CCSP IN INNATE DEFENSE AGAINST LUNG VIRAL INFECTION

本应用旨在确定Clara细胞分泌蛋白(CCSP)在体内调节宿主对病毒感染的反应中的作用。肺部持续暴露在可吸入的病原体中；然而，对于健康的人来说，它仍然非常不受感染。CCSP是肺气道液中含量丰富的蛋白质，可能具有抗炎作用。因此，CCSP可能是肺固有免疫系统的重要组成部分。吸烟者和ARDS患者肺中CCSP减少，提示CCSP在调节宿主炎症反应中起作用。病毒感染是人类，特别是儿童肺部疾病的主要原因。为了直接确定CCSP在体内的作用，建立了缺失CCSP的基因靶向小鼠(CCSP-/-)。这些小鼠正常存活，没有明显的异常。然而，最近的实验表明CCSP-/-小鼠对肺腺病毒感染易感。腺病毒感染后的CCSP-/-小鼠在病毒诱导的炎症过程中早期炎性细胞的渗透增加。浸润性炎症细胞主要由中性粒细胞组成。在腺病毒感染后，CCSP-/-小鼠的肺部细胞因子和趋化因子的产生也增加，与炎症细胞向肺内的渗透相一致。这些结果表明，CCSP在体内改变了宿主对肺腺病毒感染的反应，可能是肺内天然防御的重要机制。目前的应用验证了CCSP通过调节肺吞噬细胞功能来调节宿主反应并在感染期间增强病毒清除的假设。为了确定CCSP在病毒先天防御中的作用，实验将确定CCSP在腺病毒感染后是否改变体内吞噬细胞的激活和功能。将评估腺病毒感染后CCSP-/-小鼠肺内病毒的摄取和杀伤情况，以确定CCSP在病毒清除中的作用。对CCSP-/-小鼠给予重组CCSP(RCCSP)的时间研究将确定CCSP在病毒诱导的肺部炎症的启动和消退中的作用。CCSP-/-小鼠将通过CCSP转基因小鼠的发育恢复CCSP的表达，并随后培育成CCSP-/-小鼠模型，以评估CCSP表达在改变宿主对肺部病毒感染的防御中的空间关系。这项应用将确定CCSP对肺部病毒感染提供先天免疫的作用和机制。这些数据可能有助于设计病毒性肺炎的治疗和预防。

The present application seeks to determine the role of Clara cell secretory protein (CCSP) in modulating host responses to viral infection in vivo. The lung is continually exposed to inhaled pathogens; yet, in healthy individuals, it remains remarkably free from infection. CCSP is an abundant protein of the lung airway fluid, and may have anti- inflammatory properties. Thus, CCSP may constitute an important component of the innate immune system of the lung. CCSP is decreased in the lungs of smokers and patients with ARDS, suggesting a role for CCSP in the modulation of host inflammatory responses. Viral infection is a major cause of lung disease in humans, especially children. To directly determine the role of CCSP in vivo, gene-targeted mice lacking CCSP (CCSP -/-) were generated. These mice survive normally, with no apparent abnormalities. However, recent experiments demonstrate that CCSP -/- mice are susceptible to pulmonary adenoviral infection. CCSP - /-mice following adenoviral infection have increased infiltration of inflammatory cells early during the course of viral-induced inflammation. The infiltrating inflammatory cells consist predominantly of neutrophils. Cytokine and chemokine production is also increased in the lungs of CCSP -/- mice following adenoviral infection, coinciding with the infiltration of inflammatory cells into the lung. These results suggest that CCSP alters the host response to pulmonary adenoviral infection in vivo and may constitute an important mechanism of innate defense in the lung. The present application tests the hypothesis that CCSP modulates host responses through the regulation of lung phagocyte function and augments viral clearance during infection. To determine the role of CCSP in viral innate defense, experiments will determine if CCSP alters phagocyte activation and function in vivo following adenoviral infection. Viral uptake and killing will be assessed in the lungs of CCSP -/- mice following adenoviral infection to determine the role of CCSP in viral clearance. Temporal studies of recombinant CCSP (rCCSP) administration to CCSP -/- mice will determine the role of CCSP in modulating the initiation and resolution of viral-induced lung inflammation. CCSP expression will be restored in CCSP -/- mice through the development of CCSP transgenic mice, and subsequently bred into the CCSP -/- mouse model to assess the spatial relationship of CCSP expression in altering host defense to lung viral infection. This application will determine the role and delineate mechanisms by which CCSP provides innate immunity to viral infection in the lung. Such data may be useful in designing treatment and prevention of viral pneumonia.