Multiple Mechanisms Contribute to Robust Type 1 Diabetes Protection in Nfkbid- Overexpressing NOD Mice.

We previously reported that transgenic overexpression of Nfkbid in NOD mice led to robust type 1 diabetes protection associated with enhanced negative selection of autoreactive T cells and expansion of regulatory T cells (Tregs) with increased suppressive capacity. The goal of this study was to further identify cellular and molecular mechanisms underlying strong protection from type 1 diabetes imbued by overexpressing Nfkbid. Transcript analysis of Tregs from Nfkbid-overexpressing NOD mice show enrichment of cellular replication pathways. Effector T cells from Nfkbid-overexpressing NOD mice have increased indicators of activation-induced exhaustion in pancreatic lymph nodes and islets. This trait is intrinsic to Nfkbid-overexpressing T cells, as ex vivo anti-CD3 stimulation of splenic-derived T cells can reproduce this phenotype. Anti-PD-1 administration breaks the diabetes protective effect. Furthermore, we found that Nfkbid-overexpressing dendritic cells, but not B cells, have an enhanced capacity to stimulate proliferation of diabetogenic AI4 CD8+ T cells (with wild-type levels of Nfkbid). Conversely, B cells, but not dendritic cells, drive enhanced de novo conversion of regulatory T cells from effector T cells. Together, this study documents additional mechanisms that likely synergize to contribute to the diabetes-protective effects of Nfkbid overexpression. Understanding the mechanisms underlying protection from Nfkbid overexpression may lead to novel therapeutic avenues.