The microbiome- and metabolome-modulating activity of dietary cholesterol: insights from the small and large...

Cholesterol is an important lipid molecule that affects the gut microbiome upon ingestion. We systematically investigated the effects of cholesterol on the microbiota of the large and small intestines using ex vivo and in vivo models, combining flow cytometry, metabolomics, and metagenomics. The results showed that cholesterol directly causes a loss of bacterial membrane polarity and integrity, as well as a reduction in microbial metabolic activity. Cholesterol directly affected the global metabolism of the large and small intestinal microbiota, including amino acid, carbohydrate, and nucleotide metabolism. Ex vivo and in vivo studies shared similar results, showing that cholesterol increased the abundance of the primary bile acid-metabolizing bacteria Clostridium and Dorea in the large intestinal microbiota, confirming the enrichment effect of cholesterol on these bacteria. In the in vivo model, increased conjugated bile acids in the small intestine and decreased abundance of BSH-containing Bifidobacterium were observed due to cholesterol. Only in vivo models have demonstrated that cholesterol increases phosphatidylcholine levels in both the small and large intestines, which may be related to the effects of cholesterol on host metabolism. The pro-inflammatory capacity of the intestinal microbiota was enhanced by cholesterol, as evidenced by the increased levels of IL-1β and TNF-α in THP-1 cells upon stimulation with cholesterol-treated microbiota. This study comprehensively elucidates the effects of cholesterol on the composition and metabolic functions of the microbiota in both the large and small intestines. It offers a novel perspective on the ways in which cholesterol affects host metabolism via the gut microbiome.