Ceramides and skin function

A Dual-Modality Imaging Method Based on Polarimetry and Second Harmonic Generation for Characterization and Evaluation of Skin Tissue Structures

The characterization and evaluation of skin tissue structures are crucial for dermatological applications. Recently, Mueller matrix polarimetry and second harmonic generation microscopy have been widely used in skin tissue imaging due to their unique advantages. However, the features of layered skin tissue structures are too complicated to use a single imaging modality for achieving a comprehensive evaluation. In this study, we propose a dual-modality imaging method combining Mueller matrix polarimetry and second harmonic generation microscopy for quantitative characterization of skin tissue structures. It is demonstrated that the dual-modality method can well divide the mouse tail skin tissue specimens' images into three layers of stratum corneum, epidermis, and dermis. Then, to quantitatively analyze the structural features of different skin layers, the gray level co-occurrence matrix is adopted to provide various evaluating parameters after the image segmentations. Finally, to quantitatively measure the structural differences between damaged and normal skin areas, an index named Q-Health is defined based on cosine similarity and the gray-level co-occurrence matrix parameters of imaging results. The experiments confirm the effectiveness of the dual-modality imaging parameters for skin tissue structure discrimination and assessment. It shows the potential of the proposed method for dermatological practices and lays the foundation for further, in-depth evaluation of the health status of human skin.

A theoretical investigation on the synergetic effect of hydrogen-bonding interactions and thermodynamic property in the 1: 2 (azacyclopentane-2-one: N-methylolacetamide) ternary complex

CONTEXT

Using chemical penetration enhancers to improve the penetration effect is one kind of important strategies in transdermal drug delivery system. Azone is a widely used transdermal absorption enhancer for transdermal drug delivery. To shed light on the permeation-promoting mechanism of azone, we selected ternary systems formed by azacyclopentane-2-one and N-methylolacetamide (1: 2) and explored the synergetic effect of hydrogen-bonding interactions among them and their thermodynamic properties. The findings indicate that the synergetic effects can enhance the ability of azone to change the original conformation of ceramides and even break the original hydrogen bonds, which is more beneficial for azone to destroy the 3D network structure of ceramides. When azone interacts with ceramide, the order of action tends to interact with one molecule of ceramide first and then with another molecule of ceramide.

METHODS

The synergetic effects of hydrogen-bonding interactions in ternary systems were computed at the B3LYP/6-311 +  + G** and MP2(full)/6-311 +  + G** levels. Thermodynamic parameters for two ternary-complex routes were worked out at the B3LYP/aug-cc-pVDZ level. The shift of the electron density occurring simultaneously with trimer formation was analyzed at the MP2(full)/6-311 +  + G** level. The above calculations were carried out using the Gaussian 03 program packages. Atoms in molecules (AIM) method and the AIMPAC program showed the topological charge density at the MP2(full)/6-311 +  + G** level. The synergetic effects of hydrogen-bonding interactions and thermodynamic property in the 1: 2 (azacyclopentane-2-one: N-methylolacetamide) ternary systems were investigated using the B3LYP and MP2(full) methods.

Lipidomic Analysis of Hand Skin Surface Lipids Reveals Smoking-Related Skin Changes

Smoking contributes to the formation of skin wrinkles and reduces skin function, but the mechanism is not yet fully proven. This study aims to compare and analyze the effects of smoking on skin lipids and to further investigate the harmful effects of smoking on the skin. A total of 40 subjects (20 male smokers and 20 healthy control males) were recruited for this study. Measurement of hand skin-surface lipids (SSLs) in smoking and healthy control groups was undertaken using ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). Multivariate data analysis was used to investigate the differences in SSLs between the two groups. There were 1230 lipids detected in the two groups and significant differences in SSLs' composition were observed between them. Under selected conditions, 26 types of lipid with significant differences were observed between the two groups (p < 0.05). Sphingolipids (SP) and glycerolipids (GL) were significantly increased, and sterol lipids (ST) were significantly reduced. Smoking causes changes in skin lipids that disrupt skin homeostasis, making the skin more fragile and more susceptible to skin aging and diseases.

Efficacy and Safety of the Genistein Nutraceutical Product Containing Vitamin E, Vitamin B3, and Ceramide on Skin Health in Postmenopausal Women: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

Skin aging is one of the most concerning issues that occur after menopause. The Genistein Nutraceutical (GEN) product, containing genistein, vitamin E, vitamin B3, and ceramide, has been formulated as a topical anti-aging product for improving the health of postmenopausal women's facial skin. This study aimed to investigate the efficacy and safety of the GEN product on postmenopausal women's facial skin. This randomized, double-blind, placebo-controlled trial randomly assigned 50 postmenopausal women to receive either the GEN product (n = 25) or the placebo (PLA) product (n = 25), topically applied twice daily for 6 weeks. The outcome assessments included multiple skin parameters related to skin wrinkling, color, hydration, and facial skin quality at baseline and week 6. The percentage mean changes or absolute mean changes, where appropriate, in skin parameters were compared between the two groups. The mean age of the participants was 55.8 ± 3.4 years. For skin wrinkling and skin color parameters, only skin redness was significantly higher in the GEN group when compared to the PLA group. Following the application of the GEN product, skin hydration increased while fine pores and their area decreased. Subgroup analysis of older women (age ≥ 56 years) with adequate compliance found significant differences between the two groups in the percentage mean changes of most skin wrinkle parameters. The GEN product has benefits for the facial skin of postmenopausal women, particularly those who are older. It can moisturize facial skin, lessen wrinkles, and enhance redness.

Cera-Glow, ferment lysates of Lacticaseibacillus rhamnosus IDCC 3201, improves skin barrier function in clinical study

BACKGROUND

Ceramides are essential lipids in stratum corneum for skin permeability barrier function in that they retain the skin moisture and protect from the invasion of foreign pathogens. Previously, we demonstrated that ferment lysates of Lacticaseibacillus rhamnosus IDCC 3201 enhanced ceramide production in human epidermal keratinocytes. Furthermore, for comprehensive knowledge of this effect, in vitro experiments and multi-omics analysis were conducted to explore the underlying mechanisms.

AIMS

This study was designed to identify whether a cosmetic sample (i.e., Cera-Glow) containing the lysates improves the skin barrier function in clinical trials.

PATIENTS/METHODS

Twenty-four female participants (45.46 ± 9.78 years) had been enrolled in the transepidermal water loss (TEWL) measurement for 5 days and 21 female participants (50.33 ± 5.74 years) had undergone a skin hydration evaluation for 4 weeks. TEWL and skin hydration were evaluated using a Tewameter and the Epsilon Permittivity Imaging System, respectively. After applying the Cera-Glow sample, all participants recorded a satisfaction survey questionnaire (e.g., satisfaction, efficacy, and adverse reactions).

RESULTS

Application of Cera-Glow significantly improved transepidermal water loss induced by 1% (w/v) sodium lauryl sulfate (p < 0.05-0.01) and increased skin hydration (p < 0.01). Metabolic analysis suggested that Cera-Glow should contain beneficial gradients for skin barrier function. According to the questionnaire, most of participants were satisfied with the skin hydration improvement and efficacy of Cera-Glow.

CONCLUSIONS

Cera-Glow, ferment lysates of Lacticaseibacillus rhamnosus IDCC 3201, can significantly improve skin barrier function.

Improved Tool for Predicting Skin Irritation on Reconstructed Human Epidermis Models Based on Electrochemical Impedance Spectroscopy

The rabbit skin irritation test has been the standard for evaluating the irritation potential of chemicals; however, alternative methods that do not use animal testing are actively encouraged. Reconstructed human epidermis (RhE) models mimic the biochemical and physiological properties of the human epidermis and can be used as an alternative method. On RhE methods, the metabolic activity of RhE models is used to predict skin irritation, with a reduction in metabolic activity indicating a reduced number of viable cells and linking cell death to skin irritation processes. However, new challenges have emerged as the use of RhE models increases, including the need for non-invasive and marker-free methodologies to assess cellular states. Electrochemical impedance spectroscopy (EIS) is one such methodology that can meet these requirements. In this study, our results showed that EIS can differentiate between irritant and non-irritant chemicals, with a significant increase in the capacitance values observed in the irritant samples. A ROC curve analysis showed that the prediction method based on EIS met OECD TG 439 requirements at all time points and had 95% within-laboratory reproducibility. Comparison with the MTT viability assay showed that prediction using EIS achieved higher sensitivity, specificity, and accuracy. These results suggest that EIS could potentially replace animal testing in the evaluation of irritation potential and could be a valuable addition to in vitro testing strategies.

Lycopene, but not zeaxanthin, serves as a skeleton for the formation of an orthorhombic organization of intercellular lipids within the lamellae in the stratum corneum: Molecular dynamics simulations of the hydrated ceramide NS bilayer model

Carotenoids play an important role in the protection of biomembranes against oxidative damage. Their function depends on the surroundings and the organization of the lipid membrane they are embedded in. Carotenoids are located parallel or perpendicular to the surface of the lipid bilayer. The influence of carotenoids on the organization of the lipid bilayer in the stratum corneum has not been thoroughly considered. Here, the orientation of the exemplary cutaneous carotenoids lycopene and zeaxanthin in a hydrated ceramide NS24 bilayer model and the influence of carotenoids on the lateral organization of the lipid bilayer model were studied by means of molecular dynamics simulations for 32 °C and 37 °C. The results confirm that lycopene is located parallel and zeaxanthin perpendicular to the surface of the lipid bilayer. The lycopene-loaded lipid bilayer appeared to have a strong orthorhombic organization, while zeaxanthin-loaded and pure lipid bilayers were organized in a disordered hexagonal-like and liquid-like state, respectively. The effect is stronger at 32 °C compared to 37 °C based on p-values. Therefore, it was assumed that carotenoids without hydroxyl polar groups in their structure facilitate the formation of the orthorhombic organization of lipids, which provides the skin barrier function. It was shown that the distance between carotenoid atoms matched the distance between atoms in the lipids, indicating that parallel located carotenoids without hydroxyl groups serve as a skeleton for lipid membranes inside the lamellae. The obtained results provide reasonable prediction of the overall qualitative properties of lipid model systems and show the importance of parallel-oriented carotenoids in the development and maintenance of the skin barrier function.

Neryl acetate, the major component of Corsican Helichrysum italicum essential oil, mediates its biological activities on skin barrier

Corsican Helichrysum italicum essential oil (HIEO) is characterized by high concentrations of neryl acetate, and we previously demonstrated that Corsican HIEO increases the expression of genes that are part of the differentiation complex (involucrin, small proline rich proteins, late cornified envelope, S100 protein family). The biological activities of HIEO and neryl acetate (NA) were compared to identify how NA contributes to HIEO activity on human skin. NA, as a part component of HIEO, was tested on skin explant models for 24 hours and 5 days in comparison with HIEO. We analyzed the biological regulations in the skin explant by transcriptomic analysis, skin barrier protein immunofluorescence, lipid staining and ceramide analysis by liquid chromatography-mass spectrometry. Transcriptomic analysis revealed that 41.5% of HIEO-modulated genes were also regulated by NA and a selected panel of genes were confirmed by qquantitative reverse transcription PCR analysis. Those genes are involved in epidermal differentiation, skin barrier formation and ceramide synthesis. Involucrin (IVL), involved in formation of the cornified envelope (CE), was upregulated at both gene and protein levels after 24 hours and 5 days respectively. After 5 days of treatment, total lipids and ceramides were also increased. Our results demonstrate that NA mediates a large part of Corsican HIEO activity on skin barrier formation.

Fish Collagen Peptide (NaticolⓇ) Protects the Skin from Dryness, Wrinkle Formation, and Melanogenesis Both In Vitro and In Vivo

Consistent ultraviolet B (UVB) radiation exposure results in dry skin, wrinkles, and melanogenesis. In this study, we investigated whether fish collagen peptide (Naticol^Ⓡ) could inhibit photoaging and oxidative stress in skin exposed to UVB using cell and animal models. We measured the skin hydration, histological observations, antioxidant activities, moisturizing-related factors, collagen synthesis-related factors, and melanogenesis-related factors in skin cells and animal skin using enzyme-linked immunosorbent assay, real-time polymerase chain reaction, and Western blot assay. Naticol^Ⓡ collagen improved skin moisturization via hyaluronic acid and ceramide synthesis-related factors in HaCaT cells and SHK-I hairless mice that were exposed to UVB. In addition, Naticol^Ⓡ collagen inhibited wrinkle formation in Hs27 cells and SHK-I hairless mice exposed to UVB and restrained melanogenesis in 3-isobutyl-1-methylxanthine-induced B16F10 cells and UVB-irradiated SHK-I hairless mice. On the basis of these findings, we propose that ingestion of Naticol ^Ⓡ collagen might be valuable for preventing skin photoaging.

3D Molecular Imaging of Stratum Corneum by Mass Spectrometry Suggests Distinct Distribution of Cholesteryl Esters Compared to Other Skin Lipids

The crucial barrier properties of the stratum corneum (SC) depend critically on the design and integrity of its layered molecular structure. However, analysis methods capable of spatially resolved molecular characterization of the SC are scarce and fraught with severe limitations, e.g., regarding molecular specificity or spatial resolution. Here, we used 3D time-of-flight secondary ion mass spectrometry to characterize the spatial distribution of skin lipids in corneocyte multilayer squams obtained by tape stripping. Depth profiles of specific skin lipids display an oscillatory behavior that is consistent with successive monitoring of individual lipid and corneocyte layers of the SC structure. Whereas the most common skin lipids, i.e., ceramides, C24:0 and C26:0 fatty acids and cholesteryl sulfate, are similarly organized, a distinct 3D distribution was observed for cholesteryl oleate, suggesting a different localization of cholesteryl esters compared to the lipid matrix separating the corneocyte layers. The possibility to monitor the composition and spatial distribution of endogenous lipids as well as active drug and cosmetic substances in individual lipid and corneocyte layers has the potential to provide important contributions to the basic understanding of barrier function and penetration in the SC.

Investigating the nanostructure of a CER[NP]/CER[AP]-based stratum corneum lipid matrix model: A combined neutron diffraction & molecular dynamics simulations approach

The human skin provides a physiochemical and biological protective barrier due to the unique structure of its outermost layer known as the Stratum corneum. This layer consists of corneocytes and a multi-lamellar lipid matrix forming a composite, which is a major determining factor for the barrier function of the Stratum corneum. A substantiated understanding of this barrier is necessary, as controlled breaching or modulation of the same is also essential for various health and personal care applications such as topical drug delivery and cosmetics to a name few. In this study, we discuss the state-of-the-art of neutron diffraction techniques, using specifically deuterated lipids, combined with the information obtained from molecular models using molecular dynamics simulations, to understand the structure and barrier function of the Stratum corneum lipid matrix. As an example, the effect of ceramide concentration on a lipid lamella system consisting of CER[NP]/CER[AP]/Cholesterol/free fatty acid (deprotonated) is studied. This study demonstrates the usefulness of the combined approach of neutron diffraction and molecular dynamics simulations for effective analysis of the model systems created for the Stratum corneum lipid matrix. The optimization of force fields by comparison with experimental data is furthermore an important step in the direction of providing a predictive quality.

Ceramide Acyl Chain Length and Its Relevance to Intracellular Lipid Regulation

Ceramides are a class of sphingolipids which are implicated in skin disorders, obesity, and other metabolic diseases. As a class with pleiotropic effects, recent efforts have centred on discerning specific ceramide species and their effects on atopic dermatitis, obesity, type 2 diabetes, and cardiovascular diseases. This delineation has allowed the identification of disease biomarkers, with long acyl chain ceramides such as C16- and C18-ceramides linked to metabolic dysfunction and cardiac function decline, while ultra-long acyl chain ceramides (>25 carbon acyl chain) were reported to be essential for maintaining a functional skin barrier. Given the intricate link between free fatty acids with ceramides, especially the de novo synthetic pathway, intracellular lipid droplet formation is increasingly viewed as an important mechanism for preventing accumulation of toxic ceramide species. Here, we review recent reports of various ceramide species involved in skin abnormalities and metabolic diseases, and we propose that promotion of lipid droplet biogenesis can be seen as a potential protective mechanism against deleterious ceramides.

Occupational exposure assessment with solid substances: choosing a vehicle for in vitro percutaneous absorption experiments

Percutaneous occupational exposure to industrial toxicants can be assessed in vitro on excised human or animal skins. Numerous factors can significantly influence skin permeation of chemicals and the flux determination. Among them, the vehicle used to solubilize the solid substances is a tricky key step. A "realistic surrogate" that closely matches the exposure scenario is recommended in first intention. When direct transposition of occupational exposure conditions to in vitro experiments is impossible, it is recommended that the vehicle used does not affect the skin barrier (in particular in terms of structural integrity, composition, or enzymatic activity). Indeed, any such effect could alter the percutaneous absorption of substances in a number of ways, as we will see. Potential effects are described for five monophasic vehicles, including the three most frequently used: water, ethanol, acetone; and two that are more rarely used, but are realistic: artificial sebum and artificial sweat. Finally, we discuss a number of criteria to be verified and the associated tests that should be performed when choosing the most appropriate vehicle, keeping in mind that, in the context of occupational exposure, the scientific quality of the percutaneous absorption data provided, and how they are interpreted, may have long-range consequences. From the narrative review presented, we also identify and discuss important factors to consider in future updates of the OECD guidelines for in vitro skin absorption experiments.

Type 2 Diabetes Mellitus with Early Dry Skin Disorder: A Comparison Study Between Primary and Tertiary Care in Indonesia

BACKGROUND

The prevalence of Type 2 Diabetes Mellitus (T2DM) in Indonesia has continued to increase over the years. Management of T2DM is challenging across clinical settings, including primary and tertiary care. Uncontrolled T2DM puts patients at risk of the development of T2DM complications, especially early-stage dry skin that is neglected by most of the patients. This study aimed to investigate the comparison between the T2DM management profile and dry skin clinical profile of T2DM patients in primary care and tertiary care settings.

METHODS

The study was conducted as a cross-sectional epidemiological study by comparing T2DM patient profiles in primary and tertiary care. The data collected included sociodemographic, clinical, and laboratory data that were correlated with T2DM and early dry skin related-T2DM. This study included early dry skin within the SRRC score of 3-11 and excluded infection, ulcer, and severe erythema.

RESULTS

The patients in primary and tertiary care presented poorly controlled T2DM with median HbA1c levels of 7.8% and 7.6%. The patients in primary care also presented with high triglyceride, 179 mg/dl. Furthermore, several significant differences were found in the duration of T2DM, duration of dry skin, and DM treatment (OAD and insulin).

CONCLUSION

Significant differences in the duration of T2DM, duration of dry skin, and DM treatment (OAD and insulin) might be affected by the parameter of T2DM glycemic control (Blood pressure (BP), body mass index (BMI), HbA1c, random blood glucose (RBG), and triglyceride).

Topical and transdermal delivery with diseased human skin: passive and iontophoretic delivery of hydrocortisone into psoriatic and eczematous skin

Psoriasis and atopic dermatitis (eczema) are both common immune-mediated inflammatory skin diseases associated with changes in skin's stratum corneum lipid structure and barrier functionality. The present study aimed to investigate healthy, eczematous, and psoriatic excised human tissue for the effect of non-infectious skin diseases on skin characteristics (surface color, pH, transepidermal water loss, electrical resistance, and histology), as well as on permeation and retention profile of hydrocortisone. Further, differences in percutaneous absorption on application of iontophoresis on healthy and diseased skin were also investigated. Measurements of transepidermal water loss and electrical resistance showed a significant difference in psoriasis skin samples indicating a damaged barrier function. In vitro permeation studies on full-thickness human skin using vertical diffusion cells further confirmed these results as the drug amount retained in the psoriatic tissue was significantly higher when compared with the other groups. Despite no significant difference, the presence of the drug in the receptor chamber in both diseased groups can be concerning as it suggests the increased possibility of systemic absorption and adverse reactions associated with it in the use of topical corticosteroids. Application of anodal iontophoresis resulted in greater distribution of hydrocortisone into deeper layers of skin and the receptor chamber, in comparison to passive permeation. However, no significant differences were observed due to the healthy or diseased condition of skin.

The impact of external factors on psoriasis

Psoriasis is one of the most common chronic inflammatory skin diseases, constituting a significant health and socioeconomic problem. Despite numerous therapeutic options, the results of treatment very often remain insufficient. It is extremely important to remember that many external factors impact the effectiveness of therapy. This article discusses the importance of emollients in therapy and the influence of infectious agents and injuries on the course of psoriasis. Understanding the above-mentioned factors in the treatment of psoriasis is critical to achieve satisfactory therapeutic effects.

Molecular characterization of xerosis cutis: A systematic review

Background

Xerosis cutis or dry skin is a highly prevalent dermatological disorder especially in the elderly and in patients with underlying health conditions. In the past decades, numerous molecular markers have been investigated for their association with the occurrence or severity of skin dryness. The aim of this review was to summarize the molecular markers used in xerosis cutis research and to describe possible associations with different dry skin etiologies.

Methods

We conducted a systematic review of molecular markers of xerosis cutis caused by internal or systemic changes. References published between 1990 and September 2020 were searched using ‘MEDLINE’, ‘EMBASE’ and ‘Biological abstracts’ databases. Study results were summarized and analyzed descriptively. The review protocol was registered in PROSPERO database (CRD42020214173).

Results

A total of 21 study reports describing 72 molecules were identified including lipids, natural moisturizing factors (NMFs), proteins including cytokines and metabolites or metabolic products. Most frequently reported markers were ceramides, total free fatty acids, triglycerides and selected components of NMFs. Thirty-one markers were reported only once. Although, associations of these molecular markers with skin dryness were described, reports of unclear and/or no association were also frequent for nearly every marker.

Conclusion

An unexpectedly high number of various molecules to quantify xerosis cutis was found. There is substantial heterogeneity regarding molecular marker selection, tissue sampling and laboratory analyses. Empirical evidence is also heterogeneous regarding possible associations with dry skin. Total free fatty acids, total ceramide, ceramide (NP), ceramide (NS), triglyceride, total free amino acids and serine seem to be relevant, but the association with dry skin is inconsistent. Although the quantification of molecular markers plays an important role in characterizing biological processes, pathogenic processes or pharmacologic responses, it is currently unclear which molecules work best in xerosis cutis.

Barrier disruption, dehydration and inflammation: Investigation of the vicious circle underlying dry skin

OBJECTIVE

Many endogenous or exogenous factors, isolated or combined, can trigger dry skin disorder, leading to a water/lipids-depleted stratum corneum concomitant with uncomfortable rough and scaly skin surface. In a defensive reaction, the alteration of the skin barrier stimulates the production of cytokines to initiate homeostasis restoration but this can also induce an inflammatory response that further weakens the barrier. The two phenomena intertwining one another lead to the creation of a vicious circle, here called Inflamm'dryness, that maintains dry skin state. It is thus very important to investigate biological mechanisms involved in Inflamm'dryness to better manage dry skin.

METHODS

A 3D model mimicking dry skin has been developed. Adjustment of tape stripping level allowed to reproduce skin barrier alterations and resulting inflammation involved in dry skin. The effect of Helichrysum stoechas extract on this downward spiral was then investigated to validate the concept.

RESULTS

Tape-stripping permitted to successively remove the cell layers of the stratum corneum: the barrier function was altered and skin was inflamed creating a vicious circle, mimicking very dry skin prone to Inflamm'dryness. Helichrysum stoechas extract was not only able to resolve inflammation but also to reverse concurrently adverse tape-stripping effects and imparted significant structural and functional recovery of the barrier (e.g. on NMF and ceramides levels, TEWL, tissue organization).

CONCLUSION

This 3D model reproduces Inflamm'dryness vicious circle present in dry skin and highlights the importance of breaking this process to improve dry skin conditions. Helichrysum stoechas extract is a promising active ingredient for the management of dry skin.

The presurgical controlling nutritional status (CONUT) score is independently associated with severe peristomal skin disorders: a single-center retrospective cohort study

While nutritional interventions may potentially lower the risk of peristomal skin disorders (PSDs) and their exacerbation, no previous studies have evaluated the relationship between PSDs and nutritional status using the Controlling Nutritional Status (CONUT) score. The purpose of this study was to assess the impact of preoperative nutritional status on stoma health, and determine risk factors for postoperative PSDs, including severe PSDs. A retrospective analysis was performed of 116 consecutive patients with rectal cancer who underwent radical surgery with ileostomy or colostomy creation. PSDs were diagnosed in 32 patients (27.6%); including 10 cases (8.7%) that were defined as severe based on the ABCD-stoma score. Multivariable logistic regression showed that smoking (odds ratio [OR] 3.451, 95% confidence interval [CI] 1.240–9.607, p = 0.018) and ileostomy (OR 3.287, 95% CI 1.278–8.458, p = 0.014) were independent risk factors for PSDs. A separate multivariable logistic regression analysis of risk factors for severe PSDs, found that the only independent risk factor was the CONUT score (OR 10.040, 95% CI 1.191–84.651, p = 0.034). Severe PSDs are associated with preoperative nutritional disorders, as determined by the CONUT score. Furthermore, nutritional disorders may increase the severity of PSDs, regardless of the stoma type.

Standardized Edible Bird's Nest Extract Prevents UVB Irradiation-Mediated Oxidative Stress and Photoaging in the Skin

We investigated whether standardized edible bird’s nest extract (BNE-PK) can prevent ultraviolet B (UVB) irradiation-mediated oxidative stress and photoaging in the skin using in vitro and in vivo models. BNE-PK increased skin hydration by hyaluronic acid synthesis and activation of ceramide synthase in UVB-irradiated hairless mice and HaCaT cells. Furthermore, BNE-PK suppressed melanogenesis by down-regulation of the cAMP/PKA/CREB/MITF/TRP-1/TRP-2/tyrosinase pathway in UVB-irradiated hairless mice and 3-isobutyl-1-methylxanthine (IBMX)-treated B16F10 cells. In UVB-irradiated hairless mice, BNE-PK attenuated the wrinkle formation-related JNK/c-FOS/c-Jun/MMP pathway and activated the TGF-βRI/SMAD3/pro-collagen type I pathway during UVB-mediated oxidative stress. Based on these findings, our data suggest that BNE-PK may potentially be used for the development of effective natural anti-photoaging functional foods for skin health.

Alterations of Ultra Long-Chain Fatty Acids in Hereditary Skin Diseases-Review Article

The skin is a flexible organ that forms a barrier between the environment and the body's interior; it is involved in the immune response, in protection and regulation, and is a dynamic environment in which skin lipids play an important role in maintaining homeostasis. The different layers of the skin differ in both the composition and amount of lipids. The epidermis displays the best characteristics in this respect. The main lipids in this layer are cholesterol, fatty acids (FAs) and ceramides. FAs can occur in free form and as components of complex molecules. The most poorly characterized FAs are very long-chain fatty acids (VLCFAs) and ultra long-chain fatty acids (ULCFAs). VLCFAs and ULCFAs are among the main components of ceramides and are part of the free fatty acid (FFA) fraction. They are most abundant in the brain, liver, kidneys, and skin. VLCFAs and ULCFAs are responsible for the rigidity and impermeability of membranes, forming the mechanically and chemically strong outer layer of cell membranes. Any changes in the composition and length of the carbon chains of FAs result in a change in their melting point and therefore a change in membrane permeability. One of the factors causing a decrease in the amount of VLCFAs and ULCFAs is an improper diet. Another much more important factor is mutations in the genes which code proteins involved in the metabolism of VLCFAs and ULCFAs—regarding their elongation, their attachment to ceramides and their transformation. These mutations have their clinical consequences in the form of inborn errors in metabolism and neurodegenerative disorders, among others. Some of them are accompanied by skin symptoms such as ichthyosis and ichthyosiform erythroderma. In the following review, the structure of the skin is briefly characterized and the most important lipid components of the skin are presented. The focus is also on providing an overview of selected proteins involved in the metabolism of VLCFAs and ULCFAs in the skin.

The Manufacture of Unbreakable Bionics via Multifunctional and Self-Healing Silk-Graphene Hydrogels

Biomaterials capable of transmitting signals over longer distances than those in rigid electronics can open new opportunities for humanity by mimicking the way tissues propagate information. For seamless mirroring of the human body, they also have to display conformability to its curvilinear architecture, as well as, reproducing native-like mechanical and electrical properties combined with the ability to self-heal on demand like native organs and tissues. Along these lines, a multifunctional composite is developed by mixing silk fibroin and reduced graphene oxide. The material is coined "CareGum" and capitalizes on a phenolic glue to facilitate sacrificial and hierarchical hydrogen bonds. The hierarchal bonding scheme gives rise to high mechanical toughness, record-breaking elongation capacity of ≈25 000%, excellent conformability to arbitrary and complex surfaces, 3D printability, a tenfold increase in electrical conductivity, and a fourfold increase in Young's modulus compared to its pristine counterpart. By taking advantage of these unique properties, a durable and self-healing bionic glove is developed for hand gesture sensing and sign translation. Indeed, CareGum is a new advanced material with promising applications in fields like cyborganics, bionics, soft robotics, human-machine interfaces, 3D-printed electronics, and flexible bioelectronics.

Integratomics of Human Dermal Fibroblasts Treated with Low Molecular Weight Hyaluronic Acid

Hyaluronic acid (HA) is a glycosaminoglycan very common in commercial products from pharmaceuticals to cosmetics due to its widespread distribution in humans and its diversified physico-chemical proprieties. Despite its extended use and preliminary evidence showing even also opposite activities to the native form, the precise cellular effects of HA at low-molecular-weight (LWM-HA) are currently unclear. The ‘omics sciences currently in development offer a new and combined perspective on the cellular and organismal environment. This work aims to integrate lipidomics analyses to our previous quantitative proteomics one for a multi-omics vision of intra- and extra-cellular impact of different concentrations (0.125, 0.25, and 0.50%) of LMW-HA (20–50 kDa) on normal human dermal fibroblasts by LC-high resolution mass spectrometry (LC-HRMS). Untargeted lipidomics allowed us to identify 903 unique lipids mostly represented by triacylglycerols, ceramides, and phosphatidylcholines. According to proteomics analyses, LMW-HA 0.50% was the most effective concentration also in the lipidome rearrangement especially stimulating the synthesis of ceramides involved in skin hydration and reparation, cell signaling, and energy balance. Finally, integrative analyses showed 25 nodes covering several intra- and extra-cellular functions. The more complete comprehension of intra- and extra-cellular effects of LMW-HA here pointed out will be useful to further exploit its features and improve current formulations even though further studies on lipids biosynthesis and degradation are necessary.

Increased Levels of Short-Chain Ceramides Modify the Lipid Organization and Reduce the Lipid Barrier of Skin Model Membranes

The skin barrier function is attributed to the stratum corneum (SC) intercellular lipid matrix, which is composed primarily of ceramides (CERs), free fatty acids, and cholesterol. These lipids are organized in two lamellar phases: the short and long periodicity phases (SPP and LPP), respectively. The LPP is considered important for the skin barrier function. High levels of short-chain CERs are observed in various inflammatory skin diseases and have been correlated with barrier dysfunction. In this research, we investigated how the increase in the fraction of the short-chain CER with a nonhydroxy C16 acyl chain linked to a C18 sphingosine base CER NS(C16) at the expense of the physiological chain length CER NS with a C24 acyl chain (CER NS(C24)) impacts the microstructure and barrier function of a lipid model that mimicked certain characteristics of the SC lipid organization. The permeability and lipid organization of the model membranes were compared with that of a control model without CER NS(C16). The permeability increased significantly when ≥50% of CER NS(C24) was substituted with CER NS(C16). Employing biophysical techniques, we showed that the lipid packing density reduced with an increasing proportion of CER NS(C16). Substitution of 75% of CER NS(C24) by CER NS(C16) resulted in the formation of phase-separated lipid domains and alteration of the LPP structure. Using deuterium-labeled lipids enabled simultaneous characterization of the C24 and C16 acyl chains in the lipid models, providing insight into the mechanisms underlying the reduced skin barrier function in diseased skin.

SLIDE-Novel Approach to Apocrine Sweat Sampling for Lipid Profiling in Healthy Individuals

We designed a concept of 3D-printed attachment with porous glass filter disks—SLIDE (Sweat sampLIng DevicE) for easy sampling of apocrine sweat. By applying advanced mass spectrometry coupled with the liquid chromatography technique, the complex lipid profiles were measured to evaluate the reproducibility and robustness of this novel approach. Moreover, our in-depth statistical evaluation of the data provided an insight into the potential use of apocrine sweat as a novel and diagnostically relevant biofluid for clinical analyses. Data transformation using probabilistic quotient normalization (PQN) significantly improved the analytical characteristics and overcame the ‘sample dilution issue’ of the sampling. The lipidomic content of apocrine sweat from healthy subjects was described in terms of identification and quantitation. A total of 240 lipids across 15 classes were identified. The lipid concentrations varied from 10⁻¹⁰ to 10⁻⁴ mol/L. The most numerous class of lipids were ceramides (n = 61), while the free fatty acids were the most abundant ones (average concentrations of 10⁻⁵ mol/L). The main advantages of apocrine sweat microsampling include: (a) the non-invasiveness of the procedure and (b) the unique feature of apocrine sweat, reflecting metabolome and lipidome of the intracellular space and plasmatic membranes. The SLIDE application as a sampling technique of apocrine sweat brings a promising alternative, including various possibilities in modern clinical practice.

Decrease of ceramides with long-chain fatty acids in psoriasis: Possible inhibitory effect of interferon gamma on chain elongation

Reportedly, decreases in fatty acid (FA) chain length of ceramide (CER) are associated with interferon-γ (IFN-γ), which shows increased expression in psoriasis. However, the underlying mechanism of this association remains unclear. Therefore, in this study, we aimed to clarify this association between FA chain length of CER, IFN-γ, and the major transcriptional factors involving psoriasis. CER profiling according to FA chain length and class was performed in murine epidermis (n = 10 BALB/c mice topically treated with imiquimod, n = 10 controls) and human stratum corneum (SC) (n = 12 psoriasis, n = 11 controls). The expression of lipid synthetic enzymes, including elongases (ELOVLs), in murine epidermis was also measured using RT-PCR. Furthermore, the association of IFN-γ with various enzymes and transcription factors involved in the generation of long-chain CERs was also investigated using in vitro keratinocyte. A significant decrease in the percentage of long-chain CERs was observed in psoriasis-like murine epidermis and human psoriatic SC. Additionally, the expression levels of ELOVL1, ELOVL4, and ceramide synthase3 (CerS3) were significantly decreased in psoriasis-like murine epidermis and IFN-γ-treated keratinocyte. There was also a significant decrease in the expression of transcriptional factors, including peroxisome proliferator-activated receptor (PPAR), in IFN-γ treated keratinocyte. Thus, it could be suggested that IFN-γ may regulate ELOVL and CerS levels by down-regulating the transcriptional factors. Additionally, given the possible involvement of PPARs or liver X receptor agonist in the CER elongation process, they may serve as potential therapeutic agents for lengthening the CER FAs in psoriasis.

Role of Centella asiatica and ceramide in skin barrier improvement: a double blind clinical trial of Indonesian batik workers

OBJECTIVES

Batik dyes contain irritant chemicals that increase the risk of skin barrier disruption. This study aims to determine the effect of Centella asiatica and ceramide in transepidermal water loss (TEWL), hydration of the stratum corneum and skin acidity (pH).

METHODS

This was a double blind clinical trial of 30 Indonesian batik workers who suffered from skin dryness, but had no clinical manifestation of contact dermatitis. Subjects were given cream containing C. asiatica or ceramide that formulated and randomly labeled by manufacturer (PT Paragon Technology and Innovation). Both subjects and researchers were blinded to the type of the cream. Cream was applied to the hands and arms twice a day. Biological function of the skin (TEWL, stratum corneum hydration level, and skin acidity) was examined by Cutometer dual MP-580. Baseline was recorded in the first examination, followed by second and third examinations at two and four weeks after treatment.

RESULTS

After four weeks treatment, there were significant improvement of C. asiatica application in evaluation of corneometer palmar (p=0.007; CI 95%), corneometer dorsum (p=0.001; CI 95%), and skin acidity dorsum (p=0.017; CI 95%). Ceramide application also gave significant improvement of corneometer palmar (0.038; CI 95%), skin acidity palmar (p=0.001; CI 95%), TEWL dorsum (p=0.023; CI 95%), corneometer dorsum (p=0.002; CI 95%) and skin acidity dorsum (p=0.011; CI 95%). There were no significant differences of C. asiatica effectiveness compared to ceramide in skin barrier improvement.

CONCLUSIONS

C. asiatica and ceramide can improve skin barrier hydration in order to prevent the risk of contact dermatitis in batik workers.

Differences in the Fatty Acid Profile, Morphology, and Tetraacetylphytosphingosine-Forming Capability Between Wild-Type and Mutant Wickerhamomyces ciferrii

One tetraacetylphytosphingosine (TAPS)-producing Wickerhamomyces ciferrii mutant was obtained by exposing wild-type W. ciferrii to γ-ray irradiation. The mutant named 736 produced up to 9.1 g/L of TAPS (218.7 mg-TAPS/g-DCW) during batch fermentation in comparison with 1.7 g/L of TAPS (52.2 mg-TAPS/g-DCW) for the wild type. The highest production, 17.7 g/L of TAPS (259.6 mg-TAPS/g-DCW), was obtained during fed-batch fermentation by mutant 736. Fatty acid (FA) analysis revealed an altered cellular FA profile of mutant 736: decrease in C16:0 and C16:1 FA levels, and increase in C18:1 and C18:2 FA levels. Although a significant change in the cellular FA profile was observed, scanning electron micrographs showed that morphology of wild-type and mutant 736 cells was similar. Genetic alteration analysis of eight TAPS biosynthesis-related genes revealed that there are no mutations in these genes in mutant 736; however, mRNA expression analysis indicated 30% higher mRNA expression of TCS10 among the eight genes in mutant 736 than that in the wild-type. Collectively, these results imply that the enhancement of TAPS biosynthesis in mutant 736 may be a consequence of system-level genetic and physiological alterations of a complicated metabolic network. Reverse metabolic engineering based on system-level omics analysis of mutant 736 can make the mutant more suitable for commercial production of TAPS.

Skin lipids in health and disease: A review

Our skin is the interface between us and our environment - a flexible barrier that has evolved for protection, immunity, regulation and sensation. Once regarded as inert, we now know that it is a dynamic environment. Skin lipids are crucial to the structure and function of skin. From deep in the hypodermis, through the ceramide-rich epidermis, to the lipids of the skin surface, there are a vast array of different lipids with important roles to play. This review firstly discusses the lipid composition of human skin and secondly, changes that have been found in skin lipid composition in different skin diseases. Further research into skin lipids facilitated by ever-improving methodologies will no doubt generate new knowledge, paving the way for diagnosis, prevention and treatment of skin disorders and diseases.

Colonization With Staphylococcus aureus in Atopic Dermatitis Patients: Attempts to Reveal the Unknown

Atopic dermatitis (AD) patients are massively colonized with Staphylococcus aureus (S. aureus) in lesional and non-lesional skin. A skin infection may become systemic if left untreated. Of interest, the incidence of multi-drug resistant S. aureus (MRSA) in AD patients is higher as compared to a healthy population, which makes treatment even more challenging. Information on the specific genetic background of S. aureus accompanying and/or causing AD flares would be of great importance in terms of possible treatment option development. In this review, we summarized the data on the prevalence of S. aureus in general in AD skin, and the prevalence of specific clones that might be associated with flares of eczema. We put our special interest in the presence and role of staphylococcal enterotoxins as important virulence factors in the epidemiology of AD-derived S. aureus. Also, we summarize the present and potentially useful future anti-staphylococcal treatment.

The noncanonical chronicles: Emerging roles of sphingolipid structural variants

Sphingolipids (SPs) are structurally diverse and represent one of the most quantitatively abundant classes of lipids in mammalian cells. In addition to their structural roles, many SP species are known to be bioactive mediators of essential cellular processes. Historically, studies have focused on SP species that contain the canonical 18‑carbon, mono-unsaturated sphingoid backbone. However, increasingly sensitive analytical technologies, driven by advances in mass spectrometry, have facilitated the identification of previously under-appreciated, molecularly distinct SP species. Many of these less abundant species contain noncanonical backbones. Interestingly, a growing number of studies have identified clinical associations between these noncanonical SPs and disease, suggesting that there is functional significance to the alteration of SP backbone structure. For example, associations have been found between SP chain length and cardiovascular disease, pain, diabetes, and dementia. This review will provide an overview of the processes that are known to regulate noncanonical SP accumulation, describe the clinical correlations reported for these molecules, and review the experimental evidence for the potential functional implications of their dysregulation. It is likely that further scrutiny of noncanonical SPs may provide new insight into pathophysiological processes, serve as useful biomarkers for disease, and lead to the design of novel therapeutic strategies.

Engineering Yarrowia lipolytica for de novo production of tetraacetyl phytosphingosine

AIMS

To genetically engineer the oleaginous yeast Yarrowia lipolytica for de novo production of tetraacetylphytosphingosine (TAPS), a precursor of phytosphingosine, and optimization of fermentation conditions for high yield.

METHODS AND RESULTS

We successfully constructed a TAPS-producing Y. lipolytica CE3 strain by co-expression of Wickerhamomyces ciferrii-derived acetyl transferases, Sli1p and Atf2p. Next, we optimized several environmental factors including temperature, initial pH and C/N ratio for TAPS production in a shake culture. Deletion of LCB4 in CE3 strain increased the volumetric TAPS titre and cell-specific yield to 142·1 ± 10·7 mg_TAPS  l^-1 and 3·08 ± 0·11 mg_TAPS  g_DCW ^-1 , respectively, in a shake flask culture incubated for 120 h at 28°C with glycerol as the carbon source. Finally, we developed a 5-l fed-batch process with NaOH-mediated pH control and olive oil as a carbon source, exhibiting 650 ± 24 mg_TAPS  l^-1 of TAPS production within 56 h of the fermentation.

CONCLUSIONS

The introduction of codon-optimized Sli1p and Atf2p, deletion of LCB4 gene and sexual hybridization, accompanied by specific fermentation conditions, enhanced TAPS yield in Y. lipolytica.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our results highlight Y. lipolytica as a promising candidate for the industrial production of TAPS, an important component of cosmetic formulations.

High concentration of the ester-linked ω-hydroxy ceramide increases the permeability in skin lipid model membranes

The ester-linked ω-hydroxy acyl chain linked to a sphingosine base referred to as CER EOS is essential for the skin barrier lipid organization. While the majority of the skin lipids form a dense, crystalline structure, associated with low permeability, the unsaturated moiety of CER EOS, (either the linoleate or the oleate chain) exists in a liquid phase at the skin's physiological temperature. Thus, the relationship between CER EOS and barrier function is not entirely comprehended. We studied the permeability and lipid organization in skin lipid models, gradually increasing in CER EOS concentration, mixed with non-hydroxy sphingosine-based ceramide (CER NS) in an equimolar ratio of CERs, cholesterol, and free fatty acids (FFAs) mimicking the ratio in the native skin. A significant increase in the orthorhombic-hexagonal phase transition temperature was recorded when CER EOS concentration was raised to 70 mol% of the total CER content and higher, rendering a higher fraction of lipids in the orthorhombic phase at the expense of the hexagonal phase at physiological temperature. The model's permeability did not differ when CER EOS concentration ranged between 10 and 30% but increased significantly at 70% and higher. Using CER EOS with a perdeuterated oleate chain, it was shown that the fraction of lipids in a liquid phase increased with CER EOS concentration, while the neighboring CERs and FFAs remained in a crystalline state. The increased fraction of the liquid phase therefore, had a stronger effect on permeability than the increased fraction of lipids forming an orthorhombic phase.

Safety and Efficacy of Oral Intake of Ceramide-Containing Acetic Acid Bacteria for Improving the Stratum Corneum Hydration: A Randomized, Double-Blind, Placebo-Controlled Study over 12 Weeks

The barrier function of the skin protects it from external stresses to which it is constantly exposed, such as dryness, ultraviolet rays, and chemicals. Lipids, in particular a type of sphingolipid known as ceramides, play a central role in the barrier function of the skin by preventing dryness. The number of ceramides in the skin is known to decrease with age, which has led to the development of a large number of anti-aging cosmetic products that contain ceramides. Recently, it has become evident that oral intake of ceramides can also improve the quality of the skin. To elucidate the effects of oral ceramide intake on skin moisture content, we conducted a randomized, double-blinded, placebo-controlled parallel comparative study in which males and females between 20 and 60 years of age who were worried about dry skin ingested a food with acetic acid bacteria containing 0.8 mg of dihydroceramide or a placebo for 12 weeks. Concurrently, we investigated the safety of continuous ingestion of the ceramide-containing food over 12 weeks. Oral intake of ceramide over the 12 weeks significantly improved stratum corneum hydration, i.e. the moisture content of the skin, and did not result in harmful effects in any of the participants.

Release of Ceramide Molecules from Ceramide-Containing UV-curable Acrylic Adhesive Gel Sheet Affixed to Human Skin

Ceramide, an intercellular lipid of the stratum corneum, plays an essential role in making the skin barrier. One problem with the use of medical adhesive tape or sheets for skin is that their repeated attachment and detachment may cause some damage to the skin. An attempt has been made to eliminate this problem by mixing ceramide into the adhesive of sheets, and has delivered excellent clinical results. This study aimed to investigate whether ceramide is transferred from the adhesive with added ceramide to the skin. An adhesive sheet was prepared by adding synthetic ceramide (CER) to UV-curable acrylic adhesive gel. After affixing the adhesive sheet to human skin for a certain period, it was peeled off and cut perpendicular to the adhesive surface. Synchrotron micro-infrared spectroscopy of the sectioned samples showed that the ceramide concentration in the gel sheet decreases as the application time to human skin increases. This is thought to be due to the release of CER from the gel sheet.

Efficacy and safety of a topical moisturizer containing linoleic acid and ceramide for mild-to-moderate psoriasis vulgaris: A multicenter randomized controlled trial

Psoriasis is a chronic, recurrent skin disease requiring long-term management. Agents that repair the skin's barrier function are invaluable additives in topical treatments of psoriasis. This multicenter, randomized, controlled trial evaluated the efficacy and safety of a linoleic acid-ceramide-containing moisturizer (LA-Cer) for mild-to-moderate psoriasis vulgaris. We randomized 178 patients from both northern and southern regions of China into two groups: 81 patients in the control group received mometasone furoate (MF, 0.1%) cream, while MF in combination with LA-Cer was administered to 86 patients in the treatment group for 4 weeks. The LA-Cer-MF group maintained the use of moisturizer after topical glucocorticoid administration. The primary endpoint, Psoriasis Area and Severity Index 50 (PASI 50) response, revealed the superiority of LA-Cer-MF with lower relapse rates at week 8. The use of the LA-Cer-containing moisturizer as maintenance therapy resulted in a continuous improvement in the clinical state in terms of body surface area, PASI, investigators' assessment of skin dryness and desquamation, and Physician Global Assessment of Psoriasis score, and in the patients' quality of life. Thus, the LA-Cer-containing moisturizer is a promising agent to prevent and treat psoriasis as it enhances the therapeutic effect induced by topical glucocorticoids and delays relapse.

Cancer stem cells and ceramide signaling: the cutting edges of immunotherapy

The multipotent, self renewing "cancer stem cells" (CSCs), a small population within tumor microenvironment facilitates transformed cells to grow and propagate within the body. The CSCs are discovered as resistant to the chemotherapeutic drug with distinct immunological characteristics. In recent years, immunologically targeting CSCs have emerged as an integral part of effective and successful cancer therapy. CSCs notably exhibit dysregulation in conventional sub-cellular sphingolipid metabolism. Recently, ceramide decaying enzymes have been shown to activate alternative ceramide signaling pathways leading to reduction in efficacy of the chemotherapeutic drugs. Therefore, a control over ceramide mediated modulations of CSCs offers an attractive dimension of effective cancer treatment strategy in future. In this review, we focused on the recent findings on broad spectrum of ceramide mediated signaling in CSCs within the tumor niche and their role in potential cancer immunotherapy.

Association of dry skin with intercellular lipid composition of stratum corneum after erlotinib administration

PURPOSE

Erlotinib, an inhibitor of the epidermal growth factor receptor tyrosine kinase, causes skin disorders such as dry skin, which impairs the skin barrier function. Stratum corneum (SC) lipids play an important role in skin barrier function; therefore, this study aimed to investigate the relationship between erlotinib-related dry skin and changes in the intercellular lipid composition and structure of the SC.

METHODS

Overall, 21 patients with non-small lung cancer were enrolled in this study. All patients received 150 mg/day erlotinib orally. A SC sample of each patient was collected from the inner forearm using the tape stripping method on days 0, 7, 14, 28, and 56 after erlotinib administration. The intercellular lipid components of ceramide (CER), free fatty acid (FFA), and cholesterol sulfate (CS) in samples extracted from the tape were analyzed using liquid chromatography/time-of-flight/mass spectrometry. SC samples from six healthy subjects were collected as controls on days 0, 28 and 56 and analyzed similarly.

RESULTS

Although total CER and FFA levels were not changed after erlotinib administration, the levels of CER subclasses [AP] and [AH] and hydroxy FFA, which are structural components of CER subclass [A], decreased. In contrast, the CS levels increased after erlotinib administration. Moreover, higher CS levels in the SC correlated with the clinical condition of dry skin. No changes were observed in the SC lipid composition in healthy subjects.

CONCLUSION

Erlotinib-related dry skin was associated with a higher CS level in the SC.

PKCζ mediated anti-proliferative effect of C2 ceramide on neutralization of the tumor microenvironment and melanoma regression

Immunotherapy, which has advantages over chemotherapy due to lesser toxicity and higher specificity, is on the rise to treat cancer. Recently, pro-apoptotic glycolipid, ceramide has emerged as a key regulator in cancer immunotherapy. The present study elucidated the potential anti-melanoma efficacy of cell-permeable, exogenous C2 ceramide on cell death and amelioration of tumor microenvironment (TME). We, for the first time, demonstrated that C2 ceramide triggered apoptosis of melanoma cells by augmenting PKCζ along with pro-inflammatory cytokines and signaling factors. C2 ceramide showed a PKCζ-mediated tumor-suppressive role in melanoma without exhibiting hepatotoxicity and nephrotoxicity. Moreover, PKCζ was revealed as one of the key regulators of Akt and ceramide during C2 ceramide-mediated apoptosis. C2 ceramide was effective in repolarization of M2 macrophage phenotype and reduction of angiogenic factors such as VEGF, VEGFR1, VEGFR2, HIF1α. Interestingly, PKCζ knockdown attenuated C2 ceramide-mediated inhibition of melanoma progression. Restoration of the Th1 type TME by C2 ceramide enhanced cytotoxic T cell-mediated killing of melanoma cells. Altogether, the study unraveled that C2 ceramide-induced PKCζ was associated with favorable immune cell functioning in TME leading to melanoma regression. Thus, our findings explored a novel mechanistic insight into C2 ceramide as a promising immunotherapeutic agent in melanoma treatment.

Sphingolipids in food and their critical roles in human health

Sphingolipids (SLs) are ubiquitous structural components of cell membranes and are essential for cell functions under physiological conditions or during disease progression. Abundant evidence supports that SLs and their metabolites, including ceramide (Cer), ceramide-1-phosphate (C1P), sphingosine (So), sphingosine-1-phosphate (S1P), are signaling molecules that regulate a diverse range of cellular processes and human health. However, there are limited reviews on the emerging roles of exogenous dietary SLs in human health. In this review, we discuss the ubiquitous presence of dietary SLs, highlighting their structures and contents in foodstuffs, particularly in sea foods. The digestion and metabolism of dietary SLs is also discussed. Focus is given to the roles of SLs in both the etiology and prevention of diseases, including bacterial infection, cancers, neurogenesis and neurodegenerative diseases, skin integrity, and metabolic syndrome (MetS). We propose that dietary SLs represent a "functional" constituent as emerging strategies for improving human health. Gaps in research that could be of future interest are also discussed.

Glucocerebrosidase: Functions in and Beyond the Lysosome

Glucocerebrosidase (GCase) is a retaining β-glucosidase with acid pH optimum metabolizing the glycosphingolipid glucosylceramide (GlcCer) to ceramide and glucose. Inherited deficiency of GCase causes the lysosomal storage disorder named Gaucher disease (GD). In GCase-deficient GD patients the accumulation of GlcCer in lysosomes of tissue macrophages is prominent. Based on the above, the key function of GCase as lysosomal hydrolase is well recognized, however it has become apparent that GCase fulfills in the human body at least one other key function beyond lysosomes. Crucially, GCase generates ceramides from GlcCer molecules in the outer part of the skin, a process essential for optimal skin barrier property and survival. This review covers the functions of GCase in and beyond lysosomes and also pays attention to the increasing insight in hitherto unexpected catalytic versatility of the enzyme.

Lipidomic Analysis Reveals Specific Differences between Fibroblast and Keratinocyte Ceramide Profile of Patients with Psoriasis Vulgaris

Ceramides are important lipid metabolites for primal skin functions. There is increasing evidence that alteration of the profile and metabolism of ceramides is associated with skin diseases, such as psoriasis vulgaris. Most studies have reported alteration in ceramide content in the stratum corneum, but these have been scarcely reported for other skin layers. In the present work, we aimed to explore changes in the ceramide profile of fibroblasts and keratinocytes in patients with psoriasis vulgaris and healthy subjects. Using the reversed-phase liquid chromatography-quadrupole-time-of-flight-tandem-mass spectrometry (RPLC-QTOF-MS/MS) platform, we identified ceramide containing non-hydroxy fatty acid ([N]), α-hydroxy fatty acid ([A]), and esterified ω-hydroxy fatty acid ([EO]) and 3 sphingoid bases, dihydrosphingosine ([DS]), sphingosine ([S]), and phytosphingosine ([P]). We found that in the keratinocytes of patients with psoriasis, CER[NS], CER[NP], CER[AS], CER[ADS], CER[AP] and CER[EOS] tended to be expressed at higher relative levels, whereas CER[NDS] tended to be expressed with lower levels than in healthy subjects. In the case of fibroblasts, significant differences were observed, mainly in the three ceramide classes (CER[AS], CER[ADS] and CER[EOS]), which were expressed at significantly higher levels in patients with psoriasis. The most significant alteration in the fibroblasts involved elevated levels of CER[EOS] that contained ester-linked fatty acids. Our findings provide insights into the ceramide profile in the dermis and epidermis of patients with psoriasis and contribute for the research in this field, focusing on the role of keratinocyte-fibroblast crosstalk in the development of psoriasis vulgaris.

Epidermal Delivery of Retinyl Palmitate Loaded Transfersomes: Penetration and Biodistribution Studies

The alteration of retinoids levels in the skin can cause different disorders in the maturation of epithelial skin cells. Topical administration of these lipophilic molecules is a challenge that can be addressed by encapsulation into drug delivery systems. In this study, retinyl palmitate transferosomes formulated in cream were developed and the increases in the penetration of the active ingredients as well as the biodistribution were evaluated in vitro and in vivo. Transfersomes demonstrated a significant increase in the administration of retinyl palmitate to the epidermis by quantification of the active ingredients in the different layers of the skin, as well as by fluorescence microscopy of biopsies of non-dermatomized pig-ear skin. These results suggest that transfersomes may be an efficient vehicle for the delivery of retinoids to inner layers of the skin, such as the epidermis.