Figure 7.

Potential cholesterol-lowering mechanisms of Lactobacillus delbrueckii–fed pigs. Ileal microbiota modification (mainly increased ileal Lactobacillus abundance) with L. delbrueckii administration led to bile salts deconjugation by BSH activity and facilitated fecal TBA and TC excretion. Meanwhile, less deconjugated BAs are reabsorbed into enterohepatic circulation and downregulate BA transporter expression (ASBT and IBABP) and promote BA synthesis via increasing the conversion of cholesterol to BA with the help of CYP7A1, a rate-limiting enzyme, in the liver. Additionally, ileal BA deconjugation by microbiota alteration affects BA signaling (FXR–FGF19 axis) to regulated BA synthesis. Enhancement of BA synthesis using circulating cholesterol (blood transport) to restore the bile acid pool.