Nonhydroxylated 1-O-acylceramides in vernix caseosa

Abstract

This article is available online at http://www.jlr.org lamellar structure composed of ceramides, cholesterol, and FAs. The stratum corneum provides a major barrier to water loss and the permeation of exogenous substances (1,2). The skin begins to form during embryogenesis in the third week of gestation. The initial layer of ectodermal cells undergoes gradual differentiation to create a stratified epithelium. By the end of the fourth week, the skin consists of a basal layer and the periderm, which protects the fetus from amniotic fluid and ensures glucose uptake. An intermediate layer is then formed by the proliferation of keratinocytes from the spinous layer between the basal layer and the periderm. The stratum corneum begins to be shaped in the eighteenth week. The periderm cells are completely replaced by the twenty-third week of gestation. At about the same time, vernix caseosa starts to be produced (3,4).Vernix caseosa is a cheese-like substance that coats the fetal skin from the middle of gestation (5). It protects the fetus from the amniotic fluid, prevents the loss of water and electrolytes, and aids in postbirth adaptation of a newborn's skin. The main components of the vernix caseosa are water, sebum, desquamated epithelial cells, and shed lanugo hair. Chemically, it is a rich mixture of lipids and proteins. Even though it has been studied for many decades, the chemical constituents of vernix caseosa have not been comprehensively characterized yet. The enormous chemical complexity of vernix caseosa lipids has fascinated scientists, but they are still far from completely understanding the biological roles of individual lipid classes. Earlier studies of lipid composition focused on abundant neutral (nonpolar) species (6-16), with significantly less attention Abstract Vernix caseosa, the waxy substance that coats the skin of newborn babies, has an extremely complex lipid composition. We have explored these lipids and identified nonhydroxylated 1-O-acylceramides (1-O-ENSs) as a new class of lipids in vernix caseosa. These ceramides mostlycontain saturated C11-C38 ester-linked (1-O) acyls, saturated C12-C39 amide-linked acyls, and C16-C24 sphingoid bases. Because their fatty acyl chains are frequently branched, numerous molecular species were separable and detectable by HPLC/MS: we found more than 2,300 molecular species, 972 of which were structurally characterized. The most abundant 1-O-ENSs contained straight-chain and branched fatty acyls with 20, 22, 24, or 26 carbons in the 1-O position, 24 or 26 carbons in the N position, and sphingosine. The 1-O-ENSs were isolated using multistep TLC and HPLC and they accounted for 1% of the total lipid extract. The molecular species of 1-O-ENSs were separated on a C18 HPLC column using an acetonitrile/propan-2-ol gradient and detected by APCI-MS, and the structures were elucidated by high-resolution and tandem MS. Medium-polarity 1-O-ENSs likely contribute to the cohesiveness and to the waterproofing and moisturizing properties of vernix caseosa.-Harazim, E., V. Vrko...

Epidermal 1‐O‐acylceramides appear with the establishment of the water permeability barrier in mice and are produced by maturating keratinocytes

“…Although we identified keratinocytes as a possible source of 1‐OACs here, production of 1‐OACs by sebaceous glands cannot be excluded. Indeed, the presence of 1‐OACs in vernix caseosa would indicate their role in 1‐OAC production (Harazim et al, 2018). Scd1 is strongly expressed in sebaceous glands and its deficiency has been associated with interference of corresponding cholesteryl ester, triglycerides, and wax ester synthesis (Miyazaki et al, 2001).…”

Introduction of a Fixed-Charge, Photolabile Derivative for Enhanced Structural Elucidation of Fatty Acids

“…The synthesis of derivatization reagents 4-I-AMPP + and 3-I-AMPP + is detailed in the Supporting Information, along with comprehensive characterization of the target reagents and synthetic intermediates. A triacylglycerol fraction of vernix caseosa was provided by Prof. Josef Cvačka (Charles University, Prague). − FA standards and lipid extracts were derivatized using a slight modification to a previously reported procedure as summarized in Figure (for full details, see the Supporting Information). …”

Molecular Dynamics Investigation into CerENP’s Effect on the Lipid Matrix of Stratum Corneum

“…However, the unique physicochemical characteristics of CerENs point to a potentially significant role in organizing the lipid matrix structure and maintaining water barrier homeostasis. Beyond their biological importance, these insights into CerENs are shaping the advancement of dermatological therapeutics and cosmetic formulations designed to mend skin barrier impairments associated with various conditions. − Nevertheless, elucidating the exact impact of CerENs on the lipid matrix configuration and skin barrier function remains an intriguing area of ongoing research.…”