Intestinal barrier defects are involved in the pathogenesis of inflammatory bowel disease. The present study investigated the ameliorative effects of naringenin, a citrus polyphenol, on intestinal tight junction (TJ) barrier defects and inflammation in a murine model of colitis. In Expt. 1, using a 2 × 2 fractional design, the mice were administered water or 2% dextran sulfate sodium (DSS) in combination with feeding control or naringenin-containing diets for 9 d (severe disease stage). DSS administration caused severe colon damage and inflammation, as indicated by body weight loss, increased clinical sores, colon shortening, and gene expressions of inflammatory cytokines [interferon-γ, interleukin (IL)-6, macrophage inflammatory protein-2, and IL-17A). DSS administration also impaired TJ barrier integrity in the colon, as indicated by increased colon permeability and plasma LPS-binding protein levels, resulting from the impaired colonic expression of TJ proteins, occludin, junctional adhesion molecule-A, and claudin-3. Supplemental feeding with naringenin totally or partially attenuated these symptoms, suggesting that naringenin ameliorates the DSS-induced colitis at least partially through protection of the TJ barrier. In Expt. 2, analyses were performed at different disease stages (d 3, 6, and 9) to more widely examine the ameliorative role of naringenin on the initiation and development of colitis. DSS administration moderately induced colon shortening at d 3 and 6 and increased the disease activity index (DAI) and inflammatory cytokine (IL-6 and IL-17A) expression without any significant increases in colonic permeability. Feeding naringenin attenuated the increased DAI and colon shortening and tended to suppress the increased cytokine expression. These findings suggest that the presence of an additional mechanism underlying the naringenin-mediated, anticolitic effect along with barrier protection.

No abstract

No abstract