Effect of low level laser therapy on acute lung injury

Abstract

Low level laser therapy (LLLT) is prescribed as adjuvant therapy for inflammatory diseases. Hence, we examined whether LLLT may ameliorate acute lung injury (ALI) induced by intratracheal LPS instillation. C57 black mice (n=10 per group) were treated with intratracheal LPS (5mg/kg) or PBS. Six hours after instillation, two groups (PBS and LPS) were irradiated with laser at 660 nm, power output 30mW, fluency 10J/cm2. We observed a marked decrease in the number of cells recovered by bronchoalveolar lavage in LPS + LLLT animals compared to LPS alone (2.0±0.8 x 4.4±1.3, respectively p<0.05). LLLT also decreased the number of inflammatory cells infiltrated in lung interstitium (49.6±3.15 x 71.8±3.92), p<0.05). There was also a decrease in the expression of F4/80 (macrophage surface marker) and MCP-1 (monocyte chemoattractant protein-1), detected by quantitative PCR, in animals submitted to LPS + LLLT, when compared to animals that received only LPS. A marked decrease in cytokines secretion (IL1β, TNFα, IL6, IL10) was also observed in LPS+LLLT group. No difference was observed in animals that received PBS, regardless of LLLT. Therefore, LLLT decreases pulmonary inflammatory cell infiltration, cytokines and chemokines secretion in an experimental model of ALI, supporting the notion that laser therapy attenuates inflammatory intensity, what can contribute to accelerate ALI resolution.