CD4 and atherosclerosis: Our study showed that oral administration of the active form of vitamin D3 (calcitriol) attenuated atherosclerosis development in Apoe−/− mice by expanding tolerogenic DCs and CD4+Foxp3+ Tregs systemically and locally in atherosclerotic lesions, which might interact with each other and efficiently regulate aortic inflammatory responses associated with atherosclerosis [94].