Innate immune-mediated control of pulmonary Legionella pneumophila infection

项目摘要 细胞内细菌病原体，如嗜肺军团菌，这是导致社区和 医院获得性肺炎是世界范围内显著发病率和死亡率的原因。蔓延 广谱抗生素耐药性的细菌病原体正在升级，发现新的先天性 免疫防御机制可能是未来治疗方法的关键， 威胁细胞内病原体部署毒力因子使许多免疫细胞功能丧失。赢得这场 战斗，主机必须克服这种颠覆，通过尚未明确定义的机制。为了解决这个 在知识的关键差距，我们试图定义成功的先天免疫清除的参数， 军团菌军团菌通过其IV型分泌系统在肺泡巨噬细胞内复制， 细菌效应物，其中几种抑制宿主蛋白质合成。几种效应物抑制宿主蛋白 合成.尽管在宿主翻译中存在这种阻断，但军团菌感染却矛盾地增强了 炎性细胞因子在上一个资助期，我们证明了军团菌感染的肺泡 巨噬细胞能够合成和释放IL-1;此外，需要IL-1受体（IL-1 R）信号传导 用于通过旁观者骨髓细胞稳健地产生TNF和IL-12。有趣的是，我们最新发表的研究表明， 肺泡上皮细胞中的IL-1 R信号转导首次诱导粒细胞-巨噬细胞的产生， 集落刺激因子（GM-CSF），这是所需的旁观者细胞因子的生产和细菌 间隙有趣的是，虽然GM-CSF作为一种有效的炎性细胞因子在宿主防御广泛的炎症反应中起作用， 我们的研究结果首次表明，GM-CSF代谢重编程单核细胞 进行有氧糖酵解，从而促进细胞因子的产生。我们将检验肺泡 上皮来源的GM-CSF代谢性地重编程单核细胞，以放大表观遗传变化， TLR驱动的细胞因子产生和感染控制。在这次更新中，我们提出了三个目标，首先：定义 哪些细胞类型产生并响应GM-CSF，第二：了解GM-CSF介导的 第三：定义GM-CSF和TLR信号传导如何合作， 促进细胞因子的产生。总之，这些研究将定义新的先天免疫机制， 通过宿主克服病原体编码的毒力活动。因此，拟议的研究将提供 对宿主防御机制的重要见解，用于对抗广泛的微生物病原体 并有助于开发改进的抗微生物治疗剂和疫苗。

Project Summary Intracellular bacterial pathogens such as Legionella pneumophila, an important cause of community- and hospital-acquired pneumonia, are responsible for significant morbidity and mortality worldwide. As the spread of broad-spectrum antibiotic resistance among bacterial pathogens is escalating, discovery of novel innate immune defense mechanisms may hold the key for future therapeutic approaches to deal with this increasing threat. Intracellular pathogens deploy virulence factors to disable many immune cell functions. To win this battle, the host must overcome this subversion, through as yet poorly defined mechanisms. To address this critical gap in knowledge, we seek to define the parameters of successful innate immune clearance of Legionella. Legionella replicates within alveolar macrophages by using its type IV secretion system to deliver bacterial effectors, several of which inhibit host protein synthesis. Several effectors inhibit host protein synthesis. Despite this block in host translation, Legionella infection paradoxically enhances production of inflammatory cytokines. In the previous funding period, we demonstrated that Legionella-infected alveolar macrophages are able to synthesize and release IL-1; moreover, IL-1 receptor (IL-1R) signaling was required for robust production of TNF and IL-12 by bystander myeloid cells. Intriguingly, our newly published study show for the first time that IL-1R signaling in alveolar epithelial cells induces production of granulocyte-macrophage colony-stimulating factor (GM-CSF), which was required for bystander cytokine production and bacterial clearance. Intriguingly, while GM-CSF acts as a potent inflammatory cytokine in host defense against a broad spectrum of pathogens, our findings show for the first time that GM-CSF metabolically reprograms monocytes to undergo aerobic glycolysis, thereby promoting cytokine production. We will test the hypothesis that alveolar epithelium-derived GM-CSF metabolically reprograms monocytes to amplify epigenetic changes that enhance TLR-driven cytokine production and control of infection. In this renewal, we propose three Aims to first: define which cell types produce and respond to GM-CSF, second: understand the role of GM-CSF-mediated metabolic reprogramming in host defense, and third: define how GM-CSF and TLR signaling collaborate to promote cytokine production. Together, these studies will define novel innate immune mechanisms employed by the host to surmount pathogen-encoded virulence activities. The proposed research will therefore provide vital insight into mechanisms of host defense that are utilized against broad classes of microbial pathogens and aid development of improved anti-microbial therapeutics and vaccines.