965 The importance of CD206+ macrophages in squaric acid dibutylester-induced hair cycle activation

Squaric acid dibutylester (SADBE) is a topical sensitizer useful for contact immunotherapy of alopecia areata (AA). However, the mechanism action not fully understood. Macrophages activated by cytokines such as IL-1β or IL-4 are reported to promote hair growth. M2 macrophages induced IL-4, IL-10 IL-13 exhibit anti-inflammatory function and produce several growth factors that induce tissue repair, proposed contribute regrowth. C3H/HeJ mice spontaneously develop AA were applied with SADBE showed regrowth on day 28. To evaluate effect in simpler experimental system, young without shaved SADBE. In this setting, was observed 14, histologically, anagen hairs at least 5. Immunohistochemical examinations revealed intense infiltration expressing CD206, typical marker macrophages, dermal tissues. Quantitative image analysis infiltrating cells divided into three subsets: CD206+F4/80–, CD206+F4/80+, CD206–F4/80+. These subsets formed three-layered structure, CD206+/F4/80+ localized around papilla. Likewise, repeated application correlation increase CD206+ macrophages. Our observations suggest induces M2-like papilla 3 triggers cycle progression early AA, macrophage depletion intradermal injection clodronate liposomes inhibited SADBE-induced suggesting indispensable. Therefore, CD206+macrophages play important role promotion via dermatitis have potential be novel therapeutic target AA.