Assistant Research Fellow National Taiwan University Hospital National Taiwan University Hospital, Taiwan
Abstract: Allergic contact dermatitis (ACD) has been utilized as a therapeutic approach for alopecia areata, an autoimmune hair loss condition driven by T cell-mediated Th1 responses. Despite its clinical use, the underlying mechanisms by which ACD stimulates hair regrowth remain unclear. In this study, we demonstrate that ACD induces early anagen entry in wild-type mice, suggesting a direct role in promoting hair growth. Hair follicle stem cells (HFSCs), critical for hair regeneration, are regulated by dynamic signals from the local microenvironment. We hypothesize that macrophages recruited during the ACD response mediate HFSC activation through specific signaling pathways, thereby initiating a new hair cycle.
To test this hypothesis, we employed diphenylcyclopropenone (DPCP) as an allergen to establish a robust ACD-induced hair growth model. Transcriptomic analysis using bulk RNA sequencing (RNA-seq) revealed significant changes in gene expression associated with immune cell recruitment and activation in the skin. Further, we utilized immune cell depletion strategies to dissect the role of macrophages in this process. Our findings highlight macrophages as key mediators in ACD-driven hair regeneration, shedding light on the crosstalk between immune responses and HFSC activation. This study not only advances our understanding of ACD-induced hair regrowth but also opens new avenues for developing macrophage-targeted therapies for alopecia.
