Mark H T Stappers

Radboud University Medical Centre (Radboudumc), Nymegen, Gelderland, Netherlands

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Publications (6)22.57 Total impact

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    ABSTRACT: Complicated skin and skin structure infections (cSSSIs) are caused by Gram-positive and Gram-negative, aerobic and anaerobic pathogens, with a polymicrobial aetiology being frequent. Recognition of invading pathogens by the immune system results in the production of pro- and anti-inflammatory cytokines, which are extremely important for intercellular communication and control of infection. This study assessed whether genetic variation in genes encoding cytokines influences the susceptibility to cSSSIs. For the association study, 318 patients with cSSSI and 328 healthy controls were genotyped for single nucleotide polymorphisms (SNPs) in cytokine genes IL1A, IL1B, IL1RN, TNF, IL10, IL17A, IL17F and IFNG. For immunological validation, peripheral blood mononuclear cells (PBMCs) from 74 healthy individuals, genotyped for SNPs of interest, were stimulated with Staphylococcus aureus or Escherichia coli and corresponding cytokine levels were determined by enzyme-linked immunosorbent assay (ELISA). Polymorphisms IL6 rs1800797, TNF rs1800629, IL10 rs1800871, IL17A rs8193036 and IFNG rs2069705 influenced susceptibility to cSSSIs. No differences in cytokine responses, stratified for genotype, were detected after PBMC stimulation. No association with cSSSIs was observed for polymorphisms IL1A rs17561 and rs1800587, IL1B rs16944 and rs1143627, IL1RN rs4251961, TNF rs361525, IL10 rs1800896, IL17A rs2275913 and IL17F rs763780. In conclusion, polymorphisms in IL6, TNF, IL10, IL17A and IFNG are associated with susceptibility to cSSSIs.
    07/2014;
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    ABSTRACT: Background. Complicated skin and skin structure infections (cSSSIs) are characterized by infections with either Gram-positive and Gram-negative aerobic or anaerobic bacteria, as well as 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. 318 cSSSI patients and 328 healthy controls were genotyped for 9 non-synonymous single nucleotide polymorphisms (SNPs) in PRR genes coding for Toll-like receptors (TLR)1/2/4/6, NOD-like receptor 2 and signaling adaptor TIRAP. PBMCs obtained from 74 SNP-genotyped healthy individuals were stimulated with Staphylococcus aureus. IL-6 cytokine concentrations were determined in supernatants by ELISA.Results. Polymorphisms in TLR1 (S248N and R80T), TLR2 (P631H) and TLR6 (P249S) increased susceptibility to cSSSIs. Furthermore, PBMCs from individuals bearing the TLR1 248N or 80T allele showed lower IL-6 secretion upon stimulation with S. aureus. No association with susceptibility to cSSSIs was observed for polymorphisms TLR2 (R753Q), TLR4 (D299G and T399I), NOD2 (P268S) and TIRAP (S180 L).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.
    The Journal of Infectious Diseases 02/2014; · 5.85 Impact Factor
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    ABSTRACT: 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.
    Cytokine 12/2012; 60(3):861–869. · 2.52 Impact Factor
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    ABSTRACT: 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.
    Infection and immunity 02/2012; 80(5):1917-22. · 4.21 Impact Factor
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    ABSTRACT: 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-/-). 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. 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. These findings suggest that IL-22 plays an important role in IL-1-driven chronic joint destruction.
    Arthritis & Rheumatology 05/2011; 63(10):2939-48. · 7.48 Impact Factor
  • Cytokine 01/2011; 56(1):93-93. · 2.52 Impact Factor

Publication Stats

25 Citations
22.57 Total Impact Points

Institutions

  • 2012–2014
    • Radboud University Medical Centre (Radboudumc)
      • Department of Human Genetics
      Nymegen, Gelderland, Netherlands
    • Universitatea de Medicina si Farmacie Craiova
      Croiova, Dolj, Romania
    • Canisius-Wilhelmina Ziekenhuis
      Nymegen, Gelderland, Netherlands