Dipeptidyl peptidase IV (DPP4) is a serine peptidase which cleaves the last 2 amino acids at N-terminus of substrates with penultimate proline or Alanine. The majority of mammalian skin fibroblast express this molecule on their surface and pharmacological inhibition of DPP4 in splinted wounds results in decreased deposition of scar tissue. Other cell types of the skin have been reported to express this molecule and it is hypothesized to participate in many physiological and pathological processes. So far the expression pattern, regulation and exact functions of DPP4 in the skin during homeostasis and wound healing remain unknown. We investigate DPP4 in the context of healing of large wounds, which are able to regenerate hair follicles. In comparison, small wounds do not show this wound induced hair follicle neogenesis (WIHN). For WHIN, Wnt-Signals from the dermis and later from the epidermis need to be produced in a window of time of approximately 9 to 15 days post wounding (pw). Our studies show a downregulation of DPP4/Dpp4 upon wounding at the beginning of the inflammatory phase and at the beginning of activationd of WIHN (pw9). Interestingly the center of wounds show reduced numbers of DPP4 positive cells compared to the wound margins, where normally no WIHN takes place. Detailed Investigation of cutaneous cell populations show a differential Regulation of DPP4 in dermal, epithelial and immune cells. Inhibition of DPP4 around pw9 interestingly increases the number of WIHN hair follicles and the Expression of Wnt Targets and ligands in the Skin. Together our observations support the notion of DPP4 being a inhibitory factor for hair follicle regeneration

ESDR362 - Not just a cell marker: DPP4 modulates regeneration of hair follicles in large wounds

50th Annual Meeting of the European Society for Dermatological Research. VIRTUAL MEETING