Topically Applied Ceramides Interact with the Stratum Corneum Lipid Matrix in Compromised Ex Vivo Skin.

PURPOSE: To determine whether formulations containing ceramides (including a ceramide with a long hydroxyl acyl chain linked to a linoleate, CER EOS) and fatty acids are able to repair the skin barrier by normalizing the lipid organization in stratum corneum (SC). METHODS: The formulations were applied on a skin barrier repair model consisting of ex vivo human skin from which SC was removed by stripping. The effect of formulations on the lipid organization and conformational ordering in the regenerated SC were analyzed using Fourier transform infrared spectroscopy and small angle X-ray diffraction. RESULTS: Application of the formulation containing only one ceramide on regenerating SC resulted in a higher fraction of lipids adopting an orthorhombic organization. A similar fraction of lipids forming an orthorhombic organization was observed after application of a formulation containing two ceramides and a fatty acid on regenerating SC. No effects on the lamellar lipid organization were observed. CONCLUSIONS: Application of a formulation containing either a single ceramide or two ceramides and a fatty acid on regenerating SC, resulted in a denser lateral lipid packing of the SC lipids in compromised skin. The strongest effect was observed after application of a formulation containing a single ceramide.

Degree of Skin Barrier Disruption Affects Lipid Organization in Regenerated Stratum Corneum.

Previously, a skin barrier repair model was developed to examine the effect of formulations on the lipid properties of compromised skin. In this model, the lipid organization mimics that of several skin diseases with impaired skin barrier and less dense lateral lipid organization. In addition, parakeratosis was occasionally observed. The present study investigated whether the extent of initial barrier disruption affects lipid organization and parakeratosis in regenerated stratum corneum. After barrier disruption and stratum corneum regeneration the fraction of lipids adopting a less dense lateral organization gradually increased with increasing degree of barrier disruption. Only when 75% of the stratum corneum was removed, were parakeratosis and a change in lamellar organization observed. This demonstrates the possibility of using the skin barrier repair model to study the effects of formulations on compromised skin in which the presence of parakeratosis and lipid organization can be modified by the extent of barrier disruption.

Applying a vernix caseosa based formulation accelerates skin barrier repair by modulating lipid biosynthesis.

Restoring the lipid homeostasis of the stratum corneum (SC) is a common strategy to enhance skin barrier function. Here, we used a ceramide containing vernix caseosa (VC)-based formulation and were able to accelerate barrier recovery in healthy volunteers. The recovery was examined over 16 days by monitoring trans-epidermal water loss (TEWL) after barrier disruption by tape-stripping. Four skin sites were used to examine the effects of both treatment and barrier recovery. After 16 days, samples were harvested at these sites to examine the SC ceramide composition and lipid organization. Changes in ceramide profiles were identified using principal component analysis. After barrier recovery, the untreated sites showed increased levels of ceramide subclass AS and ceramides with a 34 total carbon-atom chain length, while the mean ceramide chain length was reduced. These changes were diminished by treatment with the studied formulation, which concurrently increased the formulated ceramides. Correlations were observed between SC lipid composition, lipid organization, and TEWL, and changes in the ceramide subclass composition suggest changes in the ceramide biosynthesis. These results suggest that VC-based formulations enhance skin barrier recovery and are attractive candidates to treat skin disorders with impaired barrier properties.

Topically applied fatty acids are elongated before incorporation in the stratum corneum lipid matrix in compromised skin.

In several skin diseases, both the lipid composition and organization in the stratum corneum (SC) are altered which contributes to the impaired skin barrier function in patients. One of the approaches for skin barrier repair is treatment with topical formulations to normalize SC lipid composition and organization. Vernix caseosa (VC), a white cheesy cream on the skin during gestational delivery, has shown to enhance skin barrier repair. In this study, we examined how a fatty acid (FA) containing formulation mimicking the lipid composition of VC interacts with the lipid matrix in the SC. The formulation was applied on ex vivo human skin after SC removal. Subsequently, the ex vivo human skin generated SC during culture. The effect of FA containing formulations on the lipid organization and composition in the regenerated SC was analysed by Fourier transform infrared (FTIR) spectroscopy and liquid chromatography mass spectroscopy (LC/MS), respectively. FTIR results demonstrate that the FAs are intercalated in the lipid matrix of the regenerated SC and partition in the same lattice with the endogenous SC lipids, thereby enhancing the fraction of lipids forming an orthorhombic (very dense) packing in the SC. LC/MS data show that the topically applied FAs are elongated before intercalation in the lipid matrix and are thus involved in the lipid biosynthesis in the skin.

An ex vivo human skin model for studying skin barrier repair.

In the studies described in this study, we introduce a novel ex vivo human skin barrier repair model. To develop this, we removed the upper layer of the skin, the stratum corneum (SC) by a reproducible cyanoacrylate stripping technique. After stripping the explants, they were cultured in vitro to allow the regeneration of the SC. We selected two culture temperatures 32 °C and 37 °C and a period of either 4 or 8 days. After 8 days of culture, the explant generated SC at a similar thickness compared to native human SC. At 37 °C, the early and late epidermal differentiation programmes were executed comparably to native human skin with the exception of the barrier protein involucrin. At 32 °C, early differentiation was delayed, but the terminal differentiation proteins were expressed as in stripped explants cultured at 37 °C. Regarding the barrier properties, the SC lateral lipid organization was mainly hexagonal in the regenerated SC, whereas the lipids in native human SC adopt a more dense orthorhombic organization. In addition, the ceramide levels were higher in the cultured explants at 32 °C and 37 °C than in native human SC. In conclusion, we selected the stripped ex vivo skin model cultured at 37 °C as a candidate model to study skin barrier repair because epidermal and SC characteristics mimic more closely the native human skin than the ex vivo skin model cultured at 32 °C. Potentially, this model can be used for testing formulations for skin barrier repair.

Polymorphisms in alcohol-metabolizing enzymes and esophageal carcinoma susceptibility: a Dutch Caucasian case-control study.

Esophageal cancer (EC), mainly consisting of squamous cell carcinoma (ESCC) in the Eastern world and adenocarcinoma (EAC) in the Western world, is strongly associated with dietary factors such as alcohol use. We aimed to clarify the modifying role in EC etiology in Caucasians of functional genotypes in alcohol-metabolizing enzymes. In all, 351 Caucasian patients with EC and 430 matched controls were included and polymorphisms in CYP2E1, ADH and near ALDH2 genes were determined. In contrast to the results on ESCC in mainly Asian studies, we found that functional genotypes of alcohol-metabolizing enzymes were not significantly associated with EAC or ESCC in an European population.