CYP7A1 and atherosclerosis: In addition, TMAO administration could suppress levels of liver BA synthetase (Cyp7a1 and Cyp27a1) and BA transporters (Oatp1, Oatp4, Mrp2, and Ntcp), leading to a disorder of BA-related pathways and atherosclerosis (Koeth et al., 2013), suggesting that the atherosclerotic promoting effect of TMAO is also associated with the variation in BA metabolism.