背景:表皮含有许多结构多样的神经酰胺,其形成皮肤渗透性屏障(皮肤屏障)。参与ω-O-酰基神经酰胺(酰基神经酰胺)和蛋白质结合的神经酰胺合成的基因中的突变会导致鱼鳞病。
目的:我们旨在阐明皮肤屏障损伤程度与由酰基神经酰胺合成基因突变引起的表皮神经酰胺谱变化之间的关系。
方法:敲除(KO)小鼠三种基因-脂肪酸(FA)ω-羟化酶Cyp4f39(人CYP4F22直系同源物),对FA延伸酶Elovl1和酰基辅酶A合成酶Fatp4进行了经皮失水测量,甲苯胺蓝染色,和表皮神经酰胺通过液相色谱和串联质谱分析。
结果:在Cyp4f39KO小鼠中,经表皮失水最高,其次是Elovl1KO和Fatp4KO小鼠,而Cyp4f39KO小鼠也显示出最强程度的甲苯胺蓝染色。在Cyp4f39KO,Elovl1KO,和Fatp4KO小鼠,酰基神经酰胺水平为0.6%,1.6%,12%,分别,在野生型小鼠中。蛋白质结合的神经酰胺水平为0.2%,30%,33%,分别,在野生型小鼠中。我们还观察到Cyp4f39KO小鼠几乎完全不存在ω-羟基神经酰胺,Elovl1KO小鼠的总神经酰胺水平降低,FA部分缩短,Fatp4KO小鼠中羟基化神经酰胺水平增加和FA部分略微缩短。
结论:在这三种菌株中,蛋白结合神经酰胺水平的降低程度可能与皮肤屏障缺陷的严重程度有关。然而,还涉及每个KO菌株特有的降低的酰基神经酰胺水平和神经酰胺组成的其他变化。
BACKGROUND: The epidermis contains many structurally diverse ceramides, which form the skin permeability barrier (skin barrier). Mutations in genes involved in the synthesis of ω-O-acylceramides (acylceramides) and protein-bound ceramides cause ichthyosis.
OBJECTIVE: We aimed to elucidate the relationship between the degree of skin barrier impairment and changes in epidermal ceramide profiles caused by mutations in acylceramide synthesis genes.
METHODS: Knockout (KO) mice of three genes-fatty acid (FA) ω-hydroxylase Cyp4f39 (human CYP4F22 ortholog), FA elongase Elovl1, and acyl-CoA synthetase Fatp4-were subjected to transepidermal water loss measurement, toluidine blue staining, and epidermal ceramide profiling via liquid chromatography coupled with tandem mass spectrometry.
RESULTS: Transepidermal water loss was highest in Cyp4f39 KO mice, followed by Elovl1 KO and Fatp4 KO mice, and Cyp4f39 KO mice also showed the strongest degree of toluidine blue staining. In Cyp4f39 KO, Elovl1 KO, and Fatp4 KO mice, acylceramide levels were 0.6%, 1.6%, and 12%, respectively, of those in wild-type mice. Protein-bound ceramide levels were 0.2%, 30%, and 33%, respectively, of those in wild-type mice. We also observed a near-complete absence of ω-hydroxy ceramides in Cyp4f39 KO mice, reduced total ceramide levels and shortened FA moieties in Elovl1 KO mice, and increased hydroxylated ceramide levels and slightly shortened FA moieties in Fatp4 KO mice.
CONCLUSIONS: The degree of reduction in protein-bound ceramide levels is probably related to the severity of skin barrier defects in these three strains. However, reduced acylceramide levels and other changes in ceramide composition unique to each KO strain are also involved.