The natural cytotoxicity receptor NKp46 is dispensable for IL-22-mediated innate intestinal immune defense against Citrobacter rodentium

J Immunol. 2009 Nov 15;183(10):6579-87. doi: 10.4049/jimmunol.0901935. Epub 2009 Oct 21.

Abstract

Natural cytotoxicity receptors (including NKp30, NKp44, and NKp46 in humans and NKp46 in mice) are type I transmembrane proteins that signal NK cell activation via ITAM-containing adapter proteins in response to stress- and pathogen-induced ligands. Although murine NKp46 expression (encoded by Ncr1) was thought to be predominantly restricted to NK cells, the identification of distinct intestinal NKp46(+) cell subsets that express the transcription factor Rorc and produce IL-22 suggests a broader function for NKp46 that could involve intestinal homeostasis and immune defense. Using mice carrying a GFP-modified Ncr1 allele, we found normal numbers of gut CD3(-)GFP(+) cells with a similar cell surface phenotype and subset distribution in the absence of Ncr1. Splenic and intestinal CD3(-)NKp46(+) cell subsets showed distinct patterns of cytokine secretion (IFN-gamma, IL-22) following activation via NK1.1, NKp46, IL-12 plus IL-18, or IL-23. However, IL-22 production was sharply restricted to intestinal CD3(-)GFP(+) cells with the CD127(+)NK1.1(-) phenotype and could be induced in an Ncr1-independent fashion. Because NKp46 ligands can trigger immune activation in the context of infectious pathogens, we assessed the response of wild-type and Ncr-1-deficient Rag2(-/-) mice to the enteric pathogen Citrobacter rodentium. No differences in the survival or clinical score were observed in C. rodentium-infected Rag2(-/-) mice lacking Ncr1, indicating that NKp46 plays a redundant role in the differentiation of intestinal IL-22(+) cells that mediate innate defense against this pathogen. Our results provide further evidence for functional heterogeneity in intestinal NKp46(+) cells that contrast with splenic NK cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Ly / genetics
  • Antigens, Ly / immunology*
  • Antigens, Ly / metabolism
  • Citrobacter rodentium / immunology*
  • Cytokines / immunology
  • Cytokines / metabolism
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / immunology*
  • DNA-Binding Proteins / metabolism
  • Enterobacteriaceae Infections / immunology
  • Enterobacteriaceae Infections / microbiology
  • Immunity, Innate
  • Interleukin-22
  • Interleukins / immunology*
  • Interleukins / metabolism
  • Intestine, Small / immunology*
  • Intestine, Small / metabolism
  • Intestine, Small / microbiology
  • Killer Cells, Natural / immunology*
  • Killer Cells, Natural / metabolism
  • Killer Cells, Natural / microbiology
  • Lymphocyte Activation / immunology
  • Mice
  • Mice, Inbred C57BL
  • Natural Cytotoxicity Triggering Receptor 1 / genetics
  • Natural Cytotoxicity Triggering Receptor 1 / immunology*
  • Natural Cytotoxicity Triggering Receptor 1 / metabolism
  • Nuclear Receptor Subfamily 1, Group F, Member 3 / immunology
  • Nuclear Receptor Subfamily 1, Group F, Member 3 / metabolism
  • Spleen / cytology
  • Spleen / immunology*
  • Spleen / metabolism
  • Spleen / microbiology

Substances

  • Antigens, Ly
  • Cytokines
  • DNA-Binding Proteins
  • Interleukins
  • Natural Cytotoxicity Triggering Receptor 1
  • Ncr1 protein, mouse
  • Nuclear Receptor Subfamily 1, Group F, Member 3
  • Rag2 protein, mouse
  • Rorc protein, mouse