DSS-Induced Colitis and Probiotic Treatment

Six-week-old male SPF C57BL/6 mice (weight, 18–20 g) were purchased from Shanghai SLRC Laboratory Animal Co. Ltd. (Shanghai, China). The mice were housed at a constant temperature of 23 ± 2°C with a 12-h dark/light cycle and given ad libitum access to standard chow and water at all times. All mice were allowed at least 1 week to adapt to the experimental environment before conducting the following experiments. The experimental procedures were performed in accordance with the institutional and governmental regulations on the ethical use of experimental animals.
The mice were randomly divided into 11 groups of eight (Figure 1). The Control group was given free access to sterile water and fed a normal diet for the whole experimental period (12 days). The DSS group was given free access to 2.5% DSS-containing drinking water for the first 7 days and then fed normal diet and normal water for the next 5 days of the experiment. The DSS-treated mouse groups of L. plantarum AR113 and its seven bshmutant derivatives were administered the corresponding strains (0.2 mL containing 5 × 10⁹CFU/mL) once a day by gavage from day 5 to day 12. The 5-ASA group of DSS-treated mice was administered 5-ASA (0.2mL) once a day by gavage from day 5 to day 12.