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

Abstract

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 <i>C57BL/6J</i> 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, <i>in silico</i> site-directed mutagenesis, and <i>in vitro</i> experiments using HepG2 cultured cells were performed to validate PR-PFD binding to peroxisome proliferator-activated receptor alpha (PPAR-α), activation of PPAR-α 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-α/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 PPARα 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-α and SIRT1 activators and inhibitors. Finally, we found that PR-PFD is a true agonist/ligand for PPAR-α. <i>Conclusions:</i> PR-PFD provided an anti-steatogenic effect and protection for inflammation and fibrosis.