Figure 5.

Mechanisms linking the pro-atherosclerotic activity of gut microbial metabolite TMAO and cholesterol transport and synthesis in the intestine, liver, and macrophage. The intestinal microbiota metabolizes choline, phosphatidylcholine, L-carnitine, and betaine to trimethylamine (TMA), which is oxidized into TMAO by hepatic flavin monooxygenases (FMO). Green arrows indicate an increase of expression or activation whereas red arrows indicate a reduction of the expression. Yellow arrows indicate that the results in the literature are controversial.