Patrick Rampal

Saccharomyces boulardii preserves the barrier function and modulates the signal transduction pathway induced in enteropathogenic Escherichia coli-infected T84 cells.

ABSTRACT Use of the nonpathogenic yeast Saccharomyces boulardiiin the treatment of infectious diarrhea has attracted growing interest. The present study designed to investigate the effect of this yeast on enteropathogenic Escherichia coli (EPEC)-associated disease demonstrates that S. boulardii abrogated the alterations induced by an EPEC strain on transepithelial resistance, [3H]inulin flux, and ZO-1 distribution in T84 cells. Moreover, EPEC-mediated apoptosis of epithelial cells was delayed in the presence of S. boulardii. The yeast did not modify the number of adherent bacteria but lowered by 50% the number of intracellular bacteria. Infection by EPEC induced tyrosine phosphorylation of several proteins in T84 cells, including p46 and p52 SHC isoforms, that was attenuated in the presence of S. boulardii. Similarly, EPEC-induced activation of the ERK1/2 mitogen-activated protein (MAP) kinase pathway was diminished in the presence of the yeast. Interestingly, inhibition of the ERK1/2 pathway with the specific inhibitor PD 98059 decreased EPEC internalization, suggesting that modulation of the ERK1/2 MAP pathway might account for the lowering of the number of intracellular bacteria observed in the presence of S. boulardii. Altogether, this study demonstrated that S. boulardii exerts a protective effect on epithelial cells after EPEC adhesion by modulating the signaling pathway induced by bacterial infection.

The putative role of inflammation in the irritable bowel syndrome

The irritable bowel syndrome (IBS) may be defined as a painful chronic abdominal symptom complex which is usually associated with altered bowel habit, and for which there is no discernible underlying structural abnormality. It is generally accepted that symptoms are generated by abnormalities of gut function, including altered sensory perception, abnormal motility and, in some patients, abnormalities of epithelial function. Behavioural factors are important, particularly in the reporting of symptoms. What is lacking is an understanding of the pathogenetic mechanisms that alter gut function. IBS is a heterogeneous condition, not only in its clinical presentation and pathophysiology, but also in terms of its pathogenesis. While both central and peripheral factors have been implicated in the pathogenesis of IBS, this article will restrict itself to an evaluation of the evidence supporting inflammation as a basis for altered gut function in IBS. In considering the role of inflammation in IBS, one is prompted to make a comparison with asthma. Like IBS, asthma was once considered a psychosomatic disorder, particularly in non-atopic children. For more than 50 years the treatment of asthma focused on the pharmacological correction of abnormal end organ physiology (that is, airways hyperresponsiveness), an approach that is similar to current therapeutic approaches to IBS, and which are aimed at modulating motor activity or sensory perception. The subsequent discovery of inflammatory cells in the normally sterile broncheoalveolar lavage led to the recognition of asthma as an inflammatory condition. There are two reasons why a similar shift in thinking in IBS will be difficult. Firstly, the gut is normally in a state of controlled inflammation and the challenge of identifying a subtle increase in inflammatory cell number or composition is not to be underestimated. Secondly, IBS is intuitively more heterogeneous than asthma, and inflammation is unlikely to be a factor in all …

Experimental effects of Saccharomyces boulardii on diarrheal pathogens

Saccharomyces boulardii is a selected strain of yeast that may have applications in the prevention and treatment of intestinal infections. The animal models and in vitro studies developed to elucidate the mechanisms of this protection are reviewed and discussed.

Saccharomyces boulardii Interferes with Enterohemorrhagic Escherichia coli-Induced Signaling Pathways in T84 Cells

ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) infections are associated with the modification of tight-junction permeability and synthesis of proinflammatory cytokine interleukin-8 (IL-8). In a previous study, it was demonstrated that EHEC-induced IL-8 secretion is due to the involvement of the mitogen-activated protein kinase (MAPK), AP-1, and NF-κB pathways. In this study, we investigated the effect of the yeast Saccharomyces boulardii on EHEC infection in T84 cells. For this purpose, cells were (i) incubated with bacteria and yeast at the same time or (ii) incubated overnight with yeast cells that were maintained during infection or eliminated by several washes before infection. Coincubation is sufficient to maintain the transmonolayer electrical resistance (TER) of EHEC-infected cells, whereas the preincubation of cells with the yeast without elimination of the yeast during infection is necessary to significantly decrease IL-8 secretion. We thus analyzed the mechanisms of S. boulardii action. We showed that S. boulardii has no effect on EHEC growth or on EHEC adhesion. Kinetics studies revealed that EHEC-induced myosin light chain (MLC) phosphorylation precedes the decrease of TER. ML-7, an MLC kinase inhibitor, abolishes the EHEC-induced MLC phosphorylation and decrease of TER. Studies show that S. boulardii also abolishes EHEC-induced MLC phosphorylation. We demonstrated that the preincubation of cells with S. boulardii without washes before EHEC infection inhibits NF-κB DNA binding activity, phosphorylation and degradation of IκB-α, and activation of the three members of a MAPK group (extracellular signal-regulated protein kinases 1 and 2, p38, and c-jun N-terminal kinase). These findings demonstrate that S. boulardii exerts a preventive effect on EHEC infection by (i) interfering with one of the transduction pathways implicated in the control of tight-junction structure and (ii) decreasing IL-8 proinflammatory secretion via inhibition of the NF-κB and MAPK signaling pathways in infected T84 cells.

Enterohemorrhagic Escherichia coli Infection Induces Interleukin-8 Production via Activation of Mitogen-Activated Protein Kinases and the Transcription Factors NF-κB and AP-1 in T84 Cells

ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) infections are associated with hemorrhagic colitis and the hemolytic-uremic syndrome (HUS). In vivo, elevated plasma levels of the proinflammatory cytokine interleukin-8 (IL-8) in EHEC-infected children are correlated with a high risk of developing HUS. As IL-8 gene transcription is regulated by the transcription factors NF-κB and AP-1, we analyzed the role of these factors in the regulation of IL-8 production after infection of the epithelial intestinal T84 cell line by EHEC. By 6 h of infection, EHEC had induced significant secretion of IL-8 (35.84 ± 6.76 ng/ml versus 0.44 ± 0.04 ng/ml in control cells). EHEC induced AP-1 and NF-κB activation by 3 h of infection. Moreover, the three mitogen-activated protein kinases (MAPK) (ERK1/2, p38, and JNK) were phosphorylated in EHEC-infected T84 cells concomitant with induction of AP-1 DNA binding activity, and IκB-α was phosphorylated and then degraded concomitant with induction of NF-κB DNA binding activity. Pretreatment of cells with the highly specific MEK1/2 inhibitor U0126, the p38 inhibitor SB203580, and/or the proteasome inhibitor ALLN led to inhibition of the IL-8 secretion induced in EHEC-infected T84 cells. These findings demonstrate that (i) EHEC can induce in vitro a potent proinflammatory response by secretion of IL-8 and (ii) the secretion of IL-8 is due to the involvement of MAPK, AP-1, and NF-κB signaling pathways.

Endoscopic bilateral metal stent placement for malignant hilar stenoses: identification of optimal technique ☆

BACKGROUND The aim of this study was to identify factors that facilitate bilateral insertion of metal stents in malignant hilar stenoses, for which plastic stents often result in incomplete drainage and subsequent cholangitis. METHODS Between January 1994 and April 1998, we collected 45 cases of advanced (Bismuth stage II or higher) hilar malignant stenoses. The insertion technique was progressively modified and the success rate in the early period (1994 to 1995) was compared with that of a later period (1996) and the most recent period (1997 to 1998). RESULTS Overall success rate was 73.3% (33 of 45). The success rates for the three periods were 50%, 67%, and 88% (p = 0.008), respectively. Cholangitis occurred in 3 of the patients with unilateral stents compared with 1 with bilateral stents. CONCLUSION We have described a technique for endoscopic insertion of bilateral metallic stents for malignant hilar stenoses that results in high (>88%) and reproducible success rates.

Chondrex (YKL-40), a potential new serum fibrosis marker in patients with alcoholic liver disease

Objectives Chondrex (YKL‐40) is a mammalian member of a protein family that includes bacterial chitinases. The pattern of its expression in certain tissues such as human liver or cartilage suggests a function in remodelling or degradation of extracellular matrix. The purpose of this study was to assess whether circulating YKL‐40 might be a serum fibrosis marker in alcoholics. Methods Plasma YKL‐40 was determined in 146 consecutive heavy drinkers (106 men, 40 women; mean age, 49.2 ± 9.0 years). Liver biochemical parameters and serum fibrosis markers such as hyaluronate were also measured. Fibrosis and inflammation in liver biopsy were evaluated using a semi‐quantitative scoring system. Results Plasma YKL‐40 increased in parallel with the severity of fibrosis (P < 0.00001). YKL‐40 also increased in the presence of hepatic inflammation (P < 0.01). Receiver operating characteristic curves of Chondrex revealed that a threshold of 330 μg/E gave a specificity of 88.5%; however, the sensitivity was only 50.8%. Only 11.5% of patients without severe fibrosis displayed a Chondrex plasma level above this threshold. A positive correlation was found between Chondrex and hyaluronate (r = 0.40, P < 0.0001), and a negative correlation was shown between Chondrex and the prothrombin index (r = −0.37, P < 0.0001). Conclusions The severity of liver fibrosis is associated with elevated circulating Chondrex levels. The overlap in YKL‐40 values prevents use of Chondrex in a screening programme. High levels of Chondrex (above 330 μg/E) are predictive of severe liver fibrosis. Increased plasma YKL‐40 may reflect the remodelling of liver fibrosis in alcoholics. Eur J Gastroenterol Hepatol 12:989‐993

Effect of ondansetron, a 5-HT3 receptor antagonist, on fatigue in chronic hepatitis C: a randomised, double blind, placebo controlled study

Background and aims: There are no available effective therapies for fatigue associated with chronic hepatitis C (CHC). The serotonin antagonist ondansetron has been shown to be effective in the chronic fatigue syndrome. In this randomised, placebo controlled, double blind trial, we investigated the effect of orally administered ondansetron on fatigue in CHC. Methods: Thirty six patients with CHC were included if fatigue was their predominant symptom and they scored more than 4 on a visual analogue scale (0–10). During the study, fatigue and depression were measured on days 0, 15, 30, and 60 using a validated self report questionnaire (fatigue impact scale and Beck depression inventory). Patients were randomised to receive ondansetron tablets 4 mg twice daily or placebo for one month followed by an additional four weeks of observation. Results: Fatigue score was 85.4 (28.2) and 98.2 (26.9) in the ondansetron and placebo groups, respectively (NS). Ondansetron significantly reduced the fatigue score with more than 30% improvement on day 15 (57.1 (38.9); p<0.01), day 30 (54.5 (37.6); p<0.01), and day 60 (60.8 (37.3); p<0.01) whereas placebo did not. Overall, the reduction in fatigue was significantly higher with ondansetron compared with placebo (ANOVA for repeated measurements) for the whole follow up period (p = 0.03) or for the treatment period only (p = 0.04). Ondansetron also significantly reduced depression scores. Conclusions: The 5-hydroxytryptamine receptor type 3 antagonist ondansetron had a significant positive effect on fatigue in CHC. These observations support the concept that fatigue involves serotoninergic pathways and may encourage further evaluations of the efficacy of ondansetron on fatigue in chronic liver diseases.

Implication of mitogen-activated protein kinases in T84 cell responses to enteropathogenic Escherichia coli infection.

ABSTRACT Enteropathogenic Escherichia coli (EPEC) infection of T84 cells induces a decrease in transepithelial resistance, the formation of attaching and effacing (A/E) lesions, and cytokine production. The purpose of this study was to investigate the ability of EPEC to activate mitogen-activated protein (MAP) kinases in T84 cells and to correlate these signaling pathways with EPEC-induced cell responses. T84 cells were infected with either the wild-type (WT) EPEC strain E2348/69 or two mutants, intimin deletion strain CVD206 (ΔeaeA) and type III secretion apparatus mutant strain CVD452 (ΔescN::aphA). Infection of T84 cells with WT but not mutant EPEC strains induced tyrosine phosphorylation of several proteins in T84 cells, including the p46 and p52 Shc isoforms. Kinetics studies revealed that ERK1/2, p38, and c-Jun N-terminal kinase (JNK) MAP kinases were activated in cells infected with strain E2348/69 but not with the mutant strains. Inhibition of MAP kinases with PD98059 or SB203580 did not affect the EPEC-induced decrease in transepithelial resistance or actin accumulation beneath the WT bacteria, but these two inhibitors significantly decreased interleukin-8 (IL-8) synthesis. We demonstrate that EPEC induces activation of ERK1/2, p38, and JNK cascades, which all depend on bacterial adhesion and expression of the bacterial type III secretion system. ERK1/2 and p38 MAP kinases were equally implicated in IL-8 expression but did not participate in A/E lesion formation or transepithelial resistance modification, indicating that the signaling pathways involved in these events are distinct.

Saccharomyces boulardii does not prevent relapse of Crohn's disease.

BACKGROUND & AIMS Saccharomyces boulardii is a probiotic yeast that has been shown to have beneficial effects on the intestinal epithelial barrier and digestive immune system. There is preliminary evidence that S boulardii could be used to treat patients with Crohns disease (CD). We performed a randomized, placebo-controlled trial to evaluate the effects of S boulardii in patients with CD who underwent remission during therapy with steroids or aminosalicylates. METHODS We performed a prospective study of 165 patients who achieved remission after treatment with steroids or salicylates; they were randomly assigned to groups given S boulardii (1 g/day) or placebo for 52 weeks. The primary end point was the percentage of patients in remission at week 52. Time to relapse, Crohns disease activity index scores, and changes in parameters of inflammation were secondary end points. RESULTS CD relapsed in 80 patients, 38 in the S boulardii group (47.5%) and 42 in the placebo group (53.2%, a nonsignificant difference). The median time to relapse did not differ significantly between patients given S boulardii (40.7 weeks) vs placebo (39.0 weeks). There were no significant differences between groups in mean Crohns disease activity index scores or erythrocyte sedimentation rates or in median levels of C-reactive protein. In a post hoc analysis, nonsmokers given S boulardii were less likely to experience a relapse of CD than nonsmokers given placebo, but this finding requires confirmation. CONCLUSIONS Although the probiotic yeast S boulardii is safe and well tolerated, it does not appear to have any beneficial effects for patients with CD in remission after steroid or salicylate therapies.