A Modified Glycosaminoglycan, GM-0111, Inhibits Molecular Signaling Involved in Periodontitis

PLoS One. 2016 Jun 16;11(6):e0157310. doi: 10.1371/journal.pone.0157310. eCollection 2016.

Abstract

Background: Periodontitis is characterized by microbial infection, inflammation, tissue breakdown, and accelerated loss of alveolar bone matrix. Treatment targeting these multiple stages of the disease provides ways to treat or prevent periodontitis. Certain glycosaminoglycans (GAGs) block multiple inflammatory mediators as well as suppress bacterial growth, suggesting that these GAGs may be exploited as a therapeutic for periodontitis.

Methods: We investigated the effects of a synthetic GAG, GM-0111, on various molecular events associated with periodontitis: growth of Porphyromonas gingivalis (P. gingivalis) and Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) pathogenic bacteria associated with periodontitis; activation of pro-inflammatory signaling through TLR2 and TLR4 in mouse macrophage RAW 264.7 cells and heterologously expressed HEK 293 cells; osteoclast formation and bone matrix resorption in cultured mouse pre-osteoclasts.

Results: (1) GM-0111 suppressed the growth of P. gingivalis and A. actinomycetemcomitans even at 1% (w/v) solution. The antibacterial effects of GM-0111 were stronger than hyaluronic acid (HA) or xylitol in P. gingivalis at all concentrations and comparable to xylitol in A. actinomycetemcomitans at ≥2% (w/v) solution. We also observed that GM-0111 suppressed biofilm formation of P. gingivalis and these effects were much stronger than HA. (2) GM-0111 inhibited TLR-mediated pro-inflammatory cellular signaling both in macrophage and HEK 293 cells with higher selectivity for TLR2 than TLR4 (IC50 of 1-10 ng/mL vs. > 100 μg/mL, respectively). (3) GM-0111 blocked RANKL-induced osteoclast formation (as low as 300 ng/mL) and bone matrix resorption. While GM-0111 showed high affinity binding to RANKL, it did not interfere with RANKL/RANK/NF-κB signaling, suggesting that GM-0111 inhibits osteoclast formation by a RANKL-RANK-independent mechanism.

Conclusions: We report that GM-0111 inhibits multiple molecular events involved in periodontitis, spanning from the early pro-inflammatory TLR signaling, to pathways activated at the later stage component of bone loss.

MeSH terms

  • Aggregatibacter actinomycetemcomitans / drug effects*
  • Aggregatibacter actinomycetemcomitans / growth & development
  • Aggregatibacter actinomycetemcomitans / metabolism
  • Animals
  • Anti-Inflammatory Agents, Non-Steroidal / chemical synthesis
  • Anti-Inflammatory Agents, Non-Steroidal / pharmacology*
  • Binding Sites
  • Biofilms / drug effects*
  • Biofilms / growth & development
  • Bone Density Conservation Agents / chemical synthesis
  • Bone Density Conservation Agents / pharmacology*
  • Cell Line
  • Gene Expression
  • Glycosaminoglycans / chemical synthesis
  • Glycosaminoglycans / pharmacology*
  • HEK293 Cells
  • Humans
  • Macrophages / cytology
  • Macrophages / drug effects
  • Macrophages / metabolism
  • Mice
  • NF-kappa B / genetics
  • NF-kappa B / metabolism
  • Osteoblasts / cytology
  • Osteoblasts / drug effects
  • Osteoblasts / metabolism
  • Osteoclasts / cytology
  • Osteoclasts / drug effects
  • Osteoclasts / metabolism
  • Periodontitis / prevention & control
  • Porphyromonas gingivalis / drug effects*
  • Porphyromonas gingivalis / growth & development
  • Porphyromonas gingivalis / metabolism
  • Protein Binding
  • RANK Ligand / genetics
  • RANK Ligand / metabolism
  • Receptor Activator of Nuclear Factor-kappa B / genetics
  • Receptor Activator of Nuclear Factor-kappa B / metabolism
  • Signal Transduction / drug effects*
  • Toll-Like Receptor 2 / genetics
  • Toll-Like Receptor 2 / metabolism
  • Toll-Like Receptor 4 / genetics
  • Toll-Like Receptor 4 / metabolism

Substances

  • Anti-Inflammatory Agents, Non-Steroidal
  • Bone Density Conservation Agents
  • Glycosaminoglycans
  • NF-kappa B
  • RANK Ligand
  • Receptor Activator of Nuclear Factor-kappa B
  • Tlr2 protein, mouse
  • Tlr4 protein, mouse
  • Tnfrsf11a protein, mouse
  • Tnfsf11 protein, mouse
  • Toll-Like Receptor 2
  • Toll-Like Receptor 4