Unacylated ghrelin (UnAG) induces oxidative stress resistance in a glucose intolerance mouse model and peripheral artery disease by restoring endothelial cell miR-126 expression.

Reactive oxygen species (ROS) are crucial in long-term diabetes complications, including peripheral artery disease (PAD). In this study, we have investigated the potential clinical impact of unacylated ghrelin (UnAG) in a glucose intolerance and PAD mouse model. We demonstrate that UnAG is able to protect skeletal muscle and endothelial cells (ECs) from ROS imbalance in hind limb ischemia subjected ob/ob mice. This effect translates into reductions in hind limb functional impairment. We show that UnAG rescues sirtuin 1 (SIRT1) activity and superoxide-dismutase-2 (SOD-2) expression in ECs. This leads to SIRT1-mediated p53 and histone 3 (H3K56) deacetylation and results in reduced EC senescence in vivo. We demonstrate, using siRNA technology, that SIRT1 is also crucial for SOD-2 expression. UnAG also renews miR-126 expression, resulting in the post-transcriptional regulation of vascular cell adhesion molecule 1 (VCAM-1) expression and a reduced number of infiltrating inflammatory cells in vivo. Loss-of-function experiments that target miR-126 demonstrate that miR-126 also controls SIRT1 and SOD-2 expression, thus confirming its role in driving UnAG-mediated EC protection against ROS imbalance. These results indicate that UnAG protects vessels from ROS imbalance in ob/ob mice by rescuing miR-126 expression thus emphasizing its potential clinical impact in avoiding limb loss in PAD.