The ceramide [NP]/[NS] ratio in the stratum corneum is a potential marker for skin properties and epidermal differentiation.

BACKGROUND: Specific species of ceramides (Cer), major constituents of lipids in the stratum corneum (SC), are decreased and are correlated with SC barrier and water-holding functions in the skin of patients with atopic dermatitis (AD) or psoriasis (Pso). However, possible correlations between Cer subclass ratios and skin properties in barrier-disrupted skin and in healthy skin remain unclear. The objective of this study was to identify a new marker to evaluate skin properties and epidermal differentiation in SC not only in barrier-disrupted skin but also in healthy skin. METHODS: The Cer subclass ratios in the SC of healthy control subjects and in patients with AD or Pso were evaluated. Correlations with candidate markers and facial skin features of healthy Japanese females (20-74 years old, n = 210) were investigated. Variations of markers during epidermal differentiation were studied in human epidermis and in cultured keratinocytes. RESULTS: The ratios of Cer [NP]/[NS], Cer [NH]/[NS], Cer [NP]/[AS], Cer [NH]/[NS], Cer [NDS]/[AS], Cer [AH]/[AS] and Cer [EOP]/[AS] showed significant differences between non-lesional skin of AD patients and normal skin of healthy control subjects, as well as Pso patients and their healthy control subjects. The Cer [NP]/[NS] ratio was correlated with SC functional parameters (transepidermal water loss and capacitance) and with skin appearance (texture, scaling and color) even in the cheek skin of healthy female subjects. The Cer [NP]/[NS] ratio in the SC was approximately 18-times higher than in living keratinocytes, and it increased as they differentiated. CONCLUSIONS: The Cer [NP]/[NS] ratio in the SC is a potential marker for skin properties and epidermal differentiation in barrier-disrupted skin as well as in healthy skin.

Properties of Skin in Chinese Infants: Developmental Changes in Ceramides and in Protein Secondary Structure of the Stratum Corneum.

The properties of infant skin regarding its structure and stratum corneum (SC) properties during development compared to adult skin have been reported only for a few races and body sites. The aim of this study was to understand the developmental changes of skin properties in Chinese infants, focusing on SC ceramides and protein secondary structure, which are important for skin barrier function. Three body sites with distinct characteristics (cheeks, inner upper arms, and buttocks) were assessed. Sixty pairs of Chinese infants and their mothers were measured for SC hydration, transepidermal water loss, ceramide levels, sebum with an ester bond, and protein secondary structure of superficial SC. Skin hydration decreased with age at all body sites. TEWL was similar between the 2-12- and 13-24-month-old groups but was higher than the adult group at the buttocks and inner upper arms and was equal to the adult group at the cheeks. These differences coincided with differences in protein secondary structure. Ceramide and sebum levels were lower in the infant groups. We conclude that both the SC functions and the components of infant skin are still developing and are not fully adapted as in adult skin at each body site examined.

Essential role of the cytochrome P450 CYP4F22 in the production of acylceramide, the key lipid for skin permeability barrier formation.

A skin permeability barrier is essential for terrestrial animals, and its impairment causes several cutaneous disorders such as ichthyosis and atopic dermatitis. Although acylceramide is an important lipid for the skin permeability barrier, details of its production have yet to be determined, leaving the molecular mechanism of skin permeability barrier formation unclear. Here we identified the cytochrome P450 gene CYP4F22 (cytochrome P450, family 4, subfamily F, polypeptide 22) as the long-sought fatty acid ω-hydroxylase gene required for acylceramide production. CYP4F22 has been identified as one of the autosomal recessive congenital ichthyosis-causative genes. Ichthyosis-mutant proteins exhibited reduced enzyme activity, indicating correlation between activity and pathology. Furthermore, lipid analysis of a patient with ichthyosis showed a drastic decrease in acylceramide production. We determined that CYP4F22 was a type I membrane protein that locates in the endoplasmic reticulum (ER), suggesting that the ω-hydroxylation occurs on the cytoplasmic side of the ER. The preferred substrate of the CYP4F22 was fatty acids with a carbon chain length of 28 or more (≥C28). In conclusion, our findings demonstrate that CYP4F22 is an ultra-long-chain fatty acid ω-hydroxylase responsible for acylceramide production and provide important insights into the molecular mechanisms of skin permeability barrier formation. Furthermore, based on the results obtained here, we proposed a detailed reaction series for acylceramide production.

Dry skin in the winter is related to the ceramide profile in the stratum corneum and can be improved by treatment with a Eucalyptus extract.

BACKGROUND: Dry skin in the winter has been reported to involve scaling, defects in water holding and barrier functions, and decreased ceramide (CER) levels in the stratum corneum (SC). We previously reported that a Eucalyptus extract promotes CER synthesis in cultured keratinocytes and accelerates the recovery of hydration in a barrier-disrupted model of human skin. AIMS: One of the objectives was to examine the CER profile and its contribution to the relief of dry skin. The other objective was to assess the efficacy of a Eucalyptus extract to treat dry skin. PATIENTS/METHODS: Twenty subjects with dry skin on their legs were assessed and their CER profiles were analyzed using tape-stripping. A moisturizer with a Eucalyptus extract was assessed for its effects on dry skin using a leg regression methodology comprising 28 days of treatment and 14 days of regression. RESULTS: Indicators of dry skin conditions (conductance, dryness, roughness, and scaliness) strongly correlated with the level of CER, CER [NP], and CER[NH]. Treatment with the Eucalyptus extract significantly improved conductance (3 days after regression) and transepidermal water loss (14 days after regression) compared with the placebo. After 28 days of treatment with the Eucalyptus extract, the level of CER in the SC did not increase, but CER [NP] did increase. CONCLUSIONS: These results suggest that not only the level of CER, but also specific CER species strongly contribute to dry skin relief and products that increase those are useful to improve dry skin conditions.

Self-improvement of keratinocyte differentiation defects during skin maturation in ABCA12-deficient harlequin ichthyosis model mice.

Harlequin ichthyosis (HI) is caused by loss-of-function mutations in the keratinocyte lipid transporter ABCA12. The patients often die in the first 1 or 2 weeks of life, although HI survivors' phenotypes improve within several weeks after birth. In order to clarify the mechanisms of phenotypic recovery, we studied grafted skin and keratinocytes from Abca12-disrupted (Abca12(-/-)) mice showing abnormal lipid transport. Abca12(-/-) neonatal epidermis showed significantly reduced total ceramide amounts and aberrant ceramide composition. Immunofluorescence and immunoblotting of Abca12(-/-) neonatal epidermis revealed defective profilaggrin/filaggrin conversion and reduced protein expression of the differentiation-specific molecules, loricrin, kallikrein 5, and transglutaminase 1, although their mRNA expression was up-regulated. In contrast, Abca12(-/-) skin grafts kept in a dry environment exhibited dramatic improvements in all these abnormalities. Increased transepidermal water loss, a parameter representing barrier defect, was remarkably decreased in grafted Abca12(-/-) skin. Ten-passage sub-cultured Abca12(-/-) keratinocytes showed restoration of intact ceramide distribution, differentiation-specific protein expression and profilaggrin/filaggrin conversion, which were defective in primary-cultures. Using cDNA microarray analysis, lipid transporters including four ATP-binding cassette transporters were up-regulated after sub-culture of Abca12(-/-) keratinocytes compared with primary-culture. These results indicate that disrupted keratinocyte differentiation during the fetal development is involved in the pathomechanism of HI and, during maturation, Abca12(-/-) epidermal keratinocytes regain normal differentiation processes. This restoration may account for the skin phenotype improvement observed in HI survivors.

Comprehensive quantification of ceramide species in human stratum corneum.

One of the key challenges in lipidomics is to quantify lipidomes of interest, as it is practically impossible to collect all authentic materials covering the targeted lipidomes. For diverse ceramides (CER) in human stratum corneum (SC) that play important physicochemical roles in the skin, we developed a novel method for quantification of the overall CER species by improving our previously reported profiling technique using normal-phase liquid chromatography-electrospray ionization-mass spectrometry (NPLC-ESI-MS). The use of simultaneous selected ion monitoring measurement of as many as 182 kinds of molecular-related ions enables the highly sensitive detection of the overall CER species, as they can be analyzed in only one SC-stripped tape as small as 5 mm x 10 mm. To comprehensively quantify CERs, including those not available as authentic species, we designed a procedure to estimate their levels using relative responses of representative authentic species covering the species targeted, considering the systematic error based on intra-/inter-day analyses. The CER levels obtained by this method were comparable to those determined by conventional thin-layer chromatography (TLC), which guarantees the validity of this method. This method opens lipidomics approaches for CERs in the SC.

New bisindole alkaloids isolated from Myxomycetes Arcyria cinerea and Lycogala epidendrum.

Two new bisindole alkaloids, named cinereapyrrole A (1) and B (2), were isolated from wild fruit bodies of Arcyria cinerea and three new bisindole alkaloids (3-5) were isolated from wild fruit bodies of Lycogala epidendrum. Seven known bisindoles (6-12) were concomitantly obtained from them. The structures of the new compounds were elucidated by spectral data. Among these bisindole alkaloids, compound 12 showed cytotoxicity against cultured tumor cell lines.

Isolation of bisindole alkaloids that inhibit the cell cycle from Myxomycetes Arcyria ferruginea and Tubifera casparyi.

From a myxomycete Arcyria ferruginea, dihydroarcyriarubin C (1), a new bisindole alkaloid, has been isolated together with two known bisindoles, arcyriarubin C (2) and arcyriaflavin C (3), and arcyriaflavin C (3) was also isolated from Tubifera casparyi together with arcyriaflavin B (4). Arcyriaflavin C (3) exhibited cell cycle inhibition effect at G1 and G2/M stage at 10 and 100ng/mL, respectively.