Mechanisms and applications of the anti-inflammatory effects of photobiomodulation

Abstract

Photobiomodulation (PBM) also known as low-level level laser therapy is the use of red and near-infrared light to stimulate healing, relieve pain, and reduce inflammation. The primary chromophores have been identified as cytochrome c oxidase in mitochondria, and calcium ion channels (possibly mediated by light absorption by opsins). Secondary effects of photon absorption include increases in ATP, a brief burst of reactive oxygen species, an increase in nitric oxide, and modulation of calcium levels. Tertiary effects include activation of a wide range of transcription factors leading to improved cell survival, increased proliferation and migration, and new protein synthesis. There is a pronounced biphasic dose response whereby low levels of light have stimulating effects, while high levels of light have inhibitory effects. It has been found that PBM can produce ROS in normal cells, but when used in oxidatively stressed cells or in animal models of disease, ROS levels are lowered. PBM is able to up-regulate anti-oxidant defenses and reduce oxidative stress. It was shown that PBM can activate NF-kB in normal quiescent cells, however in activated inflammatory cells, inflammatory markers were decreased. One of the most reproducible effects of PBM is an overall reduction in inflammation, which is particularly important for disorders of the joints, traumatic injuries, lung disorders, and in the brain. PBM has been shown to reduce markers of M1 phenotype in activated macrophages. Many reports have shown reductions in reactive nitrogen species and prostaglandins in various animal models. PBM can reduce inflammation in the brain, abdominal fat, wounds, lungs, spinal cord.

Photobiomodulation and different macrophages phenotypes during muscle tissue repair

“…In the present study, PBM at 780 nm (70 mW and 8 J) led to an increase in TGF‐ β mRNA after 2 and 4 days. This difference could be related to the different amounts of energy delivered in the 2 studies 10, 111, 3, 25…”

“…The effects of PBM on macrophage phenotypes are beginning to be described in cell cultures studies,10, 30, 31, 32, 33, 34 evidencing that this therapeutic modality, especially using the NIR wavelength, is capable of altering the polarization of these cells in vitro. In vivo experiments have demonstrated that PBM (808 nm) can shift the phenotype of brain microglial polarization from the pro‐inflammatory phenotype (M1) to the anti‐inflammatory (M2) phenotype after ischemic stroke, promoting cortical neurogenesis 35.…”

Near-infrared photobiomodulation combined with coenzyme Q10 for depression in a mouse model of restraint stress: reduction in oxidative stress, neuroinflammation, and apoptosis

“…Low levels of light at these wavelengths modulates the release of nitric oxide (NO) (Uozumi et al, 2010) and increases both cerebral oxygenation (Wang et al, 2017) and blood flow (Salgado et al, 2015). Besides these effects, transcranial PBM can stimulate neurogenesis (Tanaka et al, 2011) and provide neuroprotection via antioxidant, anti-neuroinflammatory, and anti-apoptotic activities (De Taboada et al, 2011; Hamblin, 2017; Lu et al, 2017; Salehpour et al, 2017; Salehpour et al, 2018a). In particular, it has been demonstrated that transcranial PBM is able to increase regional cerebral blood flow in MDD patients (Schiffer et al, 2009).…”

Differential response of human dermal fibroblast subpopulations to visible and near‐infrared light: Potential of photobiomodulation for addressing cutaneous conditions

“…Traditionally, cytochrome c oxidase and nitrozated proteins were considered as the major targets of light . Recently, there has been increasing evidence that cryptochromes and opsins , mediate the cell's response to visible and UV light. All this suggests that there are several molecular targets, which could intercept a photon of light and trigger multiple signaling cascades.…”