Altered IFN-γ-mediated immunity and transcriptional expression patterns in N-Ethyl-N-nitrosourea-induced STAT4 mutants confer susceptibility to acute typhoid-like disease

J Immunol. 2014 Jan 1;192(1):259-70. doi: 10.4049/jimmunol.1301370. Epub 2013 Nov 27.

Abstract

Salmonella enterica is a ubiquitous Gram-negative intracellular bacterium that continues to pose a global challenge to human health. The etiology of Salmonella pathogenesis is complex and controlled by pathogen, environmental, and host genetic factors. In fact, patients immunodeficient in genes in the IL-12, IL-23/IFN-γ pathway are predisposed to invasive nontyphoidal Salmonella infection. Using a forward genomics approach by N-ethyl-N-nitrosourea (ENU) germline mutagenesis in mice, we identified the Ity14 (Immunity to Typhimurium locus 14) pedigree exhibiting increased susceptibility following in vivo Salmonella challenge. A DNA-binding domain mutation (p.G418_E445) in Stat4 (Signal Transducer and Activator of Transcription Factor 4) was the causative mutation. STAT4 signals downstream of IL-12 to mediate transcriptional regulation of inflammatory immune responses. In mutant Ity14 mice, the increased splenic and hepatic bacterial load resulted from an intrinsic defect in innate cell function, IFN-γ-mediated immunity, and disorganized granuloma formation. We further show that NK and NKT cells play an important role in mediating control of Salmonella in Stat4(Ity14/Ity14) mice. Stat4(Ity14/Ity14) mice had increased expression of genes involved in cell-cell interactions and communication, as well as increased CD11b expression on a subset of splenic myeloid dendritic cells, resulting in compromised recruitment of inflammatory cells to the spleen during Salmonella infection. Stat4(Ity14/Ity14) presented upregulated compensatory mechanisms, although inefficient and ultimately Stat4(Ity14/Ity14) mice develop fatal bacteremia. The following study further elucidates the pathophysiological impact of STAT4 during Salmonella infection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Load
  • CD11b Antigen / genetics
  • CD11b Antigen / metabolism
  • Cation Transport Proteins / genetics
  • Cluster Analysis
  • DNA Mutational Analysis
  • Dendritic Cells / immunology
  • Dendritic Cells / metabolism
  • Gene Expression Regulation*
  • Genetic Loci
  • Genetic Predisposition to Disease*
  • Immunity, Innate / genetics
  • Interferon-gamma / immunology*
  • Interferon-gamma / metabolism
  • Killer Cells, Natural / immunology
  • Killer Cells, Natural / metabolism
  • Liver / immunology
  • Liver / metabolism
  • Liver / microbiology
  • Mice
  • Mutation* / drug effects
  • Natural Killer T-Cells / immunology
  • Natural Killer T-Cells / metabolism
  • Nitrosourea Compounds / toxicity
  • Pedigree
  • STAT4 Transcription Factor / genetics*
  • Salmonella Infections, Animal / genetics*
  • Salmonella Infections, Animal / immunology*
  • Salmonella Infections, Animal / microbiology
  • Salmonella Infections, Animal / mortality
  • Salmonella typhimurium / immunology
  • Spleen / immunology
  • Spleen / metabolism
  • Spleen / microbiology
  • Transcription, Genetic*
  • Transcriptome

Substances

  • CD11b Antigen
  • Cation Transport Proteins
  • Nitrosourea Compounds
  • STAT4 Transcription Factor
  • natural resistance-associated macrophage protein 1
  • Interferon-gamma