Smart Bacteria Survive In Our Gums

Armen Hareyan's picture
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The bacteria Porphyromonas gingivalis are the cause of several periodontal diseases including periodontitis or gum inflammation. They can survive in our mouth by establishing their place in our gums and preventing infected cells from undergoing programmed cell death (apoptosis). According to a research study published in 2001 by Simin F. Nakhjiri et al., this happens because P. gingivalis alters the signals in the pathway that the cell follows for apoptosis (or, put simply, it blocks the cell’s instruction to kill itself). This, prevention of our cell death may sound like a good deal but it really isn’t.

A cell is programmed to kill itself when it is infected and can spread the infection. Blocking this part of the cell’s function means keeping the cell infected and alive and with the ability to spread the infection to other cells. Each of these infected cells can harbor thousands of P. gingival and because of this pathogen their chances of apoptosis decreases gradually through the first 24 hours after infection.

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P. gingival enters the epithelial cells of our gums. As soon as these cells detect the presence of this pathogen it starts the programmed cell death or apoptosis. DNA fragmentation is one of the actions induced by apoptotic machinery. The apoptotic machinery also includes molecules that will detect the cell’s condition and decide to either go on or prevent the act of killing itself. P. gingival increases those molecules that are anti-apoptosis and decreases those that are pro-apoptosis. This can also be detected by checking the DNA fragmentation which is present when checked immediately after infection but not detected 24 hours after infection. This shows that P. gingival stops the process of apoptosis.

Finally, this study had a very important future implication for cancer research. They found that P. gingival was able to stop apoptosis even if the infected cells were given a cancer chemotherapeutic agent called camptothecin. This finding along with the fact that it disrupts the normal periodontal health suggested that P. gingival can be associated with some form of oral cancer.

Reference: Inhibition of epithelial cell apoptosis by Porphyromonas gingivalis
FEMS Microbiology Letters, , Volume 200, Issue 2, 25 June 2001, Pages 145-149
Simin F. Nakhjiri, Yoonsuk Park, Ozlem Yilmaz, Whasun O. Chung, Kiyoko Watanabe, Azza El-Sabaeny, Kyewhan Park, Richard J. Lamont

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