The synergistic effects of UVA and DHT in the senescence of dermal papilla cells in hair loss

Summary: Abstract Body: Androgenetic alopecia (AGA) is one of the most common forms of hair loss, and recent studies suggest that dihydrotestosterone (DHT)-induced senescence of dermal papilla cells (DPCs) plays a crucial role in its pathogenesis. Clinically, we have observed overlap between areas exposed to ultraviolet (UV) radiation and regions affected by androgenetic hair loss. However, the link between UVA radiation, which penetrates deep into the dermis, and the onset of AGA remains unclear. In this study, we investigate the role of UVA in exacerbating DHT-induced hair loss, with a focus on the potential activation of cellular senescence pathways. We utilized an AGA mouse model and combined it with UVA irradiation to examine the role of UVA in delaying DHT-induced hair growth. To further investigate the mechanisms of the interaction between DHT and UVA, we isolated human dermal papilla cells (DPCs) and performed transcriptome sequencing analysis. UVA accelerates DHT-Induced hair growth delay in AGA mouse model. UVA intensifies DHT-induced cellular senescence in hDPCs. This process is associated with the activation of mTOR pathway. However, rapamycin alleviates this UVA- and DHT-induced cellular senescence by modulating autophagy dysfunction. Furthermore, rapamycin effectively reverses UVA-exacerbated DHT-induced hair loss in AGA mouse model. UVA exposure can affect autophagy levels via mTOR pathway, enhancing DHT-induced cellular senescence in DPCs. Xiuzu Song¹, Dongfan Wei¹ 1. Hangzhou third people's hospital, Hangzhou, China. UV Biology/Injury and Non-melanoma Cancers