Grifola frondosapolysaccharides ameliorate lipid metabolic disorders and gut microbiota dysbiosis in high-fat diet fed rats

The purpose of this study was to assess the potential effects of polysaccharides from edible mushroom Grifola frondosa (GFP) on lipid metabolic disorders and gut microbiota dysbiosis, and elucidate their possible regulatory mechanisms on lipid and cholesterol metabolism in high-fat diet (HFD)-exacerbated hyperlipidemic and hypercholesterolemic rats. Results showed that oral administration of GFP markedly alleviated dyslipidaemia through decreasing the serum levels of total triglycerides, total cholesterol, and free fatty acids, and significantly suppressing hepatic lipid accumulation and steatosis. Besides, the excretion of fecal bile acids was also promoted by oral administration of GFP. Metagenomic analysis revealed that GFP supplementation (400 mg kg-1 day-1) resulted in significant structure changes on gut microbiota in HFD-fed rats, in particular modulating the relative abundance of functionally relevant microbial phylotypes compared with the HFD group. Key microbial phylotypes responding to GFP intervention were identified to strongly correlate with the lipid metabolism disorder associated parameters using the correlation network based on Spearman's correlation coefficient. Serum and hepatic lipid profiles were found positively correlated with Clostridium-XVIII, Butyricicoccus and Turicibacter, but negatively correlated with Helicobater, Intestinimonas, Barnesiella, Parasutterella, Ruminococcus and Flavonifracter. Moreover, GFP treatment (400 mg kg-1 day-1) regulated the mRNA expression levels of the genes responsible for hepatic lipid and cholesterol metabolism. Oral supplementation of GFP markedly increased the mRNA expression of cholesterol 7α-hydroxylase (CYP7A1) and bile salt export pump (BSEP), suggesting an enhancement of bile acid (BA) synthesis and excretion from the liver. These findings illustrated that GFP could ameliorate lipid metabolic disorders through modulating specific gut microbial phylotypes and regulating hepatic lipid and cholesterol metabolism related genes, and therefore could be used as a potential functional food ingredient for the prevention or treatment of hyperlipidemia.