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-1ß, 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.

Effect of Photobiomodulation on C2C12 Myoblasts Cultivated in M1 Macrophage-conditioned Media.

Moderate levels of a proinflammatory macrophages phenotype are indispensable and play an important role in the skeletal muscle repair process since this response depends on their secreted products concentration to influence and modulate muscle inflammation as well as the differentiation of myoblasts. This study investigated the effects of photobiomodulation (PBM) on undifferentiated and differentiation-induced C2C12 myoblasts cultivated in different concentrations of M1 phenotype macrophage-conditioned media of J774 cells (MCM1) also submitted to PBM using the same irradiation parameters. Irradiation was performed once with low-level laser (780 nm, 70 mW, 1 J) and was evaluated cell viability, proliferation and differentiation, nitric oxide (NO) synthesis and IL-6 and TNF-α protein levels 24 and 48 h after C2C12 irradiation. PBM treatment in undifferentiated myoblasts exhibited lower IL-6 levels in the presence of nonirradiated MCM1 at both concentrations. Myoblasts in proliferation condition cultivated with irradiated MCM1 showed lower IL-6 and TNF-α levels after 48 h in the presence of both concentrations evaluated. PBM induced a decrease in the synthesis of NO on undifferentiated and differentiation-induced myoblasts. PBM was able to reduce the level of proinflammatory protein and markers, which are important to allow the differentiation of myoblasts during the muscle repair process.

Differential expression of inflammatory and anti-inflammatory mediators by M1 and M2 macrophages after photobiomodulation with red or infrared lasers.

In response to stimuli in the microenvironment, macrophages adopt either the M1 or M2 phenotype to coordinate the tissue repair process. Photobiomodulation (PBM) plays an important role in the modulation of acute inflammation, including cellular influx, macrophage polarization, and the release of inflammatory mediators. The aim of the present study was to evaluate the effects of red and infrared PBM on the mRNA expression of cytokines and chemokines in macrophages polarized to the M1 and M2 phenotypes. J774 macrophages activated to induce M1 (lipopolysaccharide + interferon gamma) or M2 (interleukin-4) phenotypes were irradiated with red or infrared PBM (1 J). After 4 and 24 h, gene expression was analyzed by qPCR. PBM at 660 nm decreased the mRNA expression of CCL3, CXCL2, and TNF-α in M1 macrophages and CXCL2 in M2 macrophages 4 h after irradiation. Similarly, PBM at 780 nm decreased mRNA expression levels of CCL3 and IL-6 by M1 macrophages 24 h after irradiation. Moreover, PBM at 780 nm increased the mRNA expression of TGFß1 4 h after irradiation and decreased the expression of this gene after 24 h in M2 macrophages. Although red and infrared PBM were able to modulate and reduce M1/M2a-related markers, infrared laser irradiation promoted a temporal increase in the expression of TGFß1 in M2 macrophages. Thus, depending on the time PBM is used on injured tissue, different parameters can promote optimal results by modulating specific macrophage phenotypes.