Downing D T, Stewart M E, Wertz P W, Colton S W, Abraham W, Strauss J S
J Invest Dermatol. 1987 Mar;88(3 Suppl):2s-6s. doi: 10.1111/1523-1747.ep12468850.
The stratum corneum lipids, responsible for the epidermal water barrier, consist principally of ceramides, cholesterol, cholesteryl sulfate, and free fatty acids. These lipids are arranged in multiple intercellular lamellae that provide an efficient water barrier because of the crystalline array of the straight and predominantly saturated lipid chains. Interlamellar linkages provided by lipids based on 30-carbon omega-hydroxyacids may be responsible for holding together the intercellular lamellae as well as for assembly of the lamellar granules of the granular cells. The normally ordered exfoliation of corneocytes as they arrive at the surface seems to require hydrolysis of the cholesteryl sulfate to free cholesterol. The sebaceous glands secrete continuously, producing sebum that consists predominantly of triglycerides, wax esters, and squalene. High rates of sebum production per sebocyte result in low levels of linoleate in the sebaceous esters, subjecting the follicular epithelium to essential fatty acid deficiency and the characteristic hyperkeratosis that results in comedo formation. Suppression of sebum production by drugs elevates sebum linoleate concentration and relieves follicular hyperkeratosis. Thus, sebum continues to be a prime suspect in the crime of acne. Low levels of sebaceous gland activity are not correlated with the occurrence of dry skin.
角质层脂质负责表皮的水屏障功能，主要由神经酰胺、胆固醇、硫酸胆固醇酯和游离脂肪酸组成。这些脂质排列在多个细胞间层中，由于直链且主要为饱和脂质链的晶体排列，形成了有效的水屏障。基于30碳ω - 羟基酸的脂质提供的层间连接可能负责将细胞间层维系在一起，以及负责颗粒细胞层状颗粒的组装。角质形成细胞到达表面时正常有序的脱落似乎需要硫酸胆固醇酯水解为游离胆固醇。皮脂腺持续分泌，产生的皮脂主要由甘油三酯、蜡酯和角鲨烯组成。每个皮脂腺细胞的皮脂分泌率高导致皮脂酯中亚油酸水平低，使毛囊上皮细胞出现必需脂肪酸缺乏以及导致粉刺形成的特征性角化过度。药物抑制皮脂分泌可提高皮脂中亚油酸浓度并缓解毛囊角化过度。因此，皮脂仍然是痤疮发病的主要嫌疑因素。皮脂腺活性低与干性皮肤的发生无关。
