Determining the Injury-Associated Microbial Nutrients that Facilitate Secondary Bacterial Infection in Acutely Injured Lungs

项目总结 继发性肺炎经常发生在急性肺损伤的患者中，并增加了 急性肺损伤。虽然急性肺损伤是由各种肺部和全身损伤引起的，但所有 急性肺损伤的病因导致血-气屏障的完整性受损，允许蛋白质- 肺部空隙内有丰富的血清来源的液体。因此，内部的微环境受到了严重的伤害 肺部从根本上改变了健康状况，并为肺炎的发展提供了选择性优势- 相关的病原体。然而，使细菌在急性损伤的肺中生长的因素尚不清楚。 本研究的目的是确定损伤肺中的哪些可溶性因子可以提高小鼠的存活率。 与肺炎相关的细菌作为细菌的营养物质。使用建议的研究计划，我们将测试 中心性假说认为血清衍生的水肿流入受损的肺微环境 增加肺炎可吸收和代谢的底物的多样性和数量- 联合细菌，促进细菌在受损的肺微环境中的生长和健康。我们 我将通过以下具体目标来验证这一假说：(1)确定细菌的营养吸收系统 和代谢途径，为受伤肺中的肺炎相关细菌提供健康优势 微环境，以及(2)决定细菌营养底物的多样性和数量 可在受损的肺部微环境中促进细菌生长。为了实现这些特定的目标， 我们将使用铜绿假单胞菌和金黄色葡萄球菌，这是两种最常见的肺炎- 相关病原体、氧致肺损伤小鼠模型和一种新的体外培养方法 比较健康肺和受损肺细菌生长和基因表达差异的系统 微环境。为了补充小鼠建模和体外细菌培养，我们将进行有针对性的 代谢物分析，以检测宿主衍生的营养物质的存在，这些营养物质支持受损肺中的细菌生长。 我们将使用细菌敲除、竞争性共培养和体外营养调节实验来验证 我们的发现。这项研究将确定特定的、与伤害相关的营养物质，这些营养物质直接促进细菌在 急性肺损伤和建立营养可利用性对呼吸系统疾病进展的影响 在急性肺损伤的背景下，生物失调导致继发性细菌感染。此外，这项研究的结果 将为急性肺损伤患者的临床干预措施的发展提供机制基础 患肺炎的风险。成功完成拟议的研究和培训计划将使贝克女士能够 培养与沟通和领导力有关的专业技能和独特的跨学科专业知识 肺部病理生物学、细菌发病机制和生物信息学。这个F31奖项对她来说是必不可少的 持续的专业和科学发展，将为她的职业生涯的下一步做好准备 成为肺部宿主-微生物群相互作用领域的独立学术研究员。

PROJECT SUMMARY Secondary pneumonia occurs frequently in patients with acutely injured lungs and increases the mortality of acute lung injury. Although acute lung injury is caused by a variety of pulmonary and systemic insults, all etiologies of acute lung injury result in compromised integrity of the blood-air barrier, allowing an influx of protein- rich, serum-derived fluid in the pulmonary airspace. Consequently, the microenvironment within acutely injured lungs is radically altered from health and provides a selective advantage to the outgrowth of pneumonia- associated pathogens. However, the factors that enable bacterial growth in acutely injured lungs are unknown. The objective of this study is to determine which soluble factors in the injured lung enhance the survival of pneumonia-associated bacteria by serving as bacterial nutrients. Using the proposed research plan, we will test the central hypothesis that the influx of serum-derived edema into the injured lung microenvironment increases the diversity and quantity of substrates which can be taken up and metabolized by pneumonia- associated bacteria, enhancing bacterial growth and fitness in the injured lung microenvironment. We will test this hypothesis through the following specific aims: (1) determine the bacterial nutrient uptake systems and metabolic pathways that provide fitness advantages for pneumonia-associated bacteria in the injured lung microenvironment, and (2) determine the diversity and quantity of bacterial nutrient substrates that become available in the injured lung microenvironment and enhance bacterial growth. To accomplish these specific aims, we will employ Pseudomonas aeruginosa and Staphylococcus aureus, two of the most common pneumonia- associated pathogens, along with a murine model of oxygen-induced lung injury and a novel ex vivo culture system to compare differences in bacterial growth and gene expression between healthy and injured lung microenvironments. To complement the murine modeling and ex vivo bacterial culture, we will perform targeted metabolite analysis to detect the presence of host-derived nutrients that support bacterial growth in injured lungs. We will use bacterial knockouts, competitive co-culture, and in vitro nutrient modulation experiments to validate our findings. This study will identify specific, injury-associated nutrients that directly promote bacterial growth in acutely injured lungs and establish the influence of nutrient availability on the progression from respiratory dysbiosis to secondary bacterial infection in the context of acute lung injury. Furthermore, the results of this study will provide a mechanistic basis for the development of clinical interventions for patients with acute lung injury at risk for pneumonia. Successful completion of the proposed research and training plan will enable Ms. Baker to develop professional skills pertaining to communication and leadership and unique interdisciplinary expertise in pulmonary pathobiology, bacterial pathogenesis, and bioinformatics. This F31 award will be essential for her continued professional and scientific development and will equip her for the next step of her professional journey to become an independent academic researcher in the field of pulmonary host-microbiome interactions.