MODELS OF P CARINII INFECTION: SP-A AND SP-D NULL MICE

尽管在诊断、治疗和预防方面取得了进展，卡氏肺孢子虫肺炎（PCP）仍然是HIV感染患者发病和死亡的主要原因。 这种疾病是由一种神秘的病原体引起的，由于难以在体外培养这种生物体，因此对其基本生物学仍然知之甚少。 因此，动物模型仍然是研究PCP发病机制的主要手段。 虽然在对卡氏肺吸虫感染的即时反应中保护性免疫的定义方面已经取得了进展，但与这种感染的发病机制的研究相关的一个极其重要的空白仍然存在，该研究围绕着无法量化体内发病机制中的各个步骤。 表面活性蛋白A（SP-A）和表面活性蛋白D（SP-D）是在远端气道和肺泡中高度表达的胶原样凝集素（collectins）。 这两种蛋白质已被证明可以结合并介导卡氏肺孢子虫与肺泡巨噬细胞的附着，并调节T细胞群的细胞因子分泌。 SP-A和SP-D基因敲除小鼠的最新发展已经开始暗示这些蛋白在局部肺宿主防御和调节肺部炎症反应中的重要作用。我们假设SP-A和SP-D：a）增强卡氏肺孢子虫从肺泡腔中的清除; B）调节PCP期间发生的促炎和抗炎反应之间的平衡。 我们建议利用最近开发的SP-A和SP-D基因敲除小鼠作为卡氏肺孢子虫感染的新模型，以确定凝集素在宿主防御PCP中的作用。 具体目标是：1）利用SP-A和SP-D基因敲除小鼠，研究肺凝集素（SP-A，SP-D）在体内卡氏肺孢子虫感染的建立和清除中的作用; 2）研究SP-A和SP-D基因敲除小鼠对卡氏肺孢子虫的免疫应答。3)表征表面活性蛋白敲除小鼠中PC肺炎发展和进展期间表面活性物质组成和功能的变化; 4）确定SP-A和/或SP-D的外源性替代对卡氏肺孢子虫感染清除的影响。 该项目将联合收割机结合几个已建立的主题研究项目的要素，产生一个全面的调查提案，包括：1）一名在表面活性剂生物学所有主要方面拥有专业知识的首席研究员2）被公认为PCP免疫功能低下小鼠模型和表面活性剂蛋白基因敲除小鼠的权威的顾问。 这些研究结果将扩大我们对卡氏肺孢子虫感染发病机制的认识。

Despite advances in diagnosis, therapy, and prophylaxis, Pneumocystis carinii pneumonia (PCP) remains a leading cause of morbidity and mortality in patients with HIV infection. The disease is caused by an enigmatic pathogen whose basic biology remains poorly understood because of difficulty in culturing the organism in vitro. Thus, animal models remain a mainstay of investigation into the pathogenesis of PCP. Although progress has been made in the definition of protective immunity in the immediate response to P carinii infection, an extremely important gap remains related to studies of the pathogenesis of this infection which centers around an inability to quantify various steps in pathogenesis in vivo. Surfactant protein A (SP-A) and surfactant protein D (SP-D) are collagen like lectins (collectins) which are highly expressed in the distal airways and alveolus. Both proteins have been shown to bind to and mediate the attachment of P carinii to the alveolar macrophage and to modulate cytokine elaboration by T-cell populations. Recent development of both SP-A and SP-D knockout mice has begun to implicate important roles for these proteins in local lung host defense and in modulation of the pulmonary inflammatory response. We hypothesize that SP-A and SP-D: a) Augment clearance of P. carinii from the alveolar space; b) Moderate a balance between pro- and anti-inflammatory responses which occurs during PCP. We propose to utilize the recently developed SP-A and SP-D knockout mice as new models of P. carinii infection to define the role of the collectins in host defense against PCP. The specific aims are: 1) Using SP-A and SP-D knockout mice, determine the role of the lung collectins (SP-A, SP-D) in the establishment and clearance of P. carinii infection in vivo; 2) Characterize the host immune response to P. carinii in SP-A and SP-D deficient models.; 3) Characterize changes in surfactant composition and function during development and progression of PC pneumonia in surfactant protein knockout mice; 4) Determine the effect of exogenous replacement of SP-A and/or SP-D on the clearance of P. carinii infection. The project will combine elements of several established thematic research programs to yield a comprehensive investigative proposal including: 1) A Principal Investigator with expertise in all major aspects of surfactant biology 2) Consultants recognized as authorities on immunocompromised mouse models of PCP and in generation of surfactant protein knockout mice. Results from these studies will extend our understanding of the pathogenesis of P. carinii infection.