Plasma levels of atrial natriuretic peptide in hypertrophic cardiomyopathy

Dysregulation of the calcium handling protein, CCDC47, is associated with diabetic cardiomyopathy

Background

Diabetes mellitus is associated with an increased risk in diabetic cardiomyopathy (DCM) that is distinctly not attributed to co-morbidities with other vasculature diseases. To date, while dysregulation of calcium handling is a key hallmark in cardiomyopathy, studies have been inconsistent in the types of alterations involved. In this study human cardiomyocytes were exposed to an environmental nutritional perturbation of high glucose, fatty acids, and l-carnitine to model DCM and iTRAQ-coupled LC–MS/MS proteomic analysis was used to capture proteins affected by the perturbation. The proteins captured were then compared to proteins currently annotated in the cardiovascular disease (CVD) gene ontology (GO) database to identify proteins not previously described as being related to CVD. Subsequently, GO analysis for calcium regulating proteins and endoplasmic/sarcoplasmic reticulum (ER/SR) associated proteins was carried out.

Results

Here, we identified CCDC47 (calumin) as a unique calcium regulating protein altered in our in vitro nutritional perturbation model. The cellular and functional role of CCDC47 was then assessed in rat cardiomyocytes. In rat H9C2 myocytes, overexpression of CCDC47 resulted in increase in ionomycin-induced calcium release and reuptake. Of interest, in a diet-induced obese (DIO) rat model of DCM, CCDC47 mRNA expression was increased in the atrium and ventricle of the heart, but CCDC47 protein expression was significantly increased only in the atrium of DIO rats compared to lean control rats. Notably, no changes in ANP, BNP, or β-MHC were observed between DIO rats and lean control rats.

Conclusions

Together, our in vitro and in vivo studies demonstrate that CCDC47 is a unique calcium regulating protein that is associated with early onset hypertrophic cardiomyopathy.

Electronic supplementary material

The online version of this article (10.1186/s13578-018-0244-0) contains supplementary material, which is available to authorized users.

Midregional pro-atrial natriuretic peptide: a novel marker of myocardial fibrosis in patients with hypertrophic cardiomyopathy

We aimed to determine the diagnostic performance of biomarkers in predicting myocardial fibrosis assessed by late gadolinium enhancement (LGE) cardiovascular magnetic resonance imaging (CMR) in patients with hypertrophic cardiomyopathy (HCM). LGE CMR was performed in 40 consecutive patients with HCM. Left and right ventricular parameters, as well as the extent of LGE were determined and correlated to the plasma levels of midregional pro-atrial natriuretic peptide (MR-proANP), midregional pro-adrenomedullin (MR-proADM), carboxy-terminal pro-endothelin-1 (CT-proET-1), carboxy-terminal pro-vasopressin (CT-proAVP), matrix metalloproteinase-9 (MMP-9), tissue inhibitor of metalloproteinase-1 (TIMP-1) and interleukin-8 (IL-8). Myocardial fibrosis was assumed positive, if CMR indicated LGE. LGE was present in 26 of 40 patients with HCM (65%) with variable extent (mean: 14%, range: 1.3-42%). The extent of LGE was positively associated with MR-proANP (r = 0.4; P = 0.01). No correlations were found between LGE and MR-proADM (r = 0.1; P = 0.5), CT-proET-1 (r = 0.07; P = 0.66), CT-proAVP (r = 0.16; P = 0.3), MMP-9 (r = 0.01; P = 0.9), TIMP-1 (r = 0.02; P = 0.85), and IL-8 (r = 0.02; P = 0.89). After adjustment for confounding factors, MR-proANP was the only independent predictor associated with the presence of LGE (P = 0.007) in multivariate analysis. The area under the ROC curve (AUC) indicated good predictive performance (AUC = 0.882) of MR-proANP with respect to LGE. The odds ratio was 1.268 (95% confidence interval 1.066-1.508). The sensitivity of MR-proANP at a cut-off value of 207 pmol/L was 69%, the specificity 94%, the positive predictive value 90% and the negative predictive value 80%. The results imply that MR-proANP serves as a novel marker of myocardial fibrosis assessed by LGE CMR in patients with HCM.

Biomarkers of pathophysiology in hypertrophic cardiomyopathy: implications for clinical management and prognosis

The study of biomarkers and their signalling pathways has allowed the development of new therapeutic strategies in a range of disorders. The aim of the present systematic review is to provide an overview of different biomarkers in patients with hypertrophic cardiomyopathy that could give some insight into the pathophysiologic mechanism(s) underlying the typical clinical and histological manifestations of the disease. Several pathophysiological models are presented and discussed, including studies that have investigated these biomarkers for diagnostic and prognostic reasons, in relation to disease progression and/or mortality.

Tachycardia-induced myocardial ischemia and diastolic dysfunction potentiate secretion of ANP, not BNP, in hypertrophic cardiomyopathy

The aim of this study was to investigate what factor determines tachycardia-induced secretion of atrial and brain natriuretic peptides (ANP and BNP, respectively) in patients with hypertrophic cardiomyopathy (HCM). HCM patients with normal left ventricular (LV) systolic function and intact coronary artery (n = 22) underwent rapid atrial pacing test. The cardiac secretion of ANP and BNP and the lactate extraction ratio (LER) were evaluated by using blood samples from the coronary sinus and aorta. LV end-diastolic pressure (LVEDP) and the time constant of LV relaxation of tau were measured by a catheter-tip transducer. These parameters were compared with normal controls (n = 8). HCM patients were divided into obstructive (HOCM) and nonobstructive (HNCM) groups. The cardiac secretion of ANP was significantly increased by rapid pacing in HOCM from 384 +/- 101 to 1,268 +/- 334 pg/ml (P < 0.05); however, it was not significant in control and HNCM groups. In contrast, the cardiac secretion of BNP was fairly constant and rather significantly decreased in HCM (P < 0.01). The cardiac ANP secretion was significantly correlated with changes in LER (r = -0.57, P < 0.01) and tau (r = 0.73, P < 0.001) in HCM patients. Tachycardia potentiates the cardiac secretion of ANP, not BNP, in patients with HCM, particularly when it induces myocardial ischemia and LV diastolic dysfunction.

Neurohumoral profiles in patients with hypertrophic cardiomyopathy: differences to hypertensive left ventricular hypertrophy

BACKGROUND

Patients with hypertrophic cardiomyopathy (HCM) or hypertensive heart disease (HHD) have increased concentrations of various neurohumoral factors. Thus, the aim of the present study was to evaluate the differences in the neurohumoral profiles of HCM and HHD.

METHODS AND RESULTS

Plasma concentrations of epinephrine, norepinephrine, atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), angiotensin II and endothelin-1 were measured in 40 patients with HCM, 35 with HHD, and 15 controls. Additionally, the concentrations of these neurohumoral factors in the coronary sinus and aortic root were measured in 12 HCM patients and 10 controls. Plasma concentrations of norepinephrine, ANP and BNP were significantly higher in HCM than HHD and controls. In HCM, there was no significant correlation between the left ventricular mass index and any neurohumoral factor. The plasma BNP concentration significantly correlated with left intraventricular pressure gradient in HCM. There were significant differences in the plasma concentrations of ANP and BNP between HCM with and without left ventricular diastolic dysfunction. Transcardiac production of BNP was significantly higher in patients with obstructive HCM than in those with non-obstructive HCM.

CONCLUSIONS

The significant neurohumoral differences between HCM and HHD were the plasma concentrations of norepinephrine, ANP and BNP. In HCM patients, the plasma BNP concentration may reflect the intraventricular pressure gradient and left ventricular diastolic dysfunction whereas the plasma ANP concentration reflects only the left ventricular diastolic dysfunction.

The molecular genetic basis for hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM), a relatively common disease, is diagnosed clinically by unexplained cardiac hypertrophy and pathologically by myocyte hypertrophy, disarray, and interstitial fibrosis. HCM is the most common cause of sudden cardiac death (SCD) in the young and a major cause of morbidity and mortality in elderly. Hypertrophy and fibrosis are the major determinants of morbidity and SCD. More than 100 mutations in nine genes, all encoding sarcomeric proteins have been identified in patients with HCM, which had led to the notion that HCM is a disease of contractile sarcomeric proteins. The beta -myosin heavy chain (MyHC), cardiac troponin T (cTnT) and myosin binding protein-C (MyBP-C) are the most common genes accounting for approximately 2/3 of all HCM cases. Genotype-phenotype correlation studies suggest that mutations in the beta -MyHC gene are associated with more extensive hypertrophy and a higher risk of SCD as compared to mutations in genes coding for other sarcomeric proteins, such as MyBP-C and cTnT. The prognostic significance of mutations is related to their hypertrophic expressivity and penetrance, with the exception of those in the cTnT, which are associated with mild hypertrophic response and a high incidence of SCD. However, there is a significant variability and factors, such as modifier genes and probably the environmental factors affect the phenotypic expression of HCM. The molecular pathogenesis of HCM is not completely understood. In vitro and in vivo studies suggest that mutations impart a diverse array of functional defects including reduced ATPase activity of myosin, acto-myosin interaction, cross-bridging kinetics, myocyte contractility, and altered Ca2+ sensitivity. Hypertrophy and other clinical and pathological phenotypes are considered compensatory phenotypes secondary to functional defects. In summary, the molecular genetic basis of HCM has been identified, which affords the opportunity to delineate its pathogenesis. Understanding the pathogenesis of HCM could provide for genetic based diagnosis, risk stratification, treatment and prevention of cardiac phenotypes.

In vivo short-term expression of a hypertrophic cardiomyopathy mutation in adult rabbit myocardium: myofibrillar incorporation without early disarray

Cardiac myocyte disarray is the pathological hallmark of hypertrophic cardiomyopathy (HCM), a disease of sarcomeric proteins. Mutations in the cardiac troponin T (cTnT), a major gene responsible for HCM, are associated with severe myocyte disarray. To study the pathogenesis of cardiac myocyte disarray, we expressed normal and mutant cTnT proteins in the myocardium of adult rabbits via direct intramyocardial injection of recombinant adenoviruses. Aliquots of 1010 plaque-forming units of normal (Ad/CMV/cTnT-Arg92) and mutant (Ad/CMV/cTnT-Gln92) recombinant viruses or a control vector (Ad/DeltaE) virus were mixed with equal aliquots of a reporter virus (Ad/CMV/Lac-Z) and co-injected into the myocardium of adult rabbits (n = 12). One week following gene transfer, thin myocardial sections were obtained and analyzed for beta-galactosidase, messenger RNA (mRNA) and protein expression, hematoxylin and eosin, Masson's trichrome, immunofluorescence staining, and electron microscopy. The efficiency of gene transfer varied from 2% to 60% of the cells in an area approximately 2.5 mm in length. Northern blotting confirmed expression of the transgenes into mRNA. Immunoblotting of the myofibrillar protein extracts and indirect immunofluorescence staining confirmed expression and incorporation of the transgene proteins into myofibrils. Expression of the mutant cTnT was up to 18% of the endogenous. Light and electron microscopic studies showed normal cardiac myocyte and sarcomere structures. Thus, despite incorporation of the mutant cTnT-Gln92, stable myofibrillar formation and sarcomere assembly proceeded in vivo. The absence of myocyte and sarcomere disarray may reflect the duration, or the level of expression, or the extent of myofibrillar incorporation of the mutant cTnT-Gln92, as well as the site and timing of expression of the transgenes, and interspecies variation in the pathogenesis of HCM.

Molecular genetic basis of hypertrophic cardiomyopathy: genetic markers for sudden cardiac death

Hypertrophic cardiomyopathy (HCM) is an autosomal dominant disease caused by mutations in sarcomeric proteins. The disease is characterized by left ventricular hypertrophy in the absence of an increased external load, and myofibrillar disarray. A large number of mutations in genes coding for the beta-myosin heavy chain (beta-MyHC), cardiac troponin T (cTnT), cardiac troponin I, alpha-tropomyosin, myosin binding protein C (MyBP-C), and myosin light chain 1 and 2 in patients with HCM have been identified. Genotype-phenotype correlation studies have shown that mutations carry prognostic significance. The Gly256Glu, Val606Met, and Leu908Val mutations in the beta-MyHC are associated with a benign prognosis. In contrast, Arg403Gln, Arg719Trp, and Arg453Cys mutations are associated with a high incidence of sudden cardiac death (SCD). Mutations in cTnT are associated with a mild degree of hypertrophy, but a high incidence of SCD. Mutations in MyBP-C are associated with mild hypertrophy and a benign prognosis. However, it has become evident that factors other than the underlying mutations, such as genetic background and possibly environmental factors, also modulate phenotypic expression of HCM.

Familial hypertrophic cardiomyopathy: diagnostic and therapeutic implications of recent genetic studies

Familial hypertrophic cardiomyopathy is the first primary cardiomyopathy to have yielded to the techniques of modern molecular genetics. In the past few years, four genes responsible for this disease have been identified, all of which code for sarcomeric structural proteins. In addition, structure-function analysis and genotype-phenotype correlation studies have shed significant light on the molecular basis of this disease. It is hoped that within the next few years the application of molecular genetic tools will not only facilitate the diagnosis of hypertrophic cardiomyopathy but will also provide prognostic and therapeutic stratification for more definitive therapy.

Plasma atrial natriuretic peptide is elevated in patients with hypertrophic cardiomyopathy

STUDY OBJECTIVES

To determine if plasma levels of atrial natriuretic peptide are elevated in patients with hypertrophic cardiomyopathy and to determine the relationship of atrial natriuretic peptide to symptoms and echocardiographic indices of left ventricular structure and diastolic function in these patients.

DESIGN

A prospective study in which atrial natriuretic peptide was measured in peripheral venous plasma in 14 patients (age 44 +/- 14 years) with hypertrophic cardiomyopathy and 17 healthy controls. Echocardiography was performed in all cases and 30 controls to examine indices of left heart structure and function. All patients underwent clinical evaluation.

RESULTS

The concentration of atrial natriuretic peptide was significantly higher in patients with hypertrophic cardiomyopathy than controls, (17.86 +/- 8.72 vs. 6.22 +/- 3.26 pmol/l, P = 0.0001). Diastolic dysfunction was observed in 11 of 14 patients with hypertrophic cardiomyopathy. No correlation was demonstrated between atrial natriuretic peptide levels and the degree of diastolic dysfunction, septal or free wall thickness, left atrial size, degree of mitral regurgitation or New York Heart Association functional class.

CONCLUSIONS

Plasma levels of atrial natriuretic peptide are elevated in patients with hypertrophic cardiomyopathy but do not correlate with symptoms or echocardiographically-derived indices of left ventricular structure or diastolic function.

Potentiation of human polymorphonuclear leukocyte activation by atrial natriuretic peptide. Inhibitory effect of carnitine congeners

Polymorphonuclear leukocytes (PMN), atrial natriuretic peptide (ANP) and leukotriene B4 (LTB4) reportedly play a major role in ischemia/reperfusion states of coronary artery disease. We sought to determine whether ANP and LTB4 cooperate in inducing PMN activation with consequent modulation of membrane molecules required for adherence to endothelium and myocardial cells, namely CD11b and L-selectin and the release of toxic oxygen radicals. ANP (from 10(-16) to 10(-8) M), LTB4 (from 10(-10) to 10(-6) M) and combinations of the two were incubated with normal PMN at 37 degrees C for 15 minutes. Membrane molecules modulation was measured by flow cytometry using specific monoclonal antibodies. Hydrogen peroxide production, an indicator of the capacity of PMN to release toxic oxygen species was quantified by flow cytometry using the peroxide-sensitive fluorescent probe dichlorofluorescein diacetate. ANP, uneffective when used alone, dose-dependently potentiated the PMN response to LTB4 (10(-9) M) as evidenced by an up-regulation of CD11b expression and peroxide production, and a down-regulation of L-selectin expression. These effects were prevented dose-dependently by the protein kinase C (PKC) inhibitor staurosporine (from 10 to 160 microM). Two carnitine congeners, palmytoylcarnitine (tested from 125 pg to 2 micrograms/ml) that also possesses an established ability to antagonise PKC and L-carnitine (tested from 12 to 200 ng/ml) were also effective. These data indicate that ANP potentiates LTB4 in inducing PMN mobilization and activation with a possible consequent detrimental effect on cardiac tissue and evisages the usefulness of PMN metabolism modulators.

Hypertrophic cardiomyopathy. Clinical spectrum and treatment

HCM is a heterogeneous disease genotypically, phenotypically, pathophysiologically, clinically, and therapeutically. In decisions on the management of these patients, it is important to recognize this heterogeneity and to direct therapy at the predominant abnormalities.

Molecular genetics of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is genetically and phenotypically a heterogeneous disease. Genes identified include the beta myosin heavy chain gene (beta MHC) on chromosome 14q1, the troponin T gene on chromosome 1q, and the alpha tropomyosin gene on chromosome 15q. In addition, a fourth locus is present on chromosome 11q11, but the gene remains to be identified. More than 35 missense mutations in the beta MHC, 3 mutations in troponin T, and 2 mutations in alpha tropomyosin gene in HCM patients have been identified. Functional studies have shown that the mutant beta MHC protein has impaired actomyosin interaction and that expression of the mutant myosin disrupts the assembly of sarcomere in feline cardiocytes. Genotype-phenotype correlations of beta MHC mutations have shown that mutations such as Arg403Gln, Arg453Cys, and Arg719Trp are associated with a high incidence of sudden cardiac death and a significantly decreased life expectancy, whereas mutations Gly256Glu and Leu908Val have a near-normal life span. Preclinical genetic diagnosis should help in genetic counseling and therapeutic stratification.