Cigarette smoke and LDL cooperate in reducing nitric oxide bioavailability in endothelial cells via effects on both eNOS and NADPH oxidase

Comorbidity of Anxiety and Hypertension: Common Risk Factors and Potential Mechanisms

Anxiety is more common in patients with hypertension, and these two conditions frequently coexist. Recently, more emphasis has been placed on determining etiology in patients with comorbid hypertension and anxiety. This review focuses on the common risk factors and potential mechanisms of comorbid hypertension and anxiety. Firstly, we analyze the common risk factors of comorbid hypertension and anxiety including age, smoking, alcohol abuse, obesity, lead, and traffic noise. The specific mechanisms underlying hypertension and anxiety were subsequently discussed, including interleukin (IL)-6 (IL-6), IL-17, reactive oxygen species (ROS), and gut dysbiosis. Increased IL-6, IL-17, and ROS accelerate the development of hypertension and anxiety. Gut dysbiosis leads to hypertension and anxiety by reducing short-chain fatty acids, vitamin D, and 5-hydroxytryptamine (5-HT), and increasing trimethylamine N-oxide (TAMO) and MYC. These shared risk factors and potential mechanisms may provide an effective strategy for treating and preventing hypertension and comorbid anxiety.

Immunometabolism in the pathogenesis of vitiligo

Vitiligo is a common depigmenting skin disorder characterized by the selective loss of melanocytes. Autoimmunity, genetic, environmental, and biochemical etiology have been proposed in vitiligo pathogenesis. However, the exact molecular mechanisms of vitiligo development and progression are unclear, particularly for immunometabolism. Sporadic studies have suggested mitochondrial dysfunction, enhanced oxidative stress, and specific defects in other metabolic pathways can promote dysregulation of innate and adaptive immune responses in vitiligo. These abnormalities appear to be driven by genetic and epigenetic factors modulated by stochastic events. In addition, glucose and lipid abnormalities in metabolism have been associated with vitiligo. Specific skin cell populations are also involved in the critical role of dysregulation of metabolic pathways, including melanocytes, keratinocytes, and tissue-resident memory T cells in vitiligo pathogenesis. Novel therapeutic treatments are also raised based on the abnormalities of immunometabolism. This review summarizes the current knowledge on immunometabolism reprogramming in the pathogenesis of vitiligo and novel treatment options.

Is the insulin necessary for the struggle against oxidative stress in diabetes mellitus type 2: A pilot study

Background/Aim. Hyperglycaemia has a detrimental effect on the progress of micro/macrovascular complications in patients with diabetes mellitus type 2 (T2DM). Additionally, all known complications in T2DM are coupled with oxidative stress developed from different metabolic pathways. The aim of this study was to estimate the quality of glucoregulation and the degree of oxidative stress in T2DM patients depending on the applied therapeutic protocol and assess their correlation with clinical data and crucial biochemical parameters important for the development of diabetes complications. Methods. All included patients were divided into two groups: those treated with oral antidiabetic drugs (OAD) and those treated with oral antidiabetic drugs and insulin (OA-DINS). Thiobarbituric acid reactive substances (TBARS), total sulfhydryl groups (TSH), the activity of superoxide dismutase (SOD), total nitrites (NOx), vascular endothelial growth factor (VEGF), and activities of matrix metalloproteinase 9 (MMP9) were measured, together with lipid profile and routine biochemical parameters. All subjects were analyzed for demographic characteristics and detailed medical history as well as smoking habits and calculated for body mass index (BMI). Results. All patients were uniformly poor glucoregulated and dyslipidemic. SOD activity was decreased, and lipid peroxidation was increased in the OAD group compared to OADINS. Deficient glucoregulation in both the OAD and the OADINS groups did not associate with an oxidative state outcome. In both of these groups, the concentrations of VEGF and MMP9 were significantly higher than in controls. Conclusion. The better antioxidative outcome, expressed with a normalized concentration of TBARS, preserved TSH, and normalized SOD activity in T2DM patients treated with OADINS compared to those treated exclusively with OAD, suggests the need for more careful consideration of earlier insulin introduction into T2DM therapy in order to prevent the development of complications.

Antioxidant properties of anthocyanins and their mechanism of action in atherosclerosis

Atherosclerosis develops due to lipid accumulation in the arterial wall and sclerosis as result of increased hyperlipidemia, oxidative stress, lipid oxidation, and protein oxidation. However, improving antioxidant status through diet may prevent the progression of atherosclerotic cardiovascular disease. It is believed that polyphenol-rich plants contribute to the inverse relationship between fruit and vegetable intake and chronic disease. Anthocyanins are flavonoid polyphenols with antioxidant properties that have been associated with reduced risk of cardiovascular disease. The consumption of anthocyanins increases total antioxidant capacity, antioxidant defense enzymes, and HDL antioxidant properties by several measures in preclinical and clinical populations. Anthocyanins appear to impart antioxidant actions via direct antioxidant properties, as well as indirectly via inducing intracellular Nrf2 activation and antioxidant gene expression. These actions counter oxidative stress and inflammatory signaling in cells present in atherosclerotic plaques, including macrophages and endothelial cells. Overall, anthocyanins may protect against atherosclerosis and cardiovascular disease through their effects on cellular antioxidant status, oxidative stress, and inflammation; however, their underlying mechanisms of action appear to be complex and require further elucidation.

Nicotine promotes vascular calcification via intracellular Ca2+-mediated, Nox5-induced oxidative stress and extracellular vesicle release in vascular smooth muscle cells

Aims

Smokers are at increased risk of cardiovascular events. However, the exact mechanisms through which smoking influences cardiovascular disease resulting in accelerated atherosclerosis and vascular calcification are unknown. The aim of this study was to investigate effects of nicotine on initiation of vascular smooth muscle cell (VSMC) calcification and to elucidate underlying mechanisms.

Methods and results

We assessed vascular calcification of 62 carotid lesions of both smoking and non-smoking patients using ex vivo micro-computed tomography (µCT) scanning. Calcification was present more often in carotid plaques of smokers (n = 22 of 30, 73.3%) compared to non-smokers (n = 11 of 32, 34.3%; P < 0.001), confirming higher atherosclerotic burden. The difference was particularly profound for microcalcifications, which was 17-fold higher in smokers compared to non-smokers. In vitro, nicotine-induced human primary VSMC calcification, and increased osteogenic gene expression (Runx2, Osx, BSP, and OPN) and extracellular vesicle (EV) secretion. The pro-calcifying effects of nicotine were mediated by Ca²⁺-dependent Nox5. SiRNA knock-down of Nox5 inhibited nicotine-induced EV release and calcification. Moreover, pre-treatment of hVSMCs with vitamin K2 ameliorated nicotine-induced intracellular oxidative stress, EV secretion, and calcification. Using nicotinic acetylcholine receptor (nAChR) blockers α-bungarotoxin and hexamethonium bromide, we found that the effects of nicotine on intracellular Ca²⁺ and oxidative stress were mediated by α7 and α3 nAChR. Finally, we showed that Nox5 expression was higher in carotid arteries of smokers and correlated with calcification levels in these vessels.

Conclusion

In this study, we provide evidence that nicotine induces Nox5-mediated pro-calcific processes as novel mechanism of increased atherosclerotic calcification. We identified that activation of α7 and α3 nAChR by nicotine increases intracellular Ca²⁺ and initiates calcification of hVSMCs through increased Nox5 activity, leading to oxidative stress-mediated EV release. Identifying the role of Nox5-induced oxidative stress opens novel avenues for diagnosis and treatment of smoking-induced cardiovascular disease.

Digestive n-6 Lipid Oxidation, a Key Trigger of Vascular Dysfunction and Atherosclerosis in the Western Diet: Protective Effects of Apple Polyphenols

SCOPE

A main risk factor of atherosclerosis is a Western diet (WD) rich in n-6 polyunsaturated fatty acids (PUFAs) sensitive to oxidation. Their oxidation can be initiated by heme iron of red meat leading to the formation of 4-hydroxy-2-nonenal (4-HNE), a cytotoxic aldehyde. An increased 4-HNE production is implicated in endothelial dysfunction and atherosclerosis. By contrast, a diet rich in proanthocyanidins reduces oxidative stress and arterial diseases. This study evaluates the effects of a WD on vascular integrity in ApolipoproteinE (ApoE-/- ) mice and the protective capacity of apple extract and puree rich in antioxidant proanthocyanidins.

METHODS AND RESULTS

ApoE-/- mice are fed during 12 weeks with a WD with or without n-6 PUFAs. Moreover, two WD + n-6 PUFAs groups are supplemented with apple puree or phenolic extract. An increase in digestive 4-HNE production associated with a rise in plasmatic 4-HNE and oxidized LDL concentrations is reported. Oxidizable n-6 PUFAs consumption is associated with a worsened endothelial dysfunction and atherosclerosis. Interestingly, supplementations with apple polyphenol extract or puree prevented these impairments while reducing oxidative stress.

CONCLUSION

n-6 lipid oxidation during digestion may be a key factor of vascular impairments. Nevertheless, an antioxidant strategy can limit 4-HNE formation during digestion and thus durably protect vascular function.

Lipid Peroxidation in Atherosclerotic Cardiovascular Diseases

Significance: Atherosclerotic cardiovascular diseases (ACVDs) continue to be a primary cause of mortality worldwide in adults aged 35-70 years, occurring more often in countries with lower economic development, and they constitute an ever-growing global burden that has a considerable socioeconomic impact on society. The ACVDs encompass diverse pathologies such as coronary artery disease and heart failure (HF), among others. Recent Advances: It is known that oxidative stress plays a relevant role in ACVDs and some of its effects are mediated by lipid oxidation. In particular, lipid peroxidation (LPO) is a process under which oxidants such as reactive oxygen species attack unsaturated lipids, generating a wide array of oxidation products. These molecules can interact with circulating lipoproteins, to diffuse inside the cell and even to cross biological membranes, modifying target nucleophilic sites within biomolecules such as DNA, lipids, and proteins, and resulting in a plethora of biological effects. Critical Issues: This review summarizes the evidence of the effect of LPO in the development and progression of atherosclerosis-based diseases, HF, and other cardiovascular diseases, highlighting the role of protein adduct formation. Moreover, potential therapeutic strategies targeted at lipoxidation in ACVDs are also discussed. Future Directions: The identification of valid biomarkers for the detection of lipoxidation products and adducts may provide insights into the improvement of the cardiovascular risk stratification of patients and the development of therapeutic strategies against the oxidative effects that can then be applied within a clinical setting.

Support for increased cardiovascular risk in non-segmental vitiligo among Egyptians: A hospital-based, case-control study

BACKGROUND

Data have been accumulating in the past few years that identify vitiligo as a disorder with systemic implications.

RESULTS AND METHODS

In this hospital-based, cross-sectional, case-control study, 50 patients with non-segmental vitiligo and 50 age- and sex-matched controls underwent analysis of serum lipid profile, oxidative stress biomarkers and carotid duplex. Hydrogen peroxide (H₂ O₂ ) and malondialdehyde (MDA) were significantly higher in patients than controls (p-value < .001, <.001, respectively); on the other hand, total antioxidant capacity (TAC) was significantly lower in patients than controls (p-value = .001). A significantly higher percentage of patients had hypercholesterolemia and borderline high, high or very high levels of LDL-C, compared to controls (p-value = .001 and .001, respectively). Atherosclerotic plaques and increased common carotid intima media thickness were significantly detected in patients versus controls.

DISCUSSION

Results of the present study suggest that a subset of patients with vitiligo are at a higher risk of developing dyslipidemia and atherosclerosis, which might increase their future risk for the development of cardiovascular disease. Confirmation of these findings would subsequently influence investigative and the treatment strategies in the management plan of vitiligo patients in the near future.

SIGNIFICANCE

Vitiligo patients might be at a higher risk of developing dyslipidemia and atherosclerosis, which might increase their risk for the development of cardiovascular disease necessitating prophylactic measures to improve prognosis. Our results might influence the investigative and treatment strategies in the management plan of vitiligo patients in the near future.

Cardiovascular bioimaging of nitric oxide: Achievements, challenges, and the future

Nitric oxide (NO) is a ubiquitous, volatile, cellular signaling molecule that operates across a wide physiological concentration range (pM-µM) in different tissues. It is a highly diffusible messenger and intermediate in various metabolic pathways. NO plays a pivotal role in maintaining optimum cardiovascular function, particularly by regulating vascular tone and blood flow. This review highlights the need for accurate, real-time bioimaging of NO in clinical diagnostic, therapeutic, monitoring, and theranostic applications within the cardiovascular system. We summarize electrochemical, optical, and nanoscale sensors that allow measurement and imaging of NO, both directly and indirectly via surrogate measurements. The physical properties of NO render it difficult to accurately measure in tissues using direct methods. There are also significant limitations associated with the NO metabolites used as surrogates to indirectly estimate NO levels. All these factors added to significant variability in the measurement of NO using available methodology have led to a lack of sensors and imaging techniques of clinical applicability in relevant vascular pathologies such as atherosclerosis and ischemic heart disease. Challenges in applying current methods to biomedical and clinical translational research, including the wide physiological range of NO and limitations due to the characteristics and toxicity of the sensors are discussed, as are potential targets and modifications for future studies. The development of biocompatible nanoscale sensors for use in combination with existing clinical imaging modalities provides a feasible opportunity for bioimaging NO within the cardiovascular system.

Immune-Inflammation in Atherosclerosis: A New Twist in an Old Tale

Background and Objective:

Atherosclerosis, a chronic and progressive inflammatory disease, is triggered by the activation of endothelial cells followed by infiltration of innate and adaptive immune cells including monocytes and T cells in arterial walls. Major populations of T cells found in human atherosclerotic lesions are antigen-specific activated CD4+ effectors and/or memory T cells from Th1, Th17, Th2 and Treg subsets. In this review, we will discuss the significance of T cell orchestrated immune inflammation in the development and progression of atherosclerosis.

Discussion:

Pathogen/oxidative stress/lipid induced primary endothelial wound cannot develop to a full-blown atherosclerotic lesion in the absence of chronically induced inflammation. While the primary inflammatory response might be viewed as a lone innate response, the persistence of such a profound response over time must be (and is) associated with diverse local and systemic T cell responses. The interplay between T cells and innate cells contributes to a phenomenon called immuneinflammation and has an impact on the progression and outcome of the lesion. In recent years immuneinflammation, an old term, has had a comeback in connecting the puzzle pieces of chronic inflammatory diseases.

Conclusion:

Taking one-step back and looking from afar at the players of immune-inflammation may help us provide a broader perspective of these complicated interactions. This may lead to the identification of new drug targets and the development of new therapies as well as preventative measures.

Mulberry Extract Attenuates Endothelial Dysfunction through the Regulation of Uncoupling Endothelial Nitric Oxide Synthase in High Fat Diet Rats

Dyslipidemia is associated with endothelial dysfunction, which is linked to nitric oxide (NO) biology. The coupling of endothelial NO synthase with cofactors is a major step for NO release. This study is aimed to investigate the vascular pharmacology effects of mulberry in rat thoracic aorta and human vascular endothelial cells. In vitro, we investigated the protective effects of the mulberry extract and its main component cyanidin-3-rutinoside (C-3-R), against oxidized low-density lipoprotein (ox-LDL)-induced endothelial nitric oxide synthase (eNOS) uncoupling. Whereas ox-LDL significantly decreased NO levels in endothelial cells, mulberry extract, and C-3-R significantly recovered NO levels and phospho-eNOS Thr495 and Ser1177 expression. In vivo, mulberry was administered to 60% of high-fat diet (w/w)-fed Sprague Dawley (SD) rats for six weeks, in which endothelium-dependent relaxations were significantly improved in organ bath studies and isometric tension recordings. Consistently, aortic expressions of phospho-eNOS and nitrotyrosine were increased. Mulberry also raised serum NO levels, increased phosphorylation of eNOS, and reduced nitrotyrosine and intracellular reactive oxygen species (ROS) in aortas, showing that mulberry preserves endothelium-dependent relaxation in aortas from high-fat diet rats. We suggest that this effect is mediated through enhanced NO bioavailability, in which the regulation of ROS and its reduced eNOS uncoupling are involved.

In times of tobacco-free nicotine consumption: The influence of nicotine on vascular calcification

BACKGROUND

Smoking remains the most important avoidable cause of global mortality. Even though the number of cigarette smokers declines in first world countries, the uses of alternative nicotine delivery products increase and may even surpass the sells of cigarettes. In this light, the explicit role of nicotine in the development of cardiovascular diseases should be elucidated.

OBJECTIVES

This narrative review attempts to connect current literature about possible effects of nicotine on the environment of the vasculature to the pathogenesis of vascular calcification, focusing on the tunica media of the vessel wall.

METHODS

For this review, papers found on Pubmed and Medline until December 2018 by searching for the keywords nicotine, vascular calcification, oxidative stress, osteoblastic transdifferentiation and matrix degradation were considered.

RESULTS

Nicotine creates an environment that probably facilitates and maybe even induces osteogenic transdifferentiation of VSMC by inflammation, endothelial dysfunction and reactive oxygen species. This process is believed to be a key event in calcification of the tunica media of the vessel wall. Furthermore, nicotine could lead to the formation of nucleation sites for hydroxyapatite by facilitating matrix vesicles and extracellular matrix degradation.

CONCLUSIONS

There is a growing body of evidence implicating that nicotine alone could impair vascular function and lead to vascular calcification. Further research is necessary to elucidate the explicit influence of nicotine on arteriosclerosis.

Passive Smoking Exacerbates Nicotinamide-Adenine Dinucleotide Phosphate Oxidase Isoform 2-Induced Oxidative Stress and Arterial Dysfunction in Children with Persistent Allergic Rhinitis

OBJECTIVE

To characterize nicotinamide-adenine dinucleotide phosphate oxidase isoform 2 (NOX2), oxidative stress, and endothelial function in children with and without allergic rhinitis and to ascertain the effect of passive smoke exposure on these factors, because there is an established association between allergic rhinitis and increased cardiovascular risk in adults.

METHODS

We recruited 130 children-65 with persistent allergic rhinitis and 65 healthy controls. A cross-sectional study was performed to compare endothelial function by flow-mediated dilation, blood levels of isoprostanes, serum activity of soluble NOX2-dp (sNOX2-dp), and nitric oxide bioavailability, in these 2 groups of children. Serum cotinine levels were assessed to measure exposure to passive smoking.

RESULTS

Compared with healthy controls, children with persistent allergic rhinitis had significantly higher sNOX2-dp and isoprostanes levels, lower flow-mediated dilation, and reduced nitric oxide bioavailability. Multivariable linear regression analysis showed that flow-mediated dilation, isoprostanes, and cotinine were independently associated with sNOX2-dp levels. Of note, sNOX2-dp serum levels were significantly higher in children with allergic rhinitis exposed to smoke, as compared with unexposed children with allergic rhinitis.

CONCLUSION

NOX2 is activated in children with persistent allergic rhinitis and passive smoke exposure exacerbates this effect. We further demonstrate an association between higher sNOX2-dp and oxidative stress and endothelial dysfunction.

A Phenotype of Primary Open-angle Glaucoma With Systemic Vasospasm

PURPOSE

Primary open-angle glaucoma (POAG) patients constitute a heterogenous group. Identification of phenotypic subtypes among these patients may provide a deeper understanding of the disease and aid associations with genotypes. We describe a phenotype of POAG patients associated with a constellation of systemic disorders; patients with this phenotype seem to be vulnerable to optic nerve damage at low intraocular pressures.

MATERIALS AND METHODS

In this retrospective study, we evaluated the medical records of active Jules Stein Eye Institute glaucoma patients from January 1996 to 2017 and included subjects with POAG, acquired pits of the optic nerve (APON), and at least one of the following: systolic blood pressure persistently ≤100 mm Hg, history of migraine headaches or migraine variant, and the Raynaud syndrome.

RESULTS

Of 87 patients (125 eyes) with APON, 37 patients (55 eyes) met the study criteria. In total, 34 patients were female (92%). The median age at the time of diagnosis was 55 years. Nineteen patients (73%) had low systolic blood pressures, same number had Raynaud syndrome, and 25 (68%) had a history of migraine.

CONCLUSIONS

We describe a POAG subtype with APON and systemic vascular instability, predominantly female in their sixth decade of life who demonstrate progressive glaucomatous visual field damage at low intraocular pressure. We suggest that this clinical picture represents an important phenotype of POAG, and that identification and further study of it will help guide diagnosis and development of individualized treatments.

Vascular component of hand-arm vibration syndrome: a 22-year follow-up study

BACKGROUND

Vibration-induced white finger (VWF) is often assessed using the Stockholm Workshop Scale (SWS) and cold challenge plethysmography. However, long-term longitudinal studies using both methods are scarce.

AIMS

To study the long-term course and prognostic factors of VWF assessed with the SWS and photoplethysmography (PPG), and to examine the effects of lifestyle on PPG score, regardless of VWF status.

METHODS

Forty male construction workers were examined with a test battery and clinical examination in 1994 and 2016/17.

RESULTS

At baseline, the sample comprised 27 workers with, and 13 without, symptoms of hand-arm vibration syndrome (HAVS). Thirty-five workers reported vibration exposure during follow-up. The mean age of the workers was 60 years (45-78) at follow-up. The paired t-test showed that PPG scores deteriorated from 1994 to 2017 in the 27 workers with HAVS in 1994 (mean difference 2.7 min, 95% confidence interval (CI) 0.2-5.2). However, there was no statistically significant change in SWS scores in these workers over time. Smoking and age were associated with PPG score deterioration. Vibration exposure during follow-up predicted SWS score deterioration: 1000 h of exposure predicted a deterioration stage of 0.09 (95% CI 0.03-0.16). Analysis of all 40 workers showed that 2017 PPG scores were associated with positive serum cotinine and self-reported smoking during follow-up.

CONCLUSIONS

Whereas age and smoking predicted a PPG deterioration, continued vibration exposure predicted worsening of white finger symptoms. The association of PPG score and smoking should be considered in diagnostic and prognostic factor evaluations.

Dietary docosahexaenoic acid supplementation prevents the formation of cholesterol oxidation products in arteries from orchidectomized rats

Testosterone deficiency has been correlated with increased cardiovascular diseases, which in turn has been associated with increased oxidative stress. Several studies have considered cholesterol oxidation products (COPs) as oxidative stress biomarkers, since some of them play pro-oxidant and pro-inflammatory roles. We have previously described the cardioprotective effects of a dosahexaenoic acid (DHA) supplemented diet on the aortic and mesenteric artery function of orchidectomized rats. The aim of this study was to investigate whether impaired gonadal function alters the formation of COPs, as well as the potential preventive role of a DHA-supplemented diet on that effect. For this purpose, aortic and mesenteric artery segments obtained from control and orchidectomized rats, fed with a standard or supplemented with DHA, were used. The content of the following COPs: 7α-hydroxycholesterol, 7β-hydroxycholesterol, 7-ketocholesterol, 5,6α-epoxycholesterol, 5,6β-epoxycholesterol, cholestanetriol and 25-hydroxycholesterol, were analyzed by gas chromatography. The results showed that orchidectomy increased the formation of COPs in arteries from orchidectomized rats, which may participate in the orchidectomy-induced structural and functional vascular alterations already reported. The fact that the DHA-supplemented diet prevented the orchidectomy-induced COPs increase confirms the cardiovascular protective actions of DHA, which could be of special relevance in mesenteric arterial bed, since it importantly controls the systemic vascular resistance.

Oxidative Stress in Atherosclerosis

PURPOSE OF REVIEW

Atherosclerosis is now considered a chronic inflammatory disease. Oxidative stress induced by generation of excess reactive oxygen species has emerged as a critical, final common mechanism in atherosclerosis. Reactive oxygen species (ROS) are a group of small reactive molecules that play critical roles in the regulation of various cell functions and biological processes. Although essential for vascular homeostasis, uncontrolled production of ROS is implicated in vascular injury. Endogenous anti-oxidants function as checkpoints to avoid these untoward consequences of ROS, and an imbalance in the oxidant/anti-oxidant mechanisms leads to a state of oxidative stress. In this review, we discuss the role of ROS and anti-oxidant mechanisms in the development and progression of atherosclerosis, the role of oxidized low-density lipoprotein cholesterol, and highlight potential anti-oxidant therapeutic strategies relevant to atherosclerosis.

RECENT FINDINGS

There is growing evidence on how traditional risk factors translate into oxidative stress and contribute to atherosclerosis. Clinical trials evaluating anti-oxidant supplements had failed to improve atherosclerosis. Current studies focus on newer ROS scavengers that specifically target mitochondrial ROS, newer nanotechnology-based drug delivery systems, gene therapies, and anti-miRNAs. Synthetic LOX-1 modulators that inhibit the effects of Ox-LDL are currently in development. Research over the past few decades has led to identification of multiple ROS generating systems that could potentially be modulated in atherosclerosis. Therapeutic approaches currently being used for atheroslcerotic vascular disease such as aspirin, statins, and renin-angiotensin system inhibitors exert a pleiotropic antioxidative effects. There is ongoing research to identify novel therapeutic modalities to selectively target oxidative stress in atherosclerosis.

Impact of Oxidative Stress on the Heart and Vasculature: Part 2 of a 3-Part Series

Vascular disease and heart failure impart an enormous burden in terms of global morbidity and mortality. Although there are many different causes of cardiac and vascular disease, most causes share an important pathological mechanism: oxidative stress. In the failing heart, oxidative stress occurs in the myocardium and correlates with left ventricular dysfunction. Reactive oxygen species (ROS) negatively affect myocardial calcium handling, cause arrhythmia, and contribute to cardiac remodeling by inducing hypertrophic signaling, apoptosis, and necrosis. Similarly, oxidative balance in the vasculature is tightly regulated by a wealth of pro- and antioxidant systems that orchestrate region-specific ROS production and removal. Reactive oxygen species also regulate multiple vascular cell functions, including endothelial and smooth muscle cell growth, proliferation, and migration; angiogenesis; apoptosis; vascular tone; host defenses; and genomic stability. However, excessive levels of ROS promote vascular disease through direct and irreversible oxidative damage to macromolecules, as well as disruption of redox-dependent vascular wall signaling processes.

Roles of Vascular Oxidative Stress and Nitric Oxide in the Pathogenesis of Atherosclerosis

Major reactive oxygen species (ROS)–producing systems in vascular wall include NADPH (reduced form of nicotinamide adenine dinucleotide phosphate) oxidase, xanthine oxidase, the mitochondrial electron transport chain, and uncoupled endothelial nitric oxide (NO) synthase. ROS at moderate concentrations have important signaling roles under physiological conditions. Excessive or sustained ROS production, however, when exceeding the available antioxidant defense systems, leads to oxidative stress. Animal studies have provided compelling evidence demonstrating the roles of vascular oxidative stress and NO in atherosclerosis. All established cardiovascular risk factors such as hypercholesterolemia, hypertension, diabetes mellitus, and smoking enhance ROS generation and decrease endothelial NO production. Key molecular events in atherogenesis such as oxidative modification of lipoproteins and phospholipids, endothelial cell activation, and macrophage infiltration/activation are facilitated by vascular oxidative stress and inhibited by endothelial NO. Atherosclerosis develops preferentially in vascular regions with disturbed blood flow (arches, branches, and bifurcations). The fact that these sites are associated with enhanced oxidative stress and reduced endothelial NO production is a further indication for the roles of ROS and NO in atherosclerosis. Therefore, prevention of vascular oxidative stress and improvement of endothelial NO production represent reasonable therapeutic strategies in addition to the treatment of established risk factors (hypercholesterolemia, hypertension, and diabetes mellitus).

NADPH oxidase (NOX) 1 mediates cigarette smoke-induced superoxide generation in rat vascular smooth muscle cells

Smoking is a well-established risk factor for cardiovascular diseases. Oxidative stress is one of the common etiological factors, and NADPH oxidase (NOX) has been suggested as a potential mediator of oxidative stress. In this study, cigarette smoke (CS)-induced superoxide production was characterized in vascular smooth muscle cells (VSMC). CS was prepared in forms of cigarette smoke extract (CSE) and total particulate matter (TPM). Several molecular probes for reactive oxygen species were trialed, and dihydroethidium (DHE) and WST-1 were chosen for superoxide detection considering the autofluorescence, light absorbance, and peroxidase inhibitory activity of CS. Both CSE and TPM generated superoxide in a VSMC culture system by stimulating cells to produce superoxide and by directly producing superoxide in the aqueous solution. NOX, specifically NOX1 was found to be an important cellular source of superoxide through experiments with the NOX inhibitors diphenyleneiodonium (DPI) and VAS2870 as well as isoform-specific NOX knockdown. NOX inhibitors and the superoxide dismutase mimetic TEMPOL reduced the cytotoxicity of CSE, thus suggesting the contribution of NOX1-derived superoxide to cytotoxicity. Since NOX1 is known to mediate diverse pathological processes in the vascular system, NOX1 may be a critical effector of cardiovascular toxicity caused by smoking.

Serum levels of nitric oxide and cytokines in smokers at the beginning and after 4months of treatment for smoking cessation

INTRODUCTION

Nitric oxide (NO) modulates inflammatory reactions, having beneficial or toxic effects depending on the concentration. Its elevation can cause proinflammatory effects amplifying the inflammatory process with the participation of cytokines. Smoking has a negative impact on health and is considered one of the risk factors that influence disease development facilitating inflammatory processes.

AIM

To compare the serum concentration of NO and cytokines in smokers at baseline and after 4months of abstinence treatment.

METHODS

Blood samples which were collected to obtain the serum, at baseline and after 4months, were stored at -80°C until analysis. NO was measured by the total dose of nitrite determined by the Greiss method. CBA was the used technique to determine the concentration of cytokines in supernatants serum. The initial and final results of NO, TNF-α, IL-1, IL-6, IL-8, IL-10 and IL-12 that remained after 4months treatment were compared. Wilcoxon test was used to compare the data and Spearman test for correlations between NO and other variables. A significance level of p<0.05 was adopted.

RESULTS

The analysis of NO observed a significant reduction (p=0.001) of the initial median value of 18.80 (3.55-80.01) μmol/L to 8.10 (2.85-14.97) μmol/L after 4months of treatment. There were no significant differences in cytokines from baseline to the end of treatment.

CONCLUSION

The results may not mean harm to the body, but an adaptive process, decreasing the metabolism of abstinents due to the reduction of the use of nicotine.

Icariin improves eNOS/NO pathway to prohibit the atherogenesis of apolipoprotein E-null mice

Impaired endothelial nitric oxide synthase (eNOS)/nitric oxide (NO) pathway induces atherogenesis. The present study examined whether icariin improves the eNOS/NO pathway to prohibit the atherogenesis of apolipoprotein E-null (ApoE^-/-) mice. In vitro, primary human umbilical vein endothelial cells (HUVECs) were randomly divided into 7 groups: control; vehicle; icariin 10; lyphosphatidylcholine (LPC) group; LPC + icariin 1; LPC + icariin 3; and LPC + icariin 10. In vivo, 80 mice were separated randomly into 4 groups (n = 20): control, ApoE^-/-, ApoE^-/- + icariin 10, and ApoE^-/- + icariin 30. ApoE^-/- mice had significantly more atherosclerosis in the aortic root together with increased aortic ROS production, body mass, plasma triglyceride (TG) and total cholesterol (TC) concentration, decreased aortic eNOS expression, and plasma NO concentration. LPC (10 μg/mL) treatment induced a big decline in NO level in the conditioned medium and eNOS expression, and an increase in intracellular reactive oxygen species (ROS) production in HUVECs. Icariin treatment decreased atherogenesis, ROS production, body mass, plasma TG concentration, and plasma TC concentration, and increased NO concentration and eNOS expression. These findings suggested icariin could improve eNOS/NO-pathway to prohibit the atherogenesis of apolipoprotein E-null mice by restraining oxidative stress.

NADPH oxidase and the cardiovascular toxicity associated with smoking

Smoking is one of the most serious but preventable causes of cardiovascular disease (CVD). Key aspects of pathological process associated with smoking include endothelial dysfunction, a prothrombotic state, inflammation, altered lipid metabolism, and hypoxia. Multiple molecular events are involved in smokinginduced CVD. However, the dysregulations of reactive oxygen species (ROS) generation and metabolism mainly contribute to the development of diverse CVDs, and NADPH oxidase (NOX) has been established as a source of ROS responsible for the pathogenesis of CVD. NOX activation and resultant ROS production by cigarette smoke (CS) treatment have been widely observed in isolated blood vessels and cultured vascular cells, including endothelial and smooth muscle cells. NOX-mediated oxidative stress has also been demonstrated in animal studies. Of the various NOX isoforms, NOX2 has been reported to mediate ROS generation by CS, but other isoforms were not tested thoroughly. Of the many CS constituents, nicotine, methyl vinyl ketone, and α,β-unsaturated aldehydes, such as, acrolein and crotonaldehyde, appear to be primarily responsible for NOX-mediated cytotoxicity, but additional validation will be needed. Human epidemiological studies have reported relationships between polymorphisms in the CYBA gene encoding p22phox, a catalytic subunit of NOX and susceptibility to smoking-related CVDs. In particular, G allele carriers of A640G and -930^A/G polymorphisms were found to be vulnerable to smoking-induced cardiovascular toxicity, but results for C242T studies are conflicting. On the whole, evidence implicates the etiological role of NOX in smoking-induced CVD, but the clinical relevance of NOX activation by smoking and its contribution to CVD require further validation in human studies. A detailed understanding of the role of NOX would be helpful to assess the risk of smoking to human health, to define high-risk subgroups, and to develop strategies to prevent or treat smoking-induced CVD.

The p-ERK-p-c-Jun-cyclinD1 pathway is involved in proliferation of smooth muscle cells after exposure to cigarette smoke extract

An epidemiological survey has shown that smoking is closely related to atherosclerosis, in which excessive proliferation of vascular smooth muscle cells (SMCs) plays a key role. To investigate the mechanism underlying this unusual smoking-induced proliferation, cigarette smoke extract (CSE), prepared as smoke-bubbled phosphate-buffered saline (PBS), was used to induce effects mimicking those exerted by smoking on SMCs. As assessed by Cell Counting Kit-8 detection (an improved MTT assay), SMC viability increased significantly after exposure to CSE. Western blot analysis demonstrated that p-ERK, p-c-Jun, and cyclinD1 expression increased. When p-ERK was inhibited using U0126 (inhibitor of p-ERK), cell viability decreased and the expression of p-c-Jun and cyclinD1 was reduced accordingly, suggesting that p-ERK functions upstream of p-c-Jun and cyclinD1. When a c-Jun over-expression plasmid was transfected into SMCs, the level of cyclinD1 in these cells increased. Moreover, when c-Jun was knocked down by siRNA, cyclinD1 levels decreased. In conclusion, our findings indicate that the p-ERK-p-c-Jun-cyclinD1 pathway is involved in the excessive proliferation of SMCs exposed to CSE.

Association of digital vascular function with cardiovascular risk factors: a population study

OBJECTIVES

Vasodilation of the peripheral arteries during reactive hyperaemia depends in part on release of nitric oxide from endothelial cells. Previous studies mainly employed a fingertip tonometric device to derive pulse wave amplitude (PWA) and PWA hyperaemic changes. An alternative approach is based on photoplethysmography (PPG). We sought to evaluate the correlates of digital PPG PWA hyperaemic responses as a measure of peripheral vascular function.

DESIGN

The Flemish Study on Environment, Genes and Health Outcomes (FLEMENGHO) is a population-based cohort study.

SETTING

Respondents were examined at one centre in northern Belgium.

PARTICIPANTS

For this analysis, our sample consisted of 311 former participants (53.5% women; mean age 52.6 years; 43.1% hypertensive), who were examined from January 2010 until March 2012 (response rate 85.1%).

PRIMARY OUTCOME MEASURES

Using a fingertip PPG device, we measured digital PWA at baseline and at 30 s intervals for 4 min during reactive hyperaemia induced by a 5 min forearm cuff occlusion. We performed stepwise regression to identify correlates of the hyperaemic response ratio for each 30 s interval after cuff deflation.

RESULTS

The maximal hyperaemic response was detected in the 30-60 s interval. The explained variance for the PPG PWA ratio ranged from 9.7% at 0-30 s interval to 22.5% at 60-90 s time interval. The hyperaemic response at each 30 s interval was significantly higher in women compared with men (p≤0.001). The PPG PWA changes at 0-90 s intervals decreased with current smoking (p≤0.0007) and at 0-240 s intervals decreased with higher body mass index (p≤0.035). These associations with sex, current smoking and body mass index were mutually independent.

CONCLUSIONS

Our study is the first to implement the new PPG technique to measure digital PWA hyperaemic changes in a general population. Hyperaemic response, as measured by PPG, is inversely associated with traditional cardiovascular risk factors such as male sex, smoking and obesity.

Anti-inflammatory properties of kaempferol via its inhibition of aldosterone signaling and aldosterone-induced gene expression

Osteopontin (OPN), also called cytokine Eta-1, is a pro-inflammatory cytokine. Recent studies have shown that aldosterone increases OPN gene expression in endothelial cells. As a flavonoid compound, kaempferol has potent anti-inflammatory properties, but whether kaempferol regulates aldosterone signaling and aldosterone-induced gene expression is still unknown. Human umbilical vein endothelial cells (HUVECs) were pretreated with kaempferol (0, 1, 3, or 10 μmol/L) for 1 h prior to exposure to aldosterone (10−6 mol/L) for 24 h. Aldosterone induced generation of reactive oxygen species; OPN and cluster of differentiation 44 gene expression; phospho-p38 MAPK and NF-κB binding activity. The effect of aldosterone was abrogated by kaempferol and spironolactone (10−6 mol/L). The present results suggest that kaempferol exerts its anti-inflammatory properties via its inhibition of aldosterone signaling and aldosterone-induced gene expression in HUVECs.

Isolation of functional human endothelial cells from small volumes of umbilical cord blood

Endothelial cells (ECs) isolated from endothelial progenitor cells in blood have great potential as a therapeutic tool to promote vasculogenesis and angiogenesis and treat cardiovascular diseases. However, current methods to isolate ECs are limited by a low yield with few colonies appearing during isolation. In order to utilize blood-derived ECs for therapeutic applications, a simple method is needed that can produce a high yield of ECs from small volumes of blood without the addition of animal-derived products. For the first time, we show that human ECs can be isolated without the prior separation of blood components through the technique of diluted whole blood incubation (DWBI) utilizing commercially available human serum. We isolated ECs from small volumes of blood (~10 mL) via DWBI and characterized them with flow cytometry, immunohistochemistry, and uptake of DiI-labeled acetylated low density lipoprotein (DiI-Ac-LDL). These ECs are functional as demonstrated by their ability to form tubular networks in Matrigel, adhere and align with flow under physiological fluid shear stress, and produce increased nitric oxide under fluid flow. An average of 7.0 ± 2.5 EC colonies that passed all functional tests described above were obtained per 10 mL of blood as compared to only 0.3 ± 0.1 colonies with the traditional method based on density centrifugation. The time until first colony appearance was 8.3 ± 1.2 days for ECs isolated with the DWBI method and 12 ± 1.4 days for ECs isolated with the traditional isolation method. A simplified method, such as DWBI, in combination with advances in isolation yield could enable the use of blood-derived ECs in clinical practice.

Oxidative stress in vascular disease and its pharmacological prevention

Cardiovascular risk factors lead to enhanced production of reactive oxygen species (ROS) generated by NADPH oxidase, xanthine oxidase (XO), the mitochondrial electron-transport chain (ETC), and dysfunctional endothelial nitric oxide synthase (eNOS). When the capacity of antioxidant defense systems [e.g., superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), heme oxygenase (HO), paraoxonase (PON)] is exceeded, this results in oxidative stress, which can promote atherogenesis. Therefore, pharmacological means to prevent oxidative stress are of major therapeutic interest. Some established drugs and novel therapeutic approaches can prevent oxidative stress and, presumably, vascular disease. These include angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor type 1 (AT1 receptor) blockers (ARBs), statins, nebivolol, pentaerithrityl tetranitrate (PETN), resveratrol, and mitochondria-targeted antioxidants. Molecular mechanisms involved in the induction of oxidative stress under pathological conditions as well as pharmacological approaches (and their molecular mechanisms) are summarized in this review.

Uncoupling of endothelial NO synthase in atherosclerosis and vascular disease

Nitric oxide (NO) produced by the endothelial NO synthase (eNOS) is an antihypertensive, antithrombotic and anti-atherosclerotic molecule. Hypercholesterolemia leads to a reduction in vascular NO bioavailability. This is attributed to a dysfunction of the eNOS enzyme and a reduced eNOS activity. NADPH oxidase-mediated oxidative stress leads to oxidation of tetrahydrobiopterin (BH4), the essential cofactor of eNOS. In BH4 deficiency, oxygen reduction uncouples from NO synthesis, thereby converting eNOS to a superoxide-producing enzyme. As a consequence of eNOS uncoupling, NO production is reduced and the pre-existing oxidative stress is enhanced, which contribute significantly to atherogenesis. Therefore, pharmacological approaches that prevent eNOS uncoupling and enhance eNOS activity are of therapeutic interest. Angiotensin-converting enzyme inhibitors, AT1 receptor blockers, statins, nebivolol and resveratrol have been shown to reverse eNOS uncoupling and to stimulate eNOS activity concurrently. Molecular mechanisms of the aforementioned drugs/compounds on eNOS functionality is summarized and discussed in this review.

A model of interaction between nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and apocynin analogues by docking method

Some apocynin analogues have exhibited outstanding inhibition to NADPH oxidase. In this study, the key interactions between apocynin analogues and NADPH oxidase were analyzed by the docking method. The potential active site was first identified by the SiteID program combining with the key residue CYS378. Afterwards, the compounds in the training set were docked into NADPH oxidase (1K4U) under specific docking constraints to discuss the key interactions between ligands and the receptor. These key interactions were then validated by the consistence between the docking result and the experimental result of the test set. The result reveals that the Pi interaction between apocynin analogues and NADPH oxidase has a direct contribution to inhibition activities, except for H-bond formation and docking score. The key interactions might be valuable to discover and screen apocynin analogues as potent inhibitors of NADPH oxidase.