A novel mechanism of immunosuppression in sepsis: Depletion of monocytes and macrophages

脓毒症免疫抑制的新机制：单核细胞和巨噬细胞的耗竭

基本信息

批准号：
10020416
负责人：
ZHENYU Li
金额：
$ 37.73万
依托单位：
UNIVERSITY OF KENTUCKY
依托单位国家：
美国
项目类别：
财政年份：
2019
资助国家：
美国
起止时间：
2019-09-20 至 2023-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10020416
关键词：
Affect Apoptosis B-Lymphocytes Bacteria Binding CASP1 gene Caspase Cell Death Cell membrane Cells Cessation of life Cleaved cell Clinical Research Data Dendritic Cells Disease Disseminated Intravascular Coagulation Effector Cell Escherichia coli Family member Flagellin Goals Gram-Negative Bacteria Gram-Negative Bacterial Infections Immune Immune response Immunosuppression Impairment In Vitro Infection Inflammasome Inflammatory Lead Life Modeling Molecular Morbidity - disease rate Mus N-terminal Pathogenesis Pathway interactions Patients Peripheral Phagocytosis Play Proteins Reporting Research Project Grants Rod Role Rupture Sepsis T-Cell Depletion Testing Thromboplastin Tissues Type III Secretion System Pathway United States Work acyl-CoA dehydrogenase cecal ligation puncture driving force insight intravenous injection macrophage monocyte mortality mouse model new therapeutic target novel pathogen release factor response septic patients

项目摘要

Sepsis is a life-threatening condition that affects more than 1 million patients a year in the United States. Growing evidence indicates that immunosuppression is a major driving force for mortality in sepsis. Macrophages play essential roles in immune response to pathogens. Previous clinical studies have shown that peripheral monocytes are depleted in septic patients through apoptosis. Recent in vitro studies revealed that bacterial components, flagellin, the rod protein of the type III secretion system (T3SS), or LPS induce pyroptosis of macrophages through activation of inflammasome pathways. In this proposal, we provide convincing evidence that both peripheral monocytes and tissue macrophages are depleted due to pyroptosis in mouse sepsis models including the cecal ligation and puncture (CLP) model. We show that intravenous injection of flagellin or the rod proteins induced depletion of peripheral monocytes and macrophages in tissues. We further demonstrate that depletion of these cells in mice impaired immune response and increased mortality rate by subsequent challenged with E. coli. Importantly, our data indicate that tissue factor released from pyroptotic monocytes and macrophages triggers disseminated intravascular coagulation (DIC). Thus, our findings identified monocyte/macrophage depletion as a novel mechanism of immunosuppression and DIC in sepsis. The goal of this application is to delineate the underlying mechanisms of monocyte/macrophage depletion and its contribution to immunosuppression in sepsis. Aim 1 is to delineate the mechanisms of pyroptotic monocyte and macrophage death during sepsis. The working hypothesis is that inflammasome activation and subsequent pyroptosis play a critical role in monocyte/macrophage depletion during sepsis. Mouse models deficient in caspase-1, caspase-11, caspase-1/11 double, or GSDMD (whole-body and macrophage-specific) will be used to elucidate the detailed mechanism of inflammasome activation and pyroptosis in monocyte/macrophage depletion. Aim 2 is to identify the mechanism by which rod protein and flagellin induce pyroptosis leading to monocyte/macrophage depletion. We recently identified an intracellular binding partner of EprJ, the acyl-CoA dehydrogenase family member type 9 (ACAD9) in macrophages. We will use different approaches to test the hypothesis that the ACAD9-dependent pathway contributes to macrophage depletion. Aim 3 is to identify the contribution of monocyte/macrophage depletion to immunosuppression during sepsis. We will use a combination of sepsis models to investigate the role of monocyte/macrophage depletion in immunosuppression during sepsis. Peripheral monocyte depletion in septic patients will also be investigated. Completion of the proposed studies will reveal a novel molecular mechanism of immunosuppression induced by Gram-negative bacteria. Such findings will significantly advance our understanding about the pathogenesis of sepsis and identify new drug targets for this deadly disease.

败血症是一种危及生命的疾病，在美国每年影响超过 100 万患者。越来越多的证据表明，免疫抑制是败血症死亡率的主要驱动力。巨噬细胞在病原体的免疫反应中发挥重要作用。先前的临床研究表明脓毒症患者的外周单核细胞通过细胞凋亡而耗尽。最近的体外研究表明细菌成分、鞭毛蛋白、III 型分泌系统的杆蛋白 (T3SS) 或 LPS 诱导通过激活炎症小体途径导致巨噬细胞焦亡。在本提案中，我们提供令人信服的证据表明，外周单核细胞和组织巨噬细胞均因细胞焦亡而耗尽小鼠脓毒症模型，包括盲肠结扎穿刺（CLP）模型。我们证明静脉注射注射鞭毛蛋白或杆蛋白诱导组织中外周单核细胞和巨噬细胞的消耗。我们进一步证明，小鼠中这些细胞的耗竭会损害免疫反应并增加随后用大肠杆菌攻击的死亡率。重要的是，我们的数据表明组织因子释放焦亡单核细胞和巨噬细胞引发弥散性血管内凝血 (DIC)。因此，我们的研究结果表明单核细胞/巨噬细胞耗竭是免疫抑制和 DIC 的一种新机制败血症。该应用的目标是描述单核细胞/巨噬细胞的潜在机制耗竭及其对脓毒症免疫抑制的贡献。目标 1 是描述机制脓毒症期间单核细胞焦亡和巨噬细胞死亡。工作假设是炎症小体激活和随后的细胞焦亡在脓毒症期间的单核细胞/巨噬细胞耗竭中起着关键作用。 caspase-1、caspase-11、caspase-1/11 double 或 GSDMD 缺陷的小鼠模型（全身和巨噬细胞特异性）将用于阐明炎症小体激活的详细机制和单核细胞/巨噬细胞耗竭中的焦亡。目标 2 是确定杆状蛋白和鞭毛蛋白诱导细胞焦亡，导致单核细胞/巨噬细胞耗竭。我们最近发现了一种细胞内 EprJ 的结合伴侣，EprJ 是巨噬细胞中酰基辅酶 A 脱氢酶家族成员 9 型 (ACAD9)。我们将使用不同的方法来检验 ACAD9 依赖性途径有助于的假设巨噬细胞耗竭。目标 3 是确定单核细胞/巨噬细胞耗竭对脓毒症期间的免疫抑制。我们将使用脓毒症模型的组合来研究脓毒症期间免疫抑制中的单核细胞/巨噬细胞耗竭。脓毒症中的外周单核细胞耗竭患者也将接受调查。完成拟议的研究将揭示一种新的分子机制革兰氏阴性菌引起的免疫抑制。这些发现将极大地推进我们的了解脓毒症的发病机制并确定这种致命疾病的新药物靶点。