Laser phototherapy triggers the production of reactive oxygen species in oral epithelial cells without inducing DNA damage.
Laser phototherapy (LPT) is widely used in clinical practice to accelerate healing. Although the use of LPT has advantages, the molecular mechanisms involved in the process of accelerated healing and the safety concerns associated with LPT are still poorly understood. We investigated the physiological effects of LPT irradiation on the production and accumulation of reactive oxygen species (ROS), genomic instability, and deoxyribose nucleic acid (DNA) damage in human epithelial cells. In contrast to a high energy density (20  J/cm²), laser administered at a low energy density (4  J/cm²) resulted in the accumulation of ROS. Interestingly, 4  J/cm² of LPT did not induce DNA damage, genomic instability, or nuclear influx of the BRCA1 DNA damage repair protein, a known genome protective molecule that actively participates in DNA repair. Our results suggest that administration of low energy densities of LPT induces the accumulation of safe levels of ROS, which may explain the accelerated healing results observed in patients. These findings indicate that epithelial cells have an endowed molecular circuitry that responds to LPT by physiologically inducing accumulation of ROS, which triggers accelerated healing. Importantly, our results suggest that low energy densities of LPT can serve as a safe therapy to accelerate epithelial healing.
Federal University of Rio Grande do Sul, School of Dentistry, Department of Oral Pathology, Rio Grande do Sul 90035-003, Brazil.
Caroline Siviero
CS
Dillenburg
University of Michigan School of Dentistry, Department of Periodontics and Oral Medicine, Laboratory of Epithelial Biology, Ann Arbor, Michigan 48109-1078.
Luciana Oliveira
LO
Almeida
Federal University of Rio Grande do Sul, School of Dentistry, Department of Oral Pathology, Rio Grande do Sul 90035-003, Brazil.
Manoela Domingues
MD
Martins
University of Michigan School of Dentistry, Department of Periodontics and Oral Medicine, Laboratory of Epithelial Biology, Ann Arbor, Michigan 48109-1078.
Cristiane Helena
CH
Squarize
University of Michigan School of Dentistry, Department of Periodontics and Oral Medicine, Laboratory of Epithelial Biology, Ann Arbor, Michigan 48109-1078.
Rogerio Moraes
RM
Castilho
D019313:BRCA1 Protein / Q000032:analysis / Q000378:metabolism; D002460:Cell Line; D053903:DNA Breaks, Double-Stranded / Q000528:radiation effects*; D004260:DNA Repair; D004847:Epithelial Cells / Q000378:metabolism / Q000528:radiation effects*; D006657:Histones / Q000032:analysis / Q000378:metabolism; D006801:Humans; D028022:Low-Level Light Therapy; D017382:Reactive Oxygen Species / Q000032:analysis / Q000378:metabolism* / Q000528:radiation effects
D019313:BRCA1 Protein; C492913:BRCA1 protein, human; C468783:H2AX protein, human; D006657:Histones; D017382:Reactive Oxygen Species