GM-CSF-Induced Metal Sequestration and Histoplasma

描述（由申请方提供）：双形真菌，荚膜组织胞浆菌（Hc），是美国中西部和东南部的地方病，是真菌呼吸道感染的最常见原因。该生物体在巨噬细胞的细胞内环境中繁殖并建立潜伏状态。使用多学科的方法，包括金属蛋白质组学，免疫生物学和生物信息学，我们的研究已经确定了一种新的活性的细胞因子粒细胞巨噬细胞集落刺激因子（GM-CSF）。暴露于GM-CSF的人和鼠巨噬细胞急剧限制锌，但不是铁或铜，细胞内HC的可及性。在小鼠巨噬细胞中，锌的脱钙与一个锌进口者和两个锌出口者的显著和选择性上调相关。此外，小鼠巨噬细胞积累细胞内锌，但它们通过储存在金属硫蛋白中来拒绝真菌。我们已经收集了大量的机械数据表明，限制获得锌是一个主要手段，其中GM-CSF激活停止细胞内生长的HC。这一新发现使我们假设锌限制是GM-CSF对巨噬细胞施加的重要宿主抗性机制。为此，我们提出了三个具体目标。第一个目的是确定人类巨噬细胞中改变宿主细胞和Hc中锌含量的信号通路和锌转运蛋白。目的是确定人巨噬细胞如何对GM-CSF作出反应，包括转运蛋白和储存分子的改变。目的2利用目的1和我们的初步数据中收集的数据来研究已鉴定的锌转运蛋白和储存分子在剥夺HC中这种微量金属的功能重要性。目的3将研究IL-4如何抵消GM-CSF的作用，促进HC中锌含量的增加。该应用程序利用跨学科的团队在抗菌效应研究和吞噬细胞生物学方面开辟了一个有趣的前景。

DESCRIPTION (provided by applicant): The dimorphic fungus, Histoplasma capsulatum (Hc), is endemic to the Midwestern and southeastern United States and is the most frequent cause of fungal respiratory infections. The organism thrives within the intracellular environment of macrophages and establishes a latent state. Using a multidisciplinary approach including metalloproteomics, immunobiology, and bioinformatics, our studies have identified a novel activity of the cytokine granulocyte macrophage colony-stimulating factor (GM-CSF). Exposure of human and murine macrophages to GM-CSF sharply limits zinc, but not iron or copper, accessibility to intracellular Hc. Deprivation of zinc is associated with a marked and selective upregulation in a zinc importer and two zinc exporters in murine macrophages. Moreover, murine macrophages amass intracellular zinc but they deny it to the fungus by storage in metallothioneins. We have gathered substantial mechanistic data to indicate that limiting access to zinc is a principal means by which GM-CSF activation halts intracellular growth of Hc. This new finding has led us to hypothesize that zinc limitation is a crucial host resistance mechanism exerted by GM-CSF on macrophages. Herein, we propose 3 specific aims. The first aim is to identify the signaling pathways and zinc transporters in human macrophages that alter zinc content in host cells and in Hc. The intent is to determine how human macrophages respond to GM-CSF including alteration of transporters and storage molecules. Aim 2 harnesses data gathered in aim 1 and in our preliminary data to investigate the functional importance of the identified zinc transporters and storage molecules in depriving Hc of this trace metal. Aim 3 will examine how IL-4, which counteracts the effect of GM-CSF, promotes increases in zinc content in Hc. This application utilizes an interdisciplinary team to open an intriguing vista in antimicrobial effector research and phagocyte biology.