FLI-1基因甲基化在造血干细胞移植后持续性血小板减少中的作用和机制研究

Prolonged isolated thrombocytopenia (PT) showed impaired megakaryocyte maturation and insufficient platelet production, is a serious complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Friend leukemia virus integration 1 (FLI1) acts as a driver in FLI1 regulates its expression, thereby, DNA demethylation in the FLI1 regulates its expression. Moreover, our experiment found reduced FLI1 expression in PT patients, PT bone marrow plasma could inhibit megakaryocyte maturation and platelet production, which could be significantly inhibited by demethylating agent. In this study, we plan to use megakaryocytes cultures in vitro and a nude mice model transplanted with human MDS cell line SKM-1 cells as study objects and conduct experiment in vitro and in vivo. The aim is to study the role of FLI1 methylation in the regulating its expression on megakaryocyte dysdifferentiation in PT, and to explore the possible therapeutic targets, which may provide novel insights into PT treatment.

持续性血小板减少（Prolonged isolated thrombocytopenia，PT）是异基因造血干细胞移植（allo-HSCT）严重的并发症，表现为巨核细胞减少和巨核分化障碍。Friend白血病病毒整合1（FLI-1）在造血干细胞向巨核细胞分化成熟中发挥重要作用，FLI-1基因甲基化水平调控FLI-1表达。前期试验证实：PT巨核细胞FLI-1低表达，PT骨髓血浆诱导CD34+细胞向巨核细胞分化障碍，去甲基化制剂可逆转巨核分化障碍，为此，我们提出假说：PT造血微环境促进FLI-1基因甲基化，抑制FLI-1表达，抑制allo-HSCT后造血干细胞向巨核细胞分化。本项目将以骨髓来源CD34+细胞巨核细胞体外培养系统和SKM1荷瘤小鼠造血干细胞移植模型为对象，探讨FLI-1基因启动子甲基化调控FLI-1表达对巨核细胞分化的影响，明确其在PT中的治疗作用及具体机制，寻求PT治疗新思路

嵌合抗原受体修饰的T细胞（chimeric antigen receptor T cell therapy，CAR-T）疗法作为肿瘤免疫治疗中最为引人瞩目的翘楚，在治疗R/R 的B 系肿瘤中获得巨大成功，如：急性B淋巴细胞性白血病、非霍奇金淋巴瘤和多发性骨髓瘤等。然而CAR-T疗法在AML的治疗中尚未显现出明显优势，其最核心的问题是至今尚未找到类似CD19兼具有效性和安全性的靶点。尽管先后有Leiws Y、CD33、CD123、CD44v6、NKG2D-L和FRβ等髓系靶点的相关研究，但大部分存在效率低、脱靶效应等严重副作用，限制其大规模临床应用。因此，R/R AML患者的CAR-T治疗仍然是白血病领域亟待解决的难点和重点。.通过前瞻性临床研究证实CD38 CAR-T治疗R/R AML的疗效和安全性；R/R AML患者T细胞存在免疫抑制，靶向CD38 CAR-T可以逆转AML患者免疫负性微环境；R/R AML肿瘤细胞和Treg诱导T细胞衰老，CD38+PD1+T细胞亚群衰老更显著。.我们前期运用靶向CD38、CD7、CLL1和CD19等不同靶标治疗R/R AML，并取得一定成功，但髓系CAR-T仍存在疗效不如CAR-T在B系肿瘤的运用，AML免疫微屏障是可能是影响髓系CAR-T发挥的重要因素，CAR-T细胞治疗AML临床疗效和免疫微环境研究在国内外均远未完善。我们拟通过全面深入分析CAR-T治疗疗效与免疫微环境信号通路和信号分子关系，探寻影响疗效的AML免疫屏障中重要免疫通路和分子靶点，为突破髓系免疫屏障的CAR-T细胞临床转化提供支撑。