Mechanisms of host protection against pathogen-associated proteases in acute lung injury

急性肺损伤中宿主针对病原体相关蛋白酶的保护机制

• 批准号: 10478014
• 负责人: Janet Sojung Lee
• 金额: $ 56.81万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10478014
• 关键词: Acute Lung Injury; Acute Respiratory Distress Syndrome; Admission activity; Alpha Granule; Alveolar; Bacteria; Bacterial Infections; Bacterial Pneumonia; Biology; Blood Platelets; Blood capillaries; Cathepsins; Cell Survival; Cells; Clinical; Critical Care; Data; Elastases; Environment; Epithelial Cells; Exhibits; Extracellular Matrix; Goals; Host Defense; Human; Infection; Inflammation; Inflammatory; Inflammatory Response; Injury; Integration Host Factors; Knockout Mice; Leukocyte Elastase; Lower respiratory tract structure; Lung; Lung infections; Mediating; Metalloproteases; Modeling; Molecular; Morbidity - disease rate; Mus; Mutation; N-terminal; Neutrophil Activation; Outcome; Pathogenicity; Pathway interactions; Patients; Peptide Hydrolases; Platelet Activation; Positioning Attribute; Predisposition; Production; Property; Proteins; Proteolysis; Proteolytic Processing; Pseudomonas; Pseudomonas aeruginosa; Pseudomonas aeruginosa infection; Publishing; Pulmonary Inflammation; RNA Interference; Reporter; Respiratory Failure; Respiratory Tract Infections; Role; Serine Protease; Site; Source; Structure of parenchyma of lung; System; Thrombospondin 1; Translating; Type II Secretion System Pathway; Virulence; Virus; Work; antimicrobial drug; base; conditional knockout; cytokine; extracellular; fungus; improved; in vivo; indexing; inhibitor; intravital microscopy; lung injury; mortality; neutralizing antibody; neutrophil; pathogen; rational design; repaired; resilience; respiratory; response; targeted treatment; tissue injury

Project Summary/Abstract: The broad, long term objective is to identify host-protective mechanisms that counter pathogen-initiated lung inflammation and injury. Many pathogens secrete proteases to cause direct damage to the lung, but bacteria, fungi and viruses can also co-opt host proteases to increase pathogenicity and promote lung injury. We have studied Pseudomonas aeruginosa (PA) as a model of infection-induced injury to probe how a pathogen-encoded protease called Pseudomonas elastase LasB, a metalloprotease released into the extracellular milieu by the PA type II secretion system, induces lung tissue damage and secondary trigger of host-derived serine proteases such as neutrophil elastase (NE). We previously identified thrombospondin-1 (TSP-1), a matricellular protein secreted by a variety of cells following injury that disarms both pathogen-encoded LasB and host protease NE, to limit lung injury and inflammation. Key questions that have arisen from this work is how an unregulated proteolytic environment drives excessive inflammatory response and dysregulated repair following injury, and what are the host factors that calibrate this response in the lung. Our preliminary findings suggest that a feed-forward neutrophilic inflammatory response occurs in the proteolytic environment of PA infection through N-terminal processing of IL-36γ that is exaggerated in the absence of TSP-1. Moreover, platelet TSP-1 appears protective against PA-induced lung injury, but the precise mechanism related to TSP-1's role at the alveolar-capillary interface remains unknown. Furthermore, we show that PA elastase activity in clinical strains confer excessive inflammation and injury in mice and is associated with worse clinical outcomes when compared with non-elastase producers. Based upon these findings, we propose the following aims utilizing genetically deficient mice, cell-specific conditional knockout systems, and PA clinical respiratory isolates obtained from the ICU to (1) elucidate the mechanisms by which TSP-1 counters the hyperinflammatory response mediated by proteolytic processing of the pro-inflammatory cytokine IL-36γ; (2) examine the contribution of TSP-1 and platelet TSP-1 in protection against alveolar barrier disruption and stabilization of the early provisional matrix following lung injury; (3) determine whether PA ICU respiratory isolates with elastolytic properties drive unwarranted inflammation and persistent tissue injury in the susceptible host. A better understanding of host biology during severe respiratory infection could prove useful in the rational design of targeted therapeutics against pathogen-derived proteases and deregulated host inflammation as adjuncts to current antimicrobial agents and supportive pulmonary and critical care management.

项目摘要/摘要：广泛的长期目标是确定宿主保护机制 抵抗病原体引发的肺部炎症和损伤。许多病原体会分泌蛋白酶，直接引起 对肺部造成损害，但细菌、真菌和病毒也可以选择宿主蛋白酶来增加致病性 并促进肺损伤。我们研究了铜绿假单胞菌（PA）作为感染诱导的模型 损伤以探究病原体编码的蛋白酶（称为假单胞菌弹性蛋白酶 LasB，一种金属蛋白酶）如何发挥作用 由 PA II 型分泌系统释放到细胞外环境，诱导肺组织损伤并 宿主来源的丝氨酸蛋白酶（例如中性粒细胞弹性蛋白酶（NE））的次要触发因素。我们之前确定了 血小板反应蛋白-1 (TSP-1)，一种由多种细胞在受伤后分泌的基质细胞蛋白，可解除​​武装 病原体编码的 LasB 和宿主蛋白酶 NE，以限制肺损伤和炎症。关键问题 这项工作产生的问题是不受监管的蛋白水解环境如何导致过度炎症 损伤后的反应和失调修复，以及校准这种反应的宿主因素是什么 肺。我们的初步研究结果表明，前馈中性粒细胞炎症反应发生在 PA 感染的蛋白水解环境通过 IL-36γ 的 N 末端加工来实现，IL-36γ 在 缺乏 TSP-1。此外，血小板 TSP-1 似乎可以预防 PA 引起的肺损伤，但精确的 与 TSP-1 在肺泡-毛细血管界面的作用相关的机制仍不清楚。此外，我们还展示了 临床菌株中的 PA 弹性蛋白酶活性会导致小鼠过度炎症和损伤，并且与 与非弹性蛋白酶生产者相比，临床结果更差。根据这些发现，我们 利用遗传缺陷小鼠、细胞特异性条件敲除系统提出以下目标，以及 从 ICU 获得的 PA 临床呼吸道分离株用于 (1) 阐明 TSP-1 的机制 对抗促炎细胞因子的蛋白水解过程介导的过度炎症反应 IL-36γ； (2)检查TSP-1和血小板TSP-1在保护肺泡屏障方面的贡献 肺损伤后早期临时基质的破坏和稳定； (3)判断是否PA ICU 具有弹力分解特性的呼吸道分离株会导致不必要的炎症和持续性组织损伤 易感宿主。更好地了解严重呼吸道感染期间的宿主生物学可能是有用的 合理设计针对病原体来源的蛋白酶和解除管制的宿主的靶向治疗 炎症作为当前抗菌药物的辅助手段以及支持性肺部和重症监护 管理。