Suppression of hepcidin expression and iron overload mediate Salmonella susceptibility in ankyrin 1 ENU-induced mutant

PLoS One. 2013;8(2):e55331. doi: 10.1371/journal.pone.0055331. Epub 2013 Feb 4.

Abstract

Salmonella, a ubiquitous Gram-negative intracellular bacterium, is a food borne pathogen that infects a broad range of hosts. Infection with Salmonella Typhimurium in mice is a broadly recognized experimental model resembling typhoid fever in humans. Using a N-ethyl-N-nitrosurea (ENU) mutagenesis recessive screen, we report the identification of Ity16 (Immunity to Typhimurium locus 16), a locus responsible for increased susceptibility to infection. The position of Ity16 was refined on chromosome 8 and a nonsense mutation was identified in the ankyrin 1 (Ank1) gene. ANK1 plays an important role in the formation and stabilization of the red cell cytoskeleton. The Ank1(Ity16/Ity16) mutation causes severe hemolytic anemia in uninfected mice resulting in splenomegaly, hyperbilirubinemia, jaundice, extramedullary erythropoiesis and iron overload in liver and kidneys. Ank1(Ity16/Ity16) mutant mice demonstrated low levels of hepcidin (Hamp) expression and significant increases in the expression of the growth differentiation factor 15 (Gdf15), erythropoietin (Epo) and heme oxygenase 1 (Hmox1) exacerbating extramedullary erythropoiesis, tissue iron deposition and splenomegaly. As the infection progresses in Ank1(Ity16/Ity16), the anemia worsens and bacterial load were high in liver and kidneys compared to wild type mice. Heterozygous Ank1(+/Ity16) mice were also more susceptible to Salmonella infection although to a lesser extent than Ank1(Ity16/Ity16) and they did not inherently present anemia and splenomegaly. During infection, iron accumulated in the kidneys of Ank1(+/Ity16) mice where bacterial loads were high compared to littermate controls. The critical role of HAMP in the host response to Salmonella infection was validated by showing increased susceptibility to infection in Hamp-deficient mice and significant survival benefits in Ank1(+/Ity16) heterozygous mice treated with HAMP peptide. This study illustrates that the regulation of Hamp and iron balance are crucial in the host response to Salmonella infection in Ank1 mutants.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anemia, Hemolytic / genetics*
  • Anemia, Hemolytic / metabolism
  • Anemia, Hemolytic / microbiology
  • Anemia, Hemolytic / mortality
  • Animals
  • Ankyrins / genetics*
  • Ankyrins / metabolism
  • Antimicrobial Cationic Peptides / deficiency
  • Antimicrobial Cationic Peptides / genetics*
  • Codon, Nonsense / drug effects*
  • Erythrocytes / metabolism
  • Erythrocytes / pathology
  • Erythropoietin / genetics
  • Erythropoietin / metabolism
  • Ethylnitrosourea / toxicity*
  • Gene Expression
  • Genetic Predisposition to Disease
  • Growth Differentiation Factor 15 / genetics
  • Growth Differentiation Factor 15 / metabolism
  • Heme Oxygenase-1 / genetics
  • Heme Oxygenase-1 / metabolism
  • Hepcidins
  • Heterozygote
  • Homozygote
  • Iron / metabolism
  • Iron Overload / genetics*
  • Iron Overload / metabolism
  • Iron Overload / microbiology
  • Iron Overload / mortality
  • Liver / metabolism
  • Liver / pathology
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Mice
  • Salmonella Infections / genetics*
  • Salmonella Infections / metabolism
  • Salmonella Infections / microbiology
  • Salmonella Infections / mortality
  • Salmonella typhimurium / physiology
  • Survival Analysis

Substances

  • Ank1 protein, mouse
  • Ankyrins
  • Antimicrobial Cationic Peptides
  • Codon, Nonsense
  • Gdf15 protein, mouse
  • Growth Differentiation Factor 15
  • HAMP protein, human
  • Hamp protein, mouse
  • Hepcidins
  • Membrane Proteins
  • Erythropoietin
  • Iron
  • Heme Oxygenase-1
  • Hmox1 protein, mouse
  • Ethylnitrosourea