Figure 4. The microbiota/mTOR axis regulates epithelial necrosis and colitis.

(A) Mice were intraperitoneally injected with vehicle or rapamycin (5 mg/kg for 5 days), colon sections (n = 5) were stained by IF, and double-positive cells were quantified over 15 images. Scale bars: 20 μm. (B and C) Three days after rapamycin treatment, mice were treated with 2.5% DSS for 5 days in the presence of rapamycin for only 2 days, and body weight (B) and survival (C) were recorded daily. (D) Immunoblots of colonic epithelial lysates from the indicated mice (n = 2). (E) Survival curve of mice treated with 2.5% DSS for 5 days (n = 12). (F) Immunoblots of colonic epithelial cell lysates from B6 mice maintained in a germ-free or specific pathogen–free facility (n = 2–4). p-RIPK1 (S166), p-RIPK3 (S232), p-MLKL (S345), p-S6 (S235/236), and p–4E-BP1 (Thr27/46) were used. Numbers under Western blot bands represent relative quantifications over actin. (G) Mice untreated or pretreated with antibiotics (ABX) for 5 weeks were challenged with 2.5% DSS for 5 days to induce colitis, and body weights were recorded daily (n = 5). Data were pooled from 3 independent experiments (B, C, and E) or are representative of 3 independent experiments (A, D, F, and G) and are shown as mean ± SEM. ***P < 0.001, ****P < 0.0001, by log-rank test (C and E), unpaired Student’s t test (B and G), or 1-way ANOVA (A).