Flagellin hypervariable region determines symbiotic properties of commensal Escherichia coli strains
Fig 5
EcN-flagellin–induced protective effects are mediated by host TLR5+CD11c+ cells in the cLP.
(a) Schematic depiction of the generation of BMCM as described in the experimental procedures. Red dots represent the typical sites of TLR5 expression in the mouse intestine. (b) Different SPF BMCM were administered 3.5% DSS in drinking water at day 0. Mice were additionally treated with 1010 viable bacteria of EcN or the EcNΔ(fliC)HVR mutant resuspended in 100 mL DSS-containing drinking water. See text for further information on the nomenclature of distinct BMCM groups. Indicated p-values refer to the comparison of the respective data set with the WT → Tlr5−/− + DSS + EcN group. Upper panel: HCS at day 7. Lower panel: HE-stained colonic sections at day 7 after start of DSS administration. (d) Irradiated WT recipient mice were transplanted with bone marrow from Tlr5−/− and ΔCD11c donor mice in a 1:1 ratio. Mice were administered 3.5% DSS in drinking water at day 0. Mice were additionally treated with 1010 viable bacteria of EcN resuspended in 100 mL DSS-containing drinking water and compared to control groups. See text for further information on the BMCM groups nomenclature. Middle panel: HCS at day 7. Right panel: HE-stained colonic sections at day 7 after start of DSS administration. Statistics: (b) One-way ANOVA with Tukey multiple comparison test, (c) Mann–Whitney test, (d) Kruskal–Wallis test with multiple comparisons, p-values < 0.05 are considered to represent statistical significance. (b + c) The data underlying this figure can be found in S1 Data. BMCM, bone-marrow–chimeric mice; cLP, colonic LP; DSS, dextran sodium sulphate; EcN, E. coli Nissle 1917; fliC, flagellin; HCS, histological colitis score; HE, hematoxylin–eosin; HVR, hypervariable region; LP, lamina propria; SPF, specific-pathogen–free; TLR, Toll-like receptor; WT, wild type.