The capsule-encoding viaB locus reduces intestinal inflammation by a Salmonella pathogenicity island 1-independent mechanism.
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.
Haneda
Takeshi
T
Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, California 95616-8645, USA.
Winter
Sebastian E
SE
Butler
Brian P
BP
Wilson
R Paul
RP
Tükel
Cagla
C
Winter
Maria G
MG
Godinez
Ivan
I
Tsolis
Renée M
RM
Bäumler
Andreas J
AJ
D000818:Animals; D002432:Cecum / Q000382:microbiology / Q000473:pathology; D002460:Cell Line; D016207:Cytokines / Q000096:biosynthesis; D004847:Epithelial Cells / Q000382:microbiology; D023061:Gene Order; D044404:Genomic Islands; D006801:Humans; D007249:Inflammation / Q000382:microbiology / Q000473:pathology*; D007413:Intestinal Mucosa / Q000382:microbiology / Q000473:pathology*; D051379:Mice; D008954:Models, Biological; D011135:Polysaccharides, Bacterial / Q000502:physiology*; D012485:Salmonella typhi / Q000276:immunology / Q000472:pathogenicity*; D012486:Salmonella typhimurium / Q000276:immunology / Q000472:pathogenicity*
D016207:Cytokines; D011135:Polysaccharides, Bacterial