Activation of antibacterial autophagy by NADPH oxidases

Proc Natl Acad Sci U S A. 2009 Apr 14;106(15):6226-31. doi: 10.1073/pnas.0811045106. Epub 2009 Apr 1.

Abstract

Autophagy plays an important role in immunity to microbial pathogens. The autophagy system can target bacteria in phagosomes, promoting phagosome maturation and preventing pathogen escape into the cytosol. Recently, Toll-like receptor (TLR) signaling from phagosomes was found to initiate their targeting by the autophagy system, but the mechanism by which TLR signaling activates autophagy is unclear. Here we show that autophagy targeting of phagosomes is not exclusive to those containing TLR ligands. Engagement of either TLRs or the Fcgamma receptors (FcgammaRs) during phagocytosis induced recruitment of the autophagy protein LC3 to phagosomes with similar kinetics. Both receptors are known to activate the NOX2 NADPH oxidase, which plays a central role in microbial killing by phagocytes through the generation of reactive oxygen species (ROS). We found that NOX2-generated ROS are necessary for LC3 recruitment to phagosomes. Antibacterial autophagy in human epithelial cells, which do not express NOX2, was also dependent on ROS generation. These data reveal a coupling of oxidative and nonoxidative killing activities of the NOX2 NADPH oxidase in phagocytes through autophagy. Furthermore, our results suggest a general role for members of the NOX family in regulating autophagy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autophagy / immunology*
  • Cell Line
  • Epithelial Cells / cytology
  • Epithelial Cells / enzymology
  • Epithelial Cells / immunology*
  • Epithelial Cells / microbiology*
  • Humans
  • Mice
  • NADPH Oxidases / genetics
  • NADPH Oxidases / metabolism*
  • Phagosomes / immunology
  • Reactive Oxygen Species / metabolism
  • Receptors, Antigen, T-Cell / immunology
  • Receptors, IgG / immunology
  • Salmonella typhimurium / immunology*
  • Signal Transduction / immunology

Substances

  • Reactive Oxygen Species
  • Receptors, Antigen, T-Cell
  • Receptors, IgG
  • NADPH Oxidases