Designer natriuretic peptides: a vision for the future of heart failure therapeutics

Despite recent pharmacological advances in heart failure therapy, mortality from acute decompensated heart failure remains high. Conventional therapies are often insufficient to address the complex interplay between structural, functional, neurohumoral, and renal mechanisms involved in the heart failure syndrome. The natriuretic peptide system, however, offers a unique pleiotropic strategy which could bridge this gap in heart failure therapy. Exogenous administration of native A-type and B-type natriuretic peptides has been met with both success and limitations, and despite the limitations, remains a worthwhile endeavor. Alternatively, synthetic modification to create "designer" chimeric peptides holds the possibility to extend both the application and therapeutic benefits possible with a natriuretic peptide based approach. Herein we describe the development of natriuretic peptide based heart failure therapies, including the design, rationale, and preliminary studies of the novel chimeric peptides CD-NP and CU-NP.     

Recent advances in natriuretic peptide research

The natriuretic peptides are a family of related hormones that play a crucial role in cardiovascular and renal homeostasis. They have recently emerged as potentially important clinical biomarkers in heart failure. Natriuretic peptides, particularly brain natriuretic peptide (BNP) and the inactive N-terminal fragment of BNP, NT-proBNP, that has an even greater half-life than BNP, are elevated in heart failure and therefore considered to be excellent predictors of disease outcome. Nesiritide, a recombinant human BNP, has been shown to provide symptomatic and haemodynamic improvement in acute decompensated heart failure, although recent reports have suggested an increased short-term risk of death with nesiritide use. This review article describes: the current use of BNP and its inactive precursor NT-proBNP in diagnosis, screening, prognosis and monitoring of therapy for congestive heart failure, the renoprotective actions of natriuretic peptides after renal failure and the controversy around the therapeutic use of the recombinant human BNP nesiritide.     

Natriuretic peptides - physiology, pathophysiology and clinical use in heart failure

The natriuretic peptides - atrial, brain and C-type - were discovered during the last twenty years. Their effects on cardiovascular, renal, cerebral and other tissues through guanylyl cyclase were uncovered. Over the past decade natriuretic peptides (NPs) became a very useful tool in the management of heart failure patients. Results of many clinical trials have shown that BNP and NT-proBNP are helpful for diagnosis of heart failure. They are also independent markers of prognosis not only in heart failure patients but also in patients with other cardiovascular diseases. Recently published data document the utility of NPs in guiding treatment of heart failure patients. In this article, we focus on basic biochemical and physiological characteristics of NPs as well as on their significance in management of heart failure patients. Some limitations and pitfalls of NPs levels interpretation in diagnosing heart failure are also discussed.     

利钠肽家族基因与心血管疾病研究新进展

利钠肽家族是一组由心肌细胞分泌的激素,主要包括A型、B型和C型利钠肽,具有相似的基因结构和生理学效应,可对心血管系统产生血压调节、抗心肌肥厚、抗心肌纤维化和抗心肌弛缓等保护作用。利钠肽受体A、B和C亦介导多种生理活性,调节心血管稳态。利钠肽受体A选择性结合A型、B型利钠肽。利钠肽受体B结合C型利钠肽。利钠肽受体C结合各型利钠肽,通过受体介导的内化和退化作用清除血液循环中利钠肽。对利钠肽家族及其受体基因单核甘酸多态性及功能研究显示,其与多种心血管疾病(房颤、高血压、心力衰竭等)的易感性相关。利钠肽家族及其受体基因缺失的转基因小鼠表现为心肌肥厚、心肌纤维化,与高血压、心肌病及心力衰竭的发生发展相关。各种导致心肌肥厚和缺血性损伤的刺激均参与利钠肽及其受体基因的表达调控。临床将脑钠肽作为左室功能障碍和心力衰竭失代偿的一个预测指标。静脉注射重组脑钠肽已经成为治疗急性心力衰竭的有效手段。深入了解利钠肽家族基因变异及其信号调控有助于探索心血管疾病的病理生理机制,为临床诊疗开辟新思路。     

利钠肽家族基因与心血管疾病研究新进展

利钠肽家族是一组由心肌细胞分泌的激素, 主要包括A型、B型和C型利钠肽, 具有相似的基因结构和生理学效应, 可对心血管系统产生血压调节、抗心肌肥厚、抗心肌纤维化和抗心肌弛缓等保护作用。利钠肽受体A、B和C亦介导多种生理活性, 调节心血管稳态。利钠肽受体A选择性结合A型、B型利钠肽。利钠肽受体B结合C型利钠肽。利钠肽受体C结合各型利钠肽, 通过受体介导的内化和退化作用清除血液循环中利钠肽。对利钠肽家族及其受体基因单核甘酸多态性及功能研究显示, 其与多种心血管疾病(房颤、高血压、心力衰竭等)的易感性相关。利钠肽家族及其受体基因缺失的转基因小鼠表现为心肌肥厚、心肌纤维化, 与高血压、心肌病及心力衰竭的发生发展相关。各种导致心肌肥厚和缺血性损伤的刺激均参与利钠肽及其受体基因的表达调控。临床将脑钠肽作为左室功能障碍和心力衰竭失代偿的一个预测指标。静脉注射重组脑钠肽已经成为治疗急性心力衰竭的有效手段。深入了解利钠肽家族基因变异及其信号调控有助于探索心血管疾病的病理生理机制, 为临床诊疗开辟新思路。     

Atrial natriuretic peptides in heart failure: pathophysiological significance, diagnostic and prognostic value

Neurohormonal activation in patients with heart failure is dominated by the deleterious long-term effects of activation of the sympathetic nervous system and the renin-angiotensin-aldosterone system. The natriuretic peptides, including brain natriuretic peptide (BNP) and atrial natriuretic peptide (ANP), are also upregulated in heart failure, and partially counteract these deleterious effects by promoting vasodilation, natriuresis, and diuresis. Although BNP has been established as an important biomarker in the diagnosis and prognosis of heart failure, growing evidence suggests that measurement of plasma ANP, specifically its metabolite mid-regional pro-ANP, has similar diagnostic and prognostic value. Furthermore, its measurement may provide incremental diagnostic value when BNP levels fall into "grey zone" levels and may be a more potent prognostic marker of mortality.     

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.     

利钠肽在急性心力衰竭预后评估及指导治疗中的作用

利钠肽(BNP与NT-proBNP)是预测急性心衰预后及评估急性心衰治疗效果可靠的指标.日常临床决策加用利钠肽检测提高了急性心衰高危患者的发现率,而这些患者往往需要加强追踪及强化治疗.现就利钠肽在评估急性心衰预后及指导心衰治疗中的价值作如下综述.     

Tailored therapy for heart failure: neurohormones

Plasma B type cardiac natriuretic peptides reflect cardiac structure and function and have proven roles in assisting in the diagnosis of acute heart failure. They are also powerful independent prognostic indicators across the full spectrum of cardiovascular disease. The efficacy of serial measurements of plasma B type peptides in guiding titration of therapy for chronic heart failure has been the subject of a number of randomized controlled trials. These are summarized in the following brief review. In the decade 2000-2010, 8 trials have been completed. Study design, the characteristics of the heart failure population studied, duration of follow-up, the exact end points recorded, and target peptide levels pursued all differ somewhat between trials. However, an overall consistency is emerging, supported by 2 metaanalyses. In aggregate, the existing trial data suggest that adjustment of treatment in chronic heart failure according to serial B type peptide measurements used in conjunction with established clinical methods is likely to reduce cardiac mortality and admissions with heart failure, at least in those patients aged under 75?years with impaired left ventricular systolic function.     

Peptides natriurétiques en biologie clinique: quelques applications particulières

Knowledge of the cardiac role played by natriuretic peptides is recent (BNP and NT pro-BNP). The plasma levels of these natriuretic peptides are well correlated with the severity of cardiac dysfunction (NYHA classification). We outline the interest of natriuretic peptides in several medical indications: blood diseases, oncology, diabetes, sport health and psychiatry. Natriuretic peptides could prove to be useful biomarkers in clinical practice for patients with suspected heart failure in these specific situations.     

Natriuretic peptides in cardiovascular diseases

The natriuretic peptide family comprises atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), C-type natriuretic peptide (CNP), dendroaspis natriuretic peptide (DNP), and urodilatin. The activities of natriuretic peptides and endothelins are strictly associated with each other. ANP and BNP inhibit endothelin-1 (ET-1) production. ET-1 stimulates natriuretic peptide synthesis. All natriuretic peptides are synthesized from polypeptide precursors. Changes in natriuretic peptides and endothelin release were observed in many cardiovascular diseases: e.g. chronic heart failure, left ventricular dysfunction and coronary artery disease.     

Pathophysiologic relevance of measuring the plasma levels of cardiac natriuretic peptide hormones in humans.

Cardiac natriuretic peptides (ANP, BNP, and biologically active peptides of the N-terminal proANP1-98) are differently regulated in their production/secretion patterns and clearance rates; consequently, the assay for these peptides may provide complementary (or even different) pathophysiological and/or clinical information. The assay for cardiac natriuretic peptides has been utilized in clinical conditions associated with expanded fluid volume. In particular, this assay can be useful in discriminating between normal subjects and patients in different stages of heart failure and can also be considered a prognostic indicator of long-term survival in patients with heart failure and/or after acute myocardial infarction. Non-competitive immunometric assays (such as two-site IRMAs), even if more expensive, seem to be preferable to RIAs for routinary assay of cardiac peptide hormones because they generally have a better degree of sensitivity, accuracy, and precision.     

The endocrine heart and natriuretic peptides: histochemistry, cell biology, and functional aspects of the renal urodilatin system

 This review focuses on some selected aspects of the endocrine heart and natriuretic peptides. The endocrine heart is composed of specific myoendocrine cells of the cardiac atria. The myoendocrine cells synthesize and secrete the natriuretic peptide hormones which exhibit natriuretic, diuretic, and vasorelaxant properties. Immunohistochemical analyses show that natriuretic peptides of the A-type and B-type are localized not only in the specific granules of these myoendocrine cells but also in many other organs including the brain, adrenal medulla, and kidney. Also, their receptors are detected in many organs showing the multiple functions of these regulatory peptides. Of the members of the natriuretic peptide family, ANP (ANP for atrial natriuretic peptide; also denominated cardiodilatin, CDD), brain natriuretic peptide (BNP), C-type natriuretic peptide (CNP), and the A-type, including its renal form, urodilatin, are emphasized in this review. Urodilatin is localized in the kidney, differentially processed, and secreted into the urine. The intrarenal synthesis and secretion is the basis for a paracrine system regulating water and sodium reabsorption at the level of the collecting duct. CDD/ANP-1-126, cleaved from a precursor of 126 amino acids in the heart to a 28-amino acid-containing circulating molecular form (CDD/ANP-99-126), and urodilatin (CDD/ANP-95-126) share similar biochemical features and biological functions, but urodilatin may be more involved in the regulation of body fluid volume and water–electrolyte excretion, while circulating CDD/ANP-99-126 is responsible for blood pressure regulation. The physiological and pharmacological properties of these peptides have great clinical impact, and as a consequence urodilatin is involved in drug development for the treatment of acute renal failure, cardiomyopathia, and acute asthma. Accepted: 8 July 1998     

Effects of natriuretic peptides on load and myocardial function in normal and heart failure dogs

The effects on myocardial function and loading conditions of clinically relevant doses of the natriuretic peptides (NP) have not been established. The actions of single doses (100 ng x kg(-1) x min(-1) iv over 30 min) of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP) were studied in conscious normal dogs and in dogs with pacing-induced heart failure. All three NP reduced end-diastolic pressure in normal dogs, and ANP and BNP reduced end-diastolic volume. In heart failure ANP and BNP reduced EDP, and ANP reduced EDV. Arterial elastance was unchanged in normal dogs and in dogs with heart failure. ANP increased end-systolic elastance (E(es)) in normal dogs, whereas BNP tended to increase E(es) (P = 0.06). In dogs with heart failure, no inotropic effect was seen. In normal dogs, all NP reduced the time constant of isovolumic relaxation (tau), and ANP and BNP reduced tau in dogs with heart failure. Increases in plasma cGMP in dogs with heart failure were blunted. The NP reduced preload and enhanced systolic and diastolic function in normal dogs. Effects of ANP and BNP on preload and diastolic function were maintained in heart failure. Lack of negative inotropic effects in heart failure supports the validity of the NP as therapeutic agents.     

Guanylyl cyclase / atrial natriuretic peptide receptor-A: role in the pathophysiology of cardiovascular regulation

Atrial natriuretic factor (ANF), also known as atrial natriuretic peptide (ANP), is an endogenous and potent hypotensive hormone that elicits natriuretic, diuretic, vasorelaxant, and anti-proliferative effects, which are important in the control of blood pressure and cardiovascular events. One principal locus involved in the regulatory action of ANP and brain natriuretic peptide (BNP) is guanylyl cyclase / natriuretic peptide receptor-A (GC-A/NPRA). Studies on ANP, BNP, and their receptor, GC-A/NPRA, have greatly increased our knowledge of the control of hypertension and cardiovascular disorders. Cellular, biochemical, and molecular studies have helped to delineate the receptor function and signaling mechanisms of NPRA. Gene-targeted and transgenic mouse models have advanced our understanding of the importance of ANP, BNP, and GC-A/NPRA in disease states at the molecular level. Importantly, ANP and BNP are used as critical markers of cardiac events; however, their therapeutic potentials for the diagnosis and treatment of hypertension, heart failure, and stroke have just begun to be realized. We are now just at the initial stage of molecular therapeutics and pharmacogenomic advancement of the natriuretic peptides. More investigations should be undertaken and ongoing ones be extended in this important field.     

Immunoreactive forms of natriuretic peptides in ovine brain: response to heart failure

In order to elucidate how brain natriuretic peptides (NPs) are affected by experimentally induced heart failure, we have measured the immunoreactive (IR) levels of the NP in extracts from 10 regions of ovine brain, including pituitary, and clarified their molecular forms using high performance liquid chromatography (HPLC). Using species-specific radioimmunoassay (RIA), atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP) and C-type natriuretic peptide (CNP) were all detected in extracts taken from control animals and sheep that had undergone rapid ventricular pacing for 7 days to induce heart failure. CNP was the most abundant NP as assessed by specific RIA, and the pituitary contained the highest IR levels for all three NP. Compared with control animals, the pituitary content of BNP in animals with heart failure was reduced by 40% (control, 0.26±0.02 pmol/g wet weight versus heart failure 0.16±0.01; P<0.01, n=7). No other significant changes were observed. The molecular forms of ANP and CNP in whole brain extracts as assessed by HPLC were proANP and CNP22, CNP53 and proCNP, respectively. BNP in pituitary extracts was assessed to be primarily proBNP with a minor component of mature BNP26.     

Intérêt du dosage des peptides natriurétiques en urgence dans la dyspnée aiguë

Acute dyspnea often leads to an emergency room visit. B-type natriuretic peptide (BNP) and its N-terminal fragment (NT-proBNP) are natriuretic peptide factors secreted by ventricular myocytes when pressure is exerted on the ventricular wall. BNP fights against the activation of the renin-angiotensin-aldosterone system, while NT-proBNP exhibits no activity in this regard. Elevated blood levels of these factors correlate with a variety of functional indices for left-sided heart failure. Several studies have demonstrated their usefulness as markers of left-sided heart failure, the main cause of acute dyspnea seen in emergency rooms. The diagnostic performance of BNP and NT-proBNP appears to be identical; it is, however, greater than that of the emergency room physician. BNP and NT-proBNP have high sensitivity and specificity in the diagnosis of acute heart failure. Briefly, when BNP is less than 100 pg/ml, heart failure is very unlikely (NT-proBNP <500 pg/ml); when it is greater than 400 pg/ml (NT-proBNP >2000 pg/ml); when it is greater than 400 pg/ml (NT-proBNP >2000 pg/ml), it is very likely. The early measurement of BNP in emergency room situations improves the care of patients presenting with acute dyspnea and makes it possible to reduce hospitalisation costs.     

Cardiovascular and renal effects of eel and rat atrial natriuretic peptide in rainbow trout,Salmo gairdneri

Summary The renal and in vitro vascular effects of atrial natriuretic peptides have been examined in seveal species of fish. However, comparatively few investigations have described the effects of these peptides on the cardiovascular system in vivo. In the present experiments the dorsal aorta and urinary bladder were cannulated and the effects of atrial natriuretic peptides from rat and eel were monitored in conscious trout during bolus injection or continuous atrial natriuretic peptide infusion. The results show that the initial pressor effect of atrial natriuretic peptides is independent of environmental salinity adaptation (fresh or seawater) and the chemical form of atrial natriuretic peptide injected, but it is affected by the rate of atrial natriuretic peptide administration. This pressor response, and the accompanying diuresis, are mediated through -adrenergic activation. Continuous infusion of either rat or eel atrial natriuretic peptide produces a steady fall in mean arterial blood pressure, which is temporally preceded by an increase in heart rate and a decrease in pulse pressure. Diuresis induced by atrial natriuretic peptides is only partially sustained during continuous infusion. Propranolol partially blocks the increase induced in heart rate by atrial natriuretic peptides, but does not affect either pulse pressure or mean arterial pressure. Propranolol significantly increases urine flow in saline-infused animals but has no apparent effect on animals subjected to infusions of atrial natriuretic peptides. These results indicate that there are multiple foci for the action of atrial natriuretic peptides in trout and that in many instances the effects of atrial natriuretic peptides are mediated through secondary effector systems.Abbreviations ANP atrial natriuretic peptide - bw body weight - PBS phosphate-buffered saline     

脑钠肽在慢性心功能不全诊治的临床观察

目的：评价脑钠肽在慢性心功能不全过程中的诊治效果,探讨其临床适用性。方法：选择从2012年3月至2013年3月于我院就诊的82例心功能不全患者作为实验组,另选择同期的80例健康体检者作为对照组,分析实验组和对照组人员的脑钠肽的浓度,以及实验组患者经过治疗后的脑钠肽浓度变化情况,所有人员同时给予超声心动并观察实验组血浆脑钠肽浓度与左室射血分数及心功能分级之间的关系。结果：实验组患者的血浆脑钠肽浓度明显高于对照组人员,差异有统计学意义（P〈0．05）;实验组患者治疗前后血浆脑钠肽浓度有明显改变,差异也有统计学意义（P〈0．05）;心功能和左室射血分数不同分级之间的血浆脑钠肽浓度也不同,各级差异有明显统计学意义（P〈0．05）;脑钠肽浓度的不同参考值测定的灵敏度和特异性也不同。结论：脑钠肽在慢性心功能不全的诊治过程中有重要价值,为临床心功能的判断可以提供较为敏感的指示,适合临床长期推广应用。