Divisions of Musculoskeletal and Dermatological Sciences, The University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom.
Cell Matrix Biology & Regenerative Medicine, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom.
Curr Med Chem. 2018;25(40):5503-5511. doi: 10.2174/0929867324666171106164916.
A competent epidermal barrier is crucial for terrestrial mammals. This barrier must keep in water and prevent entry of noxious stimuli. Most importantly, the epidermis must also be a barrier to ultraviolet radiation (UVR) from the sunlight. Currently, the effects of ultraviolet radiation on epidermal barrier function are poorly understood. However, studies in mice and more limited work in humans suggest that the epidermal barrier becomes more permeable, as measured by increased transepidermal water loss, in response UVR, at doses sufficiently high to induce erythema. The mechanisms may include disturbance in the organisation of lipids in the stratum corneum (the outermost layer of the epidermis) and reduction in tight junction function in the granular layer (the first living layer of the skin). By contrast, suberythemal doses of UVR appear to have positive effects on epidermal barrier function. Topical sunscreens have direct and indirect protective effects on the barrier through their ability to block UV and also due to their moisturising or occlusive effects, which trap water in the skin, respectively. Some topical agents such as specific botanical extracts have been shown to prevent the loss of water associated with high doses of UVR. In this review, we discuss the current literature and suggest that the biology of UVR-induced barrier dysfunction, and the use of topical products to protect the barrier, are areas worthy of further investigation.
一个功能健全的表皮屏障对于陆生哺乳动物至关重要。这个屏障必须能够保持水分，防止有害物质进入，最重要的是，它还必须能够阻挡阳光中的紫外线（UVR）。目前，人们对紫外线辐射对表皮屏障功能的影响知之甚少。然而，在小鼠中的研究以及在人类中更为有限的研究表明，表皮屏障的通透性会增加，这可以通过经表皮水分丢失的增加来衡量，这种增加是对足以引起红斑的 UVR 剂量的反应。其机制可能包括角质层（表皮的最外层）中脂质排列的紊乱以及颗粒层（皮肤的第一层活细胞）中紧密连接功能的降低。相比之下，亚红斑剂量的 UVR 似乎对表皮屏障功能有积极影响。防晒霜通过其阻挡 UV 的能力以及保湿或封闭作用（分别将水分困在皮肤中）对屏障具有直接和间接的保护作用。一些局部用制剂，如特定的植物提取物，已被证明可以防止与高剂量 UVR 相关的水分流失。在这篇综述中，我们讨论了当前的文献，并提出 UVR 诱导的屏障功能障碍的生物学以及使用局部产品来保护屏障是值得进一步研究的领域。
