Zwara Agata, Wertheim-Tysarowska Katarzyna, Mika Adriana
Department of Environmental Analysis, Faculty of Chemistry, University of Gdansk, Gdansk, Poland.
Department of Medical Genetics, Institute of Mother and Child, Warsaw, Poland.
Front Med (Lausanne). 2021 Aug 23;8:730855. doi: 10.3389/fmed.2021.730855. eCollection 2021.
The skin is a flexible organ that forms a barrier between the environment and the body's interior; it is involved in the immune response, in protection and regulation, and is a dynamic environment in which skin lipids play an important role in maintaining homeostasis. The different layers of the skin differ in both the composition and amount of lipids. The epidermis displays the best characteristics in this respect. The main lipids in this layer are cholesterol, fatty acids (FAs) and ceramides. FAs can occur in free form and as components of complex molecules. The most poorly characterized FAs are very long-chain fatty acids (VLCFAs) and ultra long-chain fatty acids (ULCFAs). VLCFAs and ULCFAs are among the main components of ceramides and are part of the free fatty acid (FFA) fraction. They are most abundant in the brain, liver, kidneys, and skin. VLCFAs and ULCFAs are responsible for the rigidity and impermeability of membranes, forming the mechanically and chemically strong outer layer of cell membranes. Any changes in the composition and length of the carbon chains of FAs result in a change in their melting point and therefore a change in membrane permeability. One of the factors causing a decrease in the amount of VLCFAs and ULCFAs is an improper diet. Another much more important factor is mutations in the genes which code proteins involved in the metabolism of VLCFAs and ULCFAs-regarding their elongation, their attachment to ceramides and their transformation. These mutations have their clinical consequences in the form of inborn errors in metabolism and neurodegenerative disorders, among others. Some of them are accompanied by skin symptoms such as ichthyosis and ichthyosiform erythroderma. In the following review, the structure of the skin is briefly characterized and the most important lipid components of the skin are presented. The focus is also on providing an overview of selected proteins involved in the metabolism of VLCFAs and ULCFAs in the skin.
皮肤是一种柔韧的器官，在环境与身体内部之间形成一道屏障；它参与免疫反应、保护和调节过程，是一个动态环境，皮肤脂质在维持体内平衡方面发挥着重要作用。皮肤的不同层在脂质的组成和含量上存在差异。表皮在这方面表现出最佳特性。该层的主要脂质是胆固醇、脂肪酸（FAs）和神经酰胺。FAs可以以游离形式存在，也可以作为复杂分子的组成部分。特征描述最少的FAs是极长链脂肪酸（VLCFAs）和超长链脂肪酸（ULCFAs）。VLCFAs和ULCFAs是神经酰胺的主要成分之一，也是游离脂肪酸（FFA）部分的一部分。它们在大脑、肝脏、肾脏和皮肤中含量最为丰富。VLCFAs和ULCFAs负责细胞膜的刚性和不透性，形成细胞膜机械和化学性质强大的外层。FAs碳链组成和长度的任何变化都会导致其熔点改变，进而导致膜通透性改变。导致VLCFAs和ULCFAs数量减少的一个因素是饮食不当。另一个更重要的因素是编码参与VLCFAs和ULCFAs代谢的蛋白质的基因突变——涉及它们的延长、与神经酰胺的连接以及它们的转化。这些突变会以先天性代谢错误和神经退行性疾病等形式产生临床后果。其中一些伴有皮肤症状，如鱼鳞病和鱼鳞病样红皮病。在以下综述中，简要描述了皮肤的结构，并介绍了皮肤最重要的脂质成分。重点还在于概述皮肤中参与VLCFAs和ULCFAs代谢的选定蛋白质。
