Hemodynamic effects of inducible nitric oxide synthase and nitrotyrosine generation in heart failure

Novel Oxidative Stress Biomarkers with Risk Prognosis Values in Heart Failure

Oxidative stress (OS) is mediated by reactive oxygen species (ROS), which in cardiovascular and other disease states, damage DNA, lipids, proteins, other cellular and extra-cellular components. OS is both initiated by, and triggers inflammation, cardiomyocyte apoptosis, matrix remodeling, myocardial fibrosis, and neurohumoral activation. These have been linked to the development of heart failure (HF). Circulating biomarkers generated by OS offer potential utility in patient management and therapeutic targeting. Novel OS-related biomarkers such as NADPH oxidases (sNox2-dp, Nrf2), advanced glycation end-products (AGE), and myeloperoxidase (MPO), are signaling molecules reflecting pathobiological changes in HF. This review aims to evaluate current OS-related biomarkers and their associations with clinical outcomes and to highlight those with greatest promise in diagnosis, risk stratification and therapeutic targeting in HF.

Hemodynamic Response to Acute Volume Load and Endomyocardial NO-synthase Gene Expression in Heart Transplant Recipients

A pulmonary capillary wedge pressure (PCWP) >18 mm Hg following volume load has been proposed as a partition value for the detection of heart failure with preserved ejection fraction. As hemodynamic changes in filling pressures (FP) have been attributed to a nitric oxide (NO)-mediated rightward shift of the pressure-volume relationship, we investigated the hemodynamic response to volume load in heart transplant recipients (HTx) and examined the role of inducible NO synthase (iNOS) gene expression on diastolic function changes.

Oxidative Stress-Related Parthanatos of Circulating Mononuclear Leukocytes in Heart Failure

Background

The present study aims to examine the oxidative stress-related activation of poly(ADP-ribose) polymerase (PARP), a cause of parthanatos in circulating mononuclear leukocytes of patients with chronic heart failure (CHF), that was rarely investigated in the human setting yet.

Methods

Patients with CHF (n = 20) and age- and body mass index-matched volunteers (n = 15) with a normal heart function were enrolled. C-reactive protein, N-terminal probrain-type natriuretic peptide (pro-BNP), plasma total peroxide level (PRX), plasma total antioxidant capacity (TAC), oxidative stress index (OSI), leukocyte lipid peroxidation (4-hydroxynonenal; HNE), protein tyrosine nitration (NT), poly(ADP-ribosyl)ation (PARylation), and apoptosis-inducing factor (AIF) translocation were measured in blood samples of fasting subjects.

Results

Plasma PRX, leukocyte HNE, NT, PARylation, and AIF translocation were significantly higher in the heart failure group. Pro-BNP levels in all study subjects showed a significant positive correlation to PRX, OSI, leukocyte HNE, NT, PARylation, and AIF translocation. Ejection fraction negatively correlated with the same parameters. Among HF patients, a positive correlation of pro-BNP with PRX, OSI, and PARylation was still present.

Conclusions

Markers of oxidative-nitrative stress, PARP activation, and AIF translocation in blood components showed correlation to reduced cardiac function and the clinical appearance of CHF. These results may reinforce the consideration of PARP inhibition as a potential therapeutic target in CHF.

Reactive nitrogen species: molecular mechanisms and potential significance in health and disease

Reactive nitrogen species (RNS) are various nitric oxide-derived compounds, including nitroxyl anion, nitrosonium cation, higher oxides of nitrogen, S-nitrosothiols, and dinitrosyl iron complexes. RNS have been recognized as playing a crucial role in the physiologic regulation of many, if not all, living cells, such as smooth muscle cells, cardiomyocytes, platelets, and nervous and juxtaglomerular cells. They possess pleiotropic properties on cellular targets after both posttranslational modifications and interactions with reactive oxygen species. Elevated levels of RNS have been implicated in cell injury and death by inducing nitrosative stress. The aim of this comprehensive review is to address the mechanisms of formation and removal of RNS, highlighting their potential cellular targets: lipids, DNA, and proteins. The specific importance of RNS and their paradoxic effects, depending on their local concentration under physiologic conditions, is underscored. An increasing number of compounds that modulate RNS processing or targets are being identified. Such compounds are now undergoing preclinical and clinical evaluations in the treatment of pathologies associated with RNS-induced cellular damage. Future research should help to elucidate the involvement of RNS in the therapeutic effect of drugs used to treat neurodegenerative, cardiovascular, metabolic, and inflammatory diseases and cancer.

Role of the peroxynitrite-poly(ADP-ribose) polymerase pathway in human disease

Throughout the last 2 decades, experimental evidence from in vitro studies and preclinical models of disease has demonstrated that reactive oxygen and nitrogen species, including the reactive oxidant peroxynitrite, are generated in parenchymal, endothelial, and infiltrating inflammatory cells during stroke, myocardial and other forms of reperfusion injury, myocardial hypertrophy and heart failure, cardiomyopathies, circulatory shock, cardiovascular aging, atherosclerosis and vascular remodeling after injury, diabetic complications, and neurodegenerative disorders. Peroxynitrite and other reactive species induce oxidative DNA damage and consequent activation of the nuclear enzyme poly(ADP-ribose) polymerase 1 (PARP-1), the most abundant isoform of the PARP enzyme family. PARP overactivation depletes its substrate NAD(+), slowing the rate of glycolysis, electron transport, and ATP formation, eventually leading to functional impairment or death of cells, as well as up-regulation of various proinflammatory pathways. In related animal models of disease, peroxynitrite neutralization or pharmacological inhibition of PARP provides significant therapeutic benefits. Therefore, novel antioxidants and PARP inhibitors have entered clinical development for the experimental therapy of various cardiovascular and other diseases. This review focuses on the human data available on the pathophysiological relevance of the peroxynitrite-PARP pathway in a wide range of disparate diseases, ranging from myocardial ischemia/reperfusion injury, myocarditis, heart failure, circulatory shock, and diabetic complications to atherosclerosis, arthritis, colitis, and neurodegenerative disorders.

Antioxidant therapy attenuates oxidative stress in chronic cardiopathy associated with Chagas' disease

Oxidative stress is common in inflammatory processes of many diseases, including the Chagas' disease, which is characterized by chronic inflammation. The present study is a sequence of a related publication [Oliveira TB, Pedrosa RC, Wilhelm Filho D. Oxidative stress in chronic cardiopathy associated with Chagas' disease. Int J Cardiol in press.] on the same subjects, which showed an increase in oxidative stress associated with the progression of the severity of the disease. Components of the antioxidant system and oxidative biomarkers present in the blood were measured in the same chronic chagasic patients (n=40), before and after vitamin E (800 IU/day) and vitamin C (500 mg/day) supplementation for 6 months. Antioxidant enzymes and contents of reduced glutathione in erythrocytes and plasma TBARS contents were analyzed in four groups of patients in different stages of chronic Chagas heart disease (n=10 each group, groups I, II, III, and IV) according to the Los Andes classification. After the combined vitamin supplementation, TBARS and protein carbonyl levels were decreased in plasma, whilst red cell GSH contents were increased in group I. The vitamin E contents found in the plasma were inversely related to the severity of the disease. No differences in gamma-glutamiltransferase activities were detected but the myeloperoxidase levels were decreased in patients at the initial stages, whilst seric nitric oxide levels were increased in groups II and III. After the antioxidant supplementation, CAT activity was increased in group II, GPx activity was increased in group I, GR activity was increased in groups I and II, whilst the GST activity was decreased in groups II, III and IV. The results clearly indicate that the antioxidant supplementation was able to counteract the progressive oxidative stress associated with the disease. New perspectives for the treatment of Chagas' disease might include an antioxidant therapy in order to attenuate the consequences of oxidative insult related to this disease.

Aging influences multiple indices of oxidative stress in the heart of the Fischer 344/NNia x Brown Norway/BiNia rat

We report the influence of aging on multiple markers of oxidative-nitrosative stress in the heart of adult (6-month), aged (30-month) and very aged (36-month) Fischer 344/NNiaHSd x Brown Norway/BiNia (F344/NXBN) rats. Compared to adult (6-month) hearts, indices of oxidative (superoxide anion [O2*-], 4-hydroxy-2-nonenal [4-HNE]) and nitrosative (protein nitrotyrosylation) stress were 34.1 +/- 28.1%, 186 +/- 28.1% and 94 +/- 5.8% higher, respectively, in 36-month hearts and these findings were highly correlated with increases in left ventricular wall thickness (r > 0.669; r > 0.710 and P < 0.01, respectively). Regression analysis showed that increases in cardiac oxidative-nitrosative stress with aging were significantly correlated with changes in the expression and/or regulation of proteins involved in transcriptional (NF-kappaB) activities, signaling (mitogen-activated protein kinases along with Src), apoptotic (Bcl-2, Traf-2), and cellular stress (HSPs). These results suggest that the aging F344/NXBN heart may be highly suited for unraveling the molecular events that lead to age-associated alterations in cardiac oxidative stress.

Nitric oxide and peroxynitrite in health and disease

The discovery that mammalian cells have the ability to synthesize the free radical nitric oxide (NO) has stimulated an extraordinary impetus for scientific research in all the fields of biology and medicine. Since its early description as an endothelial-derived relaxing factor, NO has emerged as a fundamental signaling device regulating virtually every critical cellular function, as well as a potent mediator of cellular damage in a wide range of conditions. Recent evidence indicates that most of the cytotoxicity attributed to NO is rather due to peroxynitrite, produced from the diffusion-controlled reaction between NO and another free radical, the superoxide anion. Peroxynitrite interacts with lipids, DNA, and proteins via direct oxidative reactions or via indirect, radical-mediated mechanisms. These reactions trigger cellular responses ranging from subtle modulations of cell signaling to overwhelming oxidative injury, committing cells to necrosis or apoptosis. In vivo, peroxynitrite generation represents a crucial pathogenic mechanism in conditions such as stroke, myocardial infarction, chronic heart failure, diabetes, circulatory shock, chronic inflammatory diseases, cancer, and neurodegenerative disorders. Hence, novel pharmacological strategies aimed at removing peroxynitrite might represent powerful therapeutic tools in the future. Evidence supporting these novel roles of NO and peroxynitrite is presented in detail in this review.

Oxidative stress in chronic cardiopathy associated with Chagas disease

BACKGROUND

Chagas disease is characterized by chronic inflammation similar to autoimmune diseases. The imbalance between prooxidant and antioxidant defenses is known as oxidative stress, and is often associated with inflammatory processes of many diseases.

METHODS

The present work measured some components of the antioxidant system present in the blood of four groups of patients in different stages of chronic Chagas heart disease (n=10 each group), according to the modified Los Andes clinical-hemodynamic classification. Each group of chagasic patients was compared with four groups of healthy subjects, and chagasic group IV was compared to group V, characterized by rheumatic cardiac disease, giving a total of 90 subjects. Antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione S-transferase (GST), and the contents of reduced (GSH), oxidized (GSSG) and total glutathione (TG) were assayed.

RESULTS

SOD, CAT and GR activities showed essentially no differences among the four groups, however, intraerythrocytic GSH concentrations showed decreased values parallel to the progression of the disease. In addition, the glutathione peroxidase (GPx) activities were higher in groups III and V and lower in groups I, II and IV, also suggesting an antioxidant depletion with progression of the disease. In contrast, except for SOD and CAT activities, patients from group V showed a generally higher antioxidant capacity compared to the chagasic group IV.

CONCLUSION

The results indicate a general increase of oxidative stress parallel to the progression of Chagas disease.

NO/redox disequilibrium in the failing heart and cardiovascular system

There is growing evidence that the altered production and/or spatiotemporal distribution of reactive oxygen and nitrogen species creates oxidative and/or nitrosative stresses in the failing heart and vascular tree, which contribute to the abnormal cardiac and vascular phenotypes that characterize the failing cardiovascular system. These derangements at the integrated system level can be interpreted at the cellular and molecular levels in terms of adverse effects on signaling elements in the heart, vasculature, and blood that subserve cardiac and vascular homeostasis.

NO/redox disequilibrium in the failing heart and cardiovascular system

There is growing evidence that the altered production and/or spatiotemporal distribution of reactive oxygen and nitrogen species creates oxidative and/or nitrosative stresses in the failing heart and vascular tree, which contribute to the abnormal cardiac and vascular phenotypes that characterize the failing cardiovascular system. These derangements at the integrated system level can be interpreted at the cellular and molecular levels in terms of adverse effects on signaling elements in the heart, vasculature, and blood that subserve cardiac and vascular homeostasis.

Increased nitration of sarcoplasmic reticulum Ca2+-ATPase in human heart failure

BACKGROUND

Reduced sarcoplasmic reticulum (SR) Ca2+-ATPase (SERCA2a isoform) activity is a major determinant of reduced contractility in heart failure. Ca2+-ATPase inactivation can occur through SERCA2a nitration. We therefore investigated the role of SERCA2a nitration in heart failure.

METHODS AND RESULTS

We measured SERCA2a levels and nitrotyrosine levels in tissue from normal and failing human hearts using Western blots. We found that nitrotyrosine levels in idiopathic dilated cardiomyopathic (DCM) hearts were almost double those of control hearts in age-matched groups. Nitrotyrosine was dominantly present in a single protein with the molecular weight of SERCA2a, and immunoprecipitation confirmed that the protein recognized by the nitrotyrosine antibody was SERCA2a. There was a positive correlation between the time to half relaxation and the nitrotyrosine/SERCA2a content (P<0.01) in myocytes isolated from control and DCM hearts. In experiments with isolated SR vesicles from porcine hearts, we also showed that the Ca pump is inactivated by peroxynitrite exposure, and inactivation was prevented by protein kinase A pretreatment.

CONCLUSIONS

We conclude that SERCA2a inactivation by nitration may contribute to Ca pump failure and hence heart failure in DCM.