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Trier NH, Houen G. Antibody Cross-Reactivity in Auto-Immune Diseases. Int J Mol Sci 2023; 24:13609. [PMID: 37686415 PMCID: PMC10487534 DOI: 10.3390/ijms241713609] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 08/25/2023] [Accepted: 08/29/2023] [Indexed: 09/10/2023] Open
Abstract
Autoimmunity is defined by the presence of antibodies and/or T cells directed against self-components. Although of unknown etiology, autoimmunity commonly is associated with environmental factors such as infections, which have been reported to increase the risk of developing autoimmune diseases. Occasionally, similarities between infectious non-self and self-tissue antigens may contribute to immunological cross-reactivity in autoimmune diseases. These reactions may be interpreted as molecular mimicry, which describes cross-reactivity between foreign pathogens and self-antigens that have been reported to cause tissue damage and to contribute to the development of autoimmunity. By focusing on the nature of antibodies, cross-reactivity in general, and antibody-antigen interactions, this review aims to characterize the nature of potential cross-reactive immune reactions between infectious non-self and self-tissue antigens which may be associated with autoimmunity but may not actually be the cause of disease onset.
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Affiliation(s)
- Nicole Hartwig Trier
- Department of Neurology, Rigshospitalet Glostrup, Valdemar Hansens Vej 1-23, 2600 Glostrup, Denmark
| | - Gunnar Houen
- Department of Neurology, Rigshospitalet Glostrup, Valdemar Hansens Vej 1-23, 2600 Glostrup, Denmark
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
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Trier NH, Houen G. Anti-citrullinated protein antibodies as biomarkers in rheumatoid arthritis. Expert Rev Mol Diagn 2023; 23:895-911. [PMID: 37578277 DOI: 10.1080/14737159.2023.2247986] [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: 03/29/2023] [Revised: 07/15/2023] [Accepted: 08/10/2023] [Indexed: 08/15/2023]
Abstract
INTRODUCTION The serological biomarker anti-citrullinated protein antibodies (ACPAs) may have several functions but is especially important for the diagnosis of rheumatoid arthritis (RA) along with clinical symptoms. AREAS COVERED This review provides an overview of ACPAs, which are useful in RA diagnostics and may improve our understanding of disease etiology. PubMed was searched with combinations of words related to antibodies recognizing epitopes containing the post-translationally modified amino acid citrulline in combination with rheumatoid arthritis; cyclic citrullinated peptide, CCP, anti-CCP, anti-citrullinated protein antibodies, ACPA, citrullination, peptide/protein arginine deiminase, PAD, filaggrin, vimentin, keratin, collagen, perinuclear factor, EBNA1, EBNA2, and others. From this search, we made a qualitative extract of publications relevant to the discovery, characterization, and clinical use of these antibodies in relation to RA. We highlight significant findings and identify areas for improvement. EXPERT OPINION ACPAs have high diagnostic sensitivity and specificity for RA and recognize citrullinated epitopes from several proteins. The best-performing single epitope originates from Epstein-Barr Virus nuclear antigen 2 and contains a central Cit-Gly motif, which is recognized by ACPAS when located in a flexible peptide structure. In addition, ACPAs may also have prognostic value, especially in relation to early treatment, although ACPAs' main function is to aid in the diagnosis of RA.
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Affiliation(s)
| | - Gunnar Houen
- Department of Neurology, Rigshospitalet Glostrup, Glostrup, Denmark
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark
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Ru Z, Zhang H, Huang X, Lou J, Liao J, Chen Z, Yang X. A new pattern of citrullinated peptides improves the sensitivity for diagnosing rheumatoid arthritis. Clin Biochem 2022; 105-106:87-93. [DOI: 10.1016/j.clinbiochem.2022.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 03/29/2022] [Accepted: 04/04/2022] [Indexed: 11/03/2022]
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Reactivity of Rheumatoid Arthritis-Associated Citrulline-Dependent Antibodies to Epstein-Barr Virus Nuclear Antigen1-3. Antibodies (Basel) 2022; 11:antib11010020. [PMID: 35323194 PMCID: PMC8944695 DOI: 10.3390/antib11010020] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 02/17/2022] [Accepted: 03/08/2022] [Indexed: 12/22/2022] Open
Abstract
Rheumatoid arthritis (RA) is a chronic disease which causes joint inflammation and, ultimately, erosion of the underlying bone. Diagnosis of RA is based on the presence of biomarkers, such as anti-citrullinated protein antibodies (ACPA) and rheumatoid factors, along with clinical symptoms. Much evidence points to a link between the Epstein-Barr virus and RA. In this study, we analyzed ACPA reactivity to citrullinated peptides originating from Epstein-Barr nuclear antigens (EBNA1, EBNA2, and EBNA3) in order to elaborate the diagnostic potential of citrullinated EBNA peptides. Moreover, ACPA cross-reactivity to citrullinated peptides from myelin basic protein (MBP) was analyzed, as citrullinated MBP recently was described to be associated with multiple sclerosis, and some degree of sequence homology between MBP and citrullinated EBNA exists. A peptide from EBNA2, (EBNA2-A, GQGRGRWRG-Cit-GSKGRGRMH) reacted with approximately 70% of all RA sera, whereas only limited reactivity was detected to EBNA1 and EBNA3 peptides. Moreover, screening of ACPA reactivity to hybrid peptides of EBNA3-A (EPDSRDQQS-Cit-GQRRGDENRG) and EBNA2-A and peptides containing citrulline close to the N-terminal confirmed that ACPA sera contain different populations of ACPAs. No notable ACPA reactivity to MBP peptides was found, confirming that ACPAs are specific for RA, and that other factors than the presence of a central Cit-Gly motif are crucial for antibody binding. Collectively, these findings illustrate that citrullinated EBNA2 is an optimal candidate for ACPA detection, supporting current evidence that EBV is linked to RA onset.
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Trejo-Zambrano MI, Gómez-Bañuelos E, Andrade F. Redox-Mediated Carbamylation As a Hapten Model Applied to the Origin of Antibodies to Modified Proteins in Rheumatoid Arthritis. Antioxid Redox Signal 2022; 36:389-409. [PMID: 33906423 PMCID: PMC8982126 DOI: 10.1089/ars.2021.0064] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 04/16/2021] [Indexed: 12/23/2022]
Abstract
Significance: The production of antibodies to posttranslationally modified antigens is a hallmark in rheumatoid arthritis (RA). In particular, the presence of citrullination-associated antibodies, targeting both citrullinating enzymes (the peptidylarginine deiminases [PADs]) and citrullinated antigens (anticitrullinated protein antibodies [ACPAs]), has suggested that dysregulated citrullination is relevant for disease pathogenesis. Antibodies to other protein modifications with physicochemical similarities to citrulline, such as carbamylated-lysine and acetylated-lysine, have also gained interest in RA, but their mechanistic relation to ACPAs remains unclear. Recent Advances: Recent studies using RA-derived monoclonal antibodies have found that ACPAs are cross-reactive to carbamylated and acetylated peptides, challenging our understanding of the implications of such cross-reactivity. Critical Issues: Analogous to the classic antibody response to chemically modified proteins, we examine the possibility that antibodies to modified proteins in RA are more likely to resemble antihapten antibodies rather than autoantibodies. This potential shift in the autoantibody paradigm in RA offers the opportunity to explore new mechanisms involved in the origin and cross-reactivity of pathogenic antibodies in RA. In contrast to citrullination, carbamylation is a chemical modification associated with oxidative stress, it is highly immunogenic, and is considered in the group of posttranslational modification-derived products. We discuss the possibility that carbamylated proteins are antigenic drivers of cross-reacting antihapten antibodies that further create the ACPA response, and that ACPAs may direct the production of antibodies to PAD enzymes. Future Directions: Understanding the complexity of autoantibodies in RA is critical to develop tools to clearly define their origin, identify drivers of disease propagation, and develop novel therapeutics. Antioxid. Redox Signal. 36, 389-409.
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Affiliation(s)
| | - Eduardo Gómez-Bañuelos
- Division of Rheumatology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Felipe Andrade
- Division of Rheumatology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Specificity of Anti-Citrullinated Protein Antibodies to Citrullinated α-Enolase Peptides as a Function of Epitope Structure and Composition. Antibodies (Basel) 2021; 10:antib10030027. [PMID: 34449533 PMCID: PMC8395424 DOI: 10.3390/antib10030027] [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: 05/22/2021] [Revised: 06/28/2021] [Accepted: 07/14/2021] [Indexed: 11/16/2022] Open
Abstract
Rheumatoid arthritis (RA) is an autoimmune disease affecting approximately 1-2% of the world population. In addition to the first discovered serologic markers for RA, the rheumatoid factors (RFs), anti-citrullinated protein antibodies (ACPAs) are even more specific for the disease compared to RFs and are found in 70-80% of RA patient sera. RA etiopathogenesis still needs to be elucidated, as different factors are proposed to be involved, such as Epstein-Barr virus infection. Hence, understanding the interaction between ACPAs and their citrullinated peptide targets is relevant for a better knowledge of RA pathophysiology and for diagnostic purposes. In this study, a cohort of RA sera, healthy control sera and multiple sclerosis sera were screened for reactivity to a variety of citrullinated peptides originating from α-enolase, pro-filaggrin, proteoglycan and Epstein-Barr nuclear antigen-2 by enzyme-linked immunosorbent assay. ACPA reactivity to citrullinated α-enolase peptides was found to depend on peptide length and peptide conformation, favouring cyclic (disulfide bond) conformations for long peptides and linear peptides for truncated ones. Additional investigations about the optimal peptide conformation for ACPA detection, employing pro-filaggrin and EBNA-2 peptides, confirmed these findings, indicating a positive effect of cyclization of longer peptides of approximately 20 amino acids. Moreover, screening of the citrullinated peptides confirmed that ACPAs can be divided into two groups based on their reactivity. Approximately 90% of RA sera recognize several peptide targets, being defined as cross-reactive or overlapping reactivities, and whose reactivity to the citrullinated peptide is considered primarily to be backbone-dependent. In contrast, approximately 10% recognize a single target and are defined as nonoverlapping, primarily depending on the specific amino acid side-chains in the epitope for a stable interaction. Collectively, this study contributed to characterize epitope composition and structure for optimal ACPA reactivity and to obtain further knowledge about the cross-reactive nature of ACPAs.
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Sahlström P, Hansson M, Steen J, Amara K, Titcombe PJ, Forsström B, Stålesen R, Israelsson L, Piccoli L, Lundberg K, Klareskog L, Mueller DL, Catrina AI, Skriner K, Malmström V, Grönwall C. Different Hierarchies of Anti–Modified Protein Autoantibody Reactivities in Rheumatoid Arthritis. Arthritis Rheumatol 2020; 72:1643-1657. [DOI: 10.1002/art.41385] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Accepted: 05/13/2020] [Indexed: 12/26/2022]
Affiliation(s)
- Peter Sahlström
- Karolinska Institutet Karolinska University Hospital, Stockholm, Sweden, and Charité Universitätsmedizin Berlin Germany
| | - Monika Hansson
- Karolinska Institutet Karolinska University Hospital Stockholm Sweden
| | - Johanna Steen
- Karolinska Institutet Karolinska University Hospital Stockholm Sweden
| | - Khaled Amara
- Karolinska Institutet Karolinska University Hospital Stockholm Sweden
| | - Philip J. Titcombe
- Karolinska Institutet Karolinska University Hospital, Stockholm, Sweden, and University of Minnesota Medical School Minneapolis
| | | | - Ragnhild Stålesen
- Karolinska Institutet Karolinska University Hospital Stockholm Sweden
| | - Lena Israelsson
- Karolinska Institutet Karolinska University Hospital Stockholm Sweden
| | - Luca Piccoli
- Institute for Research in Biomedicine Università della Svizzera italiana Bellinzona Switzerland
| | - Karin Lundberg
- Karolinska Institutet Karolinska University Hospital Stockholm Sweden
| | - Lars Klareskog
- Karolinska Institutet Karolinska University Hospital Stockholm Sweden
| | | | - Anca I. Catrina
- Karolinska Institutet Karolinska University Hospital Stockholm Sweden
| | | | | | - Caroline Grönwall
- Karolinska Institutet Karolinska University Hospital Stockholm Sweden
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Liang B, Ge C, Lönnblom E, Lin X, Feng H, Xiao L, Bai J, Ayoglu B, Nilsson P, Nandakumar KS, Zhao M, Holmdahl R. The autoantibody response to cyclic citrullinated collagen type II peptides in rheumatoid arthritis. Rheumatology (Oxford) 2020; 58:1623-1633. [PMID: 30892636 DOI: 10.1093/rheumatology/kez073] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 01/09/2019] [Indexed: 12/14/2022] Open
Abstract
OBJECTIVES The detection of anti-citrullinated peptide antibodies (ACPAs) is a serological hallmark of RA. Autoantibodies reactive with collagen type II (CII) are present in RA sera and synovial fluid and are potentially pathogenic. Here, we investigate the prevalence and specificity of the autoantibody responses to defined citrullinated cyclic peptides derived from CII in a China RA cohort. METHODS Using bead-based multiplex assay, we examined the presence of autoantibodies binding to 54 cyclic 17-mer citrullinated CII peptides, encompassing all citrullinate epitopes in CII, and the corresponding unmodified peptides in 415 RA patients, in addition to 304 patients with OA. Furthermore, the autoantibody responses to a selected set of 10 cyclic citrullinated peptides were also examined in 203 healthy individuals. RESULTS Autoantibody responses to cyclic citrullinated CII peptides were higher in RA patients as compared with OA patients or healthy individuals, whereas little or negligible antibody responses to cyclic unmodified CII peptides were observed. Interestingly, several novel citrullinated CII epitopes were identified. Antibodies to these novel citrullinated CII epitopes showed not only substantial overlapping reactivities but also had unique specificities. CONCLUSION We found a high prevalence of autoantibodies against cyclic citrullinated CII in the sera of patients in a China RA cohort. The present study revealed heterogeneous binding patterns against novel citrullinated CII epitopes, which may help to stratify RA patients into different subgroups.
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Affiliation(s)
- Bibo Liang
- Department of Pathophysiology, Key Lab for Shock and Microcirculation Research of Guangdong, Southern Medical University, Guangzhou, China
- Department of Medical Biochemistry and Biophysics, Section for Medical Inflammation Research, Karolinska Institutet, Stockholm, Sweden
| | - Changrong Ge
- Department of Medical Biochemistry and Biophysics, Section for Medical Inflammation Research, Karolinska Institutet, Stockholm, Sweden
| | - Erik Lönnblom
- Department of Medical Biochemistry and Biophysics, Section for Medical Inflammation Research, Karolinska Institutet, Stockholm, Sweden
| | - Xiaoyin Lin
- Center for Medical Immunopharmacology Research, Southern Medical University, Guangzhou
| | - Hui Feng
- Guanghua Integrative Medicine Hospital, Changning District, Shanghai
| | - Lianbo Xiao
- Guanghua Integrative Medicine Hospital, Changning District, Shanghai
| | - Jing'an Bai
- Institute of Basic Research in Clinical Medicine, China Academy of Chinese Medical Sciences, Beijing, China
| | - Burcu Ayoglu
- Affinity Proteomics, SciLifeLab, School of Biotechnology, KTH-Royal Institute of Technology, Stockholm, Sweden
| | - Peter Nilsson
- Affinity Proteomics, SciLifeLab, School of Biotechnology, KTH-Royal Institute of Technology, Stockholm, Sweden
| | - Kutty Selva Nandakumar
- Department of Medical Biochemistry and Biophysics, Section for Medical Inflammation Research, Karolinska Institutet, Stockholm, Sweden
- Center for Medical Immunopharmacology Research, Southern Medical University, Guangzhou
| | - Ming Zhao
- Department of Pathophysiology, Key Lab for Shock and Microcirculation Research of Guangdong, Southern Medical University, Guangzhou, China
| | - Rikard Holmdahl
- Department of Medical Biochemistry and Biophysics, Section for Medical Inflammation Research, Karolinska Institutet, Stockholm, Sweden
- Center for Medical Immunopharmacology Research, Southern Medical University, Guangzhou
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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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Trier NH, Holm BE, Hansen PR, Slot O, Locht H, Houen G. Specificity of Anti-Citrullinated Protein Antibodies in Rheumatoid Arthritis. Antibodies (Basel) 2019; 8:antib8020037. [PMID: 31544843 PMCID: PMC6640722 DOI: 10.3390/antib8020037] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 05/28/2019] [Accepted: 06/06/2019] [Indexed: 11/16/2022] Open
Abstract
Rheumatoid arthritis (RA) is an autoimmune disease of unknown etiology. The majority of individuals with RA are positive for the disease-specific anti-citrullinated protein antibodies (ACPAs). These antibodies are primarily of cross-reactive nature, hence, the true autoantigen to ACPA remains unidentified. In this study, we analyzed the reactivity of RA sera to several post-translationally modified epitopes, in order to further characterize the specific nature of ACPAs by immunoassays. Substituting citrulline with other amino acids, e.g., D-citrulline, homo-citrulline and methyl-arginine illustrated that ACPAs are utmost specific for citrullinated targets. Collectively, these findings support that ACPAs and citrullinated targets are specific for RA, making citrulline-containing peptide targets the most effective assays for detection of ACPAs.
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Affiliation(s)
- Nicole H Trier
- Department of Biomarkers and Autoimmunity, Statens Serum Institut, Artillerivej 5, 2300 Copenhagen S, Denmark.
| | - Bettina E Holm
- Department of Clinical Immunology, Rigshospitalet, Ole Maaløes vej 26, 2200 Copenhagen N, Denmark.
| | - Paul R Hansen
- Department of Drug Design and Pharmacology, Universitetsparken 2, 2100 Copenhagen Ø, Denmark.
| | - Ole Slot
- Department of Rheumatology, Rigshospitalet Glostrup, Nordre Ringvej 57, 2600 Glostrup, Denmark.
| | - Henning Locht
- Department of Rheumatology, Frederiksberg Hospital, Nordre Fasanvej 57, 2000 Frederiksberg, Denmark.
| | - Gunnar Houen
- Department of Biomarkers and Autoimmunity, Statens Serum Institut, Artillerivej 5, 2300 Copenhagen S, Denmark.
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Use of a Citrullinated Peptide Panel for Detection of Anti-Citrullinated Protein Antibodies by Enzyme-Linked Immunosorbent Assay. Methods Mol Biol 2019; 1901:243-253. [PMID: 30539584 DOI: 10.1007/978-1-4939-8949-2_21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2023]
Abstract
Anti-citrullinated protein antibodies (ACPA)s are a hallmark of rheumatoid arthritis (RA) and are essential for serological diagnosis of RA.ACPAs are not specific for a single citrullinated target; in fact, several citrullinated ACPA target proteins have been described. As a consequence, ACPAs are primarily detected by enzyme-linked immunosorbent assays, where several citrullinated peptides are used as target antigens.This chapter focuses on the detection of ACPAs using a recently developed peptide panel in enzyme-linked immunosorbent assays.
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12
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Ge C, Xu B, Liang B, Lönnblom E, Lundström SL, Zubarev RA, Ayoglu B, Nilsson P, Skogh T, Kastbom A, Malmström V, Klareskog L, Toes REM, Rispens T, Dobritzsch D, Holmdahl R. Structural Basis of Cross-Reactivity of Anti-Citrullinated Protein Antibodies. Arthritis Rheumatol 2019; 71:210-221. [PMID: 30152126 DOI: 10.1002/art.40698] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 08/23/2018] [Indexed: 01/12/2023]
Abstract
OBJECTIVE Anti-citrullinated protein antibodies (ACPAs) develop many years before the clinical onset of rheumatoid arthritis (RA). This study was undertaken to address the molecular basis of the specificity and cross-reactivity of ACPAs from patients with RA. METHODS Antibodies isolated from RA patients were expressed as monoclonal chimeric antibodies with mouse Fc. These antibodies were characterized for glycosylation using mass spectrometry, and their cross-reactivity was assessed using Biacore and Luminex immunoassays. The crystal structures of the antigen-binding fragment (Fab) of the monoclonal ACPA E4 in complex with 3 different citrullinated peptides were determined using x-ray crystallography. The prevalence of autoantibodies reactive against 3 of the citrullinated peptides that also interacted with E4 was investigated by Luminex immunoassay in 2 Swedish cohorts of RA patients. RESULTS Analysis of the crystal structures of a monoclonal ACPA from human RA serum in complex with citrullinated peptides revealed key residues of several complementarity-determining regions that recognized the citrulline as well as the neighboring peptide backbone, but with limited contact with the side chains of the peptides. The same citrullinated peptides were recognized by high titers of serum autoantibodies in 2 large cohorts of RA patients. CONCLUSION These data show, for the first time, how ACPAs derived from human RA serum recognize citrulline. The specific citrulline recognition and backbone-mediated interactions provide a structural explanation for the promiscuous recognition of citrullinated peptides by RA-specific ACPAs.
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Affiliation(s)
| | - Bingze Xu
- Karolinska Institutet, Stockholm, Sweden
| | - Bibo Liang
- Karolinska Institutet, Stockholm, Sweden, and Southern Medical University, Guangzhou, China
| | | | | | | | - Burcu Ayoglu
- KTH Royal Institute of Technology, Stockholm, Sweden
| | - Peter Nilsson
- KTH Royal Institute of Technology, Stockholm, Sweden
| | | | | | - Vivianne Malmström
- Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
| | - Lars Klareskog
- Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
| | - René E M Toes
- Leiden University Medical Center, Leiden, The Netherlands
| | - Theo Rispens
- University of Amsterdam, Amsterdam, The Netherlands
| | | | - Rikard Holmdahl
- Karolinska Institutet, Stockholm, Sweden, and Southern Medical University, Guangzhou, China
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Diagnostic Value of Anti-Fibrinogen Citrullinated Peptide in Rheumatoid Arthritis. ACTA ACUST UNITED AC 2018; 16:455-461. [PMID: 30594439 DOI: 10.1016/j.reuma.2018.11.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 10/18/2018] [Accepted: 11/06/2018] [Indexed: 12/20/2022]
Abstract
OBJECTIVE To determinate the diagnostic value of an antibody against a citrullinated fibrinogen peptide in Cuban patients with rheumatoid arthritis, using an enzyme immunasay. MATERIALS AND METHODS A citrullinated peptide of fibrinogen designed by informatics prediction was synthesized and used in an enzyme immunoassay. The participants were 81 patients with early disease, 81 patients with established disease, 58 patients with other rheumatic and inflammatory diseases, and 43 healthy individuals. Anti- citrullinated fibrinogen peptide, anti-mutated citrullinated vimentin, anti second generation citrullinated peptides and rheumatoid factor antibodies were determined by enzyme-linked immunosorbent assay. RESULTS Determination of anti-citrullinated peptide of fibrinogen antibodies by the designed enzyme immunoassay showed the best diagnostic value in early rheumatoid arthritis patients, with the highest value sensitivity (84%), negative predictive value (85%), Youden index (0.73%) and area under the receiver operating curve (0.9192). Specificity (89%) and positive predictive value (88%) were higher than rheumatoid factor, similar to anti- mutated citrullinated vimentin, but lower than second generation anti-citrullinated peptides assay. The positivity of C-reactive protein was associated with the presence of anti- citrullinated fibrinogen peptide antibodies and the titres of these antibodies correlated with clinical activity in early disease. CONCLUSIONS The immunoassay designed with a citrullinated fibrinogen peptide has a high diagnostic value and can identify patients with greater clinical activity in early rheumatoid arthritis.
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Trier NH, Holm BE, Heiden J, Slot O, Locht H, Jensen B, Lindegaard H, Svendsen A, Nielsen CT, Jacobsen S, Theander E, Houen G. The use of synthetic peptides for detection of anti-citrullinated protein antibodies in rheumatoid arthritis. J Immunol Methods 2018; 454:6-14. [DOI: 10.1016/j.jim.2017.11.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 09/28/2017] [Accepted: 11/06/2017] [Indexed: 11/29/2022]
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15
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Trier NH, Holm BE, Heiden J, Slot O, Locht H, Lindegaard H, Svendsen A, Nielsen CT, Jacobsen S, Theander E, Houen G. Antibodies to a strain-specific citrullinated Epstein-Barr virus peptide diagnoses rheumatoid arthritis. Sci Rep 2018; 8:3684. [PMID: 29487382 PMCID: PMC5829227 DOI: 10.1038/s41598-018-22058-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 02/09/2018] [Indexed: 12/13/2022] Open
Abstract
Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease. Anti-citrullinated protein antibodies (ACPA) are crucial for the serological diagnosis of RA, where Epstein-Barr virus (EBV) has been suggested to be an environmental agent in triggering the onset of the disease. This study aimed to analyse antibody reactivity to citrullinated EBV nuclear antigen-2 (EBNA-2) peptides from three different EBV strains (B95-8, GD1 and AG876) using streptavidin capture enzyme-linked immunosorbent assay. One peptide, only found in a single strain (AG876), obtained a sensitivity and specificity of 77% and 95%, respectively and showed high sequence similarity to the filaggrin peptide originally used for ACPA detection. Comparison of antibody reactivity to commercial assays found that the citrullinated peptide was as effective in detecting ACPA as highly sensitive and specific commercial assays. The data presented demonstrate that the citrullinated EBNA-2 peptide indeed is recognised specifically by RA sera and that the single peptide is able to compete with assays containing multiple peptides. Furthermore, it could be hypothesized that RA may be caused by (a) specific strain(s) of EBV.
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Affiliation(s)
- Nicole Hartwig Trier
- Department of Autoimmunology and Biomarkers, Statens Serum Institut, Artillerivej 5, 2300, Copenhagen S, Denmark.
| | - Bettina Eide Holm
- Department of Autoimmunology and Biomarkers, Statens Serum Institut, Artillerivej 5, 2300, Copenhagen S, Denmark
| | - Julie Heiden
- Department of Autoimmunology and Biomarkers, Statens Serum Institut, Artillerivej 5, 2300, Copenhagen S, Denmark
| | - Ole Slot
- Department of Rheumatology, Glostrup Hospital, Nordre Ringvej 57, 2600, Glostrup, Denmark
| | - Henning Locht
- Department of Rheumatology, Frederiksberg Hospital, Nordre Fasanvej 57, 2000, Frederiksberg, Denmark
| | - Hanne Lindegaard
- Department of Rheumatology, Odense University Hospital, Søndre Boulevard 29, 5000, Odense C, Denmark
| | - Anders Svendsen
- Epidemiology, Biostatistics and Bio-demography, Institute of Public Health, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark
| | - Christoffer Tandrup Nielsen
- Copenhagen Lupus and Vasculitis Clinic, Center for Rheumatology and Spine Diseases, Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark
| | - Søren Jacobsen
- Copenhagen Lupus and Vasculitis Clinic, Center for Rheumatology and Spine Diseases, Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark
| | - Elke Theander
- Department of Rheumatology, Skåne University Hospital, Lund University, 20502, Malmö, Sweden
| | - Gunnar Houen
- Department of Autoimmunology and Biomarkers, Statens Serum Institut, Artillerivej 5, 2300, Copenhagen S, Denmark.
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Szarka E, Aradi P, Huber K, Pozsgay J, Végh L, Magyar A, Gyulai G, Nagy G, Rojkovich B, Kiss É, Hudecz F, Sármay G. Affinity Purification and Comparative Biosensor Analysis of Citrulline-Peptide-Specific Antibodies in Rheumatoid Arthritis. Int J Mol Sci 2018; 19:ijms19010326. [PMID: 29361749 PMCID: PMC5796268 DOI: 10.3390/ijms19010326] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Revised: 01/15/2018] [Accepted: 01/17/2018] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND In rheumatoid arthritis (RA), anti-citrullinated protein/peptide antibodies (ACPAs) are responsible for disease onset and progression, however, our knowledge is limited on ligand binding affinities of autoantibodies with different citrulline-peptide specificity. METHODS Citrulline-peptide-specific ACPA IgGs were affinity purified and tested by ELISA. Binding affinities of ACPA IgGs and serum antibodies were compared by surface plasmon resonance (SPR) analysis. Bifunctional nanoparticles harboring a multi-epitope citrulline-peptide and a complement-activating peptide were used to induce selective depletion of ACPA-producing B cells. RESULTS KD values of affinity-purified ACPA IgGs varied between 10-6 and 10-8 M and inversely correlated with disease activity. Based on their cross-reaction with citrulline-peptides, we designed a novel multi-epitope peptide, containing Cit-Gly and Ala-Cit motifs in two-two copies, separated with a short, neutral spacer. This peptide detected antibodies in RA sera with 66% sensitivity and 98% specificity in ELISA and was recognized by 90% of RA sera, while none of the healthy samples in SPR. When coupled to nanoparticles, the multi-epitope peptide specifically targeted and depleted ACPA-producing B cells ex vivo. CONCLUSIONS The unique multi-epitope peptide designed based on ACPA cross-reactivity might be suitable to develop better diagnostics and novel therapies for RA.
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Affiliation(s)
- Eszter Szarka
- Department of Immunology, Eötvös Loránd University, 1117 Budapest, Hungary; (E.S.); (P.A.); (K.H.); (J.P.); (L.V.)
| | - Petra Aradi
- Department of Immunology, Eötvös Loránd University, 1117 Budapest, Hungary; (E.S.); (P.A.); (K.H.); (J.P.); (L.V.)
| | - Krisztina Huber
- Department of Immunology, Eötvös Loránd University, 1117 Budapest, Hungary; (E.S.); (P.A.); (K.H.); (J.P.); (L.V.)
| | - Judit Pozsgay
- Department of Immunology, Eötvös Loránd University, 1117 Budapest, Hungary; (E.S.); (P.A.); (K.H.); (J.P.); (L.V.)
| | - Lili Végh
- Department of Immunology, Eötvös Loránd University, 1117 Budapest, Hungary; (E.S.); (P.A.); (K.H.); (J.P.); (L.V.)
| | - Anna Magyar
- MTA-ELTE Research Group of Peptide Chemistry, Hungarian Academy of Science, Eötvös Loránd University, 1117 Budapest, Hungary; (A.M.); (F.H.)
| | - Gergő Gyulai
- Laboratory of Interfaces and Nanostructures, Institute of Chemistry, Eötvös Loránd University, 1117 Budapest, Hungary; (G.G.); (É.K.)
| | - György Nagy
- Department of Rheumatology, 3rd Department of Internal Medicine, Semmelweis University, 1125 Budapest, Hungary;
- Rheumatology, Buda Hospital of the Hospitaller Order of St. John of God, 1023 Budapest, Hungary;
| | - Bernadette Rojkovich
- Rheumatology, Buda Hospital of the Hospitaller Order of St. John of God, 1023 Budapest, Hungary;
| | - Éva Kiss
- Laboratory of Interfaces and Nanostructures, Institute of Chemistry, Eötvös Loránd University, 1117 Budapest, Hungary; (G.G.); (É.K.)
| | - Ferenc Hudecz
- MTA-ELTE Research Group of Peptide Chemistry, Hungarian Academy of Science, Eötvös Loránd University, 1117 Budapest, Hungary; (A.M.); (F.H.)
| | - Gabriella Sármay
- Department of Immunology, Eötvös Loránd University, 1117 Budapest, Hungary; (E.S.); (P.A.); (K.H.); (J.P.); (L.V.)
- Correspondence: ; Tel.: +36-1-372-2500 (ext. 8662)
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17
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Epitope Specificity of Anti-Citrullinated Protein Antibodies. Antibodies (Basel) 2017; 6:antib6010005. [PMID: 31548521 PMCID: PMC6698845 DOI: 10.3390/antib6010005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 02/06/2017] [Accepted: 02/22/2017] [Indexed: 01/21/2023] Open
Abstract
Anti-citrullinated protein antibodies are primarily associated with a progressive course in the autoimmune disease rheumatoid arthritis, a disease with a chronic and inflammatory nature. These antibodies do not appear to have any strict dependency for reactivity except from the presence of the non-genetically encoded amino acid citrulline, which is the result of a posttranslational modification, catalyzed by calcium-dependent peptidylarginine deiminase enzymes. Nevertheless, several amino acids surrounding the citrulline residue notably influence antibody reactivity, especially with a central-Cit-Gly-motif being essential for antibody reactivity. Most importantly, these antibodies have been proposed to be divided into two groups, based on their ability to recognize multiple citrullinated peptides. Thus, an "overlapping" antibody group, which appears to recognize several citrullinated peptides, and a "non-overlapping" antibody group, which only recognizes a limited number of citrullinated peptides, have been proposed. Based on these findings, we suggest that antibodies recognizing several citrullinated targets, also referred to as cross-reactive antibodies, primarily are backbone-dependent, whereas less cross-reactive antibodies primarily depend on the side chains of the amino acids comprising the epitopes for stable antibody-antigen interactions, which reduces the degree of cross-reactivity significantly. Clarifying the reactivity pattern of anti-citrullinated protein antibodies may contribute to determining their true nature of origin.
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