Crohn disease–associated adherent-invasive E. coli bacteria target mouse and human Peyer’s patches via long polar fimbriae
Benoit Chassaing, Nathalie Rolhion, Amélie de Vallée, Sa’ad Y. Salim, Maelle Prorok-Hamon, Christel Neut, Barry J. Campbell, Johan D. Söderholm, Jean-Pierre Hugot, Jean-Frédéric Colombel, Arlette Darfeuille-Michaud
Benoit Chassaing, Nathalie Rolhion, Amélie de Vallée, Sa’ad Y. Salim, Maelle Prorok-Hamon, Christel Neut, Barry J. Campbell, Johan D. Söderholm, Jean-Pierre Hugot, Jean-Frédéric Colombel, Arlette Darfeuille-Michaud
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Research Article

Crohn disease–associated adherent-invasive E. coli bacteria target mouse and human Peyer’s patches via long polar fimbriae

Abstract

Crohn disease (CD) is a multifactorial disease in which an abnormal immune response in the gastrointestinal (GI) tract leads to chronic inflammation. The small intestine, particularly the ileum, of patients with CD is colonized by adherent-invasive E. coli (AIEC) — a pathogenic group of E. coli able to adhere to and invade intestinal epithelial cells. As the earliest inflammatory lesions are microscopic erosions of the epithelium lining the Peyer’s patches (PPs), we investigated the ability of AIEC bacteria to interact with PPs and the virulence factors involved. We found that AIEC bacteria could interact with mouse and human PPs via long polar fimbriae (LPF). An LPF-negative AIEC mutant was highly impaired in its ability to interact with mouse and human PPs and to translocate across monolayers of M cells, specialized epithelial cells at the surface of PPs. The prevalence of AIEC strains harboring the lpf operon was markedly higher in CD patients compared with controls. In addition, increased numbers of AIEC, but not LPF-deficient AIEC, bacteria were found interacting with PPs from Nod2–/– mice compared with WT mice. In conclusion, we have identified LPF as a key factor for AIEC to target PPs. This could be the missing link between AIEC colonization and the presence of early lesions in the PPs of CD patients.

Authors

Benoit Chassaing, Nathalie Rolhion, Amélie de Vallée, Sa’ad Y. Salim, Maelle Prorok-Hamon, Christel Neut, Barry J. Campbell, Johan D. Söderholm, Jean-Pierre Hugot, Jean-Frédéric Colombel, Arlette Darfeuille-Michaud

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Figure 1

Interaction of AIEC bacteria with PPs.

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Interaction of AIEC bacteria with PPs. (A) Interaction of bacteria with ...
(A) Interaction of bacteria with murine PPs placed in Ussing chambers after a 4-hour infection period, with or without anti-GP2 antibody (1 μg/ml) and with or without 0.5% methyl α-d-mannopyranoside (mann). When needed, PPs were preincubated with anti-GP2 antibody. (B) Confocal analysis of PP sections after labeling of AIEC LF82 with LPS O83 antibody (green), of M cells with anti-GP2 antibody (red), and DNA with Hoechst (blue). Scale bars: 20 μm. Arrowheads show clear colocalization of bacteria and M cells. (C) Interaction of wild-type LF82 and lpf mutant with murine PPs placed in Ussing chambers after a 4-hour infection period. (D) HES staining and confocal analysis of indicated areas after Cy3-EUB228 FISH staining to detect bacteria (red) and Hoechst to identify DNA (blue). Scale bars: 100 μm for HES staining and 20 μm for confocal analysis. Images in the bottom row correspond to the boxed regions in the top row. (E) In vivo interaction of wild-type LF82 and lpf mutant with murine PPs using ileal loop assay after a 4-hour infection period in the presence of 0.5% methyl α-d-mannopyranoside. (F) Interaction of wild-type LF82 and lpf mutant with murine small intestine mucosa without PPs after a 4-hour infection period in Ussing chambers. All results are expressed as numbers of mucosa-associated bacteria; each value is the mean ± SEM of at least 5 separate experiments. (G) Interaction of wild-type LF82 bacteria with murine PPs placed in Ussing chambers and coincubated with nonpathogenic MG1655 E. coli K-12 strain expressing or not expressing LPFLF82. *P < 0.05, **P < 0.01, ***P < 0.001.