Polysaccharides fromEnteromorpha proliferaalleviate hypercholesterolemiaviamodulating the gut microbiota and bile acid metabolism

Polysaccharides from Enteromorpha prolifera (EP) possess multiple biological activities, while the role of EP in hypercholesterolemia and its relationship with the gut microbiota have not been elucidated. To address this issue, fifty male C57BL/6J mice were randomly subjected to a basal diet and a high-fat and high-cholesterol diet, and 3 treatment groups were fed an HFHC diet supplemented with different dosages of EP (100, 200 and 300 mg kg^-1 day^-1) for 12 weeks. Here we show that EP intervention lowered serum concentrations of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) and inhibited hepatic cholesterol deposition. EP intervention also upregulated the gene expression related to the hepatic cholesterol uptake and bile acid synthetic pathway. Apart from that, EP altered the gut microbiota, pre-dominantly increasing microbes associated with bile acid metabolism, such as norank_f_ Muribaculaceae. Moreover, bile acid profile analysis revealed that EP could alter the fecal bile acid profile and reduce fecal conjugated bile acids. Further correlation analysis indicated the negative correlation of Bacteroides, norank_f_ Muribaculaceae and Ileibacterium abundance with the levels of fecal conjugated bile acids and serum TC and LDL-C, while the abundance of Proteobacteria and Lachnoclosteridium showed a positive association with conjugated bile acids and serum TC. To sum up, the above findings revealed that EP may alleviate hypercholesterolemia and regulate cholesterol metabolism in ways that promote a favorable fecal microbiota composition and modulate bile acid metabolism.