One-year topical stabilized retinol treatment improves photodamaged skin in a double-blind, vehicle-controlled trial.

BACKGROUND: Retinol, a precursor of retinoic acid, has great potentials as a topical anti-aging molecule; however, only a handful of clinical investigations have been published to date. OBJECTIVE: This study aimed to assess the efficacy and safety of 0.1% stabilized retinol on photodamaged skin during a one-year treatment. METHODS: The investigation included two 52-week, double-blind, vehicle-controlled studies. In the main study, 62 subjects applied either a stabilized retinol formulation or its vehicle to the full face. A second exploratory study evaluated histological/histochemical markers in 12 subjects after 52 weeks of either retinol or vehicle use on contralateral dorsal forearms. RESULTS: The retinol group showed significant photodamage improvement over vehicle at all timepoints during the study. After 52 weeks, retinol had improved crow's feet fine lines by 44%, and mottled pigmentation by 84%, with over 50% of subjects showing +2 grades of improvement in many parameters. Additionally, at week 52, histochemical data confirmed the clinical results, showing increased expression of type I procollagen, hyaluronan, and Ki67 as compared to vehicle. CONCLUSION: This study confirms that a stabilized retinol (0.1%) formulation can significantly improve the signs of photoaging, and improvements in photodamage continue with prolonged use.

Galvanic zinc-copper microparticles inhibit melanogenesis via multiple pigmentary pathways.

The endogenous electrical field of human skin plays an important role in many skin functions. However, the biological effects and mechanism of action of externally applied electrical stimulation on skin remain unclear. Recent study showed that galvanic zinc-copper microparticles produce electrical stimulation and reduce inflammatory and immune responses in intact skin, suggesting the important role of electrical stimulation in non-wounded skin. The objective of this study is to investigate the biological effect of galvanic zinc-copper microparticles on skin pigmentation. Our findings showed that galvanic zinc-copper microparticles inhibited melanogenesis in a human melanoma cell line (MNT-1), human keratinocytes and melanoma cells co-cultures, and in pigmented epidermal equivalents. Treatment of galvanic zinc-copper microparticles inhibited melanogenesis by reducing the promoter transactivation of tyrosinase and tyrosinase-related protein-1 in human melanoma cells. In a co-culture Transwell system of keratinocytes and melanoma cells, galvanic zinc-copper microparticles reduced melanin production via downregulation of endothelin-1 secretion from keratinocytes and reduced tyrosinase gene expression in melanoma cells. In addition, exposure of pigmented epidermal equivalents to galvanic zinc-copper microparticles resulted in reduced melanin deposition. In conclusion, our data demonstrated for the first time that galvanic zinc-copper microparticles reduced melanogenesis in melanoma cells and melanin deposition in pigmented epidermal equivalents by affecting multiple pigmentary pathways.

A melanocortin receptor 1 and 5 antagonist inhibits sebaceous gland differentiation and the production of sebum-specific lipids.

BACKGROUND: The melanocortin receptor-5 (MC5R) is present in human sebaceous glands, where it is expressed in differentiated sebocytes only. The targeted disruption of MC5R in mice resulted in reduced sebaceous lipid production and a severe defect in water repulsion. OBJECTIVE: To investigate the physiological function of MC5R in human sebaceous glands. METHODS: A novel MC1R and MC5R antagonist (JNJ-10229570) was used to treat primary human sebaceous cells or human skins grafted onto severe combined immunodeficient (SCID) mice. Transcription profiling, lipid analyses, and histological and immunohistochemical staining were used to analyze the effect of MC5R inhibition on sebaceous gland differentiation and sebum production. RESULTS: JNJ-10229570 dose dependently inhibited the production of sebaceous lipids in cultured primary human sebocytes. Topical treatment with JNJ-10229570 of human skins transplanted onto SCID mice resulted in a marked decrease in sebum-specific lipid production, sebaceous gland's size and the expression of the sebaceous differentiation marker epithelial-membrane antigen (EMA). Treatment with flutamide, a known inhibitor of sebum production, gave similar results, validating the human skin/SCID mouse experimental system for sebaceous secretion studies. CONCLUSION: Our data suggest that antagonists of MC1R and MC5R could be effective sebum suppressive agents and might have a potential for the treatment of acne and other sebaceous gland pathologies.

Melanocortin-5 receptor and sebogenesis.

The melanocortins (α-MSH, ß-MSH, γ-MSH, and ACTH) bind to the melanocortin receptors and signal through increases in cyclic adenosine monophosphate to induce biological effects. The melanocortin MC(5) and MC(1) receptors are expressed in human sebaceous glands, which produce sebum, a lipid mixture of squalene, wax esters, triglycerides, cholesterol esters, and free fatty acids that is secreted onto the skin. Excessive sebum production is one of the major factors in the pathogenesis of acne. The expression of melanocortin MC(5) receptor has been associated with sebocyte differentiation and sebum production. Sebaceous lipids are down-regulated in melanocortin MC(5) receptor-deficient mice, consistent with the observation that α-MSH acts as a sebotropic hormone in rodents. These findings, which suggest that melanocortins stimulate sebaceous lipid production through the MC(5) receptor, led to our search for MC(5) receptor antagonists as potential sebum-suppressive agents. As predicted, an antagonist was shown to inhibit sebocyte differentiation in vitro, and to reduce sebum production in human skin transplanted onto immunodeficient mice. The melanocortin MC(5) receptor antagonists may prove to be clinically useful for the treatment of sebaceous disorders with excessive sebum production, such as acne.

Immuno-histochemical evaluation of solar lentigines: The association of KGF/KGFR and other factors with lesion development.

BACKGROUND: Solar lentigines (SLs) are macular hyperpigmented lesions associated with sun exposure and age. Histopathologically, SLs are defined by a hyperpigmented basal layer and elongated rete ridges. The molecular mechanisms involved in the formation and the development of SLs are not completely understood. Our earlier data show that keratinocyte growth factor (KGF) induces hyperpigmentary lesions with histological resemblance to SLs. OBJECTIVE: To investigate the association of KGF/KGF receptor (KGFR) and other pigmentary genes with the progression of SL development. To better understand the possible role of KGF in the pathology of SLs. METHODS: Archived human skin biopsies (24 SLs and 14 healthy skins) were studied using immunohistochemistry for KGF/KGFR, proliferation marker Ki67, stem cell marker keratin-15 (K15), tyrosinase (TYR), stem cell factor (SCF), and protease-activated receptor-2 (PAR-2). RESULTS: An increase in TYR-positive cells and expression was found throughout SL progression, as compared to normal skin. The levels of KGF, KGFR, SCF, Ki67 and PAR-2 varied during SL progression. Ki67, K15 and KGF/KGFR were significantly upregulated at early-mid SL stages. The latest-stage SLs expressed the lowest levels of KGF, KGFR, SCF, Ki67 and PAR-2. CONCLUSIONS: The upregulation of KGF/KGFR might induce the formation of rete ridges and hyperpigmentation. The reduced levels of all examined proteins (except TYR and K15) suggest a possible inactive status (dormancy or quiescence) of advanced lesions.

Extracts from Glycine max (soybean) induce elastin synthesis and inhibit elastase activity.

Elastic fibres are essential extracellular matrix components of the skin, contributing to its resilience and elasticity. In the course of skin ageing, elastin synthesis is reduced, and elastase activity is accelerated, resulting in skin sagging and reduced skin elasticity. Our studies show that non-denatured Glycine max (soybean) extracts induced elastin promoter activity, inhibited elastase activity and protected elastic fibres from degradation by exogenous elastases in vitro. Mouse and swine skins topically treated with soybean extracts showed enhanced elastic fibre network and increased desmosine content. Elastin expression was also augmented in human skin transplanted onto SCID mice in response to soy treatment. These data suggest that non-denatured soybean extracts may be used as skin care agents to reduce the signs of skin ageing.