Fig 6.

Termination of FTY720 treatment postinfection had minimal effects on peripheral blood lymphopenia or pathogen colonization. (A) Percentages of leukocyte populations in blood. Mice were treated with FTY720 or the vehicle for 6 days prior to C. rodentium infection and 2 days p.i. Leukocytes were isolated from the blood of vehicle-treated and FTY720-treated, C. rodentium-infected animals on day 14 p.i. and stained with a fluorochrome-labeled MAb. They were analyzed by flow cytometry, in which 10,000 to 20,000 events were recorded. The data represent the mean percentages of CD3⁺ (T cells), CD11c⁺ (DCs), B220⁺ (B cells), and Ly6G⁺ (neutrophils) cells at two time points during C. rodentium infection. The significance of differences between vehicle-treated (control) animals and FTY720-treated animals was determined by the Mann-Whitney U test (***, P < 0.001; **, P < 0.01;*, P < 0.05; n = 6 to 8 individual mice). Effect of FTY720 on the pathogen burden and clearance of C. rodentium infection. Representative images of whole-body (B) and ex vivo colon (co) and cecum (cae) (C) bioluminescence of vehicle-treated and FTY720-treated mice at day 14 p.i. are shown. (D) Bioluminescent signal from the colon. Data are expressed as the mean ± the SEM of 6 to 8 individual mice per group. The significance of differences was determined by the Mann-Whitney U test (***, P < 0.001). (E) Colonization and clearance of C. rodentium in vehicle-treated and FTY720-treated mice as indicated by counts of viable bacteria (CFU/g) in stool samples. Samples were taken at different time points for 14 days p.i. Data are expressed as the mean of 6 to 8 individual mice ± the SEM. The significance of differences was determined by the Kruskal-Wallis test, followed by Dunn's multiple-comparison test (**, P < 0.01; *, P < 0.05).