Natriuretic peptides in human heart: Novel insight into their molecular forms, functions, and diagnostic use

Evaluation of plasma atrial natriuretic peptide concentration in healthy bottlenose dolphins (Tursiops truncates)

There are currently no standard methods for diagnosing cardiac diseases in dolphins. These diseases may consequently be overlooked and go undiagnosed. The presence and severity of cardiac diseases in humans can be determined using blood tests. Atrial natriuretic peptide (ANP) used in human cardiac examinations has low species specificity. There have already been reports of homology between dolphin and human ANP; however, its potential for clinical application in dolphins has not been tested. This study was conducted to establish a reference for ANP levels in healthy bottlenose dolphins. Healthy bottlenose dolphins (seven females; estimated to be 7-30 years of age) at an aquarium in Japan were sampled. Each animal was tested for ANP at least three times, and the mean value and standard deviation were calculated to be 43.4 ± 19.2 pg/mL. In humans, patients with high plasma ANP levels have a poor prognosis. In veterinary medicine, cutoff values for the diagnosis of mitral regurgitation and heart failure in dogs have been established and used to predict prognosis. The results of the present study may contribute to the health management of bottlenose dolphins, particularly in the early detection and treatment of cardiac diseases.

Association of natriuretic peptides and receptor activity with cardio-metabolic health at middle age

Natriuretic peptides (NP) have multiple actions benefitting cardiovascular and metabolic health. Although many of these are mediated by Guanylyl Cyclase (GC) receptors NPR1 and NPR2, their role and relative importance in vivo is unclear. The intracellular mediator of NPR1 and NPR2, cGMP, circulates in plasma and can be used to examine relationships between receptor activity and tissue responses targeted by NPs. Plasma cGMP was measured in 348 participants previously recruited in a multidisciplinary community study (CHALICE) at age 50 years at a single centre. Associations between bio-active NPs and bio-inactive aminoterminal products with cGMP, and of cGMP with tissue response, were analysed using linear regression. Mediation of associations by NPs was assessed by Causal Mediation Analysis (CMA). ANP's contribution to cGMP far exceed those of other NPs. Modelling across three components (demographics, NPs and cardiovascular function) shows that ANP and CNP are independent and positive predictors of cGMP. Counter intuitively, findings from CMA imply that in specific tissues, NPR1 responds more to BNP stimulation than ANP. Collectively these findings align with longer tissue half-life of BNP, and direct further therapeutic interventions towards extending tissue activity of ANP and CNP.

N-terminal pro atrial natriuretic peptide as a prognostic marker of cardiac resynchronization therapy recipients

Background

Although the dynamic changes of atrial natriuretic peptide (ANP) expressions in a failing heart are well-documented, the clinical implications of detailed measurements of each ANP molecular form processed from proANP remain unclear.

Methods

Patients screening was conducted on patients who were eligible for cardiac resynchronization therapy (CRT) between 2014 and 2019 in our institution. Blood samples and echocardiographic parameters were collected on the day before and six months after implantation. Total ANP, proANP, and N-terminal fragment of proANP (NT-proANP) were examined as predictive biomarkers for cardiac death, left ventricular assist device implantation, and heart failure hospitalization following CRT implantation.

Results

A total of 86 subjects (mean age 70 years, 64 males) who underwent successful CRT implantation were enrolled. Plasma levels of total ANP, proANP, and NT-proANP were not normally distributed [25.8 pM (interquartile range: 11.1-53.1), 2.2 pM (1.0-5.4), and 4.1 nM (2.4-7.1), respectively]. Over a median follow-up of 2.7 years, 31 patients (2 deaths and 29 heart failure hospitalizations) reached the endpoints. Among the different ANP forms, only NT-proANP emerged as an independent predictor of the composite outcome (adjusted odds ratio of 2.542 in those with levels above vs. below the median, 95 % confidence interval 1.151-5.615, p = 0.021). NT-proANP levels were associated with left atrial volume and left diastolic functional parameters and decreased in response to echocardiographic improvements at six months post-implantation (16 ± 44 % decrease in responders vs 18 ± 60 % increase in non-responders, p = 0.005).

Conclusion

Pre-implantation NT-proANP levels could serve as a predictive factor for clinical outcomes in recipients of CRT.

Corin deficiency impairs cardiac function in mouse models of heart failure

Introduction

Corin is a protease in the natriuretic peptide system. Deleterious CORIN variants are associated with hypertension and heart disease. It remains unclear if and to what extent corin deficiency may contribute to heart failure (HF).

Methods

Corin knockout (KO) mice were used as a model. Cardiac function was assessed by echocardiography and tissue analysis in Corin KO mice at different ages or subjected to transverse aortic constriction (TAC), which increased pressure overload. Heart and lung tissues were analyzed for cardiac hypertrophy and lung edema using wheat germ agglutinin, Sirius red, Masson's trichrome, and Prussian blue staining. Recombinant corin was tested for its effect on cardiac function in the TAC-operated Corin KO mice. Selected gene expression in the heart was examined by RT-PCR. ELISA was used to analyze factors in plasma.

Results

Corin KO mice had progressive cardiac dysfunction with cardiac hypertrophy and fibrosis after 9 months of age, likely due to chronic hypertension. When Corin KO mice were subjected to TAC at 10-12 weeks of age, cardiac function decreased more rapidly than in similarly treated wild-type mice. When the TAC-operated Corin KO mice were treated with recombinant corin protein, cardiac dysfunction, hypertrophy, and fibrosis were ameliorated. The corin treatment also decreased the gene expression associated with cardiac hypertrophy and fibrosis, increased plasma cGMP levels, lowered plasma levels of N-terminal pro-atrial natriuretic peptide, angiotensin II, and aldosterone, and lessened lung edema in the Corin KO mice subjected to TAC.

Conclusion

Corin deficiency impairs cardiac function and exacerbates HF development in mice. Corin protein may be used to reduce cardiac hypertrophy and fibrosis, suppress the renin-angiotensin-aldosterone system, and improve cardiac function in HF.

The Natriuretic Peptide System: A Single Entity, Pleiotropic Effects

In the modern scientific landscape, natriuretic peptides are a complex and interesting network of molecules playing pleiotropic effects on many organs and tissues, ensuring the maintenance of homeostasis mainly in the cardiovascular system and regulating the water-salt balance. The characterization of their receptors, the understanding of the molecular mechanisms through which they exert their action, and the discovery of new peptides in the last period have made it possible to increasingly feature the physiological and pathophysiological role of the members of this family, also allowing to hypothesize the possible settings for using these molecules for therapeutic purposes. This literature review traces the history of the discovery and characterization of the key players among the natriuretic peptides, the scientific trials performed to ascertain their physiological role, and the applications of this knowledge in the clinical field, leaving a glimpse of new and exciting possibilities for their use in the treatment of diseases.

An update on utilising brain natriuretic peptide for risk stratification, monitoring and guiding therapy in heart failure

INTRODUCTION

Heart failure (HF) is a dominant health problem with an overall poor prognosis. Natriuretic peptides (NPs) are upregulated in HF as a compensatory mechanism. They have extensively been used for diagnosis and risk stratification.

AREAS COVERED

This review addresses the history and physiology of NPs in order to understand their current role in clinical practice. It further provides a detailed and updated narrative review on the utility of those biomarkers for risk stratification, monitoring, and guiding therapy in HF.

EXPERT OPINION

NPs show excellent predictive ability in heart failure patients, both in acute and chronic settings. Understanding their pathophysiology and their modifications in specific situations is key for an adequate interpretation in specific clinical scenarios in which their prognostic value may be weaker or less well evaluated. To better promote risk stratification in HF, NPs should be integrated with other predictive tools to develop multiparametric risk models. Both inequalities of access to NPs and evidence caveats and limitations will need to be addressed by future research in the coming years.

Endocrine functions of the heart: from bench to bedside

Heart has a recognized endocrine function as it produces several biologically active substances with hormonal properties. Among these hormones, the natriuretic peptide (NP) system has been extensively characterized and represents a prominent expression of the endocrine function of the heart. Over the years, knowledge about the mechanisms governing their synthesis, secretion, processing, and receptors interaction of NPs has been intensively investigated. Their main physiological endocrine and paracrine effects on cardiovascular and renal systems are mostly mediated through guanylate cyclase-A coupled receptors. The potential role of NPs in the pathophysiology of heart failure and particularly their counterbalancing action opposing the overactivation of renin-angiotensin-aldosterone and sympathetic nervous systems has been described. In addition, NPs are used today as key biomarkers in cardiovascular diseases with both diagnostic and prognostic significance. On these premises, multiple therapeutic strategies based on the biological properties of NPs have been attempted to develop new cardiovascular therapies. Apart from the introduction of the class of angiotensin receptor/neprilysin inhibitors in the current management of heart failure, novel promising molecules, including M-atrial natriuretic peptide (a novel atrial NP-based compound), have been tested for the treatment of human hypertension. The development of new drugs is currently underway, and we are probably only at the dawn of novel NPs-based therapeutic strategies. The present article also provides an updated overview of the regulation of NPs synthesis and secretion by microRNAs and epigenetics as well as interactions of cardiac hormones with other endocrine systems.

The Predictive Value of A, B, and C-Type Natriuretic Peptides in People at Risk of Heart Disease: Protocol for a Longitudinal Observational Study

BACKGROUND

Heart disease and stroke are major and often unheralded causes of serious morbidity and premature death in middle age. Early detection of those most at risk is an urgent unmet need for instituting preventative measures. In an earlier community study (Canterbury Health, Ageing and Life Course [CHALICE]) of healthy people aged 50 years, contrary to previous reports, low levels of the heart hormone B-type natriuretic peptide (BNP) were associated with reduced measures of heart function and higher markers of vascular risk. A specific gene variant (rs198358) was found to be an independent contributor to higher BNP levels. A closely related vascular hormone (C-type natriuretic peptide [CNP]) showed opposite associations-higher levels were correlated with higher vascular risk and reduced cardiac function. To determine whether these novel findings predict serious heart or vascular disease in later life, this proposal re-examines the same CHALICE participants 15 years later.

OBJECTIVE

The primary objective is to determine the predictive value of (1) low plasma concentrations of the circulating cardiac hormones (atrial natriuretic peptide [ANP] and BNP) and (2) high levels of the vascular hormone CNP at age 50 years in detecting impaired cardiac and vascular function 15 years later. Secondary objectives are to determine specific associations of individual analytes (ANP, BNP, CNP, cyclic guanosine monophosphate [cGMP]) with echo-derived changes in cardiac performance at ages 50 years and 65 years.

METHODS

All of the 348 participants (205/348, 58.9% female; 53/348, 15.2% Māori or Pacifica ethnicity) participating in the original CHALICE study-free of history of heart or renal disease at age 50 years and who consented to further study-will be contacted, recruited, and restudied as previously described. Data will include intervening health history, physical examination, heart function (speckle-tracking echocardiography), vascular status (carotid intimal thickness), and genetic status (genome-wide genotyping). Laboratory measures will include fasting blood sampling and routine biochemistry, ANP, BNP, CNP, their downstream effector (cGMP), and their bio-inactive products. Humoral metabolic-cardiovascular risk factors will be measured after an overnight fast. Primary outcomes will be analyzed using multiple linear regression.

RESULTS

The study will commence in 2022 and be completed in 2024.

CONCLUSIONS

Proving our hypothesis-that low BNP and high CNP at any age in healthy people predict premature aging of heart and blood vessels, respectively-opens the way to early detection and improved outcomes for those most at risk. Confirmation of our hypotheses would improve current methods of screening and, in appropriate cases, enable interventions aimed at increasing natriuretic hormones and reducing risk of serious cardiovascular complications using drugs already available. Such advances in detection, and from interventional corrections, have the potential to not only improve health in the community but also reduce the high costs inevitably associated with heart failure.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/37011.

Glucagon-like peptide-1 stimulates acute secretion of pro-atrial natriuretic peptide from the isolated, perfused pig lung exposed to warm ischemia

Glucagon-like peptide-1 (GLP-1) has proven to be protective in animal models of lung disease but the underlying mechanisms are unclear. Atrial natriuretic peptide (ANP) is mainly produced in the heart. As ANP possesses potent vaso- and bronchodilatory effects in pulmonary disease, we hypothesised that the protective functions of GLP-1 could involve potentiation of local ANP secretion from the lung. We examined whether the GLP-1 receptor agonist liraglutide was able to improve oxygenation in lungs exposed to 2 h of warm ischemia and if liraglutide stimulated ANP secretion from the lungs in the porcine ex vivo lung perfusion (EVLP) model. Pigs were given a bolus of 40 µg/kg liraglutide or saline 1 h prior to sacrifice. The lungs were then left in vivo for 2 h, removed en bloc and placed in the EVLP machinery. Lungs from the liraglutide treated group were further exposed to liraglutide in the perfusion buffer (1.125 mg). Main endpoints were oxygenation capacity, and plasma and perfusate concentrations of proANP and inflammatory markers. Lung oxygenation capacity, plasma concentrations of proANP or concentrations of inflammatory markers were not different between groups. ProANP secretion from the isolated perfused lungs were markedly higher in the liraglutide treated group (area under curve for the first 30 min in the liraglutide group: 635 ± 237 vs. 38 ± 38 pmol/L x min in the saline group) (p < 0.05). From these results, we concluded that liraglutide potentiated local ANP secretion from the lungs.

Zambrano-Rodríguez P. The Use of Peptides in Veterinary Serodiagnosis of Infectious Diseases: A Review

Peptides constitute an alternative and interesting option to develop treatments, vaccines, and diagnostic tools as they demonstrate their scope in several health aspects; as proof of this, commercial peptides for humans and animals are available on the market and used daily. This review aimed to know the role of peptides in the field of veterinary diagnosis, and include peptide-based enzyme-linked immunosorbent assay (pELISA), lateral flow devices, and peptide latex agglutination tests that have been developed to detect several pathogens including viruses and bacteria of health and production relevance in domestic animals. Studies in cattle, small ruminants, dogs, cats, poultry, horses, and even aquatic organisms were reviewed. Different studies showed good levels of sensitivity and specificity against their target, moreover, comparisons with commercial kits and official tests were performed which allowed appraising their performance. Chemical synthesis, recombinant DNA technology, and enzymatic synthesis were reviewed as well as their advantages and drawbacks. In addition, we discussed the intrinsic limitations such as the small size or affinity to polystyrene membrane and mention several strategies to overcome these problems. The use of peptides will increase in the coming years and their utility for diagnostic purposes in animals must be evaluated.

Renal Corin Is Essential for Normal Blood Pressure and Sodium Homeostasis

Atrial natriuretic peptide (ANP)-mediated natriuresis is known as a cardiac endocrine function in sodium and body fluid homeostasis. Corin is a protease essential for ANP activation. Here, we studied the role of renal corin in regulating salt excretion and blood pressure. We created corin conditional knockout (cKO), in which the Corin gene was selectively disrupted in the kidney (kcKO) or heart (hcKO). We examined the blood pressure, urinary Na⁺ and Cl⁻ excretion, and cardiac hypertrophy in wild-type, corin global KO, kcKO, and hcKO mice fed normal- and high-salt diets. We found that on a normal-salt diet (0.3% NaCl), corin kcKO and hcKO mice had increased blood pressure, indicating that both renal and cardiac corin is necessary for normal blood pressure in mice. On a high-salt diet (4% NaCl), reduced urinary Na⁺ and Cl⁻ excretion, increased body weight, salt-exacerbated hypertension, and cardiac hypertrophy were observed in corin kcKO mice. In contrast, impaired urinary Na⁺ and Cl⁻ excretion and salt-exacerbated hypertension were not observed in corin hcKO mice. These results indicated that renal corin function is important in enhancing natriuresis upon high salt intakes and that this function cannot be compensated by the cardiac corin function in mice.

Trending Cardiac Biomarkers During Pregnancy in Women With Cardiovascular Disease

BACKGROUND

Clinical utility of cardiac biomarker testing during pregnancy in women with preexisting cardiac disease is not well known. We studied the levels and temporal trends of NT-proBNP (N-terminal pro-B-type natriuretic peptide) and hs-cTnI (high-sensitivity cardiac troponin I) throughout pregnancy in women with preexisting cardiac disease and sought to assess the association between NT-proBNP and hs-cTnI and pregnancy outcomes.

METHODS

Three hundred seven pregnant women with preexisting cardiac disease were prospectively recruited. Mixed-effects linear regression analysis was used to compare the NT-proBNP and hs-cTnI levels between time periods and subgroups. Logistic regression analysis adjusted for maternal age and CARPREG II (Cardiac Disease in Pregnancy) risk score assessed the association between NT-proBNP levels and adverse events.

RESULTS

Geometric mean NT-proBNP (95% CI) was stable through pregnancy with a transient significant increase with labor and delivery (101.4 pg/mL [87.1-118.1], 90.2 pg/mL [78.5-103.6], 153.6 pg/mL [126.8-186.1], and 112.2 pg/mL [94.2-133.7] for first/second trimester, third trimester, labor/delivery and postpartum, respectively). We observed a statistically significant difference in the NT-proBNP between women with preserved versus decreased systemic ventricular function, structurally normal versus abnormal heart, modified World Health Organization class 1, 2 versus modified World Health Organization class 3, 4 and no congenital heart disease versus congenital heart disease. Compared to those without events, median (interquartile range) NT-proBNP levels were significantly higher in those who had heart failure (204 pg/mL [51-450] versus 55 pg/mL [31-97]; P=0.001) and preeclampsia (98 pg/mL [40-319] versus 55 pg/mL [31-99]; P=0.027). NT-proBNP, adjusted for age and CARPREG II risk score, was significantly associated with combined heart failure and preeclampsia (adjusted odds ratio, 2.14 [95% CI, 1.48-3.10] per log NT-proBNP increase; P<0.001). NT-proBNP <200 pg/mL had a specificity of 91% and negative predictive value of 95% in predicting combined heart failure and preeclampsia.

CONCLUSIONS

NT-proBNP remains steady over the course of pregnancy with a transient increase during labor and delivery with higher levels in subgroups of stable cardiac patients. NT-proBNP level of 200 pg/mL can be used in the diagnosis of heart failure/preeclampsia in the pregnant cardiac population.

Yi-Xin-Shu capsule ameliorates cardiac hypertrophy by regulating RB/HDAC1/GATA4 signaling pathway based on proteomic and mass spectrometry image analysis

BACKGROUND

Cardiac hypertrophy (CH) forms the main pathological basis of chronic heart failure (CHF). Mitigating and preventing CH is the key strategy for the treatment of ventricular remodeling in CHF. Yi-Xin-Shu capsule (YXS) has been commonly applied in the clinical treatment of CHF in Asian countries for several decades. However, the underlying mechanism of YXS has not been revealed yet.

PURPOSE

To assess the efficiency of YXS in CH and identify its potential therapeutic targets for the managing of CH.

METHOD

Ultrasonic cardiogram was used to evaluate the cardiac function of CH rats. Hematein Eosin (HE)-staining, Masson-staining and transmission electron microscope were used to measure the morphological changes, cardiac fibrosis degree and ultrastructure characteristics of cardiomyocytes, respectively. ELISA was used to detect the myocardial injury biomarkers. Then, the potential targets regulated by YXS were screened out via proteomic analysis and mass spectrometry image analysis. Finally, the targets were validated by real-time quantitative (RT-q) PCR, immunofluorescence, immunohistochemistry, and western-blotting methods.

RESULTS

YXS improved the cardiac function of CH rats and attenuated the injuries in morphology and subcellular structure of cardiomyocytes. A core protein-protein interaction network was established on differentially expressed proteins (DEP) using proteomics analysis. GATA binding protein 4 (GATA4) was identified as the key target regulated by YXS. The results of mass spectrometry image analysis indicated that the expressions of histone deacetylase 1 (HDAC1) and retinoblastoma (RB) could also be regulated by YXS. Further valuative experiments showed that YXS may attenuate CH by regulating the RB/HDAC1/GATA4 signaling pathway.

CONCLUSIONS

For the first time, this study discloses the precise mechanism investigation of the efficacy of YXS against CH. These data demonstrate that YXS may protect against CH by regulating the RB/HDAC1/GATA4 signaling pathway.

Brain Natriuretic Peptide (BNP) Affects Growth and Stress Tolerance of Representatives of the Human Microbiome, Micrococcus luteus C01 and Alcaligenes faecalis DOS7

Simple Summary

The body of an average person weighing 70 kg contains approximately 39 trillion bacterial cells, which densely inhabit the gastrointestinal tract, skin, mucous membranes, etc. Bacteria respond to the signaling molecules in the human body, regulate the expression of the necessary genes, and thus adapt to the physiology of the host. Signaling molecules include hormones, neurotransmitters, immune system molecules, as well as natriuretic peptides, which are involved in the regulation of the circulatory system, water and electrolyte metabolism, and adipose tissue metabolism. Brain natriuretic peptide (BNP) is secreted by the ventricles during congestion and signals heart failure. This study showed that the presence of BNP in the growth medium of human symbiont bacteria affects their growth characteristics, survival, and stress resistance, including antibiotic resistance. It was concluded that bacterial populations that develop in a healthy person at a BNP level of up to 250 pg/mL will be more stress resistant than in a person suffering from heart failure. Our findings are promising to be used both in clinical medical practice and in the production of bacterial preparations for cosmetology, agriculture, and waste management.

Abstract

Brain natriuretic peptide (BNP) is secreted by the ventricles of the heart during overload to signal heart failure. Slight bilateral skin itching induced by BNP has been associated with response activity of the skin microbiota. In this work, we studied the effect of 25–250,000 pg BNP/mL on the growth, long-term survival, and stress (H₂O₂, antibiotics, salinity, heat and pH shock) resistance of human symbiont bacteria: Gram-positive Micrococcus luteus C01 and Gram-negative Alcaligenes faecalis DOS7. The effect of BNP turned out to be dose-dependent. Up to 250 pg BNP/mL made bacteria more stress resistant. At 2500 pg BNP/mL (heart failure) the thermosensitivity of the bacteria increased. Almost all considered BNP concentrations increased the resistance of bacteria to the action of tetracycline and ciprofloxacin. Both bacteria survived 1.3–1.7 times better during long-term (up to 4 months) storage. Our findings are important both for clinical medical practice and for practical application in other areas. For example, BNP can be used to obtain stress-resistant bacteria, which is important in the collection of microorganisms, as well as for the production of bacterial preparations and probiotics for cosmetology, agriculture, and waste management.

CNP, the Third Natriuretic Peptide: Its Biology and Significance to the Cardiovascular System

Simple Summary

CNP is the third natriuretic peptide to be isolated and is widely expressed in the central nervous system, osteochondral system, and vascular system. The receptor that is mainly targeted by CNP is GC-B, which differs from GC-A, the receptor targeted by the other two natriuretic peptides, ANP and BNP. Consequently, the actions of CNP differ somewhat from those of ANP and BNP. Research into the actions of CNP has shown that CNP attenuates cardiac remodeling in animal models of cardiac hypertrophy, myocardial infarction, and myocarditis. Studies examining CNP/GC-B signaling showed that it contributes to the prevention of cardiac stiffness. Endogenous CNP, perhaps acting in part through CNP/NPR-C signaling, contributes to the regulation of vascular function and blood pressure. CNP regulates vascular remodeling and angiogenesis via CNP/GC-B/CGK signaling. CNP attenuates interstitial fibrosis and fibrosis-related gene expression in pressure overload and myocardial infarction models. The clinical application of CNP as a therapeutic agent for cardiovascular diseases is anticipated.

Abstract

The natriuretic peptide family consists of three biologically active peptides: ANP, BNP, and CNP. CNP is more widely expressed than the other two peptides, with significant levels in the central nervous system, osteochondral system, and vascular system. The receptor that is mainly targeted by CNP is GC-B, which differs from GC-A, the receptor targeted by ANP and BNP. Consequently, the actions of CNP differ somewhat from those of ANP and BNP. CNP knockout leads to severe dwarfism, and there has been important research into the role of CNP in the osteochondral system. As a result, a CNP analog is now available for clinical use in patients with achondroplasia. In the cardiovascular system, CNP and its downstream signaling are involved in the regulatory mechanisms underlying myocardial remodeling, cardiac function, vascular tone, angiogenesis, and fibrosis, among others. This review focuses on the roles of CNP in the cardiovascular system and considers its potential for clinical application in the treatment of cardiovascular diseases.

Corin: A Key Mediator in Sodium Homeostasis, Vascular Remodeling, and Heart Failure

Simple Summary

Atrial natriuretic peptide (ANP) is an important hormone that regulates many physiological and pathological processes, including electrolyte and body fluid balance, blood volume and pressure, cardiac channel activity and function, inflammatory response, lipid metabolism, and vascular remodeling. Corin is a transmembrane serine protease that activates ANP. Variants in the CORIN gene are associated with cardiovascular disease, including hypertension, cardiac hypertrophy, atrial fibrillation, heart failure, and preeclampsia. The current data indicate a key role of corin-mediated ANP production and signaling in the maintenance of cardiovascular homeostasis. In this review, we discuss the latest findings regarding the molecular and cellular mechanisms underlying the role of corin in sodium homeostasis, uterine spiral artery remodeling, and heart failure.

Abstract

Atrial natriuretic peptide (ANP) is a crucial element of the cardiac endocrine function that promotes natriuresis, diuresis, and vasodilation, thereby protecting normal blood pressure and cardiac function. Corin is a type II transmembrane serine protease that is highly expressed in the heart, where it converts the ANP precursor to mature ANP. Corin deficiency prevents ANP activation and causes hypertension and heart disease. In addition to the heart, corin is expressed in other tissues, including those of the kidney, skin, and uterus, where corin-mediated ANP production and signaling act locally to promote sodium excretion and vascular remodeling. These results indicate that corin and ANP function in many tissues via endocrine and autocrine mechanisms. In heart failure patients, impaired natriuretic peptide processing is a common pathological mechanism that contributes to sodium and body fluid retention. In this review, we discuss most recent findings regarding the role of corin in non-cardiac tissues, including the kidney and skin, in regulating sodium homeostasis and body fluid excretion. Moreover, we describe the molecular mechanisms underlying corin and ANP function in supporting orderly cellular events in uterine spiral artery remodeling. Finally, we assess the potential of corin-based approaches to enhance natriuretic peptide production and activity as a treatment of heart failure.

Targeted Genetic Reduction of Mutant Huntingtin Lessens Cardiac Pathology in the BACHD Mouse Model of Huntington's Disease

Individuals affected by Huntington's disease (HD) present with progressive degeneration that results in a wide range of symptoms, including cardiovascular (CV) dysfunction. The huntingtin gene (HTT) and its product are ubiquitously expressed, hence, the cardiomyopathy could also be driven by defects caused by its mutated form (mHTT) in the cardiomyocytes themselves. In the present study, we sought to determine the contribution of the mHTT expressed in the cardiomyocytes to CV symptoms. We utilized the BACHD mouse model, which exhibits many of the HD core symptoms, including CV dysfunction. This model allows the targeted genetic reduction of mHTT expression in the cardiomyocytes while maintaining the expression of the mHTT in the rest of the body. The BACHD line was crossed with a line of mice in which the expression of Cre recombinase is driven by the cardiac-specific alpha myosin-heavy chain (Myh6) promoter. The offspring of this cross (BMYO mice) exhibited a dramatic reduction in mHTT in the heart but not in the striatum. The BMYO mice were evaluated at 6 months old, as at this age, the BACHD line displays a strong CV phenotype. Echocardiogram measurements found improvement in the ejection fraction in the BMYO line compared to the BACHD, while hypertrophy was observed in both mutant lines. Next, we examined the expression of genes known to be upregulated during pathological cardiac hypertrophy. As measured by qPCR, the BMYO hearts exhibited significantly less expression of collagen1a as well as Gata4, and brain natriuretic peptide compared to the BACHD. Fibrosis in the hearts assessed by Masson's trichrome stain and the protein levels of fibronectin were reduced in the BMYO hearts compared to BACHD. Finally, we examined the performance of the mice on CV-sensitive motor tasks. Both the overall activity levels and grip strength were improved in the BMYO mice. Therefore, we conclude that the reduction of mHtt expression in the heart benefits CV function in the BACHD model, and suggest that cardiomyopathy should be considered in the treatment strategies for HD.

A new biomarker of cardiac resynchronization therapy response: cGMP to mature BNP ratio

BACKGROUND

Biomarkers that can predict cardiac resynchronization therapy (CRT) response have not yet been identified. The purpose of this study was to assess whether individual measurements of four brain/B-type natriuretic peptide (BNP) forms, coupled with cyclic guanosine monophosphate (cGMP) might contribute to the prediction of echocardiographic CRT responders.

METHODS

A BNP precursor (proBNP) and total BNP (= proBNP + mature BNP) were measured with newly developed kits, while an N-terminal fragment of proBNP (NT-proBNP) and cGMP were measured with commercial kits on the day before CRT implantation. Estimated mature BNP (emBNP = total BNP-proBNP), and the ratio of cGMP to each BNP form, as well as the concentrations of three other BNP forms, were prospectively investigated for their capability in predicting a response to CRT. A CRT responder was defined as an improvement in left ventricular ejection fraction >10% and/or a reduction in left ventricular end-systolic volume >15% at 6-month follow-up.

RESULTS

Out of 77 patients, 46 (60%) were categorized as CRT responders. Among the measurement parameters, only the highest quartile of the cGMP to emBNP ratio was an independent predictor of CRT responders (odds ratio 4.87, 95% confidence interval 1.25-18.89, p = 0.02). The cGMP to emBNP ratio was associated with the cumulative events of heart failure hospitalization within one year following CRT implantation (log-rank p = 0.029).

CONCLUSIONS

The cGMP to emBNP ratio could be utilized as a predictive biomarker of CRT responders. (Clinical Study on Responder Prediction in Cardiac Resynchronization Therapy Using Individual Molecular Measurement of Natriuretic Peptide: UMIN R000038927).

N-Terminal Pro-C-Type Natriuretic Peptide: The Novel Marker in Selected Disease Units

BACKGROUND

Amino-terminal pro C type natriuretic peptide (NT proCNP) is the N terminal fragment of the CNP precursor. NT proCNP occurs in an equimolar concentration with CNP in human plasma and is considered to be a marker of the extent of CNP biosynthesis. A recent study has shown associations between plasma NT proCNP and blood pressure; it is also an independent predictor of death and cardiac readmission in people with unstable angina. Beyond that, recent studies have focused on the applicability of assessing NT proCNP peptide levels in the diagnosis of diseases with different etiologies but the same denominator, i.e., inflammation.

METHODS

This study reviewed recent results on the usability of NT proCNP peptide levels in the diagnosis of diseases accompanied by statistical analysis of previously reported results.

RESULTS

The data obtained confirmed the applicability of the assessment of NT proCNP levels in biological fluids in diseases, such as Parkinson's disease, sepsis, meningitis, and asthenozoospermia.

CONCLUSION

The reported results demonstrated that NT-proCNP is helpful in a variety of diseases. Furthermore, changes in serum or CSF levels of NT-proCNP reflect only inflammatory states related to general inflammation. Local inflammation does not trigger an increase in NT proCNP level.

Piezo1 Mechanosensitive Ion Channel Mediates Stretch-Induced Nppb Expression in Adult Rat Cardiac Fibroblasts

In response to stretch, cardiac tissue produces natriuretic peptides, which have been suggested to have beneficial effects in heart failure patients. In the present study, we explored the mechanism of stretch-induced brain natriuretic peptide (Nppb) expression in cardiac fibroblasts. Primary adult rat cardiac fibroblasts subjected to 4 h or 24 h of cyclic stretch (10% 1 Hz) showed a 6.6-fold or 3.2-fold (p < 0.05) increased mRNA expression of Nppb, as well as induction of genes related to myofibroblast differentiation. Moreover, BNP protein secretion was upregulated 5.3-fold in stretched cardiac fibroblasts. Recombinant BNP inhibited TGFβ1-induced Acta2 expression. Nppb expression was >20-fold higher in cardiomyocytes than in cardiac fibroblasts, indicating that cardiac fibroblasts were not the main source of Nppb in the healthy heart. Yoda1, an agonist of the Piezo1 mechanosensitive ion channel, increased Nppb expression 2.1-fold (p < 0.05) and significantly induced other extracellular matrix (ECM) remodeling genes. Silencing of Piezo1 reduced the stretch-induced Nppb and Tgfb1 expression in cardiac fibroblasts. In conclusion, our study identifies Piezo1 as mediator of stretch-induced Nppb expression, as well as other remodeling genes, in cardiac fibroblasts.

Insulin Infusion Is Linked to Increased NPPC Expression in Muscle and Plasma C-type Natriuretic Peptide in Male Dogs

The purpose of this study was to assess insulin-stimulated gene expression in canine skeletal muscle with a particular focus on NPPC, the gene that encodes C-type natriuretic peptide, a key hormonal regulator of cardiometabolic function. Four conscious canines underwent hyperinsulinemic, euglycemic clamp studies. Skeletal muscle biopsy and arterial plasma samples were collected under basal and insulin-stimulated conditions. Bulk RNA sequencing of muscle tissue was performed to identify differentially expressed genes between these 2 steady-state conditions. Our results showed that NPPC was the most highly expressed gene in skeletal muscle in response to insulin infusion, rising 4-fold between basal and insulin-stimulated conditions. In support of our RNA sequencing data, we found that raising the plasma insulin concentration 15-fold above basal elicited a 2-fold (P = 0.0001) increase in arterial plasma concentrations of N-terminal prohormone C-type natriuretic peptide. Our data suggest that insulin may play a role in stimulating secretion of C-type natriuretic peptide by skeletal muscle. In this context, C-type natriuretic peptide may act in a paracrine manner to facilitate muscle–vascular bed crosstalk and potentiate insulin-mediated vasodilation. This could serve to enhance insulin and glucose delivery, particularly in the postprandial absorptive state.

Role of natriuretic peptides in the cardiovascular-adipose communication: a tale of two organs

Natriuretic peptides have long been known for their cardiovascular function. However, a growing body of evidence emphasizes the role of natriuretic peptides in the energy metabolism of several substrates in humans and animals, thus interrelating the heart, as an endocrine organ, with various insulin-sensitive tissues and organs such as adipose tissue, muscle skeletal, and liver. Adipose tissue dysfunction is associated with altered regulation of the natriuretic peptide system, also indicated as a natriuretic disability. Evidence points to a contribution of this natriuretic disability to the development of obesity, type 2 diabetes mellitus, and cardiometabolic complications; although the causal relationship is not fully understood at present. However, targeting the natriuretic peptide pathway may improve metabolic health in obesity and type 2 diabetes mellitus. This review will focus on the current literature on the metabolic functions of natriuretic peptides with emphasis on lipid metabolism and insulin sensitivity. Natriuretic peptide system alterations could be proposed as one of the linking mechanisms between adipose tissue dysfunction and cardiovascular disease.

PAM: diverse roles in neuroendocrine cells, cardiomyocytes, and green algae

Our understanding of the ways in which peptides are used for communication in the nervous and endocrine systems began with the identification of oxytocin, vasopressin, and insulin, each of which is stored in electron-dense granules, ready for release in response to an appropriate stimulus. For each of these peptides, entry of its newly synthesized precursor into the ER lumen is followed by transport through the secretory pathway, exposing the precursor to a sequence of environments and enzymes that produce the bioactive products stored in mature granules. A final step in the biosynthesis of many peptides is C-terminal amidation by peptidylglycine α-amidating monooxygenase (PAM), an ascorbate- and copper-dependent membrane enzyme that enters secretory granules along with its soluble substrates. Biochemical and cell biological studies elucidated the highly conserved mechanism for amidated peptide production and raised many questions about PAM trafficking and the effects of PAM on cytoskeletal organization and gene expression. Phylogenetic studies and the discovery of active PAM in the ciliary membranes of Chlamydomonas reinhardtii, a green alga lacking secretory granules, suggested that a PAM-like enzyme was present in the last eukaryotic common ancestor. While the catalytic features of human and C. reinhardtii PAM are strikingly similar, the trafficking of PAM in C. reinhardtii and neuroendocrine cells and secretion of its amidated products differ. A comparison of PAM function in neuroendocrine cells, atrial myocytes, and C. reinhardtii reveals multiple ways in which altered trafficking allows PAM to accomplish different tasks in different species and cell types.

Maternal plasma pro-atrial and C-type natriuretic peptide levels and their associations with cardiovascular and renal function in the second half of normal pregnancy: a longitudinal study

BACKGROUND

Physiological adaptation in pregnancy is characterized by remodeling of endocrine, cardiovascular and renal functions leading to fluid retention, volume expansion, altered cardiac loading conditions and hyperdynamic circulation. Natriuretic peptides have been used as biomarkers of cardiovascular function, but their associations with gestational age-related changes in maternal cardiac, endothelial and renal function have not been elucidated. The aim of this study was to establish longitudinal reference values for maternal plasma atrial natriuretic peptide (proANP) and C-type natriuretic peptide (CNP) and investigate their temporal association with cardiovascular and renal function in the second half of pregnancy.

METHODS

This study was a prospective longitudinal study of 53 low-risk pregnancies. Women were examined every 3-5 weeks during 22-40 weeks of gestation (252 observations). Fasting maternal blood samples were obtained to measure proANP, CNP, creatinine, cystatin C, uric acid, and fibrinogen levels. Cardiac function and systemic hemodynamics were assessed noninvasively by impedance cardiography (ICG) and vascular endothelial function by flow-mediated vasodilation of brachial artery (FMD).

RESULTS

The plasma proANP (R2adj = 0.79; P = 0.007), CNP (R2adj = 0.54; P = 0.005) decreased between 22 and 40 weeks. The creatinine (R2adj = 0.90; P < 0.001), cystatin C (R2adj = 0.93; P = < 0.001) and uric acid (R2adj = 0.83; P < 0.001) increased significantly, whereas the estimated glomerular filtration rate (R2adj = 0.93; P < 0.001) decreased with gestational age. The FMD did not change significantly but fibrinogen (R2adj = 0.79; P < 0.001) increased with advancing gestation. The maternal systemic vascular resistance index (R2adj = 0.50; P < 0.001) increased, stroke index (R2adj = 0.62; P < 0.001) decreased, whereas the cardiac index (R2adj = 0.62; P = 0.438) and thoracic fluid content (R2adj = 0.72; P = 0.132) did not change significantly with gestation. The proANP was associated with thoracic fluid content (R2adj = 0.74; P < 0.001) and fibrinogen (R2adj = 0.78; P = 0.034) but not with other variables of systemic hemodynamics, endothelial function, or renal function. The CNP was not associated significantly with parameters of cardiovascular or renal function.

CONCLUSION

Longitudinal reference values for maternal plasma proANP and CNP were established. These natriuretic peptides decreased slightly with advancing gestation, but they did not reflect the temporal physiological changes in maternal systemic hemodynamics, vascular endothelial function and renal function during the second half of pregnancy. The proANP correlated with the thoracic fluid content reflecting volume load in pregnancy.

Plasma volume contraction reduces atrial natriuretic peptide after four days of hypobaric hypoxia exposure

We investigated whether low arterial oxygen tension ([Formula: see text]) or hypoxia-induced plasma volume (PV) contraction, which reduces central blood volume (BV) and atrial distension, explain reduction in circulating atrial natriuretic peptide (ANP) after prolonged hypoxic exposure. Ten healthy males were exposed for 4 days to hypobaric hypoxia corresponding to an altitude of 3,500 m. PV changes were determined by carbon monoxide rebreathing. Venous plasma concentrations of midregional proANP (MR-proANP) were measured before and at the end of the exposure. At the latter time point, the measurement was repeated after 1) restoration of [Formula: see text] by breathing a hyperoxic gas mixture for 30 min and 2) restoration of BV by fluid infusion. Correspondingly, left ventricular end-diastolic volume (LVEDV), left atrial area (LAA), and right atrial area (RAA) were determined by ultrasound before exposure and both before and after fluid infusion at the end of the exposure. Hypoxic exposure reduced MR-proANP from 37.9 ± 18.5 to 24.5 ± 10.3 pmol/L (P = 0.034), LVEDV from 107.4 ± 33.5 to 91.6 ± 26.3 mL (P = 0.005), LAA from 15.8 ± 4.9 to 13.3 ± 4.2 cm² (P = 0.007), and RAA from 16.2 ± 3.1 to 14.3 ± 3.5 cm² (P = 0.001). Hyperoxic breathing did not affect MR-proANP (24.8 ± 12.3 pmol/L, P = 0.890). Conversely, fluid infusion restored LVEDV, LAA, and RAA to near-baseline values (108.0 ± 29.3 mL, 17.2 ± 5.7 cm², and 17.2 ± 3.1 cm², respectively, P > 0.05 vs. baseline) and increased MR-proANP to 29.5 ± 13.3 pmol/L (P = 0.010 vs. preinfusion and P = 0.182 vs. baseline). These findings support that ANP reduction in hypoxia is at least partially attributed to plasma volume contraction, whereas reduced [Formula: see text] does not seem to contribute.

Significance of Atrial and Brain Natriuretic Peptide Measurements in Fetuses With Heart Failure

Fetal heart failure is mainly caused by congenital heart defect and arrhythmia. It is difficult to appropriately diagnose the severity of fetal heart failure simply by ultrasonography because the development of a fetal heart in fetoplacental circulation and how well the fetal myocardium can adapt to postnatal cardiopulmonary circulation are challenging to assess. In adult cardiology, natriuretic peptides (NPs) are the most useful biomarker of heart failure; however, studies investigating NP levels in the fetuses and amniotic fluid are quite limited. Furthermore, little is known about their production and metabolism. This review summarized the most relevant findings on NP levels in the umbilical cord blood and amniotic fluid. The findings can then extend their use as a diagnostic biomarker of heart failure in fetuses with congenital heart defect and/or arrhythmia.

Comparison of the prognosis and outcome of heart failure with reduced ejection fraction patients treated with sacubitril/valsartan according to age

The treatment with sacubitril/valsartan in patients suffering from chronic heart failure with reduced ejection fraction increases left ventricular ejection fraction and decreases the risk of sudden cardiac death. We conducted a retrospective analysis regarding the impact of age differences on the treatment outcome of sacubitril/valsartan in patients with chronic heart failure with reduced ejection fraction. Patients were defined as adults if ≤65 years (n = 51) and older if >65 years of age (n = 76). The incidence of ventricular arrhythmias at 1-year follow-up was comparable in both groups (30.8 vs 26.5%; p = 0.71). The mortality rate in adult patients is significantly lower as compared with older patients (2 vs 14.5%; log-rank = 0.04). Older patients may suffer remarkably more side effects than adult patients (21.1 vs 11.8%; p = 0.03).

Usefulness of cardiac hormones for evaluating valvular disease in cynomolgus monkeys (Macaca fascicularis)

Nonhuman primates are commonly used as experimental animals due to their biological resemblance to humans. In patients with cardiac disease, the levels of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) tend to increase in response to cardiac damage, and they are thus used as indicators for the diagnosis of human heart failure. However, no reference values for ANP and BNP have been reported for heart disease in nonhuman primates. In this study, we recorded the age, sex, and body weight of 202 cynomolgus monkeys, and performed evaluations to assess the ANP and BNP levels, electrocardiography and echocardiography, and accordingly divided the monkeys into two groups: healthy monkeys and those with spontaneous cardiac disease. Statistical analysis was performed to determine the relationship of ANP and BNP with the factors of age, sex, and body weight. No significant relationship was found between the levels of ANP and BNP and the factors of age, sex, and body weight. However, both the ANP and BNP levels were significantly different between the healthy monkeys and monkeys with valvular disease. Similar to humans, the ANP and BNP levels tended to increase with the progression of cardiac disease in monkeys. Based on these results, we concluded that ANP and BNP are indicators of cardiac disease in nonhuman primates, and that this nonhuman primate cardiac disease model is applicable for cardiology research in humans.

Involvement of the BNP/NPR-A/BKCa pathway in rat trigeminal ganglia following chronic constriction injury

Accumulating evidence indicates that the brain natriuretic peptide (BNP) and its receptor (natriuretic peptide receptor, NPR) are widely distributed in a variety of tissues including trigeminal ganglion (TG). Furthermore, recent studies support the involvement of the BNP-NPR-A pathway in acute and chronic pain. To investigate the role of this pathway in chronic pain, an infraorbital nerve-chronic constriction injury (ION-CCI) model of trigeminal neuralgia (TN) was produced in the rat. The time course of changes in mechanical pain threshold was examined. We observed an upregulation of BNP and NPR-A and a downregulation of large-conductance Ca²⁺-activated K⁺ (BKCa) mRNA and protein in rats subjected to ION-CCI. Patch clamping experiments in vitro found that BKCa currents were significantly reduced in rats subjected to ION-CCI. BNP increased BKCa currents in ION-CCI rats. These results suggest that BNP and NPR-A might serve as endogenous pain relievers in ION-CCI rats. Modulation of the BNP/NPR-A/BKCa channel pathway in TG may be a viable strategy for the treatment of TN.NEW & NOTEWORTHY BNP has been known to activate its receptor, NPR-A, to modulate inflammatory pain. However, the potential modulatory roles of BNP in TN have not been investigated in detail. We established an ION-CCI model of TN in the rat and observed an upregulation of BNP and NPR-A and a downregulation of BKCa in rats subjected to ION-CCI. Moreover, BNP can increase BKCa currents in ION-CCI rats. Thus, BNP and NPR-A might have inhibitory effects on trigeminal neuralgia through activating the BNP/NPR-A/BKCa channel pathway.

Cholecystokinin peptide signaling is regulated by a TBX5-MEF2 axis in the heart

The procholecystokinin (proCCK) gene encodes a secreted peptide known to regulate the digestive, endocrine, and nervous systems. Though recently proposed as a biomarker for heart dysfunction, its physiological role in both the embryonic and adult heart is poorly understood, and there are no reports of tissue-specific regulators of cholecystokinin signaling in the heart or other tissues. In the present study, mRNA of proCCK was observed in cardiac tissues during mouse embryonic development, establishing proCCK as an early marker of differentiated cardiomyocytes which is later restricted to anatomical subdomains of the neonatal heart. Three-dimensional analysis of the expression of proCCK and CCKAR/CCKBR receptors was performed using in situ hybridization and optical projection tomography, illustrating chamber-specific expression patterns in the postnatal heart. Transcription factor motif analyses indicated developmental cardiac transcription factors TBX5 and MEF2C as upstream regulators of proCCK, and this regulatory activity was confirmed in reporter gene assays. proCCK mRNA levels were also measured in the infarcted heart and in response to cyclic mechanical stretch and endothelin-1, indicating dynamic transcriptional regulation which might be leveraged for improved biomarker development. Functional analyses of exogenous cholecystokinin octapeptide (CCK-8) administration were performed in differentiating mouse embryonic stem cells (mESCs), and the results suggest that CCK-8 does not act as a differentiation modulator of cardiomyocyte subtypes. Collectively, these findings indicate that proCCK is regulated at the transcriptional level by TBX5-MEF2 and neurohormonal signaling, informing use of proCCK as a biomarker and future strategies for upstream manipulation of cholecystokinin signaling in the heart and other tissues.

Evaluation of Enhanced Lipid Oxidation and Compensatory Suppression using Natriuretic Peptide in Patients with Cardiovascular Diseases

Malondialdehyde-modified low-density lipoprotein (MDA-LDL) is recognized as a surrogate marker of lipid oxidation and is associated with arteriosclerosis. However, there are limited reports on the relationship between heart failure and MDA-LDL. Therefore, we aimed to determine whether MDA-LDL is activated in patients with left ventricular (LV) dysfunction and examine our hypothesis that the B-type natriuretic peptide (BNP) masks the enhancement of MDA-LDL in patients with LV dysfunction by its strong antioxidative action. The study population comprised 2,976 patients with various cardiovascular diseases. Patients were divided into four groups depending on the LV ejection fraction (LVEF) or plasma BNP level. A nonparametric analysis with the Kruskal-Wallis test was used to perform an interquartile comparison. In addition, structural equation modeling and Bayesian estimation were used to compare the effects of LVEF and BNP on MDA-LDL. MDA-LDL levels did not significantly change (P > 0.05) with respect to the degree of LVEF among the four groups. In contrast, MDA-LDL levels were significantly decreased (P < 0.001) with respect to the degree of BNP among the four groups. A path model based on structural equation modeling clearly showed a significant effect of LVEF (standardized regression coefficient; β: -0.107, P < 0.001) and BNP (β: -0.114, P < 0.001) on MDA-LDL, with a significant inverse association between LVEF and BNP (correlation coefficient -0.436, P < 0.001). MDA-LDL should be activated in patients with LV dysfunction; however, BNP is thought to exert a strong compensatory suppression on lipid oxidation, masking the relationship between heart failure and lipid oxidation.

Modern trends in diuretics development

Diuretics are the first-line therapy for widespread cardiovascular and non-cardiovascular diseases. Traditional diuretics are commonly prescribed for treatment in patients with hypertension, edema and heart failure, as well as with a number of kidney problems. They are diseases with high mortality, and the number of patients suffering from heart and kidney diseases is increasing year by year. The use of several classes of diuretics currently available for clinical use exhibits an overall favorable risk/benefit balance. However, they are not devoid of side effects. Hence, pharmaceutical researchers have been making efforts to develop new drugs with a better pharmacological profile. High-throughput screening, progress in protein structure analysis and modern methods of chemical modification have opened good possibilities for identification of new promising agents for preclinical and clinical testing. In this review, we provide an overview of the medicinal chemistry approaches toward the development of small molecule compounds showing diuretic activity that have been discovered over the past decade and are interesting drug candidates. We have discussed promising natriuretics/aquaretics/osmotic diuretics from such classes as: vasopressin receptor antagonists, SGLT2 inhibitors, urea transporters inhibitors, aquaporin antagonists, adenosine receptor antagonists, natriuretic peptide receptor agonists, ROMK inhibitors, WNK-SPAK inhibitors, and pendrin inhibitors.

Recent advances in cardiac biomarkers detection: From commercial devices to emerging technologies

Although cardiac pathologies are the major cause of death in the world, it remains difficult to provide a reliable diagnosis to prevent heart attacks. Rapid patient care and management in emergencies are critical to prevent dramatic consequences. Thus, relevant biomarkers such as cardiac troponin and natriuretic peptides are currently targeted by commercialized Point-Of-Care immunoassays. Key points still to be addressed concern cost, lack of standardization, and poor specificity, which could limit the reliability of the assays. Consequently, alternatives are emerging to address these issues. New probe molecules such as aptamers or molecularly imprinted polymers should allow a reduction in cost of the assays and an increase in reproducibility. In addition, the assay specificity and reliability could be improved by enabling multiplexing through the detection of several molecular targets in a single device.

Adipokines, Myokines, and Cardiokines: The Role of Nutritional Interventions

It is now established that adipose tissue, skeletal muscle, and heart are endocrine organs and secrete in normal and in pathological conditions several molecules, called, respectively, adipokines, myokines, and cardiokines. These secretory proteins constitute a closed network that plays a crucial role in obesity and above all in cardiac diseases associated with obesity. In particular, the interaction between adipokines, myokines, and cardiokines is mainly involved in inflammatory and oxidative damage characterized obesity condition. Identifying new therapeutic agents or treatment having a positive action on the expression of these molecules could have a key positive effect on the management of obesity and its cardiac complications. Results from recent studies indicate that several nutritional interventions, including nutraceutical supplements, could represent new therapeutic agents on the adipo-myo-cardiokines network. This review focuses the biological action on the main adipokines, myokines and cardiokines involved in obesity and cardiovascular diseases and describe the principal nutraceutical approaches able to regulate leptin, adiponectin, apelin, irisin, natriuretic peptides, and follistatin-like 1 expression.

Therapeutic Implications for PDE2 and cGMP/cAMP Mediated Crosstalk in Cardiovascular Diseases

Phosphodiesterases (PDEs) are the principal superfamily of enzymes responsible for degrading the secondary messengers 3',5'-cyclic nucleotides cAMP and cGMP. Their refined subcellular localization and substrate specificity contribute to finely regulate cAMP/cGMP gradients in various cellular microdomains. Redistribution of multiple signal compartmentalization components is often perceived under pathological conditions. Thereby PDEs have long been pursued as therapeutic targets in diverse disease conditions including neurological, metabolic, cancer and autoimmune disorders in addition to numerous cardiovascular diseases (CVDs). PDE2 is a unique member of the broad family of PDEs. In addition to its capability to hydrolyze both cAMP and cGMP, PDE2 is the sole isoform that may be allosterically activated by cGMP increasing its cAMP hydrolyzing activity. Within the cardiovascular system, PDE2 serves as an integral regulator for the crosstalk between cAMP/cGMP pathways and thereby may couple chronically adverse augmented cAMP signaling with cardioprotective cGMP signaling. This review provides a comprehensive overview of PDE2 regulatory functions in multiple cellular components within the cardiovascular system and also within various subcellular microdomains. Implications for PDE2- mediated crosstalk mechanisms in diverse cardiovascular pathologies are discussed highlighting the prospective use of PDE2 as a potential therapeutic target in cardiovascular disorders.

Circulating products of C-type natriuretic peptide and links with organ function in health and disease

Paracrine actions of CNP and rapid degradation at source severely limit study of CNP's many roles in vivo. However provided sensitive and validated assays are used, there is increasing evidence that low concentrations of bioactive CNP in plasma, and the readily detectable concentrations of the bio-inactive processed product of proCNP (aminoterminal proCNP), can be used to advance understanding of the hormone's role in pathophysiology. Provided renal function is normal, concordant changes in both CNP and NTproCNP reflect change in tissue production of proCNP whereas change in CNP alone results from altered rates of bioactive CNP degradation and are reflected in the ratio of NTproCNP to CNP. As already shown in juveniles, where plasma concentration of CNP products are higher and are associated with concurrent endochondral bone growth, measurements of plasma CNP products in mature adults have potential to clarify organ response to stress and injury. Excepting the role of CNP in fetal-maternal welfare, this review examines evidence linking plasma CNP products with function of a wide range of tissues in adults, including the impact of extraneous factors such as nutrients, hormone therapy and exercise.

Natriuretic peptides and neprilysin inhibition in hypertension and hypertensive organ damage

The family of natriuretic peptides (NPs) discovered in mammalian tissues including cardiac atrium and brain consists of three members, namely, atrial, B- and C-type natriuretic peptides (ANP, BNP, CNP). Since the discovery, basic and clinical studies have been vigorously performed to explore the biological functions and pathophysiological roles of NPs in a wide range of diseases including hypertension and heart failure. These studies revealed that ANP and BNP are hormones secreted from the heart into the blood stream in response to pre- or after-load, counteracting blood pressure (BP) elevation and fluid retention through specific receptors. Meanwhile, CNP was found to be produced by the vascular endothelium, acting as a local mediator potentially serving protective functions for the blood vessels. Because NPs not only exert blood pressure lowering actions but also alleviate hypertensive organ damage, attempts have been made to develop therapeutic agents for hypertension by utilizing this family of NPs. One strategy is to inhibit neprilysin, an enzyme degrading NPs, thereby enhancing the actions of endogenous peptides. Recently, a dual inhibitor of angiotensin receptor-neprilysin was approved for heart failure, and neprilysin inhibition has also been shown to be beneficial in treating patients with hypertension. This review summarizes the roles of NPs in regulating BP, with special references to hypertension and hypertensive organ damage, and discusses the therapeutic implications of neprilysin inhibition.

Phylogenic Determinants of Cardiovascular Frailty, Focus on Hemodynamics and Arterial Smooth Muscle Cells

The evolution of the circulatory system from invertebrates to mammals has involved the passage from an open system to a closed in-parallel system via a closed in-series system, accompanying the increasing complexity and efficiency of life’s biological functions. The archaic heart enables pulsatile motion waves of hemolymph in invertebrates, and the in-series circulation in fish occurs with only an endothelium, whereas mural smooth muscle cells appear later. The present review focuses on evolution of the circulatory system. In particular, we address how and why this evolution took place from a closed, flowing, longitudinal conductance at low pressure to a flowing, highly pressurized and bifurcating arterial compartment. However, although arterial pressure was the latest acquired hemodynamic variable, the general teleonomy of the evolution of species is the differentiation of individual organ function, supported by specific fueling allowing and favoring partial metabolic autonomy. This was achieved via the establishment of an active contractile tone in resistance arteries, which permitted the regulation of blood supply to specific organ activities via its localized function-dependent inhibition (active vasodilation). The global resistance to viscous blood flow is the peripheral increase in frictional forces caused by the tonic change in arterial and arteriolar radius, which backscatter as systemic arterial blood pressure. Consequently, the arterial pressure gradient from circulating blood to the adventitial interstitium generates the unidirectional outward radial advective conductance of plasma solutes across the wall of conductance arteries. This hemodynamic evolution was accompanied by important changes in arterial wall structure, supported by smooth muscle cell functional plasticity, including contractility, matrix synthesis and proliferation, endocytosis and phagocytosis, etc. These adaptive phenotypic shifts are due to epigenetic regulation, mainly related to mechanotransduction. These paradigms actively participate in cardio-arterial pathologies such as atheroma, valve disease, heart failure, aneurysms, hypertension, and physiological aging.

Peptidylglycine α-amidating monooxygenase is required for atrial secretory granule formation

The discovery of atrial secretory granules and the natriuretic peptides stored in them identified the atrium as an endocrine organ. Although neither atrial nor brain natriuretic peptide (ANP, BNP) is amidated, the major membrane protein in atrial granules is peptidylglycine α-amidating monooxygenase (PAM), an enzyme essential for amidated peptide biosynthesis. Mice lacking cardiomyocyte PAM (Pam ^Myh6-cKO/cKO) are viable, but a gene dosage-dependent drop in atrial ANP and BNP content occurred. Ultrastructural analysis of adult Pam ^Myh6-cKO/cKO atria revealed a 13-fold drop in the number of secretory granules. When primary cultures of Pam ^{0-Cre-cKO/cKO} atrial myocytes (no Cre recombinase, PAM floxed) were transduced with Cre-GFP lentivirus, PAM protein levels dropped, followed by a decline in ANP precursor (proANP) levels. Expression of exogenous PAM in Pam ^Myh6-cKO/cKO atrial myocytes produced a dose-dependent rescue of proANP content; strikingly, this response did not require the monooxygenase activity of PAM. Unlike many prohormones, atrial proANP is stored intact. A threefold increase in the basal rate of proANP secretion by Pam ^Myh6-cKO/cKO myocytes was a major contributor to its reduced levels. While proANP secretion was increased following treatment of control cultures with drugs that block the activation of Golgi-localized Arf proteins and COPI vesicle formation, proANP secretion by Pam ^Myh6-cKO/cKO myocytes was unaffected. In cells lacking secretory granules, expression of exogenous PAM led to the accumulation of fluorescently tagged proANP in the cis-Golgi region. Our data indicate that COPI vesicle-mediated recycling of PAM from the cis-Golgi to the endoplasmic reticulum plays an essential role in the biogenesis of proANP containing atrial granules.

N-Terminal-pro-Brain natriuretic peptide dynamics during effort phenotypes ischemic heart failure and determines prognosis regardless of ejection fraction

Ischemic heart disease leading to heart failure (HF) portends a high overall morbidity and mortality. A higher N-terminal-pro-B-type natriuretic peptide (NT-pro-BNP) at rest reflects HF severity and impaired cardiac output, most often secondary to reduced ejection fraction (EF). As an insufficient increase in cardiac output during exertion is common in all HF phenotypes, we examined the value of NT-pro-BNP during exercise testing as a risk stratification index for ischemic HF secondary to either reduced (HFrEF) or mid-ranged/preserved EF (HFmrEF/HFpEF). 213 patients (123 HFrEF; 90 HFmrEF/HFpEF) underwent cardiopulmonary exercise testing (CPET). NT-pro-BNP was determined at rest and peak exercise. The distribution of HFrEF and HFmrEF/HFpEF etiology in subjects with and without oxygen consumption trajectory flattening during CPET was similar (p > 0.05). Patients with HFrEF had higher plasma levels of NT-pro-BNP at rest and peak exercise than those with HFmrEF/HFpEF (984 vs. 780; 1012 vs. 845 pg/mL, p < 0.01, respectively), whereas ΔNT-pro-BNPpeak/rest was similar (60 vs. 50 pg/mL, p > 0.05). During the tracking period (22.4 ± 20.3 months) 34 patients died, and there were 2 cardiac transplantations and 3 LVAD implantations. In a multivariate regression model only the NT-pro-BNPpeak and ΔNT-pro-BNPpeak/rest were retained in the regression for the prediction of adverse events (Chi-square:8.97, p = 0.003). ROC analysis demonstrated that NT-pro-BNPpeak ≥1506 pg/mL and ΔNT-pro-BNPpeak/rest ≥108 pg/mL were optimal for identifying patients with a risk (Sn = 76.9, 74.4 %; Sp = 84.7, 80.9 %, respectively). NT-pro-BNP changes during effort and absolute peak values reached provide novel insights emerging as new and strong predictors of adverse events in HF of any EF.

C-type natriuretic peptide stimulates osteoblastic proliferation and collagen-X expression but suppresses fibroblast growth factor-23 expression in vitro

BACKGROUND

The effects of C-type natriuretic peptide (CNP) and fibroblast growth factor (FGF)-23 appear to oppose each other during the process of bone formation, whereas few studies exist on the interaction between CNP and FGF-23. The main objective of the present study is to probe whether CNP is directly responsible for the regulation of osteoblast or via antagonizing FGF-23.

METHODS

Osteoblasts were cultured in the absence or presence of CNP (0, 10, and 100 pmol/L) for 24 h, 48 h and 72 h, respectively.

RESULTS

The findings of the present study indicated that: (1) CNP significantly stimulated osteoblastic proliferation and collagen (Col)-X expression; (2) both osteoblastic (osteocalcin, procollagen type I carboxy-terminal propeptide, total alkaline phosphatase and bone-specific alkaline phosphatase) and osteolytic (tartrate-resistant acid phosphatase and cross-linked carboxyterminal telopeptide of type I collagen) bone turnover biomarkers were up-regulated by CNP in osteoblasts; (3) FGF-23 mRNA and protein were significantly down-regulated at 24 h by CNP in osteoblasts, but the expression of FGF receptor-1/Klotho had no significant change.

CONCLUSIONS

CNP stimulates osteoblastic proliferation and Col-X expression via the down-regulation of FGF-23 possibly in vitro. However, the specific mechanisms of the interaction between CNP and FGF-23 in osteoblasts are still unclear according to our findings. A further study on osteoblasts cultured with CNP and FGF-23 inhibitor will be undertaken in our laboratory.

Cardiac natriuretic peptides

Investigations into the mixed muscle-secretory phenotype of cardiomyocytes from the atrial appendages of the heart led to the discovery that these cells produce, in a regulated manner, two polypeptide hormones - the natriuretic peptides - referred to as atrial natriuretic factor or atrial natriuretic peptide (ANP) and brain or B-type natriuretic peptide (BNP), thereby demonstrating an endocrine function for the heart. Studies on the gene encoding ANP (NPPA) initiated the field of modern research into gene regulation in the cardiovascular system. Additionally, ANP and BNP were found to be the natural ligands for cell membrane-bound guanylyl cyclase receptors that mediate the effects of natriuretic peptides through the generation of intracellular cGMP, which interacts with specific enzymes and ion channels. Natriuretic peptides have many physiological actions and participate in numerous pathophysiological processes. Important clinical entities associated with natriuretic peptide research include heart failure, obesity and systemic hypertension. Plasma levels of natriuretic peptides have proven to be powerful diagnostic and prognostic biomarkers of heart disease. Development of pharmacological agents that are based on natriuretic peptides is an area of active research, with vast potential benefits for the treatment of cardiovascular disease.

The Importance of Natriuretic Peptides in Cardiometabolic Diseases

The natriuretic peptide (NP) system is composed of 3 distinct peptides (atrial natriuretic peptide or ANP, B-type natriuretic peptide or BNP, and C-type natriuretic peptide or CNP) and 3 receptors (natriuretic peptide receptor-A or NPR-A or particulate guanynyl cyclase-A natriuretic peptide receptor-B or NPR-B or particulate guanynyl cyclase-B, and natriuretic peptide receptor-C or NPR-C or clearance receptor). ANP and BNP function as defense mechanisms against ventricular stress and the deleterious effects of volume and pressure overload on the heart. Although the role of NPs in cardiovascular homeostasis has been extensively studied and well established, much remains uncertain about the signaling pathways in pathological states like heart failure, a state of impaired natriuretic peptide function. Elevated levels of ANP and BNP in heart failure correlate with disease severity and have a prognostic value. Synthetic ANP and BNP have been studied for their therapeutic role in hypertension and heart failure, and promising trials are under way. In recent years, the expression of ANP and BNP in human adipocytes has come to light. Through their role in promotion of adipocyte browning, lipolysis, lipid oxidation, and modulation of adipokine secretion, they have emerged as key regulators of energy consumption and metabolism. NPR-A signaling in skeletal muscles and adipocytes is emerging as pivotal to the maintenance of long-term insulin sensitivity, which is disrupted in obesity and reduced glucose-tolerance states. Genetic variants in the genes encoding for ANP and BNP have been associated with a favorable cardiometabolic profile. In this review, we discuss several pathways that have been proposed to explain the role of NPs as endocrine networkers. There is much to be explored about the therapeutic role of NPs in improving metabolic milieu.

The Future of Biomarkers

Numerous compounds have been tested as potential biomarkers for multiple possible applications within intensive care medicine but none is or will ever be sufficiently specific or sensitive for the heterogeneous syndromes of critical illness. New technology and access to huge patient databases are providing new biomarker options and the focus is shifting to combinations of several or multiple biomarkers rather than the single markers that research has concentrated on in the past. Biomarkers will increasingly be used as part of routine clinical practice in the future, complementing clinical examination and physician expertise to provide accurate disease diagnosis, prediction of complications, personalized treatment guidance, and prognosis.

C-type natriuretic peptide suppresses ventricular arrhythmias in rats with acute myocardial ischemia

This study aimed to investigate the effects of C-type natriuretic peptide (CNP) on ventricular arrhythmias in rats with acute myocardial ischemia (AMI). Forty male Sprague-Dawley rats were randomly divided into sham group (n = 10), AMI group (n = 15) and AMI + CNP group (n = 15). AMI model was induced by ligating the left anterior descending branch of the coronary artery, and CNP was pumped through the femoral vein starting 30 min before ischemia and continuing until 1 h after AMI. The occurrence of ventricular arrhythmias after ischemia and heart rate variability (HRV) were recorded and analyzed. The plasma norepinephrine level was detected at 15 min after AMI. Ventricular electrophysiological parameters including ventricular effective refractory period (ERP), ERP dispersion, ventricular action potential duration (APD) alternans and ventricular fibrillation threshold (VFT) were measured one hour after AMI. Then, the expressions of cyclic guanosine monophosphate in myocardial tissue and left stellate ganglion were examined. Compared to sham group, AMI significantly shortened the ERP, augmented ERP dispersion, elevated APD alternans cycle length, reduced VFT, and increased the incidence of ventricular arrhythmias. Moreover, AMI increased the sympathetic component of HRV, raised plasma norepinephrine levels, and decreased the cyclic guanosine monophosphate levels in myocardium and left stellate ganglion. All those changes were attenuated by CNP treatment. These findings suggest that CNP protected against ventricular arrhythmias in rats with AMI, potentially by inhibiting ischemia-induced cardiac sympathetic hyperactivity and cardiac electrophysiology instability.

Biomarkers in Community-Acquired Pneumonia (Cardiac and Non-Cardiac)

Community-acquired pneumonia (CAP) remains the first cause of morbidity and mortality worldwide due to infection. Several aspects such as severity and host response are related to its clinical course and outcome. Beyond the acute implications that the infection provokes in the host, pneumonia also has long-term negative consequences. Among them, cardiovascular complications and mortality are the most outstanding. Therefore, an adequate recognition and stratification of the risk of complications and mortality is crucial. Many biomarkers have been studied for these reasons, considering that each biomarker mirrors a different aspect. Moreover, the clinical application of many of them is still being deliberated because of their limitations and the heterogeneity of the disease. In this review, we examine some of the most relevant biomarkers that we have classified as cardiac and non-cardiac. We discuss some classic biomarkers and others that are considered novel biomarkers, which are mainly involved in cardiovascular risk.

Evaluation of transcriptional levels of the natriuretic peptides, endothelin-1, adrenomedullin, their receptors and long non-coding RNAs in rat cardiac tissue as cardiovascular biomarkers of aging

Chronological age is considered one of the major risk factors for cardiovascular disease and mortality. The study aimed to evaluate the transcriptional levels of the natriuretic peptides (NP), endothelin (ET)-1, adrenomedullin (ADM), their receptors and long non-coding (Lnc) RNA MIAT, MALAT-1, CARMEN and XIST in rat cardiac tissue as cardiovascular biomarkers of aging. Three groups of male Wistar rats were studied: A (n = 6; young), B (n = 13; adult), C (n = 10; old). Total RNA was extracted from left ventricle and analyzed by Real-Time PCR. Echocardiographic and histological analyses were performed. A significant increase of Atrial NP (ANP) and Brain NP (BNP) mRNA was observed in C while C-type NP (CNP) remained in a steady-state in B and C; ET-1 mRNA increased significantly as a function of age. Any difference was observed for NP receptors. ETA expression was statistically lower in B than A while ETB were similar in all the three groups. The ADM showed an opposite trend to that of the other peptides decreasing significantly as a function of age and presenting a counter-regulation of calcitonin receptor-like receptor (CLR) and receptor activity modifying protein (RAMP)-2. LncRNA transcripts decreased significantly as a function of age except for XIST. ADM and LncRNA trend suggest that the animals are subjected to "successful aging" as also confirmed by histological analysis. Applying a multivariate logistic regression analysis, only LnANP (p = 0.003) and LnADM (p = 0.023) resulted significantly associated with aging identifying them, for the first time, as independent markers of aging. The study underlining the importance of a multi-label biomolecular approach in the evaluation of aging.