REGPEP-04509; No of Pages 4 Regulatory Peptides xxx (2014) xxx–xxx
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Serum adropin levels are decreased in patients with acute myocardial infarction Hou-you Yu a,1, Peng Zhao a,1, Ming-chun Wu b, Jian Liu a, Wen Yin a,⁎ a b
Department of Emergency Medicine, Xijing hospital, Fourth Military Medical University, No. 17 Changle West Road, Xi'an 710032, PR China Department of Anaesthiology, Wuhan general Hospital of Guangzhou Command, No. 627 Wuluo Road, Wuhan, 430070, PR China
a r t i c l e
i n f o
Article history: Received 22 January 2014 Received in revised form 16 March 2014 Accepted 1 April 2014 Available online xxxx Keywords: Coronary artery disease Atherosclerosis Acute myocardial infarction Biomarkers Adropin
a b s t r a c t Objective: Adropin is a recently identified bioactive protein that is important for energy homeostasis and maintaining insulin sensitivity. We sought to detect serum adropin levels in acute myocardial infarction (AMI) patients. Methods: We enrolled 138 AMI patients, 114 stable angina pectoris (SAP) patients and 75 controls. Adropin levels were measured by enzyme-linked immunosorbent assay (ELISA). Results: Serum adropin levels were significantly lower in patients with AMI compared with SAP patients or controls (P b 0.01). Multivariate logistic regression demonstrated that lower adropin was the independent predictor for the presence of AMI in coronary artery disease (CAD) patients (P b 0.01). Serum adropin levels were negatively associated with body mass index (BMI) (P b 0.01) and triglyceride levels (P b 0.05) in AMI patients. Conclusion: Decreased serum adropin levels are associated with the presence of AMI in CAD patients. These results revealed that adropin might represent as a novel biomarker for predicting AMI onset in CAD patients. © 2014 Elsevier B.V. All rights reserved.
1. Introduction Critical cardiovascular events such as acute myocardial infarction (AMI) remain the leading cause of morbidity and mortality worldwide. Accurate diagnosis of AMI improve prognosis through appropriate treatment without delay. In addition, biomarkers have increasingly emerged as important alternatives to traditional methods for rapid diagnosis and risk stratification of high-risk individuals [1–3]. Many blood-based protein biomarkers such as cardiac troponin (cTn) I or T, B-type natriuretic peptide (BNP) and high-sensitivity C-reactive protein (hs-CRP) has an established role in providing crucial diagnostic or prognostic value in the field of coronary artery disease (CAD). Adropin is a recently identified bioactive protein encoded by the energy homeostasis associated gene (Enho) that is expressed in the liver and the brain [4]. Adropin appears to participate in the maintenance of energy homeostasis and insulin response, which is closely related to the development and progression of atherogenesis [4]. Besides, a recent study found that adropin is also expressed in coronary artery endothelial cells and plays a potential endothelial protective role in mice [5]. It is well known that endothelial dysfunction is a key early event in atherogenesis and is integral in the onset of CAD and acute ⁎ Corresponding author. Tel./fax: +86 29 84775507. E-mail address: [email protected] (W. Yin). 1 These authors contribute equally to this paper and should be considered as Co-first authors.
coronary syndromes (ACS) [6]. More recently, Wu et al. [7] demonstrated that decreased serum adropin was an independent predictor of clinically relevant coronary atherosclerosis. Based on these findings, we hypothesized that adropin deficiency might be involved in the pathogenesis of AMI. However, the relationship between adropin concentrations and AMI has never been fully elucidated. Therefore, we aimed to detect serum adropin levels in AMI patients, and to investigate their correlation with AMI. 2. Patients and methods 2.1. Patients From August 2012 to June 2013, a total of 297 subjects admitted to Xijing hospital for coronary angiography owing to AMI (AMI group, n = 108), stable angina pectoris (SAP group, n = 114) or a clinical suspicion of CAD in subjects with multiple coronary risk factors but without lesions on angiography (controls group, n = 75) were recruited. AMI was defined by an increase in serum troponin I (2 × upper limit of the hospital normal range) associated symptoms of ischemia and/or characteristic ECG signs (ST segment-T wave changes, left bundle branch block or development of pathological Q waves) [8]. SAP was defined as no change in frequency, duration or intensity of symptoms more than 3 months before the admission. Patients were excluded on the basis of having peripheral artery disease, active inflammatory disease, autoimmune disorders, suspected myocarditis or pericarditis,
http://dx.doi.org/10.1016/j.regpep.2014.04.001 0167-0115/© 2014 Elsevier B.V. All rights reserved.
Please cite this article as: Yu H, et al, Serum adropin levels are decreased in patients with acute myocardial infarction, Regul Pept (2014), http:// dx.doi.org/10.1016/j.regpep.2014.04.001
2
H. Yu et al. / Regulatory Peptides xxx (2014) xxx–xxx
malignant disease, diabetes, severe heart failure and advanced renal and hepatic disease. Written informed consent was individually obtained regarding participation in this study. The study protocol was approved by the ethics committee of Xijing hospital.
3. Results
2.2. Blood chemistry measurement
3.1. Baseline clinical characteristics
Peripheral venous blood samples were drawn from the antecubital vein of all participants before the angiographic procedure. After clotting, the samples were immediately centrifuged and stored at −80 °C until analysis. All participants underwent conventional laboratory analyses, including determination of total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-c) and density lipoprotein cholesterol (HDL-c) using an autoanalyzer(Hitachi 7170, Hitachi Co., Japan). Hs-CRP levels were measured on an Olympus AU5400 Automatic Biochemical Analyzer (Olympus Co., Japan). N-terminal pro BNP (NTproBNP) and cTnT levels were detected in Siemens Immulite 1000 Immunoassay System (Siemens, Germany). Serum adropin levels were measured using a commercially available enzyme-linked immunosorbent assay (ELISA) kit (Cusabio Biotech Co, Wuhan, CN). The assay recognizes recombinant and natural human adropin. No significant cross-reactivity or interference was observed [9]. Test range was 0.32–20 ng/mL [9]. The sensitivity of the assay was 0.08 ng/mL, and inter-assay and intra-assay coefficients of variation (CV) were less than 14% and 5%, respectively [9]. All the serum samples were analyzed by ELISA in duplicate, and the results were averaged. Preliminary study demonstrated that adropin levels in serum are closely correlated with those in paired plasma samples.
The baseline characteristics of the three groups were shown in Table 1. Compared with controls, SAP patients had significantly higher diastolic blood pressure (SBP), LDL-c, hs-CRP and NT-proBNP levels. Compared with SAP patients, AMI patients had significantly higher hs-CRP levels as well as significantly lower HDL-c levels and left ventricular ejection fraction (LVEF). Besides, AMI patients were older than controls.
2.3. Statistical analysis All statistical analyses were performed using SPSS 17.0 for Windows version (SPSS Inc., Chicago, USA). The Kolmogorov–Smirnov test was used to analyze data normality results of normally distributed continuous variables are expressed as the mean value ± SD, and those for continuous variables with skewed distribution are expressed as the median value (interquartile range) and categorical variables as frequencies or percentages. Differences among the three groups were analyzed by one-way analysis of variance (ANOVA), followed by Tukey post hoc analysis or Kruskal–Wallis test as indicated. Multivariate logistic analysis was performed to determine the independent predictors of AMI in CAD patients. The correlation between serum adropin levels and other clinical characteristics in AMI patients was assessed by Pearson or
Spearman correlation coefficient when appropriate. Probability values (two-tailed) were considered significant at P b 0.05.
3.2. Serum adropin levels As shown in Fig. 1, our study demonstrated that SAP patients had significantly lower serum adropin levels compared to controls (3.81 ± 1.78 vs 5.12 ± 1.44 ng/ml, P b 0.01). In CAD patients, AMI patients had significantly lower serum adropin levels compared to SAP patients (2.19 ± 1.61 vs 3.81 ± 1.78 ng/ml, P b 0.01). 3.3. The independent predictors of AMI We perform multivariate logistic regression including all variables to assess the independent predictors of AMI in CAD patients. Our results revealed that lower serum levels of adropin was the significant and independent predictor of AMI in CAD patients (OR = 0.555, 95% CI = 0.438–0.704, P b 0.01; Table 2). 3.4. Correlations between adropin and other clinical characteristics in AMI patients As demonstrated in Table 3, serum adropin levels were negatively correlated with body mass index (BMI) (ρ = −0.252, P = 0.008) and TG levels in AMI patients (ρ = − 0.202, P = 0.036). However, serum adropin levels were neither correlated with cTnT levels (ρ = −0.161, P = 0.095) nor correlated with Creatine Kinase (CK)-MB levels (ρ = 0.045, P = 0.646). There was also no correlation between serum adropin levels with other conventional cardiovascular biomarkers such as hs-CRP (ρ = −0.101, P = 0.297) and NT-proBNP (ρ = −0.008, P = 0.936).
Table 1 Baseline clinical and laboratory characteristics. Variables
AMI (n = 108)
SAP patients (n = 114)
Controls (n = 75)
Age (years) Male, n (%) BMI SBP (mm Hg) DBP (mm Hg) TC (mmol/L) TG (mmol/L) LDL-c (mmol/L) HDL-c (mmol/L) FBG (mmol/L) hs-CRP (mg/L) NT-proBNP (ng/L) LVEF Smoking, n (%) On statins, n (%) On ACEI/ARB, n (%)
64.50 ± 10.53* 62 (57.41%) 25.07 (23.18–26.49) 131.76 ± 18.88 81.06 ± 10.95 4.62 ± 1.09* 1.77 (1.30–2.67) * 2.80 ± 0.80** 0.92 (0.75–1.17) **†† 5.64 (5.04–6.26) 1.68 (1.24–3.64) **†† 277 (220–324) ** 53.94 ± 11.40**†† 40 (37.04%) 21 (19.44%) 29 (26.85%)
63.67 ± 11.18 67 (58.77%) 25.12 (23.79–25.92) 135.60 ± 14.26 83.72 ± 11.92* 4.36 ± 1.06 1.61 (1.13–2.19) 2.67 ± 0.95* 1.03 (0.86–1.21) 5.62 (4.96–6.13) 0.88 (0.67–1.43) ** 282 (83–334) * 63.49 ± 8.93 40 (35.09%) 32 (28.07%) 33 (28.95%)
60.40 ± 9.58 39 (52.00%) 24.74 (23.29–25.94) 130.04 ± 16.00 79.42 ± 12.43 4.16 ± 1.04 1.50 (1.02–2.17) 2.32 ± 0.88 1.04 (0.86–1.26) 5.65 (5.12–6.16) 0.61 (0.34–0.96) 164 (58–313) 65.09 ± 7.34 22 (29.33%) 14 (18.67%) 26 (34.67%)
All values are presented as mean ± SD, median value (interquartile range) or n (%). AMI = acute myocardial infarction, SAP = stable angina pectoris, BMI = body mass index, SBP = systolic blood pressure, DBP = diastolic blood pressure, TC = total cholesterol, TG = triglycerides, LDL-c = low-density lipoprotein cholesterol, HDL-c = high density lipoprotein cholesterol, FBG = fasting glucose, hs-CRP = high-sensitivity C-reactive protein, NT-proBNP = N-terminal pro B-type natriuretic peptide, LVEF = left ventricular ejection fraction and ACEI/ARB = (on the use of) angiotensin converting enzyme inhibitor/angiotensin receptor blocker. *P b 0.05 compared with healthy controls, **P b 0.01 compared with controls; †P b 0.05 compared with SAP patients, ††P b 0.01 compared with SAP patients.
Please cite this article as: Yu H, et al, Serum adropin levels are decreased in patients with acute myocardial infarction, Regul Pept (2014), http:// dx.doi.org/10.1016/j.regpep.2014.04.001
H. Yu et al. / Regulatory Peptides xxx (2014) xxx–xxx
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Table 3 Correlations between adropin and other clinical characteristics in AMI patients.
Fig. 1. Serum adropin levels in AMI (n = 108), SAP (n = 114) patients and controls (n = 75).
4. Discussion In the current study, we found that serum adropin levels were significantly lower in patients with AMI compared with SAP patients or controls. Multivariate logistic regression demonstrated that adropin was the independent predictor for the presence of AMI in CAD patients. Additionally, we also found negative correlations between serum adropin levels and NT-proBNP and TG in AMI patients. To our best knowledge, this is the first study to investigate the relationship between serum adropin levels and AMI. Peptides secreted from peripheral organs as regulators in glucose and energy homeostasis has gained increasing interest. The adipocytesecreted hormones, termed adipokines, have an established role as the critical mediators of food intake, energy expenditure and metabolic disorders in obese people [10]. Recently, another important advance in this field is the identification of liver-derived hormones. Adropin is a recently described liver-secreted hormone that is important for energy homeostasis and maintaining insulin sensitivity [4]. Aydin et al. [11] demonstrated that adropin is expressed in brain, cerebellum, kidneys, heart, liver, pancreas and vascular tissues of diabetic rats. Adropin is a secreted protein that could be secreted into the circulation. Therefore, adropin is being explored as potential biomarkers of several diseases [9,12]. In the present study, we found decreased serum adropin levels in AMI patients compared with SAP patients or controls. As we have known, adropin expressed in the vascular tissues might transfer to the
Table 2 Multiple logistic regression analysis for the predictors of AMI. Variables
OR (95% CI)
P value
Age (per year) Male (yes) BMI SBP (per mm/Hg) DBP (per mmHg) TC (per mmol/L) TG (per mmol/L) LDL-c (per mmol/L) HDL-c (per mmol/L) FBG (per mmol/L) hs-CRP (per mg/L) NT-proBNP (per ng/L) LVEF Smoking (yes) On statins On ACEI/ARB adropin (per ng/ml)
1.016 (0.983–1.051) 0.719 (0.321–1.613) 0.857 (0.743–0.988) 0.985 (0.961–1.009) 0.963 (0.929–0.998) 1.367 (0.964–1.937) 1.025 (0.666–1.577) 1.258 (0.832–1.902) 0.404 (0.075–2.164) 0.817 (0.580–1.150) 1.388 (1.115–1.728) 1.000 (0.999–1.002) 1.107 (1.063–1.153) 1.446 (0.648–3.227) 1.889 (0.775–4.605) 0.791 (0.352–1.778) 0.555 (0.438–0.704)
0.335 0.424 0.034 0.224 0.040 0.079 0.910 0.277 0.290 0.247 0.003 0.435 b0.001 0.368 0.162 0.571 b0.001
OR = odds ratio, CI = confidence interval, other abbreviations are as in Table 1.
Variables
Correlation coefficient
P value
Age (year) BMI (kg/mm2) SBP (mm/Hg) DBP (mmHg) TC (mmol/L) TG (mmol/L) LDL-c (mmol/L) HDL-c (mmol/L) FBG (mmol/L) hs-CRP (mg/L) NT-proBNP (ng/L) LVEF cTnT (ng/ml) CK-MB (U/L)
−0.095 −0.252 −0.036 −0.074 −0.064 −0.202 −0.121 0.102 0.100 −0.101 −0.008 0.067 −0.161 0.045
0.326 0.008 0.709 0.450 0.508 0.036 0.212 0.294 0.291 0.297 0.936 0.478 0.095 0.646
cTnT = troponin T, CK-MB = creatine kinase-MB, other abbreviations are as in Table 1.
blood. Therefore, this result may reflect the deficiency of adropin expression in AMI patients. Further studies are needed to elucidate the reason for adropin deficiency in AMI patients. This result also revealed that adropin deficiency might play a pathological role in the development and progression of AMI. Lovren et al. [5] have demonstrated that adropin could enhance the expression of endothelial nitric oxide synthase (eNOS) in the endothelium via activation of vascular endothelial growth factor receptor (EGFR) 2 phosphatidylinositol 3-kinase Akt and EGFR 2 extracellular signal-regulated kinase 1/2 pathways. As eNOS is responsible for the production of vascular nitric oxide (NO) [13], adropin deficiency is associated with reduced nitric oxide bioavailability in the endothelium. Loss of NO bioavailability is a cardinal feature of endothelial dysfunction that precedes the development of overt atherosclerosis and is an independent predictor of the development of AMI [14]. Besides, the reduced circulating adropin concentrations has an important correlate of metabolic disorders associated with insulin resistance and obesity, which are related to the progression of coronary atherosclerosis and increased incidence of cardiovascular events such as AMI [4,15]. We performed multivariate logistic regression to identify independent predictors for AMI in CAD patients. The results revealed that lower serum adropin levels were independently associated with the presence of AMI in CAD patients. These results indicated that adropin appears to be a potential serum biomarker for early diagnosis of AMI in CAD patients. In addition, serum adropin levels did not show any correlation with cTnT or CK-MB in AMI patients, suggesting that adropin is not a marker for cardiac necrosis or injury. More recently, Wu et al. found that CAD patients had lower serum adropin levels compared with Non-CAD patients, and lower serum adropin was associated with greater angiographic severity of coronary atherosclerosis in both type 2 diabetic and non-diabetic patients [7]. These findings are in accordance with our results and suggested that adropin deficiency may be involved in promotion of coronary atherosclerosis and AMI. We have also investigated the relationship between adropin and other clinical characteristics in AMI patients. We have showed that serum adropin levels were negatively associated with BMI and TG levels. These results are in accordance with a previous study by Bulter et al., which demonstrated that adropin levels correlated negatively with BMI and TG in metabolic syndrome patients after gastric bypass surgery [16]. These results may be partly explained by the biological effects of adropin on increasing energy expenditure and inhibiting lipogenesis. However, Lian et al. showed that plasma adropin levels were correlated positively with BMI and the severity of heart failure in patients with heart failure, which is in contrary to our results [9]. Heart failure, which has a close relationship with obesity, is now seen as a complex pathophysiological process with activation of various neuro-endocrine systems [17].The different biochemical and neuroendocrine alterations between CAD and heart failure patients might
Please cite this article as: Yu H, et al, Serum adropin levels are decreased in patients with acute myocardial infarction, Regul Pept (2014), http:// dx.doi.org/10.1016/j.regpep.2014.04.001
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partly explain the opposite results mentioned above. However, the relationship between adropin and cardiac remodeling remain to be further investigated. The limitations of this study should be considered when interpreting our results. First, the present study is a cross-sectional study with relatively small sample size; such a study cannot establish causality. Therefore, our results should be verified in multi-center prospective longitudinal studies with larger sample size. Second, we only enrolled patients referred for the interventional diagnosis and treatment of CAD, which might induce some bias. Third, adropin is mainly expressed and produced in liver and brain. We did not evaluate the function of these relevant organs, which might contribute as potential confounders in the analysis of serum adropin levels. In conclusion, this study reported decreased serum adropin levels in patients with AMI and demonstrated a negative correlation between adropin levels and the presence of AMI in CAD patients. These results revealed that adropin might represent as a novel biomarker for predicting AMI onset in CAD patients. Further studies are necessary to substantiate the potential significance of adropin in predicting AMI.
Financial and competing interests disclosure The authors thank the catheterization laboratory staff of Xijing Hospital for their enthusiasm in supporting the study. The authors report no declarations of interest. SAP = stable angina pectoris, AMI = acute myocardial infarction; *P b 0.01 compared with controls, # P b 0.01 compared with SAP patients.
Conflict of interest The authors declare that they have no conflict of interest.
References [1] Pope JH, Aufderheide TP, Ruthazer R, Woolard RH, Feldman JA, Beshansky JR, et al. Missed diagnoses of acute cardiac ischemia in the emergency department. N Engl J Med 2000;342:1163–70. [2] Swap CJ, Nagurney JT. Value and limitations of chest pain history in the evaluation of patients with suspected acute coronary syndromes. JAMA 2005;294:2623–9. [3] Vasan RS. Biomarkers of cardiovascular disease: molecular basis and practical considerations. Circulation 2006;113:2335–62. [4] Kumar KG, Trevaskis JL, Lam DD, Sutton GM, Koza RA, Chouljenko VN, et al. Identification of adropin as a secreted factor linking dietary macronutrient intake with energy homeostasis and lipid metabolism. Cell Metab 2008;8:468–81. [5] Lovren F, Pan Y, Quan A, Singh KK, Shukla PC, Gupta M, et al. Adropin is a novel regulator of endothelial function. Circulation 2010;122:S185–92. [6] Kathir K, Adams MR. Endothelial dysfunction as a predictor of acute coronary syndromes. Semin Vasc Med 2003;3:355–62. [7] Wu L, Fang J, Chen L, Zhao Z, Luo Y, Lin C, et al. Low serum adropin is associated with coronary atherosclerosis in type 2 diabetic and non-diabetic patients. Clin Chem Lab Med 2014;52:751–8. [8] Thygesen K, Alpert JS, Jaffe AS, Simoons ML, Chaitman BR, White HD, et al. Third universal definition of myocardial infarction. Circulation 2012;126:2020–35. [9] Lian W, Gu X, Qin Y, Zheng X. Elevated plasma levels of adropin in heart failure patients. Intern Med 2011;50:1523–7. [10] Mattu HS, Randeva HS. Role of adipokines in cardiovascular disease. J Endocrinol 2013;216:T17–36. [11] Aydin S, Kuloglu T, Aydin S, Eren MN, Yilmaz M, Kalayci M, et al. Expression of adropin in rat brain, cerebellum, kidneys, heart, liver, and pancreas in streptozotocininduced diabetes. Mol Cell Biochem 2013;380:73–81. [12] Gozal D, Kheirandish-Gozal L, Bhattacharjee R, Molero-Ramirez H, Tan HL, Bandla HP. Circulating adropin concentrations in pediatric obstructive sleep apnea: potential relevance to endothelial function. J Pediatr 2013;163:1122–6. [13] Ignarro LJ. Nitric oxide as a unique signaling molecule in the vascular system: a historical overview. J Physiol Pharmacol 2002;53:503–14. [14] Alp NJ, Channon KM. Regulation of endothelial nitric oxide synthase by tetrahydrobiopterin in vascular disease. Arterioscler Thromb Vasc Biol 2004;24:413–20. [15] Mottillo S, Filion KB, Genest J, Joseph L, Pilote L, Poirier P, et al. The metabolic syndrome and cardiovascular risk a systematic review and meta-analysis. J Am Coll Cardiol 2010;56:1113–32. [16] Butler AA, Tam CS, Stanhope KL, Wolfe BM, Ali MR, O'Keeffe M, et al. Low circulating adropin concentrations with obesity and aging correlate with risk factors for metabolic disease and increase after gastric bypass surgery in humans. J Clin Endocrinol Metab 2012;97:3783–91. [17] Martin MW. Treatment of congestive heart failure a neuroendocrine disorder. J Small Anim Pract 2003;44:154–60.
Please cite this article as: Yu H, et al, Serum adropin levels are decreased in patients with acute myocardial infarction, Regul Pept (2014), http:// dx.doi.org/10.1016/j.regpep.2014.04.001
Contents lists available at ScienceDirect
Regulatory Peptides journal homepage: www.elsevier.com/locate/regpep
Serum adropin levels are decreased in patients with acute myocardial infarction Hou-you Yu a,1, Peng Zhao a,1, Ming-chun Wu b, Jian Liu a, Wen Yin a,⁎ a b
Department of Emergency Medicine, Xijing hospital, Fourth Military Medical University, No. 17 Changle West Road, Xi'an 710032, PR China Department of Anaesthiology, Wuhan general Hospital of Guangzhou Command, No. 627 Wuluo Road, Wuhan, 430070, PR China
a r t i c l e
i n f o
Article history: Received 22 January 2014 Received in revised form 16 March 2014 Accepted 1 April 2014 Available online xxxx Keywords: Coronary artery disease Atherosclerosis Acute myocardial infarction Biomarkers Adropin
a b s t r a c t Objective: Adropin is a recently identified bioactive protein that is important for energy homeostasis and maintaining insulin sensitivity. We sought to detect serum adropin levels in acute myocardial infarction (AMI) patients. Methods: We enrolled 138 AMI patients, 114 stable angina pectoris (SAP) patients and 75 controls. Adropin levels were measured by enzyme-linked immunosorbent assay (ELISA). Results: Serum adropin levels were significantly lower in patients with AMI compared with SAP patients or controls (P b 0.01). Multivariate logistic regression demonstrated that lower adropin was the independent predictor for the presence of AMI in coronary artery disease (CAD) patients (P b 0.01). Serum adropin levels were negatively associated with body mass index (BMI) (P b 0.01) and triglyceride levels (P b 0.05) in AMI patients. Conclusion: Decreased serum adropin levels are associated with the presence of AMI in CAD patients. These results revealed that adropin might represent as a novel biomarker for predicting AMI onset in CAD patients. © 2014 Elsevier B.V. All rights reserved.
1. Introduction Critical cardiovascular events such as acute myocardial infarction (AMI) remain the leading cause of morbidity and mortality worldwide. Accurate diagnosis of AMI improve prognosis through appropriate treatment without delay. In addition, biomarkers have increasingly emerged as important alternatives to traditional methods for rapid diagnosis and risk stratification of high-risk individuals [1–3]. Many blood-based protein biomarkers such as cardiac troponin (cTn) I or T, B-type natriuretic peptide (BNP) and high-sensitivity C-reactive protein (hs-CRP) has an established role in providing crucial diagnostic or prognostic value in the field of coronary artery disease (CAD). Adropin is a recently identified bioactive protein encoded by the energy homeostasis associated gene (Enho) that is expressed in the liver and the brain [4]. Adropin appears to participate in the maintenance of energy homeostasis and insulin response, which is closely related to the development and progression of atherogenesis [4]. Besides, a recent study found that adropin is also expressed in coronary artery endothelial cells and plays a potential endothelial protective role in mice [5]. It is well known that endothelial dysfunction is a key early event in atherogenesis and is integral in the onset of CAD and acute ⁎ Corresponding author. Tel./fax: +86 29 84775507. E-mail address: [email protected] (W. Yin). 1 These authors contribute equally to this paper and should be considered as Co-first authors.
coronary syndromes (ACS) [6]. More recently, Wu et al. [7] demonstrated that decreased serum adropin was an independent predictor of clinically relevant coronary atherosclerosis. Based on these findings, we hypothesized that adropin deficiency might be involved in the pathogenesis of AMI. However, the relationship between adropin concentrations and AMI has never been fully elucidated. Therefore, we aimed to detect serum adropin levels in AMI patients, and to investigate their correlation with AMI. 2. Patients and methods 2.1. Patients From August 2012 to June 2013, a total of 297 subjects admitted to Xijing hospital for coronary angiography owing to AMI (AMI group, n = 108), stable angina pectoris (SAP group, n = 114) or a clinical suspicion of CAD in subjects with multiple coronary risk factors but without lesions on angiography (controls group, n = 75) were recruited. AMI was defined by an increase in serum troponin I (2 × upper limit of the hospital normal range) associated symptoms of ischemia and/or characteristic ECG signs (ST segment-T wave changes, left bundle branch block or development of pathological Q waves) [8]. SAP was defined as no change in frequency, duration or intensity of symptoms more than 3 months before the admission. Patients were excluded on the basis of having peripheral artery disease, active inflammatory disease, autoimmune disorders, suspected myocarditis or pericarditis,
http://dx.doi.org/10.1016/j.regpep.2014.04.001 0167-0115/© 2014 Elsevier B.V. All rights reserved.
Please cite this article as: Yu H, et al, Serum adropin levels are decreased in patients with acute myocardial infarction, Regul Pept (2014), http:// dx.doi.org/10.1016/j.regpep.2014.04.001
2
H. Yu et al. / Regulatory Peptides xxx (2014) xxx–xxx
malignant disease, diabetes, severe heart failure and advanced renal and hepatic disease. Written informed consent was individually obtained regarding participation in this study. The study protocol was approved by the ethics committee of Xijing hospital.
3. Results
2.2. Blood chemistry measurement
3.1. Baseline clinical characteristics
Peripheral venous blood samples were drawn from the antecubital vein of all participants before the angiographic procedure. After clotting, the samples were immediately centrifuged and stored at −80 °C until analysis. All participants underwent conventional laboratory analyses, including determination of total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-c) and density lipoprotein cholesterol (HDL-c) using an autoanalyzer(Hitachi 7170, Hitachi Co., Japan). Hs-CRP levels were measured on an Olympus AU5400 Automatic Biochemical Analyzer (Olympus Co., Japan). N-terminal pro BNP (NTproBNP) and cTnT levels were detected in Siemens Immulite 1000 Immunoassay System (Siemens, Germany). Serum adropin levels were measured using a commercially available enzyme-linked immunosorbent assay (ELISA) kit (Cusabio Biotech Co, Wuhan, CN). The assay recognizes recombinant and natural human adropin. No significant cross-reactivity or interference was observed [9]. Test range was 0.32–20 ng/mL [9]. The sensitivity of the assay was 0.08 ng/mL, and inter-assay and intra-assay coefficients of variation (CV) were less than 14% and 5%, respectively [9]. All the serum samples were analyzed by ELISA in duplicate, and the results were averaged. Preliminary study demonstrated that adropin levels in serum are closely correlated with those in paired plasma samples.
The baseline characteristics of the three groups were shown in Table 1. Compared with controls, SAP patients had significantly higher diastolic blood pressure (SBP), LDL-c, hs-CRP and NT-proBNP levels. Compared with SAP patients, AMI patients had significantly higher hs-CRP levels as well as significantly lower HDL-c levels and left ventricular ejection fraction (LVEF). Besides, AMI patients were older than controls.
2.3. Statistical analysis All statistical analyses were performed using SPSS 17.0 for Windows version (SPSS Inc., Chicago, USA). The Kolmogorov–Smirnov test was used to analyze data normality results of normally distributed continuous variables are expressed as the mean value ± SD, and those for continuous variables with skewed distribution are expressed as the median value (interquartile range) and categorical variables as frequencies or percentages. Differences among the three groups were analyzed by one-way analysis of variance (ANOVA), followed by Tukey post hoc analysis or Kruskal–Wallis test as indicated. Multivariate logistic analysis was performed to determine the independent predictors of AMI in CAD patients. The correlation between serum adropin levels and other clinical characteristics in AMI patients was assessed by Pearson or
Spearman correlation coefficient when appropriate. Probability values (two-tailed) were considered significant at P b 0.05.
3.2. Serum adropin levels As shown in Fig. 1, our study demonstrated that SAP patients had significantly lower serum adropin levels compared to controls (3.81 ± 1.78 vs 5.12 ± 1.44 ng/ml, P b 0.01). In CAD patients, AMI patients had significantly lower serum adropin levels compared to SAP patients (2.19 ± 1.61 vs 3.81 ± 1.78 ng/ml, P b 0.01). 3.3. The independent predictors of AMI We perform multivariate logistic regression including all variables to assess the independent predictors of AMI in CAD patients. Our results revealed that lower serum levels of adropin was the significant and independent predictor of AMI in CAD patients (OR = 0.555, 95% CI = 0.438–0.704, P b 0.01; Table 2). 3.4. Correlations between adropin and other clinical characteristics in AMI patients As demonstrated in Table 3, serum adropin levels were negatively correlated with body mass index (BMI) (ρ = −0.252, P = 0.008) and TG levels in AMI patients (ρ = − 0.202, P = 0.036). However, serum adropin levels were neither correlated with cTnT levels (ρ = −0.161, P = 0.095) nor correlated with Creatine Kinase (CK)-MB levels (ρ = 0.045, P = 0.646). There was also no correlation between serum adropin levels with other conventional cardiovascular biomarkers such as hs-CRP (ρ = −0.101, P = 0.297) and NT-proBNP (ρ = −0.008, P = 0.936).
Table 1 Baseline clinical and laboratory characteristics. Variables
AMI (n = 108)
SAP patients (n = 114)
Controls (n = 75)
Age (years) Male, n (%) BMI SBP (mm Hg) DBP (mm Hg) TC (mmol/L) TG (mmol/L) LDL-c (mmol/L) HDL-c (mmol/L) FBG (mmol/L) hs-CRP (mg/L) NT-proBNP (ng/L) LVEF Smoking, n (%) On statins, n (%) On ACEI/ARB, n (%)
64.50 ± 10.53* 62 (57.41%) 25.07 (23.18–26.49) 131.76 ± 18.88 81.06 ± 10.95 4.62 ± 1.09* 1.77 (1.30–2.67) * 2.80 ± 0.80** 0.92 (0.75–1.17) **†† 5.64 (5.04–6.26) 1.68 (1.24–3.64) **†† 277 (220–324) ** 53.94 ± 11.40**†† 40 (37.04%) 21 (19.44%) 29 (26.85%)
63.67 ± 11.18 67 (58.77%) 25.12 (23.79–25.92) 135.60 ± 14.26 83.72 ± 11.92* 4.36 ± 1.06 1.61 (1.13–2.19) 2.67 ± 0.95* 1.03 (0.86–1.21) 5.62 (4.96–6.13) 0.88 (0.67–1.43) ** 282 (83–334) * 63.49 ± 8.93 40 (35.09%) 32 (28.07%) 33 (28.95%)
60.40 ± 9.58 39 (52.00%) 24.74 (23.29–25.94) 130.04 ± 16.00 79.42 ± 12.43 4.16 ± 1.04 1.50 (1.02–2.17) 2.32 ± 0.88 1.04 (0.86–1.26) 5.65 (5.12–6.16) 0.61 (0.34–0.96) 164 (58–313) 65.09 ± 7.34 22 (29.33%) 14 (18.67%) 26 (34.67%)
All values are presented as mean ± SD, median value (interquartile range) or n (%). AMI = acute myocardial infarction, SAP = stable angina pectoris, BMI = body mass index, SBP = systolic blood pressure, DBP = diastolic blood pressure, TC = total cholesterol, TG = triglycerides, LDL-c = low-density lipoprotein cholesterol, HDL-c = high density lipoprotein cholesterol, FBG = fasting glucose, hs-CRP = high-sensitivity C-reactive protein, NT-proBNP = N-terminal pro B-type natriuretic peptide, LVEF = left ventricular ejection fraction and ACEI/ARB = (on the use of) angiotensin converting enzyme inhibitor/angiotensin receptor blocker. *P b 0.05 compared with healthy controls, **P b 0.01 compared with controls; †P b 0.05 compared with SAP patients, ††P b 0.01 compared with SAP patients.
Please cite this article as: Yu H, et al, Serum adropin levels are decreased in patients with acute myocardial infarction, Regul Pept (2014), http:// dx.doi.org/10.1016/j.regpep.2014.04.001
H. Yu et al. / Regulatory Peptides xxx (2014) xxx–xxx
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Table 3 Correlations between adropin and other clinical characteristics in AMI patients.
Fig. 1. Serum adropin levels in AMI (n = 108), SAP (n = 114) patients and controls (n = 75).
4. Discussion In the current study, we found that serum adropin levels were significantly lower in patients with AMI compared with SAP patients or controls. Multivariate logistic regression demonstrated that adropin was the independent predictor for the presence of AMI in CAD patients. Additionally, we also found negative correlations between serum adropin levels and NT-proBNP and TG in AMI patients. To our best knowledge, this is the first study to investigate the relationship between serum adropin levels and AMI. Peptides secreted from peripheral organs as regulators in glucose and energy homeostasis has gained increasing interest. The adipocytesecreted hormones, termed adipokines, have an established role as the critical mediators of food intake, energy expenditure and metabolic disorders in obese people [10]. Recently, another important advance in this field is the identification of liver-derived hormones. Adropin is a recently described liver-secreted hormone that is important for energy homeostasis and maintaining insulin sensitivity [4]. Aydin et al. [11] demonstrated that adropin is expressed in brain, cerebellum, kidneys, heart, liver, pancreas and vascular tissues of diabetic rats. Adropin is a secreted protein that could be secreted into the circulation. Therefore, adropin is being explored as potential biomarkers of several diseases [9,12]. In the present study, we found decreased serum adropin levels in AMI patients compared with SAP patients or controls. As we have known, adropin expressed in the vascular tissues might transfer to the
Table 2 Multiple logistic regression analysis for the predictors of AMI. Variables
OR (95% CI)
P value
Age (per year) Male (yes) BMI SBP (per mm/Hg) DBP (per mmHg) TC (per mmol/L) TG (per mmol/L) LDL-c (per mmol/L) HDL-c (per mmol/L) FBG (per mmol/L) hs-CRP (per mg/L) NT-proBNP (per ng/L) LVEF Smoking (yes) On statins On ACEI/ARB adropin (per ng/ml)
1.016 (0.983–1.051) 0.719 (0.321–1.613) 0.857 (0.743–0.988) 0.985 (0.961–1.009) 0.963 (0.929–0.998) 1.367 (0.964–1.937) 1.025 (0.666–1.577) 1.258 (0.832–1.902) 0.404 (0.075–2.164) 0.817 (0.580–1.150) 1.388 (1.115–1.728) 1.000 (0.999–1.002) 1.107 (1.063–1.153) 1.446 (0.648–3.227) 1.889 (0.775–4.605) 0.791 (0.352–1.778) 0.555 (0.438–0.704)
0.335 0.424 0.034 0.224 0.040 0.079 0.910 0.277 0.290 0.247 0.003 0.435 b0.001 0.368 0.162 0.571 b0.001
OR = odds ratio, CI = confidence interval, other abbreviations are as in Table 1.
Variables
Correlation coefficient
P value
Age (year) BMI (kg/mm2) SBP (mm/Hg) DBP (mmHg) TC (mmol/L) TG (mmol/L) LDL-c (mmol/L) HDL-c (mmol/L) FBG (mmol/L) hs-CRP (mg/L) NT-proBNP (ng/L) LVEF cTnT (ng/ml) CK-MB (U/L)
−0.095 −0.252 −0.036 −0.074 −0.064 −0.202 −0.121 0.102 0.100 −0.101 −0.008 0.067 −0.161 0.045
0.326 0.008 0.709 0.450 0.508 0.036 0.212 0.294 0.291 0.297 0.936 0.478 0.095 0.646
cTnT = troponin T, CK-MB = creatine kinase-MB, other abbreviations are as in Table 1.
blood. Therefore, this result may reflect the deficiency of adropin expression in AMI patients. Further studies are needed to elucidate the reason for adropin deficiency in AMI patients. This result also revealed that adropin deficiency might play a pathological role in the development and progression of AMI. Lovren et al. [5] have demonstrated that adropin could enhance the expression of endothelial nitric oxide synthase (eNOS) in the endothelium via activation of vascular endothelial growth factor receptor (EGFR) 2 phosphatidylinositol 3-kinase Akt and EGFR 2 extracellular signal-regulated kinase 1/2 pathways. As eNOS is responsible for the production of vascular nitric oxide (NO) [13], adropin deficiency is associated with reduced nitric oxide bioavailability in the endothelium. Loss of NO bioavailability is a cardinal feature of endothelial dysfunction that precedes the development of overt atherosclerosis and is an independent predictor of the development of AMI [14]. Besides, the reduced circulating adropin concentrations has an important correlate of metabolic disorders associated with insulin resistance and obesity, which are related to the progression of coronary atherosclerosis and increased incidence of cardiovascular events such as AMI [4,15]. We performed multivariate logistic regression to identify independent predictors for AMI in CAD patients. The results revealed that lower serum adropin levels were independently associated with the presence of AMI in CAD patients. These results indicated that adropin appears to be a potential serum biomarker for early diagnosis of AMI in CAD patients. In addition, serum adropin levels did not show any correlation with cTnT or CK-MB in AMI patients, suggesting that adropin is not a marker for cardiac necrosis or injury. More recently, Wu et al. found that CAD patients had lower serum adropin levels compared with Non-CAD patients, and lower serum adropin was associated with greater angiographic severity of coronary atherosclerosis in both type 2 diabetic and non-diabetic patients [7]. These findings are in accordance with our results and suggested that adropin deficiency may be involved in promotion of coronary atherosclerosis and AMI. We have also investigated the relationship between adropin and other clinical characteristics in AMI patients. We have showed that serum adropin levels were negatively associated with BMI and TG levels. These results are in accordance with a previous study by Bulter et al., which demonstrated that adropin levels correlated negatively with BMI and TG in metabolic syndrome patients after gastric bypass surgery [16]. These results may be partly explained by the biological effects of adropin on increasing energy expenditure and inhibiting lipogenesis. However, Lian et al. showed that plasma adropin levels were correlated positively with BMI and the severity of heart failure in patients with heart failure, which is in contrary to our results [9]. Heart failure, which has a close relationship with obesity, is now seen as a complex pathophysiological process with activation of various neuro-endocrine systems [17].The different biochemical and neuroendocrine alterations between CAD and heart failure patients might
Please cite this article as: Yu H, et al, Serum adropin levels are decreased in patients with acute myocardial infarction, Regul Pept (2014), http:// dx.doi.org/10.1016/j.regpep.2014.04.001
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H. Yu et al. / Regulatory Peptides xxx (2014) xxx–xxx
partly explain the opposite results mentioned above. However, the relationship between adropin and cardiac remodeling remain to be further investigated. The limitations of this study should be considered when interpreting our results. First, the present study is a cross-sectional study with relatively small sample size; such a study cannot establish causality. Therefore, our results should be verified in multi-center prospective longitudinal studies with larger sample size. Second, we only enrolled patients referred for the interventional diagnosis and treatment of CAD, which might induce some bias. Third, adropin is mainly expressed and produced in liver and brain. We did not evaluate the function of these relevant organs, which might contribute as potential confounders in the analysis of serum adropin levels. In conclusion, this study reported decreased serum adropin levels in patients with AMI and demonstrated a negative correlation between adropin levels and the presence of AMI in CAD patients. These results revealed that adropin might represent as a novel biomarker for predicting AMI onset in CAD patients. Further studies are necessary to substantiate the potential significance of adropin in predicting AMI.
Financial and competing interests disclosure The authors thank the catheterization laboratory staff of Xijing Hospital for their enthusiasm in supporting the study. The authors report no declarations of interest. SAP = stable angina pectoris, AMI = acute myocardial infarction; *P b 0.01 compared with controls, # P b 0.01 compared with SAP patients.
Conflict of interest The authors declare that they have no conflict of interest.
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