title: Serum IgG antibodies to peptidylarginine deiminase 4 predict radiographic progression in patients with rheumatoid arthritis treated with tumour necrosis factor-alpha blocking agents.
abstract: BACKGROUND
  Peptidylarginine deiminase 4 (PAD4) may generate epitopes targeted by anticitrullinated protein antibodies in rheumatoid arthritis (RA). A subset of patients with RA has serum autoantibodies to human recombinant PAD4 (hPAD4). Here, we assessed whether anti-hPAD4 status in RA predicted disease outcome after antitumour necrosis factor (anti-TNF)-alpha therapy.
  
  
  METHODS
  We analysed RA sera obtained at baseline (n = 40) and after 1 year on anti-TNF-alpha therapy (n = 33) for anti-hPAD4 IgG. Association analyses between baseline anti-hPAD status and disease progression were performed.
  
  
  RESULTS
  We found that 17 of 40 patients (42.5%) were serum anti-hPAD4 positive at baseline, and the anti-hPAD4 IgG levels were stable over 1 year on anti-TNF-alpha therapy. At baseline, there were indications that anti-hPAD4 positive patients had more severe disease than the negative patients. After 1 year on anti-TNF-alpha therapy, the anti-hPAD4 positive patients displayed a persistently elevated disease activity score using 28 joint counts score and increased progression in the van der Heijde-modified Sharp erosion score. Accordingly, more anti-hPAD4 positive than negative patients presented an increase in van der Heijde-modified Sharp erosion scores >0 over 1 year.
  
  
  CONCLUSIONS
  Anti-hPAD4 IgG can be detected in a subset of RA sera and the levels are stable after initiation of anti-TNF-alpha therapy. Serum anti-hPAD4 may predict persistent disease activity and radiographic progression in patients with RA receiving anti-TNF-alpha therapy.
authors: Institute of Immunology, University of Oslo, Rikshospitalet University Hospital, Oslo, Norway. eirikhha@rr-research.no
authors: E H
authors: EH
authors: Halvorsen
authors: E A
authors: EA
authors: Haavardsholm
authors: S
authors: S
authors: Pollmann
authors: A
authors: A
authors: Boonen
authors: D
authors: D
authors: van der Heijde
authors: T K
authors: TK
authors: Kvien
authors: Ø
authors: Ø
authors: Molberg
mesh_terms: D000068879:Adalimumab; D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D061067:Antibodies, Monoclonal, Humanized; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood*; D018450:Disease Progression; D000068800:Etanercept; D005260:Female; D006801:Humans; D006867:Hydrolases / Q000276:immunology*; D007074:Immunoglobulin G / Q000097:blood / Q000627:therapeutic use; D000069285:Infliximab; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D000080002:Protein-Arginine Deiminase Type 4; D000076342:Protein-Arginine Deiminases; D011859:Radiography; D018124:Receptors, Tumor Necrosis Factor / Q000627:therapeutic use; D012720:Severity of Illness Index; D016896:Treatment Outcome; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors*
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D018501:Antirheumatic Agents; D001323:Autoantibodies; D007074:Immunoglobulin G; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D000069285:Infliximab; D006867:Hydrolases; C000629235:PADI4 protein, human; D000080002:Protein-Arginine Deiminase Type 4; D000076342:Protein-Arginine Deiminases; D000068879:Adalimumab; D000068800:Etanercept