The Role Of ALDH2 Activator In Liver Ischemia-Reperfusion Injury

Liver transplantation is the most commonly used and effective treatment for end-stage liver disease,and the liver ischemia-reperfusion injury is an inevitable pathophysiological process of liver transplantation,which often leads to serious complications after transplantation and greatly limite the effective use of marginal donor livers.Therefore,therapies to solve or alleviate the liver ischemia-reperfusion injury will benefit patients who undergoing or waiting for liver transplantation.ALDH2 is an aldehyde dehydrogenase,which is an important enzyme on the metabolic pathway of ethanol.It can oxidize exogenous or endogenous acetaldehyde into low toxicity acetic acid in mitochondria,thus playing an important physiological function under normal and pathological conditions.Recently,ALDH2 has been shown to play an important role in oxidative stress and alcohol-related diseases.However,its role in liver ischemiareperfusion has rarely been reported.The purpose of this study was to investigate the role and related mechanism of ALDH2 activation in liver ischemia-reperfusion.Part 1: Q-PCR,Western blot,enzyme activity detection,immunohistochemistry and other methods showed that the enzyme activity of ALDH2 decreased significantly and a large number of toxic aldehydes were accumulated,but the m RNA and protein levels and the distribution of ALDH2 did not change significantly in mice liver IRI model.Moreover,we found that ALDH2 agonist Alda-1 significantly increased the enzyme activity of ALDH2 and decreased the accumulation of toxic aldehydes without affecting ALDH2 expression and distribution.Part 2: To further investagate the role of ALDH2 activation in liver IRI,we used Q-PCR,Western blot,ELISA,fluorescence and immunohistochemical method both in vivo and in vitro study,and found that ALDH2 activation by Alda-1 in vivo could significantly reduce serum transa minase level,attenuate liver necrosis and apoptosis,and ameliorate liver inflammatory responses;Alda-1 pretreatment in vitro could improve hepatocyte viability,reduce hepatocyte cytoxicity,attenuate hepatocyte apoptosis,maintain normal mitochondrial membrane potential level,and reduce the production of ROS in hepatocytes.Part 3: To further investagate the relevant mechanisms of ALDH2 activation in the protection of liver IRI,we used Western blot,transmission electron microscopy(TEM),and pathway intervention both in vivo and in vitro.Interestingly,we found that Alda – 1 pretreatment could significantly enhance autophagy and autophagy blockage could abrogate the protection of Alda-1.We further demonstrated that Alda-1 treatment could activate AMPK and autophagy and that AMPK activation was required for Alda-1 mediated autophagy enhancement.In conclusion,by establishing a mouse liver IRI model,we found that the activation of ALDH2 enzyme activity by Alda-1 can significantly improve the liver IRI,and its protective mechanism may be related to AMPK-dependent autophagy enhancement.