Rôles physiologiques des mucines dans la barrière colique

Phytochemical Properties of Crataegus azarolus Berries Decoction Extract and Evaluation of its Protective Activity Against Acetic Acid-Induced Ulcerative Colitis in Rats

The present study aims to evaluate the protective effect of Crataegus azarolus berries decoction extract (CAB-DE) against acetic acid-induced ulcerative colitis as well as the mechanisms implicated in such protection. Adult male Wistar rats were separated into seven groups: Control (H2O), acetic acid (AA), AA + various doses of CAB-DE (100, 200, and 400 mg/kg, b.w.,p.o.), and AA + sulfasalazine (100 mg/kg, b.w.,p.o.) or gallic acid (50 mg/kg, b.w.,p.o.) during 10 days. All rats were kept fasting overnight and ulcerative colitis was induced by rectal infusion of AA (300 mg kg-1, b.w.) (3%, v/v, 5 mL kg-1 b.w), for 30 s. The colon was rapidly excised and macroscopically examined to measure ulcerated surfaces and the ulcer index. In vitro, we found that CAB-DE exhibited a high antioxidant activity against DPPH radical (IC50 = 164.17 ± 4.78 μg/mL). In vivo, pretreatment with CAB-DE significantly protected the colonic mucosa against AA-induced damage by stimulating mucus secretion, reducing ulcer index as well as histopathological changes. Also, CAB-DE limited the oxidative status induced by AA in the colonic mucosa, as assessed by MDA and H2O2 increased levels and the depletion of both enzymatic activities and non-enzymatic levels. In addition, AA intoxication increased iron and calcium levels in colonic mucosa and plasma, while CAB-DE pretreatment regulated all intracellular mediators deregulation and significantly reduced inflammatory markers such as CRP (1.175 ± .04 ─ .734 ± .06 μg/dl) and ALP (161.53 ± 5.02 ─ 98.60 ± 4.21 UI/L) levels. We suggest that CAB-DE protected against AA-induced ulcerative colitis due in part to its antioxidant and anti-inflammatory properties.

Refined sorghum flours precooked by extrusion enhance the integrity of the colonic mucosa barrier and promote a hepatic antioxidant environment in growing Wistar rats

The effects of precooked-refined sorghum flour consumption on antioxidant status, lipid profile, and colonic and bone health were evaluated. Twenty-four male Wistar rats were fed with control diet (C), or red or white precooked-refined sorghum based diets (SD) for 60 days. The intake of SD was lower than that of C, but the efficiency of all diets was similar. Rats fed with SD showed lower feces excretion, cecal pH and enzyme activities (β-glucosidase, β-glucuronidase and mucinase) than C. White SD improved intestinal architecture, cell proliferation and apoptosis, upregulated ZO1 and occludin tight junction proteins and stimulated goblet cell differentiation, enhancing the integrity of the mucosa barrier in both proximal and distal colonic mucosa in a better way than red SD. Consumption of SD significantly decreased serum triglyceride levels compared with the C diet. The mineral content of the right femur was not different among diets. The liver enzyme activities (superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase) did not show differences among diets. Liver reducing power and reduced glutathione/oxidize glutathione ratio were higher for animals consuming SD than C. It can be concluded that the consumption of precooked refined sorghum flours still has beneficial effects for health, mainly at the colonic level, despite the lower phenolics and fibre contents of refined flours with respect to whole grain flours.

Age-related histochemical investigations of small intestinal goblet cells in bronze turkeys (Meleagris gallopavo gallopavo)

The aim of the study was to investigate the goblet cell types and their density in the small intestine of bronze turkey (Meleagris meleagris gallopovo), by means of Alcian blue-PAS staining. Sixty birds from 10 age groups were used. In the duodenum and jejunum, goblet cells produced acid, neutral and mixed mucins, while in the jejunum - acid mucins. A negative relationship was observed between cell density and either duodenum or jejunum lengths; such a correlation was not established in the ileum.

EVALUATION OF ENEMAS CONTAINING SUCRALFATE IN TISSUE CONTENT OF MUC-2 PROTEIN IN EXPERIMENTAL MODEL OF DIVERSION COLITIS

BACKGROUND

The effects of topical application of sucralfate (SCF) on the tissue content of MUC-2 protein have not yet been evaluated in experimental models of diversion colitis.

AIM

To measure the tissue content of MUC-2 protein in the colonic mucosa diverted from fecal stream submitted to the SCF intervention.

METHODS

Thirty-six rats underwent derivation of intestinal transit through proximal colostomy and distal mucous fistula. The animals were divided into three groups which were submitted application of enemas with saline, SCF 1 g/kg/day and SCF 2 g/kg/day. Each group was divided into two subgroups, according to euthanasia was done after two or four weeks. The colitis diagnosis was established by histopathological study and the inflammatory intensity was evaluated by previously validated scale. The MUC-2 protein was identified by immunohistochemistry and the tissue content was measured computerized morphometry).

RESULTS

The application of enemas with SCF in the concentration of 2 g/kg/day reduced inflammatory score of the segments that were diverted from fecal stream. The content of MUC-2 in diverted colon of the animals submitted to the intervention with SCF, independently of intervention period and the used concentration, was significantly greater than animals submitted to the application of enemas containing saline (p< 0.01). The content of MUC-2 after the intervention with SCF in the concentration of 2 g/kg/day was significantly higher when compared to the animals submitted to the application containing SCF at concentration of 1.0 g/kg/day (p<0.01). The tissue content of MUC-2 reached the highest values after intervention with SCF in the concentration of 2 g/kg/day for four weeks (p<0.01).

CONCLUSION

The preventive application of enemas containing SCF reduces the inflammatory score and avoids the reduction of tissue content of MUC-2, suggesting that the substance is a valid therapeutic strategy to preserve the mucus layer that covers the intestinal epithelium.

EVALUATION OF ENEMAS CONTAINING SUCRALFATE IN TISSUE CONTENT OF MUC-2 PROTEIN IN EXPERIMENTAL MODEL OF DIVERSION COLITIS

BACKGROUND

The effects of topical application of sucralfate (SCF) on the tissue content of MUC-2 protein have not yet been evaluated in experimental models of diversion colitis.

AIM

To measure the tissue content of MUC-2 protein in the colonic mucosa diverted from fecal stream submitted to the SCF intervention.

METHODS

Thirty-six rats underwent derivation of intestinal transit through proximal colostomy and distal mucous fistula. The animals were divided into three groups which were submitted application of enemas with saline, SCF 1 g/kg/day and SCF 2 g/kg/day. Each group was divided into two subgroups, according to euthanasia was done after two or four weeks. The colitis diagnosis was established by histopathological study and the inflammatory intensity was evaluated by previously validated scale. The MUC-2 protein was identified by immunohistochemistry and the tissue content was measured computerized morphometry).

RESULTS

The application of enemas with SCF in the concentration of 2 g/kg/day reduced inflammatory score of the segments that were diverted from fecal stream. The content of MUC-2 in diverted colon of the animals submitted to the intervention with SCF, independently of intervention period and the used concentration, was significantly greater than animals submitted to the application of enemas containing saline (p< 0.01). The content of MUC-2 after the intervention with SCF in the concentration of 2 g/kg/day was significantly higher when compared to the animals submitted to the application containing SCF at concentration of 1.0 g/kg/day (p<0.01). The tissue content of MUC-2 reached the highest values after intervention with SCF in the concentration of 2 g/kg/day for four weeks (p<0.01). Conclusion: The preventive application of enemas containing SCF reduces the inflammatory score and avoids the reduction of tissue content of MUC-2, suggesting that the substance is a valid therapeutic strategy to preserve the mucus layer that covers the intestinal epithelium.

Function of the intestinal epithelium and its dysregulation in inflammatory bowel disease

The intestinal epithelium not only acts as a physical barrier to commensal bacteria and foreign antigens but is also actively involved in antigen processing and immune cell regulation. The inflammatory bowel diseases (IBDs) are characterized by inflammation at this mucosal surface with well-recognized defects in barrier and secretory function. In addition to this, defects in intraepithelial lymphocytes, chemokine receptors, and pattern recognition receptors promote an abnormal immune response, with increased differentiation of proinflammatory cells and a dysregulated relationship with professional antigen-presenting cells. This review focuses on recent developments in the structure of the epithelium, including a detailed account of the apical junctional complex in addition to the role of the enterocyte in antigen recognition, uptake, processing, and presentation. Recently described cytokines such as interleukin-22 and interleukin-31 are highlighted as is the dysregulation of chemokines and secretory IgA in IBD. Finally, the effect of the intestinal epithelial cell on T effector cell proliferation and differentiation are examined in the context of IBD with particular focus on T regulatory cells and the two-way interaction between the intestinal epithelial cell and certain immune cell populations.

Flagellin: key target of mucosal innate immunity

The mucosal immune system is charged with defending the host's vast interfaces with the outside world from the enormous and diverse group of microbes that colonizes these surfaces. A key means by which the mucosal immune system protects the host from such diverse microbes is using germ-line-encoded receptors that target structurally conserved motifs that mediate important bacterial functions. This review focuses on one embodiment of this notion, namely, the mucosal innate immune targeting of flagellin, the primary structural component of flagella, which afford bacteria the ability of directed locomotion. Specifically, we discuss the mechanisms by which flagellin is recognized by the innate immune system, their role in host defense, chronic inflammatory disease, and potential approaches to pharmacologically manipulate these pathways to benefit the host. Discussion will focus on the intestinal tract but will also incorporate key findings in other mucosal surfaces.