Mitochondrial protease ClpP supplementation ameliorates diet- induced NASH in mice

Abstract

Background & Aims: Mitochondrial dysfunction is considered a pathogenic linker in the development of non-alcoholic steato-hepatitis (NASH). Inappropriate mitochondrial protein-quality control, possibly induced by insufficiency of the mitochondrial matrix caseinolytic protease P (ClpP), can potentially cause mitochondrial dysfunction. Herein, we aimed to investigate he-patic ClpP levels in a diet-induced model of NASH and determine whether supplementation of ClpP can ameliorate diet -induced NASH. Methods: NASH was induced by a high-fat/high-fructose (HF/ HFr) diet in C57BL/6J mice. Stress/inflammatory signals were induced in mouse primary hepatocytes (MPHs) by treatment with palmitate/oleate (PA/OA). ClpP levels in hepatocytes were reduced using the RNAi-mediated gene knockdown technique but increased through the viral transduction of ClpP. ClpP acti-vation was induced by administering a chemical activator of ClpP.Results: Hepatic ClpP protein levels in C57BL/6J mice fed a HF/ HFr diet were lower than the levels in those fed a normal chow diet. PA/OA treatment also decreased the ClpP protein levels in MPHs. Overexpression or activation of ClpP reversed PA/OA-induced mitochondrial dysfunction and stress/inflammatory signal activation in MPHs, whereas ClpP knockdown induced mitochondrial dysfunction and stress/inflammatory signals in these cells. On the other hand, ClpP overexpression or activation improved HF/HFr-induced NASH characteristics such as hepatic steatosis, inflammation, fibrosis, and injury in the C57BL/6J mice, whereas ClpP knockdown further augmented steatohepatitis in mice fed a HF/HFr diet.Conclusions: Reduced ClpP expression and subsequent mito-chondrial dysfunction are key to the development of diet -induced NASH. ClpP supplementation through viral trans-duction or chemical activation represents a potential therapeutic strategy to prevent diet-induced NASH.Lay summary: Western diets, containing high fat and high fructose, often induce non-alcoholic steatohepatitis (NASH). Mitochondrial dysfunction is considered pathogenically linked to diet-induced NASH. We observed that the mitochondrial prote-ase ClpP decreased in the livers of mice fed a western diet and supplementation of ClpP ameliorated western diet -induced NASH.(c) 2022 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.