Franciscella Tularensis: Characterizing Lung Innate Immunity

描述（由申请人提供）：土拉菌弗朗西斯菌是土拉菌病的病原，是细胞内革兰氏阴性球菌。土拉菌可以在低温下在水、潮湿的土壤、干草、稻草和腐烂的动物尸体中存活数周。它的耐寒性和吸入后的潜在致命效应使这种生物成为武器的吸引力。这种细菌是吸入后发现的最具传染性的病原体之一，但人们对土拉菌是如何与人类宿主相互作用的知之甚少。缺乏关于这种高毒性生物的信息的一个原因是对BSL 3安全程序的要求，这使得相关的研究劳动密集。事实上，我们对土拉菌与常驻肺细胞，特别是肺泡上皮细胞（AEC）和人肺微血管内皮细胞（HPMEC）之间的相互作用一无所知。呼吸上皮是宿主与外界环境之间的动态接口。AEC对于维持肺内平衡和提供抵抗吸入病原体的物理屏障至关重要。AEC提供的两种诱导防御机制包括产生抗菌因子和分泌细胞因子，用于招募和激活免疫细胞。因此，我建议研究肺AEC和HPMEC如何对土拉菌毒力菌株（Schu 4）作出反应，以促进免疫细胞的迁移和激活。本提案的第二个目标将是在鼻内小鼠模型中检查AEC对土拉菌的反应，并将这些结果与Aim 1中的人类细胞研究相关联。这些研究将首次为了解土拉菌与AEC的相互作用以及响应土拉菌的人肺上皮/内皮与免疫细胞之间的细胞-细胞通讯提供重要信息。这对于深入了解兔热病的致病性至关重要，并将使我们能够确定靶向疫苗开发的新途径。

DESCRIPTION (provided by applicant): Francisella tularensis, the etiological agent of tularemia, is intracellular Gram-negative cocci. F. tularensis can survive for weeks at low temperatures in water, moist soil, hay, straw, and decaying animal carcasses. Its hardy nature and potentially lethal effects following inhalation have made this organism attractive for weaponization. This bacterium is one of the most infectious pathogens identified when inhaled, and yet very little is known about how F. tularensis interacts with its human host. One reason for the lack of information about this highly virulent organism is the requirement for BSL 3 safety procedures that makes associated research labor intensive. Virtually nothing is known about the interaction between F. tularensis and resident lung cells, specifically alveolar epithelial cells (AEC) and human pulmonary microvascular endothelial cells (HPMEC). The respiratory epithelium is a dynamic interface between the outside environment and the host. AEC are vital for maintaining lung homeostasis and providing a physical barrier against inhaled pathogens. Two inducible defense mechanisms provided by AEC include the production of antimicrobial factors and secreting cytokines for the recruitment and activation of immune cells. Therefore, I propose to examine how pulmonary AEC and HPMEC respond to a virulent strain of F. tularensis (Schu 4) to promote immune cell migration and activation. The second goal of this proposal will be to examine the response of AEC to F. tularensis in an intranasal mouse model and correlate these results with the human cell studies in Aim 1. These studies will, for the first time, provide vital information for understanding the interaction of F. tularensis and AEC and the cell-cell communication between human lung epithelium/endothelium and immune cells in response to F. tularensis. This is essential for gaining insight into the pathogenicity of tularemia, and will allow us to identify novel avenues for targeted vaccine development. F. tularensis can be used as a bioweapon against the public. Therefore, this application proposes to better understand how this organism interacts with lung cells and responses of the lung cells to F. tularensis. This funding of this proposal will provide crucial insight into the effective and ineffective innate immune responses to help find future vaccines and therapeutic development.