Pirfenidone suppresses TGF‑β1‑induced human intestinal fibroblasts activities by regulating proliferation and apoptosis via the inhibition of the Smad and PI3K/AKT signaling pathway.

Intestinal fibroblasts, the main effector cells of intestinal fibrosis, are considered to be a good target for anti‑fibrotic therapy. The aim of the present study was to examine the effects of pirfenidone (PFD) on human intestinal fibroblasts (HIFs) stimulated by transforming growth factor (TGF)‑β1 and to explore the potential mechanism. Prior to stimulation with TGF‑β1 (10 ng/ml), HIFs were treated with or without PFD (1 mg/ml). Cell proliferation was determined by Cell Counting Kit (CCK)‑8 and colony formation assays, and cell apoptosis was assessed using flow cytometry and a TUNEL assay. Reverse transcription‑quantitative polymerase chain reaction and western blotting were performed to evaluate the mRNA and protein expressions of α‑smooth muscle actin (α‑SMA), collagen I and fibronectin. The protein expression of TGF‑β1/mothers against decapentaplegic homolog (Smad) and phosphoinositide 3‑kinase (PI3K)/protein kinase B (AKT) signaling pathways was evaluated by western blotting. CCK‑8 and colony formation assays demonstrated that PFD significantly inhibited cell proliferation in HIFs stimulated with TGF‑β1. Flow cytometry and TUNEL assays revealed that PFD treatment significantly enhanced apoptosis in TGF‑β1‑stimulated HIFs. In addition, PFD markedly reduced TGF‑β1‑induced HIF activities, such as myofibroblast differentiation (α‑SMA), and collagen production (collagen I and fibronectin). These effects of PFD were mediated by the inhibition of the TGF‑β1/Smad and PI3K/AKT signaling pathways. Therefore, the present study demonstrated that PFD reduced TGF‑β1‑induced fibrogenic activities of HIFs, suggesting that PFD may be a potential therapeutic agent for intestinal fibrosis.