Divergent roles of endothelial nitric oxide synthases system in maintaining cardiovascular homeostasis

Antiphospholipid antibody positivity is associated with maturation failure and thrombosis of native arteriovenous fistula: a retrospective study in HD patients

Background and hypothesis

The prevalence of antiphospholipid antibody (aPL) is high among hemodialysis (HD) patients compared to the general population and is inconsistently associated with arteriovenous fistula (AVF) thrombosis or stenosis. The association with maturation failure has never been investigated. This study aims to evaluate native AVF complications (thrombosis, stenosis, and maturation failure) and primary patency in aPL positive HD patients.

Methods

We retrospectively identified 116 HD patients with native AVF. We collected the aPL profiles, the clinical and biological data potentially involved in AVF maturation failure, thrombosis, and stenosis, and investigated the association of these complications and aPL positivity. Kaplan-Meier survival analysis was performed.

Results

In our cohort, the prevalence of aPL persistent positivity was 32.7% and this was strongly associated with AVF maturation failure defined by ultrasound. aPL persistent positivity was a strong predictor in multivariate analysis and this association was independent of AVF stenosis or thrombosis during maturation process. There was no association with primary and functional primary patency, and stenosis. However, aPL persistent positivity according to ACR/EULAR classification criteria was associated with thrombosis when compared to strictly negative aPL patients.

Conclusions

In our cohort, aPL persistent positivity was significantly associated with AVF maturation failure and thrombosis but not with AVF stenosis. To our knowledge, we report for the first time, a statistically significant association between aPL positivity and delay or absence of native AVF maturation.

"NO" controversy?: A controversial role in insulin signaling of diabetic encephalopathy

Insulin, a critical hormone in the human body, exerts its effects by binding to insulin receptors and regulating various cellular processes. While nitric oxide (NO) plays an important role in insulin secretion and acts as a mediator in the signal transduction pathway between upstream molecules and downstream effectors, holds a significant position in the downstream signal network of insulin. Researches have shown that the insulin-NO system exhibits a dual regulatory effect within the central nervous system, which is crucial in the regulation of diabetic encephalopathy (DE). Understanding this system holds immense practical importance in comprehending the targets of existing drugs and the development of potential therapeutic interventions. This review extensively examines the characterization of insulin, NO, Nitric oxide synthase (NOS), specific NO pathway, their interconnections, and the mechanisms underlying their regulatory effects in DE, providing a reference for new therapeutic targets of DE.

Nitric oxide: Potential therapeutic target in Heat Stress-induced Multiple Organ Dysfunction

As climate change intensifies, urgent action is needed to address global warming and its associated health risks, particularly in vulnerable regions. Rising global temperature and increasing frequency of heatwaves present a hidden health risk, disrupting the body's temperature regulation and leading to severe consequences such as heat stress-induced multiple organ dysfunction (HS-MOD). Multiple organ injury triggered by heat stress involves complex molecular pathways such as nitric oxide dysregulation, inflammation, oxidative stress, mitochondrial dysfunction, calcium homeostasis disruption, and autophagy impairment that contribute to cellular damage. Understanding these molecular pathways is crucial for developing targeted therapeutic interventions to alleviate the impact of heat stress (HS). As we explore numerous therapeutic strategies, a remarkable molecule captures our attention: nitric oxide (NO). This colorless gas, mainly produced by nitric oxide synthase (NOS) enzymes, plays crucial roles in various body functions. From promoting vasodilation and neurotransmission to regulating the immune response, platelet function, cell signaling, and reproductive health, NO stands out for its versatility. Exploring it as a promising treatment for heat stress-induced multiple organ injury highlights its distinctive features in the journey towards effective therapeutic interventions. This involves exploring both pharmacological avenues, considering the use of NO donors and antioxidants, and non-pharmacological strategies, such as adopting nitrate-rich diets and engaging in exercise regimens. This review highlights the concept of heat stress, the molecular framework of the disease, and treatment options based upon some new interventions.

Supplementation with l-arginine and nitrates vs age and individual physiological reactivity

Ageing is a natural ontogenetic phenomenon that entails a decrease in the adaptive capacity of the organism, as a result of which the body becomes less adaptable to stressful conditions. Nitrate and nitrite enter the body from exogenous sources and from nitrification of ammonia nitrogen by intestinal microorganisms. This review considers the mechanisms of action of l-arginine, a known inducer of nitric oxide (NO) biosynthesis, and nitrates as supplements in the processes of ageing and aggravated stress states, in which mechanisms of individual physiological reactivity play an important role. This approach can be used as an element of individual therapy or prevention of premature ageing processes depending on the different levels of initial reactivity of the functional systems. A search was performed of the PubMed, Scopus, and Google Scholar databases (n = 181 articles) and the author's own research (n = 4) up to May 5, 2023. The review presents analyses of data on targeted treatment of NO generation by supplementation with l-arginine or nitrates, which is a promising means for prevention of hypoxic conditions frequently accompanying pathological processes in an ageing organism. The review clarifies the role of the individual state of physiological reactivity, using the example of individuals with a high predominance of cholinergic regulatory mechanisms who already have a significant reserve of adaptive capacity. In studies of the predominance of adrenergic influences, a poorly trained organism as well as an elderly organism correspond to low resistance, which is an additional factor of damage at increased energy expenditure.

CONCLUSION

It is suggested that the role of NO synthesis from supplementation of dietary nitrates and nitrites increases with age rather than from oxygen-dependent biosynthetic reactions from l-arginine supplementation.

Metabolic Regulation of Endothelial Cells: A New Era for Treating Wet Age-Related Macular Degeneration

Wet age-related macular degeneration (wet AMD) is a primary contributor to visual impairment and severe vision loss globally, but the prevailing treatments are often unsatisfactory. The development of conventional treatment strategies has largely been based on the understanding that the angiogenic switch of endothelial cells (ECs) is mainly dictated by angiogenic growth factors. Even though treatments targeting vascular endothelial growth factor (VEGF), like ranibizumab, are widely administered, more than half of patients still exhibit inadequate or null responses, suggesting the involvement of other pathogenic mechanisms. With advances in research in recent years, it has become well recognized that EC metabolic regulation plays an active rather than merely passive responsive role in angiogenesis. Disturbances of these metabolic pathways may lead to excessive neovascularization in angiogenic diseases such as wet AMD, therefore targeted modulation of EC metabolism represents a promising therapeutic strategy for wet AMD. In this review, we comprehensively discuss the potential applications of EC metabolic regulation in wet AMD treatment from multiple perspectives, including the involvement of ECs in wet AMD pathogenesis, the major endothelial metabolic pathways, and novel therapeutic approaches targeting metabolism for wet AMD.

Endothelial Function in Pulmonary Arterial Hypertension: From Bench to Bedside

Pulmonary arterial hypertension is a complex pathology whose etiology is still not completely well clarified. The pathogenesis of pulmonary arterial hypertension involves different molecular mechanisms, with endothelial dysfunction playing a central role in disease progression. Both individual genetic predispositions and environmental factors seem to contribute to its onset. To further understand the complex relationship between endothelial and pulmonary hypertension and try to contribute to the development of future therapies, we report a comprehensive and updated review on endothelial function in pulmonary arterial hypertension.

Evaluation of serum nitric oxide synthase levels in patients with coronary slow flow based on corrected TIMI frame count

Introduction

The coronary slow flow phenomenon (CSFP) finding in angiography is characterized by the delayed filling of the terminal vessels without significant epicardial coronary disease. The endothelium performs a vital role in cardiovascular homeostasis by releasing vasoactive substances. Endothelial cells produce nitric oxide (NO) as one of these essential compounds. Three isoforms of nitric oxide synthase (NOS) are endothelial nitric oxide synthase (eNOS), neuronal nitric oxide synthase (nNOS), and induced nitric oxide synthase (iNOS). We aimed to determine the role of NOS in the development of CSFP as the first human study.

Material and methods

A total of 129 patients who met the inclusion criteria were enrolled in the study. The patients were classified into five groups based on the results of coronary angiography: Group 1 without coronary artery disease (CAD) and without CSF, group 2 without CAD and with CSF, group 3 with CAD (< 50%) and without CSF, group 4 with CAD (50-90%) and without CSF, and group 5 with CAD and CSF. The serum level of NOS was determined in the participants. Coronary flow was quantified in patients with CSFP using the corrected TIMI frame count (CTFC) method, and the correlation between the levels of this biomarker and CTFC was investigated.

Results

In this study, the NOS serum levels were not significantly correlated with the mean CTFC. Since the total amount of NOS was measured as a result of 3 isoforms of this enzyme, the lack of correlation could be related to increased iNOS level and decreased eNOS concentration.

Conclusions

These results should be confirmed by more human studies.

Anti-atherosclerotic activity of aqueous extract of Ipomoea batatas (L.) leaves in high-fat diet-induced atherosclerosis model rats

OBJECTIVES

Cardiovascular diseases, especially atherosclerosis, are the leading cause of human mortality in Indonesia. Ipomoea batatas (L.) is a food plant used in Indonesian traditional medicine to treat cardiovascular diseases and related conditions. We assessed the anti-atherosclerotic activity of the aqueous extract of I. batatas leaves in a rat model of high-fat diet-induced atherosclerosis and its mechanism.

METHODS

The presence of amino acid content in the I. batatas L. purple variant was determined by liquid chromatography high-resolution mass spectrometry (LC-HRMS). Thirty male Wistar rats were divided into five groups (n=6/group), i.e., standard diet group (SD), high-fat diet group (HF), and HF plus I. batatas L. extracts orally (625; 1,250; or 2,500 mg/kg) groups. The numbers of macrophages and aortic wall thickness were analyzed histologically. Immunohistochemical analyses were performed to assess foam cells-oxidized low-density lipoprotein (oxLDL), endothelial nitric oxide synthase (eNOS), and vascular endothelial growth factor (VEGF) expression in the aorta.

RESULTS

LC-HRMS analysis showed nine amino acid content were identified from I. batatas L. In vivo study revealed that oral administration of I. batatas L. leaf extract alleviated foam cells-oxLDL formation and aortic wall thickness caused by high-fat diet atherosclerosis rats. Further, I. batatas L. leaf extract promoted the number of macrophages and modulated VEGF and eNOS expression in the aorta.

CONCLUSIONS

I. batatas L. leaf extract shows a positive anti-atherosclerosis effect. Furthermore, the mechanism may promote the macrophages, eNOS, VEGF expressions, and inhibition of foam cells-oxLDL formation and aortic wall thickness with the best dosage at 2,500 mg/kg. This could represent a novel approach to prevent cardiovascular diseases.

Targeting oxidative stress as a preventive and therapeutic approach for cardiovascular disease

Cardiovascular diseases (CVDs) continue to exert a significant impact on global mortality rates, encompassing conditions like pulmonary arterial hypertension (PAH), atherosclerosis (AS), and myocardial infarction (MI). Oxidative stress (OS) plays a crucial role in the pathogenesis and advancement of CVDs, highlighting its significance as a contributing factor. Maintaining an equilibrium between reactive oxygen species (ROS) and antioxidant systems not only aids in mitigating oxidative stress but also confers protective benefits on cardiac health. Herbal monomers can inhibit OS in CVDs by activating multiple signaling pathways, such as increasing the activity of endogenous antioxidant systems and decreasing the level of ROS expression. Given the actions of herbal monomers to significantly protect the normal function of the heart and reduce the damage caused by OS to the organism. Hence, it is imperative to recognize the significance of herbal monomers as prospective therapeutic interventions for mitigating oxidative damage in CVDs. This paper aims to comprehensively review the origins and mechanisms underlying OS, elucidate the intricate association between CVDs and OS, and explore the therapeutic potential of antioxidant treatment utilizing herbal monomers. Furthermore, particular emphasis will be placed on examining the cardioprotective effects of herbal monomers by evaluating their impact on cardiac signaling pathways subsequent to treatment.

Regular Exercise Rescues Heart Function Defects and Shortens the Lifespan of Drosophila Caused by dMnM Downregulation

Although studies have shown that myomesin 2 (MYOM2) mutations can lead to hypertrophic cardiomyopathy (HCM), a common cardiovascular disease that has a serious impact on human life, the effect of MYOM2 on cardiac function and lifespan in humans is unknown. In this study, dMnM (MYOM2 homologs) knockdown in cardiomyocytes resulted in diastolic cardiac defects (diastolic dysfunction and arrhythmias) and increased cardiac oxidative stress. Furthermore, the knockdown of dMnM in indirect flight muscle (IFM) reduced climbing ability and shortened lifespan. However, regular exercise significantly ameliorated diastolic cardiac dysfunction, arrhythmias, and oxidative stress triggered by dMnM knockdown in cardiac myocytes and also reversed the reduction in climbing ability and shortening of lifespan caused by dMnM knockdown in Drosophila IFM. In conclusion, these results suggest that Drosophila cardiomyocyte dMnM knockdown leads to cardiac functional defects, while dMnM knockdown in IFM affects climbing ability and lifespan. Furthermore, regular exercise effectively upregulates cardiomyocyte dMnM expression levels and ameliorates cardiac functional defects caused by Drosophila cardiomyocyte dMnM knockdown by increasing cardiac antioxidant capacity. Importantly, regular exercise ameliorates the shortened lifespan caused by dMnM knockdown in IFM.

Pro-Healing Nanomatrix-Coated Stent Analysis in an In Vitro Vascular Double-Layer System and in a Rabbit Model

Cardiovascular stent technologies have significantly improved over time. However, their optimal performance remains limited by restenosis, thrombosis, inflammation, and delayed re-endothelialization. Current stent designs primarily target inhibition of neointimal proliferation but do not promote functional arterial healing (pro-healing) in order to restore normal vascular reactivity. The endothelial lining that does develop with current stents appears to have loose intracellular junctions. We have developed a pro-healing nanomatrix coating for stents that enhances healing while limiting neointimal proliferation. This builds on our prior work evaluating the effects of the pro-healing nanomatrix coating on cultures of vascular endothelial cells (ECs), smooth muscle cells (SMCs), monocytes, and platelets. However, when a stent is deployed in an artery, multiple vascular cell types interact, and their interactions affect stent performance. Thus, in our current study, an in vitro vascular double-layer (VDL) system was used to observe stent effects on communication between different vascular cell types. Additionally, we assessed the pro-healing ability and vascular cell interactions after stent deployment in the VDL system and in a rabbit model, evaluating the nanomatrix-coated stent compared to a commercial bare metal stent (BMS) and a drug eluting stent (DES). In vitro results indicated that, in a layered vascular structure, the pro-healing nanomatrix-coated stent could (1) improve endothelialization and endothelial functions, (2) regulate SMC phenotype to reduce SMC proliferation and migration, (3) suppress inflammation through a multifactorial manner, and (4) reduce foam cell formation, extracellular matrix remodeling, and calcification. Consistent with this, in vivo results demonstrated that, compared with commercial BMS and DES, this pro-healing nanomatrix-coated stent enhanced re-endothelialization with negligible restenosis, inflammation, or thrombosis. Thus, these findings indicate the unique pro-healing features of this nanomatrix stent coating with superior efficacy over commercial BMS and DES.

Endothelium-Derived Relaxing Factors and Endothelial Function: A Systematic Review

BACKGROUND

The endothelium plays a pivotal role in homeostatic mechanisms. It specifically modulates vascular tone by releasing vasodilatory mediators, which act on the vascular smooth muscle. Large amounts of work have been dedicated towards identifying mediators of vasodilation and vasoconstriction alongside the deleterious effects of reactive oxygen species on the endothelium. We conducted a systematic review to study the role of the factors released by the endothelium and the effects on the vessels alongside its role in atherosclerosis.

METHODS

A search was conducted with appropriate search terms. Specific attention was offered to the effects of emerging modulators of endothelial functions focusing the analysis on studies that investigated the role of reactive oxygen species (ROS), perivascular adipose tissue, shear stress, AMP-activated protein kinase, potassium channels, bone morphogenic protein 4, and P2Y2 receptor.

RESULTS

530 citations were reviewed, with 35 studies included in the final systematic review. The endpoints were evaluated in these studies which offered an extensive discussion on emerging modulators of endothelial functions. Specific factors such as reactive oxygen species had deleterious effects, especially in the obese and elderly. Another important finding included the shear stress-induced endothelial nitric oxide (NO), which may delay development of atherosclerosis. Perivascular Adipose Tissue (PVAT) also contributes to reparative measures against atherosclerosis, although this may turn pathological in obese subjects. Some of these factors may be targets for pharmaceutical agents in the near future.

CONCLUSION

The complex role and function of the endothelium is vital for regular homeostasis. Dysregulation may drive atherogenesis; thus, efforts should be placed at considering therapeutic options by targeting some of the factors noted.

Opportunities for Nitric Oxide in Potentiating Cancer Immunotherapy

Despite nearly 30 years of development and recent highlights of nitric oxide (NO) donors and NO delivery systems in anticancer therapy, the limited understanding of exogenous NO's effects on the immune system has prevented their advancement into clinical use. In particular, the effects of exogenously delivered NO differing from that of endogenous NO has obscured how the potential and functions of NO in anticancer therapy may be estimated and exploited despite the accumulating evidence of NO's cancer therapy-potentiating effects on the immune system. After introducing their fundamentals and characteristics, this review discusses the current mechanistic understanding of NO donors and delivery systems in modulating the immunogenicity of cancer cells as well as the differentiation and functions of innate and adaptive immune cells. Lastly, the potential for the complex modulatory effects of NO with the immune system to be leveraged for therapeutic applications is discussed in the context of recent advancements in the implementation of NO delivery systems for anticancer immunotherapy applications. SIGNIFICANCE STATEMENT: Despite a 30-year history and recent highlights of nitric oxide (NO) donors and delivery systems as anticancer therapeutics, their clinical translation has been limited. Increasing evidence of the complex interactions between NO and the immune system has revealed both the potential and hurdles in their clinical translation. This review summarizes the effects of exogenous NO on cancer and immune cells in vitro and elaborates these effects in the context of recent reports exploiting NO delivery systems in vivo in cancer therapy applications.

Sodium Ferulate Inhibits Rat Cardiomyocyte Hypertrophy Induced by Angiotensin II Through Enhancement of Endothelial Nitric Oxide Synthase/Nitric Oxide/Cyclic Guanosine Monophosphate Signaling Pathway

ABSTRACT

Sodium ferulate (SF) is the sodium salt of ferulic acid, which is one of the effective components of Angelica sinensis and Lignsticum chuanxiong , and plays an important role in protecting the cardiovascular system. In this study, myocardial hypertrophy was induced by angiotensin II 0.1 μmol/L in neonatal Sprague-Dawley rat ventricular myocytes. Nine groups were designed, that is, normal, normal administration, model, L-arginine (L-arg 1000 μmol/L), SF (50, 100, 200 μmol/L) group, and N G -nitro-L-arg-methyl ester 1500 μmol/L combined with SF 200 μmol/L or L-arg 1000 μmol/L group, respectively. Cardiomyocyte hypertrophy was confirmed by observing histological changes and measurements of cell diameter, protein content and atrial natriuretic factor, and β-myosin heavy chain levels of the cells. Notably, SF could inhibit significantly myocardial hypertrophy of neonatal rat cardiomyocytes in a concentration-dependent manner without producing cytotoxicity, and the levels of nitric oxide, NO synthase (NOS), endothelial NOS, and cyclic guanosine monophosphate were increased, but the level of cyclic adenosine monophosphate was decreased in cardiomyocytes. Simultaneously, levels of protein kinase C beta, Raf-1, and extracellular regulated protein kinase 1/2 (ERK1/2) were downregulated, whereas levels of mitogen-activated protein kinase phosphatase-1 were significantly upregulated. All the beneficial effects of SF were blunted by N G -nitro-L-arg-methyl ester. Overall, these findings reveal that SF can inhibit angiotensin II-induced myocardial hypertrophy of neonatal rat cardiomyocytes, which is closely related to activation of endothelial NOS/NO/cyclic guanosine monophosphate, and inhibition of protein kinase C and mitogen-activated protein kinase signaling pathways.

Computational Models on Pathological Redox Signalling Driven by Pregnancy: A Review

Oxidative stress is associated with a myriad of diseases including pregnancy pathologies with long-term cardiovascular repercussions for both the mother and baby. Aberrant redox signalling coupled with deficient antioxidant defence leads to chronic molecular impairment. Abnormal placentation has been considered the primary source for reactive species; however, placental dysfunction has been deemed secondary to maternal cardiovascular maladaptation in pregnancy. While various therapeutic interventions, aimed at combating deregulated oxidative stress during pregnancy have shown promise in experimental models, they often result as inconclusive or detrimental in clinical trials, warranting the need for further research to identify candidates. The strengths and limitations of current experimental methods in redox research are discussed. Assessment of redox status and oxidative stress in experimental models and in clinical practice remains challenging; the state-of-the-art of computational models in this field is presented in this review, comparing static and dynamic models which provide functional information such as protein-protein interactions, as well as the impact of changes in molecular species on the redox-status of the system, respectively. Enhanced knowledge of redox biology in during pregnancy through computational modelling such as generation of Systems Biology Markup Language model which integrates existing models to a larger network in the context of placenta physiology.

Hypertension and COVID-19: Current Evidence and Perspectives

Coronavirus disease 2019 (COVID-19) outbreak, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), represents a real challenge for health-care systems worldwide. Male sex, older age and the coexistence of chronic comorbidities have been described as the most relevant conditions associated with a worse prognosis. Early reports suggested that hypertension might represent a risk factor for susceptibility to SARS-CoV-2 infection, a more severe course of COVID-19 and increased COVID-19-related deaths. Nevertheless, the independent role of hypertension remains under debate, since hypertension is often associated with the older age and other cardiovascular (CV) risk factors in the general population, which may also contribute to the SARS-Cov-2 infection and COVID-19. Moreover, the role of antihypertensive drugs, primarily angiotensin-converting inhibitors (ACEIs) and ARBs (angiotensin receptor blockers) in COVID-19 development and outcome appears controversial. Indeed, preclinical studies using these classes of drugs have suggested a potential upregulation of angiotensin-converting-enzyme 2 (ACE2) which is the key binding receptor promoting cell entry of SARS-CoV-2 in the organism. Renin–angiotensin system (RAS) blockers may potentially upregulate ACE2, hence, it has been initially hypothesized that these agents might contribute to a higher risk of SARS-CoV-2 infection and progressive course of COVID-19. However, several clinical reports do not support a detrimental role of RAS blockers in COVID-19, and an intense debate about the withdrawal or maintenance of chronic therapy with ACEi/ARB has been developed. In this review we will discuss the available evidence on the role of hypertension and antihypertensive drugs on SARS-CoV-2 infection and COVID-19 development.

Endothelial Dysfunction in Hypertension: Current Concepts and Clinical Implications

Endothelium plays a fundamental role in the cardiovascular system, forming an interface between blood and adjacent tissues by regulating the vascular tone through the synthesis of nitric oxide, prostaglandins and other relaxing factors. Endothelial dysfunction is characterized by vasoconstriction, cell proliferation and shifting toward a proinflammatory and prothrombic state. In hypertension endothelial dysfunction may be involved in the initiation and development of vascular inflammation, vascular remodeling, and atherosclerosis and is independently associated with increased cardiovascular risk. Different conditions such as impaired vascular shear stress, inflammation and oxidative stress, activation of the renin angiotensin system have been described as important pathophysiological mechanisms involved in the development of endothelial dysfunction. The release of extracellular vesicles by neighboring cells in the vascular wall has emerged as an important regulator of endothelial function and with potential antihypertensive properties and beneficial effects by counteracting the hypertension mediated organ damage. Furthermore, macrovesicles are emerging as an innovative therapeutic approach for vascular protection, allowing the delivery of bioactive molecules, such as miRNA and drugs interacting with the renin angiotensin system. In this review we summarize the available evidence about the pathophysiological implications of endothelial dysfunction in cardiovascular diseases, focusing on hypertension and its sequelae, and the potential innovative therapeutic strategies targeting the endothelium with the aim to improve vascular function and remodeling.

Vascular region-specific changes in arterial tone in rats with type 2 diabetes mellitus: Opposite responses of mesenteric and femoral arteries to acetylcholine and 5-hydroxytryptamine

AIMS

Type 2 diabetes mellitus (T2DM) ranks in the top 10 causes of mortality worldwide. The key factor of T2DM vascular complications is endothelial dysfunction. It is characterized by the vessels motor activity disruption and endothelium-derived factors imbalance. The blood vessels morphological and molecular heterogeneity greatly affects the changes occurring in T2DM. Therefore, we conducted a comparative study of vascular bed changes occurring in T2DM.

MAIN METHODS

Male Wistar rats were fed a high-fat diet for 20 weeks, followed by a single streptozotocin injection (20 mg/kg). T2DM was confirmed with an oral glucose tolerance test.

KEY FINDINGS

A dose-dependent contraction study showed an increase in third-order mesenteric arterioles response to serotonin but not to phenylephrine. These vessels also exhibited a decrease in acetylcholine-dependent relaxation and an increase in guanylate cyclase function. At the same time, the femoral arteries showed a tendency for increased acetylcholine-dependent relaxation. The blood plasma analysis revealed low bioavailable nitric oxide and high levels of endothelin-1 and ROS.

SIGNIFICANCE

This knowledge, in conjunction with the features of the T2DM course, can allow further targeted approaches development for the prevention and treatment of vascular complications occurring in the disease.

Anethum graveolens L. (Dill) effect on human lipid profile: An updated systematic Review

Dill is an aromatic edible herb, belongs to the genus Anethum in the celery family (Apiaceae or Umbelliferae) with a long history of cultivation from ancient times and two closely related cultivated species, European dill (Anethum graveolens) and Indian dill (Anethum Sowa). We wanted to do this systematic review on the effect of Anethum graveolens intake on lipid profile because the outcomes of multiple research and meta-analyses in this regard were inconsistent. A systematic search for English published randomized controlled trials (RCTs) covering PubMed, EMBASE, Scopus, and Coherence library. The pooled weighted mean difference (MD) and its 95% confidence interval (CI) were calculated and pooled using a random-effects model. Pooled data of six RCTs involving 171 intervention cases indicated that dill supplementation was associated with a significant reduction in mean serum total cholesterol (MD 95% CI= -3.71(-5.71,-1.70); p < 0.001), low-density lipoprotein cholesterol (LDL-C) (MD 95% CI= -1.51(-2.65,-0.47); p = 0.005), triglycerides (MD 95% CI= -2.48(-3.98,-0.98); p = 0.001) and interestingly high-density lipoprotein cholesterol level (HDL-C) (MD 95% CI= -2.19(-3.58,-0.81); p = 0.002). Subgroup analysis showed that dill use was more effective in lowering triglyceride in both hyperlipidemic patients, MD 95% CI= -3.54(-6.49,-0.60); p = 0.02) and type 2 diabetes (MD 95% CI= -3.64(-5.69,-1.58); p = 0.001). Dill use reduced the LDL levels more effectively in patients with type 2 diabetes (MD 95% CI= -3.54(-6.49,-0.60); p = 0.03). Dill supplementation significantly improved LDL-C, TG, and TC levels but not HDL-C. Further high quality controlled clinical trials on human is needed for more accurate and confirm conclusion.

AMPK, metabolism, and vascular function

Adenosine monophosphate-activated protein kinase (AMPK) is a cellular energy sensor activated during energy stress that plays a key role in maintaining energy homeostasis. This ubiquitous signaling pathway has been implicated in multiple functions including mitochondrial biogenesis, redox regulation, cell growth and proliferation, cell autophagy and inflammation. The protective role of AMPK in cardiovascular function and the involvement of dysfunctional AMPK in the pathogenesis of cardiovascular disease have been highlighted in recent years. In this review, we summarize and discuss the role of AMPK in the regulation of blood flow in response to metabolic demand and the basis of the AMPK physiological anticontractile, antioxidant, anti-inflammatory, and antiatherogenic actions in the vascular system. Investigations by others and us have demonstrated the key role of vascular AMPK in the regulation of endothelial function, redox homeostasis, and inflammation, in addition to its protective role in the hypoxia and ischemia/reperfusion injury. The pathophysiological implications of AMPK involvement in vascular function with regard to the vascular complications of metabolic disease and the therapeutic potential of AMPK activators are also discussed.

Bee Bread Ameliorates Vascular Inflammation and Impaired Vasorelaxation in Obesity-Induced Vascular Damage Rat Model: The Role of eNOS/NO/cGMP-Signaling Pathway

Obesity and hyperlipidemia are major risk factors for developing vascular diseases. Bee bread (BB) has been reported to exhibit some biological actions, including anti-obesity and anti-hyperlipidemic. This study aims to investigate whether bee bread can ameliorate vascular inflammation and impaired vasorelaxation activity through eNOS/NO/cGMP pathway in obese rats. Forty male Sprague-Dawley rats were randomly divided into four groups (n = 10/group), namely: control (normal group), obese rats (OB group), obese rats treated with bee bread (0.5 g/kg/day, OB/BB group) and obese rats treated with orlistat (10 mg/kg/day, OB/OR group). The latter three groups were given a high-fat diet (HFD) for 6 weeks to induced obesity before being administered with their respective treatments for another 6 weeks. After 12 weeks of the total experimental period, rats in the OB group demonstrated significantly higher Lee obesity index, lipid profile (total cholesterol, triglyceride, low-density lipoprotein), aortic proinflammatory markers (tumor necrosis factor-α, nuclear factor-κβ), aortic structural damage and impairment in vasorelaxation response to acetylcholine (ACh). Bee bread significantly ameliorated the obesity-induced vascular damage manifested by improvements in the lipid profile, aortic inflammatory markers, and the impaired vasorelaxation activity by significantly enhancing nitric oxide release, promoting endothelial nitric oxide synthase (eNOS) and cyclic guanosine monophosphate (cGMP) immunoexpression. These findings suggest that the administration of bee bread ameliorates the impaired vasorelaxation response to ACh by improving eNOS/NO/cGMP-signaling pathway in obese rats, suggesting its vascular therapeutic role.

Why Is COVID-19 More Severe in Patients With Diabetes? The Role of Angiotensin-Converting Enzyme 2, Endothelial Dysfunction and the Immunoinflammatory System

Meta-analyses have indicated that individuals with type 1 or type 2 diabetes are at increased risk of suffering a severe form of COVID-19 and have a higher mortality rate than the non-diabetic population. Patients with diabetes have chronic, low-level systemic inflammation, which results in global cellular dysfunction underlying the wide variety of symptoms associated with the disease, including an increased risk of respiratory infection. While the increased severity of COVID-19 amongst patients with diabetes is not yet fully understood, the common features associated with both diseases are dysregulated immune and inflammatory responses. An additional key player in COVID-19 is the enzyme, angiotensin-converting enzyme 2 (ACE2), which is essential for adhesion and uptake of virus into cells prior to replication. Changes to the expression of ACE2 in diabetes have been documented, but they vary across different organs and the importance of such changes on COVID-19 severity are still under investigation. This review will examine and summarise existing data on how immune and inflammatory processes interplay with the pathogenesis of COVID-19, with a particular focus on the impacts that diabetes, endothelial dysfunction and the expression dynamics of ACE2 have on the disease severity.

Molecular dynamics study of in silico mutations in the auto-inhibitory loop of human endothelial nitric oxide synthase FMN sub-domain

Structural flexibility of the peptide linker connecting two domains is essential for the functioning of multi-domain complex. Nitric oxide synthase (NOS) isoforms contain the oxygenase and the reductase domains connected by calmodulin binding linker (CBL) region. Additionally, the endothelial NOS (eNOS) isoform contain an auto-inhibitory loop (AI) in the FMN reductase sub-domain which represses the inter-domain electron transfer process. Binding of Ca²⁺-Calmodulin complex on the CBL region relieves the AI loop repression and facilitates electron transfer from FMN in the reductase domain to the heme in the oxygenase domain. Few experimental studies have reported that in vitro mutation of Serine-615 (S615D) and Serine-633 (S633D) in the FMN reductase sub-domain to aspartic acid increased NO production and increased Ca²⁺ sensitivity. To understand the role of AI loop in eNOS repression and activation in serine mutants (S615D and S633D), we modelled the FMN reductase sub-domain of human eNOS protein with and without the CBL region. Molecular dynamics simulations performed indicated that the mutant protein AI loop structure was stabilized by salt bridge formed between D615 and R602. It was also found that mutation increased the flexibility of C-terminal residues of eNOS CBL region. The hinge-like movement of the AI loop allowed rotation of the FMN sub-domain clockwise which may favour electron-transfer in the mutant protein. This study provides insight on mutation (S615D and S633D) induced changes in AI loop and increased flexibility of CBL region which may lead to the protein activation and may also facilitate Calmodulin binding at physiological Ca²⁺ concentration. Graphical Abstract Mutation of amino acid residues contribute to structural changes at molecular level leading to alteration in protein dynamics and its function. Serine-615 and Serine-633 in the auto-inhibitory loop of human eNOS reductase model was mutated to aspartic acid in silico and molecular dynamics simulations of the protein showed that steric hindrance due to mutation altered the auto-inhibitory loop rearrangement and the FMN sub-domain movement favouring electron transfer.

Protective Effect of Epigallocatechin Gallate on Endothelial Disorders in Atherosclerosis

Healthy vascular endothelial cells regulate vascular tone and permeability, prevent vessel wall inflammation, enhance thromboresistance, and contribute to general vascular health. Furthermore, they perform important functions including the production of vasoactive substances such as nitric oxide (NO) and endothelium-derived hyperpolarizing factors, as well as the regulation of smooth muscle cell functions. Conversely, vascular endothelial dysfunction leads to atherosclerosis, thereby enhancing the risk of stroke, myocardial infarction, and other cardiovascular diseases (CVDs). Observational studies and randomized trials showed that green tea intake was inversely related to CVD risk. Furthermore, evidence indicates that epigallocatechin gallate (EGCG) found in green tea might exert a preventive effect against CVDs. EGCG acts as an antioxidant, inducing NO release and reducing endothelin-1 production in endothelial cells. EGCG enhances the bioavailability of normal NO by reducing levels of the endogenous NO inhibitor asymmetric dimethylarginine. Furthermore, it inhibits the enhanced expression of adhesion molecules such as vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 and attenuates monocyte adhesion. In addition, EGCG prevents enhanced oxidative stress through the Nrf2/HO-1 pathway. These effects indicate that it might prevent the production of reactive oxygen species, inhibit inflammation, and reduce endothelial cell apoptosis during the initial stages of atherosclerosis. The current review summarizes recent research in this area and discusses novel findings regarding the protective effect of EGCG on endothelial dysfunction and CVDs in general.

Nobiletin Regulates ROS/ADMA/DDAHII/eNOS/NO Pathway and Alleviates Vascular Endothelium Injury by Iron Overload

Iron overload is harmful to health and associates with intracellular excessive reactive oxygen species (ROS) generation. Nobiletin (Nob) is known to be antioxidant and anti-inflammatory. However, whether Nob can protect endothelial cells against iron overload has not been studied, and the specific mechanism has not yet been elucidated. In this study, we have identified the protective effects of Nob, and its underlying molecular mechanism in human umbilical vein endothelial cells (HUVECs) suffered from iron overload via ROS/ADMA/DDAHII/eNOS/NO pathway. We found that compared with 50 μM iron dextran treatment, co-treatment with 20 μM Nob increased cell viability and decreased lactate dehydrogenase activity. Besides, Nob could upregulate DDAHII expression and activity, promote eNOS phosphorylation to produce more NO, reduce ADMA content, and therefore increase superoxide dismutase, catalase, and glutathione peroxidase activities, and decrease malondialdehyde level and ROS generation. Nob also inhibited mitochondrial permeability transition pore (mPTP) openness and cleaved caspase-3 expression, and decreased apoptosis induced by iron overload. These results were consistent when Nob was replaced by the positive control reagents L-arginine (a competitive substrate of ADMA), cyclosporin A (an mPTP closing agent), or edaravone (a free radical scavenger). The addition of pAD/DDAHII-shRNA adenovirus reversed the above effects of Nob. These data suggested that the protective mechanism of Nob was to inhibit ROS burst, upregulate DDAHII expression and activity, promote eNOS phosphorylation, produce NO, reduce ADMA content, and ultimately alleviate iron overload damage in vascular endothelium.

Evaluation of the Correlation between Serum Concentrations of Asymmetric Dimethylarginine and Corrected TIMI Frame Count in Patients with Slow Coronary Flow

Coronary slow flow (CSF) is an important angiographic entity that is characterized by delayed opacification of coronary arteries in the absence of epicardial occlusive disease. Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide synthase. Elevated levels of ADMA cause the induction of endothelial dysfunction and thus promote atherosclerosis. This study was aimed at determining the role of ADMA in the development of CSF. One hundred twenty-nine subjects who fulfilled the inclusion criteria were enrolled in this study. According to coronary angiography results, these subjects were divided into five groups. The serum concentration of ADMA was measured in these subjects. In this study, there was no significant correlation between serum concentrations of ADMA and mean corrected TIMI frame count (CTFC) (P > 0.05). However, the ADMA level was significantly correlated with CTFC in the left anterior descending (LAD) coronary artery in patients with CSF (r = −0.381, P = 0.045). Also, plasma ADMA levels were significantly higher in patients with CSF and without CAD compared to patients without CSF and with CAD (50-90%) (P = 0.034). Besides, serum concentrations of ADMA were significantly higher in subjects with BMI < 25 kg/m² compared with those having BMI > 30 kg/m² (P = 0.003). It was also shown that the levels of ADMA were significantly higher in subjects with age as a cardiovascular risk factor compared with those without this risk factor (P = 0.024). Further studies with larger population sizes are needed to confirm the present findings on the association between the serum concentrations of ADMA and CSF.

NOX4 is a major regulator of cord blood-derived endothelial colony-forming cells which promotes post-ischaemic revascularization

AIMS

Cord blood-derived endothelial colony-forming cells (CB-ECFCs) are a defined progenitor population with established roles in vascular homeostasis and angiogenesis, which possess low immunogenicity and high potential for allogeneic therapy and are highly sensitive to regulation by reactive oxygen species (ROS). The aim of this study was to define the precise role of the major ROS-producing enzyme, NOX4 NADPH oxidase, in CB-ECFC vasoreparative function.

METHODS AND RESULTS

In vitro CB-ECFC migration (scratch-wound assay) and tubulogenesis (tube length, branch number) was enhanced by phorbol 12-myristate 13-acetate (PMA)-induced superoxide in a NOX-dependent manner. CB-ECFCs highly-expressed NOX4, which was further induced by PMA, whilst NOX4 siRNA and plasmid overexpression reduced and potentiated in vitro function, respectively. Increased ROS generation in NOX4-overexpressing CB-ECFCs (DCF fluorescence, flow cytometry) was specifically reduced by superoxide dismutase, highlighting induction of ROS-specific signalling. Laser Doppler imaging of mouse ischaemic hindlimbs at 7 days indicated that NOX4-knockdown CB-ECFCs inhibited blood flow recovery, which was enhanced by NOX4-overexpressing CB-ECFCs. Tissue analysis at 14 days revealed consistent alterations in vascular density (lectin expression) and eNOS protein despite clearance of injected CB-ECFCs, suggesting NOX4-mediated modulation of host tissue. Indeed, proteome array analysis indicated that NOX4-knockdown CB-ECFCs largely suppressed tissue angiogenesis, whilst NOX4-overexpressing CB-ECFCs up-regulated a number of pro-angiogenic factors specifically-linked with eNOS signalling, in parallel with equivalent modulation of NOX-dependent ROS generation, suggesting that CB-ECFC NOX4 signalling may promote host vascular repair.

CONCLUSION

Taken together, these findings indicate a key role for NOX4 in CB-ECFCs, thereby highlighting its potential as a target for enhancing their reparative function through therapeutic priming to support creation of a pro-reparative microenvironment and effective post-ischaemic revascularization.

Antiphospholipid antibodies in end-stage renal disease: A systematic review and meta-analysis

INTRODUCTION

The relationship between autoimmune hemolytic anemia and antiphospholipid antibodies (aPL) and/or antiphospholipid syndrome has never been systematically addressed.

METHODS

Systematic review of EMBASE and PubMed databases performed according to PRISMA guidelines from inception to March 2020; meta-analysis performed by Peto's odds ratio for rare events.

FINDINGS

Forty-five studies with different outcomes met the inclusion/exclusion criteria. The pooled prevalence (PP) of IgG anticardiolipin antibodies (aCL) positivity was greater in end-stage renal disease (ESRD) than controls (20.2% vs. 2.6%, P = 0.001, I²  >80%; I² = heterogeneity), particularly in hemodialysis patients (18.3% vs. 8%, I² = 0%). The PP of lupus anticoagulant was greater in ESRD than controls (8.7% vs. 0.2%, P < 0.0001, I² = 0%). The standardized mean difference of IgG aCL favored ESRD rather than controls (P < 0.0001, I² =97%). The PP of fistula occlusion was greater in IgG aCL-positive patients than negative patients (39% vs. 27%, I² =97%); the PP of IgG aCL positivity was greater in patients with fistula occlusion than without fistula occlusion (26.9% vs. 23.2%, P = 0.01, I² =72%); the same applied to the PP of lupus anticoagulant positivity (23% vs. 0.3%, P < 0.0001, I² = 0%). The standardized mean difference of IgG aCL favored fistula occlusion (P = 0.004, I² = 91%).

DISCUSSION

Lupus anticoagulant relates to ESRD regardless of management whereas IgG aCL relates specifically to ESRD on hemodialysis, but only lupus anticoagulant associates with fistula occlusion. The expression of aPL as patients positive for aPL rather than as titers precludes further assumptions on the relationship.

Differences in metabolic profiles between bicuspid and tricuspid aortic stenosis in the setting of transcatheter aortic valve replacement

Background

To explore why bicuspid aortic stenosis has certain clinical differences from the tricuspid morphology, we evaluated the metabolomics profile involved in bicuspid aortic valve (BAV) aortic stenosis prior to and after transcatheter aortic valve replacement (TAVR) in comparison with tricuspid aortic valve (TAV).

Methods

In this TAVR cohort with prospectively collected data, blood samples were obtained before TAVR valve deployment and at the 7th day after TAVR, which were then sent for liquid and gas chromatography-mass spectrometry detection. Besides comparisons between BAV and TAV, BAV patients were also divided in subgroups according to baseline hemodynamics (i.e. maximal transaortic velocity, V_max) and post-procedural reverse left ventricular (LV) remodeling (i.e. the change in LV mass index from baseline, ∆LVMI) for further analysis. Metabolic differences between groups were identified by integrating univariate test, multivariate analysis and weighted correlation network analysis algorithm.

Results

A total of 57 patients were enrolled including 33 BAV patients. The BAV group showed lower arginine and proline metabolism both before and post TAVR than TAV represented by decreased expression of L-Glutamine. In BAV subgroup analysis, patients with baseline V_max > 5 m/s (n = 11) or the 4^th quartile of change in ∆LVMI at one-year follow-up (i.e. poorly-recovered LV, n = 8) showed elevated arachidonic acid metabolism compared with V_max < 4.5 m/s (n = 12) or the 1^st quartile of ∆LVMI (i.e. well-recovered LV, n = 8) respectively.

Conclusions

Difference in arginine and proline metabolism was identified between BAV and TAV in TAVR recipients. Elevated arachidonic acid metabolism may reflect more severe baseline hemodynamics and worse LV reserve remodeling after TAVR in BAV.

Low shear stress induces endothelial cell apoptosis and monocyte adhesion by upregulating PECAM‑1 expression

Low shear stress serves an important role in the initiation and progression of atherosclerotic lesions, with an impact on progression, but its detailed mechanisms are .not yet fully known. The present study aimed to investigate endothelial cell (EC) apoptosis, as well as monocyte adhesion induced by low shear stress and the potential underlying mechanisms. The expression of platelet endothelial cell adhesion molecule-1 (PECAM-1) was demonstrated to be enhanced in human umbilical vascular ECs with a trend that was associated with time when stimulated by low shear stress compared with unstimulated cells. EC apoptosis was increased under low shear stress compared with unstimulated cells, and knockdown of PECAM-1 inhibited this process. Furthermore, downregulation of PECAM-1 reduced monocyte adhesion induced by low shear stress compared with that in the negative control cells. Mechanistically, PECAM-1 small interfering RNA transfection increased Akt and forkhead box O1 phosphorylation under low shear stress conditions compared with that in the negative control cells. Collectively, the findings of the present study revealed that low shear stress induced EC apoptosis and monocyte adhesion by upregulating PECAM-1 expression, which suggested that PECAM-1 may be a potential therapeutic target for atherosclerosis.

Reactive oxygen species in cardiovascular health and disease: special references to nitric oxide, hydrogen peroxide, and Rho-kinase

The interaction between endothelial cells and vascular smooth muscle cells (VSMC) plays an important role in regulating cardiovascular homeostasis. Endothelial cells synthesize and release endothelium-derived relaxing factors (EDRFs), including vasodilator prostaglandins, nitric oxide (NO), and endothelium-dependent hyperpolarization (EDH) factors. Importantly, the contribution of EDRFs to endothelium-dependent vasodilatation markedly varies in a vessel size-dependent manner; NO mainly mediates vasodilatation of relatively large vessels, while EDH factors in small resistance vessels. We have previously identified that endothelium-derived hydrogen peroxide (H₂O₂) is an EDH factor especially in microcirculation. Several lines of evidence indicate the importance of the physiological balance between NO and H₂O₂/EDH factor. Rho-kinase was identified as the effectors of the small GTP-binding protein, RhoA. Both endothelial NO production and NO-mediated signaling in VSMC are targets and effectors of the RhoA/Rho-kinase pathway. In endothelial cells, the RhoA/Rho-kinase pathway negatively regulates NO production. On the contrary, the pathway enhances VSMC contraction with resultant occurrence of coronary artery spasm and promotes the development of oxidative stress and vascular remodeling. In this review, I will briefly summarize the current knowledge on the regulatory roles of endothelium-derived relaxing factors, with special references to NO and H₂O₂/EDH factor, in relation to Rho-kinase, in cardiovascular health and disease.

Protective effects of acarbose against vascular endothelial dysfunction through inhibiting Nox4/NLRP3 inflammasome pathway in diabetic rats

The cardiovascular efficacy of glucose-lowering drugs is needed due to the cardiovascular complication in type 2 diabetes mellitus (T2DM). Acarbose is an α-glucosidase inhibitor that suppresses postprandial hyperglycemia, however, the cardiovascular protection of acarbose has still remained controversial. NLRP3 inflammasome activation mediated tight junction disruption, a hallmark event of endothelial barrier dysfunction leading to endothelial hyperpermeability in diabetes. Given the anti-inflammatory property of acarbose, it was investigated that acarbose protected against vascular endothelial barrier dysfunction through inhibiting NLRP3 inflammasome in vascular endothelial cells in T2DM rats. The rat aortic endothelial cells (RAECs) were incubated with high glucose (HG, 30 mM) for 24 h in vitro. It was found that HG significantly induced the formation and activation of NLRP3 inflammasome, which was markedly blocked by acarbose treatment. Furthermore, acarbose blocked the Nox4-dependent superoxide (O₂^.-) generation, which regulated NLRP3 inflammasome in RAECs. Importantly, we found that acarbose remarkably enhanced the junction protein expression of ZO-1 and VE-Cadherin and consequently abolished vascular hyperpermeability, which was associated with inhibiting NLRP3 inflammasome in RAECs. In vivo, acarbose intervention relieved vascular leakage in the heart of diabetic rats injected with Evans blue dye and the vasodilatory response to acetylcholine, which was accompanied with the restoration of ZO-1, VE-Cadherin, Nox4 and NLRP3 inflammasome in the aortal endothelium of diabetic rats. Taken together, our data indicated that acarbose ameliorated endothelial barrier dysfunction by directly inhibiting NLRP3 inflammasome which was dependent on inhibiting Nox4 oxidase-dependent O₂^.- production. These properties might carry a potential significance for acarbose in cardiovascular protection in diabetic patients.

Natural Bioactive Compounds As Protectors Of Mitochondrial Dysfunction In Cardiovascular Diseases And Aging

Diet, particularly the Mediterranean diet, has been considered as a protective factor against the development of cardiovascular diseases, the main cause of death in the world. Aging is one of the major risk factors for cardiovascular diseases, which have an oxidative pathophysiological component, being the mitochondria one of the key organelles in the regulation of oxidative stress. Certain natural bioactive compounds have the ability to regulate oxidative phosphorylation, the production of reactive oxygen species and the expression of mitochondrial proteins; but their efficacy within the mitochondrial physiopathology of cardiovascular diseases has not been clarified yet. The following review has the purpose of evaluating several natural compounds with evidence of mitochondrial effect in cardiovascular disease models, ascertaining the main cellular mechanisms and their potential use as functional foods for prevention of cardiovascular disease and healthy aging.

TSH inhibits eNOS expression in HMEC-1 cells through the TSHR/PI3K/AKT signaling pathway

OBJECTIVE

To investigate the effects of thyroid-stimulating hormone (TSH) on the expression of endothelial nitric oxide synthase (eNOS) in human microvascular endothelial cells (HMEC-1) and explore the potential mechanism.

MATERIALS AND METHODS

Expression of thyroid-stimulating hormone receptor (TSHR) in HMEC-1 cells was determined by immunofluorescence, reverse transcription-polymerase chain reaction (RT-PCR), and Western blotting. Cell proliferation and the production of nitric oxide (NO) and superoxide anion (SA) were measured after TSH treatment. eNOS expression and AKT phosphorylation were detected by Western blotting.

RESULTS

TSHR was expressed in HMEC-1 cells. TSH promoted HMEC-1 cell proliferation and SA production, but inhibited NO generation by dose-dependent blocking of mRNA and protein expression of eNOS. Mechanism studies demonstrated that TSH promoted AKT phosphorylation (P<0.05), and that LY294002 inhibited the reduction of eNOS expression by TSH. Moreover, TSH activated the AKT signaling pathway through binding to TSHR on HMEC-1 cells.

CONCLUSIONS

TSH inhibits NO production via the TSHR/AKT signaling pathway.

Say NO to ROS: Their Roles in Embryonic Heart Development and Pathogenesis of Congenital Heart Defects in Maternal Diabetes

Congenital heart defects (CHDs) are the most prevalent and serious birth defect, occurring in 1% of all live births. Pregestational maternal diabetes is a known risk factor for the development of CHDs, elevating the risk in the child by more than four-fold. As the prevalence of diabetes rapidly rises among women of childbearing age, there is a need to investigate the mechanisms and potential preventative strategies for these defects. In experimental animal models of pregestational diabetes induced-CHDs, upwards of 50% of offspring display congenital malformations of the heart, including septal, valvular, and outflow tract defects. Specifically, the imbalance of nitric oxide (NO) and reactive oxygen species (ROS) signaling is a major driver of the development of CHDs in offspring of mice with pregestational diabetes. NO from endothelial nitric oxide synthase (eNOS) is crucial to cardiogenesis, regulating various cellular and molecular processes. In fact, deficiency in eNOS results in CHDs and coronary artery malformation. Embryonic hearts from diabetic dams exhibit eNOS uncoupling and oxidative stress. Maternal treatment with sapropterin, a cofactor of eNOS, and antioxidants such as N-acetylcysteine, vitamin E, and glutathione as well as maternal exercise have been shown to improve eNOS function, reduce oxidative stress, and lower the incidence CHDs in the offspring of mice with pregestational diabetes. This review summarizes recent data on pregestational diabetes-induced CHDs, and offers insights into the important roles of NO and ROS in embryonic heart development and pathogenesis of CHDs in maternal diabetes.

Lipoic acid antagonizes paraquat-induced vascular endothelial dysfunction by suppressing mitochondrial reactive oxidative stress

Paraquat (PQ) is a widely used herbicide in the agricultural field. The lack of an effective antidote is the significant cause of high mortality in PQ poisoning. Here, we investigate the antagonistic effects of alpha lipoic acid (α-LA), a naturally existing antioxidant, on PQ toxicity in human microvascular endothelial cells (HMEC-1). All the doses of 250, 500 and 1000 μM α-LA significantly inhibited 1000 μM PQ-induced cytotoxicity in HMEC-1 cells. α-LA pretreatment remarkably diminished the damage to cell migration ability, recovered the declined levels of the vasodilator factor nitric oxide (NO), elevated the expression level of endothelial nitric oxide synthases (eNOS), and inhibited the upregulated expression of vasoconstrictor factor endothelin-1 (ET-1). Moreover, α-LA pretreatment inhibited reactive oxygen species (ROS) generation, suppressed the damage to the mitochondrial membrane potential (ΔΨ _m) and mitigated the inhibition of adenosine triphosphate (ATP) production in HMEC-1 cells. These results suggested that α-LA could alleviate PQ-induced endothelial dysfunction by suppressing oxidative stress. In summary, our present study provides novel insight into the protective effects and pharmacological potential of α-LA against PQ toxicity in microvascular endothelial cells.

Mesenchymal Stem Cell Secretion of SDF-1α Modulates Endothelial Function in Dilated Cardiomyopathy

BACKGROUND

Endothelial dysfunction contributes to the pathophysiology of dilated cardiomyopathy (DCM). Allogeneic but not autologous mesenchymal stem cells (MSCs) improve endothelial function in DCM patients. We hypothesized that these effects are modulated by release of stromal derived factor-1α (SDF-1α).

METHODS

Plasma TNFα and endothelial progenitor cell-colony forming units (EPC-CFUs) were assessed at baseline and 3-months post-injection in a subset of POSEIDON-DCM patients that received autologous (n = 11) or allogeneic (n = 10) MSCs. SDF-1α secretion by MSCs, endothelial cell (EC) TNFα mRNA expression, and levels of reactive oxygen species (ROS) in response to SDF-1α were measured in vitro.

RESULTS

As previously shown, DCM patients (n = 21) had reduced EPC-CFUs at baseline (3 ± 3), which were restored to normal by allogeneic MSCs 3-months post-treatment (Δ10 ± 4). DCM patients had elevated baseline plasma TNFα (n = 15, 22 ± 9.4 pg/mL). Allogeneic MSCs (n = 8) decreased, and autologous MSCs (n = 7) increased, plasma TNFα (-7.1 ± 3.1 vs. 22.2 ± 17.1 pg/mL, respectively; P = 0.0005). In culture, autologous MSCs (n = 11) secreted higher levels of SDF-1α than allogeneic MSCs (n = 6) [76.0 (63.7, 100.9) vs. 22.8 (7.2, 43.5) pg/mL, P = 0.0002]. SDF-1α and plasma TNFα negatively correlated with EPC-CFUs in both treatment groups (R = -0.7, P = 0.0004). ECs treated with 20 ng SDF-1α expressed lower levels of TNFα mRNA than cells treated with 100 ng (0.7 ± 0.2 vs. 2.1 ± 0.3, P = 0.0008). SDF-1α at low but not high concentration inhibited the generation of ROS.

CONCLUSION

MSC secretion of SDF-1α inversely correlates with EPC-CFU production in DCM patients and therefore may be a modulator of MSC therapeutic effect in this clinical setting.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT01392625, identifier NCT01392625.

Different vasodilator mechanisms in intermediate- and small-sized arteries from the hindlimb vasculature of the toad Rhinella marina

In this study, myography was used to determine the effect of arterial size on nitric oxide (NO) vasodilatory mechanisms in the hindlimb vasculature of the toad Rhinella marina. Immunohistochemical analysis showed NO synthase (NOS) 1 immunoreactivity in perivascular nitrergic nerves in the iliac and sciatic arteries. Furthermore, NOS3 immunoreactivity was observed in the vascular smooth muscle of the sciatic artery, but not the endothelium. Acetylcholine (ACh) was used to facilitate intracellular Ca2+ signaling to activate vasodilatory pathways in the arteries. In the iliac artery, ACh-mediated vasodilation was abolished by blockade of the soluble guanylate cyclase pathway with the soluble guanylate cyclase inhibitor ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, 10−5 M) and blockade of the prostaglandin signaling pathway with indomethacin (10−5 M). Furthermore, disruption of the endothelium had no effect on the ACh-mediated vasodilation in the iliac artery, and generic inhibition of NOS with Nω-nitro-l-arginine (3 × 10−4 M) significantly inhibited the vasodilation, indicating NO signaling. In contrast to the iliac artery, ACh-mediated vasodilation of the sciatic artery had a significant endothelium-dependent component. Interestingly, the vasodilation was not significantly affected by Nω-nitro-l-arginine, but it was significantly inhibited by the specific NOS1 inhibitor N5-(1-imino-3-butenyl)-l-ornithine (vinyl-l-NIO, 10−4 M). ODQ mostly inhibited the ACh-mediated vasodilation. In addition, indomethacin also significantly inhibited the ACh-mediated vasodilation, indicating a role for prostaglandins in the sciatic artery. This study found that the mechanisms of vasodilation in the hindlimb vasculature of R. marina vary with vessel size and that the endothelium is involved in vasodilation in the smaller sciatic artery.

Therapeutic targets for endothelial dysfunction in vascular diseases

Vascular endothelial cells are located on the surface of the blood vessels. It has been recognized as an important barrier to the regulation of vascular homeostasis by regulating the blood flow of micro- or macrovascular vessels. Indeed, endothelial dysfunction is an initial stage of vascular diseases and is an important prognostic indicator of cardiovascular and metabolic diseases such as atherosclerosis, hypertension, heart failure, or diabetes. Therefore, in order to develop therapeutic targets for vascular diseases, it is important to understand the key factors involved in maintaining endothelial function and the signaling pathways affecting endothelial dysfunction. The purpose of this review is to describe the function and underlying signaling pathway of oxidative stress, inflammatory factors, shear stress, and epigenetic factors in endothelial dysfunction, and introduce recent therapeutic targets for the treatment of cardiovascular diseases.

Endothelium-Dependent Hyperpolarization (EDH) in Diabetes: Mechanistic Insights and Therapeutic Implications

Diabetes mellitus is one of the major risk factors for cardiovascular disease and is an important health issue worldwide. Long-term diabetes causes endothelial dysfunction, which in turn leads to diabetic vascular complications. Endothelium-derived nitric oxide is a major vasodilator in large-size vessels, and the hyperpolarization of vascular smooth muscle cells mediated by the endothelium plays a central role in agonist-mediated and flow-mediated vasodilation in resistance-size vessels. Although the mechanisms underlying diabetic vascular complications are multifactorial and complex, impairment of endothelium-dependent hyperpolarization (EDH) of vascular smooth muscle cells would contribute at least partly to the initiation and progression of microvascular complications of diabetes. In this review, we present the current knowledge about the pathophysiology and underlying mechanisms of impaired EDH in diabetes in animals and humans. We also discuss potential therapeutic approaches aimed at the prevention and restoration of EDH in diabetes.

Pharmacogenetic Implications of eNOS Polymorphisms (Glu298Asp, T786C, 4b/4a) in Cardiovascular Drug Therapy

Endothelial nitric oxide synthase (NOS3 or eNOS) is the enzyme responsible for the highest production of nitric oxide, with the greatest impact on the cardiovascular system, encoded by the eNOS gene, which presents various polymorphisms. ENOS gene polymorphisms play an important role in the response to drugs affecting nitric oxide (NO) signaling. This review discusses the pharmacogenetic impact of eNOS polymorphisms on the response to drugs affecting NO activity: angiotensin converting enzyme inhibitors, angiotensin II receptor antagonists, calcium blockers, beta-blockers, diuretics, phosphodiesterase inhibitors, and statins. The identification of biomarkers that accurately predict particular phenotypes is a challenge that needs additional large studies, in different populations. Efforts should be oriented towards a more accurate evaluation of the effects of eNOS genetic variants on biochemical parameters reflecting eNOS gene expression and enzymatic activity, in different diseases, as well as following drug treatment. This approach will allow for a better understanding of the role of eNOS genetic variants in cardiovascular disease progression and for cardiovascular drug therapy optimization.

Nitric Oxide and Hydrogen Sulfide Regulation of Ischemic Vascular Growth and Remodeling

Ischemic vascular remodeling occurs in response to stenosis or arterial occlusion leading to a change in blood flow and tissue perfusion. Altered blood flow elicits a cascade of molecular and cellular physiological responses leading to vascular remodeling of the macro- and micro-circulation. Although cellular mechanisms of vascular remodeling such as arteriogenesis and angiogenesis have been studied, therapeutic approaches in these areas have had limited success due to the complexity and heterogeneous constellation of molecular signaling events regulating these processes. Understanding central molecular players of vascular remodeling should lead to a deeper understanding of this response and aid in the development of novel therapeutic strategies. Hydrogen sulfide (H₂ S) and nitric oxide (NO) are gaseous signaling molecules that are critically involved in regulating fundamental biochemical and molecular responses necessary for vascular growth and remodeling. This review examines how NO and H₂ S regulate pathophysiological mechanisms of angiogenesis and arteriogenesis, along with important chemical and experimental considerations revealed thus far. The importance of NO and H₂ S bioavailability, their synthesis enzymes and cofactors, and genetic variations associated with cardiovascular risk factors suggest that they serve as pivotal regulators of vascular remodeling responses. © 2019 American Physiological Society. Compr Physiol 9:1213-1247, 2019.

Light-induced formation of NO in endothelial cells by photoactivatable NADPH analogues targeting nitric-oxide synthase

BACKGROUND

Nitric-oxide synthases (NOS) catalyze the formation of NO using NADPH as electron donor. We have recently designed and synthesized a new series of two-photon absorbing and photoactivatable NADPH analogues (NT). These compounds bear one or two carboxymethyl group(s) on the 2'- or/and 3'-position(s) of the ribose in the adenosine moiety, instead of a 2'-phosphate group, and differ by the nature of the electron donor in their photoactivatable chromophore (replacing the nicotinamide moiety). Here, we addressed the ability of NTs to photoinduce eNOS-dependent NO production in endothelial cells.

METHODS

The cellular fate of NTs and their photoinduced effects were studied using multiphoton fluorescence imaging, cell viability assays and a BODIPY-derived NO probe for NO measurements. The eNOS dependence of photoinduced NO production was addressed using two NOS inhibitors (NS1 and L-NAME) targeting the reductase and the oxygenase domains, respectively.

RESULTS

We found that, two compounds, those bearing a single carboxymethyl group on the 3'-position of the ribose, colocalize with the Golgi apparatus (the main intracellular location of eNOS) and display high intracellular two-photon brightness. Furthermore, a eNOS-dependent photooxidation was observed for these two compounds only, which is accompanied by a substantial intracellular NO production accounting for specific photocytotoxic effects.

CONCLUSIONS

We show for the first time that NT photoactivation efficiently triggers electron flow at the eNOS level and increases the basal production of NO by endothelial cells.

GENERAL SIGNIFICANCE

Efficient photoactivatable NADPH analogues targeting NOS could have important implications for generating apoptosis in tumor cells or modulating NO-dependent physiological processes.

Putting VE-cadherin into JAIL for junction remodeling

Junction dynamics of endothelial cells are based on the integration of signal transduction, cytoskeletal remodeling and contraction, which are necessary for the formation and maintenance of monolayer integrity, but also enable repair and regeneration. The VE-cadherin–catenin complex forms the molecular basis of the adherence junctions and cooperates closely with actin filaments. Several groups have recently described small actin-driven protrusions at the cell junctions that are controlled by the Arp2/3 complex, contributing to cell junction regulation. We identified these protrusions as the driving force for VE-cadherin dynamics, as they directly induce new VE-cadherin-mediated adhesion sites, and have accordingly referred to these structures as junction-associated intermittent lamellipodia (JAIL). JAIL extend over only a few microns and thus provide the basis for a subcellular regulation of adhesion. The local (subcellular) VE-cadherin concentration and JAIL formation are directly interdependent, which enables autoregulation. Therefore, this mechanism can contribute a subcellularly regulated adaptation of cell contact dynamics, and is therefore of great importance for monolayer integrity and relative cell migration during wound healing and angiogenesis, as well as for inflammatory responses. In this Review, we discuss the mechanisms and functions underlying these actin-driven protrusions and consider their contribution to the dynamic regulation of endothelial cell junctions.

Redox Signaling from and to Peroxisomes: Progress, Challenges, and Prospects

SIGNIFICANCE

Peroxisomes are organelles that are best known for their role in cellular lipid and hydrogen peroxide (H₂O₂) metabolism. Emerging evidence suggests that these organelles serve as guardians and modulators of cellular redox balance, and that alterations in their redox metabolism may contribute to aging and the development of chronic diseases such as neurodegeneration, diabetes, and cancer. Recent Advances: H₂O₂ is an important signaling messenger that controls many cellular processes by modulating protein activity through cysteine oxidation. Somewhat surprisingly, the potential involvement of peroxisomes in H₂O₂-mediated signaling processes has been overlooked for a long time. However, recent advances in the development of live-cell approaches to monitor and modulate spatiotemporal fluxes in redox species at the subcellular level have opened up new avenues for research in redox biology and boosted interest in the concept of peroxisomes as redox signaling platforms.

CRITICAL ISSUES

This review first introduces the reader to what is known about the role of peroxisomes in cellular H₂O₂ production and clearance, with a focus on mammalian cells. Next, it briefly describes the benefits and drawbacks of current strategies used to investigate the complex interplay between peroxisome metabolism and cellular redox state. Furthermore, it integrates and critically evaluates literature dealing with the interrelationship between peroxisomal redox metabolism, cell signaling, and human disease.

FUTURE DIRECTIONS

As the precise molecular mechanisms underlying many of these associations are still poorly understood, a key focus for future research should be the identification of primary targets for peroxisome-derived H₂O₂.