HDL rescues mTreg and emTreg from apoptosis. A: CD4+ T cells were purified by negative bead selection from PBMCs and stained with fluorescently labeled antibody. Within CD4+ T cells, Treg were identified as CD3+CD4+FOXP3+ within the live/dead singlet cells. Dimension reduction analysis was performed by t-distributed stochastic neighbor embedding. A representative example of 15 experiments is shown. B: Frequency of nTreg, mTreg, and emTreg in peripheral blood (n = 15). C and D: Bulk Treg were purified by cell sorting from CD4+ T cells from healthy donors and incubated overnight with or without pooled HDL (700 μg/ml of protein) in X-VIVO medium. Caspase-3/7 expression was measured by flow cytometry in nTreg, mTreg, and emTreg. C: Representative example of caspase 3/7 staining in Treg subsets before and after HDL treatment. D: Effect of HDL on caspase 3/7 expression in Treg subsets. Each line represents cells from one individual (n = 20). Asterisks indicate significant differences (∗∗∗∗ P< 0.0001) two-way ANOVA.