17ß-Estradiol promotes sex-specific dysfunction in isolated human arterioles.

Despite data showing that estrogen is vasculoprotective in large conduit arteries, hormone therapy (HT) during menopause has not proven to mitigate cardiovascular disease (CVD) risk. Estrogen exposure through prolonged oral contraceptive use and gender-affirming therapy can also increase cis- and trans-females' risk for future CVD, respectively. The microvasculature is a unique vascular bed that when dysfunctional can independently predict future adverse cardiac events; however, studies on the influence of estrogen on human microvessels are limited. Here, we show that isolated human arterioles from females across the life span maintain nitric oxide (NO)-mediated dilation to flow, whereas chronic (16-20 h) exposure to exogenous (100 nM) 17ß-estradiol promotes microvascular endothelial dysfunction in vessels from adult females of <40 and ≥40 yr of age. The damaging effect of estrogen was more dramatic in arterioles from biological males, as they exhibited both endothelial and smooth muscle dysfunction. Furthermore, females of <40 yr have greater endothelial expression of estrogen receptor-ß (ER-ß) and G protein-coupled estrogen receptor (GPER) compared with females of ≥40 yr and males. Estrogen receptor-α (ER-α), the prominent receptor associated with protective effects of estrogen, was identified within the adventitia as opposed to the endothelium across all groups. To our knowledge, this is the first study to report the detrimental effects of estrogen on the human microvasculature and highlights differences in estrogen receptor expression.NEW & NOTEWORTHY Microvascular dysfunction is an independent predictor of adverse cardiac events; however, the effect of estrogen on the human microcirculation represents a critical knowledge gap. To our knowledge, this is the first study to report sex-specific detrimental effects of chronic estrogen on human microvascular reactivity. These findings may offer insight into the increased CVD risk associated with estrogen use in both cis- and trans-females.

Mitochondrial Fission Protein 1: Emerging Roles in Organellar Form and Function in Health and Disease.

Mitochondrial fission protein 1 (Fis1) was identified in yeast as being essential for mitochondrial division or fission and subsequently determined to mediate human mitochondrial and peroxisomal fission. Yet, its exact functions in humans, especially in regard to mitochondrial fission, remains an enigma as genetic deletion of Fis1 elongates mitochondria in some cell types, but not others. Fis1 has also been identified as an important component of apoptotic and mitophagic pathways suggesting the protein may have multiple, essential roles. This review presents current perspectives on the emerging functions of Fis1 and their implications in human health and diseases, with an emphasis on Fis1's role in both endocrine and neurological disorders.

Pandemic Perspective: Commonalities Between COVID-19 and Cardio-Oncology.

Overlapping commonalities between coronavirus disease of 2019 (COVID-19) and cardio-oncology regarding cardiovascular toxicities (CVT), pathophysiology, and pharmacology are special topics emerging during the pandemic. In this perspective, we consider an array of CVT common to both COVID-19 and cardio-oncology, including cardiomyopathy, ischemia, conduction abnormalities, myopericarditis, and right ventricular (RV) failure. We also emphasize the higher risk of severe COVID-19 illness in patients with cardiovascular disease (CVD) or its risk factors or cancer. We explore commonalities in the underlying pathophysiology observed in COVID-19 and cardio-oncology, including inflammation, cytokine release, the renin-angiotensin-aldosterone-system, coagulopathy, microthrombosis, and endothelial dysfunction. In addition, we examine common pharmacologic management strategies that have been elucidated for CVT from COVID-19 and various cancer therapies. The use of corticosteroids, as well as antibodies and inhibitors of various molecules mediating inflammation and cytokine release syndrome, are discussed. The impact of angiotensin converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) is also addressed, since these drugs are used in cardio-oncology and have received considerable attention during the COVID-19 pandemic, since the culprit virus enters human cells via the angiotensin converting enzyme 2 (ACE2) receptor. There are therefore several areas of overlap, similarity, and interaction in the toxicity, pathophysiology, and pharmacology profiles in COVID-19 and cardio-oncology syndromes. Learning more about either will likely provide some level of insight into both. We discuss each of these topics in this viewpoint, as well as what we foresee as evolving future directions to consider in cardio-oncology during the pandemic and beyond. Finally, we highlight commonalities in health disparities in COVID-19 and cardio-oncology and encourage continued development and implementation of innovative solutions to improve equity in health and healing.

Contrast-enhanced ultrasound detects changes in microvascular blood flow in adults with sickle cell disease.

In patients with sickle cell disease (SCD), poor outcome measures compromise the potential success of clinical trials. Contrast-enhanced ultrasound (CEUS) is a technique that can non-invasively quantify deep tissue microvascular blood flow. We tested the hypothesis that CEUS of forearm skeletal muscle could be used to: 1) assess microvascular abnormalities that occur during vaso-occlusive crisis; and 2) test new therapies for SCD that are targeted to improving the status of the microcirculation. We performed a prospective study, CEUS perfusion imaging of resting forearm muscle was performed in adults with SCD: 1) during and after a pain episode, and 2) before, during, and after a 24-hour infusion of the investigative agent, regadenoson, an adenosine A2A agonist. CEUS destruction-replenishment time-intensity data were analyzed to measure microvascular blood flow, as well as its components, microvascular blood volume and flux rate. Serial CEUS measurements were obtained in 32 adults with SCD. For the studies during crisis, there was a 30% reduction in microvascular blood flow compared to steady-state (p = 0.031), a reduction that was largely due to microvascular flux rate. For the regadenoson group, a non-significant 25% increase in flux rate and 9% increase in microvascular blood flow compared to baseline were detected during infusion. In a study of adults with SCD, CEUS detected changes in microvascular blood flow associated with vaso-occlusive crises. No changes were found during an infusion of the adenosine A2A agonist, regadenoson. This study provides preliminary evidence that CEUS could detect blood flow changes consistent with SCD physiology.

Routine Assessment and Promotion of Physical Activity in Healthcare Settings: A Scientific Statement From the American Heart Association.

Physical inactivity is one of the most prevalent major health risk factors, with 8 in 10 US adults not meeting aerobic and muscle-strengthening guidelines, and is associated with a high burden of cardiovascular disease. Improving and maintaining recommended levels of physical activity leads to reductions in metabolic, hemodynamic, functional, body composition, and epigenetic risk factors for noncommunicable chronic diseases. Physical activity also has a significant role, in many cases comparable or superior to drug interventions, in the prevention and management of >40 conditions such as diabetes mellitus, cancer, cardiovascular disease, obesity, depression, Alzheimer disease, and arthritis. Whereas most of the modifiable cardiovascular disease risk factors included in the American Heart Association's My Life Check - Life's Simple 7 are evaluated routinely in clinical practice (glucose and lipid profiles, blood pressure, obesity, and smoking), physical activity is typically not assessed. The purpose of this statement is to provide a comprehensive review of the evidence on the feasibility, validity, and effectiveness of assessing and promoting physical activity in healthcare settings for adult patients. It also adds concrete recommendations for healthcare systems, clinical and community care providers, fitness professionals, the technology industry, and other stakeholders in order to catalyze increased adoption of physical activity assessment and promotion in healthcare settings and to contribute to meeting the American Heart Association's 2020 Impact Goals.

miR-29 contributes to normal endothelial function and can restore it in cardiometabolic disorders.

We investigated the role of microRNAs (miRNA) in endothelial dysfunction in the setting of cardiometabolic disorders represented by type 2 diabetes mellitus (T2DM). miR-29 was dysregulated in resistance arterioles obtained by biopsy in T2DM patients. Intraluminal delivery of miR-29a-3p or miR-29b-3p mimics restored normal endothelium-dependent vasodilation (EDVD) in T2DM arterioles that otherwise exhibited impaired EDVD Intraluminal delivery of anti-miR-29b-3p in arterioles from non-DM human subjects or rats or targeted mutation of Mir29b-1/a gene in rats led to impaired EDVD and exacerbation of hypertension in the rats. miR-29b-3p mimic increased, while anti-miR-29b-3p or Mir29b-1/a gene mutation decreased, nitric oxide levels in arterioles. The mutation of Mir29b-1/a gene led to preferential differential expression of genes related to nitric oxide including Lypla1. Lypla1 was a direct target of miR-29 and could abrogate the effect of miR-29 in promoting nitric oxide production. Treatment with Lypla1 siRNA improved EDVD in arterioles obtained from T2DM patients or Mir29b-1/a mutant rats or treated with anti-miR-29b-3p. These findings indicate miR-29 is required for normal endothelial function in humans and animal models and has therapeutic potential for cardiometabolic disorders.

Impact of DPP-4 inhibition on acute and chronic endothelial function in humans with type 2 diabetes on background metformin therapy.

Cell culture and animal work indicate that dipeptidyl peptidase-4 (DPP-4) inhibition may exert cardiovascular benefits through favorable effects on the vascular endothelium. Prior human studies evaluating DPP-4 inhibition have shown conflicting results that may in part be related to heterogeneity of background anti-diabetes therapies. No study has evaluated the acute response of the vasculature to DPP-4 inhibition in humans. We recruited 38 patients with type 2 diabetes on stable background metformin therapy for a randomized, double-blind, placebo-controlled crossover trial of DPP-4 inhibition with sitagliptin (100 mg/day). Each treatment period was 8 weeks long separated by 4 weeks of washout. Endothelial function and plasma markers of endothelial activation (intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1)) were measured prior to and 2 hours following acute dosing of sitagliptin or placebo, as well as following 8 weeks of intervention with each pill. Thirty subjects completed the study and were included in analyses. Neither acute nor chronic sitagliptin therapy resulted in significant changes in vascular endothelial function. While post-acute sitagliptin ICAM-1 levels were lower than that post-chronic sitagliptin, the ICAM-1 concentration was not significantly different than pre-acute sitagliptin levels or levels measured in relationship to placebo. There were no significant changes in plasma VCAM-1 levels at any time point. Acute and chronic sitagliptin therapies have neutral effects on the vascular endothelium in the setting of metformin background therapy. In conclusion, our findings suggest DPP-4 inhibition has a neutral effect on cardiovascular risk in patients without a history of heart failure or renal insufficiency. TRIAL REGISTRATION: NCT01859793.

Human endothelial dihydrofolate reductase low activity limits vascular tetrahydrobiopterin recycling.

Tetrahydrobiopterin (BH4) is required for NO synthesis and inhibition of superoxide release from endothelial NO synthase. Clinical trials using BH4 to treat endothelial dysfunction have produced mixed results. Poor outcomes may be explained by the rapid systemic and cellular oxidation of BH4. One of the oxidation products of BH4, 7,8-dihydrobiopterin (7,8-BH2), is recycled back to BH4 by dihydrofolate reductase (DHFR). This enzyme is ubiquitously distributed and shows a wide range of activity depending on species-specific factors and cell type. Information about the kinetics and efficiency of BH4 recycling in human endothelial cells receiving BH4 treatment is lacking. To characterize this reaction, we applied a novel multielectrode coulometric HPLC method that enabled the direct quantification of 7,8-BH2 and BH4, which is not possible with fluorescence-based methodologies. We found that basal untreated BH4 and 7,8-BH2 concentrations in human endothelial cells (ECs) are lower than in bovine and murine endothelioma cells. Treatment of human ECs with BH4 transiently increased intracellular BH4 while accumulating the more stable 7,8-BH2. This was different from bovine or murine ECs, which resulted in preferential BH4 increase. Using BH4 diastereomers, 6S-BH4 and 6R-BH4, the narrow contribution of enzymatic DHFR recycling to total intracellular BH4 was demonstrated. Reduction of 7,8-BH2 to BH4 occurs at very slow rates in cells and needs supraphysiological levels of 7,8-BH2, indicating this reaction is kinetically limited. Activity assays verified that human DHFR has very low affinity for 7,8-BH2 (DHF7,8-BH2) and folic acid inhibits 7,8-BH2 recycling. We conclude that low activity of endothelial DHFR is an important factor limiting the benefits of BH4 therapies, which may be further aggravated by folate supplements.

Relations of exercise blood pressure response to cardiovascular risk factors and vascular function in the Framingham Heart Study.

BACKGROUND: Exercise blood pressure (BP) is an important marker of left ventricular hypertrophy, incident hypertension, and future cardiovascular events. Although impaired vascular function is hypothesized to influence the BP response during exercise, limited data exist on the association of vascular function with exercise BP in the community. METHODS AND RESULTS: Framingham Offspring cohort participants (n=2115, 53% women, mean age 59 years) underwent a submaximal exercise test (first 2 stages of the Bruce protocol), applanation tonometry, and brachial artery flow-mediated dilation testing. We related exercise systolic and diastolic BP at second stage of the Bruce protocol to standard cardiovascular risk factors and to vascular function measures. In multivariable linear regression models, exercise systolic BP was positively related to age, standing BP, standing heart rate, smoking, body mass index, and the total cholesterol-to-high-density cholesterol ratio (P≤0.01 for all). Similar associations were observed for exercise diastolic BP. Carotid-femoral pulse wave velocity (P=0.02), central pulse pressure (P<0.0001), mean arterial pressure (P=0.04), and baseline brachial flow (P=0.002) were positively associated with exercise systolic BP, whereas flow-mediated dilation was negatively associated (P<0.001). For exercise diastolic BP, forward pressure wave amplitude was negatively related (P<0.0001), whereas mean arterial pressure was positively related (P<0.0001). CONCLUSIONS: Increased arterial stiffness and impaired endothelial function are significant correlates of a higher exercise systolic BP response. Our findings suggest that impaired vascular function may contribute to exaggerated BP responses during daily living, resulting in repetitive increments in load on the heart and vessels and increased cardiovascular disease risk.

Effect of sulfasalazine on inflammation and endothelial function in patients with established coronary artery disease.

Inflammation is critical for atherosclerosis development and may be a target for risk-reduction therapy. In experimental studies, activation of the inflammatory regulator, nuclear factor kappa B (NFlB), contributes to endothelial activation and reduced nitric oxide production. We treated patients with coronary artery disease with sulfasalazine, an inhibitor of NFκB, and placebo in a randomized, double-blind, crossover study design. Brachial artery flow-mediated dilation (FMD) and digital vascular function were measured at baseline and after each 6-week treatment period. Of the 53 patients enrolled in the crossover study, 32 (age 60 ± 10, 22% female) completed all the visits, with a high rate of study withdrawal due to gastrointestinal side effects. In a subset of 10 participants, we compared the effects of 4 days of sulfasalazine treatment (n = 5) to no treatment (n = 5) on NFκB-regulated gene expression in peripheral blood mononuclear cells. Tumor necrosis factor α-stimulated expression of CD69 and NFlB subunit p50 was significantly blunted after 4 days of sulfasalazine treatment but not after no treatment. However, FMD and digital vasodilator response did not significantly change from baseline with long-term sulfasalazine treatment. Short-term sulfasalazine inhibited NFlB activity; however, long-term treatment was poorly tolerated and did not improve endothelial function. Our findings suggest that sulfasalazine therapy is not the optimal anti-inflammatory treatment for reversing endothelial dysfunction in cardiovascular disease. Further studies are warranted to investigate the potential for NFlB inhibition to reduce cardiovascular risk.

Nitric oxide synthase-dependent vasodilation of human subcutaneous arterioles correlates with noninvasive measurements of endothelial function.

BACKGROUND: Noninvasive measurements of endothelial function predict future adverse cardiovascular events, but offer limited opportunities for mechanistic insights into phenotypic observations. Subcutaneous adipose arterioles, accessible through minimally invasive methods, provide an opportunity for complimentary mechanistic studies. Limited data relating subcutaneous arteriolar endothelial function, cardiovascular risk factors, and noninvasive measurements of endothelial function currently exist. METHODS: Forty-four subjects underwent noninvasive studies of endothelial function (brachial reactivity (flow-mediated dilation (FMD) and digital pulse arterial tonometry (PAT)) and measurements of endothelial-dependent vasodilation of gluteal subcutaneous arterioles to acetylcholine. Arteriolar endothelial function was measured (i) percent vasodilation to maximal acetylcholine dose (10(-5) mol/l) and (ii) total area under the curve (AUC) for the entire acetylcholine dose-response curve (total AUC-acetylcholine (Ach), doses 10(-10)-10(-5) mol/l). RESULTS: Acetylcholine responses were almost completely nitric oxide (NO) dependent. Total AUC-Ach predicted FMD and PAT, but maximal acetylcholine vasodilation was not associated with these measures. A history of hypertension, diabetes, smoking, and low-density lipoprotein cholesterol levels were independent predictors of total AUC-Ach. In regression models, total AUC-Ach independently predicted FMD. CONCLUSIONS: Acetylcholine vasodilator responses in human gluteal subcutaneous arterioles are NO synthase dependent and correlate with cardiac risk factors and in vivo measures of endothelial function. These data suggest subcutaneous arterioles offer an opportunity for translational studies of mechanisms of modulating NO bioavailability relevant to in vivo endothelial function measures.

Arteriolar function in visceral adipose tissue is impaired in human obesity.

OBJECTIVE: The purpose of this study was to characterize the relationship between adipose tissue phenotype and depot-specific microvascular function in fat. METHODS AND RESULTS: In 30 obese subjects (age 42±11 years, body mass index 46±11 kg/m(2)) undergoing bariatric surgery, we intraoperatively collected visceral and subcutaneous adipose tissue and characterized depot-specific adipose phenotypes. We assessed vasomotor function of the adipose microvasculature using videomicroscopy of small arterioles (75-250 µm) isolated from different fat compartments. Endothelium-dependent, acetylcholine-mediated vasodilation was severely impaired in visceral arterioles, compared to the subcutaneous depot (P<0.001 by ANOVA). Nonendothelium dependent responses to papaverine and nitroprusside were similar. Endothelial nitric oxide synthase inhibition with N(ω)-nitro-l-arginine methyl ester reduced subcutaneous vasodilation but had no effect on severely blunted visceral arteriolar responses. Visceral fat exhibited greater expression of proinflammatory, oxidative stress-related, hypoxia-induced, and proangiogenic genes; increased activated macrophage populations; and had a higher capacity for cytokine production ex vivo. CONCLUSIONS: Our findings provide clinical evidence that the visceral microenvironment may be intrinsically toxic to arterial health providing a potential mechanism by which visceral adiposity burden is linked to atherosclerotic vascular disease. Our findings also support the evolving concept that both adipose tissue quality and quantity may play significant roles in shaping cardiovascular phenotypes in human obesity.

Natural antioxidants and hypertension: promise and challenges.

Hypertension reigns as a leading cause of cardiovascular morbidity and mortality worldwide. Excessive reactive oxygen species (ROS) have emerged as a central common pathway by which disparate influences may induce and exacerbate hypertension. Potential sources of excessive ROS in hypertension include nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, mitochondria, xanthine oxidase, endothelium-derived NO synthase, cyclooxygenase 1 and 2, cytochrome P450 epoxygenase, and transition metals. While a significant body of epidemiological and clinical data suggests that antioxidant-rich diets reduce blood pressure and cardiovascular risk, randomized trials and population studies using natural antioxidants have yielded disappointing results. The reasons behind this lack of efficacy are not completely clear, but likely include a combination of (1) ineffective dosing regimens, (2) the potential pro-oxidant capacity of some of these agents, (3) selection of subjects less likely to benefit from antioxidant therapy (too healthy or too sick), and (4) inefficiency of nonspecific quenching of prevalent ROS versus prevention of excessive ROS production. Commonly used antioxidants include Vitamins A, C and E, L-arginine, flavanoids, and mitochondria-targeted agents (Coenzyme Q10, acetyl-L-carnitine, and alpha-lipoic acid). Various reasons, including incomplete knowledge of the mechanisms of action of these agents, lack of target specificity, and potential interindividual differences in therapeutic efficacy preclude us from recommending any specific natural antioxidant for antihypertensive therapy at this time. This review focuses on recent literature evaluating naturally occurring antioxidants with respect to their impact on hypertension.

Lifestyle choices and endothelial function: risk and relevance.

Cardiovascular disease remains the leading cause of death and disability in industrialized nations. The risk of cardiovascular disease is significantly reduced by lifestyle choices that promote cardiovascular health. Epidemiological data demonstrate that poor dietary choices, lack of exercise, smoking, obesity, stress, and pollution all increase cardiovascular risk. Poor habits and choices also have been shown to have adverse effects on vascular endothelial homeostasis leading to the development of endothelial dysfunction. Endothelial dysfunction includes broad regulatory changes leading to the expression of a vasoconstrictive, pro-thrombotic, and pro-inflammatory phenotype of the vascular endothelium. Interest in assessing lifestyle interventions as they relate to endothelial function has been encouraged by data demonstrating that measurements of endothelial function in easily accessible vascular beds such as the brachial artery correlate with risk for future cardiovascular events. Given the logistical difficulties and costs of performing large scale clinical trials assessing the ability of many lifestyle interventions designed to reduce cardiovascular risk, employing measures of endothelial function as a surrogate outcome for cardiovascular risk has allowed researchers to determine the biological plausibility of epidemiological data in this area with smaller studies. Newer study techniques, including genomic methodologies, now allow for better delineation of the mechanisms by which lifestyle choices affect the vascular endothelium and of the role of genetic variation in modifying these effects. This review discusses the effects of lifestyle choices on vascular endothelial function, the role and relevance of using studies that assess endothelial function in assessing cardiovascular risk, and future research directions in this area.

Effects of black tea consumption on plasma catechins and markers of oxidative stress and inflammation in patients with coronary artery disease.

We previously demonstrated that black tea consumption reverses endothelial dysfunction in patients with coronary artery disease. To investigate potential mechanisms of this effect, we examined plasma catechins and systemic markers of oxidation, inflammation, and antioxidant protection from 66 subjects enrolled in that study. We collected samples at baseline, 2 h after 450 ml of black tea (acute), after 4 weeks of 900 ml of black tea per day (chronic), and after acute and chronic consumption of water. Total catechins increased 33% after acute tea (P < 0.05) and 29% after chronic tea (P < 0.05). Of individual catechins, plasma epicatechin gallate (ECG) concentration significantly increased with acute tea consumption, and plasma epicatechin (EC) increased with chronic tea consumption. Tea consumption did not improve plasma antioxidant capacity and did not reduce urinary 8-hydroxy-2'-deoxyguanosine, or urinary 8-isoprostane levels. Changes in catechin levels did not correlate with changes in endothelial function, plasma markers of oxidative stress, or C-reactive protein. In contrast, endothelial function at baseline correlated with dietary flavonoid intake (beta = 0.32, P = 0.02) and with baseline plasma EC concentration after adjusting for confounding variables (beta = 0.39, P = 0.03). These findings suggest that the benefits of black tea consumption on endothelial function may not be attributable to tea catechins or a systemic antioxidant or anti-inflammatory effect. Chronic dietary flavonoid status appears to relate to endothelial function, possibly suggesting that other flavonoids or polyphenolic components of tea favorably influence vascular health and risk for cardiovascular disease.

Body mass index and total and cardiovascular mortality in men with a history of cardiovascular disease.

BACKGROUND: Previous studies designed to identify an association between body mass index (BMI) (calculated as weight in kilograms divided by the square of height in meters) and cardiovascular or total mortality in populations with known atherosclerotic disease have shown conflicting results. In this study, we used the Physicians' Health Study enrollment cohort to examine the risk of total and cardiovascular mortality among men reporting a history of myocardial infarction or stroke, excluding those who reported a history of cancer. METHODS: Cause-specific death was ascertained for 5010 men during a mean follow-up of 5.0 years. End points were classified as total deaths and deaths due to cardiovascular causes. Four BMI categories (<22.0, 22.0-24.9 [referent], 25.0-27.9, and > or =28.0) were created a priori. We used proportional hazards models to calculate age and multivariate-adjusted relative risks (RRs) for each BMI category for each end point. RESULTS: Compared with men with a BMI of 22.0 to 24.9, men with a BMI of 28.0 or greater had an age-adjusted RR of 1.11 (95% confidence interval [CI], 0.91-1.36), a multivariate RR of 1.04 (95% CI, 0.84-1.28) in a model that did not include biological mediators of obesity, and a multivariate RR of 1.06 (95% CI, 0.78-1.44) in a model that included these mediators. The RRs for cardiovascular mortality were similar, at 1.07 (95% CI, 0.85-1.35), 1.01 (95% CI, 0.79-1.29), and 1.01 (95% CI, 0.71-1.43), respectively. A BMI of less than 22.0 was associated with a small increased risk of total mortality and cardiovascular mortality. CONCLUSION: These findings indicate that elevated BMI may not be strongly associated with total or cardiovascular mortality among men with previously manifested coronary artery disease.