The goal of this proposal is to understand why people with diabetes develop severe fatty-rich plaques called atherosclerosis in arteries. Atherosclerosis is linked to several cardiovascular diseases that cause disabilities and premature death. Unfortunately, such serious medical problems are very frequent among veterans as they are almost three times more likely to develop diabetes than people in the general population. One reason that has been identified to enhance atherosclerosis among diabetic individuals is high blood sugar, often called “hyperglycemia”. But exactly how hyperglycemia enhances atherosclerosis is not known. Our research program aims to explore the role of microvesicles released by cells, called “exosomes”, as a source of atherosclerosis. Our published and preliminary findings presented in our grant proposal show that both mice and humans with diabetes accumulate exosomes in their bloodstream that can increase inflammatory signaling when cultured with naïve cells. Our results also demonstrate that pro-inflammatory exosomes can be produced by macrophages cultured in glucose-rich medium that we termed HG-exosomes. We found that HG-exosomes simulate diabetic hyperglycemia by driving atherosclerosis when injected into non-diabetic mice. Remarkably, we also uncovered that macrophages can produce anti-inflammatory exosomes when they are exposed to protective cytokines such as interleukin-4. While we have reported that IL4-exosomes can exert protective effects in suppressing atherosclerosis in non-diabetic mice, we do not know if they can do the same to control diabetic atherosclerosis that is far more aggressive. Based on our extensive findings, we propose to explore mechanisms through which HG-exosomes communicate pro-inflammatory signaling in the immune system and the vessel wall. We also aim to investigate if IL4-exosomes can serve to overcome the effects of hyperglycemia to suppress the progression of diabetic atherosclerosis. Our First Aim will investigate molecular and cellular pathways through which HG-exosomes contribute to cause cellular dysfunction in cultured macrophages. We will test if they do so by causing lipid accumulation and by impairing the ability for macrophages to display protective anti-inflammatory activities that have been reported to be critical in suppressing atherosclerosis, and are known to be defective in the setting of diabetes. Our Second Aim will test if HG-exosome can communicate inflammatory signaling to fat cells called adipocytes to increase their storage of oily lipids and thereby cause inflammatory signaling. We will also test if the injection of HG-exosomes in to non-diabetic mice can cause them to develop diabetes as a result of increased visceral fat accumulation, resulting in obesity and high blood glucose levels that then accelerate atherosclerosis. We will test if IL4-exosomes can serve to prevent these effects to control atherosclerosis in obese diabetic mice. Our Third Aim will test if HG...