Superoxide production and expression of nox family proteins in human atherosclerosis

ABCG1 Attenuates Oxidative Stress Induced by H2O2 through the Inhibition of NADPH Oxidase and the Upregulation of Nrf2-Mediated Antioxidant Defense in Endothelial Cells

Summary. Oxidative stress is an important factor that is related to endothelial dysfunction. ATP-binding cassette transporter G1 (ABCG1), a regulator of intracellular cholesterol efflux, has been found to prevent endothelial activation in vessel walls. To explore the role of ABCG1 in oxidative stress production in endothelial cells, HUAECs were exposed to H₂O₂ and transfected with the specific ABCG1 siRNA or ABCG1 overexpression plasmid. The results showed that overexpression of ABCG1 by ABCG1 plasmid or liver X receptor (LXR) agonist T0901317 treatment inhibited ROS production and MDA content induced by H₂O₂ in HUAECs. Furthermore, ABCG1 upregulation blunted the activity of prooxidant NADPH oxidase and the expression of Nox4, one of the NADPH oxidase subunits. Moreover, the increased migration of Nrf2 from the cytoplasm to the nucleus and antioxidant HO-1 expression were detected in HUAECs with upregulation of ABCG1. Conversely, ABCG1 downregulation by ABCG1 siRNA increased NADPH oxidase activity and Nox4 expression and abrogated the increase at Nrf2 nuclear protein levels. In addition, intracellular cholesterol load interfered with the balance between NADPH oxidase activity and HO-1 expression. It was suggested that ABCG1 attenuated oxidative stress induced by H₂O₂ in endothelial cells, which might be involved in the balance between decreased NADPH oxidase activity and increased Nrf2/OH-1 antioxidant defense signaling via its regulation for intracellular cholesterol accumulation.

Genetic Variants rs1049255 CYBA and rs2333227 MPO are Associated with Susceptibility to Coronary Artery Disease in Russian Residents of Central Russia

Aim      To study association of single-nucleotide polymorphisms rs1049255 CYBA and rs2333227 MPO with development of ischemic heart disease (IHD) in Russian residents of Central Russia.Material and methods  The study material was DNA samples from 436 patients with IHD (265 men, 171 women; mean age, 61 years) and 370 sex- and age-matched arbitrarily healthy volunteers (209 men, 161 women; mean age, 60 years). Genotyping was performed by allelic discrimination with TaqMan probes.Results Comparative analysis of genotype frequency (log-additive regression model) showed that SNP rs1049255 CYBA (odds ratio, OR, 0.79 at 95 % confidence interval, CI, from 0.65 to 0.96; p=0.02) and rs2333227 MPO (OR 0.72 at 95 % CI from 0.55 to 0.95; p=0.02) were associated with a decreased risk of IHD adjusted for sex and age. Analysis of sex-specific effects showed that the protective effect of rs1049255 CYBA was evident only in men (OR 0.72 at 95 % CI from 0.55 to 0.94; p=0.16).Conclusion      The study demonstrated a protective effect of rs1049255 CYBA and rs2333227 MPO with respect of IHD in Russians. The protective effect of rs1049255 CYBA was observed only in men.

Myeloperoxidase: A versatile mediator of endothelial dysfunction and therapeutic target during cardiovascular disease

Myeloperoxidase (MPO) is a prominent mammalian heme peroxidase and a fundamental component of the innate immune response against microbial pathogens. In recent times, MPO has received considerable attention as a key oxidative enzyme capable of impairing the bioactivity of nitric oxide (NO) and promoting endothelial dysfunction; a clinically relevant event that manifests throughout the development of inflammatory cardiovascular disease. Increasing evidence indicates that during cardiovascular disease, MPO is released intravascularly by activated leukocytes resulting in its transport and sequestration within the vascular endothelium. At this site, MPO catalyzes various oxidative reactions that are capable of promoting vascular inflammation and impairing NO bioactivity and endothelial function. In particular, MPO catalyzes the production of the potent oxidant hypochlorous acid (HOCl) and the catalytic consumption of NO via the enzyme's NO oxidase activity. An emerging paradigm is the ability of MPO to also influence endothelial function via non-catalytic, cytokine-like activities. In this review article we discuss the implications of our increasing knowledge of the versatility of MPO's actions as a mediator of cardiovascular disease and endothelial dysfunction for the development of new pharmacological agents capable of effectively combating MPO's pathogenic activities. More specifically, we will (i) discuss the various transport mechanisms by which MPO accumulates into the endothelium of inflamed or diseased arteries, (ii) detail the clinical and basic scientific evidence identifying MPO as a significant cause of endothelial dysfunction and cardiovascular disease, (iii) provide an up-to-date coverage on the different oxidative mechanisms by which MPO can impair endothelial function during cardiovascular disease including an evaluation of the contributions of MPO-catalyzed HOCl production and NO oxidation, and (iv) outline the novel non-enzymatic mechanisms of MPO and their potential contribution to endothelial dysfunction. Finally, we deliver a detailed appraisal of the different pharmacological strategies available for targeting the catalytic and non-catalytic modes-of-action of MPO in order to protect against endothelial dysfunction in cardiovascular disease.

Oxidative stress mitigation by antioxidants - An overview on their chemistry and influences on health status

The present review paper focuses on the chemistry of oxidative stress mitigation by antioxidants. Oxidative stress is understood as a lack of balance between the pro-oxidant and the antioxidant species. Reactive oxygen species in limited amounts are necessary for cell homeostasis and redox signaling. Excessive reactive oxygenated/nitrogenated species production, which counteracts the organism's defense systems, is known as oxidative stress. Sustained attack of endogenous and exogenous ROS results in conformational and oxidative alterations in key biomolecules. Chronic oxidative stress is associated with oxidative modifications occurring in key biomolecules: lipid peroxidation, protein carbonylation, carbonyl (aldehyde/ketone) adduct formation, nitration, sulfoxidation, DNA impairment such strand breaks or nucleobase oxidation. Oxidative stress is tightly linked to the development of cancer, diabetes, neurodegeneration, cardiovascular diseases, rheumatoid arthritis, kidney disease, eye disease. The deleterious action of reactive oxygenated species and their role in the onset and progression of pathologies are discussed. The results of oxidative attack become themselves sources of oxidative stress, becoming part of a vicious cycle that amplifies oxidative impairment. The term antioxidant refers to a compound that is able to impede or retard oxidation, acting at a lower concentration compared to that of the protected substrate. Antioxidant intervention against the radicalic lipid peroxidation can involve different mechanisms. Chain breaking antioxidants are called primary antioxidants, acting by scavenging radical species, converting them into more stable radicals or non-radical species. Secondary antioxidants quench singlet oxygen, decompose peroxides, chelate prooxidative metal ions, inhibit oxidative enzymes. Moreover, four reactivity-based lines of defense have been identified: preventative antioxidants, radical scavengers, repair antioxidants, and those relying on adaptation mechanisms. The specific mechanism of a series of endogenous and exogenous antioxidants in particular aspects of oxidative stress, is detailed. The final section resumes critical conclusions regarding antioxidant supplementation.

Oxidative Stress in Cardiovascular Diseases

Reactive oxygen species (ROS) are subcellular messengers in signal transductions pathways with both beneficial and deleterious roles. ROS are generated as a by-product of mitochondrial respiration or metabolism or by specific enzymes such as superoxide dismutases, glutathione peroxidase, catalase, peroxiredoxins, and myeloperoxidases. Under physiological conditions, the low levels of ROS production are equivalent to their detoxification, playing a major role in cellular signaling and function. In pathological situations, particularly atherosclerosis or hypertension, the release of ROS exceeds endogenous antioxidant capacity, leading to cell death. At cardiovascular levels, oxidative stress is highly implicated in myocardial infarction, ischemia/reperfusion, or heart failure. Here, we will first detail the physiological role of low ROS production in the heart and the vessels. Indeed, ROS are able to regulate multiple cardiovascular functions, such as cell proliferation, migration, and death. Second, we will investigate the implication of oxidative stress in cardiovascular diseases. Then, we will focus on ROS produced by NAPDH oxidase or during endothelial or mitochondrial dysfunction. Given the importance of oxidative stress at the cardiovascular level, antioxidant therapies could be a real benefit. In the last part of this review, we will detail the new therapeutic strategies potentially involved in cardiovascular protection and currently under study.

The Role of Antioxidants in the Prevention of Cadmium-Induced Endothelial Dysfunction

Background:

Cadmium is a worldwide spread toxicant that accumulates in tissues and affects many organs, mainly through oxidative damage. Oxidative stress is often associated with cardiovascular diseases and, when it affects vessels, it induces endothelial dysfunction, which, in turn, could precipitate atherosclerosis and hypertension. Therefore, it is reasonable to suggest antioxidant supplementation as a therapy against cadmiuminduced endothelial dysfunction.

Objective:

This literature review aims to present the mechanisms involving oxidative stress in which cadmium induces endothelial dysfunction and the benefits of antioxidant supplementation as a therapeutic strategy against its harmful effects.

Methods:

On PubMed Central, articles that contemplated studies on cadmium intoxication and associated oxidative stress with endothelial dysfunction as well as articles that reported the use of antioxidant supplementation in an attempt to prevent or avoid endothelial dysfunction induced by cadmium exposure were selected.

Results:

Most of the studies that associated cadmium intoxication with endothelial dysfunction suggested oxidative stress as the major mechanism for this damage. Furthermore, experimental studies also revealed that the administration of substances with antioxidant properties, such as ascorbic acid and curcumin, has beneficial effects on the prevention of such dysfunction, reducing reactive oxygen species within the vessels, preventing a reduction in the amount of glutathione and the increase in blood pressure observed in animals exposed to cadmium.

Conclusion:

Antioxidant therapy demonstrated to be a potential treatment to reduce cardiovascular injuries provoked by cadmium, but more studies are needed to determine the best antioxidant substance and dose to treat or avoid this complication.

[Effect of Porphyromonas gingivalis infection on atherosclerosis in apolipoprotein-E knockout mice]

OBJECTIVE

Studies have indicated that periodontal pathogen Porphyromonas gingivalis (P. gingivalis) infection may contributed to accelerate the development of atherosclerosis. The aim of this study was to investigate the effect of inflammation, oxidative stress and the mechanism on atherosclerosis in apolipoprotein-E knockout (ApoE-/-) mice with P. gingivalis infection.

METHODS

Eight-week-old male ApoE-/- mice (C57BL/6) were maintained under specific pathogen-free conditions and fed regular chow and sterile water after 1 weeks of housing. The animals were randomly divided into two groups: (a) ApoE-/- + PBS (n=8); (b) ApoE-/- + P.gingivalis strain FDC381 (n=8). Both of the groups received intravenous injections 3 times per week for 4 weeks since 8 weeks of age. The sham control group received injections with phosphate buffered saline only, while the P. gingivalis-challenged group with P.gingivalis strain FDC381at the same time. After 4 weeks, oxidative stress mediators and inflammation cytokines were analyzed by oil red O in heart, Enzyme linked immunosorbent assay (ELISA) in serum, quantitative real-time PCR and Western blot in aorta.

RESULTS

In our study, we found accelerated development of atherosclerosis and plaque formation in aorta with oil red O staining, increased oxidative stress markers [8-hydroxy-2-deoxyguanosine (8-OHdG), NADPH oxidase (NOX)-2 and NOX-4], as well as increased inflammation cytokines [interleukin (IL)-1β, IL-6 and tumor necrosis factor-α (TNF-α)] in the serum and aorta of the P. gingivalis-infected ApoE-/- mice. Compared with the control group, there was a significant increase protein level of nuclear factor-kappa B (NF-κB) in aorta after P. gingivalis infection.

CONCLUSIONS

Our results suggest that chronic intravenous infection of P. gingivalis in ApoE-/- mice could accelerate the development of atherosclerosis by disturbing the lipid profile and inducing oxidative stress and inflammation. The NF-κB signaling pathway might play a potential role in the P. gingivalis-accelerated atherogenesis.

Antioxidant Effects of PS5, a Peptidomimetic of Suppressor of Cytokine Signaling 1, in Experimental Atherosclerosis

The chronic activation of the Janus kinase/signal transducer and activator of the transcription (JAK/STAT) pathway is linked to oxidative stress, inflammation and cell proliferation. Suppressors of cytokine signaling (SOCS) proteins negatively regulate the JAK/STAT, and SOCS1 possesses a small kinase inhibitory region (KIR) involved in the inhibition of JAK kinases. Several studies showed that KIR-SOCS1 mimetics can be considered valuable therapeutics in several disorders (e.g., diabetes, neurological disorders and atherosclerosis). Herein, we investigated the antioxidant and atheroprotective effects of PS5, a peptidomimetic of KIR-SOCS1, both in vitro (vascular smooth muscle cells and macrophages) and in vivo (atherosclerosis mouse model) by analyzing gene expression, intracellular O₂^•− production and atheroma plaque progression and composition. PS5 was revealed to be able to attenuate NADPH oxidase (NOX1 and NOX4) and pro-inflammatory gene expression, to upregulate antioxidant genes and to reduce atheroma plaque size, lipid content and monocyte/macrophage accumulation. These findings confirm that KIR-SOCS1-based drugs could be excellent antioxidant agents to contrast atherosclerosis.

The Importance of Telomere Shortening for Atherosclerosis and Mortality

Telomeres are the protective end caps of chromosomes and shorten with every cell division. Short telomeres are associated with older age and adverse lifestyle factors. Leucocyte telomere length (LTL) has been proposed as a biomarker of biological age. The shortening of LTL with age is the result of the end-replication problem, environmental, and lifestyle-related factors. Epidemiologic studies have shown that LTL predicts cardiovascular disease, all-cause mortality, and death from vascular causes. Age appears to be an important co-variate that explains a substantial fraction of this effect. Although it has been proposed that short telomeres promote atherosclerosis and impair the repair of vascular lesions, existing results are inconsistent. Oxidative stress and chronic inflammation can both accelerate telomere shortening. Multiple factors, including homocysteine (HCY), vitamin B6, and vitamin B12 modulate oxidative stress and inflammation through direct and indirect mechanisms. This review provides a compact overview of telomere physiology and the utility of LTL measurements in atherosclerosis and cardiovascular disease. In addition, it summarizes existing knowledge regarding the impact of oxidative stress, inflammation, HCY, and B-vitamins on telomere function.

Reactive oxygen species in renal vascular function

Reactive oxygen species (ROS) are produced by the aerobic metabolism. The imbalance between production of ROS and antioxidant defence in any cell compartment is associated with cell damage and may play an important role in the pathogenesis of renal disease. NADPH oxidase (NOX) family is the major ROS source in the vasculature and modulates renal perfusion. Upregulation of Ang II and adenosine activates NOX via AT1R and A1R in renal microvessels, leading to superoxide production. Oxidative stress in the kidney prompts renal vascular remodelling and increases preglomerular resistance. These are key elements in hypertension, acute and chronic kidney injury, as well as diabetic nephropathy. Renal afferent arterioles (Af), the primary resistance vessel in the kidney, fine tune renal hemodynamics and impact on blood pressure. Vice versa, ROS increase hypertension and diabetes, resulting in upregulation of Af vasoconstriction, enhancement of myogenic responses and change of tubuloglomerular feedback (TGF), which further promotes hypertension and diabetic nephropathy. In the following, we highlight oxidative stress in the function and dysfunction of renal hemodynamics. The renal microcirculatory alterations brought about by ROS importantly contribute to the pathophysiology of kidney injury, hypertension and diabetes.

Bilirubin Nanomedicines for the Treatment of Reactive Oxygen Species (ROS)-Mediated Diseases

Reactive oxygen species (ROS) are chemically reactive species that are produced in cellular aerobic metabolism. They mainly include superoxide anion, hydrogen peroxide, hydroxyl radicals, singlet oxygen, ozone, and nitric oxide and are implicated in many physiological and pathological processes. Bilirubin, a cardinal pigment in the bile, has been increasingly investigated to treat cancer, diabetes, ischemia-reperfusion injury, asthma, and inflammatory bowel diseases (IBD). Indeed, bilirubin has been shown to eliminate ROS production, so it is now considered as a promising therapeutic agent for ROS-mediated diseases and can be used for the development of antioxidative nanomedicines. This review summarizes the current knowledge of the physiological mechanisms of ROS production and its role in pathological changes and focuses on discussing the antioxidative effects of bilirubin and its application in the experimental studies of nanomedicines. Previous studies have shown that bilirubin was mainly used as a responsive molecule in the microenvironment of ROS overproduction in neoplastic tissues for the development of anticancer nanodrugs; however, it could also exert powerful ROS scavenging activity in chronic inflammation and ischemia-reperfusion injury. Therefore, bilirubin, as an inartificial ROS scavenger, is expected to be used for the development of nanomedicines against more diseases due to the universality of ROS involvement in human pathological conditions.

The NADPH oxidase 4 protects vascular endothelial cells from copper oxide nanoparticles-induced oxidative stress and cell death

AIMS

Nanoparticles (NPs) exposure is associated with increased risk of cardiovascular diseases, but the underlying mechanism is still obscure. In this study, we investigated the role of NADPH oxidase 4 (NOX4) in copper oxide nanoparticles (CuONPs)-induced cytotoxicity in human umbilical vein endothelial cells (HUVECs).

MATERIALS AND METHODS

Morphology changes were examined under the microscope. Cell viability was determined by MTS assay and Calcein AM assay. Apoptosis and the levels of superoxide anion (O₂^-) and hydrogen peroxide (H₂O₂) were measured by fluorescence activated cell sorting (FACS). Oxidative stress was detected by assaying the levels of glutathione/glutathione disulfide (GSH/GSSG) and malondialdehyde (MDA). Protein expression levels were determined by western blotting.

KEY FINDINGS

We revealed that O₂^- rather than H₂O₂ was the major component of reactive oxygen species (ROS) in CuONPs-treated HUVECs. Meanwhile, CuONPs downregulated expression of O₂^--eliminating enzyme NOX4 both at mRNA and protein levels, but did not affect the expression of SOD2 and catalase. NOX4 knockdown caused more accumulation of O₂^-, and a further decrease of H₂O₂ in CuONPs-treated HUVECs, suggesting that NOX4 regulates the conversion of O₂^- to H₂O₂ in CuONPs-treated HUVECs. Furthermore, we revealed that NOX4 knockdown aggravated CuONPs-induced oxidative stress, characterized by a decrease of GSH/GSSG ratio, an increase of MDA level, and upregulation of HSPA5 and γH2AX. Finally, we showed that NOX4 knockdown exacerbated CuONPs-induced apoptotic cell death in HUVECs, indicating that NOX4 could protect ECs from CuONPs-induced cell death.

SIGNIFICANCE

Our study provides the evidence that NOX4 protects vascular endothelial cells from CuONPs-induced oxidative stress and cell death.

Breaking the vicious loop between inflammation, oxidative stress and coagulation, a novel anti-thrombus insight of nattokinase by inhibiting LPS-induced inflammation and oxidative stress

Thrombosis is a principle cause of cardiovascular disease, the leading cause of morbidity and mortality worldwide; however, the conventional anti-thrombotic approach often leads to bleeding complications despite extensive clinical management and monitoring. In view of the intense crosstalk between inflammation and coagulation, plus the contributing role of ROS to both inflammation and coagulation, it is highly desirable to develop safer anti-thrombotic agent with preserved anti-inflammatory and anti-oxidative stress activities. Nattokinase (NK) possesses many beneficial effects on cardiovascular system due to its strong thrombolytic and anticoagulant activities. Herein, we demonstrated that NK not only effectively prevented xylene-induced ear oedema in mice, but also remarkably protected against LPS-induced acute kidney injury in mice through restraining inflammation and oxidative stress, a central player in the initiation and progression of inflammation. Fascinatingly, in line with our in vivo data, NK elicited prominent anti-inflammatory activity in RAW264.7 macrophages via suppressing the LPS-induced TLR4 and NOX2 activation, thereby repressing the corresponding ROS production, MAPKs activation, and NF-κB translocation from the cytoplasm to the nucleus, where it mediates the expression of pro-inflammatory mediators, such as TNF-α, IL-6, NO, and PAI-1 in activated macrophage cells. In particular, consistent with the macrophage studies, NK markedly inhibited serum PAI-1 levels induced by LPS, thereby blocking the deposition of fibrin in the glomeruli of endotoxin-treated animals. In summary, we extended the anti-thrombus mechanism of NK by demonstrating the anti-inflammatory and anti-oxidative stress effects of NK in ameliorating LPS-activated macrophage signaling and protecting against LPS-stimulated AKI as well as glomeruler thrombus in mice, opening a comprehensive anti-thrombus strategy by breaking the vicious cycle between inflammation, oxidative stress and thrombosis.

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NK protects against LPS-induced AKI via inhibiting inflammation and oxidative stress.

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NK inhibits LPS-induced TRL4 and NOX2 activation in macrophages.

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NK inhibits inflammation and oxidative stress both in vitro and in vivo.

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NK inhibits LPS-induced PAI-I levels, thereby blocking glomerular thrombus in mice.

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NK may break the vicious loop between inflammation, oxidative stress and coagulation.

Role of reactive oxygen species in atherosclerosis: Lessons from murine genetic models

Atherosclerosis is a multifactorial chronic and inflammatory disease of medium and large arteries, and the major cause of cardiovascular morbidity and mortality worldwide. The pathogenesis of atherosclerosis involves a number of risk factors and complex events including hypercholesterolemia, endothelial dysfunction, increased permeability to low density lipoproteins (LDL) and their sequestration on extracellular matrix in the intima of lesion-prone areas. These events promote LDL modifications, particularly by oxidation, which generates acute and chronic inflammatory responses implicated in atherogenesis and lesion progression. Reactive oxygen species (ROS) (which include both free radical and non-free radical oxygen intermediates), play a key-role at each step of atherogenesis, in endothelial dysfunction, LDL oxidation, and inflammatory events involved in the initiation and development of atherosclerosis lesions. Most advanced knowledge supporting the "oxidative theory of atherosclerosis" i.e. the nature and the cellular sources of ROS and antioxidant defences, as well as the mechanisms involved in the redox balance, is based on the use of genetically engineered animals, i.e. transgenic, genetically modified, or altered for systems producing or neutralizing ROS in the vessels. This review summarizes the results obtained from animals genetically manipulated for various sources of ROS or antioxidant defences in the vascular wall, and their relevance (advance or limitation), for understanding the place and role of ROS in atherosclerosis.

Redox control of vascular biology

Redox control is lost when the antioxidant defense system cannot remove abnormally high concentrations of signaling molecules, such as reactive oxygen species (ROS). Chronically elevated levels of ROS cause oxidative stress that may eventually lead to cancer and cardiovascular and neurodegenerative diseases. In this review, we focus on redox effects in the vascular system. We pay close attention to the subcompartments of the vascular system (endothelium, smooth muscle cell layer) and give an overview of how redox changes influence those different compartments. We also review the core aspects of redox biology, cardiovascular physiology, and pathophysiology. Moreover, the topic-specific knowledgebase DES-RedoxVasc was used to develop two case studies, one focused on endothelial cells and the other on the vascular smooth muscle cells, as a starting point to possibly extend our knowledge of redox control in vascular biology.

TRIM34 attenuates colon inflammation and tumorigenesis by sustaining barrier integrity

Loss of the colonic inner mucus layer leads to spontaneously severe colitis and colorectal cancer. However, key host factors that may control the generation of the inner mucus layer are rarely reported. Here, we identify a novel function of TRIM34 in goblet cells (GCs) in controlling inner mucus layer generation. Upon DSS treatment, TRIM34 deficiency led to a reduction in Muc2 secretion by GCs and subsequent defects in the inner mucus layer. This outcome rendered TRIM34-deficient mice more susceptible to DSS-induced colitis and colitis-associated colorectal cancer. Mechanistic experiments demonstrated that TRIM34 controlled TLR signaling-induced Nox/Duox-dependent ROS synthesis, thereby promoting the compound exocytosis of Muc2 by colonic GCs that were exposed to bacterial TLR ligands. Clinical analysis revealed that TRIM34 levels in patient samples were correlated with the outcome of ulcerative colitis (UC) and the prognosis of rectal adenocarcinoma. This study indicates that TRIM34 expression in GCs plays an essential role in generating the inner mucus layer and preventing excessive colon inflammation and tumorigenesis.

NADPH Oxidase Overactivity Underlies Telomere Shortening in Human Atherosclerosis

Telomere shortening and oxidative stress are involved in the pathogenesis of atherosclerosis. Different studies have shown that phagocytic NADPH oxidase is associated with this disease. This study aimed to investigate the association between phagocytic NADPH oxidase and telomere shortening in human atherosclerosis. To assess this potential association, telomere length and phagocytic NADPH oxidase activity were determined by PCR and chemiluminescence, respectively, in a population of asymptomatic subjects free of overt clinical atherosclerosis. We also measured serum 8-hydroxy-2-deoxyguanosine (8-OHdG) levels (an index of oxidative stress) and carotid intima-media thickness (IMT), a surrogate marker of atherosclerosis. After adjusting them for age and sex, telomere length inversely correlated (p < 0.05) with NADPH oxidase-mediated superoxide production, with 8-OHdG values, and with carotid IMT. Interestingly, the asymptomatic subjects with plaques have a lower telomere length (p < 0.05), and higher values of plasma 8-OHdG and superoxide production (p < 0.05). These data were confirmed in a second population in which patients with coronary artery disease showed lower telomere length and higher 8-OHdG and superoxide production than the asymptomatic subjects. In both studies, NADPH oxidase-dependent superoxide production in phagocytic cells was only due to the specific expression of the Nox2 isoform. In conclusion, these findings suggest that phagocytic NADPH oxidase may be involved in oxidative stress-mediated telomere shortening, and that this axis may be critically involved in human atherosclerosis.

Mitochondrial dysfunction and oxidative stress in heart disease

Beyond their role as a cellular powerhouse, mitochondria are emerging as integral players in molecular signaling and cell fate determination through reactive oxygen species (ROS). While ROS production has historically been portrayed as an unregulated process driving oxidative stress and disease pathology, contemporary studies reveal that ROS also facilitate normal physiology. Mitochondria are especially abundant in cardiac tissue; hence, mitochondrial dysregulation and ROS production are thought to contribute significantly to cardiac pathology. Moreover, there is growing appreciation that medical therapies designed to mediate mitochondrial ROS production can be important strategies to ameliorate cardiac disease. In this review, we highlight evidence from animal models that illustrates the strong connections between mitochondrial ROS and cardiac disease, discuss advancements in the development of mitochondria-targeted antioxidant therapies, and identify challenges faced in bringing such therapies into the clinic.

Heart disease progression could be tackled by targeting signaling molecules that cause oxidative stress. Jennifer Kwong at Emory University School of Medicine in Atlanta, USA, and co-workers reviewed research into the role of mitochondria and their associated signaling molecules in the development of heart disease. Mitochondria are a major source of reactive oxygen species (ROS), signaling molecules involved in muscle contraction and calcium transfer in the heart, but they also destroy ROS to maintain a balance. Disruption to this balance can lead to elevated ROS, causing DNA and cellular damage, triggering disease. Animal trials using drugs to target mitochondrial ROS show promise in limiting heart disease progression. Further research is needed to determine whether this approach will work in humans and which specific heart problems might benefit from such therapies.

Galectin-3: A Harbinger of Reactive Oxygen Species, Fibrosis, and Inflammation in Pulmonary Arterial Hypertension

Significance: Pulmonary arterial hypertension (PAH) is a progressive disease arising from the narrowing of pulmonary arteries (PAs) resulting in high pulmonary arterial blood pressure and ultimately right ventricle (RV) failure. A defining characteristic of PAH is the excessive and unrelenting inward remodeling of PAs that includes increased proliferation, inflammation, and fibrosis. Critical Issues: There is no cure for PAH nor interventions that effectively arrest or reverse PA remodeling, and intensive research over the past several decades has sought to identify novel molecular mechanisms of therapeutic value. Recent Advances: Galectin-3 (Gal-3) is a carbohydrate-binding lectin remarkable for its chimeric structure, composed of an N-terminal oligomerization domain and a C-terminal carbohydrate-recognition domain. Gal-3 has been identified as a regulator of numerous changes in cell behavior that contributes to aberrant PA remodeling, including cell proliferation, inflammation, and fibrosis, but its role in PAH has remained poorly understood until recently. In contrast, pathological roles for Gal-3 have been proposed in cancer and inflammatory and fibroproliferative disorders, such as pulmonary vascular and cardiac fibrosis. Herein, we summarize the recent literature on the role of Gal-3 in the development of PAH. We provide experimental evidence supporting the ability of Gal-3 to influence reactive oxygen species production, NADPH oxidase enzyme expression, and redox signaling, which have been shown to contribute to both vascular remodeling and increased pulmonary arterial pressure. Future Directions: While several preclinical studies suggest that Gal-3 promotes hypertensive pulmonary vascular remodeling, the clinical significance of Gal-3 in human PAH remains to be established. Antioxid. Redox Signal. 00, 000-000.

Critical role of histone demethylase Jumonji domain-containing protein 3 in the regulation of neointima formation following vascular injury

Aims

Jumonji domain-containing protein 3 (JMJD3), also called lysine specific demethylase 6B (KDM6b), is an inducible histone demethylase which plays an important role in many biological processes, however, its function in vascular remodelling remains unknown. We aim to demonstrate that JMJD3 mediates vascular neointimal hyperplasia following carotid injury, and proliferation and migration in platelet-derived growth factor BB (PDGF-BB)-induced vascular smooth muscle cells (VSMCs).

Methods and results

By using both genetic and pharmacological approaches, our study provides the first evidence that JMJD3 controls PDGF-BB-induced VSMCs proliferation and migration. Furthermore, our in vivo mouse and rat intimal thickening models demonstrate that JMJD3 is a novel mediator of neointima formation based on its mediatory effects on VSMCs proliferation, migration, and phenotypic switching. We further show that JMJD3 ablation by small interfering RNA or inhibitor GSK J4 can suppress the expression of NADPH oxidase 4 (Nox4), which is correlated with H3K27me3 enrichment around the gene promoters. Besides, deficiency of JMJD3 and Nox4 prohibits autophagic activation, and subsequently attenuates neointima and vascular remodelling following carotid injury. Above all, the increased expression of JMJD3 and Nox4 is further confirmed in human atherosclerotic arteries plaque specimens.

Conclusions

JMJD3 is a novel factor involved in vascular remodelling. Deficiency of JMJD3 reduces neointima formation after vascular injury by a mechanism that inhibits Nox4-autophagy signalling activation, and suggesting JMJD3 may serve as a perspective target for the prevention and treatment of vascular diseases.

Oxidative Stress and Inflammation, Key Targets of Atherosclerotic Plaque Progression and Vulnerability: Potential Impact of Physical Activity

Atherosclerosis, a complex cardiovascular disease, is a leading cause of mortality and morbidity worldwide. Oxidative stress and inflammation are both involved in the development of atherosclerotic plaque as they increase the biological processes associated with this pathology, such as endothelial dysfunction and macrophage recruitment and adhesion. Atherosclerotic plaque rupture leading to major ischemic events is the result of vulnerable plaque progression, which is a result of the detrimental effect of oxidative stress and inflammation on risk factors for atherosclerotic plaque rupture, such as intraplaque hemorrhage, neovascularization, and fibrous cap thickness. Thus, both are key targets for primary and secondary interventions. It is well recognized that chronic physical activity attenuates oxidative stress in healthy subjects via the improvement of antioxidant enzyme capacities and inflammation via the enhancement of anti-inflammatory molecules. Moreover, it was recently shown that chronic physical activity could decrease oxidative stress and inflammation in atherosclerotic patients. The aim of this review is to summarize the role of oxidative stress and inflammation in atherosclerosis and the results of therapeutic interventions targeting them in both preclinical and clinical studies. The effects of chronic physical activity on these two key processes are then reviewed in vulnerable atherosclerotic plaques in both coronary and carotid arteries.

Black Sorghum Phenolic Extract Regulates Expression of Genes Associated with Oxidative Stress and Inflammation in Human Endothelial Cells

Oxidative stress is one of the primary factors leading to endothelial dysfunction, a major underlying cause of vascular disorders. This study aims to understand the key signalling pathways regulated by sorghum (Shawaya short black 1 variety; characterised to be very high in its antioxidant activity) under oxidative stress in endothelial cells. Human umbilical vein endothelial cells (HUVECs) were pre-treated with non-cytotoxic concentrations of phenolic-rich black sorghum extract (BSE) prior to induction of oxidative stress using hydrogen peroxide (H₂O₂). Treatment with BSE upregulated the expression of heme oxygenase 1 (HO1) and endothelial nitric oxide synthase (eNOS) and downregulated the levels of NADPH oxidase 4 (NOX4). BSE treatment significantly reduced the expression of pro-inflammatory mediators such as monocyte chemoattractant protein 1 (MCP1) and intracellular adhesion molecule 1 (ICAM1). Results from this study suggest that phenolic-rich BSE may reduce oxidative stress by regulating pro- and antioxidant signalling pathways and the expression of inflammatory mediators linked to endothelial dysfunction under oxidative stress.

Histone Acetyltransferase-Dependent Pathways Mediate Upregulation of NADPH Oxidase 5 in Human Macrophages under Inflammatory Conditions: A Potential Mechanism of Reactive Oxygen Species Overproduction in Atherosclerosis

Histone acetylation plays a major role in epigenetic regulation of gene expression. Monocyte-derived macrophages express functional NADPH oxidase 5 (Nox5) that contributes to oxidative stress in atherogenesis. The mechanisms of Nox5 regulation are not entirely elucidated. The aim of this study was to investigate the expression pattern of key histone acetyltransferase subtypes (p300, HAT1) in human atherosclerosis and to determine their role in mediating the upregulation of Nox5 in macrophages under inflammatory conditions. Human nonatherosclerotic and atherosclerotic tissue samples were collected in order to determine the expression of p300 and HAT1 isoforms, H3K27ac, and Nox5. In vitro determinations were done on human macrophages exposed to lipopolysaccharide in the absence or presence of histone acetyltransferase inhibitors. Western blot, immunohistochemistry, immunofluorescence, real-time PCR, transfection, and chromatin immunoprecipitation assay were employed. The protein levels of p300 and HAT1 isoforms, H3K27ac, and Nox5 were found significantly elevated in human atherosclerotic specimens. Immunohistochemistry/immunofluorescence staining revealed that p300, HAT1, H3K27ac, H3K9ac, and Nox5 proteins were colocalized in the area of CD45⁺/CD68⁺ immune cells and lipid-rich deposits within human atherosclerotic plaques. Lipopolysaccharide induced the levels of HAT1, H3K27ac, H3K9ac, and Nox5 and the recruitment of p300 and HAT1 at the sites of active transcription within Nox5 gene promoter in cultured human macrophages. Pharmacological inhibition of histone acetyltransferase significantly reduced the Nox5 gene and protein expression in lipopolysaccharide-challenged macrophages. The overexpression of p300 or HAT1 enhanced the Nox5 gene promoter activity. The histone acetyltransferase system is altered in human atherosclerosis. Under inflammatory conditions, HAT subtypes control Nox5 overexpression in cultured human macrophages. The data suggest the existence of a new epigenetic mechanism underlying oxidative stress in atherosclerosis.

Carnosine Decreases PMA-Induced Oxidative Stress and Inflammation in Murine Macrophages

Carnosine is an endogenous dipeptide composed of β-alanine and L-histidine. This naturally occurring molecule is present at high concentrations in several mammalian excitable tissues such as muscles and brain, while it can be found at low concentrations in a few invertebrates. Carnosine has been shown to be involved in different cellular defense mechanisms including the inhibition of protein cross-linking, reactive oxygen and nitrogen species detoxification as well as the counteraction of inflammation. As a part of the immune response, macrophages are the primary cell type that is activated. These cells play a crucial role in many diseases associated with oxidative stress and inflammation, including atherosclerosis, diabetes, and neurodegenerative diseases. In the present study, carnosine was first tested for its ability to counteract oxidative stress. In our experimental model, represented by RAW 264.7 macrophages challenged with phorbol 12-myristate 13-acetate (PMA) and superoxide dismutase (SOD) inhibitors, carnosine was able to decrease the intracellular concentration of superoxide anions (O2-•) as well as the expression of Nox1 and Nox2 enzyme genes. This carnosine antioxidant activity was accompanied by the attenuation of the PMA-induced Akt phosphorylation, the down-regulation of TNF-α and IL-6 mRNAs, and the up-regulation of the expression of the anti-inflammatory mediators IL-4, IL-10, and TGF-β1. Additionally, when carnosine was used at the highest dose (20 mM), there was a generalized amelioration of the macrophage energy state, evaluated through the increase both in the total nucleoside triphosphate concentrations and the sum of the pool of intracellular nicotinic coenzymes. Finally, carnosine was able to decrease the oxidized (NADP+)/reduced (NADPH) ratio of nicotinamide adenine dinucleotide phosphate in a concentration dependent manner, indicating a strong inhibitory effect of this molecule towards the main source of reactive oxygen species in macrophages. Our data suggest a multimodal mechanism of action of carnosine underlying its beneficial effects on macrophage cells under oxidative stress and inflammation conditions.

Reactive Oxygen Species (ROS), Intimal Thickening, and Subclinical Atherosclerotic Disease

Arteriosclerosis causes significant morbidity and mortality worldwide. Central to this process is the development of subclinical non-atherosclerotic intimal lesions before the appearance of pathologic intimal thickening and advanced atherosclerotic plaques. Intimal thickening is associated with several risk factors, including oxidative stress due to reactive oxygen species (ROS), inflammatory cytokines and lipid. The main ROS producing systems in-vivo are reduced nicotinamide dinucleotide phosphate (NADPH) oxidase (NOX). ROS effects are context specific. Exogenous ROS induces apoptosis and senescence, whereas intracellular ROS promotes stem cell differentiation, proliferation, and migration. Lineage tracing studies using murine models of subclinical atherosclerosis have revealed the contributory role of medial smooth muscle cells (SMCs), resident vascular stem cells, circulating bone-marrow progenitors and endothelial cells that undergo endothelial-mesenchymal-transition (EndMT). This review will address the putative physiological and patho-physiological roles of ROS in controlling vascular cell fate and ROS contribution to vascular regeneration and disease progression.

Increased mitochondrial NADPH oxidase 4 (NOX4) expression in aging is a causative factor in aortic stiffening

Aging is characterized by increased aortic stiffness, an early, independent predictor and cause of cardiovascular disease. Oxidative stress from excess reactive oxygen species (ROS) production increases with age. Mitochondria and NADPH oxidases (NOXs) are two major sources of ROS in cardiovascular system. We showed previously that increased mitochondrial ROS levels over a lifetime induce aortic stiffening in a mouse oxidative stress model. Also, NADPH oxidase 4 (NOX4) expression and ROS levels increase with age in aortas, aortic vascular smooth muscle cells (VSMCs) and mitochondria, and are correlated with age-associated aortic stiffness in hypercholesterolemic mice. The present study investigated whether young mice (4 months-old) with increased mitochondrial NOX4 levels recapitulate vascular aging and age-associated aortic stiffness. We generated transgenic mice with low (Nox4TG605; 2.1-fold higher) and high (Nox4TG618; 4.9-fold higher) mitochondrial NOX4 expression. Young Nox4TG618 mice showed significant increase in aortic stiffness and decrease in phenylephrine-induced aortic contraction, but not Nox4TG605 mice. Increased mitochondrial oxidative stress increased intrinsic VSMC stiffness, induced aortic extracellular matrix remodeling and fibrosis, a leftward shift in stress-strain curves, decreased volume compliance and focal adhesion turnover in Nox4TG618 mice. Nox4TG618 VSMCs phenocopied other features of vascular aging such as increased DNA damage, increased premature and replicative senescence and apoptosis, increased proinflammatory protein expression and decreased respiration. Aortic stiffening in young Nox4TG618 mice was significantly blunted with mitochondrial-targeted catalase overexpression. This demonstration of the role of mitochondrial oxidative stress in aortic stiffness will galvanize search for new mitochondrial-targeted therapeutics for treatment of age-associated vascular dysfunction.

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Aortic stiffness in aging is associated with increased mitochondrial NOX4 levels.

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Young mitochondrial Nox4 overexpressing transgenic mice phenocopy aortic stiffness.

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Nox4 transgenic mice show increased VSMC stiffness, aortic remodeling and fibrosis.

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Nox4 transgenic mouse VSMC show DNA damage, senescence, apoptosis and inflammation.

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High mitochondrial catalase levels blunt aortic stiffness in Nox4 transgenic mice.

Role of smooth muscle cells in vascular calcification: implications in atherosclerosis and arterial stiffness

Vascular calcification is associated with a significant increase in all-cause mortality and atherosclerotic plaque rupture. Calcification has been determined to be an active process driven in part by vascular smooth muscle cell (VSMC) transdifferentiation within the vascular wall. Historically, VSMC phenotype switching has been viewed as binary, with the cells able to adopt a physiological contractile phenotype or an alternate ‘synthetic’ phenotype in response to injury. More recent work, including lineage tracing has however revealed that VSMCs are able to adopt a number of phenotypes, including calcific (osteogenic, chondrocytic, and osteoclastic), adipogenic, and macrophagic phenotypes. Whilst the mechanisms that drive VSMC differentiation are still being elucidated it is becoming clear that medial calcification may differ in several ways from the intimal calcification seen in atherosclerotic lesions, including risk factors and specific drivers for VSMC phenotype changes and calcification. This article aims to compare and contrast the role of VSMCs in driving calcification in both atherosclerosis and in the vessel media focusing on the major drivers of calcification, including aging, uraemia, mechanical stress, oxidative stress, and inflammation. The review also discusses novel findings that have also brought attention to specific pro- and anti-calcifying proteins, extracellular vesicles, mitochondrial dysfunction, and a uraemic milieu as major determinants of vascular calcification.

NADPH oxidase 4 and its role in the cardiovascular system

The heart relies on complex mechanisms that provide adequate myocardial oxygen supply in order to maintain its contractile function. At the cellular level, oxygen undergoes one electron reduction to superoxide through the action of different types of oxidases (e.g. xanthine oxidases, uncoupled nitric oxide synthases, NADPH oxidases or NOX). Locally generated oxygen-derived reactive species (ROS) are involved in various signaling pathways including cardiac adaptation to different types of physiological and pathophysiological stresses (e.g. hypoxia or overload). The specific effects of ROS and their regulation by oxidases are dependent on the amount of ROS generated and their specific subcellular localization. The NOX family of NADPH oxidases is a main source of ROS in the heart. Seven distinct Nox isoforms (NOX1–NOX5 and DUOX1 and 2) have been identified, of which NOX1, 2, 4 and 5 have been characterized in the cardiovascular system. For the purposes of this review, we will focus on the effects of NADPH oxidase 4 (NOX4) in the heart.

Apocynin and Tempol ameliorate dietary sodium-induced declines in cutaneous microvascular function in salt-resistant humans

It has previously been shown that high dietary salt impairs vascular function independent of changes in blood pressure. Rodent studies suggest that NADPH-derived reactive oxygen species mediate the deleterious effect of high salt on the vasculature, and here we translate these findings to humans. Twenty-nine healthy adults (34 ± 2 yr) participated in a controlled feeding study. Participants completed 7 days of a low-sodium diet (LS; 20 mmol sodium/day) and 7 days of a high-sodium diet (HS; 300 mmol sodium/day) in random order. All participants were salt resistant, defined as a ≤5-mmHg change in 24-h mean BP determined while on the LS and HS diets. Laser Doppler flowmetry was used to assess cutaneous vasodilation in response to local heating (42°C) during local delivery of Ringer's (n = 29), 20 mM ascorbic acid (AA; n = 29), 10 µM Tempol (n = 22), and 100 µM apocynin (n = 22). Additionally, endothelial cells were obtained in a subset of participants from an antecubital vein and stained for nitrotyrosine (n = 14). Cutaneous vasodilation was attenuated by the HS diet compared with LS [LS 93.0 ± 2.2 vs. HS 86.8 ± 2.0 percentage of maximal cutaneous vascular conductance (%CVCmax); P < 0.05] and was restored by AA during the HS diet (AA 90.7 ± 1.2 %CVCmax; P < 0.05 vs. HS). Cutaneous vasodilation was also restored with the local infusion of both apocynin (P < 0.01) and Tempol (P < 0.05) on the HS diet. Nitrotyrosine expression was increased on the HS diet compared with LS (P < 0.05). These findings provide direct evidence of dietary sodium-induced endothelial cell oxidative stress and suggest that NADPH-derived reactive oxygen species contribute to sodium-induced declines in microvascular function. NEW & NOTEWORTHY High-sodium diets have deleterious effects on vascular function, likely mediating, in part, the increased cardiovascular risk associated with a high sodium intake. Local infusion of apocynin and Tempol improved microvascular function in salt-resistant adults on a high-salt diet, providing evidence that reactive oxygen species contribute to impairments in microvascular function from high salt. This study provides insight into the blood pressure-independent mechanisms by which dietary sodium impairs vascular function. Listen to this article's corresponding podcast at https://ajpheart.podbean.com/e/dietary-sodium-oxidative-stress-and-microvascular-function/ .

Regulation of Smooth Muscle Cell Proliferation by NADPH Oxidases in Pulmonary Hypertension

Hyperproliferation of pulmonary arterial smooth muscle cells is a key component of vascular remodeling in the setting of pulmonary hypertension (PH). Numerous studies have explored factors governing the changes in smooth muscle cell phenotype that lead to the increased wall thickness, and have identified various potential candidates. A role for reactive oxygen species (ROS) has been well documented in PH. ROS can be generated from a variety of sources, including mitochondria, uncoupled nitric oxide synthase, xanthine oxidase, and reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. In this article, we will review recent data supporting a role for ROS generated from NADPH oxidases in promoting pulmonary arterial smooth muscle cell proliferation during PH.

Poldip2 knockdown inhibits vascular smooth muscle proliferation and neointima formation by regulating the expression of PCNA and p21

Polymerase delta-interacting protein 2 (Poldip2) is a multi-functional protein with numerous roles in the vasculature, including the regulation of cell apoptosis and migration, as well as extracellular matrix deposition; however, its role in VSMC proliferation and neointimal formation is unknown. In this study, we investigated the role of Poldip2 in intraluminal wire-injury induced neointima formation and proliferation of vascular smooth muscle cells in vitro and in vivo. Poldip2 expression was observed in the intima and media of human atherosclerotic arteries, where it colocalized with proliferating cell nuclear antigen (PCNA). Wire injury of femoral arteries of Poldip2^+/+ mice induced robust neointimal formation after 2 weeks, which was impaired in Poldip2^+/‒ mice. PCNA expression was significantly reduced and expression of the cell cycle inhibitor p21 was significantly increased in wire-injured arteries of Poldip2^+/‒ animals compared to wild-type controls. No difference was observed in apoptosis. Downregulation of Poldip2 in rat aortic smooth muscle cells significantly reduced serum-induced proliferation and PCNA expression, but upregulated p21 expression. Downregulation of p21 using siRNA reversed the inhibition of proliferation induced by knockdown of Poldip2. These results indicate that Poldip2 plays a critical role in the proliferation of VSMCs.

Targeting Oxidative Stress Using Nanoparticles as a Theranostic Strategy for Cardiovascular Diseases

SIGNIFICANCE

Nanomedicine is an application of nanotechnology that provides solutions to unmet medical challenges. The unique features of nanoparticles, such as their small size, modifiable components, and diverse functionality, make them attractive and suitable materials for novel diagnostic, therapeutic, or theranostic applications. Cardiovascular diseases (CVDs) are the major cause of noncommunicable illness in both developing and developed countries. Nanomedicine offers novel theranostic options for the treatment of CVDs. Recent Advances: Many innovative nanoparticles to target reactive oxygen species (ROS) have been developed. In this article, we review the characteristics of nanoparticles that are responsive to ROS, their limitations, and their potential clinical uses. Significant advances made in diagnosis of atherosclerosis and treatment of acute coronary syndrome using nanoparticles are discussed.

CRITICAL ISSUES

Although there is a tremendous potential for the nanoparticle applications in medicine, their safety should be considered while using in humans. We discuss the challenges that may be encountered with some of the innovative nanoparticles used in CVDs.

FUTURE DIRECTIONS

The unique properties of nanoparticles offer novel diagnostic tool and potential therapeutic strategies. However, nanomedicine is still in its infancy, and further in-depth studies are needed before wide clinical application is achieved.

Sources of Vascular Nitric Oxide and Reactive Oxygen Species and Their Regulation

Nitric oxide (NO) is a small free radical with critical signaling roles in physiology and pathophysiology. The generation of sufficient NO levels to regulate the resistance of the blood vessels and hence the maintenance of adequate blood flow is critical to the healthy performance of the vasculature. A novel paradigm indicates that classical NO synthesis by dedicated NO synthases is supplemented by nitrite reduction pathways under hypoxia. At the same time, reactive oxygen species (ROS), which include superoxide and hydrogen peroxide, are produced in the vascular system for signaling purposes, as effectors of the immune response, or as byproducts of cellular metabolism. NO and ROS can be generated by distinct enzymes or by the same enzyme through alternate reduction and oxidation processes. The latter oxidoreductase systems include NO synthases, molybdopterin enzymes, and hemoglobins, which can form superoxide by reduction of molecular oxygen or NO by reduction of inorganic nitrite. Enzymatic uncoupling, changes in oxygen tension, and the concentration of coenzymes and reductants can modulate the NO/ROS production from these oxidoreductases and determine the redox balance in health and disease. The dysregulation of the mechanisms involved in the generation of NO and ROS is an important cause of cardiovascular disease and target for therapy. In this review we will present the biology of NO and ROS in the cardiovascular system, with special emphasis on their routes of formation and regulation, as well as the therapeutic challenges and opportunities for the management of NO and ROS in cardiovascular disease.

Carnosine Prevents Aβ-Induced Oxidative Stress and Inflammation in Microglial Cells: A Key Role of TGF-β1

Carnosine (β-alanyl-L-histidine), a dipeptide, is an endogenous antioxidant widely distributed in excitable tissues like muscles and the brain. Carnosine is involved in cellular defense mechanisms against oxidative stress, including the inhibition of amyloid-beta (Aβ) aggregation and the scavenging of reactive species. Microglia play a central role in the pathogenesis of Alzheimer's disease, promoting neuroinflammation through the secretion of inflammatory mediators and free radicals. However, the effects of carnosine on microglial cells and neuroinflammation are not well understood. In the present work, carnosine was tested for its ability to protect BV-2 microglial cells against oligomeric Aβ1-42-induced oxidative stress and inflammation. Carnosine prevented cell death in BV-2 cells challenged with Aβ oligomers through multiple mechanisms. Specifically, carnosine lowered the oxidative stress by decreasing NO and O₂-• intracellular levels as well as the expression of iNOS and Nox enzymes. Carnosine also decreased the secretion of pro-inflammatory cytokines such as IL-1β, simultaneously rescuing IL-10 levels and increasing the expression and the release of TGF-β1. Carnosine also prevented Aβ-induced neurodegeneration in mixed neuronal cultures challenged with Aβ oligomers, and these neuroprotective effects were completely abolished by SB431542, a selective inhibitor of the type-1 TGF-β receptor. Our data suggest a multimodal mechanism of action of carnosine underlying its protective effects on microglial cells against Aβ toxicity with a key role of TGF-β1 in mediating these protective effects.

Oxidative Stress in Cardiac Tissue of Patients Undergoing Coronary Artery Bypass Graft Surgery: The Effects of Overweight and Obesity

Background

Obesity is one of the major cardiovascular risk factors and is associated with oxidative stress and myocardial dysfunction. We hypothesized that obesity affects cardiac function and morbidity by causing alterations in enzymatic redox patterns.

Methods

Sixty-one patients undergoing coronary artery bypass grafting (CABG) were included in the study. Excessive right atrial myocardial tissue emerging from the operative connection to the extracorporeal circulation was harvested. Patients were assigned to control (n = 19, body mass index (BMI): <25 kg/m²), overweight (n = 25, 25 kg/m² < BMI < 30 kg/m²), or obese (n = 17, BMI: >30 kg/m²) groups. Oxidative enzyme systems were studied directly in the cardiac muscles of patients undergoing CABG who were grouped according to BMI. Molecular biological methods and high-performance liquid chromatography were used to detect the expression and activity of oxidative enzymes and the formation of reactive oxygen species (ROS).

Results

We found increased levels of ROS and increased expression of ROS-producing enzymes (i.e., p47phox, xanthine oxidase) and decreased antioxidant defense mechanisms (mitochondrial aldehyde dehydrogenase, heme oxygenase-1, and eNOS) in line with elevated inflammatory markers (vascular cell adhesion molecule-1) in the right atrial myocardial tissue and by trend also in serum (sVCAM-1 and CCL5/RANTES).

Conclusion

Increasing BMI in patients undergoing CABG is related to altered myocardial redox patterns, which indicates increased oxidative stress with inadequate antioxidant compensation. These changes suggest that the myocardium of obese patients suffering from coronary artery disease is more susceptible to cardiomyopathy and possible damage by ischemia and reperfusion, for example, during cardiac surgery.

Attenuation of utero-toxicity, metabolic dysfunction and inflammation by soy protein concentrate in rats exposed to fluoridated water: consequence of hyperlipidemia in parallel with hypohomocysteinemia

Lipid peroxidation and ROS generation are the pathogenesis of chronic fluoride toxicity, and its detrimental effects on human reproduction are noted drastically. The aim of the present study was to elucidate the defensive effects of soy protein concentrate (SPC) against sodium fluoride (NaF)-induced uterine dysfunction at biochemical and histological level. Rats were randomly distributed into four groups as control, NaF-treated (200 ppm), and SPC co-administered groups (20 mg and 40 mg/ 100 g body weight) for 16 days. SPC reversed the toxic effects of NaF. SPC significantly ameliorated the NaF-induced alterations of the antioxidant system in the uterus by decreasing lipid peroxidation products and by increasing antioxidant activities. SPC significantly counteracted the adverse effects of NaF on serum level of lactate dehydrogenase (LDH) and inflammatory markers Interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α) and nuclear factor kappa-B (NF-κB). Our results also explored that lipid profile was meaningfully altered due to NaF and also focused a diminution of circulating homocysteine (Hcy) and altered lipid profiles along with a diminished quantity of serum B₁₂ and B₉. However, both the doses of SPC reverted back serum levels of B₁₂, B₉, and Hcy status in similar fashion along with its corrective action on lipid profile. NaF-treated group exhibited a marked degree of reduction in the weights of ovary and uterus with an alteration of normal tissue histology and significant diminution in serum estradiol (ES) levels without fluctuating uterine estradiol receptor-α (ER-α). However, SPC restored the normal tissue histoarchitecture and also increased the functional efficiency and expression of the ER-α receptor by overturning the ES levels in NaF-treated rats. Moreover, both the doses of SPC were effective against NaF-induced alterations, although 40 mg SPC/100 g body weight had better efficacy in ameliorating the NaF-induced adverse effects on the uterus and ovary.

Sex differences in the mechanisms mediating blunted cutaneous microvascular function in young black men and women

The black population exhibits attenuated vasodilatory function across their lifespan, yet little is known regarding the mechanisms of this impairment. Recent evidence suggests a potential role for oxidative stress. Therefore, we tested the hypothesis that NADPH oxidase (NOX) and/or xanthine oxidase (XO) contribute to blunted nitric oxide (NO)-mediated cutaneous microvascular function in young black adults. In 30 white and black subjects (8 men and 7 women in each group), local heating was performed while NOX and XO were inhibited by apocynin and allopurinol, respectively, via intradermal microdialysis. The plateau in cutaneous vascular conductance (red blood cell flux/mean arterial pressure) during 39°C local heating at each site was compared with a control site perfused with lactated Ringer solution. Subsequent inhibition of NO synthase via N^ω-nitro-l-arginine methyl ester allowed for quantification of the NO contribution to vasodilation during heating. Black individuals, relative to white individuals, had a blunted cutaneous vascular conductance plateau at the control site (45 ± 9 vs. 68 ± 13%max, P < 0.001) that was increased by both apocynin (61 ± 15%max, P < 0.001) and allopurinol (58 ± 17%max, P = 0.005). Black men and black women had similar responses to heating at the control site ( P = 0.99), yet apocynin and allopurinol increased this response only in black men (both P < 0.001 vs. control). The NO contribution was also increased via apocynin and allopurinol exclusively in black men. These findings suggest that cutaneous microvascular function is reduced because of NOX and XO activity in black men but not black women, identifying a novel sex difference in the mechanisms that contribute to blunted vascular responses in the black population. NEW & NOTEWORTHY We demonstrate that cutaneous microvascular responses to local heating are consistently reduced in otherwise healthy young black men and women relative to their white counterparts. Inhibition of NADPH oxidase and xanthine oxidase via apocynin and allopurinol, respectively, augments microvascular function in black men but not black women. These data reveal clear sex differences in the mechanisms underlying the racial disparity in cutaneous microvascular function.

Lipoproteins and Cardiovascular Redox Signaling: Role in Atherosclerosis and Coronary Disease

SIGNIFICANCE

Lipoproteins, such as low-density lipoprotein, play a causal role in the development of atherosclerosis and coronary disease. Recent Advances: Lipoproteins can stimulate vascular production of reactive oxygen species, which act as important signaling molecules in the cardiovascular system contributing to the pathophysiology of endothelial dysfunction, hypertension, and atherosclerosis.

CRITICAL ISSUES

Modified lipoproteins have emerged as important regulators of redox signaling, such as oxidized or carbamylated low-density lipoprotein or modified high-density lipoproteins, that contain oxidized lipids, an altered protein cargo, and associated small molecules, such as symmetric dimethylarginine.

FUTURE DIRECTIONS

In this review, we provide an overview on signaling pathways stimulated by modified lipoproteins in the cardiovascular system and their potential role in cardiovascular disease development. Moreover, we highlight novel aspects of how gut microbiome-related mechanisms-a growing research field-may contribute to lipoprotein modification with subsequent impact on cardiovascular redox signaling. Antioxid. Redox Signal. 29, 337-352.

Effect of mate tea (Ilex paraguariensis) on the expression of the leukocyte NADPH oxidase subunit p47phox and on circulating inflammatory cytokines in healthy men: a pilot study

Increased superoxide production by phagocytic NADPH oxidase has been associated with inflammatory conditions. Growing evidences suggest that dietary polyphenols may modulate the expression of NADPH oxidase subunits. Herein, we examined whether soluble mate tea (SMT) consumption - a polyphenol-rich beverage - affects the expression of the leukocyte NADPH oxidase protein p47^phox and/or circulating biomarkers of inflammation and antioxidant biomarkers in humans. In a two-phase study, nine men were requested to drink water (control) for 8 d and then follow a second 8-d period drinking SMT. Blood samples were analysed for p47^phox protein in CD16⁺/CD14^- cells, interleukin (IL)-1β (IL-1β), tumour necrosis factor-alpha (TNF-α), IL-6, total phenols, and reduced and oxidised glutathione (GSH and GSSG, respectively) after each study phase. After SMT intake, CD16⁺/CD14^- cells' p47^phox protein and serum TNF-α and IL-6 levels were significantly attenuated (P < .05) while plasma phenolic compounds and blood GSH:GSSG ratio were significantly enhanced (P < .05). Consumption of SMT favourably affected leukocytes' p47^phox expression and inflammatory cytokine and antioxidants levels in peripheral blood, which may help decrease oxidative stress and low-grade inflammation.

Endothelium as a Potential Target for Treatment of Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) was previously ascribed to weaken defective medial arterial/adventitial layers, for example, smooth muscle/fibroblast cells. Therefore, besides surgical repair, medications targeting the medial layer to strengthen the aortic wall are the most feasible treatment strategy for AAA. However, so far, it is unclear whether such drugs have any beneficial effect on AAA prognosis, rate of aneurysm growth, rupture, or survival. Notably, clinical studies have shown that AAA is highly associated with endothelial dysfunction in the aged population. Additionally, animal models of endothelial dysfunction and endothelial nitric oxide synthase (eNOS) uncoupling had a very high rate of AAA formation, indicating there is crucial involvement of the endothelium and a possible pharmacological solution targeting the endothelium in AAA treatment. Endothelial cells have been found to trigger vascular wall remodeling by releasing proteases, or recruiting macrophages along with other neutrophils, into the medial layer. Moreover, inflammation and oxidative stress of the arterial wall were induced by endothelial dysfunction. Interestingly, there is a paradoxical differential correlation between diabetes and aneurysm formation in retinal capillaries and the aorta. Deciphering the significance of such a difference may explain current unsuccessful AAA medications and offer a solution to this treatment challenge. It is now believed that AAA and atherosclerosis are two separate but related diseases, based on their different clinical patterns which have further complicated the puzzle. Therefore, a thorough investigation of the interaction between endothelium and medial/adventitial layer may provide us a better understanding and new perspective on AAA formation, especially after taking into account the importance of endothelium in the development of AAA. Moreover, a novel medication strategy replacing the currently used, but suboptimal treatments for AAA, could be informed with this analysis.

Polymorphism related to cardiovascular risk in hemodialysis subjects: a systematic review

Cardiovascular disease (CVD) is one of the leading causes of mortality in hemodialysis (HD) subjects. In addition to the traditional risk factors that are common in these individuals, genetic factors are also involved, with emphasis on single nucleotide polymorphs (SNPs). In this context, the present study aims to systematically review the studies that investigated the polymorphisms associated with cardiovascular risk in this population. In general, the SNPs present in HD individuals are those of genes related to inflammation, oxidative stress and vascular calcification, also able of interfering in the cardiovascular risk of this population. In addition, polymorphisms in genes related to recognized risk factors for CVD, such as dyslipidemia, arterial hypertension and left ventricular hypertrophy, also influence cardiovascular morbidity and mortality.

The Adverse Effects of Environmental Noise Exposure on Oxidative Stress and Cardiovascular Risk

Epidemiological studies have provided evidence that traffic noise exposure is linked to cardiovascular diseases such as arterial hypertension, myocardial infarction, and stroke. Noise is a nonspecific stressor that activates the autonomous nervous system and endocrine signaling. According to the noise reaction model introduced by Babisch and colleagues, chronic low levels of noise can cause so-called nonauditory effects, such as disturbances of activity, sleep, and communication, which can trigger a number of emotional responses, including annoyance and subsequent stress. Chronic stress in turn is associated with cardiovascular risk factors, comprising increased blood pressure and dyslipidemia, increased blood viscosity and blood glucose, and activation of blood clotting factors, in animal models and humans. Persistent chronic noise exposure increases the risk of cardiometabolic diseases, including arterial hypertension, coronary artery disease, diabetes mellitus type 2, and stroke. Recently, we demonstrated that aircraft noise exposure during nighttime can induce endothelial dysfunction in healthy subjects and is even more pronounced in coronary artery disease patients. Importantly, impaired endothelial function was ameliorated by acute oral treatment with the antioxidant vitamin C, suggesting that excessive production of reactive oxygen species contributes to this phenomenon. More recently, we introduced a novel animal model of aircraft noise exposure characterizing the underlying molecular mechanisms leading to noise-dependent adverse oxidative stress-related effects on the vasculature. With the present review, we want to provide an overview of epidemiological, translational clinical, and preclinical noise research addressing the nonauditory, adverse effects of noise exposure with focus on oxidative stress. Antioxid. Redox Signal. 28, 873-908.

Design, synthesis, and biological evaluation of inhibitors of the NADPH oxidase, Nox4

NADPH oxidases (Nox enzymes) are critical mediators of both physiologic and pathophysiologic processes. Nox enzymes catalyze NADPH-dependent generation of reactive oxygen species (ROS), including superoxide and hydrogen peroxide. Until recently, Nox4 was proposed to be involved exclusively in normal physiologic functions. Compelling evidence, however, suggests that Nox4 plays a critical role in fibrosis, as well as a host of pathologies and diseases. These considerations led to a search for novel, small molecule inhibitors of this important enzyme. Ultimately, a series of novel tertiary sulfonylureas (23-25) was designed using pharmacophore modeling, synthesized, and evaluated for inhibition of Nox4-dependent signaling.

NOX4 downregulation leads to senescence of human vascular smooth muscle cells

Senescence is a stress response characterized by an irreversible growth arrest and alterations in certain cell functions. It is believed that both double-strand DNA breaks (DSB) and increased ROS level are the main culprit of senescence. Excessive ROS production is also particularly important in the development of a number of cardiovascular disorders. In this context the involvement of professional ROS-producing enzymes, NADPH oxidases (NOX), was postulated. In contrary to the common knowledge, we have shown that not only increased ROS production but also diminished ROS level could be involved in the induction of senescence.

Accordingly, our studies revealed that stress-induced premature senescence (SIPS) of vascular smooth muscle cells (VSMCs) induced by doxorubicin or H₂O₂, correlates with increased level of DSB and ROS. On the other hand, both SIPS and replicative senescence were accompanied by diminished expression of NOX4. Moreover, inhibition of NOX activity or decrease of NOX4 expression led to permanent growth arrest of VSMCs and secretion of interleukins and VEGF. Interestingly, cells undergoing senescence due to NOX4 depletion neither acquired DSB nor activated DNA damage response. Instead, transient induction of the p27, upregulation of HIF-1alpha, decreased expression of cyclin D1 and hypophosphorylated Rb was observed. Our results showed that lowering the level of ROS-producing enzyme - NOX4 oxidase below physiological level leads to cellular senescence of VSMCs which is correlated with secretion of pro-inflammatory cytokines. Thus the use of specific NOX4 inhibitors for pharmacotherapy of vascular diseases should be carefully considered.