title: Viability of cultured periodontal pocket epithelium cells and Porphyromonas gingivalis association.
abstract: OBJECTIVE
  Porphyromonas gingivalis, one of the key pathogens in the development of periodontitis, produces a number of virulence factors that might explain its pathogenicity. One of them is the ability to adhere and invade pocket epithelium. The aim of this study was to follow, over time, the association of P. gingivalis and consequent morphological changes of the pocket epithelium cells.
  
  
  METHODS
  The association capacity of four P. gingivalis serotypes [K1, K2, K4, K- (nonencapsulated)] with in vitro cultured mono-layers from periodontal pocket epithelial cells of patients with periodontitis, was followed by fluorescence microscopy and bacterial culture. The contact time between bacteria and epithelium cells ranged from 45 min to 8 h. The microscopic evaluation allowed differentiation between dead and living cells (bacteria as well as epithelium) and description of the morphological changes after association.
  
  
  RESULTS
  A highly significant difference in the number of associating bacteria was found between dead and living epithelium cells, and between non-capsulated and capsulated strains. A significant increase in the proportion of dead pocket epithelium cells was found with prolonged association time. The morphological changes (rounding of the epithelial cell, detachment from the glass cover-slip and loss of intercellular contact) occurred faster for mono-layers inoculated with the non-encapsulated P. gingivalis strain.
  
  
  CONCLUSIONS
  This study indicates that dead pocket epithelium cells harbor more P. gingivalis cells, and that a positive correlation exists between contact time and cell death. For the P. ginigvalis species, non-encapsulated strains associate in higher number. As a result, the damage they cause to the host cell seems to occur faster than occurs in encapsulated strains. As such, cell death can be seen as the end-result of bacterial association.
authors.affiliation: Catholic University of Leuven, Faculty of Medicine, School of Dentistry, Oral Pathology and Maxillo-Facial Surgery, Department of Periodontology, Kapucijnenvoer 7, B-3000 Leuven, Belgium.
authors.forename: K
authors.initials: K
authors.lastname: Dierickx
authors.forename: M
authors.initials: M
authors.lastname: Pauwels
authors.forename: J
authors.initials: J
authors.lastname: Van Eldere
authors.forename: J J
authors.initials: JJ
authors.lastname: Cassiman
authors.forename: D
authors.initials: D
authors.lastname: Van Steenberghe
authors.forename: M
authors.initials: M
authors.lastname: Quirynen
mesh_terms: D001422:Bacterial Adhesion / Q000502:physiology; D001431:Bacteriological Techniques; D002448:Cell Adhesion; D016923:Cell Death; D048429:Cell Size; D002470:Cell Survival; D002478:Cells, Cultured; D015169:Colony Count, Microbial; D004847:Epithelial Cells / Q000382:microbiology / Q000473:pathology; D006801:Humans; D007365:Intercellular Junctions / Q000473:pathology; D016014:Linear Models; D016015:Logistic Models; D008856:Microscopy, Fluorescence; D010514:Periodontal Pocket / Q000382:microbiology / Q000473:pathology*; D010518:Periodontitis / Q000382:microbiology / Q000473:pathology; D016966:Porphyromonas gingivalis / Q000145:classification / Q000472:pathogenicity / Q000502:physiology*; D012703:Serotyping; D013223:Statistics as Topic; D013997:Time Factors; D037521:Virulence Factors / Q000502:physiology
chemical_list: D037521:Virulence Factors