Calming the inflammatory storm: 4-methylcatechol ameliorates DSS-induced colitis by suppressing the NLRP3 inflammasome signaling pathway

Abstract

The natural polyphenol metabolite 4-methylcatechol (4-MC) has demonstrated anti-inflammatory and antioxidant properties. However, its effectiveness in ulcerative colitis (UC) and the molecular mechanisms involved are still poorly understood. This study aimed to evaluate the protective effects of 4-MC in a dextran sulfate sodium (DSS)-induced murine colitis model, with a particular focus on its potential role in modulating the NLRP3 inflammasome pathway. Colitis was induced in mice by administering 5% DSS in drinking water. Mice were divided into the Control, Model (DSS), Model + sulfasalazine (SASP), and Model + 4-MC groups. Disease severity was monitored through body weight changes, disease activity index (DAI) scoring, and colon length measurement. Histological injury was evaluated by H&E and TUNEL staining. Intestinal barrier integrity was examined via immunofluorescence staining of occludin and E-cadherin. Inflammatory markers (TNF-, IL-6), myeloperoxidase (MPO) activity, oxidative stress markers (SOD, MDA, GSH), and key proteins in the NF-B and NLRP3 pathways were measured by ELISA, biochemical kits, Western blot and immunofluorescence. 4-MC treatment significantly ameliorated the disease manifestations of DSS-induced colitis, including weight loss, increased DAI, and colon shortening. It attenuated colonic histopathological damage, reduced apoptosis, and increased the levels of the tight junction proteins occludin and E-cadherin. Furthermore, 4-MC suppressed the inflammatory response by decreasing TNF-, IL-6, and MPO levels. Mechanistically, 4-MC inhibited the activation of the NF-B pathway, alleviated oxidative stress, and suppressed the NLRP3 inflammasome pathway. 4-MC may protect against DSS-induced colitis by enhancing intestinal barrier function, attenuating inflammatory and oxidative stress responses, and suppressing NLRP3 inflammasome activation.