It is recognized that reactive oxygen species (ROS) are responsible for skin damage due to UVB-radiation (UVB-R). However, the triggering substance(s) for ROS generation after UVB-R is uncertain with respect to the activation of NADPH oxidase (Nox), xanthine oxidase (XOD), and respiratory chain-chain reactions in mitochondria. As a first step in identifying the trigger(s) for UVB-induced ROS generation, we examined the relationship between Ca(2+) levels and ROS generation in HaCaT keratinocytes. UVB-R exposure of HaCaT keratinocytes resulted in an immediate elevation of ROS that recurred 7 hours later. This was accompanied by immediately elevated intracellular Ca(2+) . A Ca(2+) chelating agent, BAPTA, abolished the elevation of ROS after UVB-R completely. In addition, exogenous H(2)O(2) did not increase intracellular Ca(2+) levels. This suggests that intracellular Ca(2+) is the first trigger for UVB-induced ROS generation.Journal of Investigative Dermatology Symposium Proceedings (2009) 14, 50-52; doi:10.1038/jidsymp.2009.12.

Moisturization of the skin plays an important role in maintaining skin homeostasis. Although it is understood that skin dryness initiates the formation of fine wrinkles, there are few objective reports to support that understanding. The purpose of this study was to establish an in vitro dry epidermal model using reconstructed human epidermal equivalents (RHEEs) and to elucidate the relationship between skin dryness and alterations of the dermal matrix which is one of the causes for the formation of wrinkles. An in vitro dry epidermal model was prepared by loading a CaCl2 -filled ampoule on the surface of an RHEE. To evaluate whether the in vitro model reproduced the characteristics of in vivo skin dryness, histological studies and biological assays using a protein array were carried out. Histologically, a distinct fluorescence which originated from carbonylated protein was observed in the stratum corneum. In addition, conditioned medium from RHEEs cultured under dry conditions for 24 h revealed the secretion of several proteins, such as IL-1α, IL-1ra, IL-8, MMP-9, VEGF, M-CSF and IGFBP-2 and IGFBP-3, galectin-1, Cys-C, FGF-6, OPG, Glc and TSP4 compared with normal RHEEs. It has been reported that an increase in IL-1α and the accumulation of carbonylated proteins are observed in the intact stratum corneum in the low humidity winter season. Thus, the in vitro dry epidermal model expresses the features of in vivo skin dryness observed in the winter season. Furthermore, the conditioned medium from RHEEs cultured under dry conditions enhanced MMP-1 secretion by normal human dermal fibroblasts. Taken together, we propose the hypothesis that skin dryness contributes to alterations of the dermal matrix through the elevation of MMP-1 secretion.

Recent studies have demonstrated that lysophospholipids (LPL) play critical roles in several biological signal transduction pathways to maintain the homoeostasis of cells, tissues and organs. Among them, lysophosphatidic acid (LPA) has been identified as a lipid mediator that induces morphological improvement in the epidermis in mice. In this study, we examined the effects of LPL (soybean-derived phospholipids modified with phospholipase A2 and C) compared with LPA. We initially examined the effects of LPA on normal human epidermal keratinocytes (NHEK) focusing on the expression of profilaggrin and serine palmitoyltransferase (SPT) mRNAs. LPA enhanced the expression of profilaggrin and SPT mRNAs via the modulation of Ca(2+) influx. Based on those results, the influence of LPL on NHEK was examined and was expanded to analyse the expression of two tight junction-related proteins, occludin and claudin-1. LPL had similar effects to increase profilaggrin and SPT mRNA expression and also stimulated the expression of occludin and claudin-1 at the mRNA and protein levels. In accordance with these results, LPL elicited significant improvements in surface water content in human skin. These findings indicate that LPL has the potential to strengthen the skin moisturizing capability by up-regulating the expression of mRNAs encoding components important to skin barrier function and skin hydration.

EDCEP reduces cellular damage initiated by environmental pollutants by stimulating the intracellular defense system against ROS through the activation of Nrf2, and by interfering with AHR signaling pathway activation.

Background Tetra‐isopalmitoyl ascorbic acid (VC‐IP), an oil‐soluble vitamin C derivative, is known to be effective for treating photoaging skin caused by oxidative stress. In addition, it is known that morphological changes of the skin occur on the face with aging, and the main cause has been reported to be photoaging. Aims There have not been any published reports that examined the clinical effects of vitamin C derivatives on periorbital wrinkles. The purpose of this study was to characterize the potential anti‐wrinkle effect of VC‐IP. Methods A double‐blind, randomized, placebo‐controlled, split face clinical trial was performed on 3 groups of 23 female subjects each who used 1%, 2%, or 3% VC‐IP creams versus a placebo cream to treat their facial wrinkles. VC‐IP cream was applied on the periorbital area on one side of the face of each subject twice a day for 8 weeks and a placebo cream was applied on the other side. Anti‐wrinkle effects were evaluated by visual wrinkle grading and topographic assessments. Results Periorbital wrinkles treated with VC‐IP twice a day for 8 weeks showed marked or moderate improvements according to visual observations and grading of photographs. Moreover, topographic assessments confirmed the improving effects of VC‐IP, and more interestingly, the appearance of those effects differed depending on the VC‐IP concentration. In addition, sufficient improvement was observed in parameters reported to be associated with dermal structure at lower concentrations of VC‐IP. Conclusions These results indicate that topical application of VC‐IP cream reduces periorbital wrinkles caused by skin aging.

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Alkyl glyceryl ethers (AKGs) are widely used as emulsion stabilizers, and their anti-inflammatory effects are well known. Daily exposure to environmental stresses, such as chemicals, low humidity and ultraviolet light (UV), can initiate and promote the development of various skin problems. Among those stresses, it has been established that UV induces skin pigmentation and accelerates premature skin aging due to the inflammation that results. Here, we investigated whether chimyl alcohol (CA), which is an AKG, suppresses the inflammatory process. The suppression of cell damage and the reduction of intracellular levels of reactive oxygen species (ROS) in normal human epidermal keratinocytes (NHEKs) after UVB exposure was evaluated using the Neutral red (NR) and the 2',7'-dichlorodihydrofluorescein diacetate (DCFDA) assays, respectively. Moreover, the expression levels of mRNAs and proteins related to inflammation were evaluated by Real-time RT-PCR and ELISA assays, respectively. CA suppressed prostaglandin E (PGE) production in UVB-exposed NHEKs according to the down-regulated expression level of cyclooxygenase-2 (COX-2) mRNA. Furthermore, CA up-regulated the mRNA expression levels of peroxisome proliferator-activated receptor (PPAR)-γ, nuclear factor E2-related factor 2 (Nrf2) and γ-glutamyl cysteine synthase (γ-GCS) in NHEKs. Finally, we examined the effects of CA on siPPAR-γ transfected NHEKs. siPPAR-γ transfection of NHEKs abolished the mRNA expression levels of Nrf2 and UVB-stimulated PGE secretion that were regulated by CA. Hence, CA suppresses the UVB-induced COX-2 mRNA expression and PGE production through PPAR-γ as an agonist. We conclude that CA provides useful protection and/or alleviation against UV damage.

Pyridoxine (PN), one of the vitamers of vitamin B6, plays an important role in the maintenance of epidermal function and is used to treat acne and rough skin. Clinical studies have revealed that PN deficiency causes skin problems such as seborrheic dermatitis and stomatitis. However, the detailed effects of PN and its mechanism of action in epidermal function are poorly understood. In this study, we examined the effects of PN on epidermal function in normal human epidermal keratinocytes and found that PN specifically causes an increase in the expression of profilaggrin mRNA, among marker genes of terminal epidermal differentiation. In addition, PN treatment caused an increase in the production of filaggrin protein in a concentration-dependent manner. Treatment with P2x purinoceptor antagonists, namely, pyridoxal phosphate-6-azo (benzene-2,4-disulfonic acid) tetrasodium salt hydrate and TNP-ATP hydrate, induced an increase in the filaggrin protein levels. Moreover, we showed that elevated filaggrin production induced upon PN treatment was suppressed by ATP (known as P2x purinoceptor agonist). This study is the first to report that PN causes an increase in filaggrin transcription and production, and these results suggest that PN-induced filaggrin production may be a useful target as a daily care component in atopic dermatitis, wherein filaggrin levels are specifically reduced.