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Table of Contents
RESEARCH ARTICLE
Year : 2019  |  Volume : 4  |  Issue : 4  |  Page : 111-115

Correlation between myocardial myosin-binding protein C, hypertension with left ventricular enlargement, and dilated cardiomyopathy


Department of Cardiology, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China

Date of Submission05-Aug-2019
Date of Decision16-Dec-2019
Date of Acceptance20-Dec-2019
Date of Web Publication31-Dec-2019

Correspondence Address:
Xin-Zheng Lu
Department of Cardiology, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu
China
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/cp.cp_25_19

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  Abstract 


Background: Dilated cardiomyopathy (DCM) is a relatively common clinical cardiac condition, and its progression will eventually lead to heart failure. Cardiac myosin-binding protein C (cMyBP-c) plays a vital role in the diastolic and contractile function of the heart muscle. At present, most of the relevant researches are focused on the genetic level. Our study discusses the expression of cMyBP-C in patients with DCM and its potential clinical application. Methodology: One hundred and twenty-two subjects were selected from the First Affiliated Hospital of Nanjing Medical University from August 2016 to October 2017. They were divided into two groups according to the left ventricular end-diastolic dimension (LVDd) as measured by echocardiography: normal (n = 34) and left ventricular enlargement (LVE) groups (n = 88). The LVE group was further divided into two subgroups according to the etiology: DCM (n = 57), and LVE due to hypertension (LVEH, n = 31). The left ventricular ejection fraction (EF%) was also defined in each group. Enzyme-linked immunosorbent assay (ELISA) was used for the determination of cMyBP-C in the serum. Results: (1) Serum cMyBP-C concentration was higher in DCM than in LVEH and control groups (P < 0.05) and (2) the LVDd, EF%, creatinine (Cr), urea (Ur), and uric acid (UA) in the DCM group were significantly higher than those in the LVEH group (P < 0.05). Conclusion: The serum level of cMyBP-C is expected to become a new biomarker for the diagnosis of DCM. Cr, Ur, and UA may be factors contributing to the development of DCM.

Keywords: Myocardial myosin-binding protein c, cMyBP-C, dilated cardiomyopathy, hypertension, left ventricular enlargement


How to cite this article:
Sun YL, Dookhun MN, Lu XZ. Correlation between myocardial myosin-binding protein C, hypertension with left ventricular enlargement, and dilated cardiomyopathy. Cardiol Plus 2019;4:111-5

How to cite this URL:
Sun YL, Dookhun MN, Lu XZ. Correlation between myocardial myosin-binding protein C, hypertension with left ventricular enlargement, and dilated cardiomyopathy. Cardiol Plus [serial online] 2019 [cited 2020 Apr 2];4:111-5. Available from: http://www.cardiologyplus.org/text.asp?2019/4/4/111/274575




  Introduction Top


Dilated cardiomyopathy (DCM) despite being the most common type of cardiomyopathies seen clinically, its pathogenesis is still unclear. DCM is a major cause of heart failure and sudden cardiac death with a 5-year survival rate of <50% after the emergence of symptoms.[1] DCM is multifactorial and complex cardiac condition involving one or more pathogenic pathways. Different pathway will yield different biomarkers.[2] Cardiac myosin-binding protein C (cMyBP-C) is a regulatory protein that is expressed in cardiomyocytes and its role in DCM, and other cardiac conditions are well-documented.[3] cMyBP-C has become a protein of interest clinically due to its potential as a novel biomarker for several cardiac conditions. Prior research regarding cMyBP-C was focused on the genetics and function of the protein. cMyBP-C plays a significant role in regulatory functions of the heart and possesses an N-terminus with multiple phosphorylation sites. The role of cMyBP-C in the pathophysiology of DCM continues to be studied. Reduced phosphorylation at the N-terminus of cMyBP-C has been observed in DCM patients.[4] Given that DCM has been linked to myocyte injury, which can cause release of related biomarkers, and the role of cMyBP-C as a serum biomarker needs to be further investigated.

The objective of this study was to analyze the difference in cMyBP-C levels between patients with DCM and left ventricular enlargement due to hypertension (LVEH) and controls. Moreover, the role of cMyBP-C as a biomarker in DCM was assessed.


  Methodology Top


Subjects

One hundred and twenty-two patients from the Cardiovascular Department of theFirst Affiliated Hospital of Nanjing Medical University from August 2016 to October 2017 were selected and enrolled in the study. The 122 subjects consisted of 88 patients with a LVE and 34 normal subjects serving as the control. DCM and hypertension can cause LVE; therefore, the 88 subjects with LVE were further divided into subgroups based on the etiology: either LVEH or DCM, as shown in [Figure 1].
Figure 1: Study population. LVE: Left ventricular enlargement, LVEH: Left ventricular enlargement due to hypertension, DCM: Dilated cardiomyopathy

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Inclusion criteria for patients with DCM are based on the diagnostic criteria for China's 2007 Cardiomyopathy Diagnosis and Treatment Recommendations:[5] (1) left ventricular end-diastolic diameter (LVDd) >5.0 cm (female) and >5.5 cm (male), (2) 1eft ventricular ejection fraction <45% and/or fractional shortening <25%, and (3) LVDd absolute index value >2.7 cm/m2 (left end-diastolic diameter absolute index = LVDd (cm) ÷ body surface area (BSA) and BSA (m2) = 0.0061 × height (cm) +0.0128 × body weight [kg]–0.1529). Patients with conditions that can cause myocardial damage such as coronary heart disease, valvular heart disease, congenital heart disease, alcoholic cardiomyopathy, pericardial disease, pulmonary hypertension, and neuromuscular disease were excluded from the study.

Inclusion criteria for patients with left ventricular enlargement due to hypertension is based on the 2010 Guidelines for the Prevention and Treatment of Hypertension in China,[6] that is, in the absence of antihypertensive drugs, blood pressure is measured three times on the same day, systolic blood pressure ≥140 mmHg, and/or diastolic blood pressure ≥90 mmHg. Patients with left ventricular enlargement and currently taking antihypertensive drugs can also be considered. The exclusion criteria were coronary heart disease, diabetes, congenital heart disease, valvular heart disease, pulmonary heart disease, and hyperthyroidism.

A total of 122 patients were enlisted in the study. There were 34 patients in the control group (20 males and 14 females, aged 23–73 years [46.09 ± 13.99]), and 88 patients with LVE (66 males and 22 females aged 25–75 years [50.88 ± 12.29]). The LVE group was further divided based on etiology into 57 cases of idiopathic DCM group and 31 cases of LVEH group [Figure 1].

Data collection

All participants gave informed consent and the hospital's institute committee approved the study protocol.

Gender, age, height, weight, related medical history, biochemical profile, and two-dimensional echocardiography were collected for each patient.

Echocardiography was performed by the Department of Cardiovascular Medicine of theFirst Affiliated Hospital of Nanjing Medical University with the Vivid E9 ultrasonic apparatus produced by the American EG Company. The parasternal long-axis view was used for echocardiographic measurement of the left ventricular end-diastolic diameter. The left ventricular ejection fraction was averaged over three cardiac cycles.

Specimen collection

All participants underwent a routine blood test after a 12-h fast. 5 ml of blood was collected in a blood tube. After being left for 2 h, it was centrifuged at 3000 rpm for 10 min at 4°C to obtain the upper serum and was collected into a 0.2 ml EP tube and subsequently stored at −80°C.

cMyBP-c content determination

Double-antibody sandwich method

The immunologically active cMyBP-C antibody was coated in a 96-well microplate.

As a solid phase carrier, a standard or sample is added to the microplate, wherein cMyBp-C is combined with an antibody attached to the solid support to form an antigen-antibody complex, and then, biotinylated cMyBP-c antibody is added. After washing the unbound biotinylated antibody, Horseradish Peroxidase (HRP)-labeled avidin was added, washed again, and TMB substrate was added for the color development. TMB is converted to a blue color by peroxidase catalysis and eventually converted to yellow under the action of an acid. The color intensity is positively correlated with the amount of cMyBP-C in the sample. The absorbance (Optical Density (OD) value) was measured at 450 nm using a microplate reader to calculate the sample concentration.

Data analysis

After measuring the OD value of each standard, a standard curve was obtained to get the appropriate equation. The content of the sample was then interpolated.

Statistical method

Statistical analysis was performed using the SPSS software version 23.0 (IBM SPSS Statistics for Windows, Version 23.0. Armonk, NY: IBM Corp; 2015). Data were expressed as mean ± standard deviation. The comparison between the two groups was analyzed by independent sample t-test; the data of nonnormal distribution were expressed by median and quartile and then converted into normal distribution data for the analysis. The Pearson correlation analysis method was used for the correlation analysis. Statistical significance was defined as P < 0.05.


  Results Top


Serum cMyBP-C content in control group, left ventricular enlargement due to hypertension group, and dilated cardiomyopathy group

There was no significant difference in serum cMyBP-C between the control and the LVEH groups [Table 1] and [Figure 2]. The level of cMyBP-c in the DCM group was significantly higher than that in the control and the LVEH groups.
Table 1: Comparison of cardiac myosin binding protein C content in each group

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Figure 2: Comparison of 1/cMyBP-C content in each group

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Comparison of clinical data between the control and dilated cardiomyopathy groups

There was no significant difference in gender, age, body mass index, fasting blood glucose, triglycerides, total cholesterol, high-density lipoprotein cholesterol (HDLC), low-density lipoprotein cholesterol (LDLC), and total bilirubin between the control and DCM groups (P > 0.05).

The measured Cr, (Ur, UA, and LVDd levels in the DCM group were significantly higher than those in the controls, and the EF value was significantly lower in patients with DCM [Table 2], P < 0.05].
Table 2: Comparison of 2 groups of clinical data

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There was no significant correlation between cMyBP-C content and Cr [Figure 3], Ur [Figure 4], UA [Figure 5], EF [Figure 6], and LVDd [Figure 7] in the DCM group [Table 3].
Figure 3: Correlation between serum cMyBP-C and serum creatinine in patients with dilated cardiomyopathy R =0.108, P = 0.424

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Figure 4: Correlation between serum cMyBP-C and serum urea in patients with dilated cardiomyopathy R =0.225, P =0.092

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Figure 5: Correlation between serum cMyBP-C and serum

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Figure 6: Correlation analysis of serum cMyBP-C and left ventricular ejection fraction in the dilated cardiomyopathy group, R = 0.216, P = 0.106

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Figure 7: Correlation analysis between serum cMyBP-C and left ventricular end-diastolic diameter in dilated cardiomyopathy group R = -0.210, P = 0.11

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Table 3: Correlation analysis between cardiac myosin binding protein C content and other clinical indicators

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  Discussion Top


Myosin Binding Protein-C exists into three isoforms: fast skeletal muscle type (C1), slow skeletal muscle type (C2), and myocardial type (C3). cMyBP-C (C3) is a myocardial-specific protein that is almost exclusively found in cardiomyocytes[7] and has been found to regulate myocardial contraction and relaxation. Contraction and relaxation of the myocardium depend on intact sarcolemma activity and normal coordination of various parts. cMyBP-C is easily soluble and releasable from the sarcomere following cardiac injury. Several reports have confirmed the use of cMyBP-C as a biomarker for myocardial injury.[8],[9] There is a lack of literature regarding the role of cMyBP-C as a biomarker in DCM.

Abnormal levels of cMyBP-C were previously reported in patients with heart failure with or without preserved ejection fraction as compared to controls.[10] Moreover, El Amrousy et al. demonstrated that serum cMyBP-C content in heart failure was significantly higher than the control group,[11] which is consistent with our finding. Several mechanisms could account for an increase in plasma levels of cMyBP-C such as proteolysis and dephosphorylation in the absence of necrosis or apoptosis.[12]

The diagnosis of DCM is mainly characterized by left ventricular or bi-ventricular enlargement on echocardiography. However, there are other causes of ventricular enlargement caused by secondary factors. We, therefore, have included a group of patients with left ventricular enlargement due to hypertension (LVEH group) as a subcontrol group for comparison purposes of understanding the correlation between cMyBP-C and left ventricular enlargement due to hypertension. Our study showed no significant difference in serum cMyBP-C between the controls and the hypertensive patients with LVE. However, the serum cMyBP-C levels of DCM patients were significantly higher than both control and LVEH patients, indicating that cMyBP-C release is unlikely to be involved in the pathogenesis of LVE due to hypertension.

There have been numerous reports of the influence of gene mutations expressing cMyBP-C in the development of DCM. Mutations in the gene encoding this protein can lead to a decrease in myocardial contraction and function, but how the structure of the protein or its mechanism of action changes after gene mutation is still unclear.

There is an effort to define the relationship of circulating cMyBP-C in the blood and acute myocardial infarction or heart. In this study, DCM patients were studied against healthy controls, and the ELISA method was used to determine the serum cMyBP-C content. The results were consistent with previously existing reports. The method used to detect circulating cMyBP-C is easy, safe, convenient, and cost-effective. The results of this study may contribute to the use of serum cMyBP-C as a method for risk assessment and clinical diagnosis of DCM in future. At the same time, there were some shortcomings in this study.

First, there was likely recall bias and selection bias, resulting in an inaccurate collection of relevant information. Second, due to limited operating techniques and experimental conditions, systematic errors occur during the detection process. Third, we failed to compare the effect of treatment on the level of circulating cMyBP-C prior and post-therapy. Fourth, several secondary conditions lead to left ventricular enlargement. This study only considered the factor of hypertension. Fifth, we also did not perform coronary angiography to exclude the possibility of coronary heart diseases in the DCM patients. Moreover, we fail to analyse the relationship between cMyBP-c and other biomarkers of heart failure such as BNP or NT-ProBNP.


  Conclusion Top


  1. There was no significant difference in serum cMyBP-C between the control and LVEH groups, suggesting that secondary LVE may have little effect on cMyBP-C release
  2. The serum cMyBP-C level in the DCM group was higher than that in control and the hypertensive groups with LVE. The difference was statistically significant, suggesting that there may be changes in the cMyBP-C protein during the development of DCM. cMyBP-C protein has potential to be a new biomarker for the diagnosis of DCM
  3. There were significant differences in Cr, Ur, and UA between the DCM group and the normal control group, indicating that the above three factors may be associated with DCM.


Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Towbin JA, Bowles NE. The failing heart. Nature 2002;415:227-33.  Back to cited text no. 1
    
2.
Dookhun MN, Sun Y, Zou H, Cao X, Lu X. Classification of new biomarkers of dilated cardiomyopathy based on pathogenesis – An update. Health 2018;10:300-12.  Back to cited text no. 2
    
3.
Sun Y, Dookhun MN, Zou H, Cao X, Zhang Y, Lu X. Research progress of cardiac myosin binding protein C in dilated cardiomyopathy and other cardiac conditions. World J Cardiovasc Dis 2018;08:452-61.  Back to cited text no. 3
    
4.
Copeland O, Sadayappan S, Messer AE, Steinen GJ, van der Velden J, Marston SB. Analysis of cardiac myosin binding protein-C phosphorylation in human heart muscle. J Mol Cell Cardiol 2010;49:1003-11.  Back to cited text no. 4
    
5.
Chinese Medical Association Cardiovascular Disease Branch, Editorial Board of Chinese Journal of Cardiovascular Diseases, China Cardiomyopathy Diagnosis and Treatment Recommendation Working Group. Cardiomyopathy diagnosis and treatment recommendations. Chin J Cardiovasc Dis 2007;35:5-16.  Back to cited text no. 5
    
6.
Lisheng L. Guidelines for prevention and treatment of hypertension in China 2010. Chin Med Front Mag Electron Ed 2011;39:701-8.  Back to cited text no. 6
    
7.
Oakley CE, Chamoun J, Brown LJ, Hambly BD. Myosin binding protein-C: Enigmatic regulator of cardiac contraction. Int J Biochem Cell Biol 2007;39:2161-6.  Back to cited text no. 7
    
8.
Govindan S, Kuster DW, Lin B, Kahn DJ, Jeske WP, Walenga JM, et al. Increase in cardiac myosin binding protein-C plasma levels is a sensitive and cardiac-specific biomarker of myocardial infarction. Am J Cardiovasc Dis 2013;3:60-70.  Back to cited text no. 8
    
9.
Govindan S, McElligott A, Muthusamy S, Nair N, Barefield D, Martin JL, et al. Cardiac myosin binding protein-C is a potential diagnostic biomarker for myocardial infarction. J Mol Cell Cardiol 2012;52:154-64.  Back to cited text no. 9
    
10.
Jeong EM, Zhou L, Xie A, Liu M, Zhou A, Liu H, et al. Heart failure and cardiomyopathies. JACC 2015;65:993.  Back to cited text no. 10
    
11.
El Amrousy D, Hodeib H, Suliman G, Hablas N, Salama ER, Esam A. Diagnostic and prognostic value of plasma levels of cardiac myosin binding protein-C as a novel biomarker in heart failure. Pediatr Cardiol 2017;38:418-24.  Back to cited text no. 11
    
12.
Sadayappan S, Osinska H, Klevitsky R, Lorenz JN, Sargent M, Molkentin JD, et al. Cardiac myosin binding protein C phosphorylation is cardioprotective. Proc Natl Acad Sci U S A 2006;103:16918-23.  Back to cited text no. 12
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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