Akimoto K, Yoshikawa N, Higaki Y, Kawashima M, Imokawa G
Department of Dermatology, Tokyo Women's Medical College, Japan.
J Dermatol. 1993 Jan;20(1):1-6. doi: 10.1111/j.1346-8138.1993.tb03820.x.
Sphingolipids, a major constituent of intercellular lipids, are an important determinant for both water-holding and permeability barrier function in the stratum corneum. To assess the pathogenic role of sphingolipids in the stratum corneum of dry skin disorders such as xerosis and asteatotic eczema in leg skin, ceramides were quantified by thin layer chromatography after n-hexane/ethanol extraction of resin-stripped stratum corneum and evaluated as micrograms/mg stratum corneum. In healthy leg skin (n = 49), there was age-related decline in the total ceramide, whereas xerosis (n = 25) and asteatotic eczema (n = 16) suffering significantly reduced water-holding properties, exhibited no definite decrease, rather slight increase in ceramide quantity with the same composition of each individual ceramide as compared to healthy age-matched controls. These data indicate that the seemingly elevated level of ceramide is an artificial effect due to inflammatory processes which result from susceptibility to dryness. Analysis of sebum-derived lipids present in the stratum corneum revealed that there was a significant decline in free fatty acids in xerosis and asteatotic eczema as compared to age-matched healthy controls, and a similar decline in triglycerides in the above three groups when compared to younger controls. Although the observed decrease in the stratum corneum lipids may well explain the high incidence of winter dry skin in older people, the progression toward asteatotic eczema can not be accompanied solely by a decrease in ceramide quantity, suggesting that the evolution of xerotic skin is associated with other moisturizing factors and/or environmental stimuli.
鞘脂作为细胞间脂质的主要成分，是角质层中保水和渗透屏障功能的重要决定因素。为了评估鞘脂在干性皮肤疾病（如腿部皮肤干燥症和乏脂性湿疹）角质层中的致病作用，在对去除树脂的角质层进行正己烷/乙醇萃取后，通过薄层色谱法定量测定神经酰胺，并以微克/毫克角质层来评估。在健康的腿部皮肤（n = 49）中，总神经酰胺含量随年龄增长而下降，而干燥症（n = 25）和乏脂性湿疹（n = 16）患者的保水性能显著降低，与年龄匹配的健康对照相比，神经酰胺含量没有明显下降，反而略有增加，且各神经酰胺的组成相同。这些数据表明，神经酰胺水平看似升高是由对干燥敏感导致的炎症过程引起的人为效应。对角质层中存在的皮脂衍生脂质分析显示，与年龄匹配的健康对照相比，干燥症和乏脂性湿疹患者的游离脂肪酸显著下降，与年轻对照相比，上述三组的甘油三酯也有类似下降。尽管观察到的角质层脂质减少很可能解释了老年人冬季皮肤干燥的高发病率，但向乏脂性湿疹的进展不能仅伴随着神经酰胺数量的减少，这表明干性皮肤的演变与其他保湿因素和/或环境刺激有关。
