The capsule-encoding viaB locus reduces intestinal inflammation by a Salmonella pathogenicity island 1-independent mechanism

Infect Immun. 2009 Jul;77(7):2932-42. doi: 10.1128/IAI.00172-09. Epub 2009 May 18.

Abstract

Salmonella enterica serotype Typhimurium elicits acute neutrophil influx in the human intestinal mucosa within 1 or 2 days after infection, resulting in inflammatory diarrhea. In contrast, no overt symptoms are observed within the first 1 or 2 weeks after infection with S. enterica serotype Typhi. Here we show that introduction of the capsule-encoding viaB locus of serotype Typhi reduced the ability of serotype Typhimurium to elicit acute intestinal inflammation in a streptomycin-pretreated mouse model. Serotype Typhimurium requires a functional invasion-associated type III secretion system (type III secretion system 1 [T3SS-1]) to elicit cecal inflammation within 48 h after infection of streptomycin-pretreated mice, and the presence of the viaB locus reduced its invasiveness for human intestinal epithelial cells in vitro. However, a reduced activity of T3SS-1 could not account for the ability of the viaB locus to attenuate cecal inflammation, because introduction of the viaB locus into an invasion-deficient serotype Typhimurium strain (invA mutant) resulted in a significant reduction of pathology and inflammatory cytokine expression in the cecum 5 days after infection of mice. We conclude that a T3SS-1-independent mechanism contributes to the ability of the viaB locus to reduce intestinal inflammation.

Publication types

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

MeSH terms

  • Animals
  • Cecum / microbiology
  • Cecum / pathology
  • Cell Line
  • Cytokines / biosynthesis
  • Epithelial Cells / microbiology
  • Gene Order
  • Genomic Islands
  • Humans
  • Inflammation / microbiology
  • Inflammation / pathology*
  • Intestinal Mucosa / microbiology
  • Intestinal Mucosa / pathology*
  • Mice
  • Models, Biological
  • Polysaccharides, Bacterial / physiology*
  • Salmonella typhi / immunology
  • Salmonella typhi / pathogenicity*
  • Salmonella typhimurium / immunology
  • Salmonella typhimurium / pathogenicity*

Substances

  • Cytokines
  • Polysaccharides, Bacterial