肠道胆汁酸通过LCK/Zap70/LAT/RORs通路调节炎性因子IL17-A表达介导多发性硬化中血脑屏障损伤机制研究

多发性硬化（MS）是一种淋巴细胞浸润到中枢神经系统，导致髓鞘及轴索损伤的自身免疫性疾病。前期实验我们发现MS患者中初级胆汁酸(PBAs)含量下调；益生菌治疗可下调次级胆汁酸(SBAs)，降低外周血中Th17细胞数量；在动物实验中发现SBAs干预增加肠道粘膜固有层，外周血中Th17数量，减少BBB紧密连接蛋白表达；挖掘动物单细胞测序结果发现，SBAs干预激活了LCK/Zap70/LAT/RORs通路，并能够作促进Th17分泌IL-17A。据此我们提出假说：在MS患者中，PBAs/SBAs平衡被破坏，SBAs可激活LCK/Zap70/LAT/RORs通路，促进Th17分泌IL-17A，加重对BBB的破坏，而益生菌下调SBAs的水平，抑制这一过程。本课题后续拟通过EAE动物模型以及体外BBB细胞模型进一步研究SBAs介导BBB损伤的作用机制，为MS的治疗提供理论基础和实验依据。

Multiple sclerosis (MS) is an autoimmune disease in which the blood-brain barrier (BBB) is destructed and T lymphocytes infiltrate into the central nervous system, resulting in myelin sheath and axonal damage. In the previous experiment, the levels of primary bile acids (PBAs) were down-regulated in MS patients, while probiotics therapy can down-regulate secondary bile acids (SBAs) and reduce the number of Th17 cells in the peripheral blood. SBAs intervention has been found to increase the number of Th17 cells in the intestinal mucosa lamina propria and peripheral blood in the EAE animal model, and reduce the expression of BBB tight junction protein. However, whether SBAs is related to BBB inflammatory injury in MS/EAE and its specific mechanism are still unclear. We excavated single-cell sequencing results and found that SBAs intervention activated the LCK/Zap70/LAT/RORs signaling pathway, promoted Th17 to express IL-17A, which produce cytotoxic effects. Given this, we hypothesize that in MS, the balance of primary/secondary BAs is disrupted, and SBAs activates the LCK/Zap70/LAT/RORs signaling, promoting the expression of IL-17A in Th17, which aggravated the destruction of BBB, while probiotics can down-regulate the level of SBAs and inhibit this process. This study intends to further explore the mechanism of SBAs mediating BBB injury in the EAE animal model and in vitro BBB model, to provide a theoretical basis and experimental basis for the treatment of MS.