title: Small molecule inhibitors of Clostridium difficile toxin B-induced cellular damage.
abstract: Clostridium difficile causes life-threatening diarrhea through the actions of its homologous toxins TcdA and TcdB on human colonocytes. Therapeutic agents that block toxin-induced damage are urgently needed to prevent the harmful consequences of toxin action that are not addressed with current antibiotic-based treatments. Here, we developed an imaging-based phenotypic screen to identify small molecules that protected human cells from TcdB-induced cell rounding. A series of structurally diverse compounds with antitoxin activity were identified and found to act through one of a small subset of mechanisms, including direct binding and sequestration of TcdB, inhibition of endosomal maturation, and noncompetitive inhibition of the toxin glucosyltransferase activity. Distinct classes of inhibitors were used further to dissect the determinants of the toxin-mediated necrosis phenotype occurring at higher doses of toxin. These findings validate and inform novel targeting strategies for discovering small molecule agents to treat C. difficile infection.
authors.affiliation: Molecular Structure & Function, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada.
authors.forename: John
authors.initials: J
authors.lastname: Tam
authors.affiliation: Molecular Structure & Function, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada.
authors.forename: Greg L
authors.initials: GL
authors.lastname: Beilhartz
authors.affiliation: Molecular Structure & Function, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada.
authors.forename: Anick
authors.initials: A
authors.lastname: Auger
authors.affiliation: Merck & Co. Inc., 2000 Galloping Hill Road, K15, Kenilworth, NJ 07033, USA.
authors.forename: Pulkit
authors.initials: P
authors.lastname: Gupta
authors.affiliation: Merck & Co. Inc., 2000 Galloping Hill Road, K15, Kenilworth, NJ 07033, USA.
authors.forename: Alex G
authors.initials: AG
authors.lastname: Therien
authors.affiliation: Molecular Structure & Function, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada. Electronic address: roman.melnyk@sickkids.ca.
authors.forename: Roman A
authors.initials: RA
authors.lastname: Melnyk
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000633:toxicity; D001427:Bacterial Toxins / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000633:toxicity; D044946:Biflavonoids / Q000737:chemistry / Q000378:metabolism; D002392:Catechin / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002522:Chlorocebus aethiops; D020355:Cholates / Q000737:chemistry / Q000378:metabolism; D016360:Clostridioides difficile / Q000378:metabolism*; D005707:Gallic Acid / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D009336:Necrosis; D010693:Phloretin / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D054852:Small Molecule Libraries / Q000737:chemistry* / Q000378:metabolism; D014709:Vero Cells
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D044946:Biflavonoids; D020355:Cholates; D054852:Small Molecule Libraries; C031815:toxB protein, Clostridium difficile; C077197:theaflavin digallate; D005707:Gallic Acid; D002392:Catechin; C045651:epigallocatechin gallate; C037034:methyl cholate; D010693:Phloretin