Role of Polyphenols and Carotenoids in Endothelial Dysfunction: An Overview from Classic to Innovative Biomarkers

Nowadays, the dramatically increased prevalence of metabolic diseases, such as obesity and diabetes mellitus and their related complications, including endothelial dysfunction and cardiovascular disease, represents one of the leading causes of death worldwide. Dietary nutrients together with healthy lifestyles have a crucial role in the endothelium health-promoting effects. From a growing body of evidence, active natural compounds from food, including polyphenols and carotenoids, have attracted particular attention as a complementary therapy on atherosclerosis and cardiovascular disease, as well as preventive approaches through the attenuation of inflammation and oxidative stress. They mainly act as radical scavengers by promoting a variety of biological mechanisms, such as improvements in endothelial function, blood pressure, platelet activity, and insulin sensitivity, and by modulating various known biomarkers. The present review highlights the role of polyphenols and carotenoids in early endothelial dysfunction with attention to their beneficial effect in modulating both classical and recent technologically generated emerging biomarkers. These, alone or in combination, can play an important role in the prediction, diagnosis, and evolution of cardiovascular disease. However, a main challenge is to speed up early and prompt new interventions in order to prevent or slow down disease progression, even with an adequate intake of bioactive compounds. Hence, there is an urgent need of new more validated, appropriate, and reliable diagnostic and therapeutic biomarkers useful to diagnose endothelial dysfunction at an earlier stage.

Arginase inhibition by (-)-Epicatechin reverses endothelial cell aging

Endothelial dysfunction (EnD) occurs with aging and endothelial nitric oxide (NO) production by NO synthase (NOS) can be impaired. Low NO levels have been linked to increased arginase (Ar) activity as Ar competes with NOS for L-arginine. The inhibition of Ar activity can reverse EnD and (-)-epicatechin (Epi) inhibits myocardial Ar activity. In this study, through in silico modeling we demonstrate that Epi interacts with Ar similarly to its inhibitor Norvaline (Norv). Using in vitro and in vivo models of aging, we examined Epi and Norv-inhibition of Ar activity and its endothelium-protective effects. Bovine coronary artery endothelial cells (BCAEC) were treated with Norv (10 μM), Epi (1 μM) or the combination (Epi + Norv) for 48 h. Ar activity increased in aged BCAEC, with decreased NO generation. Treatment decreased Ar activity to levels seen in young cells. Epi and Epi + Norv decreased nitrosylated Ar levels by ~25% in aged cells with lower oxidative stress (~25%) (dihydroethidium) levels. In aged cells, Epi and Epi + Norv restored the eNOS monomer/dimer ratio, protein expression levels and NO production to those of young cells. Furthermore, using 18 month old rats 15 days of treatment with either Epi (1 mg/kg), Norv (10 mg/kg) or combo, decreased hypertension and improved aorta vasorelaxation to acetylcholine, blood NO levels and tetra/dihydribiopterin ratios in cultured rat aortic endothelial cells. In conclusion, results provide evidence that inhibiting Ar with Epi reverses aged-related loss of eNOS function and improves vascular function through the modulation of Ar and eNOS protein levels and activity.

Root essential oil of Chrysopogon zizanioides relaxes rat isolated thoracic aorta - an ex vivo approach

Root of Chrysopogon zizanioides (L.) Roberty has been used in Siddha system of medicine to treat hypertension. The present study was therefore to investigate the vasorelaxation effect of root essential oil of C. zizanioides using rat isolated thoracic aortic rings. Chemical characterization of root essential oil was carried out using Gas Chromatography-Flame Ionization Detector (GC-FID) and Gas Chromatography-Mass Spectrometry (GC-MS). Essential oil nanoemulsion (EONE) was prepared and characterized. Vasorelaxant effect of EONE in endothelium-intact aortic rings precontracted with phenylephrine (PE) (1 µM) or KCl (80 mM) was investigated. Role of Ca²⁺, nitric oxide and K⁺ channels in precontracted aortic rings were investigated to elucidate the mechanism of action of the essential oil. Further, the role of muscarinic and prostacyclin receptors in EONE induced relaxation was studied. The EONE significantly induced relaxation (E_max 77.1 ± 4.87%) in PE precontracted aortic rings. The nitric oxide synthase, and cyclooxygenase inhibitors and potassium channel blockers have not significantly inhibited the vasorelaxation induced by EONE. However, EONE induced relaxation in precontracted endothelium-intact aortic rings was significantly inhibited by muscarinic receptor and calcium channel. The root essential oil of C. zizanioides possesses vasorelaxant effect through muscarinic pathway as well as acts as calcium channel blocker.

Ionizing radiation induces BH4 deficiency by downregulating GTP-cyclohydrolase 1, a novel target for preventing and treating radiation enteritis

Radiation enteritis (RE) is a common side effect after radiotherapy for abdominal cancer. RE pathogenesis is complicated, with no drugs available for prevention or treatments. Intestinal ischemia is a key factor in the occurrence and development of enteritis. The effect of ionizing radiation (IR) on intestinal ischemia is unknown. Deficiency of tetrahydrobiopterin (BH4) produced by GTP-cyclohydrolase 1 (Gch1) is important in ischemic diseases. This study focused on the relationship of Gch1/BH4 between intestinal ischemia in radiation enteritis. BH4 levels were analyzed by high-performance liquid chromatography in humans and rats after radiotherapy. Intestinal blood perfusion was measured by laser doppler flow imaging. Vascular ring tests determined the diastolic functions of rat mesenteric arteries. Gene, protein, and immunohistochemical staining experiments and inhibitor interventions were used to investigate Gch1 and endothelial NOS (eNOS) in rat mesenteric arteries and endothelial cells. The results showed that IR decreased BH4 levels in patients and rats after radiotherapy and decreased intestinal blood perfusion in rats. The degree of change in intestinal ischemia was consistent with intestinal villus injury. Gch1 mRNA and protein levels and nitric oxide (NO) production significantly decreased, while eNOS uncoupling in arterial and vascular endothelial cells strongly increased. BH4 supplementation improved eNOS uncoupling and NO levels in vascular endothelia after IR. The results of this study showed that downregulation of Gch1 in intestinal blood vessels after IR is an important target in RE. BH4 supplementation may prevent intestinal ischemia and improve vascular endothelial function after IR. These findings have clinical significance for the prevention and treatment of RE.

Vasodilation activity of dipfluzine metabolites in isolated rat basilar arteries and their underlying mechanisms

Identifying the metabolites of a drug has become an indispensable task in the development of new drugs. Dipfluzine (Dip) is a promising candidate for the treatment of cerebral vascular diseases and has 5 metabolites (M1∼M5) in rat urine and liver microsomes, but their biological activity is still unknown. Because selective cerebral vasodilation is a main role of Dip, we investigated the vasodilation of Dip and its 5 metabolites in isolated Sprague-Dawley (SD) male rat basilar arteries preconstricted with high-K⁺ or 5-HT. The results showed that only M1 possessed concentration-dependent inhibitory activity on the vasoconstriction of arteries with or without the endothelium, and M1 has a more potent vasodilatory effect than Dip on both contraction models. Like Dip, the vasodilatory mechanisms of M1 may be not only related to receptor-operated and voltage-dependent calcium ion channels of smooth muscle cells but also to the release of NO and EDHF from endothelial cells and the opening of Ca²⁺-activated K⁺ channels and ATP-sensitive potassium ion channels. Unlike Dip, the vasodilation mechanism of M1 is also related to the opening of voltage-sensitive K⁺ channel. Together with more selectivity to non-VDCC than Dip, this may partially explain why M1 has stronger vasodilatory effects than Dip. The mechanisms of vasodilation of Dip and M1 may result from the combined action of these or other factors, especially blocking non-endothelium dependent non-VDCC and endothelium dependent IK_Ca channels. These results point to the possibility that M1 provides synergism for the clinical use of Dip, which may inform the synthesis of new drugs.

Apelin inhibits an endothelium-derived hyperpolarizing factor-like pathway in rat cerebral arteries

Apelin has complex vasomotor actions inasmuch as the peptide may cause either vasodilation or vasoconstriction depending on the vascular bed and experimental conditions. In cerebral arteries, apelin inhibits endothelium-dependent relaxations mediated by nitric oxide (NO); however, its effects on relaxation to other endothelium-derived substances (e.g. prostacyclin, endothelium-derived hyperpolarizing factors(s) (EDHF)) are unknown. The present study was designed to determine effects of apelin on endothelium-dependent relaxations that are independent of NO in rat cerebral arteries. In arterial rings contracted with 5-HT, A23187 caused endothelium-dependent relaxation that was unaffected by inhibitors of eNOS, guanylyl cyclase or cyclooxygenase, but was attenuated by MS-PPOH, a selective inhibitor of cytochrome P450 catalyzed synthesis of epoxyeicosatrienoic acids (EETs) and by 14,15-EE(Z)E, an EET-receptor antagonist. Apelin inhibited A23187-induced relaxation, as well as relaxations evoked by exogenous 11,12- and 14,15-EET. These effects of apelin were mimicked by the selective BK_Ca channel blocker, iberiotoxin. The APJ receptor antagonist, F13A abolished the effects of apelin on A23187-induced relaxations. Both 11,12- and 14,15-EET also increased BK_Ca channel current density in isolated cerebral artery smooth muscle cells, effects that were inhibited in a similar manner by apelin and iberiotoxin. These findings provide evidence that apelin impairs endothelium-dependent relaxation of cerebral arteries by inhibiting an NO-independent pathway (i.e. "EDHF-like") involving activation of smooth muscle cell BK_Ca channels by endothelium-derived EETs. Inhibition of such pathway may create an environment favoring vasoconstriction in cerebral arteries.

TRAIL inhibits oxidative stress in human aortic endothelial cells exposed to pro-inflammatory stimuli

Studies suggest that tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has vasoprotective potential, as low levels of TRAIL cause accelerated vascular calcification, whereas exogenous TRAIL administration exhibits anti-atherosclerotic activity. The mechanism of TRAIL-mediated vasoprotection remains unclear. We studied the effects of TRAIL (100 ng/ml) on human aortic endothelial cells (HAECs) exposed to pro-atherogenic conditions; (a) oscillatory shear stress (±10 dynes/cm2 ) using the ibidi µ-slide fluidic system; (b) pro-inflammatory injury, that is, tumor necrosis factor alpha (TNF-α, 100 ng/ml) and hyperglycemia (30 mM d-glucose). End-points examined included inflammatory gene expression and reactive oxygen species (ROS) formation. TRAIL shifted the net gene expression toward an antioxidant phenotype in HAECs exposed to oscillatory shear stress. TRAIL significantly reduced ROS formation in HAECs exposed to both TNF-α and hyperglycemia. Therefore, TRAIL appears to confer atheroprotective effects on the endothelium, at least in part, by reducing oxidative stress.

Quercetin Inhibited Endothelial Dysfunction and Atherosclerosis in Apolipoprotein E-Deficient Mice: Critical Roles for NADPH Oxidase and Heme Oxygenase-1

NADPH oxidase-dependent superoxide (O₂^·-) production and oxidative stress play important roles in endothelial dysfunction and atherosclerosis. Herein, we investigated the potential effects of dietary quercetin, a flavonoid derived in the diet from vegetables and fruit, on vascular endothelial function and atherosclerosis in the high-fat diet (HFD)-fed apolipoprotein E-deficient (ApoE^-/-) mice. Dietary quercetin treatment significantly suppressed endothelial dysfunction and aortic atherosclerosis in HFD-fed ApoE^-/- mice (P < 0.05, all cases). Mechanistic studies demonstrated that dietary quercetin significantly attenuated p47phox expression and inhibited NADPH oxidase-derived oxidative stress in the aortas of HFD-fed ApoE^-/- mice, while the expression and activity of antioxidant enzyme heme oxygenase-1 (HO-1) was enhanced after quercetin treatment (P < 0.05, all cases). In vitro, it was found that quercetin significantly attenuated NADPH oxidase-derived O₂^·- formation (75 ± 5.6% for quercetin versus 100 ± 6.0% for the control group, P < 0.01) in endothelial cells through induction of HO-1. In addition, the favorable effects of quercetin on oxidant (i.e., H₂O₂)-induced endothelial dysfunction could be eliminated by tin protoporphyrin IX (an HO-1 inhibitor) or HO-1-specific siRNA. Our results demonstrated the critical roles of NADPH oxidase and HO-1 for the indirect antioxidant properties of quercetin in vascular diseases.

NF-κB inhibition prevents acute shear stress-induced inflammation in the saphenous vein graft endothelium

The long saphenous vein (LSV) is commonly used as a conduit in coronary artery bypass grafting. However, long term patency remains limited by the development of vascular inflammation, intimal hyperplasia and accelerated atherosclerosis. The impact of acute exposure of venous endothelial cells (ECs) to acute arterial wall shear stress (WSS) in the arterial circulation, and the subsequent activation of inflammatory pathways, remain poorly defined. Here, we tested the hypothesis that acute exposure of venous ECs to high shear stress is associated with inflammatory responses that are regulated by NF-κB both in-vitro and ex-vivo. Analysis of the LSV endothelium revealed that activation of NF-κB occurred within 30 min after exposure to arterial rates of shear stress. Activation of NF-κB was associated with increased levels of CCL2 production and enhanced binding of monocytes in LSVECs exposed to 6 h acute arterial WSS. Consistent with this, ex vivo exposure of LSVs to acute arterial WSS promoted monocyte interactions with the vessel lumen. Inhibition of the NF-κB pathway prevented acute arterial WSS-induced CCL2 production and reduced monocyte adhesion, both in vitro and in human LSV ex vivo, demonstrating that this pathway is necessary for the induction of the acute arterial WSS-induced pro-inflammatory response. We have identified NF-κB as a critical regulator of acute endothelial inflammation in saphenous vein in response to acute arterial WSS. Localised endothelial-specific inhibition of the NF-κB pathway may be beneficial to prevent vein graft inflammation and consequent failure.

Dihydromyricetin Improves Endothelial Dysfunction in Diabetic Mice via Oxidative Stress Inhibition in a SIRT3-Dependent Manner

Dihydromyricetin (DHY), a flavonoid component isolated from Ampelopsis grossedentata, exerts versatile pharmacological activities. However, the possible effects of DHY on diabetic vascular endothelial dysfunction have not yet been fully elucidated. In the present study, male C57BL/6 mice, wild type (WT) 129S1/SvImJ mice and sirtuin 3 (SIRT3) knockout (SIRT3^-/-) mice were injected with streptozotocin (STZ, 60 mg/kg/day) for 5 consecutive days. Two weeks later, DHY were given at the doses of 250 mg/kg by gavage once daily for 12 weeks. Fasting blood glucose (FBG) and glycosylated hemoglobin (HbA1c) level, endothelium-dependent relaxation of thoracic aorta, reactive oxygen species (ROS) production, SIRT3, and superoxide dismutase 2 (SOD2) protein expressions, as well as mitochondrial Deoxyribonucleic Acid (mtDNA) copy number, in thoracic aorta were detected. Our study found that DHY treatment decreased FBG and HbA1c level, improved endothelium-dependent relaxation of thoracic aorta, inhibited oxidative stress and ROS production, and enhanced SIRT3 and SOD2 protein expression, as well as mtDNA copy number, in thoracic aorta of diabetic mice. However, above protective effects of DHY were unavailable in SIRT3^-/- mice. The study suggested DHY improved endothelial dysfunction in diabetic mice via oxidative stress inhibition in a SIRT3-dependent manner.

The effect of nicorandil in patients with cardiac syndrome X: A meta-analysis of randomized controlled trials

BACKGROUND

The prevalence of cardiac syndrome X (CSX) is considerable. Some patients show recurrent angina attacks and have a poor prognosis. However, the knowledge of CSX pathophysiological mechanism is still limited, and the treatment fails to achieve a satisfactory suppression of symptoms. Nicorandil has a beneficial effect on improving coronary microvascular dysfunction (CMD). This study aims to evaluate the clinical effects and safety of nicorandil on CSX patients.

METHODS

The Cochrane Library, Pubmed, EMBASE, ClinicalTrials.gov and 4 Chinese databases were searched to identify relevant studies. The Cochrane "Risk of bias" tool was used to assess the methodological quality of eligible studies. Meta-analysis was performed by RevMan 5.3 software. The Eggers test and meta-regression were performed by software Stata 14.0. Quality of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

RESULTS

Twenty four randomized controlled trials (RCTs) involving 2323 patients were included. Most of the included studies were classified as having an unclear risk of bias because of poor reported methodology. The main outcomes are angina symptoms improvement, resting electrocardiogram (ECG) improvement, treadmill test result, and endothelial function. Meta-analysis showed that nicorandil had some benefit on improving angina symptoms (RR 1.24, 95% CI 1.19 to 1.29, I = 20%, P < .00001), resting ECG (RR = 1.24, 95% IC: 1.15 to 1.33, I = 0%, P < .00001), and prolonged the time to 1 mm ST-segment depression in treadmill test result (WMD = 38.41, 95% IC: 18.46 to 58.36, I = 0%, P = .0002). Besides nicorandil could reduce the level of endothelin-1 (ET-1) (SMD = -2.22, 95% IC: -2.61 to -1.83, I = 77%, P < .00001) and increase the level of nitric oxide (NO) (WMD = 27.45, 95% IC: 125.65 to 29.24, I = 81%, P < .00001). No serious adverse drug event was reported. The Eggers test showed that significant statistical publication bias was detected (Eggers test P = .000). The quality of evidence ranged from very low to low.

CONCLUSIONS

Nicorandil shows the potential of improving angina symptoms, ECG, and endothelial dysfunction in patients with CSX. However, there is insufficient evidence for the clinical benefits of nicorandil due to the very low-quality evidence.

Albumin as a drug: its biological effects beyond volume expansion

Albumin is the most abundant and perhaps most important protein in human blood. Research has identified many of albumin's possible roles in modulating acid-base balance, modifying inflammation, maintaining vascular endothelial integrity, and binding endogenous and exogenous compounds. Albumin plays a key role in the homeostasis of vascular endothelium, offering protection from inflammation and damage to the glycocalyx. Albumin binds a diverse range of compounds. It transports, delivers and clears drugs, plus it helps with uptake, storage and disposal of potentially harmful biological products. The biological effects of albumin in critical illness are incompletely understood, but may enhance its clinical role beyond use as an intravenous fluid. In this article, we summarise the evidence surrounding albumin's biological and physiological effects beyond its use for plasma volume expansion, and explore potential mechanistic effects of albumin as a disease modifier in patients with critical illness.

Improvement in Angiotensin 1-7 precedes and correlates with improvement in Arterial stiffness and endothelial function following Renin-Angiotensin system inhibition in type 2 diabetes with newly diagnosed hypertension

BACKGROUND AND AIM

Studies in cell cultures and animal models have revealed the possible pathophysiological factors associated with vascular endothelial dysfunction. However, the same in human subjects has not been clearly established. The current study uses a novel approach to identify the factors associated with endothelial function and arterial function by altering these vascular parameters using Angiotensin-Converting-Enzyme (ACE) inhibition.

METHODS

Diabetic patients with newly diagnosed hypertension (n = 60) were recruited for the study. Flow-mediated-dilation (FMD), carotid-femoral (cf), carotid-radial (cr) Pulse-wave-velocity (PWV), Augmentation-Index, Carotid-Intima-Media-Thickness (CIMT), serum levels of Renin, Angiotensin II (AngII), Angiotensin-Converting-Enzyme2 (ACE2), Angiotensin1-7 (Ang1-7), E-selectin, Vascular-Cell-Adhesion-Molecule-1 (VCAM-1), Highly-sensitive-C-Reactive-Protein (hsCRP) and Interleukin-10 were measured at baseline (V1), after 1 week (V2) and 3 months (V3) of ACE inhibition in patients of diabetes with newly diagnosed hypertension. The amplitude of change after 1 week (V₂-V₁) and 3 months (V₃-V₁) for the clinical and various parameters were correlated with the change in endothelial function and arterial stiffness.

RESULTS

Carotid radial-PWV_V2-V1 (p = 0.001) and Ang1-7_V2-V1 (p = 0.01) emerged as independent predictors of FMD_V2-V1. Renin_V2-V1 and VCAM-1_V2-V1 independently predicted E-selectin_V2-V1 [(p = 0.01) and (p = 0.001), respectively]. ACE 2_V2-V1 was the only independent predictor of cf-PWV_V2-V1. The same parameters remained as independent predictors of the respective vascular factors after 3 months of ACE inhibition.

CONCLUSION

The study highlights the role of AngII/Ang1-7 balance in alteration of endothelial function and central arterial stiffness in humans in addition to identifying the interrelationship between the renin-angiotensin-aldosterone-system components and clinically ascertainable parameters.

Knockdown of LINC00657 inhibits ox-LDL-induced endothelial cell injury by regulating miR-30c-5p/Wnt7b/β-catenin

Long noncoding RNAs (lncRNAs) play pivotal roles in the pathogenesis, development, and treatment of atherosclerosis (AS). The endothelial cell injury is a feature of AS. However, the role and mechanism of lncRNA LINC00657 in oxidized low-density lipoprotein (ox-LDL)-induced endothelial cell injury remain unclear. The serum samples were collected from 32 AS patients and normal volunteers. Ox-LDL-treated human umbilical vein endothelial cells (HUVEC) were used for the experiments in vitro. The levels of LINC00657, microRNA (miR)-30c-5p and Wnt family member 7B (Wnt7b) were measured by quantitative real-time polymerase chain reaction or western blot. The expression levels of proteins in Wnt7b/β-catenin pathway or endothelial-mesenchymal transition (EndMT) were detected by western blot. The secretion of inflammatory cytokine was examined by enzyme linked immunosorbent assay (ELISA). Cell viability and apoptosis were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide, flow cytometry, and western blot. The target association of miR-30c-5p and LINC00657/Wnt7b was analyzed via dual-luciferase reporter assay and RNA pull-down assay. LINC00657 expression was increased in AS serum and ox-LDL-treated HUVEC cells. LINC00657 knockdown suppressed ox-LDL-induced Wnt7b/β-catenin activation, EndMT, inflammatory response, and apoptosis in HUVEC cells. MiR-30c-5p was bound to LINC00657 and it knockdown reversed the role of LINC00657 inhibition in ox-LDL-induced HUVEC cell injury. MiR-30c-5p targeted Wnt7b to inhibit ox-LDL-induced Wnt7b/β-catenin activation, EndMT, inflammatory response, and apoptosis in HUVEC cells. Silence of LINC00657 repressed ox-LDL-induced injury via inhibiting EndMT, inflammatory response, and apoptosis in HUVEC cells by regulating miR-30c-5p/Wnt7b/β-catenin, indicating a potential target for treatment of AS.

Albumin as a drug: its biological effects beyond volume expansion

Albumin is the most abundant and perhaps most important protein in human blood. Research has identified many of albumin's possible roles in modulating acid-base balance, modifying inflammation, maintaining vascular endothelial integrity, and binding endogenous and exogenous compounds. Albumin plays a key role in the homeostasis of vascular endothelium, offering protection from inflammation and damage to the glycocalyx. Albumin binds a diverse range of compounds. It transports, delivers and clears drugs, plus it helps with uptake, storage and disposal of potentially harmful biological products. The biological effects of albumin in critical illness are incompletely understood, but may enhance its clinical role beyond use as an intravenous fluid. In this article, we summarise the evidence surrounding albumin's biological and physiological effects beyond its use for plasma volume expansion, and explore potential mechanistic effects of albumin as a disease modifier in patients with critical illness.

Endothelial Nitric Oxide Suppresses Action-Potential-Like Transient Spikes and Vasospasm in Small Resistance Arteries

Endothelial dysfunction in small arteries is a ubiquitous, early feature of cardiovascular disease, including hypertension. Dysfunction reflects reduced bioavailability of endothelium-derived nitric oxide (NO) and depressed endothelium-dependent hyperpolarization that enhances vasoreactivity. We measured smooth muscle membrane potential and tension, smooth muscle calcium, and used real-time quantitative polymerase chain reaction in small arteries and isolated tubes of endothelium to investigate how dysfunction enhances vasoreactivity. Rat nonmyogenic mesenteric resistance arteries developed vasomotion to micromolar phenylephrine (α1-adrenoceptor agonist); symmetrical vasoconstrictor oscillations mediated by L-type voltage-gated Ca2+ channels (VGCCs). Inhibiting NO synthesis abolished vasomotion so nanomolar phenylephrine now stimulated rapid, transient depolarizing spikes in the smooth muscle associated with chaotic vasomotion/vasospasm. Endothelium-dependent hyperpolarization block also enabled phenylephrine-vasospasm but without spikes or chaotic vasomotion. Depolarizing spikes were Ca2+-based and abolished by either T-type or L-type VGCCs blockers with depressed vasoconstriction. Removing NO also enabled transient spikes/vasoconstriction to Bay K-8644 (L-type VGCC activator). However, these were abolished by the L-type VGCC blocker nifedipine but not T-type VGCC block. Phenylephrine also initiated T-type VGCC-transient spikes and enhanced vasoconstriction after NO loss in nonmyogenic arteries from spontaneously hypertensive rats. In contrast to mesenteric arteries, myogenic coronary arteries displayed transient spikes and further vasoconstriction spontaneously on loss of NO. T-type VGCC block abolished these spikes and additional vasoconstriction but not myogenic tone. Therefore, in myogenic and nonmyogenic small arteries, reduced NO bioavailability engages T-type VGCCs, triggering transient depolarizing spikes in normally quiescent vascular smooth muscle to cause vasospasm. T-type block may offer a means to suppress vasospasm without inhibiting myogenic tone mediated by L-type VGCCs.

Capsaicin Causes Vasorelaxation of Rat Aorta through Blocking of L-type Ca2+ Channels and Activation of CB1 Receptors

The aim of this work was to determine whether Capsaicin may exert a vascular regulation through the activation of CB₁ and/or CB₂ receptors causing vasorelaxation in the rat aorta. Our results show the location of TRPV1 mainly in the endothelial and smooth muscle cells membrane. Nevertheless, Capsaicin caused vasorelaxation of this artery through a mechanism independent of TRPV1, since the specific antagonists Capsazepine and SB-366791 did not block the effect of Capsaicin. Because the significant expression of CB₁ and CB₂ receptors has been previously reported in the rat aorta, we used antagonists for these two receptors prior to the addition of Capsaicin. In these experiments, we found that the inhibition of CB₁ using AM281, decreases the vasorelaxant effect caused by Capsaicin. On the other hand, the vasorelaxant effect is not altered in the presence of the CB₂ receptor antagonist AM630. Furthermore, a partial decrease of the effect of Capsaicin was also seen when L-type calcium channels are blocked. A complete block of Capsaicin-induced vasorelaxation was achieved using a combination of Verapamil and AM281. In accordance to our results, Capsaicin-induced vasorelaxation of the rat aorta is neither dependent of TRPV1 or CB₂ receptors, but rather it is strongly suggested that a tandem mechanism between inactivation of L-type calcium channels and the direct activation of CB₁ receptors is involved. These findings are supported by CB₁ docking simulation which predicted a binding site on CB₁ receptors for Capsaicin.

Autophagy protein ATG7 is a critical regulator of endothelial cell inflammation and permeability

Endothelial cell (EC) inflammation and permeability are critical pathogenic mechanisms in many inflammatory conditions including acute lung injury. In this study, we investigated the role of ATG7, an essential autophagy regulator with no autophagy-unrelated functions, in the mechanism of EC inflammation and permeability. Knockdown of ATG7 using si-RNA significantly attenuated thrombin-induced expression of proinflammatory molecules such as IL-6, MCP-1, ICAM-1 and VCAM-1. Mechanistic study implicated reduced NF-κB activity in the inhibition of EC inflammation in ATG7-silenced cells. Moreover, depletion of ATG7 markedly reduced the binding of RelA/p65 to DNA in the nucleus. Surprisingly, the thrombin-induced degradation of IκBα in the cytosol was not affected in ATG7-depleted cells, suggesting a defect in the translocation of released RelA/p65 to the nucleus in these cells. This is likely due to suppression of thrombin-induced phosphorylation and thereby inactivation of Cofilin1, an actin-depolymerizing protein, in ATG7-depleted cells. Actin stress fiber dynamics are required for thrombin-induced translocation of RelA/p65 to the nucleus, and indeed our results showed that ATG7 silencing inhibited this response via inactivation of Cofilin1. ATG7 silencing also reduced thrombin-mediated EC permeability by inhibiting the disassembly of VE-cadherin at adherens junctions. Together, these data uncover a novel function of ATG7 in mediating EC inflammation and permeability, and provide a mechanistic basis for the linkage between autophagy and EC dysfunction.

The soluble VEGF receptor sFlt-1 contributes to endothelial dysfunction in IgA nephropathy

Endothelial injury is a common manifestation in IgA nephropathy (IgAN). After the previous identification of the upregulated soluble fms-like tyrosine kinase-1 (sFlt-1) correlated with endothelial injury in IgAN, in the present study, we further explored the role of sFlt-1 in endothelial injury in IgAN. We enrolled 72 patients with IgAN and detected the sFlt-1 levels. The polymeric IgA1 (pIgA1) complexes were isolated from the pooled plasma samples of another 10 patients with IgAN. Apoptosis proteins were detected in cultured human umbilical vein endothelial cells (HUVECs) with the stimulation of recombinant sFlt-1 or the caspase-9 inhibitor Z-LEHD-FMK. We identified there were positive correlations between sFlt-1 and IgA-IgG complex as well as vWF levels in patients with IgAN. The sFlt-1 levels in HUVECs were significantly upregulated by pIgA1 complex derived from IgAN patients in a concentration-dependent manner. The proliferation ability of HUVECs was damaged when stimulated with sFlt-1 protein in a time- and dose- dependent manner. And the apoptosis rate was up-regulated significantly as the stimulation concentrations of sFlt-1 increased. We found sFlt-1 challenge could significantly increase the expression of vWF. In addition, sFlt-1 increased the levels of caspase-9, caspase-3, Bax and mitochondrial membrane potential; facilitated the release of cytochrome C from mitochondria to cytoplasma. In contrast, Z-LEHD-FMK attenuated high sFlt-1-induced HUVECs apoptosis. In conclusion, our study demonstrated that sFlt-1 expression was up-regulated by the challenge of pIgA1 complex derived from patients with IgAN. Furthermore, increased sFlt-1 facilitated human umbilical vein endothelial cells apoptosis via the mitochondrial-dependent pathway.

Targeting Endothelial Dysfunction in Eight Extreme-Critically Ill Patients with COVID-19 Using the Anti-Adrenomedullin Antibody Adrecizumab (HAM8101)

Recently, the stabilization of the endothelium has been explicitly identified as a therapeutic goal in coronavirus disease 2019 (COVID-19). Adrecizumab (HAM8101) is a first-in-class humanized monoclonal anti-Adrenomedullin (anti-ADM) antibody, targeting the sepsis- and inflammation-based vascular and capillary leakage. Within a "treatment on a named-patient basis" approach, Adrecizumab was administered to eight extreme-critically ill COVID-19 patients with acute respiratory distress syndrome (ARDS). The patients received a single dose of Adrecizumab, which was administered between 1 and 3 days after the initiation of mechanical ventilation. The SOFA (median 12.5) and SAPS-II (median 39) scores clearly documented the population at highest risk. Moreover, six of the patients suffered from acute renal failure, of whom five needed renal replacement therapy. The length of follow-up ranged between 13 and 27 days. Following the Adrecizumab administration, one patient in the low-dose group died at day 4 due to fulminant pulmonary embolism, while four were in stable condition, and three were discharged from the intensive care unit (ICU). Within 12 days, the SOFA score, as well as the disease severity score (range 0-16, mirroring critical resources in the ICU, with higher scores indicating more severe illness), decreased in five out of the seven surviving patients (in all high-dose patients). The PaO2/FiO2 increased within 12 days, while the inflammatory parameters C-reactive protein, procalcitonin, and interleukin-6 decreased. Importantly, the mortality was lower than expected and calculated by the SOFA score. In conclusion, in this preliminary uncontrolled case series of eight shock patients with life-threatening COVID-19 and ARDS, the administration of Adrecizumab was followed by a favorable outcome. Although the non-controlled design and the small sample size preclude any definitive statement about the potential efficacy of Adrecizumab in critically ill COVID-19 patients, the results of this case series are encouraging.

Allisartan Isoproxil Improves Endothelial Function and Vascular Damage in Patients with Essential Hypertension: A Single-Center, Open-Label, Randomized Controlled Trial

INTRODUCTION

Allisartan isoproxil is a novel angiotensin II type 1 receptor antagonist that has been confirmed to lower blood pressure and protect target organs effectively. However, its role in improving endothelial function and vascular damage has not been investigated yet.

METHODS

Patients with initially diagnosed mild essential hypertension (BP ranging from 140/90 to 159/99 mmHg) with age from 25-75 years were randomly assigned 1:1 to either the allisartan group (allisartan 240 mg/day and lifestyle modification) or the lifestyle modification group and were followed up for 30 days. Flow-mediated dilation (FMD), brachial-ankle pulse wave velocity (baPWV) and endothelial microparticles (EMPs) were measured for evaluation of endothelial function and vascular damage. In addition, we enrolled 36 normotensive individuals as healthy control.

RESULTS

Seventy-two mildly hypertensive patients were enrolled in this study. After 30 days of treatment, a significant increase in FMD was observed in the allisartan group (0.9 ± 0.7%, p < 0.001) and remained unchanged in the lifestyle modification group, but the difference between the two groups did not reach statistical significance (p = ns). EMPs, baPWV, SBP and DBP decreased by 251.0 ± 255.9 counts/μl (p < 0.001), 102.8 ± 84.2 cm/s (p < 0.001), 13.20 ± 3.9 mmHg (p < 0.001) and 9.35 ± 2.5 mmHg (p < 0.001), respectively, in the allisartan group, while by 21.3 ± 84.3 counts/μl (p = ns), 0.4 ± 22.0 cm/s (p = ns), 3.2 ± 6.0 mmHg (p < 0.01) and 1.0 ± 2.5 mmHg (p = ns), respectively, in the lifestyle modification group. All of the indexes above achieved statistical significance between the allisartan and lifestyle modification groups (p < 0.05). Besides, after 30 days of allisartan administration baPWV and EMPs were comparable to those measured in the healthy control group, while the difference in SBP, DBP and FMD remained significant between the allisartan and healthy control groups (p < 0.05).

CONCLUSION

The present study demonstrates for the first time that allisartan isoproxil exerts a favorable effect on improving endothelial function and vascular damage in patients with mild EH, making it a promising drug for management of EH.

CLINICAL TRIAL REGISTRATION

ChiCTR2000032332.

Role of growth hormone signaling pathways in the development of atherosclerosis

OBJECTIVE

The direct actions of growth hormone (GH) in the development of atherosclerosis are unclear. The goal of this study was to characterize GH-induced changes in expression of signaling pathway elements and other proteins that may be related to atherosclerosis.

METHODS

Human umbilical vein endothelial cells (HUVEC) and THP-1, a human acute monocytic leukemia cell line, were stimulated by exposure to 10^-9 M or 10^-8 M human GH with or without pretreatment with a mitogen-activated protein kinase kinase (MEK) 1 inhibitor. Levels of transcripts encoding vascular cell adhesion molecule (VCAM) -1, E-selectin, monocyte chemotactic protein (MCP-1), interleukin (IL) -6, and IL-8 were investigated by reverse transcription (RT) -PCR. For the quantitative adhesion assay, THP-1 cells or human primary monocytes were fluorescently labeled with 3'-O-acetyl-2',7'-bis(carboxyethyl) -4 diacetoxymethyl ester (BCECF/AM). HUVEC treated with human GH were co-incubated with BCECF-labeled THP-1 cells. One hour later, the number of BCECF-labeled THP-1 cells was assessed. An equivalent experiment was performed using BCECF-labeled primary monocytes, and the number of monocytes adhering to HUVEC was counted.

RESULTS

Treatment with hGH increased the levels of E-selectin- and VCAM-1-encoding mRNAs in HUVEC. This effect was attenuated by pretreatment with a MEK1 inhibitor. Furthermore, hGH treatment increased adhesion of BCECF-labeled THP-1 cells or primary monocytes to HUVEC, and this effect was attenuated by pretreatment with a MEK1 inhibitor.

CONCLUSIONS

VCAM-1 and E-selectin expression was stimulated by GH via the mitogen-activated protein kinase pathway, resulting in augmented adhesion of THP-1 cells and monocytes to HUVEC. These data suggested that GH directly stimulates the development of atherosclerosis.

Long-term Mercury Exposure Accelerates the Development of Hypertension in Prehypertensive Spontaneously Hypertensive Rats Inducing Endothelial Dysfunction: the Role of Oxidative Stress and Cyclooxygenase-2

Mercury is a metal widely dispersed in nature that when in contact with human organism, it damages the cardiovascular system. Long-term mercury exposure for 30 days induces endothelial dysfunction without blood pressure changes in normotensive adult rats. However, it is not known whether exposure to mercury can exacerbate endothelial dysfunction and hypertension development in predisposed animals. Thus, we aimed to investigate the effects of long-term mercury exposure on the blood pressure (BP) and in the isolated aortas of young normotensive and prehypertensive spontaneously hypertensive rats (SHRs). Four-week-old male Wistar rats and SHRs were treated daily with mercury chloride (HgCl₂) (1st dose, 4.6 μg/kg; subsequent dose, 0.07 μg/kg/day, im, 30 days) or vehicle. BP was assessed weekly and the vascular reactivity to phenylephrine was evaluated in isolated aorta from rats exposed or not to mercury. Mercury exposure did not affect BP in young Wistar rats but accelerated the development of hypertension in young SHRs. Vascular reactivity to phenylephrine increased only in the aorta from mercury-exposed SHRs. While HgCl₂ exposure in SHRs did not alter nitric oxide production, we observed increased superoxide anion production and decreased superoxide dismutase-1 protein expression, and enhanced cyclooxygenase-2 (COX-2) participation with increased prostaglandin (PGE₂) production and decreased prostacyclin. In the Wistar group, mercury exposure did not alter superoxide anion production or the COX-2 pathway. Mercury exposure accelerated the natural course of hypertension in young SHRs and increased oxidative stress associated with reduced participation of antioxidant enzymes, an activated COX-2 pathway, thereby producing endothelial dysfunction, which is a risk factor in prehypertensive individuals.

Ubiquinol Improves Endothelial Function in Patients with Heart Failure with Reduced Ejection Fraction: A Single-Center, Randomized Double-Blind Placebo-Controlled Crossover Pilot Study

BACKGROUND

Endothelial dysfunction is reportedly associated with worse outcomes in patients with chronic heart failure. Ubiquinol is a reduced form of coenzyme Q10 (CoQ10) that may improve endothelial function.

OBJECTIVE

We assessed the hypothesis that ubiquinol improves peripheral endothelial function in patients with heart failure with reduced ejection fraction (HFrEF).

METHODS

In this randomized, double-blind, placebo-controlled, crossover pilot study, 14 patients with stable HFrEF were randomly and blindly allocated to ubiquinol 400 mg/day or placebo for 3 months. After a 1-month washout period, patients were crossed over to the alternative treatment. Before and after each treatment, we assessed peripheral endothelial function using the reactive hyperemia index (RHI) and analyzed it using the natural logarithm of RHI (LnRHI).

RESULTS

Peripheral endothelial function as assessed by LnRHI tended to improve with ubiquinol 400 mg/day for 3 months (p = 0.076). Original RHI values were also compared, and RHI significantly improved with ubiquinol treatment (pre-RHI 1.57 [interquartile range (IQR) 1.39-1.80], post-RHI 1.74 [IQR 1.63-2.02], p = 0.026), but not with placebo (pre-RHI 1.67 [IQR 1.53-1.85], post-RHI 1.51 [IQR 1.39-2.11], p = 0.198).

CONCLUSIONS

Ubiquinol 400 mg/day for 3 months led to significant improvement in peripheral endothelial function in patients with HFrEF. Ubiquinol may be a therapeutic option for individuals with HFrEF. Large-scale randomized controlled trials of CoQ10 supplementation in patients with HFrEF are needed.

CLINICAL TRIAL REGISTRATION

Japanese University Hospital Medical Information Network (UMIN-ICDR). Clinical Trial identifier number UMIN000012604.

Oxytocin mediated cardioprotection is independent of coronary endothelial function in rats

The cardioprotective effect of oxytocin (OT) has been well established. However, there are no related studies on the role of endothelia in oxytocin-induced cardioprotection. Endothelial dysfunction (ED) model was established by injection of 0.01 % Triton X-100 in the isolated rat heart. Oxytocin pretreatment was conducted at the end of stabilization for 40 min, followed by 30 min global ischemia and 60 min reperfusion to induce I/R injury. Coronary perfusion pressure, hemodynamics and arrhythmia severity scores were measured respectively. High-sensitivity cardiac troponin T (hs-cTnT) was evaluated by enzyme-linked immunosorbent assay. Infarct size was detected by triphenyltetrazolium chloride staining. The morphological changes in coronary endothelium were observed by scanning electron microscopy. Injection of 0.01 % Triton X-100 caused significant reduction of CPP induced by histamine and endothelium removal from scanning electron microscopy, but SNP had no significant effect. Oxytocin pretreatment showed significant recovery in LVDP, ±dp/dt_max, RPP and SI after reperfusion (P <  0.05). Additionally, I/R injury led to a rise of arrhythmia severity score, hs-cTnT and infarct size. No significant differences between ED-OT-I/R and OT-I/R groups were found in arrhythmia severity score, hs-cTnT, and infarct size (P >  0.05). I/R injury exacerbated the decrease in CPP and worsened the migration, deformation, and fracture of coronary endothelium, while oxytocin reversed these injuries. Despite the presence of endothelial damages, oxytocin partially alleviated I/R- and Triton-induced endothelial damages. The cardioprotective effects of oxytocin are independent of endothelial function in alleviating I/R injury and I/R-induced coronary endothelial dysfunction.

Suppression of Ocular Vascular Inflammation through Peptide-Mediated Activation of Angiopoietin-Tie2 Signaling

Persistent inflammation is a complication associated with many ocular diseases. Changes in ocular vessels can amplify disease responses and contribute to vision loss by influencing the delivery of leukocytes to the eye, vascular leakage, and perfusion. Here, we report the anti-inflammatory activity for AXT107, a non-RGD, 20-mer αvβ3 and α5β1 integrin-binding peptide that blocks vascular endothelial growth factor (VEGF)-signaling and activates tyrosine kinase with immunoglobulin and EGF-like domains 2 (Tie2) using the normally inhibitory ligand angiopoietin 2 (Ang2). Tumor necrosis factor α (TNFα), a central inflammation mediator, induces Ang2 release from endothelial cells to enhance its stimulation of inflammation and vascular leakage. AXT107 resolves TNFα-induced vascular inflammation in endothelial cells by converting the endogenously released Ang2 into an agonist of Tie2 signaling, thereby disrupting both the synergism between TNFα and Ang2 while also preventing inhibitor of nuclear factor-κB α (IκBα) degradation directly through Tie2 signaling. This recovery of IκBα prevents nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) nuclear localization, thereby blocking NF-κB-induced inflammatory responses, including the production of VCAM-1 and ICAM-1, leukostasis, and vascular leakage in cell and mouse models. AXT107 also decreased the levels of pro-inflammatory TNF receptor 1 (TNFR1) without affecting levels of the more protective TNFR2. These data suggest that AXT107 may provide multiple benefits in the treatment of retinal/choroidal and other vascular diseases by suppressing inflammation and promoting vascular stabilization.

Mediating effects of platelet-derived extracellular vesicles on PM2.5-induced vascular endothelial injury

At present, PM_2.5 exposure has been considered as a major risk factor for cardiovascular disease. Most studies have focused on the toxic mechanism of PM_2.5 in direct contact with cells or biomolecules, only few studies have reported the toxic mechanism of PM_2.5 mediated by intercellular communication. Extracellular vesicles are the main carriers of intercellular communication and signal transduction in vivo, and play a vital role in the occurrence and development of cardiovascular disease. Therefore, the present research aimed to determine whether platelets-derived extracellular vesicles (P-EVs) secreted from PM_2.5-exposed platelets are transferred into the human umbilical vein endothelial cells (HUVECs) and mediated the PM_2.5-induced vascular endothelial injury by affecting normal cellular function. The result showed that P-EVs secreted from PM_2.5-exposed platelets significantly reduced the proliferation promoting effect of normal P-EVs on vascular endothelium by decreasing the effective factors promoting vascular endothelial growth. Meanwhile, the levels of intercellular adhesion molecules, proinflammatory factors (ICAM-1, IL-6, and TNF-α) and the ROS level of HUVECs were markedly elevated. In addition, the apoptotic rate was increased via up-regulating the protein level of cytochrome-C(Cyt C), Bax, cleaved caspase-3 and down-regulating Bcl-2 in HUVECs, indicating that mitochondrial apoptotic pathway was activated by P-EVs secreted from PM_2.5-exposed platelets. Further, the expression level of P-EVs targeted miRNAs in HUVECs was altered, indicating that miRNAs released from P-EVs were transferred to HUVECs and regulated the cellular function, while PM_2.5 could inhibit this regulatory effect. In summary, these results demonstrate that the P-EVs secreted from PM_2.5-exposed platelets can enter the HUVECs, which mediate the PM_2.5-induced vascular endothelial injury. These findings provide a new perspective and theoretical basis for further exploring the mechanism of cardiovascular damage caused by PM_2.5 exposure.

Efficacy and safety of Danhong injection on endothelial function and inflammatory factors after the percutaneous coronary intervention for coronary heart disease: A protocol of systematic review and meta-analysis of randomized controlled trials

BACKGROUND

To systematically review the effects of Danhong injection on endothelial function and inflammatory factors after the percutaneous coronary intervention (PCI) for coronary heart disease (CHD) and to provide a basis for further research.

METHODS

Through computer retrieval, including PubMed, Embase, the Cochrane Library, CNKI, Wan Fang Data, VIP, SinoMed were retrieved on a computer. Randomized controlled trials (RCTs) on the effects of Danhong injection on endothelial function and inflammatory factors after PCI for CHD were collected in strict accordance with the pre-established inclusion and exclusion criteria. Chinese and English literatures in published from the establishment of each database to December 1, 2019, were retrieved by combining subject headings and free terms. Literatures were screened out by 2 researchers independently, and the risk of bias was assessed by 2 independent researchers by using the assessment tool for risk of bias as described Cochrane systematic reviewer's manual 5.1.0. Statistical analysis was performed by using Stata 14.0 software.

RESULTS

By collecting the existing evidence, this study would determine the effects of Danhong injection on endothelial function and inflammatory factors after PCI for CHD by meta-analysis.

CONCLUSION

Through this study, we will draw a definite conclusion on whether Danhong injection has significant effects on endothelial function and inflammatory factors after PCI for CHD. This conclusion will provide practical and scientific guidance for the use of Danhong injection after PCI for CHD.

PROSPERO REGISTRATION NUMBER

PROSPERO CRD42020165568.

Crotonaldehyde-induced vascular relaxation and toxicity: Role of endothelium and transient receptor potential ankyrin-1 (TRPA1)

INTRODUCTION

Crotonaldehyde (CR) is an electrophilic α,β-unsaturated aldehyde present in foods and beverages and is a minor metabolite of 1,3-butadiene. CR is a product of incomplete combustion, and is at high levels in smoke of cigarettes and structural fires. Exposure to CR has been linked to cardiopulmonary toxicity and cardiovascular disease.

OBJECTIVE

The purpose of this study was to examine the direct effects of CR in murine blood vessels (aorta and superior mesenteric artery, SMA) using an in vitro system.

METHODS AND RESULTS

CR induced concentration-dependent (1-300 μM) relaxations (75-80%) in phenylephrine (PE) precontracted aorta and SMA. Because the SMA was 20× more sensitive to CR than aorta (SMA EC50 3.8 ± 0.5 μM; aorta EC50 76.0 ± 2.0 μM), mechanisms of CR relaxation were studied in SMA. The CR-induced relaxation at low concentrations (1-30 μM) was inhibited by: 1) mechanically-impaired endothelium; 2) Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME); 3) guanylyl cyclase (GC) inhibitor (ODQ); 4) transient receptor potential ankyrin-1 (TRPA1) antagonist (A967079); and, 5) by non-vasoactive level of nicotine (1 μM). Similarly, a TRPA1 agonist, allyl isothiocyanate (AITC; mustard oil), stimulated SMA relaxation dependent on TRPA1, endothelium, NO, and GC. Consistent with these mechanisms, TRPA1 was present in the SMA endothelium. CR, at higher concentrations (100-300 μM), induced tension oscillations (spasms) and irreversibly impaired contractility (a vasotoxic effect enhanced by impaired endothelium).

CONCLUSIONS

CR relaxation depends on a functional endothelium and TRPA1, whereas vasotoxicity is enhanced by endothelium dysfunction. Thus, CR is both vasoactive and vasotoxic along a concentration continuum.

Trimethylamine-N-Oxide Promotes Age-Related Vascular Oxidative Stress and Endothelial Dysfunction in Mice and Healthy Humans

Age-related vascular endothelial dysfunction is a major antecedent to cardiovascular diseases. We investigated whether increased circulating levels of the gut microbiome-generated metabolite trimethylamine-N-oxide induces endothelial dysfunction with aging. In healthy humans, plasma trimethylamine-N-oxide was higher in middle-aged/older (64±7 years) versus young (22±2 years) adults (6.5±0.7 versus 1.6±0.2 µmol/L) and inversely related to brachial artery flow-mediated dilation (r2=0.29, P<0.00001). In young mice, 6 months of dietary supplementation with trimethylamine-N-oxide induced an aging-like impairment in carotid artery endothelium-dependent dilation to acetylcholine versus control feeding (peak dilation: 79±3% versus 95±3%, P<0.01). This impairment was accompanied by increased vascular nitrotyrosine, a marker of oxidative stress, and reversed by the superoxide dismutase mimetic 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl. Trimethylamine-N-oxide supplementation also reduced activation of endothelial nitric oxide synthase and impaired nitric oxide-mediated dilation, as assessed with the nitric oxide synthase inhibitor L-NAME (NG-nitro-L-arginine methyl ester). Acute incubation of carotid arteries with trimethylamine-N-oxide recapitulated these events. Next, treatment with 3,3-dimethyl-1-butanol for 8 to 10 weeks to suppress trimethylamine-N-oxide selectively improved endothelium-dependent dilation in old mice to young levels (peak: 90±2%) by normalizing vascular superoxide production, restoring nitric oxide-mediated dilation, and ameliorating superoxide-related suppression of endothelium-dependent dilation. Lastly, among healthy middle-aged/older adults, higher plasma trimethylamine-N-oxide was associated with greater nitrotyrosine abundance in biopsied endothelial cells, and infusion of the antioxidant ascorbic acid restored flow-mediated dilation to young levels, indicating tonic oxidative stress-related suppression of endothelial function with higher circulating trimethylamine-N-oxide. Using multiple experimental approaches in mice and humans, we demonstrate a clear role of trimethylamine-N-oxide in promoting age-related endothelial dysfunction via oxidative stress, which may have implications for prevention of cardiovascular diseases.

Significance of neutrophil microparticles in ischaemia-reperfusion: Pro-inflammatory effectors of endothelial senescence and vascular dysfunction

Endothelial senescence is an emerging cause of vascular dysfunction. Because microparticles are effectors of endothelial inflammation and vascular injury after ischaemia-reperfusion, we examined leucocyte-derived microparticles of spleen origin as possible contributors. Microparticles were generated from primary rat splenocytes by either lipopolysaccharide or phorbol-myristate-acetate/calcium ionophore, under conditions mimicking innate and adaptive immune responses. Incubation of primary porcine coronary endothelial cells with either type of microparticles, but not with those from unstimulated splenocytes, leads to a similar threefold raise in senescence-associated β-galactosidase activity within 48 hours, indicating accelerated senescence, to endothelial oxidative stress, and a fivefold and threefold increase in p21 and p16 senescence markers after 24 hours. After 12-hour incubation, the endothelial-dependent relaxation of coronary artery rings was reduced by 50%, at distinct optimal microparticle concentration. In vitro, microparticles were pro-thrombotic by up-regulating the local angiotensin system, by prompting tissue factor activity and a secondary generation of pro-coagulant endothelial microparticles. They initiated an early pro-inflammatory response by inducing phosphorylation of NF-κB, MAP kinases and Akt after 1 hour, and up-regulated VCAM-1 and ICAM-1 at 24 hours. Accordingly, VCAM-1 and COX-2 were also up-regulated in the coronary artery endothelium and eNOS down-regulated. Lipopolysaccharide specifically favoured the shedding of neutrophil- and monocyte-derived microparticles. A 80% immuno-depletion of neutrophil microparticles reduced endothelial senescence by 55%, indicating a key role. Altogether, data suggest that microparticles from activated splenocytes prompt early pro-inflammatory, pro-coagulant and pro-senescent responses in endothelial cells through redox-sensitive pathways. The control of neutrophil shedding could preserve the endothelium at site of ischaemia-reperfusion-driven inflammation and delay its dysfunction.

Chronic Sildenafil Treatment Improves Vasomotor Function in a Mouse Model of Accelerated Aging

Aging leads to a loss of vasomotor control. Both vasodilation and vasoconstriction are affected. Decreased nitric oxide–cGMP-mediated relaxation is a hallmark of aging. It contributes to vascular disease, notably hypertension, infarction, and dementia. Decreased vasodilation can be caused by aging independently from cardiovascular risk factors. This process that can be mimicked in mice in an accelerated way by activation of the DNA damage response. Genetic deletion of the DNA repair enzyme ERCC1 endonuclease in mice, as in the case of Ercc1^Δ/- mice, can be used as a tool to accelerate aging. Ercc1^Δ/- mice develop age-dependent vasomotor dysfunction from two months after birth. In the present study we tested if chronic treatment with sildenafil, a phosphodiesterase 5 inhibitor that augments NO–cGMP signaling, can reduce the development of vasomotor dysfunction in Ercc1^Δ/- mice. Ercc1^Δ/- mice and wild-type littermates were treated with 10 mg/kg/d of sildenafil from the age of 6 to the age of 14 weeks. Blood pressure and in vivo and ex vivo vasomotor responses were measured at the end of the treatment period. Ercc1^Δ/- mice developed decreased reactive hyperemia, and diminished NO–cGMP-dependent acetylcholine responses. The diminished acetylcholine response involved both endothelial and vascular smooth muscle cell signaling. Chronic sildenafil exclusively improved NO–cGMP signaling in VSMC, and had no effect on endothelium-derived hyperpolarization. Sildenafil also improved KCl hypocontractility in Ercc1^Δ/- mice. All effects were blood pressure-independent. The findings might be of clinical importance for prevention of morbidities related to vascular aging as well as for progeria patients with a high risk of cardiovascular disease.

Mechanisms of enhanced vascular smooth muscle contraction induced by sickle erythrocyte constituents

The mechanisms of the increased vascular tone associated with vaso-occlusive crisis of sickle cell disease have not been clearly defined. The goal of the present study was to examine the role of vascular smooth muscle membrane Na+-K+-ATPase enzyme activity as well as nitric oxide synthase inhibition on the contractile responses induced by sickle erythrocyte constituents. 2 mm ring segments of rabbit carotid arterial ring preparations were placed in 20 ml organ baths containing physiological salt solution (PSS) bubbled with 95% O2, 5% CO2, at 37oC and pH 7.4 and isometric contractions recorded, under an initial load of 2g. Arterial rings were exposed to 50 µl of each erythrocyte constituent at an adjusted haematocrit of 0.6. The magnitude of K+-induced relaxation of 10-7 M phenylephrine (PE)-precontracted rings exposed for 30 minutes to K+-free PSS (which inhibits Na+-K+ pump) was estimated in the absence (control) or presence of RBC constituents (ghosts, erythrocytes or haemoglobin solution) from Hb SS subjects. Secondly, the influence of 20-minute exposure of the rings to SS GHOSTS on acetylcholine-induced, endothelium-dependent relaxation of 10-7 M PE phenylephrine-precontraction (in the absence or presence of L-NAME) was evaluated. Our results show that K+-induced relaxation was significantly and differentially attenuated by erythrocyte constituents (p<0.05) in the order: SS GHOST > SS HBS > SS RBC. NO synthase inhibition with L-NAME further potentiated the enhanced PE contractions induced by SS GHOSTS and caused a greater attenuation of Ach-induced relaxation (compared with SS GHOSTS alone). The results suggest that SS erythrocyte GHOSTS induce enhancement of vascular smooth muscle tone via impairment of vascular Na+-K+ ATPase enzyme activity as well as attenuate endothelium-dependent relaxation. These functional changes in vascular smooth muscle and endothelial function may contribute to the pathophysiology of vaso-occlusive crisis of sickle cell disease.

Relaxation Responses of Ketamine and Propofol to Vasoactive Agents in Streptozotocin-Induced Diabetic Rats

Diabetes mellitus (DM) is a major risk factor for the development of endothelial dysfunction which affects the ability of blood vessels to regulate vascular tone. The study aimed to investigate the mechanisms of vasodilator action of the anaesthetic agents ketamine and propofol in diabetic rat aorta. 30 male Sprague-Dawley rats were randomly divided into two equal groups: (i) non-diabetic control (ii) Streptozotocin-induced diabetic group. DM was induced by a single intra-peritoneal injection of streptozotocin at 50 mg/kg body weight.  Blood samples were taken from the tail vein after 24 hours and tested for glucose level using an automated glucose analyser. A blood glucose ≥10 mmol/L confirmed hyperglycaemia and the development of DM.  Rats were  sacrificed, and the aortae excised.  The vascular responses of  aortic rings from both groups to ketamine, propofol in the presence of  vasoactive agents  were studied using standard organ bath procedures. Ketamine and propofol reduced Phe-induced contraction similarly in the diabetic and control groups. Barium chloride, attenuated the relaxation response to propofol in diabetic aorta when compared to ketamine. 4-aminopyridine significantly attenuated the relaxation response to ketamine and propofol in diabetic aorta. Glibenclamide, significantly reduced  ketamine-induced relaxation in diabetic aorta when compared to propofol. Activation of K+ channels with nicorandil or NS1619 did not affect the relaxation response to ketamine or propofol in diabetic aorta. The results recommend that propofol can be effective in mitigating the consequences of hemodynamic instability in glibenclamide treated diabetics when compared to ketamine. This response is mediated by propofol-induced inhibition of intracellular calcium influx.

The vascular dilatation induced by Hydroxysafflor yellow A (HSYA) on rat mesenteric artery through TRPV4-dependent calcium influx in endothelial cells

ETHNOPHARMACOLOGICAL RELEVANCE

Hydroxysafflor yellow A (HSYA) is the principal constituent of the flowers of Carthamus tinctorius L., a traditional Chinese herbal medicine, which has been used for the treatment of cerebrovascular and cardiovascular diseases due to its property of promoting blood circulation and removing blood stasis. It is dominated in the water extract of Carthamus tinctorius L., which has been used in the clinical treatment for cardiovascular diseases. HSYA exerts a variety of pharmacological efficacy upon the vascular system. However, the underlying mechanisms remain unclear.

AIM OF THE STUDY

To investigate the vascular dilatation effect of HSYA on rat mesenteric artery (MA) and its potential mechanism.

MATERIALS AND METHODS

Adult male Wistar rats were applied to the study. Tension studies were conducted to determine the dilatation activity of HSYA against pre-contracted mesenteric arterial (MA) rings by U 46619 and Phenylephrine (PE). The vascular activities were measured with or without incubation with some selective inhibitors, including L-N(ω)-nitro-L-arginine methyl ester (L-NAME, a nitro oxide synthase inhibitor), HC-067047 (a selective TRPV4 antagonist), BaCl₂ (a Kir channel blocker), and Indomethacin (Indo, a nonselective cyclooxygenase inhibitor), respectively. Immunocytochemistry, Calcium Imaging, NO Production detection, and Western Blot were also employed to further study the underlying mechanism.

RESULTS

HSYA reversed the constriction of MAs induced by U 46619 in a manner of concentration dependency, and the dilatation capability was reversed by L-NAME. This effect was significantly dependent on the intactness of MA endothelium, accompanying an increment of NO production in mesenteric arterial endothelium cells. The increment of NO production was reversed by inhibiting the PKA. Also, the expression of p-eNOS was activated by HSYA shown in Western Blot assays. The cells imaging revealed a significant increase and drop of the influx of Ca²⁺ before and after treatment with HC-067047.

CONCLUSIONS

These findings suggest that HSYA exerts vessel dilation effect on MAs via a TRPV4-dependent influx of Ca²⁺ in endothelium cells, PKA-dependent eNOS phosphorylation and NO production mechanism. The present study indicates that HSYA has the potential to be a future candidate for the treatment of hypertension.

Multicellular 3D Neurovascular Unit Model for Assessing Hypoxia and Neuroinflammation Induced Blood-Brain Barrier Dysfunction

The blood-brain barrier (BBB) is a dynamic component of the brain-vascular interface that maintains brain homeostasis and regulates solute permeability into brain tissue. The expression of tight junction proteins between adjacent endothelial cells and the presence of efflux proteins prevents entry of foreign substances into the brain parenchyma. BBB dysfunction, however, is evident in many neurological disorders including ischemic stroke, trauma, and chronic neurodegenerative diseases. Currently, major contributors to BBB dysfunction are not well understood. Here, we employed a multicellular 3D neurovascular unit organoid containing human brain microvascular endothelial cells, pericytes, astrocytes, microglia, oligodendrocytes and neurons to model the effects of hypoxia and neuroinflammation on BBB function. Organoids were cultured in hypoxic chamber with 0.1% O2 for 24 hours. Organoids cultured under this hypoxic condition showed increased permeability, pro-inflammatory cytokine production, and increased oxidative stress. The anti-inflammatory agents, secoisolariciresinol diglucoside and 2-arachidonoyl glycerol, demonstrated protection by reducing inflammatory cytokine levels in the organoids under hypoxic conditions. Through the assessment of a free radical scavenger and an anti-inflammatory endocannabinoid, we hereby report the utility of the model in drug development for drug candidates that may reduce the effects of ROS and inflammation under disease conditions. This 3D organoid model recapitulates characteristics of BBB dysfunction under hypoxic physiological conditions and when exposed to exogenous neuroinflammatory mediators and hence may have potential in disease modeling and therapeutic development.

Additive effect of erythropoietin use on exercise-induced endothelial activation and hypercoagulability in athletes

Purpose

Recombinant human erythropoietin (rHuEPO) is known to increase thrombotic risk in patients and might have similar effects in athletes abusing the drug. rHuEPO is prohibited by anti-doping legislation, but this risk has not been investigated thoroughly. This analysis was designed to evaluate whether rHuEPO impacts hemostatic profile and endothelial and platelet activation markers in trained subjects, and whether the combination with exercise affects exercise induced alterations.

Methods

This double-blind, randomized, placebo-controlled trial enrolled healthy, trained male cyclists aged 18–50 years. Participants were randomly allocated (1:1) to receive subcutaneous injections of rHuEPO (epoetin-β; mean dose 6000 IU per week) or placebo (0.9% NaCl) for 8 weeks. Subjects performed five maximal exercise tests and a road race, coagulation and endothelial/platelet markers were measured at rest and directly after each exercise effort.

Results

rHuEPO increased P-selectin (+ 7.8% (1.5–14.5), p = 0.02) and E-selectin (+ 8.6% (2.0–15.7), p = 0.01) levels at rest. Maximal exercise tests significantly influenced all measured coagulation and endothelial/platelet markers, and in the rHuEPO group maximal exercise tests led to 15.3% ((7.0–24.3%), p = 0.0004) higher E-selectin and 32.1% ((4.6–66.8%), p = 0.0207) higher Platelet factor 4 (PF4) levels compared to the placebo group.

Conclusion

In conclusion, rHuEPO treatment resulted in elevated E- and P-selectin levels in trained cyclists, indicating enhanced endothelial activation and/or platelet reactivity. Exercise itself induces hypercoagulability, and the combination of rHuEPO and exercise increased E-selectin and PF4 levels more than either intervention alone. Based on this, exercise potentially increases thrombotic risk, a risk that might be enhanced in combination with rHuEPO use.

Electronic supplementary material

The online version of this article (10.1007/s00421-020-04419-0) contains supplementary material, which is available to authorized users.

Anti-Inflammatory Potential of n-3 Polyunsaturated Fatty Acids Enriched Hen Eggs Consumption in Improving Microvascular Endothelial Function of Healthy Individuals-Clinical Trial

The effects of consumption of n-3 polyunsaturated fatty acids (n-3 PUFAs) enriched hen eggs on endothelium-dependent and endothelium-independent vasodilation in microcirculation, and on endothelial activation and inflammation were determined in young healthy individuals. Control group (N = 21) ate three regular hen eggs/daily (249 mg n-3 PUFAs/day), and n-3 PUFAs group (N = 19) ate three n-3 PUFAs enriched hen eggs/daily (1053 g n-3 PUFAs/day) for 3 weeks. Skin microvascular blood flow in response to iontophoresis of acetylcholine (AChID; endothelium-dependent) and sodium nitroprusside (SNPID; endothelium-independent) was assessed by laser Doppler flowmetry. Blood pressure (BP), body composition, body fluid status, serum lipid and free fatty acids profile, and inflammatory and endothelial activation markers were measured before and after respective dietary protocol. Results: Serum n-3 PUFAs concentration significantly increased, AChID significantly improved, and SNPID remained unchanged in n-3 PUFAs group, while none was changed in Control group. Interferon-γ (pro-inflammatory) significantly decreased and interleukin-10 (anti-inflammatory) significantly increased in n-3 PUFAs. BP, fat free mass, and total body water significantly decreased, while fat mass, interleukin-17A (pro-inflammatory), interleukin-10 and vascular endothelial growth factor A significantly increased in the Control group. Other measured parameters remained unchanged in both groups. Favorable anti-inflammatory properties of n-3 PUFAs consumption potentially contribute to the improvement of microvascular endothelium-dependent vasodilation in healthy individuals.

Relaxant Effect of Monoterpene (-)-Carveol on Isolated Human Umbilical Cord Arteries and the Involvement of Ion Channels

Carveol is a monoterpene present in the structure of many plant products. It has a variety of biological activities: antioxidant, anticancer and vasorelaxation. However, studies investigating the effect of monoterpenoids on human vessels have not yet been described. Thus, the present study aimed to characterize the effect of (−)-carveol on human umbilical arteries (HUAs). HUA ring preparations were isolated and subjected to isometric tension recordings of umbilical artery smooth muscle contractions. (−)-Carveol exhibited a significant vasorelaxant effect on KCl and 5-HT-induced contractions, obtaining EC₅₀ values of 344.25 ± 8.4 and 175.82 ± 4.05 µM, respectively. The participation of calcium channels in the relaxation produced by (−)-carveol was analyzed using vessels pre-incubated with (−)-carveol (2000 µM) in a calcium-free medium, where the induction of contractions was abolished. The vasorelaxant effect of (−)-carveol on HUAs was reduced by tetraethylammonium (TEA), which increased the (−)-carveol EC₅₀ to 484.87 ± 6.55 µM. The present study revealed that (−)-carveol possesses a vasorelaxant activity in HUAs, which was dependent on the opening of calcium and potassium channels. These results pave the way for further studies involving the use of monoterpenoids for the vasodilatation of HUAs. These molecules have the potential to treat diseases such as pre-eclampsia, which is characterized by resistance in umbilical arteries.

To beer or not to beer: A meta-analysis of the effects of beer consumption on cardiovascular health

A moderate alcohol consumption is demonstrated to exert a protective action in terms of cardiovascular risk. Although this property seems not to be beverage-specific, the various composition of alcoholic compounds could mediate peculiar effects in vivo. The aim of this study was to evaluate potential beer-mediated effects on the cardiovascular health in humans, using a meta-analytic approach (trial registration number: CRD42018118387). The literature search, comprising all English articles published until November, 30th 2019 in EMBASE, PubMed and Cochrane database included all controlled clinical trials evaluating the cardiovascular effects of beer assumption compared to alcohol-free beer, water, abstinence or placebo. Both sexes and all beer preparations were considered eligible. Outcome parameters were those entering in the cardiovascular risk charts and those related to endothelial dysfunction. Twenty-six trials were included in the analysis. Total cholesterol was significantly higher in beer drinkers compared to controls (14 studies, 3.52 mg/dL, 1.71–5.32 mg/dL). Similar increased levels were observed in high-density lipoprotein (HDL) cholesterol (18 studies, 3.63 mg/dL, 2.00–5.26 mg/dL) and in apolipoprotein A1 (5 studies, 0.16 mg/dL, 0.11–0.21 mg/dL), while no differences were detected in low density lipoprotein (LDL) cholesterol (12 studies, -2.85 mg/dL, -5.96–0.26 mg/dL) and triglycerides (14 studies, 0.40 mg/dL, -5.00–5.80 mg/dL) levels. Flow mediated dilation (FMD) resulted significantly higher in beer-consumers compared to controls (4 studies, 0.65%, 0.07–1.23%), while blood pressure and other biochemical markers of inflammation did not differ. In conclusion, the specific beer effect on human cardiovascular health was meta-analysed for the first time, highlighting an improvement of the vascular elasticity, detected by the increase of FMD (after acute intake), and of the lipid profile with a significant increase of HDL and apolipoprotein A1 serum levels. Although the long-term effects of beer consumption are not still understood, a beneficial effect of beer on endothelial function should be supposed.

Weight change and sulfonylurea therapy are related to 3 year change in microvascular function in people with type 2 diabetes

AIMS/HYPOTHESIS

Although cardiovascular disease is the biggest cause of death in people with diabetes, microvascular complications have a significant impact on quality of life and financial burden of the disease. Little is known about the progression of microvascular dysfunction in the early stages of type 2 diabetes before the occurrence of clinically apparent complications. We aimed to explore the determinants of endothelial-dependent and -independent microvascular function progression over a 3 year period, in people with and without both diabetes and few clinical microvascular complications.

METHODS

Demographics were collected in 154 participants with type 2 diabetes and in a further 99 participants without type 2 diabetes. Skin microvascular endothelium-dependent response to iontophoresis of acetylcholine and endothelium-independent responses to sodium nitroprusside were measured using laser Doppler fluximetry. All assessments were repeated 3 years later.

RESULTS

People with type 2 diabetes had impaired endothelial-dependent microvascular response compared with those without (AUC 93.9 [95% CI 88.1, 99.4] vs 111.9 [102.3, 121.4] arbitrary units [AU] × min, p < 0.001, for those with vs without diabetes, respectively). Similarly, endothelial-independent responses were attenuated in those with diabetes (63.2 [59.2, 67.2] vs 75.1 [67.8, 82.4] AU × min, respectively, p = 0.002). Mean microvascular function declined over 3 years in both groups to a similar degree (p_interaction 0.74 for response to acetylcholine and 0.69 for response to sodium nitroprusside). In those with diabetes, use of sulfonylurea was associated with greater decline (p = 0.022 after adjustment for co-prescriptions, change in HbA_1c and weight), whereas improving glycaemic control was associated with less decline of endothelial-dependent microvascular function (p = 0.03). Otherwise, the determinants of microvascular decline were similar in those with and without diabetes. The principal determinant of change in microvascular function in the whole population was weight change over 3 years, such that those that lost ≥5% weight had very little decline in either endothelial-dependent or -independent function compared with those that were weight stable, whereas those who gained weight had a greater decline in function (change in endothelial-dependent function was 1.2 [95% CI -13.2, 15.7] AU × min in those who lost weight; -15.8 [-10.5, -21.0] AU × min in those with stable weight; and -37.8 [-19.4, -56.2] AU × min in those with weight gain; p_trend < 0.001). This association of weight change with change in endothelial function was driven by people with diabetes; in people without diabetes, the relationship was nonsignificant.

CONCLUSIONS/INTERPRETATION

Over 3 years, physiological change in weight was the greatest predictor of change in microvascular function.

Application of Oxidative Stress to a Tissue-Engineered Vascular Aging Model Induces Endothelial Cell Senescence and Activation

Clinical studies have established a connection between oxidative stress, aging, and atherogenesis. These factors contribute to senescence and inflammation in the endothelium and significant reductions in endothelium-dependent vasoreactivity in aged patients. Tissue-engineered blood vessels (TEBVs) recapitulate the structure and function of arteries and arterioles in vitro. We developed a TEBV model for vascular senescence and examined the relative influence of endothelial cell and smooth muscle cell senescence on vasoreactivity. Senescence was induced in 2D endothelial cell cultures and TEBVs by exposure to 100 µM H₂O₂ for one week to model chronic oxidative stress. H₂O₂ treatment significantly increased senescence in endothelial cells and mural cells, human neonatal dermal fibroblasts (hNDFs), as measured by increased p21 levels and reduced NOS3 expression. Although H₂O₂ treatment induced senescence in both the endothelial cells (ECs) and hNDFs, the functional effects on the vasculature were endothelium specific. Expression of the leukocyte adhesion molecule vascular cell adhesion molecule 1 (VCAM-1) was increased in the ECs, and endothelium-dependent vasodilation decreased. Vasoconstriction and endothelium-independent vasodilation were preserved despite mural cell senescence. The results suggest that the functional effects of vascular cell senescence are dominated by the endothelium.

Pharmacological management of vascular endothelial dysfunction in diabetes: TCM and western medicine compared based on biomarkers and biochemical parameters

Diabetes, a worldwide health concern while burdening significant populace of countries with time due to a hefty increase in both incidence and prevalence rates. Hyperglycemia has been buttressed both in clinical and experimental studies to modulate widespread molecular actions that effect macro and microvascular dysfunctions. Endothelial dysfunction, activation, inflammation, and endothelial barrier leakage are key factors contributing to vascular complications in diabetes, plus the development of diabetes-induced cardiovascular diseases. The recent increase in molecular, transcriptional, and clinical studies has brought a new scope to the understanding of molecular mechanisms and the therapeutic targets for endothelial dysfunction in diabetes. In this review, an attempt made to discuss up to date critical and emerging molecular signaling pathways involved in the pathophysiology of endothelial dysfunction and viable pharmacological management targets. Importantly, we exploit some Traditional Chinese Medicines (TCM)/TCM isolated bioactive compounds modulating effects on endothelial dysfunction in diabetes. Finally, clinical studies data on biomarkers and biochemical parameters involved in the assessment of the efficacy of treatment in vascular endothelial dysfunction in diabetes was compared between clinically used western hypoglycemic drugs and TCM formulas.

Screening of the active fractions from the Coreopsis tinctoria Nutt. Flower on diabetic endothelial protection and determination of the underlying mechanism

ETHNOPHARMACOLOGICAL RELEVANCE

The Coreopsis tinctoria Nutt. flower (CTF) has been used traditionally in China for treating hypertension and diabetes as well as reducing body weight and blood fat. However, the vascular protection effect of the CTF has not been studied to date.

AIM OF THE STUDY

This study aimed to screen and identify bioactive fractions from the CTF with a diabetic endothelial protection effect and to clarify the underlying mechanism.

MATERIALS AND METHODS

The vascular protection effect of Fraction A was studied in high-fat diet and streptozocin-induced diabetic models. The endothelial protection effect of Fraction A-2 was further studied in an in vitro vascular endothelial dysfunction model induced by high glucose. In a high glucose-induced human umbilical vein endothelial cell (HUVEC) model, Fractions A-2-2 and A-2-3 were screened, and their detailed mechanisms of endothelial protection were studied. Liquid chromatography mass spectrometry (LC-MS) was used to identify the main components in Fractions A-2-2 and A-2-3.

RESULTS

Fraction A treatment significantly improved the endothelium-dependent vasodilation of the mesenteric artery induced by acetylcholine in diabetic rats. The maximum relaxation was 79.82 ± 2.45% in the control group, 64.36 ± 9.81% in the model group, and 91.87 ± 7.38% in the Fraction A treatment group (P < 0.01). Fraction A treatment also decreased rat tail pressure compared with the model group at the 12th week. The systolic blood pressure was 152.7 5 ± 16.99 mmHg in the control group, 188.50 ± 5.94 mmHg in the model group, and 172.60 ± 14.31 mmHg in the Fraction A treatment group (P < 0.05). The mean blood pressure was 128.50 ± 13.79 mmHg in the control group, 157.00 ± 6.06 mmHg in the model group, and 144.80 ± 11.97 mmHg in the Fraction A treatment group (P < 0.05). In an in vitro vascular endothelium-dependent vasodilation dysfunction model induced by high glucose, Fraction A-2 improved the vasodilation of the mesenteric artery. The maximum relaxation was 82.15 ± 16.24% in the control group, 73.29 ± 14.25% in the model group, and 79.62 ± 13.89% in the Fraction A-2 treatment group (P < 0.05). In a high glucose-induced HUVEC model, Fraction A-2-2 and Fraction A-2-3 upregulated the expression of IRS-1, Akt, and eNOS and increased the levels of p-IRS-1^Ser307, p-Akt ^Ser473, and p-eNOS^Ser1177 and also decreased the expression of NOX4, TNF-α, IL-6, sVCAM, sICAM, and NF-κB (P < 0.01). With the intervention of AG490 and LY294002, the above effects of Fraction A-2-2 and Fraction A-2-3 were inhibited (P < 0.01). LC-MS data showed that in Fraction A-2-2 and Fraction A-2-3, there were 10 main components: flavanocorepsin; polyphenolic; flavanomarein; isochlorogenic acid A; dicaffeoylquinic acid; coreopsin; marein; coreopsin; luteolin-7-O-glucoside; and 3',5,5',7-tetrahydroxyflavanone-O-hexoside.

CONCLUSION

The protective effect of the CTF on diabetic endothelial dysfunction may be due to its effect on the JAK2/IRS-1/PI3K/Akt/eNOS pathway and the related oxidative stress and inflammation. The results strongly suggested that Fraction A-2-2 and Fraction A-2-3 were the active fractions from the CTF, and the CTF might be a potential option for the prevention of vascular complications in diabetes.

Artificial sweeteners impair endothelial vascular reactivity: Preliminary results in rodents

BACKGROUND AND AIMS

Prospective epidemiological studies highlighted recently the link between artificial sweeteners (AS) consumption and the risk of developing cardiometabolic diseases. However, underlying mechanisms remain unknown. Thus, the aim of this preliminary study was to characterize, in a healthy rat population, the effect of chronic AS consumption on body composition and vascular function, an early marker for cardiovascular disease.

METHODS AND RESULTS

Healthy Wistar rats followed a 10-week standard diet including the consumption of water sweetened or not with a sucralose/acesulfame potassium solution at different concentrations: for moderate consumption at 1 and 2 mg.kg^-1.day^-1, respectively or high intake at 15 and 15 mg.kg^-1.day^-1 for both molecules (acceptable daily intake). Body fat composition has been evaluated and ex vivo aortic vasomotor function has been investigated with a pharmacological approach.

CONCLUSION

Both groups of AS-treated rats showed a significant increase in subcutaneous and perirenal adipose tissue mass storage, without changes in total body mass. However, rats that have consumed AS at Acceptable Daily Intake (ADI) concentration revealed a significant vascular endothelial dysfunction compared to other groups. These results are interesting because they will help to better explain the observed increase in cardiometabolic risk.

Excessive dietary salt promotes aortic stiffness in murine renovascular hypertension

Renovascular hypertension is characterized by activation of the renin-angiotensin-aldosterone system, blunted natriuretic responses, and elevated sympathetic nerve activity. Excess dietary salt intake exaggerates arterial blood pressure (ABP) in multiple models of experimental hypertension. The present study tested whether a high-salt diet exaggerated ABP and vascular dysfunction in a 2-kidney, 1-clip (2K1C) murine model. Male C57BL/6J mice (8-12 wk) were randomly assigned, and fed a 0.1% or 4.0% NaCl diet, and instrumented with telemetry units to measure ABP. Then, the 2K1C model was produced by placing a cuff around the right renal artery. Systolic, diastolic, and mean ABP were significantly higher in mice fed 4.0% vs. 0.1% NaCl at 1 wk but not after 3 wk. Interestingly, 2K1C hypertension progressively increased arterial pulse pressure in both groups; however, the magnitude was significantly greater in mice fed 4.0% vs. 0.1% NaCl at 3 wk. Moreover, pulse wave velocity was significantly greater in 2K1C mice fed 4.0% vs. 0.1% NaCl diet or sham-operated mice fed either diet. Histological assessment of aortas indicated no structural differences among groups. Finally, endothelium-dependent vasodilation was significantly and selectively attenuated in the aorta but not mesenteric arteries of 2K1C mice fed 4.0% NaCl vs. 0.1% NaCl or sham-operated control mice. The findings suggest that dietary salt loading transiently exaggerates 2K1C renovascular hypertension but promotes chronic aortic stiffness and selective aortic vascular dysfunction.NEW & NOTEWORTHY High dietary salt exaggerates hypertension in multiple experimental models. Here we demonstrate that a high-salt diet produces a greater increase in arterial blood pressure at 1 wk after induction of 2-kidney, 1-clip (2K1C) hypertension but not at 3 wk. Interestingly, 2K1C mice fed a high-salt diet displayed an exaggerated pulse pressure, elevated pulse wave velocity, and reduced endothelium-dependent vasodilation of the aorta but not mesenteric arteries. These findings suggest that dietary salt may interact with underlying cardiovascular disease to promote selective vascular dysfunction and aortic stiffness.

Focal adhesion kinase and Src mediate microvascular hyperpermeability caused by fibrinogen- γC- terminal fragments

Objectives

We previously reported microvascular leakage resulting from fibrinogen-γ chain C-terminal products (γC) occurred via a RhoA-dependent mechanism. The objective of this study was to further elucidate the signaling mechanism by which γC induces endothelial hyperpermeability. Since it is known that γC binds and activates endothelial αvβ3, a transmembrane integrin receptor involved in intracellular signaling mediated by the tyrosine kinases FAK and Src, we hypothesized that γC alters endothelial barrier function by activating the FAK-Src pathway leading to junction dissociation and RhoA driven cytoskeletal stress-fiber formation.

Methods and results

Using intravital microscopy of rat mesenteric microvessels, we show increased extravasation of plasma protein (albumin) resulting from γC administration. In addition, capillary fluid filtration coefficient (K_fc) indicated γC-induced elevated lung vascular permeability. Furthermore, γC decreased transendothelial barrier resistance in a time-dependent and dose-related fashion in cultured rat lung microvascular endothelial cells (RLMVECs), accompanied by increased FAK/Src phosphorylation detection by western blot. Experiments with pharmacological inhibition or gene silencing of FAK showed significantly reduced γC-induced albumin and fluid leakage across microvessels, stress-fiber formation, VE-cadherin tyrosine phosphorylation, and improved γC-induced endothelial barrier dysfunction, indicating the involvement of FAK in γC mediated hyperpermeability. Comparable results were found when Src was targeted in a similar manner, however inhibition of FAK prevented Src activation, suggesting that FAK is upstream of Src in γC-mediated hyperpermeability. In addition, γC-induced cytoskeletal stress-fiber formation was attenuated during inhibition or silencing of these tyrosine kinases, concomitantly with RhoA inhibition.

Conclusion

The FAK-Src pathway contributes to γC-induced microvascular barrier dysfunction, junction protein phosphorylation and disorganization in a manner that involves RhoA and stress-fiber formation.

Dietary Potassium Attenuates the Effects of Dietary Sodium on Vascular Function in Salt-Resistant Adults

The influence of dietary sodium and potassium on blood pressure (BP) has been extensively studied, however their impact on endothelial function, particularly any interactive effects, has received less attention. The purpose of this study was to determine if dietary potassium can offset the deleterious effect of high dietary sodium on endothelial function independent of BP. Thirty-three adults with salt-resistant BP (16 M and 17 F; 27 ± 1 year) completed seven days each of the following diets in a random order: a moderate potassium/low sodium diet (65 mmol potassium/50 mmol sodium; MK/LS), a moderate potassium/high sodium diet (65mmol potassium/300 mmol sodium; MK/HS) and a high potassium/high sodium (120 mmol potassium/300 mmol sodium; HK/HS). On day seven of each diet, 24-h ambulatory BP and a urine collection were performed. Brachial artery flow-mediated dilation (FMD) was measured in response to reactive hyperemia. Between diets, 24-h BP was unchanged confirming salt resistance (p > 0.05). Sodium excretion increased on both HS diets compared to MK/LS (p < 0.05) and potassium excretion was increased on the HK diet compared to MK/LS and MK/HS (p < 0.05) confirming diet compliance. FMD was lower in MK/HS (5.4 ± 0.5%) compared to MK/LS (6.7 ± 0.5%; p < 0.05) and HK/HS (6.4 ± 0.5%), while there was no difference between the MK/LS and HK/HS diets (p > 0.05). These data suggest that dietary potassium provides vascular protection against the deleterious effects of high dietary sodium by restoring conduit artery function.

Vasorelaxant effects of Crataegus pentagyna: Links with arginase inhibition and phenolic profile

ETHNOPHARMACOLOGICAL RELEVANCE

Crataegus leaves, flowers and fruits have been traditionally used to improve blood circulation, numerous preclinical and clinical studies supporting the cardiovascular benefits of Crataegus preparations. In this respect, there is very limited data on Crataegus pentagyna; in addition, the chemical profile of this species is still incompletely elucidated.

AIM OF THE STUDY

The objective of this study was to examine the cardiovascular benefits of Crataegus pentagyna Waldst. et Kit. ex Willd. (small-flowered black hawthorn, Rosaceae) extracts (leaf, flower and fruit ethyl acetate extracts) and the underlying mechanisms. We hypothesized that C. pentagyna extracts might exert vasodilatory effects and inhibit arginase activity due, in large part, to their polyphenolic constituents.

MATERIALS AND METHODS

C. pentagyna extracts induced-relaxation and the mechanisms involved were studied ex vivo in isolated aortic rings from Sprague-Dawley rats. The inhibitory effects on bovine liver arginase I were assessed by an in vitro assay. Metabolite profiling of C. pentagyna extracts was performed and the most endothelium- and nitric oxide synthase-dependent; flower extract additionally reduced Ca²⁺ entry and, to a lesser extent, Ca²⁺ release from the sarcoplasmic reticulum. C. pentagyna proved to be an important source of arginase inhibitors with potential benefits in endothelial dysfunction that remains to be explored.

Effects of Nigella sativa on endothelial dysfunction in diabetes mellitus: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Endothelial dysfunction is involved in lesion generation by the promotion of both early and late mechanism(s) of atherosclerosis such as adhesion molecules up-regulation, increased chemokine secretion and leukocyte adherence, increased cell permeability, enhanced low-density lipoprotein oxidation, cytokine elaboration, platelet activation and vascular smooth muscle cell migration, and proliferation. Nigella sativa is from the Ranunculaceae family which is used in some countries for various medicinal purposes. Nigella sativa seed has been widely used in traditional medicine for the treatment of diabetes.

AIM OF THE REVIEW

This review article summarized the therapeutic effects of Nigella sativa on endothelial dysfunction.

METHODS

Databases such as PubMed, Web of Science, Google Scholar, Scopus, and Iran Medex were considered. The search terms were " Nigella sativa " or "endothelium" and " Diabetes"," endothelial dysfunction ", " Thymoquinone " and " anti-inflammatory effect ".

RESULTS

The current review shows that Nigella sativa and Thymoquinone have a protective effect on endothelial dysfunction induced by diabetes. This is done by several mechanisms such as reduction of inflammatory and apoptotic markers, improving hyperglycemia, hyperlipidemia and antioxidant function, inhibiting platelet aggregation, and regulating eNOS, VCAM-1 and LOX-1 genes expression that involve in the endothelial dysfunction. Thymoquinone also reduces expression and secretion of some cytokines such as MCP-1, interleukin-1β, TNF-α, NF-κB, and Cox-2 that result in anti-inflammation effect.

CONCLUSION

Thymoquinone, the main phenolic terpene found in Nigella sativa, has several important properties such as antidiabetic, anti-inflammatory, and antioxidant activity. Therefore, Nigella sativa can improve endothelial dysfunction.