Photobiomodulation therapy modulates epigenetic events and NF-κB expression in oral epithelial wound healing

The aim of this study was to evaluate the effect of photobiomodulation therapy (PBMT) on histone 3 acetylation (acH3) and NF-κB expression during oral ulcer healing. A total of 48 male Wistar rats were divided into control group (CG) and PBMT group (n = 24 each). Traumatic ulcers were created in the dorsum of the rats' tongue with a punch tool. Irradiation with InGaAlP laser, 660 nm, 40 mW, 0.04 cm² spot size, 4 J/cm², 4 s, and 0.16 J per spot was performed once a day in close contact for 10 consecutive days. CG received only daily handling. Rats were euthanized on days 3, 5, and 10 (n = 8) and were monitored daily to assess wound status. Immunohistochemical analysis for acH3 and NF-κB detection was performed. One thousand epithelial cells were counted, and mean acH3- and NF-κB-positive cells were calculated and compared between the groups. PBMT accelerated the repair of oral ulcers. On day 3, PBMT showed significantly higher means for acH3- and NF-κB-positive cells than CG. On day 5, no difference was observed between the groups concerning both markers. On day 10, PBMT presented lower acH3 and NF-κB means than the control group. We concluded that PBMT stimulates keratinocyte migration in the early stage of oral wound healing and keratinocyte differentiation at the final stage by modulating histone acetylation and NF-κB expression.