TRAF5通过Runx1调控结肠炎小鼠肠道Th1/Th17细胞相互转化的机制研究

The mutual transformation of Th1 and Th17 cells is common in IBD patients and colitis mice. Runx1 plays important roles in their transformation. Our previous study indicated that TRAF5’s deficiency could significantly enhance the expression of Runx1 and the ratio of CD4+IFN-γ+IL-17a+ cells in the colons of colitis mice. Furthermore, bioinformatics results showed that there were multiple linkages between TRAF5 and Runx1. Therefore, we hypothesized that TRAF5 might regulate the mutual transformation of Th1 and Th17 cells via Runx1. In this study, we intent to use TRAF5 knockout and transgenic mice to construct the CD4+CD45RBhi T cells, Th1 cells and Th17 cells induced colitis models. Moreover, by the means of RNA interference and adenovirus transfection, we up-regulate and down-regulate the expression of Runx1 and to investigate the possible mechanism by which TRAF5 regulates the mutual transformation of Th1 and Th17 cells through Runx1. Our study will further clarify the roles of TRAF5 in the pathogenesis of IBD and will provide a new strategy for its treatment.

炎症性肠病（IBD）患者及结肠炎小鼠体内普遍存在Th1/Th17细胞相互转化的现象，Runx1在其相互转化过程中发挥重要作用。我们前期研究发现肿瘤坏死因子受体相关因子5（TRAF5）基因缺失显著增加DSS模型小鼠肠黏膜Runx1的表达及中间状态CD4+IFN-γ+IL-17a+ T细胞的比例，且生物信息学研究表明TRAF5与Runx1蛋白间存在密切联系，提示TRAF5可能通过Runx1调控Th1/Th17细胞间的相互转化。本项目拟利用TRAF5基因敲除及转基因小鼠构建CD4+CD45RBhi T细胞、Th1及Th17细胞过继转移性结肠炎模型，同时运用靶向RNA干扰及腺病毒转染技术分别下调或上调Runx1的表达，通过体内及体外实验研究TRAF5通过Runx1调控Th1/Th17细胞相互转化的作用机制，从而进一步阐明TRAF5在IBD发病中的作用，并为IBD的诊疗提供新思路。

本研究中，我们首先通过构建 CD4+CD45RBhigh T 细胞过继转移性小鼠结肠炎模型，研究CD4+T细胞中TRAF5基因缺失对结肠炎小鼠的粘膜炎症及肠道Th1/Th17细胞分化的影响，初步证实了TRAF5在小鼠过继转移性结肠炎中发挥抗炎的作用，并抑制Th1/Th17细胞的分化和免疫应答。接着，我们通过对CD4+T细胞中TRAF5基因缺失和未缺失的炎症小鼠肠道组织中Runx1的mRNA和蛋白表达水平进行检测，发现TRAF5基因缺失的CD4+T细胞受体鼠的Runx1表达水平明显上调，证实TRAF5可以显著抑制转录因子Runx1的表达，与我们前期研究DSS肠炎模型中得到的结论一致。最后，我们通过活体腺病毒干扰技术在体敲低小鼠体内Runx1的表达，通过构建CD4+T细胞过继转移性结肠炎模型，证实TRAF5通过抑制转录因子Runx1的表达进而调节结肠炎小鼠体内Th1/Th17细胞分化。本研究通过一系列分子生物学实验技术阐明了TRAF5在小鼠结肠炎中的具体抗炎机制，从而为临床IBD的诊疗提供了一种新思路。