title: Increased levels of serum myeloperoxidase in patients with active rheumatoid arthritis.
abstract: OBJECTIVE
  The clinical significance of myeloperoxidase (MPO) has been the focus of investigation because it may contribute to the chronic, non-microbial inflammatory process in various diseases. Here, we determined serum MPO levels in rheumatoid arthritis (RA) and other autoimmune or inflammatory conditions, and investigated the associations between MPO levels and disease activity indicators in RA.
  
  
  METHODS
  The distribution of MPO was determined in serum samples from patients with RA, systemic lupus erythematosus (SLE), primary Sjögren's syndrome (pSS), dermatomyositis (DM), or ankylosing spondylitis (AS) and from healthy controls using commercial ELISA kits. Associations of serum MPO levels with the disease variables of RA patients were evaluated.
  
  
  RESULTS
  All patient samples analyzed showed higher serum levels of MPO than healthy controls. Furthermore, MPO levels in RA were significantly higher than those in the other diseases with the exception of DM. Higher MPO levels were observed in RA patients with increased C-reactive protein (p=0.005) or neutrophil percentage (p<0.001), as well as in those with highly active disease (p<0.001). Moderate positive correlations between MPO levels and IgM (r=0.334, p=0.001), C-reactive protein (r=0.293, p=0.003), erythrocyte sedimentation rate (r=0.240, p=0.016), or DAS28 (r=0.350, p<0.001) were also demonstrated.
  
  
  CONCLUSIONS
  The MPO concentration is likely to increase in patients with chronic inflammation. The associations between MPO and the disease variables of RA patients support a role for MPO in the inflammatory process of the disease.
authors.affiliation: Department of Clinical Laboratory, Xiangya Hospital, Central South University, Changsha, Hunan, PR China. Electronic address: weiweiwang1983@163.com.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Department of Clinical Laboratory, Xiangya Hospital, Central South University, Changsha, Hunan, PR China.
authors.forename: Zijuan
authors.initials: Z
authors.lastname: Jian
authors.affiliation: Department of Clinical Laboratory, Xiangya Hospital, Central South University, Changsha, Hunan, PR China.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Guo
authors.affiliation: Department of Clinical Laboratory, The First Affiliated Hospital of Hunan University of Chinese Medicine, Changsha, Hunan, PR China.
authors.forename: Xingwang
authors.initials: X
authors.lastname: Ning
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000503:physiopathology*; D015415:Biomarkers / Q000378:metabolism; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000378:metabolism; D016022:Case-Control Studies; D003882:Dermatomyositis / Q000503:physiopathology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007249:Inflammation / Q000503:physiopathology*; D008180:Lupus Erythematosus, Systemic / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009195:Peroxidase / Q000097:blood*; D012859:Sjogren's Syndrome / Q000503:physiopathology; D013167:Spondylitis, Ankylosing / Q000503:physiopathology
chemical_list: D015415:Biomarkers; D002097:C-Reactive Protein; D009195:Peroxidase
keywords: Inflammation; Myeloperoxidase; Oxidative stress; Rheumatoid arthritis