Loss of Epidermal Evi/Wls Results in a Phenotype Resembling Psoriasiform Dermatitis

The study investigated the role of Wnt proteins in skin homeostasis by creating a conditional knockout of the Wnt cargo receptor Evi in mice. Mice lacking Evi expression in the epidermis exhibited hair loss during the first hair cycle, reddish skin, and impaired skin barrier function, resembling human psoriasis. The absence of Evi led to up-regulation of inflammation-associated genes and immune cell infiltration, including an age-dependent depletion of dendritic epidermal T cells and infiltration of γδ low T cells. These findings highlighted the essential role of Wnt secretion in maintaining normal skin homeostasis and immune cell recruitment.