线粒体稳态失衡在孕期炎症刺激致子代小鼠心脏损伤敏感性增加中的作用及机制研究

Under the successive supports from National Scientific Foundation Council, we raised and verified a new hypothesis that cardiovascular diseases origin from prenatal inflammatory stimulation (PIS). We further found that offspring of PIS showed myocardial remodeling accompany by compensatory enhanced cardiac function before cardiac dysfunction occurred, but showed obvious exacerbated cardiac injuries when challenged with isoproterenol (ISO) stimulation. However, the detailed mechanisms are largely unknown. Mitochondrial homeostasis has a critical role in cardiac function maintain and compensation, and mTORC1 in turn plays an important role in promoting mitochondrial homeostasis, such as mitochondrial biogenesis. Our preliminary data showed that mitochondrial biogenesis and mTORC1 activity were significantly increased under resting state, but were reversely decreased when challenged with ISO in offspring of PIS at the age of 16 weeks. By using cardiac conditional knockout technology, recovering mTORC1 activity to the normal level after birth could reverse the mitochondrial dyshomestasis together with cardiac function protection. By combining all these evidence together, we proposed that mTORC1 activity abnormality mediated mitochondrial dyshomestasis plays a critical role in the increased sensitivity of cardiac damages in offspring of PIS. By using the strategy of cardiac conditional knockout mice and ect, we will confirm the role of mTORC1 activity abnormality mediated mitochondrial dyshomestasis in the the hypersensitivity of cardiac damage responding to cardiac risk factors in offspring of PIS. This will provide new ideas and deepen the understanding of the pathogenesis of cardiac diseases. It will also provide the experimental basis to find a new strategy of cardiac diseases intervention.

我们发现PIS致子代动物心脏损伤敏感性增强，但机制亟待阐明。鉴于线粒体稳态对心功能的至关重要和mTORC1在维持线粒体稳态中的关键作用，结合预实验发现PIS导致子代心功能障碍前出现心肌重构、代偿性心功能增强，且对异丙肾上腺素（ISO）再刺激心脏损伤敏感性明显增强；ISO再刺激后线粒体生物合成由增强转为显著抑制，心脏组织mTORC1由持续活化转为活性抑制，且与心脏线粒体稳态失衡和心功能降低呈一致性变化；采用敲基因技术恢复心肌mTORC1活性，不仅逆转ISO刺激后线粒体稳态失衡、且降低心脏损伤敏感性；为此推测mTORC1信号异常介导的线粒体稳态失衡在PIS子代心脏损伤敏感性增加中具有重要作用。本项目即以线粒体稳态失衡为切入点，采用条件性基因敲除等技术，明确其在心脏损伤敏感性增加中的作用及机制；旨在为探明PIS子代易患心血管疾病的机制提供新思路，并为寻找防治新策略提供实验依据。

本项目以本团队自行建立的孕期炎症刺激（Prenatal inflammatory stimuli，PIS）致子代小鼠心脏损伤敏感性增高为切入点，首先系统分析了PIS子代小鼠不同时相点心肌细胞线粒体结构、功能、mTORC1信号通路活性及关键调控因子改变规律及其与心肌损伤敏感性增高的关系；继之构建心脏条件性敲低mTORC1 活性动物模型，明确mTORC1信号异常在子代心脏损伤敏感性增加中的作用；第三，通过质谱分析子代小鼠心脏代谢变化，并探索了干预子代饮食成分在改善PIS子代小鼠心脏损伤敏感性增加中的作用及相关机制。在圆满完成本项目研究目标的同时，还新发现并鉴定了心脏局部存在特异性的II型固有淋巴细胞；新阐明了在有基础心脏损伤的背景下（ISO暴露），iNKT细胞激活可以促进心脏损伤和炎症的进展的分子机制。总之，本项目对PIS诱发子代心脏线粒体稳态失衡的改变规律、机制及其在子代心脏损伤敏感性改变上作用的系统研究，为深化对心脏重构发病机制的认识及寻找心脏重构新的有效防治靶点提供了新的思路和理论依据。在课题资助下，课题组成员进行了广泛的国内、国际学术交流（主办国内会议1次；课题组20余人次参加国际、国内学术会议）；培养研究生8名（其中，博士5名，硕士3名），培养出站博士后2名；获批国际发明专利1项，申请国防专利1项。已发表SCI论文7篇，其中10分以上2篇， 5-10分4篇。