Overexpression of Cytotoxic T-Lymphocyte-Associated Antigen-4 Prevents Atherosclerosis in Mice

Objective-Although T-cell-mediated chronic inflammation contributes to atherosclerosis development, the role of a negative regulatory molecule cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) in atherosclerosis is poorly understood. We investigated the effects of CTLA-4 overexpression on atherosclerosis in apolipoprotein E-deficient (Apoe(-/-)) mice. Approach and Results-We generated CTLA-4 transgenic (CTLA-4-Tg)/Apoe(-/-) mice that display constitutive cell surface and intracellular expression of CTLA-4 in T cells and assessed atherosclerosis at age 16 weeks. CTLA-4 overexpression significantly reduced atherosclerotic lesion formation and intraplaque accumulation of macrophage and CD4(+) T cells in the aortic root compared with controls. CTLA-4-Tg/Apoe(-/-) mice showed decreased numbers of effector CD4(+) T cells and decreased expression of costimulatory molecules CD80 and CD86, ligands for CTLA-4, and a costimulatory molecule CD28, on CD11c(+) dendritic cells compared with controls. Consistent with in vivo findings, in vitro experiments revealed that CD4(+) T cells from CTLA-4-Tg/Apoe(-/-) mice showed decreased proliferative capacity and proinflammatory cytokine production, downregulated CD80 expression on CD11c(+) dendritic cells, and suppressed the proliferation of other T cells by limiting the costimulatory pathway. Moreover, CD11c(+) dendritic cells from CTLA-4-Tg/Apoe(-/-) mice showed reduced proliferative activity of T cells in vitro, suggesting the suppression of dendritic cell maturation in vivo. Conclusions-CTLA-4 regulates atherosclerosis by suppressing proatherogenic immune responses and could be an attractive therapeutic target for atherosclerosis.