Skin codelivery of contact sensitizers and neurokinin-1 receptor antagonists integrated in microneedle arrays suppresses allergic contact dermatitis.

BACKGROUND: Allergic contact dermatitis (CD) is a chronic inflammatory skin disease caused by type 1 biased adaptive immunity for which there is an unmet need for antigen (Ag)-specific immunotherapies. Exposure to skin sensitizers stimulates secretion of the proinflammatory neuropeptides substance P and hemokinin 1, which signal via the neurokinin-1 receptor (NK1R) to promote the innate and adaptive immune responses of CD. Accordingly, mice lacking the NK1R develop impaired CD. Nonetheless, the role and therapeutic opportunities of targeting the NK1R in CD remain to be elucidated. OBJECTIVE: We sought to develop an Ag-specific immunosuppressive approach to treat CD by skin codelivery of hapten and NK1R antagonists integrated in dissolvable microneedle arrays (MNA). METHODS: In vivo mouse models of contact hypersensitivity and ex vivo models of human skin were used to delineate the effects and mechanisms of NK1R signaling and the immunosuppressive effects of the contact sensitizer NK1R antagonist MNA in CD. RESULTS: We demonstrated in mice that CD requires NK1R signaling by substance P and hemokinin 1. Specific deletion of the NK1R in keratinocytes and dendritic cells, but not in mast cells, prevented CD. Skin codelivery of hapten or Ag MNA inhibited neuropeptide-mediated skin inflammation in mouse and human skin, promoted deletion of Ag-specific effector T cells, and increased regulatory T cells, which prevented CD onset and relapses locally and systemically in an Ag-specific manner. CONCLUSIONS: Immunoregulation by engineering localized skin neuroimmune networks can be used to treat cutaneous diseases that like CD are caused by type 1 immunity.