Lung inflammation and endothelial cell damage are decreased after treatment with phototherapy (PhT) in a model of acute lung injury induced by Escherichia coli lipopolysaccharide in the rat

Lipopolysaccharide (LPS) mimics the symptoms of acute lung injury (ALI), which is characterized by the accumulation in the lungs of neutrophils producing inflammatory mediators. Because of the lack of information about phototherapy (PhT) effects on ALI, we investigated whether PhT (685 nm InGaAlP) attenuates LPS-induced ALI. PhT reduced lung edema, the accumulation of TNF-α in the lung, and myeloperoxidase (MPO) activity. However, PhT was not efficient in reducing of TNF-α concentration in both serum and neutrophils of blood after LPS. In another series of experiments, in vitro assays of the effects of PhT effect on mouse pulmonary arterial endothelium cells (MPAECs) after TNF-α showed that the laser restores the MPAECs damage induced at 6 or 24 h after TNF-α. These results suggest the PhT effect on ALI is partly due to inhibition of TNF-α release from neutrophils and lung cells.