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Sokolove J, Bromberg R, Deane KD, Lahey LJ, Derber LA, Chandra PE, Edison JD, Gilliland WR, Tibshirani RJ, Norris JM, Holers VM, Robinson WH. Autoantibody epitope spreading in the pre-clinical phase predicts progression to rheumatoid arthritis. PLoS One 2012; 7:e35296. [PMID: 22662108 PMCID: PMC3360701 DOI: 10.1371/journal.pone.0035296] [Citation(s) in RCA: 341] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 03/13/2012] [Indexed: 12/12/2022] Open
Abstract
Rheumatoid arthritis (RA) is a prototypical autoimmune arthritis affecting nearly 1% of the world population and is a significant cause of worldwide disability. Though prior studies have demonstrated the appearance of RA-related autoantibodies years before the onset of clinical RA, the pattern of immunologic events preceding the development of RA remains unclear. To characterize the evolution of the autoantibody response in the preclinical phase of RA, we used a novel multiplex autoantigen array to evaluate development of the anti-citrullinated protein antibodies (ACPA) and to determine if epitope spread correlates with rise in serum cytokines and imminent onset of clinical RA. To do so, we utilized a cohort of 81 patients with clinical RA for whom stored serum was available from 1–12 years prior to disease onset. We evaluated the accumulation of ACPA subtypes over time and correlated this accumulation with elevations in serum cytokines. We then used logistic regression to identify a profile of biomarkers which predicts the imminent onset of clinical RA (defined as within 2 years of testing). We observed a time-dependent expansion of ACPA specificity with the number of ACPA subtypes. At the earliest timepoints, we found autoantibodies targeting several innate immune ligands including citrullinated histones, fibrinogen, and biglycan, thus providing insights into the earliest autoantigen targets and potential mechanisms underlying the onset and development of autoimmunity in RA. Additionally, expansion of the ACPA response strongly predicted elevations in many inflammatory cytokines including TNF-α, IL-6, IL-12p70, and IFN-γ. Thus, we observe that the preclinical phase of RA is characterized by an accumulation of multiple autoantibody specificities reflecting the process of epitope spread. Epitope expansion is closely correlated with the appearance of preclinical inflammation, and we identify a biomarker profile including autoantibodies and cytokines which predicts the imminent onset of clinical arthritis.
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Affiliation(s)
- Jeremy Sokolove
- Division of Rheumatology, Department of Medicine, Stanford University School of Medicine, Stanford, California, United States of America
- VA Palo Alto Health Care System, Palo Alto, California, United States of America
- * E-mail: (JS); (WHR)
| | - Reuven Bromberg
- Division of Rheumatology, Department of Medicine, Stanford University School of Medicine, Stanford, California, United States of America
- VA Palo Alto Health Care System, Palo Alto, California, United States of America
| | - Kevin D. Deane
- Division of Rheumatology, Department of Medicine, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Lauren J. Lahey
- Division of Rheumatology, Department of Medicine, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Statistics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Lezlie A. Derber
- Division of Rheumatology, Department of Medicine, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Piyanka E. Chandra
- Division of Rheumatology, Department of Medicine, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Statistics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Jess D. Edison
- Walter Reed Army Medical Center, Washington, D.C., United States of America
| | | | - Robert J. Tibshirani
- Department of Statistics, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Health Research and Policy, Stanford University School of Medicine, Stanford, California, United States of America
| | - Jill M. Norris
- Department of Epidemiology, Colorado School of Public Health, University of Colorado, Aurora, Colorado, United States of America
| | - V. Michael Holers
- Division of Rheumatology, Department of Medicine, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - William H. Robinson
- Division of Rheumatology, Department of Medicine, Stanford University School of Medicine, Stanford, California, United States of America
- VA Palo Alto Health Care System, Palo Alto, California, United States of America
- * E-mail: (JS); (WHR)
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102
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Dwivedi N, Upadhyay J, Neeli I, Khan S, Pattanaik D, Myers L, Kirou KA, Hellmich B, Knuckley B, Thompson PR, Crow MK, Mikuls TR, Csernok E, Radic M. Felty's syndrome autoantibodies bind to deiminated histones and neutrophil extracellular chromatin traps. ACTA ACUST UNITED AC 2011; 64:982-92. [PMID: 22034172 DOI: 10.1002/art.33432] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
OBJECTIVE To test the hypothesis that autoantigen modifications by peptidylarginine deiminase type 4 (PAD-4) increase immunoreactivity. METHODS We assembled sera from patients with systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), Felty's syndrome (FS), and antineutrophil cytoplasmic antibody-associated vasculitides (AAVs), as well as sera from control subjects without autoimmune diseases. The sera were tested for binding to activated neutrophils, deiminated histones, and neutrophil extracellular chromatin traps (NETs). IgG binding to lipopolysaccharide-activated neutrophils was assessed with confocal microscopy, and binding to in vitro-deiminated histones was measured using enzyme-linked immunosorbent assay (ELISA) and Western blotting. In addition, we quantitated histone deimination in freshly isolated neutrophils from the blood of patients and control subjects. RESULTS Increased IgG reactivity with activated neutrophils, particularly binding to NETs, was paralleled by preferential binding to deiminated histones over nondeiminated histones by ELISA in a majority of sera from FS patients but only in a minority of sera from SLE and RA patients. Immunoblotting revealed autoantibody preference for deiminated histones H3, H4, and H2A in most FS patients and in a subset of SLE and RA patients. In patients with AAVs, serum IgG preferentially bound nondeiminated histones over deiminated histones. Increased levels of deiminated histones were detected in neutrophils from RA patients. CONCLUSION Circulating autoantibodies in FS are preferentially directed against PAD-4-deiminated histones and bind to activated neutrophils and NETs. Thus, increased reactivity with modified autoantigens in FS implies a direct contribution of neutrophil activation and the production of NET-associated nuclear autoantigens in the initiation or progression of FS.
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Affiliation(s)
- Nishant Dwivedi
- University of Tennessee Health Science Center, Memphis, TN 38163, USA
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103
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Causey CP, Jones JE, Slack JL, Kamei D, Jones LE, Subramanian V, Knuckley B, Ebrahimi P, Chumanevich AA, Luo Y, Hashimoto H, Sato M, Hofseth LJ, Thompson PR. The development of N-α-(2-carboxyl)benzoyl-N(5)-(2-fluoro-1-iminoethyl)-l-ornithine amide (o-F-amidine) and N-α-(2-carboxyl)benzoyl-N(5)-(2-chloro-1-iminoethyl)-l-ornithine amide (o-Cl-amidine) as second generation protein arginine deiminase (PAD) inhibitors. J Med Chem 2011; 54:6919-35. [PMID: 21882827 DOI: 10.1021/jm2008985] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Protein arginine deiminase (PAD) activity is upregulated in a number of human diseases, including rheumatoid arthritis, ulcerative colitis, and cancer. These enzymes, there are five in humans (PADs 1-4 and 6), regulate gene transcription, cellular differentiation, and the innate immune response. Building on our successful generation of F- and Cl-amidine, which irreversibly inhibit all of the PADs, a structure-activity relationship was performed to develop second generation compounds with improved potency and selectivity. Incorporation of a carboxylate ortho to the backbone amide resulted in the identification of N-α-(2-carboxyl)benzoyl-N(5)-(2-fluoro-1-iminoethyl)-l-ornithine amide (o-F-amidine) and N-α-(2-carboxyl)benzoyl-N(5)-(2-chloro-1-iminoethyl)-l-ornithine amide (o-Cl-amidine), as PAD inactivators with improved potency (up to 65-fold) and selectivity (up to 25-fold). Relative to F- and Cl-amidine, the compounds also show enhanced potency in cellulo. As such, these compounds will be versatile chemical probes of PAD function.
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Affiliation(s)
- Corey P Causey
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, Florida 33458, United States
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104
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Abstract
Rheumatoid arthritis (RA) is an autoimmune disease characterized by autoantibodies against citrullinated antigens. The importance of citrulline for the epitopes bound by these autoantibodies, referred to as ACPA (anti-citrullinated peptide/protein antibodies), was first described in 1998. In addition to citrullinated proteins, cyclic citrullinated peptides (CCP) can also be used as test substrates for detecting ACPA. The standard test for these antibodies is the second-generation CCP (CCP2) test, which is one of the best in terms of sensitivity and specificity. The generation of ACPA is an early event in the disease course, and is dependent on the presence of certain MHC class II alleles. ACPA in the inflamed synovium have been shown to associate with citrullinated antigens to form immune complexes, resulting in progression of the inflammatory process. The involvement of ACPA in the chronicity of RA is probably the reason why ACPA-positive patients have a more erosive disease course than ACPA-negative patients. The presence of ACPA has been included in the 2010 RA classification criteria. Thus, it is important to further standardize ACPA testing, for example by including an internal serum standard, which may lead to a better distinction between low and high ACPA levels.
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106
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High throughput proteomic analysis of the secretome in an explant model of articular cartilage inflammation. J Proteomics 2011; 74:704-15. [PMID: 21354348 PMCID: PMC3078332 DOI: 10.1016/j.jprot.2011.02.017] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Revised: 01/26/2011] [Accepted: 02/15/2011] [Indexed: 11/24/2022]
Abstract
This study employed a targeted high-throughput proteomic approach to identify the major proteins present in the secretome of articular cartilage. Explants from equine metacarpophalangeal joints were incubated alone or with interleukin-1beta (IL-1β, 10ng/ml), with or without carprofen, a non-steroidal anti-inflammatory drug, for six days. After tryptic digestion of culture medium supernatants, resulting peptides were separated by HPLC and detected in a Bruker amaZon ion trap instrument. The five most abundant peptides in each MS scan were fragmented and the fragmentation patterns compared to mammalian entries in the Swiss-Prot database, using the Mascot search engine. Tryptic peptides originating from aggrecan core protein, cartilage oligomeric matrix protein (COMP), fibronectin, fibromodulin, thrombospondin-1 (TSP-1), clusterin (CLU), cartilage intermediate layer protein-1 (CILP-1), chondroadherin (CHAD) and matrix metalloproteinases MMP-1 and MMP-3 were detected. Quantitative western blotting confirmed the presence of CILP-1, CLU, MMP-1, MMP-3 and TSP-1. Treatment with IL-1β increased MMP-1, MMP-3 and TSP-1 and decreased the CLU precursor but did not affect CILP-1 and CLU levels. Many of the proteins identified have well-established extracellular matrix functions and are involved in early repair/stress responses in cartilage. This high throughput approach may be used to study the changes that occur in the early stages of osteoarthritis.
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