Validated method for assessing the effects of blue light on human skin

ABSTRACT

The COVID pandemic caused an increase in virtual meetings & work from home scenarios that resulted in people spending increased time in front of computer screens & electronic devices. Studies have shown that blue light can produce cytotoxic effects, primarily through the production of reactive oxygen species & increased inflammation. However, the topic has been controversial with some studies claiming no adverse effects of blue light on the skin. Methods for testing the effects of blue light using in vitro testing models are lacking. Our work was conducted in order to develop a reproducible, validated testing method for assessing the effects of blue light on the skin. We designed a custom blue-light box that can be used to generate blue light at 460 nm wavelength. We performed a series of studies to optimize the dose and timing of the exposure & skin-culture conditions. Our work demonstrates that 6 hours of daily blue light for 5 consecutive days (total 30 J/cm2) produced a dose-and-time dependent decrease in skin health in 3D full thickness in vitro skin tissues. In addition, gene expression data showed an increase in the expression of genes that regulate inflammation and oxidative stress pathways (IL1A, IL6, CXCL8, COX2, CYP1B1, & NQO1) & a decrease in the expression of genes that maintain skin barrier and integrity (KRT1, KRT10, LOR, DSC and Collagen). Genes regulating skin aging & hydration including MMP1 & FLG were also regulated by exposure to blue light. Enzyme-linked immunoassays were performed to confirm changes in specific proteins. Exposure to blue light significantly increased 8-hydroxy-2' -deoxyguanosine, a marker for oxidative stress, & MMP1, markers for photoaging. Immunohistochemistry staining was performed to confirm changes in Collagen, Filaggrin & NQO1 protein expression in skin tissue. Our results showed that consistent blue light exposure produced skin damage via alterations in key biological pathways. This work provides a new, reproducible in vitro testing method for assessing the effects of blue light on human skin using gene expression, protein ELISA and IHC staining.