Pirfenidone inhibits transforming growth factor beta 1-induced extracellular matrix production in nasal polyp-derived fibroblasts

Abstract

Purpose: Pirfenidone has been shown to have antifibrotic and anti-inflammatory effects in the lungs. The purpose of this study was to evaluate the inhibitory effects of pirfenidone on transforming growth factor (TGF)-beta 1-induced myofibroblast differentiation and extracellular matrix accumulation. We also determined the molecular mechanisms of pirfenidone in nasal polyp-derived fibroblasts (NPDF). Methods: NPDFs were isolated from nasal polyps from eight patients who had chronic rhinosinusitis with nasal polyp. Pirfenidone was used to treat TGF-beta 1-induced NPDFs. Cytotoxicity was evaluated by using a 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyl-tetrazolium bromide assay. Fibroblast migration was evaluated with scratch assays. Expression levels of alpha-smooth muscle actin (SMA), fibronectin, and phosphorylated Smad2/3 were determined by Western blot and/or reverse transcription-polymerase chain reaction and immunofluorescent staining. Total collagen production was analyzed with the Sircol collagen assay and contractile activity was measured by a collagen gel contraction assay. Results: Pirfenidone (0-2 mg/mL) has no significant cytotoxic effects in TGF-beta 1-induced NPDFs. Migration of NPDFs was significantly inhibited by pirfenidone treatment. The expression levels of alpha-SMA and fibronectin were significantly reduced in pirfenidone-treated NPDFs. Collagen contraction and production were also significantly decreased by pirfenidone treatment. Finally, pirfenidone significantly inhibited phosphorylation of the Smad2/3 pathway in TGF-beta 1-induced NPDFs. Conclusions: Pirfenidone has an inhibitory effect on TGF-beta 1-induced migration, myofibroblast differentiation (alpha-SMA), extracellular matrix accumulation, and collagen contraction by blocking the phosphorylation of Smad2/3 pathways in NPDFs. Thus, pirfenidone may inhibit TGF-beta 1-induced extracellular matrix by regulating Smad2/3.