Abstract
BackgroundPorphyromonas gingivalis is associated with periodontal disease and invades different cell types including epithelial, endothelial and smooth muscle cells. In addition to P. gingivalis DNA, we have previously identified live invasive bacteria in atheromatous tissue. However, the mechanism of persistence of this organism in vascular tissues remains unclear. Therefore, the objective of this study was to analyze the ability of intracellular P. gingivalis to persist for extended periods of time, transmit to and possibly replicate in different cell types.ResultsUsing antibiotic protection assays, immunofluorescent and laser confocal microscopy, we found that after a prolonged intracellular phase, while P. gingivalis can still be detected by immunostaining, the intracellular organisms lose their ability to be recovered in vitro. Surprisingly however, intracellular P. gingivalis could be recovered in vitro upon co incubation with fresh vascular host cells. We then demonstrated that the organism was able to exit the initially infected host cells, then enter and multiply in new host cells. Further, we found that cell-to-cell contact increased the transmission rate but was not required for transmission. Finally, we found that the invasion of new host cells allowed P. gingivalis to increase its numbers.ConclusionOur results suggest that the persistence of vascular tissue-embedded P. gingivalis is due to its ability to transmit among different cell types. This is the first communication demonstrating the intercellular transmission as a likely mechanism converting latent intracellular bacteria from state of dormancy to a viable state allowing for persistence of an inflammatory pathogen in vascular tissue.
Highlights
Porphyromonas gingivalis is associated with periodontal disease and invades different cell types including epithelial, endothelial and smooth muscle cells
P. gingivalis is able to transmit from infected to uninfected cells Once we found that no P. gingivalis could be recovered on blood agar plates (BAP) from endothelial cells (EC) and smooth muscle cells (SMC) at 48 hours post invasion, we investigated the possibility of intracellular P. gingivalis leaving the host cells to invade and possibly replicate in new host cells
Here we present data demonstrating that in our experimental set-up P. gingivalis strain W83: (1) displays an invasive ability that differs by up to an order of magnitude in the tested cell lines and the difference could be minimized by spin inoculation, (2) could be detected intracellularly in large numbers at 48 hr post invasion by immunofluorescent microscopy, but most of the bacteria could not be recovered on BAP; (3) can spread intercellularly between the same as well as between different cell types; (4) the invasion of fresh host cells ends the dormant, uncultivable state allowing for P. gingivalis isolation in vitro, and (5) cell-cell contact between infected cells and new host cells increases the rate of transmission
Summary
Porphyromonas gingivalis is associated with periodontal disease and invades different cell types including epithelial, endothelial and smooth muscle cells. The objective of this study was to analyze the ability of intracellular P. gingivalis to persist for extended periods of time, transmit to and possibly replicate in different cell types. We recently demonstrated for the first time the presence of viable invasive P. gingivalis in atheromatous plaque [8], implicating this chronic inflammatory agent in direct contribution to the development of inflammatory lesions at remote sites. This discovery led us to the legitimate question of the mechanism that would allow this organism to penetrate vascular walls upon dissemination and to persist in human vascular tissue
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
