IADR Abstract Archives
Bacterial extracellular ATP: A novel signalling molecule in periodontal disease
Objectives: In mammalian cells, extracellular ATP (eATP) is secreted by activated immune cells or damaged cells to alert the immune system of impending danger, eliciting the recruitment and priming of phagocytes. Since eATP triggers and amplifies innate immune responses, we hypothesized that periodontal pathogens may also possess the ability to secrete eATP, contributing to inflammation in periodontitis. It is currently unknown if oral bacteria secrete ATP extracellularly. The objectives of this study were, i) to determine if periodontal bacteria secrete eATP and ii) to determine if bacterial-derived eATP is functional as a signalling molecule to elicit host inflammatory responses.
Methods: The amount of eATP in the culture supernatant of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia and Fusobacterium nucleatum were determined by bioluminescence assay. Periodontal fibroblasts were treated with filter sterilized bacterial culture supernatant with and without treatment with apyrase, an enzyme which degrades ATP, and chemokine expression was determined by qPCR. Pharmacological inhibitors were employed to determine the host receptor responsible for sensing bacterial eATP. Migration assay was carried out to determine the effects of bacterial eATP on monocyte recruitment.
Results: A. actinomycetemcomitans secreted ATP into the culture supernatant. The bacterial eATP was found to be a functional signalling molecule eliciting chemokine expression in periodontal fibroblast. The expression of chemokines was found to be dependent on purinergic receptors. Bacterial eATP-induced chemokine expression was independent of cAMP and phospholipase C signalling pathways, suggesting the involvement of the ionotrophic P2X receptor. Furthermore, bacterial eATP also served as a chemotaxis signal for the recruitment of monocytes.
Conclusions: We provide evidence that A. actinomycetemcomitans derived eATP is a novel virulence factor which could contribute to the initiation of inflammation during periodontal disease.
Methods: The amount of eATP in the culture supernatant of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia and Fusobacterium nucleatum were determined by bioluminescence assay. Periodontal fibroblasts were treated with filter sterilized bacterial culture supernatant with and without treatment with apyrase, an enzyme which degrades ATP, and chemokine expression was determined by qPCR. Pharmacological inhibitors were employed to determine the host receptor responsible for sensing bacterial eATP. Migration assay was carried out to determine the effects of bacterial eATP on monocyte recruitment.
Results: A. actinomycetemcomitans secreted ATP into the culture supernatant. The bacterial eATP was found to be a functional signalling molecule eliciting chemokine expression in periodontal fibroblast. The expression of chemokines was found to be dependent on purinergic receptors. Bacterial eATP-induced chemokine expression was independent of cAMP and phospholipase C signalling pathways, suggesting the involvement of the ionotrophic P2X receptor. Furthermore, bacterial eATP also served as a chemotaxis signal for the recruitment of monocytes.
Conclusions: We provide evidence that A. actinomycetemcomitans derived eATP is a novel virulence factor which could contribute to the initiation of inflammation during periodontal disease.