The role of catalase in pulmonary fibrosis.
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.[1]References
- The role of catalase in pulmonary fibrosis. Odajima, N., Betsuyaku, T., Nagai, K., Moriyama, C., Wang, D.H., Takigawa, T., Ogino, K., Nishimura, M. Respir. Res. (2010) [Pubmed]
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