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Entrance of Actinobacillus actinomycetemcomitans into HEp-2 cells in vitro
1Department of Microbiology, Dental Faculty, University of Oslo, Norway.
Abstract:
A strain of actinobacillus actinomycetemcomitans, freshly isolated from a juvenile periodontitis patient, and the FDC Y4 laboratory strain of Aa were tested for their capacity to adhere to and enter the epithelial cell line HEp-2 cells in vitro. Immunofluorescence microscopy as well as scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that both strains adhered to the outer surface of the HEp-2 cells. In the TEM studies, the specimens were also treated with Aa specific antibodies and gold labeled protein A. These examinations showed that only the freshly isolated strain of Aa was found within the HEp-2 cells. The intracellular Aa were found to be viable, and in one case one of them was seen to undergo division. It is concluded that freshly isolated Aa has the ability to enter epithelial HEp-2 cells in vitro, and it is tentatively suggested that this may play a role in the pathogenesis of periodontal disease.
Insights
Freshly isolated Actinobacillus actinomycetemcomitans (Aa) can invade HEp-2 epithelial cells, unlike laboratory strains. This invasion ability may contribute to the development of periodontal disease.
Area of Science:
- Microbiology
- Oral Biology
- Pathogenesis
Background:
- Actinobacillus actinomycetemcomitans (Aa) is implicated in juvenile periodontitis.
- Understanding bacterial invasion mechanisms is crucial for disease pathogenesis.
Purpose of the Study:
- To investigate the in vitro adherence and invasion capabilities of a freshly isolated Aa strain compared to a laboratory strain.
- To determine if Aa can enter and survive within epithelial cells.
Main Methods:
- Utilized HEp-2 epithelial cell lines for in vitro studies.
- Employed immunofluorescence microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM).
- Applied Aa-specific antibodies and gold-labeled protein A for enhanced TEM visualization.
Main Results:
- Both freshly isolated and laboratory Aa strains adhered to HEp-2 cells.
- Only the freshly isolated Aa strain was observed to invade HEp-2 cells.
- Intracellular Aa were viable, with some undergoing division.
Conclusions:
- Freshly isolated Aa possesses the ability to enter epithelial cells in vitro.
- Bacterial invasion of epithelial cells may play a role in periodontal disease pathogenesis.