Wnt/β-catenin信号通路诱导脓毒症调节性树突状细胞异常分化作用与机制研究

Immunosuppression plays the most important role in the pathogenesis of sepsis. Our recent studies have confirmed that regulatory dendritic cells (regDCs) abnormal differentiation is the key to immunosuppression in sepsis, but the regulating mechanism is still unclear. The latest research has shown that Wnt/β-catenin signal pathway has an important role in regulating regDCs differentiation to decide the immune response or immune tolerance. Our preliminary experiments have shown that high expression of spleen Wnt5a ligand in sepsis model inhibited NF-κB activation and promoted bone marrow-derived immature DCs differentiating to regDCs, which caused immune suppression. We hypothesized that Wnt/β-catenin signal pathway activation related closely to regDCs differentiation, and this may be a new mechanism of regDCs abnormal differentiation in sepsis, but there are still no related studies on it. On the basis of preliminary studies, this project plans to explore the molecular mechanism of Wnt/β-catenin signal pathway regulating regDCs abnormal differentiation in vivo and in vitro in sepsis using cell biology and molecular immunology techniques and methods, and try to reverse sepsis immunosuppression by experimental blocking Wnt/β-catenin signal pathway. This project will provide theoretical and experimental base for further elucidating the immunological mechanism of sepsis, and develop new orientation directing the study on prevention and cure of sepsis，and it is prospective to acquire effective target for immunological regulation and treatment.

免疫抑制是脓毒症发病机制的中心环节，申请者前期研究证实调节性树突状细胞（regDCs）异常分化是免疫抑制的重要原因，但其调控机制不明。最新研究表明Wnt/β-catenin信号通路对regDCs的增殖分化具有明确的调控作用，决定机体免疫应答与耐受间平衡。我们预实验发现脓毒症模型脾脏高表达Wnt5a配体，抑制NF-κB活化，促进骨髓源性未成熟DCs向regDCs分化，导致机体免疫功能低下。我们推测Wnt/β-catenin通路激活与regDCs分化密切相关，可能是脓毒症regDCs异常分化的一种新机制，目前国内外未见相关研究。本项目拟运用细胞生物学与分子免疫学技术，探讨Wnt/β-catenin通路调控脓毒症regDCs异常分化的分子机制，并试图通过实验性阻断该通路逆转脓毒症的免疫抑制状态，为深入阐明脓毒症免疫紊乱机制提供理论依据，为脓毒症防治开拓新的方向，有望获得脓毒症免疫治疗的有效靶点。

免疫抑制是脓毒症发病机制中的重要原因，树突状细胞（DCs）分化及功能异常与脓毒症免疫抑制密切相关。本项目利用组织病理学、分子生物学及细胞免疫学等技术，通过动物模型体内及细胞学体外研究表明，Wnt/β-catenin信号通路影响调节性树突状细胞（regDCs）的异常分化，促进抑制性T细胞和调节性T细胞（Tregs）增殖分化，发挥负性免疫调控作用，导致免疫功能抑制，这是脓毒症出现器官损伤及功能障碍的重要原因；利用β-catenin基因敲除小鼠动物模型研究表明，抑制Wnt/β-catenin信号通路可以减轻脓毒症过度炎症及免疫抑制的程度，可以减轻脓毒症的器官损伤和降低实验动物死亡率；本项目还探讨了微小RNA-146a（miR-146a）负性调控自然杀伤（NK）细胞免疫应答功能的作用及机制，为miR-146a参与脓毒症免疫紊乱的调节机制研究提供依据。本项目上述研究结果初步阐明了Wnt/β-catenin信号通路参与脓毒症炎症及免疫紊乱的病理学新机制，为脓毒症的诊断和治疗开辟了新的途径。