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van der Meulen S, Zhang L, van Veenendaal JMF, van der Woude D, Trouw LA. Differences in avidity of anti-post-translationally modified protein antibodies in mouse models and rheumatoid arthritis patients: not one-size-fits-all. RMD Open 2024; 10:e004131. [PMID: 38796182 PMCID: PMC11129038 DOI: 10.1136/rmdopen-2024-004131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/30/2024] [Indexed: 05/28/2024] Open
Affiliation(s)
- Stef van der Meulen
- Department of Immunology, Leiden University Medical Center, Leiden, The Netherlands
| | - Lu Zhang
- Department of Immunology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Diane van der Woude
- Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands
| | - Leendert A Trouw
- Department of Immunology, Leiden University Medical Center, Leiden, The Netherlands
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2
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Nandakumar KS, Fang Q, Wingbro Ågren I, Bejmo ZF. Aberrant Activation of Immune and Non-Immune Cells Contributes to Joint Inflammation and Bone Degradation in Rheumatoid Arthritis. Int J Mol Sci 2023; 24:15883. [PMID: 37958864 PMCID: PMC10648236 DOI: 10.3390/ijms242115883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 10/25/2023] [Accepted: 10/30/2023] [Indexed: 11/15/2023] Open
Abstract
Abnormal activation of multiple immune and non-immune cells and proinflammatory factors mediate the development of joint inflammation in genetically susceptible individuals. Although specific environmental factors like smoking and infections are associated with disease pathogenesis, until now, we did not know the autoantigens and arthritogenic factors that trigger the initiation of the clinical disease. Autoantibodies recognizing specific post-translationally modified and unmodified antigens are generated and in circulation before the onset of the joint disease, and could serve as diagnostic and prognostic markers. The characteristic features of autoantibodies change regarding sub-class, affinity, glycosylation pattern, and epitope spreading before the disease onset. Some of these antibodies were proven to be pathogenic using animal and cell-culture models. However, not all of them can induce disease in animals. This review discusses the aberrant activation of major immune and non-immune cells contributing to joint inflammation. Recent studies explored the protective effects of extracellular vesicles from mesenchymal stem cells and bacteria on joints by targeting specific cells and pathways. Current therapeutics in clinics target cells and inflammatory pathways to attenuate joint inflammation and protect the cartilage and bones from degradation, but none cure the disease. Hence, more basic research is needed to investigate the triggers and mechanisms involved in initiating the disease and relapses to prevent chronic inflammation from damaging joint architecture.
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Affiliation(s)
- Kutty Selva Nandakumar
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17177 Stockholm, Sweden
- Department of Environmental and Biosciences, Halmstad University, 30118 Halmstad, Sweden; (I.W.Å.); (Z.F.B.)
| | - Qinghua Fang
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA;
| | - Isabella Wingbro Ågren
- Department of Environmental and Biosciences, Halmstad University, 30118 Halmstad, Sweden; (I.W.Å.); (Z.F.B.)
| | - Zoe Fuwen Bejmo
- Department of Environmental and Biosciences, Halmstad University, 30118 Halmstad, Sweden; (I.W.Å.); (Z.F.B.)
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3
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van den Beukel MD, Stoelinga AEC, van der Meer AJ, van der Meulen S, Zhang L, Tushuizen ME, van Hoek B, Trouw LA. Commentary: Commentary: Antibodies against multiple post-translationally modified proteins aid in diagnosis of autoimmune hepatitis and associate with complete biochemical response to treatment. Front Med (Lausanne) 2023; 10:1297191. [PMID: 37937138 PMCID: PMC10627174 DOI: 10.3389/fmed.2023.1297191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 10/06/2023] [Indexed: 11/09/2023] Open
Affiliation(s)
| | - Anna E C Stoelinga
- Department of Gastroenterology and Hepatology, Leiden University Medical Center, Leiden, Netherlands
| | - Adriaan J van der Meer
- Department of Gastroenterology and Hepatology, Erasmus Medical Center, Rotterdam, Netherlands
| | - Stef van der Meulen
- Department of Immunology, Leiden University Medical Center, Leiden, Netherlands
| | - Lu Zhang
- Department of Immunology, Leiden University Medical Center, Leiden, Netherlands
| | - Maarten E Tushuizen
- Department of Gastroenterology and Hepatology, Leiden University Medical Center, Leiden, Netherlands
| | - Bart van Hoek
- Department of Gastroenterology and Hepatology, Leiden University Medical Center, Leiden, Netherlands
| | - Leendert A Trouw
- Department of Immunology, Leiden University Medical Center, Leiden, Netherlands
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4
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Brevet P, Lattard C, Guillou C, Rottenberg P, Fardellone P, Le-Loët X, Lequerré T, Cosette P, Boyer O, Fréret M, Vittecoq O. Anti-Carbamylated Fibrinogen Antibodies Might Be Associated With a Specific Rheumatoid Phenotype and Include a Subset Recognizing In Vivo Epitopes of Its γ Chain One of Which Is Not Cross Reactive With Anti-Citrullinated Protein Antibodies. Front Immunol 2021; 12:733511. [PMID: 34691039 PMCID: PMC8529038 DOI: 10.3389/fimmu.2021.733511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 09/16/2021] [Indexed: 11/19/2022] Open
Abstract
To identify the targets recognized by anti-carbamylated protein antibodies (anti-CarP) in patients with early Rheumatoid Arthritis (RA), to study the cross-reactivity between anti-CarP and anti-citrullinated protein antibodies (ACPA) and to evaluate their prognostic value. 331 patients (184 RA and 147 other rheumatisms) from the Very Early Arthritis (VErA) French cohort were analyzed. We performed mass spectrometry analysis of RA sera displaying anti-CarP activity and epitope mapping of the carbamylated fibrinogen γ chain to identify immunodominant peptides. The specificity of these targets was studied using competition assays with the major antigens recognized by ACPA. The prognostic value of anti-carbamylated fibrinogen IgG antibodies (ACa-Fib IgG) was compared to that of anti-cyclic citrullinated peptide antibodies (anti-CCP) and anti-CarP using an in-house ELISA. Besides the α chain, the γ chain of fibrinogen, particularly one immunodominant epitope that has a specific reactivity, was identified as a circulating carbamylated target in sera. The prevalence of ACa-Fib was 37% at baseline and 10.9% for anti-CCP-negative RA. In anti-CCP-negative patients, ACa-Fib positivity was associated with a more inflammatory and erosive disease at baseline but not with rapid radiological progression, which remains strongly related to anti-CCP antibodies. Fibrinogen seems to be one of the antigens recognized in vivo by the anti-CarP response, particularly 2 epitopes of the γ chain, one of which is not cross reactive with ACPA. This specificity might be associated with a distinct clinical phenotype since ACa-Fib IgG were shown to be linked to systemic inflammation in very early RA but not to rapid radiological progression.
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Affiliation(s)
- Pauline Brevet
- Rouen University Hospital, Department of Rheumatology & CIC-CRB1404, Rouen, France.,Normandie University, UNIROUEN, INSERM, U1234, Rouen, France
| | - Claire Lattard
- Rouen University Hospital, Department of Rheumatology & CIC-CRB1404, Rouen, France.,Rouen University Hospital, Department of Pharmacology, Rouen, France
| | - Clément Guillou
- Normandie University, UNIROUEN, PISSARO Proteomics Facility & PBS-UMR6270 CNRS, IRIB, Rouen, France
| | - Pascal Rottenberg
- Rouen University Hospital, Department of Rheumatology & CIC-CRB1404, Rouen, France
| | | | - Xavier Le-Loët
- Rouen University Hospital, Department of Rheumatology & CIC-CRB1404, Rouen, France
| | - Thierry Lequerré
- Rouen University Hospital, Department of Rheumatology & CIC-CRB1404, Rouen, France.,Normandie University, UNIROUEN, INSERM, U1234, Rouen, France
| | - Pascal Cosette
- Normandie University, UNIROUEN, PISSARO Proteomics Facility & PBS-UMR6270 CNRS, IRIB, Rouen, France
| | - Olivier Boyer
- Normandie University, UNIROUEN, INSERM, U1234, Rouen, France.,Rouen University Hospital, Department of Immunology, Rouen, France
| | - Manuel Fréret
- Rouen University Hospital, Department of Rheumatology & CIC-CRB1404, Rouen, France.,Normandie University, UNIROUEN, INSERM, U1234, Rouen, France
| | - Olivier Vittecoq
- Rouen University Hospital, Department of Rheumatology & CIC-CRB1404, Rouen, France.,Normandie University, UNIROUEN, INSERM, U1234, Rouen, France
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5
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Impact of Posttranslational Modification in Pathogenesis of Rheumatoid Arthritis: Focusing on Citrullination, Carbamylation, and Acetylation. Int J Mol Sci 2021; 22:ijms221910576. [PMID: 34638916 PMCID: PMC8508717 DOI: 10.3390/ijms221910576] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 09/23/2021] [Accepted: 09/26/2021] [Indexed: 12/24/2022] Open
Abstract
Rheumatoid arthritis (RA) is caused by prolonged periodic interactions between genetic, environmental, and immunologic factors. Posttranslational modifications (PTMs) such as citrullination, carbamylation, and acetylation are correlated with the pathogenesis of RA. PTM and cell death mechanisms such as apoptosis, autophagy, NETosis, leukotoxic hypercitrullination (LTH), and necrosis are related to each other and induce autoantigenicity. Certain microbial infections, such as those caused by Porphyromonasgingivalis, Aggregatibacter actinomycetemcomitans, and Prevotella copri, can induce autoantigens in RA. Anti-modified protein antibodies (AMPA) containing anti-citrullinated protein/peptide antibodies (ACPAs), anti-carbamylated protein (anti-CarP) antibodies, and anti-acetylated protein antibodies (AAPAs) play a role in pathogenesis as well as in prediction, diagnosis, and prognosis. Interestingly, smoking is correlated with both PTMs and AMPAs in the development of RA. However, there is lack of evidence that smoking induces the generation of AMPAs.
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Xie X, van Delft MAM, Shuweihdi F, Kingsbury SR, Trouw LA, Doody GM, Conaghan PG, Ponchel F. Auto-antibodies to post-translationally modified proteins in osteoarthritis. Osteoarthritis Cartilage 2021; 29:924-933. [PMID: 33757859 DOI: 10.1016/j.joca.2021.03.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 03/10/2021] [Accepted: 03/15/2021] [Indexed: 02/07/2023]
Abstract
OBJECTIVE Autoantibodies (AutoAbs) have been observed in osteoarthritis (OA) with broad antigenicity, although their prevalence and role remain unclear. Post-translational modification (PTMs) of proteins (oxidation, carbamylation, citrullination) is associated with synovitis and can lead to AutoAb development. Given the prevalence of synovitis, we explored whether AutoAbs to PTM-antigens are common in OA compared with rheumatoid arthritis (RA). METHODS Serum (n = 895) was obtained from healthy controls, OA and RA patients; and arthritic synovial fluid (SF, n = 290). ELISAs were used to quantify anti-citrullinated peptide (ACPA), anti-carbamylated protein (anti-CarP), anti-oxidized collagen (anti-ROS-CI/CII) antibodies. RESULTS In sera, positivity for PTM-antigens AutoAbs was observed at a lower frequency in OA with 64.1% (95%CI: 57.2-70.1%) more ACPA+ and 29.8% (21.0-37.3%) more anti-CarP + patients in RA (both P < 0.0001). Levels of ACPA, anti-CarP were also lower in OA (P < 0.0001). Anti-ROS-CII positivity was lower in OA compared to RA (16.6%, 4.8-28.6%) less frequent, P = 0.033) but not anti-native-CII. There was no impact of age/gender on AutoAbs associations with diseases either looking at positivity or levels. In SF, OA patients were often ACPA+ (45.9%) although less frequently than in RA (P = 0.004). Anti-CarP were rarely observed (<5% all samples). All collagen AutoAbs were more frequent in RA compared to OA (all P < 0.010) but only levels of anti-CII and anti-ROS-CII were significantly higher in they RA (P < 0.050). CONCLUSION Although the frequency of AutoAbs for PTM proteins were lower in OA sera compared to RA, a higher proportion of OA SF were positive. The relative retention of AutoAbs in the OA joint requires further investigation.
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Affiliation(s)
- X Xie
- Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds and the NIHR Leeds Biomedical Research Centre, Leeds, UK.
| | - M A M van Delft
- Department of Rheumatology, Leiden University Medical Center, Leiden, the Netherlands.
| | - F Shuweihdi
- Leeds Institute of Health Sciences, University of Leeds, Leeds, UK.
| | - S R Kingsbury
- Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds and the NIHR Leeds Biomedical Research Centre, Leeds, UK.
| | - L A Trouw
- Department of Immunology, Leiden University Medical Center, Leiden, the Netherlands.
| | - G M Doody
- Division of Haematology and Immunology, Leeds Institute of Medical Research, University of Leeds, UK.
| | - P G Conaghan
- Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds and the NIHR Leeds Biomedical Research Centre, Leeds, UK.
| | - F Ponchel
- Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds and the NIHR Leeds Biomedical Research Centre, Leeds, UK.
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Avidity of anti-phospholipid antibodies in relation to their levels. Cent Eur J Immunol 2021; 45:136-143. [PMID: 33456323 PMCID: PMC7792445 DOI: 10.5114/ceji.2020.97901] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 05/07/2019] [Indexed: 11/30/2022] Open
Abstract
Introduction The heterogeneity of anti-phospholipid antibodies can be manifested not only in different antigenic specificities, but also in their avidities. The aim of the study was to investigate the relationship between anti-cardiolipin antibody (aCL) IgG avidities and levels within the range of their titres, from very low to high ones. Material and methods We analyzed 78 serum samples from 60 patients by ELISA with chaotropic agents, using urea concentration of 6 and 8 mol/l and single diluted serum samples. The changes of aCL levels and avidities were explored during a long-term follow-up in 14 patients. Results The avidities of aCLs did not differ in the groups of patients classified according to aCL levels. The higher avidity antibodies predominated in our patients and the fluctuation of avidities in the longitudinal follow-up did not show significant differences. No relationship between aCL levels and their avidities was found. Conclusions aCL avidities seem to have no relationship with aCL levels and high-avidity aCLs; the potentially deleterious effects might be present also in patients with low and extremely low aCL levels. Avidity of aCLs belongs to stable characteristics with insignificant changes in time.
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8
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Wu CY, Yang HY, Luo SF, Lai JH. From Rheumatoid Factor to Anti-Citrullinated Protein Antibodies and Anti-Carbamylated Protein Antibodies for Diagnosis and Prognosis Prediction in Patients with Rheumatoid Arthritis. Int J Mol Sci 2021; 22:ijms22020686. [PMID: 33445768 PMCID: PMC7828258 DOI: 10.3390/ijms22020686] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/04/2021] [Accepted: 01/06/2021] [Indexed: 02/07/2023] Open
Abstract
Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease mainly involving synovial inflammation and articular bone destruction. RA is a heterogeneous disease with diverse clinical presentations, prognoses and therapeutic responses. Following the first discovery of rheumatoid factors (RFs) 80 years ago, the identification of both anti-citrullinated protein antibodies (ACPAs) and anti-carbamylated protein antibodies (anti-CarP Abs) has greatly facilitated approaches toward RA, especially in the fields of early diagnosis and prognosis prediction of the disease. Although these antibodies share many common features and can function synergistically to promote disease progression, they differ mechanistically and have unique clinical relevance. Specifically, these three RA associating auto-antibodies (autoAbs) all precede the development of RA by years. However, while the current evidence suggests a synergic effect of RF and ACPA in predicting the development of RA and an erosive phenotype, controversies exist regarding the additive value of anti-CarP Abs. In the present review, we critically summarize the characteristics of these autoantibodies and focus on their distinct clinical applications in the early identification, clinical manifestations and prognosis prediction of RA. With the advancement of treatment options in the era of biologics, we also discuss the relevance of these autoantibodies in association with RA patient response to therapy.
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Affiliation(s)
- Chao-Yi Wu
- Division of Allergy, Asthma, and Rheumatology, Department of Pediatrics, Chang Gung Memorial Hospital, Taoyuan 33303, Taiwan;
- College of Medicine, Chang Gung University, Taoyuan 333, Taiwan;
| | - Huang-Yu Yang
- College of Medicine, Chang Gung University, Taoyuan 333, Taiwan;
- Department of Nephrology, Chang Gung Memorial Hospital, Taoyuan 333, Taiwan
| | - Shue-Fen Luo
- Division of Allergy, Immunology, and Rheumatology, Department of Internal Medicine, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan 333, Taiwan;
| | - Jenn-Haung Lai
- Division of Allergy, Immunology, and Rheumatology, Department of Internal Medicine, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan 333, Taiwan;
- Graduate Institute of Medical Science, National Defense Medical Center, Taipei 114, Taiwan
- Correspondence: ; Tel.: +886-2-8791-8382; Fax: +886-2-8791-8382
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van Delft MAM, Huizinga TWJ. An overview of autoantibodies in rheumatoid arthritis. J Autoimmun 2020; 110:102392. [PMID: 31911013 DOI: 10.1016/j.jaut.2019.102392] [Citation(s) in RCA: 162] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 12/13/2019] [Indexed: 12/21/2022]
Abstract
Rheumatoid arthritis (RA) is a systemic auto-immune disease principally effecting synovial joints. RA is characterized by immune cell infiltration in the joint. The presence of autoantibodies is a hallmark for the disease, among these are rheumatoid factor and antibodies against post-translational modified proteins like citrullination (ACPA) and carbamylation (anti-CarP antibodies). These autoantibodies may form immune complexes in the joint, leading to the attraction of immune cells. Based on the presence of these autoantibodies, RA patients can be subdivided in autoantibody positive and negative disease. Both subsets can be associated with genetic and environmental risk factors for RA, like the human leukocyte antigen (HLA) allele and smoking. Autoantibodies can already be detected years before disease onset in a subgroup of patients and at symptom onset a broad isotype spectrum is observed. This suggests that various events occur prior to the development of RA in which the first autoantibodies develop in predisposed individuals. Therefore, the presence of these autoantibodies can be useful in predicting future RA patients. Research on the characteristics and effector function of these autoantibodies is ongoing and will give more knowledge in the inflammatory responses underlying RA. This will give insight in the pathogenic role of autoantibodies in RA. Recent data are suggestive of a role for mucosal surfaces in the development of auto-immune responses associated with (the development of) RA. In conclusion, investigating the potential pathogenic effector functions of autoantibody isotypes and their molecular- and physicochemical-compositions might improve understanding of the disease origin and its underlying immunological processes. This may lead to the development of new therapeutic targets and strategies.
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Affiliation(s)
- Myrthe A M van Delft
- Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, the Netherlands.
| | - Tom W J Huizinga
- Department of Rheumatology, Leiden University Medical Center, Leiden, the Netherlands
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10
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Volkov M, van Schie KA, van der Woude D. Autoantibodies and B Cells: The ABC of rheumatoid arthritis pathophysiology. Immunol Rev 2019; 294:148-163. [PMID: 31845355 PMCID: PMC7065213 DOI: 10.1111/imr.12829] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 11/07/2019] [Indexed: 12/16/2022]
Abstract
Rheumatoid arthritis (RA) is an autoimmune disease characterized by joint inflammation. In the last few decades, new insights into RA‐specific autoantibodies and B cells have greatly expanded our understanding of the disease. The best‐known autoantibodies in RA—rheumatoid factor (RF) and anti‐citrullinated protein antibodies (ACPA)—are present long before disease onset, and both responses show signs of maturation around the time of the first manifestation of arthritis. A very intriguing characteristic of ACPA is their remarkably high abundance of variable domain glycans. Since these glycans may convey an important selection advantage of citrulline‐reactive B cells, they may be the key to understanding the evolution of the autoimmune response. Recently discovered autoantibodies targeting other posttranslational modifications, such as anti‐carbamylated and anti‐acetylated protein antibodies, appear to be closely related to ACPA, which makes it possible to unite them under the term of anti‐modified protein antibodies (AMPA). Despite the many insights gained about these autoantibodies, it is unclear whether they are pathogenic or play a causal role in disease development. Autoreactive B cells from which the autoantibodies originate have also received attention as perhaps more likely disease culprits. The development of autoreactive B cells in RA largely depends on the interaction with T cells in which HLA “shared epitope” and HLA DERAA may play an important role. Recent technological advances made it possible to identify and characterize citrulline‐reactive B cells and acquire ACPA monoclonal antibodies, which are providing valuable insights and help to understand the nature of the autoimmune response underlying RA. In this review, we summarize what is currently known about the role of autoantibodies and autoreactive B cells in RA and we discuss the most prominent hypotheses aiming to explain the origins and the evolution of autoimmunity in RA.
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Affiliation(s)
- Mikhail Volkov
- Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands
| | - Karin Anna van Schie
- Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands
| | - Diane van der Woude
- Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands
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11
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Zheng Z, Mergaert AM, Fahmy LM, Bawadekar M, Holmes CL, Ong IM, Bridges AJ, Newton MA, Shelef MA. Disordered Antigens and Epitope Overlap Between Anti-Citrullinated Protein Antibodies and Rheumatoid Factor in Rheumatoid Arthritis. Arthritis Rheumatol 2019; 72:262-272. [PMID: 31397047 DOI: 10.1002/art.41074] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 08/06/2019] [Indexed: 12/30/2022]
Abstract
OBJECTIVE Anti-citrullinated protein antibodies (ACPAs) and rheumatoid factor (RF) are commonly present in rheumatoid arthritis (RA) without a clear rationale for their coexistence. Moreover, autoantibodies develop against proteins with different posttranslational modifications and native proteins without obvious unifying characteristics of the antigens. We undertook this study to broadly evaluate autoantibody binding in seronegative and seropositive RA to identify novel features of reactivity. METHODS An array was created using a total of 172,828 native peptides, citrulline-containing peptides, and homocitrulline-containing peptides derived primarily from proteins citrullinated in the rheumatoid joint. IgG and IgM binding to peptides were compared between cyclic citrullinated peptide (CCP)-positive RF+, CCP+RF-, CCP-RF+, and CCP-RF- serum from RA patients (n = 48) and controls (n = 12). IgG-bound and endogenously citrullinated peptides were analyzed for amino acid patterns and predictors of intrinsic disorder, i.e., unstable 3-dimensional structure. Binding to IgG-derived peptides was specifically evaluated. Enzyme-linked immunosorbent assay confirmed key results. RESULTS Broadly, CCP+RF+ patients had high citrulline-specific IgG binding to array peptides and CCP+RF- and CCP-RF+ patients had modest citrulline-specific IgG binding (median Z scores 3.02, 1.42, and 0.75, respectively; P < 0.0001). All RA groups had low homocitrulline-specific binding. CCP+RF+ patients had moderate IgG binding to native peptides (median Z score 2.38; P < 0.0001). The highest IgG binding was to citrulline-containing peptides, irrespective of protein identity, especially if citrulline was adjacent to glycine or serine, motifs also seen in endogenous citrullination in the rheumatoid joint. Highly bound peptides had multiple features predictive of disorder. IgG from CCP+RF+ patients targeted citrulline-containing IgG-derived peptides. CONCLUSION Disordered antigens, which are frequently citrullinated, and common epitopes for ACPAs and RF are potentially unifying features for RA autoantibodies.
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Affiliation(s)
| | | | | | | | | | - Irene M Ong
- University of Wisconsin-Madison and University of Wisconsin Carbone Comprehensive Cancer Center
| | - Alan J Bridges
- University of Wisconsin-Madison and William S. Middleton Memorial Veterans Hospital
| | | | - Miriam A Shelef
- University of Wisconsin-Madison and William S. Middleton Memorial Veterans Hospital
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Nakabo S. Clinical and etiological meaning of anti-carbamylated protein antibodies in rheumatoid arthritis. Immunol Med 2019; 41:147-153. [PMID: 30714481 DOI: 10.1080/25785826.2018.1556017] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Several autoantibodies against proteins with post-translational modifications have been detected in patients with rheumatoid arthritis (RA) and are called anti-modified protein antibodies (AMPAs). Anti-carbamylated protein antibodies (Anti-CarP Ab) are the second most vigorously researched AMPAs following anti-citrullinated protein/peptide antibodies (ACPA). Anti-CarP Ab and ACPA show cross-reactivity to some extent and frequently co-exist with each other in RA, but are two distinct antibodies. Although the diagnostic efficacy of anti-CarP Ab is inferior to that of ACPA, the diagnostic specificity of RA may improve when used in combination with ACPA and rheumatoid factor. Anti-CarP Ab and ACPA are also useful for identifying patients at high risk of more severe joint destruction and cardiovascular diseases. The high prevalence of the co-existence of both antibodies suggests a common factor in their production, and this is important for the development of RA because both antibodies emerge before the onset of clinical symptoms. Neutrophils may also be crucially involved. It is important to distinguish citrullinated antigens from carbamylated antigens because the methods commonly used to detect the former are now known to be cross-reactive with the latter. Research on anti-CarP Ab will provide novel insights into the pathology and etiology of RA.
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Affiliation(s)
- Shuichiro Nakabo
- a Systemic Autoimmunity Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases , National Institutes of Health , Bethesda , MD , USA
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