title: Metalloproteases and their inhibitors are altered in both torn and intact rotator cuff tendons.
abstract: BACKGROUND
  We evaluated the role of matrix metalloproteases (MMPs) and their inhibitors which are involved in extracellular matrix remodeling and degradation, in the pathogenesis of chronic rotator cuff tears.
  
  
  METHODS
  Tendon samples were harvested from 13 patients who underwent arthroscopic repair of a rotator cuff tear. Supraspinatus biopsy specimens were harvested en bloc from the arthroscopically intact middle portion of the tendon more than 1 cm from the torn edge, from the lateral edge of the tear, and from the superior one third of the macroscopically intact subscapularis tendon used as control. Histological analysis and an evaluation of the activity of specific metalloproteases and the tissue inhibitors of metalloprotease (TIMP-1, TIMP-2) was done blindly by multiplex sandwich ELISA (Search-Light technology) in each specimen
  
  
  RESULTS
  Histological evidence of tendinopathy was present in all patients with a tear of the rotator cuff, and not in the macroscopically intact subscapularis tendon. There was a significant increase in MMP 1, MMP 2, MMP 3 and in TIMP-1, TIMP-2 levels in all specimens examined, including the macroscopically intact portion of the supraspinatus tendon and in the control specimens
  
  
  CONCLUSIONS
  The tissue in the ruptured area of the supraspinatus tendon undergoes marked rearrangement at molecular levels. This involves the activity of MMP 1, 2 and 3, and supports the critical role of MMPs in the tendon physiology. Seemingly intact parts of the injured supraspinatus tendon can present tendinopathic features, with altered cellular metabolism.
authors.affiliation: Unitá Chirurgia Spalla e gomito, IRCCS Istituto Humanitas, Milan, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Castagna
authors.forename: E
authors.initials: E
authors.lastname: Cesari
authors.forename: A
authors.initials: A
authors.lastname: Gigante
authors.forename: M
authors.initials: M
authors.lastname: Conti
authors.forename: R
authors.initials: R
authors.lastname: Garofalo
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D045726:Metalloproteases / Q000378:metabolism*; D008875:Middle Aged; D011446:Prospective Studies; D017006:Rotator Cuff / Q000033:anatomy & histology / Q000201:enzymology* / Q000473:pathology; D000070636:Rotator Cuff Injuries; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000378:metabolism*; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000378:metabolism*
chemical_list: C560822:TIMP1 protein, human; C560823:TIMP2 protein, human; D019715:Tissue Inhibitor of Metalloproteinase-1; D019716:Tissue Inhibitor of Metalloproteinase-2; D045726:Metalloproteases