Membrane attack complex impairs hepatocyte autophagy in alcohol-related liver disease by regulating the SIRT1-FOXO3 signaling

Background

Impaired hepatocyte autophagy is a key feature of alcohol-related liver disease (ALD). Activation of the membrane attack complex (MAC) regulates autophagy. This study examined the role and regulatory mechanisms of MAC in hepatocyte autophagy during ALD progression.

Methods

For the animal model, C57BL/6 mice were fed a Lieber-DeCarli liquid diet containing 5 % ethanol (EtOH) (w/v). For the cell model, AML12 cells were exposed to 100 mM EtOH for 72 h. Pathological changes in the liver were examined using hematoxylin–eosin staining, and hepatic steatosis was evaluated using Oil Red O staining. The mRNA and protein expression levels were analyzed by RT-qPCR and western blotting, respectively. Secretion levels of pro-inflammatory cytokines were determined by ELISA. Immunofluorescence staining was employed to detect C5b-9 and LC3 levels, as well as FOXO3 cellular localization. The interaction between FOXO3 and the LAMP2 promoter was analyzed using the ChIP assay.

Results

MAC inhibition reduced liver injury, lipid accumulation, and inflammation in the liver tissues of ALD mice while promoting hepatocyte autophagy. CD59 overexpression not only inhibited EtOH-induced lipid accumulation and inflammation in AML12 cells but also promoted autophagy by activating the SIRT1-FOXO3 axis. Mechanistically, SIRT1 promoted FOXO3-mediated LAMP2 transcriptional activation by enhancing the deacetylation and nuclear translocation of FOXO3. As expected, SIRT1 silencing weakened the effects of CD59 overexpression on lipid accumulation, inflammatory response, and autophagy in EtOH-treated AML12 cells.

Conclusion

MAC inhibition enhances LAMP2-mediated hepatocyte autophagy in ALD by promoting SIRT1-mediated FOXO3 deacetylation and nuclear translocation, thereby alleviating ALD progression.