Disrupted skin barrier, one of the severe attributes of inflammatory skin diseases, is caused by lower content and pathological changes of lipids in the uppermost skin layer-stratum corneum (SC). Restoring skin barrier with native skin lipids, especially ceramides (Cers), appears to be a promising therapy with minimum side effects. For testing the efficiency of these formulations, suitable in vitro models of the skin with disrupted barriers are needed. For the similarity with the human tissue, our models were based on the pig ear skin. Three different ways of skin barrier disruption were tested and compared: tape stripping, lipid extraction with organic solvents, and barrier disruption by sodium lauryl sulfate. The level of barrier disruption was investigated by permeation studies, and parameters of each method were modified to reach significant changes between the non-disrupted skin and our model. Fourier transform infrared (FTIR) spectroscopy was employed to elucidate the changes of the skin permeability on the molecular scale. Further, the potential of the developed models to be restored by skin barrier repairing agents was evaluated by the same techniques. We observed a significant decrease in permeation characteristics through our in vitro models treated with the lipid mixtures compared to the untreated damaged skin, which implied that the skin barrier was substantially restored. Taken together, the results suggest that our in vitro models are suitable for the screening of potential barrier repairing agents.

• Klíčová slova
• FTIR spectroscopy, ceramides, liposomes, permeation experiment, skin barrier disruption models, stratum corneum lipids, topical treatment,
• MeSH
• ceramidy * MeSH
• epidermis MeSH
• kůže * MeSH
• lipidy MeSH
• permeabilita MeSH
• prasata MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ceramidy * MeSH
• lipidy MeSH

Stratum corneum ceramides are fundamental for maintaining the skin barrier properties. Their content is decreased in some skin diseases, e.g. atopic dermatitis, and ceramide supplementation is one of the therapeutic approaches. In the present study we have designed novel ceramide analogue 14S24 ((S)-2-tetracosanoylamino-3-hydroxypropionic acid tetradecyl ester) as a potential barrier-repairing agent. We report a convenient two-step synthesis of this analogue with high yields. The ability of 14S24 to repair the disturbed skin barrier was evaluated in vitro on the porcine skin. After 2h application of 14S24 on the skin disrupted by lipid extraction, the permeability decreased significantly almost to the values of the native skin. The compound is effective in 0.1% aqueous suspension and its effect is comparable with physiological skin lipids under the same condition. The comparison of 14S24 and skin ceramides was made via computer modelling and the in silico physico-chemical parameters are reported. We suggest that allylic hydroxyl, that is essential for the apoptogenic activity of ceramides, is not a necessary component of the skin barrier-forming ceramides. The main result of this study is to demonstrate that simpler and easier-to-synthesise ceramide analogues could be effective in the skin barrier repair.

• MeSH
• ceramidy chemie   metabolismus   farmakologie   MeSH
• kožní absorpce účinky léků   MeSH
• kůže účinky léků   metabolismus   MeSH
• membránové lipidy metabolismus   MeSH
• prasata MeSH
• techniky in vitro MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• Názvy látek
• ceramidy MeSH
• membránové lipidy MeSH

Lipid membranes play a crucial role in regulating the body's water balance by adjusting their properties in response to hydration. The intercellular lipid matrix of the stratum corneum (SC), the outermost skin layer, serves as the body's primary defense against environmental factors. Osmolytes, including urocanic acid (UCA) and glycerol, are key components of the natural moisturizing factor that help the SC resist osmotic stress from dry environments. This study examines the effects of UCA and glycerol (each at 5 mol %) on isolated human SC lipids. For this, different techniques were employed, offering complementary information of the system's multiscale characteristics, including humidity-scanning quartz crystal microbalance with dissipation monitoring, infrared spectroscopy, x-ray diffraction, electrical impedance spectroscopy, and studies of water loss and permeability. Our results show that UCA increases water sorption and makes lipid films more liquid-like at high relative humidity, without significantly altering the lipid lamellar structure, chain order, or orthorhombic chain packing. Lipid films containing UCA exhibited higher water loss and significantly higher model drug permeability compared to lipid films without UCA. Further, incorporation of UCA resulted in kinetically faster changes in electrical properties upon contact with aqueous solution compared with control lipids. These observations suggest that UCA reduces lipid cohesion in regions other than the acyl chain-rich leaflets, which may impact SC desquamation. In contrast, glycerol did not influence the hydration or permeability of the SC lipid matrix. However, it increased the proportion of orthorhombic domains at high humidities and slowed the kinetics of the hydration process, as evidenced by slower changes in the dielectric properties of the lipid film. These findings suggest that glycerol enhances lipid cohesion rather than increasing water uptake, which is typically the expected function of humectants. Consequently, UCA and glycerol appear to have distinct roles in maintaining epidermal homeostasis.

• MeSH
• glycerol * chemie   farmakologie   MeSH
• kůže metabolismus   MeSH
• kyselina urokanová chemie   farmakologie   metabolismus   MeSH
• lidé MeSH
• lipidy chemie   MeSH
• permeabilita MeSH
• voda * chemie   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• glycerol * MeSH
• kyselina urokanová MeSH
• lipidy MeSH
• voda * MeSH

Ceramides are a family of lipids constituted by a sphingoid base and a fatty acid. In the skin, they are mainly present in the stratum corneum where, with cholesterol and free fatty acids, they constitute the inter-corneocyte lipids. With the other lipid groups, they play a key role in the formation of dense lamellar structures between adjacent corneocytes, collectively ensuring the vital efficient barrier to water evaporation and protection from foreign agents´ penetration. Changes in ceramide level and relative composition, with potential impairment of lipid arrangement, have been evidenced in different skin conditions and skin diseases. Therefore, use of suitably formulated ceramides has been proposed for topical treatment to help re-structure damaged lipid arrangement and repair impaired skin barrier function. Nonetheless, the formulation of ceramides in products necessitates specific processes such as heating to high temperature before their introduction in the final formula. In this review on the structure, the role and the potential of ceramides for skincare, we point out the necessity of rigorous process when formulating ceramides into the final product. We demonstrate the counterproductive effects of undissolved ceramides on skin barrier repair capacity of the formulas, when assessed in different in vitro models of disrupted skin barrier.

Les céramides sont une famille de lipides constituée d'une base sphingoïde et d'un acide gras. Dans la peau, ils sont principalement présents dans la couche cornée où, avec le cholestérol et les acides gras libres, ils constituent les lipides inter‐cornéocytes. Avec les autres groupes de lipides, ils jouent un rôle clé dans la formation de structures lamellaires denses entre les cornéocytes adjacents, assurant collectivement la barrière efficace vitale contre l'évaporation de l'eau et la protection contre la pénétration des agents étrangers. Des modifications du taux de céramides et de la composition relative, avec une altération potentielle de l'arrangement lipidique, ont été observées dans différentes affections cutanées et maladies cutanées. Par conséquent, l'utilisation de céramides formulés de manière appropriée a été proposée pour un traitement topique afin d'aider à restructurer la disposition des lipides endommagés et à réparer la fonction de barrière cutanée altérée. Néanmoins, la formulation des céramides dans les produits nécessite des processus spécifiques tels que le chauffage à température élevée avant leur introduction dans la formule finale. Dans cette revue sur la structure, le rôle et le potentiel des céramides pour les soins de la peau, nous soulignons la nécessité d'un processus rigoureux lors de la formulation des céramides dans le produit final. Nous démontrons les effets contre‐productifs des céramides non dissous sur la capacité de réparation de la barrière cutanée des formules, lorsqu'ils sont évalués dans différents modèles in vitro de barrière cutanée perturbée.

• Klíčová slova
• ceramides, emulsion, formulation, skin barrier, skin physiology/structure, topical application,
• MeSH
• ceramidy * chemie   MeSH
• kůže * metabolismus   MeSH
• lidé MeSH
• péče o kůži * metody   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• ceramidy * MeSH

Epidermal omega-O-acylceramides (ω-O-acylCers) are essential components of a competent skin barrier. These unusual sphingolipids with ultralong N-acyl chains contain linoleic acid esterified to the terminal hydroxyl of the N-acyl, the formation of which requires the transacylase activity of patatin-like phospholipase domain containing 1 (PNPLA1). In ichthyosis with dysfunctional PNPLA1, ω-O-acylCer levels are significantly decreased, and ω-hydroxylated Cers (ω-OHCers) accumulate. Here, we explore the role of the linoleate moiety in ω-O-acylCers in the assembly of the skin lipid barrier. Ultrastructural studies of skin samples from neonatal Pnpla1+/+ and Pnpla1-/- mice showed that the linoleate moiety in ω-O-acylCers is essential for lamellar pairing in lamellar bodies, as well as for stratum corneum lipid assembly into the long periodicity lamellar phase. To further study the molecular details of ω-O-acylCer deficiency on skin barrier lipid assembly, we built in vitro lipid models composed of major stratum corneum lipid subclasses containing either ω-O-acylCer (healthy skin model), ω-OHCer (Pnpla1-/- model), or combination of the two. X-ray diffraction, infrared spectroscopy, and permeability studies indicated that ω-OHCers could not substitute for ω-O-acylCers, although in favorable conditions, they form a medium lamellar phase with a 10.8 nm-repeat distance and permeability barrier properties similar to long periodicity lamellar phase. In the absence of ω-O-acylCers, skin lipids were prone to separation into two phases with diminished barrier properties. The models combining ω-OHCers with ω-O-acylCers indicated that accumulation of ω-OHCers does not prevent ω-O-acylCer-driven lamellar stacking. These data suggest that ω-O-acylCer supplementation may be a viable therapeutic option in patients with PNPLA1 deficiency.

• Klíčová slova
• PNPLA1 deficiency, Skin, acylceramides, barrier function, ceramides, linoleic acid, lipids, model membranes, sphingolipids, stratum corneum,
• MeSH
• acyltransferasy MeSH
• ceramidy * chemie   MeSH
• epidermis MeSH
• ichtyóza MeSH
• kůže * MeSH
• kyselina linolová MeSH
• lipasa MeSH
• myši MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• acyltransferasy MeSH
• ceramidy * MeSH
• kyselina linolová MeSH
• lipasa MeSH
• PNPLA1 protein, mouse MeSH Prohlížeč

Electron paramagnetic resonance (EPR) spectroscopy represents an established tool to study properties of microenvironments, e.g. to investigate the structure and dynamics of biological and artificial membranes. In this study, the partitioning of the spin probe 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) in ex vivo human abdominal and breast skin, ex vivo porcine abdominal and ear skin as well as normal and inflammatory in vitro skin equivalents was investigated by EPR spectroscopy. Furthermore, the stratum corneum (SC) lipid composition (as determined by high-performance thin-layer chromatography), SC lipid chain order (probed by infrared spectroscopy) and the SC thickness (investigated by histology) were determined in the skin models. X-band EPR measurements have shown that TEMPO partitions in the lipophilic and hydrophilic microenvironment in varying ratios in different ex vivo and in vitro skin models. Ex vivo human abdominal skin exhibited the highest amount of TEMPO in the lipophilic microenvironment. In contrast, the lowest amount of TEMPO in the lipophilic microenvironment was determined in ex vivo human breast skin and the inflammatory in vitro skin equivalents. Individual EPR spectra of epidermis including SC and dermis indicated that the lipophilic microenvironment of TEMPO mainly corresponds to the most lipophilic part of the epidermis, the SC. The amount of TEMPO in the lipophilic microenvironment was independent of the SC lipid composition and the SC lipid chain order but correlated with the SC thickness. In conclusion, EPR spectroscopy could be a novel technique to determine differences in the SC thickness, thus suitably complementing existing methods.

• Klíčová slova
• Electron paramagnetic resonance spectroscopy, Skin barrier lipids, Stratum corneum thickness, TEMPO partitioning,
• MeSH
• břicho MeSH
• buněčné mikroprostředí MeSH
• chromatografie na tenké vrstvě MeSH
• cyklické N-oxidy chemie   MeSH
• dospělí MeSH
• elektronová paramagnetická rezonance MeSH
• epidermis chemie   MeSH
• kůže chemie   cytologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• lipidy chemie   MeSH
• mladý dospělý MeSH
• prasata MeSH
• prsy MeSH
• senioři MeSH
• spektrofotometrie infračervená MeSH
• spinové značení MeSH
• tloušťka kožní řasy MeSH
• zevní ucho MeSH
• zvířata MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cyklické N-oxidy MeSH
• lipidy MeSH
• spinové značení MeSH
• TEMPO MeSH Prohlížeč

Hyaluronic acid (HA) hydrogels are interesting delivery systems for topical applications. Besides moisturizing the skin and improving wound healing, HA facilitates topical drug absorption and is highly compatible with labile biomacromolecules. Hence, in this study we investigated the influence of HA hydrogels with different molecular weights (5 kDa, 100 kDa, 1 MDa) on the skin absorption of the model protein bovine serum albumin (BSA) using fluorescence lifetime imaging microscopy (FLIM). To elucidate the interactions of HA with the stratum corneum and the skin absorption of HA itself, we combined FLIM and Fourier-transform infrared (FTIR) spectroscopy. Our results revealed distinct formulation and skin-dependent effects. In barrier deficient (tape-stripped) skin, BSA alone penetrated into dermal layers. When BSA and HA were applied together, however, penetration was restricted to the epidermis. In normal skin, penetration enhancement of BSA into the epidermis was observed when applying low molecular weight HA (5 kDa). Fluorescence resonance energy transfer analysis indicated close interactions between HA and BSA under these conditions. FTIR spectroscopic analysis of HA interactions with stratum corneum constituents showed an α-helix to β-sheet interconversion of keratin in the stratum corneum, increased skin hydration, and intense interactions between 100 kDa HA and the skin lipids resulting in a more disordered arrangement of the latter. In conclusion, HA hydrogels restricted the delivery of biomacromolecules to the stratum corneum and viable epidermis in barrier deficient skin, and therefore seem to be potential topical drug vehicles. In contrast, HA acted as an enhancer for delivery in normal skin, probably mediated by a combination of cotransport, increased skin hydration, and modifications of the stratum corneum properties.

• Klíčová slova
• FLIM, FTIR, epidermal drug delivery, hyaluronic acid, proteins, skin hydration, skin penetration,
• MeSH
• aplikace kožní MeSH
• kožní absorpce MeSH
• kůže metabolismus   MeSH
• kyselina hyaluronová chemie   MeSH
• prasata MeSH
• sérový albumin hovězí chemie   metabolismus   MeSH
• skot MeSH
• spektroskopie infračervená s Fourierovou transformací MeSH
• techniky in vitro MeSH
• zvířata MeSH
• Check Tag
• skot MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kyselina hyaluronová MeSH
• sérový albumin hovězí MeSH

Transdermal drug delivery is an attractive non-invasive method offering numerous advantages over the conventional routes of administration. The main obstacle to drug transport is, however, the powerful skin barrier that needs to be modulated, for example, by transdermal permeation enhancers. Unfortunately, there are still only a few enhancers showing optimum properties including low toxicity and reversibility of enhancing effects. For this reason, we investigated a series of new N-alkylmorpholines with various side chains as potential enhancers in an in vitro permeation study, using three model permeants (theophylline, indomethacin, diclofenac). Moreover, electrical impedance, transepidermal water loss, cellular toxicity and infrared spectroscopy measurements were applied to assess the effect of enhancers on skin integrity, reversibility, toxicity and enhancers' mode of action, respectively. Our results showed a bell-shaped relationship between the enhancing activity and the hydrocarbon chain length of the N-alkylmorpholines, with the most efficient derivatives having 10-14 carbons for both transdermal and dermal delivery. These structures were even more potent than the unsaturated oleyl derivative. The best results were obtained for indomethacin, where particularly the C10-14 derivatives showed significantly stronger effects than the traditional enhancer Azone. Further experiments revealed reversibility in the enhancing effect, acceptable toxicity and a mode of action based predominantly on interactions with stratum corneum lipids.

• Klíčová slova
• dermal and transdermal drug delivery, morpholine derivatives, skin barrier, skin permeation enhancers,
• Publikační typ
• časopisecké články MeSH

Overcoming the skin barrier properties efficiently, temporarily, and safely for successful transdermal drug delivery remains a challenge. We synthesized three series of potential skin permeation enhancers derived from natural amino acid derivatives proline, 4-hydroxyproline, and pyrrolidone carboxylic acid, which is a component of natural moisturizing factor. Permeation studies using in vitro human skin identified dodecyl prolinates with N-acetyl, propionyl, and butyryl chains (Pro2, Pro3, and Pro4, respectively) as potent enhancers for model drugs theophylline and diclofenac. The proline derivatives were generally more active than 4-hydroxyprolines and pyrrolidone carboxylic acid derivatives. Pro2-4 had acceptable in vitro toxicities on 3T3 fibroblast and HaCaT cell lines with IC50 values in tens of µM. Infrared spectroscopy using the human stratum corneum revealed that these enhancers preferentially interacted with the skin barrier lipids and decreased the overall chain order without causing lipid extraction, while their effects on the stratum corneum protein structures were negligible. The impacts of Pro3 and Pro4 on an in vitro transepidermal water loss and skin electrical impedance were fully reversible. Thus, proline derivatives Pro3 and Pro4 have an advantageous combination of high enhancing potency, low cellular toxicity, and reversible action, which is important for their potential in vivo use as the skin barrier would quickly recover after the drug/enhancer administration is terminated.

• MeSH
• aplikace kožní MeSH
• hydroxyprolin metabolismus   MeSH
• kožní absorpce * MeSH
• kůže metabolismus   MeSH
• kyseliny karboxylové metabolismus   MeSH
• léčivé přípravky metabolismus   MeSH
• lidé MeSH
• organické látky metabolismus   MeSH
• permeabilita MeSH
• prolin * metabolismus   MeSH
• pyrrolidinony farmakologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• hydroxyprolin MeSH
• kyseliny karboxylové MeSH
• léčivé přípravky MeSH
• organické látky MeSH
• prolin * MeSH
• pyrrolidinony MeSH