Non‐mammalian Hosts and Photobiomodulation: Do All Life‐forms Respond to Light?

Abstract

Photobiomodulation (PBM), also known as low-level laser (light) therapy, was discovered over 50 years ago, but only recently has it been making progress toward wide acceptance. PBM originally used red and near-infrared (NIR) lasers, but now other wavelengths and non-coherent light-emitting diodes (LEDs) are being explored. The almost complete lack of side effects makes the conduction of controlled clinical trials relatively easy. Laboratory research has mainly concentrated on mammalian cells (normal or cancer) in culture, and small rodents (mice and rats) as models of different diseases. A sizeable body of work was carried out in the 1970s and 1980s in Russia looking at various bacterial and fungal cells. The present review covers some of these studies and a recent number of papers that have applied PBM to so-called "model organisms." These models include flies (Drosophila), worms (Caenorhabditis elegans), fish (zebrafish) and caterpillars (Galleria). Much knowledge about the genomics and proteomics, and many reagents for these organisms already exist. They are inexpensive to work with and have lower regulatory barriers compared to vertebrate animals. Other researchers have studied different models (snails, sea urchins, Paramecium, toads, frogs and chickens). Plants may respond to NIR light differently from visible light (photosynthesis and photomorphogenesis) but PBM in plants has not been much studied. Veterinarians routinely use PBM to treat non-mammalian patients. The conclusion is that red or NIR light does indeed have significant biologic effects conserved over many different kingdoms, and perhaps it is true that "all life-forms respond to light."

Photobiomodulation Affects Key Cellular Pathways of all Life‐Forms: Considerations on Old and New Laser Light Targets and the Calcium Issue

“…In fact, the review by Hamblin et al . clearly shows how PBM affects the cell behavior from bacteria up to vertebrate animals thought protozoa, fungi, invertebrate deuterostomes ( i.e . Paracentrotus lividus ) and protostomes ( i.e .…”

“…In addition, with regard to the repeatability of the PBM effects on all life‐forms (for instance, the increment of cell proliferation as reviewed by Hamblin et al . ), it is not a coincidence that the specific chromophore‐target of PBM, the complex IV, is the cytochrome c oxidase of the mitochondrial respiratory chain of eukaryotes, which is presented also as large transmembrane protein complex in bacteria . Therefore, the electron transfers can similarly take place on the inner part of the cell membrane of prokaryotic cells or in specialized protein complexes in the inner membrane of the mitochondria of eukaryotic cells, and the generated electrochemical gradient makes ATP by oxidative phosphorylation.…”

“…However, not all phenomena observed in PBM seem to be due to that interplay; as reported by Hamblin et al . “in recent years, it has become apparent that there are other chromophores operating in different regions of the spectrum”. The most important alternative photoacceptors appear to be water and the transient receptor potential (TRP) ion channels; the latter can be activated by light or by heating up microscopic regions of water in the channel and give rise to changes in cytosolic and mitochondrial calcium levels .…”

1064 nm Nd:YAG laser light affects transmembrane mitochondria respiratory chain complexes

“…In both the organelles, the same set of functional genes for electron transport chain proteins is encoded; they show common stereo‐selective biochemical pathways and their molecular biology/bioenergetics share basic chemical processes . Authors pointed out that cytochrome‐c‐oxidase or complex IV, which is present also as large transmembrane protein complex in bacteria , is the specific chromophore's target of PBM at the red (600‐700 nm) and NIR (760‐900 nm) wavelength regions . Conversely, Complexes I and II are not affected by those wavelengths, while at 808 nm, the complex III is poorly stimulated by higher energies .…”

“…In addition, the light–chromophore interaction is reflected in modulation of adenosine triphosphate (ATP) production . These evidences explain because, in the range of 600 to 810 nm, PBM affects the cell behavior from bacteria and protozoa up to animals and humans and have been the most employed wavelengths for PBM . In recent years, it was suggested that the infrared region of the spectrum could influence other chromospheres, despite the interaction by wavelengths higher than 900 nm, and particularly 1064 nm, with mitochondrial chromophores was not clearly demonstrated .…”