PMC

(A) MMP measured 1 hour after photobiomodulation. (B) Intracellular calcium measured within 1 minute after photobiomodulation. (C) Time course of ROS production. (D) MMP 1 hour after photobiomodulation, comparing 15mW/cm², 75mW/cm² of 980 nm at doses of 0.3 J/cm² and 3 J/cm². (E) ROS 1 hour after photobiomodulation, comparing 15mW/cm², 75mW/cm² of 980 nm at doses of 0.3 J/cm² and 3 J/cm². Data represent mean ± SEM. All data are expressed as percentage above control. (n=6 or 8; ^**P<0.01, ^***P<0.001)

Photobiomodulation increased the expression level of phosphorylated MerTK but not phosphorylated FAK. FAK and MerTK expression was measured by western blot. The quantification of the expression of phosphorylated FAK and phosphorylated MerTK was corrected by β-actin and total MerTK, respectively. A: Oxidative stress reduced phosphorylated FAK expression, and photobiomodulation did not change the expression of phosphorylated FAK. NAC increased the expression of phosphorylated FAK. B: Oxidative stress also reduced the expression of phosphorylated MerTK, and both photobiomodulation and NAC increased the oxidative stress-induced reduction of phosphorylated MerTK expression. The data are expressed as means ± SEM (n=4–10) *p<0.05 versus the H₂O₂ only group. In this point, we performed the statistical analysis between H₂O₂ only treated group and photobimodulation group. PBM: photobiomodulation; NAC: N-acetylcysteine.

Photobiomodulation enhanced the phagocytic activity in human retinal pigment epithelium cell cultures. A: Oxidative stress reduced the phagocytic activity, and photobiomodulation improved phagocytic activity induced by oxidative stress in hRPE cells. Scale bar=500 μm. B: Oxidative stress reduced the expression of phosphorylated MerTK, and photobiomodulation increased the oxidative stress-induced reduction of phosphorylated MerTK expression. The data are expressed as means ± SEM (n=6) **p<0.01 versus the H₂O₂ only group. In this point, we performed the statistical analysis between H₂O₂ only treated group and photobimodulation group. PBM: photobiomodulation.

Photobiomodulation reduced ROS production but did not change the cell viability or mitochondrial membrane potential. A: Cell viability was measured using a WST-8 assay kit. Cell viability was reduced by oxidative stress, and photobiomodulation did not change the cell viability compared to the H₂O₂ only group. In this point, we performed the statistical analysis between H₂O₂ only treated group and photobimodulation group. B: ROS production was measured using the general oxidative stress indicator, CM-H₂DCFDA. Oxidative stress significantly increased ROS generation, and photobiomodulation reduced ROS production. NAC used as a positive controls also reduced ROS production compared to the H₂O₂ only group. In this point, we performed the statistical analysis between H₂O₂ only treated group and photobimodulation group. C: Mitochondrial membrane potential was evaluated using JC-1 dye. Green fluorescence indicates the low mitochondrial membrane potential, and red fluorescence indicates the low mitochondrial membrane potential. Oxidative stress and photobiomodulation did not change the mitochondrial membrane potential. Scale bar=500 μm. The data are expressed as means ± SEM (n=5 or 6) *p<0.05, **p<0.01 versus the H₂O₂ only group. In this point, we performed the statistical analysis between H₂O₂ only treated group and photobimodulation group. PBM: photobiomodulation; NAC: N-acetylcysteine.