The Role of Lung Epithelium in B. anthracis Pathogenesis

肺上皮在炭疽杆菌发病机制中的作用

基本信息

批准号：
7942879
负责人：
YI XU
金额：
$ 21.98万
依托单位：
TEXAS A&M UNIVERSITY HEALTH SCIENCE CTR
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-06-01 至 2012-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7942879
关键词：
A Mouse Affect Anthrax disease Antibiotics Apical Bacillus (bacterium)Bacillus anthracis Bacillus anthracis spore Bacteria Biological Biological Assay Cell Line Cells Cellular Structures Clinical Data Disease Distal Environment Epithelial Cells Epithelium Equilibrium Event Future Germination Goals In Vitro Infection Investigation Knockout Mice Lead Lung Mediating Microbe Modeling Molecular Mus Organ Organism Outcome Pathogenesis Pathway interactions Play Principal Investigator Process Reagent Regimen Reproduction spores Respiratory System Respiratory physiology Role Route Side Signal Transduction Signaling Molecule Site Staging alveolar epithelium base combat extracellular improved in vitro Model in vivo killings macrophage microbial microorganism migration mouse model novel novel therapeutics pathogen prevent programs public health relevance respiratory trafficking uptake

项目摘要

DESCRIPTION (provided by applicant): We recently demonstrated that soon after Bacillus anthracis spores are delivered into mouse lungs significant quantities of these spores are found inside the lung epithelial cells. Here we hypothesize that this intracellular presence plays an important role in B. anthracis pathogenesis. Specifically, we propose a model where spores enter lung epithelial cells at the early stages of infection and they either germinate into vegetative bacilli and are translocated across the epithelial cells, or, they persist inside them as spores, i.e., intracellular germination is a prerequisite to switching on a "translocation pathway". The crucial importance of dissemination and germination in inhalational anthrax is well established. Persistence of spores in the lung has also been noted for decades. However, the mechanisms permitting persistence, germination and dissemination in vivo are poorly understood or unknown. Our hypothesis that the intracellular environment of the lung epithelial cells provides a venue for all these events is a novel concept and provides an alternative pathway to the classical model of macrophage uptake and dissemination. This is made more compelling by recent evidence that B. anthracis bacilli are susceptible to phagocytic killing by macrophages both in vitro and in vivo. Therefore, this new model has significant advantages for the bacterium in terms of survivability. Consequently results from this application will have a significant impact on understanding the pathogenic mechanisms of B. anthracis. From a broader point of view, dissemination and persistence are two important issues concerning many microbial infections. Despite the importance, much remains to be elucidated including what roles the lung epithelium can play during an infection. Therefore, this application will have broad implications to bacterial pathogenesis in general as well as enhancing our understanding of the function of the lung epithelium under microbial challenge. Our new model is further supported by the following data. B. anthracis spores are internalized by cultured epithelial cell lines and primary lung epithelial cells. B. anthracis can survive inside lung epithelial cells and can cross an in vitro model of the alveolar epithelium from the apical to the basolateral side via a transcellular route. Only germinated spores/vegetative bacilli are recovered from the basolateral side of the epithelium even under assay conditions that do not permit extracellular germination of spores, suggesting that germination occurs inside epithelial cells and is a prerequisite for exiting these cells. In this application, we propose three specific aims to determine if lung epithelial cells are a site for dissemination, persistence and germination in vivo. In future studies, we will investigate the molecular basis underlying these events and the dynamic balances between these events. PUBLIC HEALTH RELEVANCE: How Bacillus anthracis, the causative agent of anthrax, spreads in the host body and persists in the lung is not well understood. Our studies suggest that the lung epithelium may play a critical role in these processes. Investigation of this possibility will improve the current understanding of how this bacterium causes disease and may reveal new therapeutic strategies.

描述（由申请人提供）：我们最近证明，在炭疽芽孢杆菌孢子被输送到小鼠肺中后不久，在肺上皮细胞内发现了大量这些孢子。在这里，我们假设这种细胞内存在在炭疽芽孢杆菌发病机理中起重要作用。具体而言，我们提出了一个模型，其中孢子在感染的早期阶段进入肺上皮细胞，然后它们要么发芽到植物性杆菌中，并在上皮细胞中易位，或者它们持续存在为孢子，即细胞内发芽是开关“转运途径”的前提。在吸入炭疽中传播和发芽的关键重要性已经很好地确定。数十年来，肺部的孢子的持续存在已被注意到。然而，允许持续性，在体内发芽和传播的机制知之甚少或未知。我们的假设是，肺上皮细胞的细胞内环境为所有这些事件提供了一个新颖的概念，并为巨噬细胞吸收和传播的经典模型提供了替代途径。最近的证据表明，炭疽芽孢杆菌在体外和体内都易受巨噬细胞的吞噬性杀戮。因此，这种新模型在生存能力方面具有显着的优势。因此，该应用的结果将对理解炭疽芽孢杆菌的致病机制产生重大影响。从更广泛的角度来看，传播和持久性是关于许多微生物感染的两个重要问题。尽管很重要，但仍有许多尚待阐明，包括在感染期间肺上皮可以扮演的角色。因此，该应用将对一般的细菌发病机理具有广泛的影响，并增强我们在微生物挑战下对肺上皮功能的理解。以下数据进一步支持我们的新模型。 B.炭疽孢子通过培养的上皮细胞系和原发性肺上皮细胞内化。 B.炭疽病可以在肺上皮细胞内生存，并可以通过跨细胞途径从顶端到基底外侧的牙槽上皮的体外模型。即使在不允许细胞外孢子的测定条件下，也仅从上皮的基底外侧回收了发芽的孢子/营养杆菌，这表明发芽发生在上皮细胞内，并且是消除这些细胞的先决条件。在此应用中，我们提出了三个特定的目的，以确定肺上皮细胞是否是在体内传播，持久性和发芽的部位。在未来的研究中，我们将研究这些事件的基础分子基础以及这些事件之间的动态平衡。公共卫生的相关性：炭疽病的病因芽孢杆菌如何在宿主体内传播并持续存在于肺中。我们的研究表明，肺上皮可能在这些过程中起关键作用。对这种可能性的研究将提高人们对这种细菌如何引起疾病的理解，并可能揭示新的治疗策略。