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Abstract
Rheumatoid arthritis (RA) is a systemic autoimmune disease of unknown etiology, characterized by chronic joint inflammation that often leads to joint destruction. Diagnosis of RA is currently based on the revised classification criteria of the American College of Rheumatology (ACR); however, it remains imprecise, especially early in the course of disease. Rheumatoid factor (RF) has been widely used in clinical practice as a useful serological marker for diagnosis of RA. Although RF is the only serological test in the criteria of the ACR, its specificity is limited since RF can be also detected in other rheumatic diseases. Because the current therapeutic strategies in RA employ increasingly aggressive regimens from early stage of the disease, more specific serological markers than RF are desirable. Recently, anti-cyclic citrullinated peptide (anti-CCP) antibodies have attracted attention as a useful marker for the diagnosis of RA with high specificity. In addition to the diagnostic properties, anti-CCP antibodies showed to be a good prognostic marker for joint destructions. In this review, we will explain about the clinical usefulness of anti-CCP antibodies for the daily practice of RA.
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Affiliation(s)
- Toshihiro Matsui
- Department of Rheumatology, Sagamihara National Hospital, National Hospital Organization
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102
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Cantaert T, De Rycke L, Bongartz T, Matteson EL, Tak PP, Nicholas AP, Baeten D. Citrullinated proteins in rheumatoid arthritis: Crucial … but not sufficient! ACTA ACUST UNITED AC 2006; 54:3381-9. [PMID: 17075816 DOI: 10.1002/art.22206] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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103
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Auger I, Sebbag M, Vincent C, Balandraud N, Guis S, Nogueira L, Svensson B, Cantagrel A, Serre G, Roudier J. Influence of HLA-DR genes on the production of rheumatoid arthritis-specific autoantibodies to citrullinated fibrinogen. ACTA ACUST UNITED AC 2005; 52:3424-32. [PMID: 16255019 DOI: 10.1002/art.21391] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVE Antibodies directed against citrullinated fibrinogen are highly specific for rheumatoid arthritis (RA). This study was undertaken to test whether RA-associated HLA-DR alleles are associated with anti-citrullinated fibrinogen in RA patient sera and whether replacement of arginyl by citrullyl residues on fibrinogen peptides modifies their binding to HLA-DR molecules and their recognition by T cells. METHODS Antikeratin, antifilaggrin, and anti-citrullinated fibrinogen antibodies were assayed in RA patients who had undergone HLA-DR typing. Direct assays were performed to investigate binding of citrullinated or native fibrinogen peptides (encompassing the entire alpha- and beta-chains of fibrinogen) to purified HLA-DR molecules. T cell proliferative responses to citrullinated or native fibrinogen peptides were measured in RA patients and controls. RESULTS HLA-DRB1*0404 was associated with anti-citrullinated fibrinogen in RA sera (P = 0.002). For the RA-associated alleles HLA-DRB1*0401 and HLA-DR1, there was a nonsignificant trend toward association (P = 0.07). Multiple peptides from the alpha- and beta-chains of fibrinogen bound many HLA-DR alleles; DRB1*0404 was the best fibrinogen peptide binder. Citrullination did not influence fibrinogen peptide binding to HLA-DR or fibrinogen peptide recognition by T cells. Peripheral blood T cells that recognized native or citrullinated fibrinogen peptides were common in RA patients but not in healthy controls. CONCLUSION The RA-associated HLA-DRB1*0404 allele is also associated with production of antibodies to citrullinated fibrinogen. DRB1*0401 and DRB1*01 tend to be associated with anti-citrullinated fibrinogen, but this is not statistically significant. Citrullination of fibrinogen peptide does not influence peptide-DR-T cell interaction. Finally, T cell proliferation in response to citrullinated or uncitrullinated fibrinogen peptides is frequent in RA patients and very infrequent in controls.
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Affiliation(s)
- Isabelle Auger
- INSERM UMR 639, La Conception Hospital, Faculté de Médecine, 27 Boulevard Jean Moulin, 13005 Marseille, France
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104
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Kinloch A, Tatzer V, Wait R, Peston D, Lundberg K, Donatien P, Moyes D, Taylor PC, Venables PJ. Identification of citrullinated alpha-enolase as a candidate autoantigen in rheumatoid arthritis. Arthritis Res Ther 2005; 7:R1421-9. [PMID: 16277695 PMCID: PMC1297593 DOI: 10.1186/ar1845] [Citation(s) in RCA: 263] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2005] [Revised: 09/08/2005] [Accepted: 09/29/2005] [Indexed: 11/10/2022] Open
Abstract
Antibodies against citrullinated proteins are highly specific for rheumatoid arthritis (RA), but little is understood about their citrullinated target antigens. We have detected a candidate citrullinated protein by immunoblotting lysates of monocytic and granulocytic HL-60 cells treated with peptidylarginine deiminase. In an initial screen of serum samples from four patients with RA and one control, a protein of molecular mass 47 kDa from monocytic HL-60s reacted with sera from the patients, but not with the serum from the control. Only the citrullinated form of the protein was recognised. The antigen was identified by tandem mass spectrometry as alpha-enolase, and the positions of nine citrulline residues in the sequence were determined. Serum samples from 52 patients with RA and 40 healthy controls were tested for presence of antibodies against citrullinated and non-citrullinated alpha-enolase by immunoblotting of the purified antigens. Twenty-four sera from patients with RA (46%) reacted with citrullinated alpha-enolase, of which seven (13%) also recognised the non-citrullinated protein. Six samples from the controls (15%) reacted with both forms. Alpha-enolase was detected in the RA joint, where it co-localised with citrullinated proteins. The presence of antibody together with expression of antigen within the joint implicates citrullinated alpha-enolase as a candidate autoantigen that could drive the chronic inflammatory response in RA.
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Affiliation(s)
- Andrew Kinloch
- Kennedy Institute of Rheumatology, Imperial College London, Charing Cross Hospital Campus, 1 Aspenlea Road, London W6 8LH, UK
| | - Verena Tatzer
- Kennedy Institute of Rheumatology, Imperial College London, Charing Cross Hospital Campus, 1 Aspenlea Road, London W6 8LH, UK
| | - Robin Wait
- Kennedy Institute of Rheumatology, Imperial College London, Charing Cross Hospital Campus, 1 Aspenlea Road, London W6 8LH, UK
| | - David Peston
- Kennedy Institute of Rheumatology, Imperial College London, Charing Cross Hospital Campus, 1 Aspenlea Road, London W6 8LH, UK
| | - Karin Lundberg
- Kennedy Institute of Rheumatology, Imperial College London, Charing Cross Hospital Campus, 1 Aspenlea Road, London W6 8LH, UK
| | - Phillipe Donatien
- Kennedy Institute of Rheumatology, Imperial College London, Charing Cross Hospital Campus, 1 Aspenlea Road, London W6 8LH, UK
| | - David Moyes
- Kennedy Institute of Rheumatology, Imperial College London, Charing Cross Hospital Campus, 1 Aspenlea Road, London W6 8LH, UK
| | - Peter C Taylor
- Kennedy Institute of Rheumatology, Imperial College London, Charing Cross Hospital Campus, 1 Aspenlea Road, London W6 8LH, UK
| | - Patrick J Venables
- Kennedy Institute of Rheumatology, Imperial College London, Charing Cross Hospital Campus, 1 Aspenlea Road, London W6 8LH, UK
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105
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van Gaalen F, Ioan-Facsinay A, Huizinga TWJ, Toes REM. The Devil in the Details: The Emerging Role of Anticitrulline Autoimmunity in Rheumatoid Arthritis. THE JOURNAL OF IMMUNOLOGY 2005; 175:5575-80. [PMID: 16237041 DOI: 10.4049/jimmunol.175.9.5575] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Rheumatoid arthritis is a chronic inflammatory autoimmune disease of unknown cause. The immune response against citrullinated Ags has recently become the prime suspect for disease pathogenesis. Immunity against citrullinated Ags is thought to play a pivotal role in the disease for several reasons: 1) citrullinated Ags are expressed in the target organ, the inflamed joint; 2) anti-citrullinated protein Abs are present before the disease becomes manifest; and 3) these Abs are highly specific for rheumatoid arthritis. In this review, data from clinical, genetic, biochemical, and animal studies is combined to create a profile of this remarkable autoantibody response. Moreover, a model is proposed of how the anti-citrullinated proteins response is generated and how it could eventually lead to chronic inflammation.
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Affiliation(s)
- Floris van Gaalen
- Department of Rheumatology, Leiden University Medical Centre, Leiden, The Netherlands
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106
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De Rycke L, Nicholas AP, Cantaert T, Kruithof E, Echols JD, Vandekerckhove B, Veys EM, De Keyser F, Baeten D. Synovial intracellular citrullinated proteins colocalizing with peptidyl arginine deiminase as pathophysiologically relevant antigenic determinants of rheumatoid arthritis-specific humoral autoimmunity. ACTA ACUST UNITED AC 2005; 52:2323-30. [PMID: 16052592 DOI: 10.1002/art.21220] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE To address the ongoing debate concerning the specificity of synovial citrullinated proteins for rheumatoid arthritis (RA) and to analyze their pathophysiologic relevance to the induction or perpetuation of the RA-specific anti-citrullinated protein antibodies (ACPAs). METHODS Synovium of 19 RA patients and 19 non-RA controls was immunostained for the presence of citrullinated proteins with a mouse monoclonal antibody (F95), for the citrullinating enzyme peptidyl arginine deiminase type 2 (PAD-2), and for the free citrulline-producing enzyme inducible nitric oxide synthase (iNOS). Extending the RA cohort to 61 patients, the findings of anticitrulline staining in synovium were related to serum and synovial fluid ACPA levels, as measured by enzyme-linked immunosorbent assay. RESULTS F95 staining indicated the presence of synovial intracellular citrullinated proteins in 53% of RA samples versus 5% of control samples, whereas extracellular staining was not RA specific. Immunoblotting and inhibition experiments confirmed that the antibody recognized citrullinated proteins but not free citrulline. Accordingly, iNOS was equally found in RA and control synovium and in intracellular citrullinated protein-positive and intracellular citrullinated protein-negative samples. In contrast, intracellular citrullinated proteins colocalized with PAD-2, which was found in 59% of RA samples versus 17% of control samples. Independent of local disease activity, the presence of the RA-specific synovial intracellular citrullinated proteins was associated with significantly higher systemic and local ACPA levels and with local ACPA production in the joint. CONCLUSION These data confirm the presence of RA-specific intracellular citrullinated proteins in synovium. The link with PAD-2 and local and systemic ACPA levels emphasizes their pathophysiologic relevance for RA-specific humoral autoimmunity.
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107
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Suzuki A, Yamada R, Ohtake-Yamanaka M, Okazaki Y, Sawada T, Yamamoto K. Anti-citrullinated collagen type I antibody is a target of autoimmunity in rheumatoid arthritis. Biochem Biophys Res Commun 2005; 333:418-26. [PMID: 15950180 DOI: 10.1016/j.bbrc.2005.05.137] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2005] [Accepted: 05/14/2005] [Indexed: 11/21/2022]
Abstract
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.
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Affiliation(s)
- Akari Suzuki
- Laboratory for Rheumatic Diseases, SNP Research Center, The Institute of Physical and Chemical Research, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
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108
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Chapuy-Regaud S, Sebbag M, Baeten D, Clavel C, Foulquier C, De Keyser F, Serre G. Fibrin deimination in synovial tissue is not specific for rheumatoid arthritis but commonly occurs during synovitides. THE JOURNAL OF IMMUNOLOGY 2005; 174:5057-64. [PMID: 15814737 DOI: 10.4049/jimmunol.174.8.5057] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Autoantibodies to deiminated (citrullinated) proteins are the most specific serological markers of rheumatoid arthritis (RA). Deimination is critical in generating the peptidic epitopes they recognize. In the synovial tissue (ST), deiminated forms of the alpha- and beta-chains of fibrin are their major autoantigenic targets (anti-human fibrin(ogen) autoantibodies (AhFibA)). We investigated whether the presence of deiminated fibrin in the ST was specific for RA, because this could explain why AhFibA are RA specific. In 13 patients with RA and 19 patients with various other rheumatological disorders, knee ST biopsies were collected in macroscopically inflamed areas identified under arthroscopy. Synovitis was histopathologically confirmed in all of the biopsies. By immunoblotting, using antisera to fibrin, Abs to citrullyl residues, and AhFibA purified from RA sera, deiminated fibrin was evidenced in ST extracts from all of the patients. Moreover, variations in the degree of fibrin deimination were observed that were not related to the disease. Immunohistochemical analysis, using Abs to citrullyl residues and an antiserum to fibrin on adjacent serial sections of ST, confirmed the results because deiminated proteins colocalized with fibrin in RA as well as in control patients. Therefore, fibrin deimination in the ST is a general phenomenon associated to any synovitis, which does not necessarily induce a B autoimmune response with production of AhFibA.
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Affiliation(s)
- Sabine Chapuy-Regaud
- Laboratory of Epidermis Differentiation and Rheumatoid Autoimmunity, Unité Mixte de Recherche 5165 Centre National de la Recherche Scientifique-Toulouse III University, Institut Fédératif de Recherche 30, Toulouse, France
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109
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Nijenhuis S, Zendman AJW, Vossenaar ER, Pruijn GJM, vanVenrooij WJ. Autoantibodies to citrullinated proteins in rheumatoid arthritis: clinical performance and biochemical aspects of an RA-specific marker. Clin Chim Acta 2005; 350:17-34. [PMID: 15530456 DOI: 10.1016/j.cccn.2004.07.016] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2004] [Revised: 06/30/2004] [Accepted: 07/15/2004] [Indexed: 12/01/2022]
Abstract
Rheumatoid arthritis (RA) is a common, systemic autoimmune disease of which the exact etiology is not known. In the past 10 years, substantial progress has been made in the identification of the antigens specifically recognized by the autoantibodies of RA patients. A central factor in this respect is citrullination, a form of post-translational modification that is strongly associated with autoimmunity in RA. Here, we summarize and discuss our current knowledge on (i) autoantibody systems in RA, (ii) the occurrence of peptidylarginine deiminases and (iii) citrullinated proteins in natural and diseased environments, and (iv) genetic factors involved in RA that may influence the generation and presentation of citrullinated proteins and the resulting antibody production against these modified proteins. Citrullination of proteins may play a key role in the initiation and/or the progression of RA. The onset of citrulline-specific autoimmunity in RA is probably mediated by both environmental and genetic factors, and future studies will learn whether therapeutic intervention at the level of citrullination may provide new possibilities to treat RA.
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Affiliation(s)
- Suzanne Nijenhuis
- Department of Biochemistry 161, Radboud University Nijmegen, PO Box 9101, NL-6500 HB Nijmegen, The Netherlands
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110
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Chapuy-Regaud S, Nogueira L, Clavel C, Sebbag M, Vincent C, Serre G. IgG subclass distribution of the rheumatoid arthritis-specific autoantibodies to citrullinated fibrin. Clin Exp Immunol 2005; 139:542-50. [PMID: 15730401 PMCID: PMC1809305 DOI: 10.1111/j.1365-2249.2004.02708.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
In the rheumatoid synovium, deiminated ('citrullinated') forms of fibrin are the major targets of IgG autoantibodies to citrullinated proteins (ACPA), the most specific serological markers of rheumatoid arthritis (RA). To further the characterization of ACPA, we determined their subclass distribution. From a previously validated highly sensitive and specific enzyme-linked immunosorbent assay (ELISA) onto in vitro deiminated human fibrinogen - antihuman fibrin(ogen) autoantibodies (AhFibA)-ELISA - we derived and calibrated four ELISAs, using monoclonal antibodies to each of the four IgG subclasses, to determine the proportions of AhFibA subclasses in the sera. A series of 186 serum samples from RA patients was analysed. All AhFibA-positive sera contained IgG1-AhFibA, which reached the highest titres and accounted for more than 80% of AhFibA in three-quarters of the sera. One or two other subclasses were associated with IgG1 in 39% of the sera, IgG4-AhFibA being observed much more frequently and at higher titres than IgG3- or IgG2-AhFibA. IgG1 alone or IgG(1 + 4)-AhFibA were the AhFibA subclass profiles found in more than 80% of patients. AhFibA are mainly IgG1 and, to a lesser extent, IgG4. Such IgG subclass profiles may influence the effector phases of the immunological conflict between ACPA and deiminated fibrin that takes place specifically in the rheumatoid synovium and therefore may play a critical role in the self-maintenance of rheumatoid inflammation.
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Affiliation(s)
- S Chapuy-Regaud
- Laboratory of 'Epidermis Differentiation and Rheumatoid Autoimmunity', UMR 5165 CNRS-Toulouse III University, Toulouse, France
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111
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Lundberg K, Nijenhuis S, Vossenaar ER, Palmblad K, van Venrooij WJ, Klareskog L, Zendman AJW, Harris HE. Citrullinated proteins have increased immunogenicity and arthritogenicity and their presence in arthritic joints correlates with disease severity. Arthritis Res Ther 2005; 7:R458-67. [PMID: 15899032 PMCID: PMC1174941 DOI: 10.1186/ar1697] [Citation(s) in RCA: 194] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2004] [Revised: 12/16/2004] [Accepted: 01/20/2005] [Indexed: 01/14/2023] Open
Abstract
Autoantibodies directed against citrulline-containing proteins have an impressive specificity of nearly 100% in patients with rheumatoid arthritis and have been suggested to be involved in the disease pathogenesis. The targeted epitopes are generated by a post-translational modification catalysed by the calcium-dependent enzyme peptidyl arginine deiminase (PAD), which converts positively charged arginine to polar but uncharged citrulline. The aim of this study was to explore the effects of citrullination on the immunogenicity of autoantigens as well as on potential arthritogenicity. Thus, immune responses to citrullinated rat serum albumin (Cit-RSA) and to unmodified rat serum albumin (RSA) were examined as well as arthritis development induced by immunisation with citrullinated rat collagen type II (Cit-CII) or unmodified CII. In addition, to correlate the presence of citrullinated proteins and the enzyme PAD4 with different stages of arthritis, synovial tissues obtained at different time points from rats with collagen-induced arthritis were examined immunohistochemically. Our results demonstrate that citrullination of the endogenous antigen RSA broke immunological tolerance, as was evident by the generation of antibodies directed against the modified protein and cross-reacting with the native protein. Furthermore we could demonstrate that Cit-CII induced arthritis with higher incidence and earlier onset than did the native counterpart. Finally, this study reveals that clinical signs of arthritis precede the presence of citrullinated proteins and the enzyme PAD4. As disease progressed into a more severe and chronic state, products of citrullination appeared specifically in the joints. Citrullinated proteins were detected mainly in extracellular deposits but could also be found in infiltrating cells and on the cartilage surface. PAD4 was detected in the cytoplasm of infiltrating mononuclear cells, from day 21 after immunisation and onwards. In conclusion, our data reveal the potency of citrullination to break tolerance against the self antigen RSA and to increase the arthritogenic properties of the cartilage antigen CII. We also show that citrullinated proteins and the enzyme PAD4 are not detectable in healthy joints, and that the appearance and amounts in arthritic joints of experimental animals are correlated with the severity of inflammation.
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Affiliation(s)
- Karin Lundberg
- Rheumatology Unit, Department of Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Suzanne Nijenhuis
- Department of Biochemistry, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Erik R Vossenaar
- Department of Biochemistry, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Karin Palmblad
- Rheumatology Unit, Department of Medicine, Karolinska Institutet, Stockholm, Sweden
| | | | - Lars Klareskog
- Rheumatology Unit, Department of Medicine, Karolinska Institutet, Stockholm, Sweden
| | - AJW Zendman
- Department of Biochemistry, Radboud University Nijmegen, Nijmegen, The Netherlands
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112
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Nielen MMJ, van der Horst AR, van Schaardenburg D, van der Horst-Bruinsma IE, van de Stadt RJ, Aarden L, Dijkmans BAC, Hamann D. Antibodies to citrullinated human fibrinogen (ACF) have diagnostic and prognostic value in early arthritis. Ann Rheum Dis 2005; 64:1199-204. [PMID: 15640269 PMCID: PMC1755615 DOI: 10.1136/ard.2004.029389] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND The anti-cyclic citrullinated peptide (CCP) test has a high sensitivity and specificity for rheumatoid arthritis, although CCP is not the physiological target of the autoantibodies. Citrullinated fibrin is abundant in inflamed synovium OBJECTIVE To assess the diagnostic and prognostic value of antibodies against citrullinated fibrinogen (ACF), a soluble precursor of fibrin, in comparison with IgM-rheumatoid factor (IgM-RF) and the second generation anti-CCP test. METHODS In 379 patients with early arthritis (258 rheumatoid and 121 undifferentiated), the sensitivity, specificity, and positive predictive value of ACF, anti-CCP, and IgM-RF for diagnosing rheumatoid arthritis were calculated. Multivariate logistic regression analysis was used to assess the diagnostic and prognostic value (radiographic progression after two years) of the tests. RESULTS The sensitivities of the ACF, anti-CCP, and IgM-RF tests were 55.8%, 57.8%, and 44.6%, with specificities of 92.6%, 94.2%, and 96.7%, respectively. Approximately 30% of the IgM-RF negative patients were positive for ACF or anti-CCP or both. The ACF and anti-CCP test had a high agreement in early arthritis (kappa = 0.84). Of all baseline characteristics, the ACF test and the anti-CCP test were the best predictors for diagnosing rheumatoid arthritis at one year (odds ratio (OR) = 10.3 and 10.6, respectively) and for radiographic progression after two years (OR = 12.1 and 14.8). CONCLUSIONS ACF is as sensitive as anti-CCP and more sensitive than IgM-RF in diagnosing rheumatoid arthritis in early arthritis. The ACF test is also a good predictor of radiographic progression, with a performance similar to the anti-CCP test. The ACF test and the anti-CCP test are especially valuable in IgM-RF negative arthritis.
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Affiliation(s)
- M M J Nielen
- Jan van Breemen Institute, Amsterdam, Netherlands
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113
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Sebbag M, Chapuy-Regaud S, Auger I, Petit-Texeira E, Clavel C, Nogueira L, Vincent C, Cornélis F, Roudier J, Serre G. Clinical and pathophysiological significance of the autoimmune response to citrullinated proteins in rheumatoid arthritis. Joint Bone Spine 2004; 71:493-502. [PMID: 15589429 DOI: 10.1016/j.jbspin.2004.07.004] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2004] [Accepted: 07/12/2004] [Indexed: 11/16/2022]
Abstract
Rheumatoid arthritis (RA) is the most frequent human autoimmune disease, affecting about 1% of the adult population worldwide. A better knowledge of the autoimmune mechanisms involved is essential. We identified the epithelial targets of various autoantibodies specifically associated to RA, as variants of (pro)filaggrin. We also showed that these targets correspond to deiminated ("citrullinated") proteins, of which arginyl residues have been posttranslationally transformed into citrullyl residues by a peptidylarginine deiminase (PAD). Moreover, we and others established that citrullyl residues are indispensable elements of the epitopes recognized by these autoantibodies but only in the context of specific aminoacid sequences. We also demonstrated that these autoantibodies to citrullinated proteins (ACPA) are secreted by plasma cells of the synovial tissue and that their major targets correspond to citrullinated forms of the alpha- and beta-chains of fibrin, abundant in the tissue. These results have allowed the development of new efficient immunochemical methods for the detection of ACPA. Some of them are already commercially available. These new methods have permitted the high diagnostic value of ACPA which are present very early in the course of the disease, and also their prognostic value, to be confirmed. ACPA detection should therefore prove to be also a very valuable tool to guide the choice of therapeutic strategies, from the earliest stages of the disease. The synthesis of ACPA in the rheumatoid synovial tissue and the existence therein of a specific antigenic target constitute a strong argument for the involvement of this specific immunological conflict in the pathophysiology of RA. Indeed, it could lead to activation of effector mechanisms with pro-inflammatory effects, thus to formation in the tissue of new fibrin deposits, secondarily citrullinated. We therefore, propose a new pathophysiological model accounting for the self-maintenance and chronicity of rheumatoid inflammation. Numerous questions about the pathophysiological significance of the autoimmune response to deiminated proteins in RA remain to be answered to confirm this model.
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Affiliation(s)
- Mireille Sebbag
- Faculté de Médecine, Purpan-IFR30, Unité Différenciation Epidermique et Auto-immunité Rhumatoïde, UMR 5165 CNRS-Toulouse III Université, (CNRS-Inserm-Université Paul Sabatier-CHU de Toulouse), Place du Docteur Baylac, 31059 Toulouse, France
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114
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Vossenaar ER, Smeets TJM, Kraan MC, Raats JM, van Venrooij WJ, Tak PP. The presence of citrullinated proteins is not specific for rheumatoid synovial tissue. ACTA ACUST UNITED AC 2004; 50:3485-94. [PMID: 15529392 DOI: 10.1002/art.20584] [Citation(s) in RCA: 195] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Antibodies directed toward citrullinated proteins (e.g., anti-cyclic citrullinated peptide antibodies) are highly specific for rheumatoid arthritis (RA) and are produced locally at the site of inflammation. Although the presence of citrullinated proteins in rheumatoid synovium has been described in the literature, it is uncertain whether their presence is specific for RA. The present study was undertaken to investigate this. METHODS The local production of the anti-citrullinated protein antibodies was investigated by comparing the concentration of the antibodies (corrected for the total amount of IgG present) in paired samples of serum and synovial fluid from RA patients. The presence of citrullinated proteins in the synovial tissue was investigated by immunohistochemical analysis of synovial tissue from RA patients and from patients with other arthropathies, using a variety of specific antibodies to citrullinated proteins. RESULTS In RA patients, anti-citrullinated protein antibodies constituted a 1.4-fold higher proportion of IgG in synovial fluid compared with serum, which is indicative of a local production of the antibodies. Immunohistochemical staining of citrullinated proteins was observed in the lining layer, the sublining layer, and in extravascular fibrin deposits in inflamed synovial tissue from RA as well as non-RA patients. CONCLUSION The presence of citrullinated proteins in the inflamed synovium is not specific for RA, but rather, it may be an inflammation-associated phenomenon. The high specificity of the anti-citrullinated protein antibodies is, therefore, most likely the result of an abnormal humoral response to these proteins.
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Affiliation(s)
- Erik R Vossenaar
- Department of Biochemistry 161, Radboud University Nijmegen, NL-6500 HB Nijmegen, The Netherlands.
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115
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Caponi L, Petit-Teixeira E, Sebbag M, Bongiorni F, Moscato S, Pratesi F, Pierlot C, Osorio J, Chapuy-Regaud S, Guerrin M, Cornelis F, Serre G, Migliorini P. A family based study shows no association between rheumatoid arthritis and the PADI4 gene in a white French population. Ann Rheum Dis 2004; 64:587-93. [PMID: 15485997 PMCID: PMC1755438 DOI: 10.1136/ard.2004.026831] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Autoantibodies to citrullinated proteins (ACPA) are considered a specific marker for rheumatoid arthritis. Peptidylarginine deiminase (PAD) is the enzyme that converts arginyl into citrullyl residues; different isoforms of the enzyme are expressed in mammals. It has been suggested that the PADI4 gene may contribute to genetic susceptibility to rheumatoid arthritis, but conflicting results have been obtained in different populations. OBJECTIVE To test the hypothesis that the PADI4 gene may confer susceptibility to rheumatoid arthritis in a white French population, using powerful and highly reliable family based association tests. METHODS DNA samples were analysed from 100 families where one member was affected by rheumatoid arthritis and both parents were available for sampling. Five single nucleotide polymorphisms, located within the PADI4 gene and in its close proximity, were genotyped by restriction fragment length polymorphism, and haplotypes were constructed. The analysis involved use of the transmission disequilibrium test and genotype relative risk. ACPA were detected by ELISA on cyclic citrullinated peptides and on human deiminated fibrinogen. RESULTS No single SNP or haplotype was associated with the disease, or was preferentially transmitted. No association was found when patients were partitioned according to ACPA positivity. CONCLUSIONS No PADI4 haplotype is associated with rheumatoid arthritis in a white French population. The role of genes encoding the other PAD isoforms, or modulating tissue expression or enzyme activity, remains to be elucidated.
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Affiliation(s)
- L Caponi
- Department of Experimental Pathology, University of Pisa, via Roma 67, I-56126 Pisa, Italy
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116
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van Gaalen FA, van Aken J, Huizinga TWJ, Schreuder GMT, Breedveld FC, Zanelli E, van Venrooij WJ, Verweij CL, Toes REM, de Vries RRP. Association between HLA class II genes and autoantibodies to cyclic citrullinated peptides (CCPs) influences the severity of rheumatoid arthritis. ACTA ACUST UNITED AC 2004; 50:2113-21. [PMID: 15248208 DOI: 10.1002/art.20316] [Citation(s) in RCA: 275] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE The functional role of HLA class II molecules in the pathogenesis of rheumatoid arthritis (RA) is unclear. HLA class II molecules are involved in the interaction between T and B lymphocytes required for long-lived B cell responses and generation of high-affinity IgG antibodies. We undertook this study to investigate the relationship between HLA class II gene polymorphisms and RA-specific IgG antibodies against cyclic citrullinated peptides (anti-CCP antibodies). METHODS High-resolution HLA-DR and DQ typing and anti-CCP-2 antibody testing were performed on 268 RA patients from the Early Arthritis Clinic cohort at the Department of Rheumatology of the Leiden University Medical Center. The presence of anti-CCP antibodies was analyzed in carriers of the different DR and DQ alleles. Disease progression was measured over a period of 4 years by scoring radiographs of the hands and feet using the Sharp/van der Heijde method. RESULTS Carriership of the individual alleles HLA-DRB1*0401, DRB1*1001, DQB1*0302, and DQB1*0501 was associated with the presence of anti-CCP antibodies. Carriers of DQ-DR genotypes containing proposed RA susceptibility alleles were significantly more often anti-CCP antibody positive. Carriership of one or two HLA-DRB1 shared epitope (SE) alleles was significantly associated with production of anti-CCP antibodies (odds ratio [OR] 3.3, 95% confidence interval [95% CI] 1.8-6.0 and OR 13.3, 95% CI 4.6-40.4, respectively). An increased rate of joint destruction was observed in SE+, anti-CCP+ patients (mean Sharp score 7.6 points per year) compared with that in SE-, anti-CCP+ patients (2.4 points per year) (P = 0.04), SE+, anti-CCP- patients (1.6 points per year) (P < 0.001), and SE-, anti-CCP- patients (1.6 points per year) (P < 0.001). CONCLUSION HLA class II RA susceptibility alleles are associated with production of anti-CCP antibodies. Moreover, more severe disease progression is found in RA patients with both anti-CCP antibodies and SE alleles.
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117
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Meyer O. Is the celiac disease model relevant to rheumatoid arthritis? Joint Bone Spine 2004; 71:4-6. [PMID: 14769512 DOI: 10.1016/j.jbspin.2003.10.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2003] [Accepted: 10/09/2003] [Indexed: 02/07/2023]
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118
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119
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Vossenaar ER, Radstake TRD, van der Heijden A, van Mansum MAM, Dieteren C, de Rooij DJ, Barrera P, Zendman AJW, van Venrooij WJ. Expression and activity of citrullinating peptidylarginine deiminase enzymes in monocytes and macrophages. Ann Rheum Dis 2004; 63:373-81. [PMID: 15020330 PMCID: PMC1754951 DOI: 10.1136/ard.2003.012211] [Citation(s) in RCA: 322] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND Antibodies directed to proteins containing the non-standard amino acid citrulline, are extremely specific for rheumatoid arthritis (RA). Peptidylcitrulline can be generated by post-translational conversion of arginine residues. This process, citrullination, is catalysed by a group of calcium dependent peptidylarginine deiminase (PAD) enzymes. OBJECTIVE To investigate the expression and activity of four isotypes of PAD in peripheral blood and synovial fluid cells of patients with RA. RESULTS The data presented here show that citrullination of proteins by PAD enzymes is a process regulated at three levels: transcription-in peripheral blood PAD2 and PAD4 mRNAs are expressed predominantly in monocytes; PAD4 mRNA is not detectable in macrophages, translation-translation of PAD2 mRNA is subject to differentiation stage-specific regulation by its 3' UTR, and activation-the PAD proteins are only activated when sufficient Ca(2+) is available. Such high Ca(2+) concentrations are normally not present in living cells. In macrophages, which are abundant in the inflamed RA synovium, vimentin is specifically citrullinated after Ca(2+) influx. CONCLUSION PAD2 and PAD4 are the most likely candidate PAD isotypes for the citrullination of synovial proteins in RA. Our results indicate that citrullinated vimentin is a candidate autoantigen in RA.
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Affiliation(s)
- E R Vossenaar
- Department of Biochemistry, University of Nijmegen, Nijmegen, The Netherlands.
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120
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Vossenaar ER, van Venrooij WJ. Citrullinated proteins: sparks that may ignite the fire in rheumatoid arthritis. Arthritis Res Ther 2004; 6:107-11. [PMID: 15142259 PMCID: PMC416453 DOI: 10.1186/ar1184] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2004] [Revised: 04/05/2004] [Accepted: 04/05/2004] [Indexed: 11/25/2022] Open
Abstract
Antibodies directed to citrullinated proteins (e.g. anti-CCP [cyclic citrullinated peptide] antibodies) are highly specific for rheumatoid arthritis (RA). These antibodies are produced at the site of inflammation in RA, and therefore citrullinated antigens are also expected to be present in the inflamed synovium. We discuss literature showing that the presence of citrullinated proteins in the synovium is not specific for RA. The RA-specific antibodies are therefore most likely the result of an abnormal immune response that specifically occurs in RA patients. It was recently shown that presence of anti-CCP antibodies precedes the onset of clinical symptoms of RA by years. It thus appears that it may take years for initial events that cause the generation of anti-CCP antibodies to develop into full-blown disease.
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Affiliation(s)
- Erik R Vossenaar
- Department of Biochemistry, University of Nijmegen, Nijmegen, The Netherlands.
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121
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van Gaalen FA, Linn-Rasker SP, van Venrooij WJ, de Jong BA, Breedveld FC, Verweij CL, Toes REM, Huizinga TWJ. Autoantibodies to cyclic citrullinated peptides predict progression to rheumatoid arthritis in patients with undifferentiated arthritis: a prospective cohort study. ACTA ACUST UNITED AC 2004; 50:709-15. [PMID: 15022309 DOI: 10.1002/art.20044] [Citation(s) in RCA: 405] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
OBJECTIVE Rheumatoid arthritis (RA) is a common, severe, chronic inflammatory joint disease. Since the disease may initially be indistinguishable from other forms of arthritis, early diagnosis can be difficult. Autoantibodies seen in RA can be detected years before clinical symptoms develop. In an inception cohort of patients with recent-onset arthritis, we undertook this study to assess the predictive value of RA-specific autoantibodies to cyclic citrullinated peptides (CCPs) in patients with undifferentiated arthritis (UA). METHODS Anti-CCP2 antibody tests were performed at baseline in 936 consecutive, newly referred patients with recent-onset arthritis. Patients who could not be properly classified 2 weeks after inclusion were categorized as having UA. Patients with UA were followed up for 3 years and evaluated for progression of their disease to RA as defined by the American College of Rheumatology (ACR) 1987 revised criteria. RESULTS Three hundred eighteen of 936 patients with recent-onset arthritis were classified as having UA and were available for analysis. After 3 years of followup, 127 of 318 UA patients (40%) had been classified as having RA. RA had developed in 63 of 249 patients (25%) with a negative anti-CCP test and in 64 of 69 patients (93%) with a positive anti-CCP test (odds ratio 37.8 [95% confidence interval 13.8-111.9]). Multivariate analysis of the presence of anti-CCP antibodies and parameters from the ACR criteria identified polyarthritis, symmetric arthritis, erosions on radiographs, and anti-CCP antibodies as significant predictors of RA. CONCLUSION Testing for anti-CCP antibodies in UA allows accurate prediction of a substantial number of patients who will fulfill the ACR criteria for RA.
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Affiliation(s)
- F A van Gaalen
- Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands.
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122
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Vossenaar ER, Zendman AJW, van Venrooij WJ, Pruijn GJM. PAD, a growing family of citrullinating enzymes: genes, features and involvement in disease. Bioessays 2004; 25:1106-18. [PMID: 14579251 DOI: 10.1002/bies.10357] [Citation(s) in RCA: 705] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Peptidylarginine deiminase (PAD, EC 3.5.3.15) enzymes catalyze the conversion of protein-bound arginine to citrulline. This post-translational modification may have a big impact on the structure and function of the target protein. In this review, we will discuss the effects of citrullination and its involvement in several human diseases, including rheumatoid arthritis and multiple sclerosis. So far, four isotypes of PAD have been described in mammals. We describe the existence of PAD in non-mammalian vertebrates and the existence of a fifth mammalian PAD. In addition, tissue-specific expression, genomic organization and evolutionary conservation of the different PAD isotypes will be discussed in detail. This article contains supplementary material which may be viewed at the BioEssays website at http://www.interscience.wiley.com/jpages/0265-9247/suppmat/2003/25/v25.1106.html.
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Affiliation(s)
- Erik R Vossenaar
- Department of Biochemistry, University of Nijmegen, Nijmegen, The Netherlands.
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123
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El-Gabalawy HS, Wilkins JA. Anti-Sa antibodies: prognostic and pathogenetic significance to rheumatoid arthritis. Arthritis Res Ther 2004; 6:86-9. [PMID: 15059270 PMCID: PMC400444 DOI: 10.1186/ar1171] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2004] [Accepted: 03/05/2004] [Indexed: 11/10/2022] Open
Abstract
Anti-Sa antibodies are detected in the serum of 20-47% of patients with rheumatoid arthritis. These antibodies have a high degree of specificity for the disease, and appear to identify a subset of early rheumatoid arthritis patients destined to have aggressive and destructive disease. It has recently been confirmed that anti-Sa antibodies are directed to citrullinated vimentin, thus placing them in the anti-citrulline family of autoantibodies. The Sa antigen has previously been shown to be present in synovium. This, along with the demonstration of citrullinated proteins in rheumatoid synovium, suggests that anti-Sa antibodies may play a pathogenetic role in the initiation and/or persistence of rheumatoid synovitis.
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Affiliation(s)
- Hani S El-Gabalawy
- Rheumatic Disease Research Laboratory, University of Manitoba, Winnipeg, Manitoba, Canada.
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124
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Vossenaar ER, Zendman AJW, Van Venrooij WJ. Citrullination, a possible functional link between susceptibility genes and rheumatoid arthritis. Arthritis Res Ther 2003; 6:1-5. [PMID: 14979924 PMCID: PMC400418 DOI: 10.1186/ar1027] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2003] [Accepted: 10/23/2003] [Indexed: 01/26/2023] Open
Abstract
Antibodies directed to citrullinated proteins (anti-cyclic citrullinated peptide) are highly specific for rheumatoid arthritis (RA). Recent data suggest that the antibodies may be involved in the disease process of RA and that several RA-associated genetic factors might be functionally linked to RA via modulation of the production of anti-cyclic citrullinated peptide antibodies or citrullinated antigens.
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Affiliation(s)
- Erik R Vossenaar
- Department of Biochemistry, University of Nijmegen, The Netherlands.
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125
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Ruiz-Alegría C, López-Hoyos M. [Autoantibodies in the diagnosis of rheumatoid arthritis. Utility of anti-cyclic citrullinated peptides]. Med Clin (Barc) 2003; 121:619-24. [PMID: 14636538 DOI: 10.1016/s0025-7753(03)74035-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Rheumatoid arthritis (RA) is one of the commonest inflammatory joint diseases, affecting about 1% of population. Despite its high prevalence, many aspects of its etiopathogeny remain unclarified. Recently, some important findings related to RA pathogenesis with a number of consequences on the treatment and prognosis of this aggressive disease have been reported. It is important to diagnose and to treat the disease early to avoid long-term damage. However, the search for a specific and sensitive serological test to early identify RA patients has yielded poor results. Autoantibodies are found in the sera of RA patients with a variable prevalence and have been classified into RA-specific and RA-unspecific antibodies. It has been recently demonstrated that many of those RA-specific autoantibodies recognize peptides that contain citrulline residues and, thus, a new test to measure the presence of anti-cyclic citrullinated peptides (CCP) antibodies has been developed. Research publications about the utility of anti-CCP antibodies not only in the diagnosis, but also in the prognosis, of RA are increasing exponentially. In fact, the value of the measurement of anti-CCP antibodies is already widely recognized. This review summarizes the most important data about the autoantibodies employed to date in the diagnosis of RA, including anti-CCP antibodies.
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Affiliation(s)
- Carlos Ruiz-Alegría
- Servicio de Inmunología. Hospital Universitario Marqués de Valdecilla. Santander. España
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126
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Moen K, Brun JG, Madland TM, Tynning T, Jonsson R. Immunoglobulin G and A antibody responses to Bacteroides forsythus and Prevotella intermedia in sera and synovial fluids of arthritis patients. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 2003; 10:1043-50. [PMID: 14607865 PMCID: PMC262434 DOI: 10.1128/cdli.10.6.1043-1050.2003] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2003] [Revised: 06/09/2003] [Accepted: 08/08/2003] [Indexed: 11/20/2022]
Abstract
The objective of the present study was to investigate immunoglobulin G (IgG) and IgA antibody immune responses to Porphyromonas gingivalis, Prevotella intermedia, Bacteroides forsythus, and Candida albicans in the sera of patients with rheumatoid arthritis (RA), the synovial fluid (SF) of patients with RA (RA-SF samples), and the SF of patients without RA (non-RA-SF samples). An enzyme-linked immunosorbent assay was used to determine IgG and IgA antibody levels in 116 serum samples from patients with RA, 52 RA-SF samples, and 43 non-RA-SF samples; and these were compared with those in SF samples from 9 patients with osteoarthritis (OA-SF samples) and the blood from 100 donors (the control [CTR] group). Higher levels of IgG antibodies against B. forsythus (P < 0.0001) and P. intermedia (P < 0.0001) were found in non-RA-SF samples than in OA-SF samples, and higher levels of IgG antibodies against B. forsythus (P = 0.003) and P. intermedia (P = 0.024) were found in RA-SF samples than in OA-SF samples. Significantly higher levels of IgA antibodies against B. forsythus were demonstrated in both RA-SF and non-RA-SF samples than in OA-SF samples. When corrected for total Ig levels, levels of IgG antibody against B. forsythus were elevated in RA-SF and non-RA-SF samples compared to those in OA-SF samples. Lower levels of Ig antibodies against B. forsythus were found in the sera of patients with RA than in the plasma of the CTR group for both IgG (P = 0.003) and IgA (P < 0.0001). When corrected for total Ig levels, the levels of IgG and IgA antibodies against B. forsythus were still found to be lower in the sera from patients with RA than in the plasma of the CTR group (P < 0.0001). The levels of antibodies against P. gingivalis and C. albicans in the sera and SF of RA and non-RA patients were comparable to those found in the respective controls. The levels of IgG and IgA antibodies against B. forsythus were elevated in SF from patients with RA and non-RA-SF samples compared to those in OA-SF samples. Significantly lower levels of IgG and IgA antibodies against B. forsythus were found in the sera of patients with RA than in the plasma of the CTR group. This indicates the presence of an active antibody response in synovial tissue and illustrates a potential connection between periodontal and joint diseases.
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Affiliation(s)
- Ketil Moen
- Broegelmann Research Laboratory, The Gade Institute, University of Bergen, Bergen, Norway.
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127
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Majka DS, Holers VM. Can we accurately predict the development of rheumatoid arthritis in the preclinical phase? ACTA ACUST UNITED AC 2003; 48:2701-5. [PMID: 14558071 DOI: 10.1002/art.11224] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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128
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Vossenaar ER, Nijenhuis S, Helsen MMA, van der Heijden A, Senshu T, van den Berg WB, van Venrooij WJ, Joosten LAB. Citrullination of synovial proteins in murine models of rheumatoid arthritis. ARTHRITIS AND RHEUMATISM 2003; 48:2489-500. [PMID: 13130468 DOI: 10.1002/art.11229] [Citation(s) in RCA: 179] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
OBJECTIVE Antibodies directed to citrulline-containing proteins are highly specific for rheumatoid arthritis (RA) and can be detected in up to 80% of patients with RA. Citrulline is a nonstandard amino acid that can be incorporated into proteins only by posttranslational modification of arginine by peptidylarginine deiminase (PAD) enzymes. The objective of this study was to investigate the presence of anticitrulline antibodies, PAD enzymes, and citrullinated antigens in mouse models of both acute and chronic destructive arthritis: streptococcal cell wall (SCW)-induced arthritis and collagen-induced arthritis (CIA), respectively. METHODS Synovial tissue biopsy specimens were obtained from naive mice, mice with CIA, and mice with SCW-induced arthritis. The expression of messenger RNA (mRNA) for PAD enzymes was analyzed by reverse transcriptase-polymerase chain reaction; the presence of PAD proteins and their products (citrullinated proteins) was analyzed by Western blotting and by immunolocalization. The presence of anticitrullinated protein antibodies was investigated by an anti-cyclic citrullinated peptide (anti-CCP) enzyme-linked immunosorbent assay (ELISA) and an ELISA using in vitro citrullinated fibrinogen. RESULTS In both mouse models, PAD type 2 (PAD2) mRNA was present in the synovium but was not translated into PAD2 protein. In contrast, PAD4 mRNA, although absent from healthy synovium, was readily transcribed and translated by polymorphonuclear neutrophils infiltrating the synovial tissue during inflammation. As a consequence, several synovial proteins were subjected to citrullination. One of these proteins was identified as fibrin, which has been reported to be citrullinated also in synovium of patients with RA. Although generation of citrullinated antigens during synovial inflammation in the mice was eminent, no anti-CCP antibodies could be detected. CONCLUSION Citrullination of synovial antigens is an active process during joint inflammation in both mice and humans, but the induction of autoantibodies directed to these proteins is a more specific phenomenon, detectable only in human RA patients.
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MESH Headings
- Animals
- Antibody Specificity
- Arthritis, Experimental/immunology
- Arthritis, Experimental/metabolism
- Arthritis, Experimental/pathology
- Arthritis, Rheumatoid/immunology
- Arthritis, Rheumatoid/metabolism
- Arthritis, Rheumatoid/pathology
- Autoantibodies/blood
- Biopsy
- Citrulline/immunology
- Citrulline/metabolism
- Disease Models, Animal
- Epitopes
- Gene Expression Regulation, Enzymologic/immunology
- Hydrolases/genetics
- Hydrolases/metabolism
- Male
- Mice
- Mice, Inbred DBA
- Protein-Arginine Deiminase Type 2
- Protein-Arginine Deiminase Type 3
- Protein-Arginine Deiminase Type 4
- Protein-Arginine Deiminases
- Proteins/immunology
- Proteins/metabolism
- RNA, Messenger/analysis
- Synovial Fluid/immunology
- Synovial Membrane/enzymology
- Synovial Membrane/immunology
- Synovial Membrane/pathology
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Affiliation(s)
- Erik R Vossenaar
- Department of Biochemistry, University of Nijmegen, Nijmegen, The Netherlands.
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129
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Abstract
Posttranslational modifications of proteins often perform a key role in the biological functioning of proteins. Some of these modifications also change the immunogenicity of proteins and peptides and create 'self'-antigens which might induce autoimmune responses. In particular modifications of arginines within a defined protein context can lead to a specific B-cell immune response. This review discusses the generation of such modifications and their relevance for autoimmunity.
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Affiliation(s)
- M A M van Boekel
- Department of Biochemistry, University of Nijmegen, Nijmegen, The Netherlands.
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130
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Fritsch R, Eselböck D, Skriner K, Jahn-Schmid B, Scheinecker C, Bohle B, Tohidast-Akrad M, Hayer S, Neumüller J, Pinol-Roma S, Smolen JS, Steiner G. Characterization of autoreactive T cells to the autoantigens heterogeneous nuclear ribonucleoprotein A2 (RA33) and filaggrin in patients with rheumatoid arthritis. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:1068-76. [PMID: 12097415 DOI: 10.4049/jimmunol.169.2.1068] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The role of autoimmune reactions in the pathogenesis of rheumatoid arthritis (RA) is poorly understood. To address this issue we have investigated the spontaneous T cell response to two well-characterized humoral autoantigens in RA patients and controls: 1) the heterogeneous nuclear ribonucleoprotein A2, i.e., the RA33 Ag (A2/RA33), and 2) filaggrin in unmodified and citrullinated forms. In stimulation assays A2/RA33 induced proliferative responses in PBMC of almost 60% of the RA patients but in only 20% of the controls (patients with osteoarthritis or psoriatic arthritis and healthy individuals), with substantially stronger responses in RA patients (p < 0.00002). Furthermore, synovial T cells of seven RA patients investigated were also clearly responsive. In contrast, responses to filaggrin were rarely observed and did not differ between RA patients and controls. Analysis of A2/RA33-induced cytokine secretion revealed high IFN-gamma and low IL-4 production in both RA and control PBMC, whereas IL-2 production was mainly observed in RA PBMC (p < 0.03). Moreover, A2/RA33-specific T cell clones from RA patients showed a strong Th1 phenotype and secreted higher amounts of IFN-gamma than Th1 clones from controls (p < 0.04). Inhibition experiments performed with mAbs against MHC class II molecules showed A2/RA33-induced T cell responses to be largely HLA-DR restricted. Finally, immunohistochemical analyses revealed pronounced overexpression of A2/RA33 in synovial tissue of RA patients. Taken together, the presence of autoreactive Th1-like cells in RA patients in conjunction with synovial overexpression of A2/RA33 may indicate potential involvement of this autoantigen in the pathogenesis of RA.
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Affiliation(s)
- Ruth Fritsch
- Division of Rheumatology, Department of Internal Medicine III, University of Vienna, Vienna, Austria
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131
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Zhou Z, Ménard HA. Autoantigenic posttranslational modifications of proteins: does it apply to rheumatoid arthritis? Curr Opin Rheumatol 2002; 14:250-3. [PMID: 11981322 DOI: 10.1097/00002281-200205000-00010] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
There are many posttranslational modifications of proteins of which all are homeostatically important either to carry out a particular structural or functional role or to allow efficient recycling of the amino acid constituents. An important feature of the modified proteins is the acquisition of autoantigenicity. That notion should have been recognized for years with the modifications of immunoglobulin G that constitute new targets for rheumatoid factors. Citrullination or the deimination of arginine residues in proteins creates epitopes that are targeted by rheumatoid autoantibodies with a diagnostic sensitivity and specificity of 40% to 70% and 92% to 99%, respectively. The how, when, and why of the responsible break in tolerance are largely speculative but apoptosis, multiple genetic and environmental influences are likely required. Identifying citrullinated proteins as autoantigens has resulted in new diagnostic and prognostic autoantibody markers for RA and studying the citrullination process and its nature and role in cell biology has provided new insights into its pathogenesis.
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Affiliation(s)
- ZhiJie Zhou
- Division of Rheumatology, McGill University, Montreal, Quebec, Canada
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132
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Union A, Meheus L, Humbel RL, Conrad K, Steiner G, Moereels H, Pottel H, Serre G, De Keyser F. Identification of citrullinated rheumatoid arthritis-specific epitopes in natural filaggrin relevant for antifilaggrin autoantibody detection by line immunoassay. ARTHRITIS AND RHEUMATISM 2002; 46:1185-95. [PMID: 12115222 DOI: 10.1002/art.10229] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE To identify immunodominant epitopes in natural filaggrin that are reactive with antifilaggrin autoantibodies (AFA) in the sera of patients with rheumatoid arthritis (RA) and to explore their use in a diagnostic assay format. METHODS Based on the results of epitope mapping of human natural filaggrin as well as molecular modeling and computational chemistry, synthetic peptides together with recombinant citrullinated filaggrin were evaluated by a line immunoassay (LIA) for AFA detection. Diagnostic performance was assessed using 336 RA and 253 disease control sera and was compared with that of reference methods. RESULTS Several immunoreactive epitopes were identified in natural filaggrin, all of which contained at least 1 citrulline residue. Three antigenic substrates, including 2 synthetic peptides and recombinant citrullinated filaggrin showing maximal reactivity on LIA, were finally selected. Using the 3-antigen LIA3, overall sensitivity, specificity, and positive predictive value for RA were 65.2%, 98.0%, and 89.1%, respectively, compared with 61.9%, 98.8%, and 92.8% using the 2-antigen LIA2 (without recombinant protein). Thirty-seven percent of the rheumatoid factor (RF)-negative RA samples (30 of 81) were AFA-positive by LIA2, and 52 of 54 RF-positive control samples had no AFA detected on LIA2. Higher specificity and sensitivity were obtained by LIA2 versus anti-RA33 immunoblot, whereas good agreement was observed with antikeratin antibody testing. LIA performed significantly better than AFA immunoblotting using natural filaggrin, at a specificity level of 99% (P = 0.0047). CONCLUSION Citrullinated residues are present in immunoreactive epitopes of natural human filaggrin. AFA can be readily detected by citrullinated peptides in an LIA-based test, resulting in high specificity and positive predictive value for RA. The LIA could serve as a user-friendly alternative to existing immunofluorescence tests and AFA immunoblot techniques. Given its complementarity to RF, this test can be a valuable tool in the differential diagnosis of arthritis.
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Affiliation(s)
- Ann Union
- Immune Diseases Group, Innogenetics NV, Ghent, Belgium.
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133
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Steiner G, Smolen J. Autoantibodies in rheumatoid arthritis and their clinical significance. ARTHRITIS RESEARCH 2002; 4 Suppl 2:S1-5. [PMID: 12110150 PMCID: PMC3238219 DOI: 10.1186/ar551] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/17/2001] [Revised: 02/13/2002] [Accepted: 02/15/2002] [Indexed: 11/28/2022]
Abstract
Autoantibodies are proven useful diagnostic tools for a variety of rheumatic and non-rheumatic autoimmune disorders. However, a highly specific marker autoantibody for rheumatoid arthritis (RA) has not yet been determined. The presence of rheumatoid factors is currently used as a marker for RA. However, rheumatoid factors have modest specificity (~70%) for the disease. In recent years, several newly characterized autoantibodies have become promising candidates as diagnostic indicators for RA. Antikeratin, anticitrullinated peptides, anti-RA33, anti-Sa, and anti-p68 autoantibodies have been shown to have >90% specificity for RA. These autoantibodies are reviewed and the potential role of the autoantibodies in the pathogenesis of RA is briefly discussed.
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Affiliation(s)
- Günter Steiner
- Vienna General Hospital, University of Vienna, and Ludwig Boltzmann Institute for Rheumatology, Vienna, Austria.
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134
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van Boekel MAM, Vossenaar ER, van den Hoogen FHJ, van Venrooij WJ. Autoantibody systems in rheumatoid arthritis: specificity, sensitivity and diagnostic value. ARTHRITIS RESEARCH 2001; 4:87-93. [PMID: 11879544 PMCID: PMC128920 DOI: 10.1186/ar395] [Citation(s) in RCA: 251] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2001] [Revised: 10/05/2001] [Accepted: 10/09/2001] [Indexed: 11/10/2022]
Abstract
The diagnosis of rheumatoid arthritis (RA) is primarily based on clinical symptoms, so it is often difficult to diagnose RA in very early stages of the disease. A disease-specific autoantibody that could be used as a serological marker would therefore be very useful. Most autoimmune diseases are characterized by a polyclonal B-cell response targeting multiple autoantigens. These immune responses are often not specific for a single disease. In this review, the most important autoantibody/autoantigen systems associated with RA are described and their utility as a diagnostic and prognostic tool, including their specificity, sensitivity and practical application, is discussed. We conclude that, at present, the antibody response directed to citrullinated antigens has the most valuable diagnostic and prognostic potential for RA.
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Affiliation(s)
- Martinus A M van Boekel
- Department of Biochemistry, University of Nijmegen, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
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135
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Hengstman GJ, van Engelen BG, Vree Egberts WT, van Venrooij WJ. Myositis-specific autoantibodies: overview and recent developments. Curr Opin Rheumatol 2001; 13:476-82. [PMID: 11698723 DOI: 10.1097/00002281-200111000-00004] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Myositis-specific autoantibodies (MSAs) are found in almost half the patients with an idiopathic inflammatory myopathy (IIM). Several clinical and epidemiological studies have suggested that MSAs are associated with specific clinical characteristics. Some of these associations are well-defined and are of clinical significance ( eg, anti-Jo-1 and the anti-synthetase syndrome), others are less well established and can cause unnecessary anxiety for both patients and physicians ( eg, anti-SRP and cardiac involvement). In this review, an overview is given of the various MSAs, their biochemical background, their clinical usefulness, and the promises they hold for a better understanding of IIM.
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Affiliation(s)
- G J Hengstman
- Neuromuscular Centre Nijmegen, Institute of Neurology, University Medical Centre Nijmegen, Nijmegen, The Netherlands.
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136
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Smolen JS, Steiner G. Rheumatoid arthritis is more than cytokines: autoimmunity and rheumatoid arthritis. ARTHRITIS AND RHEUMATISM 2001; 44:2218-20. [PMID: 11665960 DOI: 10.1002/1529-0131(200110)44:10<2218::aid-art382>3.0.co;2-c] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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137
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Baeten D, Peene I, Union A, Meheus L, Sebbag M, Serre G, Veys EM, De Keyser F. Specific presence of intracellular citrullinated proteins in rheumatoid arthritis synovium: relevance to antifilaggrin autoantibodies. ARTHRITIS AND RHEUMATISM 2001; 44:2255-62. [PMID: 11665966 DOI: 10.1002/1529-0131(200110)44:10<2255::aid-art388>3.0.co;2-#] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE To investigate the presence of citrullinated proteins in the synovial membrane of patients with rheumatoid arthritis (RA) and controls, and to analyze a possible relationship with antifilaggrin autoantibody (AFA) reactivity. METHODS Synovial biopsy samples were obtained from 88 consecutive patients undergoing needle arthroscopy for knee synovitis associated with RA (n = 36), spondylarthropathy (n = 35), osteoarthritis (n = 9), or other diagnoses (n = 8). Tissue sections were stained with 2 different anticitrulline polyclonal antibodies and an antifilaggrin monoclonal antibody (mAb). The phenotype of citrulline-positive cells and the colocalization with affinity-purified AFA were investigated by double immunofluorescence on frozen sections. RESULTS Studies with the first antibody showed that citrulline is expressed intracellularly in the lining and sublining layers of RA synovial tissue. Staining with the second antibody, monospecific for proteins containing modified citrulline, and with anti-inducible nitric oxide synthetase confirmed the presence of citrullinated proteins rather than free citrulline in the synovium. Citrulline-positive cells were detected in 50% of the RA patients (18 of 36) but in none of the controls (0 of 52). The anticitrulline reactivity colocalized with affinity-purified AFA reactivity, although stainings with the antifilaggrin mAb indicated the absence of filaggrin in the synovium. CONCLUSION Intracellular citrullinated proteins, which are not recognized by an antifilaggrin mAb, are expressed in RA but not in control synovium. The high specificity of this finding and the colocalization with AFA reactivity boost the interest in citrullinated proteins as possible triggers of autoimmune responses in RA. Moreover, this is the first description of a specific histologic marker for RA synovium.
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Affiliation(s)
- D Baeten
- Department of Rheumatology, Ghent University Hospital, Belgium
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138
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Nogueira L, Sebbag M, Vincent C, Arnaud M, Fournié B, Cantagrel A, Jolivet M, Serre G. Performance of two ELISAs for antifilaggrin autoantibodies, using either affinity purified or deiminated recombinant human filaggrin, in the diagnosis of rheumatoid arthritis. Ann Rheum Dis 2001; 60:882-7. [PMID: 11502616 PMCID: PMC1753817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
OBJECTIVE To develop a standardisable enzyme linked immunosorbent assay (ELISA), using human filaggrin, for detection of antifilaggrin autoantibodies in rheumatoid arthritis (RA). To compare the diagnostic performance of the ELISA with those of reference tests: "antikeratin antibodies" ("AKA"), and antibodies to human epidermis filaggrin detected by immunoblotting (AhFA-IB). METHODS Two ELISAs were developed using either affinity purified neutral-acidic human epidermis filaggrin (AhFA-ELISA-pur) or a recombinant human filaggrin deiminated in vitro (AhFA-ELISA-rec) as immunosorbent. Antifilaggrin autoantibodies were assayed in 714 serum samples from patients with well characterised rheumatic diseases, including 241 RA and 473 other rheumatic diseases, using the two ELISAs. "AKA" and AhFA-IB tests were carried out in the same series of patients. The diagnostic performance of the four tests was compared and their relationships analysed. RESULTS The titres of "AKA", AhFA-IB, and the AhFA-ELISAs correlated strongly with each other. The diagnostic sensitivity of the AhFA-ELISA-rec, which was better than that of AhFA-ELISA-pur, was 0.52 for a specificity of 0.95. This performance was similar to those of "AKA" or AhFA-IB. However, combining AhFA-ELISA-rec with AhFA-IB led to a diagnostic sensitivity of 0.55 for a specificity of 0.99. CONCLUSION A simple and easily standardisable ELISA for detection of antifilaggrin autoantibodies was developed and validated on a large series of patients using a citrullinated recombinant human filaggrin. The diagnostic performance of the test was similar to that of the "AKA" and AhFA-IB. Nevertheless, combining the AhFA-ELISA-rec with one of the other tests clearly enhanced the performance.
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Affiliation(s)
- L Nogueira
- Department of Biology and Pathology of the Cell, Institut National de la Santé et de la Recherche Médicale (CJF 96-02), Toulouse-Purpan School of Medicine, University of Toulouse III (IFR Claude de Préval, INSERM-CNRS-UPS - CHU), France
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139
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Masson-Bessière C, Sebbag M, Girbal-Neuhauser E, Nogueira L, Vincent C, Senshu T, Serre G. The major synovial targets of the rheumatoid arthritis-specific antifilaggrin autoantibodies are deiminated forms of the alpha- and beta-chains of fibrin. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 166:4177-84. [PMID: 11238669 DOI: 10.4049/jimmunol.166.6.4177] [Citation(s) in RCA: 491] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
IgG antifilaggrin autoantibodies (AFA) are the most specific serological markers of rheumatoid arthritis. In epithelial tissues, they recognize citrulline-bearing epitopes present on various molecular forms of (pro)filaggrin. Histological analysis of rheumatoid synovial membranes with an Ab to citrulline showed labeling of interstitial amorphous deposits and mononuclear cells of various types. Immunochemical analysis of exhaustive sequential extracts of the same tissues showed that they contain several deiminated (citrulline containing) proteins. Among them, two proteins, p64--78 and p55--61, present in urea-DTT and guanidine extracts, were shown by immunoblotting to be specifically targeted by AFA. By amino-terminal sequencing the proteins were identified as deiminated forms of the alpha- and beta-chains of fibrin, respectively. Their identity was confirmed using several Abs specific for the A alpha- and/or to the B beta-chain of fibrin(ogen). Moreover, AFA-positive rheumatoid arthritis (RA) sera and purified AFA were highly reactive to the A alpha- and B beta-chains of human fibrinogen only after deimination of the molecules by a peptidylarginine deiminase. Autoantibodies affinity purified from a pool of RA sera onto deiminated fibrinogen were reactive toward all of the epithelial and synovial targets of AFA. This confirmed that the autoantibodies to the deiminated A alpha-and B beta-chains of fibrinogen, the autoantibodies to the synovial proteins p64--78 and p55--61, and, lastly, AFA, constitute largely overlapping autoantibody populations. These results show that deiminated forms of fibrin deposited in the rheumatoid synovial membranes are the major target of AFA. They suggest that autoimmunization against deiminated fibrin is a critical step in RA pathogenesis.
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Affiliation(s)
- C Masson-Bessière
- Department of Biology and Pathology of the Cell, Institut National de la Santé et de la Recherche Médicale Contrat Jeune Formation 96-02, Toulouse-Purpan School of Medicine, University Toulouse III, Toulouse, France
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Serre G. Autoantibodies to filaggrin/deiminated fibrin (AFA) are useful for the diagnosis and prognosis of rheumatoid arthritis, and are probably involved in the pathophysiology of the disease. Joint Bone Spine 2001; 68:103-5. [PMID: 11324923 DOI: 10.1016/s1297-319x(01)00259-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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141
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Serre G. Autoanticorps antifilaggrine/antifibrine déiminée. Outre leur intérêt diagnostique et pronostique, les autoanticorps antifilaggrine/antifibrine déiminée (AFA) sont probablement impliqués dans la physiopathogénie rhumatoïde. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s1169-8330(01)00131-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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142
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Baeten D, Peene I, Union A, Meheus L, Sebbag M, Serre G, Veys EM, De Keyser F. Specific presence of intracellular citrullinated proteins in rheumatoid arthritis synovium: Relevance to antifilaggrin autoantibodies. ACTA ACUST UNITED AC 2001. [DOI: 10.1002/1529-0131(200110)44:10<2255::aid-art388>3.0.co;2-%23] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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143
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van Venrooij WJ, Pruijn GJ. Citrullination: a small change for a protein with great consequences for rheumatoid arthritis. ARTHRITIS RESEARCH 2000; 2:249-51. [PMID: 11094435 PMCID: PMC130012 DOI: 10.1186/ar95] [Citation(s) in RCA: 157] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2000] [Revised: 05/02/2000] [Accepted: 05/08/2000] [Indexed: 11/26/2022]
Abstract
A new autoantibody activity, which is almost 100% specific for rheumatoid arthritis (RA), has been found. The essential part of the B-cell epitope is a modified form of arginine (ie citrulline). The conversion of protein-contained arginine to citrulline is an enzymatic process that is carried out by peptidylarginine deiminase (PAD), an enzyme that appears to be hormonally controlled. Because of its remarkable specificity, citrullination and related processes might open new possibilities for studying the aetiology of RA.
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Affiliation(s)
- W J van Venrooij
- Department of Biochemistry, University of Nijmegen, Nijmegen, The Netherlands.
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