COL1A1 and idiopathic pulmonary fibrosis: Individual and combined IFN-γ and PFD treatment inhibited TGF-β1-induced COL1A1 expression in both NHLFs and IPF fibroblasts, with a significant difference noted between the effects of IFN-γ and PFD treatment (p < 0.01, Fig. 5a & b) and individual and combined treatment (p < 0.001, Fig. 5a & b).