系统生物学框架下骨髓区域微环境中交感神经组织调控Th细胞免疫网络在急性髓性白血病中的作用机制研究

Immunological deregulation in bone marrow microenvironment is the main reason for refractoriness and death of patients with acute myeloid leukemia (AML). Bone marrow sympathetic nerve tissue has been proven to be vital in regulating the hematopoiesis and immunology in bone marrow microenvironment. Our previous study has confirmed the sympathetic neuropathy and imbalanced Th immunological network in bone marrow of AML patients, and they are correlated significantly. Under the framework of systems biology and using experiments, we will construct the Bayesian network of bone marrow sympathetic nerve tissue and Th subsets variation of AML and clarify the key cells and molecules. After co-culturing bone marrow nerve cells with BMDCs, CD4+ T cells or AML cells, we will investigate the bone marrow sympathetic nerve regulatory mechanism on Th immunological network, and clarify their effects on biological behavior of AML cells. We will illuminate the detailed mechanism of nerve/Th network in AML development after studying the related signaling pathway. Furthermore, we will establish AML mouse model with or without BM nerve functional deficiency and monitor the sympathetic neuropathy and Th immunological network in vivo. We will study the effects and mechanisms on reversing imbalanced Th immunological network after applying neurotransmitter and nerve protection. Our project will demonstrate the detailed mechanisms during the process from BM sympathetic nerve damage to the development of AML, and provide strategy for AML targeting therapy.

骨髓微环境免疫失衡是急性髓性白血病(AML)难治和死亡重要原因。新近证明，骨髓交感神经组织对骨髓造血和免疫功能具有重要调控作用。我们前期发现，AML骨髓中存在交感神经组织病变及辅助性T(Th)细胞免疫网络失衡，且二者显著相关。本项目拟在系统生物学框架内，采用网络分析方法，并结合实验验证，构建AML骨髓局部交感神经组织以及骨髓区域微环境Th细胞的贝叶斯网络模型，明确其关键节点；通过体外骨髓神经细胞与BMDCs、CD4+T、AML细胞共培养，研究其下游相关通路，揭示骨髓神经对Th免疫网络调控作用，及其对AML细胞生物学行为的作用及机制。构建骨髓神经功能缺失（及正常）AML小鼠，体内监测小鼠AML发生发展中神经损伤与Th免疫网络关系，应用神经递质及保护剂，观察对小鼠骨髓中Th免疫网络失衡的逆转作用，以期揭示从AML骨髓局部交感神经组织损伤到AML发生发展的内在网络机制，为AML靶向治疗提供借鉴。

AML的发生发展是遗传、环境相互作用的多因素、多步骤过程，靶向抑制白血病细胞增殖、促进凋亡、诱导分化是AML治疗的重要基础。目前，针对AML的治疗不断进展，但多数患者仍出现复发甚至死亡，探究AML发生及耐药机制具有重大临床意义。近年来，交感神经递质和NLRP3炎症小体在恶性疾病中的作用引起研究者的广泛关注，但其在AML中的作用仍不清楚。本研究证实，AML患者骨髓微环境中存在骨髓神经相关分子和神经递质的降低，明确了白血病患者骨髓局部存在神经损害，且与预后不良明显相关。同时发现，AML患者骨髓微环境中存在Th亚群免疫失衡，Th1和Th17亚群及相关细胞因子在AML患者中明显降低，而免疫抑制性亚群Treg明显升高。通过建立贝叶斯网络模型和生物信息学分析，确定了骨髓神经组织和Th亚群异常中的关键信号分子。进一步研究发现，交感神经递质肾上腺素和去甲肾上腺素可抑制AML患者骨髓中Th亚群向Th1、Th17方向分化、促进其向Treg方向分化，并发挥促进白血病细胞增殖的作用。本研究进一步探索骨髓来源的树突状细胞（BMDCs）中NLRP3炎症小体激活后调控Th亚群分化及对白血病的影响。研究发现，NLRP3炎性小体激活的BMDCs通过分泌IL-1β促进CD4+T细胞向Th1分化，而Th1通过分泌IFN-γ杀伤AML白血病细胞。另外证实，神经递质多巴胺通过DR1/5受体途径，可激活AML细胞的NLRP3炎症小体，释放效应分子IL-1β，促进白血病细胞增殖，抗IL-1β抗体靶向阻断可逆转此效应。因此，本研究发现AML患者骨髓微环境中存在着骨髓神经损害、Th亚群和NLRP3炎症小体等免疫异常并阐明其作用机制，靶向干预可为AML的治疗提供新靶点。