Non-oxidative Resistance to A. fumigatus by Alveolar Macrophages

肺泡巨噬细胞对烟曲霉的非氧化抗性

• 批准号: 7449490
• 负责人: JAMES B BURRITT
• 金额: $ 18.63万
• 依托单位: UNIVERSITY OF WISCONSIN STOUT
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-05-27 至 2011-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7449490
• 关键词: Address; Alveolar Macrophages; Animals; Antifungal Agents; Aspergillosis; Aspergillus fumigatus; Bioprobe; Breathing; Cause of Death; Cells; Conflict (Psychology); Data; Development; Environment; Event; Gene Expression; Generations; Germination; Goals; Harvest; Host Defense; Human; Immune; Immunity; Immunocompromised Host; In Vitro; Individual; Infection; Inflammatory Response; Life; Lung; Mediating; Medical; Methods; Molecular; Mouse Strains; Mus; NADPH Oxidase; Natural Immunity; Nutrient; Organism; Oxidants; Oxidases; Patients; Phagocytes; Phagocytosis; Phagolysosome; Process; Production; Protein Kinase C; Reporting; Reproduction spores; Research; Resistance; Respiratory Burst; Risk; Role; Superoxides; System; Testing; Time; Up-Regulation; Work; Zymosan; deprivation; design; fungus; in vivo; killings; microbicide; mouse model; neutrophil; particle; pathogen; public health relevance; response; therapeutic target

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.

描述（由申请人提供）：烟曲霉引起的感染是免疫受损个体死亡的主要原因。烟曲霉对那些缺乏功能性 NADPH 氧化酶系统（吞噬免疫细胞的防御性氧化剂生成系统）的人也构成威胁。肺泡巨噬细胞 (AM) 是已知在针对烟曲霉分生孢子的早期先天防御中发挥重要作用的吞噬细胞，并且据报道可产生氧化剂来杀死参与的病原体。然而，关于 AM 杀死烟曲霉的分子机制的许多细节尚不清楚。由于关于 AM 的抗真菌机制以及 NADPH 氧化酶在此过程中的作用的数据相互矛盾，我们建议更好地定义 AM 防止烟曲霉感染的杀菌机制。正在研究的总体假设是，AM 衍生的对烟曲霉分生孢子的抗性是由 NADPH 氧化酶独立的杀菌机制介导的，该机制涉及营养物封存，导致分生孢子被杀死。为实现这一目标提出的三个目标是：1) 使用体外和体内分析来比较正常小鼠和缺乏功能性吞噬细胞氧化酶的 gp91phox-/- 小鼠的 AM 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 的呼吸爆发对于抵抗曲霉病是必要的，正如我们已经证明的那样，它在中性粒细胞中是必需的。这些信息将有助于更好地了解 NADPH 氧化酶如何应用于曲霉病免疫。 2)比较正常C57Bl/6和gp91phox-/-小鼠中AM释放的NADPH氧化酶依赖性超氧化物，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，当由氧化剂触发兴奋剂或真菌颗粒的吞噬作用触发时，正常小鼠和 gp91phox-/- 小鼠的 AM 中氧化剂的产生没有显着差异。该信息将有助于更好地了解 AM 产生氧化剂的能力，以及 3) 比较正常 C57Bl/6 小鼠暴露于 AM 的分生孢子与低营养条件下分生孢子的转录反应。该目的将测试养分封存是否是 AM 的分生孢子机制。如果 AM 不利用氧化杀死分生孢子，则应通过内化分生孢子的转录反应来建议使用烟曲霉分生孢子作为 AM 分生孢子环境的生物探针。这些信息将有助于更好地了解 AM 杀死烟曲霉分生孢子的抗真菌机制。这些方法的长期目标是确定潜在的治疗靶点，以增强自然免疫力，防止烟曲霉感染。 公共卫生相关性：烟曲霉是一种吸入性真菌，如果免疫抑制，可以感染多种类型的人类患者。目前，尽管采取了积极的医疗管理措施，大多数被这种生物体感染的人仍无法生存。这项工作的长期目标是确定使肺泡巨噬细胞能够杀死烟曲霉孢子样分生孢子形式的分子机制，从而增强高危人群的自然免疫力。