A study of histochemical changes in mucus from patients with ulcerative colitis, Crohn's disease, and diverticular disease of the colon

Is the colon mucosa affected by ten days of gastric restriction in an animal model?

PURPOSE

To identify whether the colon mucosa is affected by ten days of gastric restriction in an animal model.

METHODS

An experimental model of gastric restriction was devised using rats. The animals were submitted to surgical gastrostomy, and a cylindrical loofah was inserted into the stomach. We studied 30 adult male Wistar rats divided into three groups: the stomach restriction group (R10); the sham group (S10), which underwent the same procedure except for the loofah insertion; and the control group (C10). The expression of neutral and acid mucins was evaluated using histochemical techniques. Goblet cells and protein content were compared between groups using generalized estimation equations (GEEs). Bonferroni's multiple comparison was applied to identify differences between the groups. All tests considered a 5% significance level.

RESULTS

There was an increased expression of neutral mucins, acid mucins and goblet cells in the R10 group. Collagen was also enhanced in the R10 group.

CONCLUSION

The colon mucosa is affected by ten days of gastric restriction in an animal model, increasing neutral mucins, acid mucins and collagen content with trophic maintenance.

A slippery slope: On the origin, role and physiology of mucus

The mucosa of the gastrointestinal tract, eyes, nose, lungs, cervix and vagina is lined by epithelium interspersed with mucus-secreting goblet cells, all of which contribute to their unique functions. This mucus provides an integral defence to the epithelium against noxious agents and pathogens. However, it can equally act as a barrier to drugs and delivery systems targeting epithelial passive and active transport mechanisms. This review highlights the various mucins expressed at different mucosal surfaces on the human body, and their role in creating a mucoid architecture to protect epithelia with specialized functions. Various factors compromising the barrier properties of mucus have been discussed, with an emphasis on how disease states and microbiota can alter the physical properties of mucus. For instance, Akkermansia muciniphila, a bacterium found in higher levels in the gut of lean individuals induces the production of a thickened gut mucus layer. The aims of this article are to elucidate the different physiological, biochemical and physical properties of bodily mucus, a keen appreciation of which will help circumvent the slippery slope of challenges faced in achieving effective mucosal drug and gene delivery.

Gut immunity in a protochordate involves a secreted immunoglobulin-type mediator binding host chitin and bacteria

Protochordate variable region-containing chitin-binding proteins (VCBPs) consist of immunoglobulin-type V domains and a chitin-binding domain (CBD). VCBP V domains facilitate phagocytosis of bacteria by granulocytic amoebocytes; the function of the CBD is not understood. Here we show that the gut mucosa of Ciona intestinalis contains an extensive matrix of chitin fibrils to which VCBPs bind early in gut development, before feeding. Later in development, VCBPs and bacteria colocalize to chitin-rich mucus along the intestinal wall. VCBP-C influences biofilm formation in vitro and, collectively, the findings of this study suggest that VCBP-C may influence the overall settlement and colonization of bacteria in the Ciona gut. Basic relationships between soluble immunoglobulin-type molecules, endogenous chitin and bacteria arose early in chordate evolution and are integral to the overall function of the gut barrier.

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

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.

Some food-associated mycotoxins as potential risk factors in humans predisposed to chronic intestinal inflammatory diseases

Mycotoxins are fungal metabolites able to affect the functions of numerous tissues and organs in animals and humans, including intestinal and immune systems. However, the potential link between exposure to some mycotoxins and human chronic intestinal inflammatory diseases, such as celiac and Crohn's diseases or ulcerative colitis, has not been investigated. Instead, several theories based on bacterial, immunological or neurological events have been elaborated to explain the etiology of these pathologies. Here we reviewed the literature on mycotoxin-induced intestinal dysfunctions and compared these perturbations to the impairments of intestinal functions typically observed in human chronic intestinal inflammatory diseases. Converging evidence based on various cellular and animal studies show that several mycotoxins induce intestinal alterations that are similar to those observed at the onset and during the progression of inflammatory bowel diseases. Although epidemiologic evidence is still required, existing data are sufficient to suspect a role of some food-associated mycotoxins in the induction and/or persistence of human chronic intestinal inflammatory diseases in genetically predisposed patients.

Tissue quantification of neutral and acid mucins in the mucosa of the colon with and without fecal stream in rats

PURPOSE: To quantify the intensity of the expression of neutral and acids mucins in mucosa of the colon with and without fecal stream and to correlate this with the duration of fecal transit diversion. METHODS: Thirty male Wistar rats were subjected to fecal transit deviation in the left colon by a proximal colostomy and a distal mucous fistula. The animals were divided into three experimental groups, according to whether sacrificing would be performed six, 12 or 18 weeks after surgery. The expression of neutral and acid mucins was evaluated using the histochemical techniques of Periodic Acid Schiff and Alcian Blue, respectively. The tissue mucins expression was quantified by computer-assisted image analysis software (NIS-Elements) in the segments with and without fecal stream. Student's paired t test was used to compare the quantities of mucins in colon with or without fecal stream and variance between the experimental groups by ANOVA and Newman-Keuls post-test, establishing level of signification of 5% (p<0.05). RESULTS: There were significant decreased quantities of acid and neutral mucins in the colon without transit, compared with the colon with fecal stream, independent of the duration of exclusion. There was increased expression of neutral mucins in the colon with fecal stream after 12 and 18 weeks of exclusion. There was no increase in the expression of acid mucins in the colon with transit as the duration of fecal transit exclusion progressed. There was increased production of acid mucins in the animals submitted to diversion of the fecal stream for 18 weeks, compared with those subjected to diversion for 6 and 12 weeks. In the colon without fecal stream, there was increased expression of neutral mucins after 12 and 18 weeks of exclusion. CONCLUSIONS: Deviation of the fecal stream decreased the expression of acid and neutral mucins in the segments without fecal transit, compared with segments with transit. Regardless of the reduced expression of acid and neutral mucins in the segments without fecal stream, their tissue expression increased with increasing duration of intestinal deviation.

Sialosyl-Tn antigen: initial report of a new marker of malignant progression in long-standing ulcerative colitis

BACKGROUND & AIMS

Expression of the mucin-associated carbohydrate antigen sialosyl-Tn (STn) correlates with malignant transformation in sporadic colonic neoplasms. The aim of this study was to analyze STn antigen expression in patients with long-standing ulcerative colitis (UC).

METHODS

STn antigen was assessed by immunohistochemistry in archival tissues. Study A was a retrospective chronological case-control study. Serial surveillance colonoscopic biopsy specimens without inflammation or dysplasia were analyzed in 7 patients who developed colon cancer and in 8 controls who did not develop colon cancer. Study B analyzed the anatomic distribution of STn expression in 17 cancer-bearing (case) and 6 cancer-free (control) colectomy specimens from patients with UC. In some colectomy specimens, STn was compared with aneuploidy, which was determined by flow cytometry.

RESULTS

In study A, among the 7 patients with UC who developed cancer, 6 patients (86%) expressed STn in at least one prior nondysplastic surveillance biopsy specimen from the same site. Only 3 of 8 control patients (38%) expressed STn. In study B, STn was expressed in 40 of 82 specimens (49%) from cancer-bearing colons but only 8 of 62 specimens (13%) from cancer-free colons. STn was expressed in most aneuploid areas but was also found in diploid, nondysplastic mucosa.

CONCLUSIONS

STn antigen seems to be a promising marker of cancer risk in patients with UC.

Thickness of adherent mucus gel on colonic mucosa in humans and its relevance to colitis

The thickness of adherent mucus gel on the surface of colonic mucosa was measured in surgically resected specimens from 46 'control' patients most of whom had carcinoma of the colon; 12 were from right colon, 17 left colon, and 21 from rectum. In addition specimens were examined from 17 patients with ulcerative colitis and 15 patients with Crohn's disease. In controls a continuous layer of mucus was readily seen on specially prepared sections viewed by phase contrast illumination. Mean values for right and left colon and rectum were 107 (48), 134 (68), and 155 (54) microns respectively with a significant difference between right colon and rectum (p = 0.015). Values in ulcerative colitis showed greater variation and in those areas with acute inflammation mucosa was denuded of the mucus layer. In contrast, values for Crohn's disease were normal or greater than normal in thickness--right colon 190 (83) microns compared with 107 48 microns, p = 0.0093. A series of validation experiments are described for the method used to measure mucus thickness. The possible role of mucus in the pathogenesis of inflammatory bowel disease is discussed.

Mucin profiles in ulcerative colitis with dysplasia and carcinoma

Mucin secretion was assessed in Crohn's colitis, in ulcerative colitis with regeneration, dysplasia and carcinoma and in non-colitic adenocarcinoma. The high iron diamine-alcian blue (HID-AB) and periodate borohydride-saponification periodic acid Schiff (PB-KOH-PAS) techniques were used to demonstrate sulphomucins and sialomucins, and O-acylated sialomucins respectively. There was mucosal hyperplasia and increased sialomucin secretion in Crohn's disease, quiescent and active ulcerative colitis. In colitis with carcinoma inflamed mucosa away from the tumour had increased sialomucins as had colitis with dysplasia. They did not differ statistically from each other or from colitic controls without cancer. Dysplastic crypts frequently secreted sulphomucins and the increased sialomucins were in transitional-like glands in the surface fronds or adjacent to the dysplasia. A comparative study of the HID-AB technique gave total correct qualitative allocation of individual quantitatively assessed crypts. Routine HID-AB staining did not aid the recognition of dysplasia in ulcerative colitis. With the PB-KOH-PAS technique colorectal adenocarcinoma showed a significant diminution in O-acylated sialomucins compared with its adjacent mucosa. Mucosal dysplasia in ulcerative colitis displayed a similar trend in O-acylated sialic acid variants, differing with respect to age-and sex-matched colitic controls. The PB-KOH-PAS technique may be of help in assessing mucin secretion in ulcerative colitis as a guide to the evolution of malignancy.

Mucin abnormality of colonic mucosa in ulcerative colitis associated with carcinoma and/or dysplasia

Twenty cases of resected specimens of carcinoma and/or dysplasia complicating ulcerative colitis were histochemically investigated by the periodic acid-thionein Schiff/potassium hydroxide/periodic acid-Schiff (PAT/KOH/PAS) staining method to see mucin characteristics of carcinoma, dysplasia, and the background mucosa of these lesions. As a control, 11 resected specimens of ulcerative colitis without dysplastic changes and 26 specimens of colonic carcinoma were examined also. All dysplasia and carcinoma in ulcerative colitis stained blue, whereas normal colonic mucin stained red in 65 percent. In 14 of 20 specimens with carcinoma and/or dysplasia, the background mucosa appeared normal with hematoxylin and eosin staining, but showed a mosaic staining pattern with PAT/KOH/PAS. However, only two of 11 specimens of ulcerative colitis without dysplasia and none of 26 specimens of flat mucosa with colorectal carcinoma showed a mosaic staining pattern. From these observations it was concluded that the PAT/KOH/PAS staining method could be useful as a histochemical marker of premalignant change in longstanding ulcerative colitis.

Influence of sialomucin at the resection margin on local tumour recurrence and survival of patients with colorectal cancer: a multivariate analysis

In a multicentre prospective trial 358 patients undergoing curative surgery for colorectal cancer were followed for a median 18.0 months (+/- 7.2 months). The presence or absence of sialomucin in either resection margin was studied using the high iron diamine-alcian blue stain. There was evidence of excess sialomucin at one or other resection margin in 106 patients (29.6 per cent). Apart from sigmoid carcinomas occurring more often in the sialomucin positive group, there were no significant differences in any histological or clinical parameters between groups. Survival analysis for the events 'death', 'local recurrence', and 'all recurrence' was undertaken using the Cox regression model. The best prognostic variables selected in a stepwise fashion for death and all recurrence were 'Dukes' classification', 'sialomucin present' and 'histological differentiation'. The best prognostic variables selected for local recurrence were 'sialomucin present', 'Dukes' classification' and 'histological differentiation'. Sialomucin in a resection margin is an important independent prognostic variable for the development of local tumour recurrence and of subsequent survival for patients with colorectal carcinoma.