Increase of epidermal proteins involved in the maintenance of skin barrier in human skin keratinocytes by moisturizing cosmetics.
Author: Samara Eberlin
Published at: October 27, 2014
28th IFSCC Congress (International Federation of Societies of Cosmetic Chemists); Paris, October 27-28, 2014.
Eberlin S, Polettini AJ, Costa A, Pereira AFC, Weisz LTM, Lage R.
Numerous biochemical reactions take place during the transition from the basal layer to the stratum corneum (SC), including the synthesis of specific basal (K5 and K14) and suprabasal (K1 and K10) keratins and cornified envelope-associated proteins in the keratinocytes. The epidermal differentiation complex (EDC) is constituted through cross-linking of involucrin, envoplakin, loricrin, profilaggrin, among others, on the intracellular surface of the plasma membrane in the upper spinous and granular layers of the epidermis. Studies have shown that variation in EDC results in the pathogenesis of at least three common skin disorders: ichthyosis vulgaris (IC), atopic dermatitis (AD), and psoriasis. In this study, we evaluated the effects of moisturizing lotions and antiperspirants on the production of envelope proteins filaggrin, involucrin, and loricrin, and keratins 10 and 14, using an in vitro model of human keratinocytes. The test products, including antiperspirant 1 (At-1), antiperspirant 2 (At-2), lotion 1 (Lo-1), and lotion 2 (Lo-2), were composed of different compounds from vegetable origin. Incubation of keratinocyte cultures with Lo-1, Lo-2, At-1, and At-2 promoted significant increases in the synthesis of envelope proteins filaggrin, involucrin, and loricrin. Considering that more pronounced biological effects were elicited by Lo-2 treatment, which significantly increased the levels of all envelope proteins, we also evaluated its ability to stimulate the production of basal (K14) and suprabasal (K10) keratins. A sharp rise in the production of keratin 10 was elicited by Lo-2, reaching up to 2.4-fold in relation to the control group. Similarly, Lo-2 also provided an increase of up to 54% in the synthesis of keratin 14. The water content of the SC and skin surface lipids are important factors in the appearance and function of the skin barrier. Traditional moisturizing ingredients are known to decelerate the loss of skin humidity, increase hydration of the SC, and improve the physical and chemical properties of the skin surface, making it moist, smooth, and soft. However, most of the products claimed for skin moisturizing produce an immediate and transient effect, which is not enough to relieve the discomfort caused by eczema. Thus, optimized skin care cosmetics should be developed to supply a proper moisturizing effect while also being capable of balancing the synthesis of skin barrier proteins. In this study, we evaluated the ability of moisturizing cosmetics to promote the production of proteins involved in SC turnover and integrity. Moisturizing lotions and antiperspirants increased the levels of all proteins evaluated. The results indicate a biological activity of these skin care products in promoting cellular hydration and skin barrier integrity.