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Published on: December 30, 2021
Evaluation of laser-photobiomodulation different irradiation parameters on macrophages (RAW 264.7) inflammatory
Guilherme Aparecido Monteiro Duque da Fonseca1, Denise Carvalho Roxo2, Mariana Moreira Figueira2
1Guarulhos University, Guarulhos, Brazil. Guilherme.fonseca1210@gmail.com.
Purpose:
Macrophages are pivotal cells in the inflammatory process, and their functions can be modulated by laser irradiation. However, there is no consensus in the literature about Laser-photobiomodulation (L-PBM) parameters that are more suited to stimulate or inhibit them. The goal of this research is to contribute to the understanding of the effects of different L-PBM protocols on inflammatory mediators' production/inhibition and cell viability of macrophage cells in vitro.
Materials And Methods:
The macrophages cells (RAW 264.7) were divided into two groups: LPS-stimulated (Lipopolysaccharide from Escherichia coli) and non-LPS-stimulated. Each group was subdivided into non-irradiated and irradiated groups. The irradiated group was further divided into: 660 nm, 1 J, 10s; 660 nm, 2 J, 20s; 660, 3 J, 30s; 808 nm 1 J, 10s; 808 nm, 2 J, 20s; 808, 3 J, 30s groups. To all groups and subgroups, a negative (non-irradiated) group was added. All groups and subgroups were evaluated for cell viability, Nitric oxide (NO), interleukin-6 (IL-6) and Tumor Necrosis Factor- α (TNF-α) production.
Results:
The results indicated that macrophages irradiated at 660 nm and 808 nm, operating in 1 J, 10s; 2 J, 20s and 3 J, 30s did not change NO, TNF-α and IL-6 production nor cell Viability in non-LPS groups. However, in LPS-stimulated macrophages, a significant stimulatory effect on NO production was observed after laser-irradiation with 660 nm for 2 J, 20s. This NO-stimulatory effect was not observed in the 880 nm irradiated group. LPS-activated macrophages and L-PBM irradiation at 660 nm and 808 nm also resulted in significant inhibitory effects on TNF-α and IL-6 production after 2 J, 20s irradiation. However, TNF-α and IL-6 inhibition using 1 J, 10s was achieved only in 660 nm group.
Conclusion:
Our findings suggested that, if other parameters are fixed, time and related fluence/energy delivery are important dimensions to consider in L-PBM-production/inhibition on the inflammatory mediators tested. The NO synthesis was more prone to be modulated by a specific wavelength (660 nm) and a broader time-range inhibition of TNF-α and IL-6 was observed in 660 nm groups. Cell viability was not changed in any parameter tested.
Insights
Laser-photobiomodulation (L-PBM) can modulate macrophage inflammatory mediator production. Specific parameters, particularly at 660 nm, influenced nitric oxide (NO) production and inhibited interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) without affecting cell viability.
Area of Science:
- Biomedical Engineering
- Immunology
- Photomedicine
Background:
- Macrophages are key immune cells involved in inflammation.
- Laser-photobiomodulation (L-PBM) shows potential for modulating macrophage activity.
- Optimal L-PBM parameters for macrophage modulation remain unclear.
Purpose of the Study:
- To investigate the effects of different L-PBM protocols on macrophage inflammatory mediator production and cell viability.
- To determine specific L-PBM parameters for stimulating or inhibiting inflammatory responses in macrophages.
- To contribute to understanding L-PBM's role in inflammatory processes.
Main Methods:
- RAW 264.7 macrophage cells were divided into LPS-stimulated and non-LPS-stimulated groups.
- Irradiated groups received L-PBM at 660 nm or 808 nm with varying energy (1-3 J) and time (10-30s).
- Assessed cell viability, nitric oxide (NO), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) production.
Main Results:
- L-PBM did not alter NO, TNF-α, or IL-6 production or cell viability in non-LPS-stimulated macrophages.
- In LPS-stimulated macrophages, 660 nm L-PBM (2 J, 20s) significantly stimulated NO production.
- L-PBM at both wavelengths (660 nm and 808 nm) with 2 J, 20s significantly inhibited TNF-α and IL-6 production.
Conclusions:
- Time and energy delivery are critical L-PBM parameters for modulating inflammatory mediators.
- Nitric oxide (NO) synthesis is particularly sensitive to 660 nm wavelength.
- 660 nm L-PBM demonstrated broader inhibition of TNF-α and IL-6, with no observed impact on cell viability.
