Hair Follicles Are Critical Modulators of Skin Barrier Function

This study investigates the role of hair follicles in skin barrier function by examining the effects of deleting the ABCA12 gene, which is linked to severe skin barrier disease. The research reveals that while deletion of ABCA12 in interfollicular epidermis (IFE) stem cells leads to temporary ichthyotic symptoms, its deletion in hair follicle stem cells results in chronic effects. The study identifies four key concepts: the upper hair follicle (uHF) forms a functional barrier, barrier disruption in the uHF leads to increased barrier protein expression in the epidermis, ABCA12 deletion in the uHF affects desquamation and sebum release, and uHF cells can migrate into the epidermis to alter skin phenotype. These processes are partly driven by the upregulation of Il17a. The findings highlight hair follicles as crucial regulators of skin barrier function.