IDO1 and atherosclerosis: This macrophage subset was distinguished in part, by expression of the immunomodulatory genes IDO and CHIT (encoding chitotriosidase), which is abundantly produced by lipid-laden macrophages in other conditions such as Gaucher’s disease, Niemenn-Pick disease, and atherosclerosis (Barone et al., 2007; Yap et al., 2020).