title: Stromal expression of matrix metalloprotease-9 in middle ear cholesteatomas.
abstract: BACKGROUND
  Matrix metalloprotease-9 (MMP-9) plays an important role in the degradation of extracellular matrix (ECM). In cholesteatoma there are significant changes in the composition of the ECM, supporting the view of a disturbed cell-ECM interaction. It has been reported that in cholesteatoma tissues, MMP-9 is expressed in epithelial cells but not in stromal cells. In this study, we report conflicting results regarding the identity of the cholesteatoma cells that express MMP-9.
  
  
  METHODS
  An immunohistochemical assay was performed to examine the expression of MMP-9 in 25 cases (formalin-fixed paraffin-embedded sections) of cholesteatoma, using an MMP-9-specific monoclonal antibody.
  
  
  RESULTS
  In all cholesteatomas examined, MMP-9 was expressed in the stromal cells but not in the epithelial cells. MMP-9 immunostaining was undetectable in external auditory meatal skin (n = 5) and tympanic membrane (n = 3).
  
  
  CONCLUSIONS
  These results suggest that the MMP-9 expressed in stromal cells may be involved in the disturbed cell-ECM interaction associated with the process of cholesteatoma formation.
authors.affiliation: Department of Otolaryngology, St. Marianna University School of Medicine, Kawasaki, Kanagawa, Japan.
authors.forename: E
authors.initials: E
authors.lastname: Shibosawa
authors.forename: K
authors.initials: K
authors.lastname: Tsutsumi
authors.forename: T
authors.initials: T
authors.lastname: Takakuwa
authors.forename: S
authors.initials: S
authors.lastname: Takahashi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal; D002648:Child; D018424:Cholesteatoma, Middle Ear / Q000201:enzymology* / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D008875:Middle Aged; D017154:Stromal Cells / Q000201:enzymology / Q000473:pathology
chemical_list: D000911:Antibodies, Monoclonal; D020780:Matrix Metalloproteinase 9