The role of the mineralocorticoid receptor in skin.

The mineralocorticoid receptor (MR) plays a pivotal role in skin homeostasis, inflammation, and repair, interacting closely with the glucocorticoid receptor (GR) to regulate various physiological and pathological processes. Dysregulation of MR signaling has been implicated in several skin disorders, including psoriasis, atopic dermatitis, and impaired wound healing. Furthermore, studies have shown that patients with primary hyperaldosteronism exhibit epidermal hyperplasia, impaired differentiation, increased immune cell infiltrates, and elevated pro-inflammatory cytokines due to MR overactivation. Pharmacological studies demonstrate that MR antagonists can mitigate glucocorticoid-induced skin barrier dysfunction, epidermal atrophy, and delayed wound healing. Additionally, skin sodium storage and water conservation mechanisms are emerging as key factors in systemic fluid balance and blood pressure regulation, with skin glycosaminoglycans (GAGs) thought to serve as sodium reservoirs. Mouse models of psoriasis further reveal how the disrupted skin barrier activates systemic protective mechanisms, including water retention processes in the skin that can lead to increased blood pressure; psoriasis in humans is also associated with hypertension. These findings and additional data are discussed in this review and underscore the dual role of cutaneous MR in both maintaining epidermal integrity and contributing to inflammatory skin disorders, and potentially hypertension, when dysregulated. Targeting MR signaling pathways may offer novel therapeutic strategies for skin diseases while enhancing our understanding of the skin's role in systemic homeostasis.