Fig. 6: The gut microbiota derived from the KO-DSS mice displayed more severe colon injuries in the FMT C57BL/6J mice.

A Mice were administered with a spectrum antibiotic mixture of penicillin (200 U/mL) and streptomycin (200 μg/mL) by oral gavage for 3 days and then transplanted with microbiota which were harvested from WT-DSS (WT-DSS FMT) and KO-DSS (KO-DSS FMT) mice for 5 days and rested for 3 days. Finally, 3% DSS was given to these mice and sacrificed in 7 days (n = 5/group). B Body weight was recorded during FMT assay. C The length of the colon from WT-DSS FMT and KO-DSS FMT mice was recorded after 7 days of 3% DSS treatment. D Representative images of PAS staining of the colon tissue and statistical analysis of the PAS-positive cells number. Black arrows pointed to the PAS-positive cells. Scale bars: 200 μm (whole colon sections) and 50 μm (enlarged insets). E The expression of ZO1, MUC1, and occludin in the colon of WT-DSS FMT and KO-DSS FMT mice were detected by western blotting. F Qualification of the band intensity of occludin, MUC1, and ZO-1. G q-PCR analyzed the mRNA expression level of antimicrobial peptides such as Defa-1, Defa-4, Defa-5, Camp, and Lyz in colon tissue. H q-PCR analyzed the mRNA expression level of Il-1β, Il-6, Il-22, Il-23, Ifn-γ, and Tnf-α in colon tissue. I Fecal microbiota from WT-DSS and KO-DSS mice co-cultured with intestinal epithelial cell line MODE-K. J ROS levels of MODE-K cells treated with microbiota were detected by fluorescent probe (red). The black arrows were directed toward the ROS-positive cells. Scale bars: 50 μm. K q-PCR analyzed the mRNA expression of occludin, Muc1, Muc2 after MODE-K cells were infected with fecal microbiota. L q-PCR analyzed the mRNA expression of Il-1β, Il-6, Il-10, and Tnf-α in MODE-K infected with fecal microbiota. All bars represent the mean of measurements from three independent experiments, and the error bars indicate ±SEM; *P < 0.05, **P < 0.01, ***P < 0.001, “ns” indicates not significant. Two-tailed Student’s t test (B–H, J–L).