GM-CSF-Induced Metal Sequestration and Histoplasma

描述（由申请人提供）：二态真菌，荚膜组织浆体（Hc），是美国中西部和东南部的地方性疾病，是真菌呼吸道感染的最常见原因。该生物在巨噬细胞的细胞内环境中繁殖并建立潜伏状态。利用多学科方法，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细胞因子粒细胞巨噬细胞集落刺激因子（GM-CSF）的新活性。人类和小鼠巨噬细胞暴露于GM-CSF会严重限制细胞内Hc对锌的可及性，但不限制铁或铜的可及性。在小鼠巨噬细胞中，锌的剥夺与一个锌输入细胞和两个锌输出细胞的显著和选择性上调有关。此外，小鼠巨噬细胞在细胞内聚集锌，但它们通过金属硫蛋白的储存将其拒绝给真菌。我们已经收集了大量的机制数据，表明限制对锌的获取是GM-CSF激活阻止Hc细胞内生长的主要手段。这一新发现使我们假设锌限制是GM-CSF对巨噬细胞施加的关键宿主抗性机制。在此，我们提出3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。目的是确定人类巨噬细胞对GM-CSF的反应，包括转运体和储存分子的改变。目的2利用目的1中收集的数据和我们的初步数据来研究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。本应用程序利用跨学科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.