title: The role of catalase in pulmonary fibrosis.
abstract: BACKGROUND
  Catalase is preferentially expressed in bronchiolar and alveolar epithelial cells, and acts as an endogenous antioxidant enzyme in normal lungs. We thus postulated epithelial damage would be associated with a functional deficiency of catalase during the development of lung fibrosis.
  
  
  METHODS
  The present study evaluates the expression of catalase mRNA and protein in human interstitial pneumonias and in mouse bleomycin-induced lung injury. We examined the degree of bleomycin-induced inflammation and fibrosis in the mice with lowered catalase activity.
  
  
  RESULTS
  In humans, catalase was decreased at the levels of activity, protein content and mRNA expression in fibrotic lungs (n = 12) compared to control lungs (n = 10). Immunohistochemistry revealed a decrease in catalase in bronchiolar epithelium and abnormal re-epithelialization in fibrotic areas. In C57BL/6J mice, catalase activity was suppressed along with downregulation of catalase mRNA in whole lung homogenates after bleomycin administration. In acatalasemic mice, neutrophilic inflammation was prolonged until 14 days, and there was a higher degree of lung fibrosis in association with a higher level of transforming growth factor-β expression and total collagen content following bleomycin treatment compared to wild-type mice.
  
  
  CONCLUSIONS
  Taken together, these findings demonstrate diminished catalase expression and activity in human pulmonary fibrosis and suggest the protective role of catalase against bleomycin-induced inflammation and subsequent fibrosis.
authors.affiliation: First Department of Medicine, Hokkaido University School of Medicine, N-15, W-7, Kita-ku, Sapporo 060-8638, Japan. bytomoko@med.hokudai.ac.jp
authors.forename: Nao
authors.initials: N
authors.lastname: Odajima
authors.forename: Tomoko
authors.initials: T
authors.lastname: Betsuyaku
authors.forename: Katsura
authors.initials: K
authors.lastname: Nagai
authors.forename: Chinatsu
authors.initials: C
authors.lastname: Moriyama
authors.forename: Da-Hong
authors.initials: DH
authors.lastname: Wang
authors.forename: Tomoko
authors.initials: T
authors.lastname: Takigawa
authors.forename: Keiki
authors.initials: K
authors.lastname: Ogino
authors.forename: Masaharu
authors.initials: M
authors.lastname: Nishimura
mesh_terms: D000818:Animals; D002374:Catalase / Q000378:metabolism*; D005260:Female; D006801:Humans; D008168:Lung / Q000201:enzymology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008875:Middle Aged; D011658:Pulmonary Fibrosis / Q000201:enzymology*; D014018:Tissue Distribution
chemical_list: D002374:Catalase