The protective effect of PTL against DSS-induced colitis disappeared after gut-microbiota depletion. (A) WT mice were put on a course of intragastric antibiotics administration for 5 days for gut microbiota depletion prior to DSS treatment. The ABX(DSS) and ABX(PTL+DSS) groups were intraperitoneal injection with 100 μl saline or 100 μl PTL solution from Day 0 to Day 14, respectively. (B) Body weight change. (C) Survival. (D) DAI score. (E) Representative pictures of colon gross appearance and colon length. (F) Representative microscopic pictures of H&E staining (40x and 200x magnification) and histology score. (G) Representative colonoscopy images and colonoscopy score. (A-G) n = 10 mice per group, mean values ± SD are presented, p values were calculated using Unpaired T-test, * p < 0.05, ** p < 0.01, *** p < 0.001. Data are pooled from three independent experiments with n = 10 mice per group.