Temperature measurement and Hsp47 immunoexpression in oral ulcers irradiated with defocused high-energy diode laser

Heat shock proteins (HSPs) are conservative protective proteins responsible for protein integrity during transcription in the cell under stress. Hsp47 is one of the most important chaperonins for collagen synthesis and release, and is up-regulated during wound repair. The aim of this study was to verify whether defocused high-energy diode laser (DDL) causes sufficient increase in local temperature to cause Hsp47 up-regulation during repair of oral ulcers. Chemically-induced ulcers in the rat tongue, and non-ulcerated tongue mucosa were irradiated using a high energy diode laser (non-contact – 4 mm from surface, 500 mW, 10 Hz for 40 s, energy density 80 J/cm2, fixed ulcer area of 0.25 cm2). Afterwards the specimens were submitted to immunohistochemical test for Hsp47. Temperature oscillation during DDL irradiation was also measured using a thermographic camera. Irradiated specimens exhibited transient mild increase in local temperature and significant up-regulation of Hsp47 in the mucosa from the superficial region (p = 0.035) to 1.7 mm deep (p = 0.049). In the deepest region of the mucosa Hsp47 was up-regulated only in ulcerated specimens mainly at 24 h (p = 0.049) and 72 h (p = 0.029) after ulcer induction. Conclusion: DDL increases local temperature and Hsp47 expression, which may contribute to wound repair by improvement collagen synthesis and release.

► Defocused diode laser increases local temperature and induces Hsp47 up-regulation.
► Hsp47 induction during laser irradiation is associated with improvement on tissue repair.
► The natural inflammation-evoked Hsp47 during tissue repair is increased by laser irradiation.