CYP27A1 and atherosclerosis: Serum TMAO levels have been linked to increased cardiovascular events.[82,83] TMAO impairs RCT, as indicated by increased macrophage cholesterol and oxLDL, CD36 and SR-A1 receptors, and foam-cell formation, to promote atherosclerosis in a gut microbiota-dependent manner.[78] TMAO supplementation in diet suppresses CYP7A1 and CYP27A1 expression, increases hepatic cholesterol, and decreases the total bile acid pool.[78] TMAO also suppresses expression of intestinal NPC1 L1 and ABCG5/ABCG8, thereby reducing intestinal cholesterol absorption.[78]