Coronary artery disease (CAD) is a chronic inflammatory vascular condition that remains a leading cause of death in the United States with disproportionate impact on the US veteran and active military populations. Cigarette smoking and other tobacco products clearly accelerate the development of CAD; however, the cellular and molecular mechanisms linking smoke with CAD remain poorly understood. To combat these issues, our group has provided extensive evidence linking smoke exposure with extracellular matrix degradation by matrix metalloproteases (MMPs) and the production of bioactive peptide fragments. These bioactive matrix fragments can promote chemotaxis (termed matrix-derived chemokines, or matrikines) and have been described by our group and others as novel mediators of inflammation in cardiovascular disease. Despite these observations, the contribution of matrikines to smoke-associated CAD is unknown. We provide preliminary data demonstrating the pro-inflammatory matrikine proline-glycine-proline (PGP) and its receptor CXC Chemokine Receptor 2 (CXCR2) to be inducible mediators of endothelial dysfunction and vascular inflammation with smoking. We also provide evidence that neutrophil and macrophage-derived exosomes are loaded with active proteases capable of generating PGP in response to smoke (i.e., proteolytic exosomes). Importantly, within a local cohort of patients with a significant history of smoking we observed that increased plasma PGP is associated with CAD or prior coronary revascularization. These results beg the question as to whether smoke induces a feedforward mechanism of proteolytic exosome release, PGP production, and subsequent inflammatory cell infiltration into the vascular wall thereby accelerating the development of CAD. For this proposal, we will build on our seminal observations by first investigating PGP production and endothelial CXCR2 signaling as critical promoters of vascular disease in a smoke-induced mouse model of atherosclerosis (Specific Aim 1). Secondly, we will investigate smoke activated neutrophil and/or macrophage exosomes as direct mediators of endothelial dysfunction and vascular inflammation (Specific Aim 2). Notably, we hypothesize that neutrophil-exosome associated neutrophil elastase (NE) and macrophage-exosome associated MMP-12 may propagate vascular matrix fragmentation and endothelial dysfunction in response to smoke. Finally, we will identify PGP and NE+ / MMP-12+ exosomes as clinical biomarkers of CAD within a cohort of subjects referred for coronary angiography and defined by their smoking status (i.e., Never, Former, and Current, Specific Aim 3). Successful completion of these aims will lead to an increased understanding of matrikine biology in vascular disease, as well as improve our ability to stratify veterans at risk for smoke-induced CAD. Importantly, these studies will likely result in the development of new biomarkers and potential new therapeutic approaches for the prevention of CAD...