Impaired Endothelium-dependent Vasodilation Research Articles

Hypertension Cure Research progress: The use of Zilebesiran in Hypertension

Chronic hypertension is a lifelong condition, and the patients need lifelong treatment with oral anti-hypertensive medications to say healthy and to prevent the development of serious complications. Demands for changing this situation of lifelong dependence on daily medications have been increasing. The aim of this paper is to highlight the recent breakthrough in hypertension research. Expert opinion: Zilebesiran, a small interfering RNA targeting angiotensinogen has the main advantage of long duration of action which allows meeting many hypertensions patients’ demand of avoiding the inconvenience of talking oral hypertensive medication on daily basis. It is worth mentioning that a more optimal blockade of renin-angiotensin-aldosterone system is not the only advantageous therapeutic approach for the treatment of hypertension. Impairment of endothelium-dependent vasodilation has been increasingly recognized as an important contributor for the development of essential hypertension’s-arginine is an amino acid that is considered the biological precursor of nitric oxide which is an important contributor to microvascular vasodilation and to the reduction atherosclerosis. Oral L-arginine has been emerging as a new effective approach of reducing blood through improving endothelial function in hypertensive patients.

Low density lipoprotein oxidized under lysosomal conditions decreases arterial vasodilatation

Endothelial dysfunction is a risk factor for atherosclerosis and includes impaired endothelium-dependent vasodilatation. We have shown previously that low density lipoprotein (LDL) can be oxidized by iron in the lysosomes of macrophages. Macrophage lysis in atherosclerotic lesions might expose endothelial cells to this oxidized LDL and adversely affect their function. LDL was oxidized by ferrous sulfate (5 µM) for 24 h at pH 4.5 at 37 °C. Aortas from male Wistar rats were cut into rings and subjected to wire myography for isometric tension recording. The rings were incubated with or without oxidized LDL (50 µg protein/ml) for one hour, constricted with 100 nM phenylephrine and relaxation to acetylcholine (1 nM − 3 µM) was measured. There was about 50% less relaxation in the presence of this oxidized LDL. Endothelial-independent vasodilatation induced by sodium nitroprusside was less affected by oxidized LDL. Oxidized LDL increased the formation of reactive oxygen species by the aortic rings and by cultured human aortic and dermal microvascular endothelial cells, which might have inactivated nitric oxide. Acetylcholine increased the activatory phosphorylation of eNOS (ser-1177), but oxidized LDL had little effect on this activation in cultured human aortic endothelial cells. These findings raise the possibility that LDL oxidized in lysosomes and released from lysed macrophages might decrease vasodilatation in atherosclerotic arteries.

TMAO Impairs Mouse Aortic Vasodilation by Inhibiting TRPV4 Channels in Endothelial Cells.

Trimethylamine oxide (TMAO) is an intestinal flora metabolite associated with risk of cardiovascular diseases. Transient receptor potential vanilloid 4 (TRPV4) is a Ca2+-permeable ion channel that is essential for vasodilation and endothelial function. Currently, there are few studies on the effect of TMAO on TRPV4 channels. In the present study, Ca2+ imaging of vascular tissue showed that TMAO inhibited TRPV4-mediated Ca2+ influx into aortic endothelial cells in a dose-dependent manner. Furthermore, a whole-cell patch clamp assay showed that TMAO blocked TRPV4-mediated cation currents. Notably, results of aortic vascular tension measurement showed that TMAO impaired endothelium-dependent vasodilation in mouse aortic vessels through the TRPV4-NO pathway. Our results indicated that TMAO inhibited Ca2+ entry in endothelial cells and impaired vasodilation through the TRPV4-NO pathway in mice. These results provide scientific evidence for novel pathogenic mechanisms underlying the role of TMAO in cardiovascular disease.

Increased oxidative stress alters coronary microvascular tone in exercising swine with multiple comorbidities

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Dutch Cardiovascular Alliance Background/Objectives We have previously shown, in female swine that the combination of three cardiovascular risk factors (diabetes mellitus (DM), hypercholestolemia (HC) and chronic kidney disease (CKD)) induces systemic inflammation, oxidative stress, coronary endothelial dysfunction and impaired myocardial perfusion due to impaired nitric oxide (NO) bioavailability. In the present study we hypothesized that the reduced bioavailability of nitric oxide (NO) is the result of increased production of reactive oxygen species (ROS) and ROS scavenging will restore myocardial oxygen balance thereby improving myocardial perfusion. Methods 12 female swine, with DM (streptozotocin 3x50mg/kg iv), CKD (renal embolization), and HC (high fat, high sugar, high salt diet) and 9 female healthy swine on normal pig chow (Normal) were included. The effect of ROS scavenging on the coronary microvascular tone control was studied in vivo, at rest and during graded treadmill exercise before and after infusion of the ROS scavengers (MPG+Tempol). Additionally, vasodilation to bradykinin was studied in the presence of MPG and TEMPOL and after subsequent addition to catalase, in isolated left ventricle small coronary arteries, in vitro using wire-myography. Results 6 months of DM+HC+CKD resulted in hyperglycemia (18.0±1.3 vs 8.4±0.9mmol/L), hypercholesterolemia (13.4±2.1 vs 1.7±0.1mmol/l), renal dysfunction (plasma creatinine: 166±9 vs 119±3µmol/l), and systemic inflammation (TNFα: 63±8 vs 41±4pg/ml, all P<0.05) associated with impaired endothelium-dependent vasodilator response to bradykinin in vitro. Furthermore, myocardial oxidative stress was increased in DM+HC+CKD animals (8-isoprostane 13±1 vs 10±1pg/ml) and total antioxidant capacity was reduced (0.67±0.02 vs 0.72±0.01nmol Trolox eq./mg protein, both P<0.05). Surprisingly, in vivo ROS scavenging resulted in an even further increase in myocardial oxygen extraction in DM+HC+CKD while it had no effect in Normal, indicating the involvement of a vasodilator ROS (most likely H2O2) in the control of coronary microvascular tone. This was supported by increased activity of catalase in the myocardium of DM+HC+CKD animals (44±3 vs 31±4nmol/min/ml, both P<0.05) and the vascular relaxation response to bradykinin when catalase was added on top of the ROS scavenging in vitro. Conclusion In swine exposed for 6 months to multiple comorbidities, impaired myocardial perfusion is mediated by a loss of NO bioavailability due to increased oxidative stress which was partially compensated by increased H2O2-mediated coronary vasodilation.

Exposure to occupational air pollution and vascular endothelial dysfunction in workers of the steel industry in Iran.

Air pollution is recognized as a risk factor for cardiovascular diseases; however, the precise underlying mechanisms remain unclear. This study investigated the impact of occupational air pollution exposure on endothelial function in workers within the steel industry. Specifically, we examined male employees in the coke-making division of the Isfahan Steel Company in Iran, as well as those in administrative roles with no known history of cardiovascular risk. Data on age, body mass index, duration of employment, blood pressure, fasting blood sugar, and lipid profile were collected. To assess endothelial function, flow-mediated dilation (FMD) was measured. The baseline brachial artery diameter was greater (mean difference [95% CI] = 0.068mm [0.008 to 0.128]), while the FMD was lower (mean difference [95% CI] = -0.908 % [-1.740 to -0.075]) in the coke-making group than in the control group. After controlling for potential confounding variables, it was observed that working in the coke-making sector of the industry was associated with lower FMD (F = 3.954, p = .049). These findings indicated that occupational air pollution exposure among workers in the steel industry is linked to impaired endothelium-dependent vasodilation.

IMPAIRED BETA-ADRENERGIC VASODILATOR FUNCTION IN HYPERTENSIVE PATIENTS WITH SYMPTOMS OF DEPRESSION

Objective: Hypertension and depression are amongst the most common chronic physical and mental conditions worldwide. The two conditions cluster, however the mechanisms underlying the association are not well understood. Hypertension complicated by affective disorders may be characterised by high sympathetic activity. We investigated whether symptoms of depression may be associated with impaired endothelium-dependent beta2-adrenergic vasodilator responses. Design and method: Hypertensive subjects with no previous history of diabetes or cardiovascular disease were recruited from the hypertension outpatient service at St. Thomas’ Hospital, London. Detailed medical history and baseline characteristics including blood pressure (BP), heart rate (HR), routine biochemistry including C-reactive protein (CRP) and low-density lipoprotein (LDL) were obtained during a single study visit. Plasma concentrations of normetadrenaline were measured as a marker of resting sympathetic activity. Depression symptom severity was assessed using the Patient Health Questionnaire-9 (PHQ-9). The pulse wave response to the beta2-adrenergic vasodilator salbutamol (PWRS) was assessed using radial tonometry to measure the change in augmentation index after inhalation of 200μg salbutamol from a metered dose inhaler with spacer device. Results: 100 subjects (62% male, mean ± SD age 41.0±11.6 years) were recruited. 79% were on pharmacological treatment for hypertension. Mean PHQ-9 depression score was 8.8±6.2, consistent with a high prevalence of depression. After adjusting for confounders (age, sex, smoking status, body mass index, BP, HR, CRP, LDL, treatment for hypertension), PWRS was significantly related to depression score (Beta= 0.447, P=0.002). Depression score was also significantly associated with plasma concentrations of normetadrenaline (Beta= 0.605, P<0.001) and after adjusting for plasma normetadrenaline level, the association between PWRS and depression score was no longer significant (Beta= 0.343, P=0.102). Conclusions: These results suggest that in hypertensive subjects with depression, an impaired endothelium-dependent beta2-adrenergic vasodilator response is mediated by a high level of sympathetic activity which could contribute to cardiovascular complications.

The Regulatory Role of microRNA-21 in Coronary Microcirculation in Metabolic Syndrome

Coronary vasculature is essential to supply oxygen and nutrients to the heart and maintain normal cardiac function. Obstruction of large vessels of coronaries (atherosclerosis) is well studied, but coronary microvascular dysfunction (CMD), which is associated with diabetic cardiomyopathy, Takotsubo cardiomyopathy, Ischemia with the non-obstructive coronary artery (INOCA), and HFpEF, is understudied. CMD is characterized by impaired endothelial-dependent vasodilation, but detailed mechanisms have yet to be elucidated. The anti-fibrotic role of microRNA-21 (miR-21) is reported in the HFrEF induced by ischemia/reperfusion or pressure overload, but how miR-21 regulates CMD is not entirely understood. Our recent study shows miR-21 ablation ameliorated impaired vasodilation in isolated coronaries of mice fed on high fat and high sugar (HFHS) diet. In this study, we examined the coronary flow reserve (CFR), the relationship between myocardial blood flow (MBF) and cardiac work (doppler) under hyperemia, cardiac function (echocardiography and exercise exertion test), fibrosis and gene expression of miR-21 knockout and wild-type (WT) mice fed on chow or HFHS diet. Our preliminary data show that MBF and CFR were decreased, cardiac index, stroke volume, and running distance were reduced, and the E/E’ ratio was increased in WT mice fed on the HFHS diet compared to the WT mice fed on the chow diet. The perivascular fibrosis was increased in the WT mice fed on the HFHS diet compared to WT mice on the chow diet. The ablation of miR-21 reversed all these changes in the mice treated with HFHS, suggesting miR-21 deficiency ameliorated CMD in metabolic syndrome. Moreover, we used endothelial-specific miR-21 knockout to study the endothelial miR-21 function. Interestingly, the endothelial mi-R21 KO phenocopied the global knockouts, suggesting the benefit of miR-21 deficiency to coronary microvascular function in metabolic syndrome is from endothelial cells. The study provides the potential therapeutic strategy to target vascular endothelial cells with miR-21 antagomir for CMD in metabolic syndromes. AHA 970663,1R56HL165207,1 R01 HL165207-01A1 to LY and 1 F31 HL156726-01A1 to CJ. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Coronary microvascular dysfunction in postmenopausal minipigs with multiple risk factors

Coronary microvascular angina occurs in both men and women, however, the majority of patients are postmenopausal women with multiple cardiovascular risk factors, such as diabetes mellitus (DM), chronic kidney disease (CKD) and dyslipidemia. No treatment is available for coronary microvascular dysfunction, requiring more in depth knowledge on the mechanisms underlying this syndrome in this expanding group of patients. Here we studied microvascular function in vivo and and in vitro in isolated small coronary arteries, in postmenopausal miniswine with multiple cardiovascular risk factors. DM (streptozotocin), hypercholesterolemia (HC, high fat, high sugar diet), CKD (renal artery embolization) and menopause (OVX) were induced in 5 adult female minipigs (1.5-2 years old, ±40kg, DM+HC+CKD+OVX) for 6 months, while 11 healthy female minipigs matched for age and weight, on normal pig chow served as controls (Control). At sacrifice, coronary flow reserve (CFR) in response to intracoronary infusion of adenosine was measured under anesthesia, and endothelium-dependent response to bradykinin in the presence and absence of eNOS blockade with LNAME, were studied in vitro in isolated small coronary arteries. 6 months of sustained hyperglycemia (17.5±1.0 in in DM+HC+CKD+OVX vs 8.2±0.9 mmol/l in Control), hypercholesterolemia (15.4±2.0 vs 1.7±0.1 mmol/l) and renal dysfunction (plasma total protein: 84±3 vs 72±1 g/l) were accompanied by systemic inflammation (TNFalpha: 62±7 vs 47±1 pg/ml, all p<0.05 by t-test). Coronary flow reserve was significantly reduced in animals with multiple risk factors (3.4±0.4 in DM+HC+CKD+OVX) as compared to the healthy animals (4.9±0.3 in Control, p<0.05). In vitro, coronary small arteries from DM+HC+CKD+OVX animals showed impaired endothelium-dependent vasodilation to bradykinin, which was mediated by a loss of nitric oxide. Conclusion: Postmenopausal minipigs with multiple risk factors, displayed severe coronary microvascular dysfunction as evidenced by a significantly reduced coronary flow reserve and endothelial dysfunction. The latter was characterized by a marked loss of nitric oxide. Such perturbations may contribute to reduced myocardial perfusion that is often observed in postmenopausal women with multiple cardiovascular risk factors. Funding: Grant 2020B008 RECONNEXT. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Abstract 3133: Selective Vulnerability Of Coronary Arteries To Hypercholesterolemia And Angiotensin II-induced Hypertension

Hypercholesterolemia and hypertension are major risk factors for cardiovascular disease. We aimed to determine their concomitant effects on coronary atherogenesis. An SR-BI (an HDL receptor) suppression and doxycycline-inducible angiotensin II (AngII) cassette was inserted downstream of the ApoE promoter to ablate ApoE expression and overproduce AngII. The resulting mutants (ApoE SA/SA ) exhibited mild coronary atherosclerosis after Western diet feeding. Doxycycline induced AngII-induced hypertension and drastically accelerated coronary atherosclerosis, with lesions exhibiting endothelial erosion, myeloid cell infiltration, and plaque rupture, resulting in myocardial infarction, heart failure, and male-propensity of sudden death. AngII, but not norepinephrine-induced hypertension, led to severe coronary atherogenesis under hypercholesterolemia, which was abolished by losartan. Notably, norepinephrine constricted femoral arteries, but it dilated coronary arteries. In contrast to coronary arteries, femoral arteries did not develop atherosclerosis. Proteomic analyses revealed distinctive differences between the two vascular beds. Coronary vasodilation to acetylcholine was highly susceptible to the risk factors, compared to femoral artery, and was markedly attenuated by AngII exposure and prostaglandin inhibition. Interestingly, coronary prostaglandin synthesis was suppressed in atherogenesis, and elevated coronary capacity to produce prostaglandins following methotrexate administration was associated with ameliorated early coronary endothelial dysfunction and improved cardiovascular survival, featuring markedly reduced lesional myeloid cells. Coronary arteries from patients with hypertension and hypercholesterolemia showed substantially impaired endothelium-dependent vasodilation, compared to internal mammary arteries of similar risk exposure, whereas their endothelium-independent vasodilation was intact. Thus, the combination of hypercholesterolemia and AngII-induced hypertension drastically promoted coronary atherosclerosis with spontaneous lesion rupture, which confers a selective vulnerability of coronary vasodilation to prostaglandin inhibition and AngII exposure.

Abstract P197: Dietary Quality Determined by Healthy Eating Index-2015 and Endothelial Function in Healthy Adults

The Healthy Eating Index (HEI) is a measure of diet quality based on Dietary Guidelines for Americans and developed in collaboration with the US Department of Health and Human Services and the US Department of Agriculture. Clinical interest in HEI has increased due to its association with obesity, inflammatory biomarkers and risk of coronary heart disease and stroke. Indeed, higher HEI-2015 score has been linked with reduced cardiovascular risk, morbidity, and mortality. Endothelial dysfunction, particularly impaired endothelium-dependent vasodilation, is a central etiological factor underlying cardiovascular risk and events. We and others have previously demonstrated that diets high in saturated fat and other proatherogenic diets are associated with endothelial vasodilator dysfunction. It is currently unknown whether HEI-2015 dietary score is associated with endothelial function. If so, assessing dietary quality based on HEI-2015 may provide targeted nutritional guidance for enhancing vascular health and mitigating cardiovascular risk. The aim of this study was to determine whether HEI-2015 score is associated with endothelial vasodilator function in healthy adults. Using data from 4-day dietary records, HEI-2015 scores were determined in 103 adults (65 M/38 F; age 44-68 years) free of overt cardiometabolic disease. The HEI-2015 score is based on 13 components summed to yield a total score from 0 to 100; higher score representing higher diet quality. The adults were stratified by HEI-2015 score quartiles: Q1: HEI < 52.5 (n=25; 23 M/2 F); Q2: HEI 52.6-59.1 (n=26; 14 M/12 F); Q3: HEI 59.2-66.0 (n=26; 15 M/11 F); and Q4: HEI > 66.0 (n=26; 13 M/13 F). Endothelium-dependent vasodilation was determined by forearm blood flow (FBF) (via plethysmography) responses to intra-arterial infusion of acetylcholine (ACh: 4.0, 8.0, and 16.0 μg/100 mL tissue/min) and sodium nitroprusside (NTP: 1.0, 2.0, and 4.0 μg/100 mL tissue/min). There were no significant differences in endothelium-dependent vasodilation across the HEI-2015 score quartiles. FBF blood responses to ACh were remarkably similar between Q1 (5.1±0.2 to 13.0±0.7 mL/100 mL tissue/min), Q2 (4.3±0.2 to 12.1±0.7 mL/100 mL tissue/min), Q3 (4.4±0.2 to 13.0±0.7 mL/100 mL tissue/min) and Q4 (4.5±0.2 to 14.4±0.6 mL/100 mL tissue/min). Moreover, HEI scores were not significantly associated with the vasodilator response to either ACh (r=0.15, P=0.13) or NTP (r=-0.04; P=0.72). In summary, although diet quality determined by HEI-2015 score has been shown to be associated with increased risk of cardiovascular disease and events, HEI-2015 was not associated endothelial function in mid-life and older adults. Given the established experimental and pathophysiological evidence linking between diet, endothelial vasodilator function and cardiovascular risk, HEI-2015 score is not a sensitive dietary indicator/biomarker of vascular function.

Lipid droplets in the endothelium: The missing link between metabolic syndrome and cardiovascular disease?

The physiology of lipid droplets (LDs) has been most extensively characterized in adipocytes, but LDs also accumulate in endothelial cells lining blood vessels in response to changing levels of triglycerides. In recent issues of the JCI, two independent papers highlight a direct role of endothelial LDs in the genesis of hypertension and atherosclerosis in rodent models. Kim et al. demonstrated that accumulation of LDs in the endothelium leads to hypertension, impairs endothelial function, and accelerates atherosclerosis. Boutagy, Gamez-Mendez, et al. knocked out Atgl in the endothelium and confirmed triglyceride accumulation in endothelial cells that was associated with reduced NO synthesis and impaired endothelial-dependent vasodilation. These data suggest that enhancing triglyceride breakdown in the endothelium could provide a treatment target for patients with metabolic syndrome.

Inhalation of particulate matter containing environmentally persistent free radicals induces endothelial dysfunction mediated via AhR activation at the air-blood interface.

Particulate matter (PM) containing environmentally persistent free radicals (EPFR) is formed by the incomplete combustion of organic wastes, resulting in the chemisorption of pollutants to the surface of PM containing redox-active transition metals. In prior studies in mice, EPFR inhalation impaired endothelium-dependent vasodilation. These findings were associated with aryl hydrocarbon receptor (AhR) activation in the alveolar type-II (AT-II) cells that form the air-blood interface in the lung. We thus hypothesized that AhR activation in AT-II cells promotes the systemic release of mediators that promote endothelium dysfunction peripheral to the lung. To test our hypothesis, we knocked down AhR in AT-II cells of male and female mice and exposed them to 280 µg/m3 EPFR lo (2.7e + 16 radicals/g) or EPFR (5.5e + 17 radicals/g) compared with filtered air for 4 h/day for 1 day or 5 days. AT-II-AhR activation-induced EPFR-mediated endothelial dysfunction, reducing endothelium-dependent vasorelaxation by 59%, and eNOS expression by 50%. It also increased endothelin-1 mRNA levels in the lungs and peptide levels in the plasma in a paracrine fashion, along with soluble vascular cell adhesion molecule-1 and iNOS mRNA expression, possibly via NF-kB activation. Finally, AhR-dependent increases in antioxidant response signaling, coupled to increased levels of 3-nitrotyrosine in the lungs of EPFR-exposed littermate control but not AT-II AhR KO mice suggested that ATII-specific AhR activation promotes oxidative and nitrative stress. Thus, AhR activation at the air-blood interface mediates endothelial dysfunction observed peripheral to the lung, potentially via release of systemic mediators.

The oxidized phospholipid PGPC impairs endothelial function by promoting endothelial cell ferroptosis via FABP3

Ferroptosis is a novel cell death mechanism that is mediated by iron-dependent lipid peroxidation. It may be involved in atherosclerosis development. Products of phospholipid oxidation play a key role in atherosclerosis. 1-palmitoyl-2-glutaroyl-sn-glycero-3-phosphocholine (PGPC) is a phospholipid oxidation product present in atherosclerotic lesions. It remains unclear whether PGPC causes atherosclerosis by inducing endothelial cell ferroptosis. In this study, human umbilical vein endothelial cells (HUVECs) were treated with PGPC. Intracellular levels of ferrous iron, lipid peroxidation, superoxide anions (O2•−), and glutathione were detected, and expression of fatty acid binding protein-3 (FABP3), glutathione peroxidase 4 (GPX4), and CD36 were measured. Additionally, the mitochondrial membrane potential (MMP) was determined. Aortas from C57BL6 mice were isolated for vasodilation testing. Results showed that PGPC increased ferrous iron levels, the production of lipid peroxidation and O2•−, and FABP3 expression. However, PGPC inhibited the expression of GPX4 and glutathione production and destroyed normal MMP. These effects were also blocked by ferrostatin-1, an inhibitor of ferroptosis. FABP3 silencing significantly reversed the effect of PGPC. Furthermore, PGPC stimulated CD36 expression. Conversely, CD36 silencing reversed the effects of PGPC, including PGPC-induced FABP3 expression. Importantly, E06, a direct inhibitor of the oxidized 1-palmitoyl-2-arachidonoyl-phosphatidylcholine IgM natural antibody, inhibited the effects of PGPC. Finally, PGPC impaired endothelium-dependent vasodilation, ferrostatin-1 or FABP3 inhibitors inhibited this impairment. Our data demonstrate that PGPC impairs endothelial function by inducing endothelial cell ferroptosis through the CD36 receptor to increase FABP3 expression. Our findings provide new insights into the mechanisms of atherosclerosis and a therapeutic target for atherosclerosis.

Bioactive Flavonoids in Protecting Against Endothelial Dysfunction and Atherosclerosis.

Atherosclerosis is a common cardiovascular disease closely associated with factors such as hyperlipidaemia and chronic inflammation. Among them, endothelial dysfunction serves as a major predisposing factor. Vascular endothelial dysfunction is manifested by impaired endothelium-dependent vasodilation, enhanced oxidative stress, chronic inflammation, leukocyte adhesion and hyperpermeability, endothelial senescence, and endothelial-mesenchymal transition (EndoMT). Flavonoids are known for their antioxidant activity, eliminating oxidative stress induced by reactive oxygen species (ROS), thereby preventing the oxidation of low-density lipoprotein (LDL) cholesterol, reducing platelet aggregation, alleviating ischemic damage, and improving vascular function. Flavonoids have also been shown to possess anti-inflammatory activity and to protect the cardiovascular system. This review focuses on the protective effects of these naturally-occuring bioactive flavonoids against the initiation and progression of atherosclerosis through their effects on endothelial cells including, but not limited to, their antioxidant, anti-inflammatory, anti-thrombotic, and lipid-lowering properties. However, more clinical evidences are still needed to determine the exact role and optimal dosage of these compounds in the treatment of atherosclerosis.

Chymase-independent vascular Ang-(1–12)/Ang II pathway and TXA2 generation are involved in endothelial dysfunction in the murine model of heart failure

The angiotensin (Ang)-(1–12)/Ang II pathway contributes to cardiac pathology. However, its involvement in the development of peripheral endothelial dysfunction associated with heart failure (HF) remains unknown. Therefore, this study aimed to characterise the effect of exogenous Ang-(1–12) and its conversion to Ang II on endothelial function using the murine model of HF (Tgαq*44 mice), focusing on the role of chymase and vascular-derived thromboxane A2 (TXA2).Ex vivo myographic assessments of isolated aorta showed impaired endothelium-dependent vasodilation in late-stage HF in 12-month-old Tgαq*44 mice. However, endothelium-dependent vasodilation was fully preserved in the early stage of HF in 4-month-old Tgαq*44 mice and 4- and 12-month-old FVB control mice. Ang-(1–12) impaired endothelium-dependent vasodilation in 4- and 12-month-old Tgαq*44 mice, that was associated with increased Ang II production. The chymase inhibitor chymostatin did not inhibit this response. Interestingly, TXA2 production reflected by TXB2 measurement was upregulated in response to Ang-(1–12) and Ang II in aortic rings isolated from 12-month-old Tgαq*44 mice but not from 4-month-old Tgαq*44 mice or age-matched FVB mice. Furthermore, in vivo magnetic resonance imaging showed that Ang-(1–12) impaired endothelium-dependent vasodilation in the aorta of Tgαq*44 mice and FVB mice. However, this response was inhibited by angiotensin I converting enzyme (ACE) inhibitor; perindopril, angiotensin II receptor type 1 (AT1) antagonist; losartan and TXA2 receptor (TP) antagonist-picotamide in 12-month-old-Tgαq*44 mice only.In conclusion, the chymase-independent vascular Ang-(1–12)/Ang II pathway and subsequent TXA2 overactivity contribute to systemic endothelial dysfunction in the late stage of HF in Tgαq*44 mice. Therefore, the vascular TXA2 receptor represents a pharmacotherapeutic target to improve peripheral endothelial dysfunction in chronic HF.

Endothelial Dysfunction and Heart Failure with Preserved Ejection Fraction-An Updated Review of the Literature.

Heart failure (HF) is a clinical syndrome consisting of typical symptoms and signs due to structural and/or functional abnormalities of the heart, resulting in elevated intracardiac pressures and/or inadequate cardiac output. The vascular system plays a crucial role in the development and progression of HF regardless of ejection fraction, with endothelial dysfunction (ED) as one of the principal features of HF. The main ED manifestations (i.e., impaired endothelium-dependent vasodilation, increased oxidative stress, chronic inflammation, leukocyte adhesion, and endothelial cell senescence) affect the systemic and pulmonary haemodynamic and the renal and coronary circulation. The present review is aimed to discuss the contribution of ED to HF pathophysiology-in particular, HF with preserved ejection fraction-ED role in HF patients, and the possible effects of pharmacological and non-pharmacological approaches. For this purpose, relevant data from a literature search (PubMed, Scopus, EMBASE, and Medline) were reviewed. As a result, ED, assessed via venous occlusion plethysmography or flow-mediated dilation, was shown to be independently associated with poor outcomes in HF patients (e.g., mortality, cardiovascular events, and hospitalization due to worsening HF). In addition, SGLT2 inhibitors, endothelin antagonists, endothelial nitric oxide synthase cofactors, antioxidants, and exercise training were shown to positively modulate ED in HF. Despite the need for future research to better clarify the role of the vascular endothelium in HF, ED represents an interesting and promising potential therapeutic target.

Dexrazoxane does not mitigate early vascular toxicity induced by doxorubicin in mice.

Apart from cardiotoxicity, the chemotherapeutic agent doxorubicin (DOX) provokes acute and long-term vascular toxicity. Dexrazoxane (DEXRA) is an effective drug for treatment of DOX-induced cardiotoxicity, yet it remains currently unknown whether DEXRA prevents vascular toxicity associated with DOX. Accordingly, the present study aimed to evaluate the protective potential of DEXRA against DOX-related vascular toxicity in a previously-established in vivo and ex vivo model of vascular dysfunction induced by 16 hour (h) DOX exposure. Vascular function was evaluated in the thoracic aorta in organ baths, 16h after administration of DOX (4 mg/kg) or DOX with DEXRA (40 mg/kg) to male C57BL6/J mice. In parallel, vascular reactivity was evaluated after ex vivo incubation (16h) of murine aortic segments with DOX (1 μM) or DOX with DEXRA (10 μM). In both in vivo and ex vivo experiments, DOX impaired acetylcholine-stimulated endothelium-dependent vasodilation. In the ex vivo setting, DOX additionally attenuated phenylephrine-elicited vascular smooth muscle cell (VSMC) contraction. Importantly, DEXRA failed to prevent DOX-induced endothelial dysfunction and hypocontraction. Furthermore, RT-qPCR and Western blotting showed that DOX decreased the protein levels of topoisomerase-IIβ (TOP-IIβ), a key target of DEXRA, in the heart, but not in the aorta. Additionally, the effect of N-acetylcysteine (NAC, 10 μM), a reactive oxygen species (ROS) scavenger, was evaluated ex vivo. NAC did not prevent DOX-induced impairment of acetylcholine-stimulated vasodilation. In conclusion, our results show that DEXRA fails to prevent vascular toxicity resulting from 16h DOX treatment. This may relate to DOX provoking vascular toxicity in a ROS- and TOP-IIβ-independent way, at least in the evaluated acute setting. However, it is important to mention that these findings only apply to the acute (16h) treatment period, and further research is warranted to delineate the therapeutic potential of DEXRA against vascular toxicity associated with longer-term repetitive DOX dosing.

Doxorubicin-induced cardiovascular toxicity: a longitudinal evaluation of functional and molecular markers.

Apart from cardiotoxicity, the chemotherapeutic doxorubicin (DOX) induces vascular toxicity, represented by arterial stiffness and endothelial dysfunction. Both parameters are of interest for cardiovascular risk stratification as they are independent predictors of future cardiovascular events in the general population. However, the time course of DOX-induced cardiovascular toxicity remains unclear. Moreover, current biomarkers for cardiovascular toxicity prove insufficient. Here, we longitudinally evaluated functional and molecular markers of DOX-induced cardiovascular toxicity in a murine model. Molecular markers were further validated in patient plasma. DOX (4 mg/kg) or saline (vehicle) was administered intra-peritoneally to young, male mice weekly for 6 weeks. In vivo cardiovascular function and ex vivo arterial stiffness and vascular reactivity were evaluated at baseline, during DOX therapy (Weeks 2 and 4) and after therapy cessation (Weeks 6, 9, and 15). Left ventricular ejection fraction (LVEF) declined from Week 4 in the DOX group. DOX increased arterial stiffness in vivo and ex vivo at Week 2, which reverted thereafter. Importantly, DOX-induced arterial stiffness preceded reduced LVEF. Further, DOX impaired endothelium-dependent vasodilation at Weeks 2 and 6, which recovered at Weeks 9 and 15. Conversely, contraction with phenylephrine was consistently higher in the DOX-treated group. Furthermore, proteomic analysis on aortic tissue identified increased thrombospondin-1 (THBS1) and alpha-1-antichymotrypsin (SERPINA3) at Weeks 2 and 6. Up-regulated THBS1 and SERPINA3 persisted during follow-up. Finally, THBS1 and SERPINA3 were quantified in plasma of patients. Cancer survivors with anthracycline-induced cardiotoxicity (AICT; LVEF < 50%) showed elevated THBS1 and SERPINA3 levels compared with age-matched control patients (LVEF ≥ 60%). DOX increased arterial stiffness and impaired endothelial function, which both preceded reduced LVEF. Vascular dysfunction restored after DOX therapy cessation, whereas cardiac dysfunction persisted. Further, we identified SERPINA3 and THBS1 as promising biomarkers of DOX-induced cardiovascular toxicity, which were confirmed in AICT patients.

Placenta-Derived Extracellular Vesicles From Preeclamptic Pregnancies Impair Vascular Endothelial Function via Lectin-Like Oxidized LDL Receptor-1.

Preeclampsia is a complex syndrome that includes maternal vascular dysfunction. Syncytiotrophoblast-derived extracellular vesicles from preeclampsia placentas (preeclampsia-STBEVs) were shown to induce endothelial dysfunction, but an endothelial transmembrane mediator is still unexplored. The LOX-1 (lectin-like oxLDL receptor-1) is a transmembrane scavenger receptor that can cause endothelial dysfunction, and its expression is increased in the endothelium of preeclampsia women. In this study, we hypothesized that LOX-1 mediates the effects of preeclampsia-STBEVs on endothelial function. Preeclampsia-STBEVs were collected by perfusion of placentas from women with preeclampsia and in vitro and ex vivo endothelial cell function were assessed. In human umbilical vein endothelial cells, inhibition of LOX-1 with TS20 (LOX-1 blocking antibody) reduced the uptake of preeclampsia-STBEVs (61.3±8.8%). TS20 prevented the activation of ERK (a kinase downstream of LOX-1) and reduced the activation of NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells; 21.1±8.0%) and nitrative stress (23.2±10.3%) that was induced by preeclampsia-STBEVs. Vascular function was assessed by wire myography in isolated mesenteric arteries from pregnant rats that were incubated overnight with preeclampsia-STBEVs±TS20. TS20 prevented endothelium-dependent vasodilation impairment induced by preeclampsia-STBEVs. Nitric oxide contribution to the relaxation was reduced by preeclampsia-STBEVs, which was prevented by TS20. Superoxide dismutase or apocynin, an inhibitor of NOX (nicotinamide adenine dinucleotide phosphate oxidase), restored the impaired endothelium-dependent vasodilation in arteries exposed to preeclampsia-STBEVs. Taken together, our findings demonstrate that LOX-1 mediates the endothelial dysfunction induced by preeclampsia-STBEVs. Our study further expands on the mechanisms that may lead to adverse outcomes in preeclampsia and proposes LOX-1 as a potential target for future interventions.

Abstract P2094: The Regulatory Role Of Sirtuin 6 In Coronary Microcirculation In Hfpef

Coronary vasculature is essential to support the supply oxygen and nutrients to the heart and maintain the normal cardiac function. Obstruction of large vessels of coronaries (atherosclerosis) is well studied, but coronary microvascular dysfunction (CMD), which is associated with diabetic cardiomyopathy, Takotsubo cardiomyopathy, andheart failure with preserved ejection fraction (HFpEF), is understudied. CMD is characterized by impaired endothelial-dependent vasodilation, but detailed mechanisms have yet to be elucidated. Sirtuin 6 (Sirt6) has been implicated in obesity, insulin resistance, type 2 diabetes mellitus, and cardiovascular diseases. Sirt6 protects EC from premature senescence, oxidative stress, and atherosclerosis by sustaining high eNOS levels and preserving cell replication. A recent publication showed that overexpressed Sirt 6 in EC mitigated heart failure with preserved ejection fraction (HFpEF) in diabetes. We hypothesize Sirt 6 deficiency causes CMD in HFpEF How Sirt6 regulates coronary microvascular function remains to be determined. Inducible Sirt6 endothelial-specific knockout and wild-type (WT) mice were fed a chow or high fat and sugar (HFHS) diet. Coronary arterioles were isolated, and endothelial-dependent vasodilation (EDD) was assessed using myography (DMT). Echocardiography and treadmill exercise exertion tests were performed to evaluate cardiac function. Myocardial blood flow (MBF) was measured by doppler. Cardiac fibrosis was detected using trichrome staining, and molecular pathways were elucidated via gene and protein analysis. Our preliminary data show that the EDD of coronary arterioles of Sirt6 endothelial-specific knockout treated with HFHS was impaired, and the mediator of coronary vasodilation switched from NO to H 2 O 2 in the Sirt6 knockout mice. Compared to the WT mice, myocardial blood flow and cardiac function were changed in Sirt6 knockout mice. Our data suggest that Sirt6 regulated coronary microvascular function through endothelial cells, and ablation of Sirt6 in endothelial cells caused CMD and diastolic dysfunction, eventually HFpEF. Further genetic profiling will elucidate the pathways and mechanisms converging with Sirt6 to regulate microvascular function in HFpEF.