Establishment of mouse ulcerative colitis model

Mice were randomly divided into five groups of 10 mice each: control group, DSS model group, mesalazine group (DSS + Mesalazine), low-dose HLD group (DSS + HLD-L), and high-dose HLD group (DSS + HLD-H). According to related studies [5, 19] and our previous work, all groups except the normal group were given 2.5% DSS ad libitum for seven days to replicate the ulcerative colitis model. The success of the model replication was based on a significant decrease in body weight, a significant increase in the disease activity index, a significant increase in serum inflammatory factor levels, and a significant shortening of colon length with a large amount of inflammatory infiltration. All mice were anesthetized with isoflurane, an inhalational anesthetic. The mice in the control group were not specially treated, and the mice in the DSS group were administered an equal amount of distilled water enema. The positive drug group was given 0.82 g/kg Mesalazine daily, the HLD-L group was given 12.81 g/kg/d HLD enema, and the HLD-H group was given 25.62 g/kg/d HLD enema for seven consecutive days. After the final administration, all mice fasted without water for 12 h. Blood was collected from the orbital plexus under anesthesia, centrifuged (4 °C, 600 × g, 10 min) to extract the supernatant, and stored at -80 °C. After blood collection, the mice were euthanized via inhalation of carbon dioxide in a specific device, and the colonic tissue was separated. A portion of the tissue from the distal colon was cut and fixed in a 4% paraformaldehyde solution, and the rest of the tissue was stored at -80 °C for subsequent experiments.