Mechanisms by which psychologic stress alters cutaneous permeability barrier homeostasis and stratum corneum integrity

Although many skin disorders, including psoriasis and atopic dermatitis, are adversely affected by psychologic stress (PS), the pathophysiologic link between PS and disease expression remains unclear. Recent studies demonstrated PS-induced alterations in permeability barrier homeostasis, mediated by increased endogenous glucocorticoids. Here, we assessed the mechanisms by which PS alters stratum corneum (SC) function. Insomniac psychologic stress (IPS) altered both barrier homeostasis and SC integrity. IPS decreased epidermal cell proliferation, impaired epidermal differentiation, and decreased the density and size of corneodesmosomes (CD), which was linked to degradation of CD proteins (e.g., desmoglein1). Barrier compromise was linked to decreased production and secretion of lamellar bodies (LB), which in turn could be attributed to a decrease in de novo synthesis of epidermal lipids. Topical physiologic lipids (equimolar cholesterol, ceramides, and free fatty acids) normalized both barrier homeostasis and SC integrity in IPS mice, further evidence that lipid deficiency accounted for these functional abnormalities. Thus, PS inhibition of epidermal lipid synthesis results in decreased LB formation and secretion, as well as decreased CD, compromising both permeability barrier homeostasis and SC integrity. These studies suggest that topical treatment with epidermal physiologic lipids could be beneficial in stress-induced, barrier-associated dermatoses, such as psoriasis and atopic dermatitis.