Mechanisms of immune evasion by a neuroinvasive fungal pathogen

神经侵袭性真菌病原体的免疫逃避机制

• 批准号: 10533346
• 负责人: Michael Joseph Boucher
• 金额: $ 4.92万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-01-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10533346
• 关键词: Acquired Immunodeficiency Syndrome; Address; Antifungal Agents; Aspergillus fumigatus; Bone Marrow; Candida albicans; Cell Wall; Central Nervous System; Cessation of life; Classification; Code; Complex; Cryptococcus; Cryptococcus neoformans; Cryptococcus neoformans infection; Defect; Diagnostic; Disease; Environment; Fellowship; Foundations; Fungal Genes; Fungal Meningitis; Genes; Immune; Immune Evasion; Immunocompromised Host; In Vitro; Individual; Infection; Inflammatory; Knock-out; Knowledge; Libraries; Literature; Lung; Lung infections; Macrophage; Maintenance; Meningitis; Modeling; Molecular; Mus; Natural Immunity; Pathogenesis; Pathway interactions; Pattern; Pattern recognition receptor; Phenotype; Physiological; Process; Proteins; Research; Research Training; Role; Signal Transduction; Specific qualifier value; TNF gene; Testing; Training; Virulence; Virulence Factors; Wild Type Mouse; Work; Yeasts; attenuation; beta-Glucans; capsule; cytokine; dectin 1; design; feasibility research; fitness; functional genomics; fungus; genomic tools; improved; in vivo; mortality; mutant; neglect; novel; pathogen; pathogenic fungus; programs; receptor; response; sensor; tool; treatment strategy

Project Summary Cryptococcus neoformans is a neuroinvasive yeast that causes fatal meningitis in immunocompromised individuals, resulting in >180,000 annual deaths representing 15% of global AIDS-related mortality. Cryptococci initiate infection in the lungs, where they must overcome host innate immunity to establish a replicative niche and disseminate to the central nervous system. Dectin-1 is a critical pattern recognition receptor (PRR) that initiates antifungal defenses in response to β-glucans, a pathogen-associated molecular pattern (PAMP) ubiquitous in fungal cell walls. While Dectin-1 is essential for defense against important pathogens such as Candida albicans and Aspergillus fumigatus, this receptor fails induce protective responses during C. neoformans infection, despite the presence of β-glucans in the cryptococcal cell wall. This suggests that cryptococci employ yet-undiscovered mechanisms to evade Dectin-1 sensing. The objective of this proposal is to define these mechanisms. To accomplish this, I will test the central hypothesis that C. neoformans evades Dectin-1 sensing using virulence factors that shield PAMPs and/or suppress host inflammatory signaling. Specifically, I aim to 1) identify fungal genes necessary for Dectin-1 evasion and 2) determine the relative contributions of PAMP shielding and inflammatory suppression to this process. Preliminary work in the Madhani lab has produced a library of >4000 well-validated, single-gene C. neoformans deletion strains, and I have developed a robust sequencing-based workflow to quantify these mutants in complex pools. Leveraging these tools, I will systematically identify fungal virulence factors required for Dectin-1 evasion using an in vivo murine pulmonary infection model and an in vitro macrophage stimulation model. To then define mechanisms of Dectin- 1 evasion, I will profile Dectin-1 evasion mutants for diverse phenotypes diagnostic of roles in either PAMP shielding or inflammatory suppression. This will classify novel evasion factors as acting through one or both of these mechanisms, thereby revealing the extent to which PAMP shielding and inflammatory suppression influence Dectin-1 evasion. Thus, by identifying the factors that subvert a key antifungal sensing pathway and defining the mechanisms through which this pathway is neutralized, this work addresses an important knowledge gap in cryptococcal pathogenesis and will provide a foundational understanding for how invasive fungi overcome innate defenses.

项目摘要 新型隐球菌是一种神经侵入性酵母菌，可在免疫功能低下的患者中引起致命性脑膜炎。 每年有超过180，000人死亡，占全球艾滋病相关死亡率的15%。隐球菌 在肺部引发感染，在那里它们必须克服宿主的先天免疫以建立复制生态位 并扩散到中枢神经系统。Dectin-1是一种重要的模式识别受体（PRR）， 针对β-葡聚糖启动抗真菌防御，这是一种病原体相关分子模式（PAMP） 普遍存在于真菌细胞壁中。虽然Dectin-1对于防御重要的病原体如 白念珠菌和烟曲霉感染时，该受体不能诱导保护性反应。 尽管隐球菌细胞壁中存在β-葡聚糖，但它仍然是新型球菌感染的一个重要原因。这表明 隐球菌采用尚未发现的机制来逃避Dectin-1传感。本提案的目的是 来定义这些机制。为了实现这一点，我将测试的中心假设，C。新生儿逃避 使用保护PAMP和/或抑制宿主炎症信号传导的毒力因子的Dectin-1感测。 具体来说，我的目标是1）确定真菌基因所必需的Dectin-1逃避和2）确定相对的 PAMP屏蔽和炎症抑制对该过程的贡献。Madhani的初步工作 实验室已经产生了一个超过4000个经过充分验证的单基因C。新型人缺失株，我有 开发了一个强大的基于测序的工作流程来量化复杂池中的这些突变体。利用这些 工具，我将系统地确定真菌毒力因子所需的Dectin-1逃避使用体内鼠 肺部感染模型和体外巨噬细胞刺激模型。然后定义Dectin的机制- 1逃避，我将分析Dectin-1逃避突变体的不同表型，诊断在PAMP中的作用， 屏蔽或炎症抑制。这将把新的逃避因素归类为通过以下一种或两种方式起作用： 这些机制，从而揭示PAMP屏蔽和炎症抑制的程度， 影响Dectin-1规避。因此，通过确定破坏关键抗真菌传感途径的因素， 通过定义这一途径被中和的机制，这项工作解决了一个重要的知识 在隐球菌发病机制的差距，并将提供一个基本的了解如何侵入性真菌克服 天生的防御