GARP激活TGF-β1抑制异基因造血干细胞移植后骨髓NK细胞GⅤL效应的机制研究

急性髓系白血病（AML）患者经异基因造血干细胞移植（Allo-HSCT）后，存在复发率高、生存率低等现象，但机制不明。Allo-HSCT后可通过NK细胞介导的GVL效应清除AML细胞。我们前期研究发现allo-HSCT后AML早期复发患者骨髓中存在高水平活化型TGF-β1，CD4+T细胞高表达糖蛋白A为主的重复序列（GARP），NK细胞GVL效应低下。因GARP有助于TGF-β1的活化和分泌，我们推测复发时骨髓CD4+T细胞表达GARP促进活化型TGF-β1产生并抑制NK细胞GVL效应，导致肿瘤细胞免疫逃逸。本课题拟分析allo-HSCT后复发与未复发患者骨髓中活化型TGF-β1的水平并探究其产生机理，通过代谢组学与转录组测序寻找调控NK细胞代谢和GVL效应的关键分子，并通过细胞共培养与抗体阻断实验进行验证，从而阐明AML复发的新机制。为防治allo-HSCT后AML早期复发提供理论依据。

After allogeneic hematopoietic stem-cell transplantation (Allo-HSCT), patients with acute myeloid leukemia (AML) have a high relapse rate and low survival rate. However, little is known about the underlying mechanisms. Allo-HSCT can eliminate AML cells through the GVL effect of NK cells. In our preliminary data, we showed that patients with early relapse of AML after allo-HSCT have high level of active TGF-β1 in bone marrow, up-regulation of GARP expression on CD4+ T cells, and low GVL effect of NK cells. Based on these data, we hypothesize that the high expression of GARP in CD4+ T cells of bone marrow promotes the activation of TGF-β1 during relapse, and in turn, active TGF-β1 could lead to the impaired GVL effect of NK cells and immune escape of AML cells. To test the hypothesis, we will conduct a series of experiments as follows: we plan to analyze the level of active TGF-β1 in the bone marrow of patients after allo-HSCT, and explore the mechanism of production of active TGF-β1. Besides, we will use metabolomics and RNA-seq to investigate the regulatory roles of active TGF-β1 in regulating metabolism and GVL effect of NK cells in bone marrow of patients after allo-HSCT; and we will perform a co-culture assay, as well as experiments with the blocking antibody to clarify the new mechanism of AML relapse. It will provide an important sight for tumor immunotherapy of early relapse of AML after allo-HSCT.