CD274 and atherosclerosis: Taken together, in this review, we have elaborated the involvement of PD-1, PD-L1 and PD-L2 in blood vessel inflammatory diseases with underlying atherosclerosis, where a precise and deeper understandings of the inhibitory mechanisms of PD-1 in atherosclerosis will uncover and support the rationale for developing PD-1/PD-L1-based immuno-modulatory therapies for diversified blood vessel inflammatory diseases.