Tapinarof ameliorates rejection in a human skin grafted model of face transplantation

Abstract

Abstract T cell mediated immune rejection is the primary barrier to broader implementation of face transplants (vascularized composite allografts, VCA). Our bulk and single cell transcriptional profiling of human face transplant rejection demonstrated that VCA rejection is an INFγ driven cytotoxic process with unique induction of skin specific immunoregulatory pathways including SOCS1, KIR3DL2, and LY9. Tapinarof is a novel small-molecule topical aryl hydrocarbon receptor agonist and antioxidant that is effective in treating psoriasis and atopic dermatitis. Patients who cleared on once a day topical tapinarof remained clear for an average of four months after discontinuation, suggesting it has durable immunoregulatory effects in skin. We modeled VCA by grafting NSG mice with freshly excised, living, immunologically intact adult human skin. Once healed, 5×10 6allogeneic PBMCs from a second unrelated human donor were infused via tail vein. The inflamed skin mimicked VCA rejection after 21 days, with grafts showing epidermal injury, T cell infiltration, dyskeratosis, and genetic signatures of cytotoxicity, antigen presentation, and INFγ signaling. Topical tapinarof ameliorated this inflammation, with fewer T cells and reduced antigen-specific T cell activation. Induction of immunoregulatory pathways was also noted, including upregulation of SOCS1 signaling, TREX1 mediated reductions in cytosolic nucleotide sensing, and IL1RN inhibition of IL-1 mediated inflammation. Tapinarof could be a novel therapy for VCA rejection that does not require systemic immune suppression. Our results suggest that strengthening immunoregulatory networks in skin is a viable approach to combat inflammation and promote tolerance in VCA rejection. NIH T32 Training Grant 2T32AR007098-47 Dept. of Dermatology, Harvard Medical School RT170025 (P.I. Rachael A. Clark) Department of Defense - congressionally Directed Medical Research Programs; "T cells and Rejection in Vascularized Composite Allografts).