title: Circulating Dickkopf-1 is correlated with bone erosion and inflammation in rheumatoid arthritis.
abstract: OBJECTIVE
  To explore the potential role of Dickkopf-1 (DKK-1) in rheumatoid arthritis (RA) and to evaluate the effect of a tumor necrosis factor-α (TNF-α) inhibitor (infliximab) and an interleukin 1 receptor antagonist (IL-1Ra; anakinra) on DKK-1 secretion in patients with RA.
  
  
  METHODS
  Serum samples were collected from 100 patients with RA, 100 patients with other rheumatic diseases (e.g., osteoarthritis and ankylosing spondylitis), and 40 healthy controls. DKK-1 and osteoprotegerin (OPG) levels in serum were detected by ELISA. Serum C-reactive protein (CRP) levels, erythrocyte sedimentation rates (ESR), rheumatoid factor (RF) titers, and anti-cyclic citrullinated peptide antibody were also measured in patients with RA.
  
  
  RESULTS
  The serum level of DKK-1 was significantly higher in patients with RA than in healthy controls and those with other rheumatic diseases (p < 0.01); the serum DKK-1 level was correlated with levels of CRP (r = 0.488, p = 0.003) and ESR (r = 0.458, p = 2.4 x 10(-4)) and the Sharp score of radiologic change (r = 0.449, p = 0.001) in RA. In contrast to the increasing level of OPG, DKK-1 was significantly decreased in RA patients treated with TNF-α inhibitor (p < 0.01). DKK-1 was significantly decreased in RA patients treated with IL-1Ra (p < 0.01).
  
  
  CONCLUSIONS
  DKK-1, as an important mediator, was correlated with bone erosion and inflammation in RA. The change of DKK-1 level may serve as a biomarker of disease activity and bone erosion.
authors.affiliation: Department of Rheumatology and Immunology, Clinical Immunology Center, Beijing University People's Hospital, 11 Xizhimen South Street, Beijing, China.
authors.forename: Shi-Yao
authors.initials: SY
authors.lastname: Wang
authors.forename: Yan-Ying
authors.initials: YY
authors.lastname: Liu
authors.forename: Hua
authors.initials: H
authors.lastname: Ye
authors.forename: Jian-Ping
authors.initials: JP
authors.lastname: Guo
authors.forename: Ru
authors.initials: R
authors.lastname: Li
authors.forename: Xia
authors.initials: X
authors.lastname: Liu
authors.forename: Zhan-Guo
authors.initials: ZG
authors.lastname: Li
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000097:blood* / Q000188:drug therapy; D001862:Bone Resorption / Q000097:blood*; D002097:C-Reactive Protein / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007249:Inflammation / Q000097:blood*; D036341:Intercellular Signaling Peptides and Proteins / Q000097:blood*; D053590:Interleukin 1 Receptor Antagonist Protein / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D053244:Osteoprotegerin / Q000097:blood; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors; D055815:Young Adult
chemical_list: C501126:DKK1 protein, human; D036341:Intercellular Signaling Peptides and Proteins; D053590:Interleukin 1 Receptor Antagonist Protein; D053244:Osteoprotegerin; D014409:Tumor Necrosis Factor-alpha; D002097:C-Reactive Protein