Role of Anti–Carbamylated Protein Antibodies Compared to Anti–Citrullinated Protein Antibodies in Indigenous North Americans With Rheumatoid Arthritis, Their First‐Degree Relatives, and Healthy Controls
Objective Rheumatoid arthritis (RA) is characterized by the presence of autoantibodies, including seropositivity for rheumatoid factor (RF) and anti–citrullinated protein antibodies (ACPAs). In addition, antibodies to carbamylated proteins (anti‐CarP) are present in patients with RA and are associat...
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Published in | Arthritis & rheumatology (Hoboken, N.J.) Vol. 68; no. 9; pp. 2090 - 2098 |
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Main Authors | , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
Wiley Subscription Services, Inc
01.09.2016
John Wiley and Sons Inc |
Subjects | |
Online Access | Get full text |
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Summary: | Objective
Rheumatoid arthritis (RA) is characterized by the presence of autoantibodies, including seropositivity for rheumatoid factor (RF) and anti–citrullinated protein antibodies (ACPAs). In addition, antibodies to carbamylated proteins (anti‐CarP) are present in patients with RA and are associated with joint damage. This study was undertaken to assess the presence of anti‐CarP antibodies in indigenous North Americans (First Nations [FN] populations) with RA compared to their at‐risk first‐degree relatives (FDRs) and healthy controls.
Methods
Anti‐CarP IgG and ACPAs (specifically, anti–cyclic citrullinated peptide [anti‐CCP] antibodies) were measured by enzyme‐linked immunosorbent assay in the sera of FN patients with RA (n = 95), their unaffected FDRs (n = 109), and healthy FN controls (n = 85). Antibodies to additional citrullinated peptides were measured using a multiplex ACPA array, and the number of peptides recognized was reported as an ACPA score. Groups were compared using the chi‐square test and Mann‐Whitney U test. Associations between RA and seropositivity for RF, ACPAs, and anti‐CarP antibodies were determined by logistic regression.
Results
Anti‐CarP antibodies were more frequent in FN patients with RA (44.3%) compared to FDRs (18.3%) and FN controls (4.7%) (both P < 0.0001 versus RA). Moreover, anti‐CarP antibodies were more frequent in FDRs than in FN controls (P = 0.008). The ACPA score was higher in anti‐CCP–positive FN patients with RA than in anti‐CCP–positive FN FDRs (median score 7 [interquartile range (IQR) 7] versus median score 1 [IQR 4]; P = 0.04). The association with RA was strongest when all 3 autoantibodies (RF, anti‐CCP, and anti‐CarP) were present in the patients’ serum (odds ratio 194, 95% confidence interval 23–1,609, P < 0.0001).
Conclusion
Anti‐CarP antibodies are prevalent in FN patients with RA and also more common in their at‐risk FDRs compared to healthy controls. The results indicate an association of RF, ACPAs, and anti‐CarP with RA that is strongest when all 3 autoantibodies are present. These findings may provide new insights into the evolution of autoimmunity in preclinical RA. |
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Bibliography: | Supported by the Canadian Institutes of Health Research (Institute of Musculoskeletal Health and Arthritis operating grant MOP‐77700), the European Union Seventh Framework Programme (project Euro‐TEAM; HEALTH‐2012‐INNOVATION‐1‐305549), and the Innovative Medicine Initiative Joint Undertaking–funded project BeTheCure (contract 115142‐2). Dr. Trouw's work was supported by a ZonMW Vidi grant from The Netherlands Organization for Scientific Research and by a fellowship from Janssen Biologics. Drs. Trouw, Huizinga, and Toes have submitted a patent application for the use of anti‐CarP antibodies as a diagnostic test. ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 2326-5191 2326-5205 |
DOI: | 10.1002/art.39664 |