Serum biomarkers for heart failure

Imaging characterization of myocardial function, fibrosis, and perfusion in a nonhuman primate model with heart failure-like features

Introduction

The availability of a human-like chronic heart failure (HF) animal model was critical for affiliating development of novel therapeutic drug treatments. With the close physiology relatedness to humans, the non-human primate (NHP) HF model would be valuable to better understand the pathophysiology and pharmacology of HF. The purpose of this work was to present preliminary cardiac image findings using echocardiography and cardiovascular magnetic resonance (CMR) in a HF-like cynomolgus macaque model.

Methods

The NHP diet-induced model developed cardiac phenotypes that exhibited diastolic dysfunction with reduced left ventricular ejection fraction (LVEF) or preserved LVEF. Twenty cynomolgus monkeys with cardiac dysfunction were selected by echocardiography and subsequently separated into two groups, LVEF < 65% (termed as HFrEF, n = 10) and LVEF ≥ 65% with diastolic dysfunction (termed as HFpEF, n = 10). Another group of ten healthy monkeys was used as the healthy control. All monkeys underwent a CMR study to measure global longitudinal strain (GLS), myocardial extracellular volume (ECV), and late gadolinium enhancement (LGE). In healthy controls and HFpEF group, quantitative perfusion imaging scans at rest and under dobutamine stress were performed and myocardial perfusion reserve (MPR) was subsequently obtained.

Results

No LGE was observed in any monkey. Monkeys with HF-like features were significantly older, compared to the healthy control group. There were significant differences among the three groups in ECV (20.79 ± 3.65% in healthy controls; 27.06 ± 3.37% in HFpEF group, and 31.11 ± 4.50% in HFrEFgroup, p < 0.001), as well as for stress perfusion (2.40 ± 0.34 ml/min/g in healthy controls vs. 1.28 ± 0.24 ml/min/g in HFpEF group, p < 0.01) and corresponding MPR (1.83 ± 0.3 vs. 1.35 ± 0.29, p < 0.01). After adjusting for age, ECV (p = 0.01) and MPR (p = 0.048) still showed significant differences among the three groups.

Conclusion

Our preliminary imaging findings demonstrated cardiac dysfunction, elevated ECV, and/or reduced MPR in this HF-like NHP model. This pilot study laid the foundation for further mechanistic research and the development of a drug testing platform for distinct HF pathophysiology.

Effects of ANP and BNP on the generation of respiratory rhythms in brainstem-spinal cord preparation isolated from newborn rats

Natriuretic peptides (NPs) are a family of peptide hormones produced in cardiac muscle cells and consist mainly of three types: atrial NP (ANP), B-type (or brain) NP (BNP), and C-type NP. We herein report the effects of ANP and BNP on central respiratory activity in brainstem-spinal cord preparation isolated from newborn rats. Bath application of these peptides (100 nM) induced a weak transient depression of the respiratory rhythm followed by recovery. Respiratory-related neurons in the rostral ventrolateral medulla showed a tendency for transient hyperpolarization followed by recovery during the application of ANP or BNP. The application of a membrane-permeable cGMP, 8-Br-cGMP (10 or 20 μM), did not induce significant effects on respiratory rhythm, suggesting no involvement of guanylyl cyclase in effects of ANP or BNP. We also examined effects of BNP on respiratory depression induced by the sedative dexmedetomidine, which exerts an inhibitory influence on respiratory rhythm. When pretreated with 50 nM BNP, the inhibitory effect of 100 nM dexmedetomidine was significantly reduced. Our findings suggest that ANP and BNP act as mild excitatory agents with sustained effects on respiratory rhythm after an initial transient depression.

EGFR Inhibitor Gefitinib Induces Cardiotoxicity through the Modulation of Cardiac PTEN/Akt/FoxO3a Pathway and Reactive Metabolites Formation: In Vivo and in Vitro Rat Studies

Gefitinib (GEF) is a selective inhibitor of the epidermal growth factor receptor (EGFR) used to treat non-small cell lung cancer. Yet, few cases of cardiotoxicity have been reported. However, the role of the PTEN/Akt/FoxO3a pathway, which mediates GEF anticancer activity, in GEF cardiotoxicity remains unclear. For this purpose, in vitro H9c2 cells and in vivo rat cardiomyocytes were utilized as study models. Treatment of H9c2 cells and Sprague-Dawley rats with GEF significantly induced the expression of hypertrophic and apoptotic markers at mRNA and protein levels with an increased plasma level of troponin. This was accompanied by induction of autophagy and mitochondrial dysfunction in H9c2 cells. Inhibition of cardiac EGFR activity and Akt cellular content of in vitro and in vivo rat cardiomyocytes by GEF increased PTEN and FoxO3a gene expression and cellular content. Importantly, treatment of H9c2 cells with PI3K/Akt inhibitor increased PTEN and FoxO3a mRNA expression associated with potentiation of GEF cardiotoxicity. In addition, by using LC-MS/MS, we showed that GEF is metabolized in the rat heart microsomes into one cyanide- and two methoxylamine-adduct reactive metabolites, where their formation was entirely blocked by CYP1A1 inhibitor, α-naphthoflavone. The current study concludes that GEF induces cardiotoxicity through modulating the expression and function of the cardiac PTEN/AKT/FoxO3a pathway and the formation of CYP1A1-mediated reactive metabolites.

In-hospital and long-term outcomes of congestive heart failure: Predictive value of B-type and amino-terminal pro-B-type natriuretic peptides and their ratio

Relative changes in B-type natriuretic peptide (BNP) and amino terminal pro-BNP (NT-proBNP) levels may help to assess the risk of congestive heart failure (CHF). However, whether these levels at the time of admission enable the prediction of outcomes with acute exacerbation remains unknown. The current study determined the abilities of BNP, NT-proBNP and their ratio to predict in-hospital and long-term outcomes of patients with CHF. Patients who were admitted to the cardiac care unit of Juntendo University Hospital (Tokyo, Japan) with acute CHF onset were consecutively enrolled into the present observational study. Serum levels of BNP and NT-proBNP were immediately measured on admission, and other biomarkers and clinical data were also investigated. Of 195 enrolled patients, 16 (8.2%) succumbed to CHF in hospital and 124 (69.3%) reached the endpoint of mortality or readmission following a median follow-up of 14 months. Multiple linear regression analysis revealed body mass index, low density lipoprotein cholesterol, hemoglobin, estimated glomerular filtration rate and C-reactive protein as independent predictors of the NT-proBNP/BNP ratio. BNP, NT-proBNP and their ratio were significantly higher among those who succumbed to CHF than in those who remained alive in hospital (P<0.05). Logistic regression analysis indicated that the ratio was an independent predictor for in-hospital mortality and long-term outcomes. In conclusion, the ratio of NT-proBNP to BNP more effectively predicts in-hospital outcomes than either factor alone and it may also help to predict outcomes among patients with acute exacerbation of HF.

The value of urotensin II in patients with left-sided rheumatic valvular regurgitation

Aims

Rheumatic valve diseases are most common etiological valve diseases in developing countries. Urotensin II is cardiovascular autacoid/hormone and may be associated with patients of heart valve diseases. The present study was to measure plasma urotensin II concentrations in patients with left-sided rheumatic valve diseases such as mitral regurgitation (MR) and aortic regurgitation (AR), and to examine its correlation with severity of valve impairment, function (New York Heart association, NYHA) class and pulmonary artery pressure (PAP).

Methods and results

Sixty patients with moderate to severe rheumatic left-sided valve regurgitation and 20 healthy controls were selected after performing the echocardiography. Plasma urotensin II level was measured in all subjects. The patients with MR and AR were significantly increased of left ventricular end diastolic dimension (LVEDD), left ventricular end systolic dimension (LVESD), left atrial diameter, PAP, but decreased of EF% versus the controls. Urotensin II level was highly significant in patients with MR (1.83 ± 0.92 ng/ml, P < 0.001) and AR (0.79 ± 0.3 ng/ml, P < 0.05) versus the controls (0.48 ± 0.13 ng/ml). Also, there was significant correlation between Urotensin II level and LVEDD (MR, r = 0.318, P = 0.03; AR, r = 0.805, P < 0.001), LVESD (MR, r = −0.271, P = 0.115; AR, r = 0.614, P = 0.001), and PAP (MR, r = 0.706, P < 0.001; AR, r = 0.129, P = 0.538).

Conclusion

Urotensin II was elevated in patients with rheumatic left-sided valvular regurgitation, and positively correlated with increased LVEDD (in both MR and AR), LVESD (only AR) and pulmonary artery pressure (only MR). Therefore, urotensin II level may be used as diagnostic biomarker in patients with rheumatic valvular diseases for assessment of the severity in parallel with echocardiography.

Molecular mechanisms of cardiotoxicity of gefitinib in vivo and in vitro rat cardiomyocyte: Role of apoptosis and oxidative stress

Gefitinib (GEF) is a multi-targeted tyrosine kinase inhibitor with anti-cancer properties, yet few cases of cardiotoxicity has been reported as a significant side effect associated with GEF treatment. The main purpose of this study was to investigate the potential cardiotoxic effect of GEF and the possible mechanisms involved using in vivo and in vitro rat cardiomyocyte model. Treatment of rat cardiomyocyte H9c2 cell line with GEF (0, 1, 5, and 10μM) caused cardiomyocyte death and upregulation of hypertrophic gene markers, such as brain natriuretic peptides (BNP) and Beta-myosin heavy chain (β-MHC) in a concentration-dependent manner at the mRNA and protein levels associated with an increase in the percentage of hypertrophied cardiac cells. Mechanistically, GEF treatment caused proportional and concentration-dependent increases in the mRNA and protein expression levels of apoptotic markers caspase-3 and p53 which was accompanied with marked increases in the percentage of H9c2 cells underwent apoptosis/necrosis as compared to control. In addition, oxidative stress marker (heme oxygenase-1, HO-1) and the formation of reactive oxygen species were increased in response to GEF treatment. At the in vivo level, treatment of Wistar albino rats for 21days with GEF (20 and 30mg/kg) significantly increased the cardiac enzymes (CK, CKmb, and LDH) levels associated with histopathological changes indicative of cardiotoxicity. Similarly, in vivo GEF treatment increased the mRNA and protein levels of BNP and β-MHC whereas inhibited the antihypertrophoic gene (α-MHC) associated with increased the percentage of hypertrophied cells. Furthermore, the mRNA and protein expression levels of caspase-3, p53, and HO-1 genes and the percentage of apoptotic cells were significantly increased by GEF treatment, which was more pronounced at the 30mg/kg dose. In conclusion, GEF induces cardiotoxicity and cardiac hypertrophy in vivo and in vitro rat model through cardiac apoptotic cell death and oxidative stress pathways.

Mitogen-activated protein kinases pathways mediate the sunitinib-induced hypertrophy in rat cardiomyocyte H9c2 cells

Sunitinib (SUN) is a multi-targeted tyrosine kinase inhibitor used for the treatment of gastrointestinal stromal tumors and renal cell carcinoma. Cardiotoxicity has been reported as a significant side effect associated with the SUN treatment, yet the mechanism is poorly understood. The main purpose of this study was to investigate the potential effects of SUN on cardiac hypertrophic genes and the role of mitogen-activated protein kinases (MAPKs) signaling pathway in rat cardiomyocyte H9c2 cell line. In the present study, real-time quantitative polymerase chain reaction showed that the treatment of H9c2 cells with increasing concentrations of SUN (0, 1, 2.5, and 5 µM) significantly induced hypertrophic gene markers, such as brain natriuretic peptides (BNP) and myosin heavy chain (β-MHC and α-MHC) in concentration- and time-dependent manners. The onset of mRNA induction was observed as early as 9 h and remained elevated for at least 18 h after treatment with SUN 5 µM. At the protein level, Western blot analysis showed that SUN increased BNP and β-MHC, while it inhibited α-MHC protein levels in a concentration-dependent manner. These SUN-mediated effects were associated with increase in cell size and hypertrophy by approximately 70 % at the highest concentration, 5 µM. Importantly, inhibition of the MAPK signaling pathway using SB203580 (p38 MAPK inhibitor), U0126 (extracellular signal-regulated kinase inhibitor), and SP600125 (c-Jun NH2-terminal kinase inhibitor) significantly potentiated the SUN-induced BNP and β-MHC mRNA levels, but did alter the α-MHC level. Whereas at the protein level, MAPK inhibitors generally decreased the SUN-induced BNP, whereas only SB and U0 increased β-MHC protein levels with no effect on α-MHC, which were associated with a significant decrease in cell size. Together, these results indicate that SUN induced hypertrophic gene expression through MAPK-dependent mechanisms.

Effect on the Gastrointestinal Absorption of Drugs from Different Classes in the Biopharmaceutics Classification System, When Treating with Liraglutide

Like other GLP-1 receptor agonists used for treatment of type 2 diabetes, liraglutide delays gastric emptying. In this clinical absorption study, the primary objective was to investigate the effect of liraglutide (at steady state) on the rate and/or extent of gastrointestinal (GI) absorption of concomitantly orally taken drugs from three classes of the Biopharmaceutics Classification System (BCS). To provide a general prediction on liraglutide drug-drug absorption interaction, single-dose pharmacokinetics of drugs representing BCS classes II (low solubility-high permeability; atorvastatin 40 mg and griseofulvin 500 mg), III (high solubility-low permeability; lisinopril 20 mg), and IV (low solubility-low permeability; digoxin 1 mg) were studied in healthy subjects at steady state of liraglutide 1.8 mg, or placebo, in a two-period crossover design. With liraglutide, the oral drugs atorvastatin, lisinopril, and digoxin showed delayed tmax (by ≤2 h) and did not meet the criterion for bioequivalence for Cmax (reduced Cmax by 27-38%); griseofulvin had similar tmax and 37% increased Cmax. Although the prespecified bioequivalence criterion was not met by all drugs, the overall plasma exposure (AUC) of griseofulvin, atorvastatin, lisinopril, and digoxin only exhibited minor changes and was not considered to be of clinical relevance.

Vascular endothelial growth factor-induced neovascularization rescues cardiac function but not adverse remodeling at advanced ischemic heart disease

OBJECTIVE

Proangiogenic therapy is a promising avenue for the treatment for chronic heart failure and a potentially powerful modality for reversing adverse cardiac remodeling. There is a concern, however, that adverse remodeling might enter an irreversible stage, and become refractory to treatments. The present study aims to determine whether neovascularization therapy is feasible at end stage heart failure and its capacity to reverse adverse cardiac remodeling during progressive disease stages.

METHODS AND RESULTS

Using a conditional transgenic mouse system for generating escalating levels of myocardium-specific vascular deficit and resultant stepwise development of heart remodeling, we show that left ventricular dilatation and fibrosis precede ventricular hypertrophy, but that interstitial fibrosis is progressive and eventually results in heart failure. Vascular endothelial growth factor-mediated neovascularization was efficient even at the end stage of disease, and rescued compromised contractile function. Remarkably, remodeling was also fully reversed by neovascularization during early and late stages. Adverse remodeling could not be rescued, however, at the end stage of the disease, thus defining a point of no return and indentifying a critical level of fibrosis as the key determinant to be considered in intended reversal.

CONCLUSIONS

The study supports the notion of a restricted golden time for remodeling reversal but not for vascular endothelial growth factor-induced neovascularization, which is feasible even during advanced disease stages.

Relation of natriuretic peptide concentrations to central sleep apnea in patients with heart failure

BACKGROUND

Central sleep apnea (CSA) is frequent among patients with heart failure (HF) and associated with increased morbidity and mortality. Elevated cardiac filling pressures promote CSA and atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) secretion. We hypothesized that circulating natriuretic peptide concentrations predict CSA.

METHODS

Consecutive patients with HF (n = 44) with left ventricular ejection fraction (LVEF) ≤ 35% underwent polysomnography for detection of CSA. CSA was defined as an apnea-hypopnea index ≥ 15 with ≥ 50% central apneic events. The relation of natriuretic peptide concentrations to CSA was evaluated by estimation of ORs and receiver operator characteristics (ROCs).

RESULTS

Twenty-seven subjects (61%) had CSA, with men more frequently affected than women (73% vs 27%; OR, 7.1; P = .01); given that only three women had CSA, further analysis was restricted to men. Subjects with CSA had higher mean ANP (4,336 pg/mL vs 2,510 pg/mL, P = .03) and BNP concentrations (746 pg/mL vs 379 pg/mL, P = .05). ANP and BNP concentrations were significantly related to CSA (OR, 3.7 per 3,000 pg/mL, P = .03 and OR, 1.5 per 200 pg/mL, P = .04, respectively), whereas age, LVEF, and New York Heart Association functional class were not. Concentrations of ANP and BNP were predictive of CSA as ROC demonstrated areas under the curve of 0.75 and 0.73, respectively.

CONCLUSIONS

Risk of CSA is related to severity of HF. ANP and BNP concentrations performed similarly for detection of CSA; low concentrations appear associated with low risk for CSA in men.

Role of urotensin II in health and disease

Urotensin II (UII) is an 11 amino acid cyclic peptide originally isolated from the goby fish. The amino acid sequence of UII is exceptionally conserved across most vertebrate taxa, sharing structural similarity to somatostatin. UII binds to a class of G protein-coupled receptor known as GPR14 or the urotensin receptor (UT). UII and its receptor, UT, are widely expressed throughout the cardiovascular, pulmonary, central nervous, renal, and metabolic systems. UII is generally agreed to be the most potent endogenous vasoconstrictor discovered to date. Its physiological mechanisms are similar in some ways to other potent mediators, such as endothelin-1. For example, both compounds elicit a strong vascular smooth muscle-dependent vasoconstriction via Ca2+ release. UII also exerts a wide range of actions in other systems, such as proliferation of vascular smooth muscle cells, fibroblasts, and cancer cells. It also 1) enhances foam cell formation, chemotaxis of inflammatory cells, and inotropic and hypertrophic effects on heart muscle; 2) inhibits insulin release, modulates glomerular filtration, and release of catecholamines; and 3) may help regulate food intake and the sleep cycle. Elevated plasma levels of UII and increased levels of UII and UT expression have been demonstrated in numerous diseased conditions, including hypertension, atherosclerosis, heart failure, pulmonary hypertension, diabetes, renal failure, and the metabolic syndrome. Indeed, some of these reports suggest that UII is a marker of disease activity. As such, the UT receptor is emerging as a promising target for therapeutic intervention. Here, a concise review is given on the vast physiologic and pathologic roles of UII.

Diagnostic performance of mid-regional pro-adrenomedullin as an analyte for the exclusion of left ventricular dysfunction

AIMS

In ambulatory patients with coronary artery disease (CAD) we aimed to evaluate the diagnostic performance of mid-regional pro-adrenomedullin (MR-proADM) for the detection or exclusion of impaired left ventricular ejection fraction (LVEF).

METHODS AND RESULTS

MR-proADM levels were measured in blood samples taken from 102 outpatients with CAD classified according to the New York Heart Association (NYHA) and Canadian Cardiovascular society (CCS) I-II. Increased levels of MR-proADM correlated with impaired LVEF (r=-0.21, p=0.046). The optimal threshold of MR-proADM for identification of impaired LVEF <50% was 0.54 nmol/L with an area under the ROC curve (AUC) of 0.64 (p=0.06). In univariate and multivariate calculation, MR-proADM >0.54 nmol/L remained associated with left ventricular dysfunction even after adjusting for age and gender. The negative predictive value (NPV) for MR-proADM <or=0.54 nmol/L was 88%, the specificity was 66%.

CONCLUSIONS

We showed that MR-proADM is related to impaired LVEF. With an NPV of 88% MR-proADM might be a supportive tool to exclude negatively tested outpatients with CAD from further LVEF-diagnosis with moderate reliability.

Evaluation of postmortem measurement of NT-proBNP as a marker for cardiac function

Clinical biomarkers of cardiac function could also be monitored postmortem. Among the natriuretic peptides, the aminoterminal portion of pro-brain natriuretic peptide (NT-proBNP) appears to be a more reliable postmortem tool than the BNP, owing to its longer half-life and greater stability. In living persons, NT-proBNP is considered to be a marker of heart failure, and its level rises after cardiac ischemia. The goal of this study was first to evaluate the postmortem stability of NT-proBNP, then to measure the NT-proBNP levels in postmortem cases of heart failure related to coronary ischemia. The goal of this study was also to evaluate the correlations between different specimens collected at autopsy (e.g. blood, serum, vitreous humor and pericardial fluid). The study included 96 cases, which were classified into 4 groups according to the autopsy and histological findings. The NT-proBNP levels were significantly higher in individuals who had suffered from chronic cardiac ischemia, with or without acute coronary events, than in either control cases or those who had suffered from acute thromboembolism or acute rupture of a plaque without chronic cardiac ischemia. The highest levels were registered in individuals who had suffered from acute coronary thromboembolism in association with chronic coronary ischemia. Good correlations in the NT-proBNP levels for the different specimens were observed between samples of femoral blood, serum, and pericardial fluid. Our data indicated that postmortem measurements of NT-proBNP are reliable and compatible with clinical findings.

Hyperthyroidism may affect serum N-terminal pro-B-type natriuretic peptide levels independently of cardiac dysfunction

BACKGROUND AND AIM

It is known that NT-proBNP levels increase in cardiac failure. However, NT-proBNP levels in different thyroid states are still unclear. We aimed to evaluate serum NT-proBNP levels in both hyperthyroid and hypothyroid patients without cardiac insufficiency.

SUBJECTS AND METHODS

Thirty-six patients with hyperthyroidism (42.9 +/- 16.7 years), 25 patients with hypothyroidism (35.4 +/- 13.9 years) and 34 age-matched euthyroid subjects (41.4 +/- 13.8 years) were included in the study. After anthropometric evaluations, body fat analyses were determined by bioelectrical impedance. Electrocardiography and echocardiography were used in cardiac evaluations. Serum NT-proBNP was measured by immunoassay.

RESULTS

Mean serum NT-proBNP levels in hyperthyroid patients were higher than in both control subjects (13.65 +/- 13.02 vs. 6.50 +/- 4.83 pmol/l, P = 0.002) and hypothyroid patients (13.65 +/- 13.02 vs. 5.98 +/- 5.08 pmol/l, P = 0.003). However, mean serum NT-proBNP levels in hypothyroid patients were not different from those in control subjects. There was a positive correlation between serum NT-proBNP and thyroid hormones (NT-proBNP and FT3: r = 0.324, P = 0.001; NT-proBNP and FT4: r = 0.269, P = 0.009, respectively). Serum NT-proBNP levels were positively correlated with left ventricle end-diastolic diameters (r = 0.232, P = 0.04), interventricular septum thickness (r = 0.315, P = 0.006), and negatively correlated with left ventricular ejection fraction (r = -0.238, P = 0.04).

CONCLUSIONS

Serum NT-proBNP levels may increase in hyperthyroidism independently of cardiac insufficiency. Therefore, hyperthyroidism may lead to cardiac ultrastructural changes undetermined by conventional echocardiography and these changes may be responsible for elevation of NT-proBNP levels. In contrast to decreased thyroid hormones, excess thyroid hormones may have a more pronounced effect on serum NT-proBNP levels.