title: MMP protein and activity levels in synovial fluid from patients with joint injury, inflammatory arthritis, and osteoarthritis.
abstract: OBJECTIVE
  To determine protein and activity levels of matrix metalloproteinases 1 and 3 (MMP-1 and MMP-3) in synovial fluid of patients with knee joint injury, primary osteoarthritis, and acute pyrophosphate arthritis (pseudogout).
  
  
  METHODS
  Measurements were done on knee synovial fluid obtained in a cross sectional study of cases of injury (n = 283), osteoarthritis (n = 105), and pseudogout (n = 65), and in healthy controls (n = 35). Activity of MMP-1 and MMP-3 in alpha(2) macroglobulin complexes was measured using specific low molecular weight fluorogenic substrates. ProMMP-1, proMMP-3, and TIMP-1 (tissue inhibitor of metalloproteinase 1) were quantified by immunoassay.
  
  
  RESULTS
  Mean levels of proMMP-1, proMMP-3, and TIMP-1 were increased in injury, osteoarthritis, and pseudogout compared with controls. MMP-1 activity was increased in pseudogout and injury groups over control levels, whereas MMP-3 activity was increased only in the pseudogout group. The increase in MMP-1 activity coincided with a decrease in TIMP-1 levels in the injury group.
  
  
  CONCLUSIONS
  Patients with joint injury have a persistent increase in proMMP-1 and proMMP-3 in synovial fluid and an increase in activated MMPs, which are not inhibited by TIMP. The differences in activation and inhibition patterns between the study groups are consistent with disease specific patterns of MMP activation and/or inhibition in joint pathology.
authors.affiliation: Division of Biomedical Research, TNO Prevention and Health, PO Box 2215, 2301 CE, Leiden, Netherlands.
authors.forename: I
authors.initials: I
authors.lastname: Tchetverikov
authors.forename: L S
authors.initials: LS
authors.lastname: Lohmander
authors.forename: N
authors.initials: N
authors.lastname: Verzijl
authors.forename: T W J
authors.initials: TW
authors.lastname: Huizinga
authors.forename: J M
authors.initials: JM
authors.lastname: TeKoppele
authors.forename: R
authors.initials: R
authors.lastname: Hanemaaijer
authors.forename: J
authors.initials: J
authors.lastname: DeGroot
mesh_terms: D000208:Acute Disease; D000328:Adult; D001168:Arthritis / Q000201:enzymology / Q000378:metabolism*; D002805:Chondrocalcinosis / Q000201:enzymology / Q000378:metabolism; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D020782:Matrix Metalloproteinases / Q000378:metabolism*; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000201:enzymology / Q000378:metabolism; D013582:Synovial Fluid / Q000201:enzymology / Q000378:metabolism*; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000378:metabolism; D000511:alpha-Macroglobulins / Q000378:metabolism
chemical_list: D019715:Tissue Inhibitor of Metalloproteinase-1; D000511:alpha-Macroglobulins; D020782:Matrix Metalloproteinases