Non-oxidative Resistance to A. fumigatus by Alveolar Macrophages

描述（由申请方提供）：烟曲霉菌引起的感染是免疫受损个体死亡的主要原因。A.烟曲霉对那些缺乏功能性NADPH氧化酶系统的人也是一种威胁，NADPH氧化酶系统是吞噬免疫细胞的防御性氧化剂生成系统。肺泡巨噬细胞（Alveolar macrophages，AM）是一种吞噬细胞，在机体对A.烟曲霉分生孢子，并已报道产生氧化剂以杀死接合的病原体。然而，关于AM杀死A.烟曲霉还没有被很好地理解。由于关于AM的抗真菌机制和NADPH氧化酶在此过程中的作用的相互矛盾的数据，我们提出更好地定义AM的抗A.烟熏。研究的总体假设是AM来源的对A.烟曲霉分生孢子是由NADPH氧化酶非依赖性杀微生物机制介导的，该机制涉及营养物螯合，导致分生孢子杀死。提出了三个目的来解决这个目标是：1）使用体外和体内分析来比较来自正常小鼠和缺乏功能性吞噬细胞氧化酶的gp 91 phox-/-小鼠的AM的杀分生孢子活性。关于AM的NADPH氧化酶在保护人类免受IPA侵害方面的作用的报道是相互矛盾的，我们的数据并不表明AM中的呼吸爆发对于抵抗曲霉病是必要的，因为我们已经表明它在中性粒细胞中是必要的。这一信息将提供一个更好的了解NADPH氧化酶是如何应用于曲霉免疫。2)比较正常C57 B1/6和gp 91 phox-/-小鼠AM的NADPH氧化酶依赖性超氧化物释放，以描述这些小鼠品系中AM产生氧化剂的能力。我们的初步数据表明，从正常和gp 91 phox-/-小鼠的AM中的氧化剂生产是没有显着不同时，触发氧化剂触发兴奋剂，或真菌颗粒的吞噬作用。该信息将提供对AM产生氧化剂的能力的更好理解，和3）比较暴露于来自正常C57 B1/6小鼠的AM的分生孢子与经受低营养条件的分生孢子中的那些分生孢子的转录响应。这一目的将测试是否营养螯合是AM的杀分生孢子的机制。如果AM不能利用氧化杀死分生孢子，那么使用A.烟曲霉分生孢子作为AM杀分生孢子环境的生物探针应该通过内化分生孢子的转录反应来建议。这些信息将有助于更好地了解AM的抗真菌机制。烟曲霉分生孢子这些方法的长期目标是确定潜在的治疗靶点，以增强保护免受A.烟熏。 公共卫生相关性：烟曲霉菌是一种吸入性真菌，如果免疫抑制，可感染各种类型的人类患者。在这个时候，大多数被这种微生物感染的个体无法存活，尽管积极的医疗管理。这项工作的长期目标是确定使肺泡巨噬细胞能够杀死孢子样分生孢子形式的A。烟曲霉，这样自然免疫力可以在那些处于危险之中。

DESCRIPTION (provided by applicant): Infections caused by Aspergillus fumigatus are a leading cause of death in immune compromised individuals. A. fumigatus is also a threat to those lacking a functional NADPH oxidase system, a defensive oxidant-generating system of phagocytic immune cells. Alveolar macrophages (AM) are phagocytes known to be important in the early innate defense against A. fumigatus conidia, and have been reported to produce oxidants to kill engaged pathogens. However, many details about the molecular mechanisms by which AM kill A. fumigatus are not well understood. With conflicting data about the antifungal mechanisms of AM, and the role of NADPH oxidase in this process, we proposed to better define the microbicidal mechanism of AM that protects from infections by A. fumigatus. The overall hypothesis being investigated is that the AM-derived resistance to A. fumigatus conidia is mediated by NADPH oxidase-independent microbicidal mechanisms that involve nutrient sequestration, leading to conidial killing. Three aims proposed to address this goal are: 1) to compare the conidiacidal activity of AM from normal and gp91phox-/- mice that lack a functional phagocyte oxidase, using both in vitro and in vivo analyses. Reports on the role of NADPH oxidase of AM in protecting humans from IPA are conflicting, and our data do not indicate the respiratory burst in AM is necessary for a resistance to aspergillosis, as we have shown it is in neutrophils. This information will provide a better understanding of how the NADPH oxidase is applied in aspergillosis immunity. 2) to compare NADPH oxidase-dependent superoxide liberation by AM from normal C57Bl/6 and gp91phox-/- mice to describe the capabilities of oxidant production of AM in these mouse strains. Our preliminary data suggest that oxidant production in AM from normal and gp91phox-/- mice is not significantly different when triggered by oxidant-triggering stimulants, or by phagocytosis of fungal particles. This information will provide a better understanding of the capacity of oxidant generation by AM, and 3) to compare transcriptional responses of conidia exposed to AM from normal C57Bl/6 mice, to those in conidia subjected to low nutrient conditions. This aim will test whether nutrient sequestration is a conidiacidal mechanism of AM. If oxidative killing of conidia is not utilized by AM, then the use of A. fumigatus conidia as a bioprobe of the conidiacidal environment of the AM should be suggested by transcriptional responses of internalized conidia. This information will provide a better understanding of the antifungal mechanism of AM that kills A. fumigatus conidia. The long-term goal of these approaches is to identify potential therapeutic targets to augment the natural immunity that protects from infections by A. fumigatus. PUBLIC HEALTH RELEVANCE: Aspergillus fumigatus is an inhaled fungus that can infect human patients with various types if immune suppression. At this time, most individuals that become infected by this organism do not survive, despite aggressive medical management. The long- term goal of this work is to identify molecular mechanisms that enable alveolar macrophages to kill the spore-like conidial form of A. fumigatus, so that natural immunity can be augmented in those at risk.