Effect of low-level laser therapy on the modulation of the mitochondrial activity of macrophages

Abstract

BACKGROUND: Macrophages play a major role among the inflammatory cells that invade muscle tissue following an injury. Low-level laser therapy (LLLT) has long been used in clinical practice to accelerate the muscle repair process. However, little is known regarding its effect on macrophages. OBJECTIVE: This study evaluated the effect of LLLT on the mitochondrial activity (MA) of macrophages. METHOD: J774 macrophages were treated with lipopolysaccharide (LPS) and interferon - gamma (IFN-γ) (activation) for 24 h to simulate an inflammatory process, then irradiated with LLLT using two sets of parameters (780 nm; 70 mW; 3 J/cm2 and 660 nm; 15 mW; 7.5 J/cm2). Non-activated/non-irradiated cells composed the control group. MA was evaluated by the cell mitochondrial activity (MTT) assay (after 1, 3 and 5 days) in three independent experiments. The data were analyzed statistically. RESULTS: After 1 day of culture, activated and 780 nm irradiated macrophages showed lower MA than activated macrophages, but activated and 660 nm irradiated macrophages showed MA similar to activated cells. After 3 days, activated and irradiated (660 nm and 780 nm) macrophages showed greater MA than activated macrophages, and after 5 days, the activated and irradiated (660 nm and 780 nm) macrophages showed similar MA to the activated macrophages. CONCLUSIONS: These results show that 660 nm and 780 nm LLLT can modulate the cellular activation status of macrophages in inflammation, highlighting the importance of this resource and of the correct determination of its parameters in the repair process of skeletal muscle.

Review of light parameters and photobiomodulation efficacy: dive into complexity

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Effect of laser therapy on immune cells infiltrate after excisional wounds in diabetic rats

“…PBM is believed to promote angiogenesis, enhance neovascularization, increase collagen synthesis, and accelerate the healing of skin wounds . Recent studies have found that PBM at different wavelengths can modulate neutrophil chemotaxis and the cellular activation status of macrophages in inflammation processes .…”

Participation of the Immune System and Hedgehog Signaling in Neoangiogenesis Under Laser Photobiomodulation

“…Some studies have shown the role of LPBM in macrophage activity at the beginning of wound healing, but the presence of these cells have not yet been investigated in later stages of repair. 18 We can suggest that the inflammatory response that takes place in the early phase of wound repair indeed extends into later stages of this process, even when the wound is clinically healed.…”