Analysis of the activity to induce toll-like receptor (TLR)2- and TLR4-mediated stimulation of supragingival plaque

BACKGROUND: The deleterious effects of the accumulation of supragingival plaque are well known, but the role of the proinflammatory property of supragingival plaque in periodontal diseases has not been completely elucidated. The aim of this study was to determine the relevance of Toll-like receptor (TLR)2- and TLR4-stimulating activity of supragingival plaque to periodontal parameters. METHODS: We isolated 144 supragingival plaque samples and analyzed TLR2- and TLR4-stimulating activity using genetically engineered Chinese hamster ovary reporter cells that express a reporter molecule upon activation of nuclear factor-kappa B through TLR2 or TLR4. The numbers of Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans), and Streptococcus mutans cells in each plaque sample were determined by real-time polymerase chain reaction. RESULTS: The activity to induce TLR4-mediated stimulation, but not TLR2-mediated stimulation, was positively associated with the plaque score and bleeding on probing score of the teeth from which the plaque samples were taken. The activity to induce TLR2-mediated stimulation, but not TLR4-mediated stimulation, was negatively associated with probing depth and clinical attachment level. The ratio of TLR4-/TLR2-mediated stimulation was positively associated with all of those parameters. The number of P. gingivalis cells in each plaque sample was associated with the plaque score and clinical attachment level, but no strong association was observed between the ratio of examined bacteria in each plaque sample and the activity to induce TLR2- or TLR4-mediated stimulation, except for a weak correlation between the ratio of A. actinomycetemcomitans cells and the activity to induce TLR4-mediated stimulation. CONCLUSION: The TLR2- and TLR4-stimulating activity of supragingival plaque is associated with clinical parameters for gingivitis and periodontitis.