Effects of interferon-gamma on bleomycin-induced pulmonary fibrosis in rats at the fibrosing stage

Objective: To observe the change of the levels of tumor necrosis factor-α(TNF-α),interferon-γ(IFN-γ) and interleukin-10(IL-10) in bronchial alveolar lavage fluid(BALF) from rats with pulmonary fibrosis induced by bleomycin and investigate the intervention by IFN-γ on it. Methods: The SD rats were randomly divided into three groups: the normal control group(Group N),the bleomycin-A_5 group(Group B),and the interferon-γ treated group(Group I).The pulmonary fibrosis model was established by a single intratracheal injection of 5 mg/kg of bleomycin.The rats were sacrificed at day 17,21,28 after modeling in batch.Semi-quantitative analysis of the histopathologic changes stained with Haematoxylin-eosin(H-E) was performed.The levels of TNF-α,IFN-γ and IL-10 in BALF were measured with ELISA.The content of hydroxyproline in the lungs was determined by digestion method.Results:①The scores of pulmonary alveolitis and pulmonary fibrosis in Group I and Group B were significantly higher from 17d after bleomycin administration compared with Group N(all P0.01).②In Group I,the level of TNF-α protein in BALF was significantly increased from 17d after modeling compared with Group N and Group B(all P0.01).The significantly increased level of IFNγ protein in BALF after IFN-γ administration was seen at 21 d and 28 d compared with Group N and Group B(P(0.05)).The level of IL-10 protein in BALF in Group I was significantly increased at 17 d in comparison with the normal group(P0.01).③The contents of hydroxyproline in the lungs in Group I and Group B were significantly higher from 17 d after bleomycin administration compared with Group N(all P(0.01)). Conclusion: The treatment of IFN-γ does not significantly influence progression of pulmonary fibrosis at the fibrosing stage by enhancing the levels of TNF-α,IFN-γ and IL-10 protein in vivo.