Effect of phototherapy with low intensity laser on local and systemic immunomodulation following focal brain damage in rat

Abstract

Brain injury is responsible for significant morbidity and mortality in trauma patients, but controversy still exists over therapeutic management for these patients. The objective of this study was to analyze the effect of phototherapy with low intensity lasers on local and systemic immunomodulation following cryogenic brain injury. Laser phototherapy was applied (or not-controls) immediately after cryogenic brain injury performed in 51 adult male Wistar rats. The animals were irradiated twice (3 h interval), with continuous diode laser (gallium–aluminum–arsenide (GaAlAs), 780 nm, or indium–gallium–aluminum–phosphide (InGaAlP), 660 nm) in two points and contact mode, 40 mW, spot size 0.042 cm 2, 3 J/cm 2 and 5 J/cm 2 (3 s and 5 s, respectively). The experimental groups were: Control (non-irradiated), RL3 (visible red laser/ 3 J/cm 2), RL5 (visible red laser/5 J/cm 2), IRL3 (infrared laser/3 J/cm 2), IRL5 (infrared laser/5 J/cm 2). The production of interleukin-1IL-1β (IL-1β), interleukin6 (IL-6), interleukin-10 (IL-10), and tumor necrosis factor-α (TNF-α) was analyzed by enzyme immunoassay technique (ELISA) test in brain and blood samples. The IL-1β concentration in brain of the control group was significantly reduced in 24 h ( p < 0.01). This reduction was also observed in the RL5 and IRL3 groups. The TNF-α and IL-6 concentrations increased significantly ( p < 0.01 and p < 0.05, respectively) in the blood of all groups, except by the IRL3 group. The IL-6 levels in RL3 group were significantly smaller than in control group in both experimental times. IL-10 concentration was maintained stable in all groups in brain and blood. Under the conditions of this study, it is possible to conclude that the laser phototherapy can affect TNF-α, IL-1β and IL-6 levels in the brain and in circulation in the first 24 h following cryogenic brain injury.