A photobiomodulation approach (1068 nm) for COVID-19 treatment: validation and mechanism

Photobiomodulation therapy (PBMT) uses low-intensity red to near-infrared (NIR) light to stimulate, enhance and heal cell and tissue function. Previous studies have indicated that the wavelength 1068 nm can protect cells of the central nervous system (CNS), as well as improve cognitive function in dementia patients and ageing individuals. The primary aim of this project was to utilise both in vitro and in vivo model systems to explore responses to 1068 nm PBMT and assess whether PBMT is a viable therapeutic approach for the neurological symptoms of COVID-19. In vivo, PBMT extended the lifespan of wildtype and PINK1 mutant Drosophila melanogaster following dietary stress with SARS-CoV-2 spike-protein: relevant as COVID-19 may exacerbate Parkinson’s Disease symptoms and mortality. Wildtype flies exhibited a PBMT-induced elevation in reactive oxygen species (ROS), possibly representing a preconditioning hormesis response. In vitro, PBMT modulated ACE2 receptor localisation and induced insult-dependent changes in key cellular and inflammatory responses, including mitochondrial viability (32% increase in unstressed neurons), calcium signalling and TNF- (92% reduction following PBMT in microglia). Notably, the inflammatory signalling molecules ROS and NF-B showed protective preconditioning responses following PBMT on unstressed cells, including a 15-fold ROS increase in neurons, but displayed significant anti-inflammatory effects when PBMT was applied to stressed cells. This insult-dependent response to PBMT is a novel finding, both for the 1068 nm wavelength and in the context of SARS-CoV-2. 1068 nm PBMT also demonstrated enhanced neuronal and glial proliferation under various conditions. In conclusion, this study provides solid evidence base for the effectiveness of 1068 nm irradiation following SARS-CoV-2 infection of the CNS, involving receptor re-distribution and adaptable inflammatory responses. This supports the use of PBMT for addressing the neurological complications of COVID-19, although further work is required to determine optimal dosing parameters, molecular mechanisms, and clinical efficacy.