Fig. 1: Intestinal microbiota regulates susceptibility to CPI-induced colitis.
a Colon mass in wildtype female 6-week-old Balb/C mice at 1 week, 3 weeks and 6 weeks without treatment (Control: n = 56 at 1 week, n = 79 at 3 weeks, n = 4 at 6 weeks), treatment with combination anti-CTLA4/anti-PD-1 (CPI: n = 10 at 1 week, n = 25 at 3 weeks, n = 6 at 6 weeks), treatment with fecal microbiota (FMT: n = 6 at 1 week, n = 35 at 3 weeks, n = 24 at 6 weeks) and mice treated with both CPI and FMT (CPI + FMT: n = 68 at 1 week, n = 182 at 3 weeks, n = 23 at 6 weeks). Two-way ANOVA with Tukey’s multiple comparison test used ****P < 0.0001. CPI injections were given once a week intraperitoneally. b Representative colon sections cut at 3 µm thick FFPE from control, CPI, FMT and CPI + FMT treated wildtype female 6-week-old Balb/C mice stained with H&E (Leica). c Summary histological colitis score from mice treated with CPI-C (n = 11), plus controls (Control: n = 6, CPI: n = 7 and FMT: n = 7). Average colitis scored based on apoptosis (0–3), infiltrating lymphocytes (0–3), crypt abscess formation (0–3). Bar graph showing mean with SEM and Two-way ANOVA with Tukey’s multiple comparison test used whereby *P = 0.0106 **P = 0.0051 and ****P < 0.0001. d Representative flow cytometry plot showing the CD4+ and CD8+ T cell gating. e Number of CD4+ and CD8+ T cells from the colonic lamina propria of Control (n = 29), CPI (n = 12), FMT (n = 30) and CPI + FMT (n = 79) treated wildtype female 6-week-old Balb/C mice. Two-way ANOVA with Tukey’s multiple comparison test used ****P < 0.0001. f Representative flow cytometry plot showing Gr-1hi neutrophils from Control, CPI, FMT and CPI + FMT treated wildtype female 6-week-old Balb/C mice. g Number of Gr-1hi neutrophils from the colonic lamina propria of Control (n = 70), CPI (n = 18), FMT (n = 33) and CPI + FMT (n = 95) treated wildtype female 6-week-old Balb/C mice. Two-way ANOVA with Tukey’s multiple comparison test used **P<0.01 ****P < 0.0001.
