Dermal elastic fibres are extracellular matrix protein complexes produced by fibroblasts and involved in skin elasticity. Elastin fibres decrease with age as a result of reduced synthesis and increased degradation, resulting in skin sagging and reduced skin elasticity. In this study, we show that retinol (ROL), known to enhance dermal collagen production, is also enhancing elastin fibre formation. ROL induced elastin gene expression and elastin fibre formation in cultured human dermal fibroblasts. Topical treatment of cultured human skin explants with a low dose (0.04%) of ROL increased mRNA and protein levels of tropoelastin and of fibrillin-1, an elastin accessory protein, as documented by QPCR and immunohistochemistry staining. Luna staining confirmed the increased elastin fibre network in the ROL-treated skin explants, as compared with untreated controls. These data demonstrate that ROL exerts its anti-ageing benefits not only via enhanced epidermal proliferation and increased collagen production, but also through an increase in elastin production and assembly.

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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.Keywords: elastase -elastin -Glycine max -non-denaturedskin ageing -soy -soybean The resilience of the skin depends on the functionality of its elastic fibres. Elastic fibre formation is a multi-step process engaging a variety of factors. It involves tropoelastin synthesis and secretion, and its deposition on microfibrils followed by cross-linking into mature fibres (1-4). In addition, growth factors, such as TGF-b, IGF-1 and IL-1b induce elastin expression (5-9), while TNF-a and EGF inhibit elastin synthesis (10,11). Loss of elastic fibres is a major contributing factor of skin ageing (12,13). Chronological ageing, UV exposure and inflammation, all increase the release of elastases, and in particular of human neutrophil and human macrophage elastases (HLE and HME) (14-16). These elastases degrade elastic fibres, resulting in skin sagging and wrinkling (14,(16)(17)(18)(19)(20)(21). Indeed, the inhibition of fibroblast-derived elastase protects skin's elastic fibres and reduces wrinkle formation in rodents (19,22,23).Our previous studies showed that treatments with nondenatured soybean extracts and with the soybean derived protease inhibitors (STI and BBI) result in skin lightening (24-26) and in delayed hair growth (26). During the clinical studies, we noticed an improvement in skin elasticity of soy-treated subjects (27). Here we report that soybean extracts enhance the elastic fibres in skin by inducing elastin promoter activity and by inhibiting elastases.To understand the mechanism of action of the soybean extracts, we generated two elastin promoterreporter constructs, and their activities were examined in transiently transfected H9c2 cells (rat cardiac myoblasts). A 2.2 kb promoter-reporter construct (Elp2.2, Fig. S1a) showed lower basal promoter activity than a shorter, 0.5 kb construct (Elp0.5, Fig. S1a,b), because of negative cis-acting elements between )2260 and )495 (28). Treatment of Elp2.2 transfected cells with soybean extracts resulted in a dose-dependent increase in elastin promoter activity (Fig. 1a). No induction was observed with the Elp0.5 promoter (not shown), suggesting a possible de-repression, via regulatory elements located between )2260 and )495 ...

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