Stevia rebaudiana root polysaccharide modulates liver metabolism, bile acid, and gut microbiota improving HFD-induced NAFLD: Potential roles of ACSL1 and FADS2

Background

Non-alcoholic fatty liver disease (NAFLD) is a prevalent metabolic disorder characterized by liver lipid accumulation and insulin resistance. However, effective therapeutic drugs for NAFLD are currently unavailable. Stevia rebaudiana root polysaccharides (SRRP) are inulin-type polysaccharides known for their hypoglycemic properties. Despite this, the effects of SRRP on improving NAFLD and the underlying mechanisms remain poorly understood.

Purpose

This study aims to evaluate the potential of SRRP in alleviating NAFLD and to explore its mechanisms of action.

Methods

NAFLD was induced in male C57BL/6 J mice through high-fat diet (HFD) feeding, with subsequent SRRP administration over 8 weeks. Comprehensive assessments included serum biochemical profiling, hepatic histopathological examination, and proinflammatory enzyme activity quantification. Mechanistic investigations employed tripartite analytical approaches: gut microbiota analysis via 16S rRNA sequencing, hepatic metabolomic profiling and bile acid profiling, and validation of transport protein expression through Western blot (WB) techniques.

Results

SRRP administration significantly alleviated NAFLD through reduced serum lipid concentrations, ameliorated inflammatory responses and oxidative stress, and decreased hepatic lipid deposition mechanistically, SRRP improved the structure of the gut microbiota by enhancing the proliferation of beneficial bacterial, including Lactobacillales and Bifidobacteriales, which subsequently elevated circulating Cholic acid (CA) and Chenodeoxycholic acid (CDCA), and improved hepatic lipid metabolites. Notably, KEGG from metabolomics indicated that the linoleic acid pathway might be associated with the improvement in hepatic lipid metabolite levels by SRRP. In Western blot analysis, SRRP significantly upregulated hepatic ACSL1 and FADS2 in NAFLD mice, demonstrating that the alleviation of NAFLD by SRRP may be achieved through the reduction of hepatic lipid accumulation.

Conclusions

SRRP exerts effects on improving NAFLD by modulating the gut microbiota, hepatic metabolites, bile acid levels, and the expression of ACSL1 and FADS2 proteins, providing more scientific evidence and support for the improvement of NAFLD by SRRP.