Norlén L, Nicander I, Lundsjö A, Cronholm T, Forslind B
Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden.
Arch Dermatol Res. 1998 Sep;290(9):508-16. doi: 10.1007/s004030050344.
The inner stratum corneum is likely to represent the location of the intact skin barrier, unperturbed by degradation processes. In our studies of the physical skin barrier a new high-performance liquid chromatography (HPLC)-based method was developed for the quantitative analysis of lipids of the inner stratum corneum. All main lipid classes were separated and quantitated by HPLC/light scattering detection (LSD) and the free fatty acid fraction was further analysed by gas-liquid chromatography (GLC). Mass spectrometry (MS) was used for peak identification and flame ionization detection (FID) for quantitation. Special attention was paid to the free fatty acid fraction since unsaturated free fatty acids may exert a key function in the regulation of the skin barrier properties by shifting the physical equilibrium of the multilamellar lipid bilayer system towards a noncrystalline state. Our results indicated that the endogenous free fatty acid fraction of the stratum corneum barrier lipids in essence exclusively consisted of saturated long-chain free fatty acids. This fraction was characterized as a very stable population (low interindividual peak variation) dominated by saturated lignoceric acid (C24:0, 39 molar%) and hexacosanoic acid (C26:0, 23 molar%). In addition, trace amounts of very long-chain (C32-C36) saturated and monounsaturated free fatty acids were detected in human forearm inner stratum corneum. Our analysis method gives highly accurate and precise quantitative information on the relative composition of all major lipid species present in the skin barrier. Such data will eventually permit skin barrier model systems to be created which will allow a more detailed analysis of the physical nature of the human skin barrier.
角质层内层可能代表完整皮肤屏障的位置，未受降解过程的干扰。在我们对物理皮肤屏障的研究中，开发了一种基于高效液相色谱（HPLC）的新方法，用于对角质层内层脂质进行定量分析。所有主要脂质类别通过HPLC/光散射检测（LSD）进行分离和定量，游离脂肪酸部分通过气液色谱（GLC）进一步分析。质谱（MS）用于峰鉴定，火焰离子化检测（FID）用于定量。特别关注游离脂肪酸部分，因为不饱和游离脂肪酸可能通过将多层脂质双层系统的物理平衡向非晶态转变，在皮肤屏障特性的调节中发挥关键作用。我们的结果表明，角质层屏障脂质的内源性游离脂肪酸部分基本上仅由饱和长链游离脂肪酸组成。该部分的特征是非常稳定（个体间峰变化低），以饱和木蜡酸（C24:0，39摩尔%）和二十六烷酸（C26:0，23摩尔%）为主。此外，在人前臂角质层内层中检测到微量的极长链（C32 - C36）饱和和单不饱和游离脂肪酸。我们的分析方法提供了关于皮肤屏障中所有主要脂质种类相对组成的高度准确和精确的定量信息。这些数据最终将允许创建皮肤屏障模型系统，从而能够对人类皮肤屏障的物理性质进行更详细的分析。
