Target cell expression of suppressor of cytokine signaling-1 prevents diabetes in the NOD mouse

Although lymphocyte infiltration and islet destruction are hallmarks of diabetes, the mechanisms of beta-cell destruction are not fully understood. One issue that remains unresolved is whether cytokines play a direct role in beta-cell death. We investigated whether beta-cell cytokine signaling contributes to autoimmune type 1 diabetes. We demonstrated that NOD mice harboring beta-cells expressing the suppressor of cytokine signaling-1 (SOCS-1), an inhibitor of Janus kinase/signal transducers and activators of transcription (JAK/ STAT) signaling, have a markedly reduced incidence of diabetes. Similar to their non-transgenic (Tg) litter-mates, SOCS-1-Tg mice develop insulitis and their splenocytes transfer disease to NODscid recipients. Disease protection correlates with suppression of cytokine-induced STAT-1 phosphorylation in SOCS-1-expressing beta-cells and with a reduced sensitivity of these cells to destruction by diabetogenic cells in vivo. Interestingly, lymphocytes recruited to the pancreas of SOCS-1-Tg mice transferred diabetes to NODscid recipients with a reduced efficiency, suggesting that the pancreatic environment in SOCS-1-Tg mice does not support the maintenance of functionally differentiated T-cells. These results suggest that cytokines contribute to the development of type 1 diabetes by acting directly on the target beta-cell. Importantly, given that the SOCS-1 expressing mouse maintain normal blood glucose levels throughout life, this study also showed that SOCS-1 expression by beta-cells can represent a promising strategy to prevent type 1 diabetes.