Investigation of the effects of photobiomodulation on exosomal micro-rnas in an in-vitro oxidative stress model

Application of low-level laser therapy (LLLT)/ photobiomodulation, has proven to have beneficial outcomes on Alzheimer's disease (AD). AD, the most common neurodegenerative disease and most common type of dementia, is characterized by depositions of extracellular neuritic plaques and intraneuronal neurofibrillary tangles (NFTs). The neuritic plaques consist of amyloid-β (Aβ) peptides and the NFTs consist of hyperphosphorylated tau protein. One of the driving forces of these accumulations in AD is oxidative stress. Oxidative stress is a phenomenon caused by an imbalance between the production of reactive oxygen species (ROS) and antioxidants in the favor of the oxidants. Oxidative stress can trigger AD pathology by altering the expression of potent non-coding RNAs known as microRNAs (miRNAs). The dysregulated miRNAs can target messenger RNAs that are involved in the initiation of AD. As miRNAs can be carried by exosomes, a type of extracellular vesicle, exosomal miRNAs can be considered the mediators of the crosstalk between oxidative stress and AD. This study investigates the effect of LLLT on the expression of exosomal miRNAs in an oxidative stress-induced human neuroblastoma SH-SY5Y cell line. The findings demonstrate that laser at 660nm with energy densities 1J/cm2 and 3J/cm2 has a pro-survival effect on oxidative stress-induced cells. In addition, exosomal hsa-miR-193b-3p, hsa-miR-193b-5p, and hsa-miR-375-3p, which have roles in AD pathology, were significantly increased in expression in exosomes after oxidative stress induction and laser irradiation at 660nm, 3J/cm2. Only hsa-miR-193b-3p also showed to have a significant increase in expression in laser irradiation at 1J/cm2.