CD180 and the Macrophage Response to Legionella pneumophila

描述(申请人提供)：CD180和巨噬细胞对嗜肺军团菌的反应嗜肺军团菌(LP)是一种革兰氏阴性细胞内细菌，感染人肺泡巨噬细胞，导致一种被称为军团病(LD)的肺炎疾病。CD180(RP105)是TLR家族中调节TLR2和TLR4功能的非信号成员，其在军团菌发病中的作用尚不清楚。我们假设CD180调节小鼠和人类对LP感染的易感性。我们用LP感染骨髓来源的巨噬细胞，在CD180-/-小鼠中观察到在野生型和鞭毛蛋白缺陷型LP菌株中的一系列MOI中，CD180-/-小鼠的复制显著高于C57BL/6对照。CD180-/-巨噬细胞中LP复制的增强与IL-1β、IL-6或TNF等关键天然免疫细胞因子的释放无关。利用1999年荷兰军团病暴发的病例对照研究，我们发现CD180单核苷酸多态与LD的保护性显著相关(OD 0.27-0.50)。这些多态之一与单核细胞CD180表达降低有关。在这一应用中，我们建议研究依赖CD180的宿主抵抗LP感染的体外机制。此外，我们将研究人类CD180的变种及其在调节单核细胞和巨噬细胞对LP感染的反应中的作用。我们将研究CD180功能的改变，通过人类的多态或小鼠的靶向基因缺失，是否在分子和细胞水平上改变宿主对鞭毛细胞内细菌的反应。CD180缺乏的个体提供了一个独特的机会来研究人类CD180变异在体外和体内的影响，并将与CD180-/-小鼠一起，使我们能够研究CD180在LP先天免疫反应中的作用。来自这些研究的免疫遗传模型将阐明宿主对LP和可能由其他细胞内细菌引起的疾病的易感性的机制，并最终为未来的治疗提供新的见解。 与公共卫生的相关性：尽管肺部感染继续在世界范围内造成主要的发病率和死亡率，但肺炎的治疗仍然面临严峻的挑战，包括需要更有效的疫苗和新的治疗干预措施。嗜肺军团菌是一种感染人类肺泡巨噬细胞的机会性病原体，是社区获得性肺炎的重要原因。这项建议的目的是研究一种新的病原体识别受体CD180在调节宿主对军团菌感染的抵抗力中的作用，使用鼠和人的巨噬细胞。

DESCRIPTION (provided by applicant): CD180 and the Macrophage Response to Legionella neumophila Legionella pneumophila (Lp) is a gram-negative intracellular bacterium that infects human alveolar macrophages and causes a pneumonic illness known as Legionnaire's Disease (LD). The role of CD180 (RP105), a non-signaling member of the TLR family that regulates TLR2 and TLR4 function, in Legionella pathogenesis is unknown. We hypothesized that CD180 regulates susceptibility to Lp infection in mice and humans. We infected bone-marrow derived macrophages with Lp and observed significantly greater replication in CD180-/- mice compared to C57BL/6 controls over a range of MOIs in both wildtype and flagellin-deficient Lp strains. The enhanced replication of Lp in CD180-/- macrophages was not associated with release of key innate immune cytokines, such as IL-1¿, IL-6, or TNF. Using a case-control study of individuals from a 1999 outbreak of Legionnaire's Disease in the Netherlands, we found CD180 single nucleotide polymorphisms that were significantly associated with protection from LD (OD 0.27-0.50). One of these polymorphisms was associated with decreased expression of CD180 in monocytes. In this application, we propose to examine the in vitro mechanisms underlying CD180-dependent host resistance to Lp infection in mice. In addition, we will examine human variants of CD180 and their role in regulating monocyte and macrophage responses to Lp infection. We will examine whether alteration of CD180 function, via polymorphisms in humans or targeted gene deletion in mice, changes the host response to a flagellated, intracellular bacteria at the molecular and cellular level. Individuals with CD180 deficiency provide a unique opportunity to study the in vitro and in vivo effects of human CD180 variation and, along with CD180-/- mice, will enable us to examine the role of CD180 in the innate immune response to Lp. The immunogenetic models derived from these studies will illuminate mechanisms of host susceptibility to diseases caused by Lp and possibly other intracellular bacteria and culminate in novel insights for future therapies. PUBLIC HEALTH RELEVANCE: Although pulmonary infections continue to cause major morbidity and mortality worldwide, there remain formidable challenges for treating pneumonia, including the need for more effective vaccines and novel therapeutic interventions. Legionella pneumophila, an opportunistic pathogen that infects the human alveolar macrophage, is an important cause of community-acquired pneumonia. The objective of this proposal is to examine the role of a novel pathogen recognition receptor, CD180, in regulating host resistance to Legionella infection using murine and human macrophages.