Anti-fibrotic effects of pirfenidone in lung fibroblasts derived from patients with idiopathic pulmonary fibrosis

Introduction: Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease with poor prognosis. Collagen and hyaluronic acid (HA) are main components of the extracellular matrix and their enhanced accumulation is associated with tissue fibrosis. Pirfenidone is a pyridone that exhibits anti-fibrotic effects. Its beneficial effects were demonstrated in patients with IPF by reducing disease progression. The inhibition of TGF-β-induced effects has been suggested to be part of pirfenidone9s anti-fibrotic properties. Aim: To study the effect of pirfenidone on secretion of collagen and HA in primary human lung fibroblasts. Methods: Primary human fibroblasts were isolated from lungs derived from patients with IPF. After incubation with pirfenidone (0.5 - 4 mM) and TGF-β1 (5 ng/ml), secretion of collagen and HA was measured by enzyme-linked immunosorbent assay, and down-stream signalling pathways of TGF-β were studied by western blotting. Results: TGF-β1 significantly induced the secretion of collagen type-III and HA. Pirfenidone significantly reduced the TGF-β1-induced secretion of collagen type-III (36% reduction at 1 mM [p=0.02], 40% reduction at 2 mM [p=0.01], 55% reduction at 4 mM pirfenidone [p=0.002]), and significantly antagonized TGF-β1-induced HA secretion (57% reduction at 2 mM [p=0.01], 65% reduction at 4 mM pirfenidone [p=0.006]). TGF-β1-induced phosphorylation of ERK1/2 MAP kinase was prevented in IPF fibroblasts by pirfenidone. Conclusion: Our data demonstrate that pirfenidone counteracts TGF-β-induced pro-fibrotic effects and suggest that the antagonistic effect of pirfenidone on TGF-β-induced effects is associated with the inhibition of ERK1/2.