Immune tolerance is executed partly by Foxp3+regulatory T (Treg) cells, which suppress autoreactive T cells. In autoimmune type 1 diabetes (T1D) impaired tolerance promotes destruction of insulin-producing β-cells. The development of autoantigen-specific vaccination strategies for Foxp3+Treg-induction and prevention of islet autoimmunity in patients is still in its infancy. Here, using human haematopoietic stem cell-engrafted NSG-HLA-DQ8 transgenic mice, we provide direct evidence for human autoantigen-specific Foxp3+Treg-induction in vivo. We identify HLA-DQ8-restricted insulin-specific CD4+T cells and demonstrate efficient human insulin-specific Foxp3+Treg-induction upon subimmunogenic vaccination with strong agonistic insulin mimetopes in vivo. Induced human Tregs are stable, show increased expression of Treg signature genes such as Foxp3, CTLA4, IL-2Rα and TIGIT and can efficiently suppress effector T cells. Such Foxp3+Treg-induction does not trigger any effector T cells. These T1D vaccine candidates could therefore represent an expedient improvement in the challenge to induce human Foxp3+Tregs and to develop novel precision medicines for prevention of islet autoimmunity in children at risk of T1D.

Summary Obesity and type-2 diabetes are associated with tissue-inflammation and metabolic defects in fat depots. Foxp3+regulatory T(Treg) cells mediate T-cell tolerance, thereby controlling tissue inflammation. However, the molecular underpinnings how environmental stimuli interlink T-cell tolerance with adipose tissue function remain largely unknown. Here, we report that cold exposure or beta3-adrenergic receptor (ADRB3) stimulation induces T-cell tolerance in vitro and in murine and humanized models. Tolerance induction was verified by CD4+T-cell-proteomes revealing higher protein expression of Foxp3 regulatory networks. Specifically, Ragulator-interacting protein C17orf59, which limits mTORC1 activity, was upregulated by either ADRB3-stimulation or cold-exposure, and therefore might enhance Treg induction. By loss and gain-of-function studies, including Treg depletion and transfers in vivo, we demonstrated that a T-cell-specific Stat6/Pten axis links cold-exposure or ADRB3 stimulation with Foxp3+Treg induction and adipose tissue function. Our findings open new avenues in understanding tissue-specific T-cell tolerance and the design of precision concepts toward personalized immune-metabolic health.