APOE and atherosclerosis: A recent study investigated the role of another costimulatory pathway, CD27–CD70, in atherosclerosis by inducing bone marrow-derived and systemic CD27 deficiency in Apoe−/− mice, and showed that CD27 deficiency exacerbated early stages of atherosclerosis, along with reduced Treg numbers in various lymphoid organs and the aorta [53].