MyD88介导树突状细胞影响Foxp3+Treg功能参与脓毒症发病的机制研究

Immunosuppression induced by abnormal activation of regulatory T cells (Foxp3+Treg) is the main cause of mortality in sepsis, dendritic cells (DC) are the key link of the activation of Foxp3+Treg. On this basis, the applicant further studies found that the increased MyD88 expression in sepsis could induce the recruitment of dendritic cells, but the state of immune suppression could be attenuated by blocking the expression of MyD88. We speculate that MyD88-mediated DC-induced abnormal activation of Foxp3+Treg is involved in the progression of sepsis. The aim of this study is to establish the sepsis model and to explore the effects of MyD88-mediated dendritic cells on the function of Foxp3+Treg (cell phenotype, inhibitory activity of effector T cells, cytokine secretion, apoptosis induction, etc.) and inflammatory response in combination with DC-conditional MyD88 knockout mice. Then, the effect of dendritic cells extracted from healthy bone marrow (BMDCs) on immune function and the mechanism of dendritic cells abnormal activation of Foxp3+Treg are elaborated, and further to explore the molecular mechanism. The purpose of this study is to explore the mechanism of immunosuppression in sepsis and provide theoretical basis for clinical treatment of sepsis.

Foxp3+调节性T细胞（Foxp3+Treg）功能异常活化诱发的免疫抑制是脓毒症死亡的主因，树突状细胞（DC）是诱导Foxp3+Treg活化的关键环节。在此基础上申请人进一步研究发现，脓毒症状态下DC募集增强伴随着MyD88表达升高，而下调MyD88表达可显著改善脓毒症免疫抑制，鉴于此我们推测：DC内MyD88介导的TLRs/NF-KB通路是诱导Foxp3+Treg异常活化的重要原因。本研究拟建立脓毒症模型，结合DC条件性MyD88敲除小鼠，探讨MyD88介导的DC对Foxp3+Treg功能变化（细胞表型、对效应T细胞抑制活性、细胞因子分泌、诱导凋亡等）及炎症反应的影响；继而输注健康骨髓提取的DC后对免疫功能的作用，阐述DC异常活化Foxp3+Treg的作用机制，并阐释其分子机制。本课题旨在探索脓毒症免疫抑制的发生机理，为脓毒症临床治疗提供理论依据。

Foxp3+调节性T细胞（Foxp3+Treg）功能异常活化诱发的免疫抑制是脓毒症死亡的主因，树突状细胞（DC）是诱导Foxp3+Treg活化的关键环节。在此基础上申请人进一步研究发现，脓毒症状态下DC募集增强伴随着MyD88表达升高，而下调MyD88表达可显著改善脓毒症免疫抑制，鉴于此我们推测：DC内MyD88介导的TLRs/NF-KB通路是诱导Foxp3+Treg异常活化的重要原因。本研究拟建立脓毒症模型，结合DC条件性MyD88敲除小鼠，探讨MyD88介导的DC对Foxp3+Treg功能变化（细胞表型、对效应T细胞抑制活性、细胞因子分泌、诱导凋亡等）及炎症反应的影响；继而输注健康骨髓提取的DC后对免疫功能的作用，阐述DC异常活化Foxp3+Treg的作用机制，并阐释其分子机制。课题组对脓毒症不同阶段细胞凋亡的变化规律、对病程进展及预后的影响、以及目前现阶段调控细胞凋亡对病程影响进行了系统性的研究；在后续研究中，对肺损伤中上皮组织修复机制进行了探讨。在肺损伤早期，特殊的一类细胞亚群Sox9-positive AEC2s显著增殖，且mRNA和蛋白表达升高，而AEC1s受损明显。我们通过单细胞测序进一步对Sox9-positive AEC2s的免疫微环境、富集分析及拟时序分析进行了探讨，并对信号通路进行了初步的预测，并对其作用机制及分子机制进行阐述。通过该项目的实施解读脓毒症 Foxp3+ Treg细胞活性增强的本质和分子机制，且从分子生物学角度阐释Sox9+ AEC2s细胞在化学源性肺损伤中的治疗作用及机制，为干细胞治疗临床预防和治疗脓毒症及ALI/ARDS提供理论依据和潜在的治疗靶点。