Enlarged rete pegs with excessive accumulation of melanosomes leading to darker aging spots revealed by histomorphological measurements of internal structures of the epidermis.

OBJECTIVE: Various histological studies of facial pigmented spot sites such as solar lentigo have been reported, but few studies have used quantitative indices by histomorphometric analysis of the internal structure of pigmented spot sites using non-invasive methods. In the present study, to quantitatively elucidate morphological changes in the epidermis in male, darker-pigmented spots and female, light-pigmented spots, indices that characterize the internal structure of the epidermis in pigmented spot sites were measured using in vivo confocal laser scanning microscopy (CLSM). METHODS: The darkness of pigmented spots on the cheeks of 69 women and 43 men was analysed using image analysis software. The L* value was calculated from RGB values obtained from facial images. The internal structures of pigmented spots on the cheeks of 13 subjects were observed by CLSM. Various parameters were measured using CLSM images from the surface of the stratum corneum to the bottom of the dermal papillae, including the thickness of the epidermis, melanosome content, and shape of the dermal papillae. RESULTS: Mean ΔL* values between pigmented spots and non-pigmented areas of male subjects were significantly increased in the 40s and 50s compared with those of female subjects. Conspicuous pigmented spots increased in the 40s in male subjects and the 50s in female subjects. In CLSM observations, significant increases in the thickness of the epidermis and melanosome content were confirmed in pigmented spots compared with surrounding non-pigmented areas. In particular, melanosome content in the male subject group with dark-coloured pigmented spots increased significantly to about eight times that of non-pigmented areas, and more than double that of the male subject group with light-coloured pigmented spots. CONCLUSION: From the measurements of quantitative parameters, morphological changes in the epidermis were clearly related to the surface colour tone of pigmented spots. Darker pigmented spot sites tended to show longer rete pegs in the epidermis. Accumulation of melanosomes in epidermal basal cells could be considered to increase with the degree of elongation of rete pegs at pigmented spot sites and, thus, induce darker pigmented spots.

OBJECTIF: Même si diverses études histologiques des taches pigmentées du visage, tels que les lentigos solaires, ont été publiées, il n'existe que peu d'études ayant utilisé des indices quantitatifs par analyse histomorphométrique de la structure interne des taches pigmentées via des méthodes non invasives. Dans la présente étude, afin d'expliquer quantitativement les changements morphologiques dans l'épiderme des taches pigmentées plus foncées chez l'homme et des taches pigmentées légères chez la femme, les indices qui caractérisent la structure interne de l'épiderme dans les taches pigmentées ont été mesurés par microscopie confocale à balayage laser (MCBL) in vivo. MÉTHODES: L'aspect foncé des taches pigmentées sur les joues de 69 femmes et 43 hommes a été analysé à l'aide d'un logiciel d'analyse d'images. La valeur L* a été calculée à partir des valeurs RVB obtenues des images du visage. Sur les joues de 13 sujets, les structures internes des taches pigmentées ont été observées par MCBL. Divers paramètres ont été mesurés à l'aide des images provenant de la MCBL, de la surface de la couche cornée jusqu'au bas des papilles dermiques, y compris l'épaisseur de l'épiderme, la teneur en mélanosome et la forme des papilles dermiques. RÉSULTATS: Les valeurs moyennes de ΔL* entre les zones de taches pigmentées et non pigmentées des hommes ont augmenté de manière significative chez les sujets dans la quarantaine et la cinquantaine par rapport aux valeurs des femmes. Chez les hommes, les taches pigmentées visibles ont augmenté dans la quarantaine, tandis qu'elles ont augmenté dans la cinquantaine chez les femmes. Dans les observations par MCBL, des augmentations significatives de l'épaisseur de l'épiderme et de la teneur en mélanosome ont été confirmées dans les zones de taches pigmentées par rapport aux zones de taches non pigmentées environnantes. Dans le groupe d'hommes présentant des taches pigmentées de couleur foncée en particulier, la teneur en mélanosomes a augmenté de façon significative jusqu'à environ 8 fois celle des zones non pigmentées, et jusqu'à plus du double de celle du groupe d'hommes présentant des taches pigmentées de couleur claire. CONCLUSION: D'après les mesures des paramètres quantitatifs, les changements morphologiques dans l'épiderme étaient clairement liés à la couleur à la surface des taches pigmentées. Les sites de taches pigmentées plus foncées montraient généralement des extensions des crêtes épidermiques dans l'épiderme. On pourrait envisager que l'accumulation de mélanosomes dans les cellules basales épidermiques augmente selon le degré d'allongement des crêtes épidermiques au niveau des sites de taches pigmentées, et entraîne ainsi des taches pigmentées plus foncées.

Extract of Scutellaria baicalensis induces semaphorin 3A production in human epidermal keratinocytes.

In a disease-state-dependent manner, the histamine-resistant itch in dry skin-based skin diseases such as atopic dermatitis (AD) and xerosis is mainly due to hyperinnervation in the epidermis. Semaphorin 3A (Sema3A) is a nerve repulsion factor expressed in keratinocytes and it suppresses nerve fiber elongation in the epidermis. Our previous studies have shown that Sema3A ointment inhibits epidermal hyperinnervation and scratching behavior and improves dermatitis scores in AD model mice. Therefore, we consider Sema3A as a key therapeutic target for improving histamine-resistant itch in AD and xerosis. This study was designed to screen a library of herbal plant extracts to discover compounds with potential to induce Sema3A in normal human epidermal keratinocytes (NHEKs) using a reporter gene assay, so that positive samples were found. Among the positive samples, only the extract of S. baicalensis was found to consistently increase Sema3A levels in cultured NHEKs in assays using quantitative real-time PCR and ELISA. In evaluation of reconstituted human epidermis models, the level of Sema3A protein in culture supernatants significantly increased by application of the extract of S. baicalensis. In addition, we investigated which components in the extract of S. baicalensis contributed to Sema3A induction and found that baicalin and baicalein markedly increased the relative luciferase activity, and that baicalein had higher induction activity than baicalin. Thus, these findings suggest that S. baicalensis extract and its compounds, baicalin and baicalein, may be promising candidates for improving histamine-resistant itch via the induction of Sema3A expression in epidermal keratinocytes.

Beneficial Effects of the Genus Aloe on Wound Healing, Cell Proliferation, and Differentiation of Epidermal Keratinocytes.

Aloe has been used as a folk medicine because it has several important therapeutic properties. These include wound and burn healing, and Aloe is now used in a variety of commercially available topical medications for wound healing and skin care. However, its effects on epidermal keratinocytes remain largely unclear. Our data indicated that both Aloe vera gel (AVG) and Cape aloe extract (CAE) significantly improved wound healing in human primary epidermal keratinocytes (HPEKs) and a human skin equivalent model. In addition, flow cytometry analysis revealed that cell surface expressions of ß1-, α6-, ß4-integrin, and E-cadherin increased in HPEKs treated with AVG and CAE. These increases may contribute to cell migration and wound healing. Treatment with Aloe also resulted in significant changes in cell-cycle progression and in increases in cell number. Aloe increased gene expression of differentiation markers in HPEKs, suggesting roles for AVG and CAE in the improvement of keratinocyte function. Furthermore, human skin epidermal equivalents developed from HPEKs with medium containing Aloe were thicker than control equivalents, indicating the effectiveness of Aloe on enhancing epidermal development. Based on these results, both AVG and CAE have benefits in wound healing and in treatment of rough skin.

Crystal structure of human mono-phosphorylated ERK1 at Tyr204.

Extracellular signal-regulated kinase (ERK) is a member of the MAP kinase family, and can regulate several cellular responses. The isoforms ERK1 and ERK2 have markedly similar amino acid sequences, but exhibit distinctive physiological functions. As well as ERK2, ERK1 was auto- and mono-phosphorylated at Tyr204 in the activation loop during Escherichia coli production, resulting in basal level activity, approximately 500-fold less compared with fully-active ERK1 dual-phosphorylated at Thr202 and Tyr204. Crystal structure demonstrated that the mono-phosphorylated ERK1 kinase possessed a novel conformation distinguishable from the un-phosphorylated (inactive) and the dual-phosphorylated (full-active) forms. The characteristic structural features in both the C-helix and the activation loop likely contribute to the basal activity of the mono-phosphorylated ERK1. The structural dissection of ERK1 compared to ERK2 suggests that the structural differences in the D-motif binding site and in the backside binding site are putative targets for development of selective ERK1/ERK2 inhibitors.