Targeting NOS as a therapeutic approach for heart failure

TRPA1: A promising target for pulmonary fibrosis?

Pulmonary fibrosis is a disease characterized by progressive scar formation and the ultimate manifestation of numerous lung diseases. It is known as "cancer that is not cancer" and has attracted widespread attention. However, its formation process is very complex, and the mechanism of occurrence has not been fully elucidated. Current research has found that TRPA1 may be a promising target in the pathogenesis of pulmonary fibrosis. The TRPA1 channel was first successfully isolated in human lung fibroblasts, and it was found to have a relatively concentrated distribution in the lungs and respiratory tract. It is also involved in various acute and chronic inflammatory processes of lung diseases and may even play a core role in the progression and/or prevention of pulmonary fibrosis. Natural ligands targeting TRPA1 could offer a promising alternative treatment for pulmonary diseases. Therefore, this review delves into the current understanding of pulmonary fibrogenesis, analyzes TRPA1 biological properties and regulation of lung disease with a focus on pulmonary fibrosis, summarizes the TRPA1 molecular structure and its biological function, and summarizes TRPA1 natural ligand sources, anti-pulmonary fibrosis activity and potential mechanisms. The aim is to decipher the exact role of TRPA1 channels in the pathophysiology of pulmonary fibrosis and to consider their potential in the development of new therapeutic strategies.

The Muscarinic Acetylcholine M2 Receptor-Induced Nitration of p190A by eNOS Increases RhoA Activity in Cardiac Myocytes

p190RhoGAP, which exists in two paralogs, p190RhoGAP-A (p190A) and p190RhoGAP-B (p190B), is a GTPase activating protein (GAP) contributing to the regulation of the cellular activity of RhoGTPases. Recent data showed that M2 muscarinic acetylcholine receptor (M2R) stimulation in neonatal rat cardiac myocytes (NRCM) induces the binding of p190RhoGAP to the long isoform of the regulator of G protein signaling 3 (RGS3L). This complex formation alters the substrate preference of p190RhoGAP from RhoA to Rac1. By analyzing carbachol-stimulated GAP activity, we show herein that p190A, but not p190B, alters its substrate preference in NRCM. Based on data that the RhoGAP activity of p190A in endothelial cells is diminished upon nitration by endothelial nitric oxide synthase (eNOS)-derived peroxynitrite, we studied whether carbachol-induced NO/peroxynitrite formation contributes to the carbachol-induced RhoA activation in NRCM. Interestingly, the carbachol-induced RhoA activation in NRCM was suppressed by the eNOS-preferring inhibitor L-NIO as well as the non-selective NOS inhibitor L-NAME. Using L-NIO, we firstly verified the carbachol-induced NO production concurrent with eNOS activation and, secondly, the carbachol-induced nitration of p190A in NRCM. By co-immunoprecipitation, the carbachol-induced complex formation of eNOS, p190A, RGS3L and caveolin-3 was detected. We thus conclude that the NO production by M2R-induced eNOS activation in caveolae in NRCM is required for the nitration of p190A, leading to the binding to RGS3L and the change in substrate preference from RhoA to Rac1. In line with this interpretation, the disruption of caveolae in NRCM by methyl-β-cyclodextrin suppressed carbachol-induced RhoA activation in NRCM to a similar extent as the inhibition of NO production.

Synergistic mechanism of processing method for Qixue Shuangbu prescription in the treatment of chronic heart failure based on plasma metabolomics-Systematic bioinformatics

Previous clinical studies have found that the efficacy of processed Qixue Shuangbu Prescription has been significantly improved in the treatment of chronic heart failure. However, the absorbed constituents and synergistic mechanisms of processed Qixue Shuangbu Prescription to enhance the therapeutic effect of chronic heart failure remain unclear. In this study, we propose an integrated strategy combining plasma metabolomics, network pharmacology, and molecular docking to study the absorbed constituents and synergistic mechanisms of processed Qixue Shuangbu Prescription. A total of 34 prototype constituents and 24 metabolites were identified in rat plasma after administration of crude and processed Qixue Shuangbu Prescription. As a result, six potential absorbed constituents and six potential targets for the treatment of chronic heart failure were identified. In addition, the result of molecular docking indicated that the key constituents exhibited good affinity to hub targets. This study showed that the multiomics approach could effectively clarify absorbed constituents and synergistic mechanisms of traditional Chinese medicine processing from a new perspective.

Heart Failure in Rheumatic Disease: Secular Trends and Novel Insights

There is a significant increase in risk of heart failure in several rheumatic diseases. Common cardiovascular risk factors and inflammatory processes, present in both rheumatic diseases and heart failure, are contributing to this increase. The opportunities for using immune-based strategies to fight development of heart failure in rheumatic diseases are evolving. The diversity of inflammation calls for a tailored characterization of inflammation, enabling differentiation of inflammation and subsequent introduction of precision medicine using target-specific strategies and immunomodulatory therapy. As the field of rheuma-cardiology is still evolving, clear recommendations cannot be given yet.

Pretreatment of Nicorandil Protects the Heart from Exhaustive Exercise-Induced Myocardial Injury in Rats

OBJECTIVE

Nicorandil has been widely used for the treatment of angina pectoris and myocardial infarction. The purpose of this study was to investigate whether nicorandil plays a protective role in exhaustive exercise (EE)-induced myocardial injury.

METHODS

Here, we applied the rat EE model and treated them with exercise preconditioning (EP, reported to protect the heart) or different doses of nicorandil gavage, respectively, to explore whether there are protective effects of single EP or nicorandil or a combination of both and the potential mechanism. Forty-nine male Sprague Dawley rats were randomly divided into control, EE, EP + EE, nicorandil (with low, middle, and high dose) + EE, and EP + nicorandil (middle dose) + EE. Blood samples and myocardial tissues were collected to analyze the myocardial injury-related index.

RESULTS

EE induced myocardial structural damage and altered the myocardial injury markers, which were partially reversed by pretreatment of nicorandil. In addition, oxidative stress and inflammation lead to the accumulation of reactive oxygen species (ROS) products and further damage to the myocardium, while pretreatment of nicorandil reduces the oxidative stress response and inflammation. Moreover, nicorandil suppressed the myocardial apoptosis induced by EE, as indicated by a decrease of Bax and caspase-3 expression and an increase of Bcl-2 expression. Finally, the pathway in which nicorandil plays a role may be involved in the endothelial nitric oxide synthase (eNOS)/nitric oxide (NO) pathway. Pretreatment of nicorandil increased the protein level of myocardial eNOS and NO production.

CONCLUSION

Our result demonstrated that nicorandil has protective effects in EE-induced myocardial injury with dose-dependent effects. A combination of nicorandil and EP can further improve the protective effects. Taken together, nicorandil can be potentially used as an intervention method in EE-induced myocardial injury.

Targeting Rac1 for the prevention of atherosclerosis among U.S. Veterans with inflammatory bowel disease

Evidence suggests that Ras-related C3 botulinum toxin substrate 1 (Rac1) might be a target in atherosclerotic disease (AD). We hypothesize that due to their ability to inhibit Rac1, thiopurines are associated with a lower risk of AD. We fit a time-dependent cox proportional hazards model estimating the hazard of AD among a national cohort of US veterans with inflammatory bowel disease. Patients exposed to thiopurines had a 7.5% lower risk of AD (HR = 0.925; 95% CI = (0.87-0.984)) compared to controls. The propensity score weighted analysis reveals thiopurine exposure reduces the risk of AD by 6.6% (HR = 0.934; 95% CI = (0.896-0.975)), compared to controls. Further exploration and evaluation of Rac1 inhibition as a target for AD is warranted.

Activation of Nrf2 by Lithospermic Acid Ameliorates Myocardial Ischemia and Reperfusion Injury by Promoting Phosphorylation of AMP-Activated Protein Kinase α (AMPKα)

Background: As a plant-derived polycyclic phenolic carboxylic acid isolated from Salvia miltiorrhiza, lithospermic acid (LA) has been identified as the pharmacological management for neuroprotection and hepatoprotection. However, the role and mechanism of lithospermic acid in the pathological process of myocardial ischemia-reperfusion injury are not fully revealed. Methods: C57BL/6 mice were subjected to myocardial ischemia and reperfusion (MI/R) surgery and pretreated by LA (50 mg/kg, oral gavage) for six consecutive days before operation. The in vitro model of hypoxia reoxygenation (HR) was induced by hypoxia for 24 h and reoxygenation for 6 h in H9C2 cells, which were subsequently administrated with lithospermic acid (100 μM). Nrf2 siRNA and dorsomorphin (DM), an inhibitor of AMPKα, were used to explore the function of AMPKα/Nrf2 in LA-mediated effects. Results: LA pretreatment attenuates infarct area and decreases levels of TnT and CK-MB in plasm following MI/R surgery in mice. Echocardiography and hemodynamics indicate that LA suppresses MI/R-induced cardiac dysfunction. Moreover, LA ameliorates oxidative stress and cardiomyocytes apoptosis following MI/R operation or HR in vivo and in vitro. In terms of mechanism, LA selectively activates eNOS, simultaneously increases nuclear translocation and phosphorylation of Nrf2 and promotes Nrf2/HO-1 pathway in vivo and in vitro, while cardioprotection of LA is abolished by pharmacological inhibitor of AMPK or Nrf2 siRNA in H9C2 cells. Conclusion: LA protects against MI/R-induced cardiac injury by promoting eNOS and Nrf2/HO-1 signaling via phosphorylation of AMPKα.

Inflammation in Human Heart Failure: Major Mediators and Therapeutic Targets

Inflammation has been recognized as a major pathophysiological contributor to the entire spectrum of human heart failure (HF), including HF with reduced ejection fraction, HF with preserved ejection fraction, acute HF and cardiogenic shock. Nevertheless, the results of several trials attempting anti-inflammatory strategies in HF patients have not been consistent or motivating and the clinical implementation of anti-inflammatory treatments for HF still requires larger and longer trials, as well as novel and/or more specific drugs. The present work reviews the different inflammatory mechanisms contributing to each type of HF, the major inflammatory mediators involved, namely tumor necrosis factor alpha, the interleukins 1, 6, 8, 10, 18, and 33, C-reactive protein and the enzymes myeloperoxidase and inducible nitric oxide synthase, and their effects on heart function. Furthermore, several trials targeting these mediators or involving other anti-inflammatory treatments in human HF are also described and analyzed. Future therapeutic advances will likely involve tailored anti-inflammatory treatments according to the patient's inflammatory profile, as well as the development of resolution pharmacology aimed at stimulating resolution of inflammation pathways in HF.

Nutraceutical, Dietary, and Lifestyle Options for Prevention and Treatment of Ventricular Hypertrophy and Heart Failure

Although well documented drug therapies are available for the management of ventricular hypertrophy (VH) and heart failure (HF), most patients nonetheless experience a downhill course, and further therapeutic measures are needed. Nutraceutical, dietary, and lifestyle measures may have particular merit in this regard, as they are currently available, relatively safe and inexpensive, and can lend themselves to primary prevention as well. A consideration of the pathogenic mechanisms underlying the VH/HF syndrome suggests that measures which control oxidative and endoplasmic reticulum (ER) stress, that support effective nitric oxide and hydrogen sulfide bioactivity, that prevent a reduction in cardiomyocyte pH, and that boost the production of protective hormones, such as fibroblast growth factor 21 (FGF21), while suppressing fibroblast growth factor 23 (FGF23) and marinobufagenin, may have utility for preventing and controlling this syndrome. Agents considered in this essay include phycocyanobilin, N-acetylcysteine, lipoic acid, ferulic acid, zinc, selenium, ubiquinol, astaxanthin, melatonin, tauroursodeoxycholic acid, berberine, citrulline, high-dose folate, cocoa flavanols, hawthorn extract, dietary nitrate, high-dose biotin, soy isoflavones, taurine, carnitine, magnesium orotate, EPA-rich fish oil, glycine, and copper. The potential advantages of whole-food plant-based diets, moderation in salt intake, avoidance of phosphate additives, and regular exercise training and sauna sessions are also discussed. There should be considerable scope for the development of functional foods and supplements which make it more convenient and affordable for patients to consume complementary combinations of the agents discussed here. Research Strategy: Key word searching of PubMed was employed to locate the research papers whose findings are cited in this essay.

Exploring Molecular Mechanism of Huangqi in Treating Heart Failure Using Network Pharmacology

Heart failure (HF), a clinical syndrome with a high incidence due to various reasons, is the advanced stage of most cardiovascular diseases. Huangqi is an effective treatment for cardiovascular disease, which has multitarget, multipathway functions. Therefore, we used network pharmacology to explore the molecular mechanism of Huangqi in treating HF. In this study, 21 compounds of Huangqi, which involved 407 targets, were obtained and reconfirmed using TCMSP and PubChem databases. Moreover, we used Cytoscape 3.7.1 to construct compound-target network and screened the top 10 compounds. 378 targets related to HF were obtained from CTD and GeneCards databases and HF-target network was constructed by Cytoscape 3.7.1. The 46 overlapping targets of HF and Huangqi were gotten by Draw Venn Diagram. STRING database was used to set up a protein-protein interaction network, and MCODE module and the top 5 targets with the highest degree for overlapping targets were obtained. GO analysis performed by Metascape indicated that the overlapping targets were mainly enriched in blood vessel development, reactive oxygen species metabolic process, response to wounding, blood circulation, and so on. KEGG analysis analyzed by ClueGO revealed that overlapping targets were mainly enriched in AGE-RAGE signaling pathway in diabetic complications, IL-17 signaling pathway, HIF-1 signaling pathway, c-type lectin receptor signaling pathway, relaxin signaling pathway, and so on. Finally, molecular docking showed that top 10 compounds of Huangqi also had good binding activities to important targets compared with digoxin, which was carried out in CB-Dock molecular docking server. In conclusion, Huangqi has potential effect on regulating overlapping targets and GE-RAGE signaling pathway in diabetic complications, IL-17 signaling pathway, HIF-1 signaling pathway, and so on to be a latent multitarget, multipathway treatment for HF.

A reliable fluorimetric method to screen the nitric oxide synthase inhibitors in 96 well plate

In general, 4 amino-5-methylamino-2',7'-difluorescein diacetate (DAF-FM-DA) dye is used to detect nitric oxide in biological systems through cell imaging. In this study, we have used 96 well plate format to quantify nitric oxide using DAF-FM-DA through a multimode reader (or independently using fluorospectrometer) and could be visualized in a fluorescence microscope. Similar study otherwise will require a high-end instrument. The method has been validated to screen NOS inhibitors in the HEK 293T cell lines over-expressing the NOS isoforms. We observed that the method is very simple to use, adaptive, sensitive and most importantly it saves time. REAGENTS/TOOLS: Ethanol (70% [v/v] in distilled water), Nω-Nitro-l-arginine (l-NAME), 7-Nitro-Indazole (7-NI) (Sigma, St. Louis, MO), HEK 293T cell lines (National Centre for Cell Science (NCCS), Pune, India), DMEM (Himedia laboratories Pvt), Fetal Bovine Serum (FBS) (Invitrogen, Carlsbad, CA), 100 U/mL penicillin, and 0.1 mg/mL streptomycin in a 5% CO2 atmosphere. Hank's Balanced Salt Solution (HBSS) without Phenol Red of pH 7.4 was prepared with the following composition: NaCl, 8.0g, KCl, 0.4g, CaCl₂, 0.14g, MgSO₄⋅7H₂O, 0.1g, MgCl₂·6H₂O, 0.1g, Na₂HPO₄·2H₂O, 0.06g, KH₂PO₄, 0.06g, glucose, 1.0g, NaHCO₃, 0.35g, H₂O, to 1000 ml, Sterilized and refrigerated, Calcium Ionophore A23187 (Sigma Aldrich 52665-69-7) DAF-FM Di Acetate (Molecular Probes Life Technologies), and DAF-FM Di Aceatate was prepared as a stock solution (5 mM) in DMSO, divided into aliquots and stored at -20 °C, followed by dilution to the required concentration in HBSS buffer before use. EQUIPMENT: Neubauer chamber, Microtube centrifuges (1.5 mL), Micropipettors,10,100, and 1000 mL with corresponding tips, multimode reader (Tecan, Synergy-HT), inverted fluorescence microscope (Nikon, eclipse Ti-S), black flat bottom Microplates (96-well) (Corning 3603).

Neuronal NO synthase mediates plenylephrine induced cardiomyocyte hypertrophy through facilitation of NFAT-dependent transcriptional activity

Neuronal nitric oxide synthase (NOS1) has been consistently shown to be the predominant isoform of NOS and/or NOS-derived NO that may be involved in the myocardial remodeling including cardiac hypertrophy. However, the direct functional contribution of NOS1 in this process remains to be elucidated. Therefore, in the present study, we attempted to use silent RNA and adenovirus mediated silencing or overexpression to investigate the role of NOS1 and the associated molecular signaling mechanisms during OKphenylephrine (PE)-induced cardiac hypertrophy growth in neonatal rat ventricular cardiomyocytes (NRVMs). We found that the expression of NOS1 was enhanced in PE-induced hypertrophic cardiomyocytes. Moreover, LVNIO treatment, a selective NOS1 inhibitor, significantly decreased PE-induced NRVMs hypertrophy and [³H]-leucine incorporation. We demonstrated that NOS1 gene silencing attenuated both the increased size and the transcriptional activity of the hypertrophic marker atrial natriuretic factor (ANF) induced by PE stimulation. Further investigation suggested that deficiency of NOS1-induced diminished NRVMS hypertrophy resulted in decreased calcineurin protein expression and activity (assessed by measuring the transcriptional activity of NFAT) and, an increased activity of the anti-hypertrophic pathway, GSK-3β (estimated by its augmented phosphorylated level). In contrast, exposing the NOS1 overexpressed NRVMs to PE-treatment further increased the hypertrophic growth, ANF transcriptional activity and calcineurin activity. Together, the results of the present study suggest that NOS1 is directly involved in controlling the development of cardiomyocyte hypertrophy.

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PE stimulation induces neuronal nitric oxide synthase (NOS1) protein expression.

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Pharmacological inhibition of NOS1 inhibits PE-induced cardiomyocyte hypertrophy.

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siRNA-mediated NOS1 gene suppression inhibits PE-induced cardiomyocyte hypertrophy.

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Adenovirus-mediated NOS1 overexpression exacerbates PE-induced myocyte hypertrophy.

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NFAT transcriptional factor may play a role in NOS1-induced myocyte growth.

Measurement of nitrate and nitrite in biopsy-sized muscle samples using HPLC

Studies of rats have indicated that skeletal muscle plays a central role in whole-body nitrate ( NO3- )/nitrite ( NO2- )/nitric oxide (NO) metabolism. Extending these results to humans, however, is challenging due to the small size of needle biopsy samples. We therefore developed a method to precisely and accurately quantify NO3- and NO2- in biopsy-sized muscle samples. NO3- and NO2- were extracted from rat soleus samples using methanol combined with mechanical homogenization + ultrasound, bead beating, pulverization at liquid N₂ temperature or pulverization + 0.5% Triton X-100. After centrifugation to remove proteins, NO3- and NO2- were measured using HPLC. Mechanical homogenization + ultrasound resulted in the lowest NO3- content (62 ± 20 pmol/mg), with high variability [coefficient of variation (CV) >50%] across samples from the same muscle. The NO2- / NO3- ratio (0.019 ± 0.006) was also elevated, suggestive of NO3- reduction during tissue processing. Bead beating or pulverization yielded lower NO2- and slightly higher NO3- levels, but reproducibility was still poor. Pulverization + 0.5% Triton X-100 provided the highest NO3- content (124 ± 12 pmol/mg) and lowest NO2- / NO3- ratio (0.008 ± 0.001), with the least variability between duplicate samples (CV ~15%). These values are consistent with literature data from larger rat muscle samples analyzed using chemiluminescence. Samples were stable for at least 5 wk at -80°C, provided residual xanthine oxidoreductase activity was blocked using 0.1 mmol/l oxypurinol. We have developed a method capable of measuring NO3- and NO2- in <1 mg of muscle. This method should prove highly useful in investigating the role of skeletal muscle in NO3- / NO2- /NO metabolism in human health and disease. NEW & NOTEWORTHY Measurement of nitrate and especially nitrite in small, i.e., biopsy-sized, muscle samples is analytically challenging. We have developed a precise, accurate, and convenient method for doing so using an affordable commercial HPLC system.

Dietary Nitrate Enhances the Contractile Properties of Human Skeletal Muscle

We review recent studies of the effects of dietary nitrate on human muscle contractile function and discuss possible underlying mechanisms.

Dietary nitrate, a source of nitric oxide (NO), improves the contractile properties of human muscle. We present the hypothesis that this is due to nitrosylation of the ryanodine receptor and increased NO signaling via the soluble guanyl cyclase-cyclic guanosine monophosphate-protein kinase G pathway, which together increase the free intracellular Ca²⁺ concentration along with the Ca²⁺ sensitivity of the myofilaments themselves.

Tyrosine phosphorylation of eNOS regulates myocardial survival after an ischaemic insult: role of PYK2

Aims

Endothelial nitric oxide (NO) synthase (eNOS) is known to play a cardioprotective protective. However, the molecular mechanisms regulating eNOS activity during ischaemia/reperfusion (I/R) injury are incompletely understood. eNOS is a substrate for several kinases that positively or negatively affect its enzymatic activity. Herein, we sought to correlate eNOS phosphorylation status with cardiomyocyte survival and we investigated the contribution of the proline-rich tyrosine kinase 2 (PYK2)/eNOS axis to the regulation of myocardial infarct size in vivo.

Methods and results

Exposure of H9c2 cardiomyocytes to H2O2 lead to PYK2 phosphorylation on its activator site (Y402) and eNOS phosphorylation on the inhibitor site Y656 and the activator site S1176. Both H2O2-induced eNOS phosphorylation events were abolished by PYK2 pharmacological inhibition or gene knockdown. Activity assays demonstrated that phosphorylation of the tyrosine inhibitory site exerts a dominant effect over S1176. In cardiomyocytes subjected to oxidative stress or oxygen-glucose deprivation, inhibition of PYK2 limited cell injury; this effect was prevented by inhibition of NO production. In vivo, ischaemia-reperfusion induced an early activation of PYK2, leading to eNOS phosphorylation on Y656, which, in turn, reduced NO output, as judged by the low tissue levels of its downstream effector cGMP. Moreover, pharmacological blockade of PYK2 alleviated eNOS inhibition and prevented cardiac damage following I/R injury in wild-type, but not in eNOS KO mice.

Conclusion

The current studies demonstrate that PYK2 is a pivotal regulator of eNOS function in myocardial infarction and identify PYK2 as a novel therapeutic target for cardioprotection.

Indirubin improves antioxidant and anti-inflammatory functions in lipopolysaccharide-challenged mice

Indirubin, a traditional Chinese medicine formulation from the Muricidae family, has been reported to exhibit abroad anti-cancer and anti-inflammation activities and mediate nuclear factor-κB (NF-κB) signal. Thus, this study aimed to investigate the protective effects of indirubin on LPS-induced acute lung injury and the potential mechanism in mice. The results showed that LPS treatment caused oxidative stress and inflammation in mice. Indirubin alleviated LPS-caused oxidative stress and inflammation via reducing MDA abundance and IL-1β and TNF-α expressions in mice. Meanwhile, indirubin improved lung NO production and inhibited NF-κB activation caused by LPS exposure. In conclusion, indirubin alleviated LPS-induced acute lung injury via improving antioxidant and anti-inflammatory functions, which might be associated with the NO and NF-κB signals.

Aucubin protects against pressure overload-induced cardiac remodelling via the β3 -adrenoceptor-neuronal NOS cascades

BACKGROUND AND PURPOSE

Aucubin, the predominant component of Eucommia ulmoides Oliv., has been shown to have profound effects on oxidative stress. As oxidative stress has previously been demonstrated to contribute to acute and chronic myocardial injury, we tested the effects of aucubin on cardiac remodelling and heart failure.

EXPERIMENTAL APPROACH

Initially, H9c2 cardiomyocytes and neonatal rat cardiomyocytes pretreated with aucubin (1, 3, 10, 25 and 50 μM) were challenged with phenylephrine. Secondly, the transverse aorta was constricted in C57/B6 and neuronal NOS (nNOS)-knockout mice, then aucubin (1 or 5 mg·kg^-1 body weight day^-1 ) was injected i.p. for 25 days. Hypertrophy was evaluated by assessing morphological changes, echocardiographic parameters, histological analyses and hypertrophic markers. Oxidative stress was evaluated by examining ROS generation, oxidase activity and NO generation. NOS expression was determined by Western blotting.

KEY RESULTS

Aucubin effectively suppressed cardiac remodelling; in mice, aucubin substantially inhibited pressure overload-induced cardiac hypertrophy, fibrosis and inflammation, whereas knocking out nNOS abolished these cardioprotective effects of aucubin. Blocking or knocking down the β₃ -adrenoceptor abolished the protective effects of aucubin in vitro. Furthermore, aucubin enhanced the protective effects of a β₃ -adrenoceptor agonist in vitro by increasing cellular cAMP levels, whereas treatment with an adenylate cyclase (AC) inhibitor abolished the cardioprotective effects of aucubin.

CONCLUSIONS AND IMPLICATIONS

Aucubin suppresses oxidative stress during cardiac remodelling by increasing the expression of nNOS in a process that requires activation of the β₃ -adrenoceptor/AC/cAMP pathway. These findings suggest that aucubin could have potential as a treatment for cardiac remodelling and heart failure.

Orientin Reduces Myocardial Infarction Size via eNOS/NO Signaling and Thus Mitigates Adverse Cardiac Remodeling

Orientin is a flavonoid extracted from Chinese traditional herb, Polygonum orientale L. Previous study has reported that orientin protected myocardial from ischemia reperfusion injury. However, whether orientin could protect against cardiac remodeling after myocardial injury remains unclear. The aim of our study is to investigate the effects of orientin in the progression of cardiac remodeling after myocardial infarction (MI). Mice cardiac remodeling model was established by left coronary artery ligation surgery. Experimental groups were as follows: vehicle-sham, orientin-sham, vehicle-MI, and orientin-MI. Animals were treated with vehicle or orientin (40 mg/kg) for 25 days starting 3 days after surgery. After 4 weeks of MI, mice with orientin treatment had decreased mortality and improved cardiac function. Significantly, at 4 weeks post-MI, orientin treatment decreased fibrosis, inflammatory response, and cardiomyocyte apoptosis. Furthermore, orientin treatment attenuated the hypoxia-induced neonatal rat cardiomyocyte apoptosis and increased cell viability. Additionally, orientin supplementation mitigated oxidative stress in remodeling heart tissue and cardiomyocytes exposed to hypoxia as measured by 2′,7′-dichlorodihydrofluorescein diacetate fluorescent probe. Mechanistically, orientin promotes cardioprotection by activating the eNOS/NO signaling cascades, which was confirmed by eNOS inhibitor (L-NAME) in vitro and in vivo. Inhibition of oxidative stress by orientin via eNOS/NO signaling cascades in the heart may represent a potential therapy for cardiac remodeling.

Low Nasal NO in Congenital Heart Disease With Systemic Right Ventricle and Postcardiac Transplantation

Background

NO bioavailability has not been systematically examined in congenital heart disease (CHD). To assess NO in patients with CHD, we measured nasal NO (nNO) generated by the nasal epithelia, given blood NO is difficult to measure (half‐life, <2 ms). Given NO's role in hemodynamic regulation and the association of NO bioavailability with heart failure risk, we hypothesized NO levels may differ with varying severity of CHD physiologic characteristics.

Methods and Results

Six‐hundred eighteen subjects, 483 with CHD and 135 controls, had nNO measured noninvasively via the nares using American Thoracic Society/European Respiratory Society guidelines. Subjects were dichotomized as having low or normal nNO based on age‐specific cutoff values. Prevalence of low nNO was examined by various CHD physiologic feature types. Low nNO was more prevalent with CHD than controls (odds ratio, 2.28; P=0.001). A logistic regression model showed overall significance (P=0.035) for single ventricle, systemic right ventricle, ventricular dysfunction, oxygen desaturation, and heterotaxy predicting low nNO, with systemic right ventricle independently having twice the odds of low nNO (odds ratio, 2.04; P=0.014). Patients with low nNO had a higher risk of experiencing heart transplant or death (hazard ratio, 2.75; P=0.048), and heart transplant recipients (N=16) exhibited 5 times the odds of low nNO (69% versus 30%; odds ratio, 5.1; P=0.001).

Conclusions

Patients with CHD have increased prevalence of low nNO, with highest odds seen with systemic right ventricle and heart transplant. Further studies are needed to investigate heart failure risks in patients with CHD with left versus right systemic ventricle physiologic characteristics and utility of low nNO for predicting heart failure risk.

Alterations in NO/ROS ratio and expression of Trx1 and Prdx2 in isoproterenol-induced cardiac hypertrophy

The development of cardiac hypertrophy is a complicated process, which undergoes a transition from compensatory hypertrophy to heart failure, and the identification of new biomarkers and targets for this disease is greatly needed. Here we investigated the development of isoproterenol (ISO)-induced cardiac hypertrophy in an in vitro experimental model. After the induction of hypertrophy with ISO treatment in H9c2 cells, cell surface area, cell viability, cellular reactive oxygen species (ROS), and nitric oxide (NO) levels were tested. Our data showed that the cell viability, mitochondrial membrane potential, and NO/ROS balance varied during the development of cardiac hypertrophy in H9c2 cells. It was also found that the expression of thioredoxin1 (Trx1) and peroxiredoxin2 (Prdx2) was decreased during the cardiac hypertrophy of H9c2 cells. These results suggest a critical role for Trx1 and Prdx2 in the cardiac hypertrophy of H9c2 cells and in the transition from compensated hypertrophy to de-compensated hypertrophy in H9c2 cells, and our findings may have important implications for the management of this disease.

Dietary Nitrate Increases VO2peak and Performance but Does Not Alter Ventilation or Efficiency in Patients With Heart Failure With Reduced Ejection Fraction

BACKGROUND

Patients with heart failure with reduced ejection fraction (HFrEF) exhibit lower efficiency, dyspnea, and diminished peak oxygen uptake (VO₂peak) during exercise. Dietary nitrate (NO₃^-), a source of nitric oxide (NO), has improved these measures in some studies of other populations. We determined the effects of acute NO₃^- ingestion on exercise responses in 8 patients with HFrEF using a randomized, double-blind, placebo-controlled, crossover design.

METHODS AND RESULTS

Plasma NO₃^-, nitrite (NO₂^-), and breath NO were measured at multiple time points and respiratory gas exchange was determined during exercise after ingestion of beetroot juice containing or devoid of 11.2 mmol of NO₃^-. NO₃^- intake increased (P < .05-0.001) plasma NO₃^- and NO₂^- and breath NO by 1469 ± 245%, 105 ± 34%, and 60 ± 18%, respectively. Efficiency and ventilation during exercise were unchanged. However, NO₃^- ingestion increased (P < .05) VO₂peak by 8 ± 2% (ie, from 21.4 ± 2.1 to 23.0 ± 2.3 mL^.min^-1.kg^-1). Time to fatigue improved (P < .05) by 7 ± 3 % (ie, from 582 ± 84 to 612 ± 81 seconds).

CONCLUSIONS

Acute dietary NO₃^- intake increases VO₂peak and performance in patients with HFrEF. These data, in conjunction with our recent data demonstrating that dietary NO₃^- also improves muscle contractile function, suggest that dietary NO₃^- supplementation may be a valuable means of enhancing exercise capacity in this population.

Nitric Oxide Synthase 1 Modulates Basal and β-Adrenergic-Stimulated Contractility by Rapid and Reversible Redox-Dependent S-Nitrosylation of the Heart

S-nitrosylation of several Ca²⁺ regulating proteins in response to β-adrenergic stimulation was recently described in the heart; however the specific nitric oxide synthase (NOS) isoform and signaling pathways responsible for this modification have not been elucidated. NOS-1 activity increases inotropism, therefore, we tested whether β-adrenergic stimulation induces NOS-1-dependent S-nitrosylation of total proteins, the ryanodine receptor (RyR2), SERCA2 and the L-Type Ca²⁺ channel (LTCC). In the isolated rat heart, isoproterenol (10 nM, 3-min) increased S-nitrosylation of total cardiac proteins (+46±14%) and RyR2 (+146±77%), without affecting S-nitrosylation of SERCA2 and LTCC. Selective NOS-1 blockade with S-methyl-L-thiocitrulline (SMTC) and N^ω-propyl-l-arginine decreased basal contractility and relaxation (−25–30%) and basal S-nitrosylation of total proteins (−25–60%), RyR2, SERCA2 and LTCC (−60–75%). NOS-1 inhibition reduced (−25–40%) the inotropic response and protein S-nitrosylation induced by isoproterenol, particularly that of RyR2 (−85±7%). Tempol, a superoxide scavenger, mimicked the effects of NOS-1 inhibition on inotropism and protein S-nitrosylation; whereas selective NOS-3 inhibitor L-N⁵-(1-Iminoethyl)ornithine had no effect. Inhibition of NOS-1 did not affect phospholamban phosphorylation, but reduced its oligomerization. Attenuation of contractility was abolished by PKA blockade and unaffected by guanylate cyclase inhibition. Additionally, in isolated mouse cardiomyocytes, NOS-1 inhibition or removal reduced the Ca²⁺-transient amplitude and sarcomere shortening induced by isoproterenol or by direct PKA activation. We conclude that 1) normal cardiac performance requires basal NOS-1 activity and S-nitrosylation of the calcium-cycling machinery; 2) β-adrenergic stimulation induces rapid and reversible NOS-1 dependent, PKA and ROS-dependent, S-nitrosylation of RyR2 and other proteins, accounting for about one third of its inotropic effect.

Cardioprotective effects of Viscum album L. ssp. album (Loranthaceae) on isoproterenol-induced heart failure via regulation of the nitric oxide pathway in rats

OBJECTIVE

Viscum album L. has favorable cardiovascular effects including antihypertensive and vasorelaxant activity, and the nitric oxide (NO) pathway upregulation has been proposed to be the underlying mechanism. NO also plays an important role in the pathophysiology of heart failure. However, its effects on cardiac systolic function are unclear.

METHODS

A total of 30 male Wistar albino rats at 12 weeks of age were randomly divided into three groups: control, isoproterenol-induced heart failure group (ISO), and isoproterenol-induced heart failure + V. album treatment group (VA) groups (n=10 in each group). V. album was orally given at a dose of 250 mg/kg/day by gavage. Parameters of heart failure were compared among the groups. Tamhane's T2 test, paired sample t-test, and Bonferroni methods were used for statistical analysis.

RESULTS

V. album resulted in an improvement in all parameters of heart failure including left ventricular diameters (6.34±0.23 mm, 6.98±0.35 mm, and 6.71±0.10 mm for left ventricular end-diastolic diameter in control, ISO, and VA groups, respectively, p<0.05), ejection fraction (73.3±3.1%, 56.7±2.6%, and 65.2±1.5% for control, ISO, and VA groups, respectively, p<0.05), serum NT-proBNP levels, and histopathological changes. V. album treatment resulted in a statistically significant attenuation of increased levels of NO and iNOS (p<0.0001). The levels of hs-CRP were also found to be lower in the VA group compared with the controls and ISO groups (p<0.01).

CONCLUSION

V. album exerted favorable effects on left ventricular function in isoproterenol-induced heart failure rats. Upregulation of the NO pathway seems to be the possible pathophysiological mechanism. Favorable vascular outcomes can also be speculated considering the reduction in serum hs-CRP levels.

Caveolin-1 single-nucleotide polymorphism and arterial stiffness in non-dialysis chronic kidney disease

BACKGROUND

Arteriosclerosis is an independent predictor of increased cardiovascular mortality in chronic kidney disease (CKD). Histologically it is characterized by hypertrophy and fibrosis of the arterial media wall leading to increased arterial stiffness and end-organ damage. Caveolin-1 acts as an intracellular signalling pathway chaperone in human fibrotic and vascular diseases. The purpose of this study was to assess the association between caveolin-1 (CAV1) single-nucleotide polymorphism (SNP) rs4730751 and arterial stiffness as measured by arterial pulse wave velocity (PWV) in an early-stage CKD cohort and in a cohort with more severe CKD.

METHODS

Two prospectively maintained patient cohorts with non-dialysis CKD were studied: 144 patients in the Chronic Renal Impairment in Birmingham (CRIB) cohort and 147 patients in the Renal Impairment in Secondary Care (RIISC) cohort, with matched exclusion criteria and DNA sampling availability. At entry to each cohort database, each patient's initial arterial PWV was measured, as well as their anthropomorphic and biochemical data. CAV1 rs4730751 SNP genotyping was performed using Taqman technology.

RESULTS

The CAV1 rs4730751 SNP CC genotype was associated with lower arterial PWV in both CRIB early stage CKD patients [8.1 versus 8.6 m/s; coefficient -0.780 (-1.412, -0.149); P = 0.016] and RIISC more advanced stage CKD patients [8.7 versus 9.4 m/s; coefficient -0.695 (-1.288, -0.102); P = 0.022]; these relationships held following adjustment for other important confounders.

CONCLUSIONS

This replicated study suggests potential utility of the studied CAV1 SNP as a genetic biomarker in CKD and a role for CAV1 in the development of arteriosclerosis in this setting. Further studies are warranted to further explore the basic science driving these clinical observations.

Normal and high eNOS levels are detrimental in both mild and severe cardiac pressure-overload

Nitric oxide (NO) produced by endothelial NO synthase (eNOS) exerts beneficial effects in a variety of cardiovascular disease states. Studies on the benefit of eNOS activity in pressure-overload cardiac hypertrophy and dysfunction produced by aortic stenosis are equivocal, which may be due to different expression levels of eNOS or different severities of pressure-overload. Consequently, we investigated the effects of eNOS-expression level on cardiac hypertrophy and dysfunction produced by mild or severe pressure-overload. To unravel the impact of eNOS on pressure-overload cardiac dysfunction we subjected eNOS deficient, wildtype and eNOS overexpressing transgenic (eNOS-Tg) mice to 8weeks of mild or severe transverse aortic constriction (TAC) and studied cardiac geometry and function at the whole organ and tissue level. In both mild and severe TAC, lack of eNOS ameliorated, whereas eNOS overexpression aggravated, TAC-induced cardiac remodeling and dysfunction. Moreover, the detrimental effects of eNOS in severe TAC were associated with aggravation of TAC-induced NOS-dependent oxidative stress and by further elevation of eNOS monomer levels, consistent with enhanced eNOS uncoupling. In the presence of TAC, scavenging of reactive oxygen species with N-acetylcysteine reduced eNOS S-glutathionylation, eNOS monomer and NOS-dependent superoxide levels in eNOS-Tg mice to wildtype levels. Accordingly, N-acetylcysteine improved cardiac function in eNOS-Tg but not in wildtype mice with TAC. In conclusion, independent of the severity of TAC, eNOS aggravates cardiac remodeling and dysfunction, which appears due to TAC-induced eNOS uncoupling and superoxide production.

Molecular Signature of Nitroso-Redox Balance in Idiopathic Dilated Cardiomyopathies

BACKGROUND

Idiopathic dilated cardiomyopathy is one of the most common types of cardiomyopathy. It has been proposed that an increase in oxidative stress in heart failure leads to a decrease in nitric oxide signaling, leading to impaired nitroso-redox signaling. To test this hypothesis, we investigated the occurrence of protein S-nitrosylation (SNO) and oxidation in biopsies from explanted dilated cardiomyopathy and nonfailing donor male and female human hearts.

METHODS AND RESULTS

Redox-based resin-assisted capture for oxidation and SNO proteomic analysis was used to measure protein oxidation and SNO, respectively. In addition, 2-dimensional difference gel electrophoresis using maleimide sulfhydryl-reactive fluors was used to identify the SNO proteins. Protein oxidation increased in dilated cardiomyopathy biopsies in comparison with those from healthy donors. Interestingly, we did not find a consistent decrease in SNO in failing hearts; we found that some proteins showed an increase in SNO and others showed a decrease, and there were sex-specific differences in the response. We found 10 proteins with a significant decrease in SNO and 4 proteins with an increase in SNO in failing female hearts. Comparing nonfailing and failing male hearts, we found 9 proteins with a significant decrease and 12 proteins with a significant increase. We also found an increase in S-glutathionylation of endothelial nitric oxide synthase in failing female versus male hearts, suggesting an increase in uncoupled nitric oxide synthase in female hearts.

CONCLUSION

These findings highlight the importance of nitroso-redox signaling in both physiological and pathological conditions, suggesting a potential target to treat heart failure.

Strategies to increase nitric oxide signalling in cardiovascular disease

Nitric oxide (NO) is a key signalling molecule in the cardiovascular, immune and central nervous systems, and crucial steps in the regulation of NO bioavailability in health and disease are well characterized. Although early approaches to therapeutically modulate NO bioavailability failed in clinical trials, an enhanced understanding of fundamental subcellular signalling has enabled a range of novel therapeutic approaches to be identified. These include the identification of: new pathways for enhancing NO synthase activity; ways to amplify the nitrate-nitrite-NO pathway; novel classes of NO-donating drugs; drugs that limit NO metabolism through effects on reactive oxygen species; and ways to modulate downstream phosphodiesterases and soluble guanylyl cyclases. In this Review, we discuss these latest developments, with a focus on cardiovascular disease.

Preinduction of heat shock protein 70 protects mice against post-infection irritable bowel syndrome via NF-κB and NOS/NO signaling pathways

This study aimed to investigate the protective effects of preinduction of heat shock protein 70 (HSP70) on Trichinella spiralis infection-induced post-infectious irritable bowel syndrome (PI-IBS) in mice. Trichinella spiralis infection significantly reduced HSP70 abundance, ileal villus height and crypt depth, expression of tight junctions, serum lysine and arginine concentrations, and ileal SCL7A6 and SCL7A7 mRNA levels, induced inflammatory response, and activated NF-κB signaling pathway. Meanwhile, the heat treatment upregulated HSP70 expression, and then reversed intestinal dysfunction and inflammatory response. Preinduction of HSP70 enhanced serum arginine and intestinal SCL7A7 expression and inhibited NF-κB activation compared with PI-IBS model. Treatment with pyrrolidine dithiocarbamate (PDTC, an NF-κB inhibitor) and N-nitro-L-arginine methyl ester hydrochloride (L-NAME, a nitric oxide synthase inhibitor, NOS) further demonstrated that preinduction of HSP70 might inhibit NF-κB and activated NOS/nitric oxide (NO) signaling pathways. In conclusion, preinduction of HSP70 by heat treatment may confer beneficial effects on Trichinella spiralis infection-induced PI-IBS in mice, and the protective effect of HSP70 may be associated with inhibition of NF-κB and stimulation of NOS/NO signaling pathways.

Endothelial nitric oxide synthase single nucleotide polymorphism and left ventricular function in early chronic kidney disease

Background

Chronic kidney disease (CKD) is associated with accelerated cardiovascular disease and heart failure. Endothelial nitric oxide synthase (eNOS) Glu298Asp single nucleotide polymorphism (SNP) genotype has been associated with a worse phenotype amongst patients with established heart failure and in patients with progression of their renal disease. The association of a cardiac functional difference in non-dialysis CKD patients with no known previous heart failure, and eNOS gene variant is investigated.

Methods

140 non-dialysis CKD patients, who had cardiac magnetic resonance (CMR) imaging and tissue doppler echocardiography as part of two clinical trials, were genotyped for eNOS Glu298Asp SNP retrospectively.

Results

The median estimated glomerular filtration rate (eGFR) was 50mls/min and left ventricular ejection fraction (LVEF) was 74% with no overt diastolic dysfunction in this cohort. There were significant differences in LVEF across eNOS genotypes with GG genotype being associated with a worse LVEF compared to other genotypes (LVEF: GG 71%, TG 76%, TT 73%, p = 0.006). After multivariate analysis, (adjusting for age, eGFR, baseline mean arterial pressure, contemporary CMR heart rate, total cholesterol, high sensitive C-reactive protein, body mass index and gender) GG genotype was associated with a worse LVEF, and increased LV end-diastolic and systolic index (p = 0.004, 0.049 and 0.009 respectively).

Conclusions

eNOS Glu298Asp rs1799983 polymorphism in CKD patients is associated with relevant sub-clinical cardiac remodelling as detected by CMR. This gene variant may therefore represent an important genetic biomarker, and possibly highlight pathways for intervention, in these patients who are at particular risk of worsening cardiac disease as their renal dysfunction progresses.