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Sökning: WFRF:(Burkhardt Harald)

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  • Ge, Changrong, et al. (författare)
  • Anti-citrullinated protein antibodies cause arthritis by cross-reactivity to joint cartilage
  • 2017
  • Ingår i: JCI insight. - : AMER SOC CLINICAL INVESTIGATION INC. - 2379-3708. ; 2:13
  • Tidskriftsartikel (refereegranskat)abstract
    • Today, it is known that autoimmune diseases start a long time before clinical symptoms appear. Anti-citrullinated protein antibodies (ACPAs) appear many years before the clinical onset of rheumatoid arthritis (RA). However, it is still unclear if and how ACPAs are arthritogenic. To better understand the molecular basis of pathogenicity of ACPAs, we investigated autoantibodies reactive against the C1 epitope of collagen type II (CII) and its citrullinated variants. We found that these antibodies are commonly occurring in RA. A mAb (ACC1) against citrullinated C1 was found to cross-react with several noncitrullinated epitopes on native CII, causing proteoglycan depletion of cartilage and severe arthritis in mice. Structural studies by X-ray crystallography showed that such recognition is governed by a shared structural motif "RG-TG" within all the epitopes, including electrostatic potential-controlled citrulline specificity. Overall, we have demonstrated a molecular mechanism that explains how ACPAs trigger arthritis.
  • Apel, Maria, et al. (författare)
  • Variants in RUNX3 Contribute to Susceptibility to Psoriatic Arthritis, Exhibiting Further Common Ground With Ankylosing Spondylitis
  • 2013
  • Ingår i: Arthritis and Rheumatism. - 0004-3591 .- 1529-0131. ; 65:5, s. 1224-1231
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective Psoriatic arthritis (PsA) is a common inflammatory joint disease distinct from other chronic arthritides and frequently accompanied by psoriasis vulgaris. In a first genome-wide association study (GWAS), we were able to identify several genetic risk factors. However, even combined with previously identified factors, the genetic contribution to disease was not fully explained. Therefore, we undertook this study to investigate further 17 loci from our GWAS that did not reach genome-wide significance levels of association in the initial analysis. Methods Twenty-one of 22 single-nucleotide polymorphisms were successfully genotyped in independent cohorts of 1,398 PsA patients and 6,389 controls and in a group of 964 German patients with psoriasis vulgaris. Results Association with a RUNX3 variant, rs4649038, was replicated in independent patients and controls and resulted in a combined P value of 1.40 x 108 by Cochran-Mantel-Haenszel test and an odds ratio (OR) of 1.24 (95% confidence interval [95% CI] 1.151.33). Further analyses based on linkage disequilibrium (LD) at RUNX3 refined the most significant association to an LD block located in the first intron of one isoform. Weaker evidence for association was detected in German patients with psoriasis vulgaris (P = 5.89 x 102; OR 1.13 [95% CI 1.001.28]), indicating a role in the skin manifestations of psoriasis. Conclusion Our analyses identified variants in RUNX3 as susceptibility factors for PsA. RUNX3 has already been implicated in susceptibility to ankylosing spondylitis, another spondyloarthritis, although its risk allele is independent from the one for PsA. RUNX-3 is involved in CD8+ T lymphocyte differentiation and is therefore a good candidate for involvement in PsA and psoriasis vulgaris as T cellmediated diseases.
  • Boeiers, Ulrika, et al. (författare)
  • Collagen type II is recognized by a pathogenic antibody through germline encoded structures
  • 2008
  • Ingår i: European Journal of Immunology. - : John Wiley and Sons Inc.. - 1521-4141. ; 38:10, s. 2784-2795
  • Tidskriftsartikel (refereegranskat)abstract
    • Collagen type II (CII) is a cartilage-specific target of pathologic humoral autoimmune responses in rheumatoid arthritis as well as in the collagen-induced arthritis model. The aim of the present study is to investigate the critical amino acid residues conferring CII epitope specificity of the prototypic arthritogenic murine mAb CIIC1. A homology model of the CIIC1 single-chain antibody fragment (CIIC1scFv) in complex with its triple helical epitope was established. in silico predictions based on extensive molecular dynamics simulations were experimentally tested by the recombinant expression and functional analysis of CIIC1scFv containing alanine replacements allowing the identification of crucial CII-binding sites in the CDR2 and CDR3 regions of both heavy and light chains. Since the conversion of the CIIC1scFv sequence into the respective germline at all 13 somatically mutated positions did not affect its CII binding, our data indicate that potentially harmful cartilage-specific humoral autoimmunity could be germline encoded. The molecular modeling further demonstrates that the rigid collagen triple helix restricts the likelihood of molecular interactions with the CDR regions of the antibody considerably compared with globular antigens. These sterical constraints provide an explanation as to why somatic mutations in the arthritogenic autoantibody have no obvious impact on CII recognition.
  • Dobritzsch, Doreen, 1972-, et al. (författare)
  • Crystal structure of an arthritogenic anticollagen immune complex
  • 2011
  • Ingår i: Arthritis and Rheumatism. - 0004-3591 .- 1529-0131. ; 63:12, s. 3740-3748
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVE: In rheumatoid arthritis, joint inflammation and cartilage destruction are mediated by autoantibodies directed to various self antigens. Type II collagen (CII)-specific antibodies are likely to play a role in this process and have been shown to induce experimental arthritis in susceptible animals. The purpose of this study was to reveal how arthritogenic autoantibodies recognize native CII in its triple-helical conformation.METHODS: Site-directed mutagenesis and crystallographic studies were performed to reveal crucial contact points between the CII antibody and the triple-helical CII peptide.RESULTS: The crystal structure of a pathogenic autoantibody bound to a major triple-helical epitope present on CII was determined, allowing a first and detailed description of the interactions within an arthritogenic complex that is frequently occurring in both mice and humans with autoimmune arthritis. The crystal structure emphasizes the role of arginine residues located in a commonly recognized motif on CII and reveals that germline-encoded elements are involved in the interaction with the epitope.CONCLUSION: The crystal structure of an arthritogenic antibody binding a triple-helical epitope on CII indicates a crucial role of germline-encoded and arginine residues as the target structures.
  • Hüffmeier, Ulrike, et al. (författare)
  • Common variants at TRAF3IP2 are associated with susceptibility to psoriatic arthritis and psoriasis
  • 2010
  • Ingår i: Nature Genetics. - 1061-4036 .- 1546-1718. ; 42:11, s. 996-999
  • Tidskriftsartikel (refereegranskat)abstract
    • Psoriatic arthritis (PsA) is an inflammatory joint disease that is distinct from other chronic arthritides and which is frequently accompanied by psoriasis vulgaris (PsV) and seronegativity for rheumatoid factor. We conducted a genome-wide association study in 609 German individuals with PsA (cases) and 990 controls with replication in 6 European cohorts including a total of 5,488 individuals. We replicated PsA associations at HLA-C and IL12B and identified a new association at TRAF3IP2 (rs13190932, P = 8.56 × 10⁻¹⁷). TRAF3IP2 was also associated with PsV in a German cohort including 2,040 individuals (rs13190932, P = 1.95 × 10⁻³). Sequencing of the exons of TRAF3IP2 identified a coding variant (p.Asp10Asn, rs33980500) as the most significantly associated SNP (P = 1.13 × 10⁻²⁰, odds ratio = 1.95). Functional assays showed reduced binding of this TRAF3IP2 variant to TRAF6, suggesting altered modulation of immunoregulatory signals through altered TRAF interactions as a new and shared pathway for PsA and PsV.
  • Uysal, Hüseyin, et al. (författare)
  • Structure and pathogenicity of antibodies specific for citrullinated collagen type II in experimental arthritis.
  • 2009
  • Ingår i: Journal of Experimental Medicine. - : Rockefeller University Press. - 1540-9538 .- 0022-1007. ; 206:2, s. 449-462
  • Tidskriftsartikel (refereegranskat)abstract
    • Antibodies to citrulline-modified proteins have a high diagnostic value in rheumatoid arthritis (RA). However, their biological role in disease development is still unclear. To obtain insight into this question, a panel of mouse monoclonal antibodies was generated against a major triple helical collagen type II (CII) epitope (position 359-369; ARGLTGRPGDA) with or without arginines modified by citrullination. These antibodies bind cartilage and synovial tissue, and mediate arthritis in mice. Detection of citrullinated CII from RA patients' synovial fluid demonstrates that cartilage-derived CII is indeed citrullinated in vivo. The structure determination of a Fab fragment of one of these antibodies in complex with a citrullinated peptide showed a surprising beta-turn conformation of the peptide and provided information on citrulline recognition. Based on these findings, we propose that autoimmunity to CII, leading to the production of antibodies specific for both native and citrullinated CII, is an important pathogenic factor in the development of RA.
  • Bowes, John, et al. (författare)
  • PTPN22 is associated with susceptibility to psoriatic arthritis but not psoriasis : evidence for a further PsA-specific risk locus
  • 2015
  • Ingår i: Annals of the Rheumatic Diseases. - 0003-4967 .- 1468-2060. ; 74:10, s. 1882-1885
  • Tidskriftsartikel (refereegranskat)abstract
    • Objectives Psoriatic arthritis (PsA) is a chronic inflammatory arthritis associated with psoriasis; it has a higher estimated genetic component than psoriasis alone, however most genetic susceptibility loci identified for PsA to date are also shared with psoriasis. Here we attempt to validate novel single nucleotide polymorphisms selected from our recent PsA Immunochip study and determine specificity to PsA. Methods A total of 15 single nucleotide polymorphisms were selected (P-Immunochip <1x10(-4)) for validation genotyping in 1177 cases and 2155 controls using TaqMan. Meta-analysis of Immunochip and validation data sets consisted of 3139 PsA cases and 11 078 controls. Novel PsA susceptibility loci were compared with data from two large psoriasis studies (WTCCC2 and Immunochip) to determine PsA specificity. Results We found genome-wide significant association to rs2476601, mapping to PTPN22 (p=1.49x10(-9), OR=1.32), but no evidence for association in the psoriasis cohort (p=0.34) and the effect estimates were significantly different between PsA and psoriasis (p=3.2x10(-4)). Additionally, we found genome-wide significant association to the previously reported psoriasis risk loci; NOS2 (rs4795067, p=5.27x10(-9)). Conclusions For the first time, we report genome-wide significant association of PTPN22 (rs2476601) to PsA susceptibility, but no evidence for association to psoriasis.
  • Bäcklund, Johan, et al. (författare)
  • Predominant selection of T cells specific for the glycosylated collagen type II epitope (263-270) in humanized transgenic mice and in rheumatoid arthritis.
  • 2002
  • Ingår i: Proceedings of the National Academy of Sciences. - : National Acad Sciences. - 1091-6490. ; 99:15, s. 9960-9965
  • Tidskriftsartikel (refereegranskat)abstract
    • Rheumatoid arthritis (RA) is associated with certain MHC class II alleles and is characterized by a chronic autoimmune response in the joints. Using transgenic mice expressing human DR4 (DRB1*0401) and human CD4, but lacking endogenous MHC class II, we show that posttranslational glycosylation of type II collagen (CII) influences the level of T cell tolerance to this candidate cartilage-specific autoantigen. In such mice, the expression of human CII resulted in a tolerized murine T cell response to human CII. However, tolerance induction remained incomplete, preferentially deleting responses to the nonmodified CII 263-270 epitope, whereas T cell recognition of a glycosylated variant of this epitope was affected to a lesser degree. A similar dominance of T cell responses to CII-glycopeptides was recorded in a cohort of severely affected RA-patients (n = 14). Thus, RA T cells predominantly recognize the immunodominant CII peptide in its glycosylated form and may explain why previously it has been difficult to detect T cell responses to CII in RA patients.
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