Mechanistic Study of Stroke-induced Immune Suppression and Identification of Immune Modulatory Targets for Stroke-associated Pneumonia

中风引起的免疫抑制机制研究及中风相关肺炎免疫调节靶点的鉴定

• 批准号: 10025933
• 负责人: EDWIN CHI KEUNG WAN
• 金额: $ 26.53万
• 依托单位: WEST VIRGINIA UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-08 至 2025-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10025933
• 关键词: Acute; Adoptive Transfer; Alveolar Macrophages; Animal Model; Anti-Bacterial Agents; Antibiotic Therapy; B-Lymphocytes; Bacterial Antibiotic Resistance; Bacterial Infections; Brain; Brain Ischemia; CCL2 gene; CCL22 gene; Cell Separation; Cell physiology; Cells; Centers of Research Excellence; Chemotactic Factors; Clinical; Congenic Strain; Coupled; Data; Dendritic Cells; Event; Goals; Gold; Host Defense; ITGAM gene; Immune; Immunity; Immunosuppression; Impairment; Incidence; Infection; Infiltration; Inflammatory; Innate Immune Response; Ischemic Stroke; Kinetics; Label; Lung; Lung infections; Lymphocyte; Lymphocyte Count; Mediator of activation protein; Middle Cerebral Artery Occlusion; Molecular; Mouse Strains; Multi-site clinical study; Mus; Natural Immunity; Natural Killer Cells; Organ; Outcome; Outcome Study; PTPRC gene; Pathway interactions; Patients; Peripheral; Phagocytes; Phase; Pneumonia; Predisposition; Pseudomonas aeruginosa; Pseudomonas aeruginosa infection; Pulmonary Pathology; RANTES; Reporter; Research; Role; Severities; Site; Stroke; T-Lymphocyte; Testing; Transgenic Organisms; Universities; Urinary tract infection; Virus; West Virginia; acquired immunodeficiency; antigen-specific T cells; bactericide; cell type; chemokine; congenic; cytokine; functional disability; improved; ineffective therapies; macrophage; monocyte; mortality; mouse model; neutralizing antibody; neutrophil; new therapeutic target; novel therapeutics; post stroke; prophylactic; recruit; small molecule inhibitor; stroke event; stroke patient; stroke therapy; time use; trafficking

Project Summary/Abstract Stroke-associated pneumonia (SAP) is the major cause of mortality in patients who have suffered from acute ischemic stroke. Multi-center clinical studies suggested that prophylactic antibiotic treatments do not reduce the incidence of mortality or SAP. Moreover, the emergence of antibiotic resistant bacteria renders the “gold standard” antibiotic treatments ineffective. Therefore, novel therapeutic strategies are needed to improve clinical outcomes. Studies utilizing animal models of focal brain ischemia demonstrated that stroke-induced immune suppression is one of the causes of SAP. The overall goal of this proposal is to understand the cause of stroke-induced immune suppression and identify novel therapeutic targets for SAP. Innate immune cells including neutrophils, monocytes, macrophages, and dendritic cells (DCs) are the first line of lung immune defense, which is followed by subsequent recruitment and activation of the antigen-specific T and B cells. In phase one of the Stroke CoBRE, we used transient middle cerebral artery occlusion (tMCAO), a mouse model of focal brain ischemia, to analyze immune cell niches in the brain and the lungs, as well as determined the expression of inflammatory cytokines and chemokines in the lungs after ischemic stroke induction. Our preliminarily data demonstrate that 1) ischemic stroke increases the number of alveolar macrophages, CD11b+ DCs, and neutrophils in the lungs, but monocyte number remains unchanged despite an increased expression of monocyte chemoattractant CCL2; 2) monocyte number is significantly increased in the brain after ischemic stroke induction; 3) ischemic stroke decreases the number of T cells, B cells, and NK cells in the lungs, correlating with the reduction of chemokines CCL5 and CCL22. These observations suggest that ischemic stroke events alter the immune cell niches in the lungs and potentially impair their functions. Using tMCAO coupled with P. aeruginosa infection, we propose to further test our hypothesis that SAP is caused by the impairment of the lung-specific, anti-bacterial innate immunity. Our hypothesis will be tested in three aims. In Aim 1, we will determine the phagocytic and bactericidal activities of innate immune cells in the lungs following tMCAO and P. aeruginosa infection. In Aim 2, we will test our hypothesis that monocyte infiltration to the brain after ischemic stroke impedes their infiltrating to the lungs, and thereby contributes to SAP. We will test this hypothesis by adoptive transfer of purified monocytes from B6 CD45.2 mice to the B6 CD45.1 congenic strain recipient mice, followed by tMCAO and P. aeruginosa infection. In Aim 3, we will investigate the protective role of CCL5 and CCL22 in SAP by determining if intratracheal administration of these chemokines restores lymphocyte availability and reduces severity of SAP. We are hopeful that this research will identify key immune cell types, molecular pathways, and downstream mediators that are critical for the host defense against lung infections following ischemic stroke, and ultimately improve clinical outcomes.

项目概要/摘要 中风相关性肺炎（SAP）是急性脑卒中患者死亡的主要原因 缺血性中风。多中心临床研究表明预防性抗生素治疗不会减少 死亡率或 SAP 的发生率。此外，抗药性细菌的出现使得“黄金” 标准“抗生素治疗无效。因此，需要新的治疗策略来改善 临床结果。利用局灶性脑缺血动物模型进行的研究表明，中风引起的 免疫抑制是SAP的病因之一。该提案的总体目标是了解原因 中风引起的免疫抑制并确定 SAP 的新治疗靶点。先天免疫细胞 包括中性粒细胞、单核细胞、巨噬细胞和树突状细胞（DC），是肺免疫的第一线 防御，随后招募并激活抗原特异性 T 细胞和 B 细胞。在 中风 CoBRE 的第一阶段，我们使用了短暂性大脑中动脉闭塞 (tMCAO)，这是一种小鼠模型 局灶性脑缺血，分析大脑和肺部的免疫细胞生态位，并确定 缺血性中风诱导后肺部炎症细胞因子和趋化因子的表达。我们的 初步数据表明 1) 缺血性中风增加肺泡巨噬细胞 CD11b+ 的数量 肺中的 DC 和中性粒细胞，但单核细胞数量保持不变，尽管表达增加 单核细胞趋化剂CCL2； 2）缺血后脑内单核细胞数量显着增加 中风诱导； 3) 缺血性中风导致肺部 T 细胞、B 细胞和 NK 细胞数量减少， 与趋化因子 CCL5 和 CCL22 的减少相关。这些观察结果表明缺血 中风事件会改变肺部的免疫细胞生态位，并可能损害其功能。 使用 tMCAO 与铜绿假单胞菌感染相结合，我们建议进一步检验我们的假设：SAP 是由肺部特异性抗细菌先天免疫受损引起的。我们的假设将在 三个目标。在目标 1 中，我们将确定先天免疫细胞的吞噬和杀菌活性。 tMCAO 和铜绿假单胞菌感染后的肺部。在目标 2 中，我们将检验我们的假设：单核细胞 缺血性中风后向大脑的浸润阻碍了向肺部的浸润，从而有助于 树液。我们将通过将纯化的单核细胞从 B6 CD45.2 小鼠过继转移至 B6 来检验这一假设。 CD45.1同源品系受体小鼠，随后进行tMCAO和铜绿假单胞菌感染。在目标 3 中，我们将 通过确定是否气管内施用 CCL5 和 CCL22 在 SAP 中的保护作用 这些趋化因子可恢复淋巴细胞的可用性并降低 SAP 的严重程度。我们希望这 研究将确定关键的免疫细胞类型、分子途径和下游介质 用于宿主防御缺血性中风后的肺部感染，并最终改善临床结果。