Corin in clinical laboratory diagnostics

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.

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.

Association of Preablation Plasma Corin Levels With Atrial Fibrillation Recurrence After Catheter Ablation: A Prospective Observational Study

BACKGROUND

We assessed the impact of pre- and postprocedural plasma corin levels on the recurrence of atrial fibrillation (AF) after catheter ablation (CA).

METHODS AND RESULTS

This prospective, single-center, observational study included patients undergoing their first CA of AF. Corin was measured before and 1 day after CA. The primary end point was recurrent AF between 3 and 12 months after ablation. From April 2019 through May 2021, we analyzed 616 patients with AF (59.09% men) with a mean age of 62.86±9.42 years. Overall, 153 patients (24.84%) experienced recurrent AF. In the recurrence group, the pre- and postprocedure corin concentrations were 539.14 (329.24-702.08) and 607.37 (364.50-753.80) pg/mL, respectively, which were significantly higher than the nonrecurrence group's respective concentrations of 369.05 (186.36-489.28) and 489.12 (315.66-629.05) pg/mL (both P<0.0001). A multivariate Cox regression analysis with confounders found that elevated preablation corin levels were significantly associated with an increased risk of AF recurrence after CA. Receiver operating characteristic curve analysis identified that a preablation corin threshold of >494.85 pg/mL predicted AF recurrence at 1 year. An increase of 1 SD in corin concentrations before CA (264.94 pg/mL) increased the risk of recurrent AF by 54.3% after adjusting for confounding variables (hazard ratio, 1.465 [95% CI, 1.282-1.655]; P<0.0001).

CONCLUSIONS

Plasma corin levels at baseline is a valuable predictor of AF recurrence after CA, independent of established conventional risk factors. Risk stratification before ablation for AF may be useful in selecting treatment regimens for patients.

Corin and Left Atrial Cardiomyopathy, Hypertension, Arrhythmia, and Fibrosis

Two siblings presented with cardiomyopathy, hypertension, arrhythmia, and fibrosis of the left atrium. Each had a homozygous null variant in CORIN, the gene encoding atrial natriuretic peptide (ANP)-converting enzyme. A plasma sample obtained from one of the siblings had no detectable levels of corin or N-terminal pro-ANP but had elevated levels of B-type natriuretic peptide (BNP) and one of the two protein markers of fibrosis that we tested. These and other findings support the hypothesis that BNP cannot fully compensate for a lack of activation of the ANP pathway and that corin is critical to normal ANP activity, left atrial function, and cardiovascular homeostasis.

Corin deficiency impairs cardiac function in mouse models of heart failure

Introduction

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

Methods

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

Results

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

Conclusion

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

Corin Deficiency Diminishes Intestinal Sodium Excretion in Mice

Sodium excretion, a critical process in sodium homeostasis, occurs in many tissues, including the kidney and intestine. Unlike in the kidney, the hormonal regulation of intestinal sodium excretion remains unclear. Atrial natriuretic peptide (ANP) is a crucial hormone in renal natriuresis. Corin is a protease critical for ANP activation. Corin and ANP are expressed mainly in the heart. In this study, we investigated corin, ANP, and natriuretic peptide receptor A (Npra) expression in mouse intestines. Corin and ANP expression was co-localized in enteroendocrine cells, whereas Npra expression was on the luminal epithelial cells. In Corin knockout (KO) mice, fecal Na⁺ and Cl^- excretion decreased compared with that in wild-type (WT) mice. Such a decrease was not found in conditional Corin KO mice lacking cardiac corin selectively. In kidney conditional Corin KO mice lacking renal corin, fecal Na⁺ and Cl^- excretion increased, compared to that in WT mice. When WT, Corin KO, and the kidney conditional KO mice were treated with aldosterone, the differences in fecal Na⁺ and Cl^- levels disappeared. These results suggest that intestinal corin may promote fecal sodium excretion in a paracrine mechanism independent of the cardiac corin function. The increased fecal sodium excretion in the kidney conditional Corin KO mice likely reflected an intestinal compensatory response to renal corin deficiency. Our results also suggest that intestinal corin activity may antagonize aldosterone action in the promotion of fecal sodium excretion. These findings help us understand the hormonal mechanism controlling sodium excretion the intestinal tract.

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.

Renal Corin Is Essential for Normal Blood Pressure and Sodium Homeostasis

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

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.

Associations of corin genetic polymorphisms with salt sensitivity, blood pressure changes, and hypertension incidence in Chinese adults

Corin, a transmembrane serine protease that can cleave pro‐atrial natriuretic peptide (Pro‐ANP) into smaller bioactive molecule atrial natriuretic peptide, has been shown to be involved in the pathophysiology of hypertension, cardiac hypertrophy. We sought to examine the associations of corin genetic variations with salt sensitivity, blood pressure (BP) changes and hypertension incidence. We studied participants of the original Baoji Salt‐Sensitive cohort, recruited from 124 families from seven Chinese villages in 2004 who sequentially received a usual baseline salt diet, a 7‐day low salt diet (3 g/day) and a 7‐day high salt diet (18 g/day), respectively. They were followed up for 8 years (in 2009, 2012) to evaluate the development of hypertension. Corin SNP rs3749584 was significantly associated with diastolic BP (DBP) and mean arterial pressure (MAP) response to low‐salt diet, while rs4695253, rs17654278 were associated with pulse pressure (PP) response to low‐salt diet. SNPs rs4695253, rs12509275, rs2351783, rs2271036, rs2271037 were significantly associated with systolic BP (SBP), DBP, and MAP responses to high‐salt diet. In addition, SNPs rs12641823, rs6834933, rs2271036, and rs22710367 were significantly associated with the longitudinal changes in SBP, DBP, MAP, or PP over 8 years of follow‐up. SNP rs73814824 was significantly associated with the incidence of hypertension over 8 years. Gene‐based analysis showed that corin gene was significantly associated with longitudinal BP changes and hypertension incidence after 8‐year follow‐up. This study suggests that corin may play a role in salt sensitivity, BP progression, and development of hypertension.

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.

Ectopic expression of human airway trypsin-like protease 4 in acute myeloid leukemia promotes cancer cell invasion and tumor growth

Transmembrane serine proteases have been implicated in the development and progression of solid and hematological cancers. Human airway trypsin-like protease 4 (HAT-L4) is a transmembrane serine protease expressed in epithelial cells and exocrine glands. In the skin, HAT-L4 is important for normal epidermal barrier function. Here, we report an unexpected finding of ectopic HAT-L4 expression in neutrophils and monocytes from acute myeloid leukemia (AML) patients. Such expression was not detected in bone marrow cells from normal individuals or patients with chronic myeloid leukemia, acute lymphocytic leukemia and chronic lymphocytic leukemia. In AML patients who underwent chemotherapy, persistent HAT-L4 expression in bone marrow cells was associated with minimal residual disease and poor prognostic outcomes. In culture, silencing HAT-L4 expression in AML-derived THP-1 cells by short hairpin RNAs inhibited matrix metalloproteinase-2 activation and Matrigel invasion. In mouse xenograft models, inhibition of HAT-L4 expression reduced the proliferation and growth of THP-1 cell-derived tumors. Our results indicate that ectopic HAT-L4 expression is a pathological mechanism in AML and that HAT-L4 may be used as a cell surface marker for AML blast detection and targeting.

Corin Is Downregulated in Renal Ischemia/Reperfusion Injury and Is Associated with Delayed Graft Function after Kidney Transplantation

Renal ischemia/reperfusion (IR) injury is one of the most important risk factors for the occurrence of delayed graft function (DGF) after kidney transplantation; however, its mechanism remains not fully understood. In the present study, we screened differentially expressed genes in a murine model of renal IR injury by using high-throughput assays. We identified Corin as one of the most significantly downregulated genes among 2218 differentially expressed genes (≥2-fold, P < 0.05). By using a real-time qPCR assay, we observed that the expression of renal Corin in IR-injured mice was reduced to 11.5% of the sham-operated mice and that the protein level of renal Corin in IR-injured mice was also downregulated. Interestingly, renal IR injury in mice induced the downregulation of Corin in heart tissues, suggesting that the overall synthesis of Corin may be suppressed. We recruited 11 recipients complicated with DGF and 16 without DGF, and plasma Corin concentrations were determined by ELISA. We observed that the plasma Corin levels were indeed reduced in recipients complicated with DGF (0.98 vs. 1.95 ng/ml, P < 0.05). These findings demonstrate that Corin may be a potential biomarker of DGF after kidney transplantation and may participate in the regulation of renal IR injury.

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.

Molecular functions and specific roles of circRNAs in the cardiovascular system

As part of the superfamily of long noncoding RNAs, circular RNAs (circRNAs) are emerging as a new type of regulatory molecules that partake in gene expression control. Here, we review the current knowledge about circRNAs in cardiovascular disease. CircRNAs are not only associated with different types of cardiovascular disease, but they have also been identified as intracellular effector molecules for pathophysiological changes in cardiovascular tissues, and as cardiovascular biomarkers. This evidence is put in the context of the current understanding of general circRNA biogenesis and of known interactions of circRNAs with DNA, RNA, and proteins.

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.

Natriuretic peptides system in the pulmonary tissue of rats with heart failure: potential involvement in lung edema and inflammation

Congestive heart failure (CHF) often leads to progressive cardiac hypertrophy and salt/water retention as evident by peripheral and lung edema. Although the pathogenesis of CHF remains largely unclarified, it is widely accepted that neurohormonal changes and inflammatory processes are profoundly involved in structural and functional deterioration of vital organs including, heart, kidney and lungs. Corin, a cardiac serine protease, is responsible for converting pro-ANP and pro-BNP to biologically active natriuretic peptides (NPs). Although the involvement of corin in cardiac hypertrophy and heart failure was extensively studied, the alterations in corin and PCSK6, a key enzyme in the conversion of procorin to corin, have not been studied in the pulmonary tissue. Thus, this study aims at examining the status of PCSK6/Corin in the lung of rats with CHF induced by the creation of aorto-caval fistula (ACF) between the abdominal aorta and vena cava in SD rats. Rats with ACF were divided into 2 subgroups based on the pattern of their daily sodium excretion, compensated and decompensated CHF. Placement of ACF led to cardiac hypertrophy, pulmonary congestion, and renal dysfunction, which were more severe in the decompensated subgroup, despite remarkable elevation of circulatory ANP and BNP levels. Corin mRNA and immunoreactive peptide were detected in pulmonary tissue of all experimental groups. However, the expression and abundance of pulmonary corin significantly increased in the decompensated animals, but not in the compensated ones. Noteworthy, the expression of PCSK6 and ANP/BNP in the pulmonary tissue followed a similar pattern as corin. The upregulation of pulmonary Corin/PCSK6 and NPs were accompanied by local activation of cathepsin L and certain cytokines including IL-6. In light of the anti-inflammatory role of NPs, we postulate that the obtained upregulation of pulmonary PCSK6/Corin along NPs in rats with decompensated CHF may represent a counterbalance response to the inflammatory milieu characterizing CHF especially in severe cases.

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.

A map of human circular RNAs in clinically relevant tissues

Abstract

Cellular circular RNAs (circRNAs) are generated by head-to-tail splicing and are present in all multicellular organisms studied so far. Recently, circRNAs have emerged as a large class of RNA which can function as post-transcriptional regulators. It has also been shown that many circRNAs are tissue- and stage-specifically expressed. Moreover, the unusual stability and expression specificity make circRNAs important candidates for clinical biomarker research. Here, we present a circRNA expression resource of 20 human tissues highly relevant to disease-related research: vascular smooth muscle cells (VSMCs), human umbilical vein cells (HUVECs), artery endothelial cells (HUAECs), atrium, vena cava, neutrophils, platelets, cerebral cortex, placenta, and samples from mesenchymal stem cell differentiation. In eight different samples from a single donor, we found highly tissue-specific circRNA expression. Circular-to-linear RNA ratios revealed that many circRNAs were expressed higher than their linear host transcripts. Among the 71 validated circRNAs, we noticed potential biomarkers. In adenosine deaminase-deficient, severe combined immunodeficiency (ADA-SCID) patients and in Wiskott-Aldrich-Syndrome (WAS) patients’ samples, we found evidence for differential circRNA expression of genes that are involved in the molecular pathogenesis of both phenotypes. Our findings underscore the need to assess circRNAs in mechanisms of human disease.

Key messages

circRNA resource catalog of 20 clinically relevant tissues.

circRNA expression is highly tissue-specific.

circRNA transcripts are often more abundant than their linear host RNAs.

circRNAs can be differentially expressed in disease-associated genes.

Electronic supplementary material

The online version of this article (10.1007/s00109-017-1582-9) contains supplementary material, which is available to authorized users.

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.

Fibrosis and Fibrotic Gene Expression in Pediatric and Adult Patients With Idiopathic Dilated Cardiomyopathy

BACKGROUND

Although fibrosis seems to be prognostic for adverse outcomes in adults with idiopathic dilated cardiomyopathy (IDC), little is known about the prevalence and development of fibrosis in pediatric IDC hearts. We hypothesized that there is less activation of fibrosis at a molecular level in pediatric IDC hearts than in failing adult hearts.

METHODS AND RESULTS

Pediatric hearts were analyzed histologically to determine the prevalence of fibrosis. Left ventricular tissue from adult and pediatric IDC hearts and adult and pediatric nonfailing (NF) hearts were subjected to quantitative reverse-transcription polymerase chain reaction to study the expression of important mRNAs that affect fibrosis. We found age-specific differences between IDC and NF hearts in the regulation of noncoding galectin-3, Corin, matrix metalloproteinase (MMP) 2, MMP-9, tissue inhibitor of metalloproteinase (TIMP) 2, and TIMP-3. We also found markers that were similarly altered in both adult and pediatric IDC hearts (interleukin-1 receptor-like 1 receptor, TIMP-1, and TIMP-4). Finally, microRNAs 29a-c were significantly decreased in the pediatric IDC patients.

CONCLUSIONS

Pediatric IDC patients demonstrate age-specific differences in the molecular pathways implicated in fibrosis in the adult heart. At the ultrastructural level the unique gene expression pattern appears to limit fibrosis in the failing pediatric heart.

Changes of myocardial gene expression and protein composition in patients with dilated cardiomyopathy after immunoadsorption with subsequent immunoglobulin substitution

Immunoadsorption with subsequent immunoglobulin substitution (IA/IgG) represents a therapeutic approach for patients with dilated cardiomyopathy (DCM). Here, we studied which molecular cardiac alterations are initiated after this treatment. Transcription profiling of endomyocardial biopsies with Affymetrix whole genome arrays was performed on 33 paired samples of DCM patients collected before and 6 months after IA/IgG. Therapy-related effects on myocardial protein levels were analysed by label-free proteome profiling for a subset of 23 DCM patients. Data were analysed regarding therapy-associated differences in gene expression and protein levels by comparing responders (defined by improvement of left ventricular ejection fraction ≥20 % relative and ≥5 % absolute) and non-responders. Responders to IA/IgG showed a decrease in serum N-terminal proBNP levels in comparison with baseline which was accompanied by a decreased expression of heart failure markers, such as angiotensin converting enzyme 2 or periostin. However, despite clinical improvement even in responders, IA/IgG did not trigger general inversion of DCM-associated molecular alterations in myocardial tissue. Transcriptome profiling revealed reduced gene expression for connective tissue growth factor, fibronectin, and collagen type I in responders. In contrast, in non-responders after IA/IgG, fibrosis-associated genes and proteins showed elevated levels, whereas values were reduced or maintained in responders. Thus, improvement of LV function after IA/IgG seems to be related to a reduced gene expression of heart failure markers and pro-fibrotic molecules as well as reduced fibrosis progression.

Localization of corin and atrial natriuretic peptide expression in human renal segments

Atrial natriuretic peptide (ANP)-mediated natriuretic response is a well-established cardiac endocrine function. Corin is a transmembrane protease that activates ANP in the heart. Corin expression has been detected in non-cardiac tissues including the kidney. Here we examined corin, pro-ANP/ANP and natriuretic peptide receptor-A (NPR-A) expression in human renal segments. By immunostaining and in situ hybridization, we found similar corin, pro-ANP/ANP and NPR-A protein and mRNA expression in human renal segments. The expression was most abundant in the proximal convoluted tubules and the medullary connecting ducts. In the proximal tubules, corin protein was present in the apical membrane region underneath the brush border where the ANP-degrading protease neprilysin was abundant. These results suggest that corin-mediated pro-ANP activation may occur in renal segments and that locally produced ANP may act in an autocrine manner to regulate sodium and water reabsorption in situ Our results also point to the proximal convoluted tubules as a major site for local ANP action. Such a renal corin/ANP autocrine mechanism may differ from the cardiac corin/ANP endocrine mechanism in regulating sodium homoeostasis under physiological and pathological conditions.

Sensitive and low-background electrochemical assay of corin activity via supramolecular recognition and rolling circle amplification

Corin is an important member of type II transmembrane serine proteases that is involved in a variety of cardiovascular and pregnancy-related diseases. Herein, a sensitive and low-background electrochemical method is proposed to assay the activity of corin. In principle, a peptide comprising both the substrate motif of corin and binding site of cucurbit[8]uril (CB[8]) is first designed and immobilized on the electrode surface. Thereafter, via CB[8]-mediated supramolecular recognition, a DNA-primer is recruited, subsequently triggering the rolling circle amplification (RCA) reaction. In this way, a succeeding propagation of DNA strands is achieved on the electrode surface, which would produce remarkable repelling effect against the electrochemical species [Fe(CN)6](3-/4-), and thereby yield a highly minimized background signal. However, in the presence of activated corin, the peptide is specifically recognized and cleaved, breaching the recruitment of DNA primer as well as the RCA reaction, which decreases the repulsion to [Fe(CN)6](3-/4-), leading to a remarkable electrochemical response. As a result, the proposed assay method can sensitively determine the activity of corin with a detection limit of 0.92 pM, and can further be directly used in maternal plasma samples. Therefore, this method may provide a promising tool for pathological research and clinical diagnosis of corin-related diseases.

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.

Increased serum soluble corin in dyslipidemia: A cross-sectional study

BACKGROUND

Natriuretic peptides have been associated with dyslipidemia. As a physiological activator of natriuretic peptides, corin might also be associated with dyslipidemia. However, this association has not yet been studied in Chinese populations.

METHODS

Serum soluble corin and blood lipid profiles were determined for 2496 participants aged above 30y. A logistic regression model was applied to evaluate the association between serum soluble corin and dyslipidemia.

RESULTS

Serum soluble corin was significantly increased in participants with dyslipidemia in both men (P<0.001) and women (P<0.001). After controlling for the confounding factors, OR of dyslipidemia positively increased with increasing levels of serum soluble corin in men (P for trend=0.011) and women (P for trend=0.043). Participants with a high corin level were more likely to have dyslipidemia than those with a low corin level in men (OR, 95% CI: 1.45, 1.07-1.97) and women (OR, 95% CI: 1.33, 1.04-1.70).

CONCLUSION

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

Association Between High Serum Soluble Corin and Hypertension: A Cross-Sectional Study in a General Population of China

BACKGROUND

Corin has been suggested to be associated with hypertension by cell- and animal-based studies. However, the association still lacks population-based evidence which critically promotes translation from basic research to clinical and preventive practice. Here, we aimed to explore the association in a general population of China.

METHODS

From January to May 2010, we conducted a cross-sectional study in 2,498 participants aged above 30 years, residing in Gusu district of Suzhou. Serum soluble corin and blood pressure were measured.

RESULTS

Hypertensive participants had a higher level of serum corin than nonhypertensive participants (median (interquartile range): 1,836.83 (1,497.85-2,327.87) pg/ml vs. 1,579.14 (1,322.18-1,956.82) pg/ml, P < 0.001). Higher serum corin was positively associated with prevalent hypertension (odds ratio (OR) = 2.01, P < 0.001). In the multiple analysis, participants in the third (OR = 1.43, P = 0.007) and fourth (OR = 1.96, P < 0.001) quartiles had significantly increased odds of hypertension compared to those in the lowest quartile of serum corin. ORs of hypertension positively and significantly increased with serum corin levels (P for trend <0.001). Further subgroup analysis showed that ORs of hypertension associated with high corin (over the median level of serum corin: 1,689.20 pg/ml) were still significant in subgroups by age, body mass index, total cholesterol, low-density lipoprotein cholesterol, and fasting plasma glucose (all P < 0.05).

CONCLUSIONS

Our study showed that hypertensive participants had an increased serum corin level compared to those without hypertension. This finding suggests that corin may play a role in the pathology of hypertension.

Perspectives on edema in childhood nephrotic syndrome

There have been two major theories surrounding the development of edema in nephrotic syndrome (NS), namely, the under- and overfill hypotheses. Edema is one of the cardinal features of NS and remains one of the principal reasons for admission of children to the hospital. Recently, the discovery that proteases in the glomerular filtrate of patients with NS are activating the epithelial sodium channel (ENaC), resulting in intrarenal salt retention and thereby contributing to edema, might suggest that targeting ENaC with amiloride might be a suitable strategy to manage the edema of NS. Other potential agents, particularly urearetics and aquaretics, might also prove useful in NS. Recent evidence also suggests that there may be other areas involved in salt storage, especially the skin, and it will be intriguing to study the implications of this in NS.

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.

Global gene expression profiling of telangiectasial tissue from patients with hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT), the most common inherited vascular disorder, is predominantly caused by mutations in ENG and ACVRL1, which are part of the transforming growth factor beta (TGF-β) signaling pathway. HHT is characterized by the presence of mucocutaneous telangiectases and arteriovenous malformations in visceral organs, primarily the lungs, brain and liver. The most common symptom in HHT is epistaxis originating from nasal telangiectasia, which can be difficult to prevent and can lead to severe anemia. The clinical manifestations of HHT are extremely variable, even within family members, and the exact mechanism of how endoglin and ALK1 haploinsufficiency leads to HHT manifestations remains to be identified.

OBJECTIVES

The purpose of this study was to detect significantly differentially regulated genes in HHT, and try to elucidate the pathways and regulatory mechanisms occurring in the affected tissue of HHT patients, in order to further characterize this disorder and hypothesize on how telangiectases develop. By microarray technology (Agilent G3 Human GE 8x60), we performed global gene expression profiling of mRNA transcripts from HHT nasal telangiectasial (n = 40) and non-telangiectasial (n = 40) tissue using a paired design. Comparing HHT telangiectasial and non-telangiectasial tissue, significantly differentially expressed genes were detected using a paired t-test. Gene set analysis was performed using GSA-SNP. In the group of ENG mutation carriers, we detected 67 differentially expressed mRNAs, of which 62 were down-regulated in the telangiectasial tissue. Gene set analysis identified the gene ontology (GO) terms vasculogenesis, TGF-β signaling, and Wnt signaling as differentially expressed in HHT1. Altered Wnt signaling might be related to HHT pathogenesis and a greater understanding of this may lead to the discovery of therapeutic targets in HHT.

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.

ANP-induced signaling cascade and its implications in renal pathophysiology

The balance between vasoconstrictor/sodium-retaining and vasodilator/natriuretic systems is essential for maintaining body fluid and electrolyte homeostasis. Natriuretic peptides, such as atrial natriuretic peptide (ANP), belong to the vasodilator/natriuretic system. ANP is produced by the conversion of pro-ANP into ANP, which is achieved by a proteolytical cleavage executed by corin. In the kidney, ANP binds to the natriuretic peptide receptor-A (NPR-A) and enhances its guanylyl cyclase activity, thereby increasing intracellular cyclic guanosine monophosphate production to promote natriuretic and renoprotective responses. In the glomerulus, ANP increases glomerular permeability and filtration rate and antagonizes the deleterious effects of the renin-angiotensin-aldosterone system activation. Along the nephron, natriuretic and diuretic actions of ANP are mediated by inhibiting the basolaterally expressed Na(+)-K(+)-ATPase, reducing apical sodium, potassium, and protein organic cation transporter in the proximal tubule, and decreasing Na(+)-K(+)-2Cl(-) cotransporter activity and renal concentration efficiency in the thick ascending limb. In the medullary collecting duct, ANP reduces sodium reabsorption by inhibiting the cyclic nucleotide-gated cation channels, the epithelial sodium channel, and the heteromeric channel transient receptor potential-vanilloid 4 and -polycystin 2 and diminishes vasopressin-induced water reabsorption. Long-term ANP treatment may lead to NPR-A desensitization and ANP resistance, resulting in augmented sodium and water reabsorption. In mice, corin deficiency impairs sodium excretion and causes salt-sensitive hypertension. Characteristics of ANP resistance and corin deficiency are also encountered in patients with edema-associated diseases, highlighting the importance of ANP signaling in salt-water balance and renal pathophysiology.

State of the art of immunoassay methods for B-type natriuretic peptides: An update

The aim of this review article is to give an update on the state of the art of the immunoassay methods for the measurement of B-type natriuretic peptide (BNP) and its related peptides. Using chromatographic procedures, several studies reported an increasing number of circulating peptides related to BNP in human plasma of patients with heart failure. These peptides may have reduced or even no biological activity. Furthermore, other studies have suggested that, using immunoassays that are considered specific for BNP, the precursor of the peptide hormone, proBNP, constitutes a major portion of the peptide measured in plasma of patients with heart failure. Because BNP immunoassay methods show large (up to 50%) systematic differences in values, the use of identical decision values for all immunoassay methods, as suggested by the most recent international guidelines, seems unreasonable. Since proBNP significantly cross-reacts with all commercial immunoassay methods considered specific for BNP, manufacturers should test and clearly declare the degree of cross-reactivity of glycosylated and non-glycosylated proBNP in their BNP immunoassay methods. Clinicians should take into account that there are large systematic differences between methods when they compare results from different laboratories that use different BNP immunoassays. On the other hand, clinical laboratories should take part in external quality assessment (EQA) programs to evaluate the bias of their method in comparison to other BNP methods. Finally, the authors believe that the development of more specific methods for the active peptide, BNP1-32, should reduce the systematic differences between methods and result in better harmonization of results.

Involvement of corin downregulation in ionizing radiation-induced senescence of myocardial cells

Radiation-induced heart disease (RIHD) is becoming an increasing concern for patients and clinicians alike due to the use of radiotherapy for the treatment of breast cancer, Hodgkin's lymphoma, pediatric cancer and tumors of the thorax. However, the mechanisms underlying this phenomenon remain largely unknown. As the senescent cell fraction following irradiation is known to increase, in the present study, we investigated whether ionizing radiation (IR) causes the onset of heart disease by inducing cellular senescence in cardiomyocytes. In the present study, we evaluated the effects of IR on HL-1 and H9C2 cells, cells predominantly used in in vitro myocardial cell models. We found that the exposure of the HL-1 and H9C2 cells to IR induced reactive oxygen species (ROS)-mediated cellular senescence, as shown by staining of senescence-associated β-galactosidase (SA-β-gal). The levels of ROS in irradiated cells were determined using the fluorescent dye, 2', 7'-dichlorodihydrofluorescein diacetate (DCF-DA). Notably, the expression of corin, a cardiac protease that is essential for the proteolytic cleavage of natriuretic peptides, was significantly decreased following the exposure of the cells to IR. Importantly, the knockdown of corin by RNA interference enhanced IR-induced senescence. On the contrary, the overexpression of natriuretic peptides reversed the IR-induced senescence. Taken together, our data suggest that defects in corin function and the inhibition of natriuretic peptides following exposure to IR may contribute to the development of RIHD through the acceleration of cellular senescence.

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.

Plasma corin decreases after coronary artery bypass graft surgery and is associated with postoperative heart failure: a pilot study

OBJECTIVE

Corin is a natriuretic peptide-converting enzyme that cleaves precursor pro-B-type natriuretic peptide to active B-type natriuretic peptide (BNP) (diuretic, natriuretic, and vasodilatory properties). Increased plasma BNP is a known diagnostic and prognostic heart failure (HF) biomarker in ambulatory and surgical patients. Recent studies indicate that plasma corin is decreased significantly in chronic HF patients, yet perioperative plasma corin concentrations have not been assessed in cardiac surgical patients. The objectives of this study were to determine the effect of coronary artery bypass graft (CABG) surgery with cardiopulmonary bypass (CPB) on plasma corin concentrations and to assess the association between change in perioperative plasma corin concentration and long-term postoperative HF hospitalization or death. It was hypothesized that plasma corin concentrations decrease significantly from preoperative baseline during postoperative days 1 to 4 and that hospitalization or death from HF during the 5 years after surgery is associated with higher relative difference (preoperative baseline to postoperative nadir) in plasma corin concentrations.

DESIGN

Prospective observational pilot study.

SETTING

Two institutions: Brigham and Women's Hospital, Boston, Massachusetts and the Texas Heart Institute, St. Luke's Hospital, Houston, Texas.

PARTICIPANTS

99 patients of European ancestry who underwent isolated primary CABG surgery with CPB.

INTERVENTIONS

Nonemergency isolated primary CABG surgery with CPB.

MEASUREMENTS AND MAIN RESULTS

Plasma corin concentration was assessed preoperatively and at 4 postoperative time points (postoperative days 1-4). HF hospitalization or HF death events during the 5 years after surgery were identified by review of hospital and death records. Postoperative plasma corin concentrations were significantly lower than preoperative baseline concentrations (p<0.0001). Perioperative corin concentrations were significantly higher in males than in females (p<0.0001). Fifteen patients experienced long-term postoperative HF events. Patients who experienced HF hospitalization or HF death during study follow-up had significantly higher relative difference in plasma corin concentration (preoperative baseline to postoperative nadir) than patients who did not experience HF events during study follow-up (p=0.03).

CONCLUSIONS

Plasma corin concentrations decrease significantly from preoperative concentrations after CABG surgery. HF hospitalization or HF death during the 5 years after CABG surgery with CPB is associated with larger relative decrease in plasma corin concentration from preoperative baseline. Further investigation is warranted to determine the role of corin in postoperative HF biology.

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.

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

BACKGROUND AND OBJECTIVES

The aim of the current study was to describe the role of corin, an enzyme that cleaves pro-atrial natriuretic peptide and pro-brain natriuretic peptide into their active peptides, in patients with acute coronary syndrome (ACS).

METHODS

Serum corin level was studied in patients with non-ST-elevation ACS who underwent percutaneous coronary intervention (n=152) and in control volunteers (n=103).

RESULTS

The corin level was lower in acute coronary syndrome patients (798±288 pg/ml) than in the controls (1165±613 pg/ml, p<0.0001). Those acute coronary syndrome patients who developed major adverse cardiovascular events (MACE; 60.9%) within 3 years of discharge had lower corin levels than the patients who did not experience major adverse cardiovascular events (698.16±233.67 vs. 952.1±297.81 pg/ml, p<0.0001). Using a multiple logistic regression model, corin level was a significant predictor of post-ACS MACE: p=0.0004 for 50 pg/ml steps, AUC 0.791, while p<0.0001, and AUC 0.804 using corin and brain natriuretic peptide as predictors.

CONCLUSIONS

Patients with non-ST-elevation ACS have lower serum corin levels than controls. Corin levels are lower in ACS patients who later experience MACE and thus might be predictor for MACE. This new putative biomarker may be useful, either alone or in combination with other biomarkers, for cardiovascular risk stratification assessment and outcome prediction in ACS patients.

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.

Transcriptional profiling of left ventricle and peripheral blood mononuclear cells in a rat model of postinfarction heart failure

Background

Myocardial infarction (MI) often results in left ventricular (LV) remodeling followed by heart failure (HF). It is of great clinical importance to understand the molecular mechanisms that trigger transition from compensated LV injury to HF and to identify relevant diagnostic biomarkers. The aim of this study was to investigate gene expression in the LV and to evaluate their reflection in peripheral blood mononuclear cells (PBMCs).

Methods

MI was induced in rats by ligation of the proximal left coronary artery. Rats with small, moderate, and large MI size were included into the experiment two months after the operation. The development of heart failure was estimated by echocardiography and catheterization. Microarrays were used to compare the LV and PBMCs transcriptomes of control and experimental animals.

Results

Only rats with a large MI developed extensive LV remodeling and heart failure. 840 transcripts were altered in LV of failing hearts, and especially numerous were those associated with the extracellular matrix. In contrast, no significant gene expression changes were seen in LVs of rats with moderate or small MI that had compensated LV injury. We showed that ceruloplasmin was similarly overexpressed in the heart and blood in response to HF, whereas downregulation of tetraspanin 12 was significant only in the PBMCs.

Conclusion

A large size of infarcted area is critical for progression of LV remodeling and HF development, associated with altered gene expression in the heart. Ceruloplasmin and tetraspanin 12 are potential convenient markers in readily obtainable PBMCs.