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 TGFβ1 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 TGFβ1 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.