Quantification by computerized morphometry of tissue levels of sulfomucins and sialomucins in diversion colitis in rats

Abstract

PURPOSE: To quantify the intensity of sulfomucin and sialomucin expression in the colon mucosa, by means of computer-assisted image processing, comparing segments with and without fecal stream and correlating with the duration of fecal transit exclusion. METHODS: Forty-five Wistar rats were subjected to diversion of the fecal stream in the left colon by means of constructing a proximal colostomy and distal mucosal fistula. They were distributed randomly into three experimental groups of 15 animals, of which 10 were subjected to colon diversion (experimental subgroup) and five were only subjected to laparotomy, without colon diversion (control subgroup). The three experimental groups were formed according to the sacrifice date, which was to be performed six weeks after the surgical procedure (Group A), 12 weeks (Group B) and 18 weeks (Group C). The sulfomucin and sialomucin expression in the colon mucosa was evaluated using the histochemical technique of high iron diamine-alcian blue (HID-AB). The tissue expression was quantified for each animal, in the segments with and without fecal stream, at a location where there were four complete contiguous crypts in two random fields, with the aid of the computer-assisted image analysis software. The final value was taken to be the mean reading from the two fields selected, in the segments with and without fecal stream. To compare the expressions of the two mucin subtypes in the segments with and without fecal stream, the paired Student t test was used. To analyze variance according to duration of exclusion, ANOVA with the Newman-Keuls post-test was used, setting the significance level at 5% (p<0.05). RESULTS: There were significant reductions in tissue sulfomucin and sialomucin content in the colon without fecal stream, independent of the duration of exclusion considered. There was increased tissue sulfomucin content and decreased tissue sialomucin in the segments without fecal stream, with increasing duration of exclusion. CONCLUSIONS: Diversion of the fecal transit decreased the tissue sulfomucin and sialomucin content in the segments without fecal stream. Notwithstanding the reduction in the levels of both subtypes of acid mucin in the segments without fecal stream, there was increased tissue sulfomucin content and decreased tissue sialomucin with increasing duration of intestinal diversion.

Evaluation of the application of enemas containing sucralfate in tissue content of neutral and acid mucins in experimental model of diversion colitis

“…Glotzer et al 1 The mucous layer covering the colon epithelium is the first line of defense against invasion of the intestinal wall by bacteria and antigen that are present in the intestinal lumen 4,5 . Most of the protective effect provided by the mucous layer relates to the presence of mucins, which are the predominant glycoproteins in the chemical composition of colonic mucous [6][7][8] .…”

“…The capacity of the colonic epithelium to produce mucins depends on adequate supply of SCFAs 7 . Recent studies have shown the importance of maintaining the supply of SCFAs, particularly butyrate, in order to have adequate gene expression relating to mucin formation and content of the glycoprotein 4,5,8,13 .…”

“…Despite the histopathological similarities between UC and DC, few studies has evaluated the modifications in the tissue contents and pattern of expression of neutral and acid mucins on glands of the colonic mucosa without fecal stream 4,5,13 . The results of these studies showed that the deviation of the fecal stream reduce the content and modify the pattern of tissue expression of neutral and acid mucins.…”

“…The results of these studies showed that the deviation of the fecal stream reduce the content and modify the pattern of tissue expression of neutral and acid mucins. In other words, the deficiency in the supply of SCFAs can modify the mucus that overlying the colonic mucosa, reducing the effectiveness of this first line of defense against luminal aggression 5,13 .…”

Evaluation of topical n-acetylcysteine in diversion colitis

“…The resulting oxidative stress causes histological and biochemical alterations similar to those found in experimental models of chemically induced colitis or human colitis. The oxidative stress causes alterations in the colonic mucosa that aggravate according to the time of diversion [20][21][22][23][24][25][26][27] . Based on these evidences, the use of substances with antioxidant activity was suggested to be effective in the prevention and treatment of this disease 20,27 .The benefits of these substances in the treatment of DC were recently confirmed with the application of enemas with 5-aminosalicylic acid (5-ASA), a powerful antioxidant, was demonstrated to reduce the levels of tissue oxidative stress and improve the inflammatory process in the mucosa without fecal stream, even after the ex-vivo exposure to hydrogen peroxide (H 2 O 2 ) 27 .…”