Low environmental humidity induces synthesis and release of cortisol in an epidermal organotypic culture system

Dry environmental conditions induce a variety of skin pathologies and a recent report indicating that cortisol synthesis in epidermis was increased during wound healing led us to hypothesize that environmental dryness might induce increased cortisol secretion in epidermis. Therefore, we incubated a skin equivalent model under dry (relative humidity: less than 10%) and humid (relative humidity: approximately 100%) conditions for 48hours and evaluated cortisol secretion and mRNA levels of cortisol-synthesizing enzyme (steroid 11-hydroxylase, CYP11B1) and IL-1. Cortisol secretion was increased threefold, and CYP11B1 and IL-1 mRNAs were increased 38-fold and sixfold, respectively, in the dry condition versus the humid condition. Occlusion with a water-impermeable plastic membrane partially blocked the increases in cortisol secretion and CYP11B1 and IL-1 mRNA expression in the dry condition. Thus, environmental dryness might induce increased cortisol secretion in epidermis of diseased skin characterized by epidermal barrier dysfunction, potentially influencing mental state and systemic physiology.