title: Increased plasma osteopontin in frequent exacerbator and acute exacerbation of COPD.
abstract: BACKGROUND
  Osteopontin (OPN) is a phosphorylated glycoprotein expressed by diverse tissues including bone, brain, kidney, liver and lung. Limited data exist regarding OPN in chronic obstructive pulmonary disease (COPD) and the exacerbation of this condition.
  
  
  OBJECTIVE
  The aim of this study was to evaluate plasma OPN levels and investigate the clinical usefulness of plasma OPN measurement in patients with COPD.
  
  
  METHODS
  Plasma OPN levels were measured and compared in patients with COPD exacerbation (n = 64), patients with stable COPD (n = 68) and healthy controls (n = 30). In patients with COPD exacerbation, plasma OPN levels were measured repeatedly in convalescence. Patients with stable COPD were categorized into frequent and infrequent exacerbators according to their frequency of exacerbation, and plasma OPN levels were compared between these two groups. Plasma OPN levels were determined by enzyme-linked immunosorbent assay.
  
  
  RESULTS
  Patients with COPD exacerbation had increased plasma OPN levels compared with those with stable COPD and healthy controls (32.6 ± 29.6, 17.6 ± 11.1, 8.4 ± 6.1 ng/mL, respectively; P < 0.001). In patients with COPD exacerbation, plasma OPN levels were significantly decreased in convalescence (44.8 ± 43.5 vs 24.6 ± 13.6 ng/mL; P = 0.034). Frequent exacerbators had higher plasma OPN levels compared with infrequent exacerbators (22.5 ± 12.0 vs 15.0 ± 9.8 ng/mL; P = 0.008).
  
  
  CONCLUSIONS
  Plasma OPN levels were increased in patients with COPD exacerbation and frequent exacerbators, which suggests a possible role for OPN as a biomarker of COPD exacerbation.
authors.affiliation: Division Pulmonology and Allergy, Department of Internal Medicine, College of Medicine, Gyeongsang National University, Jinju, Korea.
authors.forename: Seung Jun
authors.initials: SJ
authors.lastname: Lee
authors.forename: Sung Hwan
authors.initials: SH
authors.lastname: Kim
authors.forename: Wanchul
authors.initials: W
authors.lastname: Kim
authors.forename: Sujin
authors.initials: S
authors.lastname: Lim
authors.forename: Seung Hun
authors.initials: SH
authors.lastname: Lee
authors.forename: Yu Eun
authors.initials: YE
authors.lastname: Kim
authors.forename: Yu Ji
authors.initials: YJ
authors.lastname: Cho
authors.forename: Yi Yeong
authors.initials: YY
authors.lastname: Jeong
authors.forename: Ho Cheol
authors.initials: HC
authors.lastname: Kim
authors.forename: Jong Deog
authors.initials: JD
authors.lastname: Lee
authors.forename: Young Sil
authors.initials: YS
authors.lastname: Hwang
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D003289:Convalescence; D005260:Female; D006801:Humans; D008297:Male; D053495:Osteopontin / Q000097:blood*; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood*
chemical_list: D015415:Biomarkers; D053495:Osteopontin
keywords: biomarker; chronic obstructive pulmonary disease; convalescence; disease exacerbation; osteopontin