1588 Molecular characterization of early stage hidradenitis suppurativa via spatial transcriptomics

Hidradenitis suppurativa (HS) is a complex inflammatory skin disorder that causes painful superficial nodules and deep abscesses as well as draining dermal tunnels in the advanced stages. It was recently claimed that the dermal tunnels, a distinguishing feature of moderate-to-severe HS (Hurley stages II and III), are a source of inflammatory mediators. However, more research is needed to understand the role of dermal epithelial linings in the pathophysiology of early-stage HS. We compared the intradermal epithelial cells of HS patients in the early stage with the non-inflamed dermal wall of epidermal cysts using spatial transcriptomics, a cutting-edge technology that provides both spatial information of cells and their gene expression patterns. Epithelial cells in HS significantly increased the genes related to ‘response to bacterium’, such as DEFB1, DEFB4B, and S100A7-9, implicating the role of bacteria in the disease. In addition, the increase of IL-4R and IL-13RA1 suggests an increase in the sensitivity of Th2 cytokine on the epidermis and in dermal-infiltrating cells. Interestingly, genes associated with B lymphocytes, such as immunoglobulins, were found to be highly expressed in HS infiltrating cells, which was confirmed by CD20 staining in the dermis. Taken together, these data suggested that “epidermis-derived” inflammatory cytokines and infiltrated B cells might play a role in the pathogenesis of early HS.