N-acetylcysteine treatment normalizes serum tumor necrosis factor-alpha level and hinders the progression of cardiac injury in hypertensive rats

Effects of concurrent training and N-acetylcysteine supplementation on cardiac remodeling and oxidative stress in middle-aged spontaneously hypertensive rats

BACKGROUND

This study evaluated the effects of concurrent isolated training (T) or training combined with the antioxidant N-acetylcysteine (NAC) on cardiac remodeling and oxidative stress in spontaneously hypertensive rats (SHR).

METHODS

Six-month-old male SHR were divided into sedentary (S, n = 12), concurrent training (T, n = 13), sedentary supplemented with NAC (SNAC, n = 13), and concurrent training with NAC supplementation (TNAC, n = 14) groups. T and TNAC rats were trained three times a week on a treadmill and ladder; NAC supplemented groups received 120 mg/kg/day NAC in rat chow for eight weeks. Myocardial antioxidant enzyme activity and lipid hydroperoxide concentration were assessed by spectrophotometry. Gene expression of NADPH oxidase subunits Nox2, Nox4, p22 phox, and p47 phox was evaluated by real time RT-PCR. Statistical analysis was performed using ANOVA and Bonferroni or Kruskal-Wallis and Dunn.

RESULTS

Echocardiogram showed concentric remodeling in TNAC, characterized by increased relative wall thickness (S 0.40 ± 0.04; T 0.39 ± 0.03; SNAC 0.40 ± 0.04; TNAC 0.43 ± 0.04 *; * p < 0.05 vs T and SNAC) and diastolic posterior wall thickness (S 1.50 ± 0.12; T 1.52 ± 0.10; SNAC 1.56 ± 0.12; TNAC 1.62 ± 0.14 * mm; * p < 0.05 vs T), with improved contractile function (posterior wall shortening velocity: S 39.4 ± 5.01; T 36.4 ± 2.96; SNAC 39.7 ± 3.44; TNAC 41.6 ± 3.57 * mm/s; * p < 0.05 vs T). Myocardial lipid hydroperoxide concentration was lower in NAC treated groups (S 210 ± 48; T 182 ± 43; SNAC 159 ± 33 *; TNAC 110 ± 23 *# nmol/g tissue; * p < 0.05 vs S, # p < 0.05 vs T and SNAC). Nox 2 and p22 phox expression was higher and p47 phox lower in T than S [S 1.37 (0.66-1.66); T 0.78 (0.61-1.04) *; SNAC 1.07 (1.01-1.38); TNAC 1.06 (1.01-1.15) arbitrary units; * p < 0.05 vs S]. NADPH oxidase subunits did not differ between TNAC, SNAC, and S groups.

CONCLUSION

N-acetylcysteine supplementation alone reduces oxidative stress in untreated spontaneously hypertensive rats. The combination of N-acetylcysteine and concurrent exercise further decreases oxidative stress. However, the lower oxidative stress does not translate into improved cardiac remodeling and function in untreated spontaneously hypertensive rats.

The role of oxidative stress in aortic dissection: a potential therapeutic target

The incidence of aortic dissection (AD) is steadily increasing, driven by the rising prevalence of chronic conditions such as hypertension and the global aging of the population. Oxidative stress emerges as a pivotal pathophysiological mechanism contributing to the progression of AD. Oxidative stress triggers apoptosis in vascular smooth muscle cells, reshapes the extracellular matrix (ECM), and governs ECM degradation and remodeling, subsequently impacting aortic compliance. Furthermore, oxidative stress not only facilitates the infiltration of macrophages and mononuclear lymphocytes but also disrupts the integral structure and functionality of endothelial cells, thereby inducing endothelial cell dysfunction and furthering the degeneration of the middle layer of the aortic wall. Investigating antioxidants holds promise as a therapeutic avenue for addressing AD.

Endothelial activation and damage as a common pathological substrate in different pathologies and cell therapy complications

The endothelium is a biologically active interface with multiple functions, some of them common throughout the vascular tree, and others that depend on its anatomical location. Endothelial cells are continually exposed to cellular and humoral factors, and to all those elements (biological, chemical, or hemodynamic) that circulate in blood at a certain time. It can adapt to different stimuli but this capability may be lost if the stimuli are strong enough and/or persistent in time. If the endothelium loses its adaptability it may become dysfunctional, becoming a potential real danger to the host. Endothelial dysfunction is present in multiple clinical conditions, such as chronic kidney disease, obesity, major depression, pregnancy-related complications, septic syndromes, COVID-19, and thrombotic microangiopathies, among other pathologies, but also in association with cell therapies, such as hematopoietic stem cell transplantation and treatment with chimeric antigen receptor T cells. In these diverse conditions, evidence suggests that the presence and severity of endothelial dysfunction correlate with the severity of the associated disease. More importantly, endothelial dysfunction has a strong diagnostic and prognostic value for the development of critical complications that, although may differ according to the underlying disease, have a vascular background in common. Our multidisciplinary team of women has devoted many years to exploring the role of the endothelium in association with the mentioned diseases and conditions. Our research group has characterized some of the mechanisms and also proposed biomarkers of endothelial damage. A better knowledge would provide therapeutic strategies either to prevent or to treat endothelial dysfunction.

Systemic oxidative stress associates with disease severity and outcome in patients with new-onset or worsening heart failure

BACKGROUND

Oxidative stress may be a key pathophysiological mediator in the development and progression of heart failure (HF). The role of serum-free thiol concentrations, as a marker of systemic oxidative stress, in HF remains largely unknown.

OBJECTIVE

The purpose of this study was to investigate associations between serum-free thiol concentrations and disease severity and clinical outcome in patients with new-onset or worsening HF.

METHODS

Serum-free thiol concentrations were determined by colorimetric detection in 3802 patients from the BIOlogy Study to TAilored Treatment in Chronic Heart Failure (BIOSTAT-CHF). Associations between free thiol concentrations and clinical characteristics and outcomes, including all-cause mortality, cardiovascular mortality, and a composite of HF hospitalization and all-cause mortality during a 2-years follow-up, were reported.

RESULTS

Lower serum-free thiol concentrations were associated with more advanced HF, as indicated by worse NYHA class, higher plasma NT-proBNP (P < 0.001 for both) and with higher rates of all-cause mortality (hazard ratio (HR) per standard deviation (SD) decrease in free thiols: 1.253, 95% confidence interval (CI): 1.171-1.341, P < 0.001), cardiovascular mortality (HR per SD: 1.182, 95% CI: 1.086-1.288, P < 0.001), and the composite outcome (HR per SD: 1.058, 95% CI: 1.001-1.118, P = 0.046).

CONCLUSIONS

In patients with new-onset or worsening HF, a lower serum-free thiol concentration, indicative of higher oxidative stress, is associated with increased HF severity and poorer prognosis. Our results do not prove causality, but our findings may be used as rationale for future (mechanistic) studies on serum-free thiol modulation in heart failure. Associations of serum-free thiol concentrations with heart failure severity and outcomes.

Oxidative Stress, Antioxidants and Hypertension

As a major cause of morbidity and mortality globally, hypertension remains a serious threat to global public health. Despite the availability of many antihypertensive medications, several hypertensive individuals are resistant to standard treatments, and are unable to control their blood pressure. Regulation of the renin-angiotensin-aldosterone system (RAAS) controlling blood pressure, activation of the immune system triggering inflammation and production of reactive oxygen species, leading to oxidative stress and redox-sensitive signaling, have been implicated in the pathogenesis of hypertension. Thus, besides standard antihypertensive medications, which lower arterial pressure, antioxidant medications were tested to improve antihypertensive treatment. We review and discuss the role of oxidative stress in the pathophysiology of hypertension and the potential use of antioxidants in the management of hypertension and its associated organ damage.

Myocardial infarction and oxidative damage in animal models: objective and expectations from the application of cysteine derivatives

Reactive oxygen species (ROS) and associated oxidative stress are the main contributors to pathophysiological changes following myocardial infarction (MI), which is the principal cause of death from cardiovascular disease. The glutathione (GSH)/glutathione peroxidase (GPx) system appears to be the main and most active cardiac antioxidant mechanism. Hence, enhancement of the myocardial GSH system might have protective effects in the setting of MI. It follows that by increasing antioxidant capacity, the heart will be able to reduce the damage associated with MI and even prevent/weaken the occurrence of oxidative stress, which is highly ranked among the factors responsible for the occurrence of acute MI. For these reasons, the primary goal of future investigations should be to address the effects of different antioxidative compounds and especially cysteine derivatives like N-acetyl cysteine (NAC) and L-2-oxothiazolidine-4-carboxylic acid (OTC) as precursors responsible for the enhancement of the GSH-related antioxidant system's capacity. It is assumed that this will lay down the basis for elucidation of the mechanisms throughout which applicable doses of OTC will manifest a potentially positive impact in the reduction of adverse effects of acute MI. The inclusion of OTC in the models for prediction of the distribution of oxygen in infarcted animal hearts can help to upgrade existing computational models. Such a model would be based on computational geometries of the heart, but the inclusion of biochemical redox features in addition to angiogenic therapy, despite improvement of the post-infarcted oxygenated outcome could enhance the accuracy of the predictive values of oxygenation.

Endothelial dysfunction: developmental mechanisms and therapeutic strategies

Introduction: Every year the importance of the normal functioning of the endothelial layer of the vascular wall in maintaining the health of the body becomes more and more obvious.

The physiological role of the endothelium: The endothelium is a metabolically active organ actively involved in the regulation of hemostasis, modulation of inflammation, maintenance of hemovascular homeostasis, regulation of angiogenesis, vascular tone, and permeability.

Risk factors for the development of endothelial dysfunction: Currently, insufficient bioavailability of nitric oxide is considered the most significant risk factor for endothelial dysfunction.

Mechanisms of development of endothelial dysfunction: The genesis of endothelial dysfunction is a multifactorial process. Among various complex mechanisms, this review examines oxidative stress, inflammation, hyperglycemia, vitamin D deficiency, dyslipidemia, excess visceral fat, hyperhomocysteinemia, hyperuricemia, as well as primary genetic defect of endotheliocytes, as the most common causes in the population underlying the development of endothelial dysfunction.

Markers of endothelial dysfunction in various diseases: This article discusses the main biomarkers of endothelial dysfunction currently used, as well as promising biomarkers in the future for laboratory diagnosis of this pathology.

Therapeutic strategies: Therapeutic approaches to the endothelium in order to prevent or reduce a degree of damage to the vascular wall are briefly described.

Conclusion: Endothelial dysfunction is a typical pathological process involved in the pathogenesis of many diseases. Thus, pharmacological agents with endothelioprotective properties can provide more therapeutic benefits than a drug without such an effect.

Uncovering the genetic links of SARS-CoV-2 infections on heart failure co-morbidity by a systems biology approach

Aims

The co‐morbidities contribute to the inferior prognosis of COVID‐19 patients. Recent reports suggested that the higher co‐morbidity rate between COVID‐19 and heart failure (HF) leads to increased mortality. However, the common pathogenic mechanism between them remained elusive. Here, we aimed to reveal underlying molecule mechanisms and genetic correlation between COVID‐19 and HF, providing a new perspective on current clinical management for patients with co‐morbidity.

Methods

The gene expression profiles of HF (GSE26887) and COVID‐19 (GSE147507) were retrieved from the GEO database. After identifying the common differentially expressed genes (|log2FC| > 1 and adjusted P < 0.05), integrated analyses were performed, namely, enrichment analyses, protein–protein interaction network, module construction, critical gene identification, and functional co‐expression analysis. The performance of critical genes was validation combining hierarchical clustering, correlation, and principal component analysis in external datasets (GSE164805 and GSE9128). Potential transcription factors and miRNAs were obtained from the JASPER and RegNetwork repository used to construct co‐regulatory networks. The candidate drug compounds in potential genetic link targets were further identified using the DSigDB database.

Results

The alteration of 12 genes was identified as a shared transcriptional signature, with the role of immune inflammatory pathway, especially Toll‐like receptor, NF‐kappa B, chemokine, and interleukin‐related pathways that primarily emphasized in response to SARS‐CoV‐2 complicated with HF. Top 10 critical genes (TLR4, TLR2, CXCL8, IL10, STAT3, IL1B, TLR1, TP53, CCL20, and CXCL10) were identified from protein–protein interaction with topological algorithms. The unhealthy microbiota status and gut–heart axis in co‐morbidity were identified as potential disease roads in bridging pathogenic mechanism, and lipopolysaccharide acts as a potential marker for monitoring HF during COVID‐19. For transcriptional and post‐transcriptional levels, regulation networks tightly coupling with both disorders were constructed, and significant regulator signatures with high interaction degree, especially FOXC1, STAT3, NF‐κB1, miR‐181, and miR‐520, were detected to regulate common differentially expressed genes. According to genetic links targets, glutathione‐based antioxidant strategy combined with muramyl dipeptide‐based microbe‐derived immunostimulatory therapies was identified as promising anti‐COVID‐19 and anti‐HF therapeutics.

Conclusions

This study identified shared transcriptomic and corresponding regulatory signatures as emerging therapeutic targets and detected a set of pharmacologic agents targeting genetic links. Our findings provided new insights for underlying pathogenic mechanisms between COVID‐19 and HF.

Early Protective Role of Inflammation in Cardiac Remodeling and Heart Failure: Focus on TNFα and Resident Macrophages

Cardiac hypertrophy, initiated by a variety of physiological or pathological stimuli (hemodynamic or hormonal stimulation or infarction), is a critical early adaptive compensatory response of the heart. The structural basis of the progression from compensated hypertrophy to pathological hypertrophy and heart failure is still largely unknown. In most cases, early activation of an inflammatory program reflects a reparative or protective response to other primary injurious processes. Later on, regardless of the underlying etiology, heart failure is always associated with both local and systemic activation of inflammatory signaling cascades. Cardiac macrophages are nodal regulators of inflammation. Resident macrophages mostly attenuate cardiac injury by secreting cytoprotective factors (cytokines, chemokines, and growth factors), scavenging damaged cells or mitochondrial debris, and regulating cardiac conduction, angiogenesis, lymphangiogenesis, and fibrosis. In contrast, excessive recruitment of monocyte-derived inflammatory macrophages largely contributes to the transition to heart failure. The current review examines the ambivalent role of inflammation (mainly TNFα-related) and cardiac macrophages (Mφ) in pathophysiologies from non-infarction origin, focusing on the protective signaling processes. Our objective is to illustrate how harnessing this knowledge could pave the way for innovative therapeutics in patients with heart failure.

Homocysteine, Vitamins B6 and Folic Acid in Experimental Models of Myocardial Infarction and Heart Failure—How Strong Is That Link?

Cardiovascular diseases are the leading cause of death and the main cause of disability. In the last decade, homocysteine has been found to be a risk factor or a marker for cardiovascular diseases, including myocardial infarction (MI) and heart failure (HF). There are indications that vitamin B6 plays a significant role in the process of transsulfuration in homocysteine metabolism, specifically, in a part of the reaction in which homocysteine transfers a sulfhydryl group to serine to form α-ketobutyrate and cysteine. Therefore, an elevated homocysteine concentration (hyperhomocysteinemia) could be a consequence of vitamin B6 and/or folate deficiency. Hyperhomocysteinemia in turn could damage the endothelium and the blood vessel wall and induce worsening of atherosclerotic process, having a negative impact on the mechanisms underlying MI and HF, such as oxidative stress, inflammation, and altered function of gasotransmitters. Given the importance of the vitamin B6 in homocysteine metabolism, in this paper, we review its role in reducing oxidative stress and inflammation, influencing the functions of gasotransmitters, and improving vasodilatation and coronary flow in animal models of MI and HF.

N-Acetylcysteine Slows Down Cardiac Pathological Remodeling by Inhibiting Cardiac Fibroblast Proliferation and Collagen Synthesis

Objective

By observing the effect of N-acetylcysteine (NAC) on the proliferation and collagen synthesis of rat cardiac fibroblasts (CFs) to explore the effect of NAC on cardiac remodeling (CR).

Methods

In vivo, first, the Sprague Dawley (SD) rat myocardial hypertrophy model was constructed, and the effect of NAC on cardiac structure and function was detected by echocardiography, serological testing, and Masson staining. Western blotting (WB) and quantitative real-time polymerase chain reaction (qRT-PCR) were used to detect the expression level of antioxidant enzymes, and flow cytometry was used to detect the intracellular reactive oxygen species (ROS) content. In vitro, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and 5-ethynyl-2′-deoxyuridine (EdU) staining were used to detect cell proliferation, and the expression level of the NF-κB signaling pathway was detected.

Results

Compared with the control group, the model group had disordered cardiac structure, reduced cardiac function, and obvious oxidative stress (OS) response. However, after NAC treatment, it could obviously improve the rat cardiac structure and cardiac function and alleviate redox imbalance and cardiology remodeling. At the same time, NAC can inhibit the activation of the NF-κB signaling pathway and reduce the proliferation level of CFs and the amount of ³H proline incorporated.

Conclusions

NAC can inhibit AngII-induced CF proliferation and collagen synthesis through the NF-κB signaling pathway, alleviate the OS response of myocardial tissue, inhibit the fibrosis of myocardial tissue, and thus slow down the pathological remodeling of the heart.

Oral N-acetylcysteine as an adjunct to standard medical therapy improved heart function in cases with stable class II and III systolic heart failure

BACKGROUND

This research attempted to assess whether N-acetylcysteine (NAC) as adjunctive therapy can be useful in the treatment of patients with heart failure (HF).

METHODS

Fifty-five cases with diagnosed systolic HF and stable symptomatic New York Heart Association (NYHA) functional class II and III and on optimal medical treatment of HF for at least 3 months were assigned for receiving oral NAC (600 mg twice daily) or placebo for 12 weeks. The outcomes were changes in the echocardiographic hemodynamic indices as well as the patients' functional capacity assessed by NYHA classification over a 12-week treatment.

RESULTS

Compared to placebo, NAC more significantly improved the systolic left ventricular (LV) function expressed as the ejection fraction and Tei index. These changes are accompanied by more improvement in other LV echocardiographic indices including LV end-diastolic volume index and LV global longitudinal strain in the patients receiving NAC in comparison with those receiving placebo. In parallel with the improvement of LV function, right ventricular (RV) function expressed as RV fractional area change and RV Tei-index also got more improvement in those receiving NAC than those receiving placebo. However, the change in RV global longitudinal strain did not show a significant difference between study groups. Additionally, at week 12, the distribution of the NYHA functional class also shifted toward a better outcome in the NAC group in comparison with the placebo group; however, it was not significant.

CONCLUSIONS

These preliminary data support experimental findings showing that NAC supplementation is able to improve heart function.

TRIAL REGISTRATION

The registration of the trial was done at the Iranian Registry of Clinical Trials ( www.irct.ir ). Identifier code: IRCT20120215009014N333. Registration date: 2020-01-11.

Putting function back in dysfunction: Endothelial diseases and current therapies in hematopoietic stem cell transplantation and cellular therapies

Endothelial dysfunction is characterized by altered vascular permeability and prothrombotic, pro-inflammatory phenotypes. Endothelial dysfunction results in end-organ damage and has been associated with diverse disease pathologies. Complications observed after hematopoietic stem cell transplantation (HCT) and chimeric antigen receptor-T cell (CAR-T) therapy for hematologic and neoplastic disorders share overlapping clinical manifestations and there is increasing evidence linking these complications to endothelial dysfunction. Despite advances in supportive care and treatments, end-organ toxicity remains the leading cause of mortality. A new strategy to mitigate endothelial dysfunction could lead to improvement of clinical outcomes for patients. Statins have demonstrated pleiotropic effects of immunomodulatory and endothelial protection by various molecular mechanisms. Recent applications in immune-mediated diseases such as autoimmune disorders, chronic inflammatory conditions, and graft-versus-host disease (GVHD) have shown promising results. In this review, we cover the mechanisms underlying endothelial dysfunction in GVHD and CAR-T cell-related toxicities. We summarize the current knowledge about statins and other agents used as endothelial protectants. We propose further studies using statins for prophylaxis and prevention of end-organ damage related to extensive endothelial dysfunction in HCT and CAR-T.

Heart failure and the glutathione cycle: an integrated view

Heart failure results from the heart's inability to carryout ventricular contraction and relaxation, and has now become a worldwide problem. During the onset of heart failure, several signatures are observed in cardiomyocytes that includes fetal reprogramming of gene expression where adult genes are repressed and fetal genes turned on, endoplasmic reticulum stress and oxidative stress. In this short review and analysis, we examine these different phenomenon from the viewpoint of the glutathione cycle and the role of the recently discovered Chac1 enzyme. Chac1, which belongs to the family of γ-glutamylcyclotransferases, is a recently discovered member of the glutathione cycle, being involved in the cytosolic degradation of glutathione. This enzyme is induced during the Endoplasmic Stress response, but also in the developing heart. Owing to its exclusive action on reduced glutathione, its induction leads to an increase in the oxidative redox potential of the cell that also serves as signaling mechanism for calcium ions channel activation. The end product of Chac1 action is 5-oxoproline, and studies with 5-oxoprolinase (OPLAH), an enzyme of the glutathione cycle has revealed that down-regulation of OPLAH can lead to the accumulation of 5-oxproline which is an important factor in heart failure. With these recent findings, we have re-examined the roles and regulation of the enzymes in the glutathione cycle which are central to these responses. We present an integrated view of the glutathione cycle in the cellular response to heart failure.

Therapeutic approaches to diabetic cardiomyopathy: Targeting the antioxidant pathway

The global epidemic of cardiovascular disease continues unabated and remains the leading cause of death both in the US and worldwide. We hereby summarize the available therapies for diabetes and cardiovascular disease in diabetics. Clearly, the current approaches to diabetic heart disease often target the manifestations and certain mediators but not the specific pathways leading to myocardial injury, remodeling and dysfunction. Better understanding of the molecular events determining the evolution of diabetic cardiomyopathy will provide insight into the development of specific and targeted therapies. Recent studies largely increased our understanding of the role of enhanced inflammatory response, ROS production, as well as the contribution of Cyp-P450-epoxygenase-derived epoxyeicosatrienoic acid (EET), Peroxisome Proliferator-Activated Receptor Gamma Coactivator-1α (PGC-1α), Heme Oxygenase (HO)-1 and 20-HETE in pathophysiology and therapy of cardiovascular disease. PGC-1α increases production of the HO-1 which has a major role in protecting the heart against oxidative stress, microcirculation and mitochondrial dysfunction. This review describes the potential drugs and their downstream targets, PGC-1α and HO-1, as major loci for developing therapeutic approaches beside diet and lifestyle modification for the treatment and prevention of heart disease associated with obesity and diabetes.

Thyroid hormones and modulation of diastolic function: a promising target for heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) is a clinical syndrome with high mortality for which there is no proven therapy to improve its prognosis. Thyroid dysfunction is common in heart failure (HF) and is associated with worse prognosis. In this review, we discuss the cardiovascular effects of thyroid hormones, the pathophysiology of HFpEF, the prognostic impact of thyroid function, and the potential of thyroid hormones for treatment of HFpEF. Thyroid hormones have a central role in cardiovascular homeostasis, improving cardiac function through genomic and non-genomic mechanisms. Both overt and subclinical hypothyroidism are associated with increased risk of HF. Even when plasmatic thyroid hormones levels are normal, patients with HF may have local cardiac hypothyroidism due to upregulation of type 3 iodothyronine deiodinase. Thyroid hormones improve several pathophysiological mechanisms of HFpEF, including diastolic dysfunction and extra-cardiac abnormalities. Supplementation with thyroid hormones (levothyroxine and/or liothyronine), modulation of deiodinase activity, and heart-specific thyroid receptor agonists are potential therapeutic approaches for the treatment of HFpEF. Further preclinical and clinical studies are needed to clarify the role of thyroid hormones in the treatment of HFpEF.

Glutathione Blood Concentrations: A Biomarker of Oxidative Damage Protection during Cardiopulmonary Bypass in Children

Background. Pediatric open-heart surgery with cardiopulmonary bypass (CPB) still remains a risky interventional procedure at high mortality/morbidity. To date, there are no clinical, laboratory, and/or monitoring parameters providing useful information on perioperative stress. We therefore investigated whether blood concentrations of glutathione (GSH), a powerful endogenous antioxidant, changed in the perioperative period. Methods. We conducted an observational study in 35 congenital heart disease (CHD) children in whom perioperative standard laboratory and monitoring parameters and GSH blood levels were assessed at five monitoring time points. Results. GSH showed a pattern characterized by a progressive increase from pre-surgery up to 24 h after surgery, reaching its highest peak at the end of CPB. GSH measured at the end of CPB correlated with CPB duration, cross-clamping, arterial oxygen partial pressure, and with body core temperature. Conclusions. The increase in GSH levels in the perioperative period suggests a compensatory mechanism to oxidative damage during surgical procedure. Caution is needed in controlling different CPB phases, especially systemic reoxygenation in a population that is per se more prone to oxidative stress/damage. The findings may point the way to detecting the optimal temperature and oxygenation target by biomarker monitoring.

Treating oxidative stress in heart failure: past, present and future

Advances in cardiovascular research have identified oxidative stress as an important pathophysiological pathway in the development and progression of heart failure. Oxidative stress is defined as the imbalance between the production of reactive oxygen species (ROS) and the endogenous antioxidant defence system. Under physiological conditions, small quantities of ROS are produced intracellularly, which function in cell signalling, and can be readily reduced by the antioxidant defence system. However, under pathophysiological conditions, the production of ROS exceeds the buffering capacity of the antioxidant defence system, resulting in cell damage and death. Over the last decades several studies have tried to target oxidative stress with the aim to improve outcome in patients with heart failure, with very limited success. The reasons as to why these studies failed to demonstrate any beneficial effects remain unclear. However, one plausible explanation might be that currently employed strategies, which target oxidative stress by exogenous inhibition of ROS production or supplementation of exogenous antioxidants, are not effective enough, while bolstering the endogenous antioxidant capacity might be a far more potent avenue for therapeutic intervention. In this review, we provide an overview of oxidative stress in the pathophysiology of heart failure and the strategies utilized to date to target this pathway. We provide novel insights into modulation of endogenous antioxidants, which may lead to novel therapeutic strategies to improve outcome in patients with heart failure.

The gastroprotective effect of N-acetylcysteine and genistein in indomethacin-induced gastric injury in rats

The protective effect of N-acetylcysteine (NAC) and genistein (GEN) on an experimental model of indomethacin (IND)-induced gastric injury was investigated. A total of 50 male rats were divided into 5 groups: (1) control, (2) IND, (3) NAC pretreated, (4) GEN pretreated, and (5) NAC+GEN pretreated. Rats in groups 3-5 were orally administered NAC (500 mg/kg), GEN (10 mg/kg), or both, respectively, once daily for 7 days before the induction of gastric injury by IND (50 mg/kg). The stomach was removed for biochemical analysis and histopathological examination. Pretreatment with NAC, GEN, or both significantly improved ulcer indices and increased nitric oxide level and superoxide dismutase activity. They also significantly decreased malondialdehyde, tumour necrosis factor α levels, and myeloperoxidase activity, and downregulated matrix metalloproteinase 9 (MMP-9) gene expression compared to the IND group. NAC alone ameliorated IND-induced apoptosis, whereas GEN only significantly increased prostaglandin E₂ level. Further, coadministration of both resulted in a significantly better gastroprotective effect versus solo administration. Coadministration of NAC and GEN has an additive gastroprotective effect in IND-induced gastric injury, which may be through interaction of their potential cytoprotective, antioxidant, anti-inflammatory, and antiapoptotic mechanisms together with regulation of MMP-9 expression.

Tumor necrosis factor-α, kidney function, and hypertension

Hypertension is considered to be a low-grade inflammatory condition characterized by the presence of various proinflammatory cytokines. Tumor necrosis factor-α (TNF-α) is a constituent of the proinflammatory cytokines that is associated with salt-sensitive hypertension (SSH) and related renal injury. Elevated angiotensin II (ANG II) and other factors such as oxidative stress conditions promote TNF-α formation. Many recent studies have provided evidence that TNF-α exerts a direct renal action by regulating hemodynamic and excretory function in the kidney. The cytokine incites a strong natriuretic response and plays a part in regulation of the intrarenal renin-angiotensin system. The exact mechanistic role of TNF-α in the development of SSH is as yet poorly understood. While TNF-α antagonism has been shown to attenuate hypertensive responses in many hypertensive animal models, contrasting findings demonstrate that the direct systemic administration of TNF-α usually induces hypotensive as well as natriuretic responses, indicating a counterregulatory role of TNF-α in SSH. Differential activities of two cell surface receptors of TNF-α (receptor type 1 and type 2) may explain the contradictory functions of TNF-α in the setting of hypertension. This short review will evaluate ongoing research studies that investigate the action of TNF-α within the kidney and its role as an influential pathophysiological variable in the development of SSH and renal injury. This information may help to develop specific TNF-α receptor targeting as an effective treatment strategy in this clinical condition.

Alu RNA accumulation in hyperglycemia augments oxidative stress and impairs eNOS and SOD2 expression in endothelial cells

Endothelial dysfunction resulting from oxidative stress and inflammation plays a dominant role in hyperglycemia-induced vasculopathy. While double-stranded RNA (dsRNA) accumulates in redox and inflammatory conditions, its precise role in hyperglycemia-associated endothelial dysfunction remains unclear. This study aimed to investigate whether and how endogenous dsRNA contributes to endothelial dysfunction via oxidative stress. We used a dsRNA-specific antibody J2 to detect and immunoprecipitate cellular dsRNA. Acquired dsRNA was recognized by cDNA library construction and DNA sequencing. Quantitative PCR, ELISA and immunoassays were performed to identify changes induced by acquired dsRNA in primary human umbilical vein endothelial cells (HUVEC). Our data showed that endogenous dsRNA homologous to Alu Sc subfamily accumulated in hyperglycemic HUVEC. Comparing Alu-transfected HUVEC with high-glucose treated HUVEC, we found that Alu RNA elicited the production of reactive oxygen species (ROS) and up-regulated interleukin-1β (IL-1β) expression and secretion in a similar manner as high-glucose treatment. Moreover, Alu RNA impeded the expression of endothelial nitric oxide synthase (eNOS) and superoxide dismutase 2 (SOD2), increased ROS production and activated nuclear factor NFκB by chemically scavenging ROS and inactivation of NFκB. The repressed expression of eNOS and SOD2 resulted from Alu RNA-mediated negative regulatory mechanisms. Our study uncovered endogenous Alu RNA accumulation in hyperglycemic endothelial cells that provoked endothelial oxidative stress and dysfunction by suppressing SOD2 and eNOS expression at both transcription and translation levels via NFκB signaling pathway. These findings suggest a novel regulatory mechanism that involves endogenous dsRNA in endothelial oxidative stress and dysfunction.

N-acetylcysteine attenuates the development of cardiac fibrosis and remodeling in a mouse model of heart failure

Oxidative stress plays a central role in the pathogenesis of heart failure. We aimed to determine whether the antioxidant N‐acetylcysteine can attenuate cardiac fibrosis and remodeling in a mouse model of heart failure. Minipumps were implanted subcutaneously in wild‐type mice (n = 20) and mice with cardiomyopathy secondary to cardiac specific overexpression of mammalian sterile 20‐like kinase 1 (MST‐1; n = 18) to administer N‐acetylcysteine (40 mg/kg per day) or saline for a period of 8 weeks. At the end of this period, cardiac remodeling and function was assessed via echocardiography. Fibrosis, oxidative stress, and expression of collagen types I and III were quantified in heart tissues. Cardiac perivascular and interstitial fibrosis were greater by 114% and 209%, respectively, in MST‐1 compared to wild type (P ≤ 0.001). In MST‐1 mice administered N‐acetylcysteine, perivascular and interstitial fibrosis were 40% and 57% less, respectively, compared to those treated with saline (P ≤ 0. 03). Cardiac oxidative stress was 119% greater in MST‐1 than in wild type (P < 0.001) and N‐acetylcysteine attenuated oxidative stress in MST‐1 by 42% (P = 0.005). These data indicate that N‐acetylcysteine can blunt cardiac fibrosis and related remodeling in the setting of heart failure potentially by reducing oxidative stress. This study provides the basis to investigate the role of N‐acetylcysteine in chronic heart failure.

Vascular endothelial dysfunction and pharmacological treatment

The endothelium exerts multiple actions involving regulation of vascular permeability and tone, coagulation and fibrinolysis, inflammatory and immunological reactions and cell growth. Alterations of one or more such actions may cause vascular endothelial dysfunction. Different risk factors such as hypercholesterolemia, homocystinemia, hyperglycemia, hypertension, smoking, inflammation, and aging contribute to the development of endothelial dysfunction. Mechanisms underlying endothelial dysfunction are multiple, including impaired endothelium-derived vasodilators, enhanced endothelium-derived vasoconstrictors, over production of reactive oxygen species and reactive nitrogen species, activation of inflammatory and immune reactions, and imbalance of coagulation and fibrinolysis. Endothelial dysfunction occurs in many cardiovascular diseases, which involves different mechanisms, depending on specific risk factors affecting the disease. Among these mechanisms, a reduction in nitric oxide (NO) bioavailability plays a central role in the development of endothelial dysfunction because NO exerts diverse physiological actions, including vasodilation, anti-inflammation, antiplatelet, antiproliferation and antimigration. Experimental and clinical studies have demonstrated that a variety of currently used or investigational drugs, such as angiotensin-converting enzyme inhibitors, angiotensin AT1 receptors blockers, angiotensin-(1-7), antioxidants, beta-blockers, calcium channel blockers, endothelial NO synthase enhancers, phosphodiesterase 5 inhibitors, sphingosine-1-phosphate and statins, exert endothelial protective effects. Due to the difference in mechanisms of action, these drugs need to be used according to specific mechanisms underlying endothelial dysfunction of the disease.

N-Acetylcysteine Ameliorates Experimental Autoimmune Myocarditis in Rats via Nitric Oxide

BACKGROUND

Oxidative stress may play an important role in the development of myocarditis. We investigated the effects of N-acetylcysteine (NAC), a potent antioxidant, on experimental autoimmune myocarditis (EAM) in rats.

METHODS AND RESULTS

A rat model of porcine myosin-induced EAM was used. After the immunization with myosin, NAC (20 mg/kg/d) or saline was injected intraperitoneally on days 1 to 21. Additional myosin-immunized rats treated with NAC were orally given 25 mg/kg/d of N(G)-nitro-l-arginine methylester (l-NAME), an inhibitor of nitric oxide (NO) synthase, and N(G)-nitro-d-arginine methylester (d-NAME), an inactive enantiomer. The NAC treatment improved cardiac pathology associated with reduced superoxide production. In the EAM rats treated with NAC associated with oral l-NAME, but not with oral d-NAME, the severity of myocarditis was not reduced. Expression of intercellular adhesion molecule 1 was reduced by NAC treatment. Myocardial c-kit(+) cells were demonstrated only in the NAC-treated group. Hemodynamic study showed that the increased left ventricular mass produced by myocardial inflammation tended to be reduced by NAC treatment.

CONCLUSION

Treatment with NAC ameliorated myocardial injury via NO system in a rat model of myocarditis.

N-Acetylcysteine effects on transforming growth factor-β and tumor necrosis factor-α serum levels as pro-fibrotic and inflammatory biomarkers in patients following ST-segment elevation myocardial infarction

Background and Aims

Ischemia following acute myocardial infarction (AMI) increases the level of pro-fibrotic and inflammatory cytokines, including transforming growth factor (TGF)-β and tumor necrosis factor (TNF)-α. N-acetylcysteine (NAC) has therapeutic benefits in the management of patients with AMI. To the best of our knowledge, this is the first study that has evaluated the effect of NAC on TNF-α and TGF-β levels in patients with AMI.

Methods

Following confirmation of AMI, 88 patients were randomly administered NAC 600 mg (Fluimucil^®, Zambon, Ticino, Switzerland) or placebo orally twice daily for 3 days. For quantification of TGF-β and TNF-α serum levels after 24 and 72 h of NAC or placebo administration, peripheral venous blood (10 mL) samples were collected at these time points.

Results

Comparisons between levels of TGF-β and TNF-α after 24 and 72 h within the NAC or placebo groups revealed that there was not any significant difference except for TGF-β levels in the placebo group, which increased significantly over time (p = 0.042). Significant relationships existed between patients’ ejection fraction (p = 0.005) and TGF-β levels.

Conclusions

Receiving NAC could prevent TGF-β levels from increasing after 72 h as compared with not receiving NAC. As TGF-β had strong correlations with the ejection fraction, its antagonism seems to be important in the prevention of remodeling.

Effects of N-acetylcysteine on the cardiac remodeling biomarkers and major adverse events following acute myocardial infarction: a randomized clinical trial

AIMS

The aims of this study were to evaluate the effects of N-acetylcysteine (NAC) on cardiac remodeling and major adverse events following acute myocardial infarction (AMI).

METHODS

In a prospective, double-blind, randomized clinical trial, the effect of NAC on the serum levels of cardiac biomarkers was compared with that of placebo in 98 patients with AMI. Also, the patients were followed up for a 1-year period for major adverse cardiac events (MACE), including the occurrence of recurrent myocardial infarction, death, and need for target vessel revascularization.

RESULTS

In patients who received NAC, the serum levels of matrix metalloproteinase (MMP)-9 and MMP-2 after 72 h were significantly lower than those in the placebo group (p = 0.014 and p = 0.045, respectively). The length of hospitalization in patients who received NAC was significantly shorter than that in the placebo group (p = 0.024). With respect to MACE, there was a significant difference between those who received NAC (14 %) and those patients on placebo (25 %) (p = 0.024). Re-infarction took place in 4 % of patients in the NAC group as compared with 16.7 % in patients who received placebo (p = 0.007).

CONCLUSION

NAC can be beneficial in preventing early remodeling by reducing the level of MMP-2 and MMP-9. Moreover, NAC decreased the length of hospital stays in patients after AMI. By decreasing MACE, NAC could possibly be introduced as a 'magic bullet' in the pharmacotherapy of patients with AMI. Further studies are needed to elucidate NAC's role in this population.

Both PKA and Epac pathways mediate N-acetylcysteine-induced Connexin43 preservation in rats with myocardial infarction

Cardiac remodeling was shown to be associated with reduced gap junction expression after myocardial infarction. A reduction in gap junctional proteins between myocytes may trigger ventricular arrhythmia. Therefore, we investigated whether N-acetylcysteine exerted antiarrhythmic effect by preserving connexin43 expression in postinfarcted rats, focusing on cAMP downstream molecules such as protein kinase A (PKA) and exchange protein directly activated by cAMP (Epac). Male Wistar rats after ligating coronary artery were randomized to either vehicle, or N-acetylcysteine for 4 weeks starting 24 hours after operation. Infarct size was similar between two groups. Compared with vehicle, cAMP levels were increased by N-acetylcysteine treatment after infarction. Myocardial connexin43 expression was significantly decreased in vehicle-treated infarcted rats compared with sham operated rats. Attenuated connexin43 expression and function were blunted after administering N-acetylcysteine, assessed by immunofluorescent analysis, dye coupling, Western blotting, and real-time quantitative RT-PCR of connexin43. Arrhythmic scores during programmed stimulation in the N-acetylcysteine-treated rats were significantly lower than those treated with vehicle. In an ex vivo study, enhanced connexin43 levels afforded by N-acetylcysteine were partially blocked by either H-89 (a PKA inhibitor) or brefeldin A (an Epac-signaling inhibitor) and completely blocked when H-89 and brefeldin A were given in combination. Addition of either the PKA specific activator N6Bz or Epac specific activator 8-CPT did not have additional increased connexin43 levels compared with rats treated with lithium chloride alone. These findings suggest that N-acetylcysteine protects ventricular arrhythmias by attenuating reduced connexin43 expression and function via both PKA- and Epac-dependent pathways, which converge through the inactivation of glycogen synthase kinase-3β.

Protective role of the endothelial isoform of nitric oxide synthase in ANG II-induced inflammatory responses in the kidney

In the present study, we examine the hypothesis that the nitric oxide (NO) produced by endothelial NO synthase (eNOS) plays a protective role in the development of ANG II-induced hypertension and renal injury by minimizing oxidative stress and the inflammation induced by TNF-α. Systolic blood pressure (SBP) and renal injury responses to chronic infusions of ANG II (via implanted minipumps) were evaluated for 2 wk in wild-type (WT) and in eNOS knockout mice (KO) cotreated with or without a superoxide (O2(-)) scavenger, tempol (400 mg/l in the drinking water), or a TNF-α receptor blocker, etanercept (5 mg/kg/day ip). In study 1, when ANG II was given at a dose of 25 ng/min, it increased mean SBP in WT mice (Δ36 ± 3 mmHg; n = 7), and this effect was attenuated in mice pretreated with tempol (Δ24 ± 3 mmHg; n = 6). In KO mice (n = 9), this dose of ANG II resulted in severe renal injury associated with high mortality. To avoid this high mortality in KO, study 2 was conducted with a lower dose of ANG II (10 ng/min) that increased SBP slightly in WT (Δ17 ± 7 mmHg; n = 6) but exaggeratedly in KO (Δ48 ± 12 mmHg, n = 6) associated with severe renal injury. Cotreatment with either tempol (n = 6) or etanercept (n = 6) ameliorated the hypertensive, as well as the renal injury responses in KO compared with WT. These data demonstrate a protective role for eNOS activity in preventing renal inflammatory injury and hypertension induced by chronic increases in ANG II.

Subendocardial increase in reactive oxygen species production affects regional contractile function in ischemic heart failure

AIMS

Heart failure (HF) is characterized by regionalized contractile alterations resulting in loss of the transmural contractile gradient across the left ventricular free wall. We tested whether a regional alteration in mitochondrial oxidative metabolism during HF could affect myofilament function through protein kinase A (PKA) signaling.

RESULTS

Twelve weeks after permanent left coronary artery ligation that induced myocardial infarction (MI), subendocardial (Endo) cardiomyocytes had decreased activity of complex I and IV of the mitochondrial electron transport chain and produced twice more superoxide anions than sham Endo and subepicardial cells. This effect was associated with a reduced antioxidant activity of superoxide dismutase and Catalase only in MI Endo cells. The myofilament contractile properties (Ca(2+) sensitivity and maximal tension), evaluated in skinned cardiomyocytes, were also reduced only in MI Endo myocytes. Conversely, in MI rats treated with the antioxidant N-acetylcysteine (NAC) for 4 weeks, the generation of superoxide anions in Endo cardiomyocytes was normalized and the contractile properties of skinned cardiomyocytes restored. This effect was accompanied by improved in vivo contractility. The beneficial effects of NAC were mediated, at least, in part, through reduction of the PKA activity, which was higher in MI myofilaments, particularly, the PKA-mediated hyperphosphorylation of cardiac Troponin I.

INNOVATION

The Transmural gradient in the mitochondrial content/activity is lost during HF and mediates reactive oxygen species-dependent contractile dysfunction.

CONCLUSIONS

Regionalized alterations in redox signaling affect the contractile machinery of sub-Endo myocytes through a PKA-dependent pathway that contributes to the loss of the transmural contractile gradient and impairs global contractility.

The antihypertensive effect of cysteine

Hypertension is a leading cause of morbidity and mortality worldwide. Individuals with hypertension are at an increased risk for stroke, heart disease and kidney failure. Essential hypertension results from a combination of genetic and lifestyle factors. One such lifestyle factor is diet, and its role in the control of blood pressure has come under much scrutiny. Just as increased salt and sugar are known to elevate blood pressure, other dietary factors may have antihypertensive effects. Studies including the Optimal Macronutrient Intake to Prevent Heart Disease (OmniHeart) study, Multiple Risk Factor Intervention Trial (MRFIT), International Study of Salt and Blood Pressure (INTERSALT) and Dietary Approaches to Stop Hypertension (DASH) study have demonstrated an inverse relationship between dietary protein and blood pressure. One component of dietary protein that may partially account for its antihypertensive effect is the nonessential amino acid cysteine. Studies in hypertensive humans and animal models of hypertension have shown that N-acetylcysteine, a stable cysteine analogue, lowers blood pressure, which substantiates this idea. Cysteine may exert its antihypertensive effects directly or through its storage form, glutathione, by decreasing oxidative stress, improving insulin resistance and glucose metabolism, lowering advanced glycation end products, and modulating levels of nitric oxide and other vasoactive molecules. Therefore, adopting a balanced diet containing cysteine-rich proteins may be a beneficial lifestyle choice for individuals with hypertension. An example of such a diet is the DASH diet, which is low in salt and saturated fat; includes whole grains, poultry, fish and nuts; and is rich in vegetables, fruits and low-fat dairy products.

Cardiac sympathetic hyperinnervation in deoxycorticosterone acetate-salt hypertensive rats

Sympathetic activities are elevated in the central SNSs (sympathetic nervous systems) of hypertensive animals, but it is not known whether sympathetic innervation is also elevated in the heart. Sympathetic hyper-responsiveness in hypertension may result from oxidative stress. The aim of the present study was to investigate sympathetic hyperinnervation in DOCA (deoxycorticosterone acetate)-salt hypertensive rats with established hypertension. At 4 weeks after the start of DOCA-salt treatment and uninephrectomization, male Wistar rats were randomized into three groups for 8 weeks: vehicle, NAC (N-acetylcysteine) and triple therapy (hydralazine, hydrochlorothiazide and reserpine). DOCA-salt was associated with increased oxidant release. DOCA-salt produced concentric left ventricular hypertrophy and cardiomyocyte hypertrophy. Sympathetic hyperinnervation was observed in DOCA-salt rats, as assessed by myocardial noradrenaline levels, immunofluorescent analysis of tyrosine hydroxylase, growth-associated factor 43 and neurofilament and Western blotting and real-time quantitative RT-PCR (reverse transcription-PCR) of NGF (nerve growth factor). Arrhythmic scores during programmed stimulation in DOCA-salt rats were significantly higher than those in the control rats. Triple therapy, despite being effective on BP (blood pressure), offered neither attenuated cardiomyocyte hypertrophy nor anti-arrhythmia. The effects of DOCA-salt treatment on NGF expression, sympathetic hyperinnervation and arrhythmias were attenuated by NAC. Furthermore, the effects of NAC on NGF were abolished by administering BSO (L-buthionine sulfoximine), an inhibitor of glutamate-cysteine ligase. In conclusion, DOCA-salt treatment contributes to up-regulation of NGF proteins probably through a free radical-dependent pathway in a BP-independent manner. DOCA-salt rats treated with NAC attenuate sympathetic hyperinnervation and thus show a beneficial effect on arrhythmogenic response to programmed electrical stimulation.

N-acetylcysteine prevents electrical remodeling and attenuates cellular hypertrophy in epicardial myocytes of rats with ascending aortic stenosis

Pressure overload is associated with cardiac hypertrophy and electrical remodeling. Here, we investigate the effects of the antioxidant N-acetylcysteine (NAC) on the cellular cardiac electrophysiology of female Sprague-Dawley rats with ascending aortic stenosis (AS). Rats were treated with NAC (1 g/kg body weight) or control solution 1 week before the intervention and in the week following AS or sham operation. Seven days after the operation, blood pressure and left ventricular pressure were measured before the heart was excised. Single cells were isolated from epicardial and endocardial layers of the left ventricular free wall and investigated using the whole-cell patch-clamp technique. Systolic blood pressure and left ventricular peak pressure were not significantly altered in the NAC group. NAC reduced the increase (p < 0.001) in the relative left ventricular weight (p < 0.05) as well as the increase (p < 0.001) in cell capacitance in epicardial (p < 0.05), but not in endocardial myocytes of AS animals. The L-type Ca(2+) current (I (CaL)) was significantly increased by AS in epicardial (+19 % at 0 mV, p < 0.01) but not in endocardial myocytes. NAC completely prevented this increase in I (CaL) (p < 0.01). The current density of the transient outward K(+) current (I (to)) was not affected by AS or NAC. Action potential duration to 90 % repolarization was significantly prolonged in epicardial (p < 0.01) as well as in endocardial (p < 0.001) cells of AS animals. NAC prevented the AP prolongation in epicardial myocytes only (p < 0.05). We conclude that reducing oxidative stress in pressure overload can prevent electrical remodeling and ameliorate hypertrophy in epicardial but not in endocardial myocytes.

Blood glutathione decrease in subjects carrying lamin A/C gene mutations is an early marker of cardiac involvement

Dominant inherited Emery-Dreifuss muscular dystrophy and limb-girdle muscular dystrophy type 1B are due to mutations in the LMNA gene encoding lamin A/C and present similar life-threatening cardiac disease, the early diagnosis of which lacks reliable biomarkers. Glutathione depletion characterizes subjects with cardiac diseases of non-genetic aetiology. We examined blood glutathione in 22 LMNA-mutated subjects without altered left ventricular ejection fraction (LVEF>40%) measured by conventional echocardiography. Left and right ventricular (LV/RV) contractility was evaluated using echocardiography implemented with tissue-Doppler echography. Blood glutathione was positively correlated with LV and RV contractility (p<0.05), and was decreased by 23% in subjects with reduced LV/RV contractility compared to subjects with normal contractility. ROC analysis showed that blood glutathione reliably detected reduced LV/RV contractility (AUC-95% CI: 0.90 [0.76-1.04]; p=0.01). Blood glutathione decrease may allow the detection of reduced contractility in muscular dystrophic LMNA-mutated patients with still preserved LVEF.

Rosuvastatin prevents proteinuria and renal inflammation in nitric oxide-deficient rats

OBJECTIVE

The aim of the present study was to assess the effects of rosuvastatin on renal injury and inflammation in a model of nitric oxide deficiency.

METHODS

Male Wistar rats were randomly divided into four groups (n = 10/group) and treated for 28 days with saline (CTRL); 30 mg/kg/day L-NAME (L-name); L-NAME and 20 mg/kg/day rosuvastatin (L-name+ROS-20); or L-NAME and 2 mg/kg/day rosuvastatin (L-name+ROS-2). Systolic blood pressure was measured by plethysmography in the central artery of the tail. The serum total cholesterol, triglycerides, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, creatinine, nitric oxide, interleukin-6, and tumor necrosis factor alpha levels were analyzed. Urine samples were taken to measure the albumin: urinary creatinine ratio. Kidneys were sectioned and stained with hematoxylin/eosin and Masson's trichrome. Immunohistochemical analysis of the renal tissue was performed to detect macrophage infiltration of the glomeruli.

RESULTS

The systolic blood pressure was elevated in the L-name but not the L-name+rosuvastatin-20 and L-name+rosuvastatin-2 groups. The L-name group had a significantly reduced nitric oxide level and an increased interleukin-6 and tumor necrosis factor alpha level, albumin: urinary creatinine ratio and number of macrophages in the renal glomeruli. Rosuvastatin increased the nitric oxide level in the L-name+rosuvastatin-2 group and reduced the interleukin-6 and tumor necrosis factor alpha levels, glomerular macrophage number and albumin:urinary creatinine ratio in the L-name+rosuvastatin-20 and L-name+rosuvastatin-2 groups.

CONCLUSION

Rosuvastatin treatment reduced glomerular damage due to improvement in the inflammatory pattern independent of the systolic blood pressure and serum lipid level. These effects may lead to improvements in the treatment of kidney disease.

Targeting the vicious inflammation-oxidative stress cycle for the management of heart failure

Oxidative stress and inflammation are each implicated independently in the development and progression of heart failure. Their interaction, however, is also evident throughout the process from initial injury to cardiac remodeling and failure. In the failing heart, the linkage between excessive reactive oxygen species (ROS) and the cytokine elaboration is manifested in shared elements and cross-promotion within downstream signaling pathways. In spite of this, the failure of anticytokine immunotherapy and antioxidant therapy, which had previously shown promise, suggests that a more complete perspective of ROS-cytokine interaction is required. The present review focuses on two of the major cytokines that are demonstrably connected to oxidative stress--the pro-inflammatory tumor necrosis factor-alpha (TNF-alpha) and the anti-inflammatory interleukin-10 (IL-10)--and their interactions in cardiac remodeling and failure. It is proposed that an optimal balance between TNF-alpha and IL-10 may be of crucial importance in mitigating both inflammation and oxidative stress processes leading to heart failure.

The cardiac renin-angiotensin system is responsible for high-salt diet-induced left ventricular hypertrophy in mice

AIMS

This study aimed to determine the role of the renin-angiotensin system (RAS) in high-salt (HS) diet-induced left ventricular hypertrophy (LVH).

METHODS AND RESULTS

Swiss mice were subjected to regular salt (RS) diet (0.6% NaCl), HS diet (4% NaCl), and HS plus irbesartan (50 mg/kg/day) or ramipril (1 mg/kg/day). After 8 weeks, arterial pressure was similar in all groups and similar to baseline, whereas left ventricle/body weight ratio was higher in HS mice than in RS mice (P < 0.005). There were also significant increases in collagen density, angiotensin-converting enzyme activity, angiotensin II type 1 receptor (AT1 receptor) density, and extracellular signal-regulated kinase (ERK1/2) phosphorylation in the left ventricle. Interestingly, increases in wall thickness and ERK1 phosphorylation were more marked in the septum than in the rest of the left ventricle. Irbesartan or ramipril treatment prevented LVH and the increase in ERK phosphorylation and reduced collagen content and AT1 up-regulation but up-regulated AT2 receptors.

CONCLUSION

In normal mice, HS diet induces septum-predominant LVH and fibrosis through activation of the cardiac RAS-ERK pathway, which can be blocked by irbesartan or ramipril, indicating a key role of the cardiac RAS in HS diet-induced LVH.

Delayed cardiomyopathy in dystrophin deficient mdx mice relies on intrinsic glutathione resource

Oxidative stress contributes to the pathogenesis of Duchenne muscular dystrophy (DMD). Although they have been a model for DMD, mdx mice exhibit slowly developing cardiomyopathy. We hypothesized that disease process was delayed owing to the development of an adaptive mechanism against oxidative stress, involving glutathione synthesis. At 15 to 20 weeks of age, mdx mice displayed a 33% increase in blood glutathione levels compared with age-matched C57BL/6 mice. In contrast, cardiac glutathione content was similar in mdx and C57BL/6 mice as a result of the balanced increased expression of glutamate cysteine ligase catalytic and regulatory subunits ensuring glutathione synthesis in the mdx mouse heart, as well as increased glutathione peroxidase-1 using glutathione. Oral administration from 10 weeks of age of the glutamate cysteine ligase inhibitor, l-buthionine(S,R)-sulfoximine (BSO, 5 mmol/L), led to a 33% and 50% drop in blood and cardiac glutathione, respectively, in 15- to 20-week-old mdx mice. Moreover, 20-week-old BSO-treated mdx mice displayed left ventricular hypertrophy associated with diastolic dysfunction, discontinuities in beta-dystroglycan expression, micronecrosis and microangiopathic injuries. Examination of the glutathione status in four DMD patients showed that three displayed systemic glutathione deficiency as well. In conclusion, low glutathione resource hastens the onset of cardiomyopathy linked to a defect in dystrophin in mdx mice. This is relevant to the glutathione deficiency that DMD patients may suffer.

Infliximab-related hepatitis: discussion of a case and review of the literature

Despite its rarity, infliximab-related hepatitis constitutes a cutting edge and challenging problem. In December 2004, a drug warning was issued by the Food and Drug Administration to alert healthcare professionals to the risk of hepatotoxicity in course of infliximab therapy. Subsequently, several reports of probable infliximab hepatitis have been published and interest is growing in trying to elucidate the impact of these events on clinical practice. After discussing our case report, the main characteristics of infliximab-mediated liver injury are analyzed, coupled with a review of the medical literature. Infliximab seems to provoke both immunomediated and a direct liver injury, but how this latter happens remains unclear. Moreover, infliximab immunomediated liver dysfunction resembles that of autoimmune hepatitis type I, with elevation of antinuclear, anti-smooth muscle, anti-double-strand DNA antibodies, and a clear preference for female sex. Finally, a flow chart is proposed with the purpose to help clinicians in the management of patients who develop signs of liver dysfunction during treatment with infliximab.

Involvement of tumor necrosis factor-alpha in natriuretic response to systemic infusion of nitric oxide synthase inhibitor in anesthetized mice

Systemic infusion of TNF-alpha exerts renal vasoconstriction but caused marked natriuresis in mice. Similar renal responses were also observed during systemic infusion of nitric oxide (NO) synthase inhibitors as opposed to their usual antinatriuretic responses when administered intrarenally. In the present study, we examined the hypothesis that acute NO blockade systemically induces TNF-alpha generation. which induces this natriuretic response. Renal responses to intravenous infusion of the NO synthase inhibitor nitro-L-arginine methyl ester (L-NAME; 0.2 microg x min(-1) x g body wt(-1) for 85 min) and its impact on the plasma level of TNF-alpha were evaluated in anesthetized mice. Plasma TNF-alpha was undetected in untreated mice (n = 7) but was elevated in L-NAME-treated mice (109 +/- 22 pg/ml; P < 0.01 vs. untreated group; n = 7) along with an increase in TNF-alpha protein expression in kidney tissue. L-NAME infusion caused a usual increase in mean arterial pressure (MAP; 98 +/- 3 to 122 +/- 3 mmHg; P < 0.01) and decreases in renal blood flow (RBF; 8.6 +/- 0.3 to 4.4 +/- 0.2 ml x min(-1) x g(-1); P < 0.01) and glomerular filtration rate (GFR; 1.14 +/- 0.07 to 0.77 +/- 0.04 ml x min(-1) x g(-1); P < 0.01) with a marked increase in sodium excretion (U(Na)V; 0.48 +/- 0.10 to 3.52 +/- 0.85 micromol x min(-1) x g(-1); P < 0.01). Interestingly, in mice (n = 7) pretreated with the TNF-alpha blocker etanercept (5 mg/kg sc), the U(Na)V response to l-NAME infusion was markedly blunted (0.58 +/- 0.08 to 1.22 +/- 0.28 micromol x min(-1) x g(-1); P = NS) although responses for MAP, RBF, and GFR were mostly unchanged. However, pretreatment with the superoxide scavenger tempol in mice (n = 7) did not alter the U(Na)V response to L-NAME. These data demonstrate that L-NAME-induced natriuresis is mediated, at least in part, by concomitant generation of TNF-alpha during NO blockade.

Burn serum causes a CD14-dependent mitochondrial damage in primary cardiomyocytes

Studies from animal models suggest that myocardial mitochondrial damage contributes to cardiac dysfunction after burn injury. In this report, we used an ex vivo model of primary cardiomyocyte culture to investigate the mechanisms of burn-induced mitochondrial impairment. Briefly, blood serum was collected from Sprague-Dawley (SD) rats subjected to 40% total body surface area burn and added (10% vol/vol) to primary cardiomyocytes prepared from SD rats. The effect of the burn serum on mitochondrial function and membrane integrity in the myocytes was analyzed. Exposure of myocytes to burn serum doubled the mitochondrial membrane damage measured by two independent assays. This treatment also significantly elevated mitochondrial oxidative stress, indicated by a more than 30% increase in lipid oxidation. Downregulation of mitochondrial antioxidant defense was also evident since the activities of the antioxidant enzymes superoxide dismutase and glutathione peroxidase were reduced by about 30% and 50%, respectively. Burn serum also induced deficiency of mitochondrial metabolism, indicated by a 30% decrease in the activity of cytochrome c oxidase. These mitochondrial dysfunctions appear to be generated by oxidative stress because burn serum induced a significant increase of mitochondrial oxygen species (mtROS) in cardiomyocytes, and pretreatment of cardiomyocytes with the antioxidant N-acetyl-cysteine prevented the mitochondrial damages induced by burn serum. Remarkably, the increase in mtROS was abolished by an antibody-mediated blockade of CD14. Furthermore, burn injury-induced mitochondrial damage in cardiomyocytes was prevented in CD14 knockout mice. Taken together, these data suggested that burn injury produces CD14-dependent mitochondrial damage via oxidative stress in myocardium.

Practical prevention of cardiac remodeling and atrial fibrillation with full-spectrum antioxidant therapy and ancillary strategies

A wealth of research data points to increased oxidative stress as a key driver of the cardiac remodeling triggered by chronic pressure overload, loss of functional myocardial tissue, or atrial fibrillation. Oxidative stress is a mediator of the cardiomyocyte hypertrophy and apoptosis, the cardiac fibrosis, and the deficits in cardiac function which typify this syndrome, and may play a role in initiating and sustaining atrial fibrillation. Nox2- and Nox4-dependent NADPH oxidase activity appears to be a major source of this oxidative stress, and oxidants can induce conformational changes in xanthine dehydrogenase, nitric oxide synthase, and the mitochondrial respiratory chain which increase their capacity to generate superoxide as well. Consistent with these insights, various synthetic antioxidants have been shown to suppress cardiac remodeling in rodents subjected to myocardial infarction, aortic constriction, or rapid atrial pacing. It may prove feasible to achieve comparable benefits in humans through use of a "full-spectrum antioxidant therapy" (FSAT) that features a complementary array of natural antioxidants. Spirulina is a rich source of phycocyanobilin, a derivative and homolog of biliverdin that appears to mimic the potent inhibitory impact of biliverdin and free bilirubin on NADPH oxidase activity. Mega-doses of folate can markedly increase intracellular levels of tetrahydrofolates which have potent and versatile radical-scavenging activities - including efficient quenching of peroxynitrite-derived radicals Supplemental coenzyme Q10, already shown to improve heart function in clinical congestive failure, can provide important antioxidant protection to mitochondria. Phase 2 inducer nutraceuticals such as lipoic acid, administered in conjunction with N-acetylcysteine, have the potential to blunt the impact of oxidative stress by boosting myocardial levels of glutathione. While taurine can function as an antioxidant for myeloperoxidase-derived radicals, its positive inotropic effect on the failing heart seems more likely to reflect an effect on intracellular calcium dynamics. These measures could aid control of cardiac modeling less directly by lowering elevated blood pressure, or by aiding the perfusion of ischemic cardiac regions through an improvement in coronary endothelial function. Since nitric oxide functions physiologically to oppose cardiomyocyte hypertrophy and cardiac fibrosis, and is also a key regulator of blood pressure and endothelial function, cocoa flavanols - which provoke endothelial release of nitric oxide - might usefully complement the antioxidant measures recommended here.

Glutathione deficiency in cardiac patients is related to the functional status and structural cardiac abnormalities

Background

The tripeptide glutathione (L-gamma-glutamyl-cysteinyl-glycine) is essential to cell survival, and deficiency in cardiac and systemic glutathione relates to heart failure progression and cardiac remodelling in animal models. Accordingly, we investigated cardiac and blood glutathione levels in patients of different functional classes and with different structural heart diseases.

Methods

Glutathione was measured using standard enzymatic recycling method in venous blood samples obtained from 91 individuals, including 15 healthy volunteers and 76 patients of New York Heart Association (NYHA) functional class I to IV, undergoing cardiac surgery for coronary artery disease, aortic stenosis or terminal cardiomyopathy. Glutathione was also quantified in right atrial appendages obtained at the time of surgery.

Results

In atrial tissue, glutathione was severely depleted (−58%) in NYHA class IV patients compared to NYHA class I patients (P = 0.002). In patients with coronary artery disease, this depletion was related to the severity of left ventricular dysfunction (P = 0.006). Compared to healthy controls, blood glutathione was decreased by 21% in NYHA class I patients with structural cardiac disease (P<0.01), and by 40% in symptomatic patients of NYHA class II to IV (P<0.0001). According to the functional NYHA class, significant depletion in blood glutathione occurred before detectable elevation in blood sTNFR1, a marker of symptomatic heart failure severity, as shown by the exponential relationship between these two parameters in the whole cohort of patients (r = 0.88).

Conclusions

This study provides evidence that cardiac and systemic glutathione deficiency is related to the functional status and structural cardiac abnormalities of patients with cardiac diseases. These data also suggest that blood glutathione test may be an interesting new biomarker to detect asymptomatic patients with structural cardiac abnormalities.