调控T细胞CCR7表达异基因造血干细胞移植后aGVHD的影响及其免疫机制研究

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the most effective therapy for some malignant hematologic diseases, while acute graft versus host disease (aGVHD) is one of the most important complications affecting the efficacy of HSCT. The migration of T cells mediated by C-C chemokine receptor type 7 (CCR7) plays an important role in the pathogenesis of GVHD. Our previous study indicated that the expression level of CCR7 on T cells in both the donors and rcipients were both related with the occurrence of aGVHD after allo-HSCT. These data suggest that regulating the expression of CCR7 on T cells could influence the presence and development of aGVHD, however the mechanism remains unclear and controversial. In this study, we will try to probe and even demonstrate the precise immunologic mechanism of CCR7 involved in aGVHD from different levels including the molecular, cellular and the level of the whole body, applying a series of cell model and mice model of aGVHD and using flow cytometry, Western blotting and transwell migration assay. Regulating CCR7 expression might influence the function of CD4+CD25+ regulatory T cells (Tregs) and T helper (Th) type 17 cells, cause the imbalance of Th1/Th2/Th17/Treg cells, affect the abilities of effector T cells of releasing cytokines and trafficking to GVHD target organs, and even effect on the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) and p38 mitogen-activated protein kinase (MAPK) signaling pathways. This study will contribute to a better understanding of the development mechanism of aGVHD and provide new evidence that targeting CCR7 may be a promising therapeutic strategy for the prevention and treatment of aGVHD.

急性移植物抗宿主病（aGVHD）是异基因造血干细胞移植后的重要并发症，也是导致移植失败的主要原因之一。CCR7介导的T细胞迁移是移植后aGVHD发病机制的重要环节。我们的前期研究提示移植供者及受者T细胞CCR7的表达均与aGVHD的发生密切相关，但其具体机制尚不明确。本项目拟在前期工作基础上通过一系列细胞及小鼠模型，采用流式细胞分析、蛋白质免疫印迹试验及趋化实验等技术，明确调控T细胞CCR7的表达对Th1/Th2/Th17/Treg 细胞平衡的影响，对效应T细胞分泌炎症因子及向GVHD靶器官迁移等功能的影响，对PI3K/Akt和p38 MAPK细胞信号转导通路的影响，分别从分子、细胞、组织、动物整体等多层次明确调控T细胞CCR7表达对移植后aGVHD的影响，探讨CCR7在aGVHD发生中的具体免疫机制。研究结果将可能有助于进一步阐明aGVHD的发病机制，为靶向防治aGVHD提供新的思路。

急性移植物抗宿主病（aGVHD）是异基因造血干细胞移植后的重要并发症，也是导致移植失败的主要原因之一，趋化因子及其受体介导的T细胞向靶器官的迁移是aGVHD发生的关键环节。我们预实验结果提示移植供者及受者T细胞CCR7的表达强度均与aGVHD的发生密切相关。以上资料提示CCR7介导的T细胞的迁移在aGVHD的发病机制中发挥重要作用，但其具体机制尚不明确。本课题组在前期工作的基础上通过体外和体内实验调控T细胞CCR7的表达，探讨CCR7在aGVHD发生发展中的作用。课题组建立了一系列细胞及小鼠aGVHD模型，采用RT-PCR、western blot、流式细胞分析及趋化实验等技术，分别从分子、细胞、组织、动物整体等多层次明确调控T细胞CCR7表达对移植后aGVHD的影响，进一步明确CCR7在aGVHD发生中的具体免疫机制。结果发现：调控T细胞CCR7的表达，能够影响T细胞的功能。抑制T细胞CCR7表达，能促使Th1/Th2/Th17/Treg细胞平衡改变，Th1细胞比例下降，Th17及Treg细胞比例增高，促使Th1向Th17或Treg细胞转化，抑制效应T细胞分泌炎症因子IFN-γ及TNF-α等，并抑制效应T细胞的增殖及趋化能力，同时抑制PI3K/Akt和p38 MAPK细胞信号转导通路，从而影响移植后aGVHD的发生。结果表明，CCR7介导的T细胞的趋化和迁移在aGVHD发病中起重要作用，有助于进一步阐明aGVHD的发病机制，为靶向防治aGVHD提供新的思路。