title: [A study on expression of tumor necrosis factor alpha in middle ear cholesteatoma and its effect on bone destruction].
abstract: OBJECTIVE
  To determine the expression and localization of tumor necrosis factor alpha (TNF-alpha) in human middle ear cholesteatoma and its effects on bone resorption.
  
  
  METHODS
  The distribution of TNF-alpha in 18 cholesteatoma tissues and 8 normal external ear canal skin, facial skin and tympanic membrane were studied immunohistochemically with paraffin-embedded sections.
  
  
  RESULTS
  TNF-alpha was localized in the epithelium and connective tissue of cholesteatomas studied, particularly on basal and spinous cells and macrophages. The epithelium of normal external ear canal skin, facial skin and tympanic membrane was slightly stained.
  
  
  CONCLUSIONS
  This study revealed significantly increased level of TNF-alpha in cholesteatoma tissues. TNF-alpha acts both directly, by causing bone erosion as an autocrine growth factor, and indirectly as an important mediator by stimulating the release of enzymes causing bone destruction.
authors.affiliation: Department of Otolaryngology, 163 Hospital of PLA, Changsha 410003.
authors.forename: Z
authors.initials: Z
authors.lastname: Li
authors.forename: X
authors.initials: X
authors.lastname: Li
authors.forename: G
authors.initials: G
authors.lastname: Liu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001862:Bone Resorption; D002648:Child; D018424:Cholesteatoma, Middle Ear / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis* / Q000502:physiology
chemical_list: D014409:Tumor Necrosis Factor-alpha