The combination of Ilexhainanoside D and ilexsaponin A1 reduces liver inflammation and improves intestinal barrier function in mice with high-fat diet-induced non-alcoholic fatty liver disease

Abstract

BackgroundNon-alcoholic fatty liver disease (NAFLD) is becoming a major health concern worldwide. Ilex hainanensis Merr. extract was proved to have anti-inflammation effect on NAFLD, and Ilexhainanoside D (IhD) and ilexsaponin A1 (IsA) were the main triterpenoid saponins extracted from it. PurposesTo investigate the hepatoprotective effect of the combination of IhD and IsA (IIC) against NAFLD and discuss the potential mechanisms. MethodsMale C57BL/6 mice were fed a high-fat diet (HFD) to induce NAFLD and were treated with IIC (60, 120 or 240 mg/kg) for 8 weeks. Growth parameters, abdominal fat content, serum biochemical markers, hepatic lipid accumulation and insulin tolerance were assessed. Quantitative real-time PCR was used to determine the hepatic gene expression of TLR2, TLR4, TNF-α, IL-6, and IL-1β. Western blot analysis was performed to determine the expression of the epidermal tight junction proteins ZO-1 and occludin. Gut microbiota profiles were established via high-throughput sequencing of the V3-V4 region of the bacterial 16S rRNA gene. ResultsIIC significantly reduced the severity of NAFLD induced by HFD in a dose-dependent manner. IIC decreased the ratio of Firmicutes/Bacteroidetes, reduced the relative abundance of Desulfovibrio and increased the relative abundance of Akkermansia. The intestinal barrier was improved as evidenced by the upregulation of the expression of ZO-1 and occludin in the ileum. IIC thus reduced the entry of LPS into the circulation and decreased the hepatic gene expression levels of proinflammatory cytokines. ConclusionThis approach demonstrated the positive effects of IIC in a mouse model of NAFLD, indicating that it possibly acts by reducing inflammation and improving the intestinal barrier function.