Together with keratinocytes (KCs) and the dense network of Langerhans cells (LCs), the epidermis is an ideal portal for vaccine delivery. Pattern recognition receptor (PRR) agonists, in particular polyinosinic-polycytidylic acid [p(I:C)], are promising adjuvant candidates for therapeutic vaccination to generate protective T cell immunity. As the efficacy of PRR agonists in skin cells has predominantly been tested in vitro, we have applied a human skin explant model and administered p(I:C) onto barrier-disrupted human epidermis to study the expression and activation of dsRNA-sensing PRRs in LCs and KCs in their natural environment.

Epidermal delivery of polyinosinic-polycytidylic acid in a human skin explant model activates the MDA5/MAVS pathway in Langerhans cells