low-level laser therapy attenuates the myeloperoxidase activity and inflammatory mediator generation in lung inflammation induced by gut ischemia and reperfusion: a dose-response study

introduction : intestinal ischemia and reperfusion (i-i/r) is an insult associated with acute respiratory distress syndrome (ards). herein we evaluate the dose-response effect of low-level laser therapy (lllt) on lung inflammation induced by i-i/r. methods : mice were subjected to mesenteric artery occlusion (45 min) and killed after clamp release and intestinal reperfusion (2h). increasing doses (1, 3, 5 and 7,5 j/cm 2 ) of laser irradiation (660 nm) was carried out on the mice skin over the upper bronchus for 5 min after initiating reperfusion. neutrophils activation was determined by myeloperoxidase (mpo) activity. the mrna expression and protein concentration of inflammatory mediators il-1β, il-6, tnf and il-10 in lung were measured by rt-pcr and elisa, respectively. results : with exception of 1j/cm 2 , lllt reduced mpo activity as well as il-1β levels in the lungs from inflamed mice. lllt was also markedly effective in reducing both il-6 and tnf expression and levels in the lungs from mice submitted to i-i/r in all laser doses studied. otherwise, lllt significantly increased the protein levels of il-10 in inflamed mice by i-i/r; however only in the dose of 1j/cm 2 . conclusion : we conclude that the lllt is able to control the neutrophils activation and pro-inflammatory cytokines release into the lungs in a model of i-i/r in mice.