PI3K/Akt/mTOR过度活化在孕期炎症刺激致子代血管重构中的作用及机制研究

Essential hypertension (EH) of unknown etiology, incidence increased yearly and life-long sympotomatic treatment, may associate with adult individual's strategy in previous studies. Under the successive supports from National Scientific Foundation Council(NSFC), we raised and verified a new hypothesis that hypertension origins from prenatal inflammatory stimulation, demonstrated that offspring hypertension, higher innate immune response and vascular reactivity abnormality produced in response to prenatal exposure to inflammation. This had been attractted the international recognition and attention, but the system needs to clarify. Traditionally, vascular remodeling (VR) is as the end of hypertension; however, our previous finding shows that VR existed prior to hypertension. PI3K/Akt/mTOR signal pathway is closely correlated with cell proliferation/immigration and its activation always results from inflammation response. Combined with our previous findings of enhanced innate immune response and early-activated PI3K/Akt/mTOR signaling in prenatal inflammation bearing offspring, we suppose that VR might be the new reason for offspring's hypertension and PI3K/Akt/mTOR activation might attribute to its mechanisms. This project will focus on the exploration of the temporal changes of VR and PI3K/Akt/mTOR signaling molecules in prenatal inflammation bearing offspring. We will further use vascular smooth muscle cell conditional knock-out mice and inhibitors of key molecules in PI3K/Akt/mTOR signal pathway to confirm the different role of PI3K/Akt/mTOR molecules in offspring's VR tissue during hypertension development. This will provide new ideas and deepen the understanding of the pathogenesis of EH and provide the experimental basis to find a new strategy of the EH intervention.

我们在NSFC连续资助下提出并证实了"高血压发生要追溯来自于孕期炎症"的新观点，发现孕期炎症刺激可致子代动物发生高血压、出现炎症高反应性和血管反应性异常，得到了国际同行的肯定与关注。传统认为血管重构（VR）是高血压的继发结果，本室则发现子代动物在高血压发生前即出现VR；鉴于PI3K/Akt/mTOR信号通路与细胞增殖等关系密切，炎症可导致其过度活化，加之预实验显示AKT、4E-BP1磷酸化显著增加和TSC2蛋白降低即PI3K/AKT/mTOR通路过度活化，为此推测VR可能是子代高血压的重要原因，其机制与PI3K/AKT/mTOR异常有关。本项目即以该通路为切入点，系统研究VR与子代高血压的关系以及该通路各关键分子在VR中的变化规律，并采用基因转染、条件性基因敲除等技术调控该信号通路，明确其异常与子代VR的关系；旨在为深化原发性高血压发病机制的认识提供新思路,并为寻找干预新策略提供实验依据。

本项目以孕期炎症刺激后子代动物血管局部PI3K/ AKT/ mTOR通路异常为切入点，系统研究该信号通路异常改变的规律、以及其与子代动物血管重构、高血压的关系。研究发现孕期炎症免疫刺激后子代大/小鼠血管组织局部mTORC1活性在出生后随着年龄的增长而逐渐升高，与子代动物出现血管重构的时相一致。mTOR抑制剂Rapamycin处理孕期炎症刺激后子代大鼠可显著逆转其血压增高、血管重构等病理改变；同时，特异性敲低血管平滑肌mTORC1活性（血管平滑肌细胞Raptor半敲小鼠模型）亦可显著逆转其血压增高和血管重构，表明PI3K-Akt-mTOR信号通路过度活化在孕期炎症刺激后子代动物血管重构及血压增高中具有关键作用。对mTORC1活性改变的机制研究发现，使用Ang II生成的抑制剂贝那普利抑制Ang II生成，耗竭循环及血管组织局部的AngII，发现贝那普利可以显著抑制mTORC1的活性；同时发现体内Ang II耗竭后的子代大鼠再次接受Ang II刺激后其mTORC1的活性在对照组和孕期炎症刺激后子代大鼠中无显著差异，说明孕期炎症刺激后子代动物PI3K-Akt-mTOR过度活化的主要机制是Ang II水平增加导致的，是一种继发性现象。此外，我们还发现心脏组织mTORC1过度活化在孕期炎症刺激后子代小鼠心脏损伤敏感性增加中具有重要作用；孕期炎症刺激后子代小鼠免疫系统异常及其在子代动脉粥样硬化敏感性增高中的作用。通过本课题初步阐明了孕期炎症刺激后子代动物PI3K-Akt-mTOR信号通路改变的规律、机制及其在子代血管重构、血压增高等中的作用， 为深化原发性高血压发病机制提供了新的思路，同时为寻找原发性高血压新的有效防治靶点提供了有益线索。在该课题资助下，进行了较广泛的国际、国内学术交流与合作（举办全国会议2次，多人次参加国际、国内学术会议，邀请国外专家来华访教1次）；培养了多名博士后及6名博士、硕士研究生，其中1名获第三军医大学优秀博士、中国药理学会2018年青年药学家奖；已发表论文8 篇（7篇SCI，10分以上2篇）。应邀作全国学术大会报告2次，分会报告2次。在此课题的基础上，获得国家自然基金重点国际合作项目1项、面上项目1项。