Oral Pathogen Can Escape Phagocytosis of Mammalian Macrophages.

Macrophages are phagocytic cells that play a key role in host immune response and clearance of microbial pathogens. is an oral pathogen associated with the development of periodontitis. Escape from macrophage phagocytosis was tested by infecting THP-1-derived human macrophages and RAW 264.7 mouse macrophages with strains of W83 and 33277 as well as DL1 and OP50 at MOI = 100. CFU counts for all intracellular bacteria were determined. Then, infected macrophages were cultured in media without antibiotics to allow for escape and escaping bacteria were quantified by CFU counting. W83 displayed over 60% of the bacterial escape from the total amount of intracellular CFUs, significantly higher compared to all other bacteria strains. In addition, bacterial escape and re-entry were also tested and W83, once again, showed the highest numbers of CFUs able to exit and re-enter macrophages. Lastly, the function of the gene of W83 was tested on escape but found not related to this activity. Altogether, our results suggest that W83 is able to significantly avoid macrophage phagocytosis. We propose this ability is likely linked to the chronic nature of periodontitis.