Effects of Photobiomodulation on Ventilatory Mechanics and Inflammatory Response in a Rat Model of Acute Lung Injury

Introduction: Acute Lung Injury (ALI) and Acute Respiratory Distress Syndrome (ARDS) are life-threatening inflammatory conditions characterized by neutrophil recruitment, cytokine storm, and disruption of ventilatory mechanics. Despite advances in supportive care, effective pharmacological therapies remain limited. Photobiomodulation (PBM), using different light spectra, including LED and low-level laser therapy (LLLT), has shown potential anti-inflammatory and tissue-regenerative effects. However, the specific impact of PBM on acute lung inflammation is not fully established. Methods: This experimental study involved 288 male Wistar rats subjected to tracheal instillation of Escherichia coli lipopolysaccharide (LPS) to induce acute lung injury. Animals were allocated to control and treatment groups receiving 430 nm LED, 660 nm red laser, or 808 nm infrared laser. After 24 hours, ventilatory mechanics (resistance, viscosity, elastance, and hysteresivity) were assessed through mechanical ventilation. Lung tissue was analyzed for myeloperoxidase (MPO) activity, cytokine expression (TNF-α, IL-1β, IL-6, IL-10) by RT-qPCR, and histological alterations. Results: Among the phototherapies, the 660 nm red laser was the only intervention capable of significantly reducing all parameters of ventilatory mechanics, MPO activity, and inflammatory cytokines, with histological evidence of attenuated neutrophil infiltration, reduced alveolar wall thickening, and decreased pulmonary edema. The 430 nm LED attenuated only selective cytokines without histological or mechanical benefits, while the 808 nm infrared laser reduced TNF-α and IL-6 with partial histological improvement but no effect on lung mechanics. Conclusion: PBM with a 660 nm red laser effectively modulated the inflammatory cascade in LPS-induced ALI, reducing the cytokine storm and improving ventilatory function with histological evidence of lung protection. These findings highlight PBM as a potential adjuvant therapy for acute lung inflammation.