Nitric oxide synthase in atherosclerosis and vascular injury: insights from experimental gene therapy

Nitric oxide releasing nanofiber stimulates revascularization in response to ischemia via cGMP-dependent protein kinase

Nitric oxide (NO) promotes angiogenesis via various mechanisms; however, the effective transmission of NO in ischemic diseases is unclear. Herein, we tested whether NO-releasing nanofibers modulate therapeutic angiogenesis in an animal hindlimb ischemia model. Male wild-type C57BL/6 mice with surgically-induced hindlimb ischemia were treated with NO-releasing 3-methylaminopropyltrimethoxysilane (MAP3)-derived or control (i.e., non-NO-releasing) nanofibers, by applying them to the wound for 20 min, three times every two days. The amount of NO from the nanofiber into tissues was assessed by NO fluorometric assay. The activity of cGMP-dependent protein kinase (PKG) was determined by western blot analysis. Perfusion ratios were measured 2, 4, and 14 days after inducing ischemia using laser doppler imaging. On day 4, Immunohistochemistry (IHC) with F4/80 and gelatin zymography were performed. IHC with CD31 was performed on day 14. To determine the angiogenic potential of NO-releasing nanofibers, aorta-ring explants were treated with MAP3 or control fiber for 20 min, and the sprout lengths were examined after 6 days. As per either LDPI (Laser doppler perfusion image) ratio or CD31 capillary density measurement, angiogenesis in the ischemic hindlimb was improved in the MAP3 nanofiber group; further, the total nitrate/nitrite concentration in the adduct muscle increased. The number of macrophage infiltrations and matrix metalloproteinase-9 (MMP-9) activity decreased. Vasodilator-stimulated phosphoprotein (VASP), one of the major substrates for PKG, increased phosphorylation in the MAP3 group. MAP3 nanofiber or NO donor SNAP (s-nitroso-n-acetyl penicillamine)-treated aortic explants showed enhanced sprouting in an ex vivo aortic ring assay, which was partially abrogated by KT5823, a potent inhibitor of PKG. These findings suggest that the novel NO-releasing nanofiber, MAP3 activates PKG and promotes therapeutic angiogenesis in response to hindlimb ischemia.

Nanoparticle endothelial delivery of PGC-1α attenuates hypoxia-induced pulmonary hypertension by attenuating EndoMT-caused vascular wall remodeling

Pulmonary hypertension (PH) induced by chronic hypoxia is characterized by thickening of pulmonary artery walls, elevated pulmonary vascular resistance, and right-heart failure. Dysfunction of endothelial cells is the hallmark event in the progression of PH. Among various mechanisms, endothelial to mesenchymal transition (EndoMT) has emerged as an important source of endothelial cell dysfunction in PH. However, the mechanisms underlying the EndoMT in PH remain largely unknown. Our results showed that peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) expression was decreased in pulmonary arterial endothelial cells (PAECs) in PH patients and hypoxia-induced PH mouse model compared to the normal controls. Endothelial-specific overexpression of PGC-1α using nanoparticle delivery significantly attenuated the progression of PH, as shown by the significantly decreased right ventricular systolic pressure and diminished artery thickness as well as reduced vascular muscularization. Moreover, Endothelial-specific overexpression of PGC-1α blocked the EndoMT of PAECs during PH, indicating that loss of PGC-1α promotes PH development by mediating EndoMT, which damages the integrity of endothelium. Intriguingly, we found that PGC-1α overexpression rescued the expression of endothelial nitric oxide synthase in mouse lung tissues that was deceased by hypoxia treatment in vivo and in endothelial cells treated with TGF-β in vitro. Consistently, PAECs and vascular smooth muscle co-culture showed that overexpression of PGC-1α in PAECs increases nitric oxide release, which would likely diffuse to smooth muscle cells, where it activates specific protein kinases, and initiates SMC relaxation by diminishing the calcium flux. Endothelial-specific overexpression of PGC-1α also attenuated hypoxia-induced pulmonary artery stiffness which appeared to be caused by both the decreased endothelial nitric oxide production and increased vascular remodeling. Taken together, these results demonstrated that endothelial-specific delivery of PGC-1α prevents PH development by inhibiting EndoMT of PAECs and thus restoring endothelial function and reducing vascular remodeling.

Genetic studies of nephrotic syndrome in Egyptian children

INTRODUCTION

Nephrotic syndrome (NS) might be caused by a kidney disorder or it can be a secondary disease. Untreated or resistant to treatment, NS stimulates glomerular damage that reduces the kidney function. This reduction leads to the end stage of renal failure. Therefore, it is very important to diagnose NS early, with the aim of inhibiting or lessening its associated morbidity and mortality.

METHODS

Gene polymorphism analysis for the three genes eNOS 27 bp VNTR, GSTP1 and IL-10(1082 G/A) were checked in 98 children with NS and 101 control subjects.

RESULTS

eNOS 27 bp VNTR genotypes and alleles are significantly different in the group of 98 children with NS compared to the 101 control subjects. The frequencies of ab and bb genotypes are significantly lower in patients than in the control group (ab: 17.2% vs. 22.8%; OR: 0.19; 95% CI: 0.06-0.58; p = 0.0026 & bb: 54.7% vs. 70.3%; OR: 0.19; 95% CI: 0.07-0.5; p = 0.0004). However, neither GSTP1 nor IL-10(1082 G/A) genotypes showed any significant difference in both groups.

CONCLUSIONS

eNOS 27 bp VNTR gene might be considered as an independent risk factor in the early prediction of nephrotic syndrome incidence, which may help prevent/reduce the occurrence of other complications associated with the late diagnosis and treatment of the disease.

Contemporary Lifestyle and Neutrophil Extracellular Traps: An Emerging Link in Atherosclerosis Disease

Neutrophil extracellular traps (NETs) are networks of extracellular genetic material decorated with proteins of nuclear, granular and cytosolic origin that activated neutrophils expel under pathogenic inflammatory conditions. NETs are part of the host's innate immune defense system against invading pathogens. Interestingly, these extracellular structures can also be released in response to sterile inflammatory stimuli (e.g., shear stress, lipidic molecules, pro-thrombotic factors, aggregated platelets, or pro-inflammatory cytokines), as in atherosclerosis disease. Indeed, NETs have been identified in the intimal surface of diseased arteries under cardiovascular disease conditions, where they sustain inflammation via NET-mediated cell-adhesion mechanisms and promote cellular dysfunction and tissue damage via NET-associated cytotoxicity. This review will focus on (1) the active role of neutrophils and NETs as underestimated players of the inflammatory process during atherogenesis and lesion progression; (2) how these extracellular structures communicate with the main cell types present in the atherosclerotic lesion in the arterial wall; and (3) how these neutrophil effector functions interplay with lifestyle-derived risk factors such as an unbalanced diet, physical inactivity, smoking or lack of sleep quality, which represent major elements in the development of cardiovascular disease.

Cellular Crosstalk between Endothelial and Smooth Muscle Cells in Vascular Wall Remodeling

Pathological vascular wall remodeling refers to the structural and functional changes of the vessel wall that occur in response to injury that eventually leads to cardiovascular disease (CVD). Vessel wall are composed of two major primary cells types, endothelial cells (EC) and vascular smooth muscle cells (VSMCs). The physiological communications between these two cell types (EC–VSMCs) are crucial in the development of the vasculature and in the homeostasis of mature vessels. Moreover, aberrant EC–VSMCs communication has been associated to the promotor of various disease states including vascular wall remodeling. Paracrine regulations by bioactive molecules, communication via direct contact (junctions) or information transfer via extracellular vesicles or extracellular matrix are main crosstalk mechanisms. Identification of the nature of this EC–VSMCs crosstalk may offer strategies to develop new insights for prevention and treatment of disease that curse with vascular remodeling. Here, we will review the molecular mechanisms underlying the interplay between EC and VSMCs. Additionally, we highlight the potential applicable methodologies of the co-culture systems to identify cellular and molecular mechanisms involved in pathological vascular wall remodeling, opening questions about the future research directions.

Mechanosensitive smooth muscle cell phenotypic plasticity emerging from a null state and the balance between Rac and Rho

Reversible differentiation of vascular smooth muscle cells (VSMCs) plays a critical role in vascular biology and disease. Changes in VSMC differentiation correlate with stiffness of the arterial extracellular matrix (ECM), but causal relationships remain unclear. We show that VSMC plasticity is mechanosensitive and that both the de-differentiated and differentiated fates are promoted by the same ECM stiffness. Differential equations developed to model this behavior predicted that a null VSMC state generates the dual fates in response to ECM stiffness. Direct measurements of cellular forces, proliferation, and contractile gene expression validated these predictions and showed that fate outcome is mediated by Rac-Rho homeostasis. Rac, through distinct effects on YAP and TAZ, is required for both fates. Rho drives the contractile state alone, so its level of activity, relative to Rac, drives phenotypic choice. Our results show how the cellular response to a single ECM stiffness generates bi-stability and VSMC plasticity.

Reversible differentiation/de-differentiation of smooth muscle cells plays a critical role in vascular biology and disease. Talwar et al. show that these differentiated and de-differentiated phenotypes emerge from a null state that is regulated by ECM stiffness and bidirectional effects of Rac on YAP and TAZ transcriptional coregulators.

Oxidative Stress in Ischemic Heart Disease

One of the novel interesting topics in the study of cardiovascular disease is the role of the oxidation system, since inflammation and oxidative stress are known to lead to cardiovascular diseases, their progression and complications. During decades of research, many complex interactions between agents of oxidative stress, oxidation, and antioxidant systems have been elucidated, and numerous important pathophysiological links to na number of disorders and diseases have been established. This review article will present the most relevant knowledge linking oxidative stress to vascular dysfunction and disease. The review will focus on the role of oxidative stress in endotheleial dysfunction, atherosclerosis, and other pathogenetic processes and mechanisms that contribute to the development of ischemic heart disease.

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Te increase in the prevalence of arterial hypertension (AH) in populations, ineffective treatment, the need for risk stratifcation, prevention, early diagnosis and successful treatment, actualize genomic studies to develop a personalized therapeutic approach to AH. Te review investigates the possible genetically determined mechanisms of the development of hypertension and endothelial dysfunction caused by polymorphism of the genes of endothelial nitric oxide synthase (eNOS) and enzymes of phases I and II of the xenobiotics detoxifcation system. Te probable interaction of both systems under the influence of harmful environmental factors, including tobacco smoking, and in the gestational period is discussed. It is proposed to study AH candidate genes in the xenobiotics detoxifcation system, the carriage of different variants of which can determine the sensitivity or resistance to antihypertensive pharmacotherapy, which can be useful for developing of the personalized tactics of managing patients with AH.

Immunometabolic Regulation of Vascular Redox State: The Role of Adipose Tissue

SIGNIFICANCE

Vascular oxidative stress plays a crucial role in atherogenesis and cardiovascular disease (CVD). Recent evidence suggests that vascular redox state is under the control of complex pathophysiological mechanisms, ranging from inflammation to obesity and insulin resistance (IR). Recent Advances: Adipose tissue (AT) is now recognized as a dynamic endocrine and paracrine organ that secretes several bioactive molecules, called adipokines. AT has recently been shown to regulate vascular redox state in both an endocrine and a paracrine manner through the secretion of adipokines, therefore providing a mechanistic link for the association between obesity, IR, inflammation, and vascular disease. Importantly, AT behaves as a sensor of cardiovascular oxidative stress, modifying its secretory profile in response to cardiovascular oxidative injury.

CRITICAL ISSUES

The present article presents an up-to-date review of the association between AT and vascular oxidative stress. We focus on the effects of individual adipokines on modulating reactive oxygen species production and scavenging in the vascular wall. In addition, we highlight how inflammation, obesity, and IR alter the biology and secretome of AT leading to a more pro-oxidant phenotype with a particular focus on the local regulatory mechanisms of perivascular AT driven by vascular oxidation.

FUTURE DIRECTIONS

The complex and dynamic biology of AT, as well as its importance in the regulation of vascular redox state, provides numerous opportunities for the development of novel, targeted treatments in the management of CVD. Therapeutic modulation of AT biology could improve vascular redox state affecting vascular disease pathogenesis. Antioxid. Redox Signal. 29, 313-336.

Effects of Xin-Ji-Er-Kang on Anticardiovascular Remodeling in L-NAME Induced Hypertensive Mice and Its Potential Mechanisms

Background

Xin-Ji-Er-Kang (XJEK) shows protective effects on the myocardial ischemic diseases in our previous reports. We hypothesized that XJEK may exert preventing effects on L-NAME induced hypertensive mice by ameliorating oxidative stress (OS) and endothelial dysfunction (ED).

Methods

After treatment with XJEK for four weeks, cardiac function and cardiovascular pathology changes were evaluated. Then, endothelial-dependent vascular relaxation and serum NO, eNOS, AMDA, SOD, MDA content, and cardiac tissue eNOS expression were detected.

Results

The hypertensive mice displayed distinct cardiovascular remodeling including increased HW/BW index (4.7 ± 0.33 versus 5.2 ± 0.34), cross-section area, and collagen deposition. In addition, ED was found manifested by decreased serum NO (20.54 ± 8.05 versus 6.29 ± 2.33), eNOS (28.34 ± 2.36 versus 20.37 ± 2.30), content, and decreased eNOS expression in cardiac tissue and damaged endothelium-dependent diastolic function. Moreover, OS was detected confirmed by decreased SOD activity and increased MDA content in serum. However, treatment with XJEK for 4 wk could reverse cardiovascular remodeling (HW/BW index normalized from 5.2 ± 0.34 to 4.59 ± 0.25), ameliorate and preserve endothelial function (NO: 16.67 ± 7.24 versus 6.29 ± 2.33; eNOS: 16.67 ± 7.24 versus 6.29 ± 2.33), and suppress OS.

Conclusion

XJEK has protective effects against cardiovascular remodeling in L-NAME induced hypertensive mice.

Ginkgetin ameliorates experimental atherosclerosis in rats

Atherosclerosis is a common disease seriously detrimental to human health. Natural products are important sources of therapeutic candidates for atherosclerosis. We here evaluated the effects of ginkgetin on experimental atherosclerosis in rats and explored the underlying mechanisms. Atherosclerosis was induced by high-fat diet for 12 weeks combined with single intraperitoneal injection of vitamin D3 in rats. The atherosclerotic rats were then treated with ginkgetin at 25, 50 and 100 mg/kg/d or simvastatin at 2 mg/kg/d for 8 weeks. Blood and thoracic aortas were collected for analyses of histopathology, lipid deposition, serum biochemistry, matrix metalloproteinases (MMPs), and nitric oxide (NO)/NO synthase (NOS) system. We found that ginkgetin improved thoracic aortic intima structure, reduced intima-media thickness and intima/media ratio, and attenuated lipid deposition in aorta of atherosclerotic rats. Ginkgetin also decreased the serum levels of total cholesterol, triglyceride and low-density lipoprotein cholesterol, but restored the serum levels of high-density lipoprotein cholesterol in atherosclerotic rats. Additionally, ginkgetin reduced the mRNA and protein expression of MMP-2 and MMP-9 in thoracic aortas of rats with atherosclerosis. Further examinations showed that ginkgetin increased the NO and NOS levels in serum and thoracic aortas. Ginkgetin also unregulated the expression of endothelial NOS and downregulated the expression of inducible NOS at both mRNA and protein levels in thoracic aortas of atherosclerotic rats. Altogether, ginkgetin showed therapeutic effects on experimental atherosclerosis associated with improving lipid profile and modulating the MMPs and NO/NOS systems in rats. Ginkgetin could be a promising candidate for the treatment of atherosclerosis.

In vivo antihyperlipidemic and antioxidant activity of porphyran in hyperlipidemic mice

The hypolipidemic and antioxidant effects of porphyran from the red algae Porphyra haitanensis as a dietary supplement were evaluated in mice. The levels of serum TC, TG and LDL-C in MP group increased significantly (p<0.05 or p<0.01) by 28.5%, 29.4% and 33.5% compared with the model group. These significant rises were accompanied by significant declines of plasma HDL-C by 21.6% compared with the model group. In addition, the liver content of malondialdehyde significantly decreased, while the superoxide dismutase, catalase, glutathione peroxidase activities significantly increased. The levels of serum SOD and GSH-Px in MP group increased significantly by 51.2% and 99.6% compared with the model group. The results suggested that porphyran could be used as functional foods and natural drugs in preventing the hyperlipidemia and this activity might be attributed to its antioxidant potential.

The role of inorganic nitrate and nitrite in CVD

CVD is the leading cause of death worldwide, a consequence of mostly poor lifestyle and dietary behaviours. Although whole fruit and vegetable consumption has been consistently shown to reduce CVD risk, the exact protective constituents of these foods are yet to be clearly identified. A recent and biologically plausible hypothesis supporting the cardioprotective effects of vegetables has been linked to their inorganic nitrate content. Approximately 60–80 % inorganic nitrate exposure in the human diet is contributed by vegetable consumption. Although inorganic nitrate is a relatively stable molecule, under specific conditions it can be metabolised in the body to produce NO via the newly discovered nitrate–nitrite–NO pathway. NO is a major signalling molecule in the human body, and has a key role in maintaining vascular tone, smooth muscle cell proliferation, platelet activity and inflammation. Currently, there is accumulating evidence demonstrating that inorganic nitrate can lead to lower blood pressure and improved vascular compliance in humans. The aim of this review is to present an informative, balanced and critical review of the current evidence investigating the role of inorganic nitrate and nitrite in the development, prevention and/or treatment of CVD. Although there is evidence supporting short-term inorganic nitrate intakes for reduced blood pressure, there is a severe lack of research examining the role of long-term nitrate intakes in the treatment and/or prevention of hard CVD outcomes, such as myocardial infarction and cardiovascular mortality. Epidemiological evidence is needed in this field to justify continued research efforts.

Nitric oxide-activatable gold nanoparticles for specific targeting and photo-thermal ablation of macrophages

Nitric oxide-activatable gold nanoparticles can be utilized as a useful NO sensing tool and a photo-thermal agent for specific inflammation-associated macrophages.

Intravenous transfusion of endothelial progenitor cells that overexpress vitamin D receptor inhibits atherosclerosis in apoE-deficient mice

Endothelial progenitor cells (EPCs) are widely used for angiogenic therapies, as well as predictive biomarkers to assess cardiovascular disease risk. However, it is unknown that whether overexpressed vitamin D receptor (VDR) in EPCs could help EPCs counteracting atherosclerotic risks. Here, we study intravenous transplantation of genetically modified EPCs over-expressing VDR in regulating endothelial dysfunction and spontaneously arising atherosclerotic plaques of ApoE-deficient mice. Firstly, we found that over-expression of VDR in EPCs could reduce atherosclerotic plaque formation in transplanted ApoE-/- mice. In addition, the concentration of serum HDL-C in ovVDR-EPCs group was much higher than that in control groups (ApoE-/- mice without injection or injected with fresh medium or adenovirus vector). While concentrations of serum total cholesterol, LDL-C, apoB and Lp (a) were negatively correlated with the expression level of VDR. What's more, improved serum concentration of NO and elevated serum and vessel wall expression of eNOS were observed in ovVDR-EPCs group. Furthermore, reduced expression and activity of MMP2, and elevated expression and activity of TIMP2 were detected in ovVDR-EPCs group. Taken together, intravenous transfusion of EPCs that overexpress VDR significantly inhibited atherosclerosis in ApoE-deficient mice and could be used as a potential method for angiogenic therapy.

Hypoxia in Atherogenesis

The anoxemia theory proposes that an imbalance between the demand for and supply of oxygen in the arterial wall is a key factor in the development of atherosclerosis. There is now substantial evidence that there are regions within the atherosclerotic plaque in which profound hypoxia exists; this may fundamentally change the function, metabolism, and responses of many of the cell types found within the developing plaque and whether the plaque will evolve into a stable or unstable phenotype. Hypoxia is characterized in molecular terms by the stabilization of hypoxia-inducible factor (HIF) 1α, a subunit of the heterodimeric nuclear transcriptional factor HIF-1 and a master regulator of oxygen homeostasis. The expression of HIF-1 is localized to perivascular tissues, inflammatory macrophages, and smooth muscle cells adjacent to the necrotic core of atherosclerotic lesions and regulates several genes that are important to vascular function including vascular endothelial growth factor, nitric oxide synthase, endothelin-1, and erythropoietin. This review summarizes the effects of hypoxia on the functions of cells involved in atherogenesis and the evidence for its potential importance from experimental models and clinical studies.

Magnetic ferroferric oxide nanoparticles induce vascular endothelial cell dysfunction and inflammation by disturbing autophagy

Despite the considerable use of magnetic ferroferric oxide nanoparticles (Fe3O4NPs) worldwide, their safety is still an important topic of debate. In the present study, we detected the toxicity and biological behavior of bare-Fe3O4NPs (B-Fe3O4NPs) on human umbilical vascular endothelial cells (HUVECs). Our results showed that B-Fe3O4NPs did not induce cell death within 24h even at concentrations up to 400 μg/ml. The level of nitric oxide (NO) and the activity of endothelial NO synthase (eNOS) were decreased after exposure to B-Fe3O4NPs, whereas the levels of proinflammatory cytokines were elevated. Importantly, B-Fe3O4NPs increased the accumulation of autophagosomes and LC3-II in HUVECs through both autophagy induction and the blockade of autophagy flux. The levels of Beclin 1 and VPS34, but not phosphorylated mTOR, were increased in the B-Fe3O4NP-treated HUVECs. Suppression of autophagy induction or stimulation of autophagy flux, at least partially, attenuated the B-Fe3O4NP-induced HUVEC dysfunction. Additionally, enhanced autophagic activity might be linked to the B-Fe3O4NP-induced production of proinflammatory cytokines. Taken together, these results demonstrated that B-Fe3O4NPs disturb the process of autophagy in HUVECs, and eventually lead to endothelial dysfunction and inflammation.

The roles of autophagy in vascular smooth muscle cells

Autophagy, which is an evolutionarily conserved mechanism and links to several cellular pathways, impacts vascular smooth muscle cells (VSMCs) survival and function. Activation of autophagy by intercellular and/or extracellular stimuli has protective effects on VSMCs against cell death, while on the contrary, overloading autophagy has been recognized as a deleterious process by excessive self-digestion. Alterations in autophagy has been documented in VSMC in response to various stimuli, resulting in modulation of VSMC functions, including proliferation, migration, matrix secretion, contraction/relaxation, and differentiation. Each of these changes in VSMC functions plays a critical role in the development of vascular diseases. Importantly, emerging evidence demonstrates that autophagy deficiency in VSMCs would contribute to atherosclerosis and restenosis, shedding novel light on therapeutic target of the vascular disorders. Herein, this review summarizes the recent progress associated with the roles of autophagy in VSMC and offers the perspectives to several challenges and future directions for further studies.

Chronic oral infection with major periodontal bacteria Tannerella forsythia modulates systemic atherosclerosis risk factors and inflammatory markers

Tannerella forsythia is a Gram-negative anaerobic organism that inhabits the subgingival cavity and initiates connective tissue destruction and alveolar bone resorption in periodontal disease (PD). PD is a chronic immunoinflammatory disease and has been linked to several systemic diseases including atherosclerosis. This study evaluated the effects of a chronic oral infection with T. forsythia ATCC 43037 on the induction of PD, inflammatory markers and atherosclerosis risk factors in hyperlipidemic ApoE(null) mice. Mice were orally infected for 12 and 24 weeks prior to euthanasia. Bacterial colonization of the oral cavity and bacteremia was confirmed via isolation of genomic DNA from oral plaque and tissues. Oral infection elicited significantly elevated levels of serum IgG and IgM antibodies and alveolar bone resorption compared to control mice. Tannerella forsythia-infected mice had increased serum amyloid A, and significantly reduced serum nitric oxide when compared to controls. Tannerella forsythia chronic infection also significantly increased serum lipoproteins suggesting altered cholesterol metabolism and potential for aortic inflammation. Despite enhanced acute phase reactants and altered lipid profiles, T. forsythia infection was associated with decreased aortic plaque. This study investigates the potential of a known periodontal bacterial pathogen found in atherosclerotic plaque in humans to accelerate atherosclerosis in hyperlipdemic mice.

Reactive oxygen species and endothelial function--role of nitric oxide synthase uncoupling and Nox family nicotinamide adenine dinucleotide phosphate oxidases

The healthy endothelium prevents platelet aggregation and leucocyte adhesion, controls permeability to plasma components and maintains vascular integrity. Damage to the endothelium promotes endothelial dysfunction characterized by: altered endothelium-mediated vasodilation, increased vascular reactivity, platelet aggregation, thrombus formation, increased permeability, leucocyte adhesion and monocyte migration. Molecular processes contributing to these phenomena include increased expression of adhesion molecules, synthesis of pro-inflammatory and pro-thrombotic factors and increased endothelin-1 secretion. Decreased nitric oxide bioavailability and increased generation of reactive oxygen species (ROS) are among the major molecular changes associated with endothelial dysfunction. A critical source of endothelial ROS is a family of non-phagocytic nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, including the prototypic Nox2-based NADPH oxidases, Nox1, Nox4 and Nox5. Other possible sources include mitochondrial electron transport enzymes, xanthine oxidase, cyclooxygenase, lipoxygenase and uncoupled nitric oxide synthase (NOS). Cross-talk between ROS-generating enzymes, such as mitochondrial oxidases and Noxs, is increasingly implicated in cellular ROS production. The present review discusses the importance of endothelial ROS in health and disease and focuses on the major ROS-generating systems in the endothelium, namely uncoupled endothelial nitric oxide synthase and NADPH oxidases.

Adenoviral transfer of vasoactive intestinal peptide (VIP) gene inhibits rat aortic and pulmonary artery smooth muscle cell proliferation

Vasoactive intestinal peptide (VIP), a 28 amino acid peptide, has been shown to inhibit proliferation of vascular smooth muscle cells. In previous studies VIP and VIP analogs have been used to study the effects of the peptide on vascular smooth muscle cell function. In this study an adenovirus encoding the VIP gene was used to investigate the mechanism of the antiproliferative action of VIP in vascular smooth muscle cells. Primary cultures of aortic and pulmonary artery smooth muscle cells from male Sprague-Dawley rats were transfected with varying concentrations of serotype 5 adenovirus encoding human VIP (Ad5CMVhVIP). Transfection efficiency and subsequently VIP gene expression were confirmed by western blot analysis and immunohistochemistry. In this study a decrease in vascular smooth muscle cell proliferation at vector concentrations of 150, 300 and 600MOI (multiplicity of infection) was observed. In addition, there was increased production of cAMP in pulmonary artery and aortic smooth muscle cells transfected with VIP. Treatment of cells with a PKA inhibitor (Rp-8-BrcAMPs) restored proliferation to about 80% of control whereas treatment with the PKG inhibitor Rp-8-BrcGMPs had no significant effect suggesting the involvement of the PKA pathway in the antiproliferative actions of VIP.

Is exercise training an effective therapy targeting endothelial dysfunction and vascular wall inflammation?

There is an increasing evidence that endothelial dysfunction and vascular wall inflammation are present in all stages of atherosclerosis. Atherosclerosis does not have to necessarily progress to an acute clinical event. Several therapeutic strategies exist, such as exercise training, which mitigates endothelial dysfunction and inflammation. Exercise training consistently improves the nitric oxide bioavailability, and the number of endothelial progenitor cells, and also diminishes the level of inflammatory markers, namely pro-inflammatory cytokines and C-reactive protein. However, the mechanisms by which exercise improves endothelial function in coronary artery disease patients are not fully clarified. Several mechanisms have been proposed to explain the positive effect of exercise on the disease progression. They include the decrease in cytokine production by the adipose tissue, skeletal muscles, endothelial cells, and blood mononuclear cells, and also, the increase in the bioavailability of nitric oxide, antioxidant defences, and regenerative capacity of endothelium. This study aims to provide a critical review of the literature linking exercise, inflammation, and endothelial dysfunction in coronary artery patients, and to discuss the potential mechanisms behind the exercise-training improvement of endothelial function and inflammatory status.

Inflammatory cytokines in vascular dysfunction and vascular disease

The vascular inflammatory response involves complex interaction between inflammatory cells (neutrophils, lymphocytes, monocytes, macrophages), endothelial cells (ECs), vascular smooth muscle cells (VSMCs), and extracellular matrix (ECM). Vascular injury is associated with increased expression of adhesion molecules by ECs and recruitment of inflammatory cells, growth factors, and cytokines, with consequent effects on ECs, VSMCs and ECM. Cytokines include tumor necrosis factors, interleukins, lymphokines, monokines, interferons, colony stimulating factors, and transforming growth factors. Cytokines are produced by macrophages, T-cells and monocytes, as well as platelets, ECs and VSMCs. Circulating cytokines interact with specific receptors on various cell types and activate JAK-STAT, NF-kappaB, and Smad signaling pathways leading to an inflammatory response involving cell adhesion, permeability and apoptosis. Cytokines also interact with mitochondria to increase the production of reactive oxygen species. Cytokine-induced activation of these pathways in ECs modifies the production/activity of vasodilatory mediators such as nitric oxide, prostacyclin, endothelium-derived hyperpolarizing factor, and bradykinin, as well as vasoconstrictive mediators such as endothelin and angiotensin II. Cytokines interact with VSMCs to activate Ca(2+), protein kinase C, Rho-kinase, and MAPK pathways, which promote cell growth and migration, and VSM reactivity. Cytokines also interact with integrins and matrix metalloproteinases (MMPs) and modify ECM composition. Persistent increases in cytokines are associated with vascular dysfunction and vascular disease such as atherosclerosis, abdominal aortic aneurysm, varicose veins and hypertension. Genetic and pharmacological tools to decrease the production of cytokines or to diminish their effects using cytokine antagonists could provide new approaches in the management of inflammatory vascular disease.

Role of glycocalyx in flow-induced production of nitric oxide and reactive oxygen species

Although the glycocalyx has been implicated in wall shear stress (WSS) mechanotransduction, the role of glycocalyx components in nitric oxide (NO) and reactive oxygen species (ROS) production remains unclear. Here, we tested the hypothesis that glycocalyx is implicated in both endothelial NO and O(2)(-) production. Specifically, we evaluated the role of hyaluronic acid (HA), heparan sulfate (HS), and sialic acid (SA) in NO and O(2)(-) mechanotransduction. Twenty-seven ex vivo porcine superficial femoral arteries were incubated with heparinase III, hyaluronidase, or neuraminidase, to remove HS, HA, or SA, respectively, from glycocalyx. The arteries were then subjected to steady-state flow and the effluent solution was measured for nitrites and the vessel diameter was tracked to quantify the degree of vasodilation. Our results show that removal of HA decreased both nitrites and vasodilation, and tempol treatment had no reversing effect. Degradation of HS proteoglycans decreased NO bioavailability through an increase in O(2)(-) production as indicated by fluorescent signals of dihydroethidium (DHE) and its area fraction (209+/-24% increase) and also removed extracellular O(2)(-) dismutase (ecSOD) (67+/-9% decrease). The removal of SA also increased O(2)(-) production as indicated by DHE fluorescent signals (86+/-17% increase) and the addition of tempol, a mimic O(2)(-) scavenger, restored both NO availability and vasodilation in both heparinase- and neuraminidase-treated vessels. This implies that HS and SA are not directly involved in WSS-mediated NO production. This study implicates HA in WSS-mediated NO mechanotransduction and underscores the role of HS and SA in ROS regulation in vessel walls in response to WSS stimulation.

High-density lipoproteins, inflammation and oxidative stress

Plasma levels of HDL (high-density lipoprotein)-cholesterol are strongly and inversely correlated with atherosclerotic cardiovascular disease. Both clinical and epidemiological studies have reported an inverse and independent association between serum HDL-cholesterol levels and CHD (coronary heart disease) risk. The cardioprotective effects of HDLs have been attributed to several mechanisms, including their involvement in the reverse cholesterol transport pathway. HDLs also have antioxidant, anti-inflammatory and antithrombotic properties and promote endothelial repair, all of which are likely to contribute to their ability to prevent CHD. The first part of this review summarizes what is known about the origins and metabolism of HDL. We then focus on the anti-inflammatory and antioxidant properties of HDL and discuss why these characteristics are cardioprotective.

SMA-copolymer conjugate of AHPP: a polymeric inhibitor of xanthine oxidase with potential antihypertensive effect

In vascular system, superoxide anion (O2(-)) generated by xanthine oxidase (XO) is known to regulate vascular tonus by reacting with, and thus consuming nitric oxide (NO), which determines vasorelaxation. We previously reported the remarkable antihypertensive effect of a potent XO inhibitor, 4-amino -6-hydroxypyrazolo[3,4-d]pyrimidine (AHPP). However, AHPP is insoluble in water, which hamper its in vivo application. Therefore, in this study we prepared a water soluble polymeric conjugate of AHPP, by using a styrene maleic acid copolymer (SMA, SMA-AHPP). SMA-AHPP showed similar inhibitory activity against XO (K(i)=0.25 microM) comparable to native AHPP (K(i)=0.17 microM), while exhibiting good water-solubility, which now made it possible for systemic injection. In vivo experiments were carried out to examine the antihypertensive effect of SMA-AHPP using the spontaneously hypertensive rats (SHR) by i.v. injection (15, 30 mg/kg) or by oral administration (100 mg/kg) of SMA-AHPP. The results showed significantly reduced blood pressures (up to 30% reduction) of SHR rats; this antihypertensive effect continued for at least 24 h after SMA-AHPP administration. These findings strongly suggest the potential value of SMA-AHPP as an antihypertensive agent with sustained in vivo activity, which warrants further investigations.

Endothelial nitric oxide synthase inhibits G12/13 and rho-kinase activated by the angiotensin II type-1 receptor: implication in vascular migration

BACKGROUND

Although, endothelial nitric oxide (NO) synthase (eNOS) is believed to antagonize vascular remodeling induced by the angiotensin II (AngII) type-1 receptor, the exact signaling mechanism remains unclear.

METHODS AND RESULTS

By expressing eNOS to vascular smooth muscle cells (VSMCs) via adenovirus, we investigated a signal transduction mechanism of the eNOS gene transfer in preventing vascular remodeling induced by AngII. We found marked inhibition of AngII-induced Rho/Rho-kinase activation and subsequent VSMC migration by eNOS gene transfer whereas G(q)-dependent transactivation of the epidermal growth factor receptor by AngII remains intact. This could be explained by the specific inhibition of G(12/13) activation by eNOS-mediated G(12/13) phosphorylation.

CONCLUSIONS

The eNOS/NO cascade specifically targets the Rho/Rho-kinase system via inhibition of G(12/13) to prevent vascular migration induced by AngII, representing a novel signal cross-talk in cardiovascular protection by NO.

Regulation of smooth muscle by inducible nitric oxide synthase and NADPH oxidase in vascular proliferative diseases

Inflammation plays a critical role in promoting smooth muscle migration and proliferation during vascular diseases such as postangioplasty restenosis and atherosclerosis. Another common feature of many vascular diseases is the contribution of reactive oxygen (ROS) and reactive nitrogen (RNS) species to vascular injury. Primary sources of ROS and RNS in smooth muscle are several isoforms of NADPH oxidase (Nox) and the cytokine-regulated inducible nitric oxide (NO) synthase (iNOS). One important example of the interaction between NO and ROS is the reaction of NO with superoxide to yield peroxynitrite, which may contribute to the pathogenesis of hypertension. In this review, we discuss the literature that supports an alternate possibility: Nox-derived ROS modulate NO bioavailability by altering the expression of iNOS. We highlight data showing coexpression of iNOS and Nox in vascular smooth muscle demonstrating the functional consequences of iNOS and Nox during vascular injury. We describe the relevant literature demonstrating that the mitogen-activated protein kinases are important modulators of proinflammatory cytokine-dependent expression of iNOS. A central hypothesis discussed is that ROS-dependent regulation of the serine/threonine kinase protein kinase Cdelta is essential to understanding how Nox may regulate signaling pathways leading to iNOS expression. Overall, the integration of nonphagocytic NADPH oxidase with cytokine signaling in general and in vascular smooth muscle in particular is poorly understood and merits further investigation.

Mechanisms for the role of tetrahydrobiopterin in endothelial function and vascular disease

NO produced by eNOS (endothelial nitric oxide synthase) is a key mediator of vascular homoeostasis. NO bioavailability is reduced early in vascular disease states, such as hypercholesterolaemia, diabetes and hypertension, and throughout the progression of atherosclerosis. This is a result of both reduced NO synthesis and increased NO consumption by reactive oxygen species. eNOS enzymatic activity appears to be determined by the availability of its cofactor BH4 (tetrahydrobiopterin). When BH4 levels are adequate, eNOS produces NO; when BH4 levels are limiting, eNOS becomes enzymatically uncoupled and generates superoxide, contributing to vascular oxidative stress and endothelial dysfunction. BH4 bioavailability is determined by a balance of enzymatic de novo synthesis and recycling, versus oxidative degradation in dysfunctional endothelium. Augmenting vascular BH4 levels by pharmacological supplementation, by enhancing the rate of de novo biosynthesis or by measures to reduce BH4 oxidation have been shown in experimental studies to enhance NO bioavailability. Thus BH4 represents a potential therapeutic target for preserving eNOS function in vascular disease.

Impact of glucose levels on advanced glycation end products in hemodialysis

The current obesity epidemic throughout the western world has resulted in a considerable increase in the condition Type II diabetes mellitus. Recently, the World Health Organization has predicted that the global prevalence of Type II will increase from 175 million patients in 2003 to over 350 million by 2030. One of the major consequences of this disorder is renal failure, which presents itself as chronic kidney disease, and can progress to end-stage renal disease. Once diagnosed, patients are generally treated using dialysis due to a shortage of kidney donors. The fundamental process of dialysis still requires improvement because the survival rate of these patients is relatively poor. This has resulted in considerable research into improvements in hemodialysis membranes, and the challenge to find more suitable marker(s) in assessing the efficacy of the dialysis process. A class of compounds highlighted as a possible accumulative toxin is advanced glycation end products or AGEs. This is an article regarding the impact of hemodialysis and hemodiafiltration on glucose and AGE levels within the body and the consequences of a chronic hyperglycemic condition. It also highlights the negative aspects of using dextrose in conventional dialysis solutions (an area that has already been identified by peritoneal dialysis clinicians as problematic). The review concludes by suggesting several possible topics of future research.

Low-density lipoprotein reduction by simvastatin is accompanied by angiotensin II type 1 receptor downregulation, reduced oxidative stress, and improved endothelial function in patients with stable coronary artery disease

OBJECTIVES

We tested the hypothesis that low-density lipoprotein-cholesterol induces angiotensin II type 1 receptor upregulation that, in turn, accounts for enhanced oxidative stress, and the subsequent endothelial dysfunction in patients with coronary artery disease.

METHODS

Brachial artery flow-mediated vasodilation, serum 8-iso-prostaglandin F2alpha (8-isoprostane), and angiotensin II type 1 receptor density on platelets were measured in 19 patients with coronary artery disease, at entry and after 12 weeks of simvastatin therapy, 40 mg/day.

RESULTS

At entry there was a significant linear correlation between: angiotensin II type 1 receptor density and plasma low-density lipoprotein-cholesterol; plasma 8-isoprostane and angiotensin II type 1 receptor density; and flow-mediated vasodilation and 8-isoprostane. Simvastatin therapy reduced low-density lipoprotein-cholesterol, downregulated angiotensin II type 1 receptor, decreased 8-isoprostane, and improved flow-mediated vasodilation. The slopes of the presimvastatin and the postsimvastatin angiotensin II type 1 receptor/low-density lipoprotein relationships did not significantly differ, indicating that simvastatin caused a downregulation of angiotensin II type 1 receptor that could be predicted by the low-density lipoprotein reduction. In addition, simvastatin-mediated changes in 8-isoprostane could be predicted by angiotensin II type 1 receptor downregulation, and flow-mediated vasodilation improvement by changes in 8-isoprostane. A significant correlation existed between simvastatin-mediated changes in 8-isoprostane and angiotensin II type 1 receptor.

CONCLUSION

The results of this study are consistent with the hypothesis that in coronary artery disease, the impairment of endothelial function is strongly associated with oxidative stress, oxidative stress with cellular angiotensin II type 1 receptor density, and the angiotensin II type 1 receptor density with low-density lipoprotein-cholesterol, suggesting cause-effect relationships between these variables. In support for this notion, these baseline associations were not significantly disturbed by low-density lipoprotein-lowering therapy with simvastatin.

Activation of endothelial nitric oxide synthase by the angiotensin II type 1 receptor

Enhanced angiotensin II (AngII) action has been implicated in endothelial dysfunction that is characterized as decreased nitric oxide availability. Although endothelial cells have been reported to express AngII type 1 (AT1) receptors, the exact role of AT1 in regulating endothelial NO synthase (eNOS) activity remains unclear. We investigated the possible regulation of eNOS through AT1 in bovine aortic endothelial cells (BAECs) and its functional significance in rat aortic vascular smooth muscle cells (VSMCs). In BAECs infected with adenovirus encoding AT1 and in VSMCs infected with adenovirus encoding eNOS, AngII rapidly stimulated phosphorylation of eNOS at Ser1179. This was accompanied with increased cGMP production. These effects were blocked by an AT1 antagonist. The cGMP production was abolished by a NOS inhibitor as well. To explore the importance of eNOS phosphorylation, VSMCs were also infected with adenovirus encoding S1179A-eNOS. AngII did not stimulate cGMP production in VSMCs expressing S1179A. However, S1179A was able to enhance basal NO production as confirmed with cGMP production and enhanced vasodilator-stimulated phosphoprotein phosphorylation. Interestingly, S1179A prevented the hypertrophic response similar to wild type in VSMCs. From these data, we conclude that the AngII/AT1 system positively couples to eNOS via Ser1179 phosphorylation in ECs and VSMCs if eNOS and AT1 coexist. However, basal level NO production may be sufficient for prevention of AngII-induced hypertrophy by eNOS expression. These data demonstrate a novel molecular mechanism of eNOS regulation and function and thus provide useful information for eNOS gene therapy under endothelial dysfunction.

Expression of nitric oxide related enzymes in coronary heart disease

Enzymes involved in the metabolism nitric oxide (NO) and reactive oxygen species (ROS) may play a role for the decreased availability of NO in atherosclerosis. We, therefore, hypothesized that the pattern of gene expression of these enzymes is altered in atherosclerosis. Myocardial tissue from patients with coronary heart disease (CHD) or without CHD (control group) was investigated. The level of enzymes related to NO/ROS metabolism was determined both at mRNA level and protein level by rt-PCR, real-time PCR, and western blot. The expression of NOS1-3 (synthesis of NO), arginase1 (reduction of L-arginine), p22phox (active subunit of NADPH oxidase), GTPCH (rate limiting enzyme for tetrahydrobiopterin), SOD1-3 (scavengers of superoxide anions), PRTMT1-3, and DDAH2 (involved in the metabolism of ADMA) was determined. All enzymes were found to be expressed in human myocardium. NOS isoforms were decreased in CHD in protein level, but only the downregulation of NOS3 expression reached statistical significance. The expression of PRMT1 and PRMT3 was increased. In addition, the expression of DDAH2 was reduced, both theoretically leading to an increase of ADMA concentration. SOD3 was downregulated in tissue from patients with CHD. Taken together, in myocardial tissue from patients with atherosclerosis, the expression of genes increasing ADMA levels is enhanced in contrast to a reduced expression of genes promoting NO synthesis. These results may contribute to the explanation of increased oxidative stress in atherosclerosis on the level of gene expression.

The roles of nitric oxide in murine cardiovascular development

Nitric oxide (NO) participates in a diverse array of biological functions in mammalian organ systems. Depending on the biochemical environment, the production of NO may result in cytoprotection or cytotoxicity. The paradoxical actions of NO arise from the complexities generated by the redox milieu, NO concentration/bioavailability, and tissue/cell context, which ultimately result in the wide range of regulatory roles observed. Additionally, in physiological versus pathological states, NO often displays diametrically opposing affects in several organ systems. Here, we will discuss the roles of NO during reproduction, organ system development, in particular, the cardiovascular system, and its potential implications in diabetes-induced fetal defects.

Role of oxidative stress in angiotensin-II mediated contraction of human conduit arteries in patients with cardiovascular disease

BACKGROUND

Angiotensin II is a powerful vasoconstrictor involved in the development of high blood pressure and in the regulation of cardiovascular growth. Recent reports have suggested that in addition to the classical pathways involved in transducing responses to receptor activation, formation of reactive oxygen species by angiotensin II may also be involved. We investigated the importance of oxidative stress in angiotensin II induced contraction in human conduit arteries from patients with cardiovascular disease.

METHODS AND RESULTS

Isometric contraction studies using human radial arteries entailed probes modulating the redox-dependent reactions to define the oxidative pathways involved in angiotensin II contraction. In situ oxidative fluorescence was employed to detect immediate superoxide tissue production in radial and internal mammary arteries. Treatment with TEMPOL, human superoxide dismutase, diphenyleneiodonium, oxypurinol, NG-monomethyl L-arginine considerably decreased contractile response to angiotensin II in radial arteries. Similarly, angiotensin II-stimulated arterial superoxide production was reduced in the presence of the above inhibitors. On the contrary, used as controls, norepinephrine vasoconstriction was not associated with increase of superoxide and neither ciprofloxacin nor aminophylline altered basal or angiotensin II induced superoxide generation.

CONCLUSIONS

Our findings provide evidence for the role of oxidative pathways in contractile response of human conduit arteries to angiotensin II. Angiotensin II induced superoxide anion production may be mediated by multiple inter-dependent rate-limiting enzymes in both types of artery. Our studies may have important implication for future therapeutic approaches involving inhibition of angiotensin II mediated superoxide generation in hypertension and prevention of cardiovascular disease.

CONDENSED ABSTRACT

We studied the role of oxidant species in contraction responses to angiotensin II in human conduit arteries. Treating radial artery segments with the anti-oxidants with a range of inhibitors, affecting the redox dependent pathways, markedly reduced contraction to angiotensin II. In parallel experiments, oxidative fluorescence was assessed and compared in human radial and internal mammary artery. Angiotensin II induced superoxide anion production may be mediated by multiple inter-dependent rate-limiting enzymes in both types of artery.

Antiatherogenic effects of S-nitroso-N-acetylcysteine in hypercholesterolemic LDL receptor knockout mice

BACKGROUND

The pathophysiology of the NO/NO synthase system and dysfunctional changes in the endothelium in the early phases of the atherogenic process are incompletely understood. In this study, we investigated the effects of the nitrosothiol NO donor S-nitroso-N-acetylcysteine (SNAC) in the early prevention of plaque development in the hypercholesterolemic LDLr-/- mice as well as the changes in endothelium-dependent relaxation and NO synthase expression.

METHODS AND RESULTS

LDLr-/- mice were fed a 1.25% cholesterol-enriched diet for 15 days. Plasma cholesterol/triglyceride levels increased and this increase was accompanied by the development of aortic root lesions. Aortic vasorelaxation to acetylcholine was increased, although endothelium-independent relaxation in response to sodium nitroprusside did not change, which suggest stimulated NO release enhanced. This dysfunction was associated with enhanced aortic superoxide production and with increased levels of constitutive NOS isoform expression, particularly neuronal NOS. SNAC (S-nitroso-N-acetylcysteine) administration (0.51 micromol/kg/day i.p. for 15 days) decreased the extent of the plaque by 55% in hypercholesterolemic mice, but had no effects on vasomotor changes. It did, however, lead to a decrease in constitutive NOS expression. The SNAC induced only minor changes in plasma lipid profile.

CONCLUSION

The present study has shown that, in early stages of plaque development in LDLr-/- mice, specific changes in NO/NO synthase system develop, that are characterized by increased endothelium-dependent vasorelaxation and increased constitutive NOS expression. Since the development of plaque and the indicator of endothelial cell dysfunction were prevented by SNAC, such treatment may constitute a novel strategy for the halting of progression of early plaque.

eNOS gene intron 4 a/b VNTR polymorphism is a risk factor for coronary artery disease in Southern Turkey

BACKGROUND

Nitric oxide (NO) plays a major role in the regulation of vascular tone Associations between NO genotypes, coronary artery disease (CAD) and other risk factors have been described by many authors. The aim of this study was to investigate the role of endothelial nitric oxide synthase (eNOS) gene intron 4 a/b variable number of tandem repeats (VNTR) polymorphism and other risk factors in the development of CAD in subjects living in Southern Turkey.

METHODS

Two-hundred and sixty-six patients (154 males and 112 females, aged between 30 and 80 years, mean 52.4+/-10.3) whose coronary arteries were evaluated by means of coronary angiography were enrolled in the study. Of the total, 133 had CAD (Group I) and the remaining had normal coronary arteries (Group II). The eNOS gene intron 4 a/b VNTR polymorphism was analyzed by polymerase chain reaction. The plasma lipid levels and other risk factors were also determined in all subjects.

RESULTS

The a allele frequencies and genotypes carrying a allele were significantly higher in Group I. Plasma lipids, except HDL-C, were also increased in this group. We found that hypertension (HT), diabetes mellitus (DM), male gender, age and smoking were the independent predictors of CAD.

CONCLUSION

a allele of eNOS intron 4 a/b VNTR polymorphism is not an independent predictor of CAD. eNOS intron 4 a/b polymorphism (presence of a allele) is a risk factor in addition to HT, DM, male gender, age and smoking for the development of CAD in Southern Turkey.

Effect of statin therapy on serum trace element status in dyslipidaemic subjects

Patients previously not treated with a lipid-lowering agent (n = 20; mean age 49.15 +/- 3.28 years) were treated with either 10 mg/day of Simvastatin (n = 11), or Atorvastatin (n = 9) for 4 months. Fourteen additional patients were recruited from the same clinic at the same hospital as a control group. The medication of these latter patients was unaltered for 4 months and the same parameters were measured as for the statin groups. Serum concentrations of zinc, copper, caeruloplasmin, selenium, glutathione peroxidase (GPx) and C-reactive protein (CRP) were measured together with their lipid profiles pre- and post-treatment. In addition to reducing serum total and low-density lipoprotein (LDL) cholesterol (p < 0.0001), statin treatment was associated with a significant reduction in mean serum zinc (9%, p = 0.03), copper (9%, p < 0.01), caeruloplasmin (24%, p < 0.05), and median CRP (45%, p < 0.03). Similar changes were not observed in the control patients. No significant effects were observed for serum selenium, copper/caeruloplasmin ratio, or GPx (p > 0.05) in either statin or control groups. These changes may be related to the known anti-inflammatory properties of the statin class of drugs.

Endothelial nitric oxide synthase gene transfer restores endothelium-dependent relaxations and attenuates lesion formation in carotid arteries in apolipoprotein E-deficient mice

Nitric oxide (NO) and monocyte chemoattractant protein-1 (MCP-1) exert partly opposing effects in vascular biology. NO plays pleiotropic vasoprotective roles including vasodilation and inhibition of platelet aggregation, smooth muscle cell proliferation, and endothelial monocyte adhesion, the last effect being mediated by MCP-1 downregulation. Early stages of arteriosclerosis are associated with reduced NO bioactivity and enhanced MCP-1 expression. We have evaluated adenovirus-mediated gene transfer of human endothelial NO synthase (eNOS) and of a N-terminal deletion (8ND) mutant of the MCP-1 gene that acts as a MCP-1 inhibitor in arteriosclerosis-prone, apolipoprotein E-deficient (ApoE(-/-)) mice. Endothelium-dependent relaxations were impaired in carotid arteries instilled with a noncoding adenoviral vector but were restored by eNOS gene transfer (p < 0.01). A perivascular collar was placed around the common carotid artery to accelerate lesion formation. eNOS gene transfer reduced lesion surface areas, intima/media ratios, and macrophage contents in the media at 5-week follow-up (p < 0.05). In contrast, 8ND-MCP-1 gene transfer did not prevent lesion formation. In conclusion, eNOS gene transfer restores endothelium-dependent vasodilation and inhibits lesion formation in ApoE(-/-) mouse carotids. Further studies are needed to assess whether vasoprotection is maintained at later disease stages and to evaluate the long-term efficacy of eNOS gene therapy for primary arteriosclerosis.

An integrated evaluation of endothelial constitutive nitric oxide synthase polymorphisms and coronary artery disease in men

In the present study, we sought to evaluate the role of three polymorphisms in the ecNOS (endothelial constitutive nitric oxide synthase) gene in relation to the existence, severity and progression of CAD (coronary artery disease), MI (myocardial infarction) and the occurrence of ischaemia in a predominantly Caucasian population. Patients with CAD (n=760) and age- and sex-matched population-based controls (n=691) were genotyped for the −786T/C, E/D298 and 4a/b polymorphisms. Patients were randomized to pravastatin (40 mg) or placebo. Progression of atherosclerosis was evaluated by sequential angiography. Functionality was assessed by ST segment analysis of ambulant ECGs. The E298 (P=0.003) and 4a (P=0.001) alleles were associated with CAD. Furthermore, E298 (P=0.009) and −786T (P=0.022) alleles were associated with previous MI among patients, predominantly smokers. D/D298 homozygotes, but not −786T/C or 4a/4b mutants, had longer-lasting ischaemia than others (P<0.05). We found no differences in progression of atherosclerosis, irrespective of pravastatin use. We conclude that the E/D298 polymorphism is most consistently associated with CAD, but not with progression of atherosclerosis. The E allele is associated with CAD and MI, whereas the D allele is associated with ischaemia.

C-reactive protein, its role in inflammation, Type 2 diabetes and cardiovascular disease, and the effects of insulin-sensitizing treatment with thiazolidinediones

Increased concentrations of the marker of inflammation, C-reactive protein (CRP), are associated with insulin resistance, Type 2 diabetes and the development of cardiovascular disease. In particular, inflammation is closely associated with endothelial dysfunction and is recognized as one of the cardiovascular risk factors clustering in the Insulin Resistance Syndrome or Metabolic Syndrome. The exact mechanisms linking insulin resistance and inflammation remain unclear. However, the close association between insulin resistance and inflammation in atherogenesis suggests that therapies that address both parameters may have benefits in reducing diabetes-related macrovascular complications. The thiazolidinedione class of oral anti-diabetic agents are powerful insulin sensitizers that also have anti-inflammatory properties. Treatment with these agents has a range of anti-atherogenic effects, including reduced levels of CRP, plasminogen activator inhibitor-1 (PAI-1), TNF-alpha and reactive oxygen species. Additionally, the insulin-sensitizing effect of thiazolidinediones improves other factors of the Insulin Resistance Syndrome, including dyslipidaemia and hypertension. Outcome studies are underway to determine if the effects of improving insulin sensitivity and reducing inflammation will translate into clinical benefits and reduce the cardiovascular morbidity and mortality associated with insulin resistance and Type 2 diabetes.

Transduction of peptide analogs of the small heat shock-related protein HSP20 inhibits intimal hyperplasia

BACKGROUND

Human saphenous vein (HSV) is the autologous conduit of choice for peripheral vascular reconstructions. However, vasospasm can lead to early graft failure. The leading cause of delayed graft failure is intimal hyperplasia.

OBJECTIVE

To develop a proteomic approach to prevent vein-graft spasm and intimal hyperplasia.

METHODS

Biomimetic peptide analogs of the small heat shock-related protein HSP20, containing a protein transduction domain (PTD), a phosphorylated serine, and a sequence of HSP20 surrounding the phosphorylation site (PTD-pHSP20), or a scrambled sequence of the same amino acids surrounding the phosphorylation site (PTD-scHSP20) were synthesized. The peptides were used in muscle bath and organ culture experiments with human saphenous vein (HSV) segments. Cultured smooth muscle cell lines were used to determine the effect of the peptides on proliferation and migration.

RESULTS

In HSV rings precontracted with norepinephrine, PTD-pHSP20 but not PTD-scHSP20 led to relaxation. There was no significant difference in smooth muscle cell proliferation in cells treated with PTD-pHSP20 compared with PTD-scHSP20. Treatment with PTD-pHSP20 significantly inhibited cellular migration compared with PTD-scHSP20. Control, untreated, and PTD-scHSP20-treated saphenous veins had significant increases in intimal thickness after culture. This intimal thickening was completely inhibited by treatment with PTD-pHSP20.

CONCLUSIONS

Protein transduction of biologically active motifs of HSP20 can affect pathologic and physiologic responses of HSV and represents a novel proteomic-based therapeutic approach.

CLINICAL RELEVANCE

We have been a part of the genomics era and are now viewing the emergence of "proteomics." The genome is linear and relatively easy to examine; however the proteome is much more complex and dynamic. In essence, the purpose of gene therapy is to manipulate the genome to produce a particular protein. This manuscript describes a new proteomic approach in which the biologically active part of a protein is directly introduced into vascular cells. Peptides were synthesized which contained a total of 24 amino acids, 11 of which represent a protein transduction domain or "carrier" while the other 13 are the biologically active "cargo." These synthetic peptides prevent spasm (contraction) and intimal hyperplasia in segments of human saphenous vein treated ex vivo. Preclinical development is currently underway to develop these molecules as a proteomic-based vein harvest solution to enhance vein-graft patency.

High-density lipoprotein and apolipoprotein AI increase endothelial NO synthase activity by protein association and multisite phosphorylation

NO propagates a number of antiatherogenic effects in the endothelium, and diminished availability has been associated with vascular disease. Recently it has been reported that phosphorylation of endothelial NO synthase (eNOS) at Ser-1179 is required to increase activity in response to stimuli, including high-density lipoprotein (HDL). The current study was undertaken to further examine the mechanism by which HDL activates eNOS and to specifically determine the role of the major apolipoprotein of HDL, apolipoprotein AI (ApoAI). Phosphorylation of eNOS residues Ser-116, Ser-617, Ser-635, Ser-1179, and Thr-497 after incubation with ApoAI and HDL was examined. There were significant increases in phosphorylation at Ser-116 in response to both HDL and ApoAI and similar magnitudes of dephosphorylation at Thr-497. Ser-1179 phosphorylation increased transiently but returned to basal level after 2.5 min. Data demonstrating activation of AMP activated protein kinase (AMPK) during HDL and ApoAI incubation suggests that AMPK may play a role in activation of eNOS. NO release in response to HDL and ApoAI stimulation in endothelial cells paralleled the time frames of phosphorylation, suggesting a causal relationship. Furthermore, ApoAI was found to associate with eNOS in endothelial cells and bind transfected eNOS in Chinese hamster ovary cells, whereas confocal data demonstrates colocalization of ApoAI and eNOS in the perinuclear region, suggesting a protein-protein interaction. Collectively, the results indicate that HDL and ApoAI increase eNOS activity by multisite phosphorylation changes, involving AMPK activation after protein association between ApoAI and eNOS.