Johnson & Johnson Santé Beauté France, 1 rue Camille Desmoulins, Issy-les-Moulineaux, France.
U-PSud, Univ. Paris-Saclay, Lip(Sys)2 Chimie Analytique Pharmaceutique, EA7357, UFR-Pharmacy, Châtenay-Malabry, France.
Int J Dermatol. 2021 Jul;60(7):834-839. doi: 10.1111/ijd.15417. Epub 2021 Feb 10.
The study objective was to examine if age and chronic environmental exposure affect the water content and the composition of the natural moisturizing factors (NMFs) of the stratum corneum (SC).
Forty healthy Caucasian women 18-70 years of age were recruited. Measurements were done on the cheek and on two skin sites on the arm (one relatively protected and one exposed to environmental factors). SC water content and NMF composition were measured by Raman confocal microspectroscopy.
The SC water content was gradually reduced with age, reaching statistically significant levels only on the exposed arm site. The SC water content remained higher on the face than on the two arm sites throughout the ages tested. The age-dependent concentration changes of various amino acids were species-specific, potentially indicating different protein sources. Interestingly, on the arm sites, the sum of decreasing amino acid concentrations is compensated by the sum of those increasing, resulting in constant total amino acid content. However, on the face, the total amino acid content statistically increased with age potentially relating to the declining cell turnover rates. The lactate content was higher on the face for all ages and statistically decreased on both arm sites.
Both chronological aging and chronic exposure to environmental factors mildly affect SC hydration, while they have variable effects in the concentrations of NMF components. The dynamics of NMF composition may at least partially explain the age-related changes in SC hydration.
本研究旨在探讨年龄和慢性环境暴露是否会影响角质层（SC）的含水量和天然保湿因子（NMFs）的组成。
招募了 40 名 18-70 岁的健康白种女性。在脸颊和手臂的两个皮肤部位（一个相对受保护，一个暴露于环境因素）进行 SC 水分含量和 NMF 组成的测量。采用共焦拉曼显微镜测量 SC 水分含量和 NMF 组成。
SC 水分含量随年龄逐渐降低，仅在暴露的手臂部位达到统计学显著水平。在测试的所有年龄段，面部 SC 水分含量均高于两个手臂部位。各种氨基酸的年龄相关浓度变化具有种属特异性，可能表明不同的蛋白质来源。有趣的是，在手臂部位，减少的氨基酸浓度之和被增加的氨基酸浓度之和补偿，导致总氨基酸含量保持不变。然而，在面部，总氨基酸含量随年龄呈统计学增加，可能与细胞更新率下降有关。对于所有年龄段，面部的乳酸含量均较高，并且在两个手臂部位的含量均呈统计学下降。
时间性老化和慢性环境暴露都会轻度影响 SC 水合作用，而对 NMF 成分的浓度有不同的影响。NMF 组成的动态变化至少可以部分解释 SC 水合作用随年龄的变化。
