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Infection and Immunity, February 2003, p. 766-773, Vol. 71, No. 2
0019-9567/03/$08.00+0     DOI: 10.1128/IAI.71.2.766-773.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.

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

Stephanie Dahan,1 Guillaume Dalmasso,1 Veronique Imbert,2 Jean-Francois Peyron,2 Patrick Rampal,1 and Dorota Czerucka1*

Laboratoire de Gastroentérologie et Nutrition,1 INSERM U526 Activation des Cellules Hématopoïétiques, IFR50, Faculté de Médecine, Université de Nice-Sophia Antipolis, 06107 Nice Cedex 2, France2

Received 15 May 2002/ Returned for modification 5 July 2002/ Accepted 15 November 2002

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-{kappa}B 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-{kappa}B DNA binding activity, phosphorylation and degradation of I{kappa}B-{alpha}, 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-{kappa}B and MAPK signaling pathways in infected T84 cells.


* Corresponding author. Mailing address: Laboratoire de Gastroentérologie, Université de Nice-Sophia Antipolis, 28 avenue de Valombrose, 06107 Nice Cedex 2, France. Phone: (33) 4 93 37 76 95. Fax: (33) 4 93 81 77 10. E-mail: czerucka{at}unice.fr.

Editor: S. H. E. Kaufmann


Infection and Immunity, February 2003, p. 766-773, Vol. 71, No. 2
0019-9567/03/$08.00+0     DOI: 10.1128/IAI.71.2.766-773.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.




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