T cell cholesterol efflux suppresses apoptosis and senescence and increases atherosclerosis in middle aged mice

Cholesterol efflux is mediated by specific transporters in T cells. Here the authors show that when the ABCA1/ABCG1 cholesterol transporters are absent, peripheral T cell numbers are reduced but activation increased with a premature aging phenotype of T cell senescence and apoptosis in middle aged Ldlr(-/-) mice. Atherosclerosis is a chronic inflammatory disease driven by hypercholesterolemia. During aging, T cells accumulate cholesterol, potentially affecting inflammation. However, the effect of cholesterol efflux pathways mediated by ATP-binding cassette A1 and G1 (ABCA1/ABCG1) on T cell-dependent age-related inflammation and atherosclerosis remains poorly understood. In this study, we generate mice with T cell-specific Abca1/Abcg1-deficiency on the low-density-lipoprotein-receptor deficient (Ldlr(-/-)) background. T cell Abca1/Abcg1-deficiency decreases blood, lymph node, and splenic T cells, and increases T cell activation and apoptosis. T cell Abca1/Abcg1-deficiency induces a premature T cell aging phenotype in middle-aged (12-13 months) Ldlr(-/-) mice, reflected by upregulation of senescence markers. Despite T cell senescence and enhanced T cell activation, T cell Abca1/Abcg1-deficiency decreases atherosclerosis and aortic inflammation in middle-aged Ldlr(-/-) mice, accompanied by decreased T cells in atherosclerotic plaques. We attribute these effects to T cell apoptosis downstream of T cell activation, compromising T cell functionality. Collectively, we show that T cell cholesterol efflux pathways suppress T cell apoptosis and senescence, and induce atherosclerosis in middle-aged Ldlr(-/-) mice.

Automated summary

The absence of ABCA1/ABCG1 cholesterol transporters in T cells leads to reduced T cell numbers and increased activation, resulting in premature aging, senescence, and apoptosis in middle-aged Ldlr(-/-) mice. However, this deficiency also decreases atherosclerosis and aortic inflammation, suggesting a complex role of cholesterol efflux pathways in T cell function and age-related diseases.