Naringin improves lipid metabolism in a tissue-engineered liver model of NAFLD and the underlying mechanisms

Aims: Nonalcoholic fatty liver disease (NAFLD) is a lipid metabolism disorder. Naringin (a main active ingredient in Ganshuang granules) is a flavanone that has been demonstrated to exert hepatoprotective and antifibrotic effects. The present study aimed to use a novel tissue-engineered fatty liver model to assess the effects and mechanisms of naringin on NAFLD. Main methods: Intracellular triglyceride (TG) was examined by oil red O staining and commercial kits. The proteins associated with lipid metabolism were measured by western blotting and/or qPCR. Very low-density lipoprotein (VLDL) was measured by ELISA. A CCK8 assay was used to assess the cytotoxicity of naringin. Molecular docking was used to predict the interactions and binding patterns between naringin and target proteins. Key findings: Naringin significantly reduced intracellular TG accumulation by 52.7% in tissue-engineered fatty (TEF) livers, and also the level of pyruvate dehydrogenase kinase 4. Naringin downregulated CD36 and proliferator activated-receptor gamma expression, reducing the uptake of FFAs; naringin also downregulated de novo liposynthetases by reducing acetyl CoA carboxylase, fatty acid synthetase etc. in TEF livers. Moreover, naringin increased the expression of proliferator activated-receptor alpha (PPAR-alpha) and carnitine palmitoyltransferase 1 to improve the oxidation of fatty acids. The levels of VLDL secreted from TEF livers were reduced by 24.7% after naringin treatment. Molecular docking analyses determined the bioactivity of naringin through its specific binding to CD36 and PPAR-alpha. Significance: Naringin improved lipid metabolism disorders in TEF livers by reducing fatty acid uptake and de novo lipogenesis and increasing fatty acid oxidation. CD36 and PPAR-alpha might be specific targets of naringin.