title: Interactions of Treponema pallidum with endothelial cell monolayers.
abstract: Syphilis is a chronic disease characterized by hematogenous dissemination of Treponema pallidum into tissues such as the cardiovascular and central nervous systems. In order to test whether these aspects of the pathogenesis of syphilis reflect an ability of T. pallidum to invade vascular endothelial surfaces, we explored the association of T. pallidum with human and rabbit endothelial cells in vitro. Using radiolabeled motile organisms, we found that treponemal attachment was two times greater to rabbit aortic endothelial cells and human umbilical endothelial cells than to HeLa cells. Mild trypsinization of attached treponemes resulted in release from cells of all organisms detectable by darkfield microscopy without visible damage to the monolayer. Nevertheless, 25% of the counts representing T. pallidum remained associated with the cell monolayers. Further trypsin treatment to release the monolayer and differential centrifugation showed that 80% of the remaining cell-associated counts were not within the cells. These results suggest that some treponemes had associated with the monolayer in a trypsin resistant niche. Additionally, motile T. pallidum passed through tight-junctioned endothelial cell monolayers on membrane filters under conditions were heat-killed T. pallidum and the host indigenous nonpathogen. T. phagedenis biotype Reiter failed to do so. Electron micrographs of transverse sections through the monolayers showed many T. pallidum in junctions between endothelial cells. These studies suggest that T. pallidum may leave the circulation by passing between endothelial cells.
authors.affiliation: Department of Microbiology and Immunology, Bowman Gray School of Medicine, Winston-Salem, North Carolina 27103.
authors.forename: D D
authors.initials: DD
authors.lastname: Thomas
authors.forename: A M
authors.initials: AM
authors.lastname: Fogelman
authors.forename: J N
authors.initials: JN
authors.lastname: Miller
authors.forename: M A
authors.initials: MA
authors.lastname: Lovett
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion / Q000187:drug effects; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured; D003470:Culture Media; D004730:Endothelium, Vascular / Q000382:microbiology*; D006367:HeLa Cells; D006801:Humans; D008854:Microscopy, Electron; D009447:Neuroblastoma; D011817:Rabbits; D013587:Syphilis / Q000382:microbiology*; D014210:Treponema pallidum / Q000187:drug effects / Q000472:pathogenicity*; D014357:Trypsin / Q000494:pharmacology; D014774:Virulence / Q000187:drug effects
chemical_list: D003470:Culture Media; D014357:Trypsin