Blockade of TLR2 Inhibits Porphyromonas gingivalis Suppression of Mineralized Matrix Formation by Human Dental Pulp Stem Cells

Introduction: Human dental pulp stem/progenitor cells (hDPSC) can differentiate into odontoblast-like cells and express dentin sialophosphoprotein (DSPP) and osteocalcin (OCN); thus, they may be used to regenerate dentin. However, residual bacterial components in the root canal may suppress this activity. Purpose: This study investigated the effect of a Porphyromonas gingivalis component on the expression of DSPP and OCN by stimulated hDPSCs and the influence of blockade of TLR2-mediated P gingivalis host recognition. Methods: Stimulated hDPSCs were exposed to varying concentrations of P gin givalis lipopolysaccharide (LPS), and the expression of DSPP and OCN was measured. Similar groups of stimulated hDPSCs were exposed to TLR2 blocking agents before exposure to LPS. Results: hDPSCs exposed to 5, 10, and 20 mu g/mL LPS exhibited a dose-dependent reduction in the expression of DSPP (3.19 +/- 0.18, 2.60 +/- 0.49, and 1.15 +/- 0.29, respectively) and OCN (3.51 +/- 1.18, 2.60 +/- 0.67 and 1.66 +/- 0.89, respectively). The expression of DSPP and OCN after exposure to 20,mu g/mL of LPS was significantly lower than measured for unexposed stimulated cells (analysis of variance and post hoc Tukey test, P <.05). The blockade of TLR2 using an extra- and intracellular agent affected DSPP (4.67 +/- 0.97 and 5.29 +/- 1.66, respectively) and OCN (5.25 +/- 1.69 and 5.82 +/- 2.38, respectively) expression at levels comparable to stimulated cells unexposed to 20 mu g/mL LPS (6.32 +/- 2.47 and 4.70 +/- 1.60 for DSPP and OCN, respectively). Conclusions: The suppressing effect of P gin givalis on mineralized matrix formation by hDPSCs is confirmed, and this suppression can be moderated by TLR2 blockade. (J Endod 2011;37:812-818)