The effect of low-level helium-neon (HeNe) laser radiation on the secretion of cytokines that promote chronic graft rejection – An in vitro study

Effects of amber LED on inflammatory and regulatory monocytes and lymphocytes

The primary objective of the present study was to assess the impact of amber LED photobiomodulation (PBM) on human monocytes and lymphocytes that were polarized into proinflammatory and regulatory/reparative phenotypes. Human leukocytes were polarized with LPS or LPS + IL-4 for 2 h and irradiated after 2 and 6 h with amber LED (590 nm). Cell absorbance spectrum and gene and protein expression of IL-1β, IL-6, IL-10, IL-17, TNF-α and IFNγ determined after 24 h. The results showed that irradiation did not significantly alter absorbance of non-polarized monocytes, whereas irradiated polarized monocytes presented reduction in absorbance in 625-850 nm region. Irradiated monocytes polarized with LPS + IL-4 presented reduction in absorbance in 600-725 nm region compared to non-irradiated group. Irradiated non-polarized lymphocytes presented absorbance peaks between 650 and 820 nm not seen in non-irradiated group. No difference was found in absorbance pattern of polarized lymphocytes after irradiation. Irradiation led to reduction in protein synthesis of IL-6 and TNFα in monocytes polarized to proinflammatory phenotype and increase in production of IL-17 in lymphocytes. Irradiation reduced production of IL-10 in monocytes and lymphocytes polarized to immunoregulatory phenotype. In conclusion, amber LED modulates light absorbance and expression of important cytokines in inflammatory/repair processes in monocytes and lymphocytes.

Effects of the phenotypic polarization state of human leukocytes on the optical absorbance spectrum

This study evaluated the optical absorbance spectrum of human monocytes, neutrophils and lymphocytes polarized, or not, to the inflammatory or immunoregulatory phenotypes. Peripheral human blood leukocytes were isolated and polarized (10 ng/mL) with LPS or IL-4 + LPS for 2 hours. After polarization, cells were washed and incubated for an additional 24 hours (monocytes and lymphocytes) or 12 hours (neutrophils). Next, cells were collected to evaluate the optical absorbance spectrum. The three types of leukocytes exhibited absorbance in the region from 450 to 900 nm, with greater absorbance at wavelengths lower than 570 nm. Lymphocytes had a second region of greater absorbance between 770 and 900 nm. Inflammatory monocytes and lymphocytes showed increased absorbance of blue, green and yellow wavelengths (monocytes), as well as red and infrared wavelengths (monocytes and lymphocytes). Immunoregulatory polarization altered the absorbance of monocytes and lymphocytes very little. Neutrophils treated with LPS or LPS + IL-4 exhibited lower absorbance at wavelengths higher than 575 nm compared to untreated cells. The present findings showed that leukocytes exhibit greater absorbance in regions of the spectrum that have not been much used in photobiomodulation (PBM), and the polarization of these cells can affect their capacity to absorb light. Taken together, these results suggest new perspectives in the use of PBM in the clinical setting depending on the wavelengths and the stage of the inflammatory process.

Photobiomodulation with 660-nm and 780-nm laser on activated J774 macrophage-like cells: Effect on M1 inflammatory markers

M1 profile macrophages exert a major influence on initial tissue repair process. Few days after the occurrence of injury, macrophages in the injured region exhibit a M2 profile, attenuate the effects of the M1 population, and stimulate the reconstruction of the damaged tissue. The different effects of macrophages in the healing process suggest that these cells could be the target of therapeutic interventions. Photobiomodulation has been used to accelerate tissue repair, but little is known regarding its effect on macrophages. In the present study, J774 macrophages were activated to simulate the M1 profile and irradiated with two different sets of laser parameters (780 nm, 70 mW, 2.6J/cm(2), 1.5s and 660 nm, 15 mW, 7.5 J/cm(2), 20s). IL-6, TNF-α, iNOS and COX-2 gene and protein expression were analyzed by RT-qPCR and ELISA. Both lasers were able to reduce TNF-α and iNOS expression, and TNF-α and COX-2 production, although the parameters used for 780 nm laser provided an additional decrease. 660 nm laser parameters resulted in an up-regulation of IL-6 expression and production. These findings imply a distinct, time-dependent modulation by the two different sets of laser parameters, suggesting that the best modulation may involve more than one combination of parameters.