Fecal microbiome transplantation of IMQ mice exacerbated DSS colitis. (A) GF mice were transplanted with a fecal microbiome derived from control mice (cont gnoto mice) or IMQ-treated mice (IMQ gnoto mice). Three weeks after transplantation, immune cells were analyzed by flow cytometry. (B) Percentage (left) and absolute number (right) of CD11b+CD64+ cells in CD45+CD3-CD19-B220- NK1.1- cells from colonic lamina propria. (C) Percentage (left) and absolute number (right) of B cells in CD45+ colonic lamina propria. (D) Percentage of IgA+ (left), IgD+ (middle), and IgM+ (right) B cells in the total B cells from colonic lamina propria (n = 6–7 in each group). (E) Experimental protocol. Cont gnoto mice and IMQ gnoto mice (shown in panel A) were further induced with acute colitis by 3% (wt/vol) DSS. After administration of DSS for 7 days, the severity of colitis was assessed. (F) Representative photograph of colon on day 7 of DSS colitis. (G) Body weight on day 7 of DSS colitis. (H) Colon length on day 7 of DSS colitis. (I) Partial DAI score on day 7 of DSS colitis. Partial DAI score was calculated as the sum of scores for perianal bleeding (0–4) and diarrhea (0–4) (part of the DAI score except for the body weight loss component). (J) Representative H&E staining of distal colon section on day 7 of DSS colitis. Scale bar: 100 μm. (K) Histologic score of colitis on day 7 of DSS (n = 3–5 in each group). (L) Experimental protocol. Mice treated with IMQ or vehicle subsequently were induced with colitis by 2% (wt/vol) DSS for 7 days. Feces derived from control mice, or saline, was administered daily by oral gavage, from the day before starting DSS to the end of the experiment. (M) Body weight changes during administration of DSS and (N) the percentage of the initial value (day 0 of DSS) of body weight on day 7 of DSS colitis. (O) DAI score on day 7 of DSS colitis (n = 6 in each group). (P) Experimental protocol. Mice treated with IMQ or vehicle were subsequently induced with colitis by 2% (wt/vol) DSS for 7 days. A mixture of L johnsonii and L reuteri, or saline, was administered daily by oral gavage, from the day before starting DSS to the end of the experiment. (Q) Body weight changes during administration of DSS and (R) the percentage of the initial value (day 0 of DSS) of body weight on day 7 of DSS colitis. (S) DAI score on day 7 of DSS colitis (n = 8 in each group). Each symbol represents an individual mouse. Statistical analyses were performed with the Student t test. *P < .05, **P < .01, ***P < .001. Error bars represent the SEM of samples within a group.