25 Hydroxyvitamin D 1 α-Hydroxylase Is Required for Optimal Epidermal Differentiation and Permeability Barrier Homeostasis

The study focused on the importance of 25 Hydroxyvitamin D 1 α-Hydroxylase (1αOHase) in skin health, specifically in epidermal differentiation and skin barrier homeostasis. Mice lacking the 1αOHase gene (1αOHase−/−) showed decreased levels of key differentiation markers (involucrin, filaggrin, and loricrin) and experienced a delayed recovery of skin barrier function after disruption, as indicated by increased transepidermal water loss (TEWL). This was associated with impaired calcium gradient formation in the epidermis and reduced lamellar body secretion. The study concluded that 1αOHase and its product, presumably 1,25-dihydroxyvitamin D (1,25(OH)2D), are crucial for maintaining normal keratinocyte differentiation and barrier recovery post-disruption. The research did not mention alopecia in the 1αOHase−/− mice. The findings imply that endogenous production of 1,25(OH)2D is significant for skin health and that deficiencies in 1αOHase could lead to more severe skin pathologies in humans or mice.