Photobiomodulation Mediates Neuroprotection against Blue Light Induced Retinal Photoreceptor Degeneration

• Published in: International journal of molecular sciences Vol. 21; no. 7; p. 2370
• Main Authors: Heinig, Nora, Schumann, Ulrike, Calzia, Daniela, Panfoli, Isabella, Ader, Marius, Schmidt, Mirko H H, Funk, Richard H W, Roehlecke, Cora
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 30.03.2020; MDPI
• Subjects: alpha-Crystallins - genetics; Animals; Apoptosis; Cellular stress response; Chains; Cytochrome-c oxidase; Degeneration; Electron transport; Energy metabolism; Female; Gene expression; Hypotheses; Infrared radiation; Infrared Rays - therapeutic use; Light therapy; Localization; low-level laser therapy; Low-Level Light Therapy - methods; Macular degeneration; Male; Mice, Inbred C57BL; Mitochondria; near-infrared light; Neuroprotection; Neuroprotection - radiation effects; Oxidative stress; Photoreceptor Cells, Vertebrate - metabolism; Photoreceptor Cells, Vertebrate - pathology; Photoreceptor Cells, Vertebrate - radiation effects; photoreceptor survival; Photoreceptors; Protein expression; Proteins; red light; Respiration; respiratory chain complexes; Retina; Retinal degeneration; Retinal Degeneration - genetics; Retinal Degeneration - pathology; Retinal Degeneration - therapy; Up-Regulation - radiation effects; Visual perception; near-infrared light; neuroprotection; respiratory chain complexes; photoreceptor survival; red light; low-level laser therapy; α-Crystallins; oxidative stress
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms21072370

Potent neuroprotective effects of photobiomodulation with 670 nm red light (RL) have been demonstrated in several models of retinal disease. RL improves mitochondrial metabolism, reduces retinal inflammation and oxidative cell stress, showing its ability to enhance visual function. However, the current knowledge is limited to the main hypothesis that the respiratory chain complex IV, cytochrome c oxidase, serves as the primary target of RL. Here, we demonstrate a comprehensive cellular, molecular, and functional characterization of neuroprotective effects of 670 nm RL and 810 nm near-infrared light (NIRL) on blue light damaged murine primary photoreceptors. We show that respiratory chain complexes I and II are additional PBM targets, besides complex IV, leading to enhanced mitochondrial energy metabolism. Accordingly, our study identified mitochondria related RL- and NIRL-triggered defense mechanisms promoting photoreceptor neuroprotection. The observed improvement of mitochondrial and extramitochondrial respiration in both inner and outer segments is linked with reduced oxidative stress including its cellular consequences and reduced mitochondria-induced apoptosis. Analysis of regulatory mechanisms using gene expression analysis identified upregulation that indicate enhanced production of proteins with protective functions that point to the rescued mitochondrial function. The results support the hypothesis that energy metabolism is a major target for retinal light therapy.