Macrophages mediate corticotomy-accelerated orthodontic tooth movement

Sci Rep. 2018 Nov 14;8(1):16788. doi: 10.1038/s41598-018-34907-5.

Abstract

Clinical evidence has suggested that surgical corticotomy of the alveolar bone can accelerate local orthodontic tooth movement (OTM), but the underlying cell and molecular mechanisms remain largely unclear. The present study examined the role of macrophages played in corticotomy-assisted OTM. Orthodontic nickel-titanium springs were applied to the left maxillary first molars of rats or mice to induce OTM with or without corticotomy. Corticotomy enhanced OTM distance by accelerating movement through induction of local osteoclastogenesis and macrophage infiltration during OTM. Further analysis showed that macrophages were polarized toward an M1-like phenotype immediately after corticotomy and then switched to an M2-like phenotype during OTM. The microenvironment of corticotomy induced macrophage infiltration and polarization through the production of TNF-α. More importantly, the amount of OTM induced by corticotomy was significantly decreased after mice were depleted of monocyte/macrophages by injection of liposome-encapsulated clodronate. Further experiments by incubating cultured macrophages with fresh tissue suspension obtained from post-corticotomy gingiva switched the cells to an M1 phenotype through activation of the nuclear factor-κB (NF-κB) signaling pathway, and to an M2 phenotype through activation of the JAK/STAT3 signaling pathway. Our results suggest that corticotomy induces macrophage polarization first by activating the NF-κB signaling pathway and later by activating the JAK/STAT3 signaling pathway, and that these processes contribute to OTM by triggering production of inflammatory cytokines and osteoclastogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alveolar Process / surgery
  • Animals
  • Janus Kinases / metabolism
  • Macrophages / metabolism
  • Macrophages / physiology*
  • Mice
  • NF-kappa B / metabolism
  • Orthodontic Appliances
  • Osteogenesis
  • Phenotype
  • Rats
  • STAT3 Transcription Factor / metabolism
  • Signal Transduction
  • Tooth Movement Techniques / methods*
  • Tumor Necrosis Factor-alpha / biosynthesis

Substances

  • NF-kappa B
  • STAT3 Transcription Factor
  • Tumor Necrosis Factor-alpha
  • Janus Kinases