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 i s 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.

Public Health Relevance

The pathogenic fungus, Histoplasma capsulatum, multiplies in macrophages and requires zinc for growth. GM-CSF activation of macrophages limits fungal growth by zinc deprivation. Our work will decipher the pathways and molecules that lead to zinc depletion and will provide new insights into phagocyte biology.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI106269-02
Application #
8660629
Study Section
Special Emphasis Panel (ZRG1-IDM-M (03))
Program Officer
Duncan, Rory A
Project Start
2013-05-15
Project End
2018-04-30
Budget Start
2014-05-01
Budget End
2015-04-30
Support Year
2
Fiscal Year
2014
Total Cost
$502,891
Indirect Cost
$181,797
Name
University of Cincinnati
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
041064767
City
Cincinnati
State
OH
Country
United States
Zip Code
45221
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Dade, Jessica; DuBois, Juwen C; Pasula, Rajamouli et al. (2016) HcZrt2, a zinc responsive gene, is indispensable for the survival of Histoplasma capsulatum in vivo. Med Mycol 54:865-75
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Fecher, Roger A; Horwath, Michael C; Friedrich, Dirk et al. (2016) Inverse Correlation between IL-10 and HIF-1α in Macrophages Infected with Histoplasma capsulatum. J Immunol 197:565-79
Hsieh, Heidi; Vignesh, Kavitha Subramanian; Deepe Jr, George S et al. (2016) Mechanistic studies of the toxicity of zinc gluconate in the olfactory neuronal cell line Odora. Toxicol In Vitro 35:24-30
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Horwath, Michael C; Fecher, Roger A; Deepe Jr, George S (2015) Histoplasma capsulatum, lung infection and immunity. Future Microbiol 10:967-75
Wüthrich, Marcel; Brandhorst, Tristan T; Sullivan, Thomas D et al. (2015) Calnexin induces expansion of antigen-specific CD4(+) T cells that confer immunity to fungal ascomycetes via conserved epitopes. Cell Host Microbe 17:452-65

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