线粒体自噬在帕金森病肠道衰老中的作用机制及干预策略

Mitophagy has become a hot-spot in anti-aging research, because of its ability to maintain mitochondrial homeostasis, to avoid cell damage and cell senescence. Intestinal aging is an early pathological change in Parkinson's disease (PD). Previous studies have shown that mitochondrial oxidative stress can lead to misfolding of α-syn, a key PD protein that accumulates in the intestine and causes CNS lesions through the brain-gut axis. However, the exact mechanism remains unknown. Our previous high-throughput transcriptome sequencing and gut bacterial sequencing analysis found significantly abnormalities in intestinal flora and its metabolites in PD patients with intestinal mucosa mitophagy obstruction. Therefore, it is speculated that abnormal regulation of intestinal flora and metabolites on mitophagy may be an important reason of oxidative stress damage and senescence in intestinal epithelium and neuron. To further confirm this scientific hypothesis, using multi-group sequencing analysis, 3D co-culture, multi-channel laser confocal and other new technologies, this study intends to comprehensively expound mitophagy on the α-syn deposition of the intestine, to explore the mechanism of gut flora and its metabolites on intestinal mitophagy regulation and to provide novel ideas for the early diagnosis and intervention of Parkinson's disease.

线粒体自噬因其具有维持线粒体稳态、避免细胞损伤和衰老的作用，是目前抗衰老研究的热点。肠道衰老是帕金森病（Parkinson’s disease, PD）的早期病理改变，既往研究表明，线粒体氧化应激可致PD关键致病蛋白α-syn的错误折叠，后者在肠道堆积并经脑肠轴引起中枢神经病变，但具体机制不明。申请者前期通过高通量全转录组测序及肠道菌群测序分析，发现PD患者肠粘膜组织线粒体自噬通路受阻，肠道菌群及其代谢物显著异常。据此推测，肠道菌群和代谢物对线粒体自噬具有异常调控，并可能是肠道上皮及神经元氧化应激损伤和衰老的重要原因。为进一步证实该科学假设，本研究拟通过多组学测序分析、3D共培养、多通道激光共聚焦等新技术，全面阐述线粒体自噬对肠道α-syn沉积的影响、探索菌群及其代谢物对肠道线粒体自噬的调控机制，为帕金森病的早期诊断及干预提供新思路。

帕金森病（Parkinson’s disease, PD）因其高发病率和高致残率已成为重大的公共卫生问题。PD患者易出现便秘、消化不良等肠道衰老表现, 且往往早于运动症状出现数年, 提示肠道衰老是PD的早期征兆。我们通过毛刷法刷刮肠粘膜取定植菌的新方法，发现肠道定植菌相比粪便过路菌对PD具有更好的区分能力。肠道菌群参与了PD的发生发展，Butyricimonas等产丁酸菌的丰度与PD疾病严重程度成正比。伴有便秘表型的PD患者相对于普通便秘人群具有更显著的肠道菌群差异。与肠道转录组数据联合分析发现，PD患者肠道信号通路明显异常，其中产丁酸菌能够影响宿主线粒体自噬、泛素-蛋白酶体系统、多巴胺突触、脂肪酸生物合成、细胞衰老等多条关键信号通路。产丁酸菌对宿主miRNA的影响较大，尤其是Clostridium XIVb和Rhodococcus，能显著下调hsa-miR-663a、hsa-miR-4661-5p，同时上调has-miR-378b、6_13786、9_17975等miRNA，调控细胞衰老、轴突引导、多巴胺突触、自噬等与PD发生发展相关的信号通路。线粒体自噬是目前抗衰老研究的热点，肠道线粒体自噬的抑制使肠道产生氧化应激损伤，影响肠粘膜上皮营养吸收、肠道正常蠕动以及产生肠道炎症。我们发现，PD患者尤其是伴有便秘的PD患者肠道中与线粒体自噬关键蛋白PINK1表达下调，PINK1的低表达也与产丁酸菌的丰度有关，进一步研究提示，丁酸可通过抑制HDAC1/2从而影响PINK1的转录，抑制线粒体自噬。miRNA可能参与了HDAC1/2对PINK1的调控作用。另外，丁酸是否可通过调控miRNA以外泌体的形式影响中枢神经系统的PINK1的表达需要进一步验证。本项目首次分析了PD患者肠道菌群与宿主肠道信号通路的相互作用，并探索从线粒体自噬的角度理解PD肠道早期病变的发病机制，预期结果能够深入理解PD患者肠道菌群与宿主肠道衰老的关系，并为PD相关肠道衰老提供预防、诊断和治疗策略。