title: Increased serum levels of C-reactive protein and matrix metalloproteinase-9 in obstructive sleep apnea syndrome.
abstract: BACKGROUND
  Obstructive sleep apnea syndrome (OSAS), characterized by intermittent hypoxia/reoxygenation (IHR), has been identified as an independent risk factor for cardiovascular diseases (CVD). The CVD biomarkers associated with OSAS have not been thoroughly investigated.
  
  
  METHODS
  Fifty-one men with OSAS recently diagnosed by polysomnography were classified into two groups according to the severity of apnea: moderate to severe OSAS group (n = 28) and mild OSAS group (n = 23). Twenty-five obese men, of comparable age and body mass index (BMI), without OSAS were chosen as control subjects. Serum metabolic variables, C-reactive protein (CRP) and matrix metalloproteinase-9 (MMP-9) were measured. Spearman correlation and regression analysis were performed.
  
  
  RESULTS
  Serum concentrations of CRP and MMP-9 were significantly higher in 51 OSAS patients than in 25 control subjects. Levels of CRP and MMP-9 were significantly higher in patients with moderate to severe OSAS than in patients with mild OSAS or in obese control subjects. A positive correlation was found between levels of CRP and MMP-9 in OSAS patients. Regression analysis showed that after adjusting for age and BMI, apnea/hypopnea index (AHI) significantly correlated with serum concentrations of CRP and MMP-9 in patients with OSAS.
  
  
  CONCLUSIONS
  AHI, mirroring the frequency of IHR, was a predictor of enhanced circulating CVD biomarkers MMP-9 and CRP. Our data support the theory that IHR contributes to the upregulation of the inflammatory factors in OSAS patients.
authors.affiliation: Sleep Disorders Centre and Department of Otolaryngology-Head and Neck Surgery, Third Affiliated Hospital of Sun Yat-sen University, Guangzhou 510630, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Ye
authors.forename: Hui
authors.initials: H
authors.lastname: Liu
authors.forename: Yuan
authors.initials: Y
authors.lastname: Li
authors.forename: Xian
authors.initials: X
authors.lastname: Liu
authors.forename: Jie-ming
authors.initials: JM
authors.lastname: Zhu
mesh_terms: D000328:Adult; D000368:Aged; D002097:C-Reactive Protein / Q000032:analysis*; D002318:Cardiovascular Diseases / Q000209:etiology; D006801:Humans; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000097:blood*; D008875:Middle Aged; D020181:Sleep Apnea, Obstructive / Q000097:blood* / Q000150:complications
chemical_list: D002097:C-Reactive Protein; D020780:Matrix Metalloproteinase 9