Innate immunity restricts Citrobacter rodentium A/E pathogenesis initiation to an early window of opportunity
Fig 5
Early C. rodentium-induced innate immune response.
(A) Lipocalin-2 quantification by ELISA in feces of germ-free mice infected for 18 h with 104 CFU C. rodentium (blue circles), 1010 CFU C. rodentium (red squares), 1010 CFU C. rodentium Δler (green triangles), 1010 E. coli HS (orange hexagons) or left uninfected (grey diamonds). MyD88-/-Triflps/lps germ-free mice were infected for 18 h with 104 CFU C. rodentium (open blue circles), 1010 CFU C. rodentium (open red squares), or left uninfected (open grey diamonds). N = 4–13 per group. Data were pooled from 3 independent experiments. (B and C) Gene expression levels of Cxcl1 (B) and Nos2 (C) in the distal colon of infected mice as determined by qPCR. (D-G) Cytokine protein levels in the distal colon of infected mice as determined by Luminex technology. (H and I) Leukocyte analysis by flow cytometry of peripheral blood. Monocytes were defined as CD45+, CD11b+, CD115+ population (H). Neutrophils were defined as CD45+, CD11b+, Ly6G+ population. Quantities are expressed as absolute numbers of cells per mL blood. (J and K) Large intestinal leukocyte analysis by flow cytometry. Infiltrating monocytes were defined as CD45+, CD11b+, CD64-, LygG-, Ly6Chigh, and MHCII- population (J). Neutrophils were defined as CD45+, CD11b+, Ly6G+ population (K). Quantities are expressed as percentages of leukocytes (of CD45+ population). Dotted lines represent detection limit. ns, statistically not significant; *, p < 0.05; **, p < 0.01; ***, p < 0.001; ****, p < 0.0001; groups were compared with the matching uninfected control group; statistical tests: Kruskal-Wallis (A), and 1-way ANOVA (B-K).