CD274 and atherosclerosis: found a significant increase in Treg cells in PD-L1/PD-L2-deficient mouse models, yet the plaques still showed significant progression, indicating that the inhibitory effect of the PD-1 pathway on activated CD4+/CD8+ T cells outweighs the protective effect of Treg cells on atherosclerosis (38–40) (Table 2) (Figure 1).