IFNs Modify the Proteome of Legionella-Containing Vacuoles and Restrict Infection Via IRG1-Derived Itaconic Acid

PLoS Pathog. 2016 Feb 1;12(2):e1005408. doi: 10.1371/journal.ppat.1005408. eCollection 2016 Feb.

Abstract

Macrophages can be niches for bacterial pathogens or antibacterial effector cells depending on the pathogen and signals from the immune system. Here we show that type I and II IFNs are master regulators of gene expression during Legionella pneumophila infection, and activators of an alveolar macrophage-intrinsic immune response that restricts bacterial growth during pneumonia. Quantitative mass spectrometry revealed that both IFNs substantially modify Legionella-containing vacuoles, and comparative analyses reveal distinct subsets of transcriptionally and spatially IFN-regulated proteins. Immune-responsive gene (IRG)1 is induced by IFNs in mitochondria that closely associate with Legionella-containing vacuoles, and mediates production of itaconic acid. This metabolite is bactericidal against intravacuolar L. pneumophila as well as extracellular multidrug-resistant Gram-positive and -negative bacteria. Our study explores the overall role IFNs play in inducing substantial remodeling of bacterial vacuoles and in stimulating production of IRG1-derived itaconic acid which targets intravacuolar pathogens. IRG1 or its product itaconic acid might be therapeutically targetable to fight intracellular and drug-resistant bacteria.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Disease Models, Animal
  • Female
  • Gene Expression Regulation
  • Gene Ontology
  • Hydro-Lyases / genetics
  • Hydro-Lyases / immunology*
  • Hydro-Lyases / metabolism
  • Immunity, Innate
  • Interferons / immunology*
  • Interferons / metabolism
  • Legionella pneumophila / genetics
  • Legionella pneumophila / immunology*
  • Legionella pneumophila / metabolism
  • Legionnaires' Disease / immunology*
  • Legionnaires' Disease / metabolism
  • Macrophages, Alveolar / immunology*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Mitochondria / metabolism
  • Models, Immunological
  • Proteome*
  • Reactive Oxygen Species / metabolism
  • Succinates / metabolism
  • Vacuoles / metabolism
  • Vacuoles / microbiology

Substances

  • Proteome
  • Reactive Oxygen Species
  • Succinates
  • Interferons
  • Hydro-Lyases
  • Irg1 protein, mouse
  • itaconic acid