Lung innate immunity against bacterial infection

肺部抵抗细菌感染的先天免疫

• 批准号: 8856487
• 负责人: Min Wu
• 金额: $ 34.5万
• 依托单位: UNIVERSITY OF NORTH DAKOTA
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-06-01 至 2019-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8856487
• 关键词: 3-methyladenine; Accounting; Acquired Immunodeficiency Syndrome; Alveolar Macrophages; Antibiotics; Autophagocytosis; Autophagosome; Bacteria; Bacterial Adhesion; Bacterial Infections; Behavior; Biochemical; Biological; Cell physiology; Cells; Cellular biology; Centers for Disease Control and Prevention (U.S.); Data; Defense Mechanisms; Diagnostic Neoplasm Staging; Disease; Eating; Elements; Genetic; Goals; Gram-Negative Bacteria; Growth; Health; Homeostasis; Host Defense; Host Defense Mechanism; Human; Image; Immune response; Infection; Knockout Mice; Lead; Ligands; Light; Link; Lung; Lysosomes; Mediating; Medical; Microbe; Modeling; Molecular; Molecular Biology; Mus; Natural Immunity; Nosocomial Infections; Pathogenesis; Patients; Phagocytosis; Phagolysosome; Phagosomes; Physiological; Play; Pneumonia; Positioning Attribute; Process; Proteins; Pseudomonas; Pseudomonas aeruginosa; Reagent; Research Personnel; Role; Signal Transduction; Starvation; System; Techniques; Time; Toll-Like Receptor 2; Toll-like receptors; Ubiquitination; Work; base; in vivo; in vivo imaging; inhibitor/antagonist; insight; interest; luminescence; macrophage; mouse model; new therapeutic target; novel; novel strategies; novel therapeutics; pathogen; response; secondary infection; src-Family Kinases; tool; whole animal imaging

DESCRIPTION (provided by applicant): Hospital-acquired infections derived from various pathogens including P. aeruginosa (Pa) require approximately $45 billion in annual medical expenses in the U.S., according to the CDC. Despite intense interest, the function of alveolar macrophages (AM) in Pa infection remains elusive. Macroautophagy (hereafter autophagy) is a conserved homeostasis mechanism by which cellular components are sequestered to autophagosomes for degradation through ubiquitination. The autophagosome machinery may contribute to the innate immunity to enhance bacterial clearance. However, it is unknown whether autophagy impacts Pa infection. Our preliminary data revealed that Pa infection can induce autophagy, and subsequently increasing bacterial degradation. We also showed that the pleiotropic Src kinase, Lyn, interacts with toll like receptors (TLRs) to boost autophagic activity In addition, we found that Atg-7 is critical for phagosome-lysosome fusion. Importantly, starvation increases AM phagocytosis of Pa and blocking autophagy by autophagy inhibitor 3-methyladenine (3MA) decreased phagocytosis and subsequent bacterial clearance. Thus, we hypothesize that Pa-induced autophagy augments host defense by facilitating phagocytosis and bacterial degradation. Our long-term goal is to discover the key factors required for regulating host defense against Pa invasion in order to develop novel therapeutic strategies. The objective of this proposal is to examine the physiological significance of Lyn/Atg-7 modulated phagocytosis with KO mice and to delineate the underlying molecular mechanisms using biochemical and whole animal imaging approaches. Aim 1: Define the functional role of Atg-7 in Pseudomonas pulmonary infection. Our working hypothesis is that atg-7 is required for protection against Pa infection. Aim 2: Evaluate the impact of autophagy on phagocytosis in pulmonary bacterial infection utilizing a mouse model and primary mouse AM. Based on our finding that Pa infection can induce autophagy and reducing bacterial burdens in AM, our working hypothesis is that Pa-induced autophagy augments macrophage phagocytosis. Aim 3: Determine the role of TLR-2, Lyn, and Atg-7 in autophagosome formation and phagolysosome fusion in host response against bacteria. Thus, our working hypothesis is that TLR-2, Lyn, and Atg-7 are key elements for delivery of bacteria to lysosomes for degradation. These proposed studies will reveal a novel mechanism for AM to eradicate bacteria and suggest novel therapeutic targets.

描述（由申请人提供）：根据 CDC 的数据，由包括铜绿假单胞菌 (Pa) 在内的各种病原体引起的医院获得性感染在美国每年需要大约 450 亿美元的医疗费用。尽管人们对此很感兴趣，但肺泡巨噬细胞 (AM) 在 Pa 感染中的功能仍然难以捉摸。巨自噬（以下简称自噬）是一种保守的稳态机制，通过该机制，细胞成分被隔离到自噬体中，通过泛素化进行降解。自噬体机制可能有助于先天免疫，从而增强细菌清除率。然而，自噬是否影响 Pa 感染尚不清楚。我们的初步数据显示，Pa 感染可以诱导自噬，从而增加细菌降解。我们还表明，多效性 Src 激酶 Lyn 与 Toll 样受体 (TLR) 相互作用以增强自噬活性。此外，我们发现 Atg-7 对于吞噬体-溶酶体融合至关重要。重要的是，饥饿会增加 AM 对 Pa 的吞噬作用，并通过自噬抑制剂 3-甲基腺嘌呤 (3MA) 阻断自噬，从而减少吞噬作用和随后的细菌清除。因此，我们假设 Pa 诱导的自噬通过促进吞噬作用和细菌降解来增强宿主防御。我们的长期目标是发现调节宿主防御 Pa 入侵所需的关键因素，以开发新的治疗策略。本提案的目的是检查 Lyn/Atg-7 调节 KO 小鼠吞噬作用的生理意义，并使用生化和整体动物成像方法描绘潜在的分子机制。目标 1：明确 Atg-7 在假单胞菌肺部感染中的功能作用。我们的工作假设是 atg-7 是防止 Pa 感染所必需的。目标 2：利用小鼠模型和原代小鼠 AM 评估自噬对肺部细菌感染吞噬作用的影响。基于我们发现 Pa 感染可以诱导自噬并减少 AM 中的细菌负担，我们的工作假设是 Pa 诱导的自噬增强了巨噬细胞的吞噬作用。目标 3：确定 TLR-2、Lyn 和 Atg-7 在宿主针对细菌的反应中自噬体形成和吞噬溶酶体融合中的作用。因此，我们的工作假设是 TLR-2、Lyn 和 Atg-7 是将细菌递送至溶酶体进行降解的关键元件。这些拟议的研究将揭示 AM 根除细菌的新机制，并提出新的治疗靶点。