Epithelial innate immune stimulation during neonatal <i>Salmonella</i> infection.

<p>(<b>A and B</b>) Quantitative RT PCR for (<b>A</b>) <i>Cxcl2</i> and (<b>B</b>) <i>Reg3γ</i> mRNA in enterocytes isolated from the indicated gene-deficient mice at 4 days p.i. with 10² CFU WT <i>S.</i> Typhimurium. The results represent the median values from 2–3 independent experiments (n = 3–14 per group: wt, n = 14; Tlr4^−/−, n = 9; Tlr5^−/−, n = 6; Myd88^−/−, n = 3; Trif^−/−, n = 12; TLR2^−/−, n = 12; TLR9^−/−, n = 12; 3d (Unc93B1 H412R), n = 3; NOD2^−/−, n = 12). (<b>C and D</b>) Organ counts in (C) colon, spleen, liver and (D) mesenteric lymph nodes (MLN) of 1-day-old Tlr4^−/− neonate mice after oral infection with 10² CFU WT <i>S.</i> Typhimurium. The results represent the median values from 3 independent experiments (n = 3–6 per group). (<b>E</b>) Immunostaining of small intestinal tissue 4 days after infection of 1-day-old Tlr4^−/− neonate mice with 10² CFU <i>S.</i> Typhimurium (red). Counterstaining with E-cadherin (green) and Dapi (blue). i, bar = 20 µm; ii, bar = 10 µm. (<b>F</b>) Viable bacteria cultured from primary enterocytes isolated from small intestinal tissue at day 4 p.i. with WT <i>S.</i> Typhimurium and left untreated or incubated in gentamicin. The results represent the median values from one out of two independent experiments (n = 7–9 per group). (<b>G</b>) Flow cytometric analysis of enterocytes isolated at day 4 p.i. from 1-day-old Tlr4^−/− mice infected with 10² CFU WT (GFP⁺) <i>S.</i> Typhimurium or from age-matched control animals. Cells were gated for the epithelial cell marker EpCAM (APC). The number of GFP-positive enterocytes of all EpCAM⁺ cells is indicated (%). One representative data set of three independent experiments is shown.