Abstract Background Investigating the impact of curcumin on IL-36α and IL-36γ expression in TNBS-induced colitis in rats. Methods Forty male Sprague-Dawley rats were randomly assigned to four groups (n = 10 per group): normal control, model, curcumin, and sulfasalazine. Rats in the model, curcumin, and sulfasalazine groups were induced with colitis by intrarectal instillation of a TNBS-ethanol solution, whereas the normal control group received an equal volume of 0.9 % NaCl solution. Beginning on day 2 after model induction, the curcumin and sulfasalazine groups were administered curcumin or sulfasalazine orally at a dose of 100 mg kg−¹ day−¹, respectively; the normal control and model groups received an equal volume of 0.9 % NaCl solution by gavage. After 7 days of treatment, the animals were sacrificed, and serum and colonic mucosa were collected. Body weight, disease activity index (DAI), and colon mucosal damage index (CMDI) were compared among the groups. Serum levels of IL-36α and IL-36γ were measured by ELISA, and the expression of IL-36α and IL-36γ proteins in colonic mucosal tissue was assessed by immunohistochemistry. Results Compared with the normal control group, the model group exhibited significantly higher disease activity index (DAI) and colon mucosal damage index (CMDI) scores (P 0.01), and serum levels of IL-36α and IL-36γ were markedly elevated (P 0.01). Compared with the model group, both the curcumin-treated and sulfasalazine-treated groups showed reductions in DAI, CMDI scores and serum IL-36α and IL-36γ concentrations; the curcumin group displayed lower values than the sulfasalazine group, with these differences reaching statistical significance (F = 3.531, 3.842, 24.503, 36.435; P 0.001). Relative to the normal control, the model group demonstrated increased expression of IL-36α and IL-36γ proteins in colonic tissue (P 0.05). In comparison with the model group, the curcumin and sulfasalazine groups showed decreased IL-36α and IL-36γ protein expression in the colonic mucosa, with the curcumin group again exhibiting lower expression than the sulfasalazine group; these differences were statistically significant (F = 3.461, 3.524; P 0.001). Conclusion Curcumin markedly suppresses the expression of IL-36α and IL-36γ in both serum and colonic mucosa of rats with experimentally induced colitis. Conflict of interest: Mr. Shilin, Tong: No conflict of interest Han, Bing: No conflict of interest Yong, Jiang: No conflict of interest
Shilin et al. (Thu,) studied this question.