This was consistent with a previous report that ABCA1, ABCG1, and HDL inhibit the proliferation of hematopoietic stem cells.44 Because leukocytosis enhances the progression of atherosclerosis, the reduction in leukocytes observed in miR-33−/−Apoe−/− mice may have had a beneficial effects on atherosclerosis.45 However, we also detected a higher frequency of Ly6Chigh monocytes in miR-33−/−Apoe−/− mice than in miR-33+/+Apoe−/− mice, and this could enhance inflammation in atherosclerotic plaque. Here, APOE is linked to atherosclerosis.