Introduction

Surgical procedures such as abdominoplasty trigger complex inflammatory and oxidative responses that influence postoperative recovery and tissue repair. Wound healing is a complex biological process involving the coordinated action of inflammatory cells, epidermal and dermal cells, extracellular matrix components, blood vessels, and plasma-derived proteins, all regulated by cytokines and growth factors [10]. This physiological process is essential for tissue repair following injury or surgical procedures. However, wound healing becomes more challenging in the presence of inflammatory complications, especially after high-complexity procedures such as abdominoplasty.

The inflammatory response triggered by surgical trauma is mediated by a complex network of cytokines that regulate immune activation and tissue repair. Among these mediators, tumor necrosis factor alpha (TNF-α) is a key pro-inflammatory cytokine involved in the early phase of wound healing, promoting leukocyte recruitment, endothelial activation, and amplification of the inflammatory cascade. Conversely, interleukin-10 (IL-10) plays a central anti-inflammatory role by limiting excessive immune responses and promoting the resolution phase of inflammation, thereby contributing to tissue repair and scar modulation. The balance between pro- and anti-inflammatory cytokines is an important indicator of postoperative inflammatory status and recovery dynamics. TNF-α reflects inflammatory activation, whereas IL-10 represents regulatory immune responses. For this reason, both cytokines are widely used as biomarkers to monitor inflammatory processes in clinical and translational studies of tissue injury and wound healing [4, 11, 20, 35].

In addition to inflammatory mediators, oxidative stress plays an important role in tissue injury and postoperative recovery. Thiobarbituric acid reactive substances (TBARS) are widely used as an indirect marker of lipid peroxidation, reflecting oxidative damage to cell membranes caused by reactive oxygen species (ROS). Increased TBARS levels have been associated with surgical trauma, inflammation, and impaired tissue repair. Therefore, TBARS is widely used as a biomarker of oxidative stress in clinical and experimental studies. Nitrite levels were also evaluated as an indirect indicator of nitric oxide (NO) metabolism. Nitric oxide is rapidly converted into more stable metabolites, such as nitrite and nitrate, in biological fluids. Therefore, nitrite concentration is commonly used as an indirect marker of NO bioavailability and endothelial function. Together, TBARS and nitrite measurements provide complementary information about oxidative stress and nitric oxide–related pathways involved in postoperative tissue repair and inflammatory regulation [3, 5, 21].

Saliva has emerged as a valuable biological fluid for monitoring inflammatory and oxidative biomarkers in clinical research. Several studies have demonstrated that salivary cytokines may reflect systemic inflammatory responses, as many circulating mediators can diffuse from blood into saliva through transcellular or paracellular pathways in the salivary glands [20, 34]. Because saliva collection is non-invasive, painless, and easily repeatable, saliva represents a practical alternative to blood sampling for longitudinal monitoring of inflammatory processes, particularly in postoperative and outpatient settings [17].

Photobiomodulation (PBM) has emerged as a promising, non-invasive therapeutic strategy that uses low-level light to modulate cellular processes and accelerate wound healing [18]. PBM interacts with mitochondrial components, particularly cytochrome c oxidase. This interaction increases ATP synthesis, promotes tissue repair, and activates cellular signaling pathways involved in regeneration [28, 37]. PBM has been shown to stimulate fibroblast proliferation and migration. It also improves extracellular matrix deposition and enhances collagen production, processes that are essential for effective wound healing. These effects are particularly relevant in pathological conditions such as diabetic wounds, where fibroblast function is often impaired [16].

Additionally, PBM can regulate gene expression during the healing process. Studies have shown downregulation of matrix metalloproteinases (MMP2 and MMP9) and pro-inflammatory cytokines such as IL-6 and IL-10. At the same time, PBM may upregulate genes such as DNMT3A and bFGF, which are associated with improved wound healing outcomes. Pilar et al., [25]. Clinical trials have also shown that PBM improves scar quality during the early stages of healing when compared to untreated scars, although its long-term effects appear to diminish after one year [29].

Despite these encouraging findings, the efficacy of PBM depends strongly on treatment parameters such as light source, wavelength, energy density, pulse structure, and application duration [18]. The effects of PBM in the acute postoperative period, particularly on inflammatory and oxidative markers in surgical patients, remain poorly explored.

Abdominoplasty represents a relevant clinical model for studying postoperative inflammation and oxidative stress because the procedure involves extensive tissue manipulation, vascular disruption, and a pronounced inflammatory response during the early healing phase.

Given the limited clinical evidence regarding PBM effects on inflammatory and oxidative biomarkers in abdominal surgery, this pilot study was designed to explore potential biological responses during the early postoperative period. Therefore, the present study aimed to investigate whether a single PBM session could modulate inflammatory and oxidative stress responses during the acute healing phase following abdominoplasty. These effects were evaluated through salivary biomarkers of inflammation (TNF-α and IL-10) and oxidative stress (TBARS and nitrites). These biomarkers provide complementary information on inflammatory activation and immune regulation during postoperative recovery. Saliva represents a non-invasive and easily accessible biological matrix for monitoring inflammatory and oxidative processes in surgical patients, making it particularly suitable for longitudinal postoperative studies.