肠道菌群丁酸代谢紊乱通过多糖包被降解加重糖尿病脑缺血再灌注损伤研究

Dysbiosis of gut microbiota disrupts the integrity of blood-brain barrier (BBB) and aggravates cerebral ischemia reperfusion injury (CIRI), nevertheless, its mechanism is still unclear. Our previous work confirmed that cerebrovascular glycocalyx degradation may contribute to BBB disruption and activation of neuroinflammation. Recently, we found the gut microbial community in T2DM patients was significantly altered with decreased butyrate producing bacteria. Fecal microbiota transplantation from T2DM to mice models damaged glycocalyx, increased BBB permeability, induced inflammation and exacerbated injury. Butyrate has proved to alleviate BBB disruption via inhibition of HIF-1α/VEGF pathway. Therefore, we hypothesize that the decrease of butyrate in T2DM patients and compromised glycocalyx lead to an increase of BBB permeability and aggravation of CIRI. By using CIRI murine model, HUVEC cells line and a clinical cohort of stroke patients, we aim to explore the pathophysiological effects of butyrate metabolism disorders, glycocalyx degradation and BBB damage during CIRI. The present study could shed light on the novel mechanism for the poor prognosis of stroke in T2DM patients, and provide a new target in microbiota-based prevention and treatment strategies for stroke patients.

肠道菌群紊乱破坏血脑屏障（BBB）完整性而加重脑缺血再灌注损伤(CIRI)，但其机制未明。课题组前期研究证实脑血管内皮细胞多糖包被降解可导致BBB损害、脑内炎症活化。课题组新近发现，2型糖尿病(T2DM)肠菌紊乱主要表现为产丁酸菌丰度下降。移植T2DM肠菌使得小鼠脑血管内皮细胞多糖包被降解，BBB通透性及炎症因子表达增加，从而加重CIRI。丁酸已被证实通过抑制HIF-1α/VEGF通路发挥对BBB的保护作用。据此假设：T2DM肠道菌群产丁酸水平下降，对多糖包被保护作用减弱，导致BBB通透性增加并加重CIRI。本项目拟采用CIRI小鼠模型、HUVEC细胞体外培养实验和轻中度卒中临床队列，从肠菌紊乱角度探讨肠道丁酸代谢紊乱、多糖包被降解、BBB损害在CIRI中的病理生理作用。研究结果有利于阐明T2DM患者卒中预后不良的新机制，为以肠道菌群为靶标的卒中预防和治疗策略提供新依据。

项目背景：二型糖尿病（T2D）加重急性缺血性脑卒中（AIS）损伤，同时T2D患者肠道菌群紊乱表现为产丁酸菌丰度的降低，因此我们假设补充丁酸可缓解T2D的AIS损伤。.主要研究内容：我们首先检测了合并和不合并T2D患者的肠道菌群及丁酸代谢水平。基础实验部分，我们使用丁酸钠（SB）或氯化钠（NaCl）对T2D小鼠进行为期4周的干预，干预完毕后收集粪便以检测肠菌及丁酸水平。我们收集干预2周后粪便并对抗生素干预后的C57BL/6小鼠进行粪菌移植，移植2周后检测受体小鼠的肠道菌群及丁酸水平，并进行脑卒中造模。.关键数据：我们发现T2D患者肠道产丁酸菌丰度显著降低。丁酸钠可显著缓解T2D小鼠的代谢表型、肠道菌群及脑损伤。移植了丁酸干预后菌群的小鼠，脑损伤损伤显著减轻，肠屏障功能改善、血清脂多糖（LPS）、LPS结合蛋白（LBP）及炎症因子水平降低，以对血脑屏障多糖包被提供保护作用。.科学意义：AIS是全球主要的健康负担，T2D是一种常见合并症，可加重AIS后的脑损伤。 然而，T2D加重AIS损伤的内在机制尚未完全阐明。我们的研究结果表明，T2D 的肠道菌群可改善AIS的脑损伤，并可被丁酸所调节，调节后菌群对脑损伤提供神经保护作用。 这些结果表明，补充丁酸是一种缓解T2D患者缺血性脑损伤的潜在策略。