Mechanisms Of Impaired Macrophage Function in Lung Injury - Project 4

项目摘要/摘要：本项目的广泛、长期目标是为了更好地了解 通过检查不同的宿主-肺感染后免疫抑制的潜在机制- 病原体相互作用。严重的急性下呼吸道感染或肺炎仍然是 脓毒症和全球急性呼吸窘迫综合征(ARDS)的危险因素。然而，细菌 肺炎也是ARDS和长时间机械通气增加的常见并发症 患者发病率、住院时间和医疗费用。然而，宿主-病原体相互作用的许多方面 仍然知之甚少，以及在关键时期发生的寄主控制机制的潜在缺陷 疾病在ARDS中仍然是悬而未决的问题。我们已经开发了一种两次击中小鼠的模型，目标是 应用单核巨噬细胞系统研究猪传染性支气管炎严重肺部感染的后果 肺炎克雷伯菌是院内常见的革兰氏阴性杆菌 肺炎，以及与全身免疫抑制的潜在联系。我们发现干扰素的表达受损- 调节因子1(IRF-1)，一种对增强抗微生物和抗病毒天然免疫至关重要的转录因子， 在这个两次打击的模型中，我们提出了IRF-1的缺陷通过以下方式介导免疫抑制表型 损害对宿主防御至关重要的关键先天免疫基因的反式激活。此外，初步的 研究结果表明，一部分危重患者表现出免疫抑制表型。 以未能控制相对无毒的产碳青霉素酶肺炎克雷伯菌(Kp)为特征 Kp的体外生长和受损的血清杀伤与替代的缺陷有关，但不是经典的 补体活性。大多数补体蛋白是在肝脏合成的，但巨噬细胞/单核细胞也是如此 合成这些因子，其中许多是由干扰素调节的。总的来说，来自 2-HIT模型和患者血清使我们提出了一个主要假设，即巨噬细胞功能障碍 以IRF-1的缺陷为特征的，标志着宿主在感染期间由于 细胞因子反应、微生物杀伤和补体活性受损。目标1将决定是否 IRF-1信号的损伤是趋化因子和细胞因子反应缺陷的一种机制 两支主打的车型。目的2将评估线粒体缺陷是否会导致脱羧酶1(ACOD1) 在KP感染和二次打击模型中，IRF-1下游会损害宿主的抗微生物程序。目标3将 评估IRF-1的激活，以及合成的替代途径补体因子的动态 危重患者队列中单核吞噬细胞与AP活性的关系。成功 这些目标的完成将阐明寄主控制的新机制，并有助于实现 了解重症肺炎并发的免疫抑制信号。

Project Summary/Abstract: The broad, long-term objective of this Project is to better understand the underlying mechanisms of immunosuppression following infection in the lungs by examining distinct host- pathogen interplay. Severe acute lower respiratory tract infection or pneumonia remains a major cause of sepsis and risk factor for the acute respiratory distress syndrome (ARDS) worldwide. However, bacterial pneumonia is also a frequent complication of ARDS and prolonged mechanical ventilation that increases patient morbidity, length of stay, and health-care costs. Yet, many aspects of host-pathogen interactions remain poorly understood and the underlying defects in host control mechanisms that occur during critical illness remain outstanding questions in ARDS. We have developed a 2-hit murine model targeting the mononuclear phagocyte system of the liver to study the consequences of severe lung infection induced by Klebsiella pneumoniae, an extracellular Gram-negative pathogen that is a common cause of nosocomial pneumonia, and potential link to systemic immunosuppression. We identified impaired expression of interferon- regulatory factor 1 (IRF-1), a transcription factor critical for boosting antimicrobial and antiviral innate immunity, in this 2-hit model leading us to propose that defects in IRF-1 mediates the immunosuppressive phenotype by impairing transactivation of key innate immunity genes important for host defense. Moreover, preliminary findings suggest that a proportion of critically ill patients exhibit an immunosuppressive phenotype characterized by failure to control relatively avirulent carbapenamase-producing Klebsiella pneumoniae (KP) growth in vitro, and impaired serum killing of KP is associated with defects in alternative but not classical complement activity. Most complement proteins are synthesized in the liver, but macrophages/monocytes also synthesize these factors, many of which are regulated by interferons. Collectively, preliminary findings from the 2-hit model and patient serum have led us to propose a major hypothesis that macrophage dysfunction characterized by defects in IRF-1 marks the host for an immunosuppressive fate during infection due to impaired cytokine response, microbial killing, and complement activity. Aim 1 will determine whether impairment in IRF-1 signaling is a mechanism for defective chemokine and cytokine response in the 2-hit model. Aim 2 will evaluate whether defects in mitochondrial aconitate decarboxylase 1 (ACOD1) downstream of IRF-1 impairs host anti-microbial program during KP infection and in the 2-hit model. Aim 3 will evaluate IRF-1 activation, the dynamics of alternative pathway complement factors synthesized by mononuclear phagocytes, and relationship to AP activity in a cohort of critically ill patients. Successful completion of the aims will elucidate novel mechanisms of host control and aid in the long-term objective of understanding immunosuppressive signals complicating severe pneumonia.