CD8+T细胞加重围手术期缺血性脑损伤及其机制研究

General anesthesia, dehydration, bed rest, stasis in the postoperative period, and perioperative withholding of antiplatelet or anticoagulant agents can aggravate surgery-induced hypercoagulability and increase the risk of perioperative ischemic stroke. Results from the literature and our initial study indicate that perioperative patients are vulnerable to ischemic stroke, meanwhile they usually suffer from more serious damage. However, the underlying mechanism remains unknown. Our preliminary experiments suggested that CD8+T cells were over-activated after perioperative stroke and played pivotal roles in aggravating ischemic brain injury. It has been shown that hypoxia, stress and other factors could cause the accumulation of L-2-hydroxyglutarate (L2HG), and then upregulated L2HG increases the activation of CD8+T cells. Meanwhile, we also found that L2HG abnormally accumulated in CD8+T cells after the attack of perioperative ischemic stroke. Thus we hypothesized that L2HG accumulated after perioperative ischemic stroke, resulting in over-activation of CD8+T cells and then more excretion of perforin and granzyme B by CD8+T cells, thus it exacerbated cerebral ischemic injury. This study intends to apply the techniques of cell co-culture and conditional knockout mice to prove this hypothesis. It provides new targets and theoretical basis for the treatment of perioperative patients with ischemic stroke.

围术期患者由于全麻、脱水、卧床、术后制动以及禁用抗血小板或抗凝药物等原因明显增加缺血性脑卒中的发生风险。文献及预实验结果表明围术期缺血性脑卒中发生率更高、损伤更重，然而其潜在机制不明。预实验结果提示CD8+T细胞在围术期缺血性脑卒中后过度活化，并在加重缺血性脑损伤的作用中扮演了关键角色。文献报道低氧、应激等因素可使体内左旋2羟基戊二酸（L2HG）累积，L2HG升高又可导致CD8+T细胞过度活化；而我们也发现围术期缺血性脑卒中后CD8+T细胞中出现L2HG的累积。由此我们提出假说围术期缺血性脑卒中使L2HG累积，导致CD8+T细胞过度活化，CD8+T细胞通过分泌穿孔素和颗粒酶B加重了脑缺血损伤。本研究拟应用细胞共培养和条件性基因敲除小鼠等技术证明上述假说，为围术期缺血性脑卒中患者的治疗提供新的靶点和理论依据。

围术期患者由于全麻、脱水、卧床、术后制动以及禁用抗血小板或抗凝药物等原因明显增加缺血性脑卒中的发生风险。文献及预实验结果表明围术期缺血性脑卒中发生率更高、损伤更重，然而其潜在机制不明。预实验结果提示CD8+T细胞在围术期缺血性脑卒中后过度活化，并在加重缺血性脑损伤的作用中扮演了关键角色。文献报道低氧、应激等因素可使体内S-2-羟基戊二酸（S-2HG）累积，S-2HG升高又可导致CD8+T细胞过度活化；而我们也发现围术期缺血性脑卒中后CD8+T细胞中出现S-2HG的累积。由此我们提出假说围术期缺血性脑卒中使S-2HG累积，导致CD8+T细胞过度活化，CD8+T细胞通过分泌穿孔素和颗粒酶B加重了脑缺血损伤。. 通过本研究，我们证实了围术期缺血性脑卒中脑损伤更严重、神经功能包括认知功能受损更严重；CD8+T细胞消融后，围术期脑缺血损伤减轻；S-2HG通过调节CD8+T细胞增殖与活化进而加重围术期缺血性脑损伤及认知损伤。本研究提示S-2HG有潜力成为围术期缺血性脑卒中新的免疫治疗靶点。. 本项目同时与其他自然科学基金项目资助了棉籽油改善脑缺血再灌注损伤的研究，我们的结果首先探索和证实棉籽油预处理可以通过抑制小胶质细胞和星形胶质细胞的活化和炎症因子释放减轻缺血性脑卒中的脑损伤效应，棉籽油有望成为预防缺血性脑卒中的新的治疗手段。本项目还与国家重点研发计划项目资助了2型糖尿病增加围术期缺血性脑卒中长期不良预后的临床研究项目。我们结果首先验证了2型糖尿病与围术期缺血性脑卒中患者长期不良预后密切相关，2型糖尿病与围术期缺血性脑卒中共病时死亡率明显升高，提示临床诊疗中要加强糖尿病的防治。