Antagonist effect of Interferon-γ aerosol inhalation on pulmonary remodeling after γ-ray irradiation

Objective To observe the antagonistic effect of interferon-γ aerosol inhalation on pulmonary remodeling after γ-ray irradiation, and explore its mechanisms. Methods The Wistar rats were randomly divided into irradiation control group and irradiation + lntederon-γ antagonist group, which proceeded IFN-γaerosol inhalation 3 days before 20 Gy 60 Co γ-ray irradiation, then were sacrificed at 10, 20, 30 days after irradiation. Conventional histopathologieal sections of lung tissue were prepared, which were stained immunohistochemicaUy for α-SMA and Sirius red. The contents of collagen Ⅳ were determined by Western blot.The expression of MMP-2, MMP-9 and TIMP-1 in lung homogenate was detected by ELISA. Results The widen degrees of interalveolar septum, the deposition of collagen Ⅰ,Ⅲ, and the expression of α-SMA decreased significantly in IFN-γ treatment group as compared with those in the irradiation control group. The expression of collagen Ⅵ appeared an elevation trend, but this phenomenon attenuated after IFN-γ was used. The levels of MMP-2 and TIMP-1 decreased 10 days after administration with IFN-γ, but the opposite trend appeared for MMP-9. The expression of MMP-2, MMP-9 and TIMP-1 decreased 30 days after administration with IFN-γ.Conclusion IFN-γ is effective in alleviating pulmonary injuries induced by irradiation in rats, possibly by decreasing the expression of TIMP-1 to relieve the inhibition to MMP-9, then degrading collagen Ⅳ to antagonize remodeling after lung injury. Key words: Interferon-Ⅳ; Radiation pulmonary injury; Matrix metalloproteinases; Type Ⅳ Collagen