Secretoneurin facilitates endothelium-dependent relaxations in porcine coronary arteries

Prognostic value of plasma secretoneurin concentration in patients with heart failure with reduced ejection fraction in one-year follow-up

BACKGROUND

This is the first study to examine the clinical utility of measuring plasma secretoneurin (SN) levels in patients with heart failure with reduced ejection fraction (HFrEF), as a predictor of unplanned hospitalization, and all-cause mortality independently, and as a composite endpoint at one-year follow-up.

METHODS

The study group includes 124 caucasian patients in New York Heart Association (NYHA) classes II to IV. Plasma SN concentrations were statistically analyzed in relation to sex, age, BMI, etiology of HFrEF, pharmacotherapy, clinical, laboratory and echocardiographic parameters. Samples were collected within 24 h of admission to the hospital.

KEY RESULTS

In the 12-month follow-up, high SN levels were noted for all three endpoints.

CONCLUSIONS

SN positively correlates with HF severity measured by NYHA classes and proves to be a useful prognostic parameter in predicting unplanned hospitalizations and all-cause mortality among patients with HFrEF. Patients with high SN levels may benefit from systematic follow-up and may be candidates for more aggressive treatment.

Young hearts, early risks: novel cardiovascular biomarkers in former very preterm infants at kindergarten age

BACKGROUND

Preterm birth is associated with long-term cardiovascular morbidity and mortality. In adults, fibroblast growth factor-23 (FGF-23), α-Klotho, and secretoneurin have all garnered attention as cardiovascular biomarkers, but their utility in pediatric populations has not yet been ascertained. The aim of this pilot study was to evaluate these novel cardiovascular biomarkers and their association with indicators of cardiovascular impairment in the highly vulnerable population of former very preterm infants.

METHODS

Five- to seven-year-old children born at < 32 weeks' gestation were eligible for the study. Healthy same-aged children born at term served as controls. Biomarkers were quantified in fasting blood samples, and echocardiographic measurements including assessment of aortic elastic properties were obtained.

RESULTS

We included 26 former very preterm infants and 21 term-born children in the study. At kindergarten age, former very preterm infants exhibited significantly higher plasma concentrations of biologically active intact FGF-23 (iFGF-23; mean 43.2 pg/mL vs. 29.1 pg/mL, p = 0.003) and secretoneurin (median 93.8 pmol/L vs. 70.5 pmol/L, p = 0.046). iFGF-23 inversely correlated with distensibility of the descending aorta.

CONCLUSION

In preterm-born children, iFGF-23 and secretoneurin both offer prospects as valuable cardiovascular biomarkers, potentially allowing for risk stratification and timely implementation of preventive measures.

IMPACT

Former very preterm infants have increased plasma concentrations of the novel cardiovascular biomarkers intact fibroblast growth factor-23 (iFGF-23) and secretoneurin at kindergarten age. Increases in iFGF-23 concentrations are associated with decreased distensibility of the descending aorta even at this early age. Monitoring of cardiovascular risk factors is essential in individuals with a history of preterm birth. Both iFGF-23 and secretoneurin hold promise as clinically valuable biomarkers for risk stratification, enabling the implementation of early preventive measures.

Secretoneurin as a Novel Biomarker of Cardiovascular Episodes: Are We There Yet? A Narrative Review

Secretoneurin (SN) is a 33 amino-acid evolutionary conserved neuropeptide from the chromogranin peptide family. SN's main effects may be cardioprotective and are believed to be mediated through its inhibition of calmodulin-dependent kinase II (CaMKII), which influences intracellular calcium handling. SN inhibition of CaMKII suppresses calcium leakage from the sarcoplasmic reticulum through the ryanodine receptor. This action may reduce the risk of ventricular arrhythmias and calcium-dependent remodelling in heart failure. SN is also involved in reducing the intracellular reactive oxygen species concentration, modulating the immune response, and regulating the cell cycle, including apoptosis. SN can predict mortality in different disease states, beyond the classical risk factors and markers of myocardial injury. Plasma SN levels are elevated soon after an arrhythmogenic episode. In summary, SN is a novel biomarker with potential in cardiovascular medicine, and probably beyond.

The Emerging Roles of Chromogranins and Derived Polypeptides in Atherosclerosis, Diabetes, and Coronary Heart Disease

Chromogranin A (CgA), B (CgB), and C (CgC), the family members of the granin glycoproteins, are associated with diabetes. These proteins are abundantly expressed in neurons, endocrine, and neuroendocrine cells. They are also present in other areas of the body. Patients with diabetic retinopathy have higher levels of CgA, CgB, and CgC in the vitreous humor. In addition, type 1 diabetic patients have high CgA and low CgB levels in the circulating blood. Plasma CgA levels are increased in patients with hypertension, coronary heart disease, and heart failure. CgA is the precursor to several functional peptides, including catestatin, vasostatin-1, vasostatin-2, pancreastatin, chromofungin, and many others. Catestatin, vasostain-1, and vasostatin-2 suppress the expression of vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 in human vascular endothelial cells. Catestatin and vasostatin-1 suppress oxidized low-density lipoprotein-induced foam cell formation in human macrophages. Catestatin and vasostatin-2, but not vasostatin-1, suppress the proliferation and these three peptides suppress the migration in human vascular smooth muscles. Chronic infusion of catestatin, vasostatin-1, or vasostatin-2 suppresses the development of atherosclerosis of the aorta in apolipoprotein E-deficient mice. Catestatin, vasostatin-1, vasostatin-2, and chromofungin protect ischemia/reperfusion-induced myocardial dysfunction in rats. Since pancreastatin inhibits insulin secretion from pancreatic β-cells, and regulates glucose metabolism in liver and adipose tissues, pancreastatin inhibitor peptide-8 (PSTi8) improves insulin resistance and glucose homeostasis. Catestatin stimulates therapeutic angiogenesis in the mouse hind limb ischemia model. Gene therapy with secretoneurin, a CgC-derived peptide, stimulates postischemic neovascularization in apolipoprotein E-deficient mice and streptozotocin-induced diabetic mice, and improves diabetic neuropathy in db/db mice. Therefore, CgA is a biomarker for atherosclerosis, diabetes, hypertension, and coronary heart disease. CgA- and CgC--derived polypeptides provide the therapeutic target for atherosclerosis and ischemia-induced tissue damages. PSTi8 is useful in the treatment of diabetes.

iTRAQ‑based quantitative proteomics analysis of the potential application of secretoneurin gene therapy for cardiac hypertrophy induced by DL‑isoproterenol hydrochloride in mice

A previous study by our group demonstrated a protective role of the neuropeptide secretoneurin (SN) in DL‑isoproterenol hydrochloride (ISO)‑induced cardiac hypertrophy in mice. To further characterize the molecular mechanism of SN treatment, an isobaric tags for relative and absolute quantification (iTRAQ)‑based quantitative proteomic analysis was applied to identify putative target proteins and molecular pathways. An SN expression vector was injected into the myocardial tissues of mice, and the animals were then subcutaneously injected with ISO (5 mg/kg/day) for 7 days to induce cardiac hypertrophy. The results of echocardiography and hemodynamic measurements indicated that the function of the heart impaired by ISO treatment was significantly ameliorated via SN gene injection. The investigation of heart proteomics was performed by iTRAQ‑based liquid chromatography‑tandem mass spectrometry analysis. A total of 2,044 quantified proteins and 15 differentially expressed proteins were associated with SN overexpression in mice with cardiac hypertrophy. Functional enrichment analysis demonstrated that these effects were possibly associated with metabolic processes. A protein‑protein interaction network analysis was constructed and the data indicated that apolipoprotein C‑III (Apoc3) was associated with the positive effect of SN on the induction of cardiac hypertrophy in mice. The present study proposed a potential mechanism of SN action on Apoc3 upregulation that may contribute to the amelioration of cardiac hypertrophy. These findings can aid the clinical application of SN in patients with cardiac hypertrophy.

Acute activation of endothelial AMPK surprisingly inhibits endothelium-dependent hyperpolarization-like relaxations in rat mesenteric arteries

BACKGROUND AND PURPOSE

Endothelium-dependent hyperpolarizations (EDHs) contribute to the regulation of peripheral resistance. They are initiated through opening of endothelial calcium-activated potassium channels (K_Ca ); the potassium ions released then diffuse to the underlying smooth muscle cells, causing hyperpolarization and thus relaxation. The present study aimed to examine whether or not AMPK modulates EDH-like relaxations in rat mesenteric arteries.

EXPERIMENTAL APPROACH

Arterial rings were isolated for isometric tension recording. AMPK activity and protein level were measured by ELISA and western blotting respectively.

KEY RESULTS

The AMPK activator, AICAR, reduced ACh-induced EDH-like relaxations and increased AMPK activity in preparations with endothelium; these responses were prevented by compound C, an AMPK inhibitor. AICAR inhibited relaxations induced by SKA-31 (opener of endothelial K_Ca ) but did not affect potassium-induced, hyperpolarization-attributable relaxations or increase AMPK activity in preparations without endothelium. A769662, another AMPK activator, not only caused a similar inhibition of relaxations to ACh and SKA-31 in preparations with endothelium but also inhibited hyperpolarization-attributable relaxations and augmented AMPK activity in rings without endothelium. Protein levels of total AMPKα, AMPKα1, or AMPKβ1/2 were comparable between preparations with and without endothelium.

CONCLUSIONS AND IMPLICATIONS

Activation of endothelial AMPK, by either AICAR or A769662, acutely inhibits EDH-like relaxations of rat mesenteric arteries. Furthermore, A769662 inhibits signalling downstream of smooth muscle hyperpolarization. In view of the major blunting effect of AMPK activation on EDH-like relaxations, caution should be applied when administering therapeutic agents that activate AMPK in patients with endothelial dysfunction characterized by reduced production and/or bioavailability of NO.

Secretoneurin suppresses cardiac hypertrophy through suppression of oxidant stress

The neuropeptide secretoneurin (SN) plays protective roles in myocardial ischemia. In the present study, the effect of SN in cardiac hypertrophy was investigated. We observed that, in isoproterenol (ISO) treatment induced cardiac or cardiomyocytes hypertrophy, a marked increase in the expression of endogenous SN in mouse plasma, myocardium and primary-cultured cardiomyocytes occurs. In hypertrophic mice, the heart size, heart weight/body weight (HW/BW) ratio, cardiomyocyte size, and atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) expression were significantly higher than those in controls but were effectively suppressed by SN gene therapy. Similarly, the protective effects of SN were also observed in cultured cardiomyocytes following ISO treatment. SN significantly increased the activity of catalase and superoxide dismutase (SOD) in parallel with the decrease in reactive oxygen species levels in cardiomyocytes. We observed that SN evoked the activation of all of the AMPK, P38/MAPK and ERK/MAPK pathways in cardiomyocytes, but pretreatment with only AMPK inhibitor (compound C) and ERK1/2/MAPK inhibitor (PD98059) counteracted the protective effects of SN against cardiomyocyte hypertrophy and the suppressive effects of SN on oxidant stress in cardiomyocytes. These results indicated that endogenous SN is induced in hypertrophic cardiomyocytes, and may play a protective role in the pathogenesis of cardiac hypertrophy. These results suggest that exogenous SN supplementation protects the cardiac hypertrophy induced by ISO treatment through the activation of AMPK and ERK/MAPK pathways, thus upregulating antioxidants and suppressing oxidative stress.

Thirty Years of Saying NO: Sources, Fate, Actions, and Misfortunes of the Endothelium-Derived Vasodilator Mediator

Endothelial cells control vascular tone by releasing nitric oxide (NO) produced by endothelial NO synthase. The activity of endothelial NO synthase is modulated by the calcium concentration and by post-translational modifications (eg, phosphorylation). When NO reaches vascular smooth muscle, soluble guanylyl cyclase is its primary target producing cGMP. NO production is stimulated by circulating substances (eg, catecholamines), platelet products (eg, serotonin), autacoids formed in (eg, bradykinin) or near (eg, adiponectin) the vascular wall and physical factors (eg, shear stress). NO dysfunction can be caused, alone or in combination, by abnormal coupling of endothelial cell membrane receptors, insufficient supply of substrate (l-arginine) or cofactors (tetrahydrobiopterin), endogenous inhibitors (asymmetrical dimethyl arginine), reduced expression/presence/dimerization of endothelial NO synthase, inhibition of its enzymatic activity, accelerated disposition of NO by reactive oxygen species and abnormal responses (eg, biased soluble guanylyl cyclase activity producing cyclic inosine monophosphate) of the vascular smooth muscle. Major culprits causing endothelial dysfunction, irrespective of the underlying pathological process (aging, obesity, diabetes mellitus, and hypertension), include stimulation of mineralocorticoid receptors, activation of endothelial Rho-kinase, augmented presence of asymmetrical dimethyl arginine, and exaggerated oxidative stress. Genetic and pharmacological interventions improve dysfunctional NO-mediated vasodilatations if protecting the supply of substrate and cofactors for endothelial NO synthase, preserving the presence and activity of the enzyme and reducing reactive oxygen species generation. Common achievers of such improvement include maintained levels of estrogens and increased production of adiponectin and induction of silent mating-type information regulation 2 homologue 1. Obviously, endothelium-dependent relaxations are not the only beneficial action of NO in the vascular wall. Thus, reduced NO-mediated responses precede and initiate the atherosclerotic process.

The role of neuropeptides in adverse myocardial remodeling and heart failure

In addition to traditional neurotransmitters of the sympathetic and parasympathetic nervous systems, the heart also contains numerous neuropeptides. These neuropeptides not only modulate the effects of neurotransmitters, but also have independent effects on cardiac function. While in most cases the physiological actions of these neuropeptides are well defined, their contributions to cardiac pathology are less appreciated. Some neuropeptides are cardioprotective, some promote adverse cardiac remodeling and heart failure, and in the case of others their functions are unclear. Some have both cardioprotective and adverse effects depending on the specific cardiac pathology and progression of that pathology. In this review, we briefly describe the actions of several neuropeptides on normal cardiac physiology, before describing in more detail their role in adverse cardiac remodeling and heart failure. It is our goal to bring more focus toward understanding the contribution of neuropeptides to the pathogenesis of heart failure, and to consider them as potential therapeutic targets.