FIG 1.

B. fragilis colonization protects mice against dextran sulfate sodium (DSS)-induced colitis. C57BL/6J (B6) mice were treated orally with either PBS or B. fragilis three times a week starting a week prior to DSS treatment and continuing until the end of the experiment (5 mice per group). DSS (2.5%) was administered via the drinking water for 6 days followed by administration of regular drinking water. Mice were sacrificed on day 8. (A) Percent weight change during DSS-induced colitis. (B) Inflammation score of colon sections of the indicated groups. (C) Expression levels of IL-1β, IL-6, TNF-α, IL-10, CCL3, and CCR5 from colon homogenates of control or B. fragilis-colonized mice on day 8 of DSS treatment. Relative values were normalized to that of β-actin. Data are representative of results from at least two experiments. Statistical significance was calculated using unpaired Student's t tests and nonparametric Mann-Whitney tests. *, P < 0.05; **, P < 0.005 (in all panels).