Periodontal bacterial-DNA initiated immuno-inflammatory responses in human osteoblastic cells

• Main Author: Bou, Chebel Najib
• Format: Others
• Published: VCU Scholars Compass 2010
• Subjects: Periodontal disease; Bacterial DNA; Osteoblast; PAMPs; Life Sciences; Physiology
• Online Access: http://scholarscompass.vcu.edu/etd/97; http://scholarscompass.vcu.edu/cgi/viewcontent.cgi?article=1096&context=etd

Periodontitis is a chronic inflammatory disease initiated by gram negative anaerobic bacteria. These bacteria possess pathogen-associated molecular patterns (PAMPs) that interact with various receptors including Toll like receptors (TLRs). Bacterial DNA (bDNA) is one of the PAMPs mainly recognized by TLR9. Interaction of bDNA and its receptors leads to activation of inflammatory signaling pathways potentially resulting in periodontal bone destruction. The aim of this study was to determine the production of IL- 6 and IL-8 in response to periodontal bDNA from human osteoblastic cells (MG-63). MG- 63 cells were stimulated in duplicate for 20 hours with 100ng/μl of bDNA from various pathogens including Porhyromonas gingivalis, Esherichia coli, Streptococcus sanguinis, Aggregatibacter actinomycetemcomitans as well as heat killed whole bacteria (1:100). E.coli LPS (10ng/μl) was used as a positive control in each experiment. To block TLR9 signaling, further experiments were carried out by treating MG-63 cells with chloroquine (10ng/μl) for 2 hours at 37ºC prior to stimulations. Cytokine levels were determined using enzyme linked-immunosorbent assay. Although IL-6 and IL-8 production was increased in response to periodontal bDNA in MG-63 cells, the results were not significant compared to unstimulated controls. As expected, E.coli DNA, E.coli LPS and heat killed whole bacteria stimulated significantly increased cytokine production (p<0.05). Blocking TLR9 with chloroquine did not affect the amount of cytokine production in bDNA stimulated cells suggesting that TLR9 may not be operant in triggering IL-6 and IL-8 production from MG- 63 cells. In conlusion, periodontal bDNA did not trigger significantly increased IL-6 and IL-8 production from MG-63 cells. Considering the involvement of several inflammatory mediators in periodontal bone destruction, further studies are warranted to assess the production of other cytokines in response to periodontal bDNA in human osteoblastic cells.