Dual Effect of Low-Level Laser Therapy (LLLT) on the Acute Lung Inflammation Induced by Intestinal Ischemia and Reperfusion: Action on Anti- and Pro-Inflammatory Cytokines

Background and Objective: It is unknown if pro-and anti-inflammatory mediators in acute lung inflammation induced by intestinal ischemia and reperfusion (i-I/R) can be modulated by low-level laser therapy (LLLT). Study Design/Material and Methods: A controlled ex vivo study was developed in which rats were irradiated (660 nm, 30 mW, 0.08 cm(2) of spot size) on the skin over the right upper bronchus 1 hour post-mesenteric artery occlusion and euthanized 4 hours later. For pretreatment with anti-tumor necrosis factor (TNF) or IL-10 antibodies, the rats received either one of the agents 15 minutes before the beginning of reperfusion. Methods: Lung edema was measured by the Evans blue extravasation and pulmonary neutrophils influx was determined by myeloperoxidase (MPO) activity. Both TNF and IL-10 expression and protein in lung were evaluated by RT-PCR and ELISA, respectively. Results: LLLT reduced the edema (80.1 +/- 41.8 mu g g(-1) dry weight), neutrophils influx (0.83 +/- 0.02 x 10(6) cells ml(-1)), MPO activity (2.91 +/- 0.60), and TNF (153.0 +/- 21.0 pg mg(-1) tissue) in lung when compared with respective control groups. Surprisingly, the LLLT increased the IL-10 (0.65 +/- 0.13) in lung from animals subjected to i-I/R. Moreover, LLLT (0.32 +/- 0.07 pg ml(-1)) reduced the TNF-alpha level in RPAECs when compared with i-I/R group. The presence of anti-TNF or IL-10 antibodies did not alter the LLLT effect on IL-10 (465.1 +/- 21.0 pg mg (1) tissue) or TNF (223.5 +/- 21.0 pg mg (1) tissue) in lung from animals submitted to i-I/R. Conclusion: The results indicate that the LLLT attenuates the i-I/R-induced acute lung inflammation which favor the IL-10 production and reduce TNF generation. Lasers Surg. Med. 43:410-420, 2011. (C) 2011 Wiley-Liss, Inc.