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Rebak AS, Hendriks IA, Elsborg JD, Buch-Larsen SC, Nielsen CH, Terslev L, Kirsch R, Damgaard D, Doncheva NT, Lennartsson C, Rykær M, Jensen LJ, Christophorou MA, Nielsen ML. A quantitative and site-specific atlas of the citrullinome reveals widespread existence of citrullination and insights into PADI4 substrates. Nat Struct Mol Biol 2024; 31:977-995. [PMID: 38321148 PMCID: PMC11189309 DOI: 10.1038/s41594-024-01214-9] [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: 12/22/2022] [Accepted: 01/04/2024] [Indexed: 02/08/2024]
Abstract
Despite the importance of citrullination in physiology and disease, global identification of citrullinated proteins, and the precise targeted sites, has remained challenging. Here we employed quantitative-mass-spectrometry-based proteomics to generate a comprehensive atlas of citrullination sites within the HL60 leukemia cell line following differentiation into neutrophil-like cells. We identified 14,056 citrullination sites within 4,008 proteins and quantified their regulation upon inhibition of the citrullinating enzyme PADI4. With this resource, we provide quantitative and site-specific information on thousands of PADI4 substrates, including signature histone marks and transcriptional regulators. Additionally, using peptide microarrays, we demonstrate the potential clinical relevance of certain identified sites, through distinct reactivities of antibodies contained in synovial fluid from anti-CCP-positive and anti-CCP-negative people with rheumatoid arthritis. Collectively, we describe the human citrullinome at a systems-wide level, provide a resource for understanding citrullination at the mechanistic level and link the identified targeted sites to rheumatoid arthritis.
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Affiliation(s)
- Alexandra S Rebak
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ivo A Hendriks
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jonas D Elsborg
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sara C Buch-Larsen
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Claus H Nielsen
- Institute for Inflammation Research, Center for Rheumatology and Spine Diseases, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Lene Terslev
- Copenhagen Center for Arthritis Research, Center for Rheumatology and Spine Diseases, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Rebecca Kirsch
- Disease Systems Biology Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Dres Damgaard
- Institute for Inflammation Research, Center for Rheumatology and Spine Diseases, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Nadezhda T Doncheva
- Disease Systems Biology Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Caroline Lennartsson
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Martin Rykær
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lars J Jensen
- Disease Systems Biology Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Michael L Nielsen
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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2
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Houen G. Peptide Antibodies: Current Status. Methods Mol Biol 2024; 2821:1-8. [PMID: 38997476 DOI: 10.1007/978-1-0716-3914-6_1] [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] [Indexed: 07/14/2024]
Abstract
Peptide antibodies have become one of the most important classes of reagents in molecular biology and clinical diagnostics. For this reason, methods for their production and characterization continue to be developed, including basic peptide synthesis protocols, peptide-conjugate production and characterization, conformationally restricted peptides, immunization procedures, etc. Detailed mapping of peptide antibody epitopes has yielded important information on antibody-antigen interaction in general and specifically in relation to antibody cross-reactivity and theories of molecular mimicry. This information is essential for detailed understanding of paratope-epitope dynamics, design of antibodies for research, design of peptide-based vaccines, development of therapeutic peptide antibodies, and de novo design of antibodies with predetermined specificity.
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Affiliation(s)
- Gunnar Houen
- Department of Neurology and Translational Research Center, Rigshospitalet, Glostrup, Denmark.
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3
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Batsalova T, Teneva I, Bardarov K, Moten D, Dzhambazov B. Anticitrullinated antibodies recognize rheumatoid arthritis associated T-cell epitopes modified by bacterial L-asparaginase. Cent Eur J Immunol 2023; 48:174-188. [PMID: 37901867 PMCID: PMC10604640 DOI: 10.5114/ceji.2023.131455] [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: 03/08/2023] [Accepted: 07/07/2023] [Indexed: 10/31/2023] Open
Abstract
Citrullinated proteins and anti-citrullinated protein antibodies (ACPAs) play an important role in the pathogenesis of rheumatoid arthritis (RA). It has been suggested that during inflammation or dysbiosis, bacteria could initiate production of ACPAs. Most patients with RA are seropositive for ACPAs, but these antibodies have overlapping reactivity to different posttranslational modifications (PTMs). For initiation and development of RA, T lymphocytes and T cell epitopes are still required. In this study, we evaluated the ability of bacterial L-asparaginase to modify RA-related T cell epitopes within type II collagen (CII259-273 and CII311-325), as well as whether these modified epitopes are recognized by ACPAs from RA patients. We included 12 patients with early RA and 11 healthy subjects selected according to predefined specific criteria. LC-MS/MS analyses revealed that the bacterial L-asparaginase can modify investigated T cell epitopes. ELISA tests showed cross-reactivity of ACPA positive sera from early RA patients towards the enzymatically modified immunodominant T cell epitopes within type II collagen (CII), but not to the modified irrelevant peptides. These data suggest that the cross-reactive ACPAs recognize the "carbonyl-Gly-Pro" motif in CII. Moreover, the T cell recognition of the modified major immunodominant T cell epitope Gal264-CII259-273 was not affected. This epitope was still able to activate autoreactive T cells from early RA patients. It is likely that such modifications are the missing link between the T cell priming and the development of anti-modified protein antibodies (AMPAs). Our results provide additional information on the etiology and pathogenesis of RA.
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Affiliation(s)
| | - Ivanka Teneva
- Faculty of Biology, Paisii Hilendarski University of Plovdiv, Plovdiv, Bulgaria
| | | | - Dzhemal Moten
- Faculty of Biology, Paisii Hilendarski University of Plovdiv, Plovdiv, Bulgaria
| | - Balik Dzhambazov
- Faculty of Biology, Paisii Hilendarski University of Plovdiv, Plovdiv, Bulgaria
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4
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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: 1] [Impact Index Per Article: 1.0] [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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5
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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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Bergmann AC, Houen G, Trier NH. Determination of crucial epitopes in the sperm protein calsperin employing synthetic peptides and monoclonal antibodies. J Pept Sci 2023; 29:e3450. [PMID: 36082776 PMCID: PMC10078156 DOI: 10.1002/psc.3450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 09/05/2022] [Accepted: 09/06/2022] [Indexed: 01/12/2023]
Abstract
The chaperone protein calsperin is exclusively expressed in the testes and is essential for sperm migration from the uterus into the oviduct. During spermatogenesis, calsperin interacts with ADAM3, a spermatozoon membrane protein required for fertilization. In this study, we characterized a calsperin epitope by using two monoclonal antibodies and resin-bound calsperin peptides, which were tested for reactivity using a modified enzyme-linked immunosorbent assay. An epitope located at the C-terminal end of calsperin corresponding to amino acids 228 WEKHFLDAS237 was identified. Three hot spot amino acids were essential for antibody binding whereas the remaining amino acids in the identified epitope appeared to be essential for bringing the critical contact residues into an α-helix structure. No notable sequence similarity was determined between the identified calsperin epitope and calreticulin, a chaperone homologue with sequence similarity, indicating that the identified epitope was specific for calsperin. Characterization of the calsperin epitope and of the two antibodies tested may be used in assays for further characterization of calsperin, where knowledge about the binding sites is necessary, for example, in sandwich assays. Moreover, studies like these may be used to study the function of calsperin during spermatogenesis and fertilization in detail and to develop new male contraception methods by targeting calsperin and mediating neutralization of its function.
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Affiliation(s)
- Ann Christina Bergmann
- Department of Autoimmunology and Biomarkers, Statens Serum Institute, Copenhagen, Denmark
| | - Gunnar Houen
- Department of Neurology, Rigshospitalet Glostrup, Glostrup, Denmark.,Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
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7
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Trier NH, Valdarnini N, Fanelli I, Rovero P, Hansen PR, Schafer-Nielsen C, Ciplys E, Slibinskas R, Pociot F, Friis T, Houen G. Peptide Antibody Reactivity to Homologous Regions in Glutamate Decarboxylase Isoforms and Coxsackievirus B4 P2C. Int J Mol Sci 2022; 23:ijms23084424. [PMID: 35457242 PMCID: PMC9028130 DOI: 10.3390/ijms23084424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 04/10/2022] [Accepted: 04/14/2022] [Indexed: 12/04/2022] Open
Abstract
Two isoforms of the glutamate decarboxylase (GAD) enzyme exist, GAD65 and GAD67, which are associated with type 1 diabetes (T1D) and stiff-person syndrome (SPS), respectively. Interestingly, it has been reported that T1D patients seldom develop SPS, whereas patients with SPS occasionally develop T1D. In addition, coxsackievirus B4 (CVB4) has previously been proposed to be involved in the onset of T1D through molecular mimicry. On this basis, we aimed to examine antibody cross-reactivity between a specific region of GAD65 and GAD67, which has high sequence homology to the nonstructural P2C protein of CVB4 to determine potential correlations at antibody level. Monoclonal peptide antibodies generated in mice specific for a region with high similarity in all three proteins were screened for reactivity along with human sera in immunoassays. In total, six antibodies were generated. Two of the antibodies reacted to both GAD isoforms. However, none of the antibodies were cross-reactive to CVB, suggesting that antibody cross-reactivity between GAD65 and CVB, and GAD67 and CVB may not contribute to the onset of T1D and SPS, respectively.
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Affiliation(s)
- Nicole Hartwig Trier
- Department of Neurology, Rigshospitalet Glostrup, Valdemar Hansens vej 13, 2600 Glostrup, Denmark
- Correspondence: (N.H.T.); (G.H.)
| | - Niccolo Valdarnini
- Interdepartmental Laboratory of Peptide and Protein Chemistry and Biology, Department of NeuroFarBa, University of Florence, Via Ugo Schiff 6, I-50019 Sesto Fiorentino, Italy; (N.V.); (I.F.); (P.R.)
| | - Ilaria Fanelli
- Interdepartmental Laboratory of Peptide and Protein Chemistry and Biology, Department of NeuroFarBa, University of Florence, Via Ugo Schiff 6, I-50019 Sesto Fiorentino, Italy; (N.V.); (I.F.); (P.R.)
| | - Paolo Rovero
- Interdepartmental Laboratory of Peptide and Protein Chemistry and Biology, Department of NeuroFarBa, University of Florence, Via Ugo Schiff 6, I-50019 Sesto Fiorentino, Italy; (N.V.); (I.F.); (P.R.)
| | - Paul Robert Hansen
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark;
| | | | - Evaldas Ciplys
- Life Sciences Center, Institute of Biotechnology, Vilnius University, Saulėtekio al. 7, LT-10257 Vilnius, Lithuania; (E.C.); (R.S.)
| | - Rimantas Slibinskas
- Life Sciences Center, Institute of Biotechnology, Vilnius University, Saulėtekio al. 7, LT-10257 Vilnius, Lithuania; (E.C.); (R.S.)
| | - Flemming Pociot
- Steno Diabetes Center, Borgmester Ib Juuls Vej 83, 2730 Hellerup, Denmark;
| | - Tina Friis
- Department of Autoimmunity and Biomarkers, Statens Serum Institut, Artillerivej 5, 2300 Copenhagen, Denmark;
| | - Gunnar Houen
- Department of Neurology, Rigshospitalet Glostrup, Valdemar Hansens vej 13, 2600 Glostrup, Denmark
- Department Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark
- Correspondence: (N.H.T.); (G.H.)
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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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Hemon MF, Lambert NC, Arnoux F, Roudier J, Auger I. PAD4 Immunization Triggers Anti-Citrullinated Peptide Antibodies in Normal Mice: Analysis With Peptide Arrays. Front Immunol 2022; 13:840035. [PMID: 35432329 PMCID: PMC9008206 DOI: 10.3389/fimmu.2022.840035] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 03/04/2022] [Indexed: 11/13/2022] Open
Abstract
The critical immunological event in rheumatoid arthritis (RA) is the production of antibodies to citrullinated proteins (ACPAs), ie proteins on which arginines have been transformed into citrullines by peptidyl arginine deiminases (PAD). In C3H mice, immunization with PAD4 triggers the production of ACPAs. Here, we developed a peptide array to analyze the fine specificity of anti-citrullinated peptide antibodies and used it to characterize the ACPA response after hPAD4 immunization in mice expressing different H-2 haplotypes. Sera from C3H, DBA/2, BALB/c and C57BL/6 mice immunized with human PAD4 (hPAD4) or control-matched mice immunized with phosphate buffered saline (PBS) were used to screen peptide arrays containing 169 peptides from collagen, filaggrin, EBNA, proteoglycan, enolase, alpha and beta fibrinogen, histon and vimentin. Human PAD4 immunization induced antibodies directed against numerous citrullinated peptides from fibrinogen, histon 4 and vimentin. Most peptides were recognized under their arginine and citrullinated forms. DBA/2 and BALB/c mice (H-2d) had the lowest anti-citrullinated peptide IgG responses. C3H (H-2k) and BL6 mice (H-2b) had the highest anti-citrullinated peptide IgG responses. The newly developed peptide array allows us to characterize the ACPA production after hPAD4 immunization in mice on the H-2d, H-2k or H-2b backgrounds. This sensitive tool will be useful for further studies on mice for prevention of ACPA production by PAD tolerization.
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Affiliation(s)
- Marie F. Hemon
- Institut National de la Santé et de la Recherche Médicale (INSERM) Unité Mixte de Recherche (UMRs) 1097, Aix Marseille University, Marseille, France
- Arthritis R&D, Neuilly-sur-Seine, France
| | - Nathalie C. Lambert
- Institut National de la Santé et de la Recherche Médicale (INSERM) Unité Mixte de Recherche (UMRs) 1097, Aix Marseille University, Marseille, France
| | - Fanny Arnoux
- Institut National de la Santé et de la Recherche Médicale (INSERM) Unité Mixte de Recherche (UMRs) 1097, Aix Marseille University, Marseille, France
| | - Jean Roudier
- Institut National de la Santé et de la Recherche Médicale (INSERM) Unité Mixte de Recherche (UMRs) 1097, Aix Marseille University, Marseille, France
- Assistance Publique Hôpitaux de Marseille (APHM), Rhumatologie, Marseille, France
| | - Isabelle Auger
- Institut National de la Santé et de la Recherche Médicale (INSERM) Unité Mixte de Recherche (UMRs) 1097, Aix Marseille University, Marseille, France
- *Correspondence: Isabelle Auger,
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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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11
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Vakilian M. A review on the effect of prolyl isomerization on immune response aberration and hypersensitivity reactions: A unifying hypothesis. Clin Immunol 2021; 234:108896. [PMID: 34848356 DOI: 10.1016/j.clim.2021.108896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 11/19/2021] [Accepted: 11/21/2021] [Indexed: 12/01/2022]
Abstract
Little is known about the causes and mechanisms of ectopic immune responses, including different types of hypersensitivity, superantigens, and cytokine storms. Two of the most questionable phenomena observed in immunology are why the intensity and extent of immune responses to different antigens are different, and why some self-antigens are attacked as foreign. The secondary structure of the peptides involved in the immune system, such as the epitope-paratope interfaces plays a pivotal role in the resulting immune responses. Prolyl cis/trans isomerization plays a fundamental role in the form of the secondary structure and the folding of proteins. This review covers some of the emerging evidence indicating the impact of prolyl isomerization on protein conformation, aberration of immune responses, and the development of hypersensitivity reactions.
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Affiliation(s)
- Mehrdad Vakilian
- Department of Cell Biology, Genetics and Physiology, University of Malaga (UMA), The Institute of Biomedical Research in Malaga (IBIMA), Málaga, Spain.
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12
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Bergmann AC, Kyllesbech C, Slibinskas R, Ciplys E, Højrup P, Trier NH, Houen G. Epitope Mapping of Monoclonal Antibodies to Calreticulin Reveals That Charged Amino Acids Are Essential for Antibody Binding. Antibodies (Basel) 2021; 10:antib10030031. [PMID: 34449535 PMCID: PMC8395503 DOI: 10.3390/antib10030031] [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: 05/20/2021] [Revised: 06/25/2021] [Accepted: 07/30/2021] [Indexed: 02/01/2023] Open
Abstract
Calreticulin is a chaperone protein, which is associated with myeloproliferative diseases. In this study, we used resin-bound peptides to characterize two monoclonal antibodies (mAbs) directed to calreticulin, mAb FMC 75 and mAb 16, which both have significantly contributed to understanding the biological function of calreticulin. The antigenicity of the resin-bound peptides was determined by modified enzyme-linked immunosorbent assay. Specific binding was determined to an 8-mer epitope located in the N-terminal (amino acids 34–41) and to a 12-mer peptide located in the C-terminal (amino acids 362–373). Using truncated peptides, the epitopes were identified as TSRWIESK and DEEQRLKEEED for mAb FMC 75 and mAb 16, respectively, where, especially the charged amino acids, were found to have a central role for a stable binding. Further studies indicated that the epitope of mAb FMC 75 is assessable in the oligomeric structure of calreticulin, making this epitope a potential therapeutic target.
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Affiliation(s)
| | - Cecilie Kyllesbech
- Department of Neurology, Rigshospitalet Glostrup, 2600 Glostrup, Denmark;
| | - Rimantas Slibinskas
- Institute of Biotechnology, University of Vilnius, 01513 Vilnius, Lithuania; (R.S.); (E.C.)
| | - Evaldas Ciplys
- Institute of Biotechnology, University of Vilnius, 01513 Vilnius, Lithuania; (R.S.); (E.C.)
| | - Peter Højrup
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense, Denmark;
| | - Nicole Hartwig Trier
- Department of Neurology, Rigshospitalet Glostrup, 2600 Glostrup, Denmark;
- Correspondence: (N.H.T.); (G.H.)
| | - Gunnar Houen
- Department of Neurology, Rigshospitalet Glostrup, 2600 Glostrup, Denmark;
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense, Denmark;
- Correspondence: (N.H.T.); (G.H.)
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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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Nogueira L, Parra E, Larrieu M, Verrouil E, Cornillet M. Are antibodies to fine specificities of citrullinated peptides/proteins useful for stratification of rheumatoid arthritis patients? Clin Transl Immunology 2021; 10:e1288. [PMID: 34257966 PMCID: PMC8256671 DOI: 10.1002/cti2.1288] [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: 09/29/2020] [Revised: 12/14/2020] [Accepted: 04/27/2021] [Indexed: 11/30/2022] Open
Abstract
Background In rheumatoid arthritis (RA), antibodies to citrullinated protein (ACPA) are believed to be heterogeneous and patient stratification by antibody profiling raised clinical interest for patient management. However, heterogeneity might be partially artificial because of the use of heterogeneous methods for ACPA detection. In recent work instead, we found that ACPA were mainly directed towards a single fibrin‐derived peptide, β60‐74BiotNt, but a comparative analysis with the presence of other ACPA specificities is still lacking. Objectives To present an overview of RA patients' stratification based on the detection of the main ACPA fine specificities with the same method as compared to that of anti‐β60‐74BiotNt antibodies. Methods Over 4500 measurements were performed with more than 22 standardised ELISAs, sera from 180 RA patients and 200 to 436 non‐RA rheumatic disease controls. Results Four to 81% of RA patients had ACPA towards various targets, confirming the heterogeneity of ACPA specificities. However, the subgroups of patients overlapped up to 97% with ACPA levels of correlation coefficients up to 0.8, showing redundancy of some targets. Multiplexing decreased diagnostic specificity from 95% to 64%. Instead, anti‐β60‐74BiotNt detection identified almost all ACPA‐positive patients. Conclusions Antibodies to citrullinated protein multiplexing shows some degree of redundancy and is not suitable for diagnostic purposes. ACPA fine specificities might be less heterogeneous than perceived by sera testing on multiple peptides. Patient stratification largely depends on detection methods and requires standardisation.
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Affiliation(s)
- Leonor Nogueira
- Laboratory of Cell Biology and Cytology University Hospital of Toulouse Toulouse France
| | - Emilie Parra
- Laboratory of Cell Biology and Cytology University Hospital of Toulouse Toulouse France
| | - Margaux Larrieu
- Laboratory of Cell Biology and Cytology University Hospital of Toulouse Toulouse France
| | - Evelyne Verrouil
- Laboratory of Cell Biology and Cytology University Hospital of Toulouse Toulouse France
| | - Martin Cornillet
- Laboratory of Cell Biology and Cytology University Hospital of Toulouse Toulouse France
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15
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Valdarnini N, Holm B, Hansen P, Rovero P, Houen G, Trier N. Fine Mapping of Glutamate Decarboxylase 65 Epitopes Reveals Dependency on Hydrophobic Amino Acids for Specific Interactions. Int J Mol Sci 2019; 20:ijms20122909. [PMID: 31207885 PMCID: PMC6627456 DOI: 10.3390/ijms20122909] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 06/06/2019] [Accepted: 06/11/2019] [Indexed: 01/10/2023] Open
Abstract
Characterization of multiple antibody epitopes has revealed the necessity of specific groups of amino acid residues for reactivity. This applies to the majority of antibody-antigen interactions, where especially charged and hydrophilic amino acids have been reported to be essential for antibody reactivity. This study describes thorough characterization of glutamic acid decarboxylase (GAD) 65 antigenic epitopes, an immunodominant autoantigen in type 1 diabetes (T1D). As linear epitopes are sparsely described for GAD65 in T1D, we aimed to identify and thoroughly characterize two GAD65 antibodies using immunoassays. A monoclonal antibody recognized an epitope in the N-terminal domain of GAD65, 8FWSFGSE14, whereas a polyclonal antibody recognized two continuous epitopes in the C-terminal domain, corresponding to amino acids 514RTLED518 and 549PLGDKVNF556. Hydrophobic amino acids were essential for antibody reactivity, which was verified by competitive inhibition assays. Moreover, the epitopes were located in flexible linker regions and turn structures. These findings confirm the versatile nature of antibody-antigen interactions and describe potential continuous epitopes related to T1D, which predominantly have been proposed to be of discontinuous nature.
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Affiliation(s)
- Niccolò Valdarnini
- Interdepartmental Laboratory of Peptide and Protein Chemistry and Biology, Department of NeuroFarBa, University of Florence, Via Ugo Schiff, 6, 50019 Sesto Fiorentino, Italy.
| | - Bettina Holm
- Department of Clinical Immunology, Rigshospitalet, Ole Maaløes vej 26, 2200 Copenhagen N, Denmark.
| | - Paul Hansen
- Department of Drug Design and Pharmacology, Universitetsparken 2, 2100 Copenhagen Ø, Denmark.
| | - Paolo Rovero
- Interdepartmental Laboratory of Peptide and Protein Chemistry and Biology, Department of NeuroFarBa, University of Florence, Via Ugo Schiff, 6, 50019 Sesto Fiorentino, Italy.
| | - Gunnar Houen
- Department of Neurology, Rigshospitalet Glostrup, Nordre Ringvej 57, 2600 Glostrup, Denmark.
| | - Nicole Trier
- Department of Neurology, Rigshospitalet Glostrup, Nordre Ringvej 57, 2600 Glostrup, Denmark.
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16
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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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Germar K, Fehres CM, Scherer HU, Uden N, Pollastro S, Yeremenko N, Hansson M, Kerkman PF, Voort EIH, Reed E, Maassen H, Kwakkenbos MJ, Bakker AQ, Klareskog L, Malmström V, Vries N, Toes REM, Lundberg K, Spits H, Baeten DL. Generation and Characterization of Anti–Citrullinated Protein Antibody–Producing B Cell Clones From Rheumatoid Arthritis Patients. Arthritis Rheumatol 2019; 71:340-350. [DOI: 10.1002/art.40739] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 09/25/2018] [Indexed: 12/27/2022]
Affiliation(s)
- Kristine Germar
- Academic Medical CenterUniversity of Amsterdam Amsterdam The Netherlands
| | - Cynthia M. Fehres
- Academic Medical CenterUniversity of Amsterdam Amsterdam The Netherlands
| | | | - Nathalie Uden
- Academic Medical CenterUniversity of Amsterdam Amsterdam The Netherlands
| | - Sabrina Pollastro
- Academic Medical CenterUniversity of Amsterdam Amsterdam The Netherlands
| | - Nataliya Yeremenko
- Academic Medical CenterUniversity of Amsterdam Amsterdam The Netherlands
| | - Monika Hansson
- Karolinska Institutet/Karolinska University Hospital Stockholm Sweden
| | | | | | - Evan Reed
- Karolinska Institutet/Karolinska University Hospital Stockholm Sweden
| | - Hanna Maassen
- Leiden University Medical Center Leiden The Netherlands
| | | | - Arjen Q. Bakker
- AIMM Therapeutics and Academic Medical CenterUniversity of Amsterdam
| | - Lars Klareskog
- Karolinska Institutet/Karolinska University Hospital Stockholm Sweden
| | | | - Niek Vries
- Academic Medical CenterUniversity of Amsterdam Amsterdam The Netherlands
| | | | - Karin Lundberg
- Karolinska Institutet/Karolinska University Hospital Stockholm Sweden
| | - Hergen Spits
- AIMM Therapeutics and Academic Medical CenterUniversity of Amsterdam
| | - Dominique L. Baeten
- Academic Medical CenterUniversity of Amsterdam, and UCB Pharma Brussels Belgium
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19
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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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20
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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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21
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Schrimpf A, Brödje D, Pfefferle P, Geyer A. A set of conformationally well-defined L/D-peptide epitopes provides a serological bar code for autoantibody subtypes. PLoS One 2018; 13:e0201735. [PMID: 30075018 PMCID: PMC6075753 DOI: 10.1371/journal.pone.0201735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 07/21/2018] [Indexed: 11/23/2022] Open
Abstract
Which conformational parameters lead to an antibody-affine peptide antigen? And in how many different conformations can we actually present the respective conformational epitope? To provide answers from a chemical point of view, we direct the bending and tethering of peptide backbones by the utilisation of a hydrophobic cluster, disulfides, and d-amino acids. Each mutation is employed pairwise on directly opposite sides of a β-hairpin. In combination, these synthetic modules guide the formation of complementary β-sheet-like structures, whereby the oppositely configured (l/d-)bi-disulfide pairs form with high regioselectivity. The conformational properties of the peptides are assessed by NMR spectroscopy and correlated with their antibody affinity in ELISA. From a pool of thus designed peptide antigens with distinctive complementary affinities against known rheumatoid arthritis (RA) autoantibodies, we select a set of epitopes for an immunoassay with sera of RA patients. We want to put emphasis on the idea, that the different conformational properties of the chosen antigens, containing the same epitope sequence, are mirrored in the distribution of autoantibody subtypes (or of the antibody polyclonality, respectively). Such directly comparable information can only be delivered by a set of peptides, rather than a single one. The hairpin-restriction technology of l/d-configured bi-disulfide amino acid pairs is not limited to RA but applicable to other shape-persistent hairpin motifs which are supposed to identify subgroups of protein receptors.
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Affiliation(s)
- Andreas Schrimpf
- Department of Chemistry, Philipps-Universität Marburg, Marburg, Germany
| | - Dörte Brödje
- Department of Medicine, Philipps-Universität Marburg, Marburg, Germany
| | - Petra Pfefferle
- Comprehensive Biomaterial Bank Marburg (CBBMR), Marburg, Germany
| | - Armin Geyer
- Department of Chemistry, Philipps-Universität Marburg, Marburg, Germany
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22
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Gunasekera S, Fernandes-Cerqueira C, Wennmalm S, Wähämaa H, Sommarin Y, Catrina AI, Jakobsson PJ, Göransson U. Stabilized Cyclic Peptides as Scavengers of Autoantibodies: Neutralization of Anticitrullinated Protein/Peptide Antibodies in Rheumatoid Arthritis. ACS Chem Biol 2018; 13:1525-1535. [PMID: 29630823 DOI: 10.1021/acschembio.8b00118] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The occurrence of autoantibodies is a hallmark of rheumatoid arthritis, specifically those autoantibodies targeting proteins containing the arginine-derived amino acid citrulline. There is strong evidence showing that the occurrence of anticitrullinated protein/peptide antibodies (ACPA) are involved in disease progression, and ACPA was recently shown to induce pain in animals. Here, we explore a novel concept useful for research, diagnostics, and possibly therapy of autoimmune diseases, namely, to directly target and neutralize autoantibodies using peptide binders. A high-affinity peptide-based scavenger of ACPA was developed by grafting a citrullinated epitope derived from human fibrinogen into a naturally occurring stable peptide scaffold. The best scavenger comprises the truncated epitope α-fibrinogen, [Cit573]fib(566-580), grafted into the scaffold sunflower trypsin inhibitor-1, SFTI-1. The final peptide demonstrates low nanomolar apparent affinity and superior stability.
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Affiliation(s)
- Sunithi Gunasekera
- Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University, Biomedical Centre, Box 574, SE-75123 Uppsala, Sweden
| | - Cátia Fernandes-Cerqueira
- Rheumatology Unit, Department of Medicine—Solna, Karolinska Institutet, Karolinska University Hospital, Rheumatology Clinic D2:01, 171 76 Solna, Stockholm, Sweden
| | - Stefan Wennmalm
- Royal Institute of Technology-KTH, Applied Physics, Experimental Biomolecular Physics, Scilifelab, Tomtebodavägen 23, 171 65 Solna, Stockholm, Sweden
| | - Heidi Wähämaa
- Rheumatology Unit, Department of Medicine—Solna, Karolinska Institutet, Karolinska University Hospital, Rheumatology Clinic D2:01, 171 76 Solna, Stockholm, Sweden
| | | | - Anca I. Catrina
- Rheumatology Unit, Department of Medicine—Solna, Karolinska Institutet, Karolinska University Hospital, Rheumatology Clinic D2:01, 171 76 Solna, Stockholm, Sweden
| | - Per-Johan Jakobsson
- Rheumatology Unit, Department of Medicine—Solna, Karolinska Institutet, Karolinska University Hospital, Rheumatology Clinic D2:01, 171 76 Solna, Stockholm, Sweden
| | - Ulf Göransson
- Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University, Biomedical Centre, Box 574, SE-75123 Uppsala, Sweden
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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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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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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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Abstract
Peptide antibodies, with their high specificities and affinities, are invaluable reagents for peptide and protein recognition in biological specimens. Depending on the application and the assay, in which the peptide antibody is to used, several factors influence successful antibody production, including peptide selection and antibody screening. Peptide antibodies have been used in clinical laboratory diagnostics with great success for decades, primarily because they can be produced to multiple targets, recognizing native wildtype proteins, denatured proteins, and newly generated epitopes. Especially mutation-specific peptide antibodies have become important as diagnostic tools in the detection of various cancers. In addition to their use as diagnostic tools in malignant and premalignant conditions, peptide antibodies are applied in all other areas of clinical laboratory diagnostics, including endocrinology, hematology, neurodegenerative diseases, cardiovascular diseases, infectious diseases, and amyloidoses.
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Dam CE, Houen G, Trier NH. The dependency on neighboring amino acids for reactivity of anti-citrullinated protein antibodies to citrullinated proteins. Scandinavian Journal of Clinical and Laboratory Investigation 2016; 76:417-25. [PMID: 27348081 DOI: 10.1080/00365513.2016.1200133] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Rheumatoid arthritis (RA) is an autoimmune connective tissue disease, associated with the presence of anti-citrullinated protein antibodies (ACPA). These antibodies have been found in approximately 70% of patients suffering from RA and they are currently used for diagnosis of RA. Although they exhibit an absolute need for citrulline for antibody reactivity, no precise cognate antigen for these antibodies has been determined. In this study, we analyzed the reactivity of ACPA to various citrullinated peptides by modified enzyme-linked immunosorbent assays, in order to determine the dependency of specific amino acids for antibody reactivity. A non-human protein (ovalbumin) and antigens directly related to RA were used as templates for synthesis of non-modified and citrullinated peptides, becoming potential target epitopes. Mainly peptides containing a Cit-Gly motif were recognized by ACPAs, while no particular amino acids N-terminal of citrulline were found to be essential for antibody reactivity. Moreover, ACPA reactivity was not restricted to antigens known to be associated with ACPA-positive RA alone, but also to proteins without relation to RA, primarily illustrating that any protein in theory can be turned into an RA autoantigen, by introducing Cit-Gly motifs. Knowledge about the interaction between ACPAs and their citrullinated targets is important for understanding autoimmune ACPA responses in RA, which are known to contribute to the pathophysiology.
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Affiliation(s)
- Catharina E Dam
- a Department of Autoimmunology and Biomarkers , Statens Serum Institut , Copenhagen , Denmark
| | - Gunnar Houen
- a Department of Autoimmunology and Biomarkers , Statens Serum Institut , Copenhagen , Denmark
| | - Nicole H Trier
- a Department of Autoimmunology and Biomarkers , Statens Serum Institut , Copenhagen , Denmark
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Trier NH, Holm BE, Slot O, Locht H, Lindegaard H, Svendsen A, Nielsen CT, Jacobsen S, Theander E, Houen G. Application of synthetic peptides for detection of anti-citrullinated peptide antibodies. Peptides 2016; 76:87-95. [PMID: 26796582 DOI: 10.1016/j.peptides.2016.01.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 01/04/2016] [Accepted: 01/08/2016] [Indexed: 01/08/2023]
Abstract
Anti-citrullinated protein antibodies (ACPAs) are a hallmark of rheumatoid arthritis (RA) and represent an important tool for the serological diagnosis of RA. In this study, we describe ACPA reactivity to overlapping citrullinated Epstein-Barr virus nuclear antigen-1 (EBNA-1)-derived peptides and analyze their potential as substrates for ACPA detection by streptavidin capture enzyme-linked immunosorbent assay. Using systematically overlapping peptides, containing a 10 amino acid overlap, labelled with biotin C-terminally or N-terminally, sera from 160 individuals (RA sera (n=60), healthy controls (n=40), systemic lupus erythematosus (n=20), Sjögren's syndrome (n=40)) were screened for antibody reactivity. Antibodies to a panel of five citrullinated EBNA-1 peptides were found in 67% of RA sera, exclusively of the IgG isotype, while 53% of the patient sera reacted with a single peptide, ARGGSRERARGRGRG-Cit-GEKR, accounting for more than half of the ACPA reactivity alone. Moreover, these antibodies were detected in 10% of CCP2-negative RA sera. In addition, 47% of the RA sera reacted with two or three citrullinated EBNA-1 peptides from the selected peptide panel. Furthermore, a negative correlation between the biotin attachment site and the location of citrulline in the peptides was found, i.e. the closer the citrulline was located to biotin, the lower the antibody reactivity. Our data suggest that citrullinated EBNA-1 peptides may be considered a substrate for the detection of ACPAs and that the presence of Epstein-Barr virus may play a role in the induction of these autoantibodies.
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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
| | - 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
- Department of Rheumatology, Copenhagen University Hospital, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | - Søren Jacobsen
- Department of Rheumatology, Copenhagen University Hospital, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | - Elke Theander
- Department of Rheumatology, Skåne University Hospital, Lund University, S-20502 Malmø, Sweden
| | - Gunnar Houen
- Department of Autoimmunology and Biomarkers, Statens Serum Institut, Artillerivej 5, 2300 Copenhagen S, Denmark.
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