EphB2/ephrin-B1通路介导BMSC-EVs在溃疡性结肠炎中的免疫调节机制及复方苦参汤协同作用研究

Abnormal differentiation of CD4+T lymphocyte subsets in the lamina propria of intestinal mucosa is a key factor to the development of ulcerative colitis (UC). Studies prove that the abnormal expression of Eph family protein is associated with the onset of UC, and Eph/ephrin pathway plays an important role in the pathogenesis of UC. Bone mesenchymal stem cells (BMSCs) can regulate T cells proliferation and differentiation in UC by EphB2/ephrin-B1 pathway. A subpopulation of BMSCs expressing high levels of EphB2 has enhanced ability to engraft to the resident intestinal cellular pool. Novel findings have revealed that EphB2 can also be incorporated into exosomes (extracellular vesicles, EVs) and cause long-distance intercellular communication independently of direct cell-cell contact. The preliminary study has found that BMSC-EVs are able to travel to damaged intestinal tissue in UC by paracrine way and inhibit the inflammatory response. Compound Sophorae Decoction has a preferable therapeutic effect on UC. On the basis of above findings, we suggest that BMSC-EVs, which are over-expressed EphB2, can increase their migratory capacity to intestinal mucosa areas, and regulate the immune function of T cells through EphB2/ephrin-B1 pathway. Therefore, this research aims at using molecular biology and lentivirus infection method, to explore whether BMSC-EVs overexpressed EphB2 can enhance the ability to migrate to damaged intestinal tissue in UC, and how to amplify its immune function through EphB2/ephrin-B1 pathway to improve the healing process. This will provide a new treatment strategy for clinical treatment of UC.

肠黏膜固有层CD4+T淋巴细胞亚群异常分化是导致UC发病关键因素。研究表明,Eph家族蛋白异常表达与UC发病有关,Eph/ephrin通路在UC发生中起重要作用,BMSCs可通过EphB2/ephrin-B1通路调节UC的T细胞增殖和分化。高表达EphB2的BMSCs具有较强肠道迁移能力,EVs携带EphB2进行远距离细胞间通讯。前期发现,BMSC-EVs可经旁分泌方式到达UC受损肠黏膜发挥免疫调节作用,复方苦参汤对UC有较好疗效。因此,推断构建过表达EphB2的BMSC-EVs,可增强其迁移至UC受损肠黏膜的能力,通过EphB2/ephrin-B1通路调节T细胞的免疫功能。本课题组拟采用分子生物学、慢病毒感染等方法,研究复方苦参汤协同过表达EphB2的BMSC-EVs迁移到UC受损肠黏膜,通过EphB2/ephrin-B1通路放大其对UC的免疫作用,为开拓该病的临床治疗提供新的治疗策略。

肠黏膜固有层CD4+T淋巴细胞亚群异常分化是导致UC发病关键因素。研究表明Eph家族蛋白异常表达与UC发病有关,Eph/ephrin通路在UC发生中起重要作用,BMSCs可通过EphB2/ephrinB1通路调节UC的T细胞增殖和分化。高表达EphB2的BMSCs具有较强肠道迁移能力,EVs携带EphB2进行远距离细胞间通讯。前期发现,BMSC-EVs可经旁分泌方式到达UC受损肠黏膜发挥免疫调节作用,复方苦参汤对UC有较好疗效。本研究通过构建过表达EphB2的骨髓间充质干细胞源性胞外囊泡，建立UC模型，对囊泡进行示踪后发现过表达EphB2的骨髓间充质干细胞源性胞外囊泡可以通过EphB2/EphrinB1反向信号靶向到达肠黏膜损伤区域，可以影响 UC大鼠 Th17、Treg 细胞的分化及功能，并证明在UC大鼠中，JNK/STAT3信号通路可能参与此调节过程；之后构建UC小鼠模型, 体内实验表明复方苦参汤可通过Notch通路、抗炎、抗凋亡促增殖、降低肠道通透性及促进上皮组织修复四个方面改善肠黏膜屏障功能，缓解DSS诱导的小鼠溃疡性结肠炎。本项目研究了临床有效验方复方苦参汤在UC治疗中的可能机制，并对药物有效成分进行检测，为以后开发相关单体药物等提供依据；同时对过表达EphB2骨髓间充质干细胞源性胞外囊泡在实验性结肠炎大鼠中的抗炎、抗氧化应激、修复肠道屏障、免疫调节等作用进行研究，证明了其在动物实验中的有效作用，为UC的治疗研发新的药物提供一个新的思路。