Claudin-3 and occludin tissue content in the glands of colonic mucosa with and without a fecal stream.

The synthesis of the proteins of the apical tight junctions (TJs) depends on a continuous supply of short-chain fatty acids (SCFAs) in colonic epithelium. No studies have evaluated the tissue contents of the TJs proteins in colon segments devoid of a fecal stream. To evaluate the contents of claudin-3 and occludin in the glands of colonic mucosa devoid of a fecal stream. Forty-five rats underwent a diversion of the fecal stream via a left side colostomy and distal mucous fistula. Three groups of 15 animals each were sacrificed at 6, 12 or 18 weeks after surgery. The presence and severity of colitis were defined by histology and inflammation grading scales, respectively. The expression of claudin-3 and occludin were evaluated by immunohistochemistry, and their contents were evaluated by computer-assisted image analysis. Mann-Whitney and Kruskal-Wallis tests were used to evaluate the results at a significance level of 5% (p < 0.05). The colonic epithelium without a fecal stream had a higher degree of inflammation. Colonic glands without a fecal stream showed a reduction in claudin-3 content independent of the time and reduction in occludin content after 12 weeks of intestinal exclusion. The content of claudin-3 and occludin were mainly reduced at the apical surfaces of the colon glands, whereas segments retaining the fecal stream were maintained. The content of claudin-3 was not reduced with time, although the levels of occludin were reduced after 6 weeks and did not vary thereafter. Deficiencies in SCFAs decreased the content of claudin-3 and occludin in colonic glands with the areas of worst inflammation, confirming the importance of an adequate supply of SCFAs in maintaining the integrity of TJ proteins.