Proposed Mechanisms of Photobiomodulation or Low-Level Light Therapy

Photobiomodulation (PBM) also known as low-level laser (or light) therapy (LLLT), has been known for almost 50 years but still has not gained widespread acceptance, largely due to uncertainty about the molecular, cellular, and tissular mechanisms of action.

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Laser Photobiomodulation: Models and Mechanisms

The overwhelming clinical evidence of the clinical effectiveness of low level laser therapy (LLLT) therapy has been balanced by few reports of equivocal or nonefficacious studies.

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Mechanisms of action for light therapy: a review of molecular interactions

The implication of cytochrome c oxidase as the photoacceptor modulating light therapy is reviewed, as are the predominant hypotheses of the biochemical pathways involved in the stimulation of wound healing, cellular proliferation, production of transcription factors and other reported stimulatory effects.

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Optimal Laser Phototherapy Parameters for Pain Relief

Conclusions: The findings of meta-analysis indicate that laser phototherapy is highly effective for pain relief. Based on the analysis of parameters, total energy can be optimized to yield the largest effect on pain relief.

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Irradiation at 830nm Stimulates Nitric Oxide Production and Inhibits Pro-Inflammatory Cytokines in Diabetic Wounded Fibroblast Cells

Results show that irradiation of diabetic wounded fibroblast cells at 830nm with 5 J/cm2 has a positive effect on wound healing in vitro. There was a decrease in pro-inflammatory cytokines (IL-1b and TNF-a) and irradiation stimulated the release of ROS and NO due to what appears to be direct photochemical processes.

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Low-Level Laser Therapy Activates NF-kB via Generation of Reactive Oxygen Species in Mouse Embryonic Fibroblasts

Conclusion: We conclude that LLLT not only enhances mitochondrial respiration, but also activates the redox-sensitive NFkB signaling via generation of ROS. Expression of anti-apoptosis and pro-survival genes responsive to NFkB could explain many clinical effects of LLLT.

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Mitochondrial Mechanisms of Photobiomodulation in Context of New Data About Multiple Roles of ATP

Various cellular responses to visible and IR-A radiation have been studied for decades in the context of molecular mechanisms of laser phototherapy [also called photobiomodulation, low-level light therapy (LLLT)]. LLLT uses monochromatic and quasimonochromatic light in the optical region of *600–1,000nm to treat in a nondestructive and nonthermal fashion various soft-tissue and neurologic conditions

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Photobiomodulation of Matrix Metalloproteinases in Rat Calcaneal Tendons

Conclusions: The photobiomodulation protocol was able to reduce MMP-1 and MMP-13 levels in injured calcaneal tendons.

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Photobiomodulation at Multiple Wavelengths Differentially Modulates Oxidative Stress In Vitro and In Vivo

We found that the various wavelengths differentially modulate ROS production. In particular, the 660nm laser light increases ROS production when applied either before or after an oxidative stimulus. In contrast, the 970 nm laser light exerted a moderate antioxidant activity both in the saliva of OM patients and in both cell types. The most marked reduction in the levels of ROS was detected in cells exposed either to the 800 nm laser light or to the combination of the three wavelengths. Overall, our study demonstrates that PBM exerts different effects on the redox state of both PMNs and keratinocytes depending on the used wavelength and prompts the validation of a multiwavelength protocol in the clinical settings.

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Low-Intensity Visible and Near-Infrared Light-Induced Cell Signaling Pathways in the Skin

In PBM, skin cells are the first to absorb photons, triggering specific cell-signaling pathways through primary and secondary effectors, leading to enhanced cell repair and survival, notably in hypoxic or stressed cells.

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