STAT2 dependent Type I Interferon response promotes dysbiosis and luminal expansion of the enteric pathogen Salmonella Typhimurium
Fig 6
Neutrophil influx and luminal oxygenation promotes S. Typhimurium survival.
C57BL/6 and Stat2-/- mice were orally infected with 109 CFU of S. Typhimurium following streptomycin pretreatment. A. Neutrophils were counted in ten fields in H&E stained tissue sections and the number of neutrophils were averaged for each sample. B. The enzymatic activity of MPO was quantified in fecal samples by ELISA. C. Paraffin embedded sections were stained with anti-MPO antibody (green) as well as DAPI (blue) to mark the nucleus. Images were captured using SPOT imaging software at 40x. C57BL/6 and Stat2-/- mice were orally infected with a 1:1 ratio of wild type S. Typhimurium and cyxA mutant mutant following streptomycin pretreatment. Mice were euthanized 4 days after infection and the competitive index (CI, output ratio of WT/cyxA mutant divided by input ratio of WT/cyxA mutant) was calculated in the D. colon contents and E. liver. F. colons of WT and Stat2-/- mice infected with 1:1 ratio of WT S. Typhimurium: cyxA mutant were collected 4 days post infection and paraffin embedded. Tissues were stained for hypoxia using the pimonidazole hypoxia probe (red) and DAPI (blue). Images were captured at 63x using Leica confocal microscope. Mean and SE were calculated by averaging results from three independent experiments. *p <0.05, ** p<0.01 as determined by Students t-test.