Myeloid-specific deletion of SIRT1 increases hepatic steatosis and hypothalamic inflammation in mice fed a high-fat diet.

Obesity-induced fatty liver disease is associated with increased hypothalamic inflammation. Previous reports have demonstrated that the deletion of SIRT1 in hepatocytes increases hepatic steatosis and inflammation. Using myeloid cell-specific SIRT1 knockout (KO) mice, we investigated whether ablation of SIRT1 in macrophages plays a role in regulating hepatic steatosis and hypothalamic inflammation. When challenged with a high-fat diet (HFD) for 24 weeks, hyperleptinemia, hyperinsulinemia, hepatic steatosis and macrophage infiltrations in HFD-fed KO mice were increased compared with HFD-fed WT mice. Hypothalamic expression levels of iba1 were increased in HFD-fed KO mice compared with HFD-fed WT mice. In particular, the expression levels of choline acetyltransferase were decreased in the hypothalamus of HFD-fed KO mice compared with HFD-fed WT mice. Thus, our findings suggest that SIRT1 plays a key role for hepatic steatosis and hypothalamic inflammation and that anti-inflammatory effect of SIRT1 may be important for the prevention of obesity-induced metabolic syndromes.