Models of P Carinii Infection: SP-A and SP-D Null Mice

描述(申请人提供)：尽管在诊断、高效抗逆转录病毒治疗和预防方案方面取得了进展，但卡氏肺孢子虫肺炎(PCP)仍然是艾滋病毒感染患者发病和死亡的重要原因，也是其他免疫功能受损患者的一种重要的危及生命的机会性感染。肺孢子虫进入肺远端可引起适应性免疫系统(细胞免疫系统和体液免疫系统)和先天免疫系统的参与，通过特异性炎症级联反应启动CD4/CD8淋巴细胞反应，产生致炎细胞因子，募集单个核细胞，激活巨噬细胞，产生一氧化氮及其中间产物。从肺灌洗液中分离出的两种蛋白，表面活性蛋白(SP)-A和SP-D，属于胶原样凝集素家族成员，是局部非抗体介导的天然免疫反应的元件。在之前的资助期间，该项目描述了PCP对免疫低下的PCP小鼠模型中集合素表达的影响和机制。在SP-A和SP-D基因缺失的小鼠中，PCP与机体负荷增加和肺损伤有关。在先前结果的基础上，本提案的总体主题是使用其他新的集合素表达小鼠模型和体外系统来确定这些局部固有宿主防御分子、肺孢子虫、固有和适应性效应细胞以及远端肺上皮之间的相互作用。具体地说，我们建议：1)利用结构性过表达和可诱导的小鼠模型，确定肺集合素(SP-A、SP-D)在清除肺孢子虫感染和调控炎症相关肺损伤中的作用；2)在这些集合素表达的小鼠模型中，定义免疫重建条件下导致肺孢子虫感染的炎症相关表面活性物质功能障碍和肺损伤的细胞群和促成肺损伤的机制；3)表征集合素对肺孢子虫感染的关键效应细胞反应的直接影响；4)从机械上定义集合素和一氧化氮代谢在调节PCP肺损伤中的关系。这些研究的结果对于加强我们对PCP发病机制的了解具有重要意义，因为有流行病学研究将集合素基因多态性与肺部疾病联系起来，以及最近有报道称PCP患者在治疗后免疫重建治疗后发生急性呼吸衰竭。

DESCRIPTION (provided by applicant): Despite advances in diagnosis, highly active antiretroviral therapy, and prophylactic regimens, Pneumocystis carinii pneumonia (PCP) remains a significant cause of morbidity and mortality in HIV infected patients, as well as an important life-threatening opportunistic infection in other immunocompromised patients. Pneumocystis entry into the distal lung triggers involvement of both adaptive (cellular and humoral) and innate immune systems with specific inflammatory cascades characterized by initiation of CD4/CD8 lymphocyte responses, production of proinflammatory cytokines, recruitment of mononuclear cells, macrophage activation, and elaboration of nitric oxide and its intermediates. Two proteins isolated from lung lavage, surfactant protein (SP) -A and SP-D, members of the collectin (collagen-like lectin) family are elements of the local non-antibody mediated innate immune response. In the previous funding period, this project characterized the effects of and mechanisms by which PCP affected collectin expression in an immunocompromised mouse model of PCP. In both SP-A and SP-D null mice, PCP was associated with increased organism burden and lung injury. Building upon the previous results, the overall theme of the current proposal is to use additional novel murine models of collectin expression and in vitro systems to define the interplay between these local innate host defense molecules, Pneumocystis, innate and adaptive effector cells, and the distal pulmonary epithelia. Specifically we propose to: 1) Define the role of lung collectins (SP-A, SP-D) in clearance of Pneumocystis infection and modulation of inflammation-associated pulmonary injury using constitutively overexpressing and inducible mouse models; 2) Define cell populations and mechanisms contributing to inflammation associated surfactant dysfunction and lung injury in PCP under conditions of immune reconstitution in these murine models of collectin expression; 3) Characterize the direct effects of collectins on key effector cell responses in PCP; 4) Mechanistically define the relationship between the collectins and nitric oxide metabolism in modulating lung damage in PCP. Results from these studies are significant to enhancing our understanding of PCP pathogenesis in light of epidemiological studies linking collectin genetic polymorphisms with lung disease and recent reports of patients developing acute respiratory failure following immune reconstitution therapy after treatment for PCP.