CO₂ laser therapy accelerates the healing of ulcers in the oral mucosa by inducing the expressions of heat shock protein-70 and tenascin C

Histol Histopathol. 2019 Feb;34(2):175-189. doi: 10.14670/HH-18-037. Epub 2018 Jun 1.

Abstract

The treatment of ulceration or stomatitis with laser therapy is known to accelerate healing and relieve pain, but the underlying biological mechanism is not fully understood. The present study used a mouse model of ulceration to investigate the molecular mechanisms by which CO₂ laser therapy accelerated the wound healing process. An ulcer was experimentally created in the palatal mucosa of the mouse and irradiated with light from a CO₂ laser. Compared with controls (no irradiation), laser irradiation induced the proliferation of epithelial cells and faster re-epithelialization of the wound area. Immunohistochemistry experiments showed that heat shock protein-70 (HSP70) was expressed mainly in the epithelium of normal palatal tissue, whereas there was little tenascin C (TnC) expression in the epithelium and mesenchyme under normal conditions. Laser irradiation induced HSP70 mRNA and protein expression in the lamina propria as well as TnC expression in the mesenchyme underlying the renewing epithelium. Epithelial cells and fibroblasts were exposed to heated culture medium or laser irradiation to establish whether hyperthermia mimicked the effect of laser irradiation. Culture of fibroblasts in heated medium increased the expressions of both TnC and TGF-β1, whereas laser irradiation induced only TnC expression. The present study indicates that CO₂ laser irradiation exerts a photobiogenic effect to up-regulate TnC expression without inducing TGF-β1 expression. We suggest that CO₂ laser therapy has an advantage over thermal stimulation.

MeSH terms

  • Animals
  • HSP70 Heat-Shock Proteins / biosynthesis*
  • HSP70 Heat-Shock Proteins / radiation effects
  • Laser Therapy*
  • Lasers, Gas*
  • Male
  • Mice
  • Mice, Inbred ICR
  • Oral Ulcer / pathology*
  • Tenascin / biosynthesis*
  • Tenascin / radiation effects
  • Wound Healing / radiation effects*

Substances

  • HSP70 Heat-Shock Proteins
  • Tenascin