Saccharomyces boulardii Improves Intestinal Epithelial Cell Restitution by Inhibiting avb5 Integrin Activation State Alexandra Canonici1,2., Emilie Pellegrino1,2., Carole Siret1,2, Chloe´ Terciolo1,2, Dorota Czerucka3, Sonia Bastonero1,2, Jacques Marvaldi1,2, Dominique Lombardo1,2, Ve´ ronique Rigot1,2, Fre´ de´ ric Andre´ 1,2* 1 Aix-Marseille Universite´, Centre de Recherche en Oncologie et Oncopharmacologie, Marseille, France, 2 Inserm UMR 9111, Marseille, France, 3 Team 4, Inflammation, Cancer, Cancer Stem Cells, INSERM U895, Centre Me´diterrane´en de Me´decine Mole´culaire, Nice, France Abstract Intestinal epithelial cell damage is frequently seen in the mucosal lesions of infectious or inflammatory bowel diseases such as ulcerative colitis or Crohn’s disease. Complete remission of these diseases requires both the disappearance of inflammation and the repair of damaged epithelium. Saccharomyces boulardii (Sb, Biocodex) is a non-pathogenic yeast widely used as a preventive and therapeutic probiotic for the prevention and treatment of diarrhea and other gastrointestinal disorders. We recently showed that it enhances the repair of intestinal epithelium through activation of a2b1 integrin collagen receptors. In the present study, we demonstrated that a2b1 integrin is not the sole cell-extracellular matrix receptor involved during Sb-mediated intestinal restitution. Indeed, by using cell adhesion assays, we showed that Sb supernatant contains heat sensitive molecule(s), with a molecular weight higher than 9 kDa, which decreased avb5 integrin- mediated adhesion to vitronectin by competing with the integrin. Moreover, Sb-mediated changes in cell adhesion to vitronectin resulted in a reduction of the avb5signaling pathway. We used a monolayer wounding assay that mimics in vivo cell restitution to demonstrate that down-modulation of the avb5 integrin-vitronectin interaction is related to Sb-induced cell migration. We therefore postulated that Sb supernatant contains motogenic factors that enhance cell restitution through multiple pathways, including the dynamic fine regulation of avb5 integrin binding activity. This could be of major importance in diseases characterized by severe mucosal injury, such as inflammatory and infectious bowel diseases. Citation: Canonici A, Pellegrino E, Siret C, Terciolo C, Czerucka D, et al. (2012) Saccharomyces boulardii Improves Intestinal Epithelial Cell Restitution by Inhibiting avb5 Integrin Activation State. PLoS ONE 7(9): e45047. doi:10.1371/journal.pone.0045047 Editor: Henri Salmon, INRA, UR1282, France Received March 30, 2012; Accepted August 13, 2012; Published September 20, 2012 Copyright: 2012 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). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. No additional external funding received for this study. 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 financial competing interests, including salaries and travel grant. The content of this article was neither influenced nor constrained by this fact. Co-author Fre´de´ric Andre´ is a PLOS ONE Editorial Board member. This does not alter the authors’ adherence to all the PLOS ONE policies on sharing data and materials. * E-mail: frederic.andre@univ-amu.fr . These authors contributed equally to this work. Introduction The colonic epithelium forms a continuous physical and functional barrier that protects the internal environment of the body from the fluctuating external milieu [1]. A variety of inflammatory gastrointestinal disorders, including infectious colitis and inflammatory bowel disease, result in the breakdown of the intestinal epithelial barrier and subsequent erosion and ulceration [1,2,3,4]. The colonic epithelium possesses an innate ability to rapidly reseal superficial wounds, critical for the maintenance of barrier function and homeostasis. This process is dependent on the precise balance of migration, proliferation and differentiation of epithelial cells adjacent to the wounded area [1]. As with other epithelia of the gastrointestinal tract, the repair of damaged colonic mucosa initially requires cell restitution. This process is identified by stages of cell spreading and migration into the wound to restore epithelial continuity [1]. Restitution is followed by the proliferation and subsequent maturation and differentiation of the cells, allowing restoration of normal architecture and absorptive/ secretory functions. Colonic 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 both dietary and non-dietary components present in the gastrointestinal lumen [4,5]. Both in vitro and in vivo studies have unveiled that adhesion-mediated signaling between cells and the extracellular matrix (ECM) is critical in the regulation of cell restitution [1,6,7,8]. Moreover, in vitro studies have demonstrated that restitution is enhanced in the presence of ECM proteins [9,10]. Interactions between cells and ECM are mainly mediated by cell surface adhesion molecules termed integrins. Integrins are glycosylated heterodimers composed of non covalently associated type I transmembrane a and b subunits [11]. In mammals, 18 a and 8 b subunits combine to form 24 distinct integrin receptors that bind various ECM ligands with different affinities [11]. Integrins allow a bi-directional flow of mechanochemical infor- PLOS ONE | www.plosone.org 1 September 2012 | Volume 7 | Issue 9 | e45047