Guneri D, Voegeli R, Gurgul S J, Munday M R, Lane M E, Rawlings A V
UCL School of Pharmacy, 29-39 Brunswick Square, London, WC1N 1AX, UK.
DSM Nutritional Products Ltd., PO Box 2676, Bldg. 205/315, Basel, 4002, Switzerland.
Int J Cosmet Sci. 2018 Mar 23. doi: 10.1111/ics.12454.
The maturity of the corneocyte envelope (CE) provides information about the barrier functionality of the stratum corneum (SC). Corneocytes are enclosed by the CE, a protein-lipid matrix, contributing to mechanical resistance and hydrophobicity of the SC.
The aim of the work was to develop a novel and robust approach to characterize CE maturity based on rigidity, hydrophobicity and surface area. This offers an alternative approach to the Nile red staining and antigenicity of involucrin to characterize the CE. The photoexposed (PE) cheek and photoprotected (PP) post-auricular sites were selected for investigation.
Nine tape strips were obtained from the cheek and post-auricular sites of healthy Caucasians. CEs on the first and last tape strip were subjected to sonication to assess rigidity, and Nile red staining to determine hydrophobicity per unit surface area. In addition, the presence of involucrin and lipids was assessed to determine CE maturity by examination of the red/green pixel ratio, percentage of involucrin expressing CEs and alternatively the ratio of fluorescence density.
The CE rigidity was lower in the deeper SC layers of the cheek, whereas post-auricular CEs were mechanically more resistant. Post-auricular CEs from the superficial SC had a larger surface area with a stronger fluorescence signal than those from the cheek. Interestingly, those CEs from the deeper SC layers had similar surface areas in both anatomical sites but were significantly different in hydrophobicity. These three parameters can be summarized as a relative CE maturity index that expresses CE maturity more precisely with a higher sensitivity than the conventional involucrin and Nile red staining approach. CEs of the cheek surface are more mature than CEs in the deeper SC layer, whereas CEs obtained from the post-auricular surface are more mature than those from the cheek surface.
The combined method developed allows characterization of CE maturity based on hydrophobicity per unit surface area and rigidity rather than a simple ratio of lipid to involucrin. A more robust and sensitive measurement has therefore been developed addressing the limitations of earlier protocols.
角质形成细胞包膜（CE）的成熟度提供了有关角质层（SC）屏障功能的信息。角质形成细胞被CE（一种蛋白质 - 脂质基质）包裹，这有助于SC的机械抵抗力和疏水性。
这项工作的目的是开发一种基于硬度、疏水性和表面积来表征CE成熟度的新颖且稳健的方法。这为尼罗红染色和内披蛋白抗原性表征CE提供了一种替代方法。选择光暴露（PE）的脸颊和光保护（PP）的耳后部位进行研究。
从健康白种人的脸颊和耳后部位获取九条胶带条。对第一条和最后一条胶带条上的CE进行超声处理以评估硬度，并进行尼罗红染色以确定每单位表面积的疏水性。此外，通过检查红/绿像素比、表达内披蛋白的CE的百分比以及荧光密度比来评估内披蛋白和脂质的存在，以确定CE成熟度。
脸颊较深SC层中的CE硬度较低，而耳后CE在机械性能上更具抵抗力。来自浅表SC的耳后CE比来自脸颊的CE具有更大的表面积和更强的荧光信号。有趣的是，来自较深SC层的那些CE在两个解剖部位具有相似的表面积，但疏水性存在显著差异。这三个参数可以总结为一个相对CE成熟度指数，该指数比传统的内披蛋白和尼罗红染色方法更精确、更灵敏地表达CE成熟度。脸颊表面的CE比深层SC层中的CE更成熟，而从耳后表面获得的CE比从脸颊表面获得的CE更成熟。
所开发的组合方法允许基于每单位表面积的疏水性和硬度来表征CE成熟度，而不是简单的脂质与内披蛋白的比率。因此，针对早期方案的局限性开发了一种更稳健、更灵敏的测量方法。
