He Xuemei, Zheng Yingqiang, Liu Shengzhi, Shi Sen, Liu Yong, He Yanzheng, Zhang Chunxiang, Zhou Xiangyu
Experimental Medicine Center, The Affiliated Hospital of Southwest Medical University, Luzhou, China.
Department of Breast and Thyroid Surgery, Chengdu Fifth People's Hospital, Chengdu, China.
J Cell Physiol. 2018 Mar;233(3):2476-2488. doi: 10.1002/jcp.26124. Epub 2017 Aug 25.
Previous studies reported that miR-146a was involved in small intestine ischemia-reperfusion (I/R) injury, but the mechanism is largely vague. Here, we aimed to identify the change of miR-146a in patients with mesenteric ischemia and explore the potential regulatory mechanism of miR-146a in intestine epithelial cells survival under ischemia and I/R injury. The plasma of 20 patients with mesenteric ischemia and 25 controls was collected to examine the miR-146a expression by qPCR. Rat intestinal epithelial cells (IEC-6) and 24 male Sprague-Dawley rats were included to build ischemia and I/R model in vitro and in vivo. The qPCR results showed that miR-146a decreased both in the plasma of patients with mesenteric ischemia and in IEC-6 cells and rat small intestine tissues in ischemia and I/R model compared to controls. Both the in vitro and in vivo results showed that I/R resulted in more severe apoptotic injury than ischemia. Cleaved-caspase 3, TLR4, TRAF6, and nuclear NF-κB p65 were up-regulated accompanying reduced XIAP and SOCS3 expression in intestinal ischemia and I/R injury. After up-regulation of miR-146a in IEC-6 cells, increased cell survival and decreased cell apoptosis were observed, concomitant with decreased cleaved-caspase 3 and down-regulated TLR4/TRAF6/NF-κB pathway. What is more, this protective effect was blocked by TRAF6 overexpression and increased nuclear NF-κB p65 nuclear. Taken together, this study revealed that miR-146a expression was decreased in small intestine ischemia and I/R injury. And miR-146a improves intestine epithelial cells survival under ischemia and I/R injury through inhibition TLR4, TRAF6, and p-IκBα, subsequently leading to decreased NF-κB p65 nuclear translocation.
先前的研究报道，miR-146a参与小肠缺血再灌注（I/R）损伤，但其机制在很大程度上尚不明确。在此，我们旨在确定肠系膜缺血患者中miR-146a的变化，并探讨miR-146a在缺血和I/R损伤下对肠上皮细胞存活的潜在调控机制。收集20例肠系膜缺血患者和25例对照者的血浆，通过qPCR检测miR-146a表达。纳入大鼠肠上皮细胞（IEC-6）和24只雄性Sprague-Dawley大鼠，分别构建体外和体内缺血及I/R模型。qPCR结果显示，与对照组相比，肠系膜缺血患者血浆、缺血及I/R模型中的IEC-6细胞和大鼠小肠组织中miR-146a均降低。体外和体内结果均显示，I/R导致的凋亡损伤比单纯缺血更严重。在肠缺血和I/R损伤中，裂解的半胱天冬酶3、Toll样受体4（TLR4）、肿瘤坏死因子受体相关因子6（TRAF6）和核因子κB p65（NF-κB p65）上调，同时X连锁凋亡抑制蛋白（XIAP）和细胞因子信号转导抑制因子3（SOCS3）表达降低。在IEC-6细胞中上调miR-146a后，观察到细胞存活率增加、细胞凋亡减少，同时裂解的半胱天冬酶3减少，TLR4/TRAF6/NF-κB通路下调。此外，TRAF6过表达和核NF-κB p65增加可阻断这种保护作用。综上所述，本研究表明，在小肠缺血和I/R损伤中miR-146a表达降低。miR-146a通过抑制TLR4、TRAF6和磷酸化IκBα（p-IκBα），改善缺血和I/R损伤下肠上皮细胞的存活，随后导致NF-κB p65核转位减少。
