PDCD1 and myocarditis: CD4+ T cells in mice with myocarditis had enhanced expressions of CCL5, which can induce NF-kB activation; NKG7, which is associated with cytotoxicity; programmed cell death protein 1 (PDCD1), which is associated with T cell exhaustion; and inhibitor of DNA binding 2 (ID2), which mediates Treg plasticity into Th17 cells [113,129,130,131].