scRNA-seq of human vitiligo reveals complex networks of subclinical immune activation and a role for CCR5 in Treg function

Vitiligo is an autoimmune skin disease characterized by the targeted destruction of melanocytes by T cells. Cytokine signaling between keratinocytes and T cells results in CD8(+) T cell infiltration of vitiligo lesions, but the full scope of signals required to coordinate autoimmune responses is not completely understood. We performed single-cell RNA sequencing on affected and unaffected skin from patients with vitiligo, as well as healthy controls, to define the role of each cell type in coordinating autoimmunity during disease progression. We confirmed that type 1 cytokine signaling occupied a central role in disease, but we also found that this pathway was used by regulatory T cells (T-regs) to restrain disease progression in nonlesional skin. We determined that CCL5-CCR5 signaling served as a chemokine circuit between effector CD8(+) T cells and Tregs, and mechanistic studies in a mouse model of vitiligo revealed that CCR5 expression on T-regs was required to suppress disease in vivo but not in vitro. CCR5 was not required for T-reg recruitment to skin but appeared to facilitate T-reg function by properly positioning these cells within the skin. Our data provide critical insights into the pathogenesis of vitiligo and uncover potential opportunities for therapeutic interventions.

Automated summary

The study revealed that cytokine signaling plays a critical role in the progression of vitiligo, while regulatory T cells also participate in inhibiting disease development. The CCL5-CCR5 signaling pathway acts as a chemokine circuit between effector CD8(+) T cells and Tregs.