Regulatory γδ T cells protect human scalp hair follicles from alopecia areata in vivo and represent potential therapeutic target

Summary: Abstract Body: Recently, we showed that IFN-γ-secreting, NKG2D+/Vδ1+ γδT cells can induce alopecia areata (AA). However, the role of immunosuppressive Foxp3+ γδTregs in AA remains unexplored. The aim of the study is to clarify whether Foxp3+ γδTregs can prevent or treat human AA. Autologous Foxp3+γδTregs were generated by pre-stimulating PBMCs with IL-2, TGF-β1, IL-15, and zoledronate. Recognized γδTreg markers and secretory activities were confirmed by FACSAria analysis and ELISA (see below). These γδTregs were either co-cultured with stressed human scalp hair follicles (HFs) ex vivo or were injected intradermally into experimentally induced AA lesions in human skin xenotransplants on SCID/beige mice in vivo. The number of Foxp3+ γδTregs was increased around lesional AA HFs. When these γδTregs (CD3+, TCRVδ2+, FOXP3+, ICOS+, CTLA4+; TGFb1- and IL-10-secreting) were co-cultured with stressed, MICA/B-overexpressing human scalp HFs ex vivo in the presence of AA-pathogenic NKG2D+/CD8+ T cells, γδTregs mitigated CD8+T cell-induced HF immune privilege collapse and hair growth inhibition ex vivo by secreting IL-10 and TGF-β1. In vivo, intradermal injection of peripheral blood-derived human autologous γδTregs significantly reduced the development of experimentally induced AA lesions in human scalp skin xenotransplants on SCID/beige mice, reduced lymphocytic HF infiltration, and restored HF immune privilege. We provide the first evidence that γδTregs are both preventive and therapeutic in human AA and thus as a potent autoimmunity-protective immune cells. This invites the use of autologous γδTregs as novel cell-based therapeutics in future AA management. Aviad Keren¹, Nyra Goldstein¹, Assaf Zeltzer¹, Marta Bertolini², Ralf Paus^{3, 4}, Amos Gilhar¹ 1. Technion Israel Institute of Technology, Haifa, Haifa District, Israel. 2. Monasterium Laboratory Skin & Hair Research Solutions GmbH, Münster, NRW, Germany. 3. University of Miami Miller School of Medicine, Miami, FL, United States. 4. CUTANEON, Hamburg, Germany. Adaptive and Auto-Immunity