Transcriptomic analysis of human dermal fibroblast cells reveals potential mechanisms underlying the protective effects of visible red light against damage from ultraviolet B light

Abstract

Background: Ultraviolet B (UVB) radiation is a major cause of skin photodamage, including the damage associated with photodermatoses, aging, and cancer. Although many studies have shown that red light has photoprotective effects on skin, the mechanisms underlying these effects are still poorly understood. Objective: The aim of this study was to identify the photoprotective effects of visible red light against UVB-induced skin damage in normal human dermal fibroblast cells using a transcriptomic approach. Methods: Next-generation sequencing-based transcriptomic analyses were used to profile transcriptomic alterations and identify genes that are differentially expressed by visible red light and by UVB exposure. To understand the biological networks among identified genes, a literature-based biological pathway analysis was performed. Quantitative real-time polymerase chain reaction assays were used for mRNAlevel validation of selected key genes. Results: We observed that visible red light contributes to skin cell protection against UVB by modulating gene expression that enhances the adaptive response to redox and inflammatory balancing and by upregulating genes involved in DNA excision repair processes. We also identified that several key genes in the red light-induced biological network were differentially regulated. Conclusions: Visible red light enhanced the UVB-protective effects in normal human skin cells via the transcriptomic modulation of genes involved in cell-protective processes. Our findings from this nextgeneration sequencing analysis may lead to a better understanding of the cytoprotective effects of visible red light and provide direction for further molecular or mechanistic studies.

Effects of visible light on mechanisms of skin photoaging

“…The propensity of melanin and carotenoids to absorb BL over other VL wavelengths suggests BL absorption to be a consequence of evolutionary selection 12 . Conversely, longer wavelengths of VL in the yellow and red spectrum, are often reported as protective against photoaging 36,42 . Radiation dose also matters, regardless of wavelength, as high doses and cumulative exposure of red light can be deleterious, while low doses of BL or broad VL/VL+IR can be protective 16,25,29,43 .…”

“…In contrast, BL (425 nm) irradiation of PMA‐treated keratinocytes did not demonstrate these beneficial effects 41 . Moreover, pretreatment with red light may be photoprotective 42 . Red light (620‐690 nm; max 660 nm; 60 J/cm 2 ) was found to upregulate genes involved in response to UVB (312 nm; 0.1 J/cm 2 )‐induced oxidative stress, DNA damage, inflammation and wound healing in human dermal fibroblasts 42 .…”

“…Moreover, pretreatment with red light may be photoprotective 42 . Red light (620‐690 nm; max 660 nm; 60 J/cm 2 ) was found to upregulate genes involved in response to UVB (312 nm; 0.1 J/cm 2 )‐induced oxidative stress, DNA damage, inflammation and wound healing in human dermal fibroblasts 42 . While many studies demonstrate red light to be protective against photoaging, higher doses can potentially be toxic.…”

Comparison of red light and blue light therapies for mild‐to‐moderate acne vulgaris: A randomized controlled clinical study

“…19 Therefore, longer exposure to high-energy blue light can also increase the amount of DNA damage, cell and tissue death, and injury, causing skin barrier damage, hyperpigmentation, and photoaging. 20 Conversely, red light is often reported to prevent photoaging, 21 but attention needs to be paid to the potential harm that long-term exposure to high doses of red light.…”

Various biological effects of solar radiation on skin and their mechanisms: implications for phototherapy

“…It has been shown that red light protects against UV-induced DNA damage, which enhances the physical interaction of apyrimidinic endonuclease 1 (APE1) with GADD45A, a protein that plays an important role in base excision repair (Kim et al 2017 ). Furthermore, red light contributes to protecting human dermal fibroblasts against UVB by regulating the expression level of specific genes related to redox balancing and DNA base excision repair (Kim et al 2019 ). These data indicate that red light may be beneficial for the skin and potentially useful in photo-medical applications, such as accelerating wound repair.…”