A study into how ultraviolet radiation from the sun effects genes in the skin

Summary The sun emits two main types of ultraviolet radiation (UVR): UVB (~5%) and UVA (~95%). We know that UVR from the sun causes sunburn (inflammation) as well as many other adverse (negative) effects including weakening the skin's immunity, accelerated skin ageing and skin cancer. These effects are caused by UVR altering the activity (expression) of the skin's genes – the so‐called ‘transcriptome’. The behaviour of genes determines the body's response to external and potentially damaging stress. Studying skin transcriptome changes in vivo (in humans) can inform us about the pathways in skin cells that are activated after a single UVR exposure (dose). This knowledge is important to develop strategies to prevent the adverse effects of sunlight. In this study, the authors examined skin transcriptome response in seven healthy, fair‐skinned volunteers after doses of UVR than could easily be obtained during one day of a sun‐holiday. The authors show that doses of UVR typical in holiday situations results in marked changes of expression of thousands of skin genes. Most striking were genes involved in the turnover of the outermost layer of the skin (a protective response), inflammation, immune system responses and accelerated skin ageing. The higher the UVR dose, the larger number of affected genes. One very interesting observation was the suppression (dampening down) of the activity of a gene involved in vitamin D production, suggesting that the body has its own mechanism to control vitamin D toxicity (too much vitamin D) in skin. The study also showed that UVB was generally more effective than UVA at causing changes in gene expression, which is consistent with other studies that show that UVB is much more powerful than UVA at causing molecular and clinical changes in the skin. This is a summary of the study: Dose and time effects of solar‐simulated ultraviolet radiation on the in vivo human skin transcriptome Linked Article: Bustamante et al. Br J Dermatol 2020; 182:1458–1468