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Rönnelid J, Turesson C, Kastbom A. Autoantibodies in Rheumatoid Arthritis - Laboratory and Clinical Perspectives. Front Immunol 2021; 12:685312. [PMID: 34054878 PMCID: PMC8161594 DOI: 10.3389/fimmu.2021.685312] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 04/20/2021] [Indexed: 01/03/2023] Open
Abstract
Measurement of two groups of autoantibodies, rheumatoid factor (RF) and anti-citrullinated protein/peptide antibodies (ACPA) have gained increasing significance in the diagnosis and classification of rheumatoid arthritis (RA) over the last 65 years. Despite this rising importance of autoimmune serology in RA, there is a palpable lack of harmonization between different commercial RF and ACPA tests. While a minimal diagnostic specificity has been defined for RF tests, which almost always are related to an international reference preparation, neither of this applies to ACPA. Especially assays with low diagnostic specificity are associated with very low positive predictive values or post-test probabilities in real world settings. In this review we focus on issues of practical bearing for the clinical physician diagnosing patients who potentially have RA, or treating patients diagnosed with RA. We advocate that all clinically used assays for RF and ACPA should be aligned to a common diagnostic specificity of 98-99% compared to healthy controls. This high and rather narrow interval corresponds to the diagnostic specificity seen for many commercial ACPA tests, and represents a specificity that is higher than what is customary for most RF assays. Data on antibody occurrence harmonized in this way should be accompanied by test result-specific likelihood ratios for the target diagnosis RA on an ordinal or interval scale, which will provide the clinical physician with more granular and richer information than merely relating numerical values to a single cut-off point. As many physicians today are used to evaluate autoantibodies as positive or negative on a nominal scale, the introduction of test result-specific likelihood ratios will require a change in clinical mindset. We also discuss the use of autoantibodies to prognosticate future arthritis development in at-risk patients as well as predict severe disease course and outcome of pharmacological treatment.
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Affiliation(s)
- Johan Rönnelid
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden.,Department of Clinical Immunology and Transfusion Medicine, Uppsala University Hospital, Uppsala, Sweden
| | - Carl Turesson
- Rheumatology, Department of Clinical Sciences, Malmö, Lund University, Malmö, Sweden.,Department of Rheumatology, Skåne University Hospital, Malmö, Sweden
| | - Alf Kastbom
- Department of Rheumatology, Linköping University Hospital, Linköping, Sweden.,Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
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Autoantibodies as Diagnostic Markers and Mediator of Joint Inflammation in Arthritis. Mediators Inflamm 2019; 2019:6363086. [PMID: 31772505 PMCID: PMC6854956 DOI: 10.1155/2019/6363086] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 09/14/2019] [Indexed: 12/11/2022] Open
Abstract
Rheumatoid arthritis is a systemic, polygenic, and multifactorial syndrome characterized by erosive polyarthritis, damage to joint architecture, and presence of autoantibodies against several self-structures in the serum and synovial fluid. These autoantibodies (anticitrullinated protein/peptide antibodies (ACPAs), rheumatoid factors (RF), anticollagen type II antibodies, antiglucose-6 phosphate isomerase antibodies, anticarbamylated protein antibodies, and antiacetylated protein antibodies) have different characteristics, diagnostic/prognostic value, and pathological significance in RA patients. Some of these antibodies are present in the patients' serum several years before the onset of clinical disease. Various genetic and environmental factors are associated with autoantibody production against different autoantigenic targets. Both the activating and inhibitory FcγRs and the activation of different complement cascades contribute to the downstream effector functions in the antibody-mediated disease pathology. Interplay between several molecules (cytokines, chemokines, proteases, and inflammatory mediators) culminates in causing damage to the articular cartilage and bones. In addition, autoantibodies are proven to be useful disease markers for RA, and different diagnostic tools are being developed for early diagnosis of the clinical disease. Recently, a direct link was proposed between the presence of autoantibodies and bone erosion as well as in the induction of pain. In this review, the diagnostic value of autoantibodies, their synthesis and function as a mediator of joint inflammation, and the significance of IgG-Fc glycosylation are discussed.
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Matsumoto I, Kurata I, Ohyama A, Kawaguchi H, Ebe H, Osada A, Kondo Y, Tsuboi H, Sumida T. Revisit of autoimmunity to glucose-6-phosphate isomerase in experimental and rheumatoid arthritis. Mod Rheumatol 2019; 30:232-238. [PMID: 31441345 DOI: 10.1080/14397595.2019.1659539] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Rheumatoid arthritis (RA) is an inflammatory disorder characterized by synovial inflammation in multiple joints. Autoantibodies (Abs) are the hallmark of RA, and as disease-specific and diagnostic markers, rheumatoid factor and anti-citrullinated protein antibody (ACPA) are produced pre-clinically, but their pathogenic roles in RA remain elusive. In this review, we focus on one of the candidate autoantigens in RA; glucose-6-phosphate isomerase (GPI). The arthritogenic role of GPI has been confirmed in two different mouse models: the K/BxN- and GPI-induced arthritis models. Both anti-GPI Abs and citrullinated-GPI peptide Abs have been detected in human RA. Studies conducted in these rodent models have confirmed that the pathogenesis of arthritis involves the localization of autoantigens not only in the joints but also in the circulation. In this review, we revisit and summarize the arthritogenic relevance of GPI in animal RA models and in human RA, and extend the discussion to joint-specific inflammation.
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Affiliation(s)
- Isao Matsumoto
- Department of Internal Medicine, Division of Rheumatology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Izumi Kurata
- Department of Internal Medicine, Division of Rheumatology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Ayako Ohyama
- Department of Internal Medicine, Division of Rheumatology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Hoshimi Kawaguchi
- Department of Internal Medicine, Division of Rheumatology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Hiroshi Ebe
- Department of Internal Medicine, Division of Rheumatology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Atsumu Osada
- Department of Internal Medicine, Division of Rheumatology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Yuya Kondo
- Department of Internal Medicine, Division of Rheumatology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Hiroto Tsuboi
- Department of Internal Medicine, Division of Rheumatology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Takayuki Sumida
- Department of Internal Medicine, Division of Rheumatology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
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Umeda N, Matsumoto I, Ito I, Kawasaki A, Tanaka Y, Inoue A, Tsuboi H, Suzuki T, Hayashi T, Ito S, Tsuchiya N, Sumida T. Anti-citrullinated glucose-6-phosphate isomerase peptide antibodies in patients with rheumatoid arthritis are associated with HLA-DRB1 shared epitope alleles and disease activity. Clin Exp Immunol 2013; 172:44-53. [PMID: 23480184 DOI: 10.1111/cei.12033] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/08/2012] [Indexed: 02/06/2023] Open
Abstract
To identify and characterize anti-citrullinated glucose-6-phosphate isomerase (GPI) peptide antibodies in patients with rheumatoid arthritis (RA). Nine GPI arginine-bearing peptides in human GPI protein were selected and cyclic citrullinated GPI peptides (CCG-1-9) were constructed. Samples were obtained from RA (n = 208), systemic lupus erythematosus (SLE) (n = 101), Sjögren's syndrome (SS; n = 101) and healthy controls (n = 174). Antibodies against CCG-1-9 were measured, and anti-citrullinated α-enolase-1 (CEP-1), -cyclic citrullinated peptides (CCP) and -GPI proteins antibodies were also examined. Patients with RA were genotyped for HLA-DRB1. The numbers of shared epitope (SE) alleles were counted and compared with those of the autoantibodies. Rabbit GPI was citrullinated with rabbit peptidylarginine deiminase and immunoblot analysis of RA sera performed. The levels of autoantibodies were compared before and after treatment with TNF antagonists in 58 RA patients. Anti-CCG-2, -4 and -7 antibodies were detected in 25·5, 33·2 and 37·0% patients with RA, respectively, and these antibodies were very specific for RA (specificity, 98·1-99·7%). Altogether, 44·2, 86·1 and 13·9% of RA sera were positive for anti-CEP-1, -CCP and -GPI protein antibodies, respectively. Anti-CCG-2, -4 and -7 antibodies were correlated with anti-CCP and anti-CEP-1 antibodies and with the presence of HLA-DRB1 SE alleles. Citrullinated GPI protein was detected using RA sera. Treatment with tumour necrosis factor antagonists reduced significantly the levels of anti-CCG-2 and -7 but not of anti-CEP-1 antibodies. This is the first report documenting the presence of anti-CCG antibodies in RA. Anti-CCG-2 and -7 antibodies could be considered as markers for the diagnosis of RA and its disease activity.
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Affiliation(s)
- N Umeda
- Department of Internal Medicine, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
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Matsumoto I, Iwanami K, Tanaka Y, Inoue A, Tanaka Y, Umeda N, Sumida T. [Autoimmunity to glycolytic enzyme in rheumatoid arthritis]. ACTA ACUST UNITED AC 2012; 34:456-63. [PMID: 22214806 DOI: 10.2177/jsci.34.456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Prognosis of rheumatoid arthritis (RA) patients has significantly improved with the recent use of biologics targeting TNFα, IL-6, and co-stimulatory molecule. In US and Europe, clear therapeutic benefit of anti-CD20 antibodies is also confirmed. As a disease specific marker, rheumatoid factor and anti-citrullinated protein antibody are crucial in RA, although the pathology of them is not defined. Here we focus on glycolytic enzyme such as glucose-6-phospate isomerase, that is confirmed as arthritogenic in two different mouse models, and discuss about pathogenic relevance to RA.
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Affiliation(s)
- Isao Matsumoto
- Division of Clinical Immunology, Graduate School of Comprehensive Human Science, University of Tsukuba, Japan
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Dai L, Zhu LJ, Zheng DH, Mo YQ, Wei XN, Su JH, Pessler F, Zhang BY. Elevated serum glucose-6-phosphate isomerase correlates with histological disease activity and clinical improvement after initiation of therapy in patients with rheumatoid arthritis. J Rheumatol 2010; 37:2452-61. [PMID: 20810510 DOI: 10.3899/jrheum.100157] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE To determine serum glucose-6-phosphate isomerase (GPI) concentrations in patients with rheumatoid arthritis (RA), and to test whether they correlate with objective measures of disease activity. METHODS Sera from 116 patients with RA, 69 patients with non-RA rheumatic diseases, and 101 healthy controls were analyzed. Levels of soluble serum GPI were measured by ELISA. Histological disease activity was determined with the synovitis score in synovial needle biopsies from 58 of the 116 patients with RA. Thirty-one of the 58 synovium samples were stained for CD68, CD3, CD20, CD38, CD79a, and CD34 by immunohistochemistry. Demographic data were collected, as well as serological and clinical variables that indicate RA disease activity, for Spearman correlation analysis. RESULTS Serum GPI level correlated positively with the synovitis score (r = 0.278, p = 0.034). Significantly higher soluble GPI levels were detected in the RA sera compared with sera from healthy controls and the non-RA disease controls (2.25 ± 2.82 vs 0.03 ± 0.05 and 0.19 ± 0.57 μg/ml, respectively; p < 0.0001). The rate of serum GPI positivity was significantly higher in the RA patients than in the non-RA disease controls (64.7% vs 10.1%; p < 0.0001). Spearman analysis showed no significant correlation between serum GPI level and Disease Activity Score in 28 joints at baseline. After initiation of antirheumatic treatments, GPI levels decreased significantly (2.81 ± 3.12 vs 1.44 ± 2.09 μg/ml; p = 0.016), paralleling improvement of the disease activity indices. CONCLUSION Elevated serum GPI may be involved in the synovitis of RA and may prove useful as a serum marker for disease activity of RA.
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Affiliation(s)
- Lie Dai
- Department of Rheumatology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, P.R. China.
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Machado P, Castrejon I, Katchamart W, Koevoets R, Kuriya B, Schoels M, Silva-Fernández L, Thevissen K, Vercoutere W, Villeneuve E, Aletaha D, Carmona L, Landewé R, van der Heijde D, Bijlsma JWJ, Bykerk V, Canhão H, Catrina AI, Durez P, Edwards CJ, Mjaavatten MD, Leeb BF, Losada B, Martín-Mola EM, Martinez-Osuna P, Montecucco C, Müller-Ladner U, Østergaard M, Sheane B, Xavier RM, Zochling J, Bombardier C. Multinational evidence-based recommendations on how to investigate and follow-up undifferentiated peripheral inflammatory arthritis: integrating systematic literature research and expert opinion of a broad international panel of rheumatologists in the 3E Initiative. Ann Rheum Dis 2010; 70:15-24. [PMID: 20724311 PMCID: PMC3002765 DOI: 10.1136/ard.2010.130625] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Objective To develop evidence-based recommendations on how to investigate and follow-up undifferentiated peripheral inflammatory arthritis (UPIA). Methods 697 rheumatologists from 17 countries participated in the 3E (Evidence, Expertise, Exchange) Initiative of 2008–9 consisting of three separate rounds of discussions and modified Delphi votes. In the first round 10 clinical questions were selected. A bibliographic team systematically searched Medline, Embase, the Cochrane Library and ACR/EULAR 2007–2008 meeting abstracts. Relevant articles were reviewed for quality assessment, data extraction and synthesis. In the second round each country elaborated a set of national recommendations. Finally, multinational recommendations were formulated and agreement among the participants and the potential impact on their clinical practice was assessed. Results A total of 39 756 references were identified, of which 250 were systematically reviewed. Ten multinational key recommendations about the investigation and follow-up of UPIA were formulated. One recommendation addressed differential diagnosis and investigations prior to establishing the operational diagnosis of UPIA, seven recommendations related to the diagnostic and prognostic value of clinical and laboratory assessments in established UPIA (history and physical examination, acute phase reactants, autoantibodies, radiographs, MRI and ultrasound, genetic markers and synovial biopsy), one recommendation highlighted predictors of persistence (chronicity) and the final recommendation addressed monitoring of clinical disease activity in UPIA. Conclusions Ten recommendations on how to investigate and follow-up UPIA in the clinical setting were developed. They are evidence-based and supported by a large panel of rheumatologists, thus enhancing their validity and practical use.
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Affiliation(s)
- P Machado
- Department of Rheumatology, Coimbra University Hospital, Coimbra, Portugal.
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Abstract
Inflammatory arthritis presents in a variety of diseases, from rheumatoid arthritis to hepatitis. Antibodies to autoantigens or to microbial constituents are commonly associated with these conditions. In some cases, the antibodies have diagnostic and prognostic relevance. It cannot as yet be determined definitively that any of them mediate joint damage, although the evidence from animal models indicates that this mechanism is likely. The purpose of this article is to give an overview of the spectrum of antibodies found in a variety of inflammatory arthritides. The relevant animal models are also discussed.
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Affiliation(s)
- Ann Duskin
- Department of Medicine, Pennsylvania Hospital, Philadelphia, PA, USA
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Robert-Pachot M, Desbos A, Moreira A, Becchi M, Tebib J, Bonnin M, Aitsiselmi T, Bienvenu J, Fabien N. Carbonic anhydrase III: A new target for autoantibodies in autoimmune diseases. Autoimmunity 2009; 40:380-9. [PMID: 17612900 DOI: 10.1080/08916930701417473] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The objective of this study was to identify new autoantibodies that could be useful for the diagnosis of rheumatoid arthritis (RA) using immunoblotting on synovial membrane proteins which represent the best source of candidate RA autoantigens. A new target protein with a molecular weight of 26 kDa was found to be recognized by autoantibodies in RA sera and was identified using MALDI-TOF mass spectrometry and second-dimension electrophoresis as carbonic anhydrase III (CAIII). Three similar protein spots at 26 kDa were recognized by both human sera and monoclonal antibody (mAb) directed against CAIII on immunoblotting using the human recombinant CAIII. Interestingly, CAIII expression within the synovial membrane was not observed in non-RA patients and was differentially expressed among RA patients. The sensitivity of these new autoantibodies for RA, using an immunoenzymatic technique, was 17%. Specificity was high when comparing non-autoimmune diseases (100%), while it was found to be weak (67%) when comparing some other autoimmune diseases, and particularly systemic lupus erythematosus (SLE). In conclusion, this study demonstrates that these new autoantibodies against CAIII are not restricted to RA. However the expression of CAIII in the synovial membrane of RA warrants further investigation of the pathophysiological relevance of this finding.
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Affiliation(s)
- Magali Robert-Pachot
- Department of Autoimmunity, Lyon-Sud Hospital, Hospices Civils de Lyon, Pierre Bénite, France
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Fabien N, Goetz J, Sordet C, Humbel RL, Sibilia J. [New autoanti-bodies in rheumatoid arthritis: anti-citrullinated protein or peptide autoanti-bodies and the others]. Presse Med 2008; 37:1756-66. [PMID: 18951757 DOI: 10.1016/j.lpm.2008.06.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2007] [Revised: 03/07/2008] [Accepted: 06/19/2008] [Indexed: 10/21/2022] Open
Abstract
New treatment strategies require that rheumatoid arthritis (RA) be diagnosed as early as possible. New diagnostic markers were required, because rheumatoid factors (RF), until now criteria for classification of RA, are not sufficiently specific and sometimes appear late, thereby limiting their diagnostic usefulness. The objective of this review is to describe the current state of knowledge and more particularly to analyze the interest of new RA autoanti-bodies, called anti-peptide or anti-citrullinated protein anti-bodies (ACPA). Other autoanti-bodies have been described, including anti-Sa, anti-alpha enolase, and anti-calpastatin autoanti-bodies. Nonetheless, their diagnostic value remains limited compared to ACPA. Accordingly, in daily practice today, the only autoanti-bodies that must be tested for to diagnose RA are the ACPAs and RFs. The discovery of ACPA (initially called anti-keratin and anti-perinuclear anti-bodies) was a major step forward for the laboratory diagnosis of RA. The tests most often used routinely areenzyme-linked immunosorbent assays(ELISA) with cyclic citrullinated peptides, whence the name anti-CCP autoanti-bodies. Accordingly, the two terms ACPA and anti-CCP can both be used. The diagnostic value, in particular their specificity, is on the order of 95%, regardless of the method of identification. These markers are very useful and are often present earlier than RF. These ACPA also have prognostic value because they are associated with more aggressive forms of RA. On the other hand, their value over time, in particular, their fluctuation as a function of treatment, is more controversial. In practice, it is recommended to test for both RF and ACPA in a diagnostic work-up for early RA. During follow-up, the value of testing for these autoanti-bodies has not been demonstrated, but additional studies are still necessary with the anti-CCP autoanti-bodies and the new anti-citrullinated protein autoanti-bodies.
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Affiliation(s)
- Nicole Fabien
- Laboratoire d'auto-immunité, Hospices Civils de Lyon, Centre hospitalier Lyon-Sud, F-69495 Pierre Bénite Cedex, France
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Robert-Pachot M, Desbos A, Moreira A, Becchi M, Tebib J, Bonnin M, Aitsiselmi T, Bienvenu J, Fabien N. A new target for autoantibodies in patients with rheumatoid arthritis. Ann N Y Acad Sci 2007; 1108:382-91. [PMID: 17894001 DOI: 10.1196/annals.1422.039] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Early treatment of rheumatoid arthritis (RA) with disease-modifying antirheumatic drugs can achieve a better disease outcome and reduce the severity of joint damage. The presence of autoantibodies in patient sera can precede onset of the disease and thus be predictive of the development of RA. To date, known autoantibodies in RA are positive in only 50-60% of RA patients at onset of disease and even less before the onset of any RA symptom. The aim of this study was to identify new antibodies that could be useful for the diagnosis of RA using synovial membrane proteins, which represent the best source of candidate RA autoantigens. The humoral reactivity of sera from RA patients was explored using immunoblotting on extracted proteins obtained from synovial membranes from RA after synovectomy or arthroplasty. A new target protein with a molecular weight of 26 kDa was found to be recognized by autoantibodies in RA sera. This protein was identified using MALDI-TOF mass spectrometry and two-dimensional electrophoresis as carbonic anhydrase III with a high level of confidence. In conclusion, this study demonstrates new autoantibodies in RA patients that are directed against carbonic anhydrase III. The sensitivity and specificity of these new autoantibodies for RA have to be further evaluated.
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Affiliation(s)
- Magali Robert-Pachot
- Hospices Civils de Lyon, INSERM U851, Lyon-Sud Hospital, Department of Immunology, 69495 Pierre-Bénite, France
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Hayashi T, Matsumoto I, Muraki Y, Takahashi R, Chino Y, Goto D, Ito S, Tsutsumi A, Sumida T. Clinical characteristics of anti-glucose-6-phosphate isomerase antibody-positive Japanese patients with rheumatoid arthritis. Mod Rheumatol 2007; 15:258-63. [PMID: 17029074 DOI: 10.1007/s10165-005-0405-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2005] [Accepted: 05/12/2005] [Indexed: 10/25/2022]
Abstract
Anti-glucose-6-phosphate isomerase (GPI) antibodies (Abs) are known to be arthritogenic in mice. These Abs are elevated in several forms of arthritic condition in humans, although their prevalence in rheumatoid arthritis (RA) patients is still in debate. Some RA patients have increased levels of anti-GPI Abs, but their clinical manifestation and relevance to other Abs are not clearly elucidated. The aims of this study were to explore the clinical and hematological characteristics of RA with anti-GPI Abs, and to compare their prevalence in RA patients, systemic lupus erythematosus (SLE) patients, and healthy subjects (HS) in a Japanese population. Anti-GPI Abs were positive in 16 patients with RA (12%, n = 137), in 10 patients with SLE (8%, n = 131), and in 6 HS (4%, n = 139). C-reactive protein (CRP), immunoglobulin G, and the antinuclear antibody titer were higher in anti-GPI-positive patients than in those who were negative (P = 0.049, P = 0.0003, and P = 0.002, respectively). Moreover, the positivity of anti-GPI Abs was correlated with CRP more than with rheumatoid factor in RA patients. It is unclear whether anti-GPI Abs can predict the progress of disease, but the prevalence of these Abs was higher in active RA patients with severe arthritis, suggesting that anti-GPI Abs may be related to the pathogenesis of severe forms of arthritis.
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Affiliation(s)
- Taichi Hayashi
- Clinical Immunology, Major of Advanced Biomedical Applications, Graduate School of Comprehensive Human Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, 305-8575, Japan
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Schaller M, Stohl W, Benoit V, Tan SM, Johansen L, Ditzel HJ. Patients with inflammatory arthritic diseases harbor elevated serum and synovial fluid levels of free and immune-complexed glucose-6-phosphate isomerase (G6PI). Biochem Biophys Res Commun 2006; 349:838-45. [PMID: 16949042 DOI: 10.1016/j.bbrc.2006.08.105] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Accepted: 08/18/2006] [Indexed: 11/23/2022]
Abstract
In K/BxN mice, anti-glucose-6-phosphate isomerase (G6PI) IgG antibodies (Abs) cause joint-specific inflammation and destruction. Anti-G6PI Abs are also present in humans with inflammatory arthritis, especially among patients with rheumatoid arthritis (RA). A contributing factor to the induction of such autoantibodies may be upregulated expression of the corresponding antigen G6PI in affected tissues and/or increased levels of G6PI in the circulation. To determine G6PI levels and the presence of free G6PI and/or G6PI-containing immune complexes in sera and synovial fluids (SF) of patients with different arthritides, serum and SF obtained concomitantly from 91 clinically well-defined arthritis patients were assessed in a blinded manner for G6PI enzymatic assay and for G6PI protein concentration by ELISA. Sera and SF from patients with immune-based inflammatory arthritis contained significantly higher levels of G6PI enzymatic activity compared to sera or SF from patients with non-immune-based inflammatory arthritis or healthy controls. In addition, significantly higher levels of total G6PI protein concentration (including both enzymatically active and inactive forms) were present in sera of RA patients vs. those with other immune-based or non-immune-based inflammatory arthritis.G6PI in sera and SF were present both as G6PI-containing immune complexes and as free G6PI, with the majority of free G6PI existing as tetramers with lesser amounts of dimers and monomers. Levels of G6PI enzymatic activity in the sera of most immune-based inflammatory arthritis patients are elevated and may reflect ongoing inflammation and cell destruction. The high serum levels of enzymatically inactive forms of G6PI in RA relative to those in other arthritic diseases are partially due to G6PI-containing immune complexes, a portion of which also contains C1q. Overall, our study supports the notion that elevated G6PI levels present in patients with immune-based inflammatory arthritis may contribute to elevated levels of anti-G6PI Abs and G6PI/anti-G6PI immune complexes. This, in turn, may trigger production of proinflammatory cytokines and perpetuate the inflammatory process.
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Affiliation(s)
- Monica Schaller
- Department of Immunology, IMM2, The Scripps Research Institute, La Jolla, CA 92037, USA
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Chaiamnuay S, Bridges SL. The role of B cells and autoantibodies in rheumatoid arthritis. ACTA ACUST UNITED AC 2006; 12:203-16. [PMID: 16102949 DOI: 10.1016/j.pathophys.2005.07.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In this article, we will review B lymphocyte development and function, then discuss the role of B cells in RA, including immune complex formation; the K/BxN mouse model of RA; toll-like receptors; B cells as antigen presenting cells; germinal center-like structures in RA synovium; and influence on T cell activation, leukocyte infiltration, and angiogenesis. With regard to autoantibody production, we will focus on rheumatoid factor (RF) and anti-CCP antibodies, particularly mechanisms of their production; sensitivity and specificity in RA; and their roles as prognostic factors. Other autoantibodies will be discussed, as will treatment implications and future areas of investigation related to B cells and autoantibodies in RA.
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Affiliation(s)
- Sumapa Chaiamnuay
- Division of Clinical Immunology and Rheumatology, Department of Medicine, 1530 3rd Avenue South, LHRB 412, University of Alabama at Birmingham, Birmingham, AL 35294-0007, USA
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