Pirfenidone Is an Agonistic Ligand for PPARα and Improves NASH by Activation of SIRT1/LKB1/pAMPK

Nonalcoholic steatohepatitis (NASH) is recognized by hepatic lipid accumulation, inflammation, and fibrosis. No studies have evaluated the prolonged-release pirfenidone (PR-PFD) properties on NASH features. The aim of this study is to evaluate how PR-PFD performs on metabolic functions, and provide insight on a mouse model of human NASH. Male C57BL/6J mice were fed with either normo diet or high-fat/carbohydrate diet for 16 weeks and a subgroup also fed with PR-PFD (300 mg/kg/day). An insulin tolerance test was performed at the end of treatment. Histological analysis, determination of serum hormones, adipocytokines measurement, and evaluation of proteins by western blot was performed. Molecular docking, in silico site-directed mutagenesis, and in vitro experiments using HepG2 cultured cells were performed to validate PR-PFD binding to peroxisome proliferator-activated receptor alpha (PPAR-alpha), activation of PPAR-alpha promoter, and sirtuin 1 (SIRT1) protein expression. Compared with the high-fat group, the PR-PFD-treated mice displayed less weight gain, cholesterol, very low density lipoprotein and triglycerides, and showed a significant reduction of hepatic macrosteatosis, inflammation, hepatocyte ballooning, fibrosis, epididymal fat, and total adiposity. PR-PFD restored levels of insulin, glucagon, adiponectin, and resistin along with improved insulin resistance. Noteworthy, SIRT1-liver kinase B1-phospho-5' adenosine monophosphate-activated protein kinase signaling and the PPAR-alpha/carnitine O-palmitoyltransferase 1/acyl-CoA oxidase 1 pathway were clearly induced in high fat + PR-PFD mice. In HepG2 cells incubated with palmitate, PR-PFD induced activation and nuclear translocation of both PPARalpha and SIRT1, which correlated with increased SIRT1 phosphorylated in serine 47, suggesting a positive feedback loop between the two proteins. These results were confirmed with both synthetic PPAR-alpha and SIRT1 activators and inhibitors. Finally, we found that PR-PFD is a true agonist/ligand for PPAR-alpha. Conclusions: PR-PFD provided an anti-steatogenic effect and protection for inflammation and fibrosis.