Expression of transforming growth factor‐β1 and tumour necrosis factor‐α in bronchoalveolar lavage cells in murine pulmonary fibrosis after intraperitoneal administration of bleomycin

Objective : We previously observed increased expression of interleukin‐1β, platelet‐derived growth factor‐A, and insulin‐like growth factor‐I in bronchoalveolar lavage (BAL) cells during the development of pulmonary fibrosis after an intraperitoneal administration of bleomycin in mice. The purpose of this study was to investigate the roles of tumour necrosis factor (TNF)‐α and transforming growth factor (TGF)‐β1 in this model. Methodology : We investigated the mRNA expression levels of TNF‐α and TGF‐β1 in BAL cells of Institute for Cancer Research mice after 10 days of the intraperitoneal administration of bleomycin with or without treatment with a specific neutrophil elastase inhibitor, ONO‐5046·Na. Results : On day 1 but not on days 15 and 29, the relative amount of TGF‐β1 mRNA in the bleomycin‐treated mice was significantly decreased compared with control mice. In the mice treated with both bleomycin and ONO‐5046·Na intermediate values for TGF‐β1 were obtained. No significant differences in TNF‐α expression were observed in any of the treatment groups. Conclusions : These results suggest that a reduced expression of TGF‐β1 in BAL cells in the early phase may be important during the development of murine pulmonary fibrosis induced by an intraperitoneal administration of bleomycin.