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Facteurs de virulence de Escherichia coli adhérents et invasifs associés à la maladie de Crohn : caractérisation et régulation de leur expression

Abstract : Crohn's disease (CD) is a chronic inflammatory disorder of the digestive tract whose etiology remains unclear. The ileal lesions of patients with CD is abnormally colonized by pathogenic strains of Escherichia coli belonging to the AIEC pathovar to Adherent-Invasive E. coli. These strains adhering strongly and invade intestinal epithelial cells. They are also able to grow strongly in macrophages and induce a higher secretion of TNF-α. The objective of this work is to analyze the control systems of the AIEC LF82 reference involved in maximal expression of virulence within the intestinal lumen and / or intracellular conditions. We studied the co-regulation of expression of type 1 pili and flagella starting from the observation that a mutant no longer expressing flagella concomitantly loses its ability to synthesize type 1 pili. We have shown that this co-complex regulation involves the intracellular concentration of di-cyclic GMP and histone-like protein Fis. These systems allow transcriptional regulation of maximal expression of type 1 pili, which in intestinal conditions, AIEC confer an advantage over the commensal flora. The annotation and genome analysis of the AIEC LF82 strain has highlighted the existence of pathogenicity islands, specific genes encoding potential virulence factors but also point mutations, type pathoadaptatives, in known virulence genes likely to allow AIEC strains to colonize the intestinal mucosa of patients genetically predisposed to develop TM.
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https://tel.archives-ouvertes.fr/tel-00719695
Contributor : Camille Meyer <>
Submitted on : Friday, July 20, 2012 - 3:03:46 PM
Last modification on : Friday, October 23, 2020 - 4:49:21 PM
Long-term archiving on: : Sunday, October 21, 2012 - 3:10:31 AM

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  • HAL Id : tel-00719695, version 1

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Sylvie Miquel. Facteurs de virulence de Escherichia coli adhérents et invasifs associés à la maladie de Crohn : caractérisation et régulation de leur expression. Biochimie, Biologie Moléculaire. Université d'Auvergne - Clermont-Ferrand I; Université Blaise Pascal - Clermont-Ferrand II, 2010. Français. ⟨NNT : 2010CLF1MM09⟩. ⟨tel-00719695⟩

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