Effects of exercise and inflammation on circulating microparticles

Abstract

Circulating microparticles (MPs), a subset of extracellular vesicles, have been implicated as novel biomarkers connected to vascular dysfunction. As such, they may contribute to atherosclerosis, hypertension, and other conditions leading to cardiovascular disease. MPs are involved in cell-to-cell communication in response to apoptosis and activation of the immune and inflammatory response, transferring their contents to nearby cells and effectively spreading each condition. The objective of this dissertation was to explore how circulating MP number and function are affected by stimuli such as diet and exercise. Our first study examined how post-prandial inflammation caused by a high-fat meal affects circulating MP number and function in young, healthy adults. We determined that a high fitness level may have a protective effect against the inflammatory load posed by a high-fat meal. The second study determined the effects of acute high-intensity interval aerobic exercise versus acute moderate intensity continuous aerobic exercise on circulating MP number and function in overweight versus lean recreationally active adults. We found that MPs and arterial stiffness in overweight individuals are differentially impacted by the type of acute exercise. Our findings suggest that overweight individuals undergo a greater inflammatory response following high-intensity exercise compared to lean. The third study investigated the effects of a 6-month aerobic exercise training program on circulating MP counts and function in previously sedentary older adults. While we found no effect of the exercise training program on MPs, we provide insight into how improvements in cardiovascular fitness as well as higher exercise intensities may be needed to see changes in MP number and function following aerobic exercise training in older adults. For the first time, we have shown that both dietary inflammation and acute exercise can significantly impact MP function. Furthermore, we have shown that fitness status and body composition play important roles in determining MP number and function after each stimulus. Our findings provide novel insight into how MPs contribute to various types of inflammation as well as how they may be used as biomarkers to measure the progression of cardiovascular disease.