Bacterial-driven immune suppression in the lung

项目摘要 急性呼吸道感染时的肺部炎症导致显著的发病率和死亡率， 微生物清除后。除了糖皮质激素外，肺部炎症的治疗选择有限 强调需要替代治疗策略。这项工作的长期目标是告知 开发肺部疾病的新治疗方法。该提案重点关注细菌如何 免疫抑制性细胞因子白细胞介素（IL）-10的刺激影响肺内稳态。近几 研究中，我们确定了一种新的途径，细菌诱导的免疫抑制在全身感染。我们 发现食源性细菌病原体单核细胞增生李斯特菌（Lm）激活IL-10的产生， 自然杀伤（NK）细胞，限制宿主对感染的保护。虽然NK细胞有助于清除 病毒和肿瘤，它们反而抑制对某些细菌感染的抵抗力。在初步研究中 我们发现NK细胞依赖性IL-10降低了对呼吸道机会性病原体的保护作用， 肺炎链球菌（Spn）。我们的数据表明，Spn诱导肺中NK细胞产生IL-10， 并且在不存在NK细胞或IL-10的情况下细菌负荷降低。对于这个提议，我将决定 细菌诱导的NK细胞IL-10如何影响肺免疫。我的中心假设是NK细胞IL-10限制了 细菌清除，但可以预防肺部炎症。首先，我检查了Spn诱导的NK细胞是否 IL-10增加肺中的Spn持续性。接下来，我研究了IL-10信号对离散肺的影响。 细胞类型及其对宿主抗Spn的保护作用（目的1）。这些实验将推动我们的 了解肺部细菌介导的免疫功能障碍的细胞靶点。肺 环境特别容易受到炎症的损害，而细菌感染的后果 IL-10对亚致死性Spn感染肺免疫病理学刺激尚不清楚。在第二个目标 在这个建议中，我将首先确定NK细胞IL-10对SPN期间肺功能和病理的影响 感染IL-10对细菌清除与肺部炎症的离散效应难以分开。 为了解决这个问题，我将在没有细菌感染的情况下，通过滴注细菌刺激剂来激活NK细胞IL-10。 蛋白质直接进入肺部。我们对Lm的研究发现，一个单一的毒力蛋白p60就足以 激活NK细胞IL-10，并且在初步数据中，我们表明滴注p60刺激NK细胞IL-10 在肺部生产。我们还发现Spn表达一种与p60同源的毒力蛋白， 体外激活肺NK细胞产生IL-10。我提出的研究用这些细菌蛋白质来询问 在没有感染的情况下，NK细胞IL-10对肺部炎症的影响，以及对 二次细菌挑战（目标2）。总之，这些研究将有助于新的见解，如何 呼吸道细菌影响肺内稳态。

PROJECT SUMMARY Lung inflammation during acute respiratory tract infection contributes to significant morbidity and mortality even after microbial clearance. The limited therapeutic options for lung inflammation beyond glucocorticoids highlights the need for alternative treatment strategies. The long-term goal of this work is to inform the development of novel therapeutic approaches for pulmonary disease. This proposal focuses on how bacterial stimulation of the immune-suppressive cytokine interleukin(IL)-10 influences lung homeostasis. In recent studies we identified a novel pathway for bacterial-induced immune suppression during systemic infection. We found that the foodborne bacterial pathogen Listeria monocytogenes (Lm) activates IL-10 production from natural killer (NK) cells, limiting host protection against infection. While NK cells contribute to clearance of viruses and tumors, they instead suppress resistance against some bacterial infections. In preliminary studies we found that NK cell-dependent IL-10 reduces protection against the respiratory tract opportunistic pathogen Streptococcus pneumoniae (Spn). Our data indicate that Spn induces IL-10 production by NK cells in the lung, and bacterial burdens are reduced in the absence of either NK cells or IL-10. For this proposal, I will determine how bacterial-induced NK cell IL-10 impacts lung immunity. My central hypothesis is that NK cell IL-10 limits bacterial clearance but is protective against lung inflammation. First, I examine whether Spn-induced NK cell IL-10 increases Spn persistence in the lung. Next, I investigate the impact of IL-10 signaling on discrete lung cell types and their contribution to host protection against Spn (Aim 1). These experiments will advance our understanding of the cellular targets of bacterial-mediated immune dysfunction in the lung. The lung environment is particularly susceptible to damage from inflammation, and the consequences of bacterial stimulation of IL-10 on lung immunopathology for sub-lethal Spn infection are not clear. In the second Aim of this proposal, I will first determine the impact of NK cell IL-10 on lung function and pathology during Spn infection. The discrete effects of IL-10 on bacterial clearance versus lung inflammation are difficult to separate. To address this, I will activate NK cell IL-10 in the absence of bacterial infection by instillation of bacterial proteins directly into the lung. Our studies with Lm found that a single virulence protein, p60, is sufficient to activate NK cell IL-10, and in preliminary data we show that instillation of p60 stimulates NK cell IL-10 production in the lung. We also found that Spn expresses a virulence protein with homology to p60 that activates lung NK cell IL-10 production in vitro. My proposed studies use these bacterial proteins to interrogate the impact of NK cell IL-10 on lung inflammation in the absence of infection, as well as susceptibility to secondary bacterial challenge (Aim 2). Together, these studies will contribute new insights into how respiratory tract bacteria influence pulmonary homeostasis.