Oral mucositis (OM), considered the main adverse effect of oncological treatment, is characterized as a painful lesion that affect patients’ basic physiological needs, such as eating and swallowing (Lalla et al., 2019, Kusiak et al., 2020). Severe OM is one of the reasons why patients may not tolerate oral diet, leading to an increase in medical appointments and use of drugs, and frequently change of treatment regimen (Elad et al., 2022, Sonis, 2011, Daugėlaitė et al., 2019. The pathogenesis of OM is described in stages, as a convenient method of describing a dynamic process involving DNA injury, cell death, ulcerations, and oral microbiome (Lalla et al., 2019, Sonis, 2011).

During the mucositis progression, the injured tissue promotes reactive oxygen species (ROS) release, activating different repair pathways. The nuclear factor-κB (NF-κB), activated by ROS, modulates the transcription of genes that represents the production of pro-inflammatory cytokines, such as tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β) (Pulito et al., 2020, Courtois et al., 2021). Also, OM has been associated with bacterial dysbiosis demonstrating the potential for dysbiotic shifts to aggravate antineoplastic-induced epithelial injury (Hong et al., 2019). Therefore, the administration of effective treatments should consider the pathways involved in mucositis pathobiology.

Photobiomodulation therapy (PBMT) has proven to reduce inflammation and pain and increase wound healing (Courtois et al., 2021). It is an eminent treatment modality recommended by The Multinational Association for Supportive care in Cancer/International Society for Oral Oncology (MASCC/ISOO) guidelines in the OM prevention and treatment of patients undergoing head and neck radiotherapy, associated or not with chemotherapy (Elad et al., 2022). The recommendation is due to the positive impact to treat patients that developed OM during cancer treatments (Sonis et al., 2016, Pellicioli et al., 2014). Although PBMT is advancing for clinical settings, standard protocols are still missing, and its cellular and molecular mechanism of action is not completely elucidated.

Until now, the mechanism of action relies on the effect of the light that penetrates the tissue and is absorbed by hemoglobin, myoglobin, and mitochondrial cytochrome c oxidase, to positively influence cellular metabolism (Courtois et al., 2021, Cronshaw et al., 2020). It is known that depending on light parameters, it can stimulate or inhibit cellular functions (Monteiro et al., 2022). However, despite recommended, the effects of photobiomodulation therapy in cellular level is still being described. Understanding the effect of each laser parameter is fundamental to develop better protocols and improve treatment strategies. Hence, it is important to understand the cellular and molecular effects of different laser parameters to elect a predictable therapy, regarding OM.

Findings of PBMT from in vitro studies are showing interesting and promising results (Ferreira et al., 2019, Monteiro et al., 2022). Establishing a protocol to deliver an ideal amount of energy and selecting optimal laser parameters has been the goal of different research groups. While recognizing the presence of studies assessing laser effects in vitro, it is crucial to emphasize the distinctive focus of our investigation. In contrast to existing research, our study sought to analyze the effects of varied parameters of PBMT on migration, proliferation, morphology, cytokines, and wound healing gene expression in both fibroblasts and keratinocytes post ionizing radiation and bacterial-induced stress. The acquisition of such comprehensive insights holds the potential to contribute significantly to the establishment of well-defined laser protocols, thereby enhancing translational research efforts.