Frontal Fibrosing Alopecia: An Example of Disrupted Aryl Hydrocarbon Receptor-Mediated Immunological Homeostasis in the Skin?

The review hypothesized that frontal fibrosing alopecia (FFA) might result from excessive facial photoprotection, disrupting immunological homeostasis mediated by the aryl hydrocarbon receptor (AHR)-kynurenine pathway (KP) axis, leading to immune privilege collapse at the hair follicle's bulge area. It suggested that a certain level of sun exposure is necessary to maintain skin immunological balance, and the rising incidence of FFA might be linked to environmental factors, including the use of sunscreens and facial care products. The study highlighted the complex interplay between AHR activity, immune regulation, and hair follicle health, proposing that disruptions in these pathways could lead to the immune-mediated destruction of hair follicles seen in FFA.