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This study investigated the protective effects of glucocerebroside-containing buttermilk concentrated powder (GCBM) on oxidative stress and photoaging in ultraviolet B (UVB)-irradiated hairless mice. We measured antioxidant enzyme activities, collagen synthesis-related pathways, and moisturizing-related factors in the dorsal skin of mice. We observed that dietary supplementation with GCBM increased antioxidant enzyme activity and decreased pro-inflammatory cytokine expression in the UVB-irradiated dorsal skin. Furthermore, dietary supplementation with GCBM inhibited wrinkle formation by suppressing the JNK/c-FOS/c-Jun/MMP pathway and stimulating the TGF-βRI/Smad3/procollagen type I pathway. Dietary supplementation with GCBM also increased skin moisturization by stimulating hyaluronic acid and ceramide synthesis in the dorsal skin. Therefore, buttermilk powder supplementation helps prevent photoaging and can be used as an effective component in developing anti-photoaging products.

Borage oil [BO: 40.9% linoleic acid (LNA) and 24.0% γ-linolenic acid (GLA)] reverses disrupted epidermal lipid barrier in essential fatty acid deficiency (EFAD). We determined the effects of BO on lamellar body (LB) content and LNA and GLA incorporation into epidermal ceramide 1 (CER1) and epidermal ceramide 2 (CER2), major barrier lipids. EFAD was induced in guinea pigs by a diet of 6% hydrogenated coconut oil (HCO) for 10 weeks (group HCO) or 8 weeks followed by 6% BO for 2 weeks (group HCO + BO). LB content and LNA and GLA incorporation into CER1 were higher in group HCO + BO than in group HCO. Small but significant levels of LNA, GLA, and their C20-metabolized fatty acids [dihomo-γ-linolenic acid (DGLA) and arachidonic acid (ARA)] were incorporated into CER2, where ARA was detected at a level lower than LNA, but DGLA incorporation exceeded that for GLA in group HCO + BO. Dietary BO enhanced LB content and differential incorporation of GLA into CER1 and DGLA into CER2.

Borage oil (BO) reverses a disrupted epidermal lipid barrier and hyperproliferation in essential fatty acid deficiency (EFAD). However, little is known about its effect on skin pH, which is maintained by epidermal lactate, free fatty acids (FFAs), and free amino acids (FAAs) which is generated by lactate dehydrogenase (LDH), secreted phospholipase A2 (sPLA2), or filaggrin degradation with peptidylarginine deiminase-3 (PADI3). We hypothesized that BO restores skin pH by regulating epidermal lactate, FFA metabolism, or FAA metabolism in EFAD. To test this hypothesis, EFAD was induced in guinea pigs by a hydrogenated coconut oil (HCO) diet for 8 weeks, followed by 2 weeks of a BO diet (group HCO + BO). As controls, groups HCO and BO were fed HCO or BO diets for 10 weeks. In group HCO + BO, skin pH, which was less acidic in group HCO, was restored; and epidermal lactate and total FFAs, including palmitate, stearate, linoleate, arachidate, behenate, and lignocerate, were higher than in group HCO. LDH and sPLA2 (mainly the PLA2G2F isoform) activities and protein expressions were similar between groups HCO + BO and BO. Epidermal acidic FAAs, as well as filaggrin and PADI3 protein and mRNA expressions were higher in group HCO + BO than in group HCO. Oleate, total FAAs including other FAAs, and LDH and sPLA2 mRNA expressions were not altered between groups HCO and HCO + BO. Basic FAAs were not altered among groups. Dietary BO restored acidic skin pH and increased epidermal levels of lactate, most FFAs, and acidic FAAs by up-regulating LDH, sPLA2, filaggrin, and PADI3 activities as well as protein or mRNA expressions in EFAD.

Triacylglycerol (TAG) metabolism is related to the acyl-ceramide (Cer) synthesis and corneocyte lipid envelope (CLE) formation involved in maintaining the epidermal barrier. Prompted by the recovery of a disrupted epidermal barrier with dietary borage oil (BO: 40.9% linoleic acid (LNA) and 24.0% γ-linolenic acid (GLA)) in essential fatty acid (EFA) deficiency, lipidomic and transcriptome analyses and subsequent quantitative RT-PCR were performed to determine the effects of borage oil (BO) on TAG content and species, and the gene expression related to overall lipid metabolism. Dietary BO for 2 weeks in EFA-deficient guinea pigs increased the total TAG content, including the TAG species esterified LNA, GLA, and their C20 metabolized fatty acids. Moreover, the expression levels of genes in the monoacylglycerol and glycerol-3-phosphate pathways, two major pathways of TAG synthesis, increased, along with those of TAG lipase, acyl-Cer synthesis, and CLE formation. Dietary BO enhanced TAG content, the gene expression of TAG metabolism, acyl-Cer synthesis, and CLE formation.

The stratum corneum (SC) acts as a barrier that protects organisms against the environment and from transepidermal water loss. It consists of corneocytes embedded in a matrix of lipid metabolites (ceramides, cholesterol, and free fatty acids). Of these lipids, ceramides are sphingolipids consisting of sphingoid bases, linked to fatty acyl chains. Typical fatty acid acyl chains are composed of α-hydroxy fatty acids (A), esterified ω-hydroxy fatty acids (EO), non-hydroxy fatty acids (N), and ω-hydroxy fatty acids (O). Of these, O-type ceramides are ester-linked via their ω-hydroxyl group to proteins in the cornified envelope and can be released and extracted following mild alkaline hydrolysis. Tandem mass spectrometry (MS/MS) analysis of O-type ceramides using chip-based direct infusion nanoelectrospray-ion trap mass spectrometry generated the characteristic fragmentation pattern of both acyl and sphingoid units, suggesting that this method could be applied to the structural identification of O-type ceramides. Based on the MS/MS fragmentation patterns of O-type ceramides, comprehensive fragmentation schemes are proposed. In addition, we have also developed a method for identifying and profiling O-type ceramides in the mouse and guinea pig SC. This information may be used to identify O-type ceramides in the SC of animal skin.

Ceramide is the most abundant lipid in the epidermis and plays a critical role in maintaining epidermal barrier function. Overall ceramide content in keratinocyte increases in parallel with differentiation, which is initiated by supplementation of calcium and/or vitamin C. However, the role of metabolic enzymes responsible for ceramide generation in response to vitamin C is still unclear. Here, we investigated whether vitamin C alters epidermal ceramide content by regulating the expression and/or activity of its metabolic enzymes. When human keratinocytes were grown in 1.2 mM calcium with vitamin C (50 μg/ml) for 11 days, bulk ceramide content significantly increased in conjunction with terminal differentiation of keratinocytes as compared to vehicle controls (1.2 mM calcium alone). Synthesis of the ceramide fractions was enhanced by increased de novo ceramide synthesis pathway via serine palmitoyltransferase and ceramide synthase activations. Moreover, sphingosine-1-phosphate (S1P) hydrolysis pathway by action of S1P phosphatase was also stimulated by vitamin C supplementation, contributing, in part, to enhanced ceramide production. However, activity of sphingomyelinase, a hydrolase enzyme that converts sphingomyelin to ceramide, remained unaltered. Taken together, we demonstrate that vitamin C stimulates ceramide production in keratinocytes by modulating ceramide metabolic-related enzymes, and as a result, could improve overall epidermal barrier function.

The innate immune element, cathelicidin antimicrobial peptide (CAMP), is vital in the formation of the antimicrobial barrier in skin. CAMP production is increased during epidermal differentiation and enriched in the stratum corneum. We recently identified an endoplasmic reticulum (ER) stress-mediated sphingosine-1-phosphate (S1P)- dependent mechanism of CAMP synthesis. Interestingly, in this study, we found that S1P synthesized by an isoform of sphingosine kinase (SPHK), SPHK1, serves as a signal for CAMP synthesis; and conversely, another isoform SPHK2 likely has a suppressor role or no role in CAMP production. Pertinently, prior studies showed that physiological ER stress is essential for normal epidermal differentiation. We here demonstrate that: increased ER stress is evident in differentiated cultured keratinocytes (KC); 2) increases in both CAMP and S1P production depend upon differentiation level of KC (proliferated

Epidermal hydration is maintained primarily by natural moisturising factors (NMF), of which free amino acids (AA) are major constituents that are generated by filaggrin degradation. To identify dietary sources that may improve skin dryness of atopic dermatitis (AD), we investigated dietary effects of silk proteins, sericin and fibroin, on epidermal levels of hydration, filaggrins and free AA, as well as PPARγ, peptidylarginine deiminase-3 (PAD3) and caspase-14 proteins involved in filaggrin expression and degradation processes. NC/Nga mice, an animal model of AD, were fed a control diet (group CA: atopic control) or diets with 1 % sericin (group S) or fibroin (group F) for 10 weeks. In group S, epidermal levels of hydration, total filaggrins and total free AA, as well as PPARγ, PAD3 and caspase-14, which were reduced in group CA, were increased to higher or similar levels of a normal control group of BALB/c mice (group C). Furthermore, profilaggrin, a precursor with multiple filaggrin repeats, and three repeat intermediates were increased, while two repeat intermediates and filaggrin were decreased in parallel with increased levels of glutamate and serine, major AA of NMF in group S. Despite increased levels of total filaggrins, total free AA, PPARγ and PAD3, epidermal levels of hydration, glutamate, serine and caspase-14 were not increased, but other minor AA of NMF were highly detected in group F. Dietary sericin improves epidermal hydration in parallel with enhancing profilaggrin expression and degradation into free AA that is coupled with elevated levels of PPARγ, PAD3 and caspase-14 proteins.

Epidermal hydration is maintained by the epidermal lipid barrier, of which ceramide (Cer) is the major constituent. We examined the dietary effect of royal jelly (RJ) on epidermal hydration in aged mice. Altered Cer metabolism was further determined by measuring epidermal levels of individual Cer, glucosylceramide (GC), and sphingomyelin (SM) species, and of Cer-metabolizing enzymes. Aged C57BL/6J mice were fed a control diet (group AGED) or diets with 1% RJ harvested from two different areas (groups AGED+RJ1:AGED + RJ2) for 16 weeks. Aged C57BL/6J mice with no dietary intervention (the control group: group C) represented the onset of aging. In group AGED, epidermal levels of hydration, Cer1/2/5/6/7, GC-A/B/C/D, SM1/2/3, and β-glucocerebrosidase (GCase) protein, an enzyme of GC hydrolysis for Cer generation, were lower than in group C; these levels, as well as those of Cer3/4 and acidic sphingomyelinase (aSMase) protein, an enzyme of SM hydrolysis for Cer generation, were higher in group AGED + RJ1 than in group AGED. Despite increases in GC-B, SM1/2/3, and serine palmitoyltransferase2 protein, an enzyme of de novo Cer synthesis, in group AGED + RJ2 to levels higher than in group AGED, epidermal levels of hydration, Cer1-7, GC-A/C/D, GCase, and aSMase proteins were similar in these two groups. Expression of GCase and aSMase mRNAs, and of Cer synthase3 and ceramidase proteins, enzymes of de novo Cer synthesis and degradation, did not differ among groups. Dietary RJ1 improved epidermal hydration by enhancing Cer metabolism with increased levels of all Cer, GC, and SM species, and of GCase and aSMase proteins.

Ceramide 1 (Cer1), a Cer species with eicosasphingenine (d20:1) amide-linked to two different ω-hydroxy fatty acids (C30wh:0:C32wh:1), which are, in turn, ester-linked to linoleic acid (LNA; 18:2n-6), plays a critical role in maintaining the structural integrity of the epidermal barrier. Prompted by the recovery of a disrupted epidermal barrier with dietary borage oil [BO: 36.5 % LNA and 23.5 % γ-linolenic acid (GLA; 18:3n-6)], in essential fatty acid (EFA)-deficient guinea pigs, we further investigated the effects of BO on the substitution of ester-linked GLA for LNA in these two epidermal Cer1 species by LC–MS in positive and negative modes. Dietary supplementation of BO for 2 weeks in EFA-deficient guinea pigs increased LNA ester-linked to C32wh:1/d20:1 and C30wh:0/d20:1 of Cer1. Moreover, GLA ester-linked to C32wh:1/d20:1, but not to C30wh:0/d20:1, of Cer1 was detected, which was further confirmed by the product ions of m/z 277.2 for ester-linked GLA and m/z 802.3 for the deprotonated C32wh:1/d20:1. C20-Metabolized fatty acids of LNA or GLA were not ester-linked to these Cer1 species. Dietary BO induced GLA ester-linked to C32wh:1/d20:1 of epidermal Cer1.

To compare the systemic efficacy of borage oil (Borago officinalis: BO) and gromwell (Lithospermum erythrorhizon), two plant species of the Boraginaceae family, epidermal hyperproliferation was induced in guinea pigs by a hydrogenated coconut oil diet for 8 weeks. Subsequently, guinea pigs were fed diets of BO (group HBO), organic extract (group HGO), or water extract (group HGW) of gromwell for 2 weeks. In groups HGO and HGW, proliferation scores and the level of ceramides, the major lipid maintaining epidermal barrier, were similar with those in normal control group BO fed BO diet for 10 weeks. Despite accumulation of 15-hydroxyeicosatrienoic acid (15-HETrE), the potent anti-proliferative metabolite of gamma-linolenic acid (GLA: major polyunsaturated fatty acid in BO), the reversal of epidermal hyperproliferation and the ceramide level of group HBO were less than those of groups HGO and HGW. Taken together, our data demonstrate that gromwell is more effective in reversing epidermal hyperproliferation with a marked increase in ceramides.

The skin displays a highly active metabolism of polyunsaturated fatty acids (PUFA). Dietary deficiency of linoleic acid (LA), an 18-carbon (n-6) PUFA, results in characteristic scaly skin disorder and excessive epidermal water loss. Although arachidonic acid (AA), a 20-carbon (n-6) PUFA, is metabolized via cyclooxygenase pathway into predominantly prostaglandin E2 (PGE2) and PGF2alpha, the metabolism of AA via the 15-lipoxygenase (15-LOX) pathway, which is very active in skin epidermis and catalyzes the transformation of AA into predominantly 15S-hydroxyeicosatetraenoic acid (15S-HETE). Additionally, the 15-LOX also metabolizes the 18-carbon LA into 13S-hydroxyoctadecadienoic acid (13S-HODE), respectively. Interestingly, 15-LOX catalyzes the transformation of dihomo-gamma-linolenic acid (DGLA), derived from dietary gamma-linolenic acid, to 15S-hydroxyeicosatrienoic acid (15S-HETrE). These monohydroxy fatty acids are incorporated into the membrane inositol phospholipids which undergo hydrolytic cleavage to yield substituted-diacylglycerols such as 13S-HODE-DAG from 13S-HODE and 15S-HETrE-DAG from 15S-HETrE. These substituted-monohydroxy fatty acids seemingly exert anti-inflammatory/antiproliferative effects via the modulation of selective protein kinase C as well as on the upstream/down-stream nuclear MAP-kinase/AP-1/apoptotic signaling events.

The skin displays a highly active metabolism of polyunsaturated fatty acids (PUFA). Dietary deficiency of linoleic acid (LA), an 18-carbon (n-6) PUFA, results in characteristic scaly skin disorder and excessive epidermal water loss. Although arachidonic acid (AA), a 20-carbon (n-6) PUFA, is metabolized via cyclooxygenase pathway into predominantly prostaglandin E2 (PGE2) and PGF2alpha. The 15-lipoygenase is very active in this tissue and catalyzes the transformation of 20-carbon AA into predominantly 15-hydroxyeicosatetraenoic acid (15-HETE). Similarly, the epidermal 15-lipoxygenase also catalyzes the transformation of 18-carbon LA and 20-carbon dihomo-gamma-linolenic acid (DGLA) to 13-hydroxyoctadecadienoic acid (13-HODE) and 15-hydroxyeicosatrienoic acid (15-HETrE), respectively. The monohydroxy fatty acids are incorporated in phospholipids which undergo catalysis to yield substituted-diacylglycerols (13-HODE-DAG) and 15-HETrE-DAG) which exert anti-inflammatory/antiproliferative effects on the skin.

Diacylglycerol containing 15-hydroxyeicosatrienoic acid (15-HETrE–DAG) was biosynthesized and examined for modulation of epidermal protein kinase C (PKC) activity. 15-HETrE–DAG competitively inhibited diolein-activated total PKC activity in a dose-dependent manner and further, selectively inhibited epidermal PKC-β activity.

We have previously reported that dietary gromwell (Lithospermum erythrorhizon; LE) prevents the development of atopic dermatitis (AD) with increased epidermal levels of total ceramide (Cer), the major lipid maintaining epidermal barrier. In this study, we investigated whether the increased level of total Cer induced by dietary LE would be related to the altered metabolism of glucosylceramide (GlcCer) and sphingomyelin (SM), two major precursor lipids in Cer generation. NC/Nga mice, an animal model of AD, were fed a control diet (group CA: atopic control) or a diet with 70% ethanol LE extracts (1% in diet; group LE) for 10 weeks. Individual species of Cer, GlcCer, and SM were analyzed by high-performance thin layer chromatography. In the epidermis of group CA, total Cer (including Cer2 and Cer5–7) and total GlcCer (including GlcCer-B/C/D) were significantly reduced; these levels in group LE were increased to levels similar to the normal control group of BALB/c mice (group C). In addition, protein expressions and activities of β-glucocerebrosidase (β-GlcCer'ase) and acidic sphingomyelinase (aSMase), enzymes for GlcCer or SM hydrolysis, respectively, were increased in group LE. However, alterations of Cer1, Cer3/4, GlcCer-A, and all SM species (including SM1–3) were not significant among groups C, CA, and LE. Dietary gromwell increases GlcCer-B/C/D, and further enhances the generation of Cer2 and Cer5–7 with high protein expressions and activities of β-GlcCer'ase and aSMase.

Purpose: Skin pH, an indicator of skin health, is maintained by various organic factors, which include lactate, free amino acid (FAA), and free fatty acid (FFA). As skin ages or with illness, skin pH becomes less acidic, and functional food has been developed to maintain the acidic pH of skin. In this study, we determined the dietary effect of green tea extract (GTE) on skin pH of photo-aged mice, as measured by epidermal levels of lactate, FAA, and FFA. The protein expression and activity of lactate dehydrogenase (LDH), an enzyme of pyruvate reduction for lactate generation, was further determined. Methods: Albino hairless mice were fed a control diet (group UV+) or a diet with 1% GTE (group GTE) in parallel with UV irradiation for 10 weeks. A normal control group was fed a control diet without UV irradiation for 10 weeks (group UV-). Results: Skin pH was higher (less acidic) in group UV+ than in group UV-. In parallel, epidermal levels of lactate and FFA, as well as of LDH protein expression and activity, were reduced in group UV+. Dietary supplementation of GTE (group GTE) reduced skin pH to similar to the level of group UV-, and inversely increased epidermal levels of lactate, LDH protein expression and activity, but not of FFA. Although epidermal levels of FAA were similar in groups UV- and UV+, it was increased in group GTE to a level higher than in group UV-. In further analysis of major FFA, epidermal levels of palmitic acid [16:0], oleic acid [18:1(n-9)], and linoleic acid [18:2(n-6), but not of stearic acid [18:0] in group GTE were similar to or lower than those in group UV+. Conclusion: Dietary GTE normalized skin pH with increased levels of lactate and FAA, as well as with increased protein expression and activity of LDH in the epidermis of UVB irradiated hairless mice.

We have previously reported that dietary sericin improves epidermal dryness with the increased total Ceramide (Cer) in NC/Nga mice, an animal model of atopic dermatitis (AD). In this study, we hypothesized that the increased level of total Cer induced by dietary sericin would be related to the altered metabolism of glucosylceramide (GlcCer) and sphingomyelin (SM), major precursors of Cer generation. NC/Nga mice were fed a control diet (group CA: atopic control) or diets with 1% silk protein, either sericin (group S) or fibroin (group F) for 10 weeks. In the epidermis of group CA, total Cer (including Cer1, 2, 3/4 and 6) and all GlcCer species were reduced; these levels in group S were increased to levels similar to or higher than in the normal control group of BALB/c mice (group C). In addition, the protein expressions, but not mRNA expressions, of GlcCer synthase, β-glucocerebrosidase, and acidic sphingomyelinase, enzymes for GlcCer synthesis, GlcCer and SM hydrolysis, respectively, were highly increased in group S. The epidermal levels of total Cer (including Cer2, 3/4, and 6) and all GlcCer species and of these enzyme proteins in group F were lower than in group S. Notably, alterations in total SM, SM1, SM3, and SM synthase 1, which were increased in group CA, were not significant between groups S and F. Cer5 and SM2 were not altered among groups. Dietary sericin enhanced the epidermal levels of all GlcCer and most Cer species with up-regulating protein expressions of GlcCer synthase, β-glucocerebrosidase, and acidic sphingomyelinase.

Prompted by the reversal of skin hyperproliferation to normal by 13-hydroxyoctadecadienoic acid (13-HODE), a 15-lipoxygenase metabolite of linoleic acid, we investigated a possible mechanism for this antiproliferative action. To address this we first demonstrated that 13-HODE is incorporated into epidermal phosphatidyl 4,5-bisphosphate (PtdIns4,5-P2) and released as 13-HODE-containing diacylglycerol by epidermal phospholipase C. Secondly, we tested the possibility whether this putative 13-HODE-containing DAG (13HODE-DAG) could exert a modulatory effect on epidermal protein kinase C (PKC) activity which previously has been associated with skin hyperproliferation. Unlabeled 13HODE-DAG was generated from 13-HODE-containing phosphatidylcholine after phospholipase C hydrolytic cleavage. The effects of the 13HODE-DAG were determined on: i) total epidermal PKC activity; ii) diolein-activated PKC activity; and iii) the two identified epidermal PKC-isozymes (PKC-beta and PKC-alpha). Our data revealed over a twofold activation of total basal PKC activity by diolein. In contrast, replacement of diolein (1,2-dioleoylglycerol) with 13HODE-DAG (1-palmitoyl,2-13HODE-glycerol) in the incubation mixture exerted no effect on total basal PKC activity. In an another experiment, 13HODE-DAG inhibited diolein-activated PKC activity in a dose-dependent manner. To determine whether the effects of 13HODE-DAG are selective, we tested its effects on DEAE-Sephacel-purified and Western blot-confirmed PKC isozymes. Our data revealed that 13HODE-DAG selectively inhibited the activity of PKC-beta isozyme, while exerting negligible effect on the PKC-alpha isozyme. This selective inhibitory effect of 13HODE-DAG on a major epidermal PKC isozyme activity suggests that 13HODE-containing DAG seemingly can modulate epidermal PKC activity, which purportedly is associated with epidermal hyperproliferation.

The most abundant polyunsaturated fatty acids (PUFAs) in human skin are linoleic acid (LA, 18: 2n-6) and arachidonic acid (AA, 20: 4n-6) (1, 2). LA is metabolized by epidermal 15-lipoxygenase into predominantly 13-hydroxyoctadecadienoic acid (13-HODE). An analysis of lipoxygenase products in the model of docosahexaenoic acid (22: 6n-3. DHA-induced hyperproliferative skin epidermis revealed a selective and markedly depressed level of 13-hydroxyoctadecadienoic acid (13-HODE), (3). The topical application of 13-HODE on the DHA-induced hyperproliferative guinea pig (GP) epidermis caused a reversal to a normal state. The reversal paralleled the in vivo replenishment of tissue with 13-HODE (3). These findings suggested that 13-HODE, may be involved in the regulation of epidermal hyperproliferation.

Ceramides and phospholipids constitute two important structural lipids of normal skin that are notably rich in polyunsaturated fatty acids. Although linoleic acid (LA) is high in the ceramides, the localization of its 15-lipoxygenase product, 13-hydroxyoctadecadienoic acid (13-HODE) in the epidermis is unknown. In this study, we investigated the relative incorporation of [14C]LA and [14C]13-HODE into ceramides and phospholipids in isolated epidermal slices. Our data revealed minor incorporation of [14C]LA and [14C]13-HODE into ceramides. In contrast, both [14C]LA and [14C]13-HODE are markedly incorporated into phospholipids, particularly, phosphatidylcholine (PC) and phosphatidylinositol (PtdIns). The incorporation of 13-HODE into the PtdIns pool in particular prompted us to investigate into its fate in the signal transduction process and its possible incorporation into diacylglycerol. Our data revealed that 13-HODE is incorporated into epidermal phosphatidylinositol 4,5-bisphosphate (PtdIns4,5-P2) resulting in epidermal phospholipase C-catalyzed release into a novel 13-HODE-containing diacylglycerol (1-acyl-2-13-HODE-glycerol). The possibility now exists that this novel 13-HODE-containing diacylglycerol could function to modulate the activity of epidermal protein kinase C and hyperproliferation/differentiation.

Royal jelly (RJ) is a honeybee product containing proteins, carbohydrates, fats, free amino acids, vitamins, and minerals. As its principal unsaturated fatty acid, RJ contains 10-hydroxy-2-decenoic acid (10-HDA), which may have antitumor and antibacterial activity and a capacity to stimulate collagen production. RJ has attracted interest in various parts of the world for its pharmacological properties. However, the effects of RJ on ultraviolet (UV)-induced photoaging of the skin have not been reported. In this study we measured the 10-HDA content of RJ by high-performance liquid chromatography and tested the effects of RJ on UVB-induced skin photoaging in normal human dermal fibroblasts. The effects of RJ and 10-HDA on UVB-induced photoaging were tested by measuring procollagen type I, transforming growth factor (TGF)-β1, and matrix metalloproteinase (MMP)-1 after UVB irradiation. The RJ contained about 0.211% 10-HDA. The UVB-irradiated human skin fibroblasts treated with RJ and 10-HDA had increased procollagen type I and TGF-β1 productions, but the level of MMP-1 was not changed. Thus RJ may potentially protect the skin from UVB-induced photoaging by enhancing collagen production.

Purpose: Borage oil (BO) and safflower oil (SO) are efficacious in reversing epidermal hyperproliferation, which is caused by the disruption of epidermal barrier. In this study, we compared the antiproliferative effect of dietary BO and SO. Altered metabolism of ceramide (Cer), the major lipid of epidermal barrier, was further determined by measurement of epidermal levels of individual Cer, glucosylceramide (GlcCer), and sphingomyelin (SM) species, and protein expression of Cer metabolizing enzymes. Methods: Epidermal hyperproliferation was induced in guinea pigs by a hydrogenated coconut diet (HCO) for 8 weeks. Subsequently, animals were fed diets of either BO (group HCO + BO) or SO (group HCO + SO) for 2 weeks. As controls, animals were fed BO (group BO) or HCO (group HCO) diets for 10 weeks. Results: Epidermal hyperproliferation was reversed in groups HCO + BO (67.6% of group HCO) and HCO + SO (84.5% of group HCO). Epidermal levels of Cer1/2, GlcCer-A/B, and β-glucocerebrosidase (GCase), an enzyme of GlcCer hydrolysis for Cer generation, were higher in group HCO + BO than in group HCO, and increased to levels similar to those of group BO. In addition, epidermal levels of SM1, serine palmitoyltransferase (SPT), and acidic sphingomyelinase (aSMase), enzymes of de novo Cer synthesis and SM hydrolysis for Cer generation, but not of Cer3-7, were higher in group HCO + BO than in group HCO. Despite an increase of SPT and aSMase in group HCO + SO to levels higher than in group HCO, epidermal levels of Cer1-7, GlcCer-A/B, and GCase were similar in these two groups. Notably, acidic ceramidase, an enzyme of Cer degradation, was highly expressed in group HCO + SO. Epidermal levels of GlcCer-C/D and SM-2/3 did not differ among groups. Conclusion: Dietary BO was more prominent for reversing epidermal hyperproliferation by enhancing Cer metabolism with increased levels of Cer1/2, GlcCer-A/B, and SM1 species, and of GCase proteins.

Background Ceramides are the main lipid component of the stratum corneum and are a structurally heterogeneous and complex group of sphingolipids of which sphingoid bases are the basic structural constituents. Altered levels of sphingoid bases have been reported in skin conditions that involve dryness and barrier disruption, including atopic dermatitis. Objective The purpose of this study was to investigate the altered levels of sphingoid bases in psoriatic epidermis and their relationship with the clinical severity of the psoriasis. Methods Samples from the lesional and non-lesional epidermis were obtained from eight psoriasis patients. Levels of sphingosine and sphinganine were analyzed by high-performance liquid chromatography. The expression of ceramide synthase and ceramidase proteins, which are related to sphingosine and sphinganine metabolism, were measured using Western blot analysis. Results Levels of sphingosine and sphinganine in the lesional epidermis were significantly higher than those in the non-lesional epidermis. Although there was no altered ceramide synthase and ceramidase, there was a highly significant positive correlation between the % change of ceramidase, the degradative enzyme of ceramide into sphingosine, and the Psoriasis Area Severity Index (PASI) score. Conclusion The levels of sphingosine and sphinganine were significantly increased in psoriatic epidermis and the % change of ceramidase was positively correlated with the clinical severity of psoriasis.

Ceramides (Cer) comprise the major constituent of sphingolipids in the epidermis and are known to play diverse roles in the outermost layers of the skin including water retention and provision of a physical barrier. In addition, they can be hydrolyzed into free sphingoid bases such as C(18) sphingosine (SO) and C(18) sphinganine (SA) or can be further metabolized to C(18) So-1-phosphate (S1P) and C(18) Sa-1-phosphate (Sa1P) in keratinocytes. The significance of ceramide metabolites emerged from studies reporting altered levels of SO and SA in skin disorders and the role of S1P and Sa1P as signaling lipids. However, the overall metabolism of sphingoid bases and their phosphates during keratinocyte differentiation remains not fully understood. Therefore, in this study, we analyzed these Cer metabolites in the process of keratinocyte differentiation. Three distinct keratinocyte differentiation stages were prepared using 0.07 mM calcium (Ca(2+)) (proliferation stage), 1.2 mM Ca(2+) (early differentiation stage) in serum-free medium, or serum-containing medium with vitamin C (50 µL/mL) (late differentiation stage). Serum-containing medium was also used to determine whether vitamin C increases the concentrations of sphingoid bases and their phosphates. The production of sphingoid bases and their phosphates after hydrolysis by alkaline phosphatase was determined using high-performance liquid chromatography. Compared to cells treated with 0.07 mM Ca(2+), levels of SO, SA, S1P, and SA1P were not altered after treatment with 1.2 mM Ca(2+). However, in keratinocytes cultured in serum-containing medium with vitamin C, levels of SO, SA, S1P, and SA1P were dramatically higher than those in 0.07- and 1.2-mM Ca(2+)-treated cells; however, compared to serum-containing medium alone, vitamin C did not significantly enhance their production. Taken together, we demonstrate that late differentiation induced by vitamin C and serum was accompanied by dramatic increases in the concentration of sphingoid bases and their phosphates, although vitamin C alone had no effect on their production.

Collagen is the major matrix protein in dermis and consists of proline and lysine, which are hydroxylated by prolyl hydroxylase (PH) and lysyl hydroxylase (LH) with cofactors such as vitamin C, oxygen, iron (Fe²?), ketoglutarate and silicon. The collagen degradation is regulated by matrix metalloproteinase-1 (MMP-1), of which is the major collagendegrading proteinase whereas tissue inhibitors of metalloproteinase-1 (TIMP-1) bind to MMP-1 thereby inhibiting MMP-1 activity. In this study, we investigated the effects of vitamin C, silicon and iron on mRNA, protein expressions of PH, LH, MMP-1 and TIMP-1. The physiological concentrations of vitamin C (0-100 ㎛), silicon (0-50 ㎛) and iron (Fe²?：0-50 ㎛) were treated to human dermal fibroblast cells (HS27 cells) for 3 or 5days. The expression level of mRNA and protein was increased in not only PH but also LH when cells were incubated with vitamin C. A similar increase in LH mRNA or protein expression occurred when cells were incubated with silicon. Our results suggest that treatment of vitamin C and silicon increased mRNA and protein expression of PH and LH in human dermal fibroblast.

Collagen I and III are the major matrix proteins in dermis and consist of proline and lysine, which are hydroxylated by prolyl hydoxylase (PH) and lysyl hydroxylase with cofactors such as ascorbic ...