Antifungal Immunity and the Mechanism of Fungal Programmed Cell Death

抗真菌免疫和真菌程序性细胞死亡机制

基本信息

批准号：
10079460
负责人：
Robert Andrew Cramer
金额：
$ 65.3万
依托单位：
SLOAN-KETTERING INST CAN RESEARCH
依托单位国家：
美国
项目类别：
财政年份：
2019
资助国家：
美国
起止时间：
2019-01-22 至 2023-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10079460
关键词：
Antifungal Agents Apoptosis Apoptosis Inhibitor Apoptosis Regulation Gene Apoptotic Applications Grants Aspergillosis Aspergillus fumigatus Aspergillus nidulans BIR Domain Baculoviruses Biochemical Biochemistry Biological Models Candida albicans Candidiasis Cartoons Caspase Cell Death Cell Death Induction Cells Collaborations Complement DNA Fragmentation Data Defect Development Disease Disease Outcome Enzymes Essential Genes Etiology Eukaryota Family Fungal Genes Fungal Proteins Fungal Spores Genetic Genetic study Germination Goals Histones Host Defense Human Hyphae Immune Immunity Immunologic Surveillance Immunologics Immunology Induction of Apoptosis Inhalation Innate Immune System Knowledge Laboratories Lung Mediating Modeling Molds Myelogenous NADPH Oxidase Oxidative Stress Pathogenesis Pathway interactions Patient-Focused Outcomes Patients Phagocytes Pharmacology Pharmacology Study Physiology Play Pneumonia Post-Translational Regulation Predisposition Process Proteins Regulation Reporter Reporting Reproduction spores Research Personnel Resistance Respiratory Burst Role Stress System Tertiary Protein Structure Testing Therapeutic Tissues Virulence Visualization Work base experience fungal genetics immune checkpoint immune function improved in vivo innovation insight member new therapeutic target novel novel therapeutic intervention pathogenic fungus predictive modeling prevent respiratory response

项目摘要

PROJECT SUMMARY Humans inhale fungal conidia (i.e, vegetative spores) on a daily basis. The ability of the respiratory innate immune system to prevent germination of inhaled conidia into tissue-invasive hyphae represents a critical immunologic checkpoint. Using Aspergillus fumigatus, the most common etiologic agent of invasive aspergillosis, as a model system for human fungal pathogens, we discovered that conidia undergo programmed cell death with apoptosis-like features during interactions with innate immune cells. This finding was facilitated by a novel fluorescent reporter of fungal physiology that enables visualization and quantitation of fungal apoptosis markers, including histone degradation, caspase activation, and DNA fragmentation. Our work demonstrates that A. fumigatus conidia express an essential and druggable anti-apoptotic protein, termed Bir1, that counters host induction of apoptosis-like programmed cell death by the action of phagocyte NADPH oxidase. Genetic and pharmacologic studies demonstrate that Bir1 expression and activity underlie conidial susceptibility to host apoptosis-like programmed cell death, and in turn, host susceptibility to invasive aspergillosis. These findings indicate that mammalian fungal immune surveillance exploits a fungal apoptosis- like programmed cell death pathway to maintain barrier immunity in the lung. In this collaborative proposal with two co-investigators, we seek to determine the mechanism through which Bir1 regulates anti-apoptotic activity during fungal-host cell encounters. Our preliminary data support a model in which Bir1 exerts anti-apoptotic activity via two conserved BIR domains, underlies post-translational regulation in response to pro-apoptotic stress, regulates candidate fungal caspase-like enzymes as apoptosis effectors, and demonstrates functional conservation across human pathogenic fungi. Based on these observations, our model predicts that fungal apoptosis-like programmed cell death is a general feature of fungal-host cell encounters and central to the establishment of invasive fungal disease. We explore this model in the following aims: (1) define the functional domains and post-translational regulation of Bir1 critical for resistance to host induction of apoptosis-like programmed cell death, (2) define the mechanism of Bir1- mediated resistance to host induction of apoptosis-like programmed cell death, with an emphasis on regulation of a candidate fungal caspase-like activity, and (3) define the role of apoptosis-like programmed cell death and Bir1 homologs following Aspergillus nidulans and Candida albicans challenge. The proposed studies are significant and innovative because they identify a novel mechanism of immune surveillance and demonstrate that higher eukaryotes can exploit programmed cell death in lower eukaryotes for the purpose of sterilizing immunity. This work will provide a mechanistic understanding of Bir1 function in regulating host-fungal encounters. Knowledge gained from these studies will inform strategies that target fungal Bir1 homologs and exploit fungal apoptosis-like programmed cell death for therapeutic gain.

项目概要人类每天吸入真菌分生孢子（即营养孢子）。与生俱来的呼吸能力免疫系统防止吸入的分生孢子萌发为组织侵入性菌丝是一个关键免疫检查点。使用烟曲霉（最常见的侵袭性病原体）曲霉病作为人类真菌病原体的模型系统，我们发现分生孢子经历在与先天免疫细胞相互作用期间具有类似凋亡特征的程序性细胞死亡。这一发现一种新型的真菌生理学荧光报告基因促进了可视化和定量真菌凋亡标志物，包括组蛋白降解、半胱天冬酶激活和 DNA 片段化。我们的工作表明，烟曲霉分生孢子表达一种必需的、可药物化的抗凋亡蛋白，称为 Bir1，通过吞噬细胞的作用对抗宿主诱导的细胞凋亡样程序性细胞死亡 NADPH 氧化酶。遗传和药理学研究表明 Bir1 表达和活性是分生孢子对宿主细胞凋亡样程序性细胞死亡的易感性，反过来，宿主对侵入性的易感性曲霉病。这些发现表明哺乳动物的真菌免疫监视利用了真菌细胞凋亡- 像程序性细胞死亡途径一样维持肺部的屏障免疫。在这项与两名联合研究者的合作提案中，我们寻求确定一种机制，通过该机制 Bir1 在真菌与宿主细胞相遇期间调节抗凋亡活性。我们的初步数据支持模型其中 Bir1 通过两个保守的 BIR 结构域发挥抗凋亡活性，是翻译后调控的基础响应促凋亡应激的调节，调节候选真菌半胱天冬酶样酶作为凋亡效应器，并展示了人类病原真菌的功能保守性。基于这些根据观察，我们的模型预测真菌凋亡样程序性细胞死亡是真菌的一个普遍特征真菌与宿主细胞的相遇对于侵袭性真菌病的形成至关重要。我们探索这个模型目标如下：(1) 定义 Bir1 的功能域和翻译后调控，这对于抵抗宿主诱导的凋亡样程序性细胞死亡，（2）定义Bir1-的机制介导对宿主诱导的凋亡样程序性细胞死亡的抵抗，重点是调节候选真菌半胱天冬酶样活性的作用，以及（3）定义凋亡样程序性细胞死亡的作用和构巢曲霉和白色念珠菌攻击后的 Bir1 同源物。拟议的研究是意义重大且具有创新性，因为他们确定了一种新的免疫监视机制并证明了高等真核生物可以利用低等真核生物的程序性细胞死亡来达到绝育的目的免疫。这项工作将从机制上理解 Bir1 在调节宿主真菌中的功能遭遇。从这些研究中获得的知识将为针对真菌 Bir1 同源物和利用真菌凋亡样程序性细胞死亡来获得治疗效果。