Therapeutic effect of fenofibrate for non-alcoholic steatohepatitis in mouse models is dependent on regime design.

Background: Non-alcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver diseases. In most cases, NAFLD progresses from benign steatosis to steatohepatitis (NASH), and then to cirrhosis. No treatment is currently approved for NAFLD/NASH in the clinic. Fenofibrate (FENO) has been clinically used to treat dyslipidemia for more than a half century, but its effects on NASH are not established. FENO's half-life is quite different between rodent and human. The aim of this study was to investigate the potential of pharmacokinetic-based FENO regime for NASH treatment and the underlying mechanisms. Methods: Two typical mouse NASH models, methionine-choline deficient (MCD) diet-fed mice and choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD)-fed mice, were used. MCD model was designed as therapeutic evaluation in experiment 1 and CDAHFD model was designed as preventive in experiment 2. Three doses of FENO (5, 25, 125 mg/kg), two times a day (BID), were administered to the above models. Serum markers of liver injury, cholestasis, and the histology of liver tissues were investigated. Normal mice were used as a model in experiment 3 for toxicity evaluation, Quantitative-PCR and Western Blot assays were used to investigate the inflammatory responses, bile acid synthesis as well as lipid catabolism. Results: Mice on the MCD and CDAHFD diets developed steatohepatitis as expected. Treatment with FENO (25 mg/kg·BID) significantly decreased hepatic steatosis, inflammation and fibrosis in both therapeutic and preventive models. In the MCD model, the therapeutic action of FENO (25 mg/kg·BID) and 125 mg/kg·BID on histopathology and the expression of inflammatory cytokines were comparable. In reducing macrophage infiltration and bile acid load, FENO (25 mg/kg·BID) was superior to 125 mg/kg·BID. In all the aspects mentioned above, FENO (25 mg/kg·BID) was the best among the 3 doses in the CDAHFD model. In a third experiment, the effects of FENO (25 mg/kg·BID) and 125 mg/kg·BID on lipid catabolism were comparable, but 125 mg/kg·BID increased the expression of inflammatory factors and bile acid load. In both models, FENO (5 mg/kg·BID) showed little effect in hepatic steatosis and inflammation, neither the adverse effects. FENO (125 mg/kg·BID) aggravated liver inflammation, increased bile acid synthesis, and promoted the potential of liver proliferation. In toxicity risk assay, FENO (25 mg/kg·BID) treatment showed low potential to trigger bile acid synthesis, inflammation and hepatocyte proliferation. Conclusion: A new regime, FENO (25 mg/kg·BID) is potentially a therapeutic strategy for the NASH treatment. Translational medicine is warranted to prove its effectiveness in the clinic.

Hepatocytic AP-1 and STAT3 contribute to chemotaxis in alphanaphthylisothiocyanate-induced cholestatic liver injury.

The development of cholestatic liver injury (CLI) involves inflammation, but the dominant pathway mediating the chemotaxis is not yet established. This work explored key signaling pathway mediating chemotaxis in CLI and the role of Kupffer cells in the inflammatory liver injury. Probe inhibitors T-5224 (100 mg/kg) for AP-1 and C188-9 (100 mg/kg) for STAT3 were used to validate key inflammatory pathways in alpha-naphthylisothiocyanate (ANIT, 100 mg/kg)-induced CLI. Two doses of GdCl3 (10 mg/kg and 40 mg/kg) were used to delete Kupffer cells and explore their role in CLI. Serum and liver samples were collected for biochemical and mechanism analysis. The liver injury in ANIT-treated mice were significantly increased supported by biochemical and histopathological changes, and neutrophils gathering around the necrotic loci. Inhibitor treatments down-regulated liver injury biomarkers except the level of total bile acid. The chemokine Ccl2 increased by 170-fold and to a less degree Cxcl2 by 45-fold after the ANIT treatment. p-c-Jun and p-STAT3 were activated in the group A but inhibited by the inhibitors in western blot analysis. The immunofluorescence results showed AP-1 not STAT3 responded to inhibitors in ANIT-induced CLI. With or without GdCl3, there was no significant difference in liver injury among the CLI groups. In necrotic loci in CLI, CXCL2 colocalized with hepatocyte biomarker Albumin, not with the F4/80 in Kupffer cells. Conclusively, AP-1 played a more critical role in the inflammation cascade than STAT3 in ANIT-induced CLI. Hepatocytes, not the Kupffer cells released chemotactic factors mediating the chemotaxis in CLI.

Fenofibrate reverses liver fibrosis in cholestatic mice induced by alpha-naphthylisothiocyanate.

Cholestatic liver fibrosis occurs in liver injuries accompanied by inflammation, which develops into cirrhosis if not effectively treated in early stage. The aim of the study is to explore the effect of fenofibrate on liver fibrosis in chronic cholestatic mice. In this study, wild-type (WT) and Pparα-null (KO) mice were dosed alpha-naphthylisothiocyanate (ANIT) diet to induce chronic cholestasis. Induced liver fibrosis was determined by pathological biomarkers. Then fenofibrate 25 mg/kg was orally administrated to mice twice/day for 14 days. Serum and liver samples were collected for analysis of biochemistry and fibrosis. In WT mice, cholestatic biomarkers were increased by 5-8-fold and the expression of tissue inhibitors of metalloproteinases 1 (TIMP-1), Monocyte chemoattractant protein 1 (MCP-1), Collagen protein I (Collagen I) was increased by more than 10-fold. Fenofibrate significantly downgraded the biochemical and fibrotic biomarkers. In Western blot analysis, levels of collagenI and alpha-smooth muscle actin (α-SMA) were strongly inhibited by fenofibrate. In KO mice, liver fibrosis was induced successfully, but no improvement after fenofibrate treatment was observed. These data showed low-dose fenofibrate reverses cholestatic liver fibrosis in WT mice but not in KO mice, suggesting the dependence of therapeutic action on peroxisome proliferator-activated receptor alpha (PPARα). The study offers an additional therapeutic strategy for cholestatic liver fibrosis in practice.