Estee Lauder Research Laboratories, 125 Pinelawn Road, Melville, NY, 11747, USA.
Environmental Medicine, New York University School of Medicine, 341 East 25th Street, New York,, NY, 10010, USA.
Int J Cosmet Sci. 2019 Dec;41(6):558-562. doi: 10.1111/ics.12572.
On a daily basis, the skin is exposed to many environmental stressors and insults. Over a 24-h natural cycle, during the day, the skin is focused on protection; while at night, the skin is focused on repairing damage that occurred during daytime and getting ready for the next morning. Circadian rhythm provides the precise timing mechanism for engaging those different pathways necessary to keep a healthy skin through clock genes that are present in all skin cells. The strongest clue for determining cellular functions timing is through sensing light or absence of light (darkness). Here, we asked the question if blue light could be a direct entrainment signal to skin cells and also disrupt their circadian rhythm at night. Through a reporter assay for per1 transcription, we demonstrate that blue light at 410 nm decreases per1 transcription in keratinocytes, showing that epidermal skin cells can sense light directly and control their own clock gene expression. This triggers cells to "think" it is daytime even at nighttime. Elsewhere, we measured different skin cell damage because of blue light exposure (at different doses and times of exposure) vs. cells that were kept in full darkness. We show an increase in ROS production, DNA damage and inflammatory mediators. These deleterious effects can potentially increase overall skin damage over time and ultimately accelerates ageing.
皮肤每天都会暴露在许多环境压力源和刺激物中。在 24 小时的自然周期中，白天皮肤专注于保护；而在晚上，皮肤则专注于修复白天发生的损伤，并为第二天早上做好准备。昼夜节律为参与那些保持健康皮肤所必需的不同途径提供了精确的时间机制，这些途径是通过存在于所有皮肤细胞中的时钟基因实现的。确定细胞功能时间的最强线索是通过感知光或无光（黑暗）。在这里，我们提出了一个问题，即蓝光是否可以成为皮肤细胞的直接同步信号，并在夜间扰乱它们的昼夜节律。通过 PER1 转录的报告基因分析，我们证明 410nm 的蓝光会降低角质形成细胞中 PER1 的转录，表明表皮皮肤细胞可以直接感知光，并控制自己的时钟基因表达。这会使细胞“认为”即使在夜间也是白天。在其他地方，我们测量了由于暴露在蓝光下（不同剂量和暴露时间）而导致的不同皮肤细胞损伤，以及那些处于完全黑暗中的细胞。我们发现 ROS 产生、DNA 损伤和炎症介质增加。这些有害影响可能会随着时间的推移增加皮肤整体损伤，并最终加速衰老。
