Phytosterol-mediated inhibition of intestinal cholesterol absorption in mice is independent of liver X receptor.

SCOPE: Previous studies have proposed that phytosterols activate liver X receptors (LXR) in the intestine, thereby reducing intestinal cholesterol absorption and promoting fecal cholesterol excretion.

METHODS AND RESULTS: In the present study, we examined the effects of dietary phytosterol supplementation on intestinal cholesterol absorption and fecal neutral sterol excretion in LXRαβ-deficient mice, and wild-type mice treated with synthetic high-affinity LXRαβ agonists. LXRαβ deficiency led to an induction of intestinal cholesterol absorption and liver cholesterol accumulation. Phytosterol feeding resulted in an approximately 40% reduction of intestinal cholesterol absorption both in wild-type and LXRαβ-deficient mice, reduced dietary cholesterol accumulation in liver and promoted the excretion of fecal cholesterol-derived compounds. Furthermore, phytosterols produced additive inhibitory effects on cholesterol absorption in mice treated with LXRαβ agonists.

CONCLUSIONS: Our data confirm the effect of LXR in regulating intestinal cholesterol absorption and demonstrate that the cholesterol-lowering effects of phytosterols occur in an LXR-independent manner.