Ultraviolet light degrades the mechanical and structural properties of human stratum corneum
Ultraviolet light degrades the mechanical and structural properties of human stratum corneum
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DOI：
10.1016/j.jmbbm.2019.103391
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发表时间：
2019-12-01
影响因子：
3.9
通讯作者：
German, Guy K.
中科院分区：
文献类型：
--
作者：
Lipsky, Zachary W.;German, Guy K.
人体皮肤长时间暴露在阳光下会造成光损伤，从而导致皱纹提早出现，并增加组织的脆弱性。虽然太阳紫外线（UV）被认为具有最具破坏性的影响，但最有害的紫外线范围仍然是一个重大争论的话题。在这项研究中，我们通过量化暴露于不同紫外线范围和剂量如何影响人类角质层（最浅层皮肤）的力学和结构特性，向阐明生物力学光老化效应迈出了第一步。力学试验表明，在UVA （365 nm）、UVB （302 mu）或UVC （265 nm）下，以高达4000 J/cm(2)的剂量照射离体SC，可显著改变其弹性模量、断裂应力、断裂应变和断裂功。在同等入射剂量下，UVC对SC的降解作用最大。然而，在扣除入射光的反射和透射分量后，SC吸收的光子能量与组织断裂的能量成本之间出现了一个广义的标度定律。这种关系表明，没有一种紫外线范围比另一种更具有破坏性。相反，吸收的紫外线能量的大小决定了组织机械完整性的退化。随后的结构研究是为了阐明这种机械退化的原因。紫外线吸收随细胞间纤维蛋白1 （desmoglin 1，角质细胞-细胞连接的一种成分）远离细胞间部位的空间分散程度而变化。结合这两个标度定律，我们建立了一个能够从dsg1色散预测紫外线诱导的组织机械完整性的力学结构模型。
Prolonged exposure of human skin to sunlight causes photodamage, which induces the early onset of wrinkles and increased tissue fragility. While solar ultraviolet (UV) light is considered to have the most damaging effect, the UV range that is most harmful remains a topic of significant debate. In this study, we take a first step towards elucidating biomechanical photoageing effects by quantifying how exposure to different UV ranges and dosages impacts the mechanical and structural properties of human stratum corneum (SC), the most superficial skin layer. Mechanical testing reveals that irradiation of isolated human SC to UVA (365 nm), UVB (302 mu), or UVC (265 nm) light with dosages of up to 4000 J/cm(2) notably alters the elastic modulus, fracture stress, fracture strain, and work of fracture. For equivalent incident dosages, UVC degrades SC the greatest. However, upon discounting reflected and transmitted components of the incident light, a generalized scaling law relating the photonic energy absorbed by the SC to the energy cost of tissue fracture emerges. This relationship indicates that no one UV range is more damaging than another. Rather, the magnitude of absorbed UV energy governs the degradation of tissue mechanical integrity. Subsequent structural studies are performed to elucidate the cause of this mechanical degradation. UV absorption scales with the spatial dispersion of desmoglein 1 (Dsg 1), a component of corneocyte cell-cell junctions, away from intercellular sites. Combining both scaling laws, we establish a mechanical-structural model capable of predicting UV induced tissue mechanical integrity from Dsg 1 dispersion.