Squaric Acid Dibutylester, Used in Alopecia Areata Immunotherapy, Promotes Innate Immune-Driven Hair Growth with CD206+ Macrophage Accumulation in the Dermis

The study investigates the mechanism of hair growth induced by squaric acid dibutyl ester (SADBE) in alopecia areata (AA) treatment. Using C3H/HeJ mice and healthy young mice models, researchers found that SADBE application leads to significant hair growth, associated with the accumulation of macrophages in the dermis, particularly CD206+ macrophages. These macrophages form a layered structure and are crucial for hair growth, as their depletion inhibits the process. The study concludes that innate immune cells, especially macrophages, are key to SADBE-induced hair growth, suggesting potential new strategies for AA treatment by targeting these cells.