Oxidative stress in cardiovascular disease: successful translation from bench to bedside?

Identification of Disease-relevant, Sex-based Proteomic Differences in iPSC-derived Vascular Smooth Muscle

The prevalence of cardiovascular disease varies with sex, and the impact of intrinsic sex-based differences on vasculature is not well understood. Animal models can provide important insight into some aspects of human biology, however not all discoveries in animal systems translate well to humans. To explore the impact of chromosomal sex on proteomic phenotypes, we used iPSC-derived vascular smooth muscle cells from healthy donors of both sexes to identify sex-based proteomic differences and their possible effects on cardiovascular pathophysiology. Our analysis confirmed that differentiated cells have a proteomic profile more similar to healthy primary aortic smooth muscle than iPSCs. We also identified sex-based differences in iPSC- derived vascular smooth muscle in pathways related to ATP binding, glycogen metabolic process, and cadherin binding as well as multiple proteins relevant to cardiovascular pathophysiology and disease. Additionally, we explored the role of autosomal and sex chromosomes in protein regulation, identifying that proteins on autosomal chromosomes also show sex-based regulation that may affect the protein expression of proteins from autosomal chromosomes. This work supports the biological relevance of iPSC-derived vascular smooth muscle cells as a model for disease, and further exploration of the pathways identified here can lead to the discovery of sex-specific pharmacological targets for cardiovascular disease.

Significance

In this work, we have differentiated 4 male and 4 female iPSC lines into vascular smooth muscle cells, giving us the ability to identify statistically-significant sex-specific proteomic markers that are relevant to cardiovascular disease risk (such as PCK2, MTOR, IGFBP2, PTGR2, and SULTE1).

Potential of natural products in the treatment of myocardial infarction: focus on molecular mechanisms

Although conventional drugs are widely used in the prevention and treatment of cardiovascular disease (CVD), they are being used less frequently due to concerns about possible side effects over the long term. There has been a renewed research interest in medicinal plant products, and their role in protecting the cardiovascular system and treating CVD, which are now being considered as potential alternatives to modern drugs. The most important mechanism causing damage to the myocardium after heart attack and reperfusion, is increased levels of free radicals and oxidative stress. Therefore, treatment approaches often focus on reducing free radicals or enhancing antioxidant defense mechanism. It has been previously reported that bioactive natural products can protect the heart muscle in myocardial infarction (MI). Since these compounds are readily available in fruits and vegetables, they could prevent the risk of MI if they are consumed daily. Although the benefits of a healthy diet are well known, many scientific studies have focused on whether pure natural compounds can prevent and treat MI. In this review we summarize the effects of curcumin, resveratrol, quercitin, berberine, and tanshinone on MI and CVD, and focus on their proposed molecular mechanisms of action.

The Kynurenine Pathway and Kynurenine 3-Monooxygenase Inhibitors

Under normal physiological conditions, the kynurenine pathway (KP) plays a critical role in generating cellular energy and catabolizing tryptophan. Under inflammatory conditions, however, there is an upregulation of the KP enzymes, particularly kynurenine 3-monooxygenase (KMO). KMO has garnered much attention due to its production of toxic metabolites that have been implicated in many diseases and disorders. With many of these illnesses having an inadequate or modest treatment, there exists a need to develop KMO inhibitors that reduce the production of these toxic metabolites. Though prior efforts to find an appropriate KMO inhibitor were unpromising, the development of a KMO crystal structure has provided the opportunity for a rational structure-based design in the development of inhibitors. Therefore, the purpose of this review is to describe the kynurenine pathway, the kynurenine 3-monooxygenase enzyme, and KMO inhibitors and their potential candidacy for clinical use.

Genome-wide differential expression profiling of lncRNAs and mRNAs in human induced pluripotent stem cell-derived endothelial cells exposed to e-cigarette extract

BACKGROUND

Electronic-cigarette (e-cig) usage, particularly in the youth population, is a growing concern. It is known that e-cig causes endothelial dysfunction, which is a risk factor for the development of cardiovascular diseases; however, the mechanisms involved remain unclear. We hypothesized that long noncoding RNAs (lncRNAs) may play a role in e-cig-induced endothelial dysfunction.

METHODS

Here, we identified lncRNAs that are dysregulated in human induced pluripotent stem cell-derived endothelial cells (iPSC-ECs) following 24 h of e-cig aerosol extract treatment via microarray analysis. We performed Gene Ontology and Kyoto Encyclopedia of Genes and Genome (KEGG) pathway analyses of the dysregulated mRNAs following e-cig exposure and constructed co-expression networks of the top 5 upregulated lncRNAs and the top 5 downregulated lncRNAs and the mRNAs that are correlated with them. Furthermore, the functional effects of knocking down lncRNA lung cancer-associated transcript 1 (LUCAT1) on EC phenotypes were determined as it was one of the significantly upregulated lncRNAs following e-cig exposure based on our profiling.

RESULTS

183 lncRNAs and 132 mRNAs were found to be upregulated, whereas 297 lncRNAs and 413 mRNAs were found to be downregulated after e-cig exposure. We also observed that e-cig caused dysregulation of endothelial metabolism resulting in increased FAO activity, higher mitochondrial membrane potential, and decreased glucose uptake and glycolysis. These results suggest that e-cig alters EC metabolism by increasing FAO to compensate for energy deficiency in ECs. Finally, the knockdown of LUCAT1 prevented e-cig-induced EC dysfunction by maintaining  vascular barrier, reducing reactive oxygen species level, and increasing migration capacity.

CONCLUSION

This study identifies an expression profile of differentially expressed lncRNAs and several potential regulators and pathways in ECs exposed to e-cig, which provide insights into the regulation of lncRNAs and mRNAs and the role of lncRNA and mRNA networks in ECs associated e-cig exposure.

Reductive Stress Causes Pathological Cardiac Remodeling and Diastolic Dysfunction

Aims: Redox homeostasis is tightly controlled and regulates key cellular signaling pathways. The cell's antioxidant response provides a natural defense against oxidative stress, but excessive antioxidant generation leads to reductive stress (RS). This study elucidated how chronic RS, caused by constitutive activation of nuclear erythroid related factor-2 (caNrf2)-dependent antioxidant system, drives pathological myocardial remodeling. Results: Upregulation of antioxidant transcripts and proteins in caNrf2-TG hearts (TGL and TGH; transgenic-low and -high) dose dependently increased glutathione (GSH) redox potential and resulted in RS, which over time caused pathological cardiac remodeling identified as hypertrophic cardiomyopathy (HCM) with abnormally increased ejection fraction and diastolic dysfunction in TGH mice at 6 months of age. While the TGH mice exhibited 60% mortality at 18 months of age, the rate of survival in TGL was comparable with nontransgenic (NTG) littermates. Moreover, TGH mice had severe cardiac remodeling at ∼6 months of age, while TGL mice did not develop comparable phenotypes until 15 months, suggesting that even moderate RS may lead to irreversible damages of the heart over time. Pharmacologically blocking GSH biosynthesis using BSO (l-buthionine-SR-sulfoximine) at an early age (∼1.5 months) prevented RS and rescued the TGH mice from pathological cardiac remodeling. Here we demonstrate that chronic RS causes pathological cardiomyopathy with diastolic dysfunction in mice due to sustained activation of antioxidant signaling. Innovation and Conclusion: Our findings demonstrate that chronic RS is intolerable and adequate to induce heart failure (HF). Antioxidant-based therapeutic approaches for human HF should consider a thorough evaluation of redox state before the treatment.

Modeling Cardiovascular Risks of E-Cigarettes With Human-Induced Pluripotent Stem Cell-Derived Endothelial Cells

BACKGROUND

Electronic cigarettes (e-cigarettes) have experienced a tremendous increase in use. Unlike cigarette smoking, the effects of e-cigarettes and their constituents on mediating vascular health remain understudied. However, given their increasing popularity, it is imperative to evaluate the health risks of e-cigarettes, including the effects of their ingredients, especially nicotine and flavorings.

OBJECTIVES

The purpose of this study was to investigate the effects of flavored e-cigarette liquids (e-liquids) and serum isolated from e-cigarette users on endothelial health and endothelial cell-dependent macrophage activation.

METHODS

Human-induced pluripotent stem cell-derived endothelial cells (iPSC-ECs) and a high-throughput screening approach were used to assess endothelial integrity following exposure to 6 different e-liquids with varying nicotine concentrations and to serum from e-cigarette users.

RESULTS

The cytotoxicity of the e-liquids varied considerably, with the cinnamon-flavored product being most potent and leading to significantly decreased cell viability, increased reactive oxygen species (ROS) levels, caspase 3/7 activity, and low-density lipoprotein uptake, activation of oxidative stress-related pathway, and impaired tube formation and migration, confirming endothelial dysfunction. Upon exposure of ECs to e-liquid, conditioned media induced macrophage polarization into a pro-inflammatory state, eliciting the production of interleukin-1β and -6, leading to increased ROS. After exposure of human iPSC-ECs to serum of e-cigarette users, increased ROS linked to endothelial dysfunction was observed, as indicated by impaired pro-angiogenic properties. There was also an observed increase in inflammatory cytokine expression in the serum of e-cigarette users.

CONCLUSIONS

Acute exposure to flavored e-liquids or e-cigarette use exacerbates endothelial dysfunction, which often precedes cardiovascular diseases.

Short time exposure to ambient ozone and associated cardiovascular effects: A panel study of healthy young adults

The evidence that exposure to ambient ozone (O₃) causes acute cardiovascular effects appears inconsistent. A repeated-measure study with 61 healthy young volunteers was conducted in Xinxiang, Central China. Real-time concentrations of O₃ were monitored. Cardiovascular outcomes including blood pressure (BP), heart rate (HR), serum levels of high sensitivity C-reactive protein (hs-CRP), 8-hydroxy-2'-deoxyguanosine (8-OHdG), tissue-type plasminogen activator (t-PA), and platelet-monocyte aggregation (PMA) were repeated measured. Linear mixed-effect models were used to analyze the association of ambient O₃ with these cardiovascular outcomes. Additionally, the modifying effects of glutathione S-transferase mu 1 (GSTM1) and glutathione S-transferase theta 1 (GSTT1) polymorphisms were estimated to explore the potential mechanisms and role of the association between O₃ exposure and the above cardiovascular outcomes. A 10 μg/m³ increase in O₃ was associated with increases of 9.2 mmHg (95% confidence interval [CI]: 2.5, 15.9), 7.2 mmHg (95% CI: 0.8, 13.6), and 21.2 bpm (95% CI: 5.8, 36.6) in diastolic BP (DBP, lag1), mean arterial BP (MABP, lag1), and HR (lag01), respectively. Meanwhile, the serum concentrations of hs-CRP, 8-OHdG, and t-PA were all increased by O₃ exposure, but the PMA level was decreased. Stratification analyses showed that the estimated effects of O₃ on DBP, MABP, and HR in GSTM1-sufficient subjects were significantly higher than in GSTM1-null subjects. Moreover, GSTM1-null genotype enhanced O₃-induced increases, albeit insignificant, in levels of serum hs-CRP, 8-OHdG, and t-PA compared with GSTM1-sufficient genotype. Insignificant increases in hs-CRP and t-PA were also detected in GSTT1-null subjects. Taken together, our findings indicate that acute exposure to ambient O₃ induces autonomic alterations, systemic inflammation, oxidative stress, and fibrinolysis in healthy young subjects. GSTM1 genotype presents the trend of modifying O₃-induced cardiovascular effects.

Ozone effects on blood biomarkers of systemic inflammation, oxidative stress, endothelial function, and thrombosis: The Multicenter Ozone Study in oldEr Subjects (MOSES)

The evidence that exposure to ozone air pollution causes acute cardiovascular effects is mixed. We postulated that exposure to ambient levels of ozone would increase blood markers of systemic inflammation, prothrombotic state, oxidative stress, and vascular dysfunction in healthy older subjects, and that absence of the glutathione S-transferase Mu 1 (GSTM1) gene would confer increased susceptibility. This double-blind, randomized, crossover study of 87 healthy volunteers 55-70 years of age was conducted at three sites using a common protocol. Subjects were exposed for 3 h in random order to 0 parts per billion (ppb) (filtered air), 70 ppb, and 120 ppb ozone, alternating 15 min of moderate exercise and rest. Blood was obtained the day before, approximately 4 h after, and approximately 22 h after each exposure. Linear mixed effect and logistic regression models evaluated the impact of exposure to ozone on pre-specified primary and secondary outcomes. The definition of statistical significance was p<0.01. There were no effects of ozone on the three primary markers of systemic inflammation and a prothrombotic state: C-reactive protein, monocyte-platelet conjugates, and microparticle-associated tissue factor activity. However, among the secondary endpoints, endothelin-1, a potent vasoconstrictor, increased from pre- to post-exposure with ozone concentration (120 vs 0 ppb: 0.07 pg/mL, 95% confidence interval [CI] 0.01, 0.14; 70 vs 0 ppb: -0.03 pg/mL, CI -0.09, 0.04; p = 0.008). Nitrotyrosine, a marker of oxidative and nitrosative stress, decreased with increasing ozone concentrations, with marginal significance (120 vs 0 ppb: -41.5, CI -70.1, -12.8; 70 vs 0 ppb: -14.2, CI -42.7, 14.2; p = 0.017). GSTM1 status did not modify the effect of ozone exposure on any of the outcomes. These findings from healthy older adults fail to identify any mechanistic basis for the epidemiologically described cardiovascular effects of exposure to ozone. The findings, however, may not be applicable to adults with cardiovascular disease.

Ethanolic extract and ethyl acetate fraction of Coutoubea spicata attenuate hyperglycemia, oxidative stress, and muscle damage in alloxan-induced diabetic rats subjected to resistance exercise training program

Gentianaceae family (such as Coutoubea spicata) contains iridoids and flavonoids with antidiabetic properties. However, there is no information available about the antidiabetic effects of C. spicata when combined with resistance exercise training (RET). This study evaluated the effects of the ethanolic extract (EE) and ethyl acetate fraction (EAF) of C. spicata on biochemical markers, muscle damage, and oxidative stress in diabetic rats submitted to RET. Alloxan-induced diabetic rats were distributed into 4 groups (each group, n = 8) treated with distilled water (TD), EE, EAF, or metformin and submitted to RET. Two groups without the disease (each group, n = 8) (sedentary control and trained control), as well as a sedentary diabetic group (n = 8) were included. Body weight and glycemia were evaluated weekly. After 30 days, lipid/lipoprotein profile, aspartate aminotransferase, alanine aminotransferase, muscle damage ((creatine kinase (CK) and lactate dehydrogenase (LDH)), and oxidative stress (malondialdehyde (MDA), sulfhydryl groups (SH), and ferric reducing antioxidant power) were evaluated. MDA and SH for pancreas, liver, heart, and muscle were evaluated. C. spicata extract and fraction combined with RET recovered body weight and reduced glycemia, muscle damage (CK: 36.83% and 21.45%; LDH: 49.83% and 68.55%), and low-density lipoprotein cholesterol (70.63%; 59.18%) and improved redox status (MDA: 50.33%, 39.74%; and SH: 53.97%; 76.41%), respectively, when compared with the TD group. C. spicata plus RET promoted anti-hyperglycemic, lipid-reducing, and antioxidant effects in diabetic rats. Novelty C. spicata presents anti-hyperglycemic and lipid-lowering effects potentiated by RET. C. spicata reduces muscle injury and increases antioxidant defense.

The toxicological analysis of secondary organic aerosol in human lung epithelial cells and macrophages

Secondary organic aerosol (SOA) is a component of airborne particulate matter in urban areas. However, their toxicities remain incompletely understood. In this study, we investigated the oxidative and inflammatory potency of SOA derived from three different volatile organic compounds (α-pinene, m-xylene, and trimethylbenzene) using human bronchial epithelial cells (BEAS-2B) and macrophages (U937). In BEAS-2B cells, all types of SOA extracts increased the expression of the heme oxygenase 1 (HMOX1) and interleukin-8 (IL8) genes, a typical marker for oxidative stress and inflammatory responses, respectively. Among the three types of SOA, m-xylene-derived SOA showed the strongest induction of the HMOX1 and IL8 genes, and transcriptional activity via the antioxidant response element (ARE). A causal candidate for SOA induction of oxidative stress is 2,6-dimethyl-1,4-benzoquinone (DMBQ) because only this quinone compound increased the transcriptional activity via ARE among components tested in this study. Similar to the case of BEAS-2B cells, SOA extracts increased the expression of HMOX1 and IL8 genes in U937 cells, mainly through oxidative stress, but these responses in U937 cells were prolonged when compared with BEAS-2B cells. Together, these results show that SOA affects lung epithelial cells and macrophages mainly through oxidative stress and inflammation, suggesting their contribution to the development of respiratory diseases.

Oxidative Balance and Inflammation in Hemodialysis Patients: Biomarkers of Cardiovascular Risk?

During chronic kidney disease, the progressive deterioration of renal function induces several biological/clinical dysfunctions, including enhancement of synthesis of inflammation/oxidative stress mediators. Impaired renal function is an independent cardiovascular risk factor; indeed, cardiovascular complications dominate the landscape of both chronic kidney disease and end-stage renal disease. The aim of this study is to explore the correlation between the global oxidative balance in hemodialysis patients and both inflammatory markers and cardiovascular events. Using photometric tests, this study explored plasmatic oxidative balance in 97 hemodialysis patients compared to a healthy population. In the hemodialysis patients, we showed that oxidative stress values were significantly lower than in controls while effectiveness in the antioxidant barrier was significantly increased in the hemodialysis group. Furthermore, we highlighted a strong correlation between oxidative index and blood levels of C-reactive protein. When patients were divided into two groups based on previous cardiovascular events, we found that subjects with previous cardiovascular events had higher values of both oxidative stress and antioxidant barrier than patients without cardiovascular events. Our results indicated that in hemodialysis patients, the clinical and prognostic significance of oxidative status is very different from general population. As cardiovascular complications represent a strong negative factor for survival of hemodialysis patients, the research of new cardiovascular risk biomarkers in these patients takes on particular importance in order to translate them into clinical practice/primary care.

Reprint of: Proteomics in cardiovascular diseases: Unveiling sex and gender differences in the era of precision medicine

Cardiovascular diseases (CVDs) represent the most important cause of mortality in women and in men. Contrary to the long-standing notion that the effects of the major risk factors on CVD outcomes are the same in both sexes, recent evidence recognizes new, potentially independent, sex/gender-related risk factors for CVDs, and sex/gender-differences in the clinical presentation of CVDs have been demonstrated. Furthermore, some therapeutic options may not be equally effective and safe in men and women. In this context, proteomics offers an extremely useful and versatile analytical platform for biomedical researches that expand from the screening of early diagnostic and prognostic biomarkers to the investigation of the molecular mechanisms underlying CDVs. In this review, we summarized the current applications of proteomics in the cardiovascular field, with emphasis on sex and gender-related differences in CVDs.

SIGNIFICANCE

Increasing evidence supports the profound effect of sex and gender on cardiovascular physio-pathology and the response to drugs. A clear understanding of the mechanisms underlying sexual dimorphisms in CVDs would not only improve our knowledge of the etiology of these diseases, but could also inform health policy makers and guideline committees in tailoring specific interventions for the prevention, treatment and management of CVDs in both men and women.

Engineering Bioinspired Antioxidant Materials Promoting Cardiomyocyte Functionality and Maturation for Tissue Engineering Application

Oxidative stress plays an important role in various pathological conditions, such as wound healing, inflammation, myocardial infarction, and biocompatibility of the materials. Antioxidant polymers to attenuate oxidative stress is an emerging field of biomaterial research with a huge impact in the field of tissue engineering and regenerative medicine. We describe here the fabrication and evaluation of an elastomeric antioxidant polyurethane (PUAO) for tissue engineering applications. Uniaxial and cyclic tensile testing, thermal analysis, degradation, cytotoxicity and antioxidant analysis was carried out. An in vitro oxidative stress model demonstrated that PUAO reduced intracellular oxidative stress in H9C2 cardiomyocytes (p < 0.05) and attenuated reactive oxygen species (ROS) induced cell death (p < 0.001). Under simulated ischemic reperfusion, PUAO could rescue hypoxia induced cell death. Further as a proof of concept, neonatal rat cardiomyocytes cultured on PUAO film displayed synchronous beating with mature phenotype showing expression of cardiac specific α-actinin, troponin-T, and connexin-43 proteins. Intracellular calcium transients established the functionality of cultured cardiomyocytes on PUAO film. Our study demonstrated the potential of this biomaterial to be developed into tissue engineered scaffold to attenuate oxidative stress for treatment of diseased conditions with increased oxidative stress, such as cardiovascular diseases, chronic wound healing, and myocardial infarction.

Impaired Oxidative Status Is Strongly Associated with Cardiovascular Risk Factors

The main target of primary prevention is the identification of cardiovascular risk factors aimed at reducing of the adverse impact of modifiable factors, such as lifestyle and pharmacological treatments. In humans, an alteration of the oxidative status has been associated with several pathologies, including diabetes and cardiovascular diseases. However, the prognostic relevance of circulating oxidative stress biomarkers remains poorly understood. Our study explored, in a healthy population (n = 322), the relationship between oxidative status and cardiovascular risk factors. Here, we were successful in demonstrating that plasmatic oxidative status is significantly associated with traditional cardiovascular risk factors. We revealed a significant depletion in the efficacy of total plasma antioxidant barrier in high cardiovascular risk categories, and we confirmed an age-related alteration of oxidative status. The efficacy of total plasma antioxidant barrier is significantly depleted in relation to metabolic disorders. Interestingly, the cholesterol imbalance is the main factor in depleting the efficacy of total plasma antioxidant barrier. The oxidative status is also influenced by hypertension, and a slight increase in systolic blood pressure determines a highly significant effect. We showed that the first detectable event of a redox disturbance is the repairing intervention of the antioxidant barrier that is thus decreased as overutilized.

Proteomics in cardiovascular diseases: Unveiling sex and gender differences in the era of precision medicine

Cardiovascular diseases (CVDs) represent the most important cause of mortality in women and in men. Contrary to the long-standing notion that the effects of the major risk factors on CVD outcomes are the same in both sexes, recent evidence recognizes new, potentially independent, sex/gender-related risk factors for CVDs, and sex/gender-differences in the clinical presentation of CVDs have been demonstrated. Furthermore, some therapeutic options may not be equally effective and safe in men and women. In this context, proteomics offers an extremely useful and versatile analytical platform for biomedical researches that expand from the screening of early diagnostic and prognostic biomarkers to the investigation of the molecular mechanisms underlying CDVs. In this review, we summarized the current applications of proteomics in the cardiovascular field, with emphasis on sex and gender-related differences in CVDs.

SIGNIFICANCE

Increasing evidence supports the profound effect of sex and gender on cardiovascular physio-pathology and the response to drugs. A clear understanding of the mechanisms underlying sexual dimorphisms in CVDs would not only improve our knowledge of the etiology of these diseases, but could also inform health policy makers and guideline committees in tailoring specific interventions for the prevention, treatment and management of CVDs in both men and women.

Constitutive activation of Nrf2 induces a stable reductive state in the mouse myocardium

Redox homeostasis regulates key cellular signaling pathways in both physiology and pathology. The cell's antioxidant response provides a defense against oxidative stress and establishes a redox tone permissive for cell signaling. The molecular regulation of the well-known Keap1/Nrf2 system acts as sensor responding to changes in redox homeostasis and is poorly studied in the heart. Importantly, it is not yet known whether Nrf2 alone can serve as a master regulator of cellular redox homeostasis without compensation of the transcriptional regulation of antioxidant response element (ARE) genes through alternate mechanisms. Here, we addressed this question using cardiac-specific transgenic expression at two different levels of constitutively active nuclear erythroid related factor 2 (caNrf2) functioning independently of Keap1. The caNrf2 mice showed augmentation of glutathione (GSH), the key regulator of the cellular thiol redox state. The Trans-AM assay for Nrf2-binding to the antioxidant response element (ARE) showed a dose-dependent increase associated with upregulation of several major antioxidant genes and proteins. This was accompanied by a significant decrease in dihydroethidium staining and malondialdehyde (MDA) in the caNrf2-TG mice myocardium. Interestingly, caNrf2 gene-dosage dependent redox changes were noted resulting in generation of a multi-stage model of pro-reductive and reductive conditions in the myocardium of TG-low and TG-high mice, respectively. These data clearly show that Nrf2 levels alone are capable of serving as the master regulator of the ARE. These models provide an important platform to investigate the impact of the Nrf2 system independent of the need to regulate the activity of Keap1 and the consequent exposure to pro-oxidants or electrophiles, which have numerous off-target effects.

Gut Microbiota in Cardiovascular Health and Disease

Significant interest in recent years has focused on gut microbiota-host interaction because accumulating evidence has revealed that intestinal microbiota play an important role in human health and disease, including cardiovascular diseases. Changes in the composition of gut microbiota associated with disease, referred to as dysbiosis, have been linked to pathologies such as atherosclerosis, hypertension, heart failure, chronic kidney disease, obesity, and type 2 diabetes mellitus. In addition to alterations in gut microbiota composition, the metabolic potential of gut microbiota has been identified as a contributing factor in the development of diseases. Recent studies revealed that gut microbiota can elicit a variety of effects on the host. Indeed, the gut microbiome functions like an endocrine organ, generating bioactive metabolites, that can impact host physiology. Microbiota interact with the host through many pathways, including the trimethylamine/trimethylamine N-oxide pathway, short-chain fatty acids pathway, and primary and secondary bile acids pathways. In addition to these metabolism-dependent pathways, metabolism-independent processes are suggested to also potentially contribute to cardiovascular disease pathogenesis. For example, heart failure-associated splanchnic circulation congestion, bowel wall edema, and impaired intestinal barrier function are thought to result in bacterial translocation, the presence of bacterial products in the systemic circulation and heightened inflammatory state. These are thought to also contribute to further progression of heart failure and atherosclerosis. The purpose of the current review is to highlight the complex interplay between microbiota, their metabolites, and the development and progression of cardiovascular diseases. We will also discuss the roles of gut microbiota in normal physiology and the potential of modulating intestinal microbial inhabitants as novel therapeutic targets.

A systematic review of the protective role of swertiamarin in cardiac and metabolic diseases

BACKGROUND

Swertiamarin, is a secoiridoid glycoside found in genera of Enicostemma Species (Enicostemma littorale and Enicostemma axillare) belonging to the family of gentianaceae, which has been reported to cure many diseases such as diabetes, hypertension, atherosclerosis, arthritis, malaria and abdominal ulcers. However, to the best of our knowledge, till date systematic studies to understand the molecular basis of cardiac and metabolic disease preventing properties of swertiamarin has not been reported.

AIM OF THE REVIEW

The present review aims to compile an up-to-date information on the progress made in the protective role of swertiamarin in cardiac and metabolic diseases with the objective of providing a guide for future research on this bioactive molecule.

MATERIALS AND METHODS

Information on the swertiamarin was collected from major scientific databases (Pubmed, Springer, google scholar, and Web of Science) for publication between1974-2016. In this review, the protective role of swertiamarin on cardiac and metabolic diseases was discussed.

RESULTS

Swertiamarin reported to exhibit a wide range of biological activities such as anti-atherosclerotic, antidiabetic, anti-inflammatory and antioxidant effects. These activities were mainly due to its effect on various signaling pathways associated with cardiac remodeling events such as inhibition of NF-kB expression, LDL oxidation, apoptosis, inflammatory and lipid peroxidation markers and stimulation of antioxidant enzymes.

CONCLUSION

Sweriamarin exhibit a wide range of biological activities. This review presents evidence supporting the point of view that swertiamarin should be considered a potential therapeutic agent against cardiac and metabolic diseases, giving rise to novel applications in their prevention and treatment.

P66Shc-SIRT1 Regulation of Oxidative Stress Protects Against Cardio-cerebral Vascular Disease

Growing evidence shows that acute and chronic overproduction of reactive oxygen species (ROS) and increased oxidants under pathophysiologic circumstances are of vital importance in the development of cardio-cerebral vascular diseases (CCVDs). It has been revealed that the impact of ROS can be suppressed by sirtuin 1 (SIRT1), a member of the highly conserved nicotinamide adenine dinucleotide-dependent class III histone deacetylases through protecting endothelial cells from oxidative injury. Plenty of evidences indicate that p66Shc stimulates mitochondrial ROS generation through its oxidoreductase activity and plays a vital role in the pathophysiology of CCVDs. The link between SIRT and p66Shc, though not very clear yet, may be generally illustrated like this: SIRT1 negatively regulates the expression of p66Shc in transcriptional level. In this review, the authors aimed to discuss the link between the pathogenesis of CCVDs, the regulation of ROS, the interrelation between SIRT1 and p66Shc, and the protective effect of the proper regulation of p66Shc/SIRT1 on CCVDs. The imbalance between the elimination and production of ROS can lead to oxidative stress (OS). More and more evidence suggest that ROS pathological overproduction is closely connected to the genesis and growth of CCVDs. P66shc is a gene that controls ROS level, apoptosis induction, and lifespan. Lots of evidence also indicate a role for SIRT1 mediating OS responses through several ways including directly deacetylating some transcription factors that control anti-OS genes. SIRT1 downregulation can lead to a decreased deacetylation of p66shc gene promoter and can then result in p66shc transcription. SIRT1 binds to the promoter of p66Shc where it can deacetylate histone H3, which weakens the transcription and translation of p66shc.

Rice Germosprout Extract Protects Erythrocytes from Hemolysis and the Aorta, Brain, Heart, and Liver Tissues from Oxidative Stress In Vitro

Identifying dietary alternatives for artificial antioxidants capable of boosting antihemolytic and antioxidative defense has been an important endeavor in improving human health. In the present study, we studied antihemolytic and antioxidative effects of germosprout (i.e., the germ part along with sprouted stems plus roots) extract prepared from the pregerminated rice. The extract contained considerable amounts of antioxidant β-carotene (414 ± 12 ng/g of extract) and phytochemicals such as total polyphenols (12.0 ± 1.1 mg gallic acid equivalent/g of extract) and flavonoids (11.0 ± 1.4 mg catechin equivalent/g of extract). The antioxidant potential of the extract was assessed by its DPPH- (2,2-diphenyl-1-picrylhydrazyl-) free radical scavenging activity where we observed that germosprout extract had considerable antioxidative potentials. To evaluate antihemolytic effect of the extract, freshly prepared erythrocytes were incubated with either peroxynitrite or Fenton's reagent in the absence or presence of the extract. We observed that erythrocytes pretreated with the extract exhibited reduced degree of in vitro hemolysis. To support the proposition that germosprout extract could act as a good antioxidative agent, we also induced in vitro oxidative stress in erythrocyte membranes and in the aorta, brain, heart, and liver tissue homogenates in the presence of the extract. As expected, germosprout extract decreased oxidative stress almost to the same extent as that of vitamin E, as measured by lipid peroxide levels, in all the mentioned tissues. We conclude that rice germosprout extract could be a good natural source of antioxidants to reduce oxidative stress-induced hemolysis and damage of blood vessels and other tissues.

Telomere length, antioxidant status and incidence of ischaemic heart disease in type 2 diabetes

Background

Type 2 diabetes (T2D) is associated with an increased risk of ischaemic heart disease (IHD). An accelerated process of vascular ageing induced by an increased oxidative stress exposure is suggested as potential pathway accounting for this association. However, no studies have explored the relationship between markers of vascular ageing, measures of oxidative stress and risk of IHD in T2D.

Objectives

To explore the association between plasma antioxidant status, marker of cellular ageing (leukocyte telomere length, LTL) and 10 years risk of IHD in patients with T2D.

Methods

Between 2001 and 2002, 489 Caucasians subjects with T2D were enrolled at the diabetic clinic, University College London Hospital. Plasma total anti-oxidant status (TAOS) and LTL were measured by photometric microassay and RT-PCR, respectively. The incidence of IHD over 10 years was determined through linkage with the national clinical audit of acute coronary syndrome in UK.

Results

At baseline, TAOS was associated with LTL (age adjusted: r = 0.106, p = 0.024). After 10 years, 61 patients developed IHD. Lower TAOS and shorter LTL at baseline predicted an increased IHD risk at follow-up (age adjusted: p = 0.033 and p = 0.040, respectively). These associations were independent of age, gender, cardiovascular risk factors, circulating levels of CRP and medication differences.

Conclusions

Reduced TAOS and short LTL are interrelated pathways which predict risk of IHD in patients with T2D. Our findings suggest that antioxidant defences are important to maintain telomere integrity, potentially reducing the progression of vascular ageing in patients with T2D.

Oxidative Stress in Obese Postmenopausal Women: An Additive Burden for Atherosclerosis

INTRODUCTION

Coronary Artery Disease are on the rise in the general population and is the leading cause of death in both men and women. The impact of CAD is underappreciated in younger women when compared to men. Women have unique risk factors for CAD and postmenopausal women are at higher risk of developing CAD when compared to normal menstruating women.

AIM

The aim of our study was to find out the difference in oxidative stress levels between obese postmenopausal women and normal menstruating women, also to compare the same in normal weight postmenopausal women.

MATERIALS AND METHODS

Thirty one normal and 29 obese postmenopausal women with age more than 45 years who visited obstetrics and gynaecology outpatient department for general clinical evaluation at a tertiary care centre were recruited in this cross-sectional study. Thirty normal menstruating women were compared. Anthropometric measurements were recorded and the body mass index was calculated. Serum Malondialdehyde and superoxide dismutase was measured using a spectrophotometer.

RESULTS

There was a significant difference in mean MDA levels in postmenopausal women (1.477 ± 0.359) when compared to normal menstruating women (0.666 ± 0.302) (p < 0.01). There was no significant difference in mean SOD levels in postmenopausal women (2.836 ± 0.899) when compared to normal menstruating women (2.986 ± 0.686) (p > 0.05). Also, there was a significant increase between mean MDA levels in obese postmenopausal women (2.48 ± 0.52) when compared to normal weight postmenopausal women (1.65 ± 0.36) (p < 0.01). There was a significant difference between mean SOD levels in obese postmenopausal women (1.36 ± 0.96) and normal weight postmenopausal women (2.56 ± 1.03) (p < 0.01).

CONCLUSION

The oxidative stress was higher in obese postmenopausal women when compared to normal weight postmenopausal women and normal menstruating women.

Genetic variants and cellular stressors associated with exfoliation syndrome modulate promoter activity of a lncRNA within the LOXL1 locus

Exfoliation syndrome (XFS) is a common, age-related, systemic fibrillinopathy. It greatly increases risk of exfoliation glaucoma (XFG), a major worldwide cause of irreversible blindness. Coding variants in the lysyl oxidase-like 1 (LOXL1) gene are strongly associated with XFS in all studied populations, but a functional role for these variants has not been established. To identify additional candidate functional variants, we sequenced the entire LOXL1 genomic locus (∼40 kb) in 50 indigenous, black South African XFS cases and 50 matched controls. The variants with the strongest evidence of association were located in a well-defined 7-kb region bounded by the 3'-end of exon 1 and the adjacent region of intron 1 of LOXL1. We replicated this finding in US Caucasian (91 cases/1031 controls), German (771 cases/1365 controls) and Japanese (1484 cases/1188 controls) populations. The region of peak association lies upstream of LOXL1-AS1, a long non-coding RNA (lncRNA) encoded on the opposite strand of LOXL1. We show that this region contains a promoter and, importantly, that the strongly associated XFS risk alleles in the South African population are functional variants that significantly modulate the activity of this promoter. LOXL1-AS1 expression is also significantly altered in response to oxidative stress in human lens epithelial cells and in response to cyclic mechanical stress in human Schlemm's canal endothelial cells. Taken together, these findings support a functional role for the LOXL1-AS1 lncRNA in cellular stress response and suggest that dysregulation of its expression by genetic risk variants plays a key role in XFS pathogenesis.

Cardiovascular and psychiatric characteristics associated with oxidative stress markers among adolescents with bipolar disorder

INTRODUCTION

In the field of bipolar disorder (BD) research there is an absence of validated biomarkers and limited understanding of the biology underlying excessive and premature cardiovascular disease (CVD). Oxidative stress is a potential biomarker in both BD and CVD.

OBJECTIVE

To examine psychiatric and cardiovascular characteristics associated with peripheral oxidative stress markers among adolescents with BD, who are at high risk for CVD.

METHODS

Participants were 30 adolescents, 13-19years old, with BD and without CVD. Ultrasonography was used to evaluate vascular function and structure. Traditional CVD risk factors were also measured. Psychiatric assessments were conducted via semi-structured interview. Serum levels of oxidative stress (lipid hydroperoxides (LPH) and protein carbonylation (PC)) were assayed.

RESULTS

Compared to published data on adults with BD, adolescents had significantly lower levels of LPH and PC (t52(11.34), p<0.0001; t58(29.68), p<0.0001, respectively). Thicker mean and maximum carotid intima media thickness was associated with greater levels of LPH (r=.455, p=.015; r=.620, p<0.0001, respectively). LPH was associated with diastolic blood pressure (r=-.488, p=0.008) and pulse pressure (r=.543, p=0.003). Mood symptoms and medication were not significantly associated with oxidative stress.

CONCLUSION

Adolescents with BD have lower levels of oxidative stress compared to adults with BD, supporting prevailing illness staging theories for BD. Oxidative stress is robustly associated with a proxy measure of atherosclerosis and may explain in part the increased risk of CVD in BD.

Arjunolic acid ameliorates reactive oxygen species via inhibition of p47(phox)-serine phosphorylation and mitochondrial dysfunction

Impaired cardiovascular function during acute myocardial infarction (MI) is partly associated with recruitment of activated polymorphonuclear neutrophils. The protective role of arjunolic acid (AA; 2,3,23-trihydroxy olean-12-en-28-oic acid) is studied in the modulation of neutrophil functions in vitro by measuring the reactive oxygen species (ROS) generation. Neutrophils were isolated from normal and acute MI mice to find out the efficacy of AA in reducing oxidative stress. Stimulation of neutrophils with phorbol-12-myristate-13-acetate (PMA) resulted in an oxidative burst of superoxide anion (O2(-)) and enhanced release of lysosomal enzymes. The treatment of neutrophils with PMA induced phosphorylation of Ser345 on p47(phox), a cytosolic component of NADPH oxidase. Furthermore, we observed activated ERK induced phosphorylation of Ser345 in MI neutrophils. Treatment with AA significantly inhibited the phosphorylation of P47(phox) and ERK in the stimulated controls and MI neutrophils. Oxidative phosphorylation activities in MI cells were lower than in control, while the glycolysis rates were elevated in MI cells compared to the control. In addition, we observed AA decreased intracellular oxidative stress and reduced the levels of O2(-) in neutrophils. This study therefore identifies targets for AA in activated neutrophils mediated by the MAPK pathway on p47(phox) involved in ROS generation.

Targeting oxidant-dependent mechanisms for the treatment of COPD and its comorbidities

Chronic obstructive pulmonary disease (COPD) is an incurable global health burden and is characterised by progressive airflow limitation and loss of lung function. In addition to the pulmonary impact of the disease, COPD patients often develop comorbid diseases such as cardiovascular disease, skeletal muscle wasting, lung cancer and osteoporosis. One key feature of COPD, yet often underappreciated, is the contribution of oxidative stress in the onset and development of the disease. Patients experience an increased burden of oxidative stress due to the combined effects of excess reactive oxygen species (ROS) and nitrogen species (RNS) generation, antioxidant depletion and reduced antioxidant enzyme activity. Currently, there is a lack of effective treatments for COPD, and an even greater lack of research regarding interventions that treat both COPD and its comorbidities. Due to the involvement of oxidative stress in the pathogenesis of COPD and many of its comorbidities, a unique therapeutic opportunity arises where the treatment of a multitude of diseases may be possible with only one therapeutic target. In this review, oxidative stress and the roles of ROS/RNS in the context of COPD and comorbid cardiovascular disease, skeletal muscle wasting, lung cancer, and osteoporosis are discussed and the potential for therapeutic benefit of anti-oxidative treatment in these conditions is outlined. Because of the unique interplay between oxidative stress and these diseases, oxidative stress represents a novel target for the treatment of COPD and its comorbidities.

Nitric Oxide Bioavailability in Obstructive Sleep Apnea: Interplay of Asymmetric Dimethylarginine and Free Radicals

Obstructive sleep apnea (OSA) occurs in 2% of middle-aged women and 4% of middle-aged men and is considered an independent risk factor for cerebrovascular and cardiovascular diseases. Nitric oxide (NO) is an important endothelium derived vasodilating substance that plays a critical role in maintaining vascular homeostasis. Low levels of NO are associated with impaired endothelial function. Asymmetric dimethylarginine (ADMA), an analogue of L-arginine, is a naturally occurring product of metabolism found in the human circulation. Elevated levels of ADMA inhibit NO synthesis while oxidative stress decreases its bioavailability, so impairing endothelial function and promoting atherosclerosis. Several clinical trials report increased oxidative stress and ADMA levels in patients with OSA. This review discusses the role of oxidative stress and increased ADMA levels in cardiovascular disease resulting from OSA.

Reduction of Store-Operated Ca(2+) Entry Correlates with Endothelial Progenitor Cell Dysfunction in Atherosclerotic Mice

The dysfunction of endothelial progenitor cells (EPCs) has been shown to prevent endothelial repair during the development of atherosclerosis (AS). Previous studies have revealed that store-operated calcium entry (SOCE) is an important factor in regulating EPC functions. However, whether this is also the mechanism in AS has not been elucidated. Therefore, we evaluated the role of SOCE in EPCs isolated from an atherosclerotic mouse model. Atheromatous plaques were more frequent in the aortas of ApoE(-/-) mice fed a high-fat diet for 16 weeks compared with controls, and the proliferative and migratory activities of atherosclerotic EPCs were significantly decreased. Accordingly, SOCE amplitude, as well as spontaneous or VEGF-induced Ca(2+) oscillations, decreased in atherosclerotic EPCs. These results may be associated with the downregulated expression of Stim1, Orai1, and TRPC1, which are major mediators of SOCE. In addition, eNOS expression and phosphorylation at Ser(1177), which are critical regulators of EPC function, were markedly reduced in the atherosclerotic EPCs. The impairment of eNOS activity could also be induced by using an SOCE inhibitor or by Stim1 gene silencing, indicating a link between the activities of eNOS and SOCE in AS. Furthermore, decreased SOCE function inhibited EPC proliferation and migration in vitro. In conclusion, our results showed that the reduction of SOCE induced EPC dysfunction during AS, potentially through downregulation of store-operated calcium channel (SOCC) components and impaired eNOS activity. Approaches aimed at reestablishing SOCE activity may thus improve the function of EPCs during AS.

Impact of methylmercury exposure on mitochondrial energetics in AC16 and H9C2 cardiomyocytes

It has been reported that chronic low dose exposures of methylmercury (MeHg) is associated with cardiovascular diseases in many populations worldwide. The toxic mechanisms through which these adverse effects occur are currently unknown. The objective of this study was to determine the bioenergetic and cytotoxic effects of MeHg on AC16 and H9C2 cardiomyocyte cell lines. Both cell lines exhibit significantly decreased mitochondrial function, cell viability and increased reactive oxygen species (ROS) production. Decreases in maximal respiration and reserve capacity was observed in both cell lines at 1μM. Bioenergetic profile experiments were also performed in tandem with cells exposed to diamide or menadione, compounds which accumulate in mitochondria and disrupt oxidative phosphorylation. AC16 cells show MeHg dose dependant sensitivities with Stateapparent and ATP production values, but H9C2 cells do not show these trends. H9C2 cells may be more resistant to MeHg toxicity than AC16 cells as reflected in the increases of proton leak and Stateapparent. No changes in expression of respiratory complexes were observed. Results suggest that MeHg has the potential to induce cytotoxicity. Furthermore, MeHg may have differential effects on AC16 and H9C2 cells, derived from human and rat cardiac tissue respectively, suggesting that differences in MeHg toxicity may be species-dependent.

Propolis: A Complex Natural Product with a Plethora of Biological Activities That Can Be Explored for Drug Development

The health industry has always used natural products as a rich, promising, and alternative source of drugs that are used in the health system. Propolis, a natural resinous product known for centuries, is a complex product obtained by honey bees from substances collected from parts of different plants, buds, and exudates in different geographic areas. Propolis has been attracting scientific attention since it has many biological and pharmacological properties, which are related to its chemical composition. Several in vitro and in vivo studies have been performed to characterize and understand the diverse bioactivities of propolis and its isolated compounds, as well as to evaluate and validate its potential. Yet, there is a lack of information concerning clinical effectiveness. The goal of this review is to discuss the potential of propolis for the development of new drugs by presenting published data concerning the chemical composition and the biological properties of this natural compound from different geographic origins.

Evaluation of two novel antioxidants with differential effects on curcumin-induced apoptosis in C2 skeletal myoblasts; involvement of JNKs

Excessive levels of reactive oxygen species (ROS) result in numerous pathologies including muscle disorders. In essence, skeletal muscle performance of daily activities can be severely affected by the redox imbalances occurring after muscular injuries, surgery, atrophy due to immobilization, dystrophy or eccentric muscle contraction. Therefore, research on the potential beneficial impact of antioxidants is of outmost importance. In this context, aiming at further exploring the mechanisms of action of our newly synthesized antioxidant compounds (AK1 and AK2) in a skeletal muscle experimental setting, we initially investigated their scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) and subsequently assessed their effect on the viability of C2 skeletal myoblasts in the presence of two pro-oxidants: H2O2 and curcumin (MTT assay). Interestingly, while both compounds reversed the detrimental effect of H2O2, only AK2 was cytoprotective in curcumin-treated C2 cells. We next confirmed the immediate activation of extracellular signal-regulated kinases (ERKs) and the more delayed activation profile of c-Jun NH2-terminal kinases (JNKs) in C2 skeletal myoblasts exposed to curcumin, by Western blotting. In correlation with the aforementioned results, only AK2 blocked the curcumin-induced activation of JNKs pathway. Furthermore, JNKs were revealed to mediate curcumin-induced apoptosis in C2 cells and only AK2 to effectively suppress it (by detecting its effect on poly(ADP-ribose) polymerase fragmentation). Overall, we have shown that two similar in structure novel antioxidants confer differential effects on C2 skeletal myoblasts viability under oxidative stress conditions. This result may be attributed to these antioxidants respective diverse mode of interaction with the signaling effectors involved in the observed responses. Future studies should further evaluate the mechanism of action of these compounds in order to support their potential application in therapeutic protocols against ROS-related muscle disorders.

Reductive potential - a savior turns stressor in protein aggregation cardiomyopathy

Redox homeostasis is essential for basal signaling of several physiological processes, but a unilateral shift towards an 'oxidative' or 'reductive' trait will alter intracellular redox milieu. Typically, such an event influences the structure and the native function of a cell or an organelle. Numerous experimental research and clinical trials over the last 6 decades have demonstrated that enhanced oxygen-derived free radicals constitute a major stimulus to trigger damage in several human diseases, including cardiovascular complications supporting the theory of oxidative stress (OS). However, until our key discovery, the dynamic interrelationship between "Reductive Stress (RS)" and cardiac health has been obscured by overwhelming OS studies (Rajasekaran et al., 2007). Notably, this seminal finding spurred considerable interest in investigations of other mechanistic insights, and thus far the results indicate a similar or stronger role for RS, as that of OS. In addition, from our own findings we strongly believe that constitutive activation of pathways that enable sustained generation of reducing equivalents of glutathione (GSH), reduced nicotinamide adenine dinucleotide phosphate (NADPH) will cause RS and impair the basal cellular signaling mechanisms operating through harmless pro-oxidative events, in turn, disrupting single and/or a combination of key cellular processes such as growth, maturation, differentiation, survival, death etc., that govern healthy cell physiology. Here, we have discussed the role of RS as a causal or contributing factor in relevant pathophysiology of a major cardiac disease of human origin.

Effects of L-carnitine supplementation on oxidative stress and antioxidant enzymes activities in patients with coronary artery disease: a randomized, placebo-controlled trial

BACKGROUND

Cardiovascular disease is the leading cause of death worldwide. Higher oxidative stress may contribute to the pathogenesis of coronary artery disease (CAD). The purpose of this study was to investigate the effect of L-carnitine (LC, 1000 mg/d) on the markers of oxidative stress and antioxidant enzymes activities in CAD patients.

METHODS

We enrolled 47 CAD patients in the study. The CAD patients were identified by cardiac catheterization as having at least 50% stenosis of one major coronary artery. The subjects were randomly assigned to the placebo (n = 24) and LC (n = 23) groups. The intervention was administered for 12 weeks. The levels of serum LC, plasma malondialdehyde (MDA), and erythrocyte antioxidant enzymes activities [catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx)] were measured before and after intervention.

RESULTS

Thirty-nine subjects completed the study (placebo, n = 19; LC, n = 20). After 12 weeks of LC supplementation, the level of MDA was significantly reduced (2.0 ± 0.3 to 1.8 ± 0.3 μmol/L, P = 0.02) and the level of LC (33.6 ± 13.6 to 40.0 ± 12.0 μmol/L, P = 0.04) and antioxidant enzymes activities [CAT (12.7 ± 5.5 to 13.1 ± 5.8 U/mg of protein, P = 0.02), SOD (14.8 ± 2.9 to 20.7 ± 5.8 U/mg of protein, P < 0.01), and GPx (20.3 ± 3.4 to 23.0 ± 3.1 U/mg of protein, P = 0.01)] were significantly increased. The level of LC was significantly positively correlated with the antioxidant enzymes activities (CAT, β = 0.87, P = 0.02; SOD, β = 0.72, P < 0.01).

CONCLUSION

LC supplementation at a dose of 1000 mg/d was associated with a significant reduction in oxidative stress and an increase in antioxidant enzymes activities in CAD patients. CAD patients might benefit from using LC supplements to increase their anti-oxidation capacity.

TRIAL REGISTRATION

Clinical Trials.gov Identifier: NCT01819701.

Gestational hypoxia increases reactive oxygen species and inhibits steroid hormone-mediated upregulation of Ca(2+)-activated K(+) channel function in uterine arteries

Gestational hypoxia inhibits steroid hormone-induced upregulation of Ca(2+)-activated K(+) (KCa) channel activities in uterine arteries. We tested the hypothesis that increased reactive oxygen species play an important role in hypoxia-mediated inhibition of KCa channel activities. Uterine arteries were isolated from nonpregnant (nonpregnant uterine artery) and near-term (≈142-145 day) pregnant (pregnant uterine artery) sheep maintained at either sea level or high altitude (3820 m, Pao2: 60 mm Hg) for 110 days. In pregnant uterine arteries, hypoxia significantly decreased large conductance channel opener NS1619- and small conductance channel opener NS309-induced relaxations, which were partially restored by reactive oxygen species inhibitor N-acetylcysteine (NAC). NAC significantly increased large conductance KCa but not small conductance KCa current densities in uterine arterial smooth muscle cells in pregnant animals acclimatized to high altitude. The NAC-sensitive component of small conductance KCa-induced relaxations was diminished in endothelium-denuded arteries. In nonpregnant uterine arteries, NS1619- and NS309-induced relaxations were diminished compared with those in pregnant uterine arteries. Treatment of nonpregnant uterine arteries with 17β-estradiol and progesterone for 48 hours increased small conductance KCa type 3 protein abundance and NS1619- and NS309-induced relaxations, which were inhibited by hypoxia. This hypoxia-mediated inhibition was reversed by NAC. Consistently, steroid hormone treatment had no significant effects on large conductance KCa current density in nonpregnant uterine arteries of hypoxic animals in the absence of NAC but significantly increased it in the presence of NAC. These results suggest an important role of hypoxia-mediated reactive oxygen species in negatively regulating steroid hormone-mediated upregulation of KCa channel activity and adaptation of uterine vascular reactivity in pregnancy, which may contribute to the increased incidence of preeclampsia and fetal intrauterine growth restriction associated with gestational hypoxia.

Regulation of protein tyrosine phosphatase oxidation in cell adhesion and migration

SIGNIFICANCE

Redox-regulated control of protein tyrosine phosphatases (PTPs) through inhibitory reversible oxidation of their active site is emerging as a novel and general mechanism for control of cell surface receptor-activated signaling. This mechanism allows for a previously unrecognized crosstalk between redox regulators and signaling pathways, governed by, for example, receptor tyrosine kinases and integrins, which control cell proliferation and migration.

RECENT ADVANCES

A large number of different molecules, in addition to hydrogen peroxide, have been found to induce PTP inactivation, including lipid peroxides, reactive nitrogen species, and hydrogen sulfide. Characterization of oxidized PTPs has identified different types of oxidative modifications that are likely to display differential sensitivity to various reducing systems. Accumulating evidence demonstrates that PTP oxidation occurs in a temporally and spatially restricted manner. Studies in cell and animal models indicate altered PTP oxidation in models of common diseases, such as cancer and metabolic/cardiovascular disease. Novel methods have appeared that allow characterization of global PTP oxidation.

CRITICAL ISSUES

As the understanding of the molecular and cellular biology of PTP oxidation is developing, it will be important to establish experimental procedures that allow analyses of PTP oxidation, and its regulation, in physiological and pathophysiological settings. Future studies should also aim to establish specific connections between various oxidants, specific PTPs, and defined signaling contexts.

FUTURE DIRECTIONS

Modulation of PTP activity still appears as a valid strategy for correction or inhibition of dys-regulated cell signaling. Continued studies on PTP oxidation might present yet unrecognized means to exploit this regulatory mechanism for pharmacological purposes.

Extracts of Artemisia ciniformis Protect Cytotoxicity Induced by Hydrogen Peroxide in H9c2 Cardiac Muscle Cells through the Inhibition of Reactive Oxygen Species

Objective. Artemisia ciniformis (Asteraceae) and A. biennis are two of 34 Artemisia species growing naturally in Iran. In this study we investigated whether different extracts of A. ciniformis and A. biennis have protective effect against hydrogen peroxide-induced cytotoxicity in rat cardiomyoblast cells (H9c2). Method. The dried and ground aerial parts of these two species were extracted successively using petroleum ether (40–60), dichloromethane, ethyl acetate (EA), ethanol (EtOH) and ethanol : water (1 : 1) by maceration method. To evaluate whether different extracts of A. ciniformis and A. biennis protect cardiomyoblast H9c2 cells from H₂O₂ cytotoxicity, we examined the direct cytotoxic effect of H₂O₂ on H9c2 cells in the presence and absence of different extracts. After then, cell viability was measured by MTT assay. Results. H₂O₂ induced cytotoxicity in a concentration dependent manner. The IC₅₀ value was 62.5 μM for 24 h exposure. However, pretreatment of cells with various concentrations of EA, EtOH, and EtOH/wt extract of A. ciniformis protected cells from H₂O₂-induced cytotoxicity. Moreover, pretreatment with EA, EtOH and EtOH/wt extracts of A. ciniformis lead to a decrease in the reactive oxygen species (ROS) generation. Taken together our observation indicated that nontoxic concentration of different extracts of A. ciniformis has protective effect on H₂O₂-induced cytotoxicity in H9c2 cells.

Effect of oxidative stress on sympathetic and renal vascular responses to ischemic exercise

Reactive oxygen species (ROS), produced acutely during skeletal muscle contraction, are known to stimulate group IV muscle afferents and accentuate the exercise pressor reflex (EPR) in rodents. The effect of ROS on the EPR in humans is unknown. We conducted a series of studies using ischemic fatiguing rhythmic handgrip to acutely increase ROS within skeletal muscle, ascorbic acid infusion to scavenge free radicals, and hyperoxia inhalation to further increase ROS production. We hypothesized that ascorbic acid would attenuate the EPR and that hyperoxia would accentuate the EPR. Ten young healthy subjects participated in two or three experimental trials on separate days. Beat-by-beat measurements of heart rate (HR), mean arterial pressure (MAP), muscle sympathetic nerve activity (MSNA), and renal vascular resistance index (RVRI) were measured and compared between treatments (saline and ascorbic acid; room air and hyperoxia). At fatigue, the reflex increases in MAP (31 ± 3 versus 29 ± 2 mmHg), HR (19 ± 3 versus 20 ± 3 bpm), MSNA burst rate (21 ± 4 versus 23 ± 4 burst/min), and RVRI (39 ± 12 versus 44 ± 13%) were not different between saline and ascorbic acid. Relative to room air, hyperoxia did not augment the reflex increases in MAP, HR, MSNA, or RVRI in response to exercise. Muscle metaboreflex activation and time/volume control experiments similarly showed no treatment effects. While contrary to our initial hypotheses, these findings suggest that ROS do not play a significant role in the normal reflex adjustments to ischemic exercise in young healthy humans.

Mitochondrial J haplogroup is associated with lower blood pressure and anti-oxidant status: findings in octo/nonagenarians from the BELFAST Study

Mitochondria produce cellular energy but also free-radicals, which damage cells despite an array of endogenous anti-oxidants. In Northern Europe, the mitochondrial haplogroup J has been related to longevity in nonagenarians and centenarians but also with age-related disease. Hypertension is an important contributor to atherosclerotic-related diseases and its pathogenesis is associated with increased oxidative stress. In this study, we questioned whether J haplogroup octo/nonagenarians from the Belfast Elderly Longitudinal Free-living Elderly STudy (BELFAST) study showed evidence of protective blood pressure or anti-oxidant profile which might explain their longevity advantage. Briefly, in a cross-sectional study, community-living, mentally alert (Folstein >25/30), octo/nonagenarian subjects, recruited for good health, were enlisted and consented as part of the BELFAST study, for blood pressure, anthropometric measurements and blood sampling. DNA typing for mitochondrial haplotypes was carried out with measurements for enzymatic and non-enzymatic antioxidants. J haplogroup carriers showed lower systolic blood pressure and glutathione peroxidase activity (Gpx) with higher folate measurements. There was no change in urate, bilirubin, albumin or nutrition-related antioxidants-selenium or vitamins A, C and α and β carotene. BELFAST study mtDNA J haplogroup octo/nonagenarians showed lower blood pressure and reduced glutathione peroxidase activity and higher folate, but no change for other antioxidants. These findings are of interest in view of mtDNA J haplogroup's association with increased age in some previous studies.

Serum bilirubin levels are lower in overweight asymptomatic middle-aged adults: an early indicator of metabolic syndrome?

OBJECTIVE

Low levels of bilirubin have recently been associated with obesity, diabetes mellitus, and metabolic syndrome. Here, we hypothesized that serum bilirubin levels might be already altered in overweight asymptomatic middle-aged individuals before full development of the metabolic syndrome.

METHODS

Healthy nonsmoking adults aged 25-49 (64 women and 32 men) participated in this cross-sectional study. All participants who reported stable weight within the last three months underwent standard anthropomorphological measurements of body composition, blood pressure measurements, aerobic and anaerobic capabilities assessment, dietary intake evaluation, and fasting serological measurements of total and direct bilirubin, glucose, insulin, triglycerides, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and C-reactive protein. Participants were divided into normal-weight and overweight groups. Linear correlation and multiple regression analyses were used to examine the association of serum bilirubin levels with all metabolic syndrome risk factor changes.

RESULTS

Serum bilirubin levels were lower in overweight healthy individuals of both sexes, and were negatively associated with abdominal obesity, insulin resistance, fasting glucose, fasting insulin, fasting triglycerides, total cholesterol, low-density lipoprotein cholesterol, and C-reactive protein levels but positively associated with aerobic body capabilities.

CONCLUSION

Our findings suggest that serum bilirubin levels have the potential to be employed as an early biomarker for indicating asymptomatic individuals at increased risk of developing metabolic syndrome.

A differential role of macrophage TRPM2 channels in Ca²⁺ signaling and cell death in early responses to H₂O₂

Reactive oxygen species such as H₂O₂ elevates the cytosolic Ca²⁺ concentration ([Ca²⁺]c) and causes cell death via poly(ADPR) polymerase (PARP) activation, which also represents the primary mechanism by which H₂O₂ activate the transient receptor potential melastatin-related 2 (TRPM2) channel as a Ca²⁺-permeable channel present in the plasma membrane or an intracellular Ca²⁺-release channel. The present study aimed to define the contribution and mechanisms of the TRPM2 channels in macrophage cells in mediating Ca²⁺ signaling and cell death during initial response to H₂O₂, using mouse peritoneal macrophage, RAW264.7, and differentiated THP-1 cells. H₂O₂ evoked robust increases in the [Ca²⁺]c, and such Ca²⁺ responses were significantly greater at body temperature than room temperature. H₂O₂-induced Ca²⁺ responses were strongly inhibited by pretreatment with PJ-34, a PARP inhibitor, and largely prevented by removal of extracellular Ca²⁺. Furthermore, H₂O₂-induced increases in the [Ca²⁺]c were completely abolished in macrophage cells isolated from trpm2-/- mice. H₂O₂ reduced macrophage cell viability in a duration- and concentration-dependent manner. H₂O₂-induced cell death was significantly attenuated by pretreatment with PJ-34 and TRPM2 channel deficiency but remained significant and persistent. Taken together, these results show that the TRPM2 channel in macrophage cells functions as a cell surface Ca²⁺-permeable channel that mediates Ca²⁺ influx and constitutes the principal Ca²⁺ signaling mechanism but has a limited, albeit significant, role in cell death during early exposure to H₂O₂.

Cross-talk between SIRT1 and p66Shc in vascular diseases

Accumulating evidence indicates that oxidative stress can occur through overproduction of reactive oxygen species (ROS) and/or reduced anti-oxidant potentials under pathophysiological conditions and plays an important role in the development of cardiovascular diseases (CVDs). Adapter protein p66Shc has the property to directly stimulate mitochondrial ROS generation by an oxidoreductase activity. A growing body of evidence implies that p66Shc plays a critical role in the pathophysiology of age-related vascular diseases. Silent mating type information regulator 2 homolog 1 (SIRT1), a nicotinamide adenine dinucleotide (NAD+)-dependent class III histone deacetylase (HDAC), has also been implicated in protection against vascular aging and age-related vascular diseases. Recently, we demonstrated that SIRT1 protects blood vessels from hyperglycemia-induced endothelial dysfunction through a novel mechanism involving the downregulation of p66Shc expression. In this review, we discuss the cross-talk between these two longevity genes as a mechanism of preventing vascular diseases by involving anti-oxidative stress responses and inhibiting endothelial senescence.