TRAIL/死亡受体信号调节凋亡在肢体远程缺血预处理抗肠缺血再灌注损伤中的作用

Intestinal ischemia/reperfusion (I/R) injury is the leading cause of perioperative death. We previously found that limb remote ischemic preconditioning (LRIP) attenuated intestinal and pulmonary injury in patients undergoing elective open infrarenal abdominal aortic aneurysm repair（Li C, et al. Anesthesiology 2013）. Therefore, we employed a rat model of intestinal I/R and created LRIP via three cycles of 5-min occlusion and 5-min reperfusion of the bilateral femoral artery, and found that LRIP could attenuate intestinal injury. However, the related mechanism is not yet clear. It has been proved that apoptosis is the main form of intestinal mucosal epithelial cell death of intestinal I/R injury. Meanwhile, many studies showed that TNF- related apoptosis- inducing ligand, (TRAIL)/death receptor (DR4, DR5) signal could induce tumor cells apoptosis, but it is not clear if this signal could mediate apoptosis on the protection of intestinal ischemia-reperfusion injury by remote ischemic preconditioning. And we recently found that intestinal I /R injury could increase expression of TRAIL, DR4 and DR5 in intestinal mucous, while LRIP could decrease the expression of them. Based on the above findings, we hypothesize that activation of TRAIL/death receptor signal is one of the mechanisms of intestinal mucosal cell apoptosis and LRIP alleviates intestinal injury induced by intestinal I/R via adjusting this signal pathway. Therefore, the present study aims to verify this hypothesis via a series of in vivo and in vitro experiments including employing knockout mice and transgenic mice. This study will provide scientific basis for seeking for therapeutic targets which can be intervened in prevention of intestinal I/R injury.

肠缺血再灌注是围术期患者死亡的主要原因之一。申请者新近发现肢体远程缺血预处理（LRIP）能显著减轻腹主动脉瘤切除术患者术后肠损伤，进一步在动物实验中发现LRIP具有抗大鼠肠I/R肠损伤的作用，但机制不清楚。已证实凋亡是肠I/R后肠粘膜细胞死亡的主要形式，同时肿瘤坏死因子相关凋亡诱导配体(TRAIL)/ 死亡受体（DR4、DR5）途径诱导肿瘤细胞凋亡已得到证实，但它是否能调节肠I/R后肠粘膜细胞凋亡尚不清楚。申请者最近发现肠I/R可使大鼠肠粘膜TRAIL 及DR4、DR5表达上调，而LRIP下调它们的表达，因此推测TRAIL/死亡受体途径的激活是肠I/R后肠粘膜细胞凋亡的机制，而LRIP则调节这一通路抑制凋亡发挥肠保护作用。据此，本项目将结合动物、离体细胞模型，运用分子生物学技术，对此进行验证。本项目有望揭示肠I/R损伤及LRIP抗肠损伤的机制，为寻找防治肠损伤的新途径提供科学依据。

肠缺血再灌注是围术期患者死亡的主要原因之一。申请者新近发现肢体远程缺血预处理（LRIP ）能显著减轻腹主动脉瘤切除术患者术后肠损伤，进一步在动物实验中发现LRIP具有抗大鼠肠 I/R肠损伤的作用，但机制不清楚。已证实凋亡是肠I/R后肠粘膜细胞死亡的主要形式，同时肿瘤坏死因子相关凋亡诱导配体(TRAIL)/ 死亡受体（DR4、DR5）途径诱导肿瘤细胞凋亡已得到 证实，但它是否能调节肠I/R后肠粘膜细胞凋亡尚不清楚。申请者最近发现肠I/R可使大鼠肠粘 膜TRAIL 及DR4、DR5表达上调，而LRIP下调它们的表达，因此推测TRAIL/死亡受体途径的激活 是肠I/R后肠粘膜细胞凋亡的机制，而LRIP则调节这一通路抑制凋亡发挥肠保护作用。据此， 本项目将结合动物、离体细胞模型，运用分子生物学技术，对此进行验证。结果显示LRIP通过抑制肠I/R后肠粘膜上皮细胞凋亡从而减轻肠损伤；Survivin作为一种应激性合成蛋白在肠I/R后肠粘膜的表达增加，其抑制剂可显著降低其表达，同时肠损伤加重；LRIP通过上调Survivin的表达抑制Caspase-3的表达、抑制肠粘膜细胞凋亡，从而发挥肠保护作用。本项目揭示肠 I/R损伤及LRIP抗肠损伤的机制，为寻找防治肠损伤的新途径提供科学依据。