RESUMO
BACKGROUND: Intestinal permeability is altered in a subgroup of irritable bowel syndrome (IBS) patients and may contribute to symptom development. The aim of this study was to evaluate the in vitro effect of the probiotic Escherichia coli Nissle 1917 (EcN) on Caco-2 permeability alterations induced by mediators released by IBS mucosal biopsies compared to asymptomatic controls (AC). METHODS: Caco-2 cells were used as an in vitro model of intestinal permeability. Seven AC and 28 well-phenotyped IBS (9 IBS-D, 8 IBS-C, and 11 IBS-M) patients were enrolled. Mucosal mediators spontaneously released (SUP) by IBS and AC biopsies were collected. Two concentrations of EcN (108 and 106 ) were applied to Caco-2 with or without SUP or SLIGRL (a protease-activated receptor-2 activating peptide), tumor necrosis factor-α, and interferon-γ. Paracellular permeability was assessed by evaluating the flow of sulfonic-acid conjugated to fluorescein through Caco-2 monolayer. KEY RESULTS: EcN 108 significantly reinforced Caco-2 monolayer compared to cells incubated with medium alone. IBS SUP induced a significant increase in paracellular permeability compared to AC SUP, independently of IBS bowel habit. EcN 108 induced a significant recovery of permeability rate compared to IBS SUP. Permeability increase induced by IBS SUP significantly correlated with severity and frequency of abdominal pain and abdominal distension. The co-incubation of EcN and IBS SUP abolished the above significant correlations. CONCLUSIONS AND INFERENCES: EcN reinforces the integrity of Caco-2 monolayer and reverts the increase of permeability induced by mediators released by IBS biopsies. Future studies should investigate EcN therapeutic potentials in IBS.
RESUMO
BACKGROUND: Mediators released in the mucosal milieu have been suggested to be involved in visceral hypersensitivity and abdominal pain in patients with irritable bowel syndrome (IBS). However, their impact on myenteric neurons remains unsettled. METHODS: Mucosal biopsies were obtained from the descending colon of patients with IBS and controls. Mucosal mast cells were identified immunohistochemically. The impact of spontaneously released mucosal mediators on guinea pig electrically stimulated longitudinal muscle myenteric plexus (LMMP) preparations was assessed in vitro by means of selective receptor antagonists and inhibitors. KEY RESULTS: Patients with IBS showed an increased mast cell count compared with controls. Application of mucosal mediators of IBS to LMMPs potentiated cholinergic twitch contractions, an effect directly correlated with mast cell counts. Enhanced contractions were inhibited by 50.3% with the prostaglandin D2 antagonist BW A868C, by 31.3% and 39% with the TRPV1 antagonists capsazepine and HC-030031, respectively, and by 60.5% with purinergic P2X antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid. Conversely, the serotonin1-4, histamine1-3, tachykinin1-3 receptor blockade, and serine protease inhibition had no significant effect. CONCLUSIONS & INFERENCES: Colonic mucosal mediators from patients with IBS excite myenteric cholinergic motor neurons. These effects were correlated with mast cell counts and mediated by activation of prostanoid receptors, TRPV1, and P2X receptors. These results support the role of mucosal inflammatory mediators and mast cell activation in altered motor function of IBS.
