title: Saccharomyces boulardii protease inhibits the effects of Clostridium difficile toxins A and B in human colonic mucosa.
abstract: Saccharomyces boulardii is a nonpathogenic yeast used in the treatment of Clostridium difficile diarrhea and colitis. We have reported that S. boulardii inhibits C. difficile toxin A enteritis in rats by releasing a 54-kDa protease which digests the toxin A molecule and its brush border membrane (BBM) receptor (I. Castagliuolo, J. T. LaMont, S. T. Nikulasson, and C. Pothoulakis, Infect. Immun. 64:5225-5232, 1996). The aim of this study was to further evaluate the role of S. boulardii protease in preventing C. difficile toxin A enteritis in rat ileum and determine whether it protects human colonic mucosa from C. difficile toxins. A polyclonal rabbit antiserum raised against purified S. boulardii serine protease inhibited by 73% the proteolytic activity present in S. boulardii conditioned medium in vitro. The anti-protease immunoglobulin G (IgG) prevented the action of S. boulardii on toxin A-induced intestinal secretion and mucosal permeability to [3H]mannitol in rat ileal loops, while control rabbit IgG had no effect. The anti-protease IgG also prevented the effects of S. boulardii protease on digestion of toxins A and B and on binding of [3H]toxin A and [3H]toxin B to purified human colonic BBM. Purified S. boulardii protease reversed toxin A- and toxin B-induced inhibition of protein synthesis in human colonic (HT-29) cells. Furthermore, toxin A- and B-induced drops in transepithelial resistance in human colonic mucosa mounted in Ussing chambers were reversed by 60 and 68%, respectively, by preexposing the toxins to S. boulardii protease. We conclude that the protective effects of S. boulardii on C. difficile-induced inflammatory diarrhea in humans are due, at least in part, to proteolytic digestion of toxin A and B molecules by a secreted protease.
authors.affiliation: Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: I
authors.initials: I
authors.lastname: Castagliuolo
authors.forename: M F
authors.initials: MF
authors.lastname: Riegler
authors.forename: L
authors.initials: L
authors.lastname: Valenick
authors.forename: J T
authors.initials: JT
authors.lastname: LaMont
authors.forename: C
authors.initials: C
authors.lastname: Pothoulakis
mesh_terms: D000818:Animals; D000992:Antitoxins / Q000494:pharmacology; D001426:Bacterial Proteins; D001427:Bacterial Toxins / Q000378:metabolism / Q000633:toxicity*; D001665:Binding Sites / Q000276:immunology; D016360:Clostridioides difficile / Q000276:immunology*; D003106:Colon / Q000201:enzymology / Q000276:immunology / Q000382:microbiology*; D017077:Culture Media, Conditioned; D003603:Cytotoxins / Q000378:metabolism / Q000633:toxicity; D004761:Enterocolitis, Pseudomembranous / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control; D004768:Enterotoxins / Q000378:metabolism / Q000633:toxicity*; D019073:HT29 Cells; D006801:Humans; D006868:Hydrolysis; D007074:Immunoglobulin G / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000201:enzymology / Q000276:immunology / Q000382:microbiology*; D008297:Male; D008666:Metalloendopeptidases / Q000276:immunology / Q000494:pharmacology*; D008871:Microvilli / Q000201:enzymology / Q000276:immunology / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000276:immunology; D051381:Rats; D017208:Rats, Wistar; D012440:Saccharomyces / Q000201:enzymology* / Q000276:immunology
chemical_list: D000992:Antitoxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D017077:Culture Media, Conditioned; D003603:Cytotoxins; D004768:Enterotoxins; D007074:Immunoglobulin G; D011500:Protein Synthesis Inhibitors; C041348:tcdA protein, Clostridium difficile; C031815:toxB protein, Clostridium difficile; D008666:Metalloendopeptidases; C043859:pseudolysin, Pseudomonas aeruginosa