PF-03491390 PAN-caspase inhibitor decreases liver injury and fibrosis in a murine model of non-alcoholic steatohepatitis (NASH)

F.J. BARREYRO, S. HOLOD, P.V. FINOCCHIETTO, A. AVAGNINA, A.M. CAMINO, C.M. BIONDO, J.B. AQUINO, M.C. CARRERAS, J.J. PODEROSO, G.J. GORE

Congreso; International Liver Congress 2010 .The 45th annual meeting of the European Association for the Study of the Liver (EASL; 2010

Background and Aims: Hepatocyte apoptosis contributes to liver injury and fibrosis. Although, both the intrinsic and extrinsic apoptotic pathways are involved in the pathogenesis of NASH, the final common step of apoptosis is executed by a family of cysteine proteases termed caspases. Thus, our aim was to ascertain if administration of PF-03491390, a pan-caspase inhibitor, ameliorates liver injury and fibrosis in a murine model of NASH. Methods: C57/BL6J mice were fed regular chow or high fat diet (HFD) for 10 weeks. All mice were treated with vehicle or pan-caspase inhibitor PF-03491390 (0.3 mg/kg/day). Hepatocyte apoptosis was assessed by TUNEL assay and biochemical measurement of caspase-3 activity. Liver injury was evaluated by histopathology, serum ALT and AST. Steatosis was measured by liver triglyceride content. Quantitative-PCR (qPCR) was used to measure markers of hepatic inflammation (IL1-b), HSC activation (alpha-smooth muscle actin, aSMA), and fibrosis (Collagen 1, Coll-1). Immunofluorescence (IF) for aSMA was performed to identify HSC activation. Collagen was quantitated by Sirius red staining.Results: Mice fed a HFD diet demonstrate an 5-fold increase in hepatocyte apoptosis by the TUNEL assay and an 1.6-fold increase in caspase-3 activity; this increase in apoptosis was substantially attenuated in mice fed a HFD and treated with PF-03491390 (HFDPF) (p < 0.05). Likewise, mice fed the HFD diet had elevations of both serum ALT (70±10) and AST (144±9) levels which were normalized in the PF-03491390-treated HFD animals (p < 0.05). Liver injury was reduced in mice fed HFD-PF as compare to HFD by measuring histologic inflammation score and IL1-b qPCR (p < 0.05). These differences could not be attributed to differences in hepatic steatosis as liver triglycerides content were similar in both HFD groups of animals. aSMA a marker for HSC activation was decreased by IF and qPCR (p < 0.05) in HFD-PF compared to mice receiving a HFD alone. Hepatic fibrosis were reduced in PF-03491390 versus vehicle-treated HFD animals by decreasing Sirius red staining and coll-1 qPCR (p < 0.05).In conclusion, these data demonstrates that in a murine model of NASH, liver injury and fibrosis are suppressed by inhibiting hepatocytes apoptosis and suggests that PF-03491390 may be an attractive anti-fibrotic therapy in NASH.