miRNA-151调节TLR9/TRAF6信号通路在肠I/R损伤后细菌移位的作用及机制

Bacterial translocation after intestinal ischemia/reperfusion (I/R) injury is the major cause of Multiple Organ Dysfunction Syndrom, but its pathogenes remains unclear. In recent years, researches have confirmed that TLR9/TRAF6 signaling pathways is playing a key role in regulating the immune inflammatory response. We previously found that Sup ODN(TLR9 selective inhibitor) could reduce bacterial traslocation following intestinal I/R injury. miRNAs are novel class of endogenous, small non-coding single-stranded RNAs, which could downregulate gene expression by degrading target mRNAs and/or inhibiting protein synthesis. However, the contributions of miRNAs to mediate bacterial translocation after intestinal I/R injury remain to be elucidated. We recently found that intestinal I /R injury could decrease the expression of miR-151 in intestinal mucous（Cell Death Dis, 2017）, and the we found that TLR9 is one of the negative regulated target gene of miR-151 by using of bioinformatics software. Based on the above findings, we hypothesize that intestinal I/R could down-regulating the expression of miR-151 which could activate the TLR9/TRAF6 signaling pathway and lead to bacterial translocation. Therefore, the present study aims to verify this hypothesis via a series of in vivo and in vitro experiments. 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（I/R）后肠内细菌移位是导致MODS的重要原因之一，其机制尚未明了。已证实TLR9/TRAF6信号通路在调节免疫炎症反应中发挥关键作用，申请者预实验发现TLR9抑制剂能抑制该通路的激活并显著减少肠I/R后细菌移位，提示TLR9/TRAF6通路与肠I/R后细菌移位有关。miRNA是新型的负性基因调控剂，其是否介导I/R后肠内细菌移位尚无报道。申请者新近筛选出miR-151在肠I/R后的肠粘膜组织中表达下调（Cell Death Dis, 2017），进一步采用生物信息学软件预测，发现TLR9是miR-151负性调控的一个靶基因。据此，申请者推测：肠I/R后肠粘膜miR-151表达下调，对TLR9负性调节作用减弱，从而激活TLR9/TRAF6信号导致炎症反应的发生，最终导致肠内细菌移位。本项目将通过一系列的体内外实验来验证该假说，为寻找防治肠I/R损伤可供干预的靶点提供理论基础。

脓毒症是全球关注的问题，多病因、机制复杂和高死亡率的特点。肠缺血再灌注（Ischemia/Reperfusion，I/R）是临床常见急危重症情况，它不仅导致肠损伤，还可导致肠外多个器官（肺、脑、心等）损伤，是导致内毒素血症及脓毒症的重要原因之一。肠缺血再灌注损伤后粘膜屏障破坏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，且缺乏好的防治方法。肠道菌群与疾病的关系非常密切，是近年的研究热点，但与肠I/R肠损伤及脓毒症的关系尚不明确，本项目探讨了如下内容。包括：①申请者新近筛选出miR-151在肠I/R后的肠粘膜组织中表达下调（Cell Death Dis, 2017），进一步采用生物信息学软件预测，发现TLR9是miR-151负性调控的一个靶基因。因此miR-151可能是调节肠I/R后黏膜屏障损伤的一个重要分子；②发现术前禁食24h处理通过重塑肠道菌群及其代谢产物从而减轻小鼠肠I/R损伤；③肠源性外泌体通过促进肝脏巨噬细胞M1极化介导了肠I/R导致的肝损伤；④聚合水凝胶纳米胶囊负载布比卡因药物递送系统用于局部麻醉药和疼痛管理；⑤miRNA-124-3p通过调节SP1/HDAC4/HIF-1α通路减轻脓毒症所致心肌损伤。