Effects of resveratrol on eNOS in the endothelium and the perivascular adipose tissue

Signaling pathways in vascular function and hypertension: molecular mechanisms and therapeutic interventions

Hypertension is a global public health issue and the leading cause of premature death in humans. Despite more than a century of research, hypertension remains difficult to cure due to its complex mechanisms involving multiple interactive factors and our limited understanding of it. Hypertension is a condition that is named after its clinical features. Vascular function is a factor that affects blood pressure directly, and it is a main strategy for clinically controlling BP to regulate constriction/relaxation function of blood vessels. Vascular elasticity, caliber, and reactivity are all characteristic indicators reflecting vascular function. Blood vessels are composed of three distinct layers, out of which the endothelial cells in intima and the smooth muscle cells in media are the main performers of vascular function. The alterations in signaling pathways in these cells are the key molecular mechanisms underlying vascular dysfunction and hypertension development. In this manuscript, we will comprehensively review the signaling pathways involved in vascular function regulation and hypertension progression, including calcium pathway, NO-NOsGC-cGMP pathway, various vascular remodeling pathways and some important upstream pathways such as renin-angiotensin-aldosterone system, oxidative stress-related signaling pathway, immunity/inflammation pathway, etc. Meanwhile, we will also summarize the treatment methods of hypertension that targets vascular function regulation and discuss the possibility of these signaling pathways being applied to clinical work.

Perivascular adipose tissue: Fine-tuner of vascular redox status and inflammation

Perivascular adipose tissue (PVAT) refers to the aggregate of adipose tissue surrounding the vasculature, exhibiting the phenotypes of white, beige and brown adipocytes. PVAT has emerged as an active modulator of vascular homeostasis and pathogenesis of cardiovascular diseases in addition to its structural role to provide mechanical support to blood vessels. More specifically, PVAT is closely involved in the regulation of reactive oxygen species (ROS) homeostasis and inflammation along the vascular tree, through the tight interaction between PVAT and cellular components of the vascular wall. Furthermore, the phenotype-genotype of PVAT at different regions of vasculature varies corresponding to different cardiovascular risks. During ageing and obesity, the cellular proportions and signaling pathways of PVAT vary in favor of cardiovascular pathogenesis by promoting ROS generation and inflammation. Physiological means and drugs that alter PVAT mass, components and signaling may provide new therapeutic insights in the treatment of cardiovascular diseases. In this review, we aim to provide an updated understanding towards PVAT in the context of redox regulation, and to highlight the therapeutic potential of targeting PVAT against cardiovascular complications.

Endothelial Nitric Oxide Synthase in the Perivascular Adipose Tissue

Perivascular adipose tissue (PVAT) is a special type of ectopic fat depot that adheres to most vasculatures. PVAT has been shown to exert anticontractile effects on the blood vessels and confers protective effects against metabolic and cardiovascular diseases. PVAT plays a critical role in vascular homeostasis via secreting adipokine, hormones, and growth factors. Endothelial nitric oxide synthase (eNOS; also known as NOS3 or NOSIII) is well-known for its role in the generation of vasoprotective nitric oxide (NO). eNOS is primarily expressed, but not exclusively, in endothelial cells, while recent studies have identified its expression in both adipocytes and endothelial cells of PVAT. PVAT eNOS is an important player in the protective role of PVAT. Different studies have demonstrated that, under obesity-linked metabolic diseases, PVAT eNOS may be even more important than endothelium eNOS in obesity-induced vascular dysfunction, which may be attributed to certain PVAT eNOS-specific functions. In this review, we summarized the current understanding of eNOS expression in PVAT, its function under both physiological and pathological conditions and listed out a few pharmacological interventions of interest that target eNOS in PVAT.

The Involvement of Sirtuin 1 Dysfunction in High-Fat Diet-Induced Vascular Dysfunction in Mice

High-fat diet (HFD)-induced vascular impairment in mice is associated with a dysfunction of the perivascular adipose tissue (PVAT). The present study was conducted to investigate the involvement of sirtuin 1 (SIRT1). Male C57BL/6J mice were fed an HFD for 20 weeks to induce obesity. Vascular function was analyzed using a wire myograph system. In obese mice, the vasodilator response of PVAT-containing aortas to acetylcholine was reduced, although the vascular function of PVAT-free aortas remained normal. SIRT1 activity in PVAT of obese mice was reduced despite enhanced SIRT1 expression. Nicotinamide adenine dinucleotide (NAD⁺) levels and the NAD⁺/NADH ratio in the PVAT of obese mice were decreased, which was likely attributable to a downregulation of the NAD⁺-producing enzyme NAMPT. The reduced SIRT1 activity was associated with an enhanced acetylation of the endothelial nitric oxide synthase (eNOS) in the PVAT. Ex vivo incubation of PVAT-containing aorta from obese mice with NAD⁺ led to a complete normalization of vascular function. Thus, reduced SIRT1 activity due to NAD⁺ deficiency is involved in obesity-induced PVAT dysfunction.

Nanostructured Lipid Carriers Deliver Resveratrol, Restoring Attenuated Dilation in Small Coronary Arteries, via the AMPK Pathway

Nanostructured lipid carriers (NLCs) are an emerging drug delivery platform for improved drug stability and the bioavailability of antihypertensive drugs and vasoprotective nutraceutical compounds, such as resveratrol (RV). The objective of this study was to ascertain NLCs’ potential to deliver RV and restore attenuated dilator function, using an ex vivo model of acute hypertension. Trimyristin–triolein NLCs were synthesized and loaded with RV. The uptake of RV-NLCs by human coronary artery endothelial cells (HCAECs) maintained their viability and reduced both mitochondrial and cytosolic superoxide levels. Acute pressure elevation in isolated coronary arteries significantly attenuated endothelial-dependent dilator responses, which were reversed following incubation in RV-NLCs, superoxide dismutase or apocynin (p < 0.0001). RV-NLCs demonstrated a five-fold increase in potency in comparison to RV solution. At elevated pressure, in the presence of RV-NLCs, incubation with Nω-nitro-l-arginine (L-NNA) or indomethacin resulted in a significant reduction in the restored dilator component (p < 0.0001), whereas apamin and TRAM-34 had no overall effect. Incubation with the adenosine monophosphate-activated protein kinase (AMPK) inhibitor dorsomorphin significantly attenuated dilator responses (p < 0.001), whereas the SIRT-1 inhibitor EX-527 had no effect. RV-NLCs improved the impaired endothelial-dependent dilation of small coronary arteries, following acute pressure elevation, via NO and downstream COX elements, mediated by AMPK. We suggest that RV-NLCs are an effective delivery modality for improved potency and sustained drug release into the vasculature. Our findings have important implications for the future design and implementation of antihypertensive treatment strategies.

Adipose Tissue-Endothelial Cell Interactions in Obesity-Induced Endothelial Dysfunction

Obesity has a strong impact on the pathogenesis of cardiovascular disease, which raises enthusiasm to understand how excess adiposity causes vascular injury. Adipose tissue is an essential regulator of cardiovascular system through its endocrine and paracrine bioactive products. Obesity induces endothelial dysfunction, which often precedes and leads to the development of cardiovascular diseases. Connecting adipose tissue-endothelial cell interplay to endothelial dysfunction may help us to better understand obesity-induced cardiovascular disease. This Mini Review discussed (1) the general interactions and obesity-induced endothelial dysfunction, (2) potential targets, and (3) the outstanding questions for future research.

Network analysis of the left anterior descending coronary arteries in swim-trained rats by an in situ video microscopic technique

BACKGROUND

We aimed to identify sex differences in the network properties and to recognize the geometric alteration effects of long-term swim training in a rat model of exercise-induced left ventricular (LV) hypertrophy.

METHODS

Thirty-eight Wistar rats were divided into four groups: male sedentary, female sedentary, male exercised and female exercised. After training sessions, LV morphology and function were checked by echocardiography. The geometry of the left coronary artery system was analysed on pressure-perfused, microsurgically prepared resistance artery networks using in situ video microscopy. All segments over > 80 μm in diameter were studied using divided 50-μm-long cylindrical ring units of the networks. Oxidative-nitrative (O-N) stress markers, adenosine A2A and estrogen receptor (ER) were investigated by immunohistochemistry.

RESULTS

The LV mass index, ejection fraction and fractional shortening significantly increased in exercised animals. We found substantial sex differences in the coronary network in the control groups and in the swim-trained animals. Ring frequency spectra were significantly different between male and female animals in both the sedentary and trained groups. The thickness of the wall was higher in males as a result of training. There were elevations in the populations of 200- and 400-μm vessel units in males; the thinner ones developed farther and the thicker ones closer to the orifice. In females, a new population of 200- to 250-μm vessels appeared unusually close to the orifice.

CONCLUSIONS

Physical activity and LV hypertrophy were accompanied by a remodelling of coronary resistance artery network geometry that was different in both sexes.

Evaluation of Biological Mechanisms of Eucommiae Folium in Hypertensive Kidney Injury by Integration of Untargeted Metabolomics and Network Pharmacology

Hypertensive kidney injury (Hki) is one of the most common complications of hypertension. Early prevention and treatment of renal injury in patients with hypertension is great significance. The study, which used an integrated ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS) analysis, network pharmacology approach, and plasma metabolomics, aimed to discover the active ingredients and therapeutic mechanisms of Eucommiae folium (Ef) in treating Hki. The chemical components of Ef were analyzed by UPLC-quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS), and the "compound-target-disease" network was constructed by screening the closely related drug targets from the drug-target database, then the signaling pathways related to Hki were analyzed. Finally, the enzyme-linked immunosorbent assay (ELISA) and real-time quantitative reverse-transcription polymerase chain reaction were used to test and verify the key targets in the common pathways of metabolomics and network pharmacology. The results indicated that Eucommiae folium might play an excellent role in treating Hki, likely through regulating the vascular endothelial growth factor signaling pathway, hypoxia inducible factor 1 (HIF-1) signaling pathway, and glycerophospholipid metabolism pathway, which were validated by increasing levels of nitric oxide, endothelial nitric oxide synthase and reducing levels of endothelin 1, angiotensin II, renin, cyclic guanosine monophosphate, blood urea nitrogen, and serum creatinine, as well as the reduced gene expression of Ache, Ddah2, Egfr, Lcat, Pla2g2a, Stat3 and Vegfa. The study systematically explored the protective mechanisms of Ef against Hki and also provided the practical treatment strategies of Hki from the Chinese herb.

Positive Correlation between nNOS and Stress-Activated Bowel Motility Is Confirmed by In Vivo HiBiT System

Neuronal nitric oxide synthase (nNOS) has various roles as a neurotransmitter. However, studies to date have produced insufficient data to fully support the correlation between nNOS and bowel motility. This study aimed to investigate the correlation between nNOS expression and gastrointestinal (GI) tract motility using a stress-induced neonatal maternal separation (NMS) mouse model. In this study, we generated a genetically modified mouse with the HiBiT sequence knock-in into the nNOS gene using CRISPR/Cas9 for analyzing accurate nNOS expression. nNOS expression was measured in the stomach, small intestine, large intestine, adrenal gland, and hypothalamus tissues after establishing the NMS model. The NMS model exhibited a significant increase in nNOS expression in large intestine, adrenal gland, and hypothalamus. Moreover, a significant positive correlation was observed between whole gastrointestinal transit time and the expression level of nNOS. We reasoned that NMS induced chronic stress and consequent nNOS activation in the hypothalamic-pituitary-adrenal (HPA) axis, and led to an excessive increase in intestinal motility in the lower GI tract. These results demonstrated that HiBiT is a sensitive and valuable tool for analyzing in vivo gene activation, and nNOS could be a biomarker of the HPA axis-linked lower intestinal tract dysfunction.

Resveratrol reduced the detrimental effects of malondialdehyde on human endothelial cells

Introduction: According to the statistics, vascular injury occurs during the onset of diabetic changes after the production of several byproducts. Many authorities have focused to find an alternative therapy for diabetic patients. In this study, we investigated the therapeutic effects of natural polyphenol like resveratrol on human endothelial cells exposed to malondialdehyde for 48 hours.

Methods: Human Umbilical Vein Endothelial Cells were randomly classified into four groups;control, malondialdehyde (2.5 mM), resveratrol (100 μM), and cells received the combined regime for 48 hours. Cell viability was determined by 3-(4, 5-dimethyl thiazol-2-yl) 2, 5-diphenyl-tetrazoliumbromide (MTT) assay. Griess reaction was performed to measure the content of Nitric oxide (NO).Apoptosis was studied by using real-time polymerase chain reaction (RT-PCR) and western blotting assays. Levels of receptor tyrosine kinases like VEGFR-1, -2, Tie-1, and -2 were analyzed by enzyme-linked immunosorbent assay(ELISA). The affinity of resveratrol and malondialdehyde to serum albumin was measured by Surface Plasmon Resonance Assay. Any changes in chromatin remodeling were detected by PCR array analysis.

Results: Resveratrol reduced cytotoxicity and NO content inside cells induced by malondialdehyde(MDA) (P < 0.05). Endothelial cell apoptosis was decreased by the reduction of pro-apoptotic factor Bax and increase of Bcl-2 following the incubation with resveratrol (P < 0.05). MDA-induced receptor tyrosine kinases increase was inhibited by resveratrol and reached near-to-normal levels (P < 0.05).Surface Plasmon Resonance revealed a higher affinity of resveratrol to albumin compared to the malondialdehyde-albumin complex. Polymerase chain reaction (PCR) array revealed the potency of resveratrol in chromatin remodeling following the treatment with malondialdehyde (P < 0.05).

Conclusion: Based on our findings, resveratrol has the potential to decrease diabetic vascular injury induced by lipid byproducts such as MDA.

Contribution of the NLRP3/IL-1β axis to impaired vasodilation in sepsis through facilitation of eNOS proteolysis and the protective role of melatonin

Endothelial dysfunction is a typical characteristic of sepsis. Endothelial nitric oxide synthase (eNOS) is important for maintaining endothelial function. Our previous study reported that the NLRP3 inflammasome promoted endothelial dysfunction by enhancing inflammation. However, the effects of NLRP3 on eNOS require further investigation. Therefore, the present study aimed to investigate the role of NLRP3 on eNOS expression levels in cecal ligation and puncture-induced impaired endothelium-dependent vascular relaxation and to determine the protective effects of melatonin. eNOS expression levels were discovered to be downregulated in the mesenteric arteries of sepsis model mice. Inhibiting NLRP3 with 10 mg/ kg MCC950 or inhibiting IL-1β with 100 mg diacerein rescued the eNOS expression and improved endothelium-dependent vascular relaxation. In vitro, IL-1β stimulation downregulated eNOS expression levels in human aortic endothelial cells (HAECs) in a concentration- and time-dependent manner, while pretreatment with 1 µM of the proteasome inhibitor MG132 reversed this effect. In addition, treatment with 10 mg/kg MG132 also prevented the proteolysis of eNOS and improved endothelium-dependent vascular relaxation in vivo. Notably, treatment with 30 mg/kg melatonin downregulated NLRP3 expression levels and decreased IL-1β secretion, subsequently increasing the expression of eNOS and improving endothelium-dependent vascular relaxation. In conclusion, the findings of the present study indicated that the NLRP3/IL-1β axis may impair vasodilation by promoting the proteolysis of eNOS and melatonin may protect against sepsis-induced endothelial relaxation dysfunction by inhibiting the NLRP3/IL-1β axis, suggesting its pharmacological potential in sepsis.

Roles of Perivascular Adipose Tissue in Hypertension and Atherosclerosis

Significance: Perivascular adipose tissue (PVAT), which is present surrounding most blood vessels, from the aorta to the microvasculature of the dermis, is mainly composed of fat cells, fibroblasts, stem cells, mast cells, and nerve cells. Although the PVAT is objectively present, its physiological and pathological significance has long been ignored. Recent Advances: PVAT was considered as a supporting component of blood vessels and a protective cushion to the vessel wall from the neighboring tissues during relaxation and contraction. Nonetheless, further extensive research found that PVAT actively regulates blood vessel tone through PVAT-derived vasoactive factors, including both relaxing and contracting factors. In addition, PVAT contributes to atherosclerosis through paracrine secretion of a large number of bioactive factors such as adipokines and cytokines. Thereby, PVAT regulates the functions of blood vessels through various mechanisms operating directly on PVAT or on the underlying vessel layers, including vascular smooth muscle cells (VSMCs) and endothelial cells (ECs). Critical Issues: PVAT is a unique adipose tissue that plays an essential role in maintaining the vascular structure and regulating vascular function and homeostasis. This review focuses on recent updates on the various PVAT roles in hypertension and atherosclerosis. Future Directions: Future studies should further investigate the actual contribution of alterations in PVAT metabolism to the overall systemic outcomes of cardiovascular disease, which remains largely unknown. In addition, the messengers and underlying mechanisms responsible for the crosstalk between PVAT and ECs and VSMCs in the vascular wall should be systematically addressed, as well as the contributions of PVAT aging to vascular dysfunction.

Tetrahydroxystilbene glycoside improves endothelial dysfunction and hypertension in obese rats: The role of omentin-1

RATIONALE

Hypertension in obesity has become a major threat for public health. Omentin-1, a novel adipokine, is down-regulated in obesity. Tetrahydroxystilbene glycoside (TSG) is the main ingredient extracted from Polygonum multiflorum Thunb (PMT), a traditional Chinese medicinal herb safely used for protecting cardiovascular systems over bimillennium. This study aims to examine (i) the impact of omentin-1 downregulation on obesity-related hypertension in murine models and the underlying mechanisms; (ii) whether tetrahydroxystilbene glycoside (TSG) improved endothelial dysfunction and obesity-associated hypertension via the increase of omentin-1.

METHODS

(TSG-treated) male Zucker diabetic fatty (ZDF) rats and omentin-1 knockout (OMT^-/-) mice were used. In vitro, human umbilical vein endothelial cells (HUVECs) and mature adipocytes differentiated from human visceral preadipocyte (HPA-v) were maintained in a co-culture system.

RESULTS

TSG was the main active component of PMT reducing systolic blood pressure and improving endothelial vasodilation. Fortnight-TSG treatment (100 mg/kg/day) increased serum omentin-1 level, also activated Akt/eNOS signaling and enhanced NO bioactivity; decreased expression of NOX2 and p22^phox, suppressed production of superoxide and peroxynitrite anion. OMT^-/- mice showed elevated blood pressure and impaired endothelial vasorelaxation, whereas hypotensive effect of TSG was blunted. In co-culture system, TSG incubation promoted binding of peroxisome proliferator-activated receptor-γ (PPAR-γ) and Itln-1 promoter in adipocytes, activated Akt/eNOS/NO signaling and attenuated oxidative/nitrative stress in HUVECs. Suppression of Itln-1 with siRNA significantly blocked the protective effect of TSG in vitro.

CONCLUSIONS

Down-regulation of omentin-1 induces endothelial dysfunction and hypertension in obesity. TSG treatment (at least partially) increases omentin-1 via promoting binding of PPAR-γ and Itln-1 promoter in adipose tissues, subsequently exerts protective effects on endothelial function via activating Akt/eNOS/NO signaling and attenuating oxidative/nitrative stress. These results suggest that TSG could be developed as a promising anti-hypertension agent that protects against endothelial dysfunction and obesity-associated cardiovascular diseases.

Aging and age-related diseases: from mechanisms to therapeutic strategies

Aging is a physiological process mediated by numerous biological and genetic pathways, which are directly linked to lifespan and are a driving force for all age-related diseases. Human life expectancy has greatly increased in the past few decades, but this has not been accompanied by a similar increase in their healthspan. At present, research on aging biology has focused on elucidating the biochemical and genetic pathways that contribute to aging over time. Several aging mechanisms have been identified, primarily including genomic instability, telomere shortening, and cellular senescence. Aging is a driving factor of various age-related diseases, including neurodegenerative diseases, cardiovascular diseases, cancer, immune system disorders, and musculoskeletal disorders. Efforts to find drugs that improve the healthspan by targeting the pathogenesis of aging have now become a hot topic in this field. In the present review, the status of aging research and the development of potential drugs for aging-related diseases, such as metformin, rapamycin, resveratrol, senolytics, as well as caloric restriction, are summarized. The feasibility, side effects, and future potential of these treatments are also discussed, which will provide a basis to develop novel anti-aging therapeutics for improving the healthspan and preventing aging-related diseases.

Resveratrol Improves Heart Function by Moderating Inflammatory Processes in Patients with Systolic Heart Failure

The effects of resveratrol (RES) in heart failure have already been evaluated in animal models; however, in human clinical trials, they have not been confirmed yet. The aim of this study was to assess the effects of resveratrol treatment in systolic heart failure patients (heart failure with reduced ejection fraction or HFrEF). In this human clinical trial, 60 outpatients with NYHA (New York Heart Association) class II-III HFrEF were enrolled and randomized into two groups: receiving either 100-mg resveratrol daily or placebo for three months. At the beginning and at the end of the study echocardiography, a six-minute walk test, spirometry, quality of life questionnaire, lab test and RNA profile analysis were performed. The systolic and diastolic left ventricular function, as well as the global longitudinal strain, were improved significantly in the resveratrol-treated group (RES). Exercise capacity, ventilation parameters and quality of life also improved significantly in the RES group. In parallel, the cardiac biomarker levels (N-terminal prohormone of brain natriuretic peptide (NT-proBNP) and galectin-3) decreased in the treated group. The level of inflammatory cytokines decreased significantly after RES supplementation, as a consequence of the decreased expression level of leucocyte electron transport chain proteins. The main findings of our trial are that RES treatment added to the standard heart failure therapy improved heart function and the clinical condition by moderating the inflammatory processes in patients with HFrEF.

Circadian Rhythm in Adipose Tissue: Novel Antioxidant Target for Metabolic and Cardiovascular Diseases

Obesity is a major risk factor for most metabolic and cardiovascular disorders. Adipose tissue is an important endocrine organ that modulates metabolic and cardiovascular health by secreting signaling molecules. Oxidative stress is a common mechanism associated with metabolic and cardiovascular complications including obesity, type 2 diabetes, and hypertension. Oxidative stress can cause adipose tissue dysfunction. Accumulating data from both humans and experimental animal models suggest that adipose tissue function and oxidative stress have an innate connection with the intrinsic biological clock. Circadian clock orchestrates biological processes in adjusting to daily environmental changes according to internal or external cues. Recent studies have identified the genes and molecular pathways exhibiting circadian expression patterns in adipose tissue. Disruption of the circadian rhythmicity has been suggested to augment oxidative stress and aberrate adipose tissue function and metabolism. Therefore, circadian machinery in the adipose tissue may be a novel therapeutic target for the prevention and treatment of metabolic and cardiovascular diseases. In this review, we summarize recent findings on circadian rhythm and oxidative stress in adipose tissue, dissect the key components that play a role in regulating the clock rhythm, oxidative stress and adipose tissue function, and discuss the potential use of antioxidant treatment on metabolic and cardiovascular diseases by targeting the adipose clock.

Anti-Hypertensive Effects of Peptides Derived from Rice Bran Protein

Hypertension is one of the major risk factors for arteriosclerosis. Anti-hypertensive peptides derived from animal proteins, such as milk, eggs and fish, are well studied. Anti-hypertensive peptides have also been identified from plant proteins such as soybeans. Rice bran, a byproduct of white rice polishing, is rich in protein and its high protein efficiency ratio is well known. This review discusses the anti-hypertensive peptides identified from rice bran protein and their mechanisms. In addition, we describe protease-digested rice bran from which functional peptides have not been isolated.

Impact of Lifestyles (Diet and Exercise) on Vascular Health: Oxidative Stress and Endothelial Function

Healthy lifestyle and diet are associated with significant reduction in risk of obesity, type 2 diabetes, and cardiovascular diseases. Oxidative stress and the imbalance between prooxidants and antioxidants are linked to cardiovascular and metabolic diseases. Changes in antioxidant capacity of the body may lead to oxidative stress and vascular dysfunction. Diet is an important source of antioxidants, while exercise offers many health benefits as well. Recent findings have evidenced that diet and physical factors are correlated to oxidative stress. Diet and physical factors have debatable roles in modulating oxidative stress and effects on the endothelium. Since endothelium and oxidative stress play critical roles in cardiovascular and metabolic diseases, dietary and physical factors could have significant implications on prevention of the diseases. This review is aimed at summarizing the current knowledge on the impact of diet manipulation and physical factors on endothelium and oxidative stress, focusing on cardiovascular and metabolic diseases. We discuss the friend-and-foe role of dietary modification (including different diet styles, calorie restriction, and nutrient supplementation) on endothelium and oxidative stress, as well as the potential benefits and concerns of physical activity and exercise on endothelium and oxidative stress. A fine balance between oxidative stress and antioxidants is important for normal functions in the cells and interfering with this balance may lead to unfavorable effects. Further studies are needed to identify the best diet composition and exercise intensity.

Perivascular Adipose Tissue as a Target for Antioxidant Therapy for Cardiovascular Complications

Perivascular adipose tissue (PVAT) is the connective tissue surrounding most of the systemic blood vessels. PVAT is now recognized as an important endocrine tissue that maintains vascular homeostasis. Healthy PVAT has anticontractile, anti-inflammatory, and antioxidative roles. Vascular oxidative stress is an important pathophysiological event in cardiometabolic complications of obesity, type 2 diabetes, and hypertension. Accumulating data from both humans and experimental animal models suggests that PVAT dysfunction is potentially linked to cardiovascular diseases, and associated with augmented vascular inflammation, oxidative stress, and arterial remodeling. Reactive oxygen species produced from PVAT can be originated from mitochondria, nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, and uncoupled endothelial nitric oxide synthase. PVAT can also sense vascular paracrine signals and response by secreting vasoactive adipokines. Therefore, PVAT may constitute a novel therapeutic target for the prevention and treatment of cardiovascular diseases. In this review, we summarize recent findings on PVAT functions, ROS production, and oxidative stress in different pathophysiological settings and discuss the potential antioxidant therapies for cardiovascular diseases by targeting PVAT.

The vascular epigenome in patients with obesity and type 2 diabetes: opportunities for personalized therapies

Our genetic background provides limited information on individual risk of developing vascular complications overtime. New biological layers, namely epigenetic modifications, are now emerging as potent regulators of gene expression thus leading to altered transcriptional programs and vascular disease phenotypes. Such epigenetic modifications, defined as changes to the genome that do not involve changes in DNA sequence, are generally induced by environmental factors and poor lifestyle habits. Of note, adverse epigenetic signals acquired during life can be transmitted to the offspring thus leading to premature alterations of the epigenetic and transcriptional landscape eventually leading to early endothelial dysfunction and vascular senescence. Modifications of the epigenome play a pivotal role in the pathophysiology of cardiometabolic disturbances such as obesity and type 2 diabetes. In these patients, changes of DNA methylation and chromatin structure contribute to alter pathways regulating insulin sensitivity, glucose homeostasis, adipogenesis and vascular function. In this perspective, unveiling the 'epigenetic landscape' in cardiometabolic patients may help to identify new players implicated in obesity and diabetes-related vascular dysfunction and may pave the way for personalized therapies in this setting. In the present review, we discuss current knowledge of the epigenetic routes implicated in vascular damage and cardiovascular disease in patients with metabolic alterations.

Phosphorylation and activation of endothelial nitric oxide synthase by red fruit (Pandanus conoideus Lam) oil and its fractions

ETHNOPHARMACOLOGICAL RELEVANCE

Red fruit (Pandanus conoideus Lam) oil (RFO) is utilized by inhabitants of the Papua Island to treat diseases such as infections, cancer, and cardiovascular disease, but the mechanism of action is unknown.

AIM OF THE STUDY

We have recently shown that RFO stimulates nitric oxide (NO) production in endothelial cells. The present study was conducted to investigate the molecular mechanism of endothelial NO synthase (eNOS) activation by RFO.

MATERIALS AND METHODS

NO production by endothelial cells was determined with electron paramagnetic resonance. The vascular function of isolated mouse aorta was examined using a wire myograph system. Phosphorylation of eNOS was studied with Western blot analyses.

RESULTS

RFO induced concentration-dependent vasodilation in isolated mouse aorta. The vasodilator effect of RFO was lost in endothelium-denuded aorta and in aorta from mice deficient in eNOS. Treatment of human EA.hy 926 endothelial cells with RFO led to an enhancement of eNOS phosphorylation at serine 1177 and NO production. The RFO-induced eNOS phosphorylation and NO production were reduced by inhibitors of Akt or AMPK, but not by an inhibitor of CaMKII. The effects of RFO were decreased by pharmacological inhibition of PI3K, indicating an involvement of the PI3K-Akt pathway. Moreover, acetone-soluble fractions and oily fractions of RFO showed higher efficacies than the RFO polar fraction in activating eNOS.

CONCLUSIONS

RFO contains highly active compounds that enhance NO production through Akt- or AMPK-mediated eNOS phosphorylation. The increase in endothelial NO production is likely to represent one of the molecular mechanisms responsible for the therapeutic effects of RFO.

Potential Adverse Effects of Resveratrol: A Literature Review

Due to its health benefits, resveratrol (RE) is one of the most researched natural polyphenols. Resveratrol's health benefits were first highlighted in the early 1990s in the French paradox study, which opened extensive research activity into this compound. Ever since, several pharmacological activities including antioxidant, anti-aging, anti-inflammatory, anti-cancerous, anti-diabetic, cardioprotective, and neuroprotective properties, were attributed to RE. However, results from the available human clinical trials were controversial concerning the protective effects of RE against diseases and their sequelae. The reason for these conflicting findings is varied but differences in the characteristics of the enrolled patients, RE doses used, and duration of RE supplementation were proposed, at least in part, as possible causes. In particular, the optimal RE dosage capable of maximizing its health benefits without raising toxicity issues remains an area of extensive research. In this context, while there is a consistent body of literature on the protective effects of RE against diseases, there are relatively few reports investigating its possible toxicity. Indeed, toxicity and adverse effects were reported following consumption of RE; therefore, extensive future studies on the long-term effects, as well as the in vivo adverse effects, of RE supplementation in humans are needed. Furthermore, data on the interactions of RE when combined with other therapies are still lacking, as well as results related to its absorption and bioavailability in the human body. In this review, we collect and summarize the available literature about RE toxicity and side effects. In this process, we analyze in vitro and in vivo studies that have addressed this stilbenoid. These studies suggest that RE still has an unexplored side. Finally, we discuss the new delivery methods that are being employed to overcome the low bioavailability of RE.

L-Arginine Ameliorates High-Fat Diet-Induced Atherosclerosis by Downregulating miR-221

Objectives

Atherosclerosis (AS) is a severe disease in which the inside of an artery narrows because of plaque formation, leading to endothelial injury in the patients. Although it has been found that endothelial nitric oxide synthase (eNOS), which produces a low concentration of NO, is necessary for endothelial function and integrity, the regulatory mechanisms of eNOS expression against the pathogenesis and development of AS are unclear. Evidence has indicated that diet supplementation with L-arginine could reduce the size of the endothelial injury lesions in AS patients. In addition, nonencoding microRNAs (miRNAs) were found to be a promising tool that regulates the expression of eNOS in human endothelial cells.

Design

The aim of this research was to explore the role of L-arginine in the development of AS and the mechanisms by which miR-221 influences the possible signaling pathways in endothelial cells during AS.

Results

The results suggested that L-arginine could prevent oxidized low-density lipoprotein-induced apoptosis in endothelial cells, which is associated with the downregulation of miR-221. Similar results were also observed in rat AS models.

Conclusion

This research could provide potential therapies for the treatment of AS.

Effects of different diets used in diet-induced obesity models on insulin resistance and vascular dysfunction in C57BL/6 mice

The aim of the present study was to compare different diets used to induce obesity in a head-to-head manner with a focus on insulin resistance and vascular dysfunction. Male C57BL/6J mice were put on standard chow diet (SCD), normal-fat diet (NFD), cafeteria diet (CAF) or high-fat diet (HFD) for 12 weeks starting at the age of 6 weeks. Both CAF and HFD led to obesity (weight gain of 179% and 194%, respectively), glucose intolerance and insulin resistance to a comparable extent. In aortas containing perivascular adipose tissue (PVAT), acetylcholine-induced vasodilation was best in the NFD group and worst in the CAF group. Reduced phosphorylation of endothelial nitric oxide synthase at serine 1177 was observed in both CAF and HFD groups. Plasma coagulation activity was highest in the HFD group and lowest in the SCD group. Even the NFD group had significantly higher coagulation activity than the SCD group. In conclusions, CAF and HFD are both reliable mouse diets in inducing visceral obesity, glucose intolerance and insulin resistance. CAF is more effective than HFD in causing PVAT dysfunction and vascular dysfunction, whereas hypercoagulability was mostly evident in the HFD group. Coagulation activity was higher in NFD than NCD group.

Remote Effects of Transplanted Perivascular Adipose Tissue on Endothelial Function and Atherosclerosis

PURPOSE

Perivascular adipose tissue (PVAT) surrounds the arterial adventitia and plays an important role in vascular homeostasis. PVAT expands in obesity, and inflamed PVAT can locally promote endothelial dysfunction and atherosclerosis. Here, using adipose tissue transplantation, we tested the hypothesis that expansion of PVAT can also remotely exacerbate vascular disease.

METHODS

Fifty milligrams of abdominal aortic PVAT was isolated from high-fat diet (HFD)-fed wild-type mice and transplanted onto the abdominal aorta of lean LDL receptor knockout mice. Subcutaneous and visceral adipose tissues were used as controls. After HFD feeding for 10 weeks, body weight, glucose/insulin sensitivity, and lipid levels were measured. Adipocytokine gene expression was assessed in the transplanted adipose tissues, and the thoracic aorta was harvested to quantify atherosclerotic lesions by Oil-Red O staining and to assess vasorelaxation by wire myography.

RESULTS

PVAT transplantation did not influence body weight, fat composition, lipid levels, or glucose/insulin sensitivity. However, as compared with controls, transplantation of PVAT onto the abdominal aorta increased thoracic aortic atherosclerosis. Furthermore, PVAT transplantation onto the abdominal aorta inhibited endothelium-dependent relaxation in the thoracic aorta. MCP-1 and TNF-α expression was elevated, while adiponectin expression was reduced, in the transplanted PVAT tissue, suggesting augmented inflammation as a potential mechanism for the remote vascular effects of transplanted PVAT.

CONCLUSIONS

These data suggest that PVAT expansion and inflammation in obesity can remotely induce endothelial dysfunction and augment atherosclerosis. Identifying the underlying mechanisms may lead to novel approaches for risk assessment and treatment of obesity-related vascular disease.

Resveratrol and Vascular Function

Resveratrol increases the production of nitric oxide (NO) in endothelial cells by upregulating the expression of endothelial NO synthase (eNOS), stimulating eNOS enzymatic activity, and preventing eNOS uncoupling. At the same time, resveratrol inhibits the synthesis of endothelin-1 and reduces oxidative stress in both endothelial cells and smooth muscle cells. Pathological stimuli-induced smooth muscle cell proliferation, vascular remodeling, and arterial stiffness can be ameliorated by resveratrol as well. In addition, resveratrol also modulates immune cell function, inhibition of immune cell infiltration into the vascular wall, and improves the function of perivascular adipose tissue. All these mechanisms contribute to the protective effects of resveratrol on vascular function and blood pressure in vivo. Sirtuin 1, AMP-activated protein kinase, and estrogen receptors represent the major molecules mediating the vascular effects of resveratrol.

Protective effect of resveratrol on methylglyoxal-induced endothelial dysfunction in aged rats

BACKGROUND

The cardiovascular benefits of resveratrol (RSV) have been well established by previous experimental and clinical studies. The aim of this study was to investigate the effectiveness of RSV administration on the impaired endothelial function induced by methylglyoxal (MGO), and to elucidate the role of endothelial nitric oxide synthase (eNOS) on its protective effect.

METHODS

Aged Wistar rats (80 weeks old, n = 15) were used in this study. The thoracic aorta was isolated and cut into rings for organ culture. Aortic segments of rats were incubated with MGO (420 µM) in the presence or absence of RSV (30 µM) for 4 h (short-term) or 24 h (long-term). Isometric tension studies were performed by an isolated organ bath in response to acetylcholine (ACh, an endothelium-dependent vasodilator) and sodium nitroprusside (SNP, an endothelium-independent vasodilator). Beside, expressions of eNOS and phospho-eNOS (p-eNOS) (Ser 1177) in thoracic aorta rings were evaluated by immunohistochemistry.

RESULTS

Both short-term and long-term MGO incubation significantly inhibited the relaxation response induced by ACh, while the relaxation to SNP was not significantly altered. In addition, eNOS and p-eNOS expressions decreased significantly in arteries incubated with MGO. The impaired endothelial reactivity as well as decreased expressions of eNOS and p-eNOS in MGO-incubated vessels were significantly improved by RSV treatment.

CONCLUSIONS

Endothelium-dependent vasodilatation of the thoracic aorta was significantly inhibited by MGO administration, and RSV may improve vascular endothelial function. The protective effect of RSV against MGO-induced endothelial dysfunction seems to be via increased eNOS expression and activity.

The Effects of Resveratrol in Patients with Cardiovascular Disease and Heart Failure: A Narrative Review

Cardiovascular disease (CVD) is the main cause of death globally and responsible for the second highest number of deaths in Canada. Medical advancements in the treatment of CVD have led to patients living longer with CVD but often progressing to another condition called heart failure (HF). As a result, HF has emerged in the last decade as a major medical concern. Fortunately, various “traditional” pharmacotherapies for HF exist and have shown success in reducing HF-associated mortality. However, to augment the treatment of patients with CVD and/or HF, alternative pharmacotherapies using nutraceuticals have also shown promise in the prevention and treatment of these two conditions. One of these natural compounds considered to potentially help treat HF and CVD and prevent their development is resveratrol. Herein, we review the clinical findings of resveratrol’s ability to be used as an effective treatment to potentially help treat HF and CVD. This will allow us to gain a more fulsome appreciation for the effects of resveratrol in the health outcomes of specific patient populations who have various disorders that constitute CVD.

Vasorelaxant and Antihypertensive Effects That Are Dependent on the Endothelial NO System Exhibited by Rice Bran-Derived Tripeptide

We recently identified a novel, potent antihypertensive peptide, Leu-Arg-Ala (LRA; minimum effective dose = 0.25 mg/kg), from rice bran protein. In this study, we found that LRA potently relaxed mesenteric arteries isolated from spontaneously hypertensive rats (SHRs) (EC₅₀ = 0.1 μM). In contrast, the vasorelaxant activity of each amino acid that constitutes the LRA tripeptide was remarkably attenuated. The LRA-induced vasorelaxant activity was inhibited by N(G)-nitro-l-arginine methyl ester (L-NAME; NO synthase [NOS] inhibitor) but not by an antagonist of bradykinin B2 and Mas receptors or by a phosphoinositide 3-kinase inhibitor. The antihypertensive effect induced after the oral administration of LRA was inhibited by L-NAME. LRA also induced the phosphorylation of endothelial NOS in human umbilical vein endothelial cells. Taken together, LRA may exhibit antihypertensive effects via NO-mediated vasorelaxation. LRA is the first example of a NO-dependent vasorelaxant peptide identified from rice bran protein.

Resveratrol and Its Human Metabolites-Effects on Metabolic Health and Obesity

Resveratrol is one of the most widely studied polyphenols and it has been assigned a plethora of metabolic effects with potential health benefits. Given its low bioavailability and extensive metabolism, clinical studies using resveratrol have not always replicated in vitro observations. In this review, we discuss human metabolism and biotransformation of resveratrol, and reported molecular mechanisms of action, within the context of metabolic health and obesity. Resveratrol has been described as mimicking caloric restriction, leading to improved exercise performance and insulin sensitivity (increasing energy expenditure), as well as having a body fat-lowering effect by inhibiting adipogenesis, and increasing lipid mobilization in adipose tissue. These multi-organ effects place resveratrol as an anti-obesity bioactive of potential therapeutic use.

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.