Circulating miR-375 as a Biomarker of β-Cell Death and Diabetes in Mice

Type 1 diabetes is a progressive autoimmune disease that is largely silent in its initial stages. Yet, sensitive methods for detection of β-cell death and prediction and prevention of diabetes are lacking. Micro-RNAs (miRNAs) have been found at high concentrations in body fluids. Here in this study we sought to determine whether an islet enriched miRNA, miR-375, is a suitable blood marker to detect β-cell death and predict diabetes in mice. We measured miR-375 levels by quantitative RT-PCR in plasma samples of streptozotocin (STZ)-treated C57BL/6 mice and nonobese diabetic (NOD) mice. We also measured miR-375 levels in media samples of cytokine- or STZ-treated islets in the presence or absence of cell-death inhibitors. High-dose STZ administration dramatically increased circulating miR-375 levels, prior to the onset of hyperglycemia. Similarly, in the NOD mouse model of autoimmune diabetes, circulating miR-375 levels were significantly increased 2 weeks before diabetes onset. Moreover, cytokine- and STZ-i...