Increased Presence of Monounsaturated Fatty Acids in the Stratum Corneum of Human Skin Equivalents

Abstract

Previous results showed that our in-house human skin equivalents (HSEs) differ in their stratum corneum (SC) lipid organization compared with human SC. To elucidate the cause of the altered SC lipid organization in the HSEs, a recently developed liquid chromatography/mass spectrometry method was used to study the free fatty acid (FFA) and ceramide composition in detail. In addition, the SC lipid composition of the HSEs and human skin was examined quantitatively with high-performance thin-layer chromatography. Our results reveal that all our HSEs have an increased presence of monounsaturated FFAs compared with human SC. Moreover, the HSEs display the presence of ceramide species with a monounsaturated acyl chain, which are not detected in human SC. All HSEs also exhibit an altered expression of stearoyl-CoA desaturase, the enzyme that converts saturated FFAs to monounsaturated FFAs. Furthermore, the HSEs show the presence of 12 ceramide subclasses, similar to native human SC. However, the HSEs have increased levels of ceramides EOS and EOH and ceramide species with short total carbon chains and a reduced FFA level compared with human SC. The presence of unsaturated lipid chains in HSE offers new opportunities to mimic the lipid properties of human SC more closely.

Nrf2 deficiency causes lipid oxidation, inflammation, and matrix-protease expression in DHA-supplemented and UVA-irradiated skin fibroblasts

“…Important insights into the biophysics of lipids that to a large part constitute the epidermal permeability barrier of the skin have been gained recently (rev in [1] and [2]. The type, chain length [3] and saturation grade [4] of fatty acids (FA) that are used as building blocks for barrier lipids of the stratum corneum or simply as acidifying agents, strongly determine the function or pathologic malfunction [5] of this outermost, dead but essential layer of the skin. When a keratinocyte differentiates and leaves the basal layer this determines fate of cellular lipids as they will mostly contribute to barrier formation.…”

Non-animal models of epithelial barriers (skin, intestine and lung) in research, industrial applications and regulatory toxicology

“…Although all lipid classes present in native human skin are also present in HSEs, there is a deviation in free lipid composition and organization compared to native human skin. The most important of such deviations are a high level of unsaturated fatty acids, shorter lipid chain lengths (Mojumdar et al, 2014;Thakoersing et al, 2013Thakoersing et al, , 2015 and an imbalance in the level of ceramide subclasses (Thakoersing et al, 2012). These changes in lipid composition are expected to contribute significantly to the impaired skin barrier of HSEs (Mojumdar et al, 2014).…”

“…The main shortcomings related to the currently available reconstructed tissue models are: i) insufficient barrier properties, reflected in a modulated lipid composition and organization (Leroy et al, 2014(Leroy et al, , 2013Thakoersing et al, 2012Thakoersing et al, , 2013 and increased flux or absorption rate in skin penetration studies (Davies et al, 2015;EFSA, 2012;Hui et al, 2012;Schafer-Korting et al, 2008); ii) lack of vascularization, sweat glands and hair; iii) lack of representation of the physiologically-relevant desquamation process; iv) lack of reproducibility of immunocompetent models.…”

Barrier Properties of an N/TERT-Based Human Skin Equivalent

“…22 For quantification, co-chromotography of serial dilutions of each of the standards was done as described earlier. 23 The standards consisted of CHOL, palmitic acid, stearic acid, arachidic acid, tricosanoic acid, behenic acid, lignoceric acid, cerotic acid, and CER EOS, NS, NP, EOP, AS, and AP. CER nomenclature according to the terminology of Masukawa et al and Motta et al 24,25 Details about CER nomenclature and quantification are provided in the Supplementary Materials and Methods section.…”