Mesencephalic astrocyte-derived neurotrophic factor alleviates non-alcoholic steatohepatitis induced by Western diet in mice

Excessive lipid accumulation, inflammation, and fibrosis in the liver are the major characteristics of non-alcoholic steatohepatitis (NASH). Mesencephalic astrocyte-derived neurotrophic factor (MANF) plays an important role in metabolic homeostasis, raising the possibility that it is involved in NASH. Here, we reduced and increased MANF levels in mice in order to explore its influence on hepatic triglyceride homeostasis, inflammation, and fibrosis during NASH progression. The MANF expression was decreased in Western diet-induced NASH mice. In vivo, liver-specific MANF knockout exacerbated hepatic lipid accumulation, inflammation, and fibrosis of mice induced by Western diet, while liver-specific MANF overexpression mitigated these NASH pathogenic features. In vitro, knocking down MANF in primary hepatocyte cultures aggravated hepatic steatosis and inflammation, which MANF overexpression markedly attenuated. Studies in vitro and in vivo suggested that MANF regulated hepatic lipid synthesis by modulating SREBP1 expression. Inhibiting SREBP1 in primary hepatocytes blocked lipid accumulation after MANF knockdown. MANF overexpression reversed LXRs agonist GW3965 induced SREBP1 and LIPIN1 expression. MANF decreased the expression of pro-inflammatory cytokines by inhibiting NF-kappa B phosphorylation. These results suggest that MANF can protect against NASH by regulating SREBP1 expression and NF-kappa B signaling.