Rheumatoid arthritis sera antibodies to citrullinated collagen type II bind to joint cartilage (original) (raw)
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Arthritis Res Ther , 2014
INTRODUCTION: Antibodies towards type II collagen (CII) are detected in patients with rheumatoid arthritis (RA) and in non-human primates and rodents with collagen induced arthritis (CIA). We have previously shown that antibodies specific for several CII-epitopes are pathogenic using monoclonal antibodies from arthritic mice, although the role of different anti-CII epitopes has not been investigated in detail in other species. We therefore performed an inter-species comparative study of the autoantibody response to CII in patients with RA versus monkeys and mice with CIA. METHODS: Analysis of the full epitope repertoire along the disease course of CIA was performed using a library of CII triple-helical peptides. The antibody responses to the major CII epitopes were analyzed in sera and synovial fluid from RA patients, and in sera from rhesus monkeys (Macaca mulatta), common marmosets (Callithrix jacchus) and mice. RESULTS: Many CII epitopes including the major C1, U1, and J1 were associated with established CIA and arginine residues played an important role in the anti-CII antibody interactions. The major epitopes were also recognized in RA patients, both in sera and even more pronounced in synovial fluid: 77% of the patients had antibodies to the U1 epitope. The anti-CII immune response was not restricted to the anti-citrulline protein antibodies (ACPA) positive RA group. CONCLUSION: CII conformational dependent antibody responses are common in RA and are likely to originate from rheumatoid joints but did not show a correlation with ACPA response. Importantly, the fine specificity of the anti-CII response is similar with CIA in monkeys and rodents where the recognized epitopes are conserved and have a major pathogenic role. Thus, anti-CII antibodies may both contribute to, as well as be the consequence of, local joint inflammation.
Anti-citrullinated collagen type I antibody is a target of autoimmunity in rheumatoid arthritis
Biochemical and Biophysical Research Communications, 2005
Rheumatoid arthritis (RA) is one of the most common autoimmune diseases, but its autoimmune mechanisms are not clearly understood. Recently, anti-citrullinated peptide antibodies have been specifically observed in sera of RA patients. Furthermore, we identified RA-susceptible variant in a gene encoding citrullinating enzyme, peptidylarginine deiminase type 4 (PADI4). Therefore, we hypothesized that proteins which are modified in RA synovium by PADI4 act as autoantigens. Subsequently, we obtained human collagen type I (huCI) as one of the autoantigens using a RA synoviocyte cDNA library by immunoscreening. We also investigated that the levels of anti-citrullinated huCI were significantly higher in RA patient sera than in normal control sera with high specificity (99%) and positively correlated with the levels of anti-cyclic citrullinated peptide (anti-CCP) antibodies. We concluded that huCI is a novel substrate protein of PADIs and that citrullinated huCI is a candidate autoantigen of RA.
The Journal of Rheumatology, 2010
Objective.To investigate the relationship between markers of collagen II synthesis and degradation with disease activity measures, autoantibodies, and radiographic outcomes in a 4-year protocol on patients with early rheumatoid arthritis (RA) who are naïve to disease-modifying antirheumatic drugs.Methods.One hundred sixty patients with newly diagnosed, untreated RA entered the Cyclosporine, Methotrexate, Steroid in RA (CIMESTRA) trial. Disease activity and radiograph status were measured at baseline and 4 years. The N-terminal propeptide of collagen IIA (PIIANP) and the cross-linked C-telopeptide of collagen II (CTX-II) were quantified at baseline by ELISA. PIIANP was also assayed at 2 and 4 years. Anticyclic citrullinated peptide (anti-CCP) was recorded at baseline. An uncoupling index for cartilage collagen metabolism was calculated from PIIANP and CTX-II measurements.Results.PIIANP was low at diagnosis and 4 years on (p < 0.001), irrespective of treatment and disease activity....
Arthritis Res Ther , 2014
INTRODUCTION: A major subset of patients with rheumatoid arthritis (RA) is characterised by the presence of circulating autoantibodies directed to citrullinated proteins/peptides (ACPA). These autoantibodies, which are commonly detected using an ELISA assay based on synthetic cyclic citrullinated peptides (CCP), predict clinical onset and a destructive disease course. In the present study, we have utilised plasma and synovial fluids from patients with RA, for the affinity purification and characterisation of anti-CCP2 reactive antibodies, with an aim to generate molecular tools that can be utilized in vitro and in vivo for future investigations into the pathobiology of the ACPA response. Specifically, this study aims to demonstrate that the surrogate marker CCP2 can capture ACPA that bind to autoantigens expressed in vivo, in the major inflammatory lesions of RA, i.e. in the rheumatoid joint. METHODS: Plasma (n = 16) and synovial fluid (n = 26) samples were collected from RA patients with anti-CCP2 IgG levels above 300 AU/ml. Total IgG was isolated on Protein G columns, and subsequently applied to CCP2 affinity columns. Purified anti-CCP2 IgG was analysed for reactivity and specificity using the CCPlus(R) ELISA assay, in-house peptide-ELISAs, western blot and immunohisto-/immunocytochemistry. RESULTS: Approximately 2% of the total IgG pool in both plasma and synovial fluid was CCP2-reactive. Purified anti-CCP2 reactive antibodies from different patients showed differences in binding to CCP2 and differences in binding to citrullinated peptides from alpha-enolase, vimentin, fibrinogen, and collagen type II, illustrating different ACPA fine-specificity profiles. Furthermore, the purified ACPA bound not only in vitro citrullinated proteins but more importantly, in vivo-generated epitopes on synovial fluid cells and synovial tissues from RA patients. CONCLUSIONS: We have isolated ACPA from plasma and synovial fluid, and demonstrated that the CCP2 peptides, frequently used in diagnostic ELISA assays, de facto act as surrogate antigens for at least four different, well-characterised, largely non cross-reactive, ACPA fine-specificities. Moreover, we have determined the concentration and proportion of CCP2-reactive IgG molecules in rheumatoid plasma and synovial fluid, and we have shown that the purified ACPA can be used to detect both in vitro- and in vivo-generated citrullinated epitopes by various techniques. We anticipate that these antibodies will provide us with new opportunities to investigate the potential pathogenic effects of human ACPAs.
Antibodies against citrullinated proteins enhance tissue injury in experimental autoimmune arthritis
The Journal of clinical investigation, 2006
Antibodies against citrullinated proteins are specific and predictive markers for rheumatoid arthritis although the pathologic relevance of these antibodies remains unclear. To investigate the significance of these autoantibodies, collagen-induced arthritis (CIA) in mice was used to establish an animal model of antibody reactivity to citrullinated proteins. DBA/1J mice were immunized with bovine type II collagen (CII) at days 0 and 21, and serum was collected every 7 days for analysis. Antibodies against both CII and cyclic citrullinated peptide, one such citrullinated antigen, appeared early after immunization, before joint swelling was observed. Further, these antibodies demonstrated specific binding to citrullinated filaggrin in rat esophagus by indirect immunofluorescence and citrullinated fibrinogen by Western blot. To evaluate the role of immune responses to citrullinated proteins in CIA, mice were tolerized with a citrulline-containing peptide, followed by antigen challenge w...
Autoantibodies Binding Citrullinated Type I and II Collagens in Rheumatoid Arthritis
2006
Rheumatoid arthritis (RA) is a systemic autoimmune disease with symmetrical articular manifestations. The etiology of the disease is unknown. The prevalence of RA is approximately 0.5-1.0% in adults. In Finland, the annual incidence is 39/100 000. RA is about three times more common in females than in males. Most commonly the disease affects first the joints of feet and fingers. Chronic inflammation leads to erosions of cartilage, bone and tendons and may destroy the whole joint. The diagnosis of RA is mainly based on the clinical features of the disease. The American College of Rheumatology (ACR) 1987 revised classification criteria of RA have commonly been used for diagnosis. No specific diagnostic test is available. Rheumatoid factor (RF) has traditionally been used in the diagnosis, but only 70 to 80% of RA patients have RF in their serum. Other antibodies found in RA are the antiperinuclear factor (APF), the anti-keratin antibody (AKA) and the antibodies to cyclic citrullinated peptide (CCP), which recognize the citrulline-containing antigenic filaggrin protein. Citrulline is an amino acid that is post-translationally formed from arginine by peptidylarginine deiminase enzymes (PADs). Autoantibodies to citrullinated proteins are more specific for RA than RF. There is no filaggrin in joints, which indicates that the autoantibodies reacting with this protein most probably only reflect immunological cross-reaction. It has been postulated that autoimmunity against collagens might be involved in the pathogenesis of RA. There are antibodies binding to collagen in cartilage (type II collagen) and in bone (type I collagen). They have been tested by using collagen preparations rendered soluble by pepsin digestion. This digestion removes the carboxyterminal (C-terminal) telopeptides of collagen. Autoantibodies to the C-telopeptides of type I and II collagens were studied in this doctoral research. Autoantibodies to the citrullinated C-telopeptides of type I and II collagens were found in the serum of patients with RA. ELISA, CLIA and inhibition ELISA were used to detect these autoantibodies. Automatic CLIA gives a more than twofold number of positive findings compared to previous ELISA. Currently the best method for the detection of these autoantibodies is inhibition ELISA. These autoantibodies are specific for citrulline in the peptide sequence. Autoantibodies that bind the normal C-telopeptides of type I and II collagens were not inhibited by soluble normal or citrullinated telopeptides. However, the antibodies that bind only citrullinated telopeptides could be inhibited by corresponding citrullinated telopeptides. Autoantibodies binding the citrullinated telopeptides of type II collagen and anti-CCP predict synergistically the development of seropositive RA.
Role of Citrullinated Collagen in Autoimmune Arthritis
International Journal of Molecular Sciences
Citrullination of proteins plays an important role in protein function and it has recently become clear that citrullinated proteins play a role in immune responses. In this study we examined how citrullinated collagen, an extracellular matrix protein, affects T-cell function during the development of autoimmune arthritis. Using an HLA-DR1 transgenic mouse model of rheumatoid arthritis, mice were treated intraperitoneally with either native type I collagen (CI), citrullinated CI (cit-CI), or phosphate buffered saline (PBS) prior to induction of autoimmune arthritis. While the mice given native CI had significantly less severe arthritis than controls administered PBS, mice receiving cit-CI had no decrease in the severity of autoimmune arthritis. Using Jurkat cells expressing the inhibitory receptor leukocyte-associated immunoglobulin-like receptor-1 (LAIR-1), Western blot analysis indicated that while CI and cit-CI bound to LAIR-1 with similar affinity, only CI induced phosphorylation...