CD4 and cardiovascular disorder: Specifically, PCSK9 overexpression promoted the polarization of naive CD4+ T cells to pro-inflammatory Th1 and Th17 subpopulations, whereas PCSK9 knockdown induced the polarization of naive CD4+ T cells to Treg cells, which may contribute to reduced inflammation and a favorable prognosis of cardiovascular disease, independent of LDL-C lowering (17).