Expression of hypothalamic-pituitary-adrenal axis in common skin diseases: evidence of its association with stress-related disease activity.

Hypothalamic-pituitary-adrenal (HPA) axis hormones and their receptors expressed in the skin are known to function locally, but how these hormones affect the maintenance of skin homeostasis or the pathogenesis of skin diseases is not fully understood. We comprehensively reviewed the distribution and function of the central and peripheral HPA axis in various stress-related skin diseases. Previous studies have shown altered expression of central and peripheral HPA axis hormones in chronic inflammatory skin diseases and skin tumours, and that hyper-active lesional HPA axis hormones may negatively feedback to the central HPA axis and interact with some cytokines and neuropeptides, leading to symptom deterioration. This provides an evidence-based understanding of the expression of the central and peripheral HPA axis in common skin diseases and its association with disease activity.