Non-technical summary Circulating angiogenic cells (CACs) repair and maintain the vascular endothelium. CACs are responsive to lifestyle factors such as diet and physical activity. For example, their capacity to regenerate the endothelium is impaired in cardiovascular disease patients, whereas exercise training can improve CAC function. In this study, we examined the effects of a high-fat meal with and without prior endurance exercise on several molecular aspects of CAC function, including levels of reactive oxygen species (ROS), nitric oxide (NO), intracellular lipids, and gene expression. Our results indicated that the high-fat meal induced significant oxidative stress (i.e. ROS production) in the CACs that expressed the cell surface protein CD31. However, when subjects performed a single bout of exercise on the prior day, the meal had no effect on ROS in CD31 + cells. Therefore, we concluded that prior exercise prevents the oxidative stress induced by a high-fat meal in CD31 + CACs.Abstract We hypothesized that prior exercise would prevent postprandial lipaemia (PPL)-induced increases in intracellular reactive oxygen species (ROS) in three distinct circulating angiogenic cell (CAC) subpopulations. CD34 + , CD31 + /CD14 − /CD34 − , and CD31 + /CD14 + /CD34 − CACs were isolated from blood samples obtained from 10 healthy men before and 4 h after ingesting a high fat meal with or without ∼50 min of prior endurance exercise. Significant PPL-induced increases in ROS production in both sets of CD31 + cells were abolished by prior exercise. Experimental ex vivo inhibition of NADPH oxidase activity and mitochondrial ROS production indicated that mitochondria were the primary source of PPL-induced oxidative stress. The attenuated increases in ROS with prior exercise were associated with increased antioxidant gene expression in CD31 + /CD14 − /CD34 − cells and reduced intracellular lipid uptake in CD31 + /CD14 + /CD34 − cells. These findings were associated with systemic cardiovascular benefits of exercise, as serum triglyceride, oxidized low density lipoprotein-cholesterol, and plasma endothelial microparticle concentrations were lower in the prior exercise trial than the control trial. In conclusion, prior exercise completely prevents PPL-induced increases in ROS in CD31 + /CD14 − /CD34 − and CD31 + /CD14 + /CD34 − cells. The mechanisms underlying the effects of exercise on CAC function appear to vary among specific CAC types.

The purpose of this study was to investigate the association of visit-to-visit and 24-h BP variability with markers of endothelial injury and vascular function. We recruited 72 African Americans who were non-diabetic, non-smoking, and free of cardiovascular and renal disease. Office BP was measured at three visits and 24-h ambulatory BP monitoring was conducted to measure visit-to-visit and 24-h BP variability, respectively. The 5-min time-course of brachial artery flow-mediated dilation and nitroglycerin-mediated dilation were assessed as measures of endothelial and smooth muscle function. Fasted blood samples were analyzed for circulating endothelial microparticles. Significantly lower CD31+CD42− endothelial microparticles were found in participants with high visit-to-visit SBP variability or high 24-h DBP variability. Participants with high visit-to-visit DBP variability had significantly lower flow-mediated dilation and higher nitroglycerin-mediated dilation at multiple time-points. When analyzed as continuous variables, 24-h mean arterial pressure variability was inversely associated with CD62+ endothelial microparticles; visit-to-visit DBP variability was inversely associated with flow-mediated dilation normalized by smooth muscle function and was positively associated with nitroglycerin-mediated dilation; and 24-h DBP variability was positively associated with nitroglycerin-mediated dilation. All associations were independent of age, gender, BMI, and mean BP. In conclusion, in this cohort of African Americans visit-to-visit and 24-h BP variability were associated with measures of endothelial injury, endothelial function, and smooth muscle function. These results suggest that BP variability may influence the pathogenesis of cardiovascular disease, in part, through influences on vascular health.

African Americans (AA) tend to have heightened systemic inflammation and endothelial dysfunction. Endothelial microparticles (EMP) are released from activated/apoptotic endothelial cells (EC) when stimulated by inflammation. The purpose of our study was to assess EMP responses to inflammatory cytokine (TNF-α) and antioxidant (superoxide dismutase, SOD) conditions in human umbilical vein ECs (HUVECs) obtained from AA and Caucasians. EMPs were measured under four conditions: control (basal), TNF-α, SOD, and TNF-α + SOD. Culture supernatant was collected for EMP analysis by flow cytometry and IL-6 assay by ELISA. IL-6 protein expression was assessed by Western blot. AA HUVECs had greater EMP levels under the TNF-α condition compared to the Caucasian HUVECs (6.8 ± 1.1 vs 4.7% ± 0.4%, P = 0.04). The EMP level increased by 89% from basal levels in the AA HUVECs under the TNF-α condition (P = 0.01) compared to an 8% increase in the Caucasian HUVECs (P = 0.70). Compared to the EMP level under the TNF-α condition, the EMP level in the AA HUVECs was lower under the SOD only condition (2.9% ± 0.3%, P = 0.005) and under the TNF-α + SOD condition (2.1% ± 0.4%, P = 0.001). Basal IL-6 concentrations were 56.1 ± 8.8 pg/mL/μg in the AA and 30.9 ± 14.9 pg/mL/μg in the Caucasian HUVECs (P = 0.17), while basal IL-6 protein expression was significantly greater (P < 0.05) in the AA HUVECs. These preliminary observational results suggest that AA HUVECs may be more susceptible to the injurious effects of the proinflammatory cytokine, TNF-α.

Park J-Y. Shear stress-induced mitochondrial biogenesis decreases the release of microparticles from endothelial cells. Am J Physiol Heart Circ Physiol 309: H425-H433, 2015. First published May 29, 2015 doi:10.1152/ajpheart.00438.2014.-The concept of enhancing structural integrity of mitochondria has emerged as a novel therapeutic option for cardiovascular disease. Flow-induced increase in laminar shear stress is a potent physiological stimulant associated with exercise, which exerts atheroprotective effects in the vasculature. However, the effect of laminar shear stress on mitochondrial remodeling within the vascular endothelium and its related functional consequences remain largely unknown. Using in vitro and in vivo complementary studies, here, we report that aerobic exercise alleviates the release of endothelial microparticles in prehypertensive individuals and that these salutary effects are, in part, mediated by shear stress-induced mitochondrial biogenesis. Circulating levels of total (CD31 ϩ /CD42a Ϫ ) and activated (CD62E ϩ ) microparticles released by endothelial cells were significantly decreased (ϳ40% for both) after a 6-mo supervised aerobic exercise training program in individuals with prehypertension. In cultured human endothelial cells, laminar shear stress reduced the release of endothelial microparticles, which was accompanied by an increase in mitochondrial biogenesis through a sirtuin 1 (SIRT1)-dependent mechanism. Resveratrol, a SIRT1 activator, treatment showed similar effects. SIRT1 knockdown using small-interfering RNA completely abolished the protective effect of shear stress. Disruption of mitochondrial integrity by either antimycin A or peroxisome proliferator-activated receptor-␥ coactivator-1␣ small-interfering RNA significantly increased the number of total, and activated, released endothelial microparticles, and shear stress restored these back to basal levels. Collectively, these data demonstrate a critical role of endothelial mitochondrial integrity in preserving endothelial homeostasis. Moreover, prolonged laminar shear stress, which is systemically elevated during aerobic exercise in the vessel wall, mitigates endothelial dysfunction by promoting mitochondrial biogenesis. shear stress; exercise; mitochondrial biogenesis; endothelial microparticle NEW & NOTEWORTHYThis study assesses effects of aerobic exercise training on the release of microparticles from endothelial cells and corroborates these findings using an in vitro experimental exercise stimulant, laminar shear stress. Furthermore, this study demonstrated that shear stress-induced mitochondrial biogenesis mediates these effects against endothelial cell activation and injury.IN ENDOTHELIAL CELLS (ECs), mitochondria occupy a relatively small compartment of cytoplasmic volume (ϳ2-6%) than other energy demanding cell-types such as cardiomyocytes (32). The endothelial mitochondria are, however, thought to play a key regulatory role in cell signaling (39), calcium handling (44), and cell survival (49). Indeed, an impaired mit...

As healthcare progresses toward individualized medicine, understanding how different racial groups respond to lifestyle interventions is valuable. It is established that African Americans have disproportionate levels of cardiovascular disease and impaired vascular health, and clinical practice guidelines suggest lifestyle interventions as the first line of treatment. Recently, we reported six months of aerobic exercise improved inflammatory markers, flow-mediated dilation (FMD), and levels of circulating endothelial microparticles (EMPs) in African American adults. This study is a subgroup analysis of the aerobic exercise-induced changes in vascular health and blood pressure (BP) measures; carotid artery intima-media thickness (IMT), nitroglycerin-mediated dilation (NMD), ambulatory BP, and office BP. Sedentary African American adults (53.4±6.2yrs;21F,5M) showed improved vascular health, but no change in BP. Carotid artery IMT decreased 6.4%, plasma NO levels increased 76.6%, plasma EMP levels decreased, percent FMD increased 59.6%, and FMD/NMD ratio increased 36.2% (P <0.05 for all). Six months of aerobic exercise training is sufficient to elicit improvements in vascular structure and function in African Americans, even without improvements in BP measures or NMD (i.e., smooth muscle function). To our knowledge, this is the first study to report such findings in African Americans.