Serum corin is reduced and predicts adverse outcome in non-ST-elevation acute coronary syndrome

Serum Soluble Corin and Long-Term Clinical Outcomes After Acute Ischemic Stroke

BACKGROUND

Corin plays important roles in the regulation of blood volume and pressure and cardiac function by activating natriuretic peptide pathway, exerting multiple cardioprotective effects. But the impacts of soluble corin on clinical outcomes after ischemic stroke are unclear. We aimed to investigate the associations between serum soluble corin and long-term clinical outcomes after acute ischemic stroke.

METHODS AND RESULTS

We measured the concentrations of serum soluble corin in 3162 participants (2010 men and 1152 women) from the China Antihypertensive Trial in Acute Ischemic Stroke. The clinical outcomes were recurrent stroke, cardiovascular events, all-cause mortality, and unfavorable functional outcome within 24 months after stroke. Risk reclassification for study clinical outcomes of models with soluble corin were evaluated. Serum soluble corin was inversely associated with recurrent stroke, cardiovascular events, and unfavorable functional outcome after ischemic stroke. After adjusting for multiple covariates, each additional SD of log-corin was associated with a 21% (95% CI, 11-30), 16% (95% CI, 6-26), and 12% (95% CI, 3-21) decreased risk for recurrent stroke, cardiovascular events, and unfavorable functional outcome, respectively. Furthermore, the addition of soluble corin to the basic model with conventional risk factors significantly improved risk discrimination for recurrent stroke, cardiovascular events, and the composite outcome of all-cause mortality and cardiovascular events, as shown by C-statistics (all P<0.05).

CONCLUSIONS

Serum soluble corin was associated with decreased risks of long-term clinical outcomes, and may be a promising prognostic biomarker for risk stratification in patients with acute ischemic stroke.

Circulating corin concentration is associated with risk of mortality and acute kidney injury in critically ill patients

Elevated serum corin concentrations in patients with cardiac diseases have been associated with adverse cardiovascular events and progressive renal dysfunction. This study aimed to determine the role of serum corin levels in predicting the incidence of acute kidney injury (AKI) and mortality in critically ill patients admitted to intensive care units (ICUs). We screened 323 patients admitted to the ICU in our institution from May 2018 through December 2019. After excluding patients receiving renal replacement therapy, 288 subjects were enrolled. Cases were divided equally into high (n = 144) and low (n = 144) corin groups according to median serum corin levels, using 910 pg/mL as the cut-off point. Patient characteristics and comorbidities were collected from medical records. The primary outcome was AKI within 48 h after ICU admission, while the secondary outcome was all-cause of mortality within 1 year. Compared with the low corin group, patients in the high corin group had higher prevalence rates of diabetes, cirrhosis, and nephrotoxic agent exposure; higher Sequential Organ Failure Assessment scores, white blood cell counts, proteinuria, and serum N-terminal pro-brain natriuretic peptide levels; but had lower initial estimated glomerular filtration rates. Furthermore, elevated serum corin was associated with higher risks of AKI within 48h of ICU admission (43.1% vs. 18.1%, p < 0.001) and all-cause mortality within one year (63.9% vs. 50.0%, p = 0.024). High corin level showed strongly positive results as an independent predictor of AKI (OR 2.15, 95% CI 1.11-4.19, p = 0.024) but not for the all-cause mortality after adjusting for confounding factors in multivariate analyses. Elevated circulating corin predicted AKI in critically ill patients, but did not predict all-cause mortality within 1 year. As a key enzyme in renin-angiotensin-aldosterone system, corin expression may be regulated through a feedback loop following natriuretic peptide resistance and desensitization of natriuretic peptide receptors in different critically ill status.

A Prediction Model for Rapid Identification of Ischemic Stroke: Application of Serum Soluble Corin

Objective

Rapid identification is critical for ischemic stroke due to the very narrow therapeutic time window. The objective of this study was to construct a diagnostic model for the rapid identification of ischemic stroke.

Methods

A mixture population constituted of patients with ischemic stroke (n = 481), patients with hemorrhagic stroke (n = 116), and healthy individuals from communities (n = 2498) were randomly resampled into training (n = 1547, mean age: 55 years, 44% males) and testing (n = 1548, mean age: 54 years, 43% males) samples. Serum corin was assayed using commercial ELISA kits. Potential risk factors including age, sex, education level, cigarette smoking, alcohol consumption, obesity, blood pressure, lipids, glucose, and medical history were obtained as candidate predictors. The diagnostic model of ischemic stroke was developed using a backward stepwise logistic regression model in the training sample and validated in the testing sample.

Results

The final diagnostic model included age, sex, cigarette smoking, family history of stroke, history of hypertension, systolic blood pressure, total cholesterol, high-density lipoprotein cholesterol, fasting glucose, and serum corin. The diagnostic model exhibited good discrimination in both training (AUC: 0.910, 95% CI: 0.884-0.936) and testing (AUC: 0.907, 95% CI: 0.881-0.934) samples. Calibration curves showed good concordance between the observed and predicted probability of ischemic stroke in both samples (all P>0.05).

Conclusion

We developed a simple diagnostic model with routinely available variables to assist rapid identification of ischemic stroke. The effectiveness and efficiency of this model warranted further investigation.

Edema formation in congestive heart failure and the underlying mechanisms

Congestive heart failure (HF) is a complex disease state characterized by impaired ventricular function and insufficient peripheral blood supply. The resultant reduced blood flow characterizing HF promotes activation of neurohormonal systems which leads to fluid retention, often exhibited as pulmonary congestion, peripheral edema, dyspnea, and fatigue. Despite intensive research, the exact mechanisms underlying edema formation in HF are poorly characterized. However, the unique relationship between the heart and the kidneys plays a central role in this phenomenon. Specifically, the interplay between the heart and the kidneys in HF involves multiple interdependent mechanisms, including hemodynamic alterations resulting in insufficient peripheral and renal perfusion which can lead to renal tubule hypoxia. Furthermore, HF is characterized by activation of neurohormonal factors including renin-angiotensin-aldosterone system (RAAS), sympathetic nervous system (SNS), endothelin-1 (ET-1), and anti-diuretic hormone (ADH) due to reduced cardiac output (CO) and renal perfusion. Persistent activation of these systems results in deleterious effects on both the kidneys and the heart, including sodium and water retention, vasoconstriction, increased central venous pressure (CVP), which is associated with renal venous hypertension/congestion along with increased intra-abdominal pressure (IAP). The latter was shown to reduce renal blood flow (RBF), leading to a decline in the glomerular filtration rate (GFR). Besides the activation of the above-mentioned vasoconstrictor/anti-natriuretic neurohormonal systems, HF is associated with exceptionally elevated levels of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP). However, the supremacy of the deleterious neurohormonal systems over the beneficial natriuretic peptides (NP) in HF is evident by persistent sodium and water retention and cardiac remodeling. Many mechanisms have been suggested to explain this phenomenon which seems to be multifactorial and play a major role in the development of renal hyporesponsiveness to NPs and cardiac remodeling. This review focuses on the mechanisms underlying the development of edema in HF with reduced ejection fraction and refers to the therapeutic maneuvers applied today to overcome abnormal salt/water balance characterizing HF.

Low serum corin levels predict end-organ damage in patients with hypertensive crisis

OBJECTIVE

The study aimed to investigate the predictive power of serum corin levels for distinguishing between hypertensive urgency (HU) and hypertensive emergency (HE) in patients with hypertensive crisis (HC) admitted to the emergency department.

METHODS

A total of 120 consecutive consenting adult patients diagnosed with HC and 55 age- and sex-matched healthy controls were enrolled. Blood pressure measurements [(systolic, diastolic, and mean arterial pressure (MAP)] and the evidence of end-organ damage at the first admission were recorded. Patients with HC were classified as patients with HE or HU according to the presence or absence of acute end-organ damage. Serum corin levels were compared between the 2 groups.

RESULTS

The mean serum corin level was significantly lower in the HC group than in the control group; it was also lower in the HE group than in the HU group (p<0.001 for all). In the HE group, clinical features associated with end-organ damage included ST-elevation myocardial infarction (n=28, 46.7%), hemorrhagic stroke (n=11, 18.3%), ischemic stroke (n=11, 18.3%), and non-ST-elevation myocardial infarction (n=10, 16.7%). The receiving operator characteristic (ROC) analysis identified a serum corin cutoff value of 45 pg/mL for distinguishing patients with HE from patients with HU with 98.3% sensitivity and 95% specificity.

CONCLUSION

Our findings suggest that serum corin levels play an important role in regulating blood pressure and are involved in the pathogenesis of HC. Low serum corin levels may predict end-organ damage and serve as a guide for diagnostic decision making in patients with HC.

Serum PCSK6 and corin levels are not associated with cardiovascular outcomes in patients undergoing coronary angiography

Introduction

Proprotein convertase subtilisin/kexin-6 (PCSK6) is a secretory protein that activates corin in the heart. Higher circulating levels of corin are associated with improved cardiovascular outcomes in patients with acute myocardial infarction. This study aimed to determine the role of serum PCSK6 and corin levels in predicting cardiovascular outcomes in patients with suspected coronary artery disease (CAD).

Materials and methods

In total, 565 patients who had undergone coronary angiography were enrolled. Serum PCSK6 and corin levels were determined before the administration of contrast media. In this study, coronary revascularization, acute myocardial infarction, acute stroke, and death were defined as cardiovascular outcomes. All patients were followed up for at least one year after coronary angiography or until the occurrence of death.

Results

During a median follow-up of 691 days, 67 patients (15.7%) developed composite cardiovascular outcomes after coronary angiography, including 51 incidents of coronary revascularization, 7 instances of acute myocardial infarction, 2 acute strokes, and 15 deaths. After adjustment for demographic characteristics and all significant variables in the univariate analysis, serum levels of neither PCSK6 nor corin were associated with increased risk for cardiovascular outcomes. This correlation remained insignificant in patients with underlying hypertension, diabetes mellitus, CAD, heart failure, or chronic kidney disease (CKD). However, in patients without CKD, higher serum PCSK6 levels were associated with increased risk for cardiovascular outcomes (hazard ratio 1.380; 95% confidence interval 1.023–1.862).

Conclusions

We found no association between cardiovascular outcomes and pre-procedural serum levels of PCSK6 or corin in patients undergoing coronary angiography. However, an increased risk was seen in non-CKD patients with higher PCSK6 levels. Further studies are needed to verify these results.

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.

Smoking modifies the effect of two independent SNPs rs5063 and rs198358 of NPPA on central obesity in the Chinese Han population

Obesity is the third most risk factors of death in the middle-income and high-income countries. Whether DNA polymorphisms in CORIN and NPPA genes were associated with obesity, and if these associations could be modified by smoking in the Chinese Han population were unknown, hence a group of 1507 participants were recruited and genotyped for 12 tag single-nucleotide polymorphisms (SNPs) of CORIN and NPPA genes. Regression models were used to test the associations of SNPs with obesity. The potential SNP-smoking interactions were detected in regression models. NPPA SNPs rs5063 and rs198358 were associated with the body mass index (BMI) (P = 0.0053 and 0.0037, respectively). Rs198358 was associated with obesity in both univariate- and multivariable-adjusted analyses (P = 0.0138 and 0.0173, respectively). Rs5063 was associated with central obesity in both univariate- and multivariable-adjusted analyses (P = 0.0454 and 0.0361, respectively). Significant interactions between cigarette smoking and rs5063 and rs198358 were detected (P = 0.0019 and 0.0006, respectively). In subgroup analyses, rs5063 and rs198358 were associated with central obesity in smokers (P = 0.0081 and 0.0037, respectively). The results of our study demonstrated that the effect of NPPA SNPs rs5063 and rs198358 on central obesity might be modified by smoking in the Chinese Han population. Further studies are needed to confirm the associations and elucidate the underlying mechanisms.

Serum Corin Level Is Associated With Subsequent Decline in Renal Function in Patients With Suspected Coronary Artery Disease

BACKGROUND

Higher circulatory corin in patients with cardiac diseases is associated with improved cardiovascular outcomes, and chronic cardiac dysfunction is a well-known cause of progressive renal dysfunction. This study aimed to determine the role of serum corin in predicting short-term and long-term renal outcomes after contrast exposure in patients with suspected coronary artery disease.

METHODS AND RESULTS

Four hundred one patients who had received coronary angiography were enrolled. Serum corin levels were determined before administration of contrast media. Contrast-induced nephropathy was defined as a rise in serum creatinine of 0.5 mg/dL or a 25% increase from baseline within 48 hours after the procedure. Progressive renal dysfunction was defined as >50% decrease in estimated glomerular filtration rate after discharge. All patients were followed up for at least 1 year or until the occurrence of death after coronary angiography. Overall, contrast-induced nephropathy occurred in 23 (5.7%) patients. During a median follow-up of 529 days, 44 (11.0%) cases had subsequent decline in renal function. After adjustment for demographic characteristics, kidney function, traditional risk factors, and medications, lower corin level was found to be independently associated with higher risk for progressive renal dysfunction (hazard ratio, 0.23; 95% confidence interval, 0.12-0.44) but not for contrast-induced nephropathy. This inverse correlation remained evident in patients with underlying chronic kidney disease, coronary artery disease, or heart failure.

CONCLUSIONS

Lower baseline serum corin was associated with higher risk of renal function decline in patients undergoing coronary angiography. Further studies are needed to verify these results.

Association of rs2271037 and rs3749585 polymorphisms in CORIN with susceptibility to hypertension in a Chinese Han population: A case-control study

Corins are membrane-bound protease that regulates blood pressure by activating the natriuretic peptides. These pro-atrial natriuretic peptide convertases are essential for sodium homeostasis and normal blood pressure. CORIN variants have been identified in humans and other animals, but no studies of CORIN polymorphisms have been conducted in northeastern China. This study aims to investigate the association of 2 single nucleotide polymorphisms (SNPs) in CORIN (rs2271037 and rs3749585) with hypertension, as well as their potential interactions with some risk factors of hypertension in a Han population of northeastern China. A case-control study, including 402 patients with hypertension and 406 participants with normal blood pressure, was conducted in Liaoning province. SNP genotyping was carried out by high resolution melting (HRM) after polymerase chain reaction amplifications. Since rs3749585 is located in 3' untranslated region (UTR) of CORIN, in silico analysis was used to predict target micro RNAs on TargetScan, miRanda, and DIANA-microT. As a result, mutant T allele in rs2271037 (odds ratio [OR], 1.693; 95% confidence [CI], 1.528-1.877; p < 0.001) and C allele in rs3749585 (OR, 1.114; 95% CI 1.011-1.227; p = 0.029) increased the risk of hypertension, comparing with wild G allele and T allele, respectively. Patients with genotype TT (OR, 10.209; 95% CI, 6.414-16.250; p < 0.001) and GT (OR, 1.730; 95% CI, 1.226-2.443; p = 0.002) have higher risk of hypertension than those with genotype GG. SNP rs2271037 was significantly associated with susceptibility to hypertension in all genetic models (dominant model: OR, 2.879; 95% CI, 2.080-3.986; p < 0.001; recessive model: OR, 7.159; 95% CI, 4.779-10.724; p < 0.001; additive model: OR, 1.535; 95% CI, 1.163-2.027; p = 0.002). SNP rs3749585 was significantly correlated with hypertension susceptibility only in dominant model (OR, 1.533; 95% CI, 1.073-2.189; p = 0.019), but not in recessive model (OR, 1.220; 95% CI, 0.906-1.644; p = 0.191) or additive model (OR, 0.915; 95% CI, 0.694-1.205; p = 0.527). After adjusting for age, gender, body mass index (BMI), smoking, low-density lipoprotein cholesterol, and serum sodium level in logistic models, the same statistical results were obtained. Interaction study showed the association between CORIN polymorphisms and hypertension could be changed by overweight (BMI ≥ 25 kg/m²). In silico analyses implicated hsa-miR-495 as a target miRNA that potentially interacts with the 3' UTR of CORIN. In conclusion, polymorphisms of rs2271037 and rs3749585 in CORIN were significantly associated with hypertension in a Han population of northeastern China. The mutant-type T allele of rs2271037 and C allele of rs3749585 might increase the susceptibility to hypertension in this population.

Pharmacogenomics of the Natriuretic Peptide System in Heart Failure

PURPOSE OF REVIEW

Heart failure (HF) continues to be a public health burden despite advances in therapy, and the natriuretic peptide (NP) system is clearly of critical importance in this setting, spawning valuable diagnostic and prognostic testing, such as B-type natriuretic peptide (BNP) and N-terminal pro-BNP (NT-proBNP), as well as current and future therapeutics, including recombinant natriuretic peptides (e.g., carperitide, nesiritide) and recently sacubitril, which inhibits the key clearance mechanism for NPs. This article intends to summarize the existing evidence for the role of NP system genetic variation on cardiovascular phenotypes relevant to HF with particular focus on the potential impact on pharmacologic therapies.

RECENT FINDINGS

Several genes in NP system have been interrogated, in many cases genetic variation impacting protein quantity and function or related disease states. Recent data supports genetic variants potentially impacting pharmacokinetics or dynamics of medications targeting the pathway. Growing evidence indicates the importance of genetic variation to the functioning of the NP system and its pharmacologic manipulation.

Identification and functional analysis of CORIN variants in hypertensive patients

Corin is a serine protease that activates atrial natriuretic peptide (ANP). CORIN gene variants have been reported in patients with hypertension. To date, however, the prevalence of CORIN variants in hypertensive patients remains unknown. To understand the prevalence and functional significance of CORIN variants in hypertension, we sequenced CORIN exons in 300 normal and 401 hypertensive individuals in a Chinese population and identified nine nonsynonymous variants, of which eight were not characterized previously. Among them, variants c.131A > G (p.Tyr13Cys), c.376G > T (p.Asp95Tyr), c.1094T > G (p.Leu334Trp), and c.1667G > A (p.Arg525His) occurred similarly in both normal and hypertensive individuals. Variants c1139G > A (p.Arg349His), c.2689C > T (p.Pro866Ser), and c.2864C > T (p.Thr924Met) were found once each in hypertensive individuals. Variant c.1683G > T (p.Arg530Ser) occurred preferentially in hypertensive individuals [10/401 (2.5%) vs. 1/300 (0.3%) in normal individuals; P = 0.023], which was confirmed in another independent cohort [9/368 (2.44%) in hypertensive and 2/377 (0.53%) in normal individuals; P = 0.033]. In biochemical and cell-based functional studies, variants p.Arg530Ser and p.Thr924Met, but not p.Tyr13Cys, p.Asp95Tyr, p.Leu334Trp, p.Arg349His, p.Arg525His, and p.Pro866Ser, exhibited reduced pro-ANP processing activity, which was caused by endoplasmic reticulum retention and poor zymogen activation, respectively. These results indicate that genetic variants impairing corin function are not uncommon in general populations and that such variants may be an important contributing factor in hypertension.

Prognostic Value of Plasma Soluble Corin in Patients With Acute Myocardial Infarction

BACKGROUND

Recent studies in animal models and humans have shown that corin is critically involved in the regulation of salt-water balance, blood pressure, and cardiac function.

OBJECTIVES

The goal of this study was to investigate the prognostic value of plasma soluble corin in patients with acute myocardial infarction (AMI).

METHODS

We enrolled 1,382 consecutive AMI patients in a prospective cohort study and explored the association of plasma corin with AMI outcomes using multivariable Cox proportional hazards analysis.

RESULTS

Patients with low corin levels were more likely to be female and to have histories of hypertension and heart failure (HF). Kaplan-Meier survival curves indicated that patients with corin levels above the median had a lower incidence of major adverse cardiac events (MACE) and all-cause mortality compared with those whose corin levels were below the median. Multivariate Cox regression analysis suggested that log corin was an independent predictor of MACE (hazard ratio [HR]: 0.61; 95% confidence interval [CI]: 0.42 to 0.96; p = 0.029), together with age, previous histories of AMI, HF, and diabetes, Killip class, percutaneous coronary intervention, coronary artery bypass graft, beta-blocker use, and log N-terminal pro-B-type natriuretic peptide. The C-statistic and integrated discrimination improvement for MACE were improved significantly by the addition of corin to the reference model. Moreover, log corin was also found to be a significant predictor of death (HR: 0.65; 95% CI: 0.41 to 0.97; p = 0.036) and HF hospitalization (HR: 0.48; 95% CI: 0.23 to 0.90; p = 0.009) after adjustment for clinical variables and established biomarkers of adverse prognosis.

CONCLUSIONS

Our study demonstrates that corin is a valuable prognostic marker of MACE in patients with AMI, independent of established conventional risk factors.

Role of corin in the regulation of blood pressure

PURPOSE OF REVIEW

Corin is a transmembrane protease that activates atrial natriuretic peptide (ANP), an important hormone in regulating salt-water balance and blood pressure. This review focuses on the regulation of corin function and potential roles of corin defects in hypertensive, heart, and renal diseases.

RECENT FINDINGS

Proprotein convertase subtilisin/kexin-6 has been identified as a primary enzyme that converts zymogen corin to an active protease. Genetic variants that impair corin intracellular trafficking, cell surface expression, and zymogen activation have been found in patients with hypertension, cardiac hypertrophy, and pre-eclampsia. Reduced corin expression has been detected in animal models of cardiomyopathies and in human failing hearts. Low levels of circulating soluble corin have been reported in patients with heart disease and stroke. Corin, ANP and natriuretic peptide receptor-A mRNAs, and proteins have been colocalized in human renal segments, suggesting a corin-ANP autocrine function in the kidney.

SUMMARY

Corin is a key enzyme in the natriuretic peptide system. The latest findings indicate that corin-mediated ANP production may act in a tissue-specific manner to regulate cardiovascular and renal function. Corin defects may contribute to major diseases such as hypertension, heart failure, pre-eclampsia, and kidney disease.

Serum Soluble Corin Deficiency Predicts Major Disability within 3 Months after Acute Stroke

OBJECTIVE

Serum soluble corin has been associated with stroke. However, whether it is associated with stroke prognosis has not yet been studied. Therefore, we aimed to study the association of serum soluble corin with risk of poor outcomes within 3 months after stroke.

METHODS

We followed 522 stroke patients for 3 months to identify major disability, death and vascular events. Serum soluble corin was measured at baseline for all participants. Logistic regression was used to examine the associations of baseline serum soluble corin with outcomes of stroke, adjusting for age, sex, baseline NIHSS score, hours from onset to hospitalization, smoking, drinking, hypertension, diabetes, coronary heart disease, atrial fibrillation, family history of stroke, and stroke subtype.

RESULTS

Patients with high corin had a significantly lower crude risk for the composite outcome of major disability or death (OR = 0.64, 95%CI: 0.43-0.96) than patients with low corin (the lowest tertile). After adjustment for age and baseline NIHSS score, patients with high corin still had a significantly lower risk for the composite outcome of major disability or death (OR = 0.60, 95%CI: 0.36-0.99). This association became bottom line significant after additionally adjusting for other conventional factors (OR = 0.61, P = 0.058). No association was found between serum soluble corin and other composite outcomes.

CONCLUSION

Serum soluble corin deficiency predicted risk for major disability within 3 months after stroke, independent of baseline neurological deficient. Our results may indicate a probable role of corin in stroke prognosis.

Association between serum soluble corin and hyperglycaemia: a cross-sectional study among Chinese adults

OBJECTIVES

Decreased natriuretic peptides are risk factors for diabetes. As a physiological activator of natriuretic peptides, corin may play a role in glucose metabolism. Here, we aimed to test the hypothesis in a general population of China.

DESIGN

Cross-sectional study.

SETTING

A population study in Suzhou, China.

PARTICIPANTS

A total of 2498 participants aged above 30 years were included in the study.

OUTCOME MEASURES

The association between serum soluble corin and hyperglycaemia was examined in men and women, using non-conditional logistic regression models, respectively.

RESULTS

Serum soluble corin, in men and women, was significantly higher in participants with hyperglycaemia than in those without (all p<0.001). OR of hyperglycaemia positively and significantly increased with serum soluble corin quartiles, in men (p for trend <0.001) and in women (p for trend=0.050), even after multivariate adjustment. Participants with a serum soluble corin, in men (OR=1.66, 95% CI 1.24 to 2.23) and women (OR=1.27, 95% CI 1.00 to 1.61), over the median level, were more likely to have hyperglycaemia compared with the remaining participants, after controlling for confounding factors.

CONCLUSIONS

Hyperglycaemia was significantly and positively associated with increased serum soluble corin in men and women. Our findings suggest that serum soluble corin may be a risk factor or a biomarker of hyperglycaemia.

Diagnostic utility of BNP, corin and furin as biomarkers for cardiovascular complications in type 2 diabetes mellitus patients

CONTEXT

The number of patients with type 2 diabetes mellitus (T2DM) is progressively increasing, and diabetic cardiovascular complications have become a public health problem. Brain or B-type natriuretic peptide (BNP) is a cardiac hormone synthesized as a pre-pro-peptide. pro-BNP is produced by cleaving the signal peptide then two proprotein convertases, corin and furin cleave pro-BNP to form a biologically active hormone. Two corin single nucleotide polymorphisms (SNPs) have been reported to alter corin protein conformation and impair its biological activity.

OBJECTIVE

We aimed to investigate the potential role of corin and furin in comparison to BNP as biomarkers for predicting cardiovascular complications in T2DM patients. The association of corin gene SNPs with corin levels was also examined.

METHODS

Seventy-five subjects were recruited in this study, including 25 T2DM patients with complications, 25 T2DM patients without complications as well as 25 healthy subjects. Plasma BNP, corin and furin levels were measured using enzyme-linked immunosorbent assays. Two corin SNPs were genotyped using allele specific oligonucleotide-polymerase chain reaction.

RESULTS

Both furin and BNP were found to be more sensitive than corin (80% versus 56%, p = 0.008), whereas furin showed higher specificity when compared to BNP (96% versus 84%, p = 0.041) and corin (96% versus 64%, p < 0.0001) in predicting cardiovascular complications in T2DM patients. Corin SNPs are not associated with corin levels, neither in the entire study cohort nor in the subgroup of T2DM patients with cardiovascular complications (p > 0.05).

CONCLUSIONS

Furin may be useful, either alone or in combination with other biomarkers, for cardiovascular risk stratification assessment in T2DM patients.

Corin is down-regulated and exerts cardioprotective action via activating pro-atrial natriuretic peptide pathway in diabetic cardiomyopathy

Background

Diabetic cardiomyopathy (DCM), a fatal cardiovascular complication of diabetes mellitus, often leads to progressive heart failure, however its pathogenesis remains unclear. Corin, a cardiac serine protease, is responsible for converting pro-atrial natriuretic peptide (pro-ANP) to biologically active atrial natriuretic peptide (ANP). It has been well established that corin deficiency is associated with the progression of hypertension, cardiac hypertrophy and heart failure. However, because the involvement of corin-mediated pro-ANP processing in DCM has not been clarified, this study aims to investigate the role of corin in the pathogenesis of DCM.

Methods

Diabetes mellitus was induced by a single intraperitoneal injection of streptozotocin (STZ 65 mg/kg) to Sprague–Dawley rats (180–220 g). DCM was confirmed by monitoring continuously transthoracic echocardiography every 4 weeks and hemodynamic measurements at 20 weeks. Myocardial disorder and fibrosis were detected by HE staining and Masson’s trichrome staining. The mRNA and protein levels of corin and ANP in rat hearts and cardiomyocytes were determined by quantitative real-time PCR, western blotting and immunohistochemical staining, respectively. H9c2 cardiomyoblasts proliferation was detected by MTT colorimetric assay and viable cell counting with trypan blue. The effect of Corin-siRNA H9c2 cardiomyoblasts on EA.hy926 cells migration was measured by the wound healing scratch assay.

Results

The corin and ANP expression in mRNA and protein levels was decreased in DCM rat hearts. Corin and ANP levels of neonatal rat cardiomyocytes and H9c2 cardiomyoblasts treated with high glucose were significantly lower than that of normal glucose treated. Precisely, corin and ANP levels decreased in DCM rats at 12, 16, 20 and 33 weeks; neonatal cardiomyocytes and H9c2 cardiomyoblasts treated with high glucose at 36, 48 and 60 h demonstrated significant reduction in corin and ANP levels. Corin-siRNA H9c2 cardiomyoblasts showed decreased proliferation. Culture supernatants of Corin-siRNA H9c2 cardiomyoblasts prevented endothelial cell line EA.hy926 migration in the wound healing scratch assay. Furthermore, iso-lectin expression in arteriole and capillary endothelium was down-regulated in DCM rats.

Conclusions

Our results indicate that corin plays an important role in cardioprotection by activating pro-atrial natriuretic peptide pathway in DCM. Corin deficiency leads to endothelial dysfunction and vascular remodeling.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-015-0298-9) contains supplementary material, which is available to authorized users.

Serum Soluble Corin is Decreased in Stroke

BACKGROUND AND PURPOSE

Soluble corin was decreased in coronary heart disease. Given the connections between cardiac dysfunction and stroke, circulating corin might be a candidate marker of stroke risk. However, the association between circulating corin and stroke has not yet been studied in humans. Here, we aimed to examine the association in patients wtith stroke and community-based healthy controls.

METHODS

Four hundred eighty-one patients with ischemic stroke, 116 patients with hemorrhagic stroke, and 2498 healthy controls were studied. Serum soluble corin and some conventional risk factors of stroke were examined. Because circulating corin was reported to be varied between men and women, the association between serum soluble corin and stroke was evaluated in men and women, respectively.

RESULTS

Patients with ischemic and hemorrhagic stroke had a significantly lower level of serum soluble corin than healthy controls in men and women (all P values, <0.05). In multivariate analysis, men in the lowest quartile of serum soluble corin were more likely to have ischemic (odds ratio [OR], 4.90; 95% confidence interval, 2.99-8.03) and hemorrhagic (OR, 17.57; 95% confidence interval, 4.85-63.71) stroke than men in the highest quartile. Women in the lowest quartile of serum soluble corin were also more likely to have ischemic (OR, 3.10; 95% confidence interval, 1.76-5.44) and hemorrhagic (OR, 8.54; 95% confidence interval, 2.35-31.02) stroke than women in the highest quartile. ORs of ischemic and hemorrhagic stroke were significantly increased with the decreasing levels of serum soluble corin in men and women (all P values for trend, <0.001).

CONCLUSIONS

Serum soluble corin was decreased in patients with stroke compared with healthy controls. Our findings raise the possibility that serum soluble corin may have a pathogenic role in stroke.

Association between serum soluble corin and obesity in Chinese adults: a cross-sectional study

OBJECTIVE

Corin has been suggested to be associated with obesity by cell- and animal-based studies. However, the association has not yet been studied in populations. Here, the aim was to explore the association in a general population of China.

METHODS

This was a cross-sectional study. Data on demographic information, lifestyle risk factors, and personal medical history were collected; body mass index, waist circumference, and blood pressures were measured; and serum corin, blood lipids, and blood glucose were determined in 2498 participants aged above 30 years.

RESULTS

Log-transformed corin correlated to body mass index (r = 0.197, P < 0.001) and waist circumference (r = 0.289, P < 0.001). In the risk factor-adjusted analysis, compared with participants in the lowest quartile of serum corin, participants in the 4th quartile had significantly increased risk of prevalent overweight or obesity (OR = 2.26, 95% CI: 1.67-3.04) and central obesity (OR = 1.74, 95% CI: 1.30-2.34). ORs of overweight or obesity and central obesity positively and significantly increased with serum corin levels (P for trend < 0.001).

CONCLUSIONS

Serum soluble corin was significantly and positively associated with obesity. Our findings suggested that serum soluble corin may be a marker or risk factor for obesity.

A corin variant identified in hypertensive patients that alters cytoplasmic tail and reduces cell surface expression and activity

Corin is a membrane-bound protease that regulates blood pressure by activating the natriuretic peptides. CORIN variants have been associated with hypertension and heart disease in African Americans. In this study, we conducted targeted exome sequencing and identified an insertion variant, c.102_103insA, in exon 1 of the CORIN gene. Analysis of two independent cohorts showed that the variant was preferentially present in hypertensive patients (38/795 or 4.78% vs. 4/632 or 0.63% in normal individuals, p = 4.14E-6). The insertion shifted the reading frame, resulting in a corin variant with a truncated cytoplasmic tail. In cell-based studies, the corin variant exhibited poor trafficking in the Golgi, reduced cell surface expression and zymogen activation, and low natriuretic peptide processing activity. Compared with normal individuals with the wild-type allele, individuals with the variant allele had lower levels of plasma corin [0.59 ± 0.07 ng/mL (n = 25) vs. 0.91 ± 0.02 ng/mL (n = 215), p<0.001] and higher levels of plasma N-terminal pro-atrial natriuretic peptide (NT-pro-ANP) [2.39 ± 3.6 nmol/L (n = 21) vs. 0.87 ± 0.6 nmol/L (n = 48), p = 0.005]. These results indicate that the variant altered corin structure and impaired the natriuretic peptide processing activity in vivo. The results highlight corin defects as an important underlying mechanism in hypertension.

Corin in natriuretic peptide processing and hypertension

Corin is a serine protease originally isolated from the heart. Functional studies show that corin is the long-sought enzyme responsible for activating cardiac natriuretic peptides. In mice, lack of corin prevents natriuretic peptide processing, causing salt-sensitive hypertension. In humans, corin variants and mutations that reduce corin activity have been identified in patients with hypertension and heart failure. Decreased plasma levels of corin antigen and activity have been reported in patients with heart failure and coronary artery disease. Low levels of urinary corin also have been found in patients with chronic kidney disease. Most recent studies show that corin also acts in the uterus to promote spiral artery remodeling and prevent pregnancy-induced hypertension. Here, we review the role of corin in natriuretic peptide processing and cardiovascular diseases such as hypertension, heart disease, pre-eclampsia, and chronic kidney disease.

Corin mutations K317E and S472G from preeclamptic patients alter zymogen activation and cell surface targeting. [Corrected]

Corin is a membrane-bound serine protease that acts as the atrial natriuretic peptide (ANP) convertase in the heart. Recent studies show that corin also activates ANP in the pregnant uterus to promote spiral artery remodeling and prevent pregnancy-induced hypertension. Two CORIN gene mutations, K317E and S472G, were identified in preeclamptic patients and shown to have reduced activity in vitro. In this study, we carried out molecular modeling and biochemical experiments to understand how these mutations impair corin function. By molecular modeling, the mutation K317E was predicted to alter corin LDL receptor-2 module conformation. Western blot analysis of K317E mutant in HEK293 cells showed that the mutation did not block corin expression on the cell surface but inhibited corin zymogen activation. In contrast, the mutation S472G was predicted to abolish a β-sheet critical for corin frizzled-2 module structure. In Western blot analysis and flow cytometry, S472G mutant was not detected on the cell surface in transfected HEK293 cells. By immunostaining, the S472G mutant was found in the ER, indicating that the mutation S472G disrupted the β-sheet, causing corin misfolding and ER retention. Thus, these results show that mutations in the CORIN gene may impair corin function by entirely different mechanisms. Together, our data provide important insights into the molecular basis underlying corin mutations that may contribute to preeclampsia in patients.