title: Blockade of TLR2 inhibits Porphyromonas gingivalis suppression of mineralized matrix formation by human dental pulp stem cells.
abstract: BACKGROUND
  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.
  
  
  OBJECTIVE
  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. gingivalis 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 μg/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 μg/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 μg/mL LPS (6.32 ± 2.47 and 4.70 ± 1.60 for DSPP and OCN, respectively).
  
  
  CONCLUSIONS
  The suppressing effect of P. gingivalis on mineralized matrix formation by hDPSCs is confirmed, and this suppression can be moderated by TLR2 blockade.
authors.affiliation: Discipline of Endodontics, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada. valerie.tom.kun@utoronto.ca
authors.forename: Valerie Tom-Kun
authors.initials: VT
authors.lastname: Yamagishi
authors.forename: Calvin D
authors.initials: CD
authors.lastname: Torneck
authors.forename: Shimon
authors.initials: S
authors.lastname: Friedman
authors.forename: George T-J
authors.initials: GT
authors.lastname: Huang
authors.forename: Michael
authors.initials: M
authors.lastname: Glogauer
mesh_terms: D057134:Antibodies, Neutralizing / Q000494:pharmacology; D018929:Cell Culture Techniques; D002454:Cell Differentiation; D003782:Dental Pulp / Q000166:cytology* / Q000187:drug effects; D003810:Dentinogenesis / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D016326:Extracellular Matrix Proteins / Q000032:analysis / Q000187:drug effects; D006801:Humans; D051550:I-kappa B Kinase / Q000037:antagonists & inhibitors; D008070:Lipopolysaccharides / Q000494:pharmacology*; D015675:Osteocalcin / Q000032:analysis / Q000187:drug effects; D010750:Phosphoproteins / Q000032:analysis / Q000187:drug effects; D016966:Porphyromonas gingivalis / Q000502:physiology*; D060888:Real-Time Polymerase Chain Reaction; D012795:Sialoglycoproteins / Q000032:analysis / Q000187:drug effects; D013234:Stem Cells / Q000187:drug effects*; D013876:Thiophenes / Q000494:pharmacology; D051195:Toll-Like Receptor 2 / Q000037:antagonists & inhibitors*; D000099311:Dentin Sialophosphoprotein
chemical_list: D057134:Antibodies, Neutralizing; D016326:Extracellular Matrix Proteins; D051550:I-kappa B Kinase; D008070:Lipopolysaccharides; D015675:Osteocalcin; D010750:Phosphoproteins; D012795:Sialoglycoproteins; D013876:Thiophenes; D051195:Toll-Like Receptor 2; D000099311:Dentin Sialophosphoprotein; C477523:SC 514; C495342:TLR2 protein, human