Increment of body mass index is positively correlated with worsening of endothelium-dependent and independent changes in forearm blood flow

Methods to evaluate vascular function: a crucial approach towards predictive, preventive, and personalised medicine

Endothelium, the gatekeeper of our blood vessels, is highly heterogeneous and a crucial physical barrier with the ability to produce vasoactive and protective mediators under physiological conditions. It regulates vascular tone, haemostasis, vascular inflammation, remodelling, and angiogenesis. Several cardio-, reno-, and cerebrovascular diseases begin with the dysfunction of endothelial cells, and more recently, COVID-19 was also associated with endothelial disease highlighting the need to monitor its function towards prevention and reduction of vascular dysfunction. Endothelial cells are an important therapeutic target in predictive, preventive, and personalised (3P) medicine with upmost importance in vascular diseases. The development of novel non-invasive techniques to access endothelial dysfunction for use in combination with existing clinical imaging modalities provides a feasible opportunity to reduce the burden of vascular disease.

This review summarises recent advances in the principles of endothelial function measurements. This article presents an overview of invasive and non-invasive techniques to determine vascular function and their major advantages and disadvantages. In addition, the article describes mechanisms underlying the regulation of vascular function and dysfunction and potential new biomarkers of endothelial damage. Recognising these biomarkers is fundamental towards a shift from reactive to 3P medicine in the vascular field. Identifying vascular dysfunction earlier with non-invasive or minimally invasive techniques adds value to predictive diagnostics and targeted prevention (primary, secondary, tertiary care). In addition, vascular dysfunction is a potential target for treatments tailored to the person.

Inflammatory and endothelial dysfunction indices among Egyptian females with obesity classes I-III

Background: Obesity is an alarming threat to health in Egypt. More than one in three Egyptians is obese, the highest rate in the world. We aimed to delineate the variability of inflammation and endothelial dysfunction markers among Egyptian females with different obesity classes. Methods: Out of 130 females, 70 were categorized into three obesity groups: Class I, body mass index (BMI) 30–34.9 kg/m²; Class II, BMI 35–39.9 kg/m² and Class III BMI ≥ 40 kg/m², besides 60 control subjects. Anthropometric measurements were recorded and serum levels of tumor necrosis factor-α (TNF-α), C-reactive protein (CRP), interleukin (IL) 6 (IL-6), IL-12, soluble intercellular adhesion molecule 1 (sICAM-1) and soluble vascular adhesion molecule 1 (sVCAM-1) were assessed among participants. Results: In all three classes of obesity, significant increase (P <0.05) in BMI, waist-hip ratio, fat mass and body fat mass % were noted. CRP and sVCAM-1 levels were increased among the three obesity groups. TNF-α levels were increased in class II and III obesity groups. IL-6 and IL-12 levels were elevated in class I and class III groups. While, ICAM-1 levels were increased in class III obesity group. Conclusion: Based on individuals’ BMI, serum levels of TNF-α, CRP, IL-6, IL-12, sVCAM-1 and sICAM-1 are differentially altered with the progression of obesity. We strongly support the hypothesis that, as the obesity rate is still mounting, a subclinical inflammatory reaction has a role in pathogenesis of obesity and emphasize the elevation of endothelial dysfunction in individuals with obesity.

The continuums of impairment in vascular reactivity across the spectrum of cardiometabolic health: A systematic review and network meta-analysis

This study aimed to assess, for the first time, the change in vascular reactivity across the full spectrum of cardiometabolic health. Systematic searches were conducted in MEDLINE and EMBASE databases from their inception to March 13, 2017, including studies that assessed basal vascular reactivity in two or more of the following health groups (aged ≥18 years old): healthy, overweight, obesity, impaired glucose tolerance, metabolic syndrome, or type 2 diabetes with or without complications. Direct and indirect comparisons of vascular reactivity were combined using a network meta-analysis. Comparing data from 193 articles (7226 healthy subjects and 19344 patients), the network meta-analyses revealed a progressive impairment in vascular reactivity (flow-mediated dilation data) from the clinical onset of an overweight status (-0.41%, 95% CI, -0.98 to 0.15) through to the development of vascular complications in those with type 2 diabetes (-4.26%, 95% CI, -4.97 to -3.54). Meta-regressions revealed that for every 1 mmol/l increase in fasting blood glucose concentration, flow-mediated dilation decreased by 0.52%. Acknowledging that the time course of disease may vary between patients, this study demonstrates multiple continuums of vascular dysfunction where the severity of impairment in vascular reactivity progressively increases throughout the pathogenesis of obesity and/or insulin resistance, providing information that is important to enhancing the timing and effectiveness of strategies that aim to improve cardiovascular outcomes.

HDL-C and non-HDL-C levels are associated with anthropometric and biochemical parameters

Background

Dyslipidemias are associated with atherosclerosis and cardiovascular diseases. Recently, non-high-density lipoprotein cholesterol (non-HDL-c) has emerged as a new target for assessment and prediction of risk of cardiovascular disease (CVD) and is closely associated with atheroma plaque progression.

Objectives

To evaluate associations between HDL-c and non-HDL-c levels and anthropometric and biochemical parameters and with the Castelli risk indexes I and II.

Methods

300 randomly selected people were subdivided into two groups: patients with normal values for non-HDL-c and patients with altered values for non-HDL-c. These parameters were analyzed for associations with glycemia, total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL-c), Castelli Index I (CI-I), Castelli Index II (CI-II), waist circumference (WC), body mass index (BMI) and presence of metabolic syndrome (MS).

Results

Glycemia, TC, TG, LDL-c, CI-I, CI-II, WC and BMI were all significantly different between subjects with normal and altered values of HDL-c and non-HDL-c. TC and WC both exhibited significantly higher values among patients with abnormal non-HDL-c when compared to patients with abnormal HDL-c. A significant difference was observed in occurrence of MS among patients with altered values of HDL-c and non-HDL-c.

Conclusions

Our results show that both HDL-c and non-HDL-c are associated with insulin resistance, dyslipidemia, atherogenic indices, and obesity. There is therefore a need for randomized clinical intervention trials examining the potential role of non-HDL-c as a possible primary therapeutic target.

30-days effects of vildagliptin on vascular function, plasma viscosity, inflammation, oxidative stress, and intestinal peptides on drug-naïve women with diabetes and obesity: a randomized head-to-head metformin-controlled study

BACKGROUND

Obesity is the main risk factor for diabetes and excessive visceral fat triggers low-grade inflammatory process, mediated by activation and release of cytokines and high flow of free fatty acids that contribute to insulin resistance, increased oxidative stress, and impaired endothelial function. Metformin and vildagliptin have known vasculoprotective actions, but the value of these drugs on drug-naïve diabetic patients during 30 days use warrants investigation. Our purpose was to observe their effects on endothelial function, oxidative stress, inflammatory biomarkers, and plasma viscosity.

METHODS

38 women with obesity and type 2 diabetes drug-naïve, aged between 19 and 50 years, BMI ≥ 30 kg/m², were recruited and subjected to measurements of endothelial function, nutritive skin microvascular reactivity, plasma viscosity, inflammatory and oxidative stress biomarkers at baseline and randomized 1:1 to ingest metformin (850 mg twice/day) or vildagliptin (50 mg twice/day) during 30 days, and then, re-evaluated.

RESULTS

No differences between groups were noticed at baseline. After treatment, vildagliptin promoted an improvement on endothelial-dependent and -independent vasodilatations, at arteriole level, while metformin resulted in improved nutritive microvascular reactivity, at the capillary level. Intragroup analysis showed that vildagliptin reduced insulin, C-peptide and oxidized LDL, and increased adiponectin and glucagon-like peptide-1 while metformin reduced weight, plasma glucose, total cholesterol, HDL-c, LDL-c, and dipeptidyl peptidase-4 activity, with an unexpected increase on tumor necrosis factor-α. No significant difference in plasma viscosity was noted.

CONCLUSIONS

In the vascular beds investigated, both drugs used for only 30 days improved endothelial function, through distinct, and possibly, complementary mechanisms on drug-naïve diabetic women.Trial Registration ClinicalTrials.gov: NCT01827280.

Obesity impairs leukocyte-endothelium cell interactions and oxidative stress in humans

BACKGROUND

To evaluate the relationship between leukocyte-endothelial cell interactions and oxidative stress parameters in non-diabetic patients with different grades of obesity.

MATERIAL AND METHODS

For this cross-sectional study, 225 subjects were recruited from January 1, 2014 to December 31, 2016 and divided into groups according to BMI (<30 kg/m² , 30-40 kg/m² and >40 kg/m²). We determined clinical parameters, systemic inflammatory markers, soluble cellular adhesion molecules, leukocyte-endothelium cell interactions-rolling flux, velocity and adhesion-, oxidative stress parameters-total ROS, total superoxide, glutathione-and mitochondrial membrane potential in leukocytes.

RESULTS

We verified that HOMA-IR and hsCRP increased progressively as obesity developed, whereas A1c, IL6 and TNFα were augmented in the BMI > 40 kg/m² group. The cellular adhesion molecule sP-selectin was increased in patients with obesity, while sICAM, total ROS, total superoxide and mitochondrial membrane potential were selectively higher in the BMI > 40 kg/m² group. Obesity induced a progressive decrease in rolling velocity and an enhancement of rolling flux and leukocyte adhesion.

CONCLUSION

Our findings reveal that endothelial dysfunction markers are altered in human obesity and are associated with proinflammatory cytokines and increased oxidative stress parameters.

Rapid versus slow ascending vasodilatation: intercellular conduction versus flow-mediated signalling with tetanic versus rhythmic muscle contractions

KEY POINTS

In response to exercise, vasodilatation ascends from downstream arterioles into upstream feed arteries (FAs). We hypothesized that the signalling events underlying ascending vasodilatation variy with the intensity and duration of skeletal muscle contraction. In the gluteus maximus muscle of C57BL/6 mice, brief tetanic contraction evoked rapid onset vasodilatation (ROV) (<1 s) throughout the resistance network. Selective damage to endothelium midway between FAs and primary arterioles eliminated ROV only in FAs. Blocking SK_Ca and IK_Ca channels attenuated ROV, implicating hyperpolarization as the underlying signal. During rhythmic twitch contractions, slow onset vasodilatation (10-15 s) in FAs remained intact following loss of ROV and was eliminated following nitric oxide synthase inhibition. Tetanic contraction initiates hyperpolarization that conducts along endothelium into FAs. Rhythmic twitch contractions stimulate FA endothelium to release nitric oxide in response to elevated shear stress secondary to metabolic dilatation of arterioles. Complementary endothelial signalling pathways for ascending vasodilatation ensure increased oxygen delivery to active skeletal muscle.

ABSTRACT

In response to exercise, vasodilatation initiated within the microcirculation of skeletal muscle ascends the resistance network into upstream feed arteries (FAs) located external to the tissue. Ascending vasodilatation (AVD) is essential for reducing FA resistance that otherwise restricts blood flow into the microcirculation. In the present study, we tested the hypothesis that signalling events underlying AVD vary with the intensity and duration of muscle contraction. In the gluteus maximus muscle of anaesthetized male C57BL/6 mice (aged 3-4 months), brief tetanic contraction (100 Hz for 500 ms) evoked rapid onset vasodilatation (ROV) in FAs that peaked within 4 s. By contrast, during rhythmic twitch contractions (4 Hz), slow onset vasodilatation (SOV) of FAs began after ∼10 s and plateaued within 30 s. Selectively damaging the endothelium with light-dye treatment midway between a FA and its primary arteriole eliminated ROV in the FA along with conducted vasodilatation of the FA initiated on the arteriole using ACh microiontophoresis. Superfusion of SK_Ca and IK_Ca channel blockers UCL 1684 + TRAM 34 attenuated ROV, implicating endothelial hyperpolarization as the underlying signal. Nevertheless, the SOV of FAs during rhythmic contractions persisted until inhibition of nitric oxide synthase with N^ω -nitro-l-arginine methyl ester. Thus, ROV of FAs reflects hyperpolarization of downstream arterioles that conducts along the endothelium into proximal FAs. By contrast, SOV of FAs reflects the local production of nitric oxide by the endothelium in response to luminal shear stress, which increases secondary to arteriolar dilatation downstream. Thus, AVD ensures increased oxygen delivery to active muscle fibres by reducing upstream resistance via complementary signalling pathways that reflect the intensity and duration of muscle contraction.

Forearm Resistance-Vessel Dilatation Function During Reactive Hyperemia in Patients With Resistant Hypertension

BACKGROUND

Forearm blood flow (FBF) measured during reactive hyperemia by venous-occlusion plethysmography assesses resistance-vessel dilatation function but has never been investigated in resistant hypertension. The aim was to evaluate the independent correlates of forearm resistance-vessel function parameters in resistant hypertensives.

METHODS

In a cross-sectional study, 274 resistant hypertensives performed 24-hour ambulatory blood pressure (BP) monitoring, 2D-echocardiography, aortic pulse wave velocity, and venous-occlusion plethysmography with baseline and hyperemic FBF and vascular resistance measurements. A subsample of 103 patients also performed ultrasonographic brachial artery endothelial function examination. Independent correlates of baseline and hyperemic vascular parameters were assessed by multiple linear regressions.

RESULTS

Median (interquartile range) baseline FBF was 3.1 (2.4-4.0) ml/min/100ml of tissue, and during hyperemia mean FBF rose to 7.0 (5.2-9.4) ml/min/100ml of tissue. Baseline FBF and resistance were independently associated with left ventricular mass index (partial correlations -0.14 and 0.13, respectively), whereas hyperemic parameters were independently associated with body mass index (BMI) (inversely for FBF, partial correlation: -0.18 to -0.21) and with the nocturnal BP fall (directly for FBF, partial correlation: 0.12-0.15), after adjustments for age, sex, mean arterial pressure, and baseline vascular parameters. In a separate analysis, a larger brachial artery diameter was associated with higher hyperemic FBF, but there were no associations between resistance-vessel and conduit-vessel dilatation function parameters.

CONCLUSION

In patients with resistant hypertension, left ventricular mass was the only correlate of baseline FBF and resistance, whereas higher BMI and lower nocturnal BP fall were independently associated with lower FBF and higher resistance during reactive hyperemia.

Impact of individual metabolic risk components or its clustering on endothelial and smooth muscle cell function in men

BACKGROUND

Impaired vasoreactivity is often observed in subjects with metabolic syndrome, a condition that includes the presence of a specific cluster of risk factors for obesity and cardiovascular disease. However, hierarchical causes in the impaired vasoreactivity have not been clarified. We evaluated the impact of individual metabolic risk components or its clustering under the condition of insulin resistance on endothelial and smooth muscle cell function.

METHODS

Vascular reactivity to acetylcholine (Ach), with or without nitric oxide synthase (NOS) inhibitor N (G)-monomethyl-L-arginine (L-NMMA), or sodium nitroprusside (SNP) by forearm venous occlusion plethysmography and insulin sensitivity index (M mg/kg/min) in euglycemic clamp were measured in men without (n = 18, control group) or with (n = 19, metabolic syndrome group) metabolic syndrome.

RESULTS

(1) Ach-induced maximal forearm blood flow (maxFBF) was impaired in subjects with metabolic syndrome. In particular, the NOS-dependent component of Ach-induced maxFBF was selectively decreased, while the NOS-independent component remained relatively unchanged. (2) Ach-induced maxFBF and ∆Ach-induced maxFBF with L-NMMA were correlated with waist circumference, glucose, and triglycerides, and most strongly correlated with visceral fat area, adiponectin, and M. (3) Multivariate regression analysis indicated that individual metabolic risk components explained Ach-induced maxFBF by 4-21 %. Clustering of all metabolic risk components increased this to 35 %, and the presence of metabolic syndrome explained 30 %, indicating that defining metabolic syndrome can effectively predict impairment of endothelial dysfunction.

CONCLUSIONS

Endothelial dysfunction was correlated with individual metabolic risk components, but more strongly with clustering of the components under a condition with low insulin sensitivity. We suggest that in subjects with metabolic syndrome, endothelial function is impaired by multiple cardiovascular risk factors exclusively when under the condition of insulin insensitivity and also that defining metabolic syndrome can effectively predict impairment of endothelial dysfunction.