Amino Carbonylation of Epidermal Basement Membrane Inhibits Epidermal Cell Function and Is Suppressed by Methylparaben

This study investigated the effect of amino carbonylation (Maillard reaction) on the function of the epidermal basement membrane (BM) by analyzing epidermal cell proliferation and keratinization and stratum corneum barrier function using a three-dimensional human epidermal BM model treated with glyceraldehyde. Intracellular ATP levels were lower in cells cultured on amino-carbonylated epidermal BM as compared to those in normal epidermal BM (control). Moreover, trans-epidermal water loss was increased by culturing on amino-carbonylated BM relative to the control; this was accompanied by downregulation of filaggrin, transglutaminase-1, and serine palmitoyltransferase 2 mRNA levels. p-Hydroxybenzoic acid methyl ester (methylparaben) abrogated the decrease in ATP production and filaggrin expression in human keratinocytes induced by amino-carbonylated collagen. Thus, amino carbonylation of the epidermal BM inhibits moisture retention, keratinization, and ceramide synthesis and disrupts the barrier function of the stratum corneum. These findings suggest that methylparaben can be an effective additive to cosmetics for improving epidermal function that is compromised by amino carbonylation.