Vitamin E supplementation and cardiovascular events in high-risk patients

Dietary supplements and disease prevention - a global overview

Dietary supplements are widely used and offer the potential to improve health if appropriately targeted to those in need. Inadequate nutrition and micronutrient deficiencies are prevalent conditions that adversely affect global health. Although improvements in diet quality are essential to address these issues, dietary supplements and/or food fortification could help meet requirements for individuals at risk of deficiencies. For example, supplementation with vitamin A and iron in developing countries, where women of reproductive age, infants and children often have deficiencies; with folic acid among women of reproductive age and during pregnancy; with vitamin D among infants and children; and with calcium and vitamin D to ensure bone health among adults aged ≥65 years. Intense debate surrounds the benefits of individual high-dose micronutrient supplementation among well-nourished individuals because the alleged beneficial effects on chronic diseases are not consistently supported. Daily low-dose multivitamin supplementation has been linked to reductions in the incidence of cancer and cataracts, especially among men. Baseline nutrition is an important consideration in supplementation that is likely to modify its effects. Here, we provide a detailed summary of dietary supplements and health outcomes in both developing and developed countries to help guide decisions about dietary supplement recommendations.

Independent design and conduct of clinical trials

Randomized clinical trials (RCTs) have justifiably become the cornerstone for the evaluation of virtually any kind of intervention: drugs, surgical or diagnostic procedures, behavioural modifications, health policies and even systems of care. This commentary focuses on two issues related to independence in clinical trials: first, the independence to ask important questions, and second, independence from bias in the conduct, analysis and reporting of trials, which can lead to misleading conclusions. The most frequent type of RCT are those evaluating therapies, and much of this commentary will be focused on issues relevant to such trials, although the principles apply generally.

Microvascular Changes in the Diabetic Foot

Impairment of the microcirculation of diabetic patients may contribute to secondary complications in the lower extremity, such as foot infections and ulcerations. These microcirculatory changes, which are mainly functional rather than structural, are responsible for the impaired ability of the microvasculature to vasodilate in response to injury. Dysfunction of vascular endothelial cells and vascular smooth muscle cells both contribute to the reduction in vasodilation that is observed in diabetic patients. Nerve-axon reflex related microvascular vasodilation is also impaired in the diabetic population, and there is a growing belief that both the failure of the vessels to dilate and the impairment of the nerve axon reflex are major causes for impaired wound healing in diabetic patients. Further studies are necessary to clarify the precise etiology of endothelial and smooth muscle dysfunction in diabetic patients so that potential therapeutic interventions may be identified.

Role of PGC-1α in Vascular Regulation: Implications for Atherosclerosis

Mitochondrial dysfunction results in high levels of oxidative stress and mitochondrial damage, leading to disruption of endothelial homeostasis. Recent discoveries have clarified several pathways, whereby mitochondrial dysregulation contributes to endothelial dysfunction and vascular disease burden. One such pathway centers around peroxisome proliferator receptor-γ coactivator 1α (PGC-1α), a transcriptional coactivator linked to mitochondrial biogenesis and antioxidant defense, among other functions. Although primarily investigated for its therapeutic potential in obesity and skeletal muscle differentiation, the ability of PGC-1α to alter a multitude of cellular functions has sparked interest in its role in the vasculature. Within this context, recent studies demonstrate that PGC-1α plays a key role in endothelial cell and smooth muscle cell regulation through effects on oxidative stress, apoptosis, inflammation, and cell proliferation. The ability of PGC-1α to affect these parameters is relevant to vascular disease progression, particularly in relation to atherosclerosis. Upregulation of PGC-1α can prevent the development of, and even encourage regression of, atherosclerotic lesions. Therefore, PGC-1α is poised to serve as a promising target in vascular disease. This review details recent findings related to PGC-1α in vascular regulation, regulation of PGC-1α itself, the role of PGC-1α in atherosclerosis, and therapies that target this key protein.

Mitochondrial quality control in the diabetic heart

Diabetes is a well-known risk factor for heart failure. Diabetic heart damage is closely related to mitochondrial dysfunction and increased ROS generation. However, clinical trials have shown no effects of antioxidant therapies on heart failure in diabetic patients, suggesting that simply antagonizing existing ROS by antioxidants is not sufficient to reduce diabetic cardiac injury. A potentially more effective treatment strategy may be to enhance the overall capacity of mitochondrial quality control to maintain a pool of healthy mitochondria that are needed for supporting cardiac contractile function in diabetic patients. Mitochondrial quality is controlled by a number of coordinated mechanisms including mitochondrial fission and fusion, mitophagy and biogenesis. The mitochondrial damage consistently observed in the diabetic hearts indicates a failure of the mitochondrial quality control mechanisms. Recent studies have demonstrated a crucial role for each of these mechanisms in cardiac homeostasis and have begun to interrogate the relative contribution of insufficient mitochondrial quality control to diabetic cardiac injury. In this review, we will present currently available literature that links diabetic heart disease to the dysregulation of major mitochondrial quality control mechanisms. We will discuss the functional roles of these mechanisms in the pathogenesis of diabetic heart disease and their potentials for targeted therapeutical manipulation.

Compartment-specific Control of Reactive Oxygen Species Scavenging by Antioxidant Pathway Enzymes

Oxidative stress arises from an imbalance in the production and scavenging rates of reactive oxygen species (ROS) and is a key factor in the pathophysiology of cardiovascular disease and aging. The presence of parallel pathways and multiple intracellular compartments, each having its own ROS sources and antioxidant enzymes, complicates the determination of the most important regulatory nodes of the redox network. Here we quantified ROS dynamics within specific intracellular compartments in the cytosol and mitochondria and determined which scavenging enzymes exert the most control over antioxidant fluxes in H9c2 cardiac myoblasts. We used novel targeted viral gene transfer vectors expressing redox-sensitive GFP fused to sensor domains to measure H2O2 or oxidized glutathione. Using genetic manipulation in heart-derived H9c2 cells, we explored the contribution of specific antioxidant enzymes to ROS scavenging and glutathione redox potential within each intracellular compartment. Our findings reveal that antioxidant flux is strongly dependent on mitochondrial substrate catabolism, with availability of NADPH as a major rate-controlling step. Moreover, ROS scavenging by mitochondria significantly contributes to cytoplasmic ROS handling. The findings provide fundamental information about the control of ROS scavenging by the redox network and suggest novel interventions for circumventing oxidative stress in cardiac cells.

Role of Renal Oxidative Stress in the Pathogenesis of the Cardiorenal Syndrome

Renal dysfunction and heart failure commonly co-exist; it is termed the cardiorenal syndrome (CRS). This combination of renal and cardiac impairment presents a substantial clinical challenge and is associated with adverse prognosis. The pathogenesis of the CRS is complex, including chronic activation of the renin-angiotensin-aldosterone system (RAAS) and the sympathetic nervous system, together with reduced renal perfusion. Chronic activation of the RAAS can impair mitochondrial function, and increase mitochondrial derived oxidative stress which in turn can lead to renal injury and sodium and water retention. For example, it has been shown that exogenous Ang II augments renal mitochondrial oxidative stress, reduces GFR and induces albuminuria in rats with heart failure. Administration of Ang II also augmented renal mitochondrial dysfunction in aged mice. Current treatments for CRS, including angiotensin-converting enzyme inhibitors, exert limited renal protection if any at all. Therefore, novel treatments particularly those that can target renal mechanisms downstream to chronic activation of the renal renin-angiotensin system are likely to exert renoprotection in the setting of CRS.

Clinical implications of oxidative stress and potential role of natural antioxidants in diabetic vascular complications

AIMS

The possible link between hyperglycaemia-induced oxidative stress (OxS) and diabetic complications is suggested by many in vitro studies. However, not much attention has been paid to the clinical evidence supporting this hypothesis, as well as to their possible therapeutic implications.

DATA SYNTHESIS

Some prospective studies show a direct correlation between an increase in OxS biomarkers and the appearance of diabetes complications. This is consistent with the evidence that any acute increase of glycaemia, particularly post-prandial, and hypoglycaemia causes endothelial dysfunction and inflammation, through the generation of an OxS. However, the detection of free radicals is difficult as they are highly reactive molecules with a short half-life. Instead, the metabolites of OxS are measured. Interventional trials with supplemented antioxidants have failed to show any beneficial effects. Conversely, natural foods show very promising results.

CONCLUSIONS

The "new antioxidant" approach includes the possibility of controlling free radical production and increasing intracellular antioxidant defence, a concept different from the old one, when antioxidant activities implied scavenging the free radicals already produced. A synergistic action in this respect could convincingly be obtained with a balanced 'Mediterranean Diet' (MedD) type. Early intensive glucose control is still the best strategy to avoid OxS and its associated diabetes complications.

Antioxidant Supplementation in the Treatment of Aging-Associated Diseases

Oxidative stress is generally considered as the consequence of an imbalance between pro- and antioxidants species, which often results into indiscriminate and global damage at the organismal level. Elderly people are more susceptible to oxidative stress and this depends, almost in part, from a decreased performance of their endogenous antioxidant system. As many studies reported an inverse correlation between systemic levels of antioxidants and several diseases, primarily cardiovascular diseases, but also diabetes and neurological disorders, antioxidant supplementation has been foreseen as an effective preventive and therapeutic intervention for aging-associated pathologies. However, the expectations of this therapeutic approach have often been partially disappointed by clinical trials. The interplay of both endogenous and exogenous antioxidants with the systemic redox system is very complex and represents an issue that is still under debate. In this review a selection of recent clinical studies concerning antioxidants supplementation and the evaluation of their influence in aging-related diseases is analyzed. The controversial outcomes of antioxidants supplementation therapies, which might partially depend from an underestimation of the patient specific metabolic demand and genetic background, are presented.

Astaxanthin has no effect on arterial stiffness, oxidative stress, or inflammation in renal transplant recipients: a randomized controlled trial (the XANTHIN trial)

BACKGROUND

There is evidence that renal transplant recipients have accelerated atherosclerosis that is manifest by increased cardiovascular morbidity and mortality. The high incidence of atherosclerosis is, in part, related to increased arterial stiffness, vascular dysfunction, elevated oxidative stress, and inflammation associated with immunosuppressive therapy. The carotenoid astaxanthin has shown potent antioxidant and anti-inflammatory properties.

OBJECTIVE

The aim was to investigate the effects of oral astaxanthin on arterial stiffness, oxidative stress, and inflammation in renal transplant recipients.

DESIGN

This trial used a randomized, placebo-controlled, double-blind design in which 61 patients received either 12 mg astaxanthin/d or an identical placebo orally for 1 y. Primary outcomes were 1) arterial stiffness measured by aortic pulse wave velocity (PWV), 2) oxidative stress assessed by total plasma F2-isoprostanes, and 3) inflammation assessed by plasma pentraxin-3. Secondary outcomes included vascular function, carotid artery intima-media thickness, augmentation index, central blood pressure, subendocardial viability ratio, and additional measures of oxidative stress and inflammation. Patients underwent assessments at baseline and at 6 and 12 mo.

RESULTS

Fifty-eight participants completed the study. There were no significant between-group differences in the changes in any of the primary outcome measures (PWV changed by +9.5% and +6.0%, F2-isoprostanes changed by -3.0% and -9.7%, and pentraxin-3 changed by +50.6% and -11.0% in the placebo and astaxanthin groups, respectively). There were no significant between-group differences in secondary outcome measures. Larger-than-expected variability decreased the power of the study and increased the possibility of a type 2 statistical error.

CONCLUSION

Astaxanthin (12 mg/d for 12 mo) had no effect on arterial stiffness, oxidative stress, or inflammation in renal transplant recipients. This trial was registered at the Australian New Zealand Clinical Trials Registry (http://www.anzctr.org.au/) as ACTRN12608000159358.

Mitochondrial Therapies in Heart Failure

The current therapy for patients with stable systolic heart failure is largely limited to treatments that interfere with neurohormonal activation. Critical pathophysiological hallmarks of heart failure are an energetic deficit and oxidative stress, and both may be the result of mitochondrial dysfunction. This dysfunction is not (only) the result of defect within mitochondria per se, but is in particular traced to defects in intermediary metabolism and of the regulatory interplay between excitation-contraction coupling and mitochondrial energetics, where defects of cytosolic calcium and sodium handling in failing hearts may play important roles. In the past years, several therapies targeting mitochondria have emerged with promising results in preclinical models. Here, we discuss the mechanisms and results of these mitochondria-targeted therapies, but also of interventions that were not primarily thought to target mitochondria but may have important impact on mitochondrial biology as well, such as iron and exercise. Future research should be directed at further delineating the details of mitochondrial dysfunction in patients with heart failure to further optimize these treatments.

Pharmacology and Clinical Drug Candidates in Redox Medicine

SIGNIFICANCE

Oxidative stress is suggested to be a disease mechanism common to a wide range of disorders affecting human health. However, so far, the pharmacotherapeutic exploitation of this, for example, based on chemical scavenging of pro-oxidant molecules, has been unsuccessful.

RECENT ADVANCES

An alternative emerging approach is to target the enzymatic sources of disease-relevant oxidative stress. Several such enzymes and isoforms have been identified and linked to different pathologies. For some targets, the respective pharmacology is quite advanced, that is, up to late-stage clinical development or even on the market; for others, drugs are already in clinical use, although not for indications based on oxidative stress, and repurposing seems to be a viable option.

CRITICAL ISSUES

For all other targets, reliable preclinical validation and drug ability are key factors for any translation into the clinic. In this study, specific pharmacological agents with optimal pharmacokinetic profiles are still lacking. Moreover, these enzymes also serve largely unknown physiological functions and their inhibition may lead to unwanted side effects.

FUTURE DIRECTIONS

The current promising data based on new targets, drugs, and drug repurposing are mainly a result of academic efforts. With the availability of optimized compounds and coordinated efforts from academia and industry scientists, unambiguous validation and translation into proof-of-principle studies seem achievable in the very near future, possibly leading towards a new era of redox medicine.

Antioxidants in Translational Medicine

SIGNIFICANCE

It is generally accepted that reactive oxygen species (ROS) scavenging molecules or antioxidants exert health-promoting effects and thus their consumption as food additives and nutraceuticals has been greatly encouraged. Antioxidants may be beneficial in situations of subclinical deficiency and increased demand or acutely upon high-dose infusion. However, to date, there is little clinical evidence for the long-term benefit of most antioxidants. Alarmingly, recent evidence points even to health risks, in particular for supplements of lipophilic antioxidants.

RECENT ADVANCES

The biological impact of ROS depends not only on their quantities but also on their chemical nature, (sub)cellular and tissue location, and the rates of their formation and degradation. Moreover, ROS serve important physiological functions; thus, inappropriate removal of ROS may cause paradoxical reductive stress and thereby induce or promote disease.

CRITICAL ISSUES

Any recommendation on antioxidants must be based on solid clinical evidence and patient-relevant outcomes rather than surrogate parameters.

FUTURE DIRECTIONS

Such evidence-based use may include site-directed application, time-limited high dosing, (functional) pharmacological repair of oxidized biomolecules, and triggers of endogenous antioxidant response systems. Ideally, these approaches need guidance by patient stratification through predictive biomarkers and possibly imaging modalities.

Concordance of Results from Randomized and Observational Analyses within the Same Study: A Re-Analysis of the Women's Health Initiative Limited-Access Dataset

Background

Observational studies (OS) and randomized controlled trials (RCTs) often report discordant results. In the Women’s Health Initiative Calcium and Vitamin D (WHI CaD) RCT, women were randomly assigned to CaD or placebo, but were permitted to use personal calcium and vitamin D supplements, creating a unique opportunity to compare results from randomized and observational analyses within the same study.

Methods

WHI CaD was a 7-year RCT of 1g calcium/400IU vitamin D daily in 36,282 post-menopausal women. We assessed the effects of CaD on cardiovascular events, death, cancer and fracture in a randomized design- comparing CaD with placebo in 43% of women not using personal calcium or vitamin D supplements- and in a observational design- comparing women in the placebo group (44%) using personal calcium and vitamin D supplements with non-users. Incidence was assessed using Cox proportional hazards models, and results from the two study designs deemed concordant if the absolute difference in hazard ratios was ≤0.15. We also compared results from WHI CaD to those from the WHI Observational Study(WHI OS), which used similar methodology for analyses and recruited from the same population.

Results

In WHI CaD, for myocardial infarction and stroke, results of unadjusted and 6/8 covariate-controlled observational analyses (age-adjusted, multivariate-adjusted, propensity-adjusted, propensity-matched) were not concordant with the randomized design results. For death, hip and total fracture, colorectal and total cancer, unadjusted and covariate-controlled observational results were concordant with randomized results. For breast cancer, unadjusted and age-adjusted observational results were concordant with randomized results, but only 1/3 other covariate-controlled observational results were concordant with randomized results. Multivariate-adjusted results from WHI OS were concordant with randomized WHI CaD results for only 4/8 endpoints.

Conclusions

Results of randomized analyses in WHI CaD were concordant with observational analyses for 5/8 endpoints in WHI CaD and 4/8 endpoints in WHI OS.

Impact of eNOS-Dependent Oxidative Stress on Endothelial Function and Neointima Formation

AIMS

Vascular oxidative stress generated by endothelial NO synthase (eNOS) was observed in experimental and clinical cardiovascular disease, but its relative importance for vascular pathologies is unclear. We investigated the impact of eNOS-dependent vascular oxidative stress on endothelial function and on neointimal hyperplasia.

RESULTS

A dimer-destabilized mutant of bovine eNOS where cysteine 101 was replaced by alanine was cloned and introduced into an eNOS-deficient mouse strain (eNOS-KO) in an endothelial-specific manner. Destabilization of mutant eNOS in cells and eNOS-KO was confirmed by the reduced dimer/monomer ratio. Purified mutant eNOS and transfected cells generated less citrulline and NO, respectively, while superoxide generation was enhanced. In eNOS-KO, introduction of mutant eNOS caused a 2.3-3.7-fold increase in superoxide and peroxynitrite formation in the aorta and myocardium. This was completely blunted by an NOS inhibitor. Nevertheless, expression of mutant eNOS in eNOS-KO completely restored maximal aortic endothelium-dependent relaxation to acetylcholine. Neointimal hyperplasia induced by carotid binding was much larger in eNOS-KO than in mutant eNOS-KO and C57BL/6, while the latter strains showed comparable hyperplasia. Likewise, vascular remodeling was blunted in eNOS-KO only.

INNOVATION

Our results provide the first in vivo evidence that eNOS-dependent oxidative stress is unlikely to be an initial cause of impaired endothelium-dependent vasodilation and/or a pathologic factor promoting intimal hyperplasia. These findings highlight the importance of other sources of vascular oxidative stress in cardiovascular disease.

CONCLUSION

eNOS-dependent oxidative stress is unlikely to induce functional vascular damage as long as concomitant generation of NO is preserved. This underlines the importance of current and new therapeutic strategies in improving endothelial NO generation.

The Cardioprotective Effect of Vitamin E (Alpha-Tocopherol) Is Strongly Related to Age and Gender in Mice

Vitamin E (VitE) only prevented cardiovascular diseases in some patients and the mechanisms remain unknown. VitE levels can be affected by aging and gender. We hypothesize that age and gender can influence VitE’s cardioprotective effect. Mice were divided into 4 groups according to age and gender, and each group of mice were divided into a control group and a VitE group. The mice were administered water or VitE for 21 days; Afterward, the cardiac function and myocardial infarct size and cardiomyocyte apoptosis were measured after myocardial ischemia reperfusion(MI/R). VitE may significantly improved cardiac function in young male mice and aged female mice by enhancing ERK1/2 activity and reducing JNK activity. Enhanced expression of HSP90 and Bcl-2 were also seen in young male mice. No changes in cardiac function and cardiac proteins were detected in aged male mice and VitE was even liked to exert a reverse effect in cardiac function in young mice by enhancing JNK activity and reducing Bcl-2 expression. Those effects were in accordance with the changes of myocardial infarction size and cardiomyocyte apoptosis in each group of mice. VitE may reduce MI/R injury by inhibiting cardiomyocyte apoptosis in young male mice and aged female mice but not in aged male mice. VitE was possibly harmful for young female mice, shown as increased cardiomyocyte apoptosis after MI/R. Thus, we speculated that the efficacy of VitE in cardiac protection was associated with age and gender.

c-Jun N-terminal kinase attenuates TNFα signaling by reducing Nox1-dependent endosomal ROS production in vascular smooth muscle cells

Tumor necrosis factor-α (TNFα), a proinflammatory cytokine, causes vascular smooth muscle cell (VSMC) proliferation and migration and promotes inflammatory vascular lesions. Nuclear factor-kappa B (NF-κB) activation by TNFα requires endosomal superoxide production by Nox1. In endothelial cells, TNFα stimulates c-Jun N-terminal kinase (JNK), which inhibits NF-κB signaling. The mechanism by which JNK negatively regulates TNFα-induced NF-κB activation has not been defined. We hypothesized that JNK modulates NF-κB activation in VSMC, and does so via a Nox1-dependent mechanism. TNFα-induced NF-κB activation was TNFR1- and endocytosis-dependent. Inhibition of endocytosis with dominant-negative dynamin (DynK44A) potentiated TNFα-induced JNK activation, but decreased ERK activation, while p38 kinase phosphorylation was not altered. DynK44A attenuated intracellular, endosomal superoxide production in wild-type (WT) VSMC, but not in NADPH oxidase 1 (Nox1) knockout (KO) cells. siRNA targeting JNK1 or JNK2 potentiated, while a JNK activator (anisomycin) inhibited, TNFα-induced NF-κB activation in WT, but not in Nox1 KO cells. TNFα-stimulated superoxide generation was enhanced by JNK1 inhibition in WT, but not in Nox1 KO VSMC. These data suggest that JNK suppresses the inflammatory response to TNFα by reducing Nox1-dependent endosomal ROS production. JNK and endosomal superoxide may represent novel targets for pharmacologic modulation of TNFα signaling and vascular inflammation.

Tocopherols in the Prevention and Treatment of Atherosclerosis and Related Cardiovascular Disease

Oxidants/antioxidants play an important role in cellular homeostasis. The human body has endogenous molecules that work as antioxidants, such as glutathione, superoxide dismutase, peroxidases, and catalase. Exogenous substances in the diet, such as β-carotene, ascorbate, and vitamin E, are vital antioxidants. Of these, vitamin E is likely the most important antioxidant in the human diet, and many studies have been performed to elucidate its role in health and disease. Vitamin E is a family of several compounds, of which α-tocopherol is the most widely known analog. α-Tocopherol exhibits antioxidative property in vitro and inhibits oxidation of low-density lipoprotein cholesterol. In addition, α-tocopherol shows anti-inflammatory activity and modulates expression of proteins involved in the uptake, transport, and degradation of atherogenic lipids. Though α-tocopherol exhibits important antioxidant, anti-inflammatory, and antiatherogenic features in vitro, α-tocopherol supplements have failed to consistently reduce atherosclerosis-related events in human trials. The conflicting results have led to reconsideration of the importance previously given to α-tocopherol and led to interest in other members of vitamin E family, especially γ-tocopherol, which exerts a much more potent antioxidant, anti-inflammatory, and cardioprotective effect than α-tocopherol. This reconsideration has been backed by solid laboratory and clinical research. We suggest that the absence of γ-tocopherol in traditional preparations may be one reason for the lack of consistent salutary effects of vitamin E preparations in clinical trials. This review summarizes our current understanding of tocopherols as antioxidant molecules and emerging evidence of an important role of γ-tocopherol in the pathophysiology of atherosclerosis-related cardiovascular disease.

Exploiting the Pleiotropic Antioxidant Effects of Established Drugs in Cardiovascular Disease

Cardiovascular disease is a leading cause of death and reduced quality of life worldwide. Arterial vessels are a primary target for endothelial dysfunction and atherosclerosis, which is accompanied or even driven by increased oxidative stress. Recent research in this field identified different sources of reactive oxygen and nitrogen species contributing to the pathogenesis of endothelial dysfunction. According to lessons from the past, improvement of endothelial function and prevention of cardiovascular disease by systemic, unspecific, oral antioxidant therapy are obviously too simplistic an approach. Source- and cell organelle-specific antioxidants as well as activators of intrinsic antioxidant defense systems might be more promising. Since basic research demonstrated the contribution of different inflammatory cells to vascular oxidative stress and clinical trials identified chronic inflammatory disorders as risk factors for cardiovascular events, atherosclerosis and cardiovascular disease are closely associated with inflammation. Therefore, modulation of the inflammatory response is a new and promising approach in the therapy of cardiovascular disease. Classical anti-inflammatory therapeutic compounds, but also established drugs with pleiotropic immunomodulatory abilities, demonstrated protective effects in various models of cardiovascular disease. However, results from ongoing clinical trials are needed to further evaluate the value of immunomodulation for the treatment of cardiovascular disease.

Antioxidants in Cardiovascular Therapy: Panacea or False Hope?

Oxidative stress is a key feature of the atherothrombotic process involved in the etiology of heart attacks, ischemic strokes, and peripheral arterial disease. It stands to reason that antioxidants represent a credible therapeutic option to prevent disease progression and thereby improve outcome, but despite positive findings from in vitro studies, clinical trials have failed to consistently show benefit. The aim of this review is to re-appraise the concept of antioxidants in the prevention and management of cardiovascular disease. In particular, the review will explore the reasons behind failed antioxidant strategies with vitamin supplements and will evaluate how flavonoids might improve cardiovascular function despite bioavailability that is not sufficiently high to directly influence antioxidant capacity. As well as reaching conclusions relating to those antioxidant strategies that might hold merit, the major myths, limitations, and pitfalls associated with this research field are explored.

The mitochondria in diabetic heart failure: from pathogenesis to therapeutic promise

SIGNIFICANCE

Diabetes is an important risk factor for the development of heart failure (HF). Given the increasing prevalence of diabetes in the population, strategies are needed to reduce the burden of HF in these patients.

RECENT ADVANCES

Diabetes is associated with several pathologic findings in the heart including dysregulated metabolism, lipid accumulation, oxidative stress, and inflammation. Emerging evidence suggests that mitochondrial dysfunction may be a central mediator of these pathologic responses. The development of therapeutic approaches targeting mitochondrial biology holds promise for the management of HF in diabetic patients.

CRITICAL ISSUES

Despite significant data implicating mitochondrial pathology in diabetic cardiomyopathy, the optimal pharmacologic approach to improve mitochondrial function remains undefined.

FUTURE DIRECTIONS

Detailed mechanistic studies coupled with more robust clinical phenotyping will be necessary to develop novel approaches to improve cardiac function in diabetes. Moreover, understanding the interplay between diabetes and other cardiac stressors (hypertension, ischemia, and valvular disease) will be of the utmost importance for clinical translation of scientific discoveries made in this field.

Assessment of vibration of effects due to model specification can demonstrate the instability of observational associations

OBJECTIVES

Model specification-what adjusting variables are analytically modeled-may influence results of observational associations. We present a standardized approach to quantify the variability of results obtained with choices of adjustments called the "vibration of effects" (VoE).

STUDY DESIGN AND SETTING

We estimated the VoE for 417 clinical, environmental, and physiological variables in association with all-cause mortality using National Health and Nutrition Examination Survey data. We selected 13 variables as adjustment covariates and computed 8,192 Cox models for each of 417 variables' associations with all-cause mortality.

RESULTS

We present the VoE by assessing the variance of the effect size and in the -log10(P-value) obtained by different combinations of adjustments. We present whether there are multimodality patterns in effect sizes and P-values and the trajectory of results with increasing adjustments. For 31% of the 417 variables, we observed a Janus effect, with the effect being in opposite direction in the 99th versus the 1st percentile of analyses. For example, the vitamin E variant α-tocopherol had a VoE that indicated higher and lower risk for mortality.

CONCLUSION

Estimating VoE offers empirical estimates of associations are under different model specifications. When VoE is large, claims for observational associations should be very cautious.

Role of Vitamin D deficiency in extraskeletal complications: predictor of health outcome or marker of health status?

The relationship of vitamin D with extraskeletal complications, such as cardiovascular disease, cancer, and autoimmune disease, is of major interest considering its roles in key biological processes and the worldwide high prevalence of vitamin D deficiency. However, the causal relationships between vitamin D and most extraskeletal complications are weak. Currently, a heated debate over vitamin D is being conducted according to two hypotheses. In this review, we first present the different arguments that suggest a major role of vitamin D in a very broad type of extraskeletal complications (hypothesis #1). We then present results from recent meta-analyses of randomized controlled trials indicating a lack of association of vitamin D with major extraskeletal complications (hypothesis #2). We discuss different issues (e.g., causality, confounding, reverse causation, misclassification, and Mendelian randomization) that contribute to the favoring of one hypothesis over the other. While ultimately only one hypothesis is correct, we anticipate that the results from the ongoing randomized controlled trials will be unlikely to reconcile the divided experts.

Are reactive oxygen species still the basis for diabetic complications?

Despite the wealth of pre-clinical support for a role for reactive oxygen and nitrogen species (ROS/RNS) in the aetiology of diabetic complications, enthusiasm for antioxidant therapeutic approaches has been dampened by less favourable outcomes in large clinical trials. This has necessitated a re-evaluation of pre-clinical evidence and a more rational approach to antioxidant therapy. The present review considers current evidence, from both pre-clinical and clinical studies, to address the benefits of antioxidant therapy. The main focus of the present review is on the effects of direct targeting of ROS-producing enzymes, the bolstering of antioxidant defences and mechanisms to improve nitric oxide availability. Current evidence suggests that a more nuanced approach to antioxidant therapy is more likely to yield positive reductions in end-organ injury, with considerations required for the types of ROS/RNS involved, the timing and dosage of antioxidant therapy, and the selective targeting of cell populations. This is likely to influence future strategies to lessen the burden of diabetic complications such as diabetes-associated atherosclerosis, diabetic nephropathy and diabetic retinopathy.

Natural products for the management of type 2 diabetes mellitus and comorbid conditions

OBJECTIVE

To provide pharmacists with practical information to guide consumers in their choices of herbal products and dietary supplements for the management of type 2 diabetes mellitus (T2DM) and its comorbid disease states.

SUMMARY

The herbal and dietary supplement market has grown exponentially over the past decade as Americans increasingly use such agents for generalized health and the prevention and treatment of chronic disease states.1 Pharmacist advice is often requested on the use of these agents for the management of T2DM; however, this is an area that has insufficient evidence to support confident recommendations. Many published studies involving herbal agents and dietary supplements are small and poorly designed, with heterogeneous results. Pharmacists should be aware of the safety and efficacy data available for these agents, recognize potential drug interactions, and identify acceptable manufactured products.

CONCLUSION

The strongest scientific evidence for blood glucose lowering effect is associated with alpha-lipoic acid and fenugreek. There is also good evidence supporting the use of ivy gourd, gymnema, and vitamin E for management of hyperglycemia; however, caution should be used when recommending vitamin E. Pharmacists should advise consumers to disclose use of any of these products to all of their health care providers.

Supplementation with vitamin E alone is associated with reduced myocardial infarction: a meta-analysis

BACKGROUND AND AIMS

Previous meta-analyses of interventional trials with vitamin E provided negative results but it remains unclear if this vitamin has some influence on cardiovascular events when supplemented alone. The aim of this study was to compare the effect of vitamin E alone or in combination with other antioxidants on myocardial infarction.

METHODS AND RESULTS

Pubmed, ISI Web of Science, SCOPUS and Cochrane database were searched without language restrictions. We investigated randomized clinical trials studying the effect of vitamin E supplementation on myocardial infarction. Sixteen randomized controlled trials of vitamin E treatment were analyzed in this meta-analysis. The dose range for vitamin E was 33-800IU. Follow-up ranged from 0.5 to 9.4 years. Compared to controls, vitamin E given alone significantly decreased myocardial infarction (3.0% vs 3.4%) (random effects R.R.: 0.82; 95% C.I., 0.70-0.96; p = 0.01). This effect was driven by reduction of fatal myocardial infarction (random effects R.R.: 0.84; 95% C.I., 0.73-0.96; p = 0.01).

CONCLUSIONS

When supplemented alone, vitamin E reduces myocardial infarction in interventional trials while it appears ineffective when associated with other antioxidants.

Mitochondria as key targets of cardioprotection in cardiac ischemic disease: role of thyroid hormone triiodothyronine

Ischemic heart disease is the major cause of mortality and morbidity worldwide. Early reperfusion after acute myocardial ischemia has reduced short-term mortality, but it is also responsible for additional myocardial damage, which in the long run favors adverse cardiac remodeling and heart failure evolution. A growing body of experimental and clinical evidence show that the mitochondrion is an essential end effector of ischemia/reperfusion injury and a major trigger of cell death in the acute ischemic phase (up to 48–72 h after the insult), the subacute phase (from 72 h to 7–10 days) and chronic stage (from 10–14 days to one month after the insult). As such, in recent years scientific efforts have focused on mitochondria as a target for cardioprotective strategies in ischemic heart disease and cardiomyopathy. The present review discusses recent advances in this field, with special emphasis on the emerging role of the biologically active thyroid hormone triiodothyronine (T3).

Antioxidant strategies in the management of diabetic neuropathy

Chronic hyperglycaemia (an abnormally high glucose concentration in the blood) resulting from defects in insulin secretion/action, or both, is the major hallmark of diabetes in which it is known to be involved in the progression of the condition to different complications that include diabetic neuropathy. Diabetic neuropathy (diabetes-induced nerve damage) is the most common diabetic complication and can be devastating because it can lead to disability. There is an increasing body of evidence associating diabetic neuropathy with oxidative stress. Oxidative stress results from the production of oxygen free radicals in the body in excess of its ability to eliminate them by antioxidant activity. Antioxidants have different mechanisms and sites of actions by which they exert their biochemical effects and ameliorate nerve dysfunction in diabetes by acting directly against oxidative damage. This review will examine different strategies for managing diabetic neuropathy which rely on exogenous antioxidants.

Cardiac NO signalling in the metabolic syndrome

It is well documented that metabolic syndrome (i.e. a group of risk factors, such as abdominal obesity, elevated blood pressure, elevated fasting plasma glucose, high serum triglycerides and low cholesterol level in high-density lipoprotein), which raises the risk for heart disease and diabetes, is associated with increased reactive oxygen and nitrogen species (ROS/RNS) generation. ROS/RNS can modulate cardiac NO signalling and trigger various adaptive changes in NOS and antioxidant enzyme expressions/activities. While initially these changes may represent protective mechanisms in metabolic syndrome, later with more prolonged oxidative, nitrosative and nitrative stress, these are often exhausted, eventually favouring myocardial RNS generation and decreased NO bioavailability. The increased oxidative and nitrative stress also impairs the NO-soluble guanylate cyclase (sGC) signalling pathway, limiting the ability of NO to exert its fundamental signalling roles in the heart. Enhanced ROS/RNS generation in the presence of risk factors also facilitates activation of redox-dependent transcriptional factors such as NF-κB, promoting myocardial expression of various pro-inflammatory mediators, and eventually the development of cardiac dysfunction and remodelling. While the dysregulation of NO signalling may interfere with the therapeutic efficacy of conventional drugs used in the management of metabolic syndrome, the modulation of NO signalling may also be responsible for the therapeutic benefits of already proven or recently developed treatment approaches, such as ACE inhibitors, certain β-blockers, and sGC activators. Better understanding of the above-mentioned pathological processes may ultimately lead to more successful therapeutic approaches to overcome metabolic syndrome and its pathological consequences in cardiac NO signalling.

Oxidative DNA damage and mortality in hemodialysis and peritoneal dialysis patients

BACKGROUND AND AIMS

Increased oxidative stress in dialysis patients is thought to contribute to increased mortality; however, confirmatory data are scarce. We analyzed the serum concentration of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker of oxidative stress, in relation to mortality in hemodialysis (HD) and peritoneal dialysis (PD) patients.

METHODS

Serum 8-OHdG, interleukin 6 (IL-6), other biochemical markers, Davies comorbidity score, and protein-energy wasting (PEW) were assessed in 303 prevalent patients treated with HD (n = 220; age: 63 ± 14 years) or PD (n = 83; age: 64 ± 14 years). Mortality was assessed after a median follow-up of 31 months.

RESULTS

The median (25th - 75th percentile) concentration of 8-OHdG was higher in HD than in PD patients: 1.3 ng/mL (0.9 - 1.8 ng/mL) versus 0.5 ng/mL (0.4 - 0.6 ng/mL), p < 0.001. The HD modality (standard β = 0.57, p < 0.001) and dialysis vintage (standard β = 0.12, p = 0.02) were independent predictors of serum 8-OHdG in a multivariable linear regression model including age, sex, body mass index, dialysis modality (HD or PD), preceding time on dialysis (dialysis vintage), PEW, comorbidity score, IL-6, and use of angiotensin converting-enzyme inhibitors or angiotensin II receptor blockers or statins. During follow-up, 107 patients died. In multivariable Cox regression models including all 303 patients and adjusted for age, sex, body mass index, dialysis modality, dialysis vintage, and comorbidity score, 8-OHdG was significantly associated with all-cause mortality (adjusted hazard ratio: 1.40; 95% confidence limits: 1.05, 1.87 for 1 standard deviation increase of 8-OHdG). In subgroup analyses according to dialysis modality, 8-OHdG was associated with mortality in HD patients but not in PD patients.

CONCLUSIONS

Oxidative stress as assessed by 8-OHdG is an independent predictor of all-cause mortality in dialysis patients. This association was seen in HD patients, but no such association could be demonstrated for PD patients.

Antioxidants and coronary artery disease: from pathophysiology to preventive therapy

Oxidant stress in the cardiovascular system may occur when antioxidant capacity is insufficient to reduce reactive oxygen species and other free radicals. Oxidant stress has been linked to the pathogenesis of atherosclerosis and incident coronary artery disease. As a result of this connection, early observational studies focused on dietary antioxidants, such as β-carotene, α-tocopherol, and ascorbic acid, and demonstrated an inverse relationship between intake of these antioxidants and major adverse cardiovascular events. These findings supported a number of randomized trials on the use of selected antioxidants as primary or secondary prevention strategies to decrease cardiac risk; however, many of these studies reported disappointing results with little or no observed risk reduction in antioxidant-treated patients. Several plausible explanations for these findings have been suggested, including incorrect antioxidant choice or dose, synthetic versus dietary antioxidants as the intervention, and patient selection, all of which will be important to consider when designing future clinical trials. This review will focus on the contemporary evidence that is the basis for our current understanding of the role of antioxidants in cardiovascular disease prevention.

Blockage of ROS and NF-κB-mediated inflammation by a new chalcone L6H9 protects cardiomyocytes from hyperglycemia-induced injuries

Increased oxidative stress and cardiac inflammation have been implicated in the pathogenesis of diabetic cardiomyopathy (DCM). We previously found that a novel chalcone derivative, L6H9, was able to reduce LPS-induced inflammatory response in macrophages. This study was designed to investigate its protective effects on DCM and the underlying mechanisms. H9C2 cells were cultured with DMEM containing 33 mmol/L of glucose in the presence or absence of L6H9. Pretreatment with L6H9 significantly reduced high glucose-induced inflammatory cytokine expression, ROS level increase, mitochondrial dysfunction, cell apoptosis, fibrosis, and hypertrophy in H9c2 cells, which may be mediated by NF-κB inhibition and Nrf2 activation. In mice with STZ-induced diabetes, oral administration of L6H9 at 20 mg/kg/day for 8 weeks significantly decreased the cardiac cytokine and ROS level, accompanied by decreasing cardiac apoptosis and hypertrophy, and, finally, improved histological abnormalities and fibrosis, without affecting the hyperglycemia. L6H9 also attenuated the diabetes-induced NF-κB activation and Nrf2 decrease in diabetic hearts. These results strongly suggest that L6H9 may have great therapeutic potential in the treatment of DCM via blockage of inflammation and oxidative stress. This study also provides a deeper understanding of the regulatory role of Nrf2 and NF-κB in DCM, indicating that they may be important therapeutic targets for diabetic complications.

Increased mortality after a first myocardial infarction in human immunodeficiency virus-infected patients; a nested cohort study

AIMS

HIV infection may be associated with an increased recurrence rate of myocardial infarction. Our aim was to determine whether HIV infection is a risk factor for worse outcomes in patients with coronaray artery disease.

METHODS

We compared data aggregated from two ongoing cohorts: (i) the Acute Myocardial Infarction in Switzerland (AMIS) registry, which includes patients with acute myocardial infarction (AMI), and (ii) the Swiss HIV Cohort Study (SHCS), a prospective registry of HIV-positive (HIV+) patients. We included all patients who survived an incident AMI occurring on or after 1st January 2005. Our primary outcome measure was all-cause mortality at one year; secondary outcomes included AMI recurrence and cardiovascular-related hospitalisations. Comparisons used Cox and logistic regression analyses, respectively.

RESULTS

There were 133 HIV+, (SHCS) and 5,328 HIV-negative [HIV-] (AMIS) individuals with incident AMI. In the SHCS and AMIS registries, patients were predominantly male (72% and 85% male, respectively), with a median age of 51 years (interquartile range [IQR] 46-57) and 64 years (IQR 55-74), respectively. Nearly all (90%) of HIV+ individuals were on successful antiretroviral therapy. During the first year of follow-up, 5 (3.6%) HIV+ and 135 (2.5%) HIV- individuals died. At one year, HIV+ status after adjustment for age, sex, calendar year of AMI, smoking status, hypertension and diabetes was associated with a higher risk of death (HR 4.42, 95% CI 1.73-11.27). There were no significant differences in recurrent AMIs (4 [3.0%] HIV+ and 146 [3.0%] HIV- individuals, OR 1.16, 95% CI 0.41-3.27) or in hospitalization rates (OR 0.68 [95% CI 0.42-1.11]).

CONCLUSIONS

HIV infection was associated with a significantly increased risk of all-cause mortality one year after incident AMI.

Pharmacogenomic interaction between the Haptoglobin genotype and vitamin E on atherosclerotic plaque progression and stability

OBJECTIVE

Homozygosity for a 1.7 kb intragenic duplication of the Haptoglobin (Hp) gene (Hp 2-2 genotype), present in 36% of the population, has been associated with a 2-3 fold increased incidence of atherothrombosis in individuals with Diabetes (DM) in 10 longitudinal studies compared to DM individuals not homozygous for this duplication (Hp 1-1/2-1). The increased CVD risk associated with the Hp 2-2 genotype has been shown to be prevented with vitamin E supplementation in man. We sought to determine if there was an interaction between the Hp genotype and vitamin E on atherosclerotic plaque growth and stability in a transgenic model of the Hp polymorphism.

METHODS AND RESULTS

Brachiocephalic artery atherosclerotic plaque volume was serially assessed by high resolution ultrasound in 28 Hp 1-1 and 26 Hp 2-2 mice in a C57Bl/6 ApoE(-/-) background. Hp 2-2 mice had more rapid plaque growth and an increased incidence of plaque hemorrhage and rupture. Vitamin E significantly reduced plaque growth in Hp 2-2 but not in Hp 1-1 mice with a significant pharmacogenomic interaction between the Hp genotype and vitamin E on plaque growth.

CONCLUSIONS

These results may help explain why vitamin E supplementation in man can prevent CVD in Hp 2-2 DM but not in non Hp 2-2 DM individuals.

Multivitamin use and cardiovascular disease in a prospective study of women

BACKGROUND

Although multivitamins are widely used, there are limited prospective studies investigating their association with both long- and short-term risk of cardiovascular disease (CVD).

OBJECTIVE

The objective was to investigate how multivitamin use is associated with the long- and short-term risk of CVD.

DESIGN

A prospective cohort study was conducted of 37,193 women from the Women's Health Study aged ≥45 y and free of CVD and cancer at baseline who were followed for an average of 16.2 y. At baseline, women self-reported a wide range of lifestyle, clinical, and dietary factors. Women were categorized into 1) no current use and 2) current use of multivitamins. Duration and updated measures over the course of the follow-up to address short-term effects were also considered. Women were followed for major CVD events, including myocardial infarction (MI), stroke, and CVD death.

RESULTS

During the follow-up, 1493 incident cases of CVD [defined as myocardial infarction (MI), stroke, and CVD death] occurred. In multivariable analyses, multivitamin use compared with no use was not associated with major CVD events (HR: 1.01; 95% CI: 0.89, 1.15), MI (HR: 1.04; 95% CI: 0.84, 1.27), stroke (HR: 0.99; 95% CI: 0.83, 1.18), or CVD death (HR: 1.10; 95% CI: 0.84, 1.45). A nonsignificant inverse association was observed between baseline multivitamin use and major CVD events among women aged ≥70 y (P-interaction = 0.04) and those consuming <3 servings/d of fruit and vegetables (P-interaction = 0.01). When updating information on multivitamin use during the course of follow-up, no associations were observed for major CVD events (HR: 0.91; 95% CI: 0.82, 1.02), MI (HR: 0.89; 95% CI: 0.74, 1.06), stroke (HR: 0.91; 95% CI: 0.78, 1.06), and CVD death (HR: 0.91; 95% CI: 0.71, 1.16).

CONCLUSIONS

In this study of middle-aged and elderly women, neither baseline nor time-varying multivitamin use was associated with the long-term risk of major CVD events, MI, stroke, cardiac revascularizations, or CVD death. Additional studies are needed to clarify the role of multivitamins on CVD.

Randomized controlled trials 1: Design

Today's clinical practice relies on the application of well-designed clinical research, the gold standard test of an intervention being the randomized controlled trial. Principles of the randomized control trial include emphasis on the principal research question, randomization, blinding; definitions of outcome measures, of inclusion and exclusion criteria, and of comorbid and confounding factors; enrolling an adequate sample size; planning data management and analysis; preventing challenges to trial integrity such as drop-out, drop-in, and bias. The application of pretrial planning is stressed to ensure the proper application of epidemiological principles resulting in clinical studies that are feasible and generalizable. In addition, funding strategies and trial team composition are discussed.

Targeted antioxidant treatment decreases cardiac alternans associated with chronic myocardial infarction

BACKGROUND

In myocardial infarction (MI), repolarization alternans is a potent arrhythmia substrate that has been linked to Ca2+ cycling proteins, such as sarcoplasmic reticulum Ca2+ ATPase (SERCA2a), located in the sarcoplasmic reticulum. MI is also associated with oxidative stress and increased xanthine oxidase (XO) activity, an important source of reactive oxygen species (ROS) in the sarcoplasmic reticulum that may reduce SERCA2a function. We hypothesize that in chronic MI, XO-mediated oxidation of SERCA2a is a mechanism of cardiac alternans.

METHODS AND RESULTS

Male Lewis rats underwent ligation of the left anterior descending coronary artery (n=54) or sham procedure (n=24). At 4 weeks, optical mapping of intracellular Ca2+ and ROS was performed. ECG T-wave alternans (ECG ALT) and Ca2+ transient alternans (Ca2+ALT) were induced by rapid pacing (300-120 ms) before and after the XO inhibitor allopurinol (ALLO, 50 µmol/L). In MI, ECG ALT (2.32±0.41%) and Ca2+ ALT (22.3±4.5%) were significantly greater compared with sham (0.18±0.08%, P<0.001; 0.79±0.32%, P<0.01). Additionally, ROS was increased by 137% (P<0.01) and oxidation of SERCA2a by 30% (P<0.05) in MI compared with sham. Treatment with ALLO significantly decreased ECG ALT (-77±9%, P<0.05) and Ca2+ ALT (-56±7%, P<0.05) and, importantly, reduced ROS (-65%, P<0.01) and oxidation of SERCA2a (-38%, P<0.05). CaMKII inhibition and general antioxidant treatment had no effect on ECG ALT and Ca2+ ALT.

CONCLUSIONS

These results demonstrate, for the first time, that in MI, increased ROS from XO is a significant cause of repolarization alternans. This suggests that targeting XO ROS production may be effective at preventing arrhythmia substrates in chronic MI.

Limiting reductive stress for treating in-stent stenosis: the heart of the matter?

Restenosis after balloon angioplasty and stenting (BAS) remains an unsolved clinical dilemma for patients with coronary artery disease. A better understanding of the mechanisms that drive this phenomenon is likely to lead to more effective treatments. In this issue of the JCI, Ali et al. uncover a critical redox axis with the antioxidant enzyme glutathione peroxidase-1 (GPX1) at its hub and identify potential new therapeutic targets, such as ROS1 tyrosine kinase. This study represents a potential new approach to finding a treatment for BAS, with implications that may extend beyond BAS to other vasculopathies involving vascular remodeling.

Oxido-reductive regulation of vascular remodeling by receptor tyrosine kinase ROS1

Angioplasty and stenting is the primary treatment for flow-limiting atherosclerosis; however, this strategy is limited by pathological vascular remodeling. Using a systems approach, we identified a role for the network hub gene glutathione peroxidase-1 (GPX1) in pathological remodeling following human blood vessel stenting. Constitutive deletion of Gpx1 in atherosclerotic mice recapitulated this phenotype of increased vascular smooth muscle cell (VSMC) proliferation and plaque formation. In an independent patient cohort, gene variant pair analysis identified an interaction of GPX1 with the orphan protooncogene receptor tyrosine kinase ROS1. A meta-analysis of the only genome-wide association studies of human neointima-induced in-stent stenosis confirmed the association of the ROS1 variant with pathological remodeling. Decreased GPX1 expression in atherosclerotic mice led to reductive stress via a time-dependent increase in glutathione, corresponding to phosphorylation of the ROS1 kinase activation site Y2274. Loss of GPX1 function was associated with both oxidative and reductive stress, the latter driving ROS1 activity via s-glutathiolation of critical residues of the ROS1 tyrosine phosphatase SHP-2. ROS1 inhibition with crizotinib and deglutathiolation of SHP-2 abolished GPX1-mediated increases in VSMC proliferation while leaving endothelialization intact. Our results indicate that GPX1-dependent alterations in oxido-reductive stress promote ROS1 activation and mediate vascular remodeling.

The progress of inflammation and oxidative stress in patients with chronic kidney disease

BACKGROUND

The variations and their correlation of inflammation and oxidative stress in chronic kidney disease (CKD) have not been thoroughly understood.

MATERIALS AND METHODS

Biomarkers of inflammation and oxidative stress were measured in a cohort of 176 patients with CKD ranging from stage 1 to 5 and 67 healthy controls. Correlation analysis in levels between inflammation and oxidative stress was also performed with estimated glomerular filtration rate (eGFR) using the Modification of Diet in Renal Disease (MDRD) formula. Concentrations of serum creatinine (Scr), hs-CRP (hypersensitive C reactive protein) and MDA (malondialdehyde) of these participants were measured again after 12 month follow-up.

RESULTS

In the present study, with the development of CKD, serum levels of hs-CRP, interleukin-6 (IL-6) and MDA were significantly increased, and the serum levels of SOD (superoxide dismutase) and GSH-PX (glutathione peroxidase) were significantly decreased in these participants. eGFR was inversely associated with MDA and positively with SOD and GSH-PX when adjusting for age and hypertension therapy. IL-6 and hs-CRP were positively correlated with MDA, and negatively associated with SOD and GSH-PX. Notably, after 12-month follow-up, the increase in Scr was positively associated with the increase in hs-CRP (p < 0.01) and MDA (p < 0.05), respectively.

CONCLUSIONS

Inflammation and oxidative stress interacted with each other and played pivotal roles in the development of CKD. Variation in eGFR was parallel with the changes of oxidative stress and inflammation when CKD developing.