ABSTRACT
OBJECTIVE Although the underlying mechanism is largely unknown, gut dysbiosis has emerged as a central initiator of obesity-related diseases including nonalcoholic fatty liver disease (NAFLD), type 2 diabetes and meta?bolic syndrome. The emerging evidence support the use of prebiotics like herb-derived polysaccharides for treating NAFLD by modulating gut microbiome. So, our study focused on the microbiota-dependent anti-NAFLD effect and the exact mechanisms of Astragalus polysaccharides (APS) extracted from Astragalus mongholicus Bunge in high-fat diet (HFD) fed mice. METHODS Co-housing experiment was used to assess the microbiota dependent anti-NAFLD effect of APS. Then, targeted metabolomics and metagenomics were adopted for determining short-chain fatty acids (SCFAs) and bacteria that were specifically enriched by APS. Further in vitro experiment was carried out to test the capacity of SCFAs-producing of identified bacterium. Finally, the anti-NAFLD efficacy of identified bacterium was tested in HFD fed mice. RESULTS Our results first demonstrated the anti-NAFLD effect of APS in HFD fed mice and the contribution of gut microbiota. Moreover, our results indicated that SCFAs, predominantly acetic acid were elevated in APS-supplemented mice and ex vivo experiment. Metagenomics revealed that D. vulgaris from Desulfovibrio genus was not only enriched by APS, but also a potent generator of acetic acid, which showed significant anti-NAFLD effects in HFD fed mice. In addition, D. vulgaris modulated the hepatic gene expression pattern of lipids metabolism, particularly suppressed hepatic fatty acid synthase (FASN) and CD36 protein expression. CONCLUSION APS enriched D. vulgaris is effective on attenuating hepatic steatosis possibly through producing acetic acid, and modulation on hepatic lipids metabolism in mice. Further studies are warranted to explore the long-term impacts of D. vulgaris on host metabolism and the underly?ing mechanism.