Immunity
Volume 39, Issue 4, 17 October 2013, Pages 697-710
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Article
Granulocyte Macrophage-Colony Stimulating Factor Induced Zn Sequestration Enhances Macrophage Superoxide and Limits Intracellular Pathogen Survival

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Highlights

  • Metallothioneins, or Zn-sequestering proteins, drive GM-CSF effector function

  • Zn sequestration augments production of reactive oxygen species via HV1

  • GM-CSF triggers Zn deprivation and enhances ROS to kill fungi in macrophages

  • GM-CSF drives Zn sequestration in vivo and in human macrophages

Summary

Macrophages possess numerous mechanisms to combat microbial invasion, including sequestration of essential nutrients, like zinc (Zn). The pleiotropic cytokine granulocyte macrophage-colony stimulating factor (GM-CSF) enhances antimicrobial defenses against intracellular pathogens such as Histoplasma capsulatum, but its mode of action remains elusive. We have found that GM-CSF-activated infected macrophages sequestered labile Zn by inducing binding to metallothioneins (MTs) in a STAT3 and STAT5 transcription-factor-dependent manner. GM-CSF upregulated expression of Zn exporters, Slc30a4 and Slc30a7; the metal was shuttled away from phagosomes and into the Golgi apparatus. This distinctive Zn sequestration strategy elevated phagosomal H+ channel function and triggered reactive oxygen species generation by NADPH oxidase. Consequently, H. capsulatum was selectively deprived of Zn, thereby halting replication and fostering fungal clearance. GM-CSF mediated Zn sequestration via MTs in vitro and in vivo in mice and in human macrophages. These findings illuminate a GM-CSF-induced Zn-sequestration network that drives phagocyte antimicrobial effector function.

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These authors contributed equally to this work