Lung innate immunity against bacterial infection

肺部抵抗细菌感染的先天免疫

• 批准号: 8762972
• 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/8762972
• 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; 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; public health relevance; 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）：根据疾病预防控制中心（CDC）的数据，在包括铜绿假单胞菌（PA）在内的各种病原体的医院获得感染需要约450亿美元的年度医疗费用。尽管感兴趣，但PA感染中肺泡巨噬细胞（AM）的功能仍然难以捉摸。大量噬菌体（以下称自噬）是一种保守的体内平衡机制，通过该机制将细胞成分隔离为自噬体，以通过泛素化来降解。自噬体机械可能有助于先天免疫，以增强细菌清除率。但是，尚不清楚自噬是否影响PA感染。我们的初步数据表明，PA感染会诱导自噬，随后增加细菌降解。我们还表明，多效性SRC激酶Lyn与Toll类似受体（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PA的AM吞噬作用，并通过自噬抑制剂3-甲基趋化（3MA）抑制自噬可减少吞噬作用和随后的细菌清除率。因此，我们假设PA诱导的自噬增强宿主防御通过促进吞噬作用和细菌降解。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，以制定新的治疗策略。该提案的目的是检查Lyn/ATG-7对KO小鼠的调节吞噬作用的生理意义，并使用生化和全动物成像方法来描绘潜在的分子机制。 AIM 1：定义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。 AIM 2：使用小鼠模型和原发性小鼠AM评估自噬对肺细胞增多症对吞噬作用的影响。根据我们的发现，PA感染可以诱导AM中的自噬和减轻细菌负担，我们的工作假设是PA诱导的自噬增强了巨噬细胞吞噬作用。 AIM 3：确定TLR-2，LYN和ATG-7在自噬体形成和吞噬体融合在宿主对细菌反应中的作用。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降解的关键要素。这些提出的研究将揭示AM消除细菌并提出新型治疗靶标的新型机制。