PHYTOSPHINGOSINE

This study aims to assess the efficacy of a novel N-acyl-phytosphingosine prepared from marula oil derived fatty acids (MO-CER NPs) in repairing impaired skin barrier function. MO-CER NPs were synthesized from N-acyl-phytosphingosine using marula oil as a fatty acid source. Their effects on skin barrier improvement were compared with those of conventional C18-CER NP. A 28-day clinical trial involving 32 subjects was conducted to evaluate the efficacy of a topical cream containing 0.05% MO-CER NPs on barrier-compromised skin. Treatment with MO-CER NPs alleviated UVB-induced barrier damage as effectively as C18-CER NP, evidenced by increased expression of filaggrin and loricrin and reduced count of sunburn cells. Notably, MO-CER NPs showed superior anti-inflammatory activity. Furthermore, MO-CER NPs upregulated key genes involved in ceramide biosynthesis, keratinocyte proliferation, and differentiation. The clinical trial confirmed that topical application of 0.05% MO-CER NPs significantly improved barrier function by reducing transepidermal water loss and erythema, while increasing skin thickness and density. MO-CER NPs demonstrated superior efficacy over conventional C18-CER NP in ameliorating skin barrier dysfunction and inflammation, highlighting its potential for improving barrier-compromised skin conditions.

The barrier function of the outermost layer of human skin, the stratum corneum (SC), arises from its multilamellar lipid matrix composed primarily of ceramides (CERs), cholesterol (CHOL), and free fatty acids (FFAs). Coarse-grained (CG) and atomistic molecular dynamics simulations have been used to study self-assembled multilayers comprising CERs NS, NP, AS, and AP, in pure CER systems and mixtures of CERs with CHOL and FFAs. Equilibrated CG configurations were reverse-mapped to recover atomistic details and analyzed to extract structures and hydrogen bonding. Simulations of pure CERs agreed with experimental trends: phytosphingosine CERs (NP and AP) exhibited more CO hydrogen bonds, consistent with lower amide I FTIR frequencies, than their sphingosine counterparts (NS and AS). Likewise, non-hydroxy CERs (NS and NP) exhibited more CO hydrogen bonding than their α-hydroxy analogs (AS and AP). CER mixtures with CHOL and FFA showed reduced CO hydrogen bonding compared to pure CERs, though this effect depended on water content. Hydroxyl location was critical: OH on the phytosphingosine base increased CO hydrogen bonding, whereas the α-hydroxy on the acyl chain reduced it. In CER NP:AP mixtures with CHOL and FFA, simulations reproduced the experimental repeat distances for NP-rich and AP-rich systems despite differences in hydrogen bonding. Simulations of multicomponent mixtures resembling the SC model of Bouwstra demonstrated the dominant effect of chain-length distribution, rather than CER hydrogen bonding, on permeability. This work shows how multiscale modeling integrated with experiments can uncover molecular mechanisms linking composition and SC barrier structure to interpret experimental results.

Keloid radiotherapy is clinically effective but has an incomplete underlying molecular mechanism and limited accessibility; we used X-ray exposure to identify effector pathways that replicate its antifibrotic benefits without further radiation. After collecting patient keloid samples, primary human keloid fibroblasts, and normal skin fibroblasts, nontargeted metabolomics and RNA sequencing were performed, identifying phytosphingosine (PHS) and KIF20A as key mediators of fibrosis and cell death in keloid radiotherapy. X-ray irradiation increased PHS release in keloid fibroblasts; exogenous PHS and X-ray irradiation independently induced cell death and reduced fibrosis; their combination exerted radiosensitization by boosting G2/M arrest and apoptosis while lowering fibrosis progression, and both PHS and irradiation reduced KIF20A, whose loss induced cell cycle arrest and apoptosis. Our findings reveal that X-ray irradiation enhances keloid fibroblast PHS secretion, which downregulates KIF20A to exert keloid therapeutic effects, and that topical PHS or KIF20A-targeting agents are immediately translatable alternatives for radiotherapy-ineligible patients.

Phytosphingosine (PHS), a sphingolipid-derived bioactive compound, exhibits multifunctional properties including antimicrobial activity, skin moisturization, and hydration, rendering it highly valuable for cosmetic and pharmaceutical applications. Through systematic metabolic engineering of  Saccharomyces cerevisiae , we achieved 82.62 mg/g DCW phytosphingosine (PHS) production via integrated pathway optimization and stress mitigation. Key strategies involved: (1) Knockout of  LCB4  (sphingoid long-chain base kinase),  SHM2  (serine hydroxymethyltransferase), and  CHA1  (l-serine deaminase) to block competitive pathways; (2) Overexpression of  TSC10  (3-ketosphingosine reductase),  SYR2  (sphingosine hydroxylase), and  LCB1/LCB2  (serine palmitoyltransferase) to amplify the PHS synthesis flux. Initial shake flask fermentation (96 h) yielded 15.31 mg/g DCW of PHS, with  ORM2  knockout providing a 73.6% productivity increase (26.54 mg/g DCW) despite inducing growth defects from sphingosine accumulation. We hypothesized that disrupted ORM2-mediated control of serine palmitoyltransferase activity might compromise ER homeostasis through sphingolipid imbalance, which was alleviated through  HAC1  overexpression to enhance unfolded protein response (UPR) capacity. Fed-batch fermentation under optimized conditions (40 mM serine, 0.5 mM palmitic acid, pH 5) demonstrated scalable production, delivering a 5.4-fold improvement over baseline. This work establishes UPR engineering as a critical strategy for resolving lipid toxicity constraints in yeast sphingolipid biosynthesis, while highlighting  S. cerevisiae 's potential as an industrial PHS production platform through coordinated pathway and stress response manipulation. The online version contains supplementary material available at 10.1007/s13205-025-04417-z.

Isotretinoin has been increasingly utilized for various dermatological diseases.However, the mechanism of action of isotretinoin on the skin, particularly the epidermis, remains unclear. This study aimed to investigate the intracellular metabolic alterations induced by isotretinoin in HaCaT cells. HaCaT cells were divided into three groups: Group A (control group), Group B(treated with 10 μM isotretinoin for 48 h), and Group C (treated with 10 μM isotretinoin for 7 d). An untargeted metabolomics analysis was employed using ultra-high performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-Q-TOF/MS). Multivariate data analyses were employed to identify distinguishing metabolites, and the Kyoto Encyclopedia of Genes and Genomes (KEGG) was utilized to assess potential metabolic pathways. Isotretinoin inhibited the proliferation of HaCaT cells in a dose-dependent manner. The OPLS-DA model displayed clear segmentation between the Group B and Group A, as well as between Group C and Group A. Compared to Group A, there were 115 significantly differentially metabolites in Group B, including glycerophosphocholine,adenosine,acetylcarnitine,creatine,Dl-lactate,hypoxanthine,uracil,LPC 18:1,creatine phosphate,5'-S-Methyl-5'-thioadenosine. In Group C, there were 140 significantly differentially expressed metabolites compared to Group A, including glycerophosphocholine, niacinamide, creatine, phytosphingosine, oleic acid, hypoxanthine, 1-Palmitoyl-sn-glycero-3-phosphocholine, Dl-lactate, 5'-S-Methyl-5'-thioadenosine and NG,NG-Dimethyl-L-arginine.A total of 30 metabolic pathways were significantly changed (p < 0.05) in Group A and Group B.The most significant metabolic pathways included purine metabolism,nucleotide metabolism,ABC transporters, and the taurine and hypotaurine metabolism signaling pathway. Additionally, 46 metabolic pathways were significantly altered (p < 0.05) in Group A and Group C, with the most significant pathways being nucleotide metabolism, ABC transporters, purine metabolism, and glycerophospholipid metabolism. Important metabolites and metabolic pathways were identified in this study,which will help clarify the underlying mechanism of action of isotretinoin on keratinocytes at the metabolite level and the mucocutaneous adverse effects associated with isotretinoin in the treatment of dermatological diseases.

Maintenance of appropriate ceramide levels and composition in the stratum corneum of the epidermis is essential for skin barrier function. Although ceramide homeostasis is regulated by both synthesis and degradation, the extent of ceramide degradation in the epidermis, as well as the ceramidase responsible for this degradation, has thus far remained unclear. Here, we found that the acid ceramidase ASAH1 is strongly expressed in differentiated human keratinocytes. To investigate its role, we generated ASAH1 KO cells using immortalized human keratinocytes and analyzed their ceramide levels. Under differentiation conditions, ASAH1 KO keratinocytes exhibited a marked accumulation of ceramide classes composed of sphingosine (S) or dihydrosphingosine (dS) and nonhydroxy fatty acid (N) (ceramides NS and NdS). In contrast, ceramides with (an) additional hydroxyl group(s)-such as those containing phytosphingosine (P) or 6-hydroxysphingosine (H) and N or α-hydroxy fatty acid (A) (ceramides NP, NH, AP, and AH)-showed a moderate or no increase. Similar results were obtained upon treatment with SABRAC, a specific ASAH1 inhibitor. In vitro enzyme assays revealed that ASAH1 exhibited strong activity toward NS and NdS, weak activity toward NP and NH, and no activity toward AP. These results indicate that ASAH1-mediated ceramide class-dependent degradation occurs in differentiated human keratinocytes. This degradation likely plays an important role in maintaining appropriate ceramide levels and class composition in the stratum corneum, thereby contributing to the integrity of the skin barrier.

Probiotics have emerged as a promising and safe alternative therapy for atopic dermatitis (AD) by regulating the gut microbiota-immune axis, correcting type 1/type 2 imbalance, and repairing the skin barrier. A mouse model of AD was established using diphenylnitromethane (DNFB). Low, medium, and high doses of human milk-derived Lacticaseibacillus rhamnosus HM126 were administered to investigate its effects on the model. We observed the scratching frequency and skin lesion scores after 28 days of continuous oral administration. Serum biochemical indicators and inflammatory cytokines were measured using ELISA, whereas the gut microbiota in feces was analyzed using 16S rDNA sequencing. Non-targeted metabolomics was used to assess the changes in fecal metabolites. Compared to the DNFB group, high-dose L. rhamnosus HM126 significantly reduced scratching frequency in AD mice. The low-dose group showed significantly reduced IgE levels. Additionally, the IFN-γ/IL-4 ratio significantly increased, indicating that L. rhamnosus HM126 modulates type 1/type 2 immune factors toward equilibrium. 16S rDNA analysis revealed that L. rhamnosus HM126 significantly reduced the ACE index and Chao 1 index of the gut microbiota in mice with AD, thereby reshaping the composition of the gut microbiome. Metabolomics analysis suggested that L. rhamnosus HM126 may improve AD by influencing the levels of asiatic acid, phytosphingosine, Ser-Glu, prostaglandin F2 alpha ethylamide (PGF(2α)EA), argininosuccinic acid, L-rhamnose, and gamma-L-glutamyl-L-glutamic acid. This study demonstrated that L. rhamnosus HM126 maintains the type 1/type 2 balance and effectively modifies the gut microbiota structure and metabolic changes to improve AD. Our findings provide a scientific basis for the development of probiotic therapeutics to prevent and treat this condition.

Hyaluronic acid (HA) has been extensively utilized in cosmetic products and topical formulations due to its remarkable moisturizing properties and the potential to enhance transdermal drug delivery. In this study, phytosphingosine (PS) was utilized as a positive charge inducer in the preparation of positively charged nanoemulsions (PS-HPR-NE). Subsequently, hydroxypinacolone retinoate (HPR) was modified onto the surface of 8 kDa HA nanoemulsions via electrostatic adsorption technology, yielding the HA-HPR-NE composite system. The resulting nanoemulsion exhibited a particle size of 116.00 ± 2.34 nm, a polydispersity index (PDI) of 0.100 ± 0.011, and a surface potential of -17.42 ± 0.19 mV. The findings of the storage stability and stability analyzer assessments demonstrated excellent stability. Subsequent analysis of cell uptake experiments revealed significantly higher fluorescent labeling both inside and outside cells in the HA-HPR-NE group compared to that in the PS-HPR-NE group. In vivo skin penetration fluorescence results indicated that HA-HPR-NE exhibited a higher fluorescence intensity in deep skin layers than PS-HPR-NE and free HPR. In vitro diffusion cell tests demonstrated that PS-HPR-NE exhibited higher skin retention rates and cumulative penetration rates than the control group, thus confirming its highly efficient drug release effect. In addition, the red blood cell hemolysis assay and human patch test demonstrated that this nanoemulsion significantly reduced the HPR irritation. In comparison with conventional cationic nanoemulsions, HA-targeted nanoemulsions demonstrate enhanced potential and a wider range of potential applications in the domains of transdermal drug-delivery and targeted drug-delivery systems.

Oat lipids are rich in ceramides. In this investigation, we analysed the delivery of a specific Oat Lipid Extract derived from Avena sativa, comprising 'skin identical' ratios of fatty acids, ceramides and cholesterol/sterol. This investigation is the first reported investigation of oat lipids utilizing Raman spectroscopy for the identification of oat ceramides from A. sativa supported by Lipbarvis®, transmission electron microscopy and immunofluorescence analysis. Oil lipid class compositions were determined by single-dimension double-development high-performance thin-layer chromatography. Ceramide class profiling was carried out using liquid chromatography with tandem mass spectrometry. Raman spectra of lipids were obtained by confocal Raman spectroscopy and immunostaining on human skin explants following treatment for 5 days. Length of lipid lamellae was determined using Lipbarvis® transmission electron microscopy followed by immuno-histochemical analysis of hyaluronic acid and ceramides, on human skin following treatment for 56 days. Measurement of skin roughness (PRIMOS) and hydration (corneometer) were performed following treatment for 56 days. Gas-liquid chromatography and high-performance thin-layer chromatography profiling of Oat Lipid Extract, revealed that of the ceramide classes identified, skin identical sphingosine and phytosphingosine bases were present. Oat Lipid Extract has a typical total polar lipid content of 40 g kg -1 of which 4 g kg -1 ceramides, comprised ceramides/hydroxyceramides, gycosyl inositol phosphoryl ceramides and glucosylceramides. Raman profiling of Oat Lipid Extract was well correlated with stratum corneum and viable epidermis lipid profiles. Oat Lipid Extract induced a significant increase in neutral and polar lipid content. Lipbarvis® transmission electron microscopy and immunostaining showed significant increase in the length of the intercellular lipid lamellae and in the amount of hyaluronic acid and ceramides. Oat Lipid Extract significantly reduced skin roughness and increased skin hydration after 56 days of treatment. Oat ceramides in the form of Oat Lipid Extract can be effectively delivered into the stratum corneum. The preliminary Raman and electron microscopy Lipbarvis® studies have given good insight into the possibility of Oat Lipid Extract mimicking the structure and function of the skin's barrier. The visible effect on the skin was observed with a decrease in skin roughness. les lipides d'avoine sont riches en céramides. Dans cette investigation, nous avons analysé la délivrance d'un extrait de lipides d'avoine spécifique dérivé de Avena sativa, comprenant des rapports identiques à la peau d'acides gras, de céramides et de cholestérol/stérol. Cette investigation est la première investigation rapportée sur les lipides d'avoine utilisant la spectroscopie de Raman pour l'identification des céramides d'avoine issus de Avena sativa soutenue par Lipbarvis®, la microscopie électronique à transmission et l'analyse par immunofluorescence. MÉTHODES: les compositions de la classe lipidique des huiles ont été déterminées par chromatographie sur couche mince haute performance à double développement et dimension unique. Le profilage de la classe des céramides a été réalisé par chromatographie liquide avec spectrométrie de masse en tandem. Les spectres de Raman des lipides ont été obtenus par spectroscopie de Raman confocale et immunomarquage sur des explants cutanés humains après 5 jours de traitement. La durée des lamelles lipidiques a été déterminée par la microscopie électronique à transmission Lipbarvis®, suivie d'une analyse immunohistochimique de l'acide hyaluronique et des céramides, sur la peau

The main lipid compounds of the outermost layer of human skin are ceramides (CERs), free fatty acids, and cholesterol. Although numerous studies performed in the past could demonstrate the importance of these lipids for an intact skin barrier function, knowledge about the impact of each single component on the lamellar lipid films is still lacking. Especially, the CERs are a very heterogeneous group with high relevance for a proper barrier. It was found that the reason for the high stability of the lamellae is related to the lipid structure and function, with the type and extent of interactions between the head groups of the individual CER subspecies being particularly important. Elucidating these at the molecular level could help us to understand CER phase behavior in general. Using grazing incidence X-ray diffraction and measurements of Langmuir isotherms, the current work investigated the lateral packing of the monolayers of different subclasses of C18:0 CERs at air-water interfaces, including phytosphingosine, sphingosine, and dihydrosphingosine CERs, all with either α-hydroxy and nonhydroxy N -acylated fatty acyl. We were able to observe clear effects of the minimal differences in the polar headgroup structures of the sphingoid bases, with respect to the number and position of hydroxyl groups and double bonds, on the CER arrangement regarding the compressibility and structure of the films they formed, revealing that the hydroxyl group at the C4 of the phytosphingosine CERs leads not only to the formation of a hydrogen bond network but also to a stable suprastructure, which might be of high benefit for the barrier properties of intact skin.

People with atopic dermatitis (AD) suffer from dry, itchy skin with reduced skin barrier function that leaves it prone to irritant and allergen penetration. Alterations in the composition and structure of the stratum corneum (SC) lipid lamellae underpin this increase in permeability. A wide range of emollients is used to ameliorate the skin of patients with AD, but the majority have unclear effects on the lipid lamellae and barrier function. To compare the effects of a multivesicular emulsion containing physiological lipids and glycerine (MVE + GL) with a commonly prescribed oil-in-water emulsion containing glycerine without physiological lipids (O/W + G). A double-blind intraparticipant-controlled study was undertaken in adults with a history of eczema. Participants applied MVE + GL to one forearm and lower leg and O/W + G to contralateral sites twice daily for 28 days. Skin properties were assessed before and after treatment. A detailed lipidomic profile was generated from SC samples, alongside in vivo attenuated total reflectance Fourier transform infrared spectroscopic analysis of its molecular composition. Fifty-eight people were included in the study [mean (SD) age 46 (21) years]. At sites treated with MVE + GL skin barrier integrity improved significantly [mean (SD) transepidermal water loss after 20 skin tape strips (TEWL20) 38.02 (18.64) g m-2 h-1 pretreatment vs. 29.79 (13.47) g m-2 h-1 post-treatment; P < 0.001], whereas O/W + G had no effect [35.6 (18.39) g m-2 h-1 vs. 37.4 (16.69) g m-2 h-1]. Concordantly, skin sensitivity to sodium lauryl sulfate (SLS) was significantly reduced by MVE + GL treatment [mean (SD) post-SLS TEWL 35.58 (15.43) g m-2 h-1 pretreatment vs. 29.54 (11.64) g m-2 h-1 post-treatment (P < 0.001); erythema was also reduced]. Skin moisture increased more rapidly at sites treated with MVE + GL vs. O/W + G, leading to a more rapid reduction in visual skin dryness. Over 1600 lipid species were detected in the SC. Ceramide species NP (non-hydroxy-phytosphingosine) and AP (α-hydroxy-phytosphingosine) with 18-carbon sphingoid bases, both ingredients of the MVE + GL, increased significantly by 24% and 19%, respectively, following MVE + GL treatment. In contrast, changes of 9% for NP(18) and 6% for AP(18) were not statistically significant at sites treated with O/W + G. Increased abundance of NP(18) species relative to NdS (non-hydroxy-dihydrosphingosine) species was related to improvements in skin barrier integrity. While the glycerine-containing emollient reduced skin dryness, it had no impact on barrier function. In contrast, MVE + GL improved the physical integrity of the barrier and reduced the sensitivity of the skin. Eczema is the most common chronic skin condition. It affects 1% to 10% of adults in Europe. The upper layers of our skin form a barrier that keeps water in our bodies and stops irritants from getting in. This skin barrier is made of cells called ‘corneocytes’. These are surrounded by a tough protein envelope and embedded in a network of ‘fatty’ molecules (called ‘lipids’). The composition of these fatty molecules is altered in the skin of people with eczema. The skin does not function effectively as a barrier as more water is lost, and irritants can more easily penetrate the deeper skin layers. Moisturizing creams are an effective treatment for eczema, but it is unclear which are most appropriate to use. This study was carried out in the UK. We aimed to find out if a cream containing lipids found in skin could improve the skin’s ability to act as a barrier. We compared this cream to one without these lipids. We asked 58 people with eczema to apply these creams separately on their forearms for a month and measured how the skin responded. We found that skin treated with the cream containing skin-identical lipids lost less water. It was also more resistant to physical damage and was less sensitive to irritation than befo

Dandruff is a common chronic scalp condition that affects approximately half the population irrespective of their origin. Dandruff scalps are characterized by flaking skin, pruritus, and minimal visible scalp inflammation. At the biological level, dandruff scalp presents a disruption of the barrier function supported by lower levels of ceramides in the stratum corneum and typically accompanied by altered microbiome diversity, including a higher abundance of Malassezia yeasts and exacerbated sebum peroxidation. This study evaluated the relationship between skin barrier integrity in association with epidermal ceramide profile, microbiome imbalance, and inflammatory markers in pathophysiology of dandruff in an ethnically diverse panel. Our results confirm a significant increase in TEWL and decrease in hydration along with an increase in erythema, dryness, flakiness, and itchiness in patients with dandruff vs normal scalps; and an elevation of IL1RA:IL1α ratio dependent on the severity of the dandruff, supporting the inflammatory association with dandruff. For the first time, a study shows that dandruff scalps have a significantly higher amount of short-chain ceramides and a significantly lower proportion of long-chain ceramides consistent with lower conformational ordering and, thus explaining a higher permeability of the skin contributing to barrier dysfunction. In addition, reduced phytosphingosine and dihydrosphingosine based ceramides (NP, AP, NDS) were also observed, supporting a weakened scalp barrier. In addition to an expected increase in Malassezia, especially Malassezia restricta, in dandruff scalp, an increase in Staphylococcus aureus and decrease in Malassezia globosa was also observed as compared to healthy scalp in the population analyzed. J Drugs Dermatol. 2025;24:3(Suppl 1):s3-14.