Reactive oxygen species regulate caspase-11 expression and activation of the non-canonical NLRP3 inflammasome during enteric pathogen infection

PLoS Pathog. 2014 Sep 25;10(9):e1004410. doi: 10.1371/journal.ppat.1004410. eCollection 2014 Sep.

Abstract

Enteropathogenic and enterohemorrhagic bacterial infections in humans are a severe cause of morbidity and mortality. Although NOD-like receptors (NLRs) NOD2 and NLRP3 have important roles in the generation of protective immune responses to enteric pathogens, whether there is crosstalk among NLRs to regulate immune signaling is not known. Here, we show that mice and macrophages deficient in NOD2, or the downstream adaptor RIP2, have enhanced NLRP3- and caspases-11-dependent non-canonical inflammasome activation in a mouse model of enteropathogenic Citrobacter rodentium infection. Mechanistically, NOD2 and RIP2 regulate reactive oxygen species (ROS) production. Increased ROS in Rip2-deficient macrophages subsequently enhances c-Jun N-terminal kinase (JNK) signaling resulting in increased caspase-11 expression and activation, and more non-canonical NLRP3-dependant inflammasome activation. Intriguingly, this leads to protection of the colon epithelium for up to 10 days in Rip2-deficient mice infected with C. rodentium. Our findings designate NOD2 and RIP2 as key regulators of cellular ROS homeostasis and demonstrate for the first time that ROS regulates caspase-11 expression and non-canonical NLRP3 inflammasome activation through the JNK pathway.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Western
  • Carrier Proteins / metabolism*
  • Caspases / metabolism*
  • Citrobacter rodentium / pathogenicity
  • Colitis / immunology
  • Colitis / metabolism
  • Colitis / microbiology
  • Colitis / pathology
  • Enterobacteriaceae Infections / immunology*
  • Enterobacteriaceae Infections / metabolism
  • Enterobacteriaceae Infections / microbiology
  • Enterobacteriaceae Infections / pathology
  • Female
  • Inflammasomes / immunology*
  • Inflammasomes / metabolism
  • JNK Mitogen-Activated Protein Kinases / metabolism
  • Macrophages / immunology
  • Macrophages / metabolism
  • Macrophages / microbiology
  • Macrophages / pathology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Inbred NOD
  • Mice, Knockout
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • Nod2 Signaling Adaptor Protein / physiology*
  • Reactive Oxygen Species / metabolism*
  • Receptor-Interacting Protein Serine-Threonine Kinases / physiology*
  • Signal Transduction

Substances

  • Carrier Proteins
  • Inflammasomes
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • Nlrp3 protein, mouse
  • Nod2 Signaling Adaptor Protein
  • Nod2 protein, mouse
  • Reactive Oxygen Species
  • Receptor-Interacting Protein Serine-Threonine Kinases
  • Ripk2 protein, mouse
  • JNK Mitogen-Activated Protein Kinases
  • Casp4 protein, mouse
  • Caspases