Saccharomyces boulardii Improves Intestinal Cell Restitution through Activation of the a2b1 Integrin Collagen Receptor Alexandra Canonici1,2, Carole Siret1,2, Emilie Pellegrino1,2, Rodolphe Pontier-Bres3, Laurent Pouyet4, Marie Pierre Montero1,2, Carole Colin1,2, Dorota Czerucka3, Ve´ ronique Rigot1,2, Fre´ de´ ric Andre´ 1,2* 1 Inserm, UMR 911, Centre de Recherche en Oncologie et Oncopharmacologie, Marseille, France, 2 Aix-Marseille Universite´, UMR 911, Marseille, France, 3 Team 4: Inflammation, Cancer, Cancer stem cells, INSERM U895, Centre Me´diterrane´en de Me´decine Mole´culaire (C3M), Nice, France, 4 Inserm U 624, Marseille, France Abstract Intestinal epithelial cell damage is frequently seen in the mucosal lesions of inflammatory bowel diseases such as ulcerative colitis or Crohn’s disease. Complete remission of these diseases requires both the cessation of inflammation and the migration of enterocytes to repair the damaged epithelium. Lyophilized Saccharomyces boulardii (Sb, Biocodex) is a nonpathogenic yeast widely used as a therapeutic agent for the treatment and prevention of diarrhea and other gastrointestinal disorders. In this study, we determined whether Sb could accelerate enterocyte migration. Cell migration was determined in Sb force-fed C57BL6J mice and in an in vitro wound model. The impact on a2b1 integrin activity was assessed using adhesion assays and the analysis of a2b1 mediated signaling pathways both in vitro and in vivo. We demonstrated that Sb secretes compounds that enhance the migration of enterocytes independently of cell proliferation. This enhanced migration was associated with the ability of Sb to favor cell-extracellular matrix interaction. Indeed, the yeast activates a2b1 integrin collagen receptors. This leads to an increase in tyrosine phosphorylation of cytoplasmic molecules, including focal adhesion kinase and paxillin, involved in the integrin signaling pathway. These changes are associated with the reorganization of focal adhesion structures. In conclusion Sb secretes motogenic factors that enhance cell restitution through the dynamic regulation of a2b1 integrin activity. This could be of major importance in the development of novel therapies targeting diseases characterized by severe mucosal injury, such as inflammatory and infectious bowel diseases. Citation: Canonici A, Siret C, Pellegrino E, Pontier-Bres R, Pouyet L, et al. (2011) Saccharomyces boulardii Improves Intestinal Cell Restitution through Activation of the a2b1 Integrin Collagen Receptor. PLoS ONE 6(3): e18427. doi:10.1371/journal.pone.0018427 Editor: Hang Nguyen, Emory University, United States of America Received November 2, 2010; Accepted March 7, 2011; Published March 31, 2011 Copyright: 2011 Canonici et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was financed in part by an institutional grant from Institut National du Cancer (InCa, Cance´ropoˆ le PACA). L. Pouyet is recipient of a postdoctoral fellowship award from Fondation pour la Recherche Medicale. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: D. Czerucka has acted as a consultant or scientific advisor to the company interested in developing therapeutic interventions for intestinal infections and inflammatory disorders; this company is BIOCODEX S.A. (Gentilly, France). She has a financial competing interest including salaries and travel grant. The content of this article was neither influenced nor constrained by this fact. * E-mail: frederic.andre@univmed.fr Introduction The colonic epithelium forms a continuous physical and functional barrier that protects the internal environment of the body from the fluctuating external milieu. Various substances including dietary elements, gastrointestinal secretory products and drugs are known to disrupt this epithelial barrier, leading to the shedding of epithelial cells and the development of wounds [1]. In addition inflammatory bowel diseases (IBD), including ulcerative colitis and Crohn’s disease, are characterized by varying degrees of mucosal surface damage, chronic inflammation and mucosal ulceration, resulting in the subsequent impairment of the barrier function [2]. Moreover, infection of the colonic mucosa by bacterial pathogens including Shigella, Salmonella or Clostridium difficile results in the development of acute intestinal inflammatory diseases and destruction of the intestinal epithelium [3,4]. The colonic barrier has a striking ability to rapidly reseal superficial wounds, which is critical for the maintenance of barrier function and homeostasis. As with other epithelia of the gastrointestinal tract, the repair of damaged colonic mucosa initially requires cell migration to restore epithelial continuity [1]. This process, termed restitution, is followed by the proliferation and subsequent maturation and differentiation of the cells, allowing the restoration of normal architecture and absorptive/secretory function. Intestinal restitution has been found to be influenced by a broad spectrum of factors derived from the gastrointestinal environment, including host epithelial and lamina propria cells, resident microbiota, and the dietary and non-dietary components present in the gastrointestinal lumen [2]. Moreover, dynamic and reciprocal crosstalk between receptors for soluble factors and those for the extracellular matrix (ECM) play a crucial role in the regulation of this process [5,6,7]. Integrins constitute the main cell surface adhesion receptors mediating cell-ECM adhesion. These transmembrane heterodi- meric molecules are made up of non-covalently bound a and b subunits. In mammals, 18 a and 8 b subunits combine to form 24 distinct integrin receptors that bind various ECM ligands with different affinities [8]. Integrins allow a bi-directional flow of mechanochemical information across the plasma membrane and facilitate interactions between the ECM and the actin cytoskeleton. PLoS ONE | www.plosone.org 1 March 2011 | Volume 6 | Issue 3 | e18427