Sirtuin 7 Promotes Alcohol-Associated Liver Injury via Modulating Myeloid Cell Chemokine (C-C Motif) Ligand 2 Secretion through the NF-κB Signaling Pathway.

The pathogenesis of alcohol-associated liver disease (ALD) is complex, and involving ethanol-induced enhancement of gut permeability results in the release of bacterial products from the intestine. This triggers intrahepatic inflammation and liver damage, with hepatic macrophages playing key roles in the inflammatory response to alcohol. Sirtuin 7 (SIRT7), an NAD-dependent type III histone deacetylase, is being recognized as a potential therapeutic target in various human diseases, including cancer. Emerging evidence shows that SIRT7 participates in immune regulation, but whether it is involved in ALD remains elusive. In the present study, using myeloid cell-specific Sirt7 knockout mice (Lyz2-Sirt7), we observed that knockout Sirt7 in myeloid cells significantly ameliorated alcohol-induced liver injury, inflammation, and cell infiltration, while only mildly affecting lipid metabolism pathways. We further identified chemokine (C-C motif) ligand 2 (CCL2) as the main target impaired by Sirt7 knockout after alcohol. In vitro studies confirmed that Sirt7 knockout impaired macrophages' ability of CCL2 secretion and monocyte recruiting, and exogenous CCL2 reversed this impairment. At the molecular level, we found that knockout of Sirt7 significantly impaired lipopolysaccharide-induced p65 phosphorylation and nuclear localization. More importantly, the SIRT7 inhibitor 40569 sufficiently decreased alcohol-induced liver injury and hepatic inflammation via preventing CCL2 in vivo. Our data thus uncover a previously undescribed role of myeloid SIRT7 in mediating ALD via promoting CCL2 secretion through the NF-κB signaling pathway. Targeting SIRT7 might offer novel mechanism-based therapeutic options for ALD.