51
|
Abstract
PURPOSE OF REVIEW Dysregulated citrullination is a key element that drives the production and maintenance of antibodies to citrullinated proteins, a hallmark in rheumatoid arthritis (RA). This article reviews recent literature on the origin of citrullinated antigens in RA. RECENT FINDINGS The study of synovial fluid from patients with RA has provided important insights into the identity of citrullinated proteins that accumulate in the RA joint (the RA citrullinome) and mechanisms that control their generation. SUMMARY Citrullinating enzymes (peptidylarginine deiminases, PADs) are tightly controlled to limit their hyperactivation. Calcium and redox conditions are important regulators of PAD activity. Studies suggest that citrullination is dysregulated both intra- and extracellularly in RA. In neutrophils, host (i.e., perforin and the membrane attack complex) and bacterial (i.e., toxins) pore-forming proteins induce prominent calcium influx, cytolysis, and hyperactivation of PADs. These factors likely drive hypercitrullination in the RA joint and at extraarticular sites of disease initiation, respectively. As oxidizing conditions present in the extracellular environment are known to inactivate PADs, extracellular citrullination in RA probably requires the constant release of active enzymes from dying cells and may be accelerated by autoantibodies that activate PADs.
Collapse
Affiliation(s)
- Erika Darrah
- Division of Rheumatology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Felipe Andrade
- Division of Rheumatology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| |
Collapse
|
52
|
Cornett DS, Scholle MD. Advances in MALDI Mass Spectrometry within Drug Discovery. SLAS DISCOVERY : ADVANCING LIFE SCIENCES R & D 2017; 22:1179-1181. [PMID: 29153034 DOI: 10.1177/2472555217735067] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
|
53
|
Damgaard D, Bjørn ME, Jensen PØ, Nielsen CH. Reactive oxygen species inhibit catalytic activity of peptidylarginine deiminase. J Enzyme Inhib Med Chem 2017; 32:1203-1208. [PMID: 28933232 PMCID: PMC6021033 DOI: 10.1080/14756366.2017.1368505] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Protein citrullination catalysed by peptidylarginine deiminase (PAD) may play an important pathogenic role in several chronic inflammatory diseases and malignancies. PAD2, PAD4, and citrullinated proteins are found in the synovium of rheumatoid arthritis patients. PAD activity is dependent on calcium and reducing conditions. However, reactive oxygen species (ROS) have been shown to induce citrullination of histones in granulocytes. Here we examine the ability of H2O2 and leukocyte-derived ROS to regulate PAD activity using citrullination of fibrinogen as read-out. H2O2 at concentrations above 40 µM inhibited the catalytic activity of PAD2 and PAD4 in a dose-dependent manner. PMA-stimulated leukocytes citrullinated fibrinogen and this citrullination was markedly enhanced when ROS formation was inhibited by the NADPH oxidase inhibitor diphenyleneiodonium (DPI). In contrast, PAD released from stimulated leukocytes was unaffected by exogenously added H2O2 at concentrations up to 1000 µM. The role of ROS in regulating PAD activity may play an important part in preventing hypercitrullination of proteins.
Collapse
Affiliation(s)
- Dres Damgaard
- a Institute for Inflammation Research, Center for Rheumatology and Spine Diseases, Copenhagen University Hospital, Rigshospitalet , Copenhagen , Denmark.,b Section for Periodontology, Microbiology and Community Dentistry, Department of Odontology, Faculty of Health and Medical Sciences , University of Copenhagen , Copenhagen , Denmark
| | - Mads Emil Bjørn
- a Institute for Inflammation Research, Center for Rheumatology and Spine Diseases, Copenhagen University Hospital, Rigshospitalet , Copenhagen , Denmark.,c Department of Haematology , Roskilde Hospital , Roskilde , Denmark
| | - Peter Østrup Jensen
- a Institute for Inflammation Research, Center for Rheumatology and Spine Diseases, Copenhagen University Hospital, Rigshospitalet , Copenhagen , Denmark.,d Department of Clinical Microbiology , Copenhagen University Hospital, Rigshospitalet , Copenhagen , Denmark
| | - Claus Henrik Nielsen
- a Institute for Inflammation Research, Center for Rheumatology and Spine Diseases, Copenhagen University Hospital, Rigshospitalet , Copenhagen , Denmark.,b Section for Periodontology, Microbiology and Community Dentistry, Department of Odontology, Faculty of Health and Medical Sciences , University of Copenhagen , Copenhagen , Denmark
| |
Collapse
|
54
|
Zhou Y, Chen B, Mittereder N, Chaerkady R, Strain M, An LL, Rahman S, Ma W, Low CP, Chan D, Neal F, Bingham CO, Sampson K, Darrah E, Siegel RM, Hasni S, Andrade F, Vousden KA, Mustelin T, Sims GP. Spontaneous Secretion of the Citrullination Enzyme PAD2 and Cell Surface Exposure of PAD4 by Neutrophils. Front Immunol 2017; 8:1200. [PMID: 28993780 PMCID: PMC5622307 DOI: 10.3389/fimmu.2017.01200] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 09/11/2017] [Indexed: 01/08/2023] Open
Abstract
Autoantibodies directed against citrullinated epitopes of proteins are highly diagnostic of rheumatoid arthritis (RA), and elevated levels of protein citrullination can be found in the joints of patients with RA. Calcium-dependent peptidyl-arginine deiminases (PAD) are the enzymes responsible for citrullination. PAD2 and PAD4 are enriched in neutrophils and likely drive citrullination under inflammatory conditions. PADs may be released during NETosis or cell death, but the mechanisms responsible for PAD activity under physiological conditions have not been fully elucidated. To understand how PADs citrullinate extracellular proteins, we investigated the cellular localization and activity of PAD2 and PAD4, and we report that viable neutrophils from healthy donors have active PAD4 exposed on their surface and spontaneously secrete PAD2. Neutrophil activation by some stimulatory agents increased the levels of immunoreactive PAD4 on the cell surface, and some stimuli reduced PAD2 secretion. Our data indicate that live neutrophils have the inherent capacity to express active extracellular PADs. These novel pathways are distinguished from intracellular PAD activation during NETosis and calcium influx-mediated hypercitrullination. Our study implies that extracellular PADs may have a physiological role under non-pathogenic conditions as well as a pathological role in RA.
Collapse
Affiliation(s)
- Yebin Zhou
- Department of Respiratory, Inflammation, and Autoimmunity, MedImmune LLC, Gaithersburg, MD, United States
| | - Bo Chen
- Department of Respiratory, Inflammation, and Autoimmunity, MedImmune LLC, Gaithersburg, MD, United States
| | - Nanette Mittereder
- Department of Respiratory, Inflammation, and Autoimmunity, MedImmune LLC, Gaithersburg, MD, United States
| | - Raghothama Chaerkady
- Antibody Discovery and Protein Engineering, MedImmune LLC., Gaithersburg, MD, United States
| | - Martin Strain
- Antibody Discovery and Protein Engineering, MedImmune LTD., Cambridge, United Kingdom
| | - Ling-Ling An
- Department of Respiratory, Inflammation, and Autoimmunity, MedImmune LLC, Gaithersburg, MD, United States
| | - Saifur Rahman
- Department of Respiratory, Inflammation, and Autoimmunity, MedImmune LLC, Gaithersburg, MD, United States
| | - Wenting Ma
- Department of Respiratory, Inflammation, and Autoimmunity, MedImmune LLC, Gaithersburg, MD, United States
| | - Choon Pei Low
- Antibody Discovery and Protein Engineering, MedImmune LTD., Cambridge, United Kingdom
| | - Denice Chan
- Antibody Discovery and Protein Engineering, MedImmune LTD., Cambridge, United Kingdom
| | - Frances Neal
- Antibody Discovery and Protein Engineering, MedImmune LTD., Cambridge, United Kingdom
| | - Clifton O Bingham
- Division of Rheumatology, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD, United States
| | - Kevon Sampson
- Division of Rheumatology, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD, United States
| | - Erika Darrah
- Division of Rheumatology, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD, United States
| | - Richard M Siegel
- Immunoregulation Section, Autoimmunity Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), NIH, Bethesda, MD, United States
| | - Sarfaraz Hasni
- Office of the Clinical Director, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), NIH, Bethesda, MD, United States
| | - Felipe Andrade
- Division of Rheumatology, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD, United States
| | - Katherine A Vousden
- Antibody Discovery and Protein Engineering, MedImmune LTD., Cambridge, United Kingdom
| | - Tomas Mustelin
- Department of Respiratory, Inflammation, and Autoimmunity, MedImmune LLC, Gaithersburg, MD, United States
| | - Gary P Sims
- Department of Respiratory, Inflammation, and Autoimmunity, MedImmune LLC, Gaithersburg, MD, United States
| |
Collapse
|
55
|
Hutchinson D, Clarke A, Heesom K, Murphy D, Eggleton P. Carbamylation/citrullination of IgG Fc in bronchiectasis, established RA with bronchiectasis and RA smokers: a potential risk factor for disease. ERJ Open Res 2017; 3:00018-2017. [PMID: 29204430 PMCID: PMC5703356 DOI: 10.1183/23120541.00018-2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 07/07/2017] [Indexed: 12/27/2022] Open
Abstract
Bronchiectasis (BR) and smoking are risk factors for rheumatoid arthritis (RA) development. The mechanisms by which smoking and BR trigger RA are unknown, but are associated with concurrent rheumatoid factor (RF) and anti-cyclic citrullinated peptide antibody (anti-CCP) positivity. Anti-carbamylated protein antibodies (anti-CarP) have also been observed in BR patients and can be induced by smoking. Given that RF only has one antigen, immunoglobulin G (IgG) we have suggested that post-translational modifications to the Fc region of the heavy chain of IgG (IgGH) are a potential explanation for the clustering of the RA-associated autoantibodies in RA. Protein analysis was undertaken on 22 individuals. Four of the individuals had a diagnosis of BR at the time of protein analysis and subsequently developed RA up to 18 months following blood sampling. Four smoking RA patients and 4 patients with both BR and RA and 10 healthy controls were also studied. We identified modified arginines (Arg) frequently in the variable region and CH3 domains of IgG in patients and control subjects alike, but only observed carbamylated Lys and/or citrullinated Arg modifications in the RF binding site of the IgG CH2 domain of 5/12 (41.7%) patients investigated (1 BR, 2 RA and 2 BRRA), but in no control subjects (0/10, 0%) p=0.02. This is the first report of citrullination and carbamylation at the RF binding site of IgG in RA. These results point towards the concept of a universal antigen in RA, an antigen that is post-translationally modified at the Fc region of IgGH. Fc region of IgG is citrullinated and carbamylated, and these PTMs can occur prior to the development of RAhttp://ow.ly/8ZDe30evfO4
Collapse
Affiliation(s)
- David Hutchinson
- University of Exeter Medical School, Exeter, UK.,Dept of Rheumatology, Royal Cornwall Hospital Trust, Truro, UK.,These authors contributed equally
| | - Alexander Clarke
- University of Exeter Medical School, Exeter, UK.,These authors contributed equally
| | - Kate Heesom
- Proteomics facility, University of Bristol, Bristol, UK
| | - Daniel Murphy
- University of Exeter Medical School, Exeter, UK.,Dept of Rheumatology, Royal Cornwall Hospital Trust, Truro, UK
| | - Paul Eggleton
- University of Exeter Medical School, Exeter, UK.,UCB Pharma, Slough, UK
| |
Collapse
|
56
|
Blachère NE, Parveen S, Frank MO, Dill BD, Molina H, Orange DE. High-Titer Rheumatoid Arthritis Antibodies Preferentially Bind Fibrinogen Citrullinated by Peptidylarginine Deiminase 4. Arthritis Rheumatol 2017; 69:986-995. [PMID: 28029744 DOI: 10.1002/art.40035] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 12/22/2016] [Indexed: 01/11/2023]
Abstract
OBJECTIVE Most patients with rheumatoid arthritis (RA) harbor antibodies to citrullinated autoantigens such as citrullinated fibrinogen. Two isoforms of peptidylarginine deiminase (PAD), PAD type 2 (PAD2) and PAD4, which catalyze citrullination with different substrate specificities, can be detected in the synovium of RA patients. This study was undertaken to determine whether RA antibodies preferentially bind PAD2- or PAD4-citrullinated fibrinogen. METHODS RA patient and normal donor plasma specimens were tested for binding to PAD2- or PAD4-citrullinated fibrinogen, native fibrinogen, or citrullinated fibrinogen peptides in various dilutions by enzyme-linked immunosorbent assay (ELISA) and Western blotting. Bands corresponding to masses demonstrating RA antibody reactivity by Western blotting were excised and analyzed by mass spectrometry. RESULTS At low antibody titers (1:40 and 1:100), there was no significant difference between RA antibody reactivity to PAD2- and PAD4-citrullinated fibrinogen. When plasma was further diluted to 1:250 and 1:1,000, RA patient plasma bound PAD4-citrullinated fibrinogen significantly more than PAD2-citrullinated fibrinogen, as measured by ELISA and Western blotting. An increased antibody titer was associated with increased avidity for both PAD2- and PAD4-citrullinated fibrinogen. Both enzymes hypercitrullinated fibrinogen, but PAD4 citrullinated arginines more intermittently, generating a mix of citrullinated and noncitrullinated arginines. Peptide ELISA and preadsorption assays confirmed that the region of intermittent citrullination accounts for the majority of RA antibody binding to the β-chain of citrullinated fibrinogen. CONCLUSION At high titers, RA antibodies preferentially bind fibrinogen modified by PAD4, because intermittent citrullination offers a more diverse assortment of citrullinated epitopes.
Collapse
Affiliation(s)
- Nathalie E Blachère
- Rockefeller University and Howard Hughes Medical Institute, New York, New York
| | | | - Mayu O Frank
- Rockefeller University and New York Genome Center, New York, New York
| | | | | | - Dana E Orange
- Rockefeller University, Hospital for Special Surgery, and New York Genome Center, New York, New York
| |
Collapse
|
57
|
Anti-citrullinated protein antibody positive rheumatoid arthritis is primarily determined by rheumatoid factor titre and the shared epitope rather than smoking per se. PLoS One 2017; 12:e0180655. [PMID: 28708862 PMCID: PMC5510819 DOI: 10.1371/journal.pone.0180655] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 06/19/2017] [Indexed: 12/15/2022] Open
Abstract
Objective To analyse the relationship between rheumatoid factor (RF) titre, smoking and HLA-DRB1 alleles coding a “shared epitope” (SE) in relation to anti-citrullinated protein antibody (ACPA) positivity in rheumatoid arthritis (RA). Methods RA patients (n = 658) attending rheumatology clinics in Cornwall, UK (cohort 1) were stratified according to RF and ACPA titre, and smoking pack years at diagnosis. A further 409 RA patients from North Staffordshire, UK (cohort 2) were studied to confirm the relationship between RF levels, smoking and ACPA positivity in relation to SE status. Results In cohort 1 there was a trend (p<0.01) of increasing ACPA positivity rates with increasing levels of RF without statistically significant differences between patients who had never smoked and smokers (never smoked: 15/71 (21%) RF -ve, vs. 43/64 (67%) RF weak +ve, vs 88/100 (88%) RF strong +ve, ever smoked: 18/70 (26%) RF -ve vs. 66/83 (80%) RF weak +ve vs. 196/210 (93%) RF strong +ve). No significant gender difference was observed. No significant difference between smoking and ACPA positivity was seen in RF negative patients. Smoking >20 pack years conferred an increased risk of anti-CCP positive RA (158/200 (79%)), compared to having never smoked (146/235 (62%), p = <0.01), but this increased risk correlated with smokers’ RF positivity as the principal determinant on subsequent regression analysis of cohort 2. In cohort 2, ACPA positivity rates significantly increased with RF positivity and carriage of 1 or 2 SE alleles (p<0.01). Little or no relationship was observed in patients lacking SE. Conclusions ACPA positivity in RA strongly associates with increasing RF titre independent of smoking. This relationship is dependent on carriage of SE alleles. There is no relationship between ACPA and smoking in RF negative patients.
Collapse
|
58
|
Lourido L, Blanco FJ, Ruiz-Romero C. Defining the proteomic landscape of rheumatoid arthritis: progress and prospective clinical applications. Expert Rev Proteomics 2017; 14:431-444. [PMID: 28425787 DOI: 10.1080/14789450.2017.1321481] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
INTRODUCTION The heterogeneity of Rheumatoid Arthritis (RA) and the absence of clinical tests accurate enough to identify the early stages of this disease have hampered its management. Therefore, proteomics research is increasingly focused on the discovery of novel biological markers, which would not only be able make an early diagnosis, but also to gain insight into the different pathological mechanisms underlying the heterogeneity of RA and also to stratify patients, which is critical to enabling effective treatments. Areas covered: The proteomic approaches that have been utilised to provide knowledge about RA pathogenesis, and to identify biomarkers for RA diagnosis, prognosis, disease monitoring and prediction of response to therapy, are summarized. Expert commentary: Although each proteomic study is unique in its design, all of them have contributed to the understanding of RA pathogenesis and the discovery of promising biomarkers for patient stratification, which would improve clinical care of RA patients. Still, efforts need to be made to validate these findings and translate them into clinical practice.
Collapse
Affiliation(s)
- Lucía Lourido
- a Rheumatology Division, ProteoRed/ISCIII Proteomics Group , INIBIC - Hospital Universitario de A Coruña , A Coruña , Spain.,b RIER-RED de Inflamación y Enfermedades Reumáticas , INIBIC-CHUAC , A Coruña , Spain
| | - Francisco J Blanco
- a Rheumatology Division, ProteoRed/ISCIII Proteomics Group , INIBIC - Hospital Universitario de A Coruña , A Coruña , Spain.,b RIER-RED de Inflamación y Enfermedades Reumáticas , INIBIC-CHUAC , A Coruña , Spain
| | - Cristina Ruiz-Romero
- a Rheumatology Division, ProteoRed/ISCIII Proteomics Group , INIBIC - Hospital Universitario de A Coruña , A Coruña , Spain.,c CIBER-BBN Instituto de Salud Carlos III , INIBIC-CHUAC , A Coruña , Spain
| |
Collapse
|
59
|
Doody KM, Bottini N, Firestein GS. Epigenetic alterations in rheumatoid arthritis fibroblast-like synoviocytes. Epigenomics 2017; 9:479-492. [PMID: 28322585 DOI: 10.2217/epi-2016-0151] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Rheumatoid arthritis is an immune-mediated disease that primarily affects diarthrodial joints. Susceptibility and severity of this disease are influenced by nongenetic factors, such as environmental stress, suggesting an important role of epigenetic changes. In this review, we summarize the epigenetic changes (DNA methylation, histone modification and miRNA expression) in fibroblast-like synoviocytes, which are the joint-lining mesenchymal cells that play an important role in joint inflammation and damage. We also review the effects of these epigenetic changes on rheumatoid arthritis pathogenesis and discuss their therapeutic potential.
Collapse
Affiliation(s)
- Karen M Doody
- Grenfell Campus, Memorial University of Newfoundland, Corner Brook, Newfoundland, Canada
| | - Nunzio Bottini
- Division of Rheumatology, Allergy & Immunology, University of California, San Diego School of Medicine, La Jolla, CA, USA
| | - Gary S Firestein
- Division of Rheumatology, Allergy & Immunology, University of California, San Diego School of Medicine, La Jolla, CA, USA
| |
Collapse
|
60
|
Gazitt T, Lood C, Elkon KB. Citrullination in Rheumatoid Arthritis-A Process Promoted by Neutrophil Lysis? Rambam Maimonides Med J 2016; 7:RMMJ.10254. [PMID: 27824546 PMCID: PMC5101001 DOI: 10.5041/rmmj.10254] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Anti-citrullinated protein antibodies (ACPAs) are highly specific serologic markers for rheumatoid arthritis (RA) and can pre-date clinical disease onset by up to 10 years, also predicting erosive disease. The process of citrullination, the post-translational conversion of arginine to citrulline residues, is mediated by peptidylarginine deiminase (PAD) enzymes present in polymorphonuclear cells (PMNs). Calcium ions (Ca2+) are required for PAD activation, but the intracellular Ca2+ concentration in normal cells is much lower than the optimal Ca2+ concentration needed for PAD activation. For this reason, it has been proposed that PAD activation, and thus citrullination, occurs only during PMN cell death when PAD enzymes leak out of the cells into the extracellular matrix, or extracellular Ca2+ enters the cells, with the high Ca2+ concentration activating PAD. Recently, using artificial in vitro systems to corroborate their hypothesis, Romero et al. demonstrated that "hypercitrullination," citrullination of multiple intracellular proteins, occurs within synovial fluid (SF) cells of RA patients, and that only modes of death leading to membranolysis such as perforin-granzyme pathway or complement membrane attack complex activation cause hypercitrullination. In order for Romero's hypothesis to hold, it is reasonable to surmise that PMN-directed lysis should occur in the rheumatoid joint or the circulation of RA patients. Research conducted thus far has shown that immunoglobulin G (IgG) targeting PMNs are present in RA SF and mediate PMN activation. However, the role of anti-PMN IgG in mediating complement activation and subsequent PMN lysis and hypercitrullination has not been fully evaluated.
Collapse
Affiliation(s)
- Tal Gazitt
- Division of Rheumatology, University of Washington, Seattle, WA, USA
| | - Christian Lood
- Division of Rheumatology, University of Washington, Seattle, WA, USA
| | - Keith B Elkon
- Division of Rheumatology, University of Washington, Seattle, WA, USA
| |
Collapse
|