干预RORγt保护小鼠心脏移植排斥反应及诱导耐受的机制研究

The latest study found that IL-17A + cells (mainly including the iLC cells, γδT cells, Th17 cells) play an important role in the regulation of the immune microenvironment,and contribute to acute allograft rejection and acts as a barrier to the induction of transplant tolerance. Our previous experiments confirmed digoxin attenuates acute cardiac allograft rejection by antagonizing ROR γt activityant, increases spleen and graft ratio and the number of local regulatory T cells.However, little is known about the mechanism of ROR γt in Th17 and γδT cells acute allograft rejection and the stability and suppression function of Treg cells. In this project, IL-17A and ROR γt deficient mice are used and their function in Th17 and γδT cells mediating allograft rejection are investigated.Moreover,we willinvestigated that RORγt + cell subsets after heart transplantation central role in the peripheral immune organs and graft local microenvironment, and ultimately mediated transplant rejection the mechanism of the reaction; vitro mixed cell culture and differentiation of Treg transformation experiments clearly RORγt + cells regulate the differentiation and proliferation of T cells and DC maturation mechanism and affect Treg differentiation and proliferation, stability and inhibit the function mechanism. The implementation of this project will explore the new target through the intervention transplant microenvironment induced tolerance, clear RORγt + cell subsets transplant microenvironment regulation mechanisms to provide more basic research support, which will give support to our better understanding of the mechanism of acute allograft rejection and tolerance induction in transplantation.

最新研究发现分泌IL-17A细胞(主要包括iLC细胞、γδT细胞、Th17细胞)在免疫微环境的调控中发挥着重要的作用，其都表达RORγt。我们前期实验证实拮抗RORγt能显著延长小鼠心脏移植物的生存期，增加脾脏和移植物局部调节性T细胞的比率和数量，但其具体机制尚不明确。本课题将利用选择性细胞过继的小鼠异位心脏移植模型，进一步研究RORγt+细胞各亚群在心脏移植后中枢、外周免疫器官及移植物局部微环境中的调控作用，及最终介导移植排斥反应的机制；利用体外混合细胞培养和Treg的分化转化实验，明确RORγt+细胞调控T细胞分化增殖及DC细胞成熟的机制，及影响Treg分化增殖、稳定性和抑制功能的机制。本课题的实施将探索通过干预移植微环境诱导耐受的新靶点，明确RORγt+细胞各亚群对移植微环境的调控机制，为诱导和维持移植耐受提供更多的基础研究支持，也为更好理解免疫防御和耐受提供新思路。

分泌 IL-17A 细胞(主要包括 iLC 细胞、γδT 细胞、 Th17 细胞)在免疫微环境的调控中发挥着重要的作用，均表达 RORγt。本项目通过选择性细胞过继的小鼠异位心脏移植模型阐明（1）与RORγt高度相关的PPARγ缺乏通过影响CD4+T细胞的分化和巨噬细胞的活化增强了移植排斥反应，证明RORγt对CD4+ T细胞分化和增殖的调节作用及对排斥反应影响具有重要意义（2）阐明TH17/RORγt信号通路高度相关的microRNA-miR155在慢性移植发生中的作用及机制，发现敲除miR155有明显减轻CAV病变的作用，并证实是IL17A起到关键作用，推进了miR155/TH17/RORγt环路在慢性排斥反应发病机制的研究进程；（3）明确了RORγt分子和其它孤儿核受体促进T细胞活化后凋亡减轻心脏排斥反应的效应及相关机制，在小鼠心脏移植模型中联合使用CsA和CsnB，发现其可产生协同作用，显著促进Csa的促移植物存活效果，体内实验则证实Nur77激动剂CsnB可有效逆转Csa对T细胞活化后凋亡及Treg分化的抑制作用；（4）阐明阻断RORγt高度相关的TLR4受体通路影响了巨噬细胞炎症因子的分泌，诱导免疫耐受的发生。本项目已完成原计划设计的研究，验证了RORγt及相关的分子在诱导和维持移植耐受的相关机制，而且在该研究基础上，取得了机制上新的研究进展。