title: Proteomic analysis of secreted proteins in early rheumatoid arthritis: anti-citrulline autoreactivity is associated with up regulation of proinflammatory cytokines.
abstract: OBJECTIVE
  To identify peripheral blood autoantibody and cytokine profiles that characterise clinically relevant subgroups of patients with early rheumatoid arthritis using arthritis antigen microarrays and a multiplex cytokine assay.
  
  
  METHODS
  Serum samples from 56 patients with a diagnosis of rheumatoid arthritis of <6 months' duration were tested. Cytokine profiles were also determined in samples from patients with psoriatic arthritis (PsA) and ankylosing spondylitis (n = 21), and from healthy individuals (n = 19). Data were analysed using Kruskal-Wallis test with Dunn's adjustment for multiple comparisons, linear correlation tests, significance analysis of microarrays (SAM) and hierarchical clustering software.
  
  
  RESULTS
  Distinct antibody profiles were associated with subgroups of patients who exhibited high serum levels of tumour necrosis factor (TNF)alpha, interleukin (IL)1beta, IL6, IL13, IL15 and granulocyte macrophage colony-stimulating factor. Significantly increased autoantibody reactivity against citrullinated epitopes was observed in patients within the cytokine "high" subgroup. Increased levels of TNFalpha, IL1alpha, IL12p40 and IL13, and the chemokines eotaxin/CCL11, monocyte chemoattractant protein-1 and interferon-inducible protein 10, were present in early rheumatoid arthritis as compared with controls (p<0.001). Chemokines showed some of the most impressive differences. Only IL8/CXCL8 concentrations were higher in patients with PsA/ankylosing spondylitis (p = 0.02).
  
  
  CONCLUSIONS
  Increased blood levels of proinflammatory cytokines are associated with autoantibody targeting of citrullinated antigens and surrogate markers of disease activity in patients with early rheumatoid arthritis. Proteomic analysis of serum autoantibodies, cytokines and chemokines enables stratification of patients with early rheumatoid arthritis into molecular subgroups.
authors.affiliation: Division of Immunology and Rheumatology, Department of Medicine, Stanford University School of Medicine, and Palo Alto VA Health Care System, MC 154R, 3801 Miranda Avenue, Palo Alto, CA 94304, USA. whueber@stanford.edu
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Hueber
authors.forename: Beren H
authors.initials: BH
authors.lastname: Tomooka
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Zhao
authors.forename: Brian A
authors.initials: BA
authors.lastname: Kidd
authors.forename: Jan W
authors.initials: JW
authors.lastname: Drijfhout
authors.forename: James F
authors.initials: JF
authors.lastname: Fries
authors.forename: Walther J
authors.initials: WJ
authors.lastname: van Venrooij
authors.forename: Allan L
authors.initials: AL
authors.lastname: Metzger
authors.forename: Mark C
authors.initials: MC
authors.lastname: Genovese
authors.forename: William H
authors.initials: WH
authors.lastname: Robinson
mesh_terms: D000328:Adult; D000368:Aged; D015535:Arthritis, Psoriatic / Q000276:immunology; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood*; D001324:Autoantigens / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D018925:Chemokines / Q000097:blood; D002956:Citrulline / Q000276:immunology*; D016207:Cytokines / Q000096:biosynthesis* / Q000097:blood; D005260:Female; D006801:Humans; D018836:Inflammation Mediators / Q000097:blood*; D008297:Male; D008875:Middle Aged; D040081:Protein Array Analysis / Q000379:methods; D040901:Proteomics; D013167:Spondylitis, Ankylosing / Q000276:immunology; D015854:Up-Regulation
chemical_list: D001323:Autoantibodies; D001324:Autoantigens; D015415:Biomarkers; D018925:Chemokines; D016207:Cytokines; D018836:Inflammation Mediators; D002956:Citrulline