title: Prevalence and significance of anti-peptidylarginine deiminase 4 antibodies in rheumatoid arthritis.
abstract: OBJECTIVE
  To detect anti-peptidylarginine deiminase 4 (PAD4) antibody in patients with rheumatoid arthritis (RA) and to investigate its clinical significance in the pathogenesis of RA.
  
  
  METHODS
  Serum samples were obtained from 109 patients with RA, 67 systemic lupus erythematosus (SLE), 48 primary Sjögren's syndrome (pSS), 41 systemic sclerosis (SSc), 34 osteoarthritis (OA), 23 dermatomyositis/polymyositis (DM/PM), and 19 ankylosing spondylitis (AS) and 106 healthy individuals. The presence of antibodies against recombinant human PAD4 (anti-PAD4) was examined by ELISA. Associations between anti-PAD4 and the clinical features of RA were evaluated.
  
  
  RESULTS
  The prevalence of anti-PAD4 in RA patients (45.0%) was significantly higher than those of SLE (9.0%), pSS (4.2%), SSc (9.8%), OA (5.9%), DM/PM (13.0%), AS (0%), and controls (4.7%). The mean titer of anti-PAD4 in RA was also significantly higher than in SLE, other rheumatic diseases, and controls. Disease Activity Score-28 (DAS28), anti-cyclic citrullinated peptide (CCP) antibody, erythrocyte sedimentation rate, rheumatoid factor, IgM, and IgG in anti-PAD4-positive patients were all higher than in anti-PAD4-negative patients. There were positive correlations between anti-PAD4 and DAS28 score (r = 0.333, p < 0.01) and anti-CCP antibody (r = 0.248, p < 0.05).
  
  
  CONCLUSIONS
  The presence of anti-PAD4 in RA indicates that PAD4 may act as an autoantigen that may play a role in the pathogenesis of RA.
authors.affiliation: Department of Rheumatology and Immunology, People's Hospital, Peking University, Beijing, China.
authors.forename: Jinxia
authors.initials: J
authors.lastname: Zhao
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhao
authors.forename: Jing
authors.initials: J
authors.lastname: He
authors.forename: Rulin
authors.initials: R
authors.lastname: Jia
authors.forename: Zhanguo
authors.initials: Z
authors.lastname: Li
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D006867:Hydrolases / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D010456:Peptides, Cyclic / Q000276:immunology; D000080002:Protein-Arginine Deiminase Type 4; D000076342:Protein-Arginine Deiminases; D012720:Severity of Illness Index
chemical_list: D001323:Autoantibodies; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide; D006867:Hydrolases; C000629235:PADI4 protein, human; D000080002:Protein-Arginine Deiminase Type 4; D000076342:Protein-Arginine Deiminases