical pattern-recognition receptor and is able to link the innate and adaptive immune responses.
Abstract.
Whibley N, Jaycox JR, Reid D, Garg AV, Taylor JA, Clancy CJ, Nguyen MH, Biswas PS, McGeachy MJ, Brown GD, et al (In Press). Delinking CARD9 and IL-17: Protects against Candida tropicalis Infection through a TNF-α–Dependent, IL-17–Independent Mechanism.
The Journal of Immunology,
195, 3781-3792.
Abstract:
Delinking CARD9 and IL-17: Protects against Candida tropicalis Infection through a TNF-α–Dependent, IL-17–Independent Mechanism
Candida is the third most common cause of bloodstream infections in hospitalized patients. Immunity to C. albicans, the most frequent species to be isolated in candidiasis, involves a well-characterized Dectin-1/caspase-associated recruitment domain adaptor 9 (CARD9)/IL-17 signaling axis. Infections caused by non-albicans Candida species are on the rise, but surprisingly little is known about immunity to these pathogens. In this study, we evaluated a systemic infection model of C. tropicalis, a clinically relevant, but poorly understood, non-albicans Candida. Mice lacking CARD9 were profoundly susceptible to C. tropicalis, displaying elevated fungal burdens in visceral organs and increased mortality compared with wild-type (WT) controls. Unlike C. albicans, IL-17 responses were induced normally in CARD9(-/-) mice following C. tropicalis infection. Moreover, there was no difference in susceptibility to C. tropicalis infection between WT and IL-23p19(-/-), IL-17RA(-/-), or Act1(-/-) mice. However, TNF-α expression was markedly impaired in CARD9(-/-) mice. Consistently, WT mice depleted of TNF-α were more susceptible to C. tropicalis, and CARD9-deficient neutrophils and monocytes failed to produce TNF-α following stimulation with C. tropicalis Ags. Both neutrophils and monocytes were necessary for defense against C. tropicalis, because their depletion in WT mice enhanced susceptibility to C. tropicalis. Disease in CARD9(-/-) mice was not due to defective neutrophil or monocyte recruitment to infected kidneys. However, TNF-α treatment of neutrophils in vitro enhanced their ability to kill C. tropicalis. Thus, protection against systemic C. tropicalis infection requires CARD9 and TNF-α, but not IL-17, signaling. Moreover, CARD9-dependent production of TNF-α enhances the candidacidal capacity of neutrophils, limiting fungal disease during disseminated C. tropicalis infection.
Abstract.
Berekméri A, Latzko A, Alase A, Macleod T, Ainscough JS, Laws P, Goodfield M, Wright A, Helliwell P, Edward S, et al (In Press). Detection of IL-36γ through noninvasive tape stripping reliably discriminates psoriasis from atopic eczema.
Journal of Allergy and Clinical Immunology,
142, 988-991.
Abstract:
Detection of IL-36γ through noninvasive tape stripping reliably discriminates psoriasis from atopic eczema
This report demonstrates that sampling and detection of IL-36γ protein by non-invasive tape stripping of skin lesion provides a highly sensitive and selective diagnostic for psoriatic inflammation.
Abstract.
McDonald JU, Rosas M, Brown GD, Jones SA, Taylor PR (In Press). Differential dependencies of monocytes and neutrophils on dectin-1, dectin-2 and complement for the recognition of fungal particles in inflammation.
PloS ONE,
7Abstract:
Differential dependencies of monocytes and neutrophils on dectin-1, dectin-2 and complement for the recognition of fungal particles in inflammation
We have re-investigated the role of the complement system and the non-opsonic pattern recognition receptors dectin-1 and dectin-2 in the recognition of fungal particles by inflammatory neutrophils, monocytes and macrophages. We have used in vivo and ex vivo models to study the recognition and response of these cells: i) We confirm previous observations regarding the importance of complement to neutrophil but not monocytic responses; ii) We show that dectin-1 is important for driving inflammatory cell recruitment to fungal stimuli and that it biases the immediate inflammatory response to one that favors neutrophil over monocyte recruitment; iii) We show that dectin-2 contributes to the physical recognition of fungal particles by inflammatory monocytes/macrophages, but is also expressed on neutrophils, where we show it has the potential to contribute to cellular activation; iv) Additionally, we show that serum-opsonization has the potential to interfere with non-opsonic recognition of fungal particles by dectin-1 and dectin-2, presumably through masking of ligands. Collectively these roles are consistent with previously described roles of dectin-1 and dectin-2 in driving inflammatory and adaptive immune responses and complement in containing fungal burdens. This study emphasizes the importance of heterogeneity of receptor expression across myeloid cell subsets in protective immune responses.
Abstract.
uthrich MW, Wang H, Li M, Lerksuthirat T, Hardison SE, Brown GD, Klein B (In Press). Fonsecaea pedrosoi-induced Th17-cell differentiation in mice is fostered by Dectin-2 and suppressed by Mincle recognition.
European Journal of Immunology,
45, 2542-2552.
Abstract:
Fonsecaea pedrosoi-induced Th17-cell differentiation in mice is fostered by Dectin-2 and suppressed by Mincle recognition
Chromoblastomycosis is a chronic skin infection caused by the pigmented saprophytic mould Fonsecaea pedrosoi. Chronicity of infection can be broken by a coordinated innate recognition of the spores by pattern recognition receptors. While Mincle signaling via the Syk/Card9 pathway is required for fungal recognition by host cells, it is not sufficient for host control. Exogenously applied TLR agonists are necessary to promote the induction of proinflammatory cytokines and clearance of infection in vivo. Here, we investigated whether costimulation by TLR agonists fosters the development of adaptive immune responses, by examining the development of fungus-specific T cells. Subcutaneous infection of mice with F. pedrosoi spores induced the activation, expansion, and differentiation of Ag-specific CD4(+) T cells but TLR costimulation did not further augment these T-cell responses. The Dectin-2/FcRγ/Card9 signaling pathway promoted the differentiation of fungus-specific CD4(+) T cells into Th17 cells, whereas Mincle inhibited the development of this T-helper subset in infected mice. These results indicate differential roles for Dectin-2 and Mincle in the generation of adaptive immune responses to F. pedrosoi infection.
Abstract.
Dambuza IM, Levitz SM, Netea MG, Brown GD (In Press). Fungal Recognition and Host Defense Mechanisms.
Microbiology spectrum,
5, 1-16.
Abstract:
Fungal Recognition and Host Defense Mechanisms
Fungi have emerged as premier opportunistic microbes of the 21st century, having a considerable impact on human morbidity and mortality. The huge increase in incidence of these diseases is largely due to the HIV pandemic and use of immunosuppressive therapies, underscoring the importance of the immune system in defense against fungi. This article will address how the mammalian immune system recognizes and mounts a defense against medically relevant fungal species.
Abstract.
Brown BR, Lee EJ, Snow PE, Vance EE, Iwakura Y, Ohno N, Miura N, Lin X, Brown GD, Wells CA, et al (In Press). Fungal-derived cues promote ocular autoimmunity through a Dectin-2/Card9-mediated mechanism.
Clinical and Experimental Immunology,
190, 293-303.
Abstract:
Fungal-derived cues promote ocular autoimmunity through a Dectin-2/Card9-mediated mechanism
Uveitis (intraocular inflammation) is a leading cause of vision loss. Although its etiology is largely speculative, it is thought to arise from complex genetic-environmental interactions that break immune tolerance to generate eye-specific autoreactive T cells. Experimental autoimmune uveitis (EAU), induced by immunization with the ocular antigen, interphotoceptor retinoid binding protein (IRBP), in combination with mycobacteria-containing CFA, has many clinical and histopathological features of human posterior uveitis. Studies in EAU have focused on defining pathogenic CD4+ T cell effector responses, such as those of Th17 cells, but the innate receptor pathways precipitating development of autoreactive, eye-specific T cells remain poorly defined. In this study, we found that fungal-derived antigens possess autoimmune uveitis-promoting function akin to CFA in conventional EAU. The capacity of commensal fungi such as C. albicans or S. cerevisae to promote IRBP-triggered EAU was mediated by Card9. Since Card9 is an essential signaling molecule of a subgroup of C-type lectin receptors (CLRs) important in host defense, we further evaluated the proximal Card9-activating CLRs. Using single receptor-deficient mice, we identified Dectin-2, but not Mincle or Dectin-1, as a predominant mediator of fungal-promoted uveitis. Conversely, Dectin-2 activation by α-mannan sufficiently reproduced the uveitic phenotype of EAU, in a process mediated by the Card9- coupled signaling axis and IL-17 production. Taken together, this report relates the potential of the Dectin-2/Card9-coupled pathway in ocular autoimmunity. Not only does it contribute to understanding of how innate immune receptors orchestrate T cell-mediated autoimmunity, it also reveals a previously unappreciated ability of fungal-derived signals to promote autoimmunity.
Abstract.
Brown GD, May RC (In Press). Host-Microbe Interactions: Fungi. Current Opinion in Microbiology, 40, v-vii.
Gow NAR, Netea MG, Munro CA, Ferwerda G, Bates S, Mora-Montes HM, Walker L, Jansen T, Jacobs L, Tsoni V, et al (In Press). Immune Recognition of Candida albicans ß-glucan by Dectin-1.
The journal of infectious diseases,
196, 1565-1571.
Abstract:
Immune Recognition of Candida albicans ß-glucan by Dectin-1
Beta (1,3)-glucans represent 40% of the cell wall of the yeast Candida albicans. The dectin-1 lectin-like receptor has shown to recognize fungal beta (1,3)-glucans and induce innate immune responses. The importance of beta-glucan-dectin-1 pathways for the recognition of C. albicans by human primary blood cells has not been firmly established. In this study we demonstrate that cytokine production by both human peripheral blood mononuclear cells and murine macrophages is dependent on the recognition of beta-glucans by dectin-1. Heat killing of C. albicans resulted in exposure of beta-glucans on the surface of the cell wall and subsequent recognition by dectin-1, whereas live yeasts stimulated monocytes mainly via recognition of cell-surface mannans. Dectin-1 induced cytokine production through the following 2 pathways: Syk-dependent production of the T-helper (Th) 2-type anti-inflammatory cytokine interleukin-10 and Toll-like receptor-Myd88-dependent stimulation of monocyte-derived proinflammatory cytokines, such as tumor necrosis factor-alpha. In contrast, stimulation of Th1-type cytokines, such as interferon-gamma , by C. albicans was independent of the recognition of beta-glucans by dectin-1. In conclusion, C. albicans induces production of monocyte-derived and T cell-derived cytokines through distinct pathways dependent on or independent of dectin-1.
Abstract.
Hebecker B, Reid DM, Brown GD (In Press). Immunity to Trichophyton rubrum in a mouse skin infection model involves the recruitment of neutrophils. Mycoses, 61, 16-17.
Bidula S, Brown GD (In Press). Immunology of Fungal Infections. In Ratcliffe M (Ed)
Immunity to Pathogens and Tumors, Elsevier Inc. 75-82.
Abstract:
Immunology of Fungal Infections
Abstract.
Dambuza IM, Wagener J, Brown GD, Gow NAR (In Press). Immunology of fungal disease. In Kibbler CC, Barton R, Gow NAR, Howell S, MacCallum DM, Manuel RJ (Eds.)
Oxford Textbook of Medical Mycology, Oxford University Press.
Abstract:
Immunology of fungal disease
Abstract.
Armstrong-James D, Brown GD, Netea MG, Zelante T, Gresnigt MS, van de Veerdonk FL, Levitz SM (In Press). Immunotherapeutic approaches to treatment of fungal diseases.
Lancet Infectious Diseases,
17, 393-402.
Abstract:
Immunotherapeutic approaches to treatment of fungal diseases
Fungal infections cause morbidity worldwide and are associated with an unacceptably high mortality despite the availability of antifungal drugs. The incidence of mycoses is rising because of the HIV pandemic and because immunomodulatory drugs are increasingly used to treat autoimmune diseases and cancer. New classes of antifungal drugs have only been partly successful in improving the prognosis for patients with fungal infection. Adjunctive host-directed therapy is therefore believed to be the only option to further improve patient outcomes. Recent advances in the understanding of complex interactions between fungi and host have led to the design and exploration of novel therapeutic strategies in cytokine therapy, vaccines, and cellular immunotherapy, each of which might become viable adjuncts to existing antifungal regimens. In this report, we discuss immunotherapeutic approaches—the rationale behind their design, the challenges in their use, and the progress that is so urgently needed to overcome the devastating effect of fungal diseases.
Abstract.
Drummond RA, Gaffen SL, Hise AG, Brown GD (In Press). Innate defense against fungal pathogens.
Cold Spring Harbor perspectives in medicine,
5Abstract:
Innate defense against fungal pathogens
Human fungal infections have been on the rise in recent years and proved increasingly difficult to treat as a result of the lack of diagnostics, effective antifungal therapies, and vaccines. Most pathogenic fungi do not cause disease unless there is a disturbance in immune homeostasis, which can be caused by modern medical interventions, disease-induced immunosuppression, and naturally occurring human mutations. The innate immune system is well equipped to recognize and destroy pathogenic fungi through specialized cells expressing a broad range of pattern recognition receptors (PRRs). This review will outline the cells and PRRs required for effective antifungal immunity, with a special focus on the major antifungal cytokine IL-17 and recently characterized antifungal inflammasomes.
Abstract.
Begun J, Lassen KG, Jijon HB, Baxt LA, Goel G, Heath RJ, Ng A, Tam JM, Kuo S-Y, Villablanca EJ, et al (In Press). Integrated Genomics of Crohn’s Disease Risk Variant Identifies a Role for CLEC12A in Antibacterial Autophagy.
Cell Reports,
11, 1905-1918.
Abstract:
Integrated Genomics of Crohn’s Disease Risk Variant Identifies a Role for CLEC12A in Antibacterial Autophagy
The polymorphism ATG16L1 T300A, associated with increased risk of Crohn’s disease, impairs pathogen defense mechanisms including selective autophagy, but specific pathway interactions altered by the risk allele remain unknown. Here, we use perturbational profiling of human peripheral blood cells to reveal that CLEC12A is regulated in an ATG16L1-T300A-dependent manner. Antibacterial autophagy is impaired in CLEC12A-deficient cells, and this effect is exacerbated in the presence of the ATG16L1(∗)300A risk allele. Clec12a(-/-) mice are more susceptible to Salmonella infection, supporting a role for CLEC12A in antibacterial defense pathways in vivo. CLEC12A is recruited to sites of bacterial entry, bacteria-autophagosome complexes, and sites of sterile membrane damage. Integrated genomics identified a functional interaction between CLEC12A and an E3-ubiquitin ligase complex that functions in antibacterial autophagy. These data identify CLEC12A as early adaptor molecule for antibacterial autophagy and highlight perturbational profiling as a method to elucidate defense pathways in complex genetic disease.
Abstract.
Yang A-M, Inamine T, Hochrath K, Chen P, Wang L, Llorente C, Bluemel S, Hartmann P, Xu J, Koyama Y, et al (In Press). Intestinal fungi contribute to development of alcoholic liver disease.
The Journal of Clinical Investigation,
127, 2829-2841.
Abstract:
Intestinal fungi contribute to development of alcoholic liver disease
Chronic liver disease with cirrhosis is the 12th leading cause of death in the United States, and alcoholic liver disease accounts for approximately half of all cirrhosis deaths. Chronic alcohol consumption is associated with intestinal bacterial dysbiosis, yet we understand little about the contribution of intestinal fungi, or mycobiota, to alcoholic liver disease. Here we have demonstrated that chronic alcohol administration increases mycobiota populations and translocation of fungal β-glucan into systemic circulation in mice. Treating mice with antifungal agents reduced intestinal fungal overgrowth, decreased β-glucan translocation, and ameliorated ethanol-induced liver disease. Using bone marrow chimeric mice, we found that β-glucan induces liver inflammation via the C-type lectin–like receptor CLEC7A on Kupffer cells and possibly other bone marrow–derived cells. Subsequent increases in IL-1β expression and secretion contributed to hepatocyte damage and promoted development of ethanol-induced liver disease. We observed that alcohol-dependent patients displayed reduced intestinal fungal diversity and Candida overgrowth. Compared with healthy individuals and patients with non–alcohol-related cirrhosis, alcoholic cirrhosis patients had increased systemic exposure and immune response to mycobiota. Moreover, the levels of extraintestinal exposure and immune response correlated with mortality. Thus, chronic alcohol consumption is associated with an altered mycobiota and translocation of fungal products. Manipulating the intestinal mycobiome might be an effective strategy for attenuating alcohol-related liver disease.
Abstract.
Brown GD, Crocker PR (In Press). Lectin Receptors Expressed on Myeloid Cells.
Microbiology spectrum,
4Abstract:
Lectin Receptors Expressed on Myeloid Cells
Lectins recognize a diverse array of carbohydrate structures and perform numerous essential biological functions. Here we focus on only two families of lectins, the Siglecs and C-type lectins. Triggering of intracellular signaling cascades following ligand recognition by these receptors can have profound effects on the induction and modulation of immunity. In this chapter, we provide a brief overview of each family and then focus on selected examples that highlight how these lectins can influence myeloid cell functioning in health and disease. Receptors that are discussed include Sn (Siglec-1), CD33 (Siglec-3), and Siglec-5, -7, -8, -9, -10, -11, -14, -15, -E, -F, and -G as well as Dectin-1, MICL, Dectin-2, Mincle/MCL, and the macrophage mannose receptor.
Abstract.
Ozment-Skelton TR, deFluiter EA, Ha T, Li C, Graves BM, Ferguson DA, Schweitzer JB, Preizsner J, Brown GD, Gordon S, et al (In Press). Leukocyte Dectin-1 expression is differentially regulated in fungal versus polymicrobial sepsis.
Critical Care Medicine,
37, 1038-1045.
Abstract:
Leukocyte Dectin-1 expression is differentially regulated in fungal versus polymicrobial sepsis
OBJECTIVE: to examine peripheral leukocyte Dectin-1 regulation in clinically relevant models of fungal and polymicrobial sepsis. DESIGN: Prospective animal study. SETTING: University medical school research laboratory. SUBJECTS: Age, weight, and sex matched ICR/HSD mice. INTERVENTIONS: Mice were infected with Candida albicans (1 x 10, intravenously) or were subjected to cecal ligation and puncture to induce polymicrobial sepsis. MEASUREMENTS: Blood, spleen, and peritoneal exudate were harvested and leukocytes were isolated. Leukocytes were evaluated for membrane-associated Dectin-1 expression and cell phenotype by flow cytometry. MAIN RESULTS: in C. albicans infection, Dectin-1-positive blood and splenic leukocytes were increased from 23.5% to 58.9% over the course of infection. The increased percentage of Dectin-1-expressing cells was primarily attributable to neutrophilia. However, the amount of Dectin-1 expressed by blood and splenic neutrophils in C. albicans-infected mice was decreased by a range of 49.0% to 53.3%. C. albicans infection also resulted in an infiltration of Dectin-1-positive macrophages and neutrophils into the kidney. In contrast, polymicrobial sepsis decreased blood leukocyte Dectin-1-expressing cells by up to 51.4%. This reduction was due to a decrease in Dectin-1-positive neutrophils in the periphery. However, the percentage of Dectin-1-expressing cells in the peritoneal cavity increased by 774% with cecal ligation and puncture. Treatment of isolated neutrophils with three soluble glucans, mannan, lipopolysaccharide, or a variety of cytokines revealed that glucans, alone or in combination, were the only treatment that resulted in a decrease in Dectin-1-positive neutrophils. CONCLUSIONS: We conclude that peripheral leukocyte Dectin-1 expression is differentially regulated in fungal vs. polymicrobial sepsis. These data demonstrate that leukocyte Dectin-1 levels are modulated in response to infections of fungal and nonfungal origin.
Abstract.
Hadebe S, Kirstein F, Fierens K, Chen K, Drummond RA, Vautier S, Sajaniemi S, Murray G, Williams DL, Redelinghuys P, et al (In Press). Microbial ligand costimulation drives neutrophilic steroid-refractory asthma.
PloS ONE,
10Abstract:
Microbial ligand costimulation drives neutrophilic steroid-refractory asthma
Asthma is a heterogeneous disease whose etiology is poorly understood but is likely to involve innate responses to inhaled microbial components that are found in allergens. The influence of these components on pulmonary inflammation has been largely studied in the context of individual agonists, despite knowledge that they can have synergistic effects when used in combination. Here we have explored the effects of LPS and β-glucan, two commonly-encountered microbial agonists, on the pathogenesis of allergic and non-allergic respiratory responses to house dust mite allergen. Notably, sensitization with these microbial components in combination acted synergistically to promote robust neutrophilic inflammation, which involved both Dectin-1 and TLR-4. This pulmonary neutrophilic inflammation was corticosteroid-refractory, resembling that found in patients with severe asthma. Thus our results provide key new insights into how microbial components influence the development of respiratory pathology.
Abstract.
Martínez-López M, Iborra S, Conde-Garrosa R, Mastrangelo A, Danne C, Mann ER, Reid DM, Gaboriau-Routhiau V, Chaparro M, Lorenzo MP, et al (In Press). Microbiota Sensing by Mincle-Syk Axis in Dendritic Cells Regulates Interleukin-17 and -22 Production and Promotes Intestinal Barrier Integrity.
Immunity,
50, 446-461.
Abstract:
Microbiota Sensing by Mincle-Syk Axis in Dendritic Cells Regulates Interleukin-17 and -22 Production and Promotes Intestinal Barrier Integrity
Production of interleukin-17 (IL-17) and IL-22 by T helper 17 (Th17) cells and group 3 innate lymphoid cells (ILC3s) in response to the gut microbiota ensures maintenance of intestinal barrier function. Here, we examined the mechanisms whereby the immune system detects microbiota in the steady state. A Syk-kinase-coupled signaling pathway in dendritic cells (DCs) was critical for commensal-dependent production of IL-17 and IL-22 by CD4+ T cells. The Syk-coupled C-type lectin receptor Mincle detected mucosal-resident commensals in the Peyer’s patches (PPs), triggered IL-6 and IL-23p19 expression, and thereby regulated function of intestinal Th17- and IL-17-secreting ILCs. Mice deficient in Mincle or with selective depletion of Syk in CD11c+ cells had impaired production of intestinal RegIIIγ and IgA and increased systemic translocation of gut microbiota. Consequently, Mincle deficiency led to liver inflammation and deregulated lipid metabolism. Thus, sensing of commensals by Mincle and Syk signaling in CD11c+ cells reinforces intestinal immune barrier and promotes host-microbiota mutualism, preventing systemic inflammation.
Abstract.
Stoppelkamp S, Reid DM, Yeoh J, Taylor J, McKenzie EJ, Brown GD, Gordon S, Forrester JV, Wong SYC (In Press). Murine pattern recognition receptor dectin-1 is essential in the development of experimental autoimmune uveoretinitis.
Molecular Immunology,
67, 398-406.
Abstract:
Murine pattern recognition receptor dectin-1 is essential in the development of experimental autoimmune uveoretinitis
Mycobacteria in complete Freund’s adjuvant (CFA) are an essential component of immunization protocols in a number of autoimmune disease animal models including experimental autoimmune encephalomyelitis and uveoretinitis (EAE and EAU, respectively). We determined the role in EAU of two C-type lectin receptors on myeloid cells that recognize and respond to mycobacteria. Using receptor-specific antibodies and knockout mice, we demonstrated for the first time that the macrophage mannose receptor delays disease development but does not affect severity. In contrast, dectin-1 is critically involved in the development of CFA-mediated EAU. Disease severity is reduced in dectin-1 knockout mice and antibody blockade of dectin-1 during the induction, but not the effector phase, prevents EAU development. Significantly, similar blockade of dectin-1 in vivo has no effect in non-CFA-mediated, spontaneously induced or adoptive transfer models of EAU. Thus dectin-1 plays a critical role in the ability of complete Freund’s adjuvant to induce EAU in mice.
Abstract.
Alsina-Beauchamp D, Escós A, Fajardo P, González-Romero D, Díaz-Mora E, Risco A, Martín-Serrano MA, Fresno CD, Dominguez-Andrés J, Aparicio N, et al (In Press). Myeloid cell deficiency of p38γ/p38δ protects against candidiasis and regulates antifungal immunity.
EMBO Molecular Medicine,
10Abstract:
Myeloid cell deficiency of p38γ/p38δ protects against candidiasis and regulates antifungal immunity
Candida albicans is a frequent etiologic agent of sepsis associated with high mortality in immunocompromised patients. Developing new antifungal therapies is a medical need due to the low efficiency and resistance to current antifungal drugs. Here, we show that p38J and p38G regulate the innate immune response to C. albicans. We describe a new TAK1-TPL2-MKK1-ERK1/2 pathway in macrophages, which is activated by Dectin-1 engagement and positively regulated by p38J/p38G. In mice, p38J/p38G deficiency protects against C. albicans infection by increasing ROS and iNOS production and thus the antifungal capacity of neutrophils and macrophages, and by decreasing the hyper-inflammation that leads to severe host damage. Leucocyte recruitment to infected kidneys and production of inflammatory mediators are decreased in p38J/G null mice, reducing septic shock. p38J/p38G in myeloid cells are critical for this effect. Moreover, pharmacological inhibition of p38J/p38G in mice reduces fungal burden, revealing that these p38MAPKs may be therapeutic targets for treating C. albicans infection in humans.
Abstract.
Branzk N, Lubojemska A, Hardison SE, Wang Q, Gutierrez MG, Brown GD, Papayannopoulos V (In Press). Neutrophils sense microbe size and selectively release neutrophil extracellular traps in response to large pathogens.
Nature Immunology,
15, 1017-1025.
Abstract:
Neutrophils sense microbe size and selectively release neutrophil extracellular traps in response to large pathogens
Neutrophils are critical for antifungal defense, but the mechanisms that clear hyphae and other pathogens that are too large to be phagocytosed remain unknown. We found that neutrophils sensed microbe size and selectively released neutrophil extracellular traps (NETs) in response to large pathogens, such as Candida albicans hyphae and extracellular aggregates of Mycobacterium bovis, but not in response to small yeast or single bacteria. NETs were fundamental in countering large pathogens in vivo. Phagocytosis via dectin-1 acted as a sensor of microbe size and prevented NET release by downregulating the translocation of neutrophil elastase (NE) to the nucleus. Dectin-1 deficiency led to aberrant NET release and NET-mediated tissue damage during infection. Size-tailored neutrophil responses cleared large microbes and minimized pathology when microbes were small enough to be phagocytosed.
Abstract.
Plato A, Hardison SE, Brown GD (In Press). Pattern recognition receptors in antifungal immunity.
Seminars in Immunopathology,
37, 97-106.
Abstract:
Pattern recognition receptors in antifungal immunity
Receptors of the innate immune system are the first line of defence against infection, being able to recognise and initiate an inflammatory response to invading microorganisms. The Toll-like (TLR), NOD-like (NLR), RIG-I-like (RLR) and C-type lectin-like receptors (CLR) are four receptor families that contribute to the recognition of a vast range of species, including fungi. Many of these pattern recognition receptors (PRRs) are able to initiate innate immunity and polarise adaptive responses upon the recognition of fungal cell wall components and other conserved molecular patterns, including fungal nucleic acids. These receptors induce effective mechanisms of fungal clearance in normal hosts, but medical interventions, immunosuppression or genetic predisposition can lead to susceptibility to fungal infections. In this review, we highlight the importance of PRRs in fungal infection, specifically CLRs, which are the major PRR involved. We will describe specific PRRs in detail, the importance of receptor collaboration in fungal recognition and clearance, and describe how genetic aberrations in PRRs can contribute to disease pathology.
Abstract.
Kerrigan AM, Brown GD (In Press). Phagocytes: fussy about carbs.
Current Biology,
21, R500-R502.
Abstract:
Phagocytes: fussy about carbs
A new mechanistic model based on the formation of a phagocytic synapse explains how immune cells detect and respond to direct contact with fungal pathogens.
Abstract.
Hardison SE, Brown GD (In Press). Receptor-ligand interactions in fungal infections. In Kurzai O (Ed)
Human Fungal Pathogens, Springer, 77-96.
Abstract:
Receptor-ligand interactions in fungal infections
Abstract.
Dambuza IM, Brown GD (In Press). Sensing fungi at the oral epithelium.
Nature Microbiology,
3, 4-5.
Abstract:
Sensing fungi at the oral epithelium
The mechanisms involved in controlling Candida albicans at mucosal sites are not fully understood. Recent work identifies the EphA2 on epithelial cells as a fungal β-glucan receptor that is critical for mediating protective immunity during oral candidiasis.
Abstract.
Heinsbroek SEM, Taylor PR, Martinez FO, Martinez-Pomares L, Brown GD, Gordon S (In Press). Stage-specific sampling by pattern recognition receptors during Candida albicans phagocytosis.
PLoS Pathogens,
4Abstract:
Stage-specific sampling by pattern recognition receptors during Candida albicans phagocytosis
Candida albicans is a medically important pathogen, and recognition by innate immune cells is critical for its clearance. Although a number of pattern recognition receptors have been shown to be involved in recognition and phagocytosis of this fungus, the relative role of these receptors has not been formally examined. In this paper, we have investigated the contribution of the mannose receptor, Dectin-1, and complement receptor 3; and we have demonstrated that Dectin-1 is the main non-opsonic receptor involved in fungal uptake. However, both Dectin-1 and complement receptor 3 were found to accumulate at the site of uptake, while mannose receptor accumulated on C. albicans phagosomes at later stages. These results suggest a potential role for MR in phagosome sampling; and, accordingly, MR deficiency led to a reduction in TNF-alpha and MCP-1 production in response to C. albicans uptake. Our data suggest that pattern recognition receptors sample the fungal phagosome in a sequential fashion.
Abstract.
Jiménez JM, Salazar M, Arancibia S, Villar J, Salazar F, Brown GD, Lavelle EC, Martínez-Pomares L, Ortiz-Quintero J, Lavandero S, et al (In Press). TLR4, but Neither Dectin-1 nor Dectin-2, Participates in the Mollusk Hemocyanin-Induced Proinflammatory Effects in Antigen-Presenting Cells from Mammals.
Frontiers in Immunology,
10Abstract:
TLR4, but Neither Dectin-1 nor Dectin-2, Participates in the Mollusk Hemocyanin-Induced Proinflammatory Effects in Antigen-Presenting Cells from Mammals
Mollusk hemocyanins have biomedical uses as carriers/adjuvants and nonspecific immunostimulants with beneficial clinical outcomes by triggering the production of proinflammatory cytokines in antigen-presenting cells (APCs) and driving immune responses toward type 1 T helper (Th1) polarization. Significant structural features of hemocyanins as a model antigen are their glycosylation patterns. Indeed, hemocyanins have a multivalent nature as highly mannosylated antigens. We have previously shown that hemocyanins are internalized by APCs through receptor-mediated endocytosis with proteins that contain C-type lectin domains, such as mannose receptor (MR). However, the contribution of other innate immune receptors to the proinflammatory signaling pathway triggered by hemocyanins is unknown. Thus, we studied the roles of Dectin-1, Dectin-2, and Toll-like receptor 4 (TLR4) in the hemocyanin activation of murine APCs, both in dendritic cells (DCs) and macrophages, using hemocyanins from Megathura crenulata (KLH), Concholepas concholepas (CCH) and Fissurella latimarginata (FLH). The results showed that these hemocyanins bound to chimeric Dectin-1 and Dectin-2 receptors in vitro; which significantly decreased when the glycoproteins were deglycosylated. However, hemocyanin-induced proinflammatory effects in APCs from Dectin-1 knock-out (KO) and Dectin-2 KO mice were independent of both receptors. Moreover, when wild-type APCs were cultured in the presence of hemocyanins, phosphorylation of Syk kinase was not detected. We further showed that KLH and FLH induced ERK1/2 phosphorylation, a key event involved in the TLR signaling pathway. We confirmed a glycan-dependent binding of hemocyanins to chimeric TLR4 in vitro. Moreover, DCs from mice deficient for MyD88-adapter-like (Mal), a downstream adapter molecule of TLR4, were partially activated by FLH, suggesting a role of the TLR pathway in hemocyanin recognition to activate APCs. The participation of TLR4 was confirmed through a decrease in IL-12p40 and IL-6 secretion induced by FLH when a TLR4 blocking antibody was used; a reduction was also observed in DCs from C3H/HeJ mice, a mouse strain with a nonfunctional mutation for this receptor. Moreover, IL-6 secretion induced by FLH was abolished in macrophages deficient for TLR4. Our data showed the involvement of TLR4 in the hemocyanin-mediated proinflammatory response in APCs, which could cooperate with MR in innate immune recognition of these glycoproteins.
Abstract.
Xiao Y, Tang J, Guo H, Zhao Y, Tang R, Ouyang S, Zeng Q, Rappleye CA, Rajaram MVS, Schlesinger LS, et al (In Press). Targeting CBLB as a potential therapeutic approach for disseminated candidiasis.
Nature Medicine,
22, 906-914.
Abstract:
Targeting CBLB as a potential therapeutic approach for disseminated candidiasis
Disseminated candidiasis has become one of the leading causes of hospital-acquired blood stream infections with high mobility and mortality. However, the molecular basis of host defense against disseminated candidiasis remains elusive, and treatment options are limited. Here we report that the E3 ubiquitin ligase CBLB directs polyubiquitination of dectin-1 and dectin-2, two key pattern-recognition receptors for sensing Candida albicans, and their downstream kinase SYK, thus inhibiting dectin-1- and dectin-2-mediated innate immune responses. CBLB deficiency or inactivation protects mice from systemic infection with a lethal dose of C. albicans, and deficiency of dectin-1, dectin-2, or both in Cblb(-/-) mice abrogates this protection. Notably, silencing the Cblb gene in vivo protects mice from lethal systemic C. albicans infection. Our data reveal that CBLB is crucial for homeostatic control of innate immune responses mediated by dectin-1 and dectin-2. Our data also indicate that CBLB represents a potential therapeutic target for protection from disseminated candidiasis.
Abstract.
Toft-Petersen M, Stidsholt Roug A, Plesner T, Ebbesen L, Brown GD, Nederby L (In Press). The CLEC12A receptor marks human basophils: Potential implications for minimal residual disease detection in acute myeloid leukemia.
Cytometry Part B: Clinical Cytometry,
94, 520-526.
Abstract:
The CLEC12A receptor marks human basophils: Potential implications for minimal residual disease detection in acute myeloid leukemia
Background: the transmembrane receptor C-type lectin domain family 12, member a (CLEC12A) is known to be highly expressed on monocytes and neutrophils and is a reliable leukemia associated marker in acute myeloid leukemia. Consequently, detailed knowledge of the various normal cell types expressing this receptor is essential. We have observed CLEC12A to be expressed on CD45lowSSClowCD14-CD123+ basophils in peripheral blood (PB) and in the present study, we aimed at verifying this observation and further delineate the CD45lowSSClowCD14-CD123+CLEC12A+ subpopulation.Methods: We analyzed PB from 20 diagnostic chronic myeloid leukemia (CML) samples and 8 healthy donors in a 6 color multicolor flowcytometry (FCM) based assay. Furthermore, we performed fluorescence activated cell sorting on one CML sample to morphologically confirm the CD45lowSSClowCD14-CD123+CLEC12A+ subset to be highly enriched for basophils. Finally, to further delineate the CD45lowSSClowCD14-CD123+CLEC12A+ subpopulation in normal PB, we examined 3 healthy donors in a 10-color FCM assay enabling further separation of the cell subset into basophils and dendritic cells.Results: the CLEC12A receptor is expressed on basophils.Conclusions: Identification and enumeration of basophils is of high relevance in diagnostic hematology and immunology. We here show that CLEC12A in a simple FCM assay consistently marks basophils. Importantly, since basophils are characterized by a CD45lowSSClow profile similar to the “blast-gate” employed for the evaluation of hematological disorders, awareness of minor normal CLEC12A+ subpopulations is crucial when using CLEC12A as a minimal residual disease marker in myeloid malignancies.
Abstract.
Dambuza IM, Drake T, Chapuis A, Zhou X, Correia J, Taylor-Smith L, Legrave N, Rasmussen T, Fisher MC, Bicanic T, et al (In Press). The Cryptococcus neoformans Titan cell is an inducible and regulated morphotype underlying pathogenesis.
PLoS Pathogens,
14, 1-28.
Abstract:
The Cryptococcus neoformans Titan cell is an inducible and regulated morphotype underlying pathogenesis
Fungal cells change shape in response to environmental stimuli, and these morphogenic transitions drive pathogenesis and niche adaptation. For example, dimorphic fungi switch between yeast and hyphae in response to changing temperature. The basidiomycete Cryptococcus neoformans undergoes an unusual morphogenetic transition in the host lung from haploid yeast to large, highly polyploid cells termed Titan cells. Titan cells influence fungal interaction with host cells, including through increased drug resistance, altered cell size, and altered Pathogen Associated Molecular Pattern exposure. Despite the important role these cells play in pathogenesis, understanding the environmental stimuli that drive the morphological transition, and the molecular mechanisms underlying their unique biology, has been hampered by the lack of a reproducible in vitro induction system. Here we demonstrate reproducible in vitro Titan cell induction in response to environmental stimuli consistent with the host lung. In vitro Titan cells exhibit all the properties of in vivo generated Titan cells, the current gold standard, including altered capsule, cell wall, size, high mother cell ploidy, and aneuploid progeny. We identify the bacterial peptidoglycan subunit Muramyl Dipeptide as a serum compound associated with shift in cell size and ploidy, and demonstrate the capacity of bronchial lavage fluid and bacterial co-culture to induce Titanisation. Additionally, we demonstrate the capacity of our assay to identify established (cAMP/PKA) and previously undescribed (USV101) regulators of Titanisation in vitro. Finally, we investigate the Titanisation capacity of clinical isolates and their impact on disease outcome. Together, these findings provide new insight into the environmental stimuli and molecular mechanisms underlying the yeast-to-Titan transition and establish an essential in vitro model for the future characterization of this important morphotype.
Abstract.
Schwartz IS, Boyles TH, Kenyon CR, Hoving JC, Brown GD, Denning DW (In Press). The estimated burden of fungal disease in South Africa.
The South African Medical JournalAbstract:
The estimated burden of fungal disease in South Africa
Background: with a population of 56.5 million, over 7 million persons living with HIV, one of the highest rates of tuberculosis, and a large proportion of the population living in poverty, South Africa’s fungal disease burden is probably substantial and broad in scope. Objectives: to estimate the burden of fungal disease in South Africa. Methods: Using total and at-risk populations and national, regional, and occasionally global data, we estimated the incidence and prevalence of the majority of fungal diseases in South Africa. Results: Estimates for the annual incidence of HIV-related life-threatening fungal disease include cryptococcal meningitis (8,357 cases), Pneumocystis pneumonia (4,452 cases), and endemic mycoses (emergomycosis, histoplasmosis and blastomycosis with 100, 60, and 10 cases per year, respectively). We estimate 3,885 cases of invasive aspergillosis annually. The annual burden of candidaemia and Candida peritonitis is estimated at 8,257 and 2,972 cases, respectively. The epidemic of pulmonary tuberculosis has probably driven up the prevalence of chronic pulmonary aspergillosis to 99,351 (175.8/100,000), perhaps the highest in the world. Fungal asthma probably affects over 100,000 adults. Mucosal candidiasis is common with an annual prevalence estimated at 1,150,000 and 623,600 oral and oesophageal cases complicating HIV infection alone (estimates in other conditions not made), and over a million women are estimated to be affected by recurrent vulvovagingal candidiasis each year. Tinea capitis in children is common and conservatively estimated at >1,000,000 cases. The inoculation mycoses sporotrichosis, chromoblastomycosis and eumycetoma occur occasionally (with 40, 40, and 10 cases estimated, respectively). Overall, over 4 million South Africans are estimated to have a fungal disease each year (7.1% of the population). Conclusions: Significant numbers of South Africans are estimated to be affected each year by fungal infections, driven primarily by the syndemics of HIV, tuberculosis and poverty. These estimates emphasize the need for better epidemiological data, and for improving the diagnosis and management of these diseases.
Abstract.
Thompson A, Davies LC, Laio C-T, da Fonseca DM, Griffiths JS, Andrews R, Jones AV, Clement M, Brown GD, Humphreys IR, et al (In Press). The protective effect of inflammatory monocytes during systemic C. albicans infection is dependent on collaboration between C-type lectin-like receptors.
PLoS Pathogens,
15Abstract:
The protective effect of inflammatory monocytes during systemic C. albicans infection is dependent on collaboration between C-type lectin-like receptors
Invasive candidiasis, mainly caused by Candida albicans, is a serious healthcare problem with high mortality rates, particularly in immunocompromised patients. Innate immune cells express pathogen recognition receptors (PRRs) including C-type lectin-like receptors (CLRs) that bind C. albicans to initiate an immune response. Multiple CLRs including Dectin-1, Dectin-2 and Mincle have been proposed individually to contribute to the immune response to C. albicans. However how these receptors collaborate to clear a fungal infection is unknown. Herein, we used novel multi-CLR knockout (KO) mice to decipher the individual, collaborative and collective roles of Dectin-1, Dectin-2 and Mincle during systemic C. albicans infection. These studies revealed an unappreciated and profound role for CLR co-operation in anti-fungal immunity. The protective effect of multiple CLRs was markedly greater than any single receptor, and was mediated through inflammatory monocytes via recognition and phagocytosis of C. albicans, and production of C. albicans-induced cytokines and chemokines. These CLRs were dispensable for mediating similar responses from neutrophils, likely due to lower expression of these CLRs on neutrophils compared to inflammatory monocytes. Concurrent deletion of Dectin-1 and Dectin-2, or all three CLRs, resulted in dramatically increased susceptibility to systemic C. albicans infection compared to mice lacking a single CLR. Multi-CLR KO mice were unable to control fungal growth due to an inadequate early inflammatory monocyte-mediated response. In response to excessive fungal growth, the multi-CLR KO mice mounted a hyper-inflammatory response, likely leading to multiple organ failure. Thus, these data reveal a critical role for CLR co-operation in the effective control of C. albicans and maintenance of organ function during infection.
Abstract.
Brown GD (In Press). Trimming Surface Sugars Protects Histoplasma from Immune Attack.
mBio,
7, 1-3.
Abstract:
Trimming Surface Sugars Protects Histoplasma from Immune Attack
Dectin-1 is an essential innate immune receptor that recognizes β-glucans in fungal cell walls. Its importance is underscored by the mechanisms that fungal pathogens have evolved to avoid detection by this receptor. One such pathogen is Histoplasma capsulatum, and in a recent article in mBio, Rappleye’s group presented data showing that yeasts of this organism secrete a β-glucanase, Eng1, which acts to prune β-glucans that are exposed on the fungal cell surface [A. L. Garfoot et al. mBio 7(2):e01388-15, 2016, http://dx.doi.org/10.1128/mBio.01388-15]. The trimming of these sugars reduces immune recognition through Dectin-1 and subsequent inflammatory responses, enhancing the pathogenesis of H. capsulatum.
Abstract.
Toft-Petersen M, Nederby L, Kjeldsen E, Kerndrup GB, Brown GD, Hokland P, Stidsholt Roug A (In Press). Unravelling the relevance of CLEC12A as a cancer stem cell marker in myelodysplastic syndrome.
British Journal of Haematology,
175, 393-401.
Abstract:
Unravelling the relevance of CLEC12A as a cancer stem cell marker in myelodysplastic syndrome
Evidence of distinct disease propagating stem cells in myelodysplastic syndrome (MDS) has emerged in recent years. However, immunophenotypic characterization of these cancer stem cells remains sparse. In acute myeloid leukaemia (AML), we have previously described aberrant expression of the C-type lectin domain family 12, member a (CLEC12A) as a stable and reliable marker of leukaemia blasts and as a tool for assessing minimal residual disease. Furthermore, CLEC12A has been proposed as a promising marker of leukaemic stem cells in AML. The role of CLEC12A in MDS, however, remains to be elucidated. In this study, we found CLEC12A aberrantly expressed on the CD34(+) CD38(-) cell compartment in 71% (22/31) of MDS patients, distributed across all Revised International Prognostic Scoring System risk groups. We showed that the CD34(+) CD38(-) CLEC12A(+) cells were indeed malignant and possessed functional stem cell properties in the long-term colony-initiating cell assay. As opposed to reported findings in AML, we showed that cancer stem cells from MDS samples derived from both CLEC12A positive and negative CD34(+) CD38(-) subpopulations. Due to the absence of CLEC12A on normal haematopoietic stem cells, CLEC12A stem cell immunophenotyping may contribute to diagnosing and monitoring MDS patients and could furthermore add knowledge about disease propagating cells in MDS.
Abstract.
Tsoni SV, Brown GD (In Press). beta-Glucans and Dectin-1.
Annals of the New York Academy of Sciences,
1143, 45-60.
Abstract:
beta-Glucans and Dectin-1
beta-Glucans are naturally occurring carbohydrates that possess immune-modulating activities, but their mechanisms of action are largely unknown. Recent discoveries, however, including identification of beta-glucan receptors, such as dectin-1, have started to shed some light on the mechanisms underlying the properties of these carbohydrates. The characterization of dectin-1, in particular, has revealed some of the processes involved in beta-glucan sensing, intracellular signaling, and induction of cellular responses and has provided new insights into the role of beta-glucans in immunity and disease. Here we review both beta-glucans and their receptor, dectin-1.
Abstract.
Hadebe S, Kirstein F, Fierens K, Redelinghuys P, Murray GI, Williams DL, Lambrecht BN, Brombacher F, Brown GD (In Press). β-Glucan exacerbates allergic airway responses to house dust mite allergen.
Respiratory Research,
17, 1-3.
Abstract:
β-Glucan exacerbates allergic airway responses to house dust mite allergen
β-(1,3)-Glucan is present in mould cell walls and frequently detected in house dust mite (HDM) faeces. β-Glucan exposure is thought to be associated with pulmonary allergic inflammation in mouse and man, although the published data are inconsistent. Here, we show that highly purified β-glucan exacerbates HDM-induced eosinophilic, T helper 2 type airway responses by acting as an adjuvant, promoting activation, proliferation and polarisation of HDM-specific T cells (1-Derβ T cells). We therefore provide definitive evidence that β-glucan can influence allergic pulmonary inflammation.
Abstract.
2023
Hatinguais R, Leaves I, Brown GD, Brown AJP, Brock M, Peres da Silva R (2023). CRISPR-based tools for targeted genetic manipulation in pathogenic Sporothrix species.
Microbiol SpectrAbstract:
CRISPR-based tools for targeted genetic manipulation in pathogenic Sporothrix species.
Sporothrix brasiliensis is an emerging fungal pathogen frequently associated with zoonotic transmission of sporotrichosis by contaminated cats. Within 25 years, the disease has spread not only throughout Brazil but now to neighboring countries in Latin America. Thermo-dimorphism, melanin, glycans, adhesins, and secreted vesicles have been associated with the ability of Sporothrix species to cause disease in the mammalian host. Although certain virulence factors have been proposed as potential determinants for sporotrichosis, the scarcity of molecular tools for performing reverse genetics in Sporothrix has significantly impeded the dissection of mechanisms underlying the disease. Here, we demonstrate that PEG-mediated protoplast transformation is a powerful method for heterologous gene expression in S. brasiliensis, S. schenckii, and S. chilensis. Combined with CRISPR/Cas9 gene editing, this transformation protocol enabled the deletion of the putative DHN-melanin synthase gene pks1, which is a proposed virulence factor of Sporothrix species. To improve in locus integration of deletion constructs, we deleted the KU80 homolog that is critical for non-homologous end-joining DNA repair. The use of Δku80 strains from S. brasiliensis enhanced homologous-directed repair during transformation resulting in increased targeted gene deletion in combination with CRISPR/Cas9. In conclusion, our CRISPR/Cas9-based transformation protocol provides an efficient tool for targeted gene manipulation in Sporothrix species. IMPORTANCE Sporotrichosis caused by Sporothrix brasiliensis is a disease that requires long periods of treatment and is rapidly spreading across Latin America. The virulence of this fungus and the surge of atypical and more severe presentations of the disease raise the need for an understanding of the molecular mechanisms underlying sporotrichosis, as well as the development of better diagnostics and antifungal therapies. By developing molecular tools for accurate genetic manipulation in Sporothrix, this study addresses the paucity of reliable and reproducible tools for stable genetic engineering of Sporothrix species, which has represented a major obstacle for studying the virulence determinants and their roles in the establishment of sporotrichosis.
Abstract.
Author URL.
King J, Dambuza IM, Reid DM, Yuecel R, Brown GD, Warris A (2023). Detailed characterisation of invasive aspergillosis in a murine model of X-linked chronic granulomatous disease shows new insights in infections caused by Aspergillus fumigatus versus Aspergillus nidulans. Frontiers in Cellular and Infection Microbiology, 13
Hatinguais R, Kay M, Salazar F, Conn DP, Williams DL, Cook PC, Willment JA, Brown GD (2023). Development of Negative Controls for Fc-C-Type Lectin Receptor Probes.
Microbiol Spectr,
11(3).
Abstract:
Development of Negative Controls for Fc-C-Type Lectin Receptor Probes.
Fc-C-type lectin receptor (Fc-CTLRs) probes are soluble chimeric proteins constituted of the extracellular domain of a CTLR fused with the constant fraction (Fc) of the human IgG. These probes are useful tools to study the interaction of CTLRs with their ligands, with applications similar to those of antibodies, often in combination with widely available fluorescent antibodies targeting the Fc fragment (anti-hFc). In particular, Fc-Dectin-1 has been extensively used to study the accessibility of β-glucans at the surface of pathogenic fungi. However, there is no universal negative control for Fc-CTLRs, making the distinction of specific versus nonspecific binding difficult. We describe here 2 negative controls for Fc-CTLRs: a Fc-control constituting of only the Fc portion, and a Fc-Dectin-1 mutant predicted to be unable to bind β-glucans. Using these new probes, we found that while Fc-CTLRs exhibit virtually no nonspecific binding to Candida albicans yeasts, Aspergillus fumigatus resting spores strongly bind Fc-CTLRs in a nonspecific manner. Nevertheless, using the controls we describe here, we were able to demonstrate that A. fumigatus spores expose a low amount of β-glucan. Our data highlight the necessity of appropriate negative controls for experiments involving Fc-CTLRs probes. IMPORTANCE While Fc-CTLRs probes are useful tools to study the interaction of CTLRs with ligands, their use is limited by the lack of appropriate negative controls in assays involving fungi and potentially other pathogens. We have developed and characterized 2 negative controls for Fc-CTLRs assays: Fc-control and a Fc-Dectin-1 mutant. In this manuscript, we characterize the use of these negative controls with zymosan, a β-glucan containing particle, and 2 human pathogenic fungi, Candida albicans yeasts and Aspergillus fumigatus conidia. We show that A. fumigatus conidia nonspecifically bind Fc-CTLRs probes, demonstrating the need for appropriate negative controls in such assays.
Abstract.
Author URL.
Willment JA, Brown GD (2023). Immunity to fungi: Editorial overview. Seminars in Immunology, 66
2022
Itabangi H, Sephton-Clark PCS, Tamayo DP, Zhou X, Starling GP, Mahamoud Z, Insua I, Probert M, Correia J, Moynihan PJ, et al (2022). A bacterial endosymbiont of the fungus Rhizopus microsporus drives phagocyte evasion and opportunistic virulence.
Curr Biol,
32(5), 1115-1130.e6.
Abstract:
A bacterial endosymbiont of the fungus Rhizopus microsporus drives phagocyte evasion and opportunistic virulence.
Opportunistic infections by environmental fungi are a growing clinical problem, driven by an increasing population of people with immunocompromising conditions. Spores of the Mucorales order are ubiquitous in the environment but can also cause acute invasive infections in humans through germination and evasion of the mammalian host immune system. How they achieve this and the evolutionary drivers underlying the acquisition of virulence mechanisms are poorly understood. Here, we show that a clinical isolate of Rhizopus microsporus contains a Ralstonia pickettii bacterial endosymbiont required for virulence in both zebrafish and mice and that this endosymbiosis enables the secretion of factors that potently suppress growth of the soil amoeba Dictyostelium discoideum, as well as their ability to engulf and kill other microbes. As amoebas are natural environmental predators of both bacteria and fungi, we propose that this tri-kingdom interaction contributes to establishing endosymbiosis and the acquisition of anti-phagocyte activity. Importantly, we show that this activity also protects fungal spores from phagocytosis and clearance by human macrophages, and endosymbiont removal renders the fungal spores avirulent in vivo. Together, these findings describe a new role for a bacterial endosymbiont in Rhizopus microsporus pathogenesis in animals and suggest a mechanism of virulence acquisition through environmental interactions with amoebas.
Abstract.
Author URL.
Theobald H, Bejarano DA, Katzmarski N, Haub J, Schulte-Schrepping J, Yu J, Bassler K, Ćirović B, Osei-Sarpong C, Piattini F, et al (2022). Apolipoprotein E controls Dectin-1-dependent development of monocyte-derived alveolar macrophages upon pulmonary β-glucan-induced inflammatory adaptation.
Hatinguais R, Willment JA, Brown GD (2022). C‐type lectin receptors in antifungal immunity: Current knowledge and future developments. Parasite Immunology, 45(2).
Haji S, Ito T, Guenther C, Nakano M, Shimizu T, Mori D, Chiba Y, Tanaka M, Mishra SK, Willment JA, et al (2022). Human Dectin-1 is O-glycosylated and serves as a ligand for C-type lectin receptor CLEC-2.
Haji S, Ito T, Guenther C, Nakano M, Shimizu T, Mori D, Chiba Y, Tanaka M, Mishra SK, Willment JA, et al (2022). Human Dectin-1 is O-glycosylated and serves as a ligand for C-type lectin receptor CLEC-2.
Elife,
11Abstract:
Human Dectin-1 is O-glycosylated and serves as a ligand for C-type lectin receptor CLEC-2.
C-type lectin receptors (CLRs) elicit immune responses upon recognition of glycoconjugates present on pathogens and self-components. While Dectin-1 is the best-characterized CLR recognizing β-glucan on pathogens, the endogenous targets of Dectin-1 are not fully understood. Herein, we report that human Dectin-1 is a ligand for CLEC-2, another CLR expressed on platelets. Biochemical analyses revealed that Dectin-1 is a mucin-like protein as its stalk region is highly O-glycosylated. A sialylated core 1 glycan attached to the EDxxT motif of human Dectin-1, which is absent in mouse Dectin-1, provides a ligand moiety for CLEC-2. Strikingly, the expression of human Dectin-1 in mice rescued the lethality and lymphatic defect resulting from a deficiency of Podoplanin, a known CLEC-2 ligand. This finding is the first example of an innate immune receptor also functioning as a physiological ligand to regulate ontogeny upon glycosylation.
Abstract.
Author URL.
Avelar GM, Dambuza IM, Ricci L, Yuecel R, Mackenzie K, Childers DS, Bain JM, Pradhan A, Larcombe DE, Netea MG, et al (2022). Impact of Changes at the Candida Albicans Cell Surface Upon Immunogenicity and Colonisation in the Gastrointestinal Tract.
Avelar GM, Dambuza IM, Ricci L, Yuecel R, Mackenzie K, Childers DS, Bain JM, Pradhan A, Larcombe DE, Netea MG, et al (2022). Impact of changes at the Candida albicans cell surface upon immunogenicity and colonisation in the gastrointestinal tract.
Cell Surf,
8Abstract:
Impact of changes at the Candida albicans cell surface upon immunogenicity and colonisation in the gastrointestinal tract.
The immunogenicity of Candida albicans cells is influenced by changes in the exposure of microbe-associated molecular patterns (MAMPs) on the fungal cell surface. Previously, the degree of exposure on the C. albicans cell surface of the immunoinflammatory MAMP β-(1,3)-glucan was shown to correlate inversely with colonisation levels in the gastrointestinal (GI) tract. This is important because life-threatening systemic candidiasis in critically ill patients often arises from translocation of C. albicans strains present in the patient's GI tract. Therefore, using a murine model, we have examined the impact of gut-related factors upon β-glucan exposure and colonisation levels in the GI tract. The degree of β-glucan exposure was examined by imaging flow cytometry of C. albicans cells taken directly from GI compartments, and compared with colonisation levels. Fungal β-glucan exposure was lower in the cecum than the small intestine, and fungal burdens were correspondingly higher in the cecum. This inverse correlation did not hold for the large intestine. The gut fermentation acid, lactate, triggers β-glucan masking in vitro, leading to attenuated anti-Candida immune responses. Additional fermentation acids are present in the GI tract, including acetate, propionate, and butyrate. We show that these acids also influence β-glucan exposure on C. albicans cells in vitro and, like lactate, they influence β-glucan exposure via Gpr1/Gpa2-mediated signalling. Significantly, C. albicans gpr1Δ gpa2Δ cells displayed elevated β-glucan exposure in the large intestine and a corresponding decrease in fungal burden, consistent with the idea that Gpr1/Gpa2-mediated β-glucan masking influences colonisation of this GI compartment. Finally, extracts from the murine gut and culture supernatants from the mannan grazing gut anaerobe Bacteroides thetaiotaomicron promote β-glucan exposure at the C. albicans cell surface. Therefore, the local microbiota influences β-glucan exposure levels directly (via mannan grazing) and indirectly (via fermentation acids), whilst β-glucan masking appears to promote C. albicans colonisation of the murine large intestine.
Abstract.
Author URL.
de Assis LJ, Bain JM, Liddle C, Leaves I, Hacker C, Peres da Silva R, Yuecel R, Bebes A, Stead D, Childers DS, et al (2022). Nature of β-1,3-Glucan-Exposing Features on Candida albicans Cell Wall and Their Modulation.
mBio,
13(6).
Abstract:
Nature of β-1,3-Glucan-Exposing Features on Candida albicans Cell Wall and Their Modulation.
Candida albicans exists as a commensal of mucosal surfaces and the gastrointestinal tract without causing pathology. However, this fungus is also a common cause of mucosal and systemic infections when antifungal immune defenses become compromised. The activation of antifungal host defenses depends on the recognition of fungal pathogen-associated molecular patterns (PAMPs), such as β-1,3-glucan. In C. albicans, most β-1,3-glucan is present in the inner cell wall, concealed by the outer mannan layer, but some β-1,3-glucan becomes exposed at the cell surface. In response to host signals, such as lactate, C. albicans induces the Xog1 exoglucanase, which shaves exposed β-1,3-glucan from the cell surface, thereby reducing phagocytic recognition. We show here that β-1,3-glucan is exposed at bud scars and punctate foci on the lateral wall of yeast cells, that this exposed β-1,3-glucan is targeted during phagocytic attack, and that lactate-induced masking reduces β-1,3-glucan exposure at bud scars and at punctate foci. β-1,3-Glucan masking depends upon protein kinase a (PKA) signaling. We reveal that inactivating PKA, or its conserved downstream effectors, Sin3 and Mig1/Mig2, affects the amounts of the Xog1 and Eng1 glucanases in the C. albicans secretome and modulates β-1,3-glucan exposure. Furthermore, perturbing PKA, Sin3, or Mig1/Mig2 attenuates the virulence of lactate-exposed C. albicans cells in Galleria. Taken together, the data are consistent with the idea that β-1,3-glucan masking contributes to Candida pathogenicity. IMPORTANCE Microbes that coexist with humans have evolved ways of avoiding or evading our immunological defenses. These include the masking by these microbes of their "pathogen-associated molecular patterns" (PAMPs), which are recognized as "foreign" and used to activate protective immunity. The commensal fungus Candida albicans masks the proinflammatory PAMP β-1,3-glucan, which is an essential component of its cell wall. Most of this β-1,3-glucan is hidden beneath an outer layer of the cell wall on these microbes, but some can become exposed at the fungal cell surface. Using high-resolution confocal microscopy, we examine the nature of the exposed β-1,3-glucan at C. albicans bud scars and at punctate foci on the lateral cell wall, and we show that these features are targeted by innate immune cells. We also reveal that downstream effectors of protein kinase a (Mig1/Mig2, Sin3) regulate the secretion of major glucanases, modulate the levels of β-1,3-glucan exposure, and influence the virulence of C. albicans in an invertebrate model of systemic infection. Our data support the view that β-1,3-glucan masking contributes to immune evasion and the virulence of a major fungal pathogen of humans.
Abstract.
Author URL.
Salazar F, Bignell E, Brown GD, Cook PC, Warris A (2022). Pathogenesis of Respiratory Viral and Fungal Coinfections.
Clin Microbiol Rev,
35(1).
Abstract:
Pathogenesis of Respiratory Viral and Fungal Coinfections.
Individuals suffering from severe viral respiratory tract infections have recently emerged as "at risk" groups for developing invasive fungal infections. Influenza virus is one of the most common causes of acute lower respiratory tract infections worldwide. Fungal infections complicating influenza pneumonia are associated with increased disease severity and mortality, with invasive pulmonary aspergillosis being the most common manifestation. Strikingly, similar observations have been made during the current coronavirus disease 2019 (COVID-19) pandemic. The copathogenesis of respiratory viral and fungal coinfections is complex and involves a dynamic interplay between the host immune defenses and the virulence of the microbes involved that often results in failure to return to homeostasis. In this review, we discuss the main mechanisms underlying susceptibility to invasive fungal disease following respiratory viral infections. A comprehensive understanding of these interactions will aid the development of therapeutic modalities against newly identified targets to prevent and treat these emerging coinfections.
Abstract.
Author URL.
Pradhan A, Ma Q, Hickey E, Avelar G, Larcombe D, Bain J, Childers D, Dambuza I, Leaves I, de Assis LJ, et al (2022). S9.4c Diverse environmental inputs mediate changes in β-glucan exposure at the Candida albicans cell surface thereby influencing tissue colonisation during systemic infection. Medical Mycology, 60(Suppl 1).
2021
Stappers MHT, Nikolakopoulou C, Wiesner DL, Yuecel R, Klein BS, Willment JA, Brown GD (2021). Characterization of antifungal C-type lectin receptor expression on murine epithelial and endothelial cells in mucosal tissues.
Eur J Immunol,
51(9), 2341-2344.
Abstract:
Characterization of antifungal C-type lectin receptor expression on murine epithelial and endothelial cells in mucosal tissues.
Our data reveal that selection of enzymes for generating single cell suspensions from murine tissues influences detection of surface expression of antifungal CLRs. Using a method that most preserves receptor expression, we show that non-myeloid expression of antifungal CLRs is limited to MelLec on endothelial cells in murine mucosal tissues.
Abstract.
Author URL.
Neves GWP, Wong SSW, Aimanianda V, Simenel C, Guijarro JI, Walls C, Willment JA, Gow NAR, Munro CA, Brown GD, et al (2021). Complement-Mediated Differential Immune Response of Human Macrophages to Sporothrix Species Through Interaction with Their Cell Wall Peptidorhamnomannans. Frontiers in Immunology, 12
Hatinguais R, Brown GD (2021). Cross-presentation is getting DNGRous.
Nat Immunol,
22(2), 108-110.
Author URL.
Bain JM, Alonso MF, Childers DS, Walls CA, Mackenzie K, Pradhan A, Lewis LE, Louw J, Avelar GM, Larcombe DE, et al (2021). Immune cells fold and damage fungal hyphae.
Proc Natl Acad Sci U S A,
118(15).
Abstract:
Immune cells fold and damage fungal hyphae.
Innate immunity provides essential protection against life-threatening fungal infections. However, the outcomes of individual skirmishes between immune cells and fungal pathogens are not a foregone conclusion because some pathogens have evolved mechanisms to evade phagocytic recognition, engulfment, and killing. For example, Candida albicans can escape phagocytosis by activating cellular morphogenesis to form lengthy hyphae that are challenging to engulf. Through live imaging of C. albicans-macrophage interactions, we discovered that macrophages can counteract this by folding fungal hyphae. The folding of fungal hyphae is promoted by Dectin-1, β2-integrin, VASP, actin-myosin polymerization, and cell motility. Folding facilitates the complete engulfment of long hyphae in some cases and it inhibits hyphal growth, presumably tipping the balance toward successful fungal clearance.
Abstract.
Author URL.
Dambuza IM, Brown GD (2021). Managing the mycobiota with IgA.
Nat Microbiol,
6(12), 1471-1472.
Author URL.
Tone K, Stappers MHT, Hatinguais R, Dambuza IM, Salazar F, Wallace C, Yuecel R, Morvay PL, Kuwano K, Willment JA, et al (2021). MelLec Exacerbates the Pathogenesis of Aspergillus fumigatus-Induced Allergic Inflammation in Mice.
Frontiers in Immunology,
12Abstract:
MelLec Exacerbates the Pathogenesis of Aspergillus fumigatus-Induced Allergic Inflammation in Mice
Environmental factors, particularly fungi, influence the pathogenesis of allergic airway inflammation, but the mechanisms underlying these effects are still unclear. Melanin is one fungal component which is thought to modulate pulmonary inflammation. We recently identified a novel C-type lectin receptor, MelLec (Clec1a), which recognizes fungal 1,8-dihydroxynaphthalene (DHN)-melanin and is able to regulate inflammatory responses. Here we show that MelLec promotes pulmonary allergic inflammation and drives the development of Th17 T-cells in response to spores of Aspergillus fumigatus. Unexpectedly, we found that MelLec deficiency was protective, with MelLec-/- animals showing normal weight gain and significantly reduced pulmonary inflammation in our allergic model. The lungs of treated MelLec-/- mice displayed significantly reduced inflammatory foci and reduced bronchial wall thickening, which correlated with a reduced cellular influx (particularly neutrophils and inflammatory monocytes) and levels of inflammatory cytokines and chemokines. Notably, fungal burdens were increased in MelLec-/- animals, without apparent adverse effects, and there were no alterations in the survival of these mice. Characterization of the pulmonary T-cell populations, revealed a significant reduction in Th17 cells, and no alterations in Th2, Th1 or Treg cells. Thus, our data reveal that while MelLec is required to control pulmonary fungal burden, the inflammatory responses mediated by this receptor negatively impact the animal welfare in this allergic model.
Abstract.
Hatinguais R, Pradhan A, Brown GD, Brown AJP, Warris A, Shekhova E (2021). Mitochondrial Reactive Oxygen Species Regulate Immune Responses of Macrophages to Aspergillus fumigatus.
Front Immunol,
12Abstract:
Mitochondrial Reactive Oxygen Species Regulate Immune Responses of Macrophages to Aspergillus fumigatus.
Reactive Oxygen Species (ROS) are highly reactive molecules that can induce oxidative stress. For instance, the oxidative burst of immune cells is well known for its ability to inhibit the growth of invading pathogens. However, ROS also mediate redox signalling, which is important for the regulation of antimicrobial immunity. Here, we report a crucial role of mitochondrial ROS (mitoROS) in antifungal responses of macrophages. We show that mitoROS production rises in murine macrophages exposed to swollen conidia of the fungal pathogen Aspergillus fumigatus compared to untreated macrophages, or those treated with resting conidia. Furthermore, the exposure of macrophages to swollen conidia increases the activity of complex II of the respiratory chain and raises mitochondrial membrane potential. These alterations in mitochondria of infected macrophages suggest that mitoROS are produced via reverse electron transport (RET). Significantly, preventing mitoROS generation via RET by treatment with rotenone, or a suppressor of site IQ electron leak, S1QEL1.1, lowers the production of pro-inflammatory cytokines TNF-α and IL-1β in macrophages exposed to swollen conidia of A. fumigatus. Rotenone and S1QEL1.1 also reduces the fungicidal activity of macrophages against swollen conidia. Moreover, we have established that elevated recruitment of NADPH oxidase 2 (NOX2, also called gp91phox) to the phagosomal membrane occurs prior to the increase in mitoROS generation. Using macrophages from gp91phox-/- mice, we have further demonstrated that NOX2 is required to regulate cytokine secretion by RET-associated mitoROS in response to infection with swollen conidia. Taken together, these observations demonstrate the importance of RET-mediated mitoROS production in macrophages infected with A. fumigatus.
Abstract.
Author URL.
Asamaphan P, Brown GD, Willment JA (2021). Quantifying Receptor-Mediated Phagocytosis and Inflammatory Responses to Fungi in Immune Cells.
,
2260, 155-178.
Abstract:
Quantifying Receptor-Mediated Phagocytosis and Inflammatory Responses to Fungi in Immune Cells
Phagocytosis and cytokine production are important processes by which innate immune cells, especially professional phagocytes such as neutrophils and macrophages, control and regulate immunity to fungi. These cellular responses are initiated when conserved pathogen components, known as pathogen-associated molecular patterns (PAMPs), are recognized by pattern-recognition receptors (PRRs), which include members of the C-type lectin receptor (CLR) family that are able to bind to fungal cell wall-derived carbohydrates. Phagocytosis and cytokine production can be quantitatively examined by flow cytometry and enzyme-linked immunosorbent assay (ELISA), respectively, using in vitro based assays with primary-derived murine cells and cell lines. Here, we describe a flow cytometry-based method using transduced cell lines to assess the ability of CLRs to mediate internalization, using A. fumigatus conidia and the β-1,3 glucan receptor, Dectin-1 (CLEC7A), as an example. The use of ELISA-based assays to measure cytokine production by immune cells that are induced in response to fungi and methods for isolating and culturing primary macrophages from various murine tissues are described.
Abstract.
Cao H, Antonopoulos A, Henderson S, Wassall H, Brewin J, Masson A, Shepherd J, Konieczny G, Patel B, Williams ML, et al (2021). Red blood cell mannoses as phagocytic ligands mediating both sickle cell anaemia and malaria resistance.
Nature Communications,
12(1).
Abstract:
Red blood cell mannoses as phagocytic ligands mediating both sickle cell anaemia and malaria resistance
In both sickle cell disease and malaria, red blood cells (RBCs) are phagocytosed in the spleen, but receptor-ligand pairs mediating uptake have not been identified. Here, we report that patches of high mannose N-glycans (Man5-9GlcNAc2), expressed on diseased or oxidized RBC surfaces, bind the mannose receptor (CD206) on phagocytes to mediate clearance. We find that extravascular hemolysis in sickle cell disease correlates with high mannose glycan levels on RBCs. Furthermore, Plasmodium falciparum-infected RBCs expose surface mannose N-glycans, which occur at significantly higher levels on infected RBCs from sickle cell trait subjects compared to those lacking hemoglobin S. The glycans are associated with high molecular weight complexes and protease-resistant, lower molecular weight fragments containing spectrin. Recognition of surface N-linked high mannose glycans as a response to cellular stress is a molecular mechanism common to both the pathogenesis of sickle cell disease and resistance to severe malaria in sickle cell trait.
Abstract.
Vendele I, Feizi T, Spyrou M, Stappers M, Brown G, Willment J, Silva L, Palma A, Chaie W, Liu Y, et al (2021). Spatial mapping of immunological epitopes in the Candida cell wall using C-type lectin probes. Access Microbiology, 3(12).
Piras M, Patruno I, Nikolakopoulou C, Willment JA, Sloan NL, Zanato C, Brown GD, Zanda M (2021). Synthesis of the Fungal Metabolite YWA1 and Related Constructs as Tools to Study MelLec-Mediated Immune Response to Aspergillus Infections †.
Journal of Organic Chemistry,
86(9), 6044-6055.
Abstract:
Synthesis of the Fungal Metabolite YWA1 and Related Constructs as Tools to Study MelLec-Mediated Immune Response to Aspergillus Infections †
We describe the chemical synthesis of the fungal naphthopyrones YWA1 and fonsecin B, as well as their functionalization with an amine-spacer arm and the conjugation of the resulting molecules to three different functional tags (i.e. biotin, Oregon green, 1-[3-(succinimidyloxycarbonyl)benzyl]-4-[5-(4-methoxyphenyl)-2-oxazolyl]pyridinium bromide (PyMPO)). The naphthopyrone-biotin and -PyMPO constructs maintained the ability to bind the C-type lectin receptor MelLec, whose interaction with immunologically active fungal metabolites (i.e. 1,8-dihydroxynaphthalene-(DHN)-melanin and YWA1) is a key step in host recognition and induction of protective immune responses against Aspergillus fumigatus. The fluorescent Fonsecin B-PyMPO construct 21 was used to selectively visualize MelLec-expressing cells, thus validating the potential of this strategy for studying the role and functions of MelLec in immunity.
Abstract.
Baldassarre M, Solano-Collado V, Balci A, Colamarino RA, Dambuza IM, Reid DM, Wilson HM, Brown GD, Mukhopadhyay S, Dougan G, et al (2021). The Rab32/BLOC-3-dependent pathway mediates host defense against different pathogens in human macrophages.
Science Advances,
7(3).
Abstract:
The Rab32/BLOC-3-dependent pathway mediates host defense against different pathogens in human macrophages
Macrophages provide a first line of defense against microorganisms, and while some mechanisms to kill pathogens such as the oxidative burst are well described, others are still undefined or unknown. Here, we report that the Rab32 guanosine triphosphatase and its guanine nucleotide exchange factor BLOC-3 (biogenesis of lysosome-related organelles complex-3) are central components of a trafficking pathway that controls both bacterial and fungal intracellular pathogens. This host-defense mechanism is active in both human and murine macrophages and is independent of well-known antimicrobial mechanisms such as the NADPH (reduced form of nicotinamide adenine dinucleotide phosphate)-dependent oxidative burst, production of nitric oxide, and antimicrobial peptides. To survive in human macrophages, Salmonella Typhi actively counteracts the Rab32/BLOC-3 pathway through its Salmonella pathogenicity island-1-encoded type III secretion system. These findings demonstrate that the Rab32/BLOC-3 pathway is a novel and universal host-defense pathway and protects mammalian species from various pathogens.
Abstract.
2020
Schaefer K, Dambuza IM, Dall’Angelo S, Yuecel R, Jaspars M, Trembleau L, Zanda M, Brown GD, Netea MG, Gow NAR, et al (2020). A Weakened Immune Response to Synthetic Exo-Peptides Predicts a Potential Biosecurity Risk in the Retrieval of Exo-Microorganisms.
Microorganisms,
8(7), 1066-1066.
Abstract:
A Weakened Immune Response to Synthetic Exo-Peptides Predicts a Potential Biosecurity Risk in the Retrieval of Exo-Microorganisms
The discovery of liquid water at several locations in the solar system raises the possibility that microbial life may have evolved outside Earth and as such could be accidently introduced into the Earth’s ecosystem. Unusual sugars or amino acids, like non-proteinogenic isovaline and α-aminoisobutyric acid that are vanishingly rare or absent from life forms on Earth, have been found in high abundance on non-terrestrial carbonaceous meteorites. It is therefore conceivable that exo-microorganisms might contain proteins that include these rare amino acids. We therefore asked whether the mammalian immune system would be able to recognize and induce appropriate immune responses to putative proteinaceous antigens that include these rare amino acids. To address this, we synthesised peptide antigens based on a backbone of ovalbumin and introduced isovaline and α-aminoisobutyric acid residues and demonstrated that these peptides can promote naïve OT-I cell activation and proliferation, but did so less efficiently than the canonical peptides. This is relevant to the biosecurity of missions that may retrieve samples from exoplanets and moons that have conditions that may be permissive for life, suggesting that accidental contamination and exposure to exo-microorganisms with such distinct proteomes might pose an immunological challenge.
Abstract.
Hoving JC, Brown GD, Gómez BL, Govender NP, Limper AH, May RC, Meya DB (2020). AIDS-Related Mycoses: Updated Progress and Future Priorities.
Trends in Microbiology,
28(6), 425-428.
Abstract:
AIDS-Related Mycoses: Updated Progress and Future Priorities
Serious fungal infections continue to devastate people living with HIV and remain a leading cause of infection-related deaths in this population, second only to tuberculosis. The third AIDS-related mycoses workshop updated progress in the field over the last 3 years and highlighted six key action points for the future.
Abstract.
Nikolakopoulou C, Willment JA, Brown GD (2020). C-Type Lectin Receptors in Antifungal Immunity. In (Ed)
Advances in Experimental Medicine and Biology, 1-30.
Abstract:
C-Type Lectin Receptors in Antifungal Immunity
Abstract.
Cao H, Antonopoulos A, Henderson S, Wassall H, Brewin J, Masson A, Shepherd J, Konieczny G, Patel B, Williams M-L, et al (2020). High mannose N-glycans on red blood cells as phagocytic ligands, mediating both sickle cell anaemia and resistance to malaria.
Vendele I, Willment JA, Silva LM, Palma AS, Chai W, Liu Y, Feizi T, Spyrou M, Stappers MHT, Brown GD, et al (2020). Mannan detecting C-type lectin receptor probes recognise immune epitopes with diverse chemical, spatial and phylogenetic heterogeneity in fungal cell walls.
PLoS Pathog,
16(1).
Abstract:
Mannan detecting C-type lectin receptor probes recognise immune epitopes with diverse chemical, spatial and phylogenetic heterogeneity in fungal cell walls.
During the course of fungal infection, pathogen recognition by the innate immune system is critical to initiate efficient protective immune responses. The primary event that triggers immune responses is the binding of Pattern Recognition Receptors (PRRs), which are expressed at the surface of host immune cells, to Pathogen-Associated Molecular Patterns (PAMPs) located predominantly in the fungal cell wall. Most fungi have mannosylated PAMPs in their cell walls and these are recognized by a range of C-type lectin receptors (CTLs). However, the precise spatial distribution of the ligands that induce immune responses within the cell walls of fungi are not well defined. We used recombinant IgG Fc-CTLs fusions of three murine mannan detecting CTLs, including dectin-2, the mannose receptor (MR) carbohydrate recognition domains (CRDs) 4-7 (CRD4-7), and human DC-SIGN (hDC-SIGN) and of the β-1,3 glucan-binding lectin dectin-1 to map PRR ligands in the fungal cell wall of fungi grown in vitro in rich and minimal media. We show that epitopes of mannan-specific CTL receptors can be clustered or diffuse, superficial or buried in the inner cell wall. We demonstrate that PRR ligands do not correlate well with phylogenetic relationships between fungi, and that Fc-lectin binding discriminated between mannosides expressed on different cell morphologies of the same fungus. We also demonstrate CTL epitope differentiation during different phases of the growth cycle of Candida albicans and that MR and DC-SIGN labelled outer chain N-mannans whilst dectin-2 labelled core N-mannans displayed deeper in the cell wall. These immune receptor maps of fungal walls of in vitro grown cells therefore reveal remarkable spatial, temporal and chemical diversity, indicating that the triggering of immune recognition events originates from multiple physical origins at the fungal cell surface.
Abstract.
Author URL.
Hatinguais R, Willment JA, Brown GD (2020). PAMPs of the fungal cell wall and mammalian PRRs.
,
425, 187-223.
Abstract:
PAMPs of the fungal cell wall and mammalian PRRs
Fungi are opportunistic pathogens that infect immunocompromised patients and are responsible for an estimated 1.5 million deaths every year. The antifungal innate immune response is mediated through the recognition of pathogen-associated molecular patterns (PAMPs) by the host’s pattern recognition receptors (PRRs). PRRs are immune receptors that ensure the internalisation and the killing of fungal pathogens. They also mount the inflammatory response, which contributes to initiate and polarise the adaptive response, controlled by lymphocytes. Both the innate and adaptive immune responses are required to control fungal infections. The immune recognition of fungal pathogen primarily occurs at the interface between the membrane of innate immune cells and the fungal cell wall, which contains a number of PAMPs. This chapter will focus on describing the main mammalian PRRs that have been shown to bind to PAMPs from the fungal cell wall of the four main fungal pathogens: Candida albicans, Aspergillus fumigatus, Cryptococcus neoformans and Pneumocystis jirovecii. We will describe these receptors, their functions and ligands to provide the reader with an overview of how the immune system recognises fungal pathogens and responds to them.
Abstract.
Gonçalves SM, Duarte-Oliveira C, Campos CF, Aimanianda V, ter Horst R, Leite L, Mercier T, Pereira P, Fernández-García M, Antunes D, et al (2020). Phagosomal removal of fungal melanin reprograms macrophage metabolism to promote antifungal immunity.
Nature Communications,
11(1).
Abstract:
Phagosomal removal of fungal melanin reprograms macrophage metabolism to promote antifungal immunity
AbstractIn response to infection, macrophages adapt their metabolism rapidly to enhance glycolysis and fuel specialized antimicrobial effector functions. Here we show that fungal melanin is an essential molecule required for the metabolic rewiring of macrophages during infection with the fungal pathogen Aspergillus fumigatus. Using pharmacological and genetic tools, we reveal a molecular link between calcium sequestration by melanin inside the phagosome and induction of glycolysis required for efficient innate immune responses. By remodeling the intracellular calcium machinery and impairing signaling via calmodulin, melanin drives an immunometabolic signaling axis towards glycolysis with activation of hypoxia-inducible factor 1 subunit alpha (HIF-1α) and phagosomal recruitment of mammalian target of rapamycin (mTOR). These data demonstrate a pivotal mechanism in the immunometabolic regulation of macrophages during fungal infection and highlight the metabolic repurposing of immune cells as a potential therapeutic strategy.
Abstract.
Höft MA, Hoving JC, Brown GD (2020). Signaling C-Type Lectin Receptors in Antifungal Immunity. In (Ed)
Current Topics in Microbiology and Immunology, 63-101.
Abstract:
Signaling C-Type Lectin Receptors in Antifungal Immunity
Abstract.
Speakman EA, Dambuza IM, Salazar F, Brown GD (2020). T Cell Antifungal Immunity and the Role of C-Type Lectin Receptors. Trends in Immunology, 41(1), 61-76.
Valsecchi I, Stephen-Victor E, Wong SSW, Karnam A, Sunde M, Guijarro JI, de Francisco BR, Krüger T, Kniemeyer O, Brown GD, et al (2020). The role of roda-conserved cysteine residues in the aspergillus fumigatus conidial surface organization.
Journal of Fungi,
6(3), 1-17.
Abstract:
The role of roda-conserved cysteine residues in the aspergillus fumigatus conidial surface organization
Immune inertness of Aspergillus fumigatus conidia is attributed to its surface rodlet-layer made up of RodAp, characterized by eight conserved cysteine residues forming four disulfide bonds. Earlier, we showed that the conserved cysteine residue point (ccrp) mutations result in conidia devoid of the rodlet layer. Here, we extended our study comparing the surface organization and immunoreactivity of conidia carrying ccrp-mutations with the RODA deletion mutant (∆rodA). Western blot analysis using anti-RodAp antibodies indicated the absence of RodAp in the cytoplasm of ccrp-mutant conidia. Immunolabeling revealed differential reactivity to conidial surface glucans, the ccrp-mutant conidia preferentially binding to α-(1,3)-glucan, ∆rodA conidia selectively bound to β-(1,3)-glucan; the parental strain conidia showed negative labeling. However, permeability of ccrp-mutants and ∆rodA was similar to the parental strain conidia. Proteomic analyses of the conidial surface exposed proteins of the ccrp-mutants showed more similarities with the parental strain, but were significantly different from the ∆rodA. Ccrp-mutant conidia were less immunostimulatory compared to ∆rodA conidia. Our data suggest that (i) the conserved cysteine residues are essential for the trafficking of RodAp and the organization of the rodlet layer on the conidial surface, and (ii) targeted point mutation could be an alternative approach to study the role of fungal cell-wall genes in host–fungal interaction.
Abstract.
2019
Tone K, Stappers MHT, Willment JA, Brown GD (2019). C-type lectin receptors of the Dectin-1 cluster: Physiological roles and involvement in disease.
European Journal of Immunology,
49(12), 2127-2133.
Abstract:
C-type lectin receptors of the Dectin-1 cluster: Physiological roles and involvement in disease
C-type lectin receptors (CLRs) are essential for multicellular existence, having diverse functions ranging from embryonic development to immune function. One subgroup of CLRs is the Dectin-1 cluster, comprising of seven receptors including MICL, CLEC-2, CLEC-12B, CLEC-9A, MelLec, Dectin-1, and LOX-1. Reflecting the larger CLR family, the Dectin-1 cluster of receptors has a broad range of ligands and functions, but importantly, is involved in numerous pathophysiological processes that regulate health and disease. Indeed, these receptors have been implicated in development, infection, regulation of inflammation, allergy, transplantation tolerance, cancer, cardiovascular disease, arthritis, and other autoimmune diseases. In this mini-review, we discuss the latest advancements in elucidating the function(s) of each of the Dectin-1 cluster CLRs, focussing on their physiological roles and involvement in disease.
Abstract.
Itabangi H, Sephton-Clark P, Zhou X, Starling G, Mahamoud Z, Insua I, Probert M, Correia J, Moynihan P, Gebremariam T, et al (2019). Environmental interactions with amoebae as drivers of bacterial-fungal endosymbiosis and pathogenicity.
Abstract:
Environmental interactions with amoebae as drivers of bacterial-fungal endosymbiosis and pathogenicity
Opportunistic infections by environmental fungi are a growing clinical problem, driven by an increasing population of people with immunocompromising conditions. Spores of the Mucorales order are ubiquitious in the environment but can also cause acute invasive infections in humans through germination and evasion of the mammalian host immune system. How they achieve this, and the evolutionary drivers underlying the acquisition of virulence mechanisms, are poorly understood. Here we show that a clinical isolate of Rhizopus microsporus contains a Ralstonia pickettii bacterial endosymbiont required for virulence in both zebrafish and mice, and that this endosymbiosis enables secretion of factors that potently suppress growth of the soil amoeba Dictyostelium discoideum , as well as their ability to engulf and kill other microbes. As amoebae are natural environmental predators of both bacteria and fungi, we propose this tri-kingdom interaction contributes to establishing the endosymbiosis, and acquisition of anti-phagocyte activity. Importantly, we show this activity also protects fungal spores from phagocytosis and clearance by human macrophages, and endosymbiont removal renders the fungal spores avirulent in vivo. Together, these findings describe a novel role for a bacterial endosymbiont in Rhizopus microsporus pathogenesis in animals, and suggest a mechanism of virulence acquisition through environmental interactions with amoebae. In brief How environmental fungi evolved the mechanisms that enable them to cause opportunistic infections in humans is unclear. Here, we identify a novel tri-kingdom interaction, whereby a bacterial endosymbiont, living within a clinical isolate of the ubiquitous environmental fungus Rhizopus microsporus , causes the generation of a secreted activity that blocks the growth and predatory activity of amoebae. We suggest this provides a new evolutionary driver for the establishment of bacterial/fungal endosymbiosis and demonstrate this is critical for fungal pathogenicity in vivo.
Abstract.
Dambuza IM, Brown GD (2019). Fungi accelerate pancreatic cancer.
Nature,
574(7777), 184-185.
Author URL.
Brown GD, Wilson D (2019). Mammalian innate immunity to fungal infection.
Semin Cell Dev Biol,
89, 1-2.
Author URL.
Vendele I, Willment JA, Silva LM, Palma AS, Chai W, Liu Y, Feizi T, Stappers MHT, Brown GD, Gow NAR, et al (2019). Mannan detecting C-type lectin receptor probes recognise immune epitopes with diverse chemical, spatial and phylogenetic heterogeneity in fungal cell walls.
Brown AJP, Gow NAR, Warris A, Brown GD (2019). Memory in Fungal Pathogens Promotes Immune Evasion, Colonisation, and Infection.
Trends in Microbiology,
27(3), 219-230.
Abstract:
Memory in Fungal Pathogens Promotes Immune Evasion, Colonisation, and Infection
By analogy with Pavlov's dogs, certain pathogens have evolved anticipatory behaviours that exploit specific signals in the human host to prepare themselves against imminent host challenges. This adaptive prediction, a type of history-dependent microbial behaviour, represents a primitive form of microbial memory. For fungal pathogens, adaptive prediction helps them circumvent nutritional immunity, protects them against phagocytic killing, and activates immune evasion strategies. We describe how these anticipatory responses, and the contrasting lifestyles and evolutionary trajectories of fungal pathogens, have influenced the evolution of such adaptive behaviours, and how these behaviours affect host colonisation and infection.
Abstract.
Pradhan A, Avelar GM, Bain JM, Childers D, Pelletier C, Larcombe DE, Shekhova E, Netea MG, Brown GD, Erwig L, et al (2019). Non-canonical signalling mediates changes in fungal cell wall PAMPs that drive immune evasion.
Nat Commun,
10(1).
Abstract:
Non-canonical signalling mediates changes in fungal cell wall PAMPs that drive immune evasion.
To colonise their host, pathogens must counter local environmental and immunological challenges. Here, we reveal that the fungal pathogen Candida albicans exploits diverse host-associated signals to promote immune evasion by masking of a major pathogen-associated molecular pattern (PAMP), β-glucan. Certain nutrients, stresses and antifungal drugs trigger β-glucan masking, whereas other inputs, such as nitrogen sources and quorum sensing molecules, exert limited effects on this PAMP. In particular, iron limitation triggers substantial changes in the cell wall that reduce β-glucan exposure. This correlates with reduced phagocytosis by macrophages and attenuated cytokine responses by peripheral blood mononuclear cells. Iron limitation-induced β-glucan masking depends on parallel signalling via the iron transceptor Ftr1 and the iron-responsive transcription factor Sef1, and the protein kinase a pathway. Our data reveal that C. albicans exploits a diverse range of specific host signals to trigger protective anticipatory responses against impending phagocytic attack and promote host colonisation.
Abstract.
Author URL.
Baldassarre M, Solano-Collado V, Balci A, Colamarino RA, Dambuza IM, Reid DM, Wilson HM, Brown GD, Mukhopadhyay S, Dougan G, et al (2019). The Rab32/BLOC-3 dependent pathway mediates host- defence against different pathogens in human macrophages.
Haider M, Dambuza IM, Asamaphan P, Stappers M, Reid D, Yamasaki S, Brown GD, Gow NAR, Erwig LP (2019). The pattern recognition receptors dectin-2, mincle, and FcRγ impact the dynamics of phagocytosis of Candida, Saccharomyces, Malassezia, and Mucor species.
PLoS One,
14(8).
Abstract:
The pattern recognition receptors dectin-2, mincle, and FcRγ impact the dynamics of phagocytosis of Candida, Saccharomyces, Malassezia, and Mucor species.
Phagocytosis is a receptor-mediated process critical to innate immune clearance of pathogens. It proceeds in a regulated sequence of stages: (a) migration of phagocytes towards pathogens, (b) recognition of PAMPs and binding through PRRs, (c) engulfment and internalisation into phagosomes, (d) phagosome maturation, and (e) killing of pathogen or host cells. However, little is known about the role that individual receptors play in these discrete stages in the recognition of fungal cells. In a previous study, we found that dectin-2 deficiency impacted some but not all stages of macrophage-mediated phagocytosis of Candida glabrata. Because the C-type lectin receptor dectin-2 critically requires coupling to the FcRγ chain for signalling, we hypothesised that this coupling may be important for regulating phagocytosis of fungal cargo. We therefore examined how deficiency in FcRγ itself or two receptors to which it couples (dectin-2 and mincle) impacts phagocytosis of six fungal organisms representing three different fungal taxa. Our data show that deficiency in these proteins impairs murine bone marrow-derived macrophage migration, engulfment, and phagosome maturation, but not macrophage survival. Therefore, FcRγ engagement with selective C-type lectin receptors (CLRs) critically affects the spatio-temporal dynamics of fungal phagocytosis.
Abstract.
Author URL.
2018
Salazar F, Brown GD (2018). A friendly danger.
Science,
362(6412), 292-293.
Abstract:
A friendly danger
Immune cell receptor DNGR-1 limits inflammatory tissue damage
Abstract.
Salazar F, Brown GD (2018). Antifungal innate immunity: a perspective from last 10 years.
Journal of Innate Immunity,
10, 373-397.
Abstract:
Antifungal innate immunity: a perspective from last 10 years
Fungal pathogens can rarely cause disease in immunocompetent individuals. However, commensal and normally non-pathogenic environmental fungi can cause life threatening infections in immunocompromised individuals. Over the last few decades, there has been a huge increase in the incidence of invasive opportunistic fungal infections along with a worrying increase in antifungal drug resistance. As a consequence, research focused on understanding the molecular and cellular basis of antifungal immunity has expanded tremendously in the last few years. This review will provide an overview of the most exciting recent advances in innate antifungal immunity, discoveries that are helping to pave the way for the development of new strategies that are desperately needed to combat these devastating diseases.
Abstract.
Brunel SF, Willment JA, Brown GD, Devereux G, Warris A (2018). Aspergillus-induced superoxide production by cystic fibrosis phagocytes is associated with disease severity.
ERS Monograph,
4(2).
Abstract:
Aspergillus-induced superoxide production by cystic fibrosis phagocytes is associated with disease severity
© ERS 2018. Aspergillus fumigatus infects up to 50% of cystic fibrosis (CF) patients and may play a role in progressive lung disease. As cystic fibrosis transmembrane conductance regulator is expressed in cells of the innate immune system, we hypothesised that impaired antifungal immune responses play a role in CF-related Aspergillus lung disease. Peripheral blood mononuclear cells, polymorphonuclear cells (PMN) and monocytes were isolated from blood samples taken from CF patients and healthy volunteers. Live-cell imaging and colorimetric assays were used to assess antifungal activity in vitro. Production of reactive oxygen species (ROS) was measured using luminol-induced chemiluminescence and was related to clinical metrics as collected by case report forms. CF phagocytes are as effective as those from healthy controls with regards to phagocytosis, killing and restricting germination of A. fumigatus conidia. ROS production by CF phagocytes was up to four-fold greater than healthy controls (p
Abstract.
Brown GD, Willment JA, Whitehead L (2018). C-type lectins in immunity and homeostasis.
Nature Reviews Immunology,
18(6), 374-389.
Abstract:
C-type lectins in immunity and homeostasis
The C-type lectins are a superfamily of proteins that recognize a broad repertoire of ligands and that regulate a diverse range of physiological functions. Most research attention has focused on the ability of C-type lectins to function in innate and adaptive antimicrobial immune responses, but these proteins are increasingly being recognized to have a major role in autoimmune diseases and to contribute to many other aspects of multicellular existence. Defects in these molecules lead to developmental and physiological abnormalities, as well as altered susceptibility to infectious and non-infectious diseases. In this Review, we present an overview of the roles of C-type lectins in immunity and homeostasis, with an emphasis on the most exciting recent discoveries.
Abstract.
Willment JA, Brown GD (2018). CLEC7A. In (Ed) Encyclopedia of Signaling Molecules, 1154-1161.
Pradhan A, Avelar GM, Bain JM, Childers DS, Larcombe DE, Netea MG, Shekhova E, Munro CA, Brown GD, Erwig LP, et al (2018). Hypoxia Promotes Immune Evasion by Triggering β-Glucan Masking on the Candida albicans Cell Surface via Mitochondrial and cAMP-Protein Kinase a Signaling.
mBio,
9(6).
Abstract:
Hypoxia Promotes Immune Evasion by Triggering β-Glucan Masking on the Candida albicans Cell Surface via Mitochondrial and cAMP-Protein Kinase a Signaling.
Organisms must adapt to changes in oxygen tension if they are to exploit the energetic benefits of reducing oxygen while minimizing the potentially damaging effects of oxidation. Consequently, organisms in all eukaryotic kingdoms display robust adaptation to hypoxia (low oxygen levels). This is particularly important for fungal pathogens that colonize hypoxic niches in the host. We show that adaptation to hypoxia in the major fungal pathogen of humans Candida albicans includes changes in cell wall structure and reduced exposure, at the cell surface, of β-glucan, a key pathogen-associated molecular pattern (PAMP). This leads to reduced phagocytosis by murine bone marrow-derived macrophages and decreased production of IL-10, RANTES, and TNF-α by peripheral blood mononuclear cells, suggesting that hypoxia-induced β-glucan masking has a significant effect upon C. albicans-host interactions. We show that hypoxia-induced β-glucan masking is dependent upon both mitochondrial and cAMP-protein kinase a (PKA) signaling. The decrease in β-glucan exposure is blocked by mutations that affect mitochondrial functionality (goa1Δ and upc2Δ) or that decrease production of hydrogen peroxide in the inner membrane space (sod1Δ). Furthermore, β-glucan masking is enhanced by mutations that elevate mitochondrial reactive oxygen species (aox1Δ). The β-glucan masking defects displayed by goa1Δ and upc2Δ cells are suppressed by exogenous dibutyryl-cAMP. Also, mutations that inactivate cAMP synthesis (cyr1Δ) or PKA (tpk1Δ tpk2Δ) block the masking phenotype. Our data suggest that C. albicans responds to hypoxic niches by inducing β-glucan masking via a mitochondrial cAMP-PKA signaling pathway, thereby modulating local immune responses and promoting fungal colonization.IMPORTANCE Animal, plant, and fungal cells occupy environments that impose changes in oxygen tension. Consequently, many species have evolved mechanisms that permit robust adaptation to these changes. The fungal pathogen Candida albicans can colonize hypoxic (low oxygen) niches in its human host, such as the lower gastrointestinal tract and inflamed tissues, but to colonize its host, the fungus must also evade local immune defenses. We reveal, for the first time, a defined link between hypoxic adaptation and immune evasion in C. albicans As this pathogen adapts to hypoxia, it undergoes changes in cell wall structure that include masking of β-glucan at its cell surface, and it becomes better able to evade phagocytosis by innate immune cells. We also define the signaling mechanisms that mediate hypoxia-induced β-glucan masking, showing that they are dependent on mitochondrial signaling and the cAMP-protein kinase pathway. Therefore, hypoxia appears to trigger immune evasion in this fungal pathogen.
Abstract.
Author URL.
Stappers MHT, Clark AE, Aimanianda V, Bidula S, Reid DM, Asamaphan P, Hardison SE, Dambuza IM, Valsecchi I, Kerscher B, et al (2018). Recognition of DHN-melanin by a C-type lectin receptor is required for immunity to Aspergillus.
Nature,
555(7696), 382-386.
Abstract:
Recognition of DHN-melanin by a C-type lectin receptor is required for immunity to Aspergillus
Resistance to infection is critically dependent on the ability of pattern recognition receptors to recognize microbial invasion and induce protective immune responses. One such family of receptors are the C-type lectins, which are central to antifungal immunity. These receptors activate key effector mechanisms upon recognition of conserved fungal cell-wall carbohydrates. However, several other immunologically active fungal ligands have been described; these include melanin, for which the mechanism of recognition is hitherto undefined. Here we identify a C-type lectin receptor, melanin-sensing C-type lectin receptor (MelLec), that has an essential role in antifungal immunity through recognition of the naphthalene-diol unit of 1,8-dihydroxynaphthalene (DHN)-melanin. MelLec recognizes melanin in conidial spores of Aspergillus fumigatus as well as in other DHN-melanized fungi. MelLec is ubiquitously expressed by CD31+ endothelial cells in mice, and is also expressed by a sub-population of these cells that co-express epithelial cell adhesion molecule and are detected only in the lung and the liver. In mouse models, MelLec was required for protection against disseminated infection with A. fumigatus. In humans, MelLec is also expressed by myeloid cells, and we identified a single nucleotide polymorphism of this receptor that negatively affected myeloid inflammatory responses and significantly increased the susceptibility of stem-cell transplant recipients to disseminated Aspergillus infections. MelLec therefore recognizes an immunologically active component commonly found on fungi and has an essential role in protective antifungal immunity in both mice and humans.
Abstract.
Gow NAR, Amin T, McArdle K, Brown AJP, Brown GD, Warris A, the WTSA-MMFI Consortium (2018). Strategic Research Funding: a Success Story for Medical Mycology.
Trends in Microbiology,
26(10), 811-813.
Abstract:
Strategic Research Funding: a Success Story for Medical Mycology
The Wellcome Trust Strategic Award in Medical Mycology and Fungal Immunology is a unique investment that aimed to bolster capacity, training and research activity throughout the UK. This article summarises the rationale for collective collaboration of multiple institutions to achieve synergies and address a common medical problem.
Abstract.
2017
Brunel SF, Willment JA, Brown GD, Devereux G, Warris A (2017). 79 Excessive reactive oxygen species production by cystic fibrosis phagocytes against Aspergillus fumigatus is adversely associated with number of clinical exacerbations and lung function. Journal of Cystic Fibrosis, 16, s84-s85.
Wagener J, Maccallum DM, Brown GD, Gow NAR (2017). Candida albicans chitin increases arginase-1 activity in human macrophages, with an impact on macrophage antimicrobial functions.
mBio,
8(1).
Abstract:
Candida albicans chitin increases arginase-1 activity in human macrophages, with an impact on macrophage antimicrobial functions
The opportunistic human fungal pathogen Candida albicans can cause a variety of diseases, ranging from superficial mucosal infections to life-threatening systemic infections. Phagocytic cells of the innate immune response, such as neutrophils and macrophages, are important first-line responders to an infection and generate reactive oxygen and nitrogen species as part of their protective antimicrobial response. During an infection, host cells generate nitric oxide through the enzyme inducible nitric oxide synthase (iNOS) to kill the invading pathogen. Inside the phagocyte, iNOS competes with the enzyme arginase-1 for a common substrate, the amino acidL-arginine. Several pathogenic species, including bacteria and parasitic protozoans, actively modulate the production of nitric oxide by inducing their own arginases or the host’s arginase activity to prevent the conversion ofL-arginine to nitric oxide. We report here that C. albicans blocks nitric oxide production in human-monocyte-derived macrophages by induction of host arginase activity. We further determined that purified chitin (a fungal cell wall polysaccharide) and increased chitin exposure at the fungal cell wall surface induces this host arginase activity. Blocking the C. albicans-induced arginase activity with the arginase-specific substrate inhibitor Nω-hydroxy-nor-arginine (nor-NOHA) or the chitinase inhibitor bisdionin F restored nitric oxide production and increased the efficiency of fungal killing. Moreover, we determined that C. albicans influences macrophage polarization from a classically activated phenotype toward an alternatively activated phenotype, thereby reducing antimicrobial functions and mediating fungal survival. Therefore, C. albicans modulatesL-arginine metabolism in macrophages during an infection, potentiating its own survival. IMPORTANCE the availability and metabolism of amino acids are increasingly recognized as crucial regulators of immune functions. In acute infections, the conversion of the “conditionally essential” amino acid L-arginine by the inducible nitric oxide synthase to nitric oxide is a resistance factor that is produced by the host to fight pathogens. Manipulation of these host defense mechanisms by the pathogen can be key to successful host invasion. We show here that the human opportunistic fungal pathogen Candida albicans influences L-arginine availability for nitric oxide production by induction of the substrate-competing host enzyme arginase-1. This led to a reduced production of nitric oxide and, moreover, reduced eradication of the fungus by human macrophages. We demonstrate that blocking of host arginase-1 activity restored nitric oxide production and increased the killing potential of macrophages. These results highlight the therapeutic potential of L-arginine metabolism in fungal diseases.
Abstract.
Dambuza IM, Levitz SM, Netea MG, Brown GD (2017). Fungal recognition and host defense mechanisms. In (Ed)
The Fungal Kingdom, 887-902.
Abstract:
Fungal recognition and host defense mechanisms
Abstract.
Stappers MHT, Brown GD (2017). Host immune responses during infections with Candida albicans. In (Ed)
Candida albicans: Cellular and Molecular Biology: Second Edition, 145-183.
Abstract:
Host immune responses during infections with Candida albicans
Abstract.
Brown GD, Crocker PR (2017). Lectin receptors expressed on myeloid cells. In (Ed)
Myeloid Cells in Health and Disease: a Synthesis, 455-483.
Abstract:
Lectin receptors expressed on myeloid cells
Abstract.
Whitehead L, Brown GD (2017). Pattern Recognition Receptors. In (Ed) Inflammation - from Molecular and Cellular Mechanisms to the Clinic, 175-216.
Dambuza IM, Drake T, Chapuis A, Taylor-Smith L, LeGrave N, Rasmussen T, Fisher MC, Bicanic T, Harrison TS, Jaspars M, et al (2017). The Cryptococcus neoformans Titan cell is an inducible and regulated morphotype underlying pathogenesis.
2016
Asamaphan P, Willment JA, Brown GD (2016). Dectin-1 (CLEC7A, BGR, CLECSF12). In (Ed)
C-Type Lectin Receptors in Immunity, 51-63.
Abstract:
Dectin-1 (CLEC7A, BGR, CLECSF12)
Abstract.
Ballou ER, Avelar GM, Childers DS, Mackie J, Bain JM, Wagener J, Kastora SL, Panea MD, Hardison SE, Walker LA, et al (2016). Lactate signalling regulates fungal β-glucan masking and immune evasion.
Nature Microbiology,
2Abstract:
Lactate signalling regulates fungal β-glucan masking and immune evasion
As they proliferate, fungi expose antigens at their cell surface that are potent stimulators of the innate immune response, and yet the commensal fungus Candida albicans is able to colonize immuno competent individuals. We show that C. albicans may evade immune detection by presenting a moving immunological target. We report that the exposure of β-glucan, a key pathogen-associated molecular pattern (PAMP) located at the cell surface of C. albicans and other pathogenic Candida species, is modulated in response to changes in the carbon source. Exposure to lactate induces β-glucan masking in C. albicans via a signalling pathway that has recruited an evolutionarily conserved receptor (Gpr1) and transcriptional factor (Crz1) from other well-characterized pathways. In response to lactate, these regulators control the expression of cell-wall-related genes that contribute to β-glucan masking. This represents the first description of active PAMP masking by a Candida species, a process that reduces the visibility of the fungus to the immune system.
Abstract.
Redelinghuys P, Whitehead L, Augello A, Drummond RA, Levesque JM, Vautier S, Reid DM, Kerscher B, Taylor JA, Nigrovic PA, et al (2016). MICL controls inflammation in rheumatoid arthritis.
Annals of the Rheumatic Diseases,
75(7), 1386-1391.
Abstract:
MICL controls inflammation in rheumatoid arthritis
Background Myeloid inhibitory C-type lectin-like receptor (MICL, Clec12A) is a C-type lectin receptor (CLR) expressed predominantly by myeloid cells. Previous studies have suggested that MICL is involved in controlling inflammation. Objective to determine the role of this CLR in inflammatory pathology using Clec12A-/- mice. Methods Clec12A-/- mice were generated commercially and primarily characterised using the collagen antibody-induced arthritis (CAIA) model. Mechanisms and progress of disease were characterised by clinical scoring, histology, flow cytometry, irradiation bone-marrow chimera generation, administration of blocking antibodies and in vivo imaging. Characterisation of MICL in patients with rheumatoid arthritis (RA) was determined by immunohistochemistry and single nucleotide polymorphism analysis. Anti-MICL antibodies were detected in patient serum by ELISA and dot-blot analysis. Results MICL-deficient animals did not present with pan-immune dysfunction, but exhibited markedly exacerbated inflammation during CAIA, owing to the inappropriate activation of myeloid cells. Polymorphisms of MICL were not associated with disease in patients with RA, but this CLR was the target of autoantibodies in a subset of patients with RA. In wild-type mice the administration of such antibodies recapitulated the Clec12A-/- phenotype. Conclusions MICL plays an essential role in regulating inflammation during arthritis and is an autoantigen in a subset of patients with RA. These data suggest an entirely new mechanism underlying RA pathogenesis, whereby the threshold of myeloid cell activation can be modulated by autoantibodies that bind to cell membrane-expressed inhibitory receptors.
Abstract.
Kerscher B, Wilson GJ, Reid DM, Mori D, Taylor JA, Besra GS, Yamasaki S, Willment JA, Brown GD (2016). Mycobacterial receptor, Clec4d (CLECSF8, MCL), is coregulated with Mincle and upregulated on mouse myeloid cells following microbial challenge.
European Journal of Immunology,
46(2), 381-389.
Abstract:
Mycobacterial receptor, Clec4d (CLECSF8, MCL), is coregulated with Mincle and upregulated on mouse myeloid cells following microbial challenge
The C-type lectin receptor (CTLR), Clec4d (MCL, CLECSF8), is a member of the Dectin-2 cluster of CTLRs, which also includes the related receptors Mincle and Dectin-2. Like Mincle, Clec4d recognizes mycobacterial cord factor, trehalose dimycolate, and we recently demonstrated its key role in anti-mycobacterial immunity in mouse and man. Here, we characterized receptor expression in naïve mice, under inflammatory conditions, and during Mycobacterium bovis BCG infection using newly generated monoclonal antibodies. In naïve mice, Clec4d was predominantly expressed on myeloid cells within the peritoneal cavity, blood, and bone marrow. Unexpectedly, basal expression of Clec4d was very low on leukocytes in the lung. However, receptor expression was significantly upregulated on pulmonary myeloid cells during M. bovis BCG infection. Moreover, Clec4d expression could be strongly induced in vitro and in vivo by various microbial stimuli, including TLR agonists, but not exogenous cytokines. Notably, we show that Clec4d requires association with the signaling adaptor FcRγ and Mincle, but not Dectin-2, for surface expression. In addition, we provide evidence that Clec4d and Mincle, but not Dectin-2, are interdependently coregulated during inflammation and infection. These data show that Clec4d is an inducible myeloid-expressed CTLR in mice, whose expression is tightly linked to that of Mincle.
Abstract.
Kerscher B, Dambuza IM, Christofi M, Reid DM, Yamasaki S, Willment JA, Brown GD (2016). Signalling through MyD88 drives surface expression of the mycobacterial receptors MCL (Clecsf8, Clec4d) and Mincle (Clec4e) following microbial stimulation.
Microbes and Infection,
18(7-8), 505-509.
Abstract:
Signalling through MyD88 drives surface expression of the mycobacterial receptors MCL (Clecsf8, Clec4d) and Mincle (Clec4e) following microbial stimulation
The heterodimeric mycobacterial receptors, macrophage C-type lectin (MCL) and macrophage inducible C-type lectin (Mincle), are upregulated at the cell surface following microbial challenge, but the mechanisms underlying this response are unclear. Here we report that microbial stimulation triggers Mincle expression through the myeloid differentiation primary response gene 88 (MyD88) pathway; a process that does not require MCL. Conversely, we show that MCL is constitutively expressed but retained intracellularly until Mincle is induced, whereupon the receptors form heterodimers which are translocated to the cell surface. Thus this “two-step” model for induction of these key receptors provides new insights into the underlying mechanisms of anti-mycobacterial immunity.
Abstract.
2015
Dambuza IM, Brown GD (2015). C-type lectins in immunity: recent developments.
CURRENT OPINION IN IMMUNOLOGY,
32, 21-27.
Author URL.
Kashem SW, Igyarto BZ, Gerami-Nejad M, Kumamoto Y, Mohammed J, Jarrett E, Drummond RA, Zurawski SM, Zurawski G, Berman J, et al (2015). Candida albicans Morphology and Dendritic Cell Subsets Determine T Helper Cell Differentiation.
IMMUNITY,
42(2), 356-366.
Author URL.
Vautier S, Drummond RA, Chen K, Murray GI, Kadosh D, Brown AJP, Gow NAR, Maccallum DM, Kolls JK, Brown GD, et al (2015). Candida albicans colonization and dissemination from the murine gastrointestinal tract: the influence of morphology and Th17 immunity.
Cellular Microbiology,
17(4), 445-450.
Abstract:
Candida albicans colonization and dissemination from the murine gastrointestinal tract: the influence of morphology and Th17 immunity
The ability of Candida albicans to cause disease is associated with its capacity to undergo morphological transition between yeast and filamentous forms, but the role of morphology in colonization and dissemination from the gastrointestinal (GI) tract remains poorly defined. To explore this, we made use of wild-type and morphological mutants of C.albicans in an established model of GI tract colonization, induced following antibiotic treatment of mice. Our data reveal that GI tract colonization favours the yeast form of C.albicans, that there is constitutive low level systemic dissemination in colonized mice that occurs irrespective of fungal morphology, and that colonization is not controlled by Th17 immunity in otherwise immunocompetent animals. These data provide new insights into the mechanisms of pathogenesis and commensalism of C.albicans, and have implications for our understanding of human disease. Candida albicans is a commensal of the human gastrointestinal (GI) tract but can also spread from this site to cause systemic disease following immune perturbation. Here, using morphologically-locked strains we show that although the yeast form is favoured in the GI tract, both the yeast and hyphal forms can disseminate from this site to distal tissues in healthy animals. Finally, we show that Th17 immunity has no role in fungal colonisation or dissemination from the GI tract.
Abstract.
Kerscher B, Wilson GJ, Reid DM, Yamasaki S, Willment JA, Brown GD (2015). Characterisation of the murine C-type lectin receptor CLECSF8 (MCL) reveals its expression on cells of the monocyte/neutrophil lineages and an inter-dependence with Mincle, but not Dectin-2. Journal of Inflammation, 12(Suppl 1).
Hadebe S, Kirstein F, Fierens K, Chen K, Drummond RA, Vautier S, Sajaniemi S, Murray G, Williams DL, Redelinghuys P, et al (2015). Correction: Microbial Ligand Costimulation Drives Neutrophilic Steroid-Refractory Asthma. PLOS ONE, 10(9).
Rieber N, Singh A, Oez H, Carevic M, Bouzani M, Amich J, Ost M, Ye Z, Ballbach M, Schaefer I, et al (2015). Pathogenic Fungi Regulate Immunity by Inducing Neutrophilic Myeloid-Derived Suppressor Cells.
CELL HOST & MICROBE,
17(4), 507-514.
Author URL.
Wilson GJ, Marakalala MJ, Hoving JC, Van Laarhoven A, Drummond RA, Kerscher B, Keeton R, Van De Vosse E, Ottenhoff THM, Plantinga TS, et al (2015). The C-type lectin receptor CLECSF8/CLEC4D is a key component of anti-mycobacterial immunity.
Cell Host and Microbe,
17(2), 252-259.
Abstract:
The C-type lectin receptor CLECSF8/CLEC4D is a key component of anti-mycobacterial immunity
The interaction of microbes with pattern recognition receptors (PRRs) is essential for protective immunity. While many PRRs that recognize mycobacteria have been identified, none is essentially required for host defense in vivo. Here, we have identified the C-type lectin receptor CLECSF8 (CLEC4D, MCL) as a key molecule in anti-mycobacterial host defense. Clecsf8-/- mice exhibit higher bacterial burdens and increased mortality upon M. tuberculosis infection. Additionally, Clecsf8 deficiency is associated with exacerbated pulmonary inflammation, characterized by enhanced neutrophil recruitment. Clecsf8-/- mice show reduced mycobacterial uptake by pulmonary leukocytes, but infection with opsonized bacteria can restore this phagocytic defect as well as decrease bacterial burdens. Notably, a CLECSF8 polymorphism identified in humans is associated with an increased susceptibility to pulmonary tuberculosis. We conclude that CLECSF8 plays a non-redundant role in anti-mycobacterial immunity in mouse and in man.
Abstract.
2014
Armstrong-James D, Meintjes G, Brown GD (2014). A neglected epidemic: fungal infections in HIV/AIDS.
TRENDS IN MICROBIOLOGY,
22(3), 120-127.
Author URL.
Brown GD, Meintjes G, Kolls JK, Gray C, Horsnell W, Working Group from the EMBO-AIDS Related Mycoses Workshop, Achan B, Alber G, Aloisi M, Armstrong-James D, et al (2014). AIDS-related mycoses: the way forward.
Trends Microbiol,
22(3), 107-109.
Abstract:
AIDS-related mycoses: the way forward.
The contribution of fungal infections to the morbidity and mortality of HIV-infected individuals is largely unrecognized. A recent meeting highlighted several priorities that need to be urgently addressed, including improved epidemiological surveillance, increased availability of existing diagnostics and drugs, more training in the field of medical mycology, and better funding for research and provision of treatment, particularly in developing countries.
Abstract.
Author URL.
Brown G (2014). C-type lectins in anti-fungal immunity.
Author URL.
Bain JM, Louw J, Lewis LE, Okai B, Walls CA, Ballou ER, Walker LA, Reid D, Munro CA, Brown AJP, et al (2014). Candida albicans hypha formation and mannan masking of β-Glucan inhibit macrophage phagosome maturation.
mBio,
5(6).
Abstract:
Candida albicans hypha formation and mannan masking of β-Glucan inhibit macrophage phagosome maturation
Candida albicans is a major life-threatening human fungal pathogen in the immunocompromised host. Host defense against systemic Candida infection relies heavily on the capacity of professional phagocytes of the innate immune system to ingest and destroy fungal cells. A number of pathogens, including C. albicans, have evolved mechanisms that attenuate the efficiency of phagosome-mediated inactivation, promoting their survival and replication within the host. Here we visualize hostpathogen interactions using live-cell imaging and show that viable, but not heat- or UV-killed C. albicans cells profoundly delay phagosome maturation in macrophage cell lines and primary macrophages. The ability of C. albicans to delay phagosome maturation is dependent on cell wall composition and fungal morphology. Loss of cell wall O-mannan is associated with enhanced acquisition of phagosome maturation markers, distinct changes in Rab GTPase acquisition by the maturing phagosome, impaired hyphal growth within macrophage phagosomes, profound changes in macrophage actin dynamics, and ultimately a reduced ability of fungal cells to escape from macrophage phagosomes. The loss of cell wall O-mannan leads to exposure of β-glucan in the inner cell wall, facilitating recognition by Dectin-1, which is associated with enhanced phagosome maturation.
Abstract.
Drummond RA, Wallace C, Reid DM, Way SS, Kaplan DH, Brown GD (2014). Cutting Edge: Failure of Antigen-Specific CD4(+) T Cell Recruitment to the Kidney during Systemic Candidiasis.
JOURNAL OF IMMUNOLOGY,
193(11), 5381-5385.
Author URL.
Loures FV, Araujo EF, Feriotti C, Bazan SB, Costa TA, Brown GD, Calich VLG (2014). Dectin-1 Induces M1 Macrophages and Prominent Expansion of CD8(+)IL-17(+) Cells in Pulmonary Paracoccidioidomycosis.
JOURNAL OF INFECTIOUS DISEASES,
210(5), 762-773.
Author URL.
Rochereau N, Drocourt D, Perouzel E, Pavot V, Redelinghuys P, Brown GD, Roblin X, Verrier B, Genin C, Corthesy B, et al (2014). Essential role of Dectin-1 in intestinal M cell-mediated reverse transcytosis of SIgA-antigen complexes.
Author URL.
Wagener J, Malireddi RKS, Lenardon MD, Köberle M, Vautier S, MacCallum DM, Biedermann T, Schaller M, Netea MG, Kanneganti TD, et al (2014). Fungal Chitin Dampens Inflammation through IL-10 Induction Mediated by NOD2 and TLR9 Activation.
PLoS Pathogens,
10(4).
Abstract:
Fungal Chitin Dampens Inflammation through IL-10 Induction Mediated by NOD2 and TLR9 Activation
Chitin is an essential structural polysaccharide of fungal pathogens and parasites, but its role in human immune responses remains largely unknown. It is the second most abundant polysaccharide in nature after cellulose and its derivatives today are widely used for medical and industrial purposes. We analysed the immunological properties of purified chitin particles derived from the opportunistic human fungal pathogen Candida albicans, which led to the selective secretion of the anti-inflammatory cytokine IL-10. We identified NOD2, TLR9 and the mannose receptor as essential fungal chitin-recognition receptors for the induction of this response. Chitin reduced LPS-induced inflammation in vivo and may therefore contribute to the resolution of the immune response once the pathogen has been defeated. Fungal chitin also induced eosinophilia in vivo, underpinning its ability to induce asthma. Polymorphisms in the identified chitin receptors, NOD2 and TLR9, predispose individuals to inflammatory conditions and dysregulated expression of chitinases and chitinase-like binding proteins, whose activity is essential to generate IL-10-inducing fungal chitin particles in vitro, have also been linked to inflammatory conditions and asthma. Chitin recognition is therefore critical for immune homeostasis and is likely to have a significant role in infectious and allergic disease.Authors Summary:Chitin is the second most abundant polysaccharide in nature after cellulose and an essential component of the cell wall of all fungal pathogens. The discovery of human chitinases and chitinase-like binding proteins indicates that fungal chitin is recognised by cells of the human immune system, shaping the immune response towards the invading pathogen. We show that three immune cell receptors- the mannose receptor, NOD2 and TLR9 recognise chitin and act together to mediate an anti-inflammatory response via secretion of the cytokine IL-10. This mechanism may prevent inflammation-based damage during fungal infection and restore immune balance after an infection has been cleared. By increasing the chitin content in the cell wall pathogenic fungi may influence the immune system in their favour, by down-regulating protective inflammatory immune responses. Furthermore, gene mutations and dysregulated enzyme activity in the described chitin recognition pathway are implicated in inflammatory conditions such as Crohn's Disease and asthma, highlighting the importance of the discovered mechanism in human health. © 2014 Wagener et al.
Abstract.
Rieber N, Singh A, Carevic M, Oez H-H, Bouzani M, Speckmann C, Grimbacher B, Ruland J, Brown GD, Beilhack A, et al (2014). Fungi undermine host defence by inducing CXCR4+granulocytic myeloid derived suppressor cells.
Author URL.
Brown AJP, Brown GD, Netea MG, Gow NAR (2014). Metabolism impacts upon candida immunogenicity and pathogenicity at multiple levels.
Trends in Microbiology,
22(11), 614-622.
Abstract:
Metabolism impacts upon candida immunogenicity and pathogenicity at multiple levels
Metabolism is integral to the pathogenicity of Candida albicans, a major fungal pathogen of humans. As well as providing the platform for nutrient assimilation and growth in diverse host niches, metabolic adaptation affects the susceptibility of C. albicans to host-imposed stresses and antifungal drugs, the expression of key virulence factors, and fungal vulnerability to innate immune defences. These effects, which are driven by complex regulatory networks linking metabolism, morphogenesis, stress adaptation, and cell wall remodelling, influence commensalism and infection. Therefore, current concepts of Candida-host interactions must be extended to include the impact of metabolic adaptation upon pathogenicity and immunogenicity.
Abstract.
Hadebe S, Brown G, Redelinghuys P, Drummond R, Fierens K, Lambrecht B, Brombacher F, Kirstein F, Vautier S (2014). Microbial PAMP co-stimulation initiates neutrophilic steroid resistant asthma.
Author URL.
Branzk N, Lubojemska A, Hardison SE, Wang Q, Gutierrez MG, Brown GD, Papayannopoulos V (2014). Microbial size regulates neutrophil responses for efficient immune defence and minimal host damage.
Author URL.
Ifrim DC, Bain JM, Reid DM, Oosting M, Verschueren I, Gow NAR, van Krieken JH, Brown GD, Kullberg BJ, Joosten LAB, et al (2014). Role of dectin-2 for host defense against systemic infection with Candida glabrata.
Infection and Immunity,
82(3), 1064-1073.
Abstract:
Role of dectin-2 for host defense against systemic infection with Candida glabrata
Although Candida glabrata is an important pathogenic Candida species, relatively little is known about its innate immune recognition. Here, we explore the potential role of Dectin-2 for host defense against C. glabrata. Dectin-2-deficient (Dectin-2-/-) mice were found to be more susceptible to C. glabrata infections, showing a defective fungal clearance in kidneys but not in the liver. The increased susceptibility to infection was accompanied by lower production of T helper 1 (Th1) and Th17-derived cytokines by splenocytes of Dectin-2-/- mice, while macrophage-derived cytokines were less affected. These defects were associated with a moderate yet significant decrease in phagocytosis of the fungus by the Dectin-2-/- macrophages and neutrophils. Neutrophils of Dectin-2-/- mice also displayed lower production of reactive oxygen species (ROS) upon challenge with opsonized C. glabrata or C. albicans. This study suggests that Dectin-2 is important in host defense against C. glabrata and provides new insights into the host defense mechanisms against this important fungal pathogen. © 2014, American Society for Microbiology.
Abstract.
Hoving JC, Wilson GJ, Brown GD (2014). Signalling C-Type lectin receptors, microbial recognition and immunity.
CELLULAR MICROBIOLOGY,
16(2), 185-194.
Author URL.
Teixeira de Sousa MDG, Jr BW, Spina R, Lota PR, Valente NS, Brown GD, Criado PR, Benard G (2014). Topical Application of Imiquimod as a Treatment for Chromoblastomycosis.
CLINICAL INFECTIOUS DISEASES,
58(12), 1734-1737.
Author URL.
Hadebe SG, Kirstein F, Fierens K, Murray G, Redelinghuys P, Lambrecht B, Kolls J, Brombacher F, Brown GD (2014). Understanding the pathogenesis of severe asthma.
Author URL.
Roug AS, Larsen HO, Nederby L, Just T, Brown G, Nyvold CG, Ommen HB, Hokland P (2014). hMICL and CD123 in combination with a CD45/CD34/CD117 backbone - a universal marker combination for the detection of minimal residual disease in acute myeloid leukaemia.
BRITISH JOURNAL OF HAEMATOLOGY,
164(2), 212-222.
Author URL.
2013
Watson CJ, Fairley CK, Grando D, Garland SM, Myers SP, Pirotta M (2013). Associations with asymptomatic colonization with candida in women reporting past vaginal candidiasis: an observational study.
EUROPEAN JOURNAL OF OBSTETRICS & GYNECOLOGY AND REPRODUCTIVE BIOLOGY,
169(2), 376-379.
Author URL.
Plato A, Willment JA, Brown GD (2013). C-Type lectin-like receptors of the dectin-1 cluster: Ligands and signaling pathways.
International Reviews of Immunology,
32(2), 134-156.
Abstract:
C-Type lectin-like receptors of the dectin-1 cluster: Ligands and signaling pathways
Innate immunity is constructed around genetically encoded receptors that survey the intracellular and extracellular environments for signs of invading microorganisms. These receptors recognise the invader and through complex intracellular networks of molecular signaling, they destroy the threat whilst instructing effective adaptive immune responses. Many of these receptors, like the Toll-like receptors in particular, are well-known for their ability to mediate downstream responses upon recognition of exogenous or endogenous ligands; however, the emerging family known as the C-type lectin-like receptors contains many members that have a huge impact on immune and homeostatic regulation. of particular interest here are the C-type lectin-like receptors that make up the Dectin-1 cluster and their intracellular signaling motifs that mediate their functions. In this review, we aim to draw together current knowledge of ligands, motifs and signaling pathways, present downstream of Dectin-1 cluster receptors, and discuss how these dictate their role within biological systems. © 2013 Informa Healthcare USA, Inc.
Abstract.
Wagener J, Malireddi RKS, Lenardon MD, Koberle M, Vautier S, MacCallum DM, Alvarez FJ, Biedermann T, Schaller M, Netea MG, et al (2013). Chitin recognition in fungal infections and its impact on the immune response.
Author URL.
Marakalala MJ, Vautier S, Potrykus J, Walker LA, Shepardson KM, Hopke A, Mora-Montes HM, Kerrigan A, Netea MG, Murray GI, et al (2013). Correction: Differential Adaptation of Candida albicans in Vivo Modulates Immune Recognition by Dectin-1. PLOS Pathogens, 9(10).
Suram S, Silveira LJ, Mahaffey S, Brown GD, Bonventre JV, Williams DL, Gow NAR, Bratton DL, Murphy RC, Leslie CC, et al (2013). Cytosolic Phospholipase A<inf>2</inf>α and Eicosanoids Regulate Expression of Genes in Macrophages Involved in Host Defense and Inflammation.
PLoS ONE,
8(7).
Abstract:
Cytosolic Phospholipase A2α and Eicosanoids Regulate Expression of Genes in Macrophages Involved in Host Defense and Inflammation
The role of Group IVA cytosolic phospholipase A2 (cPLA2α) activation in regulating macrophage transcriptional responses to Candida albicans infection was investigated. cPLA2α releases arachidonic acid for the production of eicosanoids. In mouse resident peritoneal macrophages, prostacyclin, prostaglandin E2 and leukotriene C4 were produced within minutes of C. albicans addition before cyclooxygenase 2 expression. The production of TNFα was lower in C. albicans-stimulated cPLA2α+/+ than cPLA2α-/- macrophages due to an autocrine effect of prostaglandins that increased cAMP to a greater extent in cPLA2α+/+ than cPLA2α-/- macrophages. For global insight, differential gene expression in C. albicans-stimulated cPLA2α+/+ and cPLA2α-/- macrophages (3 h) was compared by microarray. cPLA2α+/+ macrophages expressed 86 genes at lower levels and 181 genes at higher levels than cPLA2α-/- macrophages (≥2-fold, p
Abstract.
Drummond RA, Kaplan D, Reid DM, Brown GD (2013). Dectin-1 is required for normal CD4(+) T-cell function in the murine GI tract during systemic candidiasis.
Author URL.
Marakalala MJ, Williams DL, Hoving JC, Engstad R, Netea MG, Brown GD (2013). Dectin-1 plays a redundant role in the immunomodulatory activities of beta-glucan-rich ligands in vivo.
MICROBES AND INFECTION,
15(6-7), 511-515.
Author URL.
Marakalala MJ, Vautier S, Potrykus J, Walker LA, Shepardson KM, Hopke A, Mora-Montes HM, Kerrigan A, Netea MG, Murray GI, et al (2013). Differential Adaptation of Candida albicans in Vivo Modulates Immune Recognition by Dectin-1.
PLoS Pathogens,
9(4).
Abstract:
Differential Adaptation of Candida albicans in Vivo Modulates Immune Recognition by Dectin-1
The β-glucan receptor Dectin-1 is a member of the C-type lectin family and functions as an innate pattern recognition receptor in antifungal immunity. In both mouse and man, Dectin-1 has been found to play an essential role in controlling infections with Candida albicans, a normally commensal fungus in man which can cause superficial mucocutaneous infections as well as life-threatening invasive diseases. Here, using in vivo models of infection, we show that the requirement for Dectin-1 in the control of systemic Candida albicans infections is fungal strain-specific; a phenotype that only becomes apparent during infection and cannot be recapitulated in vitro. Transcript analysis revealed that this differential requirement for Dectin-1 is due to variable adaptation of C. albicans strains in vivo, and that this results in substantial differences in the composition and nature of their cell walls. In particular, we established that differences in the levels of cell-wall chitin influence the role of Dectin-1, and that these effects can be modulated by antifungal drug treatment. Our results therefore provide substantial new insights into the interaction between C. albicans and the immune system and have significant implications for our understanding of susceptibility and treatment of human infections with this pathogen. © 2013 Marakalala et al.
Abstract.
Lim E-K, Mitchell PJ, Brown N, Drummond RA, Brown GD, Kaye PM, Bowles DJ (2013). Regiospecific Methylation of a Dietary Flavonoid Scaffold Selectively Enhances IL-1 beta Production following Toll-like Receptor 2 Stimulation in THP-1 Monocytes.
JOURNAL OF BIOLOGICAL CHEMISTRY,
288(29), 21126-21135.
Author URL.
Drummond RA, Brown GD (2013). Signalling C-Type Lectins in Antimicrobial Immunity.
PLOS PATHOGENS,
9(7).
Author URL.
Kerscher B, Willment JA, Brown GD (2013). The Dectin-2 family of C-type lectin-like receptors: an update.
International Immunology,
25(5), 271-277.
Abstract:
The Dectin-2 family of C-type lectin-like receptors: an update
Myeloid and non-myeloid cells express members of the C-type lectin-like receptor (CTLR) family, which mediate crucial cellular functions during immunity and homeostasis. of relevance here is the dendritic cell-associated C-type lectin-2 (Dectin-2) family of CTLRs, which includes blood dendritic cell antigen 2 (BDCA-2), dendritic cell immunoactivating receptor (DCAR), dendritic cell immu no receptor (DCIR), Dectin-2, C-type lectin superfamily 8 (CLECSF8) and macrophage-inducible C-type lectin (Mincle). These CTLRs possess a single extracellular conserved C-type lectin-like domain and are capable of mediating intracellular signalling either directly, through integral signalling domains, or indirectly, by associating with signalling adaptor molecules. These receptors recognize a diverse range of endogenous and exogenous ligands, and can function as pattern recognition receptors for several classes of pathogens including fungi, bacteria and parasites, driving both innate and adaptive immunity. In this review, we summarize our knowledge of each of these receptors, highlighting the exciting discoveries that have been made in recent years. © the Japanese Society for Immunology. 2013.
Abstract.
Nederby L, Hokland P, Brown G, Hansen M, Nyvold CG, Roug AS (2013). Unraveling the Leukemic Nature of hMICL and CD123 Expressing Cells in Acute Myeloid Leukemia.
Author URL.
2012
Karsten CM, Pandey MK, Figge J, Kilchenstein R, Taylor PR, Rosas M, McDonald JU, Orr SJ, Berger M, Petzold D, et al (2012). Anti-inflammatory activity of IgG1 mediated by Fc galactosylation and association of Fc gamma RIIB and dectin-1.
NATURE MEDICINE,
18(9), 1401-+.
Author URL.
Vautier S, MacCallum DM, Brown GD (2012). C-type lectin receptors and cytokines in fungal immunity.
CYTOKINE,
58(1), 89-99.
Author URL.
Hardison SE, Brown GD (2012). C-type lectin receptors orchestrate antifungal immunity.
NATURE IMMUNOLOGY,
13(9), 817-822.
Author URL.
Kilchenstein R, Karsten CM, Figge J, Brown GD, Koehl J (2012). C5a drives the cutaneous lesions in experimental epidermolysis bullosa acquisita, which can be targeted by highly galactosylated IgG1 immune complexes.
Author URL.
Willment JA, Brown GD (2012). CLEC7A. In (Ed) Encyclopedia of Signaling Molecules, 425-431.
Faro-Trindade I, Willment JA, Kerrigan AM, Redelinghuys P, Hadebe S, Reid DM, Srinivasan N, Wainwright H, Lang DM, Steele C, et al (2012). Characterisation of innate fungal recognition in the lung.
PLoS ONE,
7(4).
Abstract:
Characterisation of innate fungal recognition in the lung
The innate recognition of fungi by leukocytes is mediated by pattern recognition receptors (PRR), such as Dectin-1, and is thought to occur at the cell surface triggering intracellular signalling cascades which lead to the induction of protective host responses. In the lung, this recognition is aided by surfactant which also serves to maintain the balance between inflammation and pulmonary function, although the underlying mechanisms are unknown. Here we have explored pulmonary innate recognition of a variety of fungal particles, including zymosan, Candida albicans and Aspergillus fumigatus, and demonstrate that opsonisation with surfactant components can limit inflammation by reducing host-cell fungal interactions. However, we found that this opsonisation does not contribute directly to innate fungal recognition and that this process is mediated through non-opsonic PRRs, including Dectin-1. Moreover, we found that pulmonary inflammatory responses to resting Aspergillus conidia were initiated by these PRRs in acidified phagolysosomes, following the uptake of fungal particles by leukocytes. Our data therefore provides crucial new insights into the mechanisms by which surfactant can maintain pulmonary function in the face of microbial challenge, and defines the phagolysosome as a novel intracellular compartment involved in the innate sensing of extracellular pathogens in the lung. © 2012 Faro-Trindade et al.
Abstract.
Redelinghuys P, Drummond RA, Reid DM, Brown GD (2012). Characterisation of the myeloid inhibitory C-type lectin-like receptor (mMICL) knock-out mouse.
Author URL.
Vautier S, Drummond RA, Redelinghuys P, Murray GI, MacCallum DM, Brown GD (2012). Dectin-1 is Not Required for Controlling Candida albicans Colonization of the Gastrointestinal Tract.
INFECTION AND IMMUNITY,
80(12), 4216-4222.
Author URL.
Vautier S, Drummond RA, Redelinghuys P, Murray GI, MacCallum D, Brown GD (2012). Dectin-1 is required for control of systemic, but not gastrointestinal, infections by Candida albicans.
Author URL.
Gessner MA, Werner JL, Lilly LM, Nelson MP, Metz AE, Dunaway CW, Chan YR, Ouyang W, Brown GD, Weaver CT, et al (2012). Dectin-1-Dependent Interleukin-22 Contributes to Early Innate Lung Defense against Aspergillus fumigatus.
INFECTION AND IMMUNITY,
80(1), 410-417.
Author URL.
Brown GD, Netea MG (2012). Exciting Developments in the Immunology of Fungal Infections.
CELL HOST & MICROBE,
11(5), 422-424.
Author URL.
Larsen HO, Roug AS, Just T, Brown GD, Hokland P (2012). Expression of the hMICL in acute myeloid leukemia-a highly reliable disease marker at diagnosis and during follow-up.
CYTOMETRY PART B-CLINICAL CYTOMETRY,
82B(1), 3-8.
Author URL.
Netea MG, Brown GD (2012). Fungal infections: the next challenge.
CURRENT OPINION IN MICROBIOLOGY,
15(4), 403-405.
Author URL.
Karsten CM, Pandey MK, Figge J, Taylor PR, Berger M, Strait R, Nimmerjahn F, Brown GD, Finkelman F, Koehl J, et al (2012). Galactosylated IgG1 ICs control C5aR-mediated inflammation via a novel interaction between FcgRIIB and Dectin-1.
Author URL.
Kilchenstein R, Figge J, Karsten CM, Brown GD, Ludwig R, Zillikens D, Koehl J (2012). Galactosylated IgG1 immune complexes diminish C5a-dependent inflammation in experimental Epidermolysis Bullosa Acquisita.
Author URL.
Brown GD, Denning DW, Gow NAR, Levitz SM, Netea MG, White TC (2012). Hidden killers: Human fungal infections.
Science Translational Medicine,
4(165).
Abstract:
Hidden killers: Human fungal infections
Although fungal infections contribute substantially to human morbidity and mortality, the impact of these diseases on human health is not widely appreciated. Moreover, despite the urgent need for efficient diagnostic tests and safe and effective new drugs and vaccines, research into the pathophysiology of human fungal infections lags behind that of diseases caused by other pathogens. In this Review, we highlight the importance of fungi as human pathogens and discuss the challenges we face in combating the devastating invasive infections caused by these microorganisms, in particular in immunocompromised individuals.
Abstract.
Brown GD (2012). IMMUNOLOGY Actin' dangerously.
NATURE,
485(7400), 589-590.
Author URL.
Wu KC, McDonald PR, Liu JJ, Chaguturu R, Klaassen CD (2012). Implementation of a High-Throughput Screen for Identifying Small Molecules to Activate the Keap1-Nrf2-ARE Pathway.
PLOS ONE,
7(10).
Author URL.
Iliev ID, Funari VA, Taylor KD, Nguyen Q, Reyes CN, Strom SP, Brown J, Becker CA, Fleshner PR, Dubinsky M, et al (2012). Interactions Between Commensal Fungi and the C-Type Lectin Receptor Dectin-1 Influence Colitis.
SCIENCE,
336(6086), 1314-1317.
Author URL.
Kerrigan AM, Navarro-Nuñez L, Pyz E, Finney BA, Willment JA, Watson SP, Brown GD (2012). Podoplanin-expressing inflammatory macrophages activate murine platelets via CLEC-2. Journal of Thrombosis and Haemostasis, 10(3), 484-486.
Hadebe S, Redelinghuys P, Brown G, Brombacher F (2012). Role of fungal beta-glucans and lipopolysaccharide in non-allergic airway inflammation.
Author URL.
Kerrigan AM, de Sousa MDGT, Brown GD (2012). Simple assays for measuring innate interactions with fungi.
Methods in Molecular Biology,
845, 303-317.
Abstract:
Simple assays for measuring innate interactions with fungi
In recent decades, there has been a steady rise in immunocompromised populations and consequently a dramatic increase in the clinical relevance of normally non-pathogenic and commensal fungi such as Aspergillus fumigatus and Candida albicans. Understanding how these fungi interact with the host immune system is important for the development of immunotherapeutic approaches. Here, we describe a number of methods which have been developed to investigate the interactions of fungi with host leukocytes in vitro, including measuring fungal binding and induction of cytokines, phagocytosis, the respiratory burst, and fungal killing.
Abstract.
Strasser D, Neumann K, Bergmann H, Marakalala MJ, Guler R, Rojowska A, Hopfner K-P, Brombacher F, Urlaub H, Baier G, et al (2012). Syk Kinase-Coupled C-type Lectin Receptors Engage Protein Kinase C-delta to Elicit Card9 Adaptor-Mediated Innate Immunity.
IMMUNITY,
36(1), 32-42.
Author URL.
Brown GD, Denning DW, Levitz SM (2012). Tackling Human Fungal Infections.
SCIENCE,
336(6082), 647-647.
Author URL.
Schreibelt G, Klinkenberg LJJ, Cruz LJ, Tacken PJ, Tel J, Kreutz M, Adema GJ, Brown GD, Figdor CG, de Vries IJM, et al (2012). The C-type lectin receptor CLEC9A mediates antigen uptake and (cross-)presentation by human blood BDCA3(+) myeloid dendritic cells.
BLOOD,
119(10), 2284-2292.
Author URL.
Graham LM, Gupta V, Schafer G, Reid DM, Kimberg M, Dennehy KM, Hornsell WG, Guler R, Campanero-Rhodes MA, Palma AS, et al (2012). The C-type lectin receptor CLECSF8 (CLEC4D) is expressed by myeloid cells and triggers cellular activation through syk kinase.
Journal of Biological Chemistry,
287(31), 25964-25974.
Abstract:
The C-type lectin receptor CLECSF8 (CLEC4D) is expressed by myeloid cells and triggers cellular activation through syk kinase
CLECSF8 is a poorly characterized member of the "Dectin-2 cluster" of C-type lectin receptors and was originally thought to be expressed exclusively by macrophages. We show here that CLECSF8 is primarily expressed by peripheral blood neutrophils and monocytes and weakly by several subsets of peripheral blood dendritic cells. However, expression of this receptor is lost upon in vitro differentiation of monocytes into dendritic cells or macrophages. Like the other members of the Dectin-2 family, which require association of their transmembrane domains with signaling adaptors for surface expression, CLECSF8 is retained intracellularly when expressed in non-myeloid cells. However, we demonstrate that CLECSF8 does not associate with any known signaling adaptor molecule, including DAP10, DAP12, or the FcRγ chain, and we found that the C-type lectin domain of CLECSF8 was responsible for its intracellular retention. Although CLECSF8 does not contain a signaling motif in its cytoplasmic domain, we show that this receptor is capable of inducing signaling via Syk kinase in myeloid cells and that it can induce phagocytosis, proinflammatory cytokine production, and the respiratory burst. These data therefore indicate that CLECSF8 functions as an activation receptor on myeloid cells and associates with a novel adaptor molecule. Characterization of the CLECSF8-deficient mice and screening for ligands using oligosaccharide microarrays did not provide further insights into the physiological function of this receptor. © 2012 by the American Society for Biochemistry and Molecular Biology, Inc.
Abstract.
Lilly LM, Gessner MA, Dunaway CW, Metz AE, Schwiebert L, Weaver CT, Brown GD, Steele C (2012). The beta-Glucan Receptor Dectin-1 Promotes Lung Immunopathology during Fungal Allergy via IL-22.
JOURNAL OF IMMUNOLOGY,
189(7), 3653-3660.
Author URL.
Gow NAR, Brown GD, Brown AJP, Netea MG, McArdle KE (2012). Waging war on fungi - the unknown superbugs. Microbiology Today, 39(4), 208-211.
2011
Marakalala MJ, Kerrigan AM, Brown GD (2011). Dectin-1: a role in antifungal defense and consequences of genetic polymorphisms in humans.
MAMMALIAN GENOME,
22(1-2), 55-65.
Author URL.
Gazi U, Rosas M, Singh S, Heinsbroek S, Haq I, Johnson S, Brown GD, Williams DL, Taylor PR, Martinez-Pomares L, et al (2011). Fungal Recognition Enhances Mannose Receptor Shedding through Dectin-1 Engagement.
JOURNAL OF BIOLOGICAL CHEMISTRY,
286(10), 7822-7829.
Author URL.
Karsten CMK, Pandey MK, Figge J, Taylor PR, McDonald JU, Strait RT, Harris NL, Koehl G, Brown GD, Finkelman FD, et al (2011). Galactosylated IgG1 links FcRIIB and dectin-1 to suppress CSaR-mediated inflammation.
Author URL.
McDonald JU, Cortini A, Rosas M, Fossati-Jimack L, Ling GS, Lewis KJ, Dewitt S, Liddiard K, Brown GD, Jones SA, et al (2011). In vivo functional analysis and genetic modification of in vitro-derived mouse neutrophils.
FASEB JOURNAL,
25(6), 1972-1982.
Author URL.
Redelinghuys P, Brown GD (2011). Inhibitory C-type lectin receptors in myeloid cells.
IMMUNOLOGY LETTERS,
136(1), 1-12.
Author URL.
Brown GD (2011). Innate Antifungal Immunity: the Key Role of Phagocytes. In (Ed)
ANNUAL REVIEW OF IMMUNOLOGY, VOL 29, 1-21.
Author URL.
Werner JL, Gessner MA, Lilly LM, Nelson MP, Metz AE, Horn D, Dunaway CW, Deshane J, Chaplin DD, Weaver CT, et al (2011). Neutrophils Produce Interleukin 17A (IL-17A) in a Dectin-1-and IL-23-Dependent Manner during Invasive Fungal Infection.
INFECTION AND IMMUNITY,
79(10), 3966-3977.
Author URL.
Mora-Montes HM, Netea MG, Ferwerda G, Lenardon MD, Brown GD, Mistry AR, Kullberg BJ, O'Callaghan CA, Sheth CC, Odds FC, et al (2011). Recognition and blocking of innate immunity cells by Candida albicans chitin.
Infection and Immunity,
79(5), 1961-1970.
Abstract:
Recognition and blocking of innate immunity cells by Candida albicans chitin
Chitin is a skeletal cell wall polysaccharide of the inner cell wall of fungal pathogens. As yet, little about its role during fungus-host immune cell interactions is known. We show here that ultrapurified chitin from Candida albicans cell walls did not stimulate cytokine production directly but blocked the recognition of C. albicans by human peripheral blood mononuclear cells (PBMCs) and murine macrophages, leading to significant reductions in cytokine production. Chitin did not affect the induction of cytokines stimulated by bacterial cells or lipopolysaccharide (LPS), indicating that blocking was not due to steric masking of specific receptors. Toll-like receptor 2 (TLR2), TLR4, and Mincle (the macrophage-inducible C-type lectin) were not required for interactions with chitin. Dectin-1 was required for immune blocking but did not bind chitin directly. Cytokine stimulation was significantly reduced upon stimulation of PBMCs with heat-killed chitin-deficient C. albicans cells but not with live cells. Therefore, chitin is normally not exposed to cells of the innate immune system but is capable of influencing immune recognition by blocking dectin-1-mediated engagement with fungal cell walls. © 2011, American Society for Microbiology.
Abstract.
da Gloria Sousa M, Reid DM, Schweighoffer E, Tybulewicz V, Ruland J, Langhorne J, Yamasaki S, Taylor PR, Almeida SR, Brown GD, et al (2011). Restoration of Pattern Recognition Receptor Costimulation to Treat Chromoblastomycosis, a Chronic Fungal Infection of the Skin.
CELL HOST & MICROBE,
9(5), 436-443.
Author URL.
Pyz E, Brown GD (2011). Screening for ligands of C-type lectin-like receptors.
Methods in Molecular Biology,
748, 1-19.
Abstract:
Screening for ligands of C-type lectin-like receptors
In order to execute their immune functions, leukocytes interact with a broad range of cell types through cell surface receptors, such as those of the immunoglobulin and C-type lectin families, or indirectly through soluble factors. The characterization of activating and inhibitory counterparts of NK cell receptors on myeloid cells, as well as the identification of their physiological ligands, has provided new insights into the underlying mechanisms of immunity and homeostasis. Here, we describe methodology that can be employed to screen for endogenous ligands of type-II C-type lectin-like receptors using reporter cells and Fc fusion proteins.
Abstract.
Kerrigan AM, Brown GD (2011). Syk-coupled C-type lectins in immunity.
TRENDS IN IMMUNOLOGY,
32(4), 151-156.
Author URL.
Marakalala MJ, Guler R, Matika L, Murray G, Jacobs M, Brombacher F, Rothfuchs AG, Sher A, Brown GD (2011). The Syk/CARD9-coupled receptor Dectin-1 is not required for host resistance to Mycobacterium tuberculosis in mice.
MICROBES AND INFECTION,
13(2), 198-201.
Author URL.
Drummond RA, Brown GD (2011). The role of Dectin-1 in the host defence against fungal infections.
CURRENT OPINION IN MICROBIOLOGY,
14(4), 392-399.
Author URL.
Drummond RA, Saijo S, Iwakura Y, Brown GD (2011). The role of Syk/CARD9 coupled C-type lectins in antifungal immunity.
EUROPEAN JOURNAL OF IMMUNOLOGY,
41(2), 276-281.
Author URL.
2010
Vautier S, Sousa MDG, Brown GD (2010). C-type lectins, fungi and Th17 responses.
CYTOKINE & GROWTH FACTOR REVIEWS,
21(6), 405-412.
Author URL.
Schoenen H, Bodendorfer B, Hitchens K, Manzanero S, Werninghaus K, Nimmerjahn F, Agger EM, Stenger S, Andersen P, Ruland J, et al (2010). Cutting Edge: Mincle is Essential for Recognition and Adjuvanticity of the Mycobacterial Cord Factor and its Synthetic Analog Trehalose-Dibehenate.
JOURNAL OF IMMUNOLOGY,
184(6), 2756-2760.
Author URL.
Parti RP, Loper R, Brown GD, Gordon S, Taylor PR, Bonventre JV, Murphy RC, Williams DL, Leslie CC (2010). Cytosolic Phospholipase A(2) Activation by Candida albicans in Alveolar Macrophages Role of Dectin-1.
AMERICAN JOURNAL OF RESPIRATORY CELL AND MOLECULAR BIOLOGY,
42(4), 415-423.
Author URL.
Plantinga TS, Hamza OJM, Willment JA, Ferwerda B, Van De Geer NMD, Verweij PE, Matee MIN, Banahan K, O'Neill LAJ, Kullberg BJ, et al (2010). Genetic variation of innate immune genes in HIV-infected African patients with or without oropharyngeal candidiasis.
Journal of Acquired Immune Deficiency Syndromes,
55(1), 87-94.
Abstract:
Genetic variation of innate immune genes in HIV-infected African patients with or without oropharyngeal candidiasis
Background: the occurrence of oropharyngeal candidiasis (OPC) in combination with HIV disease progression is a very common phenomenon. However, not all HIV-infected patients develop OPC, even when they progress to low CD4 + T-cell counts. Because T-cell immunity is defective in AIDS, the innate defence mechanisms are likely to have a central role in antifungal immunity in these patients. We investigated whether genetic variations in the innate immune genes DECTIN-1, TLR2, TLR4, TIRAP, and CASPASE-12 are associated with the presence of OPC in HIV-infected subjects from East Africa. Methods: a total of 225 HIV patients were genotyped for several single nucleotide polymorphisms (SNPs), and this was correlated with the occurrence of OPC in these patients. In addition, primary immune cells obtained from individuals with different genotypes were stimulated with Candida albicans, and cytokine production was measured. Results: the analysis revealed that no significant differences in the polymorphism frequencies could be observed, although a tendency toward a protective effect on OPC of the DECTIN-1 I223S SNP was apparent. Furthermore, interferon γ production capacity was markedly lower in cells bearing the DECTIN-1 SNP I223S. It could also be demonstrated that the 223S mutated form of the DECTIN-1 gene exhibits a lower capacity to bind zymosan. Conclusions: These data demonstrate that common polymorphisms of TLR2, TLR4, TIRAP, and CASPASE-12 do not influence susceptibility to OPC in HIV-infected patients in East Africa but suggest an immunomodulatory effect of the I223S SNP on dectin-1 function and possibly the susceptibility to OPC in HIV patients. Copyright © 2010 by Lippincott Williams & Wilkins.
Abstract.
Brown GD (2010). How Fungi Have Shaped Our Understanding of Mammalian Immunology.
CELL HOST & MICROBE,
7(1), 9-11.
Author URL.
Suram S, Gangelhoff TA, Taylor PR, Rosas M, Brown GD, Bonventre JV, Akira S, Uematsu S, Williams DL, Murphy RC, et al (2010). Pathways Regulating Cytosolic Phospholipase A(2) Activation and Eicosanoid Production in Macrophages by Candida albicans.
JOURNAL OF BIOLOGICAL CHEMISTRY,
285(40), 30676-30685.
Author URL.
Brown GD, Gordon S (2010). Phagocytes Part 1: Macrophages. In (Ed) Topley & Wilson's Microbiology and Microbial Infections.
Kerrigan AM, Brown GD (2010). Syk-coupled C-type lectin receptors that mediate cellular activation via single tyrosine based activation motifs.
IMMUNOLOGICAL REVIEWS,
234, 335-352.
Author URL.
Marakalala MJ, Graham LM, Brown GD (2010). The role of Syk/CARD9-coupled C-type lectin receptors in immunity to Mycobacterium tuberculosis infections.
Clinical & Developmental Immunology,
2010Abstract:
The role of Syk/CARD9-coupled C-type lectin receptors in immunity to Mycobacterium tuberculosis infections
There is increasing interest in understanding the mechanisms underlying the interactions that occur between Mycobacterium tuberculosis and host innate immune cells. These cells express pattern recognition receptors (PRRs) which recognise mycobacterial pathogen-associated molecular patterns (PAMPs) and which can influence the host immune response to the infection. Although many of the PRRs appear to be redundant in the control of M. tuberculosis infection in vivo, recent discoveries have revealed a key, nonredundant, role of the Syk/CARD9 signalling pathway in antimycobacterial immunity. Here we review these discoveries, as well as recent data investigating the role of the Syk/CARD9-coupled PRRs that have been implicated in mycobacterial recognition, including Dectin-1 and Mincle.
Abstract.
2009
Heinsbroek SEM, Kamen LA, Taylor PR, Brown GD, Swanson J, Gordon S (2009). Actin and Phosphoinositide Recruitment to Fully Formed Candida albicans Phagosomes in Mouse Macrophages.
JOURNAL OF INNATE IMMUNITY,
1(3), 244-253.
Author URL.
Werninghaus K, Babiak A, Gross O, Hoelscher C, Dietrich H, Agger EM, Mages J, Mocsai A, Schoenen H, Finger K, et al (2009). Adjuvanticity of a synthetic cord factor analogue for subunit Mycobacterium tuberculosis vaccination requires FcR gamma-Syk-Card9-dependent innate immune activation.
JOURNAL OF EXPERIMENTAL MEDICINE,
206(1), 89-97.
Author URL.
Hise AG, Tomalka J, Ganesan S, Patel K, Hall BA, Brown GD, Fitzgerald KA (2009). An Essential Role for the NLRP3 Inflammasome in Host Defense against the Human Fungal Pathogen Candida albicans.
CELL HOST & MICROBE,
5(5), 487-497.
Author URL.
Kerrigan AM, Brown GD (2009). C-type lectins and phagocytosis.
IMMUNOBIOLOGY,
214(7), 562-575.
Author URL.
Kerrigan AM, Dennehy KM, Mourão-Sá D, Faro-Trindade I, Willment JA, Taylor PR, Eble JA, Reis E Sousa C, Brown GD (2009). CLEC-2 is a phagocytic activation receptor expressed on murine peripheral blood neutrophils.
Journal of Immunology,
182(7), 4150-4157.
Abstract:
CLEC-2 is a phagocytic activation receptor expressed on murine peripheral blood neutrophils
CLEC-2 is a member of the "dectin-1 cluster" of C-type lectin-like receptors and was originally thought to be restricted to platelets. In this study, we demonstrate that murine CLEC-2 is also expressed by peripheral blood neutrophils, but only weakly by bone marrow or elicited inflammatory neutrophils. On circulating neutrophils, CLEC-2 can mediate phagocytosis of Ab-coated beads and the production of proinflammatory cytokines, including TNF-α, in response to the CLEC-2 ligand, rhodocytin. CLEC-2 possesses a tyrosine-based cytoplasmic motif similar to that of dectin-1, and we show using chimeric analyses that the activities of this receptor are dependent on this tyrosine. Like dectin-1, CLEC-2 can recruit the signaling kinase Syk in myeloid cells, however, stimulation of this pathway does not induce the respiratory burst. These data therefore demonstrate that CLEC-2 expression is not restricted to platelets and that it functions as an activation receptor on neutrophils. Copyright © 2009 by the American Association of Immunologists, Inc.
Abstract.
Mora-Montes HM, Netea MG, Sheth CC, Brown GD, Bates S, Kullberg BJ, Brown AJP, Odds FC, Gow NAR (2009). Candida albicans cell wall glycobiology: biosynthesis of N-linked mannans and interaction with the host innate immune system.
MYCOSES,
52, 24-24.
Author URL.
Brown GD, Williams DL (2009). Chapter 4.5.2 (1,3)-β-Glucans in Innate Immunity Mammalian Systems. In (Ed) Chemistry, Biochemistry, and Biology of 1-3 Beta Glucans and Related Polysaccharides, 579-619.
Tsoni SV, Kerrigan AM, Marakalala MJ, Srinivasan N, Duffield M, Taylor PR, Botto M, Steele C, Brown GD (2009). Complement C3 Plays an Essential Role in the Control of Opportunistic Fungal Infections.
INFECTION AND IMMUNITY,
77(9), 3679-3685.
Author URL.
Marakalala MI, Tsoni SV, Kerrigan AM, Srinivasan N, Duffield M, Taylor PR, Botto M, Steele C, Brown GD (2009). Complement C3 plays an essential role in the control of opportunistic fungal infections.
Author URL.
Robinson MJ, Osorio F, Rosas M, Freitas RP, Schweighoffer E, Gross O, SjefVerbeek J, Ruland J, Tybulewicz V, Brown GD, et al (2009). Dectin-2 is a Syk-coupled pattern recognition receptor crucial for Th17 responses to fungal infection.
JOURNAL OF EXPERIMENTAL MEDICINE,
206(9), 2037-2051.
Author URL.
Robinson MJ, Osorio F, Rosas M, Freitas RP, Schweighoffer E, Groß O, Verbeek JS, Ruland J, Tybulewicz V, Brown GD, et al (2009). Dectin-2 is a Syk-coupled pattern recognition receptor crucial for Th17 responses to fungal infection. Journal of Cell Biology, 186(5), i9-i9.
Plantinga TS, van der Velden WJFM, Ferwerda B, van Spriel AB, Adema G, Feuth T, Donnelly JP, Brown GD, Kullberg B-J, Blijlevens NMA, et al (2009). Early Stop Polymorphism in Human DECTIN-1 is Associated with Increased Candida Colonization in Hematopoietic Stem Cell Transplant Recipients.
CLINICAL INFECTIOUS DISEASES,
49(5), 724-732.
Author URL.
afer GS, Brown GD (2009). Generation of retroviral macrophage cDNA expression libraries and functional screening for surface receptors.
Methods in Molecular Biology,
531, 1-15.
Abstract:
Generation of retroviral macrophage cDNA expression libraries and functional screening for surface receptors
Macrophages, tissue-based phagocytic cells derived from blood monocytes, play important roles in immunity and homeostasis. As professional scavengers, macrophages phagocytose microbes, apoptotic and necrotic cells and take up modified lipoprotein particles. However, many of their complex interactions with other immune cells and/or various ligands are not yet clearly understood. To identify and isolate macrophage cell surface molecules, particularly macrophage receptors, for which ligands are known, a powerful generalized screening method has been established. As discussed in this chapter, this technique based on function has been successfully applied for the identification of dectin-1, the major macrophage receptor involved in the binding and recognition of beta-glucans (Nature 413:36-37, 2001).
Abstract.
Ferwerda B, Ferwerda G, Plantinga TS, Willment JA, Van Spriel AB, Venselaar H, Elbers CC, Johnson MD, Cambi A, Huysamen C, et al (2009). Human dectin-1 deficiency and mucocutaneous fungal infections.
New England Journal of Medicine,
361(18), 1760-1767.
Abstract:
Human dectin-1 deficiency and mucocutaneous fungal infections
Mucocutaneous fungal infections are typically found in patients who have no known immune defects. We describe a family in which four women who were affected by either recurrent vulvovaginal candidiasis or onychomycosis had the early-stop-codon mutation Tyr238X in the β-glucan receptor dectin-1. The mutated form of dectin-1 was poorly expressed, did not mediate β-glucan binding, and led to defective production of cytokines (interleukin-17, tumor necrosis factor, and interleukin-6) after stimulation with β-glucan or Candida albicans. In contrast, fungal phagocytosis and fungal killing were normal in the patients, explaining why dectin-1 deficiency was not associated with invasive fungal infections and highlighting the specific role of dectin-1 in human mucosal antifungal defense. Copyright © 2009 Massachusetts Medical Society.
Abstract.
Faro‐Trindade I, Brown GD (2009). Interaction of Candida albicans with Phagocytes. In (Ed) Phagocyte-Pathogen Interactions, 437-4p1.
Schaefer G, Jacobs M, Wilkinson RJ, Brown GD (2009). Non-Opsonic Recognition of Mycobacterium tuberculosis by Phagocytes.
JOURNAL OF INNATE IMMUNITY,
1(3), 231-243.
Author URL.
Reid DM, Gow NA, Brown GD (2009). Pattern recognition: recent insights from Dectin-1.
Current Opinion in Immunology,
21(1), 30-37.
Abstract:
Pattern recognition: recent insights from Dectin-1
The β-glucan receptor Dectin-1 is an archetypical non-toll-like pattern recognition receptor expressed predominantly by myeloid cells, which can induce its own intracellular signalling and can mediate a variety of cellular responses, such as cytokine production. Recent identification of the components of these signalling pathways, such as Syk kinase, CARD9 and Raf-1, has provided novel insights into the molecular mechanisms underlying Dectin-1 function. Furthermore, a broader appreciation of the cellular responses mediated by this receptor and the effects of interactions with other receptors, including the TLRs, have greatly furthered our understanding of innate immunity and how this drives the development of adaptive immunity, particularly Th17 responses. Recent studies have highlighted the importance of Dectin-1 in anti-fungal immunity, in both mice and humans, and have suggested a possible involvement of this receptor in the control of mycobacterial infections. © 2009 Elsevier Ltd. All rights reserved.
Abstract.
Dennehy KM, Willment JA, Williams DL, Brown GD (2009). Reciprocal regulation of IL-23 and IL-12 following co-activation of dectin-1 and TLR signaling pathways.
European Journal of Immunology,
39(5), 1379-1386.
Abstract:
Reciprocal regulation of IL-23 and IL-12 following co-activation of dectin-1 and TLR signaling pathways
Recognition ofmicrobial products by germ-line-encoded PRR initiates immune responses, but how PRR mediate specific host responses to infectious agents is poorly understood. We and others have proposed that specificity is achieved by collaborative responsesmediated between different PRR. One such example comprises the fungal β-glucan receptor Dectin-1, which collaborates with TLR to induce TNF production. We show here that collaborative responses mediated by Dectin-1 and TLR2 are more extensive than first appreciated, and result in enhanced IL-23, IL-6 and IL-10 production in DC, while down-regulating IL-12 relative to the levels produced by TLR ligation alone. Such down-regulation occurred with multiple MyD88-coupled TLR, was dependent on signaling through Dectin-1 and also occurred in macrophages. These findings explain how fungi can induce IL-23 and IL-6, while suppressing IL-12, a combination which has previously been shown to contribute to the development of Th17 responses found during fungal infections. Furthermore, these data reveal how the collaboration of different PRR can tailor specific responses to infectious agents. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Abstract.
Werner JL, Metz AE, Horn D, Schoeb TR, Hewitt MM, Schwiebert LM, Faro-Trindade I, Brown GD, Steele C (2009). Requisite Role for the Dectin-1 beta-Glucan Receptor in Pulmonary Defense against Aspergillus fumigatus.
JOURNAL OF IMMUNOLOGY,
182(8), 4938-4946.
Author URL.
Graham LM, Brown GD (2009). The Dectin-2 family of C-type lectins in immunity and homeostasis.
CYTOKINE,
48(1-2), 148-155.
Author URL.
Schaefer G, Guler R, Murray G, Brombacher F, Brown GD (2009). The Role of Scavenger Receptor B1 in Infection with Mycobacterium tuberculosis in a Murine Model.
PLOS ONE,
4(12).
Author URL.
Huysamen C, Brown GD (2009). The fungal pattern recognition receptor, Dectin-1, and the associated cluster of C-type lectin-like receptors.
FEMS MICROBIOLOGY LETTERS,
290(2), 121-128.
Author URL.
2008
Netea MG, Brown GD, Kullberg BJ, Gow NAR (2008). An integrated model of the recognition of Candida albicans by the innate immune system.
Nature Reviews Microbiology,
6(1), 67-78.
Abstract:
An integrated model of the recognition of Candida albicans by the innate immune system
The innate immune response was once considered to be a limited set of responses that aimed to contain an infection by primitive 'ingest and kill' mechanisms, giving the host time to mount a specific humoral and cellular immune response. In the mid-1990s, however, the discovery of Toll-like receptors heralded a revolution in our understanding of how microorganisms are recognized by the innate immune system, and how this system is activated. Several major classes of pathogen-recognition receptors have now been described, each with specific abilities to recognize conserved bacterial structures. The challenge ahead is to understand the level of complexity that underlies the response that is triggered by pathogen recognition. In this Review, we use the fungal pathogen Candida albicans as a model for the complex interaction that exists between the host pattern-recognition systems and invading microbial pathogens.
Abstract.
Willment JA, Brown GD (2008). C-type lectin receptors in antifungal immunity.
Trends in Microbiology,
16(1), 27-32.
Abstract:
C-type lectin receptors in antifungal immunity
Fungal infections represent a significant health burden, especially in immunocompromised individuals, yet many of the underlying immunological mechanisms involved in the recognition and control of these pathogens are unclear. The identification of the Toll-like receptors (TLRs) has shed new insights on innate microbial recognition and the initiation of immune responses; however, recent evidence indicates that the 'non-TLR' receptors also have a significant role in these processes, particularly in antifungal immunity. of interest are members of the C-type lectin-receptor family, including the mannose receptor, dendritic cell-specific intercellular adhesion molecule-3 (ICAM-3)-grabbing non-integrin (DC-SIGN), Dectin-1, Dectin-2 and the collectins. Here, we review the roles of each of these receptors, describing how they contribute to fungal recognition, uptake and killing and also participate in the induction and/or modulation of the host immune response. © 2007 Elsevier Ltd. All rights reserved.
Abstract.
Huysamen C, Willment JA, Dennehy KM, Brown GD (2008). CLEC9A is a novel activation C-type lectin-like receptor expressed on BDCA3<sup>+</sup> dendritic cells and a subset of monocytes.
Journal of Biological Chemistry,
283(24), 16693-16701.
Abstract:
CLEC9A is a novel activation C-type lectin-like receptor expressed on BDCA3+ dendritic cells and a subset of monocytes
We describe here the first characterization of CLEC9A, a group V C-type lectin-like receptor located in the "Dectin-1 cluster" of related receptors, which are encoded within the natural killer (NK)-gene complex. Expression of human CLEC9A is highly restricted in peripheral blood, being detected only on BDCA3+ dendritic cells and on a small subset of CD14+CD16- monocytes. CLEC9A is expressed at the cell surface as a glycosylated dimer and can mediate endocytosis, but not phagocytosis. CLEC9A possesses a cytoplasmic immunoreceptor tyrosine-based activation-like motif that can recruit Syk kinase, and we demonstrate, using receptor chimeras, that this receptor can induce proinflammatory cytokine production. These data indicate that CLEC9A functions as an activation receptor. © 2008 by the American Society for Biochemistry and Molecular Biology, Inc.
Abstract.
Pyz E, Huysamen C, Marshall ASJ, Gordon S, Taylor PR, Brown GD (2008). Characterisation of murine MICL (CLEC12A) and evidence for an endogenous ligand.
EUROPEAN JOURNAL OF IMMUNOLOGY,
38(4), 1157-1163.
Author URL.
Valera I, Ferandez N, Trinidad AG, Alonso S, Brown GD, Alonso A, Sanchez Crespo M (2008). Costimulation of dectin-1 and DC-SIGN triggers the arachidonic acid cascade in human monocyte-derived dendritic cells.
JOURNAL OF IMMUNOLOGY,
180(8), 5727-5736.
Author URL.
Kimberg M, Brown GD (2008). Dectin-1 and its role in antifungal immunity.
MEDICAL MYCOLOGY,
46(7), 631-636.
Author URL.
Adams EL, Rice PJ, Graves B, Ensley HE, Yu H, Brown GD, Gordon S, Monteiro MA, Papp-Szabo E, Lowman DW, et al (2008). Differential high-affinity interaction of dectin-1 with natural or synthetic glucans is dependent upon primary structure and is influenced by polymer chain length and side-chain branching.
JOURNAL OF PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICS,
325(1), 115-123.
Author URL.
Graham LM, Brown GD (2008). Innate Recognition of Aspergillus fumigatus by the Mammalian Immune System. In (Ed) Aspergillus fumigatus. and Aspergillosis, 279-289.
Brown G (2008). Innate immunity: what have we learned from Dectin-1.
Author URL.
Dennehy KM, Willment JA, Williams DL, Brown GD (2008). Reciprocal regulation of IL-23 and IL-12 following co-activation of Dectin-1/Syk and Toll-like receptor/MyD88 signaling pathways.
Author URL.
Brown GD (2008). Sensing necrosis with Mincle.
NATURE IMMUNOLOGY,
9(10), 1099-1100.
Author URL.
LeibundGut-Landmann S, Osorio F, Brown GD, Sousa CRE (2008). Stimulation of dendritic cells via the dectin-1/Syk pathway allows priming of cytotoxic T-cell responses.
BLOOD,
112(13), 4971-4980.
Author URL.
Jimenez-A MDP, Viriyakosol S, Walls L, Datta SK, Kirkland T, Heinsbroek SEM, Brown G, Fierer J (2008). Susceptibility to Coccidioides species in C57BL/6 mice is associated with expression of a truncated splice variant of Dectin-1 (Clec7a).
GENES AND IMMUNITY,
9(4), 338-348.
Author URL.
Dennehy KM, Ferwerda G, Faro-Trindade I, Pyz E, Willment JA, Taylor PR, Kerrigan A, Tsoni SV, Gordon S, Meyer-Wentrup F, et al (2008). Syk kinase is required for collaborative cytokine production induced through Dectin-1 and Toll-like receptors.
European Journal of Immunology,
38(2), 500-506.
Abstract:
Syk kinase is required for collaborative cytokine production induced through Dectin-1 and Toll-like receptors
Recognition of microbial components by germ-line encoded pattern recognition receptors (PRR) initiates immune responses to infectious agents. We and others have proposed that pairs or sets of PRR mediate host immunity. One such pair comprises the fungal β-glucan receptor, Dectin-1, which collaborates through an undefined mechanism with Toll-like receptor 2 (TLR2) to induce optimal cytokine responses in macrophages. We show here that Dectin-1 signaling through the spleen tyrosine kinase (Syk) pathway is required for this collaboration, which can also occur with TLR4, 5, 7 and 9. Deficiency of either Syk or the TLR adaptor MyD88 abolished collaborative responses, which include TNF,MIP-1α andMIP-2 production, and which are comparable to the previously described synergy between TLR2 and TLR4. Collaboration of the Syk and TLR/MyD88 pathways results in sustained degradation of the inhibitor of kB (IkB), enhancing NFkB nuclear translocation. These findings establish the first example of Syk-and MyD88-coupled PRR collaboration, further supporting the concept that paired receptors collaborate to control infectious agents. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Abstract.
Rosas M, Liddiard K, Kimberg M, Faro-Trindade I, McDonald JU, Williams DL, Brown GD, Taylor PR (2008). The induction of inflammation by dectin-1 in vivo is dependent on myeloid cell programming and the progression of phagocytosis.
JOURNAL OF IMMUNOLOGY,
181(5), 3549-3557.
Author URL.
2007
Rothfuchs AG, Bafica A, Feng CG, Egen JG, Williams DL, Brown GD, Sher A (2007). Dectin-1 interaction with mycobacterium tuberculosis leads to enhanced IL-12p40 production by splenic dendritic cells.
JOURNAL OF IMMUNOLOGY,
179(6), 3463-3471.
Author URL.
Taylor PR, Tsoni SV, Willment JA, Dennehy KM, Rosas M, Findon H, Haynes K, Steele C, Botto M, Gordon S, et al (2007). Dectin-1 is required for beta-glucan recognition and control of fungal infection.
Nat Immunol,
8(1), 31-38.
Abstract:
Dectin-1 is required for beta-glucan recognition and control of fungal infection.
Beta-glucan is one of the most abundant polysaccharides in fungal pathogens, yet its importance in antifungal immunity is unclear. Here we show that deficiency of dectin-1, the myeloid receptor for beta-glucan, rendered mice susceptible to infection with Candida albicans. Dectin-1-deficient leukocytes demonstrated significantly impaired responses to fungi even in the presence of opsonins. Impaired leukocyte responses were manifested in vivo by reduced inflammatory cell recruitment after fungal infection, resulting in substantially increased fungal burdens and enhanced fungal dissemination. Our results establish a fundamental function for beta-glucan recognition by dectin-1 in antifungal immunity and demonstrate a signaling non-Toll-like pattern-recognition receptor required for the induction of protective immune responses.
Abstract.
Author URL.
Kennedy AD, Willment JA, Dorward DW, Williams DL, Brown GD, DeLeo FR (2007). Dectin-1 promotes fungicidal activity of human neutrophils.
European Journal of Immunology,
37(2), 467-478.
Abstract:
Dectin-1 promotes fungicidal activity of human neutrophils
Human polymorphonuclear leukocytes (PMN) are a first line of defense against fungal infections. PMN express numerous pattern recognition receptors (PRR) that facilitate identification of invading microorganisms and ultimately promote resolution of disease. Dectin-1 (β-glucan receptor) is a PRR expressed on several cell types and has been studied on monocytes and macrophages. However, the role played by dectin-1 in the recognition and killing of fungi by PMN is unknown. We investigated the ability of dectin-1 to mediate human PMN phagocytosis and fungicidal activity. Dectin-1 was expressed on the surface of PMN from all subjects tested (n=29) and in an intracellular compartment that co-sedimented with azurophilic granules in Percoll density gradients. Soluble β-glucan and mAb GE2 (anti-dectin-1) inhibited binding and phagocytosis of zymosan by human PMN (e.g. ingestionwas inhibited 40.1% by 3O min, p
Abstract.
Tsoni SV, Brown GD (2007). Fungal ß-Glucans and their Receptors. In (Ed) Immunology of Fungal Infections, 273-292.
Brown J, O'Callaghan CA, Marshall ASJ, Gilbert RJC, Siebold C, Gordon S, Brown GD, Jones EY (2007). Structure of the fungal beta-glucan-binding immune receptor dectin-1: Implications for function.
PROTEIN SCIENCE,
16(6), 1042-1052.
Author URL.
LeibundGut-Landmann S, Gross O, Robinson MJ, Osorio F, Slack EC, Tsoni SV, Schweighoffer E, Tybulewicz V, Brown GD, Ruland J, et al (2007). Syk- and CARD9-dependent coupling of innate immunity to the induction of T helper cells that produce interleukin 17.
NATURE IMMUNOLOGY,
8(6), 630-638.
Author URL.
Slack EC, Robinson MJ, Hernanz-Falcon P, Brown GD, Williams DL, Schweighoffer E, Tybulewicz VL, Reis e Sousa C (2007). Syk-dependent ERK activation regulates IL-2 and IL-10 production by DC stimulated with zymosan.
EUROPEAN JOURNAL OF IMMUNOLOGY,
37(6), 1600-1612.
Author URL.
Dennehy KM, Brown GD (2007). The role of the beta-glucan receptor Dectin-1 in control of fungal infection.
JOURNAL OF LEUKOCYTE BIOLOGY,
82(2), 253-258.
Author URL.
2006
Pyz E, Marshall ASJ, Gordon S, Brown GD (2006). C-type lectin-like receptors on myeloid cells.
ANNALS OF MEDICINE,
38(4), 242-251.
Author URL.
Brown GD (2006). Dectin-1: a signalling non-TLR pattern-recognition receptor.
NATURE REVIEWS IMMUNOLOGY,
6(1), 33-43.
Author URL.
Heinsbroek SEM, Taylor PR, Rosas M, Willment JA, Williams DL, Gordon S, Brown GD (2006). Expression of functionally different dectin-1 isoforms by murine macrophages.
Journal of Immunology,
176(9), 5513-5518.
Abstract:
Expression of functionally different dectin-1 isoforms by murine macrophages
Dectin-1 is a specific receptor for β-glucans and a major receptor for fungal particles on macrophages (Mφ). It is a type II membrane receptor that has a C-terminal, NK-like, C-type lectin-like domain separated from the cell membrane by a short stalk region and a cytoplasmic immunoreceptor tyrosine-based activation-like motif. We observed functional differences in dectin-1-dependent recognition of fungal particles by Mφ from different mouse strains. RT-PCR analysis revealed that mice have at least two splice forms of dectin-1, generated by differential usage of exon 3, encoding the full-length dectin-1A and a stalkless Mφ dectin-1B. Mφ from BALB/c mice and genetically related mice expressed both isoforms in similar amounts, whereas Mφ from C57BL/6 and related mice mainly expressed the smaller isoform. NIH-3T3 fibroblast and RAW264.7 macrophage cell lines stably expressing either isoform were able to bind and phagocytose zymosan at 37°C. However, binding by the smaller dectin-1B isoform was significantly affected at lower temperatures. These properties were shared by the equivalent human isoforms. The relative ability of each of the isoforms to induce TNF-α production in RAW264.7 Mφ was also found to be different. These results are the first evidence that dectin-1 isoforms are functionally distinct and indicate that differential isoform usage may represent a mechanism of regulating cellular responses to β-glucans. Copyright © 2006 by the American Association of Immunologists, Inc.
Abstract.
Marshall ASJ, Willment JA, Pyz E, Dennehy KM, Reid DM, Dri P, Gordon S, Wong SYC, Brown GD (2006). Human MICL (CLEC12A) is differentially glycosylated and is down-regulated following cellular activation.
European Journal of Immunology,
36(8), 2159-2169.
Abstract:
Human MICL (CLEC12A) is differentially glycosylated and is down-regulated following cellular activation
C-type lectins are the most diverse and prevalent lectin family in immunity. Particular interest has recently been attracted by the C-type lectin-like receptors on NK cells, which appear to regulate the activation/inhibitory balance of these cells, controlling cytotoxicity and cytokine production. We previously identified a human C-type lectin-like receptor, closely related to both the beta-glucan receptor and the lectin-like receptor for oxidized-LDL, named MICL (myeloid inhibitory C-type lectin-like receptor), which we had shown using chimeric analysis to function as an inhibitory receptor. Using a novel MICL-specific monoclonal antibody, we show here that human MICL is expressed primarily on myeloid cells, including granulocytes, monocytes, macrophages, and dendritic cells. Although MICL was highly N-glycosylated in primary cells, the level of glycosylation was found to vary between cell types. MICL surface expression was down-regulated during inflammatory/activation conditions in vitro, as well as during an in vivo model of acute inflammation, which we characterize here. This suggests that human MICL may be involved in the control of myeloid cell activation during inflammation. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Abstract.
Palma AS, Feizi T, Zhang YB, Stoll MS, Lawson AM, Diaz-Rodriguez E, Campanero-Rhodes MA, Costa J, Gordon S, Brown GD, et al (2006). Ligands for the beta-glucan receptor, Dectin-1, assigned using "designer" microarrays of oligosaccharide probes (neoglycolipids) generated from glucan polysaccharides.
JOURNAL OF BIOLOGICAL CHEMISTRY,
281(9), 5771-5779.
Author URL.
Palma AS, Feizi T, Zhang Y, Stoll MS (2006). Ligands for the beta-glucan receptor, Dectin-1, assigned using "designer" microarrays of oligosaccharide probes (neoglycolipids) generated from glucan polysaccharides. (vol 281, pg 5771, 2006).
JOURNAL OF BIOLOGICAL CHEMISTRY,
281(34), 24999-24999.
Author URL.
Brown GD (2006). Macrophage Receptors and Innate Immunity: Insights from Dectin‐1. In (Ed) Innate Immunity to Pulmonary Infection, 114-126.
Ozment-Skelton TR, Goldman MP, Gordon S, Brown GD, Williams DL (2006). Prolonged reduction of leukocyte membrane-associated Dectin-1 levels following beta-glucan administration.
JOURNAL OF PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICS,
318(2), 540-546.
Author URL.
Suram S, Brown GD, Ghosh M, Gordon S, Loper R, Taylor PR, Akira S, Uematsu S, Williams DL, Leslie CC, et al (2006). Regulation of cytosolic phospholipase A(2) activation and cyclooxygenase 2 expression in macrophages by the beta-glucan receptor.
JOURNAL OF BIOLOGICAL CHEMISTRY,
281(9), 5506-5514.
Author URL.
Graham LM, Tsoni SV, Willment JA, Williams DL, Taylor PR, Gordon S, Dennehy K, Brown GD (2006). Soluble Dectin-1 as a tool to detect β-glucans.
Journal of Immunological Methods,
314(1-2), 164-169.
Abstract:
Soluble Dectin-1 as a tool to detect β-glucans
β-Glucans are structural components of fungal cell walls which are involved in the immune recognition of fungal pathogens and possess beneficial immunomodulatory activities in isolated form. Here we have developed a soluble chimeric form of the major mammalian β-glucan receptor, Dectin-1, and demonstrate its application for the detection and characterisation of soluble and insoluble β-glucans, including fungal particles, using ELISA, flow cytometric and fluorescence-based microscopy assays. © 2006 Elsevier B.V. All rights reserved.
Abstract.
McGreal EP, Rosas M, Brown GD, Zamze S, Wong SYC, Gordon S, Martinez-Pomares L, Taylor PR (2006). The carbohydrate-recognition domain of Dectin-2 is a C-type lectin with specificity for high mannose.
GLYCOBIOLOGY,
16(5), 422-430.
Author URL.
2005
Yoshitomi H, Sakaguchi N, Kobayashi K, Brown GD, Tagami T, Sakihama T, Hirota K, Tanaka S, Nomura T, Miki I, et al (2005). A role for fungal beta-glucans and their receptor Dectin-1 in the induction of autoimmune arthritis in genetically susceptible mice.
JOURNAL OF EXPERIMENTAL MEDICINE,
201(6), 949-960.
Author URL.
Willment JA, Marshall AS, Gordon S, Brown GD (2005). Characterisation of the human beta-glucan receptor.
Author URL.
Heinsbroek SEM, Brown GD, Gordon S (2005). Dectin-1 escape by fungal dimorphism.
TRENDS IN IMMUNOLOGY,
26(7), 352-354.
Author URL.
Heinsbroek SE, Taylor PR, Rosas M, Willment JA, Gordon S, Brown GD (2005). Dectin-1 isoforms in mice are functionally different.
Author URL.
Taylor PR, Reid DM, Heinsbroek SE, Brown GD, Gordon S, Wong SY (2005). Dectin-2 exhibits activation dependent expression on maturing inflammatory monocytes elicited in vivo.
Author URL.
Taylor PR, Reid DM, Heinsbroek SEM, Brown GD, Gordon S, Wong SYC (2005). Dectin-2 is predominantly myeloid restricted and exhibits unique activation-dependent expression on maturing inflammatory monocytes elicited in vivo.
EUROPEAN JOURNAL OF IMMUNOLOGY,
35(7), 2163-2174.
Author URL.
Su YP, Bakker T, Harris J, Tsang C, Brown GD, Wormald MR, Gordon S, Dwek RA, Rudd PM, Martinez-Pomares L, et al (2005). Glycosylation influences the lectin activities of the macrophage mannose receptor.
JOURNAL OF BIOLOGICAL CHEMISTRY,
280(38), 32811-32820.
Author URL.
Yunpeng Y, Bakker T, Harris J, Sang CT, Brown GD, Wormald MR, Gordon S, Dwek RA, Rudd PM, Martinez-Pomares L, et al (2005). Glycosylation influences the lectin activities of the mannose receptor.
Author URL.
Brown GD, Gordon S (2005). Immune recognition of fungal beta-glucans.
CELLULAR MICROBIOLOGY,
7(4), 471-479.
Author URL.
Viriyakosol S, Fierer J, Brown GD, Kirkland TN (2005). Innate immunity to the pathogenic fungus Coccidioides posadasii is dependent on toll-like receptor 2 and dectin-1.
INFECTION AND IMMUNITY,
73(3), 1553-1560.
Author URL.
Hobson RP, Munro CA, Bates S, MacCullum DM, Cutler JE, Heinsbroek SE, Brown GD, Odds FC, Gow NA (2005). Loss of cell wall mannosylphosphate in Candida albicans does not influence macrophage recognition. Journal of Biological Chemistry, 279, 39628-39635.
Taylor PR, Martinez-Pomares L, Stacey M, Lin HH, Brown GD, Gordon S (2005). Macrophage receptors and immune recognition. In (Ed)
ANNUAL REVIEW OF IMMUNOLOGY, 901-944.
Author URL.
Rice PJ, Adams EL, Ozment-Skelton T, Gonzalez AJ, Goldman MP, Lockhart BE, Barker LA, Breuel KF, DePonti WK, Kalbfleisch JH, et al (2005). Oral delivery and gastrointestinal absorption of soluble glucans stimulate increased resistance to infectious challenge.
JOURNAL OF PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICS,
314(3), 1079-1086.
Author URL.
Rogers NC, Slack EC, Edwards AD, Nolte MA, Schulz O, Schweighoffer E, Williams DL, Gordon S, Tybulewicz VL, Brown GD, et al (2005). Syk-Dependent Cytokine Induction by Dectin-1 Reveals a Novel Pattern Recognition Pathway for C Type Lectins. Immunity, 22(6), 773-774.
Rogers NC, Slack EC, Edwards AD, Nolte MA, Schulz O, Schweighoffer E, Williams DL, Gordon S, Tybulewicz VL, Brown GD, et al (2005). Syk-dependent cytokine induction by Dectin-1 reveals a novel pattern recognition pathway for C type lectins.
IMMUNITY,
22(4), 507-517.
Author URL.
Steele C, Rapaka RR, Metz A, Pop SM, Williams DL, Gordon S, Kolls JK, Brown GD (2005). The beta-glucan receptor dectin-1 recognizes specific morphologies of Aspergillus fumigatus.
PLOS PATHOGENS,
1(4), 323-334.
Author URL.
Willment JA, Marshall AS, Reid DM, Williams DL, Wong SYC, Gordon S, Brown GD (2005). The human β-glucan receptor is widely expressed and functionally equivalent to murine Dectin-1 on primary cells.
European Journal of Immunology,
35(5), 1539-1547.
Abstract:
The human β-glucan receptor is widely expressed and functionally equivalent to murine Dectin-1 on primary cells
We identified the C-type-lectin-like receptor, Dectin-1, as the major receptor for fungal β-glucans on murine macrophages and have demonstrated that it plays a significant role in the cellular response to these carbohydrates. Using two novel, isoform-specific mAb, we show here that human Dectin-1, the β-glucan receptor (βGR), is widely expressed and present on all monocyte populations as well as macrophages, DC, neutrophils and eosinophils. This receptor is also expressed on B cells and a subpopulation of T cells, demonstrating that human Dectin-1 is not myeloid restricted. Both major functional βGR isoforms - βGR-A and βGR-B - were expressed by these cell populations in peripheral blood; however, only βGR-B was significantly expressed on mature monocyte-derived macrophages and immature DC, suggesting cell-specific control of isoform expression. Inflammatory cells, recruited in vivo using a new skin-window technique, demonstrated that Dectin-1 expression was not significantly modulated on macrophages during inflammation, but is decreased on recruited granulocytes. Despite previous reports detailing the involvement of other β-glucan receptors on mature human macrophages, we have demonstrated that Dectin-1 acted as the major β-glucan receptor on these cells and contributed to the inflammatory response to these carbohydrates. © WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Abstract.
2004
Herre J, Gordon S, Brown GD (2004). Dectin-1 and its role in the recognition of beta-glucans by macrophages.
MOLECULAR IMMUNOLOGY,
40(12), 869-876.
Author URL.
Herre J, Marshall ASJ, Caron E, Edwards AD, Williams DL, Schweighoffer E, Tybulewicz V, Sousa CRE, Gordon S, Brown GD, et al (2004). Dectin-1 uses novel mechanisms for yeast phagocytosis in macrophages.
BLOOD,
104(13), 4038-4045.
Author URL.
Reid DM, Montoya M, Taylor PR, Borrow P, Gordon S, Brown GD, Wong SYC (2004). Expression of the beta-glucan receptor, dectin-1, on murine leukocytes in situ correlates with its function in pathogen recognition and reveals potential roles in leukocyte interactions.
Author URL.
Marshall ASJ, Willment JA, Lin HH, Williams DL, Gordon S, Brown GD (2004). Identification and characterization of a novel human Myeloid inhibitory c-type lectin-like receptor (MICL) that is predominantly expressed on granulocytes and monocytes.
JOURNAL OF BIOLOGICAL CHEMISTRY,
279(15), 14792-14802.
Author URL.
Diniz SN, Nomizo R, Cisalpino PS, Teixeira MM, Brown GD, Mantovani A, Gordon S, Reis LFL, Dias AAM (2004). PTX3 function as an opsonin for the dectin-1-dependent internalization of zymosan by macrophages.
JOURNAL OF LEUKOCYTE BIOLOGY,
75(4), 649-656.
Author URL.
Heinsbroek SEM, Gordon S, Brown GD (2004). Role of Dectin-1 in Candida albicans phagocytosis by macrophages.
Author URL.
Taylor PR, Brown GD, Herre J, Williams DL, Willment JA, Gordon S (2004). The Role of SIGNR1 and the β-Glucan Receptor (Dectin-1) in the Nonopsonic Recognition of Yeast by Specific Macrophages.
Journal of Immunology,
172(2), 1157-1162.
Abstract:
The Role of SIGNR1 and the β-Glucan Receptor (Dectin-1) in the Nonopsonic Recognition of Yeast by Specific Macrophages
We recently demonstrated that the β-glucan receptor Dectin-1 (βGR) was the major nonopsonic β-glucan receptor on macrophages (Mφ) for the yeast-derived particle zymosan. However, on resident peritoneal Mφ, we identified an additional mannan-inhibitable receptor for zymosan that was distinct from the Mφ mannose receptor (MR). In this study, we have studied the mannose-binding potential of murine Mφ and identified the dendritic cell-specific ICAM-3-grabbing nonintegrin homolog, SIGN-related 1 (SIGNR1), as a major MR on murine resident peritoneal Mφ. Both SIGNR1 and βGR cooperated in the nonopsonic recognition of zymosan by these Mφ. When SIGNR1 was introduced into NIH3T3 fibroblasts or RAW 264.7 Mφ, it conferred marked zymosan-binding potential on these cells. However, in the nonprofessional phagocytes (NIH3T3), SIGNR1 was found to be poorly phagocytic, suggesting that other receptors such as βGR may play a more dominant role in particle internalization on professional phagocytes. Binding of zymosan to RAW 264.7 Mφ expressing SIGNR1 resulted in TNF-α production. Treatment of RAW 264.7 Mφ expressing SIGNR1, which express low levels of βGR, with β-glucans had little effect on binding or TNF-α production, indicating that there was no absolute requirement for βGR in this process. These studies have identified SIGNR1 as a major MR for fungal and other pathogens present on specific subsets of Mφ.
Abstract.
Mukhopadhyay S, Herre J, Brown GD, Gordon S (2004). The potential for Toll-like receptors to collaborate with other innate immune receptors.
IMMUNOLOGY,
112(4), 521-530.
Author URL.
Herre J, Willment JA, Gordon S, Brown GD (2004). The role of dectin-1 in antifungal immunity.
Critical Reviews in Immunology,
24(3), 193-203.
Abstract:
The role of dectin-1 in antifungal immunity
β-Glucans are structural components of fungal cell walls, which have a stimulatory effect on the immune system. Although a number of receptors for these carbohydrates have been proposed, the recently identified C-type lectin-like receptor, Dectin-1, appears to play a central role. Dectin-1 is expressed on phagocytic cells, including macrophages and neutrophils, and mediates both the internalization and cellular responses to β-glucan, through unique mechanisms. Dectin-1 can recognize and respond to live fungal pathogens and is being increasingly appreciated as having a key role in the innate responses to these pathogens. In addition to its exogenous ligands, Dectin-1 can recognize an unidentified endogenous ligand on T cells and may act as a co-stimulatory molecule, although its function in these responses is less clear. This review will highlight the current knowledge of Dectin-1 and its potential role in antifungal immunity, as well as deficiencies in our understanding.
Abstract.
2003
Steele C, Marrero L, Swain S, Harmsen AG, Zheng MQ, Brown GD, Gordon S, Shellito JE, Kolls JK (2003). Alveolar macrophage-mediated killing of Pneumocystis carinii f. sp muris involves molecular recognition by the dectin-1 beta-glucan receptor.
JOURNAL OF EXPERIMENTAL MEDICINE,
198(11), 1677-1688.
Author URL.
Martinez-Pomares L, Reid DM, Brown GD, Taylor PR, Stillion RJ, Linehan SA, Zamze S, Gordon S, Wong SYC (2003). Analysis of mannose receptor regulation by IL-4, IL-10, and proteolytic processing using novel monoclonal antibodies.
JOURNAL OF LEUKOCYTE BIOLOGY,
73(5), 604-613.
Author URL.
Willment JA, Lin HH, Reid DM, Taylor PR, Williams DL, Wong SYC, Gordon S, Brown GD (2003). Dectin-1 Expression and Function Are Enhanced on Alternatively Activated and GM-CSF-Treated Macrophages and Are Negatively Regulated by IL-10, Dexamethasone, and Lipopolysaccharide.
Journal of Immunology,
171(9), 4569-4573.
Abstract:
Dectin-1 Expression and Function Are Enhanced on Alternatively Activated and GM-CSF-Treated Macrophages and Are Negatively Regulated by IL-10, Dexamethasone, and Lipopolysaccharide
Dectin-1 is the major macrophage receptor for β-glucans and generates a proinflammatory response through the recognition of these carbohydrates on fungal pathogens. We have examined the effects of cytokines and other agents on the expression and functions of dectin-1 in both resident and elicited murine peritoneal macrophages (Mφ). Dectin-1 expression was found to be highly up-regulated by GM-CSF and by the cytokines that induce alternative macrophage activation, IL-4 and IL-13. In contrast, IL-10, LPS, and dexamethasone, but not IFN-γ, down-regulated the expression of this receptor. Modulation of dectin-1 receptor levels correlated with the ability of these macrophages to bind zymosan and significantly affected the contribution of this receptor to the resultant proinflammatory response, as measured by the production of TNF-α, although some Mφ-specific differences were observed. These results correlate with the known effects of these cytokines and other agents on the ability of the immune system to recognize and respond to fungal pathogens.
Abstract.
Brown GD, Herre J, Williams DL, Willment JA, Marshall ASJ, Gordon S (2003). Dectin-1 mediates the biological effects of β-glucans.
Journal of Experimental Medicine,
197(9), 1119-1124.
Abstract:
Dectin-1 mediates the biological effects of β-glucans
The ability of fungal-derived β-glucan particles to induce leukocyte activation and the production of inflammatory mediators, such as tumor necrosis factor (TNF)-α, is a well characterized phenomenon. Although efforts have been made to understand how these carbohydrate polymers exert their immunomodulatory effects, the receptors involved in generating these responses are unknown. Here we show that Dectin-1 mediates the production of TNF-α in response to zymosan and live fungal pathogens, an activity that occurs at the cell surface and requires the cytoplasmic tail and immunoreceptor tyrosine activation motif of Dectin-1 as well as Toll-like receptor (TLR)-2 and Myd88. This is the first demonstration that the inflammatory response to pathogens requires recognition by a specific receptor in addition to the TLRs. Furthermore, these studies implicate Dectin-1 in the production of TNF-α in response to fungi, a critical step required for the successful control of these pathogens.
Abstract.
Willment JA, Gordon S, Brown GD (2003). Detection and Control of Fungi by Macrophages: the Role of Carbohydrates and Antifungal Agents. In (Ed) The Macrophage as Therapeutic Target, 459-478.
Brown GD, Gordon S (2003). Fungal beta-glucans and mammalian immunity.
IMMUNITY,
19(3), 311-315.
Author URL.
Taylor PR, Brown GD, Geldhof AB, Martinez-Pomares L, Gordon S (2003). Pattern recognition receptors and differentiation antigens define murine myeloid cell heterogeneity ex vivo.
EUROPEAN JOURNAL OF IMMUNOLOGY,
33(8), 2090-2097.
Author URL.
2002
Brown GD, Taylor PR, Reid DM, Willment JA, Williams DL, Martinez-Pomares L, Wong SYC, Gordon S (2002). Dectin-1 is a major β-glucan receptor on macrophages.
Journal of Experimental Medicine,
196(3), 407-412.
Abstract:
Dectin-1 is a major β-glucan receptor on macrophages
Zymosan is a β-glucan- and mannan-rich particle that is widely used as a cellular activator for examining the numerous responses effected by phagocytes. The macrophage mannose receptor (MR) and complement receptor 3 (CR3) have historically been considered the major macrophage lectins involved in the nonopsonic recognition of these yeast-derived particles. Using specific carbohydrate inhibitors, we show that a β-glucan receptor, but not the MR, is a predominant receptor involved in this process. Furthermore, nonopsonic zymosan binding was unaffected by genetic CD11b deficiency or a blocking monoclonal antibody (mAb) against CR3, demonstrating that CR3 was not the β-glucan receptor mediating this activity. To address the role of the recently described β-glucan receptor, Dectin-1, we generated a novel anti-Dectin-1 mAb, 2A11. Using this mAb, we show here that Dectin-1 was almost exclusively responsible for the β-glucan-dependent, nonopsonic recognition of zymosan by primary macrophages. These findings define Dectin-1 as the leukocyte β-glucan receptor, first described over 50 years ago, and resolves the long-standing controversy regarding the identity of this important molecule. Furthermore, these results identify Dectin-1 as a new target for examining the immunomodulatory properties of β-glucans for therapeutic drug design.
Abstract.
Dave JA, Gey van Pittius NC, Beyers AD, Ehlers MRW, Brown GD (2002). Mycosin-1, a subtilisin-like serine protease of Mycobacterium tuberculosis, is cell wall-associated and expressed during infection of macrophages.
BMC MICROBIOLOGY,
2 Author URL.
Taylor PR, Brown GD, Reid DM, Willment JA, Martinez-Pomares L, Gordon S, Wong SYC (2002). The β-glucan receptor, dectin-1, is predominantly expressed on the surface of cells of the monocyte/macrophage and neutrophil lineages.
Journal of Immunology,
169(7), 3876-3882.
Abstract:
The β-glucan receptor, dectin-1, is predominantly expressed on the surface of cells of the monocyte/macrophage and neutrophil lineages
We recently identified dectin-1 (βGR) as a major β-glucan receptor on leukocytes and demonstrated that it played a significant role in the non-opsonic recognition of soluble and particulate β-glucans. Using a novel mAb (2A11) raised against βGR, we show here that the receptor is not dendritic cell-restricted as first reported, but is broadly expressed, with highest surface expression on populations of myeloid cells (monocyte/macrophage (MΦ) and neutrophil lineages). Dendritic cells and a subpopulation of T cells also expressed the βGR, but at lower levels. Alveolar MΦ, like inflammatory MΦ, exhibited the highest surface expression of βGR, indicative of a role for this receptor in immune surveillance. In contrast, resident peritoneal MΦ expressed much lower levels of βGR on the cell surface. Characterization of the nonopsonic recognition of zymosan by resident peritoneal MΦ suggested the existence of an additional β-glucan-independent mechanism of zymosan binding that was not observed on elicited or bone marrow-derived MΦ. Although this recognition could be inhibited by mannan, we were able to exclude involvement of the MΦ mannose receptor and complement receptor 3 in this process. These observations imply the existence of an additional mannan-dependent receptor involved in the recognition of zymosan by resident peritoneal MΦ.
Abstract.
2001
Willment JA, Gordon S, Brown GD (2001). Characterization of the Human β-Glucan Receptor and its Alternatively Spliced Isoforms.
Journal of Biological Chemistry,
276(47), 43818-43823.
Abstract:
Characterization of the Human β-Glucan Receptor and its Alternatively Spliced Isoforms
β-1,3-D-Glucans are biological response modifiers with potent effects on the immune system. A number of receptors are thought to play a role in mediating these responses, including murine Dectin-1, which we recently identified as a β-glucan receptor. In this study we describe the characterization of the human homologue of this receptor and show that it is structurally and functionally similar to the mouse receptor. The human β-glucan receptor is a type II transmembrane receptor with a single extracellular carbohydrate recognition domain and an immunoreceptor tyrosine activation motif in its cytoplasmic tail. The human β-glucan receptor is widely expressed and functions as a pattern recognition receptor, recognizing a variety of β-1,3- and/or β-1,6-linked glucans as well as intact yeast. In contrast to the murine receptor, the human receptor mRNA is alternatively spliced, resulting in two major (A and B) and six minor isoforms. The two major isoforms differ by the presence of a stalk region separating the carbohydrate recognition domain from the transmembrane region and are the only isoforms that are functional for β-glucan binding. The human receptor also binds T-lymphocytes at a site distinct from the β-glucan binding site, indicating that this receptor can recognize both endogenous and exogenous ligands.
Abstract.
Brown GD, Gordon S (2001). Immune recognition - a new receptor for beta-glucans.
NATURE,
413(6851), 36-37.
Author URL.
Gey van Pittius NC, Gamieldien J, Hide W, Brown GD, Siezen RJ, Beyers AD (2001). The ESAT-6 gene cluster of Mycobacterium tuberculosis and other high G+C Gram-positive bacteria. Genome Biology, 2(10).
2000
Brown GD, Dave JA, Gey van Pittius N, Stevens L, Ehlers MRW, Beyers AD (2000). The mycosins of Mycobacterium tuberculosis H37Rv: a family of subtilisin-like serine proteases.
GENE,
254(1-2), 147-155.
Author URL.
1998
Brown GD, Thomson JA (1998). Isolation and characterisation of an aryl-beta-D-glucoside uptake and utilisation system (abg) from the gram-positive ruminal Clostridium species C-longisporum.
MOLECULAR AND GENERAL GENETICS,
257(2), 213-218.
Author URL.
Meyers PR, Bourn WR, Steyn LM, Van Helden P, Beyers AD, Brown GD (1998). Novel method for rapid measurement of growth of mycobacteria in detergent-free media.
JOURNAL OF CLINICAL MICROBIOLOGY,
36(9), 2752-2754.
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