A novel humanized mouse model closely mimics human vitiligo

Summary: Abstract Body: Vitiligo is a complex depigmentation disorder resulting from epidermal melanocyte apoptosis and premature senescence of the epidermal pigmentary unit, mainly driven by oxidative damage and CD8+ T cell-produced IFN-γ. Current vitiligo mouse replicate this complexity insufficiently. The aim of the study is to develop the first “humanized” mouse model that optimally replicates human vitiligo. Healthy human dark skin xenotransplants on SCID/beige mice were oxidatively stressed (topical catalase inhibitor plus H2O2-NaN3). Autologous PBMCs were pre-stimulated to induce a vitiligo-typical Th1 phenotype, while autologous melanocytes were cultured with menadione, MART1, gp100, and tyrosinase. Th1-skewed PBMCs and pre-treated melanocytes were co-cultured and injected intradermally into xenotransplants. Moreover, mice were intravenously treated with IgG4 from vitiligo patients and HSP70. Key vitiligo characteristics and the model’s response to established vitiligo therapeutics were assessed. Vitiligo-like depigmented lesions developed in 80% of xenotransplants. Quantitative immunohistomorphometry demonstrated depletion of epidermal melanocyte numbers and markers (Melan-A, gp100, c-KIT) and decreased melanin content, elevation of keratinocyte-derived key cytokines (IFN-γ/Krt10, IFN-α/Krt10, IL-15/Krt10, IL-18/Krt10), enhanced GP100/NKG2D/MICA and CD8/NKG2D/gp100 interactions, along with elevated CD11c+ and pDC cell numbers. The number of epidermal TRM was also increased. Lesional keratinocytes and melanocytes showed elevated senescence markers (increased P16INK4A, SIRT1, p-S6), alongside reduced antioxidant and mitochondrial markers (e.g., ,NRF2, MTCO1, Porin/VDAC, PGC1α,) preceding depigmentation. Tacrolimus and Opzelura effectively promoted repigmentation in experimentally induced vitiligo lesions, achieving 30% and 70% repigmentation, respectively. In this preclinical model, vitiligo pathogenesis can be interrogated and candidate vitiligo therapeutics tested under clinically relevant conditions in vivo. Aviad Keren¹, Assaf Zeltzer¹, Ralf Paus^{2, 3}, Amos Gilhar¹ 1. Technion Israel Institute of Technology, Haifa, Haifa District, Israel. 2. University of Miami Miller School of Medicine, Miami, FL, United States. 3. CUTANEON, Hamburg, Germany. Adaptive and Auto-Immunity