Search

African Americans (AA) have the highest prevalence of hypertension (HTN) in the world which may emanate from their predisposition to heightened endothelial inflammation. Long-term exposure of the endothelium to proinflammatory cytokines leads to increased oxidative stress, inflammation, and endothelial dysfunction which support an environment favoring HTN. It is thought that the balance between pro- and anti-inflammation plays a crucial role as a determinant of endothelial homeostasis and health. Positive associations between proinflammatory markers such as C-reactive protein (CRP) and interleukin-6 (IL-6) with HTN have been reported. Elevated circulating levels of the anti-inflammatory cytokine, interleukin-10 (IL-10) have been associated with improved endothelial function. In addition, aerobic exercise training (AEXT) has been associated with favorable endothelial adaptations. PURPOSE: To evaluate the effect of a 6-month AEXT intervention on the inflammatory biomarkers CRP, IL-6, and IL-10 in African Americans. A secondary purpose was to determine whether there are relationships between the changes in CRP, IL-6, and IL-10 subsequent to the 6-month AEXT intervention. METHODS: A Pre-Post design was employed following the completion of screening, dietary stabilization, and antihypertensive medication tapering. Subjects were sedentary, putatively healthy, 45-71 y/o AA men and women. Baseline evaluation included fasting blood sampling and graded exercise testing (GXT). Participants engaged in 6-months of AEXT. At the conclusion of the AEXT intervention, baseline tests were repeated. Concentrations of CRP, IL-6, and IL-10 were determined using an ELISA. RESULTS: There was a significant decrease in CRP (n=37; p=0.01) and a significant decrease in IL-6 (n=32; p=0.04) following AEXT. IL-10 was increased following the AEXT intervention, however it was not statistically significant (n=26; p=0.08). There were no significant relationships between the changes in the inflammatory biomarkers measured. CONCLUSION: Based on the favorable adaptations in the inflammatory biomarkers CRP and IL-6, AEXT may be a viable, nonpharmacologic method to reduce the risk for HTN in AA by improving inflammation status and endothelial function.

One of the precursors to hypertension (HTN) is systemic inflammation which can lead to vascular dysfunction and eventually HTN. Aerobic exercise training (AEXT) is known to be an important intervention tool in the prevention and treatment of HTN, inflammation and vascular dysfunction. However, no study has yet determined the effect of AEXT on inflammation in normotensive versus non-normotensive participants. Purpose: To assess whether there are differential changes in the inflammatory marker C-reactive protein (CRP) in normotensive versus non-normotensive participants in response to AEXT. METHODS: 27 participants ages 41-71 were assessed. To be considered for inclusion participants had to be free of any cardiovascular disease, non-smoking and sedentary. After inclusion participants underwent blood draws, blood pressure (BP) measurements and aerobic exercise testing. Aerobic fitness was by measuring VO2max. Participants then underwent AEXT (3 days/week, 65% of VO2max, 40 minutes/day) for 6 months. Whole blood was sent to Quest Diagnostics for the measurement of serum levels of CRP. Results: CRP levels were not significantly different between normotensive (avg. BP=113/74 mmHg, N=13) and non-normotensive (avg. BP=131/82 mmHg, N=14) participants before (2.86 ± 0.82 vs. 3.65 ± 0.90 mg/L) or after (3.28 ± 1.00 vs. 2.75 ± 0.73 mg/L) AEXT. However, non-normotensive participants significantly (p≤0.016) lowered their CRP levels (3.65 ± 0.90 vs. 2.75 ± 0.73 mg/L), whereas the normotensive group did not. Neither group lowered their BP levels. Conclusion: AEXT is a proven tool for the treatment and prevention of HTN and systemic inflammation. Although AEXT did not lower BP in our setting, results suggest that AEXT may be an important tool in lowering systemic inflammation in non-normotensives who are at greater risk for cardiovascular disease.

Background: Chronic inflammation and elevated levels of C reactive protein (CRP) can lead to reduced bioavailability of endothelium relaxing factors such as Nitric Oxide (NO) and increased production of vasoconstrictive pro-inflammatory agents such as endothelin-1 (ET1). African Americans (AA) have impaired vasodilatory capabilities evident through reduced NO bioavailability. The purpose of this study was to investigate the potential differential racial effect of CRP on ET1 and NO. METHODS: AA and Caucasian (C) Human Umbilical Vein Endothelial Cells (HUVECs) were cultured and treated with 0, 25, 50, and 100μg/mL CRP. The secretion of ET1 and NO in HUVEC culture medium supernatant was assessed by ELISA and a modified Griess assay, respectively. Results: At baseline (0μg/mL CRP) there were no significant differences between AA and C in ET1 (457.5 ± 44.8 vs 420.6 ± 34.8 pg/mL) or NO (8.0 ± 1.4 vs 7.4 ± 1.2 μmol/L). Differences (p≤.05) were found at 50μg/mL CRP between ET1 and NO between C and AA HUVECs (ET1: 566.7 ± 17.7 vs 595.8 ± 73.6 pg/mL) (NO: 0 ± 0 vs 1.1 ± 1.0 μmol/L). There was a significant increase in ET1 in the AA HUVECs from 0μg/mL (457.5 ± 44.8 pg/mL) to 25μg/mL CRP (546.8 ± 39.8 pg/mL) while NO decreased significantly in AA HUVECs from 0μg/mL (8.0 ± 1.4 μmol/L) to 25μg/mL (0.5 ± 0.2 μmol/L), 50μg/mL (1.1 ± 1.0 μmol/L), and 100μg/mL CRP (0.1 ± 0.1 μmol/L). C HUVECs showed significant changes in ET1 between 0μg/mL (420.6 ± 34.8 pg/mL) and 50μg/mL CRP (566.7 ± 17.7 pg/mL) and in NO from 0μg/mL CRP (7.4 ± 1.2 μmol/L) to 25μg/mL (0.8 ± 0.5 μmol/L), 50μg/mL (0 ± 0 μmol/L), and 100μg/mL (0.9 ± 0.6 μmol/L). Without the influence of race, significant increases in ET1 production occurred from 0μg/mL CRP (439.0 ± 39.8 pg/mL) to 25μg/mL (512.0 ± 38.9 pg/mL) (p ≤ 0.001) and 50μg/mL CRP (581.2 ± 45.6 pg/mL) and significant decreases in NO (p ≤ 0.001) from 0μg/mL CRP (7.7 ± 1.3 μmol/L) to 25μg/mL CRP (0.6 ± 0.4 μmol/L), 50μg/mL CRP (0.5 ± 0.5 μmol/L), and 100 μg/mL CRP (0.5 ± 0.3 μmol/L). Conclusions: Our data show that differential CRP induced ET1 and NO production does not appear to contribute to the difference in hypertension prevalence between AA and C. Further investigation is needed to determine the cause of the racial differences in Hypertension between African Americans and Caucasians.

Background: African Americans tend to have greater carotid intima-media thickness (IMT), and are 60% more likely to have a stroke than Caucasians. Data on the effects of lifestyle intervention on carotid IMT in African Americans does not exist. The aim of our study was to assess the efficacy of 6 months of diet and exercise intervention on carotid IMT in sedentary African American adults. Methods: Nineteen African American subjects (15F/4M, 52 ± 6yrs) who were sedentary, non smoking, non diabetic, free of cardiovascular disease, not on antihypertensive or cholesterol medications underwent 6 weeks of dietary counseling under the supervision of a registered dietician and were required to follow an AHA low fat, low salt diet for the duration of the study. Compliance was assessed by a diet log (3 days/week). Subjects completed 6 months of supervised aerobic exercise training (3 days/week, 40 minutes/session at 65% of their estimated VO 2max ). Common carotid artery IMT was assessed using high resolution ultrasonography. Results: At baseline, IMT significantly correlated with age (r = 0.58, P = 0.003) and total cholesterol (r = 0.41, P = 0.04). At 6 months, there were significant changes in basal metabolic index (ΔBMI, -0.83 kg/m 2 , P = 0.01); Δtriglycerides (-13.7 mg/dL, P = 0.03) and Δfasting glucose (-7.2 mg/dL, P = 0.01). On repeated measures ANCOVA, the mean IMT were statistically significantly different (F (1, 15) = 7.999, P = 0.013) between before vs. after training (Mean ± SD; 0.617 ± 0.092mm vs. 0.572 ± 0.068mm), after adjusting for changed variables (ΔBMI, Δtotal cholesterol and Δmean arterial pressure) as covariates. Conclusion: Our preliminary study showed that 6 months of diet and exercise intervention reduced carotid IMT by ∼7.3% and improved the cardio-metabolic profile in sedentary African Americans. Reduction in IMT from early and effective lifestyle modification strategies may help to improve cerebrovascular health and prevent stroke in this at-risk stroke population.