Low level laser therapy reduces acute lung inflammation in a model of pulmonary and extrapulmonary LPS-induced ARDS

• 830 nm laser presents anti-inflammatory effects to the lungs.
• 830 nm laser inhibits neutrophils accumulation into the lungs induce by LPS.
• 830 nm laser inhibits the cytokines release induced by LPS.
• Protective effects of 830 nm laser is independent of the origin of the insult.

The present study aimed to investigate the effects low level laser therapy (LLLT) in a LPS-induced pulmonary and extrapulmonary acute respiratory distress syndrome (ARDS) in BALB/c mice. Laser (830 nm laser, 9 J/cm2, 35 mW, 80 s per point, 3 points per application) was applied in direct contact with skin, 1 h after LPS administration. Mice were distributed in control (n = 6; PBS), ARDS IT (n = 7; LPS orotracheally 10 μg/mouse), ARDS IP (n = 7; LPS intra-peritoneally 100 μg/mouse), ARDS IT + Laser (n = 9; LPS intra-tracheally 10 μg/mouse), ARDS IP + Laser (n = 9; LPS intra-peritoneally 100 μg/mouse). Twenty-four hours after last LPS administration, mice were studied for pulmonary inflammation by total and differential cell count in bronchoalveolar lavage (BAL), cytokines (IL-1beta, IL-6, KC and TNF-alpha) levels in BAL fluid and also by quantitative analysis of neutrophils number in the lung parenchyma. LLLT significantly reduced pulmonary and extrapulmonary inflammation in LPS-induced ARDS, as demonstrated by reduced number of total cells (p < 0.001) and neutrophils (p < 0.001) in BAL, reduced levels of IL-1beta, IL-6, KC and TNF-alpha in BAL fluid and in serum (p < 0.001), as well as the number of neutrophils in lung parenchyma (p < 0.001). LLLT is effective to reduce pulmonary inflammation in both pulmonary and extrapulmonary model of LPS-induced ARDS.