The Role of Mitochondrial Metabolism in Neutrophilic Lung Inflammation

摘要 中性粒细胞在宿主防御病原体中的基础作用在动物中得到了很好的证实。 中性粒细胞减少患者的感染模式和感染易感性增加。尽管如此，许多人 中性粒细胞生物学的各个方面仍未得到充分研究。支持抗菌药所需的代谢程序 中性粒细胞的功能以及这些细胞在疾病中可能达到的可塑性程度尚不清楚。 州政府目前还不得而知。我们已经利用独特的方法来确定增加的 患者感染风险和CPT1a基因多态性。肉碱棕榈酰转移酶1a(CPT1a)是 长链脂肪酸的线粒体代谢。使用CPT1a的药物抑制剂和多个 在细菌性肺炎的小鼠模型中，我们已经证明CPT1A抑制增加了对 通过减少中性粒细胞在感染部位的动员和激活而引起的感染。我们还提供其他服务 初步数据支持中性粒细胞线粒体代谢脂肪酸生成ATP的模型， 它是放大中性粒细胞激活、趋化和 抗菌功能。基于这些发现，我们将检验脂肪酸新陈代谢是 中性粒细胞在肺内运输和抗菌防御的基本代谢程序。具体来说，我们 将检验以下假设：(I)脂肪酸新陈代谢是线粒体ATP的重要机制 中性粒细胞的产生，(Ii)中性粒细胞的扩增需要脂肪酸衍生的线粒体ATP 激活信号，以及(Iii)脂肪酸代谢中断损害中性粒细胞的激活、趋化、 抗菌防御和中性粒细胞肺部炎症。具体目标1将定义脂肪酸的作用 中性粒细胞能量代谢、迁移和效应器功能。这项工作将确立 中性粒细胞中脂肪酸代谢对线粒体ATP产生的影响，确定脂肪酸代谢的作用 在中性粒细胞激活中的作用，并确定脂肪酸代谢对中性粒细胞抗菌作用的重要性 功能。特异靶2将确定脂肪酸代谢失活对中性粒细胞肺的影响 发炎。这项工作将使用多种单细胞方法来定义中性粒细胞的可塑性和激活 感染的肺微环境中的异质性。此外，这一目标将确定脂肪酸的影响 中性粒细胞肺部炎症的代谢抑制。完成这些目标将建立脂肪酸 氧化作为一种基本的代谢程序来支持抗菌中性粒细胞的功能，并增加 目前流行的范例认为，中性粒细胞完全依赖有氧糖酵解作为代谢程序。此外， 这些研究将确定感染部位中性粒细胞异质性的功能后果和 确定中性粒细胞的可塑性是疾病状态的潜在贡献者。最后，这些目标将提供一个 存在于人类中的CPT1A多态与临床关联的机制框架 人口数量增加和感染风险增加。

SUMMARY The fundamental role of neutrophils in host defense against pathogens is well established from animal models of infection and the increased susceptibility to infection in neutropenic patients. Despite this, many aspects of neutrophil biology remain underexplored. The metabolic programs needed to support antimicrobial neutrophil functions are poorly understood and the degree of plasticity these cells may achieve in disease states is not known. We have leveraged unique approaches to identify a novel association between increased infection risk in patients and a polymorphism in Cpt1a. Carnitine palmitoyltransferase 1a (Cpt1a) is required for mitochondrial metabolism of long chain fatty acids. Using a pharmacologic inhibitor of CPT1a and multiple murine models of bacterial pneumonia, we have demonstrated that CPT1a inhibition increased susceptibility to infection by decreasing neutrophil mobilization to, and activation at, the site of infection. We provide additional preliminary data to support a model whereby neutrophil mitochondria metabolize fatty acids to generate ATP, which is necessary for amplification of activating signals required for neutrophil activation, chemotaxis, and antibacterial functions. Based on these findings, we will test the overall hypothesis that fatty acid metabolism is an essential metabolic program for neutrophil trafficking and antibacterial defense in the lung. Specifically, we will test the sub-hypotheses that (i) fatty acid metabolism is an important mechanism for mitochondrial ATP production in neutrophils, (ii) fatty acid-derived mitochondrial ATP is required for amplification of neutrophil activating signals, and (iii) disruption of fatty acid metabolism impairs neutrophil activation, chemotaxis, antibacterial defenses, and neutrophilic lung inflammation. Specific Aim 1 will define the role of fatty acid metabolism on neutrophil energetics, migration, and effector functions. This work will establish the contribution of fatty acid metabolism to mitochondrial ATP production in neutrophils, define the role of fatty acid metabolism in neutrophil activation, and determine the importance of fatty acid metabolism for neutrophil antibacterial functions. Specific Aim 2 will determine the effect of inactivation of fatty acid metabolism on neutrophilic lung inflammation. This work will use multiple single-cell approaches to define neutrophil plasticity and activation heterogeneity in the infected lung microenvironment. Further, this Aim will determine the effects of fatty acid metabolism inhibition on neutrophilic lung inflammation. Completion of these Aims will establish fatty acid oxidation as an essential metabolic program to support antimicrobial neutrophil functions and add to the current prevailing paradigm that neutrophils rely solely on aerobic glycolysis as a metabolic program. Further, these studies will determine the functional consequences of neutrophil heterogeneity at the site of infection and establish neutrophil plasticity as a potential contributor to disease states. Finally, these aims will provide a mechanistic framework for the clinical association between a Cpt1a polymorphism existing in the human population and increased infection risk.