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.

Nontargeted metabolomics to characterize the effects of isotretinoin on skin metabolism in rabbit with acne

Background: Acne vulgaris is a chronic inflammatory disease of the pilosebaceous unit. This study aimed to explore the pathogenesis of acne and the therapeutic mechanism of isotretinoin from the metabolic perspective in coal tar-induced acne in rabbits.

Methods: Ultra-high performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC-qTOF-MS) based metabolomics was used to identify skin metabolites in groups C (blank control), M (model group) and T (isotretinoin group). Multivariate statistical analysis was used to process the metabolomics data.

Results: 98 differential metabolites in group C and group M were identified. The highest proportion of differential metabolites were organic acids and derivatives, lipid metabolites, organic heterocyclic compounds, and nucleoside metabolites. The most significant metabolic pathways included protein digestion and absorption, central carbon metabolism in cancer, ABC transporters, aminoacyl-tRNA biosynthesis, biosynthesis of amino acids, and sphingolipid signaling pathway. Isotretinoin treatment normalized eight of these metabolites.

Conclusions: Our study will help to further elucidate the pathogenesis of acne, the mechanism of isotretinoin at the metabolite level, and identify new therapeutic targets for treating acne.

Untargeted metabolomics analysis of the plasma metabolic signature of moderate-to-severe acne

BACKGROUND

Acne vulgaris is a chronic inflammatory disease of pilosebaceous units and sebaceous glands. This study aimed to find out metabolites and metabolite pathways abnormal in moderate-to-severe acne vulgaris patients.

METHODS

The plasma metabolites LC-MS/MS analysis was conducted on 30 moderate-to-severe acne patients and 32 healthy controls. Multivariate data analyses were applied to identify the distinguishing metabolites.

RESULTS

Totally, 63 significant differential metabolites and 40 metabolic pathways were significantly changed. The top 3 metabolites on the basis of their VIP scores obtained from the PLS-DA were 2-Oxoadipic acid, Myo-inositol and Citrate. In addition, four sphingolipid metabolites include sphinganine, sphingosine, O-Phosphoethanolamine, and sphingomyelin (d18:1/18:0) were identified. The most closely related metabolic pathways included ATP-binding cassette (ABC) transporters and sphingolipid signaling pathway in moderate-to-severe acne patients.

CONCLUSIONS

The observed difference in metabolic profiles between acne patients and healthy controls provides a new insight into the link between plasma metabolic changes and acne vulgaris.

The role of sphingolipids in endoplasmic reticulum stress

The endoplasmic reticulum (ER) is an important intracellular compartment in eukaryotic cells and has diverse functions, including protein synthesis, protein folding, lipid metabolism and calcium homeostasis. ER functions are disrupted by various intracellular and extracellular stimuli that cause ER stress, including the inhibition of glycosylation, disulphide bond reduction, ER calcium store depletion, impaired protein transport to the Golgi, excessive ER protein synthesis, impairment of ER-associated protein degradation and mutated ER protein expression. Distinct ER stress signalling pathways, which are known as the unfolded protein response, are deployed to maintain ER homeostasis, and a failure to reverse ER stress triggers cell death. Sphingolipids are lipids that are structurally characterized by long-chain bases, including sphingosine or dihydrosphingosine (also known as sphinganine). Sphingolipids are bioactive molecules long known to regulate various cellular processes, including cell proliferation, migration, apoptosis and cell-cell interaction. Recent studies have uncovered that specific sphingolipids are involved in ER stress. This review summarizes the roles of sphingolipids in ER stress and human diseases in the context of pathogenic events.

Molecular mechanism for sphingosine-induced Pseudomonas ceramidase expression through the transcriptional regulator SphR

Pseudomonas aeruginosa, an opportunistic, but serious multidrug-resistant pathogen, secretes a ceramidase capable of cleaving the N-acyl linkage of ceramide to generate fatty acids and sphingosine. We previously reported that the secretion of P. aeruginosa ceramidase was induced by host-derived sphingolipids, through which phospholipase C-induced hemolysis was significantly enhanced. We herein investigated the gene(s) regulating sphingolipid-induced ceramidase expression and identified SphR, which encodes a putative AraC family transcriptional regulator. Disruption of the sphR gene in P. aeruginosa markedly decreased the sphingomyelin-induced secretion of ceramidase, reduced hemolytic activity, and resulted in the loss of sphingomyelin-induced ceramidase expression. A microarray analysis confirmed that sphingomyelin significantly induced ceramidase expression in P. aeruginosa. Furthermore, an electrophoretic mobility shift assay revealed that SphR specifically bound free sphingoid bases such as sphingosine, dihydrosphingosine, and phytosphingosine, but not sphingomyelin or ceramide. A β-galactosidase-assisted promoter assay showed that sphingosine activated ceramidase expression through SphR at a concentration of 100 nM. Collectively, these results demonstrated that sphingosine induces the secretion of ceramidase by promoting the mRNA expression of ceramidase through SphR, thereby enhancing hemolytic phospholipase C-induced cytotoxicity. These results facilitate understanding of the physiological role of bacterial ceramidase in host cells.

Effect of the multifunctional cosmetic ingredient sphinganine on hair loss in males and females with diffuse hair reduction

Sphingolipids are well known to promote keratinocyte differentiation and to induce ceramide production. In addition, they show anti-inflammatory and antimicrobial activities. Thus, the aim of this study is to investigate the potential effect of sphinganine on prolonging the hair anagen rate and improving the overall hair quality and scalp health. The inhibitory potential of sphinganine toward 5-α-reductase was studied using an in vitro assay. The stimulation of the antimicrobial peptide HBD2 by sphinganine was measured by real-time polymerase chain reaction and immunostaining. Sphinganine bioavailability was studied ex vivo using a pig skin model. A placebo-controlled, double-blind study was designed to evaluate the efficacy of sphinganine on hair loss and hair/scalp quality in vivo. In vitro results showed that sphinganine is a potent inhibitor of 5-α-reductase type I that prevents the conversion of testosterone to dihydrotestosterone, a key factor of androgenetic male baldness. In vivo results demonstrated efficacy in reducing non-illness-related hair loss among males. In terms of expert rating, all hair quality and scalp parameters improved after application of sphinganine. Improved scalp health might be linked to the observed increase of the antimicrobial peptide HBD2. Thus, sphinganine is well suited as a topical alternative for the improvement of scalp health and hair quality and anti-hair loss application.

Topical ceramides neither enhance UVB-induced apoptosis in normal human keratinocytes nor affect viability in UVB-irradiated reconstructed human epidermis

Ceramides are the major lipid of lamellar sheets present in intercellular spaces of the stratum corneum contributing to epidermal barrier properties. Therefore, ceramides and their analogues have been studied for barrier enhancing and water-holding properties for decades. In vitro studies have indicated cytotoxic potential for cell-permeable ceramides thereby raising the question whether topical ceramide application might contribute to UVB-induced apoptosis. Phytosphingosine, N-hexanoyl-phytosphingosine and N-stearoylphytosphingosine (ceramide III) in concentrations ≤5 μm have been used for co-stimulation with low (160 J/m(2) ) or high (600 J/m(2) ) UVB doses in subconfluent basal and confluent differentiating keratinocytes. Significantly, increased caspase-3 activity was observed in basal keratinocytes irradiated with 600 J/m(2) UVB and in differentiating keratinocytes with both UVB doses. Co-stimulation with the named ceramides did not further increase (i) caspase-3 activity and (ii) nucleosomal fragmentation in differentiating keratinocytes. Moreover, co-stimulation with 1-mm ceramides did not further affect viability/lactate dehydrogenase release in UVB-irradiated reconstructed human epidermis corroborating the safety of these ceramides.

Dissecting the calcium-induced differentiation of human primary keratinocytes stem cells by integrative and structural network analyses

The molecular details underlying the time-dependent assembly of protein complexes in cellular networks, such as those that occur during differentiation, are largely unexplored. Focusing on the calcium-induced differentiation of primary human keratinocytes as a model system for a major cellular reorganization process, we look at the expression of genes whose products are involved in manually-annotated protein complexes. Clustering analyses revealed only moderate co-expression of functionally related proteins during differentiation. However, when we looked at protein complexes, we found that the majority (55%) are composed of non-dynamic and dynamic gene products ('di-chromatic'), 19% are non-dynamic, and 26% only dynamic. Considering three-dimensional protein structures to predict steric interactions, we found that proteins encoded by dynamic genes frequently interact with a common non-dynamic protein in a mutually exclusive fashion. This suggests that during differentiation, complex assemblies may also change through variation in the abundance of proteins that compete for binding to common proteins as found in some cases for paralogous proteins. Considering the example of the TNF-α/NFκB signaling complex, we suggest that the same core complex can guide signals into diverse context-specific outputs by addition of time specific expressed subunits, while keeping other cellular functions constant. Thus, our analysis provides evidence that complex assembly with stable core components and competition could contribute to cell differentiation.

Distribution of bioactive lipid mediators in human skin

The skin produces bioactive lipids that participate in physiological and pathological states, including homeostasis, induction, propagation, and resolution of inflammation. However, comprehension of the cutaneous lipid complement, and contribution to differing roles of the epidermal and dermal compartments, remains incomplete. We assessed the profiles of eicosanoids, endocannabinoids, N-acyl ethanolamides, and sphingolipids, in human dermis, epidermis, and suction blister fluid. We identified 18 prostanoids, 12 hydroxy-fatty acids, 9 endocannabinoids and N-acyl ethanolamides, and 21 non-hydroxylated ceramides and sphingoid bases, several demonstrating significantly different expression in the tissues assayed. The array of dermal and epidermal fatty acids was reflected in the lipid mediators produced, whereas similarities between lipid profiles in blister fluid and epidermis indicated a primarily epidermal origin of suction blister fluid. Supplementation with omega-3 fatty acids ex vivo showed that their action is mediated through perturbation of existing species and formation of other anti-inflammatory lipids. These findings demonstrate the diversity of lipid mediators involved in maintaining tissue homeostasis in resting skin and hint at their contribution to signaling, cross-support, and functions of different skin compartments. Profiling lipid mediators in biopsies and suction blister fluid can support studies investigating cutaneous inflammatory responses, dietary manipulation, and skin diseases lacking biomarkers and therapeutic targets.

Effects of sphingoid bases on the sphingolipidome in early keratinocyte differentiation

Keratinocyte sphingolipids are structural elements of epidermal permeability barrier and potential regulators of epidermal functions. We tested the influence of sphingoid bases sphinganine, sphingosine and phytosphingosine on in vitro keratinocyte differentiation. Lipidomic and transcriptomic analysis after treatment emphasizes sphinganine and phytosphingosine as potent modulators of keratinocyte differentiation and lipid metabolism. Sphinganine treatment regulated differentiation and sphingolipid metabolism-related genes, and also increased all major ceramide species. Sphingosine treatment increased ceramide and phytoceramide pools without changes in dihydroceramides. Phytosphingosine treatment markedly increased phytoceramide pools without raising ceramide or dihydroceramide levels. Sphinganine treatment increased specifically very long chain ceramides essential for intact barrier function. In summary, sphingoid bases, especially sphinganine, promote differentiation and ceramide production in keratinocytes. Free sphinganine may serve as a dermatological and cosmetic agent by enhancing formation and maintenance of an intact epidermal lipid barrier, with beneficial effects for skin and hair care applications.

Immobilised lipases in the cosmetics industry

Commercial products for personal care, generally perceived as cosmetics, have an important impact on everyday life worldwide. Accordingly, the market for both consumer products and specialty chemicals comprising their ingredients is considerable. Lipases have started to play a minor role as active ingredients in so-called 'functional cosmetics' as well as a major role as catalysts for the industrial production of various specialty esters, aroma compounds and active agents. Interestingly, both applications almost always require preparation by appropriate immobilisation techniques. In addition, for catalytic use special reactor concepts often have to be employed due to the mostly limited stability of these preparations. Nevertheless, these processes show distinct advantages based on process simplification, product quality and environmental footprint and are therefore apt to more and more replace traditional chemical processes. Here, for the first time a review on the various aspects of using immobilised lipases in the cosmetics industry is given.

Phytosphingosine derivatives ameliorate skin inflammation by inhibiting NF-κB and JAK/STAT signaling in keratinocytes and mice

Phytosphingosine is abundant in plants and fungi and is found in mammalian epidermis, including the stratum corneum. Phytosphingosine and its derivatives N-acetyl phytosphingosine and tetraacetyl phytosphingosine are part of the natural defense system of the body. However, these molecules exhibit strong toxicities at high concentrations. We synthesized phytosphingosine derivatives, mYG-II-6 ((Z)-4-oxo-4-(((2S,3S,4R)-1,3,4-trihydroxyoctadecan-2-yl)amino)but-2-enoic acid) and fYG-II-6 ((E)-4-oxo-4-(((2S,3S,4R)-1,3,4-trihydroxyoctadecan-2-yl)amino)but-2-enoic acid), to increase efficacy and decrease toxicity, and the biological activities of the derivatives in the inflammatory response were examined. Both YG-II-6 compounds effectively suppressed 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammatory skin damage and inflammatory response in a mouse model. In addition, topical application of fYG-II-6 suppressed ear swelling and psoriasiform dermatitis in the ears of IL-23-injected mice. Anti-inflammatory and antipsoriatic activities of the phytosphingosine derivatives inhibited NF-κB, JAK/signal transducer and activator of transcription (JAK/STAT), and mitogen-activated protein kinase (MAPK) signaling. Finally, the YG-II-6 compounds induced programmed cell death in keratinocytes and mouse skin and were less toxic than phytosphingosine. Our study demonstrated that the phytosphingosine-derived YG-II-6 compounds have much stronger biological potencies than the lead compounds. The YG-II-6 compounds ameliorated inflammatory skin damage. Thus, YG-II-6 compounds are potential topical agents for treating chronic inflammatory skin diseases, such as psoriasis.

Draft genome sequence of Wickerhamomyces ciferrii NRRL Y-1031 F-60-10

Wickerhamomyces ciferrii is a microorganism characterized by the production and secretion of large amounts of acetylated sphingoid bases, in particular tetraacetyl phytosphingosine. Here, we present the 15.90-Mbp draft genome sequence of W. ciferrii NRRL Y-1031 F-60-10 generated by pyrosequencing and de novo assembly. The draft genome sequence comprising 364 contigs in 150 scaffolds was annotated and covered 6,702 protein-coding sequences. This information will contribute to the metabolic engineering of this yeast to improve the yield and spectrum of acetylated sphingoid bases in biotechnological production.

Genome-wide transcriptional profiles during temperature and oxidative stress reveal coordinated expression patterns and overlapping regulons in rice

Genome wide transcriptional changes by cold stress, heat stress and oxidative stress in rice seedlings were analyzed. Heat stress resulted in predominant changes in transcripts of heat shock protein and heat shock transcription factor genes, as well as genes associated with synthesis of scavengers of reactive oxygen species and genes that control the level of sugars, metabolites and auxins. Cold stress treatment caused differential expression of transcripts of various transcription factors including desiccation response element binding proteins and different kinases. Transcripts of genes that are part of calcium signaling, reactive oxygen scavenging and diverse metabolic reactions were differentially expressed during cold stress. Oxidative stress induced by hydrogen peroxide treatment, resulted in significant up-regulation in transcript levels of genes related to redox homeostasis and down-regulation of transporter proteins. ROS homeostasis appeared to play central role in response to temperature extremes. The key transcription factors that may underlie the concerted transcriptional changes of specific components in various signal transduction networks involved are highlighted. Co-ordinated expression pattern and promoter architectures based analysis (promoter models and overrepresented transcription factor binding sites) suggested potential regulons involved in stress responses. A considerable overlap was noted at the level of transcription as well as in regulatory modules of differentially expressed genes.

Metabolic engineering of the non-conventional yeast Pichia ciferrii for production of rare sphingoid bases

The study describes the identification of sphingolipid biosynthesis genes in the non-conventional yeast Pichia ciferrii, the development of tools for its genetic modification as well as their application for metabolic engineering of P. ciferrii with the goal to generate strains capable of producing the rare sphingoid bases sphinganine and sphingosine. Several canonical genes encoding ceramide synthase (encoded by PcLAG1 and PcLAF1), alkaline ceramidase (PcYXC1) and sphingolipid C-4-hydroxylase(PcSYR2), as well as structural genes for dihydroceramide Δ(4)-desaturase (PcDES1) and sphingolipid Δ(8)-desaturase (PcSLD1) were identified, indicating that P. ciferrii would be capable of synthesizing desaturated sphingoid bases, a property not ubiquitously found in yeasts. In order to convert the phytosphingosine-producing P. ciferrii wildtype into a strain capable of producing predominantly sphinganine, Syringomycin E-resistant mutants were isolated. A stable mutant almost exclusively producing high levels of acetylated sphinganine was obtained and used as the base strain for further metabolic engineering. A metabolic pathway required for the three-step conversion of sphinganine to sphingosine was implemented in the sphinganine producing P. ciferrii strain and subsequently enhanced by screening for the appropriate heterologous enzymes, improvement of gene expression and codon optimization. These combined efforts led to a strain capable of producing 240mgL(-1) triacetyl sphingosine in shake flask, with tri- and diacetyl sphinganine being the main by-products. Lab-scale fermentation of this strain resulted in production of up to 890mgkg(-1) triacetyl sphingosine. A third by-product was unequivocally identified as triacetyl sphingadienine. It could be shown that inactivation of the SLD1 gene in P. ciferrii efficiently suppresses triacetyl sphingadienine formation. Further improvement of the described P. ciferrii strains will enable a biotechnological route to produce sphinganine and sphingosine for cosmetic and pharmaceutical applications.

Optimization of filaggrin expression and processing in cultured rat keratinocytes

BACKGROUND

In normal mammalian epidermis, cell division occurs primarily in the basal layer where cells are attached to the basement membrane. Upon release from the basement membrane, these basal cells stop dividing and begin to differentiate and stratify producing cornified cells expressing differentiation markers, including the keratin bundling protein filaggrin, and cornified envelope proteins. Little is understood about the regulatory mechanisms of these processes. A rat epidermal keratinocyte cell line synthesizing and processing profilaggrin at confluence in a synchronous manner for 4-5 days provides a useful culture model for epidermal differentiation. Profilaggrin expression in this cell line however decreases with passaging, and its processing involves extensive nonspecific proteolysis.

OBJECTIVE

Our objective was to identify culture conditions that effect the decrease in profilaggrin expression with passaging and nonspecific proteolysis of profilaggrin in order to study epidermal differentiation more closely.

METHOD

The large amount of nonspecific proteolysis suggested autophagocytosis. To test this, cells were cultured in the presence of 3-methyladenine (3-MA). Two known gradients in epidermis are decreasing serum components and increasing calcium concentrations in the upper cell layers. To determine whether these gradients effected processing, cells were cultured in serum/DMEM or in serum-free KGM and under varying external calcium concentrations. Cells were also cultured in presence of aminoguanidine in an attempt to maintain profilaggrin expression with passaging.

RESULTS

Profilaggrin expression was enhanced in the presence of 3-MA, with optimum around 6mM. In the absence of aminoguanidine, profilaggrin expression decreased as a function of increasing passage number; in its presence, profilaggrin expression remained high in some, but not in all of the independently maintained cell lines. Thus, culturing in aminoguanidine was necessary, but not sufficient, for sustained ability to express profilaggrin at confluence. Production of filaggrin from profilaggrin was maximized in a serum-free medium with [Ca(2+)] at 5mM. Filaggrin associates with phospholipid vesicles in vitro forming aggregates similar to those seen in vivo, suggesting that filaggrin release induces vesicular aggregation and autophagocytosis.

CONCLUSION

We have used a keratinocyte cell line that synthesizes and processes profilaggrin after confluence as a culture model to study epidermal differentiation. In this system profilaggrin processing must be preceded by inhibition of autophagosome formation and/or modulation of vesicular trafficking, and these processes are regulated by epidermal calcium and serum factor gradients.

Large scale study of epidermal recovery after stratum corneum removal: dynamics of genomic response

The stratum corneum (SC) is a superficial skin compartment that protects the body from the outside environment. Any disturbance of this function induces cascading steps of molecular and cellular repair in the whole epidermis. The aim of this study was to investigate epidermal gene expression following SC removal by tape stripping. Twenty-nine healthy male volunteers were included (27 +/- 4 years old). Tape stripping was processed on one inner forearm, the other unstripped forearm served as a control. Epidermis samples were collected at 2, 6, 19, 30 and 72 h after tape stripping. Trans-epidermal water loss measurements were performed at each step to monitor barrier restoration. Total RNA was extracted from collected epidermis samples and analysed by using DermArray cDNA microarrays. Among 4000 genes under investigation, we found that the expression of 370 genes varied significantly at least once during the time following stripping. Using an original clustering method, the modulated genes were gathered into eight groups. A functional characterization of the clusters enabled us to get a dynamic and global view of the main molecular processes taking place during epidermal recovery.