Naive CD8⁺ T Cells Expressing CD95 Increase Human Cardiovascular Disease Severity

Cardiovascular disease (CVD) remains a significant global health concern with a high degree of mortality. While CD4⁺ T cells have been extensively studied in CVD, the importance of CD8⁺ T cells in this disease, despite their abundance and increased activation in human atherosclerotic plaques, remains largely unknown. Thus, the objective of this study was to compare peripheral T-cell signatures between humans with a high (severe) risk of CVD (including myocardial infarction or stroke) and those with a low risk of CVD. Approach and Results: Using mass cytometry, we uncovered a naive CD8⁺ T (T_N) cell population expressing CD95 (termed CD95⁺CD8⁺ stem cell memory T [CD8 T_SCM] cells) that was enriched in patients with high compared with low CVD. This T-cell subset enrichment within individuals with high CVD was a relative increase and resulted from the loss of CD95^lo cells within the T_N compartment. We found that CD8 T_SCM cells positively correlated with CVD risk in humans, while CD8⁺ T_N cells were inversely correlated. Atherosclerotic apolipoprotein E-deficient (ApoE^-/-) mice also displayed respective 7- and 2-fold increases in CD8⁺ T_SCM frequencies within the peripheral blood and aorta-draining paraaortic lymph nodes compared with C57BL/6J mice. CD8⁺ T_SCM cells were 1.7-fold increased in aortas from western diet fed ApoE^-/- mice compared with normal laboratory diet-fed ApoE^-/- mice. Importantly, transfer of T_SCM cells into immune-deficient Rag.Ldlr recipient mice that lacked T cells increased atherosclerosis, illustrating the importance of these cells in atherogenesis.

CD8⁺ T_SCM cells are increased in humans with high CVD. As these T_SCM cells promote atherosclerosis, targeting them may attenuate atherosclerotic plaque progression.