Effects of Pirfenidone in a Mouse Liver Fibrosis Model

Liver fibrosis results from chronic damage and excessive regeneration with redundant accumulation of extracellular matrix proteins, including collagen. Liver fibrosis may be caused by infectious, environmental, and autoimmune factors. Liver fibrosis is a precursor of cirrhosis and hepatocellular carcinoma. Current treatment options for liver fibrosis are primarily directed at inflammation with few options available to combat fibrogenesis. Pirfenidone (Esbriet®) is an anti-fibrotic agent for treatment of idiopathic pulmonary fibrosis, which downregulates the production of growth factors and procollagens I and II and inhibits fibroblast proliferation. We aimed to test anti-fibrotic potential of pirfenidone in liver using mouse model of sub-chronic cytotoxic fibrosis induced by carbon tetrachloride (CCl4). Additionally, considering its anti-fibrotic properties, pirfenidone was expected to suppress chemically-induced carcinogenesis. Several studies were conducted to evaluate effects of pirfenidone in liver. First, a 4-week dose-finding study was performed, male B6C3F1/J mice were treated with CCl4 (0.2 ml/kg intraperitoneal injections twice a week) while on diet with varying doses of pirfenidone (0 mg/kg, 100 mg/kg, 300 mg/kg, 600 mg/kg). Second, a 14-week subchronic study was conducted, where male B6C3F1/J mice were treated with CCl4 twice a week while on 300 mg/kg pirfenidone dose diet. Third, a 24-week anti-cancer study was performed, in which 112 male B6C3F1/J mice were exposed to single injection of either N-nitrosodiethylamine (DEN) or phosphate-buffered saline, followed with 14-week treatment by either olive oil or CCl4 in combination with either pirfenidone (300 mg/kg) or control diet. Pirfenidone treatment decreased liver fibrosis in both studies. In dose-finding study, pirfenidone had a significant anti-fibrotic and anti-inflammatory effect by significantly blunting collagen deposition in liver, serum transaminase levels, and preventing ballooning degeneration of hepatocytes at 300 and 600 mg/kg doses. In sub-chronic study, pirfenidone treatment also resulted in a significant reduction in collagen deposition in liver; however, it had little effect on inflammatory markers and liver injury. In anti-cancer study, pirfenidone did not affect incidence, size, or multiplicity of tumors. Pirfenidone showed anti-fibrogenesis effects in sub-acute and sub-chronic cytotoxic liver fibrosis model; anti-inflammatory effects were observed only in sub-acute study. Pirfenidone has no effect on development of liver tumors in anti-cancer study