title: Induction of cytoskeletal rearrangements and loss of volume regulation in epithelial cells by Treponema denticola.
abstract: The early responses of oral epithelial cells to the adhesion of the oral spirochaete Treponema denticola were studied as a model of microbial perturbation of the plasma membrane. KB cell (ATCC CCL 17) monolayers were incubated with T. denticola (ATCC 35405) in alpha-MEM (minimal essential medium) for periods of 1-4 h at 37 degrees C without serum. Control cultures were exposed to bacteria-conditioned alpha-MEM without serum or bacteria or to alpha-MEM alone. At the end of each incubation, detached and attached epithelial cells were harvested and analysed separately. Compared with controls, T. denticola induced in 25% of cells a two-fold, time-dependent increase of detachment by 4 h. Detached cells in both T. denticola-exposed and control cultures exhibited 25% reductions in modal diameter, did not exclude propidium iodide, did not readhere, and did not form colonies. In T. denticola-exposed cultures, a larger subset (75%) of cells remained attached to the substratum, demonstrated no significant reduction of colony-forming efficiency and excluded propidium iodide. However, these cells exhibited a 21% reduction in diameter (p < 0.05), a 60% decrease of F-actin (p < 0.001), and a 74% reduction in the proportion expressing desmoplakin II (p < 0.01) after exposure to T. denticola. Flow cytometry showed a small (14%) but significant (p < 0.001) reduction in mean fluorescence intensity due to keratin expression in T. denticola-treated cultures. Exposure of cells to anisosmotic media demonstrated that, in contrast to controls, cultures challenged by bacteria failed to undergo compensatory volume regulation.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Periodontics, University of Toronto, Faculty of Dentistry, Ontario, Canada.
authors.forename: A B
authors.initials: AB
authors.lastname: De Filippo
authors.forename: R P
authors.initials: RP
authors.lastname: Ellen
authors.forename: C A
authors.initials: CA
authors.lastname: McCulloch
mesh_terms: D000199:Actins / Q000737:chemistry; D001422:Bacterial Adhesion; D002448:Cell Adhesion; D002462:Cell Membrane / Q000382:microbiology*; D002465:Cell Movement; D048429:Cell Size; D002470:Cell Survival; D003598:Cytoskeletal Proteins / Q000737:chemistry* / Q000502:physiology; D003599:Cytoskeleton / Q000737:chemistry / Q000382:microbiology*; D051180:Desmoplakins; D004848:Epithelium / Q000382:microbiology / Q000473:pathology; D006801:Humans; D007624:KB Cells; D007633:Keratins / Q000737:chemistry; D011487:Protein Conformation; D014208:Treponema / Q000502:physiology*
chemical_list: D000199:Actins; D003598:Cytoskeletal Proteins; C495294:DSP protein, human; D051180:Desmoplakins; D007633:Keratins