Early enterocyte responses to enteropathogenic E. coli

Multiple Mechanisms of Flaxseed: Effectiveness in Inflammatory Bowel Disease

Materials and Methods

Aqueous-methanolic crude extracts of Flaxseed (Fs.Cr) and Flaxseed oil were tested against 6% acetic acid- (AA-) induced colitis in BALB/c mice. Microscopic damage parameters of the hematoxylin and eosin-stained and periodic acid-Schiff-alcian blue-stained sections of the colon were scored to be assessed. Possible antispasmodic mechanism was studied on isolated rabbit jejunum, while antibacterial activity was assessed in vitro for microbes implicated in IBD.

Results

In AA-induced colitis, Flaxseed oil was found to be more effective in reducing mortality and colonic ulcers than Fs.Cr at 500 mg/kg dose. Fs.Cr was more efficacious in increasing mucin content as compared to oil, exhibiting slightly greater anti-inflammatory effect (50% vs 35%) and reducing depth of lesion (55% vs 42.31%, respectively). Antispasmodic activity of Fs.Cr (0.03 and 0.1 mg/ml) was mediated by phosphodiesterase inhibitors (PDEI, possibly PDE-4 subtype) with a resultant increase in cAMP levels. Flaxseed oil PDEI activity was mild (1 and 3 mg/ml). Fs.Cr (0.1 and 0.3 mg/ml) was potent in exhibiting anticholinergic activity, similar to dicyclomine, whereas Flaxseed oil showed anticholinergic effect at 1 and 3 mg/ml. Flaxseed oil (9 and 14 µg/ml) was bactericidal against enteropathogenic E.coli (EPEC), enterotoxigenic E.coli (ETEC), and enteroaggregative E.coli (EAEC), whereas Fs.Cr exhibited bactericidal effect against EPEC at 100 µg/ml.

Conclusions

Results of this study, taken together with previous studies, suggest that Flaxseed possesses anti-inflammatory, antibacterial, and antispasmodic action through multiple pathways and thus offers promising potential to be developed for IBD.

[Recent advances in Saccharomyces boulardii research]

This review summarizes the probiotic mechanisms of action of Saccharomyces boulardii (S. boulardii) against inflammatory and non-inflammatory diarrheal conditions. S. boulardii is distributed in lyophilized form in many countries and used for the prevention of diarrhea in children and adults, including Clostridium difficile (C. difficile) associated infection. The main mechanisms of action of S. boulardii include inhibition of activities of bacterial pathogenic products, trophic effects on the intestinal mucosa, as well as modification of host signaling pathways involved in inflammatory and non-inflammatory intestinal diseases. S. boulardii inhibits production of pro-inflammatory cytokines by inhibiting main regulators of inflammation, including nuclear factor κB (NF-κB), and mitogen-activated protein kinases (MAP kinases), ERK1/2 and p38, but stimulates production of anti-inflammatory molecules such as peroxisome proliferator-activated receptor-gamma (PPAR-γ). Moreover, S. boulardii suppresses bacterial infection by inhibiting adhesion and/or overgrowth of bacteria, produces a serine protease that cleaves C. difficile toxin A, and stimulates antibody production against this toxin. Furthermore, S. boulardii may interfere with pathogenesis of Inflammatory Bowel Disease (IBD) by acting on T cells and acts in diarrheal conditions by improving the fecal biostructure in patients with diarrhea. These diverse mechanisms exerted by S. boulardii provide molecular clues for its effectiveness in diarrheal diseases and intestinal inflammatory conditions with an inflammatory component.

Review article: anti-inflammatory mechanisms of action of Saccharomyces boulardii

BACKGROUND

Saccharomyces boulardii, a well-studied probiotic, can be effective in inflammatory gastrointestinal diseases with diverse pathophysiology, such as inflammatory bowel disease (IBD), and bacterially mediated or enterotoxin-mediated diarrhoea and inflammation.

AIM

To discuss the mechanisms of action involved in the intestinal anti-inflammatory action of S. boulardii.

METHODS

Review of the literature related to the anti-inflammatory effects of this probiotic.

RESULTS

Several mechanisms of action have been identified directed against the host and pathogenic microorganisms. S. boulardii and S. boulardii secreted-protein(s) inhibit production of proinflammatory cytokines by interfering with the global mediator of inflammation nuclear factor kappaB, and modulating the activity of the mitogen-activated protein kinases ERK1/2 and p38. S. boulardii activates expression of peroxisome proliferator-activated receptor-gamma (PPAR-gamma) that protects from gut inflammation and IBD. S. boulardii also suppresses 'bacteria overgrowth' and host cell adherence, releases a protease that cleaves C. difficile toxin A and its intestinal receptor and stimulates antibody production against toxin A. Recent results indicate that S. boulardii may interfere with IBD pathogenesis by trapping T cells in mesenteric lymph nodes.

CONCLUSIONS

The multiple anti-inflammatory mechanisms exerted by S. boulardii provide molecular explanations supporting its effectiveness in intestinal inflammatory states.