The Importance of CD206+ Macrophages in Squaric Acid Dibutylester-Induced Hair Cycle Activation

The study investigates the role of CD206+ macrophages in hair growth induced by squaric acid dibutylester (SADBE), a treatment for alopecia areata (AA). In experiments with C3H/HeJ mice, SADBE application led to hair regrowth, with macrophages expressing CD206, a marker of M2 macrophages, infiltrating the dermal tissues. These macrophages, particularly the CD206+/F4/80+ subset, were found around the dermal papilla and are crucial for hair cycle progression. Inhibition of these macrophages in shaved mice without AA prevented SADBE-induced hair growth, highlighting their essential role. The findings suggest that CD206+ macrophages are key in promoting hair growth through SADBE-induced contact dermatitis and could be a novel therapeutic target for AA.