Nuclear Mir-204-3p Mitigates Metabolic Dysfunction-Associated Steatotic Liver Disease in Mice.

Background & Aims: Accumulating evidence has indicated the presence of mature microRNAs (miR) in the nucleus, but their effects on steatohepatitis remain elusive. We have previously demonstrated that the intranuclear miR-204-3p in macrophages protects against atherosclerosis, which shares multiple risk factors with metabolic dysfunction -associated steatotic liver disease (MASLD). Herein, we aimed to explore the functional significance of miR-204-3p in steatohepatitis. Methods: miR-204-3p levels and subcellular localization were assessed in the livers and peripheral blood mononuclear cells of patients with MASLD. Wild -type mice fed high -fat or methionine- and choline-deficient diets were injected with an adenoassociated virus system containing miR-204-3p to determine the effect of miR-204-3p on steatohepatitis. Co -culture systems were applied to investigate the crosstalk between macrophages and hepatocytes or hepatic stellate cells (HSCs). Multiple highthroughput epigenomic sequencings were performed to explore miR-204-3p targets. Results: miR-204-3p expression decreased in livers and macrophages in mice and patients with fatty liver. In patients with MASLD, miR-204-3p levels in peripheral blood mononuclear cells were inversely related to the severity of hepatic inflammation and damage. Macrophage -specific miR-204-3p overexpression reduced steatohepatitis in high -fat or methionine- and cholinedeficient diet -fed mice. miR-204-3p-overexpressing macrophages inhibited TLR4/JNK signaling and pro -inflammatory cytokine release, thereby limiting fat deposition and inflammation in hepatocytes and fibrogenic activation in HSCs. Epigenomic profiling identified miR-204-3p as a specific regulator of ULK1 expression. ULK1 transcription and VPS34 complex activation by intranuclear miR-204-3p improved autophagic flux, promoting the anti-inflammatory effects of miR-204-3p in macrophages. Conclusions: miR-204-3p inhibits macrophage inflammation, coordinating macrophage actions on hepatocytes and HSCs to ameliorate steatohepatitis. Macrophage miR-204-3p may be a therapeutic target for MASLD.