| Alcoholic liver disease is a common chronic liver disease worldwide,including alcoholic fatty liver,alcoholic steatohepatitis,alcoholic liver fibrosis,alcoholic cirrhosis,and hepatocellular carcinoma.Alcoholic steatohepatitis,the precursor of alcoholic liver fibrosis and cirrhosis,is the most aggressive form of alcoholic liver disease.Moreover,it is characterized by rapid disease progression and high mortality.However,there is still a lack of specific drugs in clinical treatment,when advanced to the end stage of liver disease can only be treated by liver transplantation.Therefore,to reveal the pathogenesis and discover its therapeutic targets is of great significance for the treatment of alcoholic liver disease.The BRISC deubiquitinating enzyme complex is composed of scaffold protein ABRO1,deubiquitination enzymes BRCC3,BRE,and MERIT40,which can specifically cleave the substrate-linked K63-position polyubiquitin chain.The BRISC complex plays an important role in immune regulation by control of NLRP3 and IFNAR1 activation.However,the role of the BRISC complex in alcoholic liver disease has not been reported.Analysis of published transcriptome datasets in our laboratory showed that the m RNA expression of Abro1 and Brcc3 were significantly up-regulated in the liver of patients with alcoholic hepatitis,suggesting that the BRISC complex plays an important role in alcoholic liver disease.In this study,mouse model of alcoholic liver injury was established using ABRO1 and BRCC3 knockout mice to investigate the role of BRISC complex in alcoholic liver injury.The results of H＆E staining and serum alanine aminotransferase showed that alcohol-induced liver injury in ABRO1 knockout mice was reduced;Oil red staining and quantitative method showed that lipid accumulation induced by alcohol in ABRO1 knockout mice was significantly lower than that in pair-fed mice.Analysis of neutrophil infiltration and intrahepatic inflammatory factors revealed that alcohol-induced inflammatory response in ABRO1 deficiency mice was significantly reduced.These data clearly show that knockout of ABRO1 significantly inhibited alcohol-induced liver injury.BRCC3 knockout also improved the liver injury and inflammation in mice,which was reflected in decreased serum ALT,improved the pathological changes of liver,inhibited the activation of NLRP3 inflammasome and the m RNA expression of cytokines in mouse liver.Phenotype similar to ABRO1 suggests that ABRO1/BRCC3 knockout may ameliorate alcoholic liver injury in mice by inactivating the BRISC complex.Further studies showed that small molecule inhibitors of BRISC complex improved alcoholinduced liver injury and steatosis.In conclusion,these results suggest that BRISC complex is involved in the development of alcoholic liver injury and targeting BRISC complex may be a new approach to treat alcoholic liver disease.Furthermore,we explored the mechanism by which BRISC complex promotes the development of alcoholic liver injury.It was found that the BRISC complex deficiency did not affect the level of serum LPS and the hepatic expression of alcohol metabolism enzymes,including cytochrome P450 2E1,ethanol dehydrogenase,and acetaldehyde dehydrogenase in mouse model;Compared with wild-type cells,ABRO1 knockout hepatocytes showed similar lipid toxicity to palmitic acid,but the accumulation of triglyceride in ABRO1 knockout hepatocytes was reduced;The activation of NLRP3 inflammasome in palmitic acidinduced ABRO1 knockout Kupffer cells was inhibited and IL-1β secretion was decreased.These results suggest that BRISC complex may be involved in the occurrence and development of alcoholic liver injury through regulating the activation of NLRP3 inflammasome in Kupffer cell,but the specific molecular mechanism needs to be further investigated.In conclusion,in this study,knockout mice and small molecule inhibitors were used to prove that BRISC complex can promote alcoholic liver injury in mice,providing a candidate target for the treatment of alcoholic liver injury. |
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