Bio-derived hydroxystearic acid ameliorates skin age spots and conspicuous pores.

INTRODUCTION: We report on the preparation and efficacy of 10-hydroxystearic acid (HSA) that improves facial age spots and conspicuous pores. METHODS: The hydration of oleic acid into HSA was catalyzed by the oleate hydratase from Escherichia coli. Following treatment with HSA, collagen type I and type III was assessed in primary human dermal fibroblasts together with collagen type III, p53 protein levels and sunburn cells (SBC) after UVB irradiation (1 J cm-2 ) by immunohistochemistry on human ex vivo skin. UVB-induced expression of matrix metalloprotease-1 (MMP-1) was determined from full thickness skin by RT-qPCR. Modification of the fibroblast secretome by HSA was studied by mass-spectrometry-based proteomics. In a full-face, double blind, vehicle-controlled trial HSA was assessed for its effects on conspicuous facial pore size and degree of pigmentation of age spots in Caucasian women over an 8-week period. RESULTS: HSA was obtained in enantiomeric pure, high yield (≥80%). Collagen type I and type III levels were dose-dependently increased (96% and 244%; P < 0.01) in vitro and collagen type III in ex vivo skin by +57% (P < 0.01) by HSA. HSA also inhibited UVB-induced MMP-1 gene expression (83%; P < 0.01) and mitigated SBC induction (-34% vs. vehicle control) and reduced significantly UV-induced p53 up-regulation (-46% vs. vehicle control; P < 0.01) in irradiated skin. HSA modified the fibroblast secretome with significant increases in proteins associated with the WNT pathway that could reduce melanogenesis and proteins that could modify dermal fibroblast activity and keratinocyte differentiation to account for the alleviation of conspicuous pores. Docking studies in silico and EC50 determination in reporter gene assays (EC50 5.5 × 10-6  M) identified HSA as a peroxisomal proliferator activated receptor-α (PPARα) agonist. Clinically, HSA showed a statistically significant decrease of surface and volume of skin pores (P < 0.05) after 8 weeks of application and age spots became significantly less pigmented than the surrounding skin (contrast, P < 0.05) after 4 weeks. CONCLUSION: HSA acts as a PPARα agonist to reduce the signs of age spots and conspicuous pores by significantly modulating the expression of p53, SBC, MMP-1 and collagen together with major changes in secreted proteins that modify keratinocyte, melanocyte and fibroblast cell behavior.

INTRODUCTION: voici notre rapport sur la préparation et l'efficacité de l'acide 10-hydroxystéarique (AHS) qui atténue les taches de vieillesse faciale et améliore l'apparence des pores. MÉTHODES: l'hydratation de l'acide oléique en AHS a été catalysée par l'hydratase d'oléate à partir de l'Escherichia coli. Après un traitement par AHS, les collagènes de type I et de type III ont été analysés dans des fibroblastes dermiques humains primaires, ainsi que le taux de collagène de type III et de protéine p53, et les cellules provenant de coups de soleil (sunburn cells, SBC) après irradiation par UVB (1 J cm−2 ) par immunohistochimie sur de la peau humaine ex vivo. L'expression de la matrice métalloprotéase-1 (MMP-1) induite par les UVB a été déterminée à partir d'un échantillon de pleine épaisseur de peau par RT-qPCR. La modification du sécrétome des fibroblastes par l'AHS a été étudiée par analyse protéomique basée sur une spectrométrie de masse. Dans une étude du visage entier, en double aveugle, contrôlée par excipient, l'AHS a été évaluée pour ses effets sur la taille des pores apparents du visage et sur le degré de pigmentation de taches de vieillesse chez des femmes de race blanche sur une période de 8 semaines. RÉSULTATS: l'AHS a été obtenu à un haut rendement, énantiomérique pur (≥80 %). Les taux de collagènes de type I et de type III ont augmenté in vitro en fonction de la dose (96 % et 244 %; P < 0.01) et le collagène de type III dans de la peau ex vivo de +57 % (P < 0.01) lors d'un traitement par AHS. L'AHS a également inhibé l'expression génique MMP-1 induite par les UVB (83%; P < 0.01) et a atténuée l'induction des SBC (−34 % par rapport à l'excipient), et a réduit significativement la régulation à la hausse du p53 induite par les UV (−46% par rapport à l'excipient; P < 0.01) sur de la peau irradiée. L'AHS a modifié le sécrétome des fibroblastes avec des augmentations significatives des protéines associées à la voie WNT qui pouvaient réduire la mélanogenèse et des protéines qui pouvaient modifier l'activité des fibroblastes dermiques et la différenciation des kératinocytes pour une atténuation des pores apparents. Des études de docking in silico et la détermination de l'EC50 dans les dosages des gènes rapporteurs (EC50 5.5 × 9 10−6 M) ont identifié l'AHS comme un agoniste du récepteur-α activé par les proliférateurs de peroxysomes (peroxisomal proliferator activated receptor-α, PPARα). Cliniquement, l'AHS a permis une diminution statistiquement significative de la surface et du volume des pores de la peau (P < 0.05) après 8 semaines d'application, et les taches de vieillesse sont devenues significativement moins pigmentées par rapport à la peau environnante (contraste, P < 0,05) après 4 semaines. CONCLUSION: l'AHS agit comme un agoniste du PPARα pour réduire les signes de taches de vieillesse et l'apparence des pores par une modulation significative de l'expression de la protéine p53, des SBC, de la MMP-1 et du collagène avec des changements majeurs dans les protéines sécrétées qui modifient le comportement cellulaire des kératinocytes, des mélanocytes et des fibroblastes.

Protective effects of an extract of the freshwater microalga Scenedesmus rubescens on UV-irradiated skin cells.

BACKGROUND: Skin ageing results from intrinsic but also extrinsic factors of which UV irradiation is a main cause. It is hence of interest to have means to protect skin from UV irradiation-induced damage. We selected an extract of the freshwater microalga Scenedesmus rubescens and assessed its potential to protect skin from photoageing caused by UV irradiation. METHODS: Skin cells in vitro and ex vivo were analysed for markers of UV irradiation-induced photodamage such as decreased viability, decreased collagen content, hyperpigmentation and sunburn cells. RESULTS: We found that a dry extract of the microalga Scenedesmus rubescens was able to suppress cellular signs of ageing induced by UV irradiation. It enhanced dermal fibroblast viability, rescued dermal collagen content, inhibited the formation of sunburn cells and inhibited tyrosinase activity. CONCLUSION: An extract of Scenedesmus rubescens showed broad activity against markers of UV irradiation-induced cutaneous ageing. It may therefore be used as a preventive or regenerative agent for anti-ageing strategies.

The effects of benzylsulfonyl-D-Ser-homoPhe-(4-amidino-benzylamide), a dual plasmin and urokinase inhibitor, on facial skin barrier function in subjects with sensitive skin.

OBJECTIVE: The aim of this study was to optimize the synthesis of the plasmin and urokinase (uPA) inhibitor benzylsulfonyl-D-Ser-homoPhe-(4-amidino-benzylamide) (BSFAB), to characterize its activity and mechanism of action and to assess its use to improve stratum corneum (SC) barrier function. METHODS: Peptide coupling methods were used to synthesize BSFAB, and high-performance liquid chromatography-mass spectrometry (HPLC-MS) together with 1 H- and 13 C-nuclear magnetic resonance spectroscopy (NMR) were applied to clarify its structure and determine its purity. Its binding mode was determined by docking studies to the catalytic domains of plasmin and uPA. Inhibition constants (Ki ) were determined by enzyme kinetic studies, and the effect of BSFAB on plasmin, uPA and transglutaminase 1 expression was evaluated in non-cytokine and cytokine-stimulated keratinocytes. A vehicle-controlled clinical study on SC barrier function was conducted on facial skin of subjects with self-perceived sensitive skin. RESULTS: BSFAB was synthesized with high purity (97.3%). In silico studies indicated that the amidine moiety of BSFAB was anchored in the S1 pocket of both enzymes by binding to Asp189, Ser190 and Gly219, whereas the backbone of the D-Ser residue makes an anti-parallel ß-sheet interaction with Gly216. BSFAB was shown to be an effective inhibitor of plasmin and uPA with Ki values of 29 and 25 nM, respectively. BSFAB also inhibited keratinocyte-secreted protease activities in basal (plasmin inhibition 37.7%, P < 0.05 and uPA inhibition 96.6%, P < 0.01) and cytokine-induced conditions (plasmin inhibition 41.1%, P < 0.05 and uPA inhibition 97.0%, P < 0.001) and stimulated the gene expression of transglutaminase 1 in cytokine-stimulated keratinocytes (approximately 4.5 times increased expression, P < 0.01). Clinically, BSFAB was shown to improve SC barrier integrity (P < 0.02 on day 29) and subjective improvements in the perception of healthy skin (P < 0.05 on day 28). CONCLUSION: BSFAB binds as a reversible competitive inhibitor to the active sites of plasmin and uPA. Additionally, BSFAB positively improved keratinocyte differentiation gene expression (transglutaminase 1). These effects were translated into improvements in SC barrier integrity clinically in subjects with dry and sensitive skin and improved their perception of having a healthy skin condition.

A fundamental investigation into aspects of the physiology and biochemistry of the stratum corneum in subjects with sensitive skin.

BACKGROUND: Sensitive skin is a poorly understood skin condition. Defects in stratum corneum (SC) barrier function and/or extrasensory neuronal networks in the epidermis are believed to be involved in the problem. OBJECTIVES: This study aimed to unravel the relationships between bleomycin hydrolase (BH) and calpain-1 (C-1), pyrrolidone carboxylic acid (PCA) levels, corneocyte maturation, transglutaminase (TG) and plasmin activities on the cheeks of subjects with sensitive skin. METHODS: Forty-eight female Caucasian subjects, Fitzpatrick skin phototypes II-III, with self-perceived sensitive facial skin, were assessed and underwent a capsaicin reactivity test. Expert grading of skin condition was conducted as well as the measurement of transepidermal water loss (TEWL), skin capacitance, SC cohesion and SC integrity. BH, C-1 and plasmin activities were measured as well as PCA levels, plasmin and TG activity. Differential Nile red and involucrin immunostaining was performed to assess corneocyte maturation and size. RESULTS: About 52% of the subjects reacted to capsaicin. There were no significant differences between the capsaicin-sensitive and non-capsaicin-sensitive subjects with reference to skin grading, TEWL, skin capacitance and SC cohesion. PCA levels and BH activity were lowest in the capsaicin-sensitive panel (P < 0.05) and were correlated in non-capsaicin-sensitive subjects (r = 0.72). The activity of TG was significantly lower (48%) in the capsaicin-sensitive subjects (P < 0.001) and their corneocytes were less mature and smaller (P ≤ 0.05). SC was estimated to be thinner (6.87 ± 0.28 vs. 8.68 ± 0.26 µm; P = 0.001) in the capsaicin-sensitive subjects with a corresponding shorter SC path length (83.2 ± 4.4 µm and 113.1 ± 4.5 µm; P = 0.001). CONCLUSIONS: Despite the physiological similarities between the two groups of sensitive skin subjects, differences in their biochemistry were clearly evident. Lower levels of PCA, BH and TG activities together with a greater number of smaller and immature corneocytes indicate inferior SC maturation in the capsaicin-sensitive subjects. The reduced maturation of corneocytes and thinner SC likely contributes to a greater penetration of capsaicin and the associated increased skin sensitivity.

Development of an in vitro efficacy test for self-tanning formulations.

In the last few years, the desire to acquire a tan without sunbathing has grown. In response, many cosmetic companies have produced self-tanning preparations. However, to optimize these formulations, a suitable model to assess the colour induced on the skin remains to be developed. We have developed an in vitro method using a synthetic skin in order to study the efficacy of self-tanning formulations. The in vitro test was then used to study the influence of cosmetic ingredients upon the colour induced by erythrulose- or dihydroxyacetone-containing formulations. Finally, an in vivo study allowed us to relate the results obtained in vitro with those found on human skin. The results show that this in vitro test system is a reliable tool to predict the efficacy of self-tanning products.