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. 2019 Jun 17;17(6):e3000334. doi: 10.1371/journal.pbio.3000334

Fig 6. Recombinant FliC protects against DSS-induced colitis.

Fig 6

(a) mTLR5-HEK293 cells were stimulated with rfliC(K12) or rfliC(EcN) for 24 h. Resulting IL-8 secretion into cell supernatant as a result of TLR5 receptor activation was detected by ELISA. (b) Experimental setup: SPF C57BL/6 WT mice aged 6 to 8 weeks were administered 2 μg recombinant flagellin daily via intragastral gavage. 3 days after start of flagellin administration, 3.5% DSS was added to the drinking water. Progress of DSS-induced colitis was monitored for additional 7 days. (c) HCS and representative HE-stained colonic sections at day 7. Statistical analysis was performed using the Kruskal–Wallis test. Error bars represent SD. White dots in column bars represent each biological replicate. (d) Heat map of cytokine concentrations in serum from DSS-treated mice as shown in (b). Each column represents a different individual. Right panel: IL-22 concentration in blood serum. Statistical analysis was performed using one-way ANOVA. Error bars represent SD. White dots in column bars represent each biological replicate. (e) Gating strategy to define the population of intDCs from the cLP. Lin = Ly6G/C, CD45R, CD64. (f + g) Proportion of IL-23+ (f) or IL-22+ (g) intDCs from the experiment shown in (b). Representative histograms or contour blots are shown. Statistical analysis was performed using one-way ANOVA. Error bars represent SD. White dots in column bars represent each biological replicate. p-values < 0.05 are considered to represent statistical significance. (a + c + d + f + g) The data underlying this figure can be found in S1 Data. cLP, colonic LP; DC, dendritic cell; DSS, dextran sodium sulphate; EcN, E. coli Nissle 1917; fliC, flagellin; FSC, forward scatter; HCS, histological colitis score; HE, hematoxylin–eosin; IL, interleukin; intDC, intestinal DC; LP, lamina propria; MG1655, E. coli K12 MG1655; mTLR5-HEK293 cell, mouse-TLR5–overexpressing human embryonic kidney 293 cell; ns, not significant; rfliC(EcN), recombinant flagellin from EcN; rfliC(K12), recombinant flagellin from MG1655; SPF, specific-pathogen–free; TLR, Toll-like receptor.