Netrin-1 attenuates hepatic steatosis via UNC5b/PPARγ-mediated suppression of inflammation and ER stress

The current study investigated whether netrin-1 can attenuate hepatic steatosis through PPARγ/autophagy-mediated suppression of inflammation and endoplasmic reticulum (ER) stress in experimental animal models.

Hepatic steatosis was induced by a high-fat diet in experimental mice. Recombinant mouse netrin-1 was administered via the tail vein (1 μg/mouse, once every two days). Serum inflammatory cytokines and hepatic inflammatory and ER stress markers were determined in mice using ELISA and western blotting protocol.

We found that netrin-1 expression was significantly increased (P < 0.05) in cultured macrophages treated with supernatants of subcutaneous adipocytes in the presence of palmitate and subcutaneous fat of obese mice. Recombinant netrin-1 treatment promoted PPARγ expression and autophagy, thereby attenuating inflammation and ER stress, lipid accumulation, and the expression of lipogenic proteins in mouse primary hepatocytes. High-fat diet (HFD) treatment increased hepatic inflammation and ER stress, causing hepatic steatosis in experimental mice. However, administration of netrin-1 reversed the effects of HFD on hepatic ER stress and lipid deposition.

These results suggest that subcutaneous adipose macrophage-derived netrin-1 ameliorates inflammation and ER stress in the liver, which in turn alleviates hepatic steatosis by enhancing basal PPARγ/autophagy-dependent signaling. The current study sheds light on the pathogenesis of hepatic steatosis in obesity and provides a promising therapeutic approach for treating metabolic-associated fatty liver disease (MAFLD).