Research in Mechanisms of Action Regarding Inhibitory Effects of Interferon-γ and -β in Intracellular Signal Transduction.

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Purpose :Though idiopathic pulmonary fibrosis(IPF) is fatal disease in field of diffuse lung diseases, no effective treatment improving prognosis has been reported. Interferons will be promising for treatment in fibrotic disorders in pulmonary disease, however, Interferon-β has been failed to improve survival ratio of IPF and interferon-γ fairly improved %VC in early stage of IPF (%VC>60%). Based on these clinical situations, we investigated mechanism of action of interferon-□ in bleomycin induced pulmonary fibrosis.Methods :Bleomycin at day 0 and interferon-β for 4 weeks were administered intravenously to ICR mice. At 28 days after bleomycin injection, histological and chemical analysis was performed for evaluation of effects of interferon-β. Tissue distribution and amounts of TGF-β1 and thrombospondin-1/2 were analyzed.Results and Discussion :Interferon-β□ attenuated prolylhydroxylase activity, resulting in inhibition of pulmonary fibrosis. Bleomycin-induced increase in TGF-β1 in epithelial cells and extracellular matrix was attenuated by interferon-β. Thrombospondin-1/2 was limited in platelets of control mice, but was present in foamy cells in fibrotic regions induced by bleomycin. In vitro study, IFN-g (10-1000ug/ml) did not inhibit growth of HMg2980 lung fibroblast cell line under no stimulation, but inhibited TGF-β1-induced proliferation of HMg2980 cell line.These findings suggest that the antifibrotic effect of interferon-β□ is inhibition of TGF-βand its activation via decrease in thrombospondin-1/2 in lung tissue and change in location of thrombospondin-1/2 from platelets to foamy cells. IFN-β and IFN-γ will be promising agents in different mechanisms to inhibit fibroblast proliferation.