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

• 批准号: 10436162
• 负责人: ZHENYU Li
• 金额: $ 37.88万
• 依托单位: TEXAS A&M UNIVERSITY HEALTH SCIENCE CTR
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-20 至 2024-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10436162
• 关键词: Affect; Apoptosis; B-Lymphocytes; Bacteria; Binding; CASP1 gene; Caspase; Cell Death; Cell membrane; Cells; Cessation of life; 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

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.

败血症是一种威胁生命的疾病，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。 巨噬细胞在对病原体的免疫反应中起着至关重要的作用。以前的临床研究表明 化粪池患者通过细胞凋亡耗尽周围单核细胞。最近的体外研究表明 细菌成分，鞭毛蛋白，III型分泌系统（T3SS）的棒蛋白或LPS诱导 巨噬细胞的凋亡是通过激活炎性体途径的。在此提案中，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凋亡而枯竭 小鼠败血症模型，包括盲肠连接和穿刺（CLP）模型。我们表明静脉注射 注射鞭毛蛋白或杆蛋白会诱导组织中周围单核细胞和巨噬细胞的耗竭。 我们进一步证明，这些细胞在小鼠中的耗竭会损害免疫反应并增加 随后对大肠杆菌挑战的死亡率。重要的是，我们的数据表明组织因子释放 来自凋亡的单核细胞和巨噬细胞触发了血管内凝结（DIC）。因此，我们的 发现发现单核细胞/巨噬细胞耗竭是一种新颖的免疫抑制和DIC机制 败血症。该应用的目的是描述单核细胞/巨噬细胞的基本机制 耗竭及其对败血症免疫抑制的贡献。目的1是描述 败血症期间的凋亡单核细胞和巨噬细胞死亡。工作假设是炎性体 激活和随后的凋亡在败血症期间的单核细胞/巨噬细胞耗竭中起关键作用。 缺乏caspase-1，caspase-11，caspase-1/11 double或GSDMD缺乏的鼠标模型（全身和 巨噬细胞特异性）将用于阐明炎性体激活的详细机制和 单核细胞/巨噬细胞耗竭中的凋亡。目标2是确定杆蛋白和 鞭毛蛋白诱导凋亡导致单核细胞/巨噬细胞耗尽。我们最近确定了细胞内 EPRJ的结合伴侣，巨噬细胞中的酰基-COA脱氢酶家族成员型（ACAD9）。我们将 使用不同的方法检验以下假设，即Acad9依赖性途径有助于 巨噬细胞耗尽。 AIM 3是确定单核细胞/巨噬细胞耗竭对 败血症期间的免疫抑制。我们将使用败血症模型的组合来研究 败血症期间免疫抑制中的单核细胞/巨噬细胞耗竭。化粪池中的周围单核细胞耗竭 还将研究患者。拟议研究的完成将揭示一种新型的分子机制 革兰氏阴性细菌诱导的免疫抑制。这样的发现将大大推动我们的 了解败血症的发病机理并确定这种致命疾病的新药物靶标。