[Veratric acid relieves oxidative stress and DSS-induced colitis in mice by activating the Nrf2/HO-1 signaling pathway].

OBJECTIVES: To investigate the molecular mechanism by which veratric acid (VA) ameliorates oxidative stress injury and intestinal barrier dysfunction in mice with dextran sulfate sodium (DSS)-induced colitis. METHODS: Thirty male C57BL/6 mice were randomized equally into control group, DSS model group, and VA treatment group. The mice were assessed for changes in body weight, disease activity index (DAI), colon length, and colonic histopathology. Colonic expressions of TNF-α, IL-6, and IL-10 and oxidative stress markers (SOD, GSH, MDA, and COX-2) were determined using ELISA, and the expressions of tight junction proteins (ZO-1 and claudin-1) and Nrf2/HO-1 pathway proteins were detected using immunofluorescence staining and Western blotting. In Caco-2 cells with H₂O₂-induced oxidative stress, ROS accumulation was examined using flow cytometry and a DCFH-DA probe, and Nrf2 inhibitor (ML385) was used to validate the mechanism of VA for ameliorating oxidative stress. RESULTS: VA treatment significantly alleviated DSS-induced body weight loss, colon shortening and the increase of DAI score of the mice, resulting also in improved crypt structure and increased expressions of ZO-1 and claudin-1 and the number of goblet cells. VA obviously reduced colonic levels of TNF‑α and IL-6, increased the level of IL-10, and reversed DSS-induced decreases in SOD and GSH activity and increases in MDA and COX-2 levels. In H₂O₂-treated Caco-2 cells, VA decreased ROS-positive cell rate and intracellular ROS accumulation, and increased cellular expressions of claudin-1 and ZO-1. Mechanistically, VA promoted the expressions of Nrf2 and the downstream HO-1 protein, and ML385 partially reversed ROS-reducing effect of VA. CONCLUSIONS: VA enhances antioxidant defense, inhibits inflammation, and repairs intestinal barrier function in mice with DSS-induced colitis by activating the Nrf2/HO-1 pathway, suggesting a novel strategy for treatment of inflammatory bowel disease.