Publications by year
In Press
Malavia-Jones D, Farrer RA, Stappers MHT, Edmondson MB, Borman AM, Johnson EM, Lipke PN, Gow NAR (In Press). Strain and temperature dependent aggregation of<i>Candida auris</i>is attenuated by inhibition of surface amyloid proteins.
Abstract:
Strain and temperature dependent aggregation ofCandida aurisis attenuated by inhibition of surface amyloid proteins
ABSTRACTCandida aurisis a multi-drug resistant human fungal pathogen that has become a global threat to human health due to its drug resistant phenotype, persistence in the hospital environment and propensity for patient to patient spread. Isolates display variable aggregation that may affect the relative virulence of strains. Therefore, dissection of this phenotype has gained substantial interest in recent years. We studied eight clinical isolates from four different clades (I-IV); four of which had a strongly aggregating phenotype and four of which did not. Genome analysis identified polymorphisms associated with loss of cell surface proteins were enriched in weakly-aggregating strains. Additionally, we identified down-regulation of chitin synthase and chitinase genes involved in the synthesis and dissolution of the chitinous septum. Characterisation of the cells revealed no ultrastructural defects in cytokinesis or cell separation in aggregating isolates. Strongly and weakly aggregating strains did not differ in net surface charge or in cell surface hydrophobicity. The capacity for aggregation and for adhesion to polystyrene microspheres were also not correlated. However, aggregation and extracellular matrix formation were all increased at higher growth temperatures, and treatment with the amyloid protein inhibitor Thioflavin-T markedly attenuated aggregation. Genome analysis further indicated strain specific differences in the genome content of GPI-anchored proteins including those encoding genes with the potential to form amyloid proteins. Collectively our data suggests that aggregation is a complex strain and temperature dependent phenomenon that may be linked in part to the ability to form extracellular matrix and cell surface amyloids.HIGHLIGHTSThe amyloid inhibitor Thioflavin-T inhibitedC. aurisaggregation. Aggregating isolates do not exhibit any defects in cell separation.Genomic differences were identified between strongly aggregating and weakly-aggregating strains ofC. auris.Aggregation did not correlate with surface charge or hydrophobicity of yeast cells.
Abstract.
2023
Krylov VB, Gómez-Redondo M, Solovev AS, Yashunsky DV, Brown AJP, Stappers MHT, Gow NAR, Ardá A, Jiménez-Barbero J, Nifantiev NE, et al (2023). Identification of a new DC-SIGN binding pentamannoside epitope within the complex structure of Candida albicans mannan.
The Cell Surface,
10Abstract:
Identification of a new DC-SIGN binding pentamannoside epitope within the complex structure of Candida albicans mannan
The dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) is an innate immune C-type lectin receptor that recognizes carbohydrate-based pathogen associated with molecular patterns of various bacteria, fungi, viruses and protozoa. Although a range of highly mannosylated glycoproteins have been shown to induce signaling via DC-SIGN, precise structure of the recognized oligosaccharide epitope is still unclear. Using the array of oligosaccharides related to selected fragments of main fungal antigenic polysaccharides we revealed a highly specific pentamannoside ligand of DC-SIGN, consisting of α-(1 → 2)-linked mannose chains with one inner α-(1 → 3)-linked unit. This structural motif is present in Candida albicans cell wall mannan and corresponds to its antigenic factors 4 and 13b. This epitope is not ubiquitous in other yeast species and may account for the species-specific nature of fungal recognition via DC-SIGN. The discovered highly specific oligosaccharide ligands of DC-SIGN are tractable tools for interdisciplinary investigations of mechanisms of fungal innate immunity and anti-Candida defense. Ligand- and receptor-based NMR data demonstrated the pentasaccharide-to-DC-SIGN interaction in solution and enabled the deciphering of the interaction topology.
Abstract.
Malavia-Jones D, Farrer RA, Stappers MHT, Edmondson MB, Borman AM, Johnson EM, Lipke PN, Gow NAR (2023). Strain and temperature dependent aggregation of Candida auris is attenuated by inhibition of surface amyloid proteins. The Cell Surface, 10, 100110-100110.
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.
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.
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).
2020
Peeters T, Martens S, D’Onofrio V, Stappers MHT, van der Hilst JCH, Houben B, Achten R, Joosten LAB, Gyssens IC (2020). An observational study of innate immune responses in patients with acute appendicitis.
Scientific Reports,
10(1).
Abstract:
An observational study of innate immune responses in patients with acute appendicitis
Acute appendicitis is a common surgical emergency worldwide. Exaggerated immune responses could be associated with appendicitis. This study aimed at characterizing immune responses towards a large variety of gut commensals and pathogens, and pattern recognition receptor (PRR) ligands, and investigating the course of systemic inflammation in a prospective cohort of acute appendicitis patients. PBMC responses of 23 patients of the cohort and 23 healthy controls were characterized more than 8 months post-surgery. Serum cytokine levels were measured in 23 patients at the time of appendicitis and after one month. CRP, WBC and percentage of neutrophils were analyzed in the total cohort of 325 patients. No differences in PBMC responses were found between patients and controls. Stronger IL-10 responses were found following complicated appendicitis. A trend towards lower IL-8 responses was shown following gangrenous appendicitis. Serum IL-10 and IL-6 were significantly elevated at presentation, and IL-6, IL-8 and TNF-α levels were higher in complicated appendicitis. Routine biomarkers could predict severity of appendicitis with high specificities, but low sensitivities. Cytokine responses in patients following acute appendicitis did not differ from healthy controls. Higher serum cytokine levels were found in acute complicated and gangrenous cases. Further research into discriminative biomarkers is warranted.
Abstract.
D’Onofrio V, Monnier AA, Kremer C, Stappers MHT, Netea MG, Gyssens IC (2020). Lesion size is associated with genetic polymorphisms in TLR1, TLR6, and TIRAP genes in patients with major abscesses and diabetic foot infections.
European Journal of Clinical Microbiology and Infectious Diseases,
39(2), 353-360.
Abstract:
Lesion size is associated with genetic polymorphisms in TLR1, TLR6, and TIRAP genes in patients with major abscesses and diabetic foot infections
Genetic variation in Toll-like receptors (TLRs) has previously been associated with susceptibility to complicated skin and skin structure infections (cSSSIs). The aim of this study was to investigate associations between the severity of cSSSIs, i.e. major abscesses and diabetic foot infections (DFIs), and a set of genetic polymorphisms in the Toll-like receptor pathway. A total of 121 patients with major abscesses and 132 with DFIs participating in a randomized clinical trial were genotyped for 13 nonsynonymous single-nucleotide polymorphisms (SNPs) in genes coding for TLRs and the signaling adaptor molecule TIRAP. Infection severity was defined by lesion size at clinical presentation for both types of infections. The PEDIS infection score was also used to define severity of DFIs. Linear regression models were used to study factors independently associated with severity. In patients with large abscesses, hetero- or homozygosity for the allelic variant TLR6 (P249S) was associated with significantly smaller lesions while homozygosity for the allelic variant TLR1 (R80T) was associated with significantly larger lesions. PRRs genes were not significantly associated with PEDIS. However, patients with DFI hetero- or homozygous for the allelic variant TLR1 (S248N) had significantly larger lesions. Polymorphisms in TLR1 and TLR6 influence the severity of cSSSIs as assessed by the lesion size of major abscesses and DFIs. ClinicalTrial.gov Identifier: NCT 00402727
Abstract.
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.
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.
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.
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
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.
2017
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.
2016
Stappers MHT, Hagen F, Reimnitz P, Mouton JW, Meis JF, Gyssens IC (2016). Bacteroides fragilis in biopsies of patients with major abscesses and diabetic foot infections: Direct molecular versus culture-based detection.
Diagnostic Microbiology and Infectious Disease,
85(2), 263-265.
Abstract:
Bacteroides fragilis in biopsies of patients with major abscesses and diabetic foot infections: Direct molecular versus culture-based detection
Direct determination by pathogen-specific real-time PCR assay for Bacteroides fragilis was compared to culture in major abscess and diabetic foot infection biopsy samples. Real-time PCR resulted in an increased detection rate of 12% for B. fragilis and could improve the detection of B. fragilis in clinical samples.
Abstract.
Ammerdorffer A, Stappers MHT, Oosting M, Schoffelen T, Hagenaars JCJP, Bleeker-Rovers CP, Wegdam-Blans MC, Wever PC, Roest HJ, van de Vosse E, et al (2016). Genetic variation in TLR10 is not associated with chronic Q fever, despite the inhibitory effect of TLR10 on Coxiella burnetii-induced cytokines in vitro.
Cytokine,
77, 196-202.
Abstract:
Genetic variation in TLR10 is not associated with chronic Q fever, despite the inhibitory effect of TLR10 on Coxiella burnetii-induced cytokines in vitro
Coxiella burnetii, the causative agent of Q fever, is recognized by TLR2. TLR10 can act as an inhibitory receptor on TLR2-derived immune responses. Therefore, we investigated the role of TLR10 on C. burnetii-induced cytokine production and assessed whether genetic polymorphisms in TLR10 influences the development of chronic Q fever. HEK293 cells, transfected with TLR2, TLR10 or TLR2/TLR10, and human peripheral blood mononuclear cells (PBMCs) in the presence of anti-TLR10, were stimulated with C. burnetii. In both assays, the absence of TLR10 resulted in increased cytokine responses after C. burnetii stimulation. In addition, the effect of single nucleotide polymorphisms (SNPs) in TLR10 was examined in healthy volunteers whose PBMCs were stimulated with C. burnetii Nine Mile or the Dutch outbreak isolate C. burnetii 3262. Individuals bearing SNPs in TLR10 displayed increased cytokine production upon C. burnetii 3262 stimulation. Furthermore, 139 chronic Q fever patients and 220 controls were genotyped for TLR10 N241H, I775V and I369L. None of these polymorphisms were associated with increased susceptibility to chronic Q fever. In conclusion, TLR10 has an inhibitory effect on in vitro cytokine production by C. burnetii, but the presence of TLR10 polymorphisms does not lead to an increased risk of developing chronic Q fever.
Abstract.
2015
Stappers MHT, Hagen F, Reimnitz P, Mouton JW, Meis JF, Gyssens IC (2015). Direct molecular versus culture-based assessment of Gram-positive cocci in biopsies of patients with major abscesses and diabetic foot infections.
EUROPEAN JOURNAL OF CLINICAL MICROBIOLOGY & INFECTIOUS DISEASES,
34(9), 1885-1892.
Author URL.
Stappers MHT, Oosting M, Ioana M, Reimnitz P, Mouton JW, Netea MG, Gyssens IC, Joosten LAB (2015). Genetic variation in TLR10, an inhibitory toll-like receptor, influences susceptibility to complicated skin and skin structure infections.
Journal of Infectious Diseases,
212(9), 1491-1499.
Abstract:
Genetic variation in TLR10, an inhibitory toll-like receptor, influences susceptibility to complicated skin and skin structure infections
Background.Toll-like receptors (TLRs) play a central role in the innate immune response to complicated skin and skin structure infections (cSSSIs), with TLR10 being the first family member known to have an inhibitory function. This study assessed the role of TLR10 in recognition of cSSSI-related pathogens and whether genetic variation in TLR10 influences susceptibility to cSSSIs. Methods.Human peripheral blood mononuclear cells (PBMCs) preincubated with anti-TLR10 antibody and HEK-293 cells overexpressing TLRs were exposed to cSSSI pathogens, and cytokine secretion was determined by enzyme-linked immunosorbent assay. A total of 318 patients with cSSSI and 328 healthy controls were genotyped for 4 nonsynonymous single-nucleotide polymorphisms in TLR10, and functional consequences of the TLR10 SNPs were assessed via in vitro stimulation assays. Results.PBMC stimulation with cSSSI pathogens in the presence of TLR10 neutralizing antibody significantly increased interleukin 6 secretion. Overexpression of TLR10 completely abrogated TLR2-induced interleukin 8 secretion by HEK-293 cells in response to cSSSI pathogens. Three polymorphisms in TLR10, I775L, I369L, and N241H, were associated with reduced susceptibility to cSSSIs. The presence of the TLR10 alleles 775L, 369L, or 241H increased interleukin 6 secretion by PBMCs in response to cSSSI pathogens. Conclusions.TLR10 is a modulatory receptor of innate immune responses to cSSSI-related pathogens, and genetic variants in TLR10 are associated with protection against cSSSIs.
Abstract.
Jaeger M, Stappers MHT, Joosten LAB, Gyssens IC, Netea MG (2015). Genetic variation in pattern recognition receptors: Functional consequences and susceptibility to infectious disease.
Future Microbiology,
10(6), 989-1008.
Abstract:
Genetic variation in pattern recognition receptors: Functional consequences and susceptibility to infectious disease
Cells of the innate immune system are equipped with surface and cytoplasmic receptors for microorganisms called pattern recognition receptors (PRRs). PRRs recognize specific pathogen-associated molecular patterns and as such are crucial for the activation of the immune system. Currently, five different classes of PRRs have been described: Toll-like receptors, C-type lectin receptors, nucleotide-binding oligomerization domain-like receptors, retinoic acid-inducible gene I-like receptors and absent in melanoma 2-like receptors. Following their discovery, many sequence variants in PRR genes have been uncovered and shown to be implicated in human infectious diseases. In this review, we will discuss the effect of genetic variation in PRRs and their signaling pathways on susceptibility to infectious diseases in humans.
Abstract.
2014
Stappers MHT, Thys Y, Oosting M, Plantinga TS, Ioana M, Reimnitz P, Mouton JW, Netea MG, Joosten LAB, Gyssens IC, et al (2014). Polymorphisms in cytokine genes IL6, TNF, IL10, IL17A and IFNG influence susceptibility to complicated skin and skin structure infections.
EUROPEAN JOURNAL OF CLINICAL MICROBIOLOGY & INFECTIOUS DISEASES,
33(12), 2267-2274.
Author URL.
Stappers MHT, Thys Y, Oosting M, Plantinga TS, Ioana M, Reimnitz P, Mouton JW, Netea MG, Joosten LAB, Gyssens IC, et al (2014). TLR1, TLR2, and TLR6 gene polymorphisms are associated with increased susceptibility to complicated skin and skin structure infections.
Journal of Infectious Diseases,
210(2), 311-318.
Abstract:
TLR1, TLR2, and TLR6 gene polymorphisms are associated with increased susceptibility to complicated skin and skin structure infections
Background. Complicated skin and skin structure infections (cSSSIs) are characterized by infections with gram-positive or gram-negative aerobic or anaerobic bacteria, as well as by a polymicrobial etiology. These invading microorganisms are recognized by pattern-recognition receptors (PRRs) of the innate immune system. This study assessed whether genetic variation in genes encoding PRRs influences the susceptibility to cSSSIs. Methods. A total of 318 patients with cSSSI and 328 healthy controls were genotyped for 9 nonsynonymous single-nucleotide polymorphisms (SNPs) in PRR genes coding for Toll-like receptors (TLRs) 1, 2, 4, and 6; NOD-like receptor 2; and the signaling adaptor molecule TIRAP. Associations between susceptibility to cSSSIs and a SNP were investigated by means of logistic regression models. In an additional cohort of 74 healthy individuals in whom the same SNPs were genotyped, peripheral blood mononuclear cells (PBMCs) were obtained and stimulated with Staphylococcus aureus. Interleukin 6 concentrations were determined in supernatants by enzyme-linked immunosorbent assay to determine the correlation between genotypes and levels of IL-6 secretion. Results. In the genetic association analysis, polymorphisms in TLR1 (S248N and R80T), TLR2 (P631H), and TLR6 (P249S) were associated with an increased susceptibility to cSSSIs. No association with susceptibility to cSSSIs was observed for polymorphisms TLR2 (R753Q), TLR4 (D299G and T399I), NOD2 (P268S), and TIRAP (S180L). In the functional analysis, individuals bearing the TLR1 248N or 80T allele showed lower IL-6 secretion upon stimulation with S. aureus. Conclusions. Polymorphisms in TLR1, TLR2, and TLR6 are associated with increased susceptibility to cSSSIs. For TLR1, impaired proinflammatory cytokine production due to the polymorphism is most likely the mechanism mediating this effect. © 2014 the Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved.
Abstract.
2012
Stappers MHT, Janssen NAF, Oosting M, Plantinga TS, Arvis P, Mouton JW, Joosten LAB, Netea MG, Gyssens IC (2012). A role for TLR1, TLR2 and NOD2 in cytokine induction by Bacteroides fragilis.
Cytokine,
60(3), 861-869.
Abstract:
A role for TLR1, TLR2 and NOD2 in cytokine induction by Bacteroides fragilis
Bacteroides fragilis, an intestinal flora commensal microorganism, is frequently isolated from abscesses and soft tissue infections. This study aimed to identify pattern recognition receptors (PRRs) involved in B. fragilis recognition and to characterize the induced cytokine profile. Human PBMCs were stimulated with heat-killed B. fragilis and cytokine levels were determined by ELISA. Roles of individual PRRs were assessed using specific blockers of receptor signaling pathways and PBMCs carrying single nucleotide polymorphisms of PRR genes. Cell lines expressing human TLR2 or TLR4 were employed to assess TLR-specificity of B. fragilis. TLR1, TLR2 and NOD2 were the main PRRs responsible for recognition of B. fragilis, while TLR4, TLR6, NOD1 and Dectin-1 were not involved. B. fragilis induced strong IL-6 and IL-8, moderate IL-1β and TNF-α, and poor IL-10, IL-17, IL-23 and IFN-γ production. This study identifies the receptor pathways of the innate immune response to B. fragilis, and thus provides new insights in the host defense against B. fragilis. © 2012 Elsevier Ltd.
Abstract.
Ioana M, Ferwerda B, Plantinga TS, Stappers M, Oosting M, McCall M, Cimpoeru A, Burada F, Panduru N, Sauerwein R, et al (2012). Different patterns of Toll-like receptor 2 polymorphisms in populations of various ethnic and geographic origins.
Infect Immun,
80(5), 1917-1922.
Abstract:
Different patterns of Toll-like receptor 2 polymorphisms in populations of various ethnic and geographic origins.
Upon the invasion of the host by microorganisms, innate immunity is triggered through pathogen recognition by pattern recognition receptors (PRRs). Toll-like receptors (TLRs) are the best-studied class of PRRs, and they recognize specific pathogen-associated molecular patterns (PAMPs) from various microorganisms. A large number of studies have shown that genetic variation in TLRs may influence susceptibility to infections. We assessed the genetic variation of TLR2, which encodes one of the most important TLRs, in various populations around the globe and correlated it with changes in the function of the molecule. The three best-known nonsynonymous TLR2 polymorphisms (1892C>A, 2029C>T, and 2258G>A) were assessed in different populations from the main continental masses: Romanians, Vlax-Roma, Dutch (European populations), Han Chinese (East Asia), Dogon, Fulani (Africa), and Trio Indians (America). The 2029C>T polymorphism was absent in both European and non-European populations, with the exception of the Vlax-Roma, suggesting that this polymorphism most likely arose in Indo-Aryan people after migration into South Asia. The 1892C>A polymorphism that was found exclusively in European populations, but not in Asian, African, or American volunteers, probably occurred in proto-Indo-Europeans. Interestingly, 2258G>A was present only in Europeans, including Vlax-Roma, but at a very low frequency. The differential pattern of the TLR2 polymorphisms in various populations may explain some of the differences in susceptibility to infections between these populations.
Abstract.
Author URL.
2011
Marijnissen RJ, Koenders MI, Smeets RL, Stappers MH, Nickerson-Nutter C, Joosten LA, Boots AM, van den Berg WB (2011). Increased IL-22 expression by synovial Th17 cells during late stages of arthritis is controlled by IL-1 and enhances bone degradation. Annals of the Rheumatic Diseases, 70(Suppl 2).
Marijnissen RJ, Koenders MI, Smeets RL, Stappers MHT, Nickerson-Nutter C, Joosten LAB, Boots AMH, Van Den Berg WB (2011). Increased expression of interleukin-22 by synovial Th17 cells during late stages of murine experimental arthritis is controlled by interleukin-1 and enhances bone degradation.
Arthritis and Rheumatism,
63(10), 2939-2948.
Abstract:
Increased expression of interleukin-22 by synovial Th17 cells during late stages of murine experimental arthritis is controlled by interleukin-1 and enhances bone degradation
Objective Interleukin-22 (IL-22) is a mediator in antimicrobial responses and inflammatory autoimmune diseases. Although IL-22 and its receptor, IL-22R, have been identified in the synovium of rheumatoid arthritis patients, the source of IL-22 and its contribution to disease pathogenicity remain to be established. This study was undertaken to investigate the regulation of IL-22 by Th17 cells in vitro and to evaluate the potential for IL-22 depletion in an experimental arthritis model using mice deficient in the IL-1 receptor antagonist (IL-1Ra-/-). Methods Naive murine T cells were cultured under conditions leading to polarization of the cells into subsets of Th1, Th2, induced Treg, and Th17. Cytokines were measured in the culture supernatants, and the cells were analyzed by fluorescence-activated cell sorting. Tissue samples from the inflamed ankle synovium of IL-1Ra-/- mice were isolated, and messenger RNA levels of marker genes were quantified. IL-1Ra-/- mice were treated with neutralizing anti-IL-22 antibodies. Synovial cells were isolated from the inflamed tissue and sorted into fractions for analysis of cytokine production. Results in vitro tests showed that Th17 cells produced high levels of IL-22 after stimulation with IL-1 or IL-23. Interestingly, a synergistic increase in the production of IL-22 was observed after combining IL-1 and IL-23. In vivo, IL-1Ra-/- mice displayed a progressive erosive arthritis, characterized by up-regulation of IL-17 in mildly and severely inflamed tissue, whereas the levels of IL-22 and IL-22R were increased only in severely inflamed synovia. Anti-IL-22 treatment of IL-1Ra-/- mice significantly reduced the inflammation and bone erosion. Analysis of isolated single cells from the inflamed synovia revealed that IL-22 was mainly produced by IL-17-expressing T cells. Conclusion These findings suggest that IL-22 plays an important role in IL-1-driven chronic joint destruction. Copyright © 2011 by the American College of Rheumatology.
Abstract.
2010
Bosman GJCGM, Stappers M, Novotný VMJ (2010). Changes in band 3 structure as determinants of erythrocyte integrity during storage and survival after transfusion.
Blood Transfus,
8 Suppl 3(Suppl 3), s48-s52.
Author URL.