围术期差异改变的血浆蛋白对大脑突触可塑性的调节及其在POCD中的作用

Previous studies have shown that the occurrence of postoperative cognitive dysfunction (POCD) can be promoted by individual vulnerability, and the structures and functions of brain can be affected by aging-induced changes of plasma proteins. Based on these information, we collected the plasma with the corresponding cognitive assessment and clinical data, then detected the difference of plasma proteins between POCD and no-POCD aged patients via isobaric tags for relative and absolute quantitation (iTRAQ). We found 149 plasma proteins with the intergroup difference. Among these, we confirmed four proteins DPP4、NID1、TCN2 and APOC1 were significantly changed by Elisa. Previous data have shown that these four proteins are closely involved in the synaptic plasticity. So, we proposed that the perioperative changes of plasma proteins affect the occurrence and development of POCD via modulating the synaptic plasticity. In our study, firstly we will detect the relationship between the four proteins and aged POCD patients and rats, and the mechanisms that these four proteins how to modulate the synaptic plasticity. Secondly we will investigate the relationship of other proteins to POCD and their mechanisms modulating synaptic plasticity. Thirdly, we will pick up the confirmed differential plasma proteins associated closely with POCD and build a model using the differential proteins and clinic data to predict the occurrence of POCD. Finally, we will verify the accuracy of the model in aged patients. Our results will comprehensively and systematically clarify that the change of perioperative plasma proteins how to affect the occurrence and development of POCD. In addition, our data will provide new information for the prevention, treatment and prediction of POCD.

基于个体易损性增加对术后认知功能障碍（POCD）发生的影响、血浆蛋白的年龄特性及其对大脑功能的调节，我们收集了POCD和非POCD患者的血浆标本行蛋白定量检测，筛选出149个具有组间差异的血浆蛋白,并初步验证了DPP4、NID1、TCN2、APOC1的差异改变，文献证实这四种蛋白与突触可塑性密切相关，结合突触可塑性与POCD的关系，我们推测围术期差异改变的血浆蛋白通过调节大脑的突触可塑性从而影响POCD的发生发展。为此，本项目拟行：1）进一步明确DPP4、NID1、TCN2、APOC1的蛋白水平与老年病人和老年大鼠POCD的相关性及其调节突触可塑性的机制；2）验证其它血浆差异蛋白并探索其作用机制；3）筛选与POCD发生相关的血浆差异蛋白，构建POCD的预测模型并验证其准确性。从而较系统阐明血浆蛋白的差异改变对POCD发生发展的影响，为POCD的防治和预测提供新的依据。

本项目计划探索围术期差异改变的血浆蛋白对大脑突触可塑性的调节及其在POCD中的作用。该项目的预实验结果是基于我们在北京蛋白质组研究中心用iTRAQ技术发现的差异蛋白及其小样本的ELISA方法验证。在项目执行过程中，当我们对iTRAQ技术发现的差异蛋白进行大样本的ELISA检测时，发现：围术期血浆蛋白的个体间差异很大，血浆蛋白组学发现的差异蛋白不能被ELISA方法重复验证。为了保证研究的客观性和可重复性，我们把研究计划调整为探索：1）血浆蛋白APOC2在脑老化和POCD中的作用及其机制，2）围术期益生菌干预对POCD的预防作用及其可能机制，3）β-羟丁酸对脓毒症脑病的防治作用及其机制；4）POCD的术前预测量表；5）益生菌干预对化疗脑损伤的预防作用及其机制；6）miR-124在正常脑老化中的作用及其机制。.发现：1）发现血浆蛋白APOC2水平随年龄增加而增加。外源性的APOC2能损伤培养的人血管内皮细胞、抑制其增殖。大鼠尾静脉注射的APOC2质粒大部分沉积在肝，实现肝APOC2过表达，从而升高血浆APOC2，损伤血脑屏障、突触和认知功能，加重术后脑损伤。2）围术期益生菌干预可显著降低老年患者POCD发生率、外周炎症和糖皮质激素水平，但对疼痛、睡眠、胃肠功能无显著影响。3）系统性给予β-羟丁酸能够显著降低脓毒症导致的死亡率，并且改善外周和中枢炎症，以及改善认知损伤，而β-羟丁酸的这种脑保护作用，主要通过HCA2 （β-羟丁酸受体）和 MCT2（β-羟丁酸转运体）来起作用。4）由年龄、术前认知储备、术前脑功能储备、术前日常休闲活动＜6项、术前疾病及ASA分级≥3级构建的POCD风险评估量表能较好的预估POCD风险。5）益生菌干预可显著减轻乳腺癌患者的化疗脑损伤、改变患者肠菌构成，调节其外周血代谢物水平，具有很好的安全性。进一步机制发现，在差异改变的血浆代谢物中，益生菌能增加小鼠外周血紫苏醇水平，给予外源性紫苏醇能减轻化疗药对脑结构和功能的影响。6）在脑老化过程中，脑内miR-124进行性丢失.而miR-124敲除复制脑老化的核心表型---如学习记忆障碍、神经元和突触丢失、神经炎症、LTP损伤、LTD出现。RYR3是miR-124的直接下游靶点，抑制RYR3可部分逆转miR-124敲除诱导的表型。