Extracellular Vesicles, Insulin Action and Exercise on Vascular Function in Type 2 Diabetes

PROJECT ABSTRACT Insulin resistance in the vasculature is often linked to obesity and type 2 diabetes (T2D). This occurs prior to metabolic derangement as evidenced by endothelial dysfunction that, in turn, contributes to the rises in blood pressure and glucose. However, the mechanism by which vascular dysfunction occurs throughout the progression from obesity to T2D is unknown. A better understanding of the mechanisms responsible for differences in vascular function between people with obesity and T2D compared to lean healthy controls can provide critical mechanistic understandings into disease progression as well as potentially identify novel therapeutic targets. Extracellular vesicles (EVs) are produced by cells in the body that carry bioactive substances in the blood to modulate signaling is distant tissues. Based on our preliminary work, not only does insulin promote greater clearance of EVs, but the reduction relates to metabolic insulin sensitivity, arterial compliance and fuel utilization. Consistent with this, we have seen that EVs from healthy controls promote vasodilation under insulin stimulation in contrast to people with obesity that blunt this action via potential miRNA differences. Herein, we propose overall that insulin acts on extracellular vesicles (EVs) to influence vascular insulin sensitivity. We hypothesize that insulin will 1) promote EV uptake; 2) activate EV cargo (e.g., insulin signaling/miRNA/eNOS) to 3) foster vasoreactivity of blood vessels in response to insulin. In this longitudinal prospective trial, 40-70y T2D patients will be matched-paired to adults with lean to obese BMIs with normal glucose tolerance (NGT). Then people with obesity and T2D will exercise for 16 weeks as a means of testing improved insulin sensitivity with changes in plasma EVs physiology. First, we will examine how EVs mediate Insulin induced vascular effects utilizing in-vitro and ex/in-vivo models (AIM 1). Then, we will identify EV cargo as effector of insulin mediated signaling by performing highly sensitive targeted and unbiased EV RNA and protein cargo analysis (AIM 2). Lastly, we will ascertain that exercise modulates EV mediated insulin sensitivity (AIM 3). These collective EV measures will be related to insulin-stimulated arterial stiffness (pulse wave velocity and augmentation index), and nitric oxide-mediated arterial function in conduit (flow mediated dilation), resistance (post-ischemic flow velocity) and microvascular (contrast enhanced ultrasound) vessels to translate mechanism to function in humans. If these hypotheses are correct, they will indicate 1) insulin acts on EVs as a novel mechanism of vascular function, 2) provide the first indication of whether EVs release cargo to impact endothelial function and 3) showcase a novel mechanism by which exercise contributes to CVD risk reduction. Thus, identification of EV, insulin action and exercise interactions will lay foundation for improving precision medicine that corrects vascular dysfunction in efforts to attenuate/prevent T2D and CV morbidity as well as mortality.