Low energy laser irradiation fails to modulate the inflammatory function of human monocytes and endothelial cells

BACKGROUND AND OBJECTIVE: In view of the important regulatory role of cytokines in wound healing and inflammation, we investigated the effects of low energy laser irradiation on cytokine release by human peripheral blood monocytes (M phi) and human umbilical vein endothelial cells (HUVEC) in vitro. Also, the effects of laser light on the expression of endothelial adhesion molecules, another important feature of inflammatory and regenerative responses, were assessed. STUDY DESIGN/MATERIALS AND METHODS: Cells were irradiated with a pulsed GaAs-laser (904 nm) at energy densities 0 (= sham), 0.3, 3.0, or 9.0 J/cm2 and subsequently incubated in absence or presence of endotoxin (M phi) or the proinflammatory cytokines TNF alpha and IL-1 beta (HUVEC). RESULTS: Irradiation at any of the dosages used did not significantly affect spontaneous or endotoxin-induced release of TNF alpha, IL-6, and IL-8 by M phi. Similarly, secretion of IL-6 and IL-8 by resting or cytokine-activated HUVEC after either single or repeated laser treatment was unchanged as compared to sham-irradiated controls. Moreover, laser treatment did not induce de novo expression or upregulation of the endothelial adhesion molecules E-selectin, ICAM-1, and VCAM-1, and it failed to modify their expression in response to stimulation with TNF alpha or IL-1 beta. CONCLUSION: We conclude that with the specific laser parameters and dose-regimen used, low energy laserlight does not affect the inflammatory function of human monocytes and endothelial cells in vitro.