Effect of pirfenidone on rat hepatic stellate cell proliferation and collagen production

Background/Aims: Pirfenidone has been recently shown to reduce dimethynitrosamine-induced liver fibrosis in the rat, but no information are available on the effect of this drug on cultured hepatic stellate cells (HSC). Methods: HSC proliferation was evaluated by measuring bromodeoxyuridine incorporation; PDGF-receptor autophosphorylation, extracellular signal-regulated kinase (ERK1/2) and pp70S6K activation were evaluated by western blot; protein kinase C activation was evaluated by western blot and by ELISA; type I collagen accumulation and α1(I) procollagen mRNA expression were evaluated by ELISA and northern blot, respectively. Results: Pirfenidone significantly inhibited PDGF-induced HSC proliferation, starting at a concentration of 1 μM, with a maximal effect at 1000 μM, without affecting HSC viability and without inducing apoptosis. The inhibition of PDGF-induced HSC proliferation was associated neither with variations in PDGF-receptor autophosphorylation, or with ERK1/2 and pp70S6K activation. On the other hand, pirfenidone was able to inhibit PDGF-induced activation of the Na+/H+ exchanger, which is involved in PDGF-induced HSC proliferation in HSC, with a maximal effect at 1000 μM and inhibited PDGF-induced protein kinase C activation. Pirfenidone 100 and 1000 μM inhibited type I collagen accumulation in the culture medium induced by transforming growth factorβ1 by 54% and 92%, respectively, as well as TGFβ1-induced α1(I) procollagen mRNA expression. Results: Pirfenidone could be a new candidate for antifibrotic therapy in chronic liver diseases.