miR-378调控肠粘膜细胞凋亡在肠缺血再灌注所致肠损伤中的作用及机制

The mechanism related to intestinal mucosal barrier injury following ischemia/reperfusion (I/R) is not yet clear. We previously found that aopotosis was the main mode of intestinal mucosal cell death after intestinal I/R, accompanied by increased expresssion of Caspase-3. miRNA is a novel negative gene regulation factor.We recently found 18 differentially expressed miRNAs in intestinal mucosa after intestinal I/R were down regulated. Of them, miR-378 was confirmed and futher analysis by compute assisted biological informtion method showed that Caspase-3 is one of the target genes of miR-378. Accordingly, we hypothesize that miR-378 attenuates intestinal mucosal cell apoptosis by suppressing the expression of Caspase-3 and thereby attenuates intestinal injury induced by intestinal I/R.Therefore, the present study aims to verify this hypothesis via a series of in vivo and in vitro experiments including establishing intestinal I/R injury model of rats, hypoxia/reoxygenation model of intestinal mucosal epithelial cells, and employing miR-378 mimic and inhibitor、miR-378 transgenic mice and inhibitor of Caspase-3 .This study will provide scientific basis for seeking for gene targets which can be intervened in prevention of intestinal I/R injury.

肠缺血再灌注（I/R）后肠粘膜屏障损伤的发生机制尚未完全明了。我们既往研究发现肠I/R后肠粘膜细胞的死亡以凋亡为主，同时凋亡相关蛋白Caspase-3的表达上调，因此抑制凋亡是防治肠I/R肠损伤的有效手段。miRNA是新型的负性基因调控剂，其是否能调控肠粘膜细胞凋亡尚无报道。我们最近采用miRNA微阵列基因芯片技术发现，在肠I/R后的肠粘膜组织中有18个miRNA表达下调，其中miR-378被证实，进一步采用计算机生物信息学软件预测发现 Caspase-3是miR-378调控的一个靶基因。据此，我们首次提出miR-378负性调控Caspase-3的表达从而抑制肠粘膜细胞凋亡、继而产生抗肠I/R肠损伤作用的假说。本项目拟采用miR-378 激动剂及抑制剂、miR-378转基因小鼠，通过一系列的体内、体外实验来验证该假说，为寻找防治肠I/R损伤可供干预的基因靶点提供理论基础。

肠缺血再灌注是患者围术期发生多脏器衰竭及死亡的原因之一，但确切的机制不清楚，且尚未好的防治方法。本项目探讨了如下内容。包括：①发现miR-378可能是调节肠I/R后肠损伤的一个重要因素。②发现肢体远程缺血预处理显著减轻肾下型腹主动脉瘤切除人工血管置换术患者术后肠及肺损伤；③发现缺血后处理通过醛糖还原酶介导的氧化防御和凋亡抑制作用减轻肠I/R引起的肠损伤；④发现上肢肢体远程缺血预处理显著改善单肺通气下肺切除术患者肺氧合，降低肺损伤的发生率及在院并发症发生；⑤发现临床上常用的镇静药右旋美托咪定对肝门阻断下肝癌切除术患者术后肠、肝具有保护作用。⑥发现M2型巨噬细胞向M1型转化是肠I/R后肠损伤及动物生存率下降的主要机 制，并发现重组旋毛虫蛋白通过促进M1巨噬细胞向M2的转化有效地抑制肠粘膜细胞 凋亡、改善肠损伤及提高动物生存率。