Increased levels of soluble corin in pre-eclampsia and fetal growth restriction

Molecular insights into the corin function at the uteroplacental interface

In pregnancy, cell-cell interactions and tissue remodeling are important physiological processes at the uteroplacental interface. To date, molecular mechanisms governing cell activities at the uteroplacental interface are not fully understood. Corin is a proteolytic enzyme responsible for activating atrial natriuretic peptide (ANP), a multifunctional hormone essential for cardiovascular and metabolic homeostasis. Upon progesterone stimulation, corin expression is induced in the uterus via a specific set of transcription factors. Uterine corin activates ANP to enhance decidualization and cell-cell interactions within the vasculature, leading to sequential vascular smooth muscle and endothelial cell death in spiral arteries. These events are crucial for uterine vascular remodeling and trophoblast invasion. Corin also functions in the decidua to regulate macrophage distribution and function in response to placental ischemia. In mice, Corin knockout impairs endometrial decidualization, vascular remodeling, and macrophage function at the uteroplacental interface, causing a preeclampsia (PE)-like phenotype. In humans, deleterious variants and impaired epigenetic modifications in the CORIN gene have been reported in women with PE, indicating that corin deficiency may be a contributing factor in the pathogenesis of PE. In this review, we describe the corin function at the uteroplacental interface and underlying molecular mechanisms. We also discuss potential implications of corin deficiency in pregnancy-associated diseases.

High Serum Adrenomedullin and Mid-Regional Pro-Atrial Natriuretic Peptide Concentrations in Early Pregnancy Predict the Development of Gestational Hypertension

OBJECTIVES

Adrenomedullin (AM) and natriuretic peptide levels are elevated in pre-eclampsia. The aim of the present study was to determine AM and natriuretic peptide concentrations before 20 weeks of pregnancy in women who later developed gestational hypertension and in normal pregnancies.

METHODS

95 pregnant Caucasian women were included in the study. Gestational hypertension (GH) was diagnosed in 18 patients. The control group consisted of 41 patients with normal pregnancies (non-GH). Blood samples were taken during the first trimester of pregnancy.

RESULTS

Analysis of NT-proBNP showed no significant differences between the group of patients who later developed GH and those with normal pregnancies. Patients who developed GH later in pregnancy had higher levels of both MR-proANP (p < 0.001) and adrenomedullin (p < 0.001). Higher levels of MR-proANP were found in the GH with pre-eclampsia group compared with the GH without pre-eclampsia group. Higher levels of AM (p < 0.05) and MR-proANP (p < 0.005) correlated with the risk of preterm birth.

CONCLUSIONS

(1) Plasma adrenomedullin and MR-proANP concentrations were higher before the 20th week of pregnancy in women who later developed GH; (2) NT-proBNP concentrations did not differ between women with pregnancy-induced hypertension and normal pregnancies; (3) MR-proANP concentrations were highest in patients who developed pre-eclampsia in advanced pregnancy; and (4) there was a correlation between higher plasma adrenomedullin, MR-proANP concentrations before the 20th week of pregnancy, and the risk of preterm birth.

Plasma Corin: A New Biochemical Marker for Polycystic Ovary Syndrome

INTRODUCTION

Polycystic ovary syndrome (PCOS) is a prevalent endocrine disorder. Atrial natriuretic peptide (ANP) is a risk factor for PCOS. Corin protein has an essential role in ANP synthesis. This study aimed to evaluate corin as a sensitive biomarker for PCOS.

MATERIALS AND METHODS

A case-control study was conducted with 70 PCOS patients and 70 healthy females. Plasma Corin levels were quantified using enzyme-linked immunosorbent assay.

RESULTS

The median plasma corin levels in PCOS patients and controls were 1785 and 822.5 pg/mL, respectively. Plasma corin levels were significantly elevated in PCOS patients than in the controls (p < 0.001). The optimal cut-off value was set at 1186 pg/mL. The sensitivity and specificity of Corin were 100% and 97.1%, respectively. Plasma corin levels were surrogate predictors for infertility in women with PCOS. It had an odds ratio of 5.9 (95% confidence interval: 1.1-32.7) (p = 0.04). Plasma corin levels were more highly detected in patients with PCOS than in the controls.

CONCLUSION

Plasma corin level has reasonable diagnostic interpretation for PCOS. Corin appears as a worthy distinct predictor of infertility in PCOS women. Therefore, Corin may be a substantial biomarker for PCOS.

Investigating the Effects of Atrial Natriuretic Peptide on the Maternal Endothelium to Determine Potential Implications for Preeclampsia

Preeclampsia is associated with an increased lifelong risk of cardiovascular disease (CVD). It is not clear whether this is induced by persistent systemic organ and vascular damage following preeclampsia or due to a predisposition to both conditions that share cardiovascular pathophysiology. Common to both CVD and preeclampsia is the dysregulation of corin and its proteolytic product, atrial natriuretic peptide (ANP). ANP, a hypotensive hormone converted from pro-ANP by corin, is involved in blood pressure homeostasis. While corin is predominantly a cardiac enzyme, both corin and pro-ANP are significantly upregulated in the gravid uterus and dysregulated in preeclampsia. Relatively little is known about ANP function in the endothelium during a pregnancy complicated by preeclampsia. Here, we investigated the effect of ANP on endothelial cell proliferation and migration, markers of endothelial dysfunction, and receptor expression in omental arteries exposed to circulating preeclamptic toxins. ANP receptor expression is significantly upregulated in preeclamptic vasculature but not because of exposure to preeclampsia toxins tumour necrosis factor α or soluble fms-like tyrosine kinase-1. The supplementation of endothelial cells with ANP did not promote proliferation or migration, nor did ANP improve markers of endothelial dysfunction. The role of ANP in preeclampsia is unlikely to be via endothelial pathways.

Corin-The Early Marker of Preeclampsia in Pregestational Diabetes Mellitus

Preeclampsia (PE) is one of the leading causes of mortality and morbidity in pregnant women. Pregestational diabetes (PGDM) patients are prone to vascular complications and preeclampsia, whereas vascular exposure to hyperglycemia induces inflammation, vascular remodeling, and arterial stiffness. Corin is a serine protease, converting inactive pro-atrial natriuretic peptide (pro-ANP) into an active form. It also promotes salt and water excretion by activating atrial natriuretic peptide (ANP), and significantly increases trophoblast invasion. The study aimed to determine whether corin may be a predictor of PE in a high-risk group-women with long-term PGDM. The nested case-control prospective study involved 63 patients with long-term pregestational type 1 diabetes (PGDM). In total, 17 patients developed preeclampsia (the study group), whereas 43 patients without PE constituted the control group. To assess corin concentration, blood samples were collected at two time points: between 18th-22nd week of gestation and 28th-32nd week of gestation. PE patients presented significantly higher mid-gestation corin levels, urine protein loss in each trimester, serum creatinine in the third trimester, and lower creatinine clearance in the third trimester. The results of our study indicate that serum corin assessment may play a role in predicting preeclampsia. Thus, it may be included in the PE risk calculator, initially in high-risk groups, such as patients with PGDM.

Soluble Corin Predicts the Risk of Cardiovascular Disease

Background

As a key enzyme of the natriuretic peptides system, corin may participate in the development of cardiovascular disease (CVD). Its level in circulation predicted CVD recurrence in patients with myocardial infarction and heart failure, but no study examined this prediction in general populations.

Objectives

This study sought to examine the prospective association between corin and CVD in a community-based population of Chinese adults.

Methods

The Gusu cohort included 2,498 participants (mean age 53 years, 39% men) who were free of CVD at baseline. Serum corin was measured by enzyme-linked immunosorbent assay kits at baseline and CVD events were followed every 2 years for all participants. A competing-risks survival regression model was used to examine the association between serum corin and CVD.

Results

During 10 years of follow-up, 210 participants developed CVD including 88 stroke events. A higher serum corin (after log-transformation) at baseline was significantly associated with an increased risk of CVD (HR: 1.88; P = 0.019) and stroke (HR: 3.19; P = 0.014). Analysis using categorical serum corin (in quartiles) showed that participants in the highest quartile had a 62% and 179% increased risk for CVD (HR: 1.62; P = 0.024) and stroke (HR: 2.79; P = 0.004), respectively, compared with those in the lowest quartile. We did not find a significant association between serum corin and coronary heart disease.

Conclusions

A higher serum corin at baseline predicted a higher risk of CVD events and stroke, but not coronary heart disease, in Chinese adults, independent of conventional risk factors. Serum corin may be a predictor for stroke but the underlying mechanism needs further investigation.

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.

Correlation between N-terminal pro-atrial natriuretic peptide, corin, and target organ damage in hypertensive disorders of pregnancy

The objective was to evaluate the correlation between N‐terminal pro‐atrial natriuretic peptide (NT‐proANP), corin and the severity of target organ injury in hypertensive disorders of pregnancy. A total of 78 women with hypertensive disorders of pregnancy and 49 normotensive pregnancies were enrolled. The clinical characteristics, laboratory index and echocardiogram results were collected. NT‐proANP, corin, sFlt‐1 and PlGF levels were measured. A receiver's operating characteristics (ROC) curve was performed to evaluate the efficacy of predicting target organ injury in the HDP group. The NT‐proANP, corin, and sFlt‐1/PlGF ratio were increased in the HDP group (p < .05). The area under the curve (AUC) predicted by NT‐proANP and corin were larger than sFlt‐1/PlGF ratio (0.779, 0.867, and 0.766, respectively). The creatinine and urine protein were significantly increased, while the estimated glomerular filtration rate (eGFR) was dramatically decreased in the HDP group (p < .05 each). The left atrial diameter (LAD), left atrial volume index (LAVI), left ventricular posterior wall thickness (LVPWT), and left ventricular septal thickness (LVST) were larger in the HDP group (p < .001 each). The NT‐proANP/corin levels were positively correlated with LAD, creatinine, and urine protein, and negatively correlated with eGFR in HDP group (p < .05 each). Multiple regressions demonstrated that NT‐proANP was an independent risk factor of LAD and urine protein, and corin was an independent risk factor of creatinine and eGFR in HDP group. NT‐proANP and corin may be reliable biomarkers for evaluating the severity of target organ damage in the hypertensive disorders of pregnant patients.

A review of biosensors for the detection of B-type natriuretic peptide as an important cardiovascular biomarker

Heart disease, as the most serious threat to human health globally, is responsible for rising mortality rates, largely due to lifestyle and diet. Unfortunately, the main problem for patients at high risk of heart disease is the validation of prognostic tests. To this end, the detection of cardiovascular biomarkers has been employed to obtain pathological and physiological information in order to improve prognosis and early-stage diagnosis of chronic heart failure. Short-term changes in B-type natriuretic peptide are known as a standard and important biomarker for diagnosis of heart failure. The most important problem for detection is low concentration and short half-life in the blood. The normal concentration of BNP in blood is less than 7 nM (25 pg/mL), which increases significantly to more than 80 pg/mL. Therefore, the development of new biosensors with better sensitivity, detection limit, and dynamic range than current commercial kits is urgently needed. This review classifies the biosensors designed for detection of BNP into electrochemical, optical, microfluidic, and lateral-flow immunoassay techniques. The review clearly demonstrates that a variety of immunoassay, aptasensor, enzymatic and catalytic nanomaterials, and fluorophores have been successfully employed for detection of BNP at low attomolar ranges. Dtection of B-type natriuretic peptide with biosensors.

Function and regulation of corin in physiology and disease

Atrial natriuretic peptide (ANP) is of major importance in the maintenance of electrolyte balance and normal blood pressure. Reduced plasma ANP levels are associated with the increased risk of cardiovascular disease. Corin is a type II transmembrane serine protease that converts the ANP precursor to mature ANP. Corin deficiency prevents ANP generation and alters electrolyte and body fluid homeostasis. Corin is synthesized as a zymogen that is proteolytically activated on the cell surface. Factors that disrupt corin folding, intracellular trafficking, cell surface expression, and zymogen activation are expected to impair corin function. To date, CORIN variants that reduce corin activity have been identified in hypertensive patients. In addition to the heart, corin expression has been detected in non-cardiac tissues, where corin and ANP participate in diverse physiological processes. In this review, we summarize the current knowledge in corin biosynthesis and post-translational modifications. We also discuss tissue-specific corin expression and function in physiology and disease.

Altered serum soluble furin and prorenin receptor levels in pregnancies with pre-eclampsia and fetal growth restriction

OBJECTIVE

The proprotein convertase furin is known to be involved in the processing of pro-B-type natriuretic peptide (proBNP) and prorenin receptor (PRR), suggesting that it has a potential function in blood pressure regulation. We investigated the role of furin in the etiology of pre-eclampsia and its related disorder, unexplained fetal growth restriction (FGR) without hypertension.

METHODS

We evaluated serum and placental furin levels in pre-eclampsia, FGR and uncomplicated pregnancy. Additionally, we investigated the correlation between the serum furin levels and products of furin enzymatic activity or clinical parameters.

RESULTS

We demonstrated that the maternal circulation in cases of pre-eclampsia and FGR had lower levels of soluble furin than uncomplicated pregnancies. Both NT-proBNP and soluble PRR were elevated in pre-eclampsia, whereas only soluble PRR was at higher levels in unexplained FGR. Linear regression analysis revealed a negative correlation between the serum furin level and that of NT-proBNP or soluble PRR. While we observed that the serum furin or soluble PRR level correlated with blood pressure, a stronger correlation was observed with birth and placental weights. Further to this, the FURIN mRNA levels were significantly reduced in placental pre-eclamptic placentas as well as in FGR cases.

CONCLUSION

These data suggest the possibility that reduced levels of furin may be the result of a negative feedback from the activation of the renin-angiotensin pathway that leads to feto-placental dysfunction with or without maternal hypertension. This may represent an etiologic pathway of pre-eclampsia and unexplained FGR.

Nested Case-Control Study of Corin Combined with sFlt-1/PLGF in Predicting the Risk of Preeclampsia

Background

Preeclampsia (PE), a serious pregnancy disorder, is responsible for maternal and fetal mortality worldwide. At present, numerous candidate biomarkers have been studied to predict PE.

Objective

To explore the role of Corin in PE risk prediction and then evaluate the predictive ability of soluble vascular endothelial growth factor receptor-1 (sFlt-1), placenta growth factor (PLGF), and sFlt-1/PLGF after the addition of Corin.

Methods

A total of 135 pregnant women from Affiliated Hospital of Shandong University of Traditional Chinese Medicine participated in this study in their first trimester. A nested case–control study was conducted and all subjects were divided into PE groups (n=46) and controls (n=89). The levels of PLGF, sFlt-1, sFlt-1/PLGF ratio, and Corin of the two groups at 12–16 weeks of gestation were measured and analyzed. Receiver operating characteristic (ROC) curve, net reclassification index (NRI) and integrated discrimination index (IDI) were calculated to evaluate the predictive ability of various biomarkers.

Results

The concentrations of sFlt-1, sFlt-1/PLGF, and Corin in PE group were significantly higher than that in controls, while the concentration of PLGF in the PE group was lower. The area under curve (AUC) of sFlt-1, PLGF and sFlt-1/PLGF for predicting PE was 0.786, 0.719 and 0.866, respectively. Combined with Corin, the prediction ability of the above biomarkers could be improved to 0.876, 0.847, and 0.897, respectively. Corin in combination with sFlt-1/PLGF resulted in improvements with 12.6% being reclassified and a resulting NRI of 0.142 (0.020~0.263) and IDI of 0.087 (0.037~0.137).

Conclusion

The addition of Corin to sFlt-1, PLGF and sFlt-1/PLGF can improve the ability of each marker to predict PE risk. Corin in combination with sFlt-1/PLGF can be used as ideal markers to identify the pregnant women who subsequently develop PE, which will help in risk stratification and better therapeutic management.

Correlation between corin, N-terminal pro-atrial natriuretic peptide and neonatal adverse prognostic in hypertensive disorders of pregnancy

INTRODUCTION

Atrial natriuretic peptide (ANP) regulates water-salt balance and blood pressure by promoting renal sodium and water excretion.

OBJECTIVE

Our study was to investigate plasma N-terminal pro-atrial natriuretic peptide (NT-proANP) and corin in hypertensive disorders of pregnancy (HDP) patients. Furthermore, the relationship between corin/NT-proANP and neonatal adverse prognosis were evaluated.

METHODS

Seventy-seven HDP patients and forty-eight normotensive women as control group were recruited. Clinical characteristic and plasma were collected. Plasma NT-proANP and corin were determined by ELISA. Gestational age, neonatal weight and APGAR scores were recorded. Statistical analysis was conducted.

RESULTS

NT-proANP and corin were significantly increased in HDP group compared with that of control (P < 0.05). NT-proANP and corin were significantly elevated in HDP patients who suffered from premature delivery (P < 0.05). Both NT-proANP and corin were negatively associated with delivery time, neonatal weight and APGAR scores in HDP group. Multiple regressions demonstrated that NT-proANP and corin were independent risk factor of delivery time, neonatal weight and APGAR scores.

CONCLUSIONS

Plasma NT-proANP and corin were significantly increased in HDP. NT-proANP and corin were associated with neonatal adverse events in HDP patients. Thus, NT-proANP and corin may become new biomarkers for evaluating severity of pregnancy and neonatal adverse events in HDP patients.

Neural control of blood pressure during pregnancy in humans

PURPOSE

Previous microneurographic studies found that muscle sympathetic nerve activity (MSNA) increased in normotensive pregnant women and was even greater in women with gestational hypertension and preeclampsia during the third trimester. It is possible that sympathetic activation during the latter months of normal pregnancy helps return arterial pressure to non-pregnant levels. However, when the increase in sympathetic activity is excessive, hypertension ensues. The key question that must be addressed is whether sympathetic activation develops early during pregnancy and remains high throughout gestation, or whether this sympathetic overactivity only occurs at term, providing the substrate for preeclampsia and other pregnancy-associated cardiovascular complications.

METHODS

This was a literature review of autonomic neural control during pregnancy.

RESULTS

Recent work from our laboratory and other laboratories showed that in healthy women resting MSNA increased in early pregnancy, increased further in late pregnancy, and returned to the pre-pregnancy levels shortly after delivery. We found that women who exhibited excessive sympathetic activation during the first trimester, before any clinical signs and symptoms appeared, developed gestational hypertension at term. We also found that the level of corin, an atrial natriuretic peptide-converting enzyme, was increased in the maternal circulation, especially during late pregnancy, as a homeostatic response to elevated sympathetic activity.

CONCLUSION

These findings provide important insight into the neural mechanisms underlying hypertensive disorders during pregnancy. With this knowledge, early prevention or treatment targeted to the appropriate pathophysiology may be initiated, which may reduce maternal and fetal death or morbidity, as well as cardiovascular risks in women later in life.

Aberrant corin and PCSK6 in placentas of the maternal hyperinsulinemia IUGR rat model

OBJECTIVES

Corin is a protease that converts pro-atrial natriuretic peptide (pro-ANP) to ANP. While the involvement of ANP in the cardiovascular regulation is well established, there is increasing evidence that the pregnant uterus produces ANP, which promotes spiral artery remodeling. The present study examines the alterations in corin and PCSK6, a key enzyme in the conversion of pro-corin to corin, in the placenta of hyperinsulinemic dams (HD) featuring pregnancy-induced hypertension (PIH).

MATERIALS AND METHODS

The study was conducted on female Wistar rats. Rats were rendered hyperinsulinemic by subcutaneous insulin pellet, mated and followed to the twenty-first day of pregnancy. Normal pregnant dams (NPD) served as controls. Both groups were sacrificed on day 21 of gestation and their placentas were dissected along with the mesometrial triangle (MT). The tissue was then sectioned from the maternal surface to the base of the MT, and processed for histological and molecular biology analysis of Corin, PCSK6 and ANP expression/immunoreactivity.

RESULTS

Hyperinsulinemic dams developed PIH, along lower placental and fetal weights. Corin expression and immunoreactivity were significantly decreased in the placenta by ~40-50%, but not in the MT. Similarly, placental but not MT PCSK6 immunoreactivity was lower in HD. Concomitantly with the downregulation of corin/PCSK6, proANP levels increased in the placenta of HD.

CONCLUSIONS

Corin and PCSK6 are expressed in the placenta and MT. The decline in these two enzymes in the placenta of HD suggests a role of corin/PCSK6 machinery in the development of PIH and intrauterine growth restriction characterizing hyperinsulinemia.

Placental Overexpression of Soluble CORIN in Preeclampsia

Preeclampsia (PE) is a hypertensive disease of pregnancy associated with substantial maternal and fetal morbidity and mortality. CORIN is a transmembrane type II serine protease expressed in cardiomyocytes that converts pro-atrial natriuretic peptide into atrial natriuretic peptide, a cardiac hormone that regulates blood pressure. High levels of soluble CORIN have been reported in PE and are supposed to be cardiac in origin. We hypothesized that during pregnancy soluble CORIN is released by the syncytiotrophoblast and that increased levels of soluble CORIN in preeclampsia originate from placenta. A total of 375 patients (181 PE patients and 194 controls) were analyzed. High levels of soluble CORIN were confirmed in maternal blood from preeclamptic pregnancies compared with controls. Differentiated primary villous cytotrophoblasts showed that CORIN was expressed (mRNA and protein levels) and secreted by trophoblastic cells, mostly by the syncytiotrophoblast. Finally, placental explants showed a significant increase in CORIN production and secretion in PE cases compared with controls. This study showed that CORIN is secreted by trophoblastic cells and that high levels of soluble CORIN in preeclampsia have a placental origin.

Adaptations in autonomic nervous system regulation in normal and hypertensive pregnancy

There is an increase in basal sympathetic nerve activity (SNA) during normal pregnancy; this counteracts profound primary vasodilation. However, pregnancy also impairs baroreflex control of heart rate and SNA, contributing to increased mortality secondary to peripartum hemorrhage. Pregnancy-induced hypertensive disorders evoke even greater elevations in SNA, which likely contribute to the hypertension. Information concerning mechanisms is limited. In normal pregnancy, increased angiotensin II acts centrally to support elevated SNA. Hypothalamic sites, including the subfornical organ, paraventricular nucleus, and arcuate nucleus, are likely (but unproven) targets. Moreover, no definitive mechanisms for exaggerated sympathoexcitation in hypertensive pregnancy have been identified. In addition, normal pregnancy increases gamma aminobutyric acid inhibition of the rostral ventrolateral medulla (RVLM), a key brainstem site that transmits excitatory inputs to spinal sympathetic preganglionic neurons. Accumulated evidence supports a major role for locally increased production and actions of the neurosteroid allopregnanolone as one mechanism. A consequence is suppression of baroreflex function, but increased basal SNA indicates that excitatory influences predominate in the RVLM. However, many questions remain regarding other sites and factors that support increased SNA during normal pregnancy and, more importantly, the mechanisms underlying excessive sympathoexcitation in life-threatening hypertensive pregnancy disorders such as preeclampsia.

Role of Corin in Blood Pressure Regulation in Normotensive and Hypertensive Pregnancy

Corin (an atrial natriuretic peptide-converting enzyme) represents a potential biomarker for gestational hypertensive disorders; yet, its role in blood pressure (BP) regulation throughout pregnancy remains unclear. We investigated the time course of change in blood corin content in relation to BP and sympathetic nerve activity throughout pregnancy. Forty-four women (29±0.9 years) participated. Following-term, 23 had low-risk (no personal history of gestational hypertensive disorders) normal pregnancies, 13 had high-risk (personal history of gestational hypertensive disorders) normal pregnancies, and 8 developed gestational hypertension. BP, heart rate, muscle sympathetic nerve activity, and serum corin were measured before pregnancy, during early (4-8 weeks) and late pregnancy (32-36 weeks), and postpartum (6-10 weeks). Overall, compared with prepregnancy, corin remained unchanged during early pregnancy, increased markedly during late pregnancy ( P<0.001), and returned to prepregnancy levels postpartum. In women who developed gestational hypertension, the change in corin from early to late pregnancy was greater than those with low-risk normal pregnancies (Δ971±134 versus Δ486±79 pg/mL; P<0.05). Throughout pregnancy, BP and muscle sympathetic nerve activity were augmented in women with gestational hypertension (all P<0.05). Finally, changes in corin from early to late pregnancy were related to all indices of BP ( R=0.454-0.551; all P<0.01) in late pregnancy, whereas burst frequency, burst incidence, and total muscle sympathetic nerve activity ( R=0.576-0.614; all P<0.001) in early pregnancy were related to changes in corin from early to late pregnancy. Corin plays a unique role in BP regulation throughout normotensive and, especially, hypertensive pregnancy and may represent a promising biomarker for determining women at high risk of adverse pregnancy outcome.

The role of G protein-associated estrogen receptor (GPER) 1, corin, raftlin, and estrogen in etiopathogenesis of intrauterine growth retardation

Objective: The aim of the present study was to detect the role of G protein-associated estrogen receptor (GPER) 1, corin, raftlin and estrogen in etiopathogenesis of intrauterine growth retardation (IUGR).Materials and methods: The present study was designed prospectively between January 2017 and May 2018. The study group included 32 patients with unexplained IUGR and 32 healthy pregnant women who gave birth at term among the patients who referred to obstetrics clinic of a tertiary reference hospital. Intrauterine growth retardation (IUGR) was accepted as birth weight below 10th percentile according to the estimated fetal weight. Exclusion criteria were as follows: the patients with renal or hepatic dysfunction, presence of any chronic disease, smoker patients, preeclampsia, acute or chronic inflammatory diseases, body mass index as <18 kg/m² and >25 kg/m², structural or chromosomal abnormality in fetus Estradiol (E2), estriol (E3), GPER, corin, and raftlin levels were analyzed in maternal serum and placental tissue homogenate through ELISA method.Results: Serum levels of GPER-1, raftlin, and E3 were significantly lower in IUGR group when compared with the control group (p < .05 for all). Serum corin and E2 levels were similar between two groups. GPER-1, E2, E3, raftlin, and corin levels in placental homogenate were found significantly higher in the control group (p < .05 for all).Conclusion: Although maternal, fetal, and placental causes take place in etiopathogenesis of IUGR, exact etiological factor is not revealed in majority of the IUGR cases. The present study serves as the first study revealing the role of the decrease in GPER-1 and raftlin in maternal serum and placental levels on the etiopathogenesis of IUGR. Furthermore, the decrease in placental corin expression of the cases with IUGR was detected first in the literature. The present study reveals a potential therapeutic use of GPER-1, corin, and raftlin for IUGR.

Increases in plasma corin levels following experimental myocardial infarction reflect the severity of ischemic injury

Following acute myocardial infarction, clinical studies show alterations in the blood levels of corin, a cardiac-selective activator of the natriuretic peptides pro-atrial natriuretic peptide (pro-ANP) and pro-B-type natriuretic peptide (pro-BNP). However, the temporal changes in circulating and cardiac corin levels and their relationships to the severity of myocardial infarction have not been studied. The main objective of this study was to examine the relationship between cardiac and circulating corin levels and their association with cardiac systolic function and infarct size during the early phase of acute myocardial infarction (<72 h) in a translationally relevant induced coronary ligation mouse model. This acute phase timeline was chosen to correlate with the clinical practice within which blood samples are collected from myocardial infarction patients. Heart and plasma samples were examined at 3, 24, and 72 hours post acute myocardial infarction. Plasma corin levels were examined by enzyme-linked immunosorbent assay, transcripts of cardiac corin, pro-ANP and pro-BNP by quantitative real-time polymerase chain reaction, cardiac corin expression by immunohistology, infarct size by histology and heart function by echocardiography. Plasma corin levels were significantly increased at 3 (P<0.05), 24 (P<0.001), and 72 hours (P<0.01) post-acute myocardial infarction. In contrast, cardiac corin transcript levels dropped by 5% (P>0.05), 69% (P<0.001) and 65% (P<0.001) and immunoreactive cardiac corin protein levels dropped by 30% (P<0.05), 76% (P<0.001) and 75% (P<0.001), while cardiac pro-ANP and pro-BNP transcript levels showed an opposite pattern. Plasma corin levels were negatively correlated with immunoreactive cardiac corin (P<0.01), ejection fraction (P<0.05) and fractional shortening (P<0.05), but positively correlated with infarct size (P<0.01). In conclusion, acute myocardial infarction induces rapid increases in plasma corin and decreases in cardiac corin levels. In the early phase of acute myocardial infarction, plasma corin levels are inversely correlated with heart function and may reflect the severity of myocardial damage.

Brain Natriuretic Peptide and Its Biochemical, Analytical, and Clinical Issues in Heart Failure: A Narrative Review

Heart failure (HF) is a primary cause of morbidity and mortality worldwide. As the most widely studied and commonly applied natriuretic peptide (NP), B-type natriuretic peptide (BNP) has the effects of diuresis, natriuresis, vasodilation, anti-hypertrophy, and anti-fibrosis and it inhibits the renin-angiotensin-aldosterone and sympathetic nervous systems to maintain cardiorenal homeostasis and counteract the effects of HF. Both BNP and N-terminal pro B-type natriuretic peptide (NT-proBNP) are applied as diagnostic, managing, and prognostic tools for HF. However, due to the complexity of BNP system, the diversity of BNP forms and the heterogeneity of HF status, there are biochemical, analytical, and clinical issues on BNP not fully understood. Current immunoassays cross-react to varying degrees with pro B-type natriuretic peptide (proBNP), NT-proBNP and various BNP forms and cannot effectively differentiate between these forms. Moreover, current immunoassays have different results and may not accurately reflect cardiac function. It is essential to design assays that can recognize specific forms of BNP, NT-proBNP, and proBNP to obtain more clinical information. Not only the processing of proBNP (corin/furin) and BNP (neprilysin), but also the effects of glycosylation on proBNP processing and BNP assays, should be targeted in future studies to enhance their diagnostic, therapeutic, and prognostic values.

Short-Term High-Salt Diet Increases Corin Level to Regulate the Salt-Water Balance in Humans and Rodents

BACKGROUND

Dietary sodium and potassium affect the fluctuation in blood pressure (BP) and renal function. Corin, with its enzymatic activity to convert pro-atrial natriuretic peptide (pro-ANP) to biologically active ANP, regulates BP, cardiac, and renal functions. We investigated whether corin expression responds to a high-salt (HS) diet to regulate salt and water balance.

METHODS

Forty-two volunteers followed 3 sequential diets for 7 days each: a low-salt (LS) diet (3.0 g/day NaCl), a HS diet (18.0 g/day NaCl), followed by an HS diet with K+ supplementation (HS + K+) (18.0 g/day NaCl and 4.5 g/day KCl).

RESULTS

Corin level was higher with the HS diet than the LS and HS + K+ diets and was positively correlated with systolic BP (SBP) and 24-hour urinary Na+ and microalbumin (U-mALB) excretion. In rodents, serum and renal levels of corin were transiently increased with the HS diet and were decreased if the HS diet was continued for up to 7 days. HS loading increased SBP, 24-hour urinary Na+, U-mALB excretion, and the expression of proprotein convertase subtilisin/kexin-6 (PCSK6), a corin activator. Knockdown of PCSK6 or corin in high salt-treated M1-cortical collecting duct (M1-CCD) cells increased the expression of aquaporin 2 (AQP2) and β-epithelial Na+ channel (β-ENaC).

CONCLUSIONS

Short-term HS may induce the PCSK6-corin-ANP-AQP2/β-ENaC pathway in the kidney. Enhanced serum corin level in humans and rodents is positively correlated with HS-induced SBP and 24-hour urinary Na+ and U-mALB excretion, which suggests that corin is involved in the salt-water balance in response to HS intake.

CLINICAL TRIALS REGISTRATION

Public Trials Registry Number NCT02915315.

Aberrant pro-atrial natriuretic peptide/corin/natriuretic peptide receptor signaling is present in maternal vascular endothelium in preeclampsia

OBJECTIVE

Corin is a serine protease that converts pro-atrial natriuretic peptide (pro-ANP) to atrial natriuretic peptide (ANP), a cardiac hormone that regulates salt-water balance and blood pressure. ANP is degraded by natriuretic peptide receptor (NPR). This study was to determine if aberrant pro-ANP/corin/NPR signaling is present in maternal vascular system in preeclampsia.

STUDY DESIGN

Maternal venous blood was obtained from 197 pregnant women (84 normotensive, 16 complicated with chronic hypertension (CHT), 11 mild and 86 severe preeclampsia). Plasma corin and pro-ANP concentrations were measured by enzyme-linked immunosorbent assay. Maternal subcutaneous fat tissue was obtained from 12 pregnant women with cesarean section delivery (6 normotensive and 6 preeclampsia). Vascular ANP and its receptors NPR-A, NPR-B, and NPR-C expression were examined by immunostaining of paraffin embedded subcutaneous fat tissue sections.

RESULTS

Corin concentrations were significantly higher in mild (2.78 ± 0.67 ng/ml, p < .05) and severe (2.53 ± 0.18 ng/ml, p < .01) preeclampsia than in normotensive (1.58 ± 0.08 ng/ml) and CHT (1.55 ± 0.20 ng/ml) groups. Pro-ANP concentrations were significantly higher in CHT (1.59 ± 0.53 ng/ml, p < .05) and severe preeclampsia (1.42 ± 0.24 ng/ml, p < .01) than in normotensive (0.48 ± 0.06 ng/ml) and mild preeclampsia (0.52 ± 0.09 ng/ml) groups. ANP and NPR-B expression was undetectable in maternal vessels from normotensive and preeclamptic pregnancies, but reduced NPR-A expression and increased NPR-C expression was found in maternal vessel endothelium in preeclampsia.

CONCLUSIONS

ANP is a vasodilator and NPR-C is a clearance receptor for ANP. The finding of upregulation of NPR-C expression suggests that circulating ANP clearance or degradation is increased in preeclampsia. These results also suggest that pro-ANP/corin/NPR signaling is dominant in the vascular system in preeclampsia.