The Role Of Augmenter Of Liver Regeneration Mediating Regulation Of Mitochondrial Homeostasis In Nonalcoholic Steatohepatitis

BackgroundNon-alcoholic fatty liver disease(NAFLD),an important form of metabolic syndrome in the liver,has become one of the most common chronic liver diseases affecting human health worldwide.It includes simple steatosis,non-alcoholic steatohepatitis(NASH),and a series of chronic liver diseases such as liver fibrosis,liver cirrhosis,and liver cancer that have evolved from NASH.NASH is at the core of the disease evolution process.so studying pathogenesis of NASH and seeking effective therapeutic targets have become an interesting aspect of current research.A large number of studies in recent years have confirmed that mitochondrial dysfunction plays an important role in the progression of NASH disease.Under NASH conditions,the oxidation of free fatty acids in the mitochondria of hepatocytes produces a large number of reactive oxygen species that damage mitochondrial function,resulting in decreased energy production in the mitochondria and impaired redox balance,which aggravates oxidative stress and initiates mitochondria-dependent apoptosis.Therefore,restoring mitochondrial function homeostasis provides a new strategy for the treatment of NASH.The augmenter of liver regeneration(ALR)is a cytokine extracted from the liver of the first weaned rat.It has multiple effects such as proliferative,anti-oxidative and anti-apoptotic effects.Previous studies have found that ALR can maintain cell survival by restoring damaged mitochondrial function under various stress states such as oxidative stress.This study found that ALR mainly exists in the mitochondria of cells,and the expression of ALR in mitochondria is down-regulated during NASH progression,and whether this is related to mitochondrial dysfunction under NASH conditions has not been reported yet.Therefore,we hypothesized that during the progression of NASH,the expression of ALR in the targeted regulation of mitochondria reverses the progression of NASH by maintaining mitochondrial homeostasis.ObjectiveTo investigate the regulation of mitochondrial ALR on the maintenance of mitochondrial homeostasis in a palmitic acid-induced hepatocyte NASH model.Methods1.Induction of NASH model by in vitro stimulation of normal human liver cell line LO2 with 0.2 m M palmitic acid(PA),using a fatty acid-free BSA-treated group as a control.Cell models were validated by oil red staining,cell viability,lactate dehydrogenase release,oxidative stress,and mitochondrial membrane potential detection.2.Extraction of normal intracellular mitochondria to identify intracellular localization of ALR.The difference in expression of mitochondrial ALR between normal cells and palmitic acid-stimulated cells was compared.3.In vitro,ALR overexpressing cells in mitochondria were constructed by plasmid transfection,and the effects of ALR overexpression on mitochondrial function,oxidative stress,cell viability,and lipid toxic lipid apoptosis were detected.Results1.Compared with the BSA-treated group,PA stimulated LO2 cells to increase the accumulation of lipid droplets within 24 hours,while the cell viability decreased,and the release of Lactate dehydrogenase(LDH)increased significantly.In addition,PA stimulation resulted in a series of mitochondrial dysfunction,such as increased oxidative stress,significant decrease in mitochondrial membrane potential,and increased apoptosis.2.By analyzing the different components of the cells,it was found that ALR is mainly located in the mitochondria under normal conditions.The expression of ALR in the mitochondria was significantly decreased after PA stimulation.3.Construction of mitochondrial ALR overexpressing cells by in vitro transfection of plasmids.Compared with the vector transfection group,ALR overexpressing cells showed stronger resistance under PA stimulation: increased cell viability,decreased release of LDH,reduced intracellular oxidative stress,and recovery of mitochondrial function.ConclusionsThe experimental results show that PA stimulation can effectively simulate the onset of NASH,and the low expression of ALR in mitochondria plays an important role in PA-induced NASH development.Targeted regulation of mitochondrial ALR expression can reverse the development of NASH by maintaining mitochondrial homeostasis.