Cosmetic benefits of a novel biomimetic lamellar formulation containing niacinamide in healthy females with oily, blemish-prone skin in a randomized proof-of-concept study.

OBJECTIVE: A randomized study was designed to evaluate the potential cosmetic benefit of a biomimetic, niacinamide-containing moisturizing cream in oily, blemish-prone skin. METHODS: Healthy adult women with oily, blemish-prone skin were randomized to one of three treatment groups: test, control, or positive control. In the test group, subjects used the test product (containing 4% niacinamide), plus the standard cleanser (Simple® Kind to Skin Moisturizing Facial Wash). In the control group, subjects received no moisturizer but used the standard cleanser. In the positive control group, subjects used Vivatinell Acnecinamide® Gel Cream (containing 4% niacinamide) as a moisturizer and Neutrogena Visibly Clear® Spot Clearing Facial Wash (containing 2% salicylic acid) as a cleanser. The positive control regimen was included to provide a comparison for estimates of effect size. The primary objective was to evaluate skin moisturization as a change from baseline in corneometer values at 8 h for the test regimen vs. the control regimen. Analysis of covariance was applied for the primary efficacy analysis. RESULTS: A total of 132 subjects were randomized with 44 included in each treatment group. A significant difference was observed in the primary endpoint for the test regimen compared with the control regimen (least-squares mean difference [95% CI]: 3.12 [0.68, 5.56], P = 0.0128). A trend was observed in favour of the positive control regimen compared with the control regimen. Secondary measurements of moisturization supported the primary efficacy outcome. Assessment of blemishes showed a significant difference between the test regimen vs. the control regimen for change from baseline in mean total blemish count at Week 8 (least-squares mean difference [95% CI]: -1.80 [-3.41, -0.19], P = 0.0290). No statistical comparisons between the positive control group and the test group were performed. CONCLUSION: This study provides proof-of-concept evidence that a novel lamellar lipid moisturizer containing niacinamide, in combination with a standard cleanser, can help moisturize the skin and provide an overall improvement in the complexion appearance of people with blemish-prone skin. STUDY REGISTRATION: NCT03093181.

OBJECTIF: Une étude randomisée a été conçue pour évaluer le bénéfice cosmétique potentiel d'une crème hydratante biomimétique contenant du niacinamide sur une peau grasse sujette aux imperfections. MÉTHODES: Des femmes adultes en bonne santé, à peau grasse sujette aux imperfections, ont été randomisées dans l'un des trois groupes de traitement : test, témoin ou témoin positif. Dans le groupe test, les sujets ont utilisé le produit testé (contenant 4 % de niacinamide), plus le nettoyant standard (Nettoyant visage Simple® doux pour la peau). Dans le groupe témoin, les sujets n'ont reçu aucune crème hydratante mais ont utilisé le nettoyant standard. Dans le groupe témoin positif, les sujets ont utilisé le gel crème Vivatinell Acnecinamide® (contenant 4 % de niacinamide) comme crème hydratante et le nettoyant visage pour réduire les imperfections Neutrogena Visibly Clear® (contenant 2 % d'acide salicylique) comme nettoyant. Le schéma de traitement du groupe témoin positif était inclus pour fournir une comparaison des estimations de la taille de l'effet. L'objectif principal était d'évaluer l'hydratation de la peau par le changement par rapport à la référence des valeurs du cornéomètre à 8 h pour le schéma de traitement testé par rapport au schéma de traitement témoin. Une analyse de covariance a été appliquée pour l'analyse de l'efficacité primaire. RÉSULTATS: Un total de 132 sujets ont été randomisés, dont 44 inclus dans chaque groupe de traitement. Une différence significative a été observée dans le critère d'évaluation principal en faveur du schéma de traitement testé par rapport au schéma de traitement témoin (différence moyenne des moindres carrés [IC à 95 %] : 3,12 [0,68, 5,56], P = 0,0128). Une tendance a été observée en faveur du schéma de traitement témoin positif par rapport au schéma de traitement témoin. Les mesures secondaires de l'hydratation ont appuyé le résultat principal d'efficacité. L'évaluation des imperfections a montré une différence significative entre le schéma de traitement testé par rapport au schéma de traitement témoin en ce qui concerne le changement par rapport à la référence dans le nombre moyen total d'imperfections à la semaine 8 (différence moyenne des moindres carrés [IC à 95 %] : _1,80 [_3,41, _0,19], P = 0,0290). Aucune comparaison statistique entre le groupe témoin positif et le groupe test n'a été réalisée. CONCLUSION: Cette étude fournit des éléments de preuve de concept qu'une nouvelle crème hydratante lipidique lamellaire à base de niacinamide, en association avec un nettoyant standard, peut permettre d'hydrater la peau et fournir une amélioration globale de l'aspect du teint chez des personnes dont la peau est sujette aux imperfections. Numéro d'enregistrement de l'étude : NCT03093181.

Cosmetic benefit of a biomimetic lamellar cream formulation on barrier function or the appearance of fine lines and wrinkles in randomized proof-of-concept clinical studies.

OBJECTIVE: Two studies were designed to evaluate the potential cosmetic benefit of a biomimetic, niacinamide-containing moisturizing cream for the first time in humans. METHODS: In both studies, healthy women were randomized to use two treatments, one for the left side of the body and one for the right, from three options: the test cream, a positive control or no treatment (use of standard cleanser only). Treatments were applied twice daily for 4 weeks to the face and forearms (Study 1) or the face only (Study 2). Instrumental and clinical skin assessments were performed by trained technicians. Study 1 involved tape stripping and a 5-day no-treatment ('regression') period at the end of the 4 weeks. Independent lay graders were asked to grade the skin texture of subjects in Study 2 from high-resolution photographs. RESULTS: In Study 1 (n = 66), the test cream significantly decreased the transepidermal water loss (TEWL) values on the forearm, and in the cheek area of the face, relative to baseline and compared to no treatment, and increased skin Corneometer values. The improvements were partially retained during a subsequent 5-day period of no treatment. Increases in TEWL values on skin subjected to tape stripping were significantly lower after 4 weeks of using the test cream compared to no treatment. In Study 2 (n = 72 subjects with visible signs of ageing), there was a favourable trend in the change from baseline of a skin roughness parameter, Ra , for the test cream compared to no treatment. There were statistically significant improvements in the Fitzpatrick wrinkle score compared to no treatment, decreases in TEWL and increased Corneometer values and Cutometer values (R5 elasticity parameter). Grading of high-resolution images failed to detect the improvements in skin texture (defined as pores, smoothness and unevenness) for the test cream vs. no treatment. No treatment-related serious or severe adverse events were reported. CONCLUSION: Twice daily application of the test cream over 4 weeks had beneficial effects on skin barrier function, moisturization, wrinkle dimensions and elasticity compared to no treatment. These studies provide proof-of-concept evidence and highlight the cosmetic benefit of the biomimetic lamellar cream formulation. STUDY REGISTRATION: NCT03216265, NCT03180645.

OBJECTIF: Deux études ont été conçues pour évaluer pour la première fois chez l'être humain l'éventuel bénéfice cosmétique d'une crème hydratante biomimétique contenant de la niacinamide. MÉTHODES: Dans les deux études, des femmes en bonne santé ont été randomisées pour utiliser deux traitements, un pour le côté gauche du corps et un pour le côté droit, choisis entre trois options : la crème testée, un contrôle positif ou aucun traitement (utilisation d'un nettoyant standard uniquement). Les traitements ont été appliqués deux fois par jour pendant 4 semaines sur le visage et les avant-bras (Étude 1) ou seulement sur le visage (Étude 2). Des évaluations instrumentales et cliniques de la peau ont été effectuées par des techniciens qualifiés. L'étude 1 impliquait un stripping et une période de 5 jours sans traitement (« régression ¼) à la fin des 4 semaines. Il a été demandé à des évaluateurs profanes indépendants d'évaluer la texture de la peau des participantes dans l'Étude 2 à partir de photographies à haute résolution. RÉSULTATS: Dans l'Étude 1 (n = 66), la crème testée a diminué de manière significative les valeurs de la perte en eau transépidermique (transepidermal water loss, TEWL) au niveau de l'avant-bras, et au niveau de la joue, par rapport à la valeur de base, et par rapport au groupe sans aucun traitement, et a augmenté les valeurs des paramètres cutanés mesurés avec un cornéomètre. Les améliorations ont été partiellement conservées pendant une période ultérieure de 5 jours sans aucun traitement. Des augmentations des valeurs TEWL sur la peau exposée à un décollement d'un ruban adhésif étaient significativement plus faibles après 4 semaines d'utilisation de la crème testée par rapport à l'absence de traitement. Dans l'Étude 2 (n = 72 participantes avec des signes visibles de vieillissement), il y avait une tendance favorable au niveau de la variation par rapport à la valeur de base du paramètre relatif à la rugosité de la peau, Ra, pour la crème testée par rapport à l'absence de traitement. Il y a eu des améliorations statistiquement significatives du score de Fitzpatrick pour les rides par rapport à l'absence de traitement, des diminutions des valeurs TEWL et une augmentation des valeurs des paramètres mesurés avec un cornéomètre et des valeurs des paramètres mesurés avec un cutomètre (paramètre élasticité R5). L'évaluation des images à haute résolution n'a pas permis de détecter les améliorations de la texture de la peau (définie par les pores, la finesse et les irrégularités) pour la crème testée par rapport à l'absence de traitement. Aucun événement indésirable grave ou sévère lié au traitement n'a été rapporté. CONCLUSION: Une application deux fois par jour de la crème testée pendant 4 semaines a eu des effets bénéfiques sur la fonction barrière de la peau, l'hydratation, l'aspect des rides et l'élasticité par rapport à l'absence de traitement. Ces études fournissent des éléments de preuve de concept et soulignent les bienfaits cosmétiques de la formule lamellaire biomimétique de la crème. Numéro d'enregistrement de l'étude : NCT03216265, NCT03180645.

Transcriptional activation of the melanocyte-specific genes by the human homolog of the mouse Microphthalmia protein.

Mi protein encoded at the mouse microphthalmia (mi) locus is a transcription factor with a basic helix-loop-helix/leucine zipper structure. To assess the function of the human homolog of Mi protein, termed microphthalmia-associated transcription factor (MITF), we analyzed the effects of MITF on the promoter function of the mouse tyrosinase and tyrosinase-related protein 1 (TRP-1) genes. These two gene promoters are able to direct transcription preferentially in melanin-producing cells, and an enhancer element M box of 11 bp, containing a CATGTG motif, is conserved in both promoters. By transient expression assays, we have localized the cis-acting element of the tyrosinase gene responsible for pigment cell-specific expression to the proximal 82-bp region, which contains a CATGTG motif (positions -12 to -7) but lacks the M box (positions -107 to -97). We also provide evidence that the 82-bp region and the M box are involved in the transactivation of the tyrosinase promoter by MITF and that the M box is bound by MITF in vitro. Furthermore, MITF activated the TRP-1 gene promoter possibly through the M box (positions -44 to -34). These results suggest that MITF is a common factor regulating transcription of the pigment cell-specific genes.

Characterization of density-dependent regulation of the tyrosinase gene promoter: role of protein kinase C.

The rate-limiting step in melanogenesis is catalyzed by tyrosinase, a multifunctional enzyme encoded by the albino locus. We have previously reported that depletion of protein kinase C by long-term treatment of B16 mouse melanoma cells with phorbol dibutyrate (PDBu) prevented cell density-dependent melanogenesis. This was accompanied by a lack of induction of tyrosinase protein and mRNA. We report here the effect of PDBu on the functional activity of the mouse tyrosinase promoter by reporter gene assay and its effect on the binding of nuclear proteins from B16 cells to the "M-box" region of the mouse tyrosinase promoter. Short-term PDBu treatment of B16 cells transfected with a mouse tyrosinase promoter-luciferase construct resulted in increased reporter gene activity, while long-term PDBu treatment inhibited reporter gene activity. Using an oligonucleotide containing the M-box and its flanking residues in electrophoretic mobility shift assays, we found a density-dependent change in the pattern of DNA-protein complexes. One complex was found to be negatively regulated by long-term PDBu treatment. Competition experiments with various mutated oligonucleotides demonstrated that both the M-box and flanking residues are important for nuclear protein binding. The complex whose formation was inhibited by long-term PDBu treatment was shown to contain the basic helix-loop-helix leucine zipper protein microphthalmia-associated transcription factor (MITF). These results suggest that chronic PDBu treatment might inhibit tyrosinase expression (and subsequent melanogenesis) by affecting the amount or function of MITF.

Regulation of melanogenesis in B16 mouse melanoma cells by protein kinase C.

Melanogenesis is regulated by a variety of environmental and hormonal factors. In this study, we showed that protein kinase C (PKC) plays a major role in regulating melanogenesis in B16 mouse melanoma cells. Chronic treatment of B16 cells with phorbol dibutyrate resulted in a concentration-dependent loss of density-dependent induction of tyrosinase activity, which correlated positively with a concentration-dependent loss of PKC enzyme activity. In contrast, B16 clones overexpressing PKC alpha had increased tyrosinase activity. Different phorbol derivatives inhibited tyrosinase activity and depleted cellular PKC alpha in a manner that reflected their reported tumor-promoting activity. Western blotting analysis showed that phorbol dibutyrate decreased the amount of the brown locus gene product (TRP-1) by 50% and lowered the amount of the albino locus gene product (tyrosinase) to undetectable levels. None of the phorbol derivatives affected the level of the slaty locus protein (TRP-2). The decrease in tyrosinase and TRP-1 protein levels was found to be due to a decrease in the mRNA encoded by these genes. In addition to inhibiting the density-dependent increase in tyrosinase activity, phorbol dibutyrate inhibited some, but not all, of the 8-bromocyclic AMP-induced increase in tyrosinase activity. This was accompanied by a decrease in the amount of tyrosinase protein induced by 8-bromocyclic AMP. Although 8-bromocyclic AMP did not change the level of TRP-1, it did reverse the decrease in the amount of this protein induced by phorbol dibutyrate. The amount of TRP-2 was not altered by any of these agents. These data suggest that PKC regulates melanogenesis primarily by controlling the constitutive expression of tyrosinase and, to a lesser extent, TRP-1.

Variation in melanin content and composition in type V and VI photoexposed and photoprotected human skin: the dominant role of DHI.

A combination of techniques, including high-performance liquid chromatography (HPLC), spectrophotometric measurements, and a novel method for quantifying melanosome morphology, were applied to the analysis of melanin content and composition in highly pigmented (Fitzpatrick type V and VI) human skin. We found that total epidermal melanin content is significantly elevated in photoexposed type V and VI skin (approximately 1.6 x), while analysis of individual melanin components suggests that pheomelanin content increases only slightly, whereas 5,6-dihydroxyindole-2-carboxylic acid (DHICA)-eumelanin and to a greater extent 5,6-dihydroxyindole (DHI)-eumelanin content are both markedly elevated. Analysis of the relative composition of epidermal melanin in these subjects revealed that DHI-eumelanin is the largest single component (approximately 60-70%), followed by DHICA-eumelanin (25-35%), with pheomelanin being a relatively minor component (2-8%). Moreover, there was a comparative enrichment of DHI-eumelanin at photoexposed sites, with a corresponding decline in the relative contributions from DHICA-eumelanin and pheomelanin. There was also a good correlation and close agreement between the concentration of spheroidal melanosomes determined by morphological image analysis and the concentration of pheomelanin determined by a combination of HPLC and spectrophotometric analysis (r = 0.89, P < 0.02). This study demonstrates the usefulness of melanosome morphology analysis as a sensitive new method for the quantification of melanin composition in human skin. The data also suggest that DHI-eumelanin formation is the dominant pathway for melanin synthesis in heavily pigmented (Fitzpatrick V and VI) skin types in vivo, and is the favoured pathway when melanin production is increased in chronically photoexposed skin.