Fig. 3.

Mesenteric resident bacteria exacerbate colitis in mice. a SPF C57BL/6 mice were treated by an antibiotic cocktail for 4 days. One day post antibiotics, the mice were daily orally colonized with bacterial cocktail (5-Mix or E. fergusonii, 10⁹ CFU/mouse/dose) or BHI until being euthanized. After 5 days bacterial colonization, the mice were exposed to 3% DSS for 7 days, followed by regular water for 3 days. b and c Changes of body weight (b) and disease activity index (DAI) after administration of 3% DSS (c). d–g Representative colons (d), colon length (e), representative colonic histological images (Scale bar = 40 μm and 10 μm) (f), colonic histological score (g) in mice treated with 5-mix bacterial cocktail, E. fergusonii and BHI. h Messenger RNA levels of key cytokines (TNF-α, IL-6, and IL-1β) in the terminal ileum (n=5 per group). i SPF Il10^−/− mice were treated with antibiotics cocktail for 4 days. One day post antibiotics, the mice were daily orally colonized with bacterial cocktail (5-Mix or E. fergusonii, 10⁹ CFU/mouse/dose) or BHI for 3 weeks. j–m Representative colons (j), colon length (k), representative colonic histological images (Scale bar= 40 μm and 20 μm) (l), colonic histological score from Il10^−/− mice treated with 5-Mix, E. fergusonii and BHI (m). n Inflammatory cytokines from macrophage cell line RAW264.7 after co-culture with 5 different bacteria or 5-Mix. Results are shown as the mean ± SEM. Each dot indicates an individual mouse. The statistical significance values are denoted as: *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001. One-way ANOVA following Tukey’s multiple comparison test (e, g, h, k, m, and n); two-way ANOVA following Tukey’s multiple comparison test (b and c). A.p, A. pulmonis; O.a, O.anthropi; P.a, P.alcaliphila; A.d, A.deleyi; D.r, D.riboflavina