title: Circulating matrix metalloproteinase 9 levels in relation to sampling methods, femoral and carotid atherosclerosis.
abstract: OBJECTIVE
  To examine whether circulating levels of matrix metalloproteinase 9 (MMP-9) were associated with ultrasound-assessed intima-media thickness (IMT) and echolucent plaques in the carotid and femoral arteries. To examine preanalytical sources of variability in MMP-9 concentrations related to sampling procedures.
  
  
  METHODS
  Plasma and serum MMP-9 levels were compared with ultrasound assessed measures of femoral and carotid atherosclerosis, in a cross-sectional study of 61-year-old men (n = 473). Preanalytical sources of variability in MMP-9 levels were examined in 10 healthy subjects. Main outcome measures were circulating levels of MMP-9 in serum and plasma, IMT of the carotid and femoral arteries, and plaque status based on size and echolucency.
  
  
  METHODS
  Research unit at university hospital.
  
  
  RESULTS
  Plasma concentrations of total and active MMP-9 were associated with femoral artery IMT independently of traditional cardiovascular risk factors, and were higher in subjects with moderate to large femoral plaques. Plasma MMP-9 concentration was higher in men with echolucent femoral plaques (P = 0.006) compared with subjects without femoral plaques. No similar associations were found for carotid plaques. MMP-9 concentrations were higher in serum than in plasma, and higher when sampling was performed with Vacutainer than with syringe. MMP-9 levels in serum were more strongly associated with peripheral neutrophil count compared with MMP-9 levels in plasma.
  
  
  CONCLUSIONS
  Plasma MMP-9 levels were associated with atherosclerosis in the femoral artery, and total MMP-9 concentration was higher in men with echolucent femoral plaques. The choice of sample material and sampling method affect the measurements of circulating MMP-9 levels.
authors.affiliation: Wallenberg Laboratory for Cardiovascular Research, Sahlgrenska Academy at Göteborg University, Göteborg, Sweden. fredrik.olson@wlab.gu.se
authors.forename: F J
authors.initials: FJ
authors.lastname: Olson
authors.forename: C
authors.initials: C
authors.lastname: Schmidt
authors.forename: A
authors.initials: A
authors.lastname: Gummesson
authors.forename: V
authors.initials: V
authors.lastname: Sigurdardottir
authors.forename: J
authors.initials: J
authors.lastname: Hulthe
authors.forename: O
authors.initials: O
authors.lastname: Wiklund
authors.forename: B
authors.initials: B
authors.lastname: Fagerberg
mesh_terms: D050197:Atherosclerosis / Q000000981:diagnostic imaging / Q000201:enzymology* / Q000473:pathology; D015415:Biomarkers / Q000097:blood; D001800:Blood Specimen Collection / Q000379:methods; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging / Q000201:enzymology / Q000473:pathology; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging / Q000473:pathology; D005263:Femoral Artery / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000097:blood*; D008875:Middle Aged; D012307:Risk Factors; D017539:Tunica Intima / Q000000981:diagnostic imaging / Q000473:pathology; D017540:Tunica Media / Q000000981:diagnostic imaging / Q000473:pathology; D014463:Ultrasonography
chemical_list: D015415:Biomarkers; D020780:Matrix Metalloproteinase 9