Figure 1.

Attenuated dextran sulfate sodium (DSS)-induced colitis in miR-155^−/− mice is dependent on commensal bacteria. WT or miR-155^−/− mice were given 3% DSS in drinking water for 5 days, followed by regular drinking water for 6 days. (A–E) Weight change (A), Kaplan–Meier plot of survival rate (B), stool blood (C), representative gross colon appearance [(D) left] and colon length [(D) right], and representative H&E-stained colon cross-sections [(E) left, original magnification, 200× or 400×] and semi-quantitative histopathology score [(E) right]. (F) WT and miR-155^−/− mice were treated with broad-spectrum antibiotics cocktail (ABX) for 4 weeks and then given 3% DSS, the body weight change (left) and DAI (right) were monitored daily. Ns vs WT control (G,H). The LPMCs were isolated from colon tissues of DSS-treated WT (n = 12) and miR-155^−/− (n = 15) mice, then the total number of LPMCs (CD45⁺) (G), T cells (CD4⁺ and CD8⁺), DCs (CD11c⁺CD11b⁻) and macrophages (CD11b⁺CD11c^−/low) (H) were counted by flow cytometry. (I,J) Representative FACS showing CD4⁺IL-17⁺ cells (I) and CD4⁺IFN-γ⁺ cells (J) in isolated LPMCs of DSS-treated WT (n = 12) and miR-155^−/− (n = 15) mice. *P < 0.05, **P < 0.01 vs WT control [Student’s t-test in (A,D,E,G,H) and Kaplan–Meier analysis in (B,C)]. ns vs WT control. Data are representative of three independent experiments (mean and SD in A-D); n = 12–15 mice per group in (A–F) and n = 5–6 mice per group in (G). ns, not significant. WT, wild-type.