Alveolar macrophage and mycobacteria

描述(由申请人提供)：严重的免疫抑制，如在艾滋病毒感染者中发生的，经常与并发分枝杆菌感染有关。结核分枝杆菌是一种世界性的病原体，也是正常和免疫抑制受试者发病和死亡的主要原因。非结核分枝杆菌，如禽分枝杆菌，可以是机会性感染，感染免疫抑制的个人或患有潜在疾病的受试者，如肺矽肺。无论分枝杆菌是作为病原体还是机会感染性生物，肺中的分枝杆菌首先感染肺泡巨噬细胞(AM)，肺泡巨噬细胞是肺泡腔的驻留炎症细胞。AM必须由干扰素-伽马或肿瘤坏死因子-α等细胞因子启动和激活，才能最大限度地对分枝杆菌等感染性生物产生反应。虽然AM被认为是分枝杆菌疾病发病机制的核心，但很少有研究研究AM在体内对分枝杆菌感染的响应作用。我们开发了一种新的方法，将正常和激活的AM“重建”到免疫缺陷动物的肺中。我们将使用这种新的方法来测试AM对分枝杆菌如MAC或M的反应的假设缺陷；结核病允许在免疫抑制期间最初的肺部感染和随后的传播；相反，纠正这些AM缺陷将恢复肺泡免疫，控制肺部感染和防止传播。我们将研究AM在体内对分枝杆菌感染做出反应的潜在机制，然后使用各种策略激活AM进行重建，看看肺泡宿主防御是否恢复和感染是否被根除。这也将测试由促炎细胞因子如干扰素-γ激活的肺泡巨噬细胞是否通过AM来源的肿瘤坏死因子-α介导对分枝杆菌的肺泡宿主防御。这些具体目标包括：1)确定重组到免疫缺陷小鼠肺中的正常AM恢复对分枝杆菌的肺泡宿主防御并防止传播的机制，2)确定促炎症细胞因子如干扰素-γ是否对肺泡宿主防御分枝杆菌和防止传播是必要的，3)确定体外基因治疗重组巨噬细胞是否导致体内持续过度表达促炎细胞因子如干扰素-γ，并改善肺泡宿主对分枝杆菌的防御并防止扩散，以及4)确定促炎细胞因子如干扰素-γ是否具有作用。在肺泡宿主上，对分枝杆菌的防御是由AM来源的肿瘤坏死因子-α介导的。这项提议将在体内检验其他方法不可能的假说，并将确定正常或激活的AM的重建是否足以恢复肺泡宿主对分枝杆菌疾病的防御，尽管存在持续的全身免疫抑制。

DESCRIPTION (provided by applicant): Profound immunosuppression as occurs in HIV-infected subjects is frequently associated with complicating mycobacterial infections. Mycobacterium tuberculosis is a worldwide pathogen and is a major cause of morbidity and mortality in both normal and immunosuppressed subjects. Non-tuberculous mycobacteria such as M. avium can be opportunistic infections that infect immunosuppressed individuals or subjects with underlying disorders such as pulmonary silicosis. Regardless of whether mycobacteria are acting as pathogens or opportunistic infectious organisms, mycobacteria in the lung first infect alveolar macrophages (AMs), the resident inflammatory cell of the alveolar spaces. AMs must be primed and activated by cytokines such as IFN-gamma or TNF-alpha to maximally respond to infectious organisms such as mycobacteria. Although it is recognized that AMs are central to the pathogenesis of mycobacterial disease, there are few studies that have examined the role of AMs in vivo in response to mycobacterial infection. We have developed a novel approach to "reconstitute" normal and activated AMs into the lungs of immunodeficient animals. We will use this new approach to test the hypothesis Deficiencies in the response of AMs to mycobacteria such as MAC or M. tuberculosis permit initial lung infection and subsequent dissemination during immunosuppression; conversely, correction of these AM deficiencies will restore alveolar immunity, control lung infection and prevent dissemination. We will examine the underlying mechanisms by which AMs respond in vivo to mycobacterial infection and will then use a variety of strategies to activate AMs for reconstitution to see if alveolar host defense is restored and infection eradicated. This will also test whether AMs activated by pro-inflammatory cytokines such as IFN-gamma mediate alveolar host defense to mycobacteria by AM-derived TNF-alpha. These Specific Aims include: 1) to determine the mechanisms by which normal AMs reconstituted into the lungs of immunodeficient mice restore alveolar host defense to mycobacteria and prevent dissemination, 2) to determine if proinflammatory cytokines such as IFN-gamma are essential for alveolar host defense to mycobacteria and to prevent dissemination, 3) to determine if ex vivo gene therapy to reconstituted macrophages results in persistent overexpression of pro-inflammatory cytokines such as IFN-gamma in vivo and improves alveolar host defenses to mycobacteria and prevents dissemination, and 4) to determine if the effects of pro-inflammatory cytokines such as IFN-? on alveolar host defenses to mycobacteria are mediated by AM-derived TNF-alpha. This proposal will test hypotheses in vivo not possible by other means and will determine whether reconstitution of normal or activated AMs is sufficient to restore alveolar host defense to mycobacterial disease despite the presence of ongoing systemic immunosuppression.