Mendelian randomization study of the relation between adiponectin and heart function, unravelling the paradox

High adiponectin concentrations are generally regarded as beneficial with regard to cardiometabolic health, but have been paradoxically associated with increased cardiovascular disease risk, specifically heart failure, in individuals at high cardiovascular risk. We aimed to investigate the association between adiponectin and heart function parameters, and inversely, we estimated the effect of genetically-determined heart function and NT-proBNP as the main marker of heart failure on adiponectin using Mendelian randomisation. Observational analyses between adiponectin and measures of heart function, i.e. E/A ratio, left, and right ventricular ejection fraction, were performed in participants of the Netherlands Epidemiology of Obesity (NEO) study, assessed by MRI of the heart (n = 1,138). Two-sample Mendelian randomisation analyses were conducted to estimate the effect of NT-proBNP and heart function on adiponectin concentrations using publicly-available summary statistics (ADIPOGen; the PLATO trial). The mean (standard deviation) age was 56 (6) years and mean body mass index was 26 (4) kg/m². Per five μg/mL higher adiponectin, the E/A ratio was -0.05 (95 % CI: -0.10, -0.01) lower, left ventricle ejection fraction was -0.5 % (95 % CI: -1.1, 0.1) lower, and right ventricle ejection fraction was 0.5 % (95 % CI: -0.1, 1.2) higher. Genetically-determined NT-proBNP was causally related to adiponectin concentrations in ADIPOGen: per doubling of genetically-determined NT-proBNP, adiponectin concentrations were 11.4 % (95 % CI: 1.7, 21.6) higher. With causal MR methods we showed that NT-proBNP affects adiponectin concentrations, while adiponectin is not associated with heart function parameters. Therefore, reverse causation may explain the adiponectin paradox observed in previous studies.

Pathophysiology and significance of natriuretic peptides in patients with end-stage kidney disease

Natriuretic peptides (NP), especially B type (BNP) and its N-terminal pro-B type natriuretic peptide (NT-proBNP), have long been regarded as biomarkers of volume overload and tools to exclude heart failure in the general population. However, their role in end-stage kidney disease (ESKD) is less certain given that BNP and NT-proBNP are excreted by the kidney and so serum concentrations of NPs are nearly universally elevated compared to controls. Nevertheless, the accumulated evidence suggests thatserum concentrations of NPs in patients with ESKD show moderate or strong positive relationships with underlying heart disease, abnormal cardiac structure or function and mortality. Limited evidence also supports the role of BNP including NT-proBNP, ANP in some studies, rather than CNP or DNP in risk stratification among ESKD patients as well as the utility of BNP samplings pre- and post- hemodialysis. However, studies of the cut-off values of NPs have yielded inconsistent results, such that further large-scale studies are needed to clarify these issues. This review summarizes the pathophysiology and significance of NPs in ESKD patients, especially their potential role as risk stratification biomarkers in clinical management.

Brain natriuretic peptide constitutively downregulates P2X3 receptors by controlling their phosphorylation state and membrane localization

BACKGROUND

ATP-gated P2X3 receptors are important transducers of nociceptive stimuli and are almost exclusively expressed by sensory ganglion neurons. In mouse trigeminal ganglion (TG), P2X3 receptor function is unexpectedly enhanced by pharmacological block of natriuretic peptide receptor-A (NPR-A), outlining a potential inhibitory role of endogenous natriuretic peptides in nociception mediated by P2X3 receptors. Lack of change in P2X3 protein expression indicates a complex modulation whose mechanisms for downregulating P2X3 receptor function remain unclear.

RESULTS

To clarify this process in mouse TG cultures, we suppressed NPR-A signaling with either siRNA of the endogenous agonist BNP, or the NPR-A blocker anantin. Thus, we investigated changes in P2X3 receptor distribution in the lipid raft membrane compartment, their phosphorylation state, as well as their function with patch clamping. Delayed onset of P2X3 desensitization was one mechanism for the anantin-induced enhancement of P2X3 activity. Anantin application caused preferential P2X3 receptor redistribution to the lipid raft compartment and decreased P2X3 serine phosphorylation, two phenomena that were not interdependent. An inhibitor of cGMP-dependent protein kinase and siRNA-mediated knockdown of BNP mimicked the effect of anantin.

CONCLUSIONS

We demonstrated that in mouse trigeminal neurons endogenous BNP acts on NPR-A receptors to determine constitutive depression of P2X3 receptor function. Tonic inhibition of P2X3 receptor activity by BNP/NPR-A/PKG pathways occurs via two distinct mechanisms: P2X3 serine phosphorylation and receptor redistribution to non-raft membrane compartments. This novel mechanism of receptor control might be a target for future studies aiming at decreasing dysregulated P2X3 receptor activity in chronic pain.

Endogenous BNP attenuates cardiomyocyte hypertrophy induced by Ang II via p38 MAPK/Smad signaling

Previous studies suggest that B-type natriuretic peptide (BNP) exerts inhibitory effects on cardiac hypertrophy. Our studies have shown that long-term treatment of rats with BNP attenuated cardiac hypertrophy via down-regulation of TGF-β1 and up-regulation of smad7. However, the mechanisms have not been fully elucidated. In the present study, we examined the role of endogenous BNP on cardiomyocyte hypertrophy and the related molecular mechanisms. Cardiomyocytes from neonatal rats were cultured and a cardiomyocyte hypertrophy model was established with angiotensin II (Ang II). The effects of blockade of endogenous BNP by its receptor antagonist, HS-142-1, on cell hypertrophy were investigated. Cardiomyocyte hypertrophy indices, including cell surface area, protein content and [3H] incorporation were measured. Smad and mitogen-activated protein kinase (MAPK) protein expressions were detected using Western blot analysis. We found that HS-142-1 increased Ang II-stimulated cardiomyocyte hypertrophy and Smad activation. In addition, the increase of cardiomyocyte hypertrophy and the activation of Smad caused by HS-142-1 were not altered by the ERK inhibitor, PD98059, but were decreased by the p38 MAPK inhibitor, SB203580. These results demonstrate that endogenous BNP attenuates cardiomyocyte hypertrophy, and this may be mediated through p38 MAPK/Smad, but not ERK/Smad signaling pathway.

Weaning failure: my heart is not up to it

Weaning patients from mechanical ventilation has been compared to a cardiac stress test. Weaning failure (WF) from a cardiac origin can be common in patients with limited cardiac reserve. Diuretic and vasodilator therapies are indicated for WF due to excessive preload, afterload, or myocardial ischemia. Alteration in intrathoracic pressure and lung volumes may also impact weaning process in a patient with poor cardiac function. Noninvasive ventilation decreases cardiac stress load and should be utilized in weaning patients with poor cardiac reserves. In fact, positive pressure therapy is now the standard of care for treating a patient with acute pulmonary edema and to decrease afterload (Frazier et al. Biol Res Nurs 2000; 1(4): 253-264; Pinsky MR. Chest 2005; 128(5 Suppl 2): 592S-597S.). Recently, biomarkers and echocardiography have been utilized to assess weaning success during spontaneous breathing trials. In this article, we describe the physiological alterations in cardiac and pulmonary systems during the weaning process and its impact on weaning outcome.

[Clinical significance of BNP as a biomarker for cardiac disease--from a viewpoint of basic science and clinical aspect]

BNP was discovered in the porcine brain extract in 1988. Subsequent studies have demonstrated that BNP is a cardiac hormone in humans. Plasma level of BNP is increased in patients with heart failure more than ANP. Therefore, BNP measurements as a biomarker for heart failure spread all over our country and all over the world. Now the guideline in the world recognizes that BNP is a useful biomarker for diagnosis for acute and chronic heart failure. However, the usefulness of "BNP-guided therapy for heart failure" is still controversial at present, because randomized-controlled studies have shown the neutral results. Although more than twenty years have passed since its discovery, recent studies have shown the new findings in BNP research. I describe here the recent advance of BNP research.

Potential interaction of brain natriuretic peptide with hyperadiponectinemia in preeclampsia

Adiponectin was reported recently to have roles in the pathophysiology of preeclampsia. Moreover, elevation of adiponectin and brain natriuretic peptide (BNP) has been observed in preeclampsia. We examined the possible links between adiponectin and BNP in the pathophysiology of preeclampsia. We performed a cross-sectional study in 56 preeclampsia patients and 56 controls matched for gestational age and body mass index. The BNP, leptin, and adiponectin levels were measured by ELISA, and their mRNA expressions were evaluated in omental adipose tissue by real-time PCR. The effects of BNP on adiponectin and leptin mRNA expression and secretion were investigated in primary cultures of adipocytes from obese and normal-weight women. The BNP, adiponectin, and leptin levels were significantly higher in preeclampsia patients compared with controls. The adiponectin level was increased significantly in normal-weight preeclampsia patients compared with overweight preeclampsia patients. Adiponectin mRNA expression was increased significantly in adipose tissues of preeclampsia patients compared with controls and was also increased significantly in normal-weight preeclampsia patients compared with overweight preeclampsia patients, whereas leptin was not. BNP and adiponectin showed significant positive correlations in both normal-weight and overweight preeclampsia patients. BNP had a significantly weaker effect on adiponectin in overweight compared with normal-weight preeclampsia patients. Moreover, BNP had a weaker effect on adiponectin production in adipocytes from overweight women compared with adipocytes from normal-weight women using primary culture of human adipocytes. These data suggested that BNP may play a role in hyperadiponectinemia of preeclampsia patients. The weaker effect of BNP on adiponectin production may participate in the pathophysiology of overweight preeclampsia patients.

[BNP and NT-proBNP: reference values and cutoff limits]

Natriuretic peptides, particularly BNP and NT-proBNP, are increasingly used as screening test in patients with symptoms suggestive of heart failure (HF). Due to their high negative predictive values, natriuretic peptide determinations allow to exclude chronic HF with great certainty and to identify patients for whom echography is not necessary. These biomarkers are also useful for diagnostic purposes, high plasma levels being related to an increased risk of cardiovascular hospitalisation and death. Risk stratification in patients with HF symptoms is based on "low" and "high" cut-off limits, for which different values have been proposed. The aim of this paper is to discuss the delineation of the decision limits and the intermediate grey zone in comparison to NT-proBNP reference values obtained in a representative group of subjects living in the Liège area (Belgium). Data were analysed in relation to age and gender, two of the main parameters influencing the natriuretic peptide plasma levels.

BNP and iNOS in decompensated chronic heart failure: a linear correlation

Heart Failure (HF) is characterized by activation inflammatory mediators that contributes to the disease progression. Brain natriuretic peptide (BNP) plasma levels increase in HF with a prognostic significance. The aim of this study was to evaluate the expression and activity of inducible nitric oxide synthase (iNOS) in peripheral blood mononuclear cell (PBMC) extracted from patients and a possible linear correlation between iNOS and plasma levels of BNP in decompensated chronic HF (DCHF) patients. To establish the DCHF, thirty-five male patients were evaluated. All patients were venesected within 24 h of admission to exclude an inflammatory state through evaluation of c-reactive protein. Only twenty subjects showed symptoms of DCHF were included in the study. Other patients were included in the control group. In DCHF, left ventricular ejection fraction (LVEF) percent was reduced and systolic pulmonary artery pressure (PAPs) was increased. Furthermore, iNOS expression and BNP plasma levels were significantly higher in patients with DCHF as compared to controls group. These findings indicate that in DCHF patients, iNOS activity exhibits a significant linear correlation with plasmatic BNP level.

Laboratory medicine: the precursors strike back

Laboratory Medicine represents a major component of healthcare and nowadays it is involved in more than seventy percent of medical decisions. The value of any innovative laboratory test will depend on its clinical sensitivity and specificity. This clinical value is of course influenced by the analytical performance and reliability of the assay. Some spectacular advances in the understanding of circulating forms were recently accomplished with an emphasis place on prohormones and analytes precursors. Release of prohormones in the blood flow may be of major impact to improve diagnosis and risk stratification but may also influence the analytical specificity of some commercial assays. The goal of this short review is to discuss some perspectives related to some analytes' precursors that have recently been evidenced to affect assay specificity or increase assay discriminatory power.

Plasma ANP and BNP during exercise in patients with major depressive disorder and in healthy controls

BACKGROUND

Increased levels of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) have been shown to reduce the hormones in the HPA axis. In this study we addressed the question whether patients with unmedicated major depressive disorder (MDD) might have altered baseline levels of these natriuretic peptides and an altered response to acute exercise.

METHODS

An incremental exercise test was performed in 18 patients with MDD and in 18 healthy controls. Plasma concentrations of ANP and BNP were determined at rest, during the exercise test and 30 min post exercise using immunoradiometric assays.

RESULTS

During the exercise test the concentrations of ANP and BNP increased significantly in both groups. The MDD group showed significantly lower levels of ANP than the controls at rest, at maximal work rate and post exercise and of BNP at rest and at maximal work rate. The dynamic changes of both ANP and BNP, respectively, from baseline to maximal work rate were significantly lower in the MDD group. A slightly lower (non-significant) maximal work rate was observed in the MDD group compared with the controls.

LIMITATIONS

Group sizes are relatively limited.

CONCLUSION

Lower concentrations of ANP and BNP during rest and exercise were observed in the MDD patients together with a decreased dynamic response to maximal exercise. Hypothetically, the reduced ANP and BNP concentration contributes to the high hormone levels in the HPA system seen in depressive disorders. Of interest for future research is whether physical training might increase the levels of ANP and BNP and thereby diminish depressive symptoms.

Natriuretic peptides and atrial fibrillation

BACKGROUND AND OBJECTIVE

Atrial fibrillation (AF) is the most common arrhythmia in the medical practice, it is associated with an increased total and cardiovascular mortality, as well as cardiovascular morbidity, including stroke and heart failure. AF is encountered in different medical specialties including cardiology, family medicine and emergency medicine as well. Treatment goal is to minimize stroke risk but also taking into account the quality of life. Therefore rate or a rhythm control strategies must be carefully selected. This review focuses on natriuretic polypeptides (NPs) as potential useful markers in AF patients management.

EVIDENCE AND INFORMATION SOURCES

Pubmed was searched for natriuretic peptides and atrial fibrillation. Pertinent abstracts were reviewed by the Authors and the articles fully evaluated when considered pertinent.

STATE OF THE ART

NP biology and physiology is described and general application in heart failure outlined. With regard to AF, the role of NP as predictor of cardioversion is reviewed and discussed. Patients eligible for rhythm control not always respond to treatment. Classic markers for a suitable cardioversion, such an echocardiography, are not immediately available in most settings. NP might be a resource predicting cardioversion (or not) upon patient's presentation.

PROSPECTIVES

Biomarkers, such NPs, might be used to predict treatment response other than in heart failure.

CONCLUSIONS

In AF management, NT-ProBNP is a promising tool helping physicians to choose rhythm or rate control strategy.

B-type natriuretic peptide modulates the action potential and the L-type calcium current in adult rat heart muscle cells

Natriuretic peptides seem to be a potent regulator of cell Ca2+ signalling in their action on the cardiovascular system. It was therefore the aim of this study to investigate the effect(s) of B-type natriuretic peptide (BNP) on the action potential and the L-type calcium current (I(CaL)) in the rat left ventricular myocytes. Perforated and whole cell patch clamp technique was used to record action potential (AP) and I(CaL) in current and voltage clamp mode, respectively. At the concentration tested of 10(-7) M, BNP significantly increased the action potential duration at 50% and at 90% of repolarization by 16.85% and 1639% respectively, and the phase II slope of the AP by 52.5%; reduced the I(CaL) amplitude with a 16.17% decrease in the peak amplitude; reduced (16.51%) the inactivation time course of current decay; increased the V0.5 activation of the L-type calcium channel by 32.84% and decreased V0.5 inactivation by 34.39%. These data suggest that BNP modulates cardiomyocyte function by reducing I(CaL) and modifying the AP. This study may show a novel facet to evaluate the paracrine/autocrine effect of BNP on the normal heart function.

Brain natriuretic peptide mediates the effect of creatinine clearance on development of left ventricular systolic dysfunction in patients with acute coronary syndrome

INTRODUCTION

There are only limited data about the role of renal function in the development of left ventricular systolic dysfunction in patients with an acute coronary syndrome (ACS). We sought to investigate whether renal insufficiency is an independent predictor for systolic dysfunction among patients who had an ACS.

METHODS

During 2006-2007, 814 consecutive patients who presented with an ACS event were enrolled prospectively; of these, 284 men (65 ± 14 years) and 71 women (71 ± 12 years) developed left ventricular systolic dysfunction (ejection fraction <40%), 306 men (64 ± 12 years) and 78 women (67 ± 10 years) had preserved left ventricular systolic function (ejection fraction >50%), while the rest of the patients (n=75), with ejection fraction between 40-50%, were excluded from this analysis. Creatinine clearance rates were estimated by the Cockcroft-Gault formula.

RESULTS

Eight percent of patients presented with severe and 30% with moderate renal dysfunction. Multiple logistic regression analysis revealed that a 10-unit increase of creatinine clearance levels decreases the odds of developing left ventricular systolic dysfunction by 8% (95%CI per 1 unit: 0.986-0.998), after controlling for potential confounders. Moreover, brain natriuretic peptide levels were inversely correlated with creatinine clearance (r=-0.378, p<0.001). When brain natriuretic peptide was entered into the model, creatinine clearance was not associated with left ventricular systolic dysfunction (OR=0.997, 95%CI 0.989-1.005).

CONCLUSIONS

The role of renal insufficiency in the development of left ventricular systolic dysfunction seems to be partially explained by plasma brain natriuretic peptide levels, suggesting a potential pathophysiological mechanism. Thus, patients with impaired creatinine levels and elevated brain natriuretic peptide levels should receive more aggressive medical care, as they are prone to developing left ventricular systolic dysfunction.

Regulation and significance of atrial and brain natriuretic peptides as cardiac hormones

Atrial and brain natriuretic peptides (ANP and BNP, respectively) are cardiac hormones. During cardiac development, their expression is a maker of cardiomyocyte differentiation and is under tight spatiotemporal regulation. After birth, however, their ventricular expression is only up-regulated in response to various cardiovascular diseases. As a result, analysis of ANP and BNP gene expression has led to discoveries of transcriptional regulators and signaling pathways involved in both cardiac differentiation and cardiac disease. Studies using genetically engineered mice have shed light on the molecular mechanisms regulating ANP and BNP gene expression, as well as the physiological and pathophysiological relevance of the cardiac natriuretic peptide system. In this review we will summarize what is currently known about their regulation and the significance of ANP and BNP as hormones derived from the heart.

[Biomarkers in heart failure: BNP and NT-proBNP]

Used as biomarkers of heart failure (HF), BNP and NT-proBNP may be considered as the 'fatal finish line' for all cardiovascular disorders. The incidence of heart failure has increased steadily over the past several decades. High readmission rates for patients with acute decompensated heart failure have led to a search for biomarkers able to predict future clinical outcomes that would facilitate HF patient monitoring and help guide therapy. Molecular biomarkers play an important role in heart failure. From among several promising markers, the family of natriuretic peptides, especially B-type natriuretic peptide (BNP) and NT-proBNP, have been identified as potentially valuable diagnostic and prognostic tools. Not unexpectedly, BNP/NT-proBNP fails to fulfill all the criteria of an ideal biomarker. The development of additional biomarkers will be an important step toward improving diagnosis and treatment of patients with chronic and acute decompensated heart failure.

[NT-proBNP in practice: from chemistry to medicine]

Since the introduction of routine assay for natriuretic peptides, there are a growing number of clinical applications for those new tests. Numerous studies have defined analytical characteristics and clinical interest of NT-proBNP assay. Originally limited to acute heart failure diagnosis in the emergency room, NT-proBNP assay has now a wide number of applications. This literature review presents the "state of art" of this marker, detailing NT-proBNP physiological recent knowledge and its recognized or investigated clinical applications.

Endogenous B-type natriuretic peptide: a limb of the regulatory response to acutely decompensated heart failure

Acutely decompensated heart failure (ADHF) represents an episodic failure of cardiorenal homeostasis that may resolve with upregulation of natriuretic peptides, bradykinin, and certain prostacyclins. B-type natriuretic peptide (BNP) has multiple favorable effects, including vasodilation, diuresis, natriuresis, and inhibition of vascular endothelial proliferation and cardiac fibrosis. By antagonizing the effects of activation of the renin-angiotensin-aldosterone system (RAAS) and the sympathetic nervous system in volume overload, the endogenous BNP response may help rescue patients from episodic ADHF. Although knowledge of BNP physiology is expanding, we still have limited understanding of the heterogeneity of proBNP-derived molecules, including active 32 amino acid BNP and less active junk BNP forms. Emerging evidence suggests that in ADHF, the endogenous BNP response is overwhelmed by neurohormonal activation. This relative BNP deficiency may also be accompanied by physiologic resistance to BNP. Additionally, abnormalities of BNP production may result in a lower proportion of active BNP relative to less active forms that may also be detected by point-of-care tests. Improved detection of the various BNP species may clarify these concepts and facilitate improved clinical management of ADHF.

Inflammatory pathways in patients with heart failure and preserved ejection fraction

Immune activation is well established in patients with chronic heart failure and reduced ejection fraction (HF and reduced EF) and is associated with an impaired prognosis. Patients with heart failure and preserved ejection fraction (HF and preserved EF) have an impaired prognosis as well. It is not known whether they have signs of immune activation.

METHODS

We studied patients with HF and preserved EF (n=17, NYHA II [n=7]/III [n=10]) and patients with HF and reduced EF (n=17 NYHA II [n=1]/III [n=16]) and 20 controls. Echocardiography demonstrated preserved ejection fraction (LVEF 59+/-9%), but LV hypertrophy in patients with preserved EF as compared with patients with reduced EF (LVEF 23+/-5%). We evaluated levels of TNFalpha, its receptors (sTNFR-1 and 2), IL-6, IL-10 and NT-proBNP.

RESULTS

TNFalpha, was highest in HF with reduced EF (2.87+/-0.65 vs 1.67+/-0.58 pg/mL, p<0.001) compared to preserved EF and similar between HF with preserved EF and controls. However, sTNFR1 (1618+/-384 vs 1017+/-302 pg/mL, p<0.001) and sTNFR2 levels (3554+/-916 vs 2041+/-586 pg/mL, p<0.001) in HF with preserved EF were significantly higher compared with controls. The same was true for IL-6, IL-10 and NT-proBNP. The highest cytokine and NT-proBNP levels were present in HF with reduced EF. There was a negative correlation between TNFalpha, and LVEF (r=- 0.700; p<0.0001) and positive correlations between sTNFR1 and 2 with NT-proBNP.

CONCLUSION

Patients with HF and preserved EF already show signs of systemic-immune activation which may contribute to the impaired prognosis and the progression to HF with reduced EF.

Regulation and function of cyclic GMP-mediated pathways in glial cells

A large body of evidence supports a role for the NO-cGMP-protein kinase G pathway in the regulation of synaptic transmission and plasticity, brain development and neuroprotection. Circumstantial evidence implicates natriuretic peptide-stimulated cGMP formation in the same CNS functions. In addition to neurons, both cGMP-mediated pathways are functional in glial cells and an increasing number of reports indicate that they may control important aspects of glial cell physiology relevant to neuronal function. In this article we briefly review the regulation of cGMP formation in glial cells and summarize recent evidence indicating that cGMP-mediated pathways can play important roles in astroglial and microglial function in normal and diseased brain.

[Natriuretic peptides--their receptors and role in cardiovascular system]

Natriuretic peptides belong to a family of small proteins that play a major role in modulation of natriuresis, diuresis and vasodilatation. They counteract the activity of renin-angiotensin-aldosterone system. They are also involved in the regulation of homeostasis, fat metabolism and long bone growth. Natriuretic peptides family in mammals consists of three main members: atrial natriuretic peptide (ANP) - secreted by the atrial myocardium; brain natriuretic peptide (BNP)--secreted mainly by the ventricular myocardium, and C-type natriuretic peptide (CNP)--produced and released by endothelial cells. Secretion of these peptides is stimulated by atrial and ventricular distension, increased blood pressure, hypoxia or renal dysfunction. Natriuretic peptides play their roles via interactions with NPR-A and NPR-B receptors which are transmembrane guanylyl cyclases. Their local concentrations, regulated by internalization and degradation, are mediated by the NPR-C receptor and by neutral endopeptidase. The paper presents the current knowledge of structure and biological function of natriuretic peptides.

BNP and a renal patient: emphasis on the unique characteristics of B-type natriuretic peptide in end-stage kidney disease

BACKGROUND

The widespread use of brain natriuretic peptide testing among patients with end-stage kidney disease (ESKD) has brought new insight to prognostic cardiovascular factors in this population, but has also raised questions regarding the diagnostic potential of B-type natriuretic peptide (BNP) and NT-proBNP in subjects with renal impairment.

METHODS

Highlighting the most important recent observations in the field, this review discusses the unique characteristics of BNP testing and interpretation in chronic kidney disease.

RESULTS

We review in detail the physiology and effects of BNP along with providing a thoughtful analysis of the limitations of BNP testing in patients with impaired kidney function. Additionally, the practicability of BNP in the management of renal patients with some rational suggestions for the use of BNP are presented.

CONCLUSION

Although at present the use and interpretation of BNP testing in ESKD patients is complicated by altered renal clearance and frequent cardiac co-morbidity and, moreover, the complex and in many parts unknown interplay between the heart and the kidneys (cardiorenal syndrome), the prognostic value of elevated BNP is validated in the ESKD population. The importance of improving our understanding of the mechanisms of biomarkers in heart-kidney interdependence is emphasized.

[The role of natriuretic peptides in heart failure]

Over the last decades, there has been a significant increase in incidence and prevalence of heart failure, a major cause of cardiac morbidity and mortality. Measurements of neurohormones, in particular B-type natriuretic peptide (BNP), can significantly improve diagnostic accuracy, and also correlate with long-term morbidity and mortality in patients with chronic heart failure presenting to the emergency department. BNP is secreted by cardiac ventricles mainly in response to wall stress and neurohormonal factors like the sympathetic nervous system, endothelins, and the rennin-angiotensin-aldosterone system. BNP increases myocardial relaxation and oppose the vasoconstrictive, sodium retaining, and natriuretic effects caused by vasoconstrictive factors. BNP is the first biomarker to prove its clinical value for the diagnosis of left ventricular systolic and diastolic dysfunction but also for the right ventricular dysfunction, guiding prognosis and therapy management. Emerging clinical data will help further refine biomarker-guided therapeutic and monitoring strategies involving BNP.

Acute changes in N-terminal pro-brain natriuretic peptide induced by dobutamine stress echocardiography

AIMS

Aim of the study was to determine the effect of dobutamine stress echocardiography (DSE)-induced ischemia on circulating levels of N-terminal fragment of B-type natriuretic peptide (NT-pro-BNP).

METHODS AND RESULTS

One hundred and twenty-eight patients underwent DSE for the evaluation of known or suspected coronary artery disease. NT-pro-BNP levels were measured before and 1h after completion of DSE. NT-pro-BNP levels were similar before and after DSE regardless of whether patients had (123+/-101.8 vs. 124.2+/-108.3, p=NS) or did not have inducible ischemia (96.5+/-70.5 vs. 100.5+/-71.1, p=NS). Patients with inducible myocardial ischemia had no different NT-pro-BNP levels compared to patients without inducible ischemia both before (123+/-101.8 vs. 96.5+/-70pg/ml, p=0.37) and after DSE (124.2+/-108.3 vs. 100.5+/-71.1pg/ml, p=0.55). Patients with severe inducible ischemia had significantly higher NT-pro-BNP levels compared to patients with mild or moderate inducible ischemia and patients without inducible ischemia, both before (208.5+/-125.5 vs. 96+/-78.9 vs. 96.5+/-70pg/ml, p=0.017 and p=0.025, respectively) and after DSE (212.5+/-138.1 vs. 94.8+/-81.1 vs. 100.5+/-71.1pg/ml, p=0.015 and p=0.023, respectively). NT-pro-BNP levels before DSE could be independently predicted by age (p<0.0001), presence of diabetes mellitus (p=0.002), and ejection fraction (p=0.005), but not DSE inducible ischemia.

CONCLUSION

NT-pro-BNP is not affected by DSE-induced ischemia and cannot be used in clinical practice to improve diagnostic accuracy of DSE.

B-type natriuretic peptide monitoring in the Pediatric ICU population

The natriuretic peptide system plays an active role in the regulation of fluid balance and systemic vascular resistance. Assays of these peptides are now available and may be used for both diagnostic and prognostic purposes. Despite its primary use in adults, it may have a diagnostic role in the Pediatric ICU as well. The basic physiology of the natriuretic system is discussed and the potential applications of B-type natriuretic peptide (BNP) monitoring as a diagnostic tool in various clinical scenarios in infants and children in the Pediatric ICU setting is reviewed.

Brain natriuretic peptide: clinical and research challenges

Natriuretic peptides, in particular, brain or B-type, are useful for the assessment of patients presenting with dyspnea to the medical office or emergency department. Levels of natriuretic peptides are useful for assessing prognosis of heart failure or coronary syndrome patients. Less is known about serial peptide measurements for guiding treatment strategies in heart failure. The authors review the uses, pitfalls, and practical points for using natriuretic peptides clinically.

[Natriuretic peptides: their role in diagnosis and therapy]

Cardiac natriuretic peptide hormones, atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP), are synthesized and secreted by the heart, producing several biological effects, such as natriuresis, vasorelaxation and hypotension. During the last decade these peptides, especially BNP, have received increasing attention as potential markers of cardiovascular disease. Their measurements can be used to diagnose heart failure, including diastolic dysfunction, and using them has been shown to save money. BNP levels can enable the differentiation between dyspnoic patients secondary to ventricular dysfunction and subjects with primary respiratory disorders. Moreover, there is good evidence that natriuretic peptides may have a diagnostic role in arterial hypertension, acute coronary syndromes, pulmonary hypertension, some valvular heart disease and some disorders affecting other systems (diabetes or thyroid disorders). In this paper we discuss the clinical utility of assessment of natriuretic peptide hormones in the diagnosis of various clinical conditions and their use as pharmacological agents.

Are B-type natriuretic peptide (BNP) and N-terminal-pro-BNP useful in neonates?

B-type natriuretic peptide (BNP) and N-terminal-pro-BNP (NTpBNP) have a major role in screening and diagnosis of cardiac disease and monitoring of the treatment response in children and adults. This review discusses the evidence underpinning the potential benefits of these natriuretic peptides in neonatology. They may serve as a useful adjunct to echocardiography in the diagnosis of patent ductus arteriosus and its response to treatment and the diagnosis of persistent pulmonary hypertension of the newborn. However, more work is needed to explore the possible roles of BNP/NTpBNP in the management of sepsis and monitoring of cardiac performance in neonates.

Measuring risk in end-stage renal disease: is N-terminal pro brain natriuretic peptide a useful marker?

Natriuretic peptides are important in the maintenance of body volume homeostasis. There has been interest in utilizing the levels of these peptides to diagnose and prognosticate cardiovascular disease. In end-stage renal disease, the diagnostic utility of these peptides is limited. Madsen et al. report that levels of N-terminal pro brain natriuretic peptide (NT-proBNP) levels offer important information on the risk of mortality in patients undergoing hemodialysis.

Natriuretic peptides and heart transplant

Research into hormone secretion by the heart and the release of such hormones in detectable amounts in response to given clinical conditions has provided new perspectives full of hopes but also uncertainties. These hormones, called natriuretic peptides, have diuretic, natriuretic and vasodilating properties. In heart failure, a relationship between ventricular dysfunction and the levels of these peptides, with implications for morbidity and mortality, has been demonstrated. Less research has been carried out into heart transplant, and while increased levels of hormones are also observed when graft dysfunction occurs, their role in acute rejection or as an independent factor associated with prognosis has not been clarified.

Brain natriuretic peptide reverses the effects of myocardial stunning in rabbit myocardium

We tested the hypothesis that brain natriuretic peptide (BNP) would decrease the effects of myocardial stunning in rabbit hearts. We also examined the mechanisms responsible for these effects. In two groups of anesthetized open-chest rabbits, myocardial stunning was produced by 2 15-min occlusions of the left anterior descending artery separated by 15 min of reperfusion. The treatment group had BNP (10(-3) mol/l) topically applied to the stunned area. Hemodynamic and functional parameters were measured. Coronary flow and O2 extraction were used to determine myocardial O2 consumption. In separate animals, we measured the function of isolated control and simulated ischemia (95% N2/5% CO2, 15 min)-reperfusion ventricular myocytes with BNP or C-type natriuretic peptide (10(-8)-10(-7) mol/l) followed by KT5823 (10(-6) mol/l, cyclic GMP protein kinase inhibitor). In the in vivo control group, baseline delay to contraction was 47+/-4 ms and after stunning it increased to 71+/-10 ms. In the treatment group, baseline delay to contraction was 40+/-7 ms, and after stunning and BNP it did not significantly increase (43+/-6 ms). Neither stunning nor BNP administration affected regional O2 consumption. In control myocytes, BNP (10(-7) mol/l) decreased the percent shortening from 6.7+/-0.4 to 4.5+/-0.2%; after KT5823 administration, the percent shortening increased to 5.4+/-0.5%. In ischemia-reperfusion myocytes, BNP (10(-7) mol/l) decreased the percent shortening less from 5.0+/-0.5 to 3.8+/-0.2%; KT5823 administration did not increase the percent shortening (3.8+/-0.2%). BNP similarly and significantly increased cyclic GMP levels in control and stunned myocytes. The data illustrated that BNP administration reversed the effects of stunning and its mechanism may be independent of the cyclic GMP protein kinase.

Acute decompensated heart failure: pathophysiology and treatment

Acute decompensated heart failure (ADHF) is an important milestone in the clinical course of heart failure (HF). It is an event associated with a significant deterioration in the prognosis of HF. Despite the progress that has been made in the development of new pharmacologic and nonpharmacologic therapy for HF, there is surprisingly limited advancement in the treatment of acute HF. There are currently no guidelines for the treatment of ADHF. This is a review of the current diagnostic evaluation and treatment of patients with ADHF.

Discovery of new cardiovascular hormones for the treatment of congestive heart failure

In 1628, Harvey first correctly described the heart as a pump. It was another 350 years before the heart was established as an endocrine gland that synthesized a family of peptide hormones that regulate blood volume and blood pressure. There are now five peptide hormones made in the heart which have been demonstrated to have beneficial effects in persons with congestive heart failure. One of these peptide hormones i.e. brain natriuretic peptide (BNP) is commercially available and has been widely used in the United States for the treatment of acute congestive heart failure under the name Nesiritide/Natrecor. Nesiritide has one serious side effect, i.e. it may worsen renal function in persons with acute decompensated cardiac failure. The best of these peptide hormones for the treatment of chronic heart failure is a cardiac hormone named vessel dilator which enhances sodium and water excretion 4- to 5-fold in persons with congestive heart failure but vessel dilator's biologic effects lasts six hours compared to less than 30 minutes for BNP, without the deleterious effects of BNP on renal function. This review will focus on six cardiac hormones' discovery, identification and comparison of their beneficial effects and side effects in humans with congestive heart failure.

N-terminal-pro-B-type natriuretic peptide in acute hyperthyroidism

OBJECTIVE

Serum N-terminal-pro-B-type natriuretic peptide (NT-proBNP) is elevated in systolic heart failure due to volume expansion and pressure overload. Recent data suggest a direct stimulatory effect of thyroid hormones on NT-proBNP synthesis. We examined the influence of acutely induced hyperthyroidism on serum levels of NT-proBNP.

DESIGN

Forty-three healthy women were evaluated before and after treatment with 60 mug triiodothyronine (T(3)) daily for 7 days in a noncontrolled study.

MAIN OUTCOME

Before treatment, NT-proBNP was independently and inversely associated with thyrotropin (TSH), (r = -0.34, p = 0.02). T(3) therapy induced an increase in free T(3) (3.3 times, p < 0.0001) and suppression of TSH ( p < 0.0001). Heart rate increased by 14% ( p < 0.0001); weight decreased 0.6 kg ( p < 0.0001). Median NT-proBNP increased from 53 to 66 pg/mL ( p < 0.0001). The increase in NT-proBNP levels was independently associated with increase in free T(3) ( p = 0.05) and with reduction in TSH ( p = 0.04), without any association to the changes in cardiac workload.

CONCLUSIONS

NT-proBNP is influenced by thyroid function among healthy women, as demonstrated by an inverse association between TSH and NT-proBNP. Induction of an acute hyperthyroid state resulted in an increase in NT-proBNP, which seems to reflect a direct action of T(3) on the NT-proBNP secretion rather than an effect of increased cardiac workload.

N-terminal pro brain natriuretic peptide predicts mortality in patients with end-stage renal disease in hemodialysis

Concentrations of N-terminal pro brain natriuretic peptide (NT-proBNP) increase in patients with heart failure and other cardiovascular (CV) diseases and are strong prognostic markers. In patients with end-stage renal disease (ESRD) in hemodialysis (HD), levels of NT-proBNP are almost always raised. In ESRD patients undergoing HD, we aimed at (i) identifying the factors that affect levels of NT-proBNP, (ii) determining the effect of HD on NT-proBNP, and (iii) determining the prognostic impact of NT-proBNP. A total of 109 patients underwent physical examination, electrocardiogram, and echocardiography. Serum NT-proBNP was measured before and after HD (Elecsys 2010). NT-proBNP levels were markedly elevated (pre-HD 4079 pg/ml, post-HD 2759 pg/ml, P<0.001). There was a strong inverse correlation between NT-proBNP and left ventricular ejection fraction (LVEF) (P=0.043), 24-h urine production (P=0.006), and K(t)/V (efficacy of dialysis) (P=0.016) and a positive correlation with left ventricular hypertrophy (LVH) (P=0.014). Patients with higher concentrations, both pre- and post-HD had an increased mortality rate compared to those with lower concentrations (P=0.007, P=0.002). We found age (P=0.009) and NT-proBNP (pre-HD P=0.007, post-HD P=0.001) predictive of death. Our findings demonstrate that CV disease in terms of LVH and reduced LVEF in addition to 24-h urine production and K(t)/V determine NT-proBNP levels. Post-HD levels of NT-proBNP were lower than pre-HD levels; both predictive of mortality.

[The role of brain natriuretic peptide in diagnosis of diastolic myocardial dysfunction in patients with predialysis chronic kidney disease]

Aim of the study was to elucidate possibility of the use of brain and atrial natriuretic peptide (BNP) as a diagnostic marker of diastolic dysfunction (DD) of the left ventricular myocardium in 37 patients with predialysis chronic kidney disease (CKD). We used data of echocardiography and Doppler echocardiography for detection of functional signs of DD and correlated with BNP levels. Patients with signs of DD (81.1%) had significantly higher BNP level than patients without these signs (214.3 +/- 12.3 and 60.6 +/- 17.7 pg/ml, respectively, p < 0.0001). Main parameters of DD correlated significantly with BNP level (r=0.51, p < 0.005) and were independently related to the level of the hormone according the data of multifactorial regression analysis (R2=0.76, p < 0.001). BNP concentration 100 pg/ml in predialysis patients with CKD appears to be not only diagnostic for DD, but also differential index of pseudonormal type of DD.

Brain natriuretic peptide: a potential indicator of cardiomyogenesis after autologous mesenchymal stem cell transplantation?

We observed in a pilot study that there was a transient elevation of brain natriuretic peptide (BNP) level shortly after the transplantation in the patient with ischemic heart failure, which is unexplainable by the simultaneous increase of the cardiac output and six-minute walk distance. Similar findings were observed in the phase I trial. We postulated on the basis of the finding of Fukuda in vitro that this transient elevation of BNP level against the improvement of cardiac function and exercise capacity might indicate cardiomyogenesis in patients after mesenchymal stem cell transplantation. Further study is warranted to verify the hypothesis.

Natriuretic peptides in the diagnosis and management of heart failure

The natriuretic peptides are a family of related hormones that play a crucial role in cardiovascular homeostasis. They have recently emerged as potentially important clinical markers in heart failure. Recent data have suggested an important role for these markers in establishing the diagnosis of heart failure in patients with unexplained dyspnea in both acute care and ambulatory settings. Other clinical uses of the natriuretic peptides, such as screening for asymptomatic ventricular dysfunction, establishing prognosis or guiding titration of drug therapy, are under investigation but have not yet sufficiently been validated for widespread clinical use.

Transgenic overexpression of brain natriuretic peptide prevents the progression of diabetic nephropathy in mice

AIMS/HYPOTHESIS

Brain natriuretic peptide (BNP) is a potent vasorelaxing and natriuretic peptide that is secreted from the heart and has cardioprotective properties. We have previously generated hypotensive transgenic mice (BNP-Tg mice) that overproduce BNP in the liver, which is released into the circulation. Using this animal model, we successfully demonstrated the amelioration of renal injury after renal ablation and in proliferative glomerulonephritis. Glomerular hyperfiltration is an early haemodynamic derangement, representing one of the key mechanisms of the pathogenesis of diabetic nephropathy. Based on the suggested involvement of increased endogenous natriuretic peptides, the aim of this study was to investigate their role in the development and progression of diabetic nephropathy.

MATERIALS AND METHODS

We evaluated the progression of renal injury and fibrogenesis in BNP-Tg mice with diabetes induced by streptozotocin. We also investigated the effect of BNP on high glucose-induced signalling abnormalities in mesangial cells.

RESULTS

After induction of diabetes, control mice exhibited progressively increased urinary albumin excretion with impaired renal function, whereas these changes were significantly ameliorated in BNP-Tg mice. Notably, diabetic BNP-Tg mice revealed minimal mesangial fibrogenesis with virtually no glomerular hypertrophy. Glomerular upregulation of extracellular signal-regulated kinase, TGF-beta and extracellular matrix proteins was also significantly inhibited in diabetic BNP-Tg mice. In cultured mesangial cells, activation of the above cascade under high glucose was abrogated by the addition of BNP.

CONCLUSIONS/INTERPRETATION

Chronic excess of BNP prevents glomerular injury in the setting of diabetes, suggesting that renoprotective effects of natriuretic peptides may be therapeutically applicable in preventing the progression of diabetic nephropathy.

B-type natriuretic peptide rapid assay: a diagnostic test for heart failure

Hospitals are constantly besieged with congestive heart failure admissions. Current studies show that the advent of the B-type natriuretic peptide (BNP) rapid assay as a quick and easy blood test is beneficial to nurses in confirming the diagnosis of heart failure. B-type natriuretic peptide is a neurohormone produced by the failing heart in response to increased volume and cardiac overload. The BNP rapid assay measures the presence of BNP levels present in the circulating bloodstream to confirm the diagnosis of congestive heart failure. It is a simple blood test that can be done at the bedside or at the clinic so it is a valid point-of-care modality. Elevated levels suggest severity of heart failure and possibility of sudden death. This article focuses on the description of the diagnostic performance of the BNP rapid assay, its clinical dimensions, and its implications to nursing practice and collaborative practice models.