Regulation of C-type natriuretic peptide expression

Paracrine and endocrine pathways of natriuretic peptides assessed by ligand-receptor mapping in the Japanese eel brain

The natriuretic peptide (NP) family consists of cardiac NPs (ANP, BNP, and VNP) and brain NPs (CNPs) in teleosts. In addition to CNP1-4, a paralogue of CNP4 (named CNP4b) was recently discovered in basal teleosts including Japanese eel. Mammals have lost most Cnps during the evolution, but teleost cnps were conserved and diversified, suggesting that CNPs are important hormones for maintaining brain functions in teleost. The present study evaluated the potency of each Japanese eel CNP to their NP receptors (NPR-A, NPR-B, NPR-C, and NPR-D) overexpressed in CHO cells. A comprehensive brain map of cnps- and nprs-expressing neurons in Japanese eel was constructed by integrating the localization results obtained by in situ hybridization. The result showed that CHO cells expressing NPR-A and NPR-B induced strong cGMP productions after stimulation by cardiac and brain NPs, respectively. Regarding brain distribution of cnps, cnp1 is engaged in the ventral telencephalic area and periventricular area including the parvocellular preoptic nucleus (Pp), anterior/posterior tuberal nuclei, and periventricular gray zone of the optic tectum. cnp3 is found in the habenular nucleus and prolactin cells in the pituitary. cnp4 is expressed in the ventral telencephalic area, while cnp4b is expressed in the motoneurons in the medullary area. Such CNP isoform-specific localizations suggest that function of each CNP has diverged in the eel brain. Furthermore, the Pp lacking the blood-brain barrier expressed both npra and nprb, suggesting that endocrine and paracrine NPs interplay for regulating the Pp functions in Japanese eels.

Assessment of amino-terminal C-type natriuretic peptide serum level and its correlation with high-density lipoprotein structure and function in patients with end stage renal disease before and after kidney transplantation

We aimed to investigate serum amino-terminal C-type natriuretic peptide (NT-proCNP) and its relationship with quantitative and qualitative HDL-parameters in patients with end-stage renal disease (ESRD) before, then 1 and 6 months after kidney transplantation (TX). Seventy patients (47 males, 23 females, mean age 51.7 ± 12.4 years) were enrolled in a prospective follow-up study. We examined serum creatinine, C-reactive protein, procalcitonin, fasting glucose and lipid parameters before, then 1 and 6 months after TX. High-density lipoprotein- (HDL)-associated paraoxonase-1 (PON1) paraoxonase and arylesterase activities were measured spectrophotometrically. Lipoprotein subfractions were determined by Lipoprint. NT-proCNP and oxidized low-density lipoprotein (oxLDL) levels were measured by ELISA. Mean NT-proCNP was 45.8 ± 21.9 pmol/L before renal transplantation and decreased markedly 1 month and 6 months after transplantation (5.3 ± 2.5 and 7.7 ± 4.9 pmol/L, respectively, P = 1 × 10-4). During the 6 months' follow-up, PON1 arylesterase, paraoxonase and salt-stimulated paraoxonase activities improved. NT-proCNP positively correlated with procalcitonin and creatinine and negatively with GFR, LDL-cholesterol (LDL-C) and HDL-cholesterol (HDL-C). There was a negative correlation between serum NT-proCNP and PON1 arylesterase activity. According to the multiple regression analysis, the best predicting variables of NT-proCNP were serum procalcitonin, creatinine and PON1 arylesterase activity. NT-proCNP might be a novel link between HDL dysfunction and impaired vascular function in ESRD, but not after kidney transplantation. Further studies in larger populations are needed to clarify the exact role of NT-proCNP in the risk prediction for cardiovascular comorbidities and complications in ESRD.

Decreased level of serum NT-proCNP associates with disease severity in COVID-19

BACKGROUND

C-type natriuretic peptide (CNP) is an endothelium-derived paracrine molecule with an important role in vascular homeostasis. In septic patients, the serum level of the amino-terminal propeptide of CNP (NT-proCNP) shows a strong positive correlation with inflammatory biomarkers and, if elevated, correlates with disease severity and indicates a poor outcome. It is not yet known whether NT-proCNP also correlates with the clinical outcome of patients suffering from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In the current study, we aimed to determine possible changes in the NT-proCNP levels of patients with coronavirus disease 2019 (COVID-19), with special regard to disease severity and outcome.

METHODS

In this retrospective analysis, we determined the serum level of NT-proCNP in hospitalized patients with symptoms of upper respiratory tract infection, using their blood samples taken on admission, stored in a biobank. The NT-proCNP levels of 32 SARS-CoV-2 positive and 35 SARS-CoV-2 negative patients were measured to investigate possible correlation with disease outcome. SARS-CoV-2 positive patients were then divided into two groups based on their need for intensive care unit treatment (severe and mild COVID-19).

RESULTS

The NT-proCNP was significantly different in the study groups (e.g. severe and mild COVID-19 and non-COVID-19 patients), but showed inverse changes compared to previous observations in septic patients: lowest levels were detected in critically ill COVID-19 patients, while highest levels in the non-COVID-19 group. A low level of NT-proCNP on admission was significantly associated with severe disease outcome.

CONCLUSIONS

Low-level NT-proCNP on hospital admission is associated with a severe COVID-19 disease course. The pathomechanism underlying this observation remains to be elucidated, while future studies in larger patient cohorts are necessary to confirm these observations and reveal therapeutic importance. Trial registration DRKS00026655 Registered 26. November 2021.

NT-proCNP levels predict higher atherosclerotic cardiovascular risk profile in patients with proliferative diabetic retinopathy

AIMS

In this study, we aimed to demonstrate the effectiveness of serum amino-terminal proCNP (NT-proCNP) levels in predicting coronary heart disease (CHD) and cardiovascular risk in type 2 diabetes mellitus (T2DM) patients.

METHODS

We recruited 73 patients with T2DM in the study. Additionally, we grouped the patients according to their status of diabetic retinopathy (DR) as no DR, non-proliferative DR, or proliferative DR. Serum NT-proCNP levels of the patients were measured and their atherosclerotic cardiovascular disease (ASCVD) risk scores were calculated.

RESULTS

There was no significant difference in terms of NT-proCNP levels between the groups (p = 0.3) and in terms of CHD and ASCVD risk scores (p = 0.4 and p = 0.4, respectively). In the correlation analysis, a significant correlation was observed between the NT-proCNP levels and the ASCVD risk score (r = 0.373; p = 0.008 among the entire cohort and r = 0.555; p = 0.01 in the non-proliferative-DR group), smoking status (r = 0.280; p = 0.03 among the entire cohort and r = 0.362; p = 0.035 in the non-proliferative-DR group), sBP (r = 0.278; p = 0.038 among the entire cohort), and dBP (r = 0.284; p = 0.034 among the entire cohort and r = 0.482; p = 0.004 in the proliferative-DR group). In the ROC analysis, we found that the NT-proCNP level predicted a high ASCVD risk score with 83.3% sensitivity and 70.8% specificity and a very high ASCVD risk score with 100% sensitivity and 69.2% specificity among the proliferative-DR patients. No cut-off value was calculated for the prediction of high and very-high ASCVD risk scores in patients with non-proliferative DR. Similarly, no cut-off value was revealed for the prediction of established coronary artery disease in all groups.

CONCLUSIONS

Our study revealed a significant association between NT-proCNP levels and high ASCVD risk scores in patients with proliferative DR.

Sex-specific mortality prediction by pro-C-type natriuretic peptide measurement in a prospective cohort of patients with ST-elevation myocardial infarction

OBJECTIVE

To determine the predictive value of pro-C-type natriuretic peptide (pro-CNP) measurement in plasma sampled on admission from patients presenting with ST-elevation myocardial infarction (STEMI).

DESIGN

Prospective cohort study.

SETTING

Two University Hospitals in Denmark.

PARTICIPANTS

1760 consecutive patients (470 females and 1290 males) with confirmed STEMI.

MAIN OUTCOMES AND MEASURES

The main outcome was all-cause mortality at 1 year after presentation and the primary measure was pro-CNP concentration in plasma at admission in all patients and longitudinal measurements in a consecutive subgroup of 287 patients. A reference population (n=688) defined cut-off values of increased pro-CNP concentrations.

RESULTS

In all patients, an increased pro-CNP concentration was associated with a higher all-cause mortality after 1 year (HR 1.6, 95% CI 1.1 to 2.4, P_logrank=0.009) including an interaction of sex (p=0.03). In separate sex-stratified analyses, female patients showed increased all-cause mortality (HR_{1 year} 2.6, 95% CI 1.5 to 4.6), P_logrank <0.001), whereas no differences were found in male patients (HR_{1 year} 1.1, 95% CI 0.7 to 1.9, P_logrank=0.66). After adjusting for potential risk factors, we found increased pro-CNP concentrations≥the median value to be independently associated with increased risk of mortality in female patients within 1 year (HR per 1 pmol/L increase: 1.04, 95% CI 1.01 to 1.06, p=0.007). Moreover, we found indications of sex differences in pro-CNP concentrations over time (higher pro-CNP in males (4.4, 95% CI -0.28 to 9.1 pmol/L, p=0.07) and interaction of sex and time (p=0.13)), and that hypertension was independently associated with higher pro-CNP (4.5, 95% CI 0.6 to 8.4 pmol/L, p=0.03).

CONCLUSIONS

In female but not male patients presenting with STEMI, high concentrations of pro-CNP (≥median) at admission independently indicate a higher risk of all-cause mortality. The findings are remarkably specific for female patients, suggesting a different vascular phenotype beyond traditional measures of coronary artery flow compared with male patients.

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.

Sperm Functional Genome Associated With Bull Fertility

Bull fertility is an important economic trait in sustainable cattle production, as infertile or subfertile bulls give rise to large economic losses. Current methods to assess bull fertility are tedious and not totally accurate. The massive collection of functional data analyses, including genomics, proteomics, metabolomics, transcriptomics, and epigenomics, helps researchers generate extensive knowledge to better understand the unraveling physiological mechanisms underlying subpar male fertility. This review focuses on the sperm phenomes of the functional genome and epigenome that are associated with bull fertility. Findings from multiple sources were integrated to generate new knowledge that is transferable to applied andrology. Diverse methods encompassing analyses of molecular and cellular dynamics in the fertility-associated molecules and conventional sperm parameters can be considered an effective approach to determine bull fertility for efficient and sustainable cattle production. In addition to gene expression information, we also provide methodological information, which is important for the rigor and reliability of the studies. Fertility is a complex trait influenced by several factors and has low heritability, although heritability of scrotal circumference is high and that it is a known fertility maker. There is a need for new knowledge on the expression levels and functions of sperm RNA, proteins, and metabolites. The new knowledge can shed light on additional fertility markers that can be used in combination with scrotal circumference to predict the fertility of breeding bulls. This review provides a comprehensive review of sperm functional characteristics or phenotypes associated with bull fertility.

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.

Regulation and Function of C-Type Natriuretic Peptide (CNP) in Gonadotrope-Derived Cell Lines

C-type natriuretic peptide (CNP) is the most conserved member of the mammalian natriuretic peptide family, and is implicated in the endocrine regulation of growth, metabolism and reproduction. CNP is expressed throughout the body, but is particularly abundant in the central nervous system and anterior pituitary gland. Pituitary gonadotropes are regulated by pulsatile release of gonadotropin releasing hormone (GnRH) from the hypothalamus, to control reproductive function. GnRH and CNP reciprocally regulate their respective signalling pathways in αT3-1 gonadotrope cells, but effects of pulsatile GnRH stimulation on CNP expression has not been explored. Here, we examine the sensitivity of the natriuretic peptide system in LβT2 and αT3-1 gonadotrope cell lines to continuous and pulsatile GnRH stimulation, and investigate putative CNP target genes in gonadotropes. Multiplex RT-qPCR assays confirmed that primary mouse pituitary tissue express Nppc,Npr2 (encoding CNP and guanylyl cyclase B (GC-B), respectively) and Furin (a CNP processing enzyme), but failed to express transcripts for Nppa or Nppb (encoding ANP and BNP, respectively). Pulsatile, but not continuous, GnRH stimulation of LβT2 cells caused significant increases in Nppc and Npr2 expression within 4 h, but failed to alter natriuretic peptide gene expression in αT3-1 cells. CNP enhanced expression of cJun, Egr1, Nr5a1 and Nr0b1, within 8 h in LβT2 cells, but inhibited Nr5a1 expression in αT3-1 cells. Collectively, these data show the gonadotrope natriuretic peptide system is sensitive to pulsatile GnRH signalling, and gonadotrope transcription factors are putative CNP-target genes. Such findings represent additional mechanisms by which CNP may regulate reproductive function.

Spatiotemporal expression patterns of natriuretic peptides in rat testis and epididymis during postnatal development

Natriuretic peptide (NP) family is composed of atrial, brain and C-type NP (NPPA, NPPB and NPPC). Here, we aimed to investigate NP expression in testis and epididymis during postnatal development. NPPA expression was observed in gonocytes at prepubertal period but in only spermatocytes in pachytene and leptotene/zygotene stage at pubertal period. In prepubertal and pubertal periods, we detected NPPB expression in only Leydig cells. However, NPPC expression was detected in all of the gonocytes and Sertoli cells, spermatocytes and some interstitial cells in prepubertal and pubertal periods. In postpubertal and mature periods, NPPA and NPPB staining were detected in Leydig cells, elongated and round spermatids but not in spermatogonia and spermatocytes. However, we observed NPPC expression in all cells of the seminiferous tubules and Leydig cells in the postpubertal and mature periods. Epididymal epithelium showed intense NPPC expression during postnatal period but weak NPPA and NPPB expression in prepubertal and pubertal periods. The expression of three NPs in the testis significantly increased after puberty. In conclusion, puberty had a significant effect on NP expression in testis. Unlike NPPA and NPPB, expression of NPPC in all cells of the seminiferous tubule suggests that NPPC is effective in each step of spermatogenesis.

[Novel Biomarkers of Pulmonary Hypertension]

Pulmonary hypertension (PH) is a clinical syndrome characterized by a progressive increase in pulmonary vascular resistance (PVR), which leads to remodeling of the right ventricle (RV), right heart failure and premature death of patients. Early diagnosis and monitoring of disease progression are crucial for making decisions about the necessary therapy. The gold standard for the diagnosis of pulmonary hypertension is the right heart catheterization. The estimation of systolic pressure in pulmonary artery by means of transthoracic echocardiography is also used for monitoring the course of the disease. At present, there is still a need for non-invasive biomarkers that reflect pathological changes in pulmonary arterial vessels and allow diagnosing of PH. Our review outlines the new data about some biomarkers potentially useful for diagnosis and prognostication of PH. These biomarkers (mid-regional pro-adrenomedullin, carboxyterminal pro-endothelin-1, copeptin, asymmetric dimethylarginine, growth differentiation factor 15, and others) are classified based on their relationship to endothelial cell dysfunction, inflammation, epigenetics, cardiac function, oxidative stress, extracellular matrix. The determination of biomarkers that are of diagnostic value for predicting the severity, progression of PH and response to therapy, in a simple blood test or condensate of exhaled air, can significantly reduce treatment costs and improve PH management.

C-type natriuretic peptide regulates sperm capacitation by the cGMP/PKG signalling pathway via Ca2+ influx and tyrosine phosphorylation

RESEARCH QUESTION

What is the effect of C-type natriuretic peptide (CNP) on human sperm capacitation in vitro and what is the mechanism of this effect?

DESIGN

CNP/NPR-B expression in the female rat genital tract was examined by immunohistochemistry and western blot assay, and then the role of CNP in human sperm capacitation was determined. The signal transduction pathway of CNP in the process was determined to elucidate the regulation mechanism of CNP by enzyme-linked immunosorbent assay and flow cytometry.

RESULTS

Both CNP and NPR-B were expressed in the genital tract of female rats, especially in the mucosa epithelium cell of the oviduct; the CNP level in the rat oviduct was higher than that in the cervix. Both CNP and NPR-B level in the rat oviduct varied during the oestrus cycle, maximal expression being observed at proestrus. Furthermore, intracellular cGMP level in spermatozoa was significantly enhanced by CNP (P < 0.01). PKG activity was detected in the spermatozoa, and it can be activated by the CNP and 8-Br-cGMP (cGMP analogue). The PKG inhibitor KT5823 inhibited the effect of CNP on sperm hyperactivation and the acrosome reaction. Finally, Ca²⁺ and tyrosine phosphorylation levels in spermatozoa were markedly improved by CNP and 8-Br-cGMP but significantly inhibited by the addition of KT5823 (P < 0.05).

CONCLUSIONS

CNP secreted by the female genital tract might bind to NPR-B on the spermatozoa. It successively stimulated intracellular cGMP/PKG signalling, increased Ca²⁺ and tyrosine-phosphorylated proteins, promoted hyperactivation and induced the acrosome reaction, which ultimately facilitated sperm capacitation.

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

Among the three natriuretic peptides, atrial/A-type natriuretic peptide (ANP) and brain/B-type natriuretic peptide (BNP) are primarily produced by, and secreted from, heart tissue. They maintain cardiovascular homeostasis by binding to natriuretic peptide receptor-A. Since plasma ANP and BNP concentrations, as well as expression, are elevated in response to increased body fluid volume and pressure load on the heart wall, these peptides are widely utilized as diagnostic biomarkers for evaluating heart failure. Regardless of their high utility, differences in their molecular forms between healthy and diseased subjects and how these relate to pathophysiology have not well been examined. Recent studies have shown that the circulating molecular forms of ANP and BNP are not uniform; bioactive α-ANP is the major ANP form, whereas the weakly active proBNP is the major BNP form. The relative ratios of the different molecular forms are altered under different pathophysiological conditions. These facts indicate that detailed measurements of each form may provide useful information on the pathophysiological state of heart tissue. Here, we revisit the relationship between the molecular forms of, and pathophysiological alterations in, human ANP and BNP and discuss the possible utility of the measurement of each of the molecular forms. The third peptide, C-type natriuretic peptide, activates natriuretic peptide receptor-B, but little is known about its production and function in the heart because of its extremely low levels. However, through recent studies, its role in the heart is gradually becoming clear. Here, we summarize its molecular forms, assay systems, and functions in the heart.

Host Peptidic Hormones Affecting Bacterial Biofilm Formation and Virulence

Bacterial biofilms constitute a critical problem in hospitals, especially in resuscitation units or for immunocompromised patients, since bacteria embedded in their own matrix are not only protected against antibiotics but also develop resistant variant strains. In the last decade, an original approach to prevent biofilm formation has consisted of studying the antibacterial potential of host communication molecules. Thus, some of these compounds have been identified for their ability to modify the biofilm formation of both Gram-negative and Gram-positive bacteria. In addition to their effect on biofilm production, a detailed study of the mechanism of action of these human hormones on bacterial physiology has allowed the identification of new bacterial pathways involved in biofilm formation. In this review, we focus on the impact of neuropeptidic hormones on bacteria, address some future therapeutic issues, and provide a new view of inter-kingdom communication.

Natriuretic Peptides and Normal Body Fluid Regulation

Natriuretic peptides are structurally related, functionally diverse hormones. Circulating atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are delivered predominantly by the heart. Two C-type natriuretic peptides (CNPs) are paracrine messengers, notably in bone, brain, and vessels. Natriuretic peptides act by binding to the extracellular domains of three receptors, NPR-A, NPR-B, and NPR-C of which the first two are guanylate cyclases. NPR-C is coupled to inhibitory proteins. Atrial wall stress is the major regulator of ANP secretion; however, atrial pressure changes plasma ANP only modestly and transiently, and the relation between plasma ANP and atrial wall tension (or extracellular volume or sodium intake) is weak. Absence and overexpression of ANP-related genes are associated with modest blood pressure changes. ANP augments vascular permeability and reduces vascular contractility, renin and aldosterone secretion, sympathetic nerve activity, and renal tubular sodium transport. Within the physiological range of plasma ANP, the responses to step-up changes are unimpressive; in man, the systemic physiological effects include diminution of renin secretion, aldosterone secretion, and cardiac preload. For BNP, the available evidence does not show that cardiac release to the blood is related to sodium homeostasis or body fluid control. CNPs are not circulating hormones, but primarily paracrine messengers important to ossification, nervous system development, and endothelial function. Normally, natriuretic peptides are not powerful natriuretic/diuretic hormones; common conclusions are not consistently supported by hard data. ANP may provide fine-tuning of reno-cardiovascular relationships, but seems, together with BNP, primarily involved in the regulation of cardiac performance and remodeling. © 2017 American Physiological Society. Compr Physiol 8:1211-1249, 2018.

The effects of exercise training associated with low-level laser therapy on biomarkers of adipose tissue transdifferentiation in obese women

Investigations suggest the benefits of low-level laser therapy (LLLT) to improve noninvasive body contouring treatments, inflammation, insulin resistance and to reduce body fat. However, the mechanism for such potential effects in association with exercise training (ET) and possible implications in browning adiposity processes remains unclear. Forty-nine obese women were involved, aged between 20 and 40 years with a body mass index (BMI) of 30-40 kg/m². The volunteers were divided into Phototherapy (808 nm) and SHAM groups. Interventions consisted of exercise training and phototherapy applications post exercise for 4 months, with three sessions/week. Body composition, lipid profile, insulin resistance, atrial natriuretic peptide (ANP), WNT5 signaling, interleukin-6 (IL-6), and fibroblast growth factor-21 (FGF-21) were measured. Improvements in body mass, BMI, body fat mass, lean mass, visceral fat, waist circumference, insulin, HOMA-IR, total cholesterol, LDL-cholesterol, triglycerides, and ANP in both groups were demonstrated. Only the Phototherapy group showed a reduction in interleukin-6 and an increase in WNT5 signaling. In addition, it was possible to observe a higher magnitude change for the fat mass, insulin, HOMA-IR, and FGF-21 variables in the Phototherapy group. In the present investigation, it was demonstrated that exercise training associated with LLLT promotes an improvement in body composition and inflammatory processes as previously demonstrated. The Phototherapy group especially presented positive modifications of WNT5 signaling, FGF-21, and ANP, possible biomarkers associated with browning adiposity processes. This suggests that this kind of intervention promotes results applicable in clinical practice to control obesity and related comorbidities.

New Insights into Cardiac and Vascular Natriuretic Peptides: Findings from Young Adults Born with Very Low Birth Weight

BACKGROUND

In community studies, plasma B-type natriuretic peptide (BNP) is positively associated with cardiovascular disorders. Those born with very low birth weight (VLBW) have increased risk of metabolic and vascular disorders in later life, but plasma concentrations of natriuretic peptides have not been studied. The objectives here were to evaluate BNP and C-type natriuretic peptide (CNP)—a putative marker of vascular risk—in young adults born with VLBW.

METHODS

In all, 220 VLBW cases and 97 matched controls were studied 28 years after birth during a 2-day period at 1 research center. Aminoterminal (NT) products (NTproBNP, NTproCNP) and a range of conventional vascular risk factors including echocardiographic indices were measured along with genetic polymorphisms known to increase plasma NTproBNP.

RESULTS

VLBW individuals were smaller, had smaller hearts, reduced stroke volume and endothelial function, and higher systolic blood pressure and arterial elastance. Of the many humoral vascular and metabolic risk factors measured, including NTproBNP, only plasma NTproCNP (higher in VLBW individuals) differed significantly. Across all individuals, associations of NTproCNP with each of 7 conventional risk factors, as well as with arterial elastance, were positive, whereas associations of NTproBNP with risk were all inverse. In multivariate analysis, the genetic variant rs198358 was independently associated with NTproBNP.

CONCLUSIONS

In young adults at increased risk of cardiovascular disease, higher NTproCNP likely reflects a compensatory vascular response to vascular stress, whereas the negative link with NTproBNP likely reflects beneficial genetic mutations. The ratio of NTproBNP to NTproCNP may provide a novel index of ideal cardiovascular health.

Natriuretic peptides in the control of lipid metabolism and insulin sensitivity

Natriuretic peptides have long been known for their cardiovascular function. However, a growing body of evidence emphasizes the role of natriuretic peptides in human substrate and energy metabolism, thereby connecting the heart with several insulin-sensitive organs like adipose tissue, skeletal muscle and liver. Obesity may be associated with an impaired regulation of the natriuretic peptide system, also indicated as a natriuretic handicap. Evidence points towards a contribution of this natriuretic handicap to the development of obesity, type 2 diabetes mellitus and cardiometabolic complications, although the causal relationship is not fully understood. Nevertheless, targeting the natriuretic peptide pathway may improve metabolic health in obesity and type 2 diabetes mellitus. This review will focus on current literature regarding the metabolic roles of natriuretic peptides with emphasis on lipid metabolism and insulin sensitivity. Furthermore, it will be discussed how exercise and lifestyle intervention may modulate the natriuretic peptide-related metabolic effects.

The multifaceted role of natriuretic peptides in metabolic syndrome

Due to globalization and sophisticated western and sedentary lifestyle, metabolic syndrome has emerged as a serious public health challenge. Obesity is significantly increasing worldwide because of increased high calorie food intake and decreased physical activity leading to hypertension, dyslipidemia, atherosclerosis, and insulin resistance. Thus, metabolic syndrome constitutes cardiovascular disease, type 2 diabetes, obesity, and nonalcoholic fatty liver disease (NAFLD) and recently some cancers are also considered to be associated with this syndrome. There is increasing evidence of the involvement of natriuretic peptides (NP) in the pathophysiology of metabolic diseases. The natriuretic peptides are cardiac hormones, which are produced in the cardiac atrium, ventricles of the heart and the endothelium. These peptides are involved in the homeostatic control of body water, sodium intake, potassium transport, lipolysis in adipocytes and regulates blood pressure. The three known natriuretic peptide hormones present in the natriuretic system are atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and c-type natriuretic peptide (CNP). These three peptides primarily function as endogenous ligands and mainly act via their membrane receptors such as natriuretic peptide receptor A (NPR-A), natriuretic peptide receptor B (NPR-B) and natriuretic peptide receptor C (NPR-C) and regulate various physiological and metabolic functions. This review will shed light on the structure and function of natriuretic peptides and their receptors and their role in the metabolic syndrome.

Nutrient restriction in early ovine pregnancy stimulates C-type natriuretic peptide production

C-type natriuretic peptide (CNP), a paracrine growth factor promoting vasodilation and angiogenesis, is upregulated in human and ovine pregnancy in response to vascular stress or nutrient restriction (NR) in late gestation. Postulating that maternal plasma CNP products are increased by modest NR (50% of metabolisable energy requirement) early in pregnancy, and further enhanced by litter size, we studied serial changes of maternal plasma CNP in pregnant ewes receiving a normal (NC, n=12) or restricted (NR, n=13) diet from Day 30 to Day 93 or 94 of gestation. Liveweight of NR ewes was 10kg less than that of NC ewes at slaughter. Plasma CNP products increased progressively after Day 40 and were higher in NR (P<0.05) ewes after Day 60; they were also enhanced by litter size (P<0.01) and were positively associated with increased placental efficiency. In contrast, whereas fetal and placental weight were reduced by NR, fetal plasma CNP products (Day 93/94) were not affected. We conclude that increases in CNP during rapid placental growth are further enhanced by both increasing nutrient demands and by reduced supply, presumably as part of an adaptive response benefitting placental-fetal exchange.

Three molecular forms of atrial natriuretic peptides: quantitative analysis and biological characterization

Atrial natriuretic peptide (ANP) is primarily produced in the heart tissue and plays a pivotal role in maintaining cardiovascular homeostasis in endocrine and autocrine/paracrine systems and has clinical applications as a biomarker and a therapeutic agent for cardiac diseases. ANP is synthesized by atrial cardiomyocytes as a preprohormone that is processed by a signal peptidase and stored in secretory granules as a prohormone. Subsequent proteolytic processing of ANP by corin during the secretion process results in a bioactive form consisting of 28 amino acid residues. Mechanical stretch of the atrial wall and multiple humoral factors directly stimulates the transcription and secretion of ANP. Secreted ANP elicits natriuretic and diuretic effects via cyclic guanosine monophosphate produced through binding to the guanylyl cyclase-A/natriuretic peptide receptor-A. Circulating ANP is subjected to rapid clearance by a natriuretic peptide receptor-C-mediated mechanism and proteolytic degradation by neutral endopeptidase. In humans, ANP is present as three endogenous molecular forms: bioactive α-ANP, a homodimer of α-ANP designated as β-ANP, and an ANP precursor designated as proANP (also referred to as γ-ANP). The proANP and especially β-ANP, as minor forms in circulation, are notably increased in patients with cardiac diseases, suggesting the utility of monitoring the pathophysiological conditions that result in abnormal proANP processing that cannot be monitored by inactive N-terminal proANP-related fragments. Emerging plate-based sandwich immunoassays for individual quantitation of the three ANP forms enables evaluation of diagnostic implications and net ANP bioactivity. This new tool may provide further understanding in the pathophysiology of cardiac diseases. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.

Angiotensin Receptor-Neprilysin Inhibition

The novel combination sacubitril/valsartan represents a new therapeutic approach in the management of heart failure. With the simultaneous blockage of the enzyme neprilysin (by sacubitril) and angiotensin II receptors (by valsartan), this combination reduces the degradation of natriuretic peptides and other counterregulatory peptide systems while avoiding the deleterious effect of angiotensin II receptors activation and thereby encompasses a beneficial impact of 2 important neurohormonal pathways activated in heart failure. As opposed to previously tested neprilysin inhibitors, sacubitril/valsartan represents a more effective method in reducing morbidity and mortality in heart failure, while preserving a safety profile comparable to well-established, standard, angiotensin-converting enzyme inhibitor's therapy.

C-Type Natriuretic Peptides in Coronary Disease

AIMS

C-type natriuretic peptide (CNP) is a paracrine growth factor expressed in the vascular endothelium. Although upregulated in atheromatous arteries, the predictive value of plasma CNP products for outcome in coronary disease is unknown. This study aimed to compare the prognostic value of plasma CNP products with those of other natriuretic peptides in individuals with coronary artery disease, and investigate their associations with cardiac and renal function.

METHODS AND RESULTS

Plasma concentrations of CNP and amino-terminal proCNP (NT-proCNP) were measured at baseline in 2129 individuals after an index acute coronary syndrome admission and related to cardiac and renal function, other natriuretic peptides [atrial NP (ANP) and B-type NP (BNP)] and prognosis (primary end point, mortality; secondary end point, cardiac readmission). Median follow-up was 4 years. At baseline, and in contrast to CNP, ANP, and BNP, plasma NT-proCNP was higher in males and weakly related to cardiac function but strongly correlated to plasma creatinine. All NPs were univariately associated with mortality. Resampling at 4 and 12 months in survivors showed stable concentrations of NT-proCNP whereas all other peptides declined. When studied by diagnosis (myocardial infarction, unstable angina) at index admission using a multivariate model, NT-proBNP predicted mortality and readmission in myocardial infarction. In unstable angina, only NT-proCNP predicted both mortality and cardiac readmission.

CONCLUSIONS

In contrast to the close association of NT-proBNP with cardiac function, and predictive value for outcome after myocardial infarction, plasma NT-proCNP is highly correlated with renal function and is an independent predictor of mortality and cardiac readmission in individuals with unstable angina.

Dynamic response of C-type natriuretic peptide and its aminoterminal propeptide (NTproCNP) to growth hormone treatment in children with short stature

OBJECTIVE

C-type natriuretic peptide (CNP) and its aminoterminal propeptide (NTproCNP) are potential biomarkers of recombinant human growth hormone (rhGH) efficacy. The objective of this study was to describe the pharmacodynamics of plasma CNP and NTproCNP levels in response to rhGH treatment and to identify the optimal time of sampling after starting rhGH.

DESIGN

This was a prospective, observational study. Subjects were treated with rhGH for 1 year, with blood sampled at regular intervals.

PATIENTS

Eighteen prepubertal children, eight with low levels of GH on biochemical testing and ten with idiopathic short stature, completed the study.

MEASUREMENTS

Blood levels of CNP, NTproCNP, GH, insulin-like growth factor-I, leptin and bone-specific alkaline phosphatase were measured. Anthropometrics were obtained.

RESULTS

Plasma levels of both CNP and NTproCNP reached peak levels 7-28 days after starting rhGH treatment and then declined to intermediate levels through the first year. Plasma NTproCNP levels after 14 days trended towards a correlation with height velocity after 6 and 12 months of treatment. Unexpectedly, serum GH levels measured 2 and 28 days after starting rhGH correlated strongly with height velocity after 6 and 12 months of treatment.

CONCLUSIONS

This study identified 14 days after starting rhGH treatment as the optimal time for assessing CNP and NTproCNP levels as biomarkers of rhGH efficacy. Additionally, we identified GH levels as a potential biomarker. Larger, prospective studies are now needed to test the clinical utility of these biomarkers.

Serum NT-proCNP levels increased after initiation of GH treatment in patients with achondroplasia/hypochondroplasia

OBJECTIVE

Serum amino-terminal propeptide of C-type natriuretic peptide (NT-proCNP) levels have been proposed as a biomarker of linear growth in healthy children. The usefulness of NT-proCNP in patients with achondroplasia (ACH)/hypochondroplasia (HCH) remains to be elucidated. The objective was to study whether serum NT-proCNP level is a good biomarker for growth in ACH/HCH and other patients of short stature.

DESIGN

This was a longitudinal cohort study.

PATIENTS

Sixteen children with ACH (aged 0·4-4·3 years), six children with HCH (2·7-6·3 years), 23 children with idiopathic short stature (ISS) (2·2-9·0 years), eight short children with GH deficiency (GHD) (2·9-6·8 years) and five short children born small for gestational age (SGA) (2·0-6·6 years). Patients with ACH/HCH received GH treatment for 1 year.

MEASUREMENTS

Serum NT-proCNP levels and height were measured.

RESULTS

NT-proCNP levels positively correlated with height velocity in these short children (P < 0·05, r = 0·27). NT-proCNP levels inversely correlated with age in children with ISS alone (P < 0·01, r = -0·55). Serum NT-proCNP levels in patients with ACH/HCH were increased 3 months following the initiation of GH treatment (P < 0·05). Height SDS gain during GH treatment for 1 year was positively correlated with the changes in NT-proCNP levels after the initiation of GH (P < 0·01, r = 0·72).

CONCLUSION

Serum NT-proCNP levels may be a good biomarker to indicate the effect of GH treatment on growth in patients with ACH/HCH at least in the first year and height velocity in short stature patients.

Furin as proprotein convertase and its role in normal and pathological biological processes

Furin belongs to serine intracellular Ca2+-dependent endopeptidases of the subtilisin family, also known as proprotein convertase (PC). Human furin is synthesized as zymogen with a molecular weight of 104 kDa, which is then activated by autocatalytic in two stages. This process can occur when zymogen migrates from the endoplasmic reticulum to the Golgi apparatus, where a large part of furin is accumulated. The molecular weigh t of the active furin is 98 kDa. Furin relates to enzymes with a narrow substrate specificity: it hydrolyzes peptide bonds at the site of paired basic amino acids and furin activity exhibits in a wide pH range 5-8. Its main biological function is activation of the functionally important protein precursors. It is accompanied by the launch of a cascade of reactions, which lead to appearance of biologically active molecules involved in realization of specific biological functions both in normal and in some patologicheskih processes. Furin substrates are biologically important proteins such as enzymes, hormones, growth factors and differentiation, receptors, adhesion proteins, proteins of blood plasma. Furin plays an important role in the development of processes such as proliferation, invasion, cell migration, survival, maintenance of homeostasis, embryogenesis, as well as the development of a number of pathologies, including cardiovascular, oncologic and neurodegenerative diseases. Furin and furin-like proprotein convertases participate as key factors in the realization of the regulatory functions of proteolytic enzymes, the value of which is currently being evaluated as most important in comparison with the degradative function of proteases.

Advances in treatment of achondroplasia and osteoarthritis

Achondroplasia (ACH) is the prototype and most common of the human chondrodysplasias. It results from gain-of-function mutations that exaggerate the signal output of the fibroblast growth factor receptor 3 (FGFR3), a receptor tyrosine kinase that negatively regulates growth plate activity and linear bone growth. Several approaches to reduce FGFR3 signaling by blocking receptor activation or inhibiting downstream signals have been proposed. Five show promise in preclinical mouse studies. Two candidate therapies target the extracellular domain of FGFR3. The first is a decoy receptor that competes for activating ligands. The second is a synthetic blocking peptide that prevents ligands from binding and activating FGFR3. Two established drugs, statins and meclozine, improve growth of ACH mice. The strongest candidate therapy employs an analog of C-type natriuretic peptide (CNP), which antagonizes the mitogen-activated-protein (MAP) kinase pathway downstream of the FGFR3 receptor and may also act independently in the growth plate. Only the CNP analog has reached clinical trials. Preliminary results of Phase 2 studies show a substantial increase in growth rate of ACH children after six months of therapy with no serious adverse effects. A challenge for drug therapy in ACH is targeting agents to the avascular growth plate. The application of gene therapy in osteoarthritis offers insights because it faces similar technical obstacles. Major advances in gene therapy include the emergence of recombinant adeno-associated virus as the vector of choice, capsid engineering to target vectors to specific tissues, and development of methods to direct vectors to articular chondrocytes.

Biomarkers for Heart Failure in Asia

Contributions from the Asian biomedical community to knowledge of biomarkers in heart failure have grown rapidly since 2000. Japan has made world-leading contributions in the discovery and application of cardiac natriuretic peptides as biomarkers in heart failure, but there has been rapid growth in reports from China. Contributions also come from Taiwan, South Korea, Singapore, and Hong Kong. Centers in Asia have established clinical cohorts providing powerful platforms for the discovery and validation of biomarkers in heart failure. This century, Asian enquiry into biomarkers in heart failure will include peptides, cytokines, metabolites, nucleic acids, and other analytes.

Cardioprotective effect of metformin against doxorubicin cardiotoxicity in rats

Objective:

The clinical use of doxorubicin, which is a strong antineoplastic agent, is limited due to its cardiotoxic side effects. Metformin is a drug with antihyperglycemic effects, and it has been shown to have a cardioprotective effect on left ventricular function in experimental animal models of myocardial ischemia. The present study investigated the cardioprotective effect of metformin in rats with doxorubicin cardiotoxicity.

Methods:

Wistar albino rats were used in the study. Forty male, 10-week-old Wistar albino rats were randomly divided four groups. The control group rats were intraperitoneally administered saline solution twice a week, four doses in total. The doxorubicin group rats received doxorubicin (4 mg/kg, twice a week, cumulative dose: 16 mg/kg) intraperitoneally. The metformin group rats received metformin (250 mg/kg/day, every day for 14 days) via gavage. The doxorubicin + metformin group rats received doxorubicin and metformin at the same dose. Left ventricular functions were evaluated by using M-mode echocardiography one day after the last dose of doxorubicin. Heart tissue samples were histopathologically examined. Cardiomyocyte apoptosis was detected using in situ terminal deoxynucleotide transferase assay (TUNEL). Serum brain natriuretic peptide and C-type natriuretic peptide levels were measured. Catalase, superoxide dismutase, glutathione peroxidase, and tumor necrosis factor alpha levels were analyzed in the heart tissue. The assumptions of equality of variances and normal distribution were checked for all variables (Shapiro-Wilk test and Q-Q graphics). To identify intergroup differences, one-way variant analysis or the Kruskal-Wallis test was used. A p<0.05 value was accepted as statistically significant.

Results:

Our results showed that doxorubicin treatment caused significant deterioration in left ventricular functions by echocardiography, histological heart tissue damage, and increase in cardiomyocyte apoptosis. Doxorubicin + metformin group showed protection in left ventricular function, elimination of histopathologic change, and reduced of cardiomyocyte apoptosis.

Conclusion:

The present study provided evidence that metformin has cardioprotective effects against doxorubicin cardiotoxicity.

Natriuretic peptides, heart, and adipose tissue: new findings and future developments for diabetes research

Natriuretic peptides (NPs) play a key role in cardiovascular homeostasis, counteracting the deleterious effects of volume and pressure overload and activating antibrotic and antihypertrophic pathways in the heart. N-terminal B-type NP (NT-proBNP) also is a promising biomarker of global cardiovascular risk in the general population, and there is increasing interest on its potential use in diabetic patients for screening of silent cardiovascular abnormalities, cardiovascular risk stratification, and guided intervention. Recently, both atrial NP (ANP) and B-type NP (BNP) have emerged as key mediators in the control of metabolic processes including the heart in the network of organs that regulate energy usage and metabolism. Epidemiological studies have shown that ANP and BNP are reduced in people with obesity, insulin resistance, and diabetes, and this deficiency may contribute to enhance their global cardiovascular risk. Moreover, ANP and BNP have receptors in the adipose tissue, enhance lipolysis and energy expenditure, and modulate adipokine release and food intake. Therefore, low ANP and BNP levels may be not only a consequence but also a cause of obesity, and recent prospective studies have shown that low levels of NT-proBNP and midregional proANP (MR-proANP) are a strong predictor of type 2 diabetes onset. Whether ANP and BNP supplementation may result in either cardiovascular or metabolic benefits in humans remains, however, to be established.

Cardiac fibrosis in end-stage human heart failure and the cardiac natriuretic peptide guanylyl cyclase system: regulation and therapeutic implications

Left ventricular assist device (LVAD) support has been used in the treatment of end-stage heart failure (HF), however use of anti-fibrotic co-therapies may improve prognosis. Natriuretic peptides (NPs) possess anti-fibrotic properties through their receptors, GC-A/GC-B/NPR-C. We sought to evaluate cardiac fibrosis and the endogenous NP system in end-stage HF with and without LVAD therapy and to assess the anti-fibrotic actions of the dual GC-A/-B activator CD-NP in vitro. Collagen (Col) protein content was assessed by Picrosirius Red staining and NPs, NP receptors, and Col I mRNA expression were determined by qPCR in LV tissue from patients in end-stage HF (n=13), after LVAD support (n=5) and in normal subjects (n=6). Col I mRNA and protein levels in cardiac fibroblasts (CFs) pretreated with CD-NP were compared to those of BNP or CNP pretreatment. The LV in end-stage HF was characterized by higher Col I mRNA expression and Col protein deposition compared to normal which was sustained after LVAD support. ANP and BNP mRNA expressions were higher while CNP was lower in end-stage HF LV. GC-A expression did not change while GC-B and NPR-C increased compared to normal LV. The changes in NP system expression were not reversed after LVAD support. In vitro, CD-NP reduced Col I production stimulated by TGF-beta 1 greater than BNP or CNP in CFs. We conclude that the failing LV is characterized by increased fibrosis and reduced CNP gene expression. LVAD support did not reverse Col deposition nor restore CNP production, suggesting a therapeutic opportunity for CD-NP.

C-type natriuretic peptide in complicated pregnancy: increased secretion precedes adverse events

CONTEXT

C-type natriuretic peptide (CNP), a vasoactive product of the endothelium, is markedly increased during placentation in ovine pregnancy and is further stimulated by nutrient restriction. Whether CNP products change in human pregnancy is unknown.

OBJECTIVES

The objective of the study was to compare serial changes in maternal plasma CNP peptides during normal pregnancy with changes in pregnancy complicated by adverse events and relate these to fetal growth and placental CNP content.

DESIGN

This was a prospective observational study undertaken in a tertiary care center.

METHODS

We studied changes in maternal plasma aminoterminal proCNP (NTproCNP) and CNP at monthly intervals, fetal growth, and placental and umbilical plasma CNP peptides in 51 women, 28 of whom experienced an adverse event and 23 were uneventful. Age matched healthy nonpregnant women served as a reference range for NTproCNP.

RESULTS

Compared with nonpregnant women, maternal plasma NTproCNP in an uneventful pregnancy was significantly reduced from first sampling (16 wk gestation) until 36 weeks. In contrast, in complicated pregnancy, levels did not decline and were significantly higher (P < .001 by ANOVA) than in normal pregnancy from 20 weeks. Highest values occurred in women later developing hypertension and fetal growth disorders. Placental concentration of NTproCNP was unrelated to maternal NTproCNP but strongly correlated with cord plasma levels.

CONCLUSIONS

Maternal NTproCNP is significantly raised in women who later exhibit a range of obstetric adverse events. Lack of association with placental concentrations suggests that these changes represent an adaptive response within the maternal circulation to a threatened nutrient supply to the fetus.

Natriuretic peptides: molecular biology, pathophysiology and clinical implications for the cardiologist

Natriuretic peptides (NPs) counter the effects of volume overload or adrenergic activation of the cardiovascular system. They are able to induce arterial vasodilatations, natriuresis and diuresis, and they reduce the activities of the renin-angiotensin-aldosterone system and the sympathetic nervous system. However, in addition to wall stress, other factors have been associated with elevated natriuretic peptide levels. Since 2000, because of their characteristics, NPs have become quantitative plasma biomarkers of heart failure. Nowadays, NPs play an important role not only in the diagnosis of heart failure, but also for a prognostic purpose and a guide to medical therapy. Finally, a new drug that modulates the NP system or recombinant analogs of NPs are now available in patients with heart failure.

Inducible endothelium-derived hyperpolarizing factor: role of the 15-lipoxygenase-EDHF pathway

Endothelium-derived hyperpolarizing factors (EDHFs) regulate vascular tone by contributing to the vasorelaxations to shear stress and endothelial agonists such as bradykinin and acetylcholine. 15(S)-Hydroxy-11,12-epoxyeicosatrienoic acid (15-H-11,12-EETA) and 11(R),12(S),15(S)-trihydroxyeicosatrienoic acid (11,12,15-THETA) are endothelial metabolites of the 15-lipoxygenase (15-LO) pathway of arachidonic acid metabolism and are EDHFs. 11,12,15-THETA activates small conductance, calcium-activated potassium channels on smooth muscle cells causing membrane hyperpolarization, and relaxation. Expression levels of 15-LO in the endothelium regulate the activity of the 15-LO/15-H-11,12-EETA/11,12,15-THETA pathway and its contribution to vascular tone. Regulation of its expression is by transcriptional, translational, and epigenetic mechanisms. Hypoxia, hypercholesterolemia, atherosclerosis, anemia, estrogen, interleukins, and possibly other hormones increase 15-LO expression. An increase in 15-LO results in increased synthesis of 15-H-11,12-EETA and 11,12,15-THETA, increased membrane hyperpolarization, and enhanced contribution to relaxation by endothelial agonists. Thus, the 15-LO pathway represents the first example of an inducible EDHF. In addition to 15-LO metabolites, a number of chemicals have been identified as EDHFs and their contributions to vascular tone vary with species and vascular bed. The reason for multiple EDHFs has evaded explanation. However, EDHF functioning as constitutive EDHFs or inducible EDHFs may explain the need for chemically and biochemically distinct pathways for EDHF activity and the variation in EDHFs between species and vascular beds. This new EDHF classification provides a framework for understanding EDHF activity in physiological and pathological conditions.

Identification and gene expression analyses of natriuretic peptide system in the ovary of goat (Capra hircus)

Natriuretic peptides (NPs) are involved in maintaining cardiovascular and fluid homeostasis, regulating reproductive processes and bone growth, and other numerous functions. To better understand the role of NPs in goat (Capra hircus), in the present study, full-length cDNAs of goat Nppa (natriuretic peptide precursor A), Nppb (natriuretic peptide precursor B) and Nppc (natriuretic peptide precursor C), respectively encoding ANP, BNP and CNP, were cloned from adult goat heart and ovary. The putative prepropeptide ANP (prepro-ANP) and prepro-CNP share a high amino acid sequence identity with other species. Real-time PCR showed that Nppa, Nppb and Nppc were widely expressed in adult goat tissues. The mRNA expression of Nppa and Nppb in the heart was extremely higher compared with other tissues. Nppc mRNA expression in the lung and uterus was also higher than in other tissues. The expression of Nppa, Nppb and Nppc genes was examined at different ovarian follicle stages using RT-PCR. The mRNAs of Nppa and Nppb were detected in secondary follicles as well as in COCs (cumulus-oocyte-complexes) and granulosa cells of antral follicles. However, the mRNA expression of Nppc was observed throughout ovarian follicle development, and it was especially higher in granulosa cells of antral follicles. In vitro, stimulating goat granulosa cells with FSH led to an increase in the expression of Nppc by dose- and time-dependent manners and a rapid decline was induced by LH stimulation, but the expression of Nppa and Nppb did not change after FSH or LH treatment. These results suggest that Nppc is a gonadotropin-induced gene in granulosa cells of goat ovary and CNP may be involved in the regulation of ovarian follicle development and oocyte maturation.

C-type natriuretic peptide: a new cardiac mediator

Natriuretic peptides are endogenous hormones released by the heart in response to myocardial stretch and overload. While atrial and brain natriuretic peptides (ANP, BNP) were immediately considered cardiac hormones and their role was well-characterized and defined in predicting risk in cardiovascular disease, evidence indicating the role of C-type natriuretic peptide (CNP) in cardiovascular regulation was slow to emerge until about 8 years ago. Since then, considerable literature on CNP and the cardiovascular system has been published; the aim of this review is to examine current literature relating to CNP and cardiovascular disease, in particular its role in heart failure (HF) and myocardial infarction (MI). This review retraces the fundamental steps in research that led understanding the role of CNP in HF and MI; from increased CNP mRNA expression and plasmatic concentrations in humans and in animal models, to detection of CNP expression in cardiomyocytes, to its evaluation in human leukocytes. The traditional view of CNP as an endothelial peptide has been surpassed by the results of many studies published in recent years, and while its physiological role is still under investigation, information is now available regarding its contribution to cardiovascular function. Taken together, these observations suggest that CNP and its specific receptor, NPR-B, can play a very important role in regulating cardiac hypertrophy and remodeling, indicating NPR-B as a new potential drug target for the treatment of cardiovascular disease.

Gene expression of C-type natriuretic peptide and of its specific receptor NPR-B in human leukocytes of healthy and heart failure subjects

C-type natriuretic peptide (CNP), a member of the family of natriuretic peptides, is synthesized and secreted from monocytes and macrophages that resulted to be a source of CNP at inflammatory sites. This suggests that special attention should be focused on the possible role of CNP in the immune system, in addition to its effects on the cardiovascular system. The aim of this study was to evaluate the possibility of measuring the mRNA expression of CNP and NPR-B, its specific receptor, in human whole blood samples of healthy (N; n=7) and heart failure (HF; n=7) subjects by Real-Time PCR (RT-PCR). Total RNA was extracted from leukocytes with QIAamp RNA Blood Kit and/or with PAXgene Blood RNA Kit. RT-PCR was performed and optimized for each primer. The experimental results were normalized with the three most stably expressed genes. CNP and NPR-B expression trend was similar in both fresh and frozen human whole blood. Significant higher levels of CNP and NPR-B mRNA expression were found in HF patients with respect to controls (CNP: N=1.23±0.33 vs. HF=6.54±2.09 p=0.027; NPR-B: N=0.85±0.23 vs. HF=5.31±1.98 p=0.04). A significant correlation between CNP and NPR-B (r=0.86, p<0.0001) was observed. Further studies are needed to clarify the pathophysiological properties of this peptide but the possibility to measure CNP and NPR-B mRNA expression in human leukocytes with a fast and easy procedure is a useful starting point for future investigation devoted to better understand the biomolecular processes associated to different diseases.

Mid-regional pro-atrial natriuretic peptide as a prognostic marker for all-cause mortality in patients with symptomatic coronary artery disease

In the present study, we investigated the prognostic value of MR-proANP (mid-regional pro-atrial natriuretic peptide). We consecutively evaluated a catheterization laboratory cohort of 2700 patients with symptomatic CAD (coronary artery disease) [74.1% male; ACS (acute coronary syndrome), n=1316; SAP (stable angina pectoris), n=1384] presenting to the Cardiology Department of a large primary care hospital, all of whom underwent coronary angiography. Serum MR-proANP and other laboratory markers were sampled at the time of presentation or in the catheterization laboratory. Clinical outcome was assessed by hospital chart analysis and telephone interviews. The primary end point was all-cause death at 3 months after enrolment. Follow-up data were complete in 2621 patients (97.1%). Using ROC (receiver operating characteristic) curves, the AUC (area under the curve) of 0.73 [95% CI (confidence interval), 0.67-0.79] for MR-proANP was significantly higher compared with 0.58 (95% CI, 0.55-0.62) for Tn-I (troponin-I; DeLong test, P=0.0024). According to ROC analysis, the optimal cut-off value of MR-proANP was at 236 pmol/l for all-cause death, which helped to find a significantly increased rate of all-cause death (n=76) at 3 months in patients with elevated baseline concentrations (≥236 pmol/l) compared with patients with a lower concentration level in Kaplan-Meier survival analysis (log rank, P<0.001). The predictive performance of MR-proANP was independent of other clinical variables or cardiovascular risk factors, and superior to that of Tn-I or other cardiac biomarkers (all: P<0.0001). MR-proANP may help in the prediction of all-cause death in patients with symptomatic CAD. Further studies should verify its prognostic value and confirm the appropriate cut-off value.

FGFR3 targeting strategies for achondroplasia

Mutations that exaggerate signalling of the receptor tyrosine kinase fibroblast growth factor receptor 3 (FGFR3) give rise to achondroplasia, the most common form of dwarfism in humans. Here we review the clinical features, genetic aspects and molecular pathogenesis of achondroplasia and examine several therapeutic strategies designed to target the mutant receptor or its signalling pathways, including the use of kinase inhibitors, blocking antibodies, physiologic antagonists, RNAi and chaperone inhibitors. We conclude by discussing the challenges of treating growth plate disorders in children.