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
LPF are involved in the ability of AIEC strain LF82 to target M cells.
Interaction of AIEC bacteria LF82 (A and B) and LF82-ΔlpfA isogenic mutant (C) with Caco-2-cl1 (A) or M-like cell (B and C) monolayers in the presence of 0.5% methyl α-d-mannopyranoside. Phalloidin-TRITC labeling of F-actin (red), anti-O83 antibody labeling of LF82 bacteria (green), and Hoechst labeling of DNA (blue) were used. Confocal photomicrographs of interaction of bacteria with in vitro M cells are representative of 3 separate experiments. Scale bars: 25 μm. (D) Translocation across Caco-2-cl1 or M-like cell monolayers. Results are expressed as CFU of translocated bacteria. Each value is the mean ± SEM of at least 5 separate experiments. (E) Translocation of LF82 bacteria and LF82-ΔlpfA isogenic mutant across M-like cell monolayers after 4 hours infection. Results are expressed as translocated bacteria relative to those obtained for strain LF82, taken as 1. (F) Confocal analysis of murine PP sections after labeling of AIEC LF82 with LPS O83 antibody (green), of M cell with UEA-1 TRITC (red), and DNA with Hoechst (blue). Scale bars: 20 μm. Arrowheads indicate UEA-1–positive cells. (G) Quantification of murine M cell–associated bacteria by confocal microscopy analysis. Bars represent the mean. **P < 0.01, ***P < 0.001.