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Amjadi MF, Parker MH, Adyniec RR, Zheng Z, Robbins AM, Bashar SJ, Denny MF, McCoy SS, Ong IM, Shelef MA. Novel and unique rheumatoid factors cross-react with viral epitopes in COVID-19. J Autoimmun 2024; 142:103132. [PMID: 37956528 PMCID: PMC10957334 DOI: 10.1016/j.jaut.2023.103132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 10/05/2023] [Accepted: 10/12/2023] [Indexed: 11/15/2023]
Abstract
Rheumatoid factors (RFs), polyreactive antibodies canonically known to bind two conformational epitopes of IgG Fc, are a hallmark of rheumatoid arthritis but also can arise in other inflammatory conditions and infections. Also, infections may contribute to the development of rheumatoid arthritis and other autoimmune diseases. Recently, RFs only in rheumatoid arthritis were found to bind novel linear IgG epitopes as well as thousands of other rheumatoid arthritis autoantigens. Specific epitopes recognized by infection-induced polyreactive RFs remain undefined but could provide insights into loss of immune tolerance. Here, we identified novel linear IgG epitopes bound by RFs in COVID-19 but not rheumatoid arthritis or other conditions. The main COVID-19 RF was polyreactive, binding two IgG and multiple viral peptides with a tripeptide motif, as well as IgG Fc and SARS-CoV-2 spike proteins. In contrast, a rheumatoid arthritis-specific RF recognized IgG Fc, but not tripeptide motif-containing peptides or spike. Thus, RFs have disease-specific IgG reactivity and distinct polyreactivities that reflect the broader immune response. Moreover, the polyreactivity of a virus-induced RF appears to be attributable to a very short peptide motif. These findings refine our understanding of RFs and provide new insights into how viral infections may contribute to autoimmunity.
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Affiliation(s)
- Maya F Amjadi
- Department of Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | - Maxwell H Parker
- Department of Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | - Ryan R Adyniec
- Department of Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | - Zihao Zheng
- Department of Medicine, University of Wisconsin-Madison, Madison, WI, USA; Department of Statistics, University of Wisconsin-Madison, Madison, WI, USA
| | - Alex M Robbins
- Department of Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | - S Janna Bashar
- Department of Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | - Michael F Denny
- Department of Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | - Sara S McCoy
- Department of Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | - Irene M Ong
- Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, WI, USA; Department of Biostatistics and Medical Informatics, University of Wisconsin-Madison, Madison, WI, USA; Center for Human Genomics and Precision Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | - Miriam A Shelef
- Department of Medicine, University of Wisconsin-Madison, Madison, WI, USA; William S. Middleton Memorial Veterans Hospital, Madison, WI, USA.
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Impellizzeri D, Maftei D, Severini C, Miele R, Balboni G, Siracusa R, Cordaro M, Di Paola R, Cuzzocrea S, Lattanzi R. Blocking prokineticin receptors attenuates synovitis and joint destruction in collagen-induced arthritis. J Mol Med (Berl) 2023; 101:569-580. [PMID: 36988653 DOI: 10.1007/s00109-023-02307-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 02/09/2023] [Accepted: 03/14/2023] [Indexed: 03/30/2023]
Abstract
Rheumatoid arthritis (RA) is a chronic inflammatory disease mediated by an interdependent network of proinflammatory molecules such as chemokines. Prokineticin 2 (PK2) is a chemokine-like peptide that modulates nociceptive threshold and immuno-inflammatory processes via two G-protein-linked receptors, prokineticin receptor 1 and 2 (PKR1 and PKR2). In the present study, we investigated the effects of the prokineticin receptor antagonist PC1 on arthritic pain and the inflammatory response in type II collagen-induced arthritis (CIA) in mice. We demonstrated that PC1, administered subcutaneously from day 25 to day 35 after CIA, improved clinical signs of arthritis such as paw edema, pain, and impaired locomotor activity. In CIA mice, PC1 was also able to lower plasma malondialdehyde (MDA) levels, suggesting a role in reducing oxidative damage, as well as joint expression levels of PK2, PKRs, TNFα, IL-1β, CD4, CD8, and NF-kB. These results suggest that blocking PKRs may be a successful strategy to control arthritic pain and pathology development. KEY MESSAGES: PK2/PKRs expression levels strongly increase in the synovium of RA mice. PC1 treatment shows anti-arthritic activity and reduces arthritis-induced pain. PC1 treatment significantly lowers synovial PK2/PKRs levels. PC1 treatment lowers plasma MDA levels and synovial levels of TNFα and IL -1β PC1 treatment is a viable therapeutic option for RA.
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Affiliation(s)
- Daniela Impellizzeri
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166, Messina, Italy
| | - Daniela Maftei
- Department of Physiology and Pharmacology, Vittorio Erspamer", Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy
| | - Cinzia Severini
- Department of Biochemistry and Cell Biology, National Research Council of Italy, Rome, Italy
| | - Rossella Miele
- Department of Biochemical Sciences "Alessandro Rossi Fanelli", Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy
| | - Gianfranco Balboni
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Rosalba Siracusa
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166, Messina, Italy
| | - Marika Cordaro
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166, Messina, Italy
| | - Rosanna Di Paola
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166, Messina, Italy
| | - Salvatore Cuzzocrea
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166, Messina, Italy
| | - Roberta Lattanzi
- Department of Physiology and Pharmacology, Vittorio Erspamer", Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy.
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Feyzkhanova GU, Voloshin SA, Novikov AA, Aleksandrova EN, Smoldovskaya OV, Rubina AY. Analysis of rheumatoid factor and acute phase proteins using microarrays in patients with rheumatoid arthritis. Klin Lab Diagn 2022; 67:43-47. [PMID: 35077069 DOI: 10.51620/0869-2084-2022-67-1-43-47] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
One of the biomarkers of biggest clinical importance in rheumatoid arthritis (RA) is rheumatoid factor (IgM RF). The rheumatoid factor has insufficient sensitivity and specificity, therefore, to increase the diagnostic information of the test, acute phase proteins were used as concomitant biomarkers. Using biological microchips, we measured IgM RF, C-reactive protein (CRP) and Serum amyloid protein A (SAA) in patients with RA (n = 60), ankylosing spondylitis (AS) (n=55), systemic lupus erythematosus (SLE) (n=20) and healthy donors (HD) (n=9). It was shown that the medians of IgM RF concentrations are significantly higher (p<0.01) in patients with RA compared to patients suffering from other diseases and healthy donors. CRP and SAA were also significantly increased (p<0.05) in patients with RA and AS compared with SLE and HD. It has been shown that the complex determination of three biomarkers in differentiating RA patients with the comparison group had a higher diagnostic sensitivity than the isolated determination of IgM RF, while the addition of SAA makes the greatest contribution to improving the diagnostic characteristics of the biomarker panel: the use of a logistic regression model based on IgM RF and SAA allowed to increase the diagnostic sensitivity of the analysis from 58.3% to 65%. Thus, the developed microarray-based method can be used to detect and elucidate the diagnostic characteristics of RA biomarkers; however, further use requires validation of the obtained results on an expanded sampling.
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Affiliation(s)
- G U Feyzkhanova
- FSBIS Engelhardt Institute of Molecular Biology, Russian Academy of Sciences
| | - S A Voloshin
- FSBIS Engelhardt Institute of Molecular Biology, Russian Academy of Sciences
| | - A A Novikov
- SBIHC Moscow Clinical Scientific Center n.a. A.S. Loginov
| | | | - O V Smoldovskaya
- FSBIS Engelhardt Institute of Molecular Biology, Russian Academy of Sciences
| | - A Yu Rubina
- FSBIS Engelhardt Institute of Molecular Biology, Russian Academy of Sciences
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4
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Mergaert AM, Zheng Z, Denny MF, Amjadi MF, Bashar SJ, Newton MA, Malmström V, Grönwall C, McCoy SS, Shelef MA. Rheumatoid factor and anti-modified protein antibody reactivities converge on IgG epitopes. Arthritis Rheumatol 2022; 74:984-991. [PMID: 35001558 DOI: 10.1002/art.42064] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 11/19/2021] [Accepted: 01/04/2022] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Rheumatoid arthritis (RA) patients often develop rheumatoid factors (RFs), antibodies that bind IgG Fc, and anti-modified protein antibodies (AMPAs), multi-reactive autoantibodies that commonly bind citrullinated, homocitrullinated, and acetylated antigens. Recently, antibodies that bind citrulline-containing IgG epitopes were discovered in RA, suggesting that additional undiscovered IgG epitopes could exist and that IgG could be a shared antigen for RFs and AMPAs. The objective of this study was to reveal new IgG epitopes in rheumatic disease and to determine if multi-reactive AMPAs bind IgG. METHODS Using RA, systemic lupus erythematosus, Sjögren's disease, and spondyloarthropathy sera, IgG binding to native, citrulline-containing, and homocitrulline-containing linear epitopes of the IgG constant region were evaluated by peptide array with highly bound epitopes further evaluated by ELISA. Monoclonal AMPA binding to IgG-derived peptides and IgG Fc was evaluated by ELISA. RESULTS Seropositive RA sera had high IgG binding to multiple citrulline- and homocitrulline-containing IgG-derived peptides, whereas anti-SSA+ Sjögren's disease sera had consistent binding to a single linear native epitope of IgG in the hinge region. Monoclonal AMPAs bound citrulline- and homocitrulline-containing IgG peptides and modified IgG Fc. CONCLUSION The repertoire of epitopes bound by AMPAs includes modified IgG epitopes, positioning IgG as a common antigen that connects the otherwise divergent reactivities of RFs and AMPAs.
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Affiliation(s)
- Aisha M Mergaert
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, USA.,Department of Medicine, University of Wisconsin-Madison, Madison, USA
| | - Zihao Zheng
- Department of Statistics, University of Wisconsin-Madison, Madison, USA.,Department of Medicine, University of Wisconsin-Madison, Madison, USA
| | - Michael F Denny
- Department of Medicine, University of Wisconsin-Madison, Madison, USA
| | - Maya F Amjadi
- Department of Medicine, University of Wisconsin-Madison, Madison, USA
| | - S Janna Bashar
- Department of Medicine, University of Wisconsin-Madison, Madison, USA
| | - Michael A Newton
- Department of Statistics, University of Wisconsin-Madison, Madison, USA
| | - Vivianne Malmström
- Division of Rheumatology, Department of Medicine Solna, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Caroline Grönwall
- Division of Rheumatology, Department of Medicine Solna, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Sara S McCoy
- Department of Medicine, University of Wisconsin-Madison, Madison, USA
| | - Miriam A Shelef
- Department of Medicine, University of Wisconsin-Madison, Madison, USA.,William S. Middleton Memorial Veterans Hospital, Madison, USA
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Abstract
Based on the PubMed data, we have been performing a yearly evaluation of the publications related to autoimmune diseases and immunology to ascertain the relative weight of the former in the scientific literature. It is particularly intriguing to observe that despite the numerous new avenues of immune-related mechanisms, such as cancer immunotherapy, the proportion of immunology manuscripts related to autoimmunity continues to increase and has been approaching 20% in 2019. As in the previous 13 years, we performed an arbitrary selection of the peer-reviewed articles published by the major dedicated Journals and discussed the common themes which continue to outnumber peculiarites in autoimmune diseases. The investigated areas included systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), psoriatic arthritis (PsA), autoantibodies (autoAbs), and common therapeutic avenues and novel pathogenic mechanisms for autoimmune conditions. Some examples include new pathogenetic evidence which is well represented by IL21 or P2X7 receptor (P2X7R) in SLE or the application of single-cell RNA sequencing (scRNA-seq), mass cytometry, bulk RNA sequencing (RNA-seq), and flow cytometry for the analysis of different cellular populations in RA. Cumulatively and of interest to the clinicians, a large number of findings continue to underline the importance of a strict relationship between basic and clinical science to define new pathogenetic and therapeutic developments. The therapeutic pipeline in autoimmunity continues to grow and maintain a constant flow of new molecules, as well illustrated in RA and PsA, and this is most certainly derived from the new basic evidence and the high-throughput tools applied to autoimmune diseases.
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Daphnetin induces apoptosis in fibroblast-like synoviocytes from collagen-induced arthritic rats mainly via the mitochondrial pathway. Cytokine 2020; 133:155146. [PMID: 32505094 DOI: 10.1016/j.cyto.2020.155146] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 05/22/2020] [Accepted: 05/23/2020] [Indexed: 01/27/2023]
Abstract
Rheumatoid arthritis (RA) is a chronic, symmetric, systemic autoimmune disease. Because insufficient apoptosis of fibroblast-like synoviocytes (FLS) is an important characteristic of RA, promoting apoptosis is considered a potential therapeutic tool for treating RA. We have previously found that daphnetin (7,8-dihydroxycoumarin, DAP) has a pro-apoptotic effect on fibroblast-like synoviocytes from collagen-induced arthritis (CIA) rats. In the present study, we further investigated the mechanisms of DAP-induced apoptosis in CIA-FLS. CIA-FLS were incubated with DAP for 48 h in the presence or absence of caspase inhibitors, including inhibitors of caspase-3, caspase-8, or caspase-9 or a pan-caspase inhibitor; then, a series of experiments were performed to evaluate the mechanisms of DAP-induced apoptosis. Our results showed that DAP markedly decreased cell viability and induced the apoptosis of CIA-FLS along with typical morphological and ultrastructural changes; moreover, DAP increased FasL, cytochrome c (Cyt-c), Bax, caspase-3, caspase-8, and caspase-9 mRNA expression and Bax, caspase-3, caspase-8, and caspase-9 protein expression. In contrast, DAP decreased Bcl-2 mRNA and protein expression and promoted the release of Cyt-c from the mitochondria into the cytosol; these effects were attenuated to varying degrees by pre-treatment with caspase inhibitors, especially with caspase-3 or caspase-9 inhibitors or a pan-caspase inhibitor. In conclusion, the current findings demonstrate that the DAP-induced apoptosis of CIA-FLS occurred mainly via a caspase-dependent pathway, in particular the mitochondrial pathway, and that the Bax/Bcl-2 ratio was involved in this process. Thus, DAP may be a potential therapeutic agent for RA.
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Deng H, Zheng M, Hu Z, Zeng X, Kuang N, Fu Y. Effects of daphnetin on the autophagy signaling pathway of fibroblast-like synoviocytes in rats with collagen-induced arthritis (CIA) induced by TNF-α. Cytokine 2020; 127:154952. [DOI: 10.1016/j.cyto.2019.154952] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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8
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Regueiro C, Rodriguez-Rodriguez L, Lopez-Mejias R, Nuño L, Triguero-Martinez A, Perez-Pampin E, Corrales A, Villalba A, Lopez-Golan Y, Abasolo L, Remuzgo-Martínez S, Ortiz AM, Herranz E, Martínez-Feito A, Conde C, Mera-Varela A, Balsa A, Gonzalez-Alvaro I, González-Gay MÁ, Fernandez-Gutierrez B, Gonzalez A. A predominant involvement of the triple seropositive patients and others with rheumatoid factor in the association of smoking with rheumatoid arthritis. Sci Rep 2020; 10:3355. [PMID: 32098994 PMCID: PMC7042270 DOI: 10.1038/s41598-020-60305-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 02/07/2020] [Indexed: 01/16/2023] Open
Abstract
The major environmental risk factor for rheumatoid arthritis (RA) is smoking, which according to a widely accepted model induces protein citrullination in the lungs, triggering the production of anti-citrullinated protein antibodies (ACPA) and RA development. Nevertheless, some research findings do not fit this model. Therefore, we obtained six independent cohorts with 2253 RA patients for a detailed analysis of the association between smoking and RA autoantibodies. Our results showed a predominant association of smoking with the concurrent presence of the three antibodies: rheumatoid factor (RF), ACPA and anti-carbamylated protein antibodies (ACarPA) (3 Ab vs. 0 Ab: OR = 1.99, p = 2.5 × 10–8). Meta-analysis with previous data (4491 patients) confirmed the predominant association with the concurrent presence of the three antibodies (3 Ab vs. 0 Ab: OR = 2.00, p = 4.4 ×10–16) and revealed that smoking was exclusively associated with the presence of RF in patients with one or two antibodies (RF+1+2vs. RF−0+1+2: OR = 1.32, p = 0.0002). In contrast, no specific association with ACPA or ACarPA was found. Therefore, these results showed the need to understand how smoking favors the concordance of RA specific antibodies and RF triggering, perhaps involving smoking-induced epitope spreading and other hypothesized mechanisms.
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Affiliation(s)
- Cristina Regueiro
- Experimental and Observational Rheumatology and Rheumatology Unit, Instituto de Investigacion Sanitaria, Hospital Clínico Universitario de Santiago (IDIS), Santiago de Compostela, Spain
| | - Luis Rodriguez-Rodriguez
- Rheumatology Department, Hospital Clínico San Carlos, Instituto Investigación Sanitaria San Carlos (IdISSC), Madrid, Spain
| | - Raquel Lopez-Mejias
- Valdecilla Biomedical Research Institute, Hospital Universitario Marqués de Valdecilla (IDIVAL), Santander, Spain
| | - Laura Nuño
- Rheumatology Department, Instituto de Investigación Hospital Universitario La Paz (IDIPAZ), Madrid, Spain
| | - Ana Triguero-Martinez
- Rheumatology Department, Instituto de Investigación Sanitaria la Princesa, Hospital Universitario de la Princesa (IIS-lP), Madrid, Spain
| | - Eva Perez-Pampin
- Experimental and Observational Rheumatology and Rheumatology Unit, Instituto de Investigacion Sanitaria, Hospital Clínico Universitario de Santiago (IDIS), Santiago de Compostela, Spain
| | - Alfonso Corrales
- Valdecilla Biomedical Research Institute, Hospital Universitario Marqués de Valdecilla (IDIVAL), Santander, Spain
| | - Alejandro Villalba
- Rheumatology Department, Instituto de Investigación Hospital Universitario La Paz (IDIPAZ), Madrid, Spain
| | - Yolanda Lopez-Golan
- Experimental and Observational Rheumatology and Rheumatology Unit, Instituto de Investigacion Sanitaria, Hospital Clínico Universitario de Santiago (IDIS), Santiago de Compostela, Spain
| | - Lydia Abasolo
- Rheumatology Department, Hospital Clínico San Carlos, Instituto Investigación Sanitaria San Carlos (IdISSC), Madrid, Spain
| | - Sara Remuzgo-Martínez
- Valdecilla Biomedical Research Institute, Hospital Universitario Marqués de Valdecilla (IDIVAL), Santander, Spain
| | - Ana M Ortiz
- Rheumatology Department, Instituto de Investigación Sanitaria la Princesa, Hospital Universitario de la Princesa (IIS-lP), Madrid, Spain
| | - Eva Herranz
- Rheumatology Department, Hospital Clínico San Carlos, Instituto Investigación Sanitaria San Carlos (IdISSC), Madrid, Spain
| | - Ana Martínez-Feito
- Immuno-Rheumatology Department, Instituto de Investigación Hospital Universitario La Paz (IDIPAZ), Madrid, Spain
| | - Carmen Conde
- Experimental and Observational Rheumatology and Rheumatology Unit, Instituto de Investigacion Sanitaria, Hospital Clínico Universitario de Santiago (IDIS), Santiago de Compostela, Spain
| | - Antonio Mera-Varela
- Experimental and Observational Rheumatology and Rheumatology Unit, Instituto de Investigacion Sanitaria, Hospital Clínico Universitario de Santiago (IDIS), Santiago de Compostela, Spain.,Faculty of Medicine and Dentistry, University of Santiago de Compostela, Santiago de Compostela, Spain
| | - Alejandro Balsa
- Rheumatology Department, Instituto de Investigación Hospital Universitario La Paz (IDIPAZ), Madrid, Spain
| | - Isidoro Gonzalez-Alvaro
- Rheumatology Department, Instituto de Investigación Sanitaria la Princesa, Hospital Universitario de la Princesa (IIS-lP), Madrid, Spain
| | - Miguel Ángel González-Gay
- Valdecilla Biomedical Research Institute, Hospital Universitario Marqués de Valdecilla (IDIVAL), Santander, Spain
| | - Benjamín Fernandez-Gutierrez
- Rheumatology Department, Hospital Clínico San Carlos, Instituto Investigación Sanitaria San Carlos (IdISSC), Madrid, Spain
| | - Antonio Gonzalez
- Experimental and Observational Rheumatology and Rheumatology Unit, Instituto de Investigacion Sanitaria, Hospital Clínico Universitario de Santiago (IDIS), Santiago de Compostela, Spain.
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Regueiro C, Gonzalez A. Correspondence on ‘Shared epitope defines distinct associations of cigarette smoking with levels of anticitrullinated protein antibody and rheumatoid factor’ by Ishikawa et al. Ann Rheum Dis 2019; 81:e1. [DOI: 10.1136/annrheumdis-2019-216849] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 12/20/2019] [Indexed: 11/04/2022]
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10
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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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11
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WITHDRAWN: Effects of daphnetin on the autophagy signaling pathway of fibroblast-like synoviocytes in rats with collagen-induced arthritis (CIA) induced by TNF-α. Cytokine X 2019; 1:100015. [DOI: 10.1016/j.cytox.2019.100015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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