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Cell Microbiol. 2016 May;18(5):617-31. doi: 10.1111/cmi.12539. Epub 2015 Nov 23.

The Vat-AIEC protease promotes crossing of the intestinal mucus layer by Crohn's disease-associated Escherichia coli.

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Laboratoire de Bactériologie, Centre Hospitalo-Universitaire Clermont-Ferrand, Clermont-Ferrand, France.
Microbes, Intestins, Inflammation et Susceptibilité de l'Hôte, Université d'Auvergne, INSERM U1071, INRA USC2018, Clermont-Ferrand, France.
Equipe Biophysique Neurosensorielle, Faculté de Pharmacie, Université d'Auvergne, UMR INSERM 1107, Clermont-Ferrand, France.


The aetiology of Crohn's disease (CD) involves disorders in host genetic factors and intestinal microbiota. Adherent-invasive Escherichia coli (AIEC) are receiving increased attention because in studies of mucosa-associated microbiota, they are more prevalent in CD patients than in healthy subjects. AIEC are associated both with ileal and colonic disease phenotypes. In this study, we reported a protease called Vat-AIEC from AIEC that favours the mucosa colonization. The deletion of the Vat-AIEC-encoding gene resulted in an adhesion-impaired phenotype in vitro and affected the colonization of bacteria in contact with intestinal epithelial cells in a murine intestinal loop model, and also their gut colonization in vivo. Furthermore, unlike LF82Δvat-AIEC, wild-type AIEC reference strain LF82 was able to penetrate a mucus column extensively and promoted the degradation of mucins and a decrease in mucus viscosity. Vat-AIEC transcription was stimulated by several chemical conditions found in the ileum environment. Finally, the screening of E. coli strains isolated from CD patients revealed a preferential vat-AIEC association with AIEC strains belonging to the B2 phylogroup. Overall, this study revealed a new component of AIEC virulence that might favour their implantation in the gut of CD patients.


AIEC; Crohn's disease; Escherichia coli; mucinase; mucins; serine protease

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