Calorie Restriction Up-regulates Islet PD-L1 Signaling and Decreases the Risk of Auto-immune Diabetes Onset in NOD Mice.

Abstract

Type 1 diabetes (T1D) is an autoimmune disease where beta cells are destroyed by cytotoxic T cells. Calorie restriction (CR) enhances glucose homeostasis and promotes beta cell longevity and was used as therapeutic strategy for T1D prior to the discovery of insulin. However, a significant knowledge gap remains regarding its effects on beta cells during the pathogenesis of auto-immunity. We demonstrate that CR enhances glucose homeostasis, reduces beta cell load, and delays T1D onset in NOD mice. CR induced a largely post-mitotic beta cell state marked by selective loss of beta cell identity markers, reduced DNA damage and beta cell senescence, and increased PD-L1 within the islet microenvironment. This beta cell phenotype correlates with anti-inflammatory and exhausted immune cell states in the NOD islet. Together, these findings indicate that CR improves glucose homeostasis and remodels the islet microenvironment to pro-mote beta cell longevity via a pro-tolerogenic immune microenvironment that reduces the risk for autoimmune diabetes.