调节性B细胞抑制急性GVHD保留GVL效应的机制研究

After allogeneic hematopoietic stem cell transplantation (allo-HSCT), T lymphocytes contribute to the graft-versus-leukemia, and reduce the ratio of recurrent. However, T lymphocytes also lead to acute graft-versus-host disease (GVHD), which remains the most lethal complications after allo-HSCT. Regulatory B cells (Breg) is a new kind of immune cells，which can secrete IL-10 and regulate T lymphocytes. Our studies found that Breg could promote acute GVHD prevention and maintain graft-versus-leukemia activity (GVL), but the mechanisms of which have not been elucidated. Previous studies suggested that Breg may regulate T cells and several cytokines, but whether its effect is via specific T cells (to take) or activate NK cells to kill leukemia cells is not yet clear. Moreover, researches found that suppress pathways such as JAK and PD-L1 can reduce GVHD and preserve GVL, and Breg can regulate these pathways. This may also be the mechanism of the effect of Breg. This research plan to prove Breg reducing GVHD and preserving GVL via regulating cytokines and immune cells and suppressing pathway as JAK or upgrade PD-L1 in both mouse transplant model and ex vivo experiments. The eluciation of the effects and mechanisms will contribute to establish a novel method,and provide theoretical basis for this method of reducing acute GVHD and sparing the GVL effect.

异基因造血干细胞移植供者的T细胞发挥移植物抗白血病（GVL）效应，抑制复发；但T细胞会引起急性移植物抗宿主病（aGVHD），是移植患者主要并发症和死亡原因。调节性B细胞(Breg)是一种新型免疫调节细胞，申请人前期工作发现Breg可以预防aGVHD又能保留GVL效应，但其机制仍不清楚。进一步研究提示Breg可以调控T细胞及细胞因子，但Breg的GVL作用是通过特定T细胞抗白血病还是通过激活NK等免疫细胞对白血病细胞杀伤，其途径尚不清晰。研究发现抑制JAK和上调PD-L1通路均可减轻aGVHD不影响GVL，而Breg是否能调控这些通路尚未见研究。本项目将通过小鼠模型和体外实验：①阐明Breg减轻aGVHD保留GVL的机制；②证明Breg调控细胞因子增加免疫细胞作用及调控JAK、PD-L1通路而减轻aGVHD保留GVL的机制（科学问题）。为利用免疫调节细胞预防aGVHD及复发的新方法提供依据。

异基因造血干细胞移植供者的T细胞发挥移植物抗白血病（GVL）效应，抑制复发；但T细胞会引起急性移植物抗宿主病（aGVHD），是移植患者主要并发症和死亡原因。调节性B细胞(Breg)是一种新型免疫调节细胞，前期工作发现Breg可以预防aGVHD又能保留GVL效应。本项目研究发现：1.体内应用G-CSF可明显提高体内Breg及记忆B细胞数量，模型-记忆性B细胞组细胞比率显著上升（P<0.01）。调节性B细胞总数为8.94*105 cells，记忆性B细胞总数为8.88*105cells，模型-调节性B细胞总数为1.08*106 cells，模型-记忆性B细胞总数为1.18*106cells。 本项目重现了负责人在其他中心的急性GVHD模型，急性GVHD组评分d14最高分为5分，同时Breg可减轻急性GVHD，最高分为1分，Breg组GVHD评分优于急性GVHD组，p<0.05。本项目对Breg减轻急性GVHD进行了机制研究，其机制为Breg调控诱导T细胞的分化，通过检测细胞内IFN-γ和转录因子T-bet均提示Breg具有下调Th1发挥对急性GVHD的负调控作用，另外，暂时不能说明Bregs通过调控Th2/Th17/Tregs负调控急性GVHD。同时推测Breg调控多种细胞因子及对某些细胞通路产生影响。Breg对细胞引起及细胞通路JAK和PD-L1影响的实验仍在进行中。本项目为预防aGVHD及复发的新方法提供依据。