title: Carboxymethyl beta-glucan binds to corneal epithelial cells and increases cell adhesion to laminin and resistance to oxidative stress.
abstract: OBJECTIVE
  Polysaccharides are frequently used as viscoelastic agents to improve pharmacokinetics of ophthalmic preparations. Recently, polysaccharides from yeast cell walls such as beta-glucans have emerged as bioactive molecules endowed with immunomodulatory and cytoprotective properties. In this study, we investigated the effects of carboxymethyl beta-glucan (CMG), a water-soluble derivative of yeast beta-glucan, on cultured rabbit corneal epithelial cells.
  
  
  METHODS
  We developed a fluorescein-labeled CMG to visualize its binding to corneal cells by means of digital microscopy and image deconvolution. The effects of CMG on adhesion and survival of corneal epithelial cells exposed to noxious stimuli were also studied.
  
  
  RESULTS
  CMG binds defined regions scattered throughout the body of corneal cells, suggesting binding specificity. Tridimensional reconstruction of fluorescence shows that binding is localized mainly at the plasma and nuclear membranes. Interestingly, CMG binding is highly represented at the level of focal adhesion of cells spreading onto laminin. Accordingly, CMG promotes adhesion of corneal epithelial cells to laminin without affecting their proliferation rate. CMG also protects cells from oxidative stress-dependent cell death, being ineffective in preventing ultraviolet B cytotoxicity.
  
  
  CONCLUSIONS
  Data show that CMG dynamically binds to corneal epithelial cells, promoting cell adhesion and resistance to oxidative stress.
authors.affiliation: Department of Pharmacology, University of Florence, Florence, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Porcu
authors.forename: Francesco
authors.initials: F
authors.lastname: Guarna
authors.forename: Laura
authors.initials: L
authors.lastname: Formentini
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Faraco
authors.forename: Silvia
authors.initials: S
authors.lastname: Fossati
authors.forename: Rita
authors.initials: R
authors.lastname: Mencucci
authors.forename: Emilio
authors.initials: E
authors.lastname: Rapizzi
authors.forename: Ugo
authors.initials: U
authors.lastname: Menchini
authors.forename: Flavio
authors.initials: F
authors.lastname: Moroni
authors.forename: Alberto
authors.initials: A
authors.lastname: Chiarugi
mesh_terms: D000818:Animals; D002448:Cell Adhesion / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D019573:Epithelium, Corneal / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D005456:Fluorescent Dyes; D006861:Hydrogen Peroxide / Q000633:toxicity; D007797:Laminin / Q000378:metabolism*; D018384:Oxidative Stress; D011817:Rabbits; D012441:Saccharomyces cerevisiae / Q000737:chemistry; D047071:beta-Glucans / Q000378:metabolism*
chemical_list: D005456:Fluorescent Dyes; D007797:Laminin; D047071:beta-Glucans; C029933:carboxymethyl-beta-1,3-glucan; D006861:Hydrogen Peroxide