Correlation between endothelial function measured by finger plethysmography in children and HDL-mediated eNOS activation -- a preliminary study

Impact of different training modalities on high-density lipoprotein function in HFpEF patients: a substudy of the OptimEx trial

AIMS

In heart failure with preserved ejection fraction (HFpEF), the reduction of nitric oxide (NO)-bioavailability and consequently endothelial dysfunction leads to LV stiffness and diastolic dysfunction of the heart. Besides shear stress, high-density lipoprotein (HDL) stimulates endothelial cells to increased production of NO via phosphorylation of endothelial nitric oxide synthase (eNOS). For patients with heart failure with reduced ejection fraction, earlier studies demonstrated a positive impact of exercise training (ET) on HDL-mediated eNOS activation. The study aims to investigate the influence of ET on HDL-mediated phosphorylation of eNOS in HFpEF patients.

METHODS AND RESULTS

The present study is a substudy of the OptimEx-Clin trial. The patients were randomized to three groups: (i) HIIT (high-intensity interval training; (ii) MCT (moderate-intensity continuous training); and (iii) CG (control group). Supervised training at study centres was offered for the first 3 months. From months 4-12, training sessions were continued at home with the same exercise protocol as performed during the in-hospital phase. Blood was collected at baseline, after 3, and 12 months, and HDL was isolated by ultracentrifugation. Human aortic endothelial cells were incubated with isolated HDL, and HDL-induced eNOS phosphorylation at Ser¹¹⁷⁷ and Thr⁴⁹⁵ was assessed. Subsequently, the antioxidative function of HDL was evaluated by measuring the activity of HDL-associated paraoxonase-1 (Pon1) and the concentration of thiobarbituric acid-reactive substances (TBARS). After 3 months of supervised ET, HIIT resulted in increased HDL-mediated eNOS-Ser¹¹⁷⁷ phosphorylation. This effect diminished after 12 months of ET. No effect of HIIT was observed on HDL-mediated eNOS-Thr⁴⁹⁵ phosphorylation. MCT had no effect on HDL-mediated eNOS phosphorylation at Ser¹¹⁷⁷ and Thr⁴⁹⁵ . HIIT also increased Pon1 activity after 12 months of ET and reduced the concentration of TBARS in the serum after 3 and 12 months of ET. A negative correlation was observed between TBARS concentration and HDL-associated Pon1 activity in the HIIT group (r = -0.61, P < 0.05), and a trend was evident for the correlation between the change in HDL-mediated eNOS-Ser¹¹⁷⁷ phosphorylation and the change in peak V̇O₂ after 3 months in the HIIT group (r = 0.635, P = 0.07).

CONCLUSIONS

The present study documented that HIIT but not MCT exerts beneficial effects on HDL-mediated eNOS phosphorylation and HDL-associated Pon1 activity in HFpEF patients. These beneficial effects of HIIT were reduced as soon as the patients switched to home-based ET.

Association between serum uric acid level and endothelial dysfunction in elderly individuals with untreated mild hypertension

Background

Endothelial dysfunction is the initial stage in atherosclerotic formation and progression and is associated with high serum uric acid (SUA) level. We hypothesized that reactive hyperemia index (RHI), which reflects endothelial function, is associated with SUA levels in elderly individuals with untreated mild hypertension.

Methods

We recruited 123 patients ≥ 60 years with untreated mild hypertension. The association between SUA level and RHI was analyzed using univariate correlation analysis and multiple regression analysis. The receiver operating characteristic (ROC) curve was performed to validate the cutoff value of SUA that can be used to predict endothelial dysfunction.

Results

The serum uric acid level significantly increased in the RHI < 1.67 group, and this result was still observed in the subgroup of men. RHI was inversely associated with SUA level (P = 0.006) and the association was still observed after adjusting for factors, such as age, sex, smoking status, and creatinine level (P = 0.014). In the subgroup analysis, a positive association was observed only in men. In the ROC curve analysis, the optimal cutoff values of SUA for predicting endothelial dysfunction was 293.5 µmol/L in elderly mild hypertension patients and 287.0 µmol/L in men.

Conclusion

A high SUA level was considered an independent predictor of endothelial dysfunction among elderly individuals, particularly men with untreated mild hypertension.

Do self-reported stress and depressive symptoms effect endothelial function in healthy youth? The LOOK longitudinal study

BACKGROUND AND AIMS

Endothelial dysfunction is thought to be an early indicator of risk for cardiovascular disease and has been associated with both stress and depression in adults and adolescents. Less is known of these relationships in younger populations, where the origins of CVD is thought to manifest. This study examined the effects of questionnaire derived psychosocial stress and depressive symptoms on endothelial function among children, following them through to adolescence.

METHOD

Participants were 203 grade 2 children (111 girls; M age = 7.6 ± 0.3 years) from the LOOK longitudinal study, who were followed through to adolescence (16 years). Self-reported psychosocial stress and depression were assessed using the validated Children's Stress Questionnaire and a modified and validated version of the Children's Depression Inventory respectively; endothelial function was assessed using EndoPAT 2000 system at follow-up only; and adjustments were made for fitness, pubertal development and socioeconomic status.

RESULTS

Although all relationships occurred in the hypothesised direction, no cross-sectional or prospective evidence of early symptoms of psychological stress or depression being associated with endothelial dysfunction was found among our asymptomatic cohort of adolescents (all p > .05).

CONCLUSIONS

In contrast to previous findings in adolescents, our data provided little evidence of any relationship between current or previous psychosocial stress or depression and endothelial function in 16-year-old boys and girls. However, our data need to be interpreted alongside the potential limitations in the sensitivity associated with self-report methods for detecting psychological distress of children.

Endothelial Function in Children and Adolescents Is Mainly Influenced by Age, Sex and Physical Activity - An Analysis of Reactive Hyperemic Peripheral Artery Tonometry

BACKGROUND

As adolescents rarely experience cardiovascular events, surrogate markers of atherosclerosis are useful to justify and monitor effects of primary prevention and therapy of risk factors. Endothelial function assessed by reactive hyperemic peripheral arterial tonometry (RH-PAT) resulting in a reactive hyperemic index (RHI) is a noninvasive method with limited data for use in children and adolescents.Methods and Results:We performed a total of 931 RHI measurements in 445 high-school students, aged 10-17 years, over a time period of 5 years. Students were randomized by class to 60 min physical exercise (PE) at school daily (intervention group), or 2 units of 45-min PE weekly (control group). To characterize the factors influencing the RHI, anthropometry, cardiopulmonary exercise testing, blood cholesterol and quality of life were assessed and used to build mixed linear models. Main influential factors were age, with an increase of RHI from 1.53±0.42 in the youngest to 1.96±0.59 in the oldest students, sex, with higher values in girls, and physical activity. This increase adjusted by age and sex was estimated as 0.11 [0.08, 0.14] per year. RHI was higher in the intervention group by 0.09 [-0.05, 0.23] in comparison with the control group.

CONCLUSIONS

If RH-PAT is used in research or as a clinical tool in adolescents, the shown age- and sex-dependence of RHI have to be taken in account.

Impact of Rosuvastatin Treatment on HDL-Induced PKC-βII and eNOS Phosphorylation in Endothelial Cells and Its Relation to Flow-Mediated Dilatation in Patients with Chronic Heart Failure

Background. Endothelial function is impaired in chronic heart failure (CHF). Statins upregulate endothelial NO synthase (eNOS) and improve endothelial function. Recent studies demonstrated that HDL stimulates NO production due to eNOS phosphorylation at Ser(1177), dephosphorylation at Thr(495), and diminished phosphorylation of PKC-βII at Ser(660). The aim of this study was to elucidate the impact of rosuvastatin on HDL mediated eNOS and PKC-βII phosphorylation and its relation to endothelial function. Methods. 18 CHF patients were randomized to 12 weeks of rosuvastatin or placebo. At baseline, 12 weeks, and 4 weeks after treatment cessation we determined lipid levels and isolated HDL. Human aortic endothelial cells (HAEC) were incubated with isolated HDL and phosphorylation of eNOS and PKC-βII was evaluated. Flow-mediated dilatation (FMD) was measured at the radial artery. Results. Rosuvastatin improved FMD significantly. This effect was blunted after treatment cessation. LDL plasma levels were reduced after rosuvastatin treatment whereas drug withdrawal resulted in significant increase. HDL levels remained unaffected. Incubation of HAEC with HDL had no impact on phosphorylation of eNOS or PKC-βII. Conclusion. HDL mediated eNOS and PKC-βII phosphorylation levels in endothelial cells do not change with rosuvastatin in CHF patients and do not mediate the marked improvement in endothelial function.

Childhood obesity-related endothelial dysfunction: an update on pathophysiological mechanisms and diagnostic advancements

Childhood obesity jeopardizes a healthy future for our society's children as it is associated with increased cardiovascular morbidity and mortality later on in life. Endothelial dysfunction, the first step in the development of atherosclerosis, is already present in obese children and may well represent a targetable risk factor. Technological advancements in recent years have facilitated noninvasive measurements of endothelial homeostasis in children. Thereby this topic ultimately starts to get the attention it deserves. In this paper, we aim to summarize the latest insights on endothelial dysfunction in childhood obesity. We discuss methodological advancements in peripheral endothelial function measurement and newly identified diagnostic markers of vascular homeostasis. Finally, future challenges and perspectives are set forth on how to efficiently tackle the catastrophic rise in cardiovascular morbidity and mortality that will be inflicted on obese children if they are not treated optimally.

High density lipoproteins: Measurement techniques and potential biomarkers of cardiovascular risk

Plasma high density lipoprotein cholesterol (HDL) comprises a heterogeneous family of lipoprotein species, differing in surface charge, size and lipid and protein compositions. While HDL cholesterol (C) mass is a strong, graded and coherent biomarker of cardiovascular risk, genetic and clinical trial data suggest that the simple measurement of HDL-C may not be causal in preventing atherosclerosis nor reflect HDL functionality. Indeed, the measurement of HDL-C may be a biomarker of cardiovascular health. To assess the issue of HDL function as a potential therapeutic target, robust and simple analytical methods are required. The complex pleiotropic effects of HDL make the development of a single measurement challenging. Development of laboratory assays that accurately HDL function must be developed validated and brought to high-throughput for clinical purposes. This review discusses the limitations of current laboratory technologies for methods that separate and quantify HDL and potential application to predict CVD, with an emphasis on emergent approaches as potential biomarkers in clinical practice.

Bariatric surgery in severely obese adolescents improves major comorbidities including hyperuricemia

OBJECTIVE

Serum uric acid (sUA) is believed to contribute to the pathogenesis of metabolic comorbidities like hypertension, insulin-resistance (IR) and endothelial dysfunction (EDF) in obese children. The present pilot study investigated the association between sUA concentrations and loss of body weight following laparoscopic sleeve gastrectomy (LSG) or laparoscopic Roux-en-Y-gastric bypass (RYGB) in severely obese adolescents.

MATERIALS/METHODS

10 severely obese adolescents underwent either LSG (n=5) or RYGB (n=5). 17 normal weight, healthy, age- and gender-matched adolescents served as a normal weight peer group (NWPG). Pre- and 12 months postoperatively, sUA and relevant metabolic parameters (glucose homeostasis, transaminases, lipids) were compared.

RESULTS

Preoperatively, sUA was significantly elevated in patients with severe obesity compared to NWPG. Twelve months after LSG and RYGB, a significant decrease in sUA, BMI, CVD risk factors, hepatic transaminases, and HOMA-IR was observed. Reduction in SDS-BMI significantly correlated with changes in sUA.

CONCLUSIONS

sUA levels and metabolic comorbidities improved following bariatric surgery in severely obese adolescents. The impact of changes in sUA on long-term clinical complications of childhood obesity deserves further study.

Regulation of endothelial nitric oxide synthase and high-density lipoprotein quality by estradiol in cardiovascular pathology

Estrogens have been recognized, in the last 3 decades, as important hormones in direct and indirect modulation of vascular health. In addition to their direct benefit on cardiovascular health, the presence of esterified estrogen in the lipid core of high-density lipoprotein (HDL) particles indirectly contributes to atheroprotection by significantly improving HDL quality and functionality. Estrogens modulate their physiological activity via genomic and nongenomic mechanisms. Genomic mechanisms are thought to be mediated directly by interaction of the hormone receptor complex with the hormone response elements that regulate gene expression. Nongenomic mechanisms are thought to occur via interaction of the estrogen with membrane-bound receptors, which rapidly activate intracellular signaling without binding of the hormone receptor complex to its hormone response elements. Estradiol in particular mediates early and late endothelial nitric oxide synthase (eNOS) activation via interaction with estrogen receptors through both nongenomic and genomic mechanisms. In the vascular system, the primary endogenous source of nitric oxide (NO) generation is eNOS. Nitric oxide primarily influences blood vessel relaxation, the heart rate, and myocyte contractility. The abnormalities in expression and/or functions of eNOS lead to the development of cardiovascular diseases, both in animals and in humans. Although considerable research efforts have been dedicated to understanding the mechanisms of action of estradiol in regulating cardiac eNOS, more research is needed to fully understand the details of such mechanisms. This review focuses on recent findings from animal and human studies on the regulation of eNOS and HDL quality by estradiol in cardiovascular pathology.

Methodological considerations and practical recommendations for the application of peripheral arterial tonometry in children and adolescents

Endothelial dysfunction is recognized as the primum movens in the development of atherosclerosis. Its crucial role in both cardiovascular morbidity and mortality has been confirmed. In the past, research was hampered by the invasive character of endothelial function assessment. The development of non-invasive and feasible techniques to measure endothelial function has facilitated and promoted research in various adult and paediatric subpopulations. To avoid user dependence of flow-mediated dilation (FMD), which evaluates nitric oxide dependent vasodilation in large vessels, a semi-automated, method to assess peripheral microvascular function, called peripheral arterial tonometry (Endo-PAT(®)), was recently introduced. The number of studies using this technique in children and adolescents is rapidly increasing, yet there is no consensus with regard to either measuring protocol or data analysis of peripheral arterial tonometry in children and adolescents. Most paediatric studies simply applied measuring and analysing methodology established in adults, a simplification that may not be appropriate. This paper provides a detailed description of endothelial function assessment using the Endo-PAT for researchers and clinicians. We discuss clinical and methodological considerations and point out the differences between children, adolescents and adults. Finally, the main aim of this paper is to provide recommendations for a standardised application of Endo-PAT in children and adolescents, as well as for population-specific data analysis methodology.