Oxidative stress and changes in the content and pattern of tissue expression of β-catenin protein in diversion colitis

Abstract

The aim of this study is to verify if oxidative stress is related to changes in content and pattern of β-catenin protein expression in an experimental model of diversion colitis. Methods: Sixty Wistar rats were submitted to intestinal bypass. The animals were divided into three groups according to the sacrifice to take place in six, 12 and 18 weeks. For each group, five animals only underwent laparotomy (control). The presence of colitis was diagnosed by histological study, and its severity, by inflammation grading scale. Cellular oxidative stress was measured by comet assay. Tissue expression of β-catenin protein was analyzed by the immunohistochemistry and quantification of its tissue content by computerized morphometry. Statistical analysis was performed with the Student's t-test, median, Mann-Whitney, ANOVA and Kruskal-Wallis, adopting a significance level of 5% (p <0.05). Results: Colon segments without fecal stream developed colitis, which worsened with time of exclusion. Segments without fecal stream suffer higher levels of oxidative stress when compared to those with stream, and it worsens with time of exclusion. The levels of cellular oxidative stress are directly related to the degree of inflammation. The total content of β-catenin in segments without fecal stream reduces after six weeks, and does not vary thereafter. The content of β-catenin in the apical portion of the colon crypts decreases with time, whereas in the basal region, it increases. The total content of β-catenin is inversely related to the degree of inflammation and levels of tissue oxidative stress levels. Conclusion: There are changes in tissue content of E-cadherin and increased expression of β-catenin in proliferative regions of colonic crypts, related with oxidative tissue stress.

Claudin-3 and occludin content in the glands of colonic mucosa devoid from fecal stream submitted to topical intervention with oil extract of Curcuma longa

“…These findings raise the possibility that overproduction of OFR resulting from mitochondrial dysfunction, due to lack of supply of VFAs, may damage TJs by reducing the tissue content of claudin-3 and occludin. This hypothesis is supported by other studies of our group that have analyzed the protein components of AJs (E-cadherin and β-catenin) in an experimental model of CDC and showed that the levels of both proteins decreased with the time of fecal diversion and was correlated with overproduction of OFR by cells of colonic mucosa devoid from fecal stream [8][9][10] . This evidence reinforces the importance of VFAs in the maintenance the integrity of both TJs and AJs in experimental CDC.…”

“…For the immunoexpression study of claudin-3 and occludin proteins, we used standardized methodology adopted in other studies of our group and obeying the datasheet of the manufacturers of each of the primary antibodies [9][10][11] . As primary antibody, we used anti-claudin-3 monoclonal antibody (Ref.…”

“…In oxidative stress, the increase in the production of OFR, mainly hydroxyl radical (OH) can react with constitute substances of the colonic epithelial mucosa causing breakdown of the different structural defense mechanisms of the colonic barrier allowing the bacterial infiltration of the internal environment 4,7 . Studies showed that over production of OFR reduce and modify the mucus layer that covers the colonic mucosa, causes lipid peroxidation of the cell membranes, break the proteins constituents of adherents junctions (AJs) and tight junctions (TJs) [8][9][10][11] . Experimentally it has been demonstrated that the rupture of the epithelial barrier are related to higher levels of OFR and the development of CDC 9,10 .…”

“…Studies showed that over production of OFR reduce and modify the mucus layer that covers the colonic mucosa, causes lipid peroxidation of the cell membranes, break the proteins constituents of adherents junctions (AJs) and tight junctions (TJs) [8][9][10][11] . Experimentally it has been demonstrated that the rupture of the epithelial barrier are related to higher levels of OFR and the development of CDC 9,10 . Several substances have been tested for the treatment of CDC.…”

“…No studies evaluated the effects of topical application of curcumin-containing enemas to protect against the damage of TJs in experimental models of CDC. When it was shown that oxidative stress can damage constituent proteins of TJs and curcumin has remarkable antioxidant activity, it is interesting to evaluate the effectiveness of the substance to preserve the tissue content of the claudin-3 and occludin, the main proteins constituents of the TJs in an experimental model of CDC 9,10 . If curcumin is capable of preserving the TJs integrity and consequently reduce the damage of this important mechanism of intercellular adhesion, its low cost and bioavailability could make it interesting alternative for the treatment of CDC.…”