title: Cytolethal distending toxin damages the oral epithelium of gingival explants.
abstract: The cytolethal distending toxin (Cdt), expressed by the periodontal pathogen Aggregatibacter actinomycetemcomitans, inhibits the proliferation of cultured epithelial cells by arresting the cell cycle. The gingival epithelium is an early line of defense against microbial assault. When damaged, bacteria collectively gain entry into underlying connective tissue where microbial products can affect infiltrating inflammatory cells, leading to the destruction of the attachment apparatus. Histological evaluation of rat and healthy human gingival tissue exposed ex vivo to the Cdt for 36 and 18 hours, respectively, revealed extensive detachment of the keratinized outer layer and distention of spinous and basal cells in the oral epithelium. Treated human tissue also exhibited disruption of rete pegs and dissolution of cell junctions. Cells in the connective tissue appeared unaffected. Primary gingival epithelial cells, but not gingival fibroblasts, isolated from the same healthy human tissue were cell-cycle-arrested when treated with the toxin. These findings provide new evidence that the Cdt severely damages the oral epithelium, ex vivo, by specifically targeting epithelial cells, in situ. The Cdt shows preferential targeting of the epithelium as opposed to connective tissue in animal and human gingival explant models.
  
  
  BACKGROUND
  cytolethal distending toxin (Cdt), connective tissue (CT), 4',6-diamidino-2-phenylindole (DAPI), human gingival epithelial cells (HGEC), human gingival explants (HGX), human gingival fibroblasts (HGF), junctional epithelium (JE), oral epithelium (OE), rete pegs (RP), sulcular epithelium (SE).
authors.affiliation: Department of Microbiology, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: M
authors.initials: M
authors.lastname: Damek-Poprawa
authors.forename: M
authors.initials: M
authors.lastname: Haris
authors.forename: A
authors.initials: A
authors.lastname: Volgina
authors.forename: J
authors.initials: J
authors.lastname: Korostoff
authors.forename: J M
authors.initials: JM
authors.lastname: DiRienzo
mesh_terms: D000328:Adult; D016976:Aggregatibacter actinomycetemcomitans / Q000737:chemistry*; D000818:Animals; D001427:Bacterial Toxins / Q000633:toxicity*; D002453:Cell Cycle / Q000187:drug effects; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000187:drug effects*; D005881:Gingiva / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D009061:Mouth Mucosa / Q000166:cytology / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins; D046509:Tissue Culture Techniques
chemical_list: D001427:Bacterial Toxins; D011994:Recombinant Proteins; C067044:cytolethal distending toxin