Chronic therapy with isosorbide-5-mononitrate causes endothelial dysfunction, oxidative stress, and a marked increase in vascular endothelin-1 expression

Vascular protein disulfide isomerase A1 mediates endothelial dysfunction induced by angiotensin II in mice

AIM

Protein disulfide isomerases (PDIs) are involved in platelet aggregation and intravascular thrombosis, but their role in regulating endothelial function is unclear. Here, we characterized the involvement of vascular PDIA1 in angiotensin II (Ang II)-induced endothelial dysfunction in mice.

METHODS

Endothelial dysfunction was induced in C57BL/6JCmd male mice via Ang II subcutaneous infusion, and PDIA1 was inhibited with bepristat. Endothelial function was assessed in vivo with magnetic resonance imaging and ex vivo with a myography, while arterial stiffness was measured as pulse wave velocity. Nitric oxide (NO) bioavailability was measured in the aorta (spin-trapping electron paramagnetic resonance) and plasma (NO2 - and NO3 - levels). Oxidative stress, eNOS uncoupling (DHE-based aorta staining), and thrombin activity (thrombin-antithrombin complex; calibrated automated thrombography) were evaluated.

RESULTS

The inhibition of PDIA1 by bepristat in Ang II-treated mice prevented the impairment of NO-dependent vasodilation in the aorta as evidenced by the response to acetylcholine in vivo, increased systemic NO bioavailability and the aortic NO production, and decreased vascular stiffness. Bepristat's effect on NO-dependent function was recapitulated ex vivo in Ang II-induced endothelial dysfunction in isolated aorta. Furthermore, bepristat diminished the Ang II-induced eNOS uncoupling and overproduction of ROS without affecting thrombin activity.

CONCLUSION

In Ang II-treated mice, the inhibition of PDIA1 normalized the NO-ROS balance, prevented endothelial eNOS uncoupling, and, thereby, improved vascular function. These results indicate the importance of vascular PDIA1 in regulating endothelial function, but further studies are needed to elucidate the details of the mechanisms involved.

Comprehensive Management of ANOCA, Part 2-Program Development, Treatment, and Research Initiatives: JACC State-of-the-Art Review

Centers specializing in coronary function testing are critical to ensure a systematic approach to the diagnosis and treatment of angina with nonobstructive coronary arteries (ANOCA). Management leveraging lifestyle, pharmacology, and device-based therapeutic options for ANOCA can improve angina burden and quality of life in affected patients. Multidisciplinary care teams that can tailor and titrate therapies based on individual patient needs are critical to the success of comprehensive programs. As coronary function testing for ANOCA is more widely adopted, collaborative research initiatives will be fundamental to improve ANOCA care. These efforts will require standardized symptom assessments and data collection, which will propel future large-scale clinical trials.

A medication-wide association study to identify medications associated with incident clinically significant diabetic retinopathy

Background

Diabetic retinopathy, a common microvascular complication of diabetes mellitus, is one of the leading causes of vision loss worldwide. Although some oral drugs have been suggested to affect the risk of diabetic retinopathy, systematic evaluation about the associations between medications and diabetic retinopathy is still absent.

Objective

To comprehensively investigate associations of systemic medications with incident clinically significant diabetic retinopathy (CSDR).

Design

Population-based cohort study.

Methods

From 2006 to 2009, more than 26 000 participants residing in New South Wales were enrolled in the 45 and Up study. Diabetic participants with self-reported physician diagnosis or records of anti-diabetic medication prescriptions were finally included in the current analysis. CSDR was defined as diabetic retinopathy cases requiring retinal photocoagulation recorded in the Medicare Benefits Schedule database from 2006 to 2016. Prescriptions of systemic medication from 5 years to 30 days prior to CSDR were retrieved from the Pharmaceutical Benefits Scheme. The study participants were equally split into training and testing datasets. Logistic regression analyses were performed for the association between each of systemic medication and CSDR in the training dataset. After controlling the false discovery rate (FDR), significant associations were further validated in the testing dataset.

Results

The 10-year incidence of CSDR was 3.9% (n = 404). A total of 26 systemic medications were found to be positively associated with CSDR, among which 15 were validated by the testing dataset. Additional adjustments for pertinent comorbidities suggested that isosorbide mononitrate (ISMN) (OR: 1.87, 95%CI: 1.00-3.48), calcitriol (OR: 4.08, 95% CI: 2.02-8.24), three insulins and analogues (e.g., intermediate-acting human insulin, OR: 4.28, 95% CI: 1.69-10.8), five anti-hypertensive medications (e.g., furosemide, OR: 2.53, 95% CI: 1.77-3.61), fenofibrate (OR: 1.96, 95% CI: 1.36-2.82) and clopidogrel (OR: 1.72, 95% CI: 1.15-2.58) were independently associated with CSDR.

Conclusion

This study investigated the association of a full spectrum of systemic medications with incident CSDR. ISMN, calcitriol, clopidogrel, a few subtypes of insulin, anti-hypertensive and cholesterol-lowering medications were found to be associated with incident CSDR.

Vascular redox signaling, eNOS uncoupling and endothelial dysfunction in the setting of transportation noise exposure or chronic treatment with organic nitrates

SIGNIFICANCE

Cardiovascular disease and drug-induced health side effects are frequently associated with - or even caused by - an imbalance between the concentrations of reactive oxygen and nitrogen species (RONS) and antioxidants respectively determining the metabolism of these harmful oxidants.

RECENT ADVANCES

According to the "kindling radical" hypothesis, initial formation of RONS may further trigger the additional activation of RONS formation under certain pathological conditions. The present review will specifically focus on a dysfunctional, uncoupled endothelial nitric oxide synthase (eNOS) caused by RONS in the setting of transportation noise exposure or chronic treatment with organic nitrates, especially nitroglycerin. We will further describe the various "redox switches" that are proposed to be involved in the uncoupling process of eNOS.

CRITICAL ISSUES

In particular, the oxidative depletion of tetrahydrobiopterin (BH4), and S-glutathionylation of the eNOS reductase domain will be highlighted as major pathways for eNOS uncoupling upon noise exposure or nitroglycerin treatment. In addition, oxidative disruption of the eNOS dimer, inhibitory phosphorylation of eNOS at threonine or tyrosine residues, redox-triggered accumulation of asymmetric dimethylarginine (ADMA) and L-arginine deficiency will be discussed as alternative mechanisms of eNOS uncoupling.

FUTURE DIRECTIONS

The clinical consequences of eNOS dysfunction due to uncoupling on cardiovascular disease will be summarized also providing a template for future clinical studies on endothelial dysfunction caused by pharmacological or environmental risk factors.

Elderberries as a potential supplement to improve vascular function in a SARS-CoV-2 environment

Coronavirus disease 2019 (COVID-19) pandemic has been triggered by the severe acute respiratory syndrome coronavirus (SARS-CoV-2). Although recent studies demonstrate that SARS-CoV-2 possibly does not directly infect endothelial cells (EC), the endothelium may be affected as a secondary response due to the damage of neighboring cells, circulating pro-inflammatory cytokines, and/or other mechanisms. Long-term COVID-19 symptoms specifically nonrespiratory symptoms are due to the persistence of endothelial dysfunction (ED). Based on the literature, anthocyanins a major subgroup of flavonoid polyphenols found in berries, have been well researched for their vascular protective properties as well as the prevention of cardiovascular disease (CVD)-related deaths. Elderberries have been previously used as a natural remedy for treating influenza, cold, and consequently cardiovascular health due to a high content of cyanidin-3-glucoside (C3G) a major anthocyanin found in the human diet. The literature reported many studies demonstrating that EE has both antiviral and vascular protective properties that should be further investigated as a nutritional component used against the (in)direct effect of SARS-CoV-2 in vascular function. PRACTICAL APPLICATIONS: While previous work among the literature looks promising and builds a suggestion for investigating elderberry extract (EE) against COVID-19, further in vitro and in vivo research is required to fully evaluate EE mechanisms of action and its use as a supplement to aid current therapies.

Heart Failure with Preserved Ejection Fraction: Pathogenesis, Diagnosis, Exercise, and Medical Therapies

Heart failure with preserved ejection fraction (HFpEF) accounts for more than one-half of total heart failure cases, with a high prevalence and poor prognosis, especially in older and female patients. Patients with HFpEF are characterized by hypertension, left ventricular hypertrophy, and diastolic dysfunction, and the main symptoms are dyspnea and exercise intolerance. HFpEF is currently poorly studied, and pharmacological treatment for HFpEF is still underexplored. Accumulating clinical trials have shown that exercise could exert benefits on diastolic dysfunction and quality of life in patients with HFpEF. However, there is a high limitation for applying exercise therapy due to exercise intolerance in patients with HFpEF. Key effectors of exercise-protection could be novel therapeutic targets for developing drugs to prevent and treat HFpEF. In this review article, we provide an overview of the pathogenic factors, diagnostic methods, research animal models, the mechanisms of exercise-mediated cardiac protection, and current treatments for HFpEF.

Long-Term Effects of Aircraft Noise Exposure on Vascular Oxidative Stress, Endothelial Function and Blood Pressure: No Evidence for Adaptation or Tolerance Development

Transportation noise is recognized as an important cardiovascular risk factor. Key mechanisms are noise-triggered vascular inflammation and oxidative stress with subsequent endothelial dysfunction. Here, we test for adaptation or tolerance mechanisms in mice in response to chronic noise exposure. C57BL/6J mice were exposed to aircraft noise for 0, 4, 7, 14 and 28d at a mean sound pressure level of 72 dB(A) and peak levels of 85 dB(A). Chronic aircraft noise exposure up to 28d caused persistent endothelial dysfunction and elevation of blood pressure. Likewise, reactive oxygen species (ROS) formation as determined by dihydroethidium (DHE) staining and HPLC-based measurement of superoxide formation in the aorta/heart/brain was time-dependently increased by noise. Oxidative burst in the whole blood showed a maximum at 4d or 7d of noise exposure. Increased superoxide formation in the brain was mirrored by a downregulation of neuronal nitric oxide synthase (Nos3) and transcription factor Foxo3 genes, whereas Vcam1 mRNA, a marker for inflammation was upregulated in all noise exposure groups. Induction of a pronounced hearing loss in the mice was excluded by auditory brainstem response audiometry. Endothelial dysfunction and inflammation were present during the entire 28d of aircraft noise exposure. ROS formation gradually increases with ongoing exposure without significant adaptation or tolerance in mice in response to chronic noise stress at moderate levels. These data further illustrate health side effects of long-term noise exposure and further strengthen a consequent implementation of the WHO noise guidelines in order to prevent the development of noise-related future cardiovascular disease.

Nitric Oxide as a Central Molecule in Hypertension: Focus on the Vasorelaxant Activity of New Nitric Oxide Donors

Cardiovascular diseases include all types of disorders related to the heart or blood vessels. High blood pressure is an important risk factor for cardiac complications and pathological disorders. An increase in circulating angiotensin-II is a potent stimulus for the expression of reactive oxygen species and pro-inflammatory cytokines that activate oxidative stress, perpetuating a deleterious effect in hypertension. Studies demonstrate the capacity of NO to prevent platelet or leukocyte activation and adhesion and inhibition of proliferation, as well as to modulate inflammatory or anti-inflammatory reactions and migration of vascular smooth muscle cells. However, in conditions of low availability of NO, such as during hypertension, these processes are impaired. Currently, there is great interest in the development of compounds capable of releasing NO in a modulated and stable way. Accordingly, compounds containing metal ions coupled to NO are being investigated and are widely recognized as having great relevance in the treatment of different diseases. Therefore, the exogenous administration of NO is an attractive and pharmacological alternative in the study and treatment of hypertension. The present review summarizes the role of nitric oxide in hypertension, focusing on the role of new NO donors, particularly the metal-based drugs and their protagonist activity in vascular function.

ISMN-loaded PLGA-PEG nanoparticles conjugated with anti-Staphylococcus aureus α-toxin inhibit Staphylococcus aureus biofilms in chronic rhinosinusitis

Background: Staphylococcus aureus biofilms were linked to negative postsurgical outcomes of chronic rhinosinusitis (CRS). This study aims to develop a targeted nanoparticle and characterize its bactericidal effects. Methods: The authors prepared ISMN-loaded poly-lactide-co-glycolide acid (PLGA) and polyethylene glycol (PEG) nanoparticles conjugated with anti-S. aureus α-toxin (AA; ISMN-PLGA-PEG-AA), and determined its bactericidal and toxic effects. The antibiofilm propriety of ISMN-PLGA-PEG-AA was further investigated in a sheep CRS model. Results: ISMN-PLGA-PEG-AA had no toxic effect, while ISMN, ISMN-PLGA-PEG and ISMN-PLGA-PEG-AA had significantly anti-S. aureus effects. The blood concentrations and mRNA levels in sinus tissues of IL-4, IL-8 and IFN-γ in the sheep CRS model were significantly low. Conclusion: ISMN-PLGA-PEG-AA can effectively inhibit S. aureus biofilm, and is a promising drug for CRS treatment.

Endothelin-1 axes in the framework of predictive, preventive and personalised (3P) medicine

Endothelin-1 (ET-1) is involved in the regulation of a myriad of processes highly relevant for physical and mental well-being; female and male health; in the modulation of senses, pain, stress reactions and drug sensitivity as well as healing processes, amongst others. Shifted ET-1 homeostasis may influence and predict the development and progression of suboptimal health conditions, metabolic impairments with cascading complications, ageing and related pathologies, cardiovascular diseases, neurodegenerative pathologies, aggressive malignancies, modulating, therefore, individual outcomes of both non-communicable and infectious diseases such as COVID-19. This article provides an in-depth analysis of the involvement of ET-1 and related regulatory pathways in physiological and pathophysiological processes and estimates its capacity as a predictor of ageing and related pathologies,a sensor of lifestyle quality and progression of suboptimal health conditions to diseases for their targeted preventionand as a potent target for cost-effective treatments tailored to the person.

Apocynin attenuates diabetic cardiomyopathy by suppressing ASK1-p38/JNK signaling

Diabetic cardiomyopathy (DCM) significantly increased the morbidity of heart failure in diabetic patients. Long-time oxidative stress is an indisputable contributor for DCM development. Apocynin (APO) has been suggested to be a potential drug against oxidative stress. The study aims to find out the effects of APO on DCM and the related mechanisms. Mice were randomly divided into four groups: control (CON), APO, DCM and DCM + APO. Echocardiography analyses, histological analyses, Western blot and RT-PCR were used to explore the roles and mechanisms of APO in DCM. Isolated neonatal rat cardiomyocytes (NRCMs) and cardiac fibroblasts (CFs) were used for further confirming the APO treatment effects in vitro. Deteriorated cardiac function, enlarged cardiomyocytes, excess cardiac fibrosis and significant cardiac oxidative stress were observed in DCM group. However, APO treatment successfully improved cardiac function, decreased cardiac hypertrophy and fibrosis, and depressed oxidative stress. Mechanistically, APO treatment markedly suppressed apoptosis signal regulating kinase 1(ASK1)-p38/c-jun N-terminal kinase (JNK) signaling and reduced apoptosis. It also inhibited NRCM apoptosis and CF activation via depressing ASK1-p38/JNK signaling in vitro. Moreover, adenovirus-mediated ASK1 overexpression completely removed the protection of APO in vitro. In conclusion, APO treatment could effectively attenuate DCM-associated injuries in vivo and protect against high glucose-induced NRCM and CF injuries in vitro via suppressing ASK1-p38/JNK signaling. APO might be a potential ASK1 inhibitor for treating DCM.

Nitrate-functionalized patch confers cardioprotection and improves heart repair after myocardial infarction via local nitric oxide delivery

Nitric oxide (NO) is a short-lived signaling molecule that plays a pivotal role in cardiovascular system. Organic nitrates represent a class of NO-donating drugs for treating coronary artery diseases, acting through the vasodilation of systemic vasculature that often leads to adverse effects. Herein, we design a nitrate-functionalized patch, wherein the nitrate pharmacological functional groups are covalently bound to biodegradable polymers, thus transforming small-molecule drugs into therapeutic biomaterials. When implanted onto the myocardium, the patch releases NO locally through a stepwise biotransformation, and NO generation is remarkably enhanced in infarcted myocardium because of the ischemic microenvironment, which gives rise to mitochondrial-targeted cardioprotection as well as enhanced cardiac repair. The therapeutic efficacy is further confirmed in a clinically relevant porcine model of myocardial infarction. All these results support the translational potential of this functional patch for treating ischemic heart disease by therapeutic mechanisms different from conventional organic nitrate drugs.

GLP-1 Analog Liraglutide Improves Vascular Function in Polymicrobial Sepsis by Reduction of Oxidative Stress and Inflammation

Sepsis causes high mortality in the setting of septic shock. LEADER and other trials revealed cardioprotective and anti-inflammatory properties of glucagon-like peptide-1 (GLP-1) analogs like liraglutide (Lira). We previously demonstrated improved survival in lipopolysaccharide (LPS)-induced endotoxemia by inhibition of GLP-1 degradation. Here we investigate the effects of Lira in the polymicrobial sepsis model of cecal ligation and puncture (CLP). C57BL/6J mice were intraperitoneally injected with Lira (200 µg/kg/d; 3 days) and sepsis induced by CLP after one day of GLP-1 analog treatment. Survival and body temperature were monitored. Aortic vascular function (isometric tension recording), protein expression (immunohistochemistry and dot blot) and gene expression (qRT-PCR) were determined. Endothelium-dependent relaxation in the aorta was impaired by CLP and correlated with markers of inflammation (e.g., interleukin 6 and inducible nitric oxide synthase) and oxidative stress (e.g., 3-nitrotyrosine) was higher in septic mice, all of which was almost completely normalized by Lira therapy. We demonstrate that the GLP-1 analog Lira ameliorates sepsis-induced endothelial dysfunction by the reduction of vascular inflammation and oxidative stress. Accordingly, the findings suggest that the antioxidant and anti-inflammatory effects of GLP-1 analogs may be a valuable tool to protect the cardiovascular system from dysbalanced inflammation in polymicrobial sepsis.

Ablation of lysozyme M-positive cells prevents aircraft noise-induced vascular damage without improving cerebral side effects

Aircraft noise induces vascular and cerebral inflammation and oxidative stress causing hypertension and cardiovascular/cerebral dysfunction. With the present studies, we sought to determine the role of myeloid cells in the vascular vs. cerebral consequences of exposure to aircraft noise. Toxin-mediated ablation of lysozyme M+ (LysM+) myeloid cells was performed in LysMCreiDTR mice carrying a cre-inducible diphtheria toxin receptor. In the last 4d of toxin treatment, the animals were exposed to noise at maximum and mean sound pressure levels of 85 and 72 dB(A), respectively. Flow cytometry analysis revealed accumulation of CD45+, CD11b+, F4/80+, and Ly6G-Ly6C+ cells in the aortas of noise-exposed mice, which was prevented by LysM+ cell ablation in the periphery, whereas brain infiltrates were even exacerbated upon ablation. Aircraft noise-induced increases in blood pressure and endothelial dysfunction of the aorta and retinal/mesenteric arterioles were almost completely normalized by ablation. Correspondingly, reactive oxygen species in the aorta, heart, and retinal/mesenteric vessels were attenuated in ablated noise-exposed mice, while microglial activation and abundance in the brain was greatly increased. Expression of phagocytic NADPH oxidase (NOX-2) and vascular cell adhesion molecule-1 (VCAM-1) mRNA in the aorta was reduced, while NFκB signaling appeared to be activated in the brain upon ablation. In sum, we show dissociation of cerebral and peripheral inflammatory reactions in response to aircraft noise after LysM+ cell ablation, wherein peripheral myeloid inflammatory cells represent a dominant part of the pathomechanism for noise stress-induced cardiovascular effects and their central nervous counterparts, microglia, as key mediators in stress responses.

Noise-Induced Vascular Dysfunction, Oxidative Stress, and Inflammation Are Improved by Pharmacological Modulation of the NRF2/HO-1 Axis

Vascular oxidative stress, inflammation, and subsequent endothelial dysfunction are consequences of traditional cardiovascular risk factors, all of which contribute to cardiovascular disease. Environmental stressors, such as traffic noise and air pollution, may also facilitate the development and progression of cardiovascular and metabolic diseases. In our previous studies, we investigated the influence of aircraft noise exposure on molecular mechanisms, identifying oxidative stress and inflammation as central players in mediating vascular function. The present study investigates the role of heme oxygenase-1 (HO-1) as an antioxidant response preventing vascular consequences following exposure to aircraft noise. C57BL/6J mice were treated with the HO-1 inducer hemin (25 mg/kg i.p.) or the NRF2 activator dimethyl fumarate (DMF, 20 mg/kg p.o.). During therapy, the animals were exposed to noise at a maximum sound pressure level of 85 dB(A) and a mean sound pressure level of 72 dB(A). Our data showed a marked protective effect of both treatments on animals exposed to noise for 4 days by normalization of arterial hypertension and vascular dysfunction in the noise-exposed groups. We observed a partial normalization of noise-triggered oxidative stress and inflammation by hemin and DMF therapy, which was associated with HO-1 induction. The present study identifies possible new targets for the mitigation of the adverse health effects caused by environmental noise exposure. Since natural dietary constituents can achieve HO-1 and NRF2 induction, these pathways represent promising targets for preventive measures.

Discovery of new therapeutic redox targets for cardioprotection against ischemia/reperfusion injury and heart failure

Global epidemiological studies reported a shift from maternal/infectious communicable diseases to chronic non-communicable diseases and a major part is attributable to atherosclerosis and metabolic disorders. Accordingly, ischemic heart disease was identified as a leading risk factor for global mortality and morbidity with a prevalence of 128 million people. Almost 9 million premature deaths can be attributed to ischemic heart disease and subsequent acute myocardial infarction and heart failure, also representing a substantial socioeconomic burden. As evidenced by typical oxidative stress markers such as lipid peroxidation products or oxidized DNA/RNA bases, the formation of reactive oxygen species by various sources (NADPH oxidases, xanthine oxidase and mitochondrial resperatory chain) plays a central role for the severity of ischemia/reperfusion damage. The underlying mechanisms comprise direct oxidative damage but also adverse redox-regulation of kinase and calcium signaling, inflammation and cardiac remodeling among others. These processes and the role of reactive oxygen species are discussed in the present review. We also present and discuss potential targets for redox-based therapies that are either already established in the clinics (e.g. guanylyl cyclase activators and stimulators) or at least successfully tested in preclinical models of myocardial infarction and heart failure (mitochondria-targeted antioxidants). However, reactive oxygen species have not only detrimental effects but are also involved in essential cellular signaling and may even act protective as seen by ischemic pre- and post-conditioning or eustress - which makes redox therapy quite challenging.

Revisiting pharmacology of oxidative stress and endothelial dysfunction in cardiovascular disease: Evidence for redox-based therapies

According to the latest Global Burden of Disease Study data, non-communicable diseases in general and cardiovascular disease (CVD) in particular are the leading cause of premature death and reduced quality of life. Demographic shifts, unhealthy lifestyles and a higher burden of adverse environmental factors provide an explanation for these findings. The expected growing prevalence of CVD requires enhanced research efforts for identification and characterisation of novel therapeutic targets and strategies. Cardiovascular risk factors including classical (e.g. hypertension, diabetes, hypercholesterolaemia) and non-classical (e.g. environmental stress) factors induce the development of endothelial dysfunction, which is closely associated with oxidant stress and vascular inflammation and results in CVD, particularly in older adults. Most classically successful therapies for CVD display vasoprotective, antioxidant and anti-inflammatory effects, but were originally designed with other therapeutic aims. So far, only a few 'redox drugs' are in clinical use and many antioxidant strategies have not met expectations. With the present review, we summarise the actual knowledge on CVD pathomechanisms, with special emphasis on endothelial dysfunction, adverse redox signalling and oxidative stress, highlighting the preclinical and clinical evidence. In addition, we provide a brief overview of established CVD therapies and their relation to endothelial dysfunction and oxidative stress. Finally, we discuss novel strategies for redox-based CVD therapies trying to explain why, despite a clear link between endothelial dysfunction and adverse redox signalling and oxidative stress, redox- and oxidative stress-based therapies have not yet provided a breakthrough in the treatment of endothelial dysfunction and CVD.

Non-canonical chemical feedback self-limits nitric oxide-cyclic GMP signaling in health and disease

Nitric oxide (NO)-cyclic GMP (cGMP) signaling is a vasoprotective pathway therapeutically targeted, for example, in pulmonary hypertension. Its dysregulation in disease is incompletely understood. Here we show in pulmonary artery endothelial cells that feedback inhibition by NO of the NO receptor, the cGMP forming soluble guanylate cyclase (sGC), may contribute to this. Both endogenous NO from endothelial NO synthase and exogenous NO from NO donor compounds decreased sGC protein and activity. This effect was not mediated by cGMP as the NO-independent sGC stimulator, or direct activation of cGMP-dependent protein kinase did not mimic it. Thiol-sensitive mechanisms were also not involved as the thiol-reducing agent N-acetyl-L-cysteine did not prevent this feedback. Instead, both in-vitro and in-vivo and in health and acute respiratory lung disease, chronically elevated NO led to the inactivation and degradation of sGC while leaving the heme-free isoform, apo-sGC, intact or even increasing its levels. Thus, NO regulates sGC in a bimodal manner, acutely stimulating and chronically inhibiting, as part of self-limiting direct feedback that is cGMP independent. In high NO disease conditions, this is aggravated but can be functionally recovered in a mechanism-based manner by apo-sGC activators that re-establish cGMP formation.

Impact of pulsed electromagnetic field therapy on vascular function and blood pressure in hypertensive individuals

The present study investigated the impact of 12 weeks of pulsed electromagnetic field (PEMF) therapy on peripheral vascular function, blood pressure (BP), and nitric oxide in hypertensive individuals. Thirty hypertensive individuals (SBP > 130 mm Hg and/or MAP > 100 mm Hg) were assigned to either PEMF group (n = 15) or control group (n = 15). During pre-assessment, participants underwent measures of flow-mediated dilation (FMD), BP, and blood draw for nitric oxide (NO). Subsequently, they received PEMF therapy 3x/day for 12 weeks and, at conclusion, returned to the laboratory for post-assessment. Fifteen participants from the PEMF group and 11 participants from the control group successfully completed the study protocol. After therapy, the PEMF group demonstrated significant improvements in FMD and FMD_NOR (normalized to hyperemia), but the control group did not (P = .05 and P = .04, respectively). Moreover, SBP, DBP, and MAP were reduced, but the control group did not (P = .04, .04, and .03, respectively). There were no significant alterations in NO in both groups (P > .05). Twelve weeks of PEMF therapy may improve BP and vascular function in hypertensive individuals. Additional studies are needed to identify the mechanisms by which PEMF affects endothelial function.

Environmental aircraft noise aggravates oxidative DNA damage, granulocyte oxidative burst and nitrate resistance in Ogg1-/- mice

Background: Large epidemiological studies point towards a link between the incidence of arterial hypertension, ischaemic heart disease, metabolic disease and exposure to traffic noise, supporting the role of noise exposure as an independent cardiovascular risk factor. We characterised the underlying molecular mechanisms leading to noise-dependent adverse effects on the vasculature and myocardium in an animal model of aircraft noise exposure and identified oxidative stress and inflammation as central players in mediating vascular and cardiac dysfunction. Here, we studied the impact of noise-induced oxidative DNA damage on vascular function in DNA-repair deficient 8-oxoguanine glycosylase knockout (Ogg1^-/-) mice.Methods and results: Noise exposure (peak sound levels of 85 and mean sound level of 72 dB(A) applied for 4d) caused oxidative DNA damage (8-oxoguanine) and enhanced NOX-2 expression in C57BL/6 mice with synergistic increases in Ogg1^-/- mice (shown by immunohistochemistry). A similar pattern was found for oxidative burst of blood leukocytes and other markers of oxidative stress (4-hydroxynonenal, 3-nitrotyrosine) and inflammation (cyclooxygenase-2). We observed additive impairment of noise exposure and genetic Ogg1 deficiency on endothelium-independent relaxation (nitroglycerine), which may be due to exacerbated oxidative DNA damage leading to leukocyte activation and oxidative aldehyde dehydrogenase inhibition.Conclusions: The finding that chronic noise exposure causes oxidative DNA damage in mice is worrisome since these potential mutagenic lesions could contribute to cancer progression. Human field studies have to demonstrate whether oxidative DNA damage is also found in urban populations with high levels of noise exposure as recently shown for workers with high occupational noise exposure.

Oxidative stress and inflammation contribute to traffic noise-induced vascular and cerebral dysfunction via uncoupling of nitric oxide synthases

Environmental pollution and non-chemical stressors such as mental stress or traffic noise exposure are increasingly accepted as health risk factors with substantial contribution to chronic noncommunicable diseases (e.g. cardiovascular, metabolic and mental). Whereas the mechanisms of air pollution-mediated adverse health effects are well characterized, the mechanisms of traffic noise exposure are not completely understood, despite convincing clinical and epidemiological evidence for a significant contribution of environmental noise to overall mortality and disability. The initial mechanism of noise-induced cardiovascular, metabolic and mental disease is well defined by the „noise reaction model“ and consists of neuronal activation involving the hypothalamic-pituitary-adrenal (HPA) axis as well as the sympathetic nervous system, followed by a classical stress response via cortisol and catecholamines. Stress pathways are initiated by noise-induced annoyance and sleep deprivation/fragmentation. This review highlights the down-stream pathophysiology of noise-induced mental stress, which is based on an induction of inflammation and oxidative stress. We highlight the sources of reactive oxygen species (ROS) involved and the known targets for noise-induced oxidative damage. Part of the review emphasizes noise-triggered uncoupling/dysregulation of endothelial and neuronal nitric oxide synthase (eNOS and nNOS) and its central role for vascular dysfunction.

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Exposure to (traffic) noise causes non-auditory (indirect) cardiovascular and cerebral health harms via neuronal activation.

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Noise activates the HPA axis and sympathetic nervous system increasing levels of stress hormones, vasoconstrictors and ROS.

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Noise induces inflammation and stimulates several ROS sources leading to cerebral and cardiovascular oxidative damage.

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Noise leads to eNOS and nNOS uncoupling contributing to cardiometabolic disease and cognitive impairment.

Exacerbation of adverse cardiovascular effects of aircraft noise in an animal model of arterial hypertension

Arterial hypertension is the most important risk factor for the development of cardiovascular disease. Recently, aircraft noise has been shown to be associated with elevated blood pressure, endothelial dysfunction, and oxidative stress. Here, we investigated the potential exacerbated cardiovascular effects of aircraft noise in combination with experimental arterial hypertension. C57BL/6J mice were infused with 0.5 mg/kg/d of angiotensin II for 7 days, exposed to aircraft noise for 7 days at a maximum sound pressure level of 85 dB(A) and a mean sound pressure level of 72 dB(A), or subjected to both stressors. Noise and angiotensin II increased blood pressure, endothelial dysfunction, oxidative stress and inflammation in aortic, cardiac and/or cerebral tissues in single exposure models. In mice subjected to both stressors, most of these risk factors showed potentiated adverse changes. We also found that mice exposed to both noise and ATII had increased phagocytic NADPH oxidase (NOX-2)-mediated superoxide formation, immune cell infiltration (monocytes, neutrophils and T cells) in the aortic wall, astrocyte activation in the brain, enhanced cytokine signaling, and subsequent vascular and cerebral oxidative stress. Exaggerated renal stress response was also observed. In summary, our results show an enhanced adverse cardiovascular effect between environmental noise exposure and arterial hypertension, which is mainly triggered by vascular inflammation and oxidative stress. Mechanistically, noise potentiates neuroinflammation and cerebral oxidative stress, which may be a potential link between both risk factors. The results indicate that a combination of classical (arterial hypertension) and novel (noise exposure) risk factors may be deleterious for cardiovascular health.

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Noise exposure causes non-auditory cardiovascular/cerebral adverse health effects by oxidative stress and inflammation.

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Aircraft noise causes exacerbated adverse effects on blood pressure and endothelial dysfunction in hypertensive mice.

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Aircraft noise and hypertension potentiate inflammation, ROS formation and oxidative damage in the brain, vessels and heart.

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Aircraft noise and hypertension seem to have enhanced adverse effects on stress responses in different organs.

Exogenous NO Therapy for the Treatment and Prevention of Atherosclerosis

Amyl nitrite was introduced in 1867 as the first molecule of a new class of agents for the treatment of angina pectoris. In the following 150 years, the nitric oxide pathway has been the subject of a number of pharmacological approaches, particularly since when this elusive mediator was identified as one of the most important modulators of vascular homeostasis beyond vasomotion, including platelet function, inflammation, and atherogenesis. While having potent antianginal and antiischemic properties, however, nitric oxide donors are also not devoid of side effects, including the induction of tolerance, and, as shown in the last decade, of oxidative stress and endothelial dysfunction. In turn, endothelial dysfunction is itself felt to be involved in all stages of atherogenesis, from the development of fatty streaks to plaque rupture and thrombosis. In the present review, we summarize the agents that act on the nitric oxide pathway, with a particular focus on their potentially beneficial antiatherosclerotic and unwanted pro-atherosclerotic effects.

Would a right shift of the oxy-hemoglobin dissociation curve improve exercise capacity in patients with heart failure?

Exercise intolerance is a hallmark of symptoms in patients with heart failure. In addition to reduced cardiac output, a series of impairments in pulmonary and vascular systems leads to decreases in oxygen delivery and availability in locomotor muscles. This contributes to exercise intolerance in heart failure. The oxy-hemoglobin dissociation curve is essentially a graph illustrating the relationship between the partial pressure of oxygen (PO₂, X-axis) and oxygen saturation (SaO₂, Y-axis) of hemoglobin. The rightward shift of the curve indicates that hemoglobin's affinity for oxygen decreases and in turn, it may allow the release of more oxygen to tissues. In the present study, we discuss the pathophysiological impairment, which causes exercise intolerance in heart failure patients and suggest a strategy to improve exercise capacity without altering cardiac output via modulating the oxy-hemoglobin dissociation curve.

Effects of isosorbide mononitrate loaded nanoparticles conjugated with anti-Staphylococcus aureus α-toxin on Staphylococcus aureus biofilms

Staphylococcus aureus (S. aureus) is associated with recalcitrant chronic infection, especially in chronic rhinosinusitis (CRS). S. aureus infection and biofilms cause poorer postsurgical outcomes. We developed isosorbide mononitrate (ISMN) loaded nanoparticles conjugated with an anti-Staphylococcus aureus alpha-toxin (anti-S. aureus α-toxin) antibody that could target biofilms and investigated their anti-biofilm effect. Anti-S. aureus α-toxin antibody coupled immunoliposomes were generated. The effect of ISMN immunoliposomes on S. aureus biofilm formation and their anti-biofilm efficacy were examined using the crystal violet method and confocal laser scanning microscopy, respectively. Relative biofilm viability at 24 h was tested using the alamarBlue assay. The biofilm formation inhibitory effect on all concentrations of ISMN immunoliposomes was stronger than that of ISMN liposomes and free ISMN (P<0.05). At concentrations of 45 and 23 mg/ml, the inhibitory effect of ISMN liposomes was stronger than that of free ISMN (P<0.05), while at 11 mg/ml, the inhibitory effect of ISMN liposomes was the same as that of ISMN (P>0.05). At 45 and 23 mg/ml, the inhibitory effect of ISMN immunoliposomes on formed biofilms was greater than that of ISMN liposomes and free ISMN (P<0.05) and the inhibitory effect of ISMN liposomes was stronger than that of free ISMN (P<0.05). At 11 mg/ml, ISMN immunoliposomes, ISMN liposomes, and ISMN had the same effect on formed biofilms (P>0.05). In conclusion, ISMN immunoliposomes nearly completely destroy biofilm structure. ISMN immunoliposomes provide a promising approach for treating infectious diseases caused by S. aureus biofilms, including refractory CRS, chronic skin infection, sepsis, and osteomyelitis.

Microvascular Dysfunction in Heart Failure With Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is an increasingly studied entity accounting for 50% of all diagnosed heart failure and that has claimed its own dignity being markedly different from heart failure with reduced EF in terms of etiology and natural history (Graziani et al., 2018). Recently, a growing body of evidence points the finger toward microvascular dysfunction as the major determinant of the pathological cascade that justifies clinical manifestations (Crea et al., 2017). The high burden of comorbidities such as metabolic syndrome, hypertension, atrial fibrillation, chronic kidney disease, obstructive sleep apnea, and similar, could lead to a systemic inflammatory state that impacts the physiology of the endothelium and the perivascular environment, engaging complex molecular pathways that ultimately converge to myocardial fibrosis, stiffening, and dysfunction (Paulus and Tschope, 2013). These changes could even self-perpetrate with a positive feedback where hypoxia and locally released inflammatory cytokines trigger interstitial fibrosis and hypertrophy (Ohanyan et al., 2018). Identifying microvascular dysfunction both as the cause and the maintenance mechanism of this condition has opened the field to explore specific pharmacological targets like nitric oxide (NO) pathway, sarcomeric titin, transforming growth factor beta (TGF-β) pathway, immunomodulators or adenosine receptors, trying to tackle the endothelial impairment that lies in the background of this syndrome (Graziani et al., 2018;Lam et al., 2018). Yet, many questions remain, and the new data collected still lack a translation to improved treatment strategies. To further elaborate on this tangled and exponentially growing topic, we will review the evidence favoring a microvasculature-driven etiology of this condition, its clinical correlations, the proposed diagnostic workup, and the available/hypothesized therapeutic options to address microvascular dysfunction in the failing heart.

Therapeutic Implications of Nitrite in Hypertension

Nitrite, an anion produced from the oxidative breakdown of nitric oxide (NO), has traditionally been viewed as an inert molecule. However, this dogma has been challenged with the findings that nitrite can be readily reduced to NO under pathological conditions, hence representing a physiologically relevant storage reservoir of NO either in the blood or tissues. Nitrite administration has been demonstrated to improve myocardial function in subjects with heart failure and to lower the blood pressure in hypertensive subjects. Thus, extensive amount of work has since been carried out to investigate the therapeutic potential of nitrite in treating cardiovascular diseases, especially hypertension. Studies done on several animal models of hypertension have demonstrated the efficacy of nitrite in preventing and ameliorating the pathological changes associated with the disease. This brief review of the current findings aims to re-evaluate the use of nitrite for the treatment of hypertension and in particular to highlight its role in improving endothelial function.

NADPH oxidases and oxidase crosstalk in cardiovascular diseases: novel therapeutic targets

Reactive oxygen species (ROS)-dependent production of ROS underlies sustained oxidative stress, which has been implicated in the pathogenesis of cardiovascular diseases such as hypertension, aortic aneurysm, hypercholesterolaemia, atherosclerosis, diabetic vascular complications, cardiac ischaemia-reperfusion injury, myocardial infarction, heart failure and cardiac arrhythmias. Interactions between different oxidases or oxidase systems have been intensively investigated for their roles in inducing sustained oxidative stress. In this Review, we discuss the latest data on the pathobiology of each oxidase component, the complex crosstalk between different oxidase components and the consequences of this crosstalk in mediating cardiovascular disease processes, focusing on the central role of particular NADPH oxidase (NOX) isoforms that are activated in specific cardiovascular diseases. An improved understanding of these mechanisms might facilitate the development of novel therapeutic agents targeting these oxidase systems and their interactions, which could be effective in the prevention and treatment of cardiovascular disorders.

The anti-cancer drug doxorubicin induces substantial epigenetic changes in cultured cardiomyocytes

The anthracycline doxorubicin (DOX) is widely used in cancer therapy with the limitation of cardiotoxicity leading to the development of congestive heart failure. DOX-induced oxidative stress and changes of the phosphoproteome as well as epigenome were described but the exact mechanisms of the adverse long-term effects are still elusive. Here, we tested the impact of DOX treatment on cell death, oxidative stress parameters and expression profiles of proteins involved in epigenetic pathways in a cardiomyocyte cell culture model. Markers of oxidative stress, apoptosis and expression of proteins involved in epigenetic processes were assessed by immunoblotting in cultured rat myoblasts (H9c2) upon treatment with DOX (1 or 5 μM for 24 or 48 h) in adherent viable and detached apoptotic cells. The apoptosis markers cleaved caspase-3 and fractin as well as oxidative stress markers 3-nitrotyrosine and malondialdehyde were dose-dependently increased by DOX treatment. Histone deacetylases (SIRT1 and HDAC2), histone lysine demethylases (KDM3A and LSD1) and histone lysine methyltransferases (SET7 and SMYD1) were significantly regulated by DOX treatment with generation of cleaved protein fragments and posttranslational modifications. Overall, we found significant decrease in histone 3 acetylation in DOX-treated cells. DOX treatment of cultured cardiomyocyte precursor cells causes severe cell death by apoptosis associated with cellular oxidative stress. In addition, significant regulation of proteins involved in epigenetic processes and changes in global histone 3 acetylation were observed. However, the significance and clinical impact of these changes remain elusive.

The impact of pulsed electromagnetic field therapy on blood pressure and circulating nitric oxide levels: a double blind, randomized study in subjects with metabolic syndrome

Purpose: Regulation of blood pressure (BP) is important in reducing the risk for cardiovascular disease. There is growing interest in non-pharmacological methods to treat BP including a novel approach using pulsed electromagnetic field therapy (PEMF). PEMF therapy has been proposed to impact physiological function at the cellular and tissue level and one possible mechanism is through an impact on endothelial function and nitric oxide (NO) related pathways. The focus of the present study was to evaluate the effect of PEMF on BP and NO in subjects with mild to moderate metabolic syndrome.Materials and methods: For 12 weeks, 23 subjects underwent PEMF therapy and 21 subjects underwent sham therapy. BP was measured at rest and near the end of submaximal exercise pre- and 12 week post-therapy. Additionally, plasma NO was measured at similar time points.Results: The PEMF demonstrated an increase in NO after therapy (p = .04) but SHAM did not (p = .37). For resting BP, there were no differences in systolic BP (SBP), diastolic BP (DBP) or mean arterial pressure (MAP) between groups (p > .05). During exercise, PEMF had a reduction in peak SBP (p = .04), but not SHAM (p = .57). PEMF demonstrated significant relationships between baseline SBP and change in SBP following therapy (r = -0.71, p < .01) and between MAP and change in MAP following therapy (r = -0.60, p < .01), but no such relationships were found in SHAM. Subjects with resting hypertension (SBP ≥140 mmHg) in PEMF (n = 11) had significant reductions in SBP, DBP and MAP when compared to SHAM with hypertension (n = 9) (p < .05). In this sub-group analysis, PEMF demonstrated lowered peak SBP (p = .04) at a given exercise load (p = .40) but SHAM did not (p > .05).Conclusion: PEMF may increase plasma NO availability and improve BP at rest and during exercise. However, this beneficial effect appears to be more pronounced in subjects with existing hypertension.

Effect of ranolazine on plasma arginine derivatives and urinary isoprostane 8-iso-PGF2α in patients with myocardial infarction in the randomized RIMINI-Trial

The purpose of the present study was to assess whether 6-week ranolazine application on top of guideline-based treatment impacts on the arginine/NO pathway and urinary isoprostane 8-iso-PGF_2α as marker of oxidative stress in patients directly after a myocardial infarction. 20 patients with unstable angina pectoris and proof of acute cardiac ischemia entered the study. 10 subjects received the study drug ranolazine in addition to standard treatment, the others received only standard treatment. Urine and venous blood were collected before and after treatment. At the end of the study and compared to baseline, homoarginine levels had increased in the control group. This was not the case in ranolazine-patients. Interestingly, in ranolazine-treated-patients arginine plasma levels were significantly higher at the end of the study than at baseline (difference +26 µmol/L, 95% CI 8.6 to 44 µmol/L). ADMA and SDMA levels were not different. Urine levels of the oxidative stress marker 8-iso-PGF_2α tended to be lower in ranolazine-treated patients (−144 pmol/mg creatinine). Findings of this hypothesis-driven study give evidence that ranolazine treatment enhances arginine plasma levels and lowers oxidative stress.

Potential protective effects of red yeast rice in endothelial function against atherosclerotic cardiovascular disease

Atherosclerotic cardiovascular disease (ASCVD) is the deadliest disease in the world, with endothelial injury occurring throughout the course of the disease. Therefore, improvement in endothelial function is of essential importance in the prevention of ASCVD. Red yeast rice (RYR), a healthy traditional Chinese food, has a lipid modulation function and also plays a vital role in the improvement of endothelial reactivity and cardiovascular protection; thus, it is significant in the prevention and treatment of ASCVD. This article reviews the molecular mechanisms of RYR and its related products in the improvement of endothelial function in terms of endothelial reactivity, anti-apoptosis of endothelial progenitor cells, oxidative stress alleviation and anti-inflammation.

The Endothelin Receptor Antagonist Macitentan Improves Isosorbide-5-Mononitrate (ISMN) and Isosorbide Dinitrate (ISDN) Induced Endothelial Dysfunction, Oxidative Stress, and Vascular Inflammation

Objective

Organic nitrates such as isosorbide-5-mononitrate (ISMN) and isosorbide dinitrate (ISDN) are used for the treatment of patients with chronic symptomatic stable coronary artery disease and chronic congestive heart failure. Limiting side effects of these nitrovasodilators include nitrate tolerance and/or endothelial dysfunction mediated by oxidative stress. Here, we tested the therapeutic effects of the dual endothelin (ET) receptor antagonist macitentan in ISMN- and ISDN-treated animals.

Methods and Results

Organic nitrates (ISMN, ISDN, and nitroglycerin (GTN)) augmented the oxidative burst and interleukin-6 release in cultured macrophages, whereas macitentan decreased the oxidative burst in isolated human leukocytes. Male C57BL/6j mice were treated with ISMN (75 mg/kg/d) or ISDN (25 mg/kg/d) via s.c. infusion for 7 days and some mice in addition with 30 mg/kg/d of macitentan (gavage, once daily). ISMN and ISDN in vivo therapy caused endothelial dysfunction but no nitrate (or cross-)tolerance to the organic nitrates, respectively. ISMN/ISDN increased blood nitrosative stress, vascular/cardiac oxidative stress via NOX-2 (fluorescence and chemiluminescence methods), ET1 expression, ET receptor signaling, and markers of inflammation (protein and mRNA level). ET receptor signaling blockade by macitentan normalized endothelial function, vascular/cardiac oxidative stress, and inflammatory phenotype in both nitrate therapy groups.

Conclusion

ISMN/ISDN treatment caused activation of the NOX-2/ET receptor signaling axis leading to increased vascular oxidative stress and inflammation as well as endothelial dysfunction. Our study demonstrates for the first time that blockade of ET receptor signaling by the dual endothelin receptor blocker macitentan improves adverse side effects of the organic nitrates ISMN and ISDN.

New Therapeutic Implications of Endothelial Nitric Oxide Synthase (eNOS) Function/Dysfunction in Cardiovascular Disease

The Global Burden of Disease Study identified cardiovascular risk factors as leading causes of global deaths and life years lost. Endothelial dysfunction represents a pathomechanism that is associated with most of these risk factors and stressors, and represents an early (subclinical) marker/predictor of atherosclerosis. Oxidative stress is a trigger of endothelial dysfunction and it is a hall-mark of cardiovascular diseases and of the risk factors/stressors that are responsible for their initiation. Endothelial function is largely based on endothelial nitric oxide synthase (eNOS) function and activity. Likewise, oxidative stress can lead to the loss of eNOS activity or even “uncoupling” of the enzyme by adverse regulation of well-defined “redox switches” in eNOS itself or up-/down-stream signaling molecules. Of note, not only eNOS function and activity in the endothelium are essential for vascular integrity and homeostasis, but also eNOS in perivascular adipose tissue plays an important role for these processes. Accordingly, eNOS protein represents an attractive therapeutic target that, so far, was not pharmacologically exploited. With our present work, we want to provide an overview on recent advances and future therapeutic strategies that could be used to target eNOS activity and function in cardiovascular (and other) diseases, including life style changes and epigenetic modulations. We highlight the redox-regulatory mechanisms in eNOS function and up- and down-stream signaling pathways (e.g., tetrahydrobiopterin metabolism and soluble guanylyl cyclase/cGMP pathway) and their potential pharmacological exploitation.

Induction of microRNA-199 by Nitric Oxide in Endothelial Cells Is Required for Nitrovasodilator Resistance via Targeting of Prostaglandin I2 Synthase

Background:

Nitrates are widely used to treat coronary artery disease, but their therapeutic value is compromised by nitrate tolerance, because of the dysfunction of prostaglandin I2 synthase (PTGIS). MicroRNAs repress target gene expression and are recognized as important epigenetic regulators of endothelial function. The aim of this study was to determine whether nitrates induce nitrovasodilator resistance via microRNA-dependent repression of PTGIS gene expression.

Methods:

Nitrovasodilator resistance was induced by nitroglycerin (100 mg·kg –1 ·d –1 , 3 days) infusion in Apoe –/– mice. The responses of aortic arteries to nitric oxide donors were assessed in an organ chamber. The expression levels of microRNA-199 (miR-199)a/b were assayed by quantitative reverse transcription polymerase chain reaction or fluorescent in situ hybridization.

Results:

In cultured human umbilical vein endothelial cells, nitric oxide donors induced miR-199a/b endogenous expression and downregulated PTGIS gene expression, both of which were reversed by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt or silence of serum response factor. Evidence from computational and luciferase reporter gene analyses indicates that the seed sequence of 976 to 982 in the 3′-untranslated region of PTGIS mRNA is a target of miR-199a/b. Gain functions of miR-199a/b resulting from chemical mimics or adenovirus-mediated overexpression increased PTGIS mRNA degradation in HEK293 cells and human umbilical vein endothelial cells. Furthermore, nitroglycerin-decreased PTGIS gene expression was prevented by miR-199a/b antagomirs or was mirrored by the enforced expression of miR-199a/b in human umbilical vein endothelial cells. In Apoe –/– mice, nitroglycerin induced the ectopic expression of miR-199a/b in the carotid arterial endothelium, decreased PTGIS gene expression, and instigated nitrovasodilator resistance, all of which were abrogated by miR-199a/b antagomirs or LNA—anti–miR-199. It is important that the effects of miR-199a/b inhibitions were abolished by adenovirus-mediated PTGIS deficiency. Moreover, the enforced expression of miR-199a/b in vivo repressed PTGIS gene expression and impaired the responses of aortic arteries to nitroglycerin/sodium nitroprusside/acetylcholine/cinaciguat/riociguat, whereas the exogenous expression of the PTGIS gene prevented nitrovasodilator resistance in Apoe –/– mice subjected to nitroglycerin infusion or miR-199a/b overexpression. Finally, indomethacin, iloprost, and SQ29548 improved vasorelaxation in nitroglycerin-infused Apoe –/– mice, whereas U51605 induced nitrovasodilator resistance. In humans, the increased expressions of miR-199a/b were closely associated with nitrate tolerance.

Conclusions:

Nitric oxide–induced ectopic expression of miR-199a/b in endothelial cells is required for nitrovasodilator resistance via the repression of PTGIS gene expression. Clinically, miR-199a/b is a novel target for the treatment of nitrate tolerance.

Treatment of Heart Failure with Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is a growing epidemiologic problem affecting more than half of the patients with heart failure (HF). HFpEF has a significant morbidity and mortality and so far no treatment has been clearly demonstrated to improve the outcomes in HFpEF, in contrast to the efficacy of treatment in heart failure with reduced ejection fraction (HFrEF).The failure of proven beneficial drugs in HFrEF to influence the outcome of patients with HFpEF could be related to the heterogeneity of the disease, its various phenotypes and multifactorial pathophysiology, incompletely elucidated yet. The diagnosis of HFpEF could be demanding or even inaccurate. Moreover, the therapeutic strategies were influenced by different cut-offs used to define preserved ejection fraction (EF). From this perspective, the current guidelines have classified HFpEF by an EF ≥ 50%, together with a distinct entity, heart failure with mid-range ejection fraction (HFmrEF), defined by an EF ranging from 41-49%.New therapies have been developed to interfere with the mediator pathways of HFpEF at the cellular and molecular level, including mineralocorticoid receptor antagonists, soluble guanylate cyclase stimulators, or angiotensin receptor-neprilysin inhibitors. A number of antidiabetic drugs, such as sodium/glucose cotransporter 2 inhibitors and dipeptidyl peptidase-4 inhibitors are promising options, being under research in large clinical trials. Until the results of ongoing trials shed light on these therapies, guidelines recommend empirical treatment for established HFpEF, and emphasize the crucial role of addressing cardiovascular comorbidities leading to HFpEF, in particular arterial hypertension.

The Role of Nitroglycerin and Other Nitrogen Oxides in Cardiovascular Therapeutics

The use of nitroglycerin in the treatment of angina pectoris began not long after its original synthesis in 1847. Since then, the discovery of nitric oxide as a biological effector and better understanding of its roles in vasodilation, cell permeability, platelet function, inflammation, and other vascular processes have advanced our knowledge of the hemodynamic (mostly mediated through vasodilation of capacitance and conductance arteries) and nonhemodynamic effects of organic nitrate therapy, via both nitric oxide-dependent and -independent mechanisms. Nitrates are rapidly absorbed from mucous membranes, the gastrointestinal tract, and the skin; thus, nitroglycerin is available in a number of preparations for delivery via several routes: oral tablets, sublingual tablets, buccal tablets, sublingual spray, transdermal ointment, and transdermal patch, as well as intravenous formulations. Organic nitrates are commonly used in the treatment of cardiovascular disease, but clinical data limit their use mostly to the treatment of angina. They are also used in the treatment of subsets of patients with heart failure and pulmonary hypertension. One major limitation of the use of nitrates is the development of tolerance. Although several agents have been studied for use in the prevention of nitrate tolerance, none are currently recommended owing to a paucity of supportive clinical data. Only 1 method of preventing nitrate tolerance remains widely accepted: the use of a dosing strategy that provides an interval of no or low nitrate exposure during each 24-h period. Nitric oxide's important role in several cardiovascular disease mechanisms continues to drive research toward finding novel ways to affect both endogenous and exogenous sources of this key molecular mediator.

NO and HNO donors, nitrones, and nitroxides: Past, present, and future

The biological effects attributed to nitric oxide (^• NO) and nitroxyl (HNO) have been extensively studied, propelling their array of putative clinical applications beyond cardiovascular disorders toward other age-related diseases, like cancer and neurodegenerative diseases. In this context, the unique properties and reactivity of the N-O bond enabled the development of several classes of compounds with potential clinical interest, among which ^• NO and HNO donors, nitrones, and nitroxides are of particular importance. Although primarily studied for their application as cardioprotective agents and/or molecular probes for radical detection, continuous efforts have unveiled a wide range of pharmacological activities and, ultimately, therapeutic applications. These efforts are of particular significance for diseases in which oxidative stress plays a key pathogenic role, as shown by a growing volume of in vitro and in vivo preclinical data. Although in its early stages, these efforts may provide valuable guidelines for the development of new and effective N-O-based drugs for age-related disorders. In this report, we review recent advances in the chemistry of NO and HNO donors, nitrones, and nitroxides and discuss its pharmacological significance and potential therapeutic application.

European contribution to the study of ROS: A summary of the findings and prospects for the future from the COST action BM1203 (EU-ROS)

The European Cooperation in Science and Technology (COST) provides an ideal framework to establish multi-disciplinary research networks. COST Action BM1203 (EU-ROS) represents a consortium of researchers from different disciplines who are dedicated to providing new insights and tools for better understanding redox biology and medicine and, in the long run, to finding new therapeutic strategies to target dysregulated redox processes in various diseases. This report highlights the major achievements of EU-ROS as well as research updates and new perspectives arising from its members. The EU-ROS consortium comprised more than 140 active members who worked together for four years on the topics briefly described below. The formation of reactive oxygen and nitrogen species (RONS) is an established hallmark of our aerobic environment and metabolism but RONS also act as messengers via redox regulation of essential cellular processes. The fact that many diseases have been found to be associated with oxidative stress established the theory of oxidative stress as a trigger of diseases that can be corrected by antioxidant therapy. However, while experimental studies support this thesis, clinical studies still generate controversial results, due to complex pathophysiology of oxidative stress in humans. For future improvement of antioxidant therapy and better understanding of redox-associated disease progression detailed knowledge on the sources and targets of RONS formation and discrimination of their detrimental or beneficial roles is required. In order to advance this important area of biology and medicine, highly synergistic approaches combining a variety of diverse and contrasting disciplines are needed.

INDIE-HFpEF (Inorganic Nitrite Delivery to Improve Exercise Capacity in Heart Failure With Preserved Ejection Fraction): Rationale and Design

Approximately half of patients with heart failure have preserved ejection fraction. There is no proven treatment that improves outcome. The pathophysiology of heart failure with preserved ejection fraction is complex and includes left ventricular systolic and diastolic dysfunction, pulmonary vascular disease, endothelial dysfunction, and peripheral abnormalities. Multiple lines of evidence point to impaired nitric oxide (NO)-cGMP bioavailability as playing a central role in each of these abnormalities. In contrast to traditional organic nitrate therapies, an alternative strategy to restore NO-cGMP signaling is via inorganic nitrite. Inorganic nitrite, previously considered to be an inert byproduct of NO metabolism, functions as an important in vivo reservoir for NO generation, particularly under hypoxic and acidosis conditions. As such, inorganic nitrite becomes most active at times of greater need for NO signaling, as during exercise when left ventricular filling pressures and pulmonary artery pressures increase. Herein, we present the rationale and design for the INDIE-HFpEF trial (Inorganic Nitrite Delivery to Improve Exercise Capacity in Heart Failure with Preserved Ejection Fraction), which is a multicenter, randomized, double-blind, placebo-controlled cross-over study assessing the effect of inhaled inorganic nitrite on peak exercise capacity, conducted in the National Heart, Lung, and Blood Institute-sponsored Heart Failure Clinical Research Network.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02742129.

Taking up the cudgels for the traditional reactive oxygen and nitrogen species detection assays and their use in the cardiovascular system

Reactive oxygen and nitrogen species (RONS such as H2O2, nitric oxide) confer redox regulation of essential cellular functions (e.g. differentiation, proliferation, migration, apoptosis), initiate and catalyze adaptive stress responses. In contrast, excessive formation of RONS caused by impaired break-down by cellular antioxidant systems and/or insufficient repair of the resulting oxidative damage of biomolecules may lead to appreciable impairment of cellular function and in the worst case to cell death, organ dysfunction and severe disease phenotypes of the entire organism. Therefore, the knowledge of the severity of oxidative stress and tissue specific localization is of great biological and clinical importance. However, at this level of investigation quantitative information may be enough. For the development of specific drugs, the cellular and subcellular localization of the sources of RONS or even the nature of the reactive species may be of great importance, and accordingly, more qualitative information is required. These two different philosophies currently compete with each other and their different needs (also reflected by different detection assays) often lead to controversial discussions within the redox research community. With the present review we want to shed some light on these different philosophies and needs (based on our personal views), but also to defend some of the traditional assays for the detection of RONS that work very well in our hands and to provide some guidelines how to use and interpret the results of these assays. We will also provide an overview on the "new assays" with a brief discussion on their strengths but also weaknesses and limitations.

Pentaerythritol Tetranitrate In Vivo Treatment Improves Oxidative Stress and Vascular Dysfunction by Suppression of Endothelin-1 Signaling in Monocrotaline-Induced Pulmonary Hypertension

Objective. Oxidative stress and endothelial dysfunction contribute to pulmonary arterial hypertension (PAH). The role of the nitrovasodilator pentaerythritol tetranitrate (PETN) on endothelial function and oxidative stress in PAH has not yet been defined. Methods and Results. PAH was induced by monocrotaline (MCT, i.v.) in Wistar rats. Low (30 mg/kg; MCT30), middle (40 mg/kg; MCT40), or high (60 mg/kg; MCT60) dose of MCT for 14, 28, and 42 d was used. MCT induced endothelial dysfunction, pulmonary vascular wall thickening, and fibrosis, as well as protein tyrosine nitration. Pulmonary arterial pressure and heart/body and lung/body weight ratio were increased in MCT40 rats (28 d) and reduced by oral PETN (10 mg/kg, 24 d) therapy. Oxidative stress in the vascular wall, in the heart, and in whole blood as well as vascular endothelin-1 signaling was increased in MCT40-treated rats and normalized by PETN therapy, likely by upregulation of heme oxygenase-1 (HO-1). PETN therapy improved endothelium-dependent relaxation in pulmonary arteries and inhibited endothelin-1-induced oxidative burst in whole blood and the expression of adhesion molecule (ICAM-1) in endothelial cells. Conclusion. MCT-induced PAH impairs endothelial function (aorta and pulmonary arteries) and increases oxidative stress whereas PETN markedly attenuates these adverse effects. Thus, PETN therapy improves pulmonary hypertension beyond its known cardiac preload reducing ability.