Deficiency of Nuclear Factor-κB c-Rel Accelerates the Development of Autoimmune Diabetes in NOD Mice

The nuclear factor-κB protein c-Rel plays a critical role in controlling autoimmunity. c-Rel–deficient mice are resistant to streptozotocin-induced diabetes, a drug-induced model of autoimmune diabetes. We generated c-Rel–deficient NOD mice to examine the role of c-Rel in the development of spontaneous autoimmune diabetes. We found that both CD4(+) and CD8(+) T cells from c-Rel–deficient NOD mice showed significantly decreased T-cell receptor–induced IL-2, IFN-γ, and GM-CSF expression. Despite compromised T-cell function, c-Rel deficiency dramatically accelerated insulitis and hyperglycemia in NOD mice along with a substantial reduction in T-regulatory (Treg) cell numbers. Supplementation of isogenic c-Rel–competent Treg cells from prediabetic NOD mice reversed the accelerated diabetes development in c-Rel–deficient NOD mice. The results suggest that c-Rel–dependent Treg cell function is critical in suppressing early-onset autoimmune diabetogenesis in NOD mice. This study provides a novel natural system to study autoimmune diabetes pathogenesis and reveals a previously unknown c-Rel–dependent mechanistic difference between chemically induced and spontaneous diabetogenesis. The study also reveals a unique protective role of c-Rel in autoimmune diabetes, which is distinct from other T-cell–dependent autoimmune diseases such as arthritis and experimental autoimmune encephalomyelitis, where c-Rel promotes autoimmunity.