CD8 + T Cells Negatively Modulate Ischemia‐Induced Angiogenesis in Mice

ABSTRACT Angiogenesis‐related therapeutic approaches to peripheral arterial disease (PAD) deserve attention. CD8 + T cells play important roles in human pathobiology, and we investigated the involvement of cytotoxic CD8 + T cells in angiogenesis in response to ischemic stress. We also examined the mechanism of a component of green tea catechins, epigallocatechin‐3‐gallate (EGCG), which facilitates vascular regeneration in mice. Male 8‐week‐old wild‐type [(CD8a +/+ ) and interferon‐gamma (IFN‐γ +/+ )] knockout (CD8a −/− and IFN‐γ −/− ) mice were subjected to unilateral hindlimb ischemic surgery and then loss‐of‐function studies by blood flow, molecular, and immunostaining analyses at several time points. Post‐ischemic surgery CD8a +/+ mice were treated with EGCG for the evaluation of its vasculoprotective effect. Ischemic stress increased CD8a + T cells and IFN‐γ in blood and/or ischemic muscles. A serial laser Doppler blood‐flow analysis demonstrated a higher recovery of the ischemic/normal blood‐flow ratio in CD8a −/− mice throughout the follow‐up period compared to CD8a +/+ mice. On postoperative day 14, CD8a −/− ischemic muscles showed increased capillary density, vascular endothelial growth factor, p‐ERK1/2 and decreases in oxidative stress production and NLRP3 and caspase‐1 proteins, as well as the levels of matrix metalloproteinase‐2/9, cathepsin S/K, mac‐3 + , and ssDNA + cells in the ischemic muscles. All of these beneficial effects were reproduced in IFN‐γ −/− mice. The vasculoprotection was diminished by the murine recombinant IFN‐γ supplementation. EGCG showed efficacy that was comparable to that of CD8a −/− by modulating the growth signaling and apoptosis in mice. IFN‐γ depletion rescued impaired aortic ring angiogenic action. In human umbilical vein endothelial cells, EGCG ameliorated 5% T‐cell culture medium‐induced angiogenic actions, accompanied by reductions of NLRP3 and caspase‐1. Our findings indicate that CD8a + T‐cell deficiency promotes angiogenesis, and EGCG can reverse the detrimental effects of CD8a + T‐cell activation on angiogenesis. These results provide clinically relevant insights into the potential development of immune‐inflammatory therapy targeting vascular diseases.