miR-9靶向TGFBR2诱导小胶质细胞极化失衡在术后认知功能障中的作用及金刚烷胺的干预新机制研究

Postoperative cognitive dysfunction (POCD) is a common complication in elderly patients and a critical problem needed to be solved. Our previous investigation indicated that the microglial activation plays a key role in the disease process of POCD, and that amantadine could attenuate postoperative cognitive impairment via inhibition of microglial activation. Microglial activation can be classified into two major phenotypes defined as pro-inflammatory M1 and anti-inflammatory M2 phenotype. However, a comprehensive characterization of microglial polarization after anesthetic and surgical trauma is still missing. Then we performed a pilot experiment and found that anesthesia and surgical trauma induced microglial activation toward M1 phenotype, which could be mediated through miR-9-TGFBR2 pathway. Therefore, we hypothesized that the anesthesia and surgery induced up-regulation of miR-9 could enhance the polarization of M1 microglia by targeting TGFBR2, which will result subsequent postoperative cognitive decline, while amantadine could alleviate POCD by modulation of the balance of microglial polarization via inhibition of miR-9-TGFBR2 pathway. To test this hypothesis, we will examine the relationship between the modulation of miR-9-TGFBR2 pathway on microglial polarization and POCD, and we are also determine the possible new therapeutic mechanism of amantadine concerning this pathway using in vitro BV-2 model of microglial activation exposure to lipopolysaccharide (LPS) and in vivo animal model of POCD. This investigation might determine the molecular mechanism of POCD and thereby help to provide theoretical basis for seeking an effective treatment for POCD.

术后认知功能障碍（POCD）是严重影响老年患者预后的常见并发症。目前认为小胶质细胞（MG）激活在POCD中扮演了重要角色，金刚烷胺可抑制MG激活改善POCD。MG激活后可分为促炎性M1型和抗炎性M2型，但其参与POCD的作用和机制不明。我们前期研究发现大鼠海马MG在术后向M1型极化，且这一过程与miR-9-TGFBR2（TGF-β受体2）的调控相关。由此我们认为：miR-9-TGFBR2通路介导MG极化失衡引起POCD，而金刚烷胺通过干预此过程改善POCD。我们将通过体外、体内模型，采用荧光素酶报告基因、反义寡核苷酸和慢病毒载体转染等手段，旨在探讨：①术后miR-9-TGFBR2通路和MG极化的动态变化过程；②干预miR-9-TGFBR2通路对MG极化平衡及POCD的影响；③金刚烷胺对MG极化平衡的影响。本研究将从MG极化平衡这个新视角揭示POCD的分子机制，并为POCD的防治提供新思路。

术后认知功能障碍（POCD）是严重影响老年患者预后的常见并发症。目前认为小胶质细胞激活在POCD中扮演了重要角色，小胶质细胞激活后可分为促炎性M1型和抗炎性M2型，但其参与POCD的作用和机制不明。本项目按照研究计划完成了脂多糖（LPS）刺激小胶质细胞活化的体外细胞模型miRNA-9表达的动力学过程以及与TGFBR2表达的时间关系研究，二者之间的负向表达关系在大鼠体内动物模型中得到了进一步的验证。本项目在体内动物模型实验中证实腹部手术创伤导致了大鼠术后认知功能障碍，采用Percoll梯度离心法急性分离腹部手术后第3天海马脑区的小胶质细胞进行流式细胞检测发现小胶质细胞呈M1型激活，提示手术创伤可能通过miRNA-9-TGFBR2通路诱导大鼠海马小胶质细胞M1型激活导致大鼠术后认知功能障碍。本项目在研究计划实施过程中进一步发现腹部手术创伤后第3天海马、皮层、纹状体和杏仁体等脑区的葡萄糖代谢增强，说明手术创伤诱导中枢神经系统小胶质细胞M1型激活与小胶质细胞糖代谢重编程有关；大鼠腹部创伤术后并发腹腔感染将加重中枢神经炎症反应及术后认知功能障碍；二甲双胍能够通过抑制小胶质细胞增殖、促进小胶质细胞凋亡减少LPS激活小胶质细胞炎症因子的释放。小胶质细胞代谢调控的新发现为POCD的机制研究提供了新视角；二甲双胍的中枢神经系统抗炎作用成果具有一定的转化应用价值。