High-affinity self-reactive thymocytes are purged in the thymus, and residual self-reactive T cells, which are detectable in healthy subjects, are controlled by peripheral tolerance mechanisms. Breakdown in these mechanisms results in autoimmune disease, but antigen-specific therapy to augment natural mechanisms can prevent this. We aimed to determine when antigen-specific therapy is most effective. Islet autoantigens, proinsulin (PI), and islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP) were expressed in the antigen-presenting cells (APCs) of autoimmune diabetes-prone nonobese diabetic (NOD) mice in a temporally controlled manner. PI expression from gestation until weaning was sufficient to completely protect NOD mice from diabetes, insulitis, and development of insulin autoantibodies. Insulin-specific T cells were significantly diminished, were naive, and did not express IFN-γ when challenged. This long-lasting effect from a brief period of treatment suggests that autoreactive T cells are not produced subsequently. We tracked IGRP206–214-specific CD8+ T cells in NOD mice expressing IGRP in APCs. When IGRP was expressed only until weaning, IGRP206–214-specific CD8+ T cells were not detected later in life. Thus, anti-islet autoimmunity is determined during early life, and autoreactive T cells are not generated in later life. Bolstering tolerance to islet antigens in the perinatal period is sufficient to impart lasting protection from diabetes.
Gaurang Jhala, Jonathan Chee, Prerak M. Trivedi, Claudia Selck, Esteban N. Gurzov, Kate L. Graham, Helen E. Thomas, Thomas W.H. Kay, Balasubramanian Krishnamurthy
Temporal proinsulin expression and spontaneous diabetes development in TIP mice.