- Email: [email protected]
Usefulness of soluble urokinase plasminogen activator receptor (suPAR) as an inflammatory biomarker in obese children
International Journal of Cardiology 228 (2017) 158–161
Contents lists available at ScienceDirect
International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard
Usefulness of soluble urokinase plasminogen activator receptor (suPAR) as an inflammatory biomarker in obese children Mustafa Kosecik a,⁎, Pinar Dervisoglu a, Mehmet Koroglu b, Pinar Isguven c, Bahri Elmas d, Tayfur Demiray b, Mustafa Altindis b a
Department of Pediatric Cardiology, School of Medicine, Sakarya University, Sakarya, Turkey Department of Medical Microbiology, School of Medicine, Sakarya University, Sakarya, Turkey Department of Pediatric Endocrinology, School of Medicine, Sakarya University, Sakarya, Turkey d Department of Pediatrics, School of Medicine, Sakarya University, Sakarya, Turkey b c
a r t i c l e
i n f o
Article history: Received 1 September 2016 Accepted 6 November 2016 Available online 09 November 2016 Keywords: Children Obesity Inflammation Biomarkers suPAR
a b s t r a c t Objective: Soluble urokinase plasminogen activator receptor (suPAR) has emerged as a relatively new biomarker that reflects increased inflammatory status and been associated with cardiovascular risk. We wanted to investigate the predictive value and usefulness of suPAR as an inflammatory biomarker in obese children. Methods and results: Of the total 136 participants, 76 (36 male, 40 female) were in obese group and 60 (24 male, 36 female) were in control group. The median age was 12.05 (6.16–17.30) years old for obese group, and 12.83 (8.00–16.75) years old for control group. Obese children had statistically significantly higher heart rate, systolic and diastolic blood pressure, EAT and LV mass than control group (p b 0.01). The median suPAR level in obese group was not statistically different than in control group (0.54 vs. 0.59, p = 0.26). The median hsCRP level in obese group was found statistically significantly higher than in control group (1.97 vs. 0.41, p b 0.01). A significant positive correlation between hsCRP and BMI in the obese participants was found (r = 0.45, p b 0.01), but not a relationship between suPAR and BMI (r = −0.21, p N 0.05). Conclusion: Our research did not demonstrate the usefulness of suPAR as an inflammatory biomarker and a predictive value for future atherosclerosis in obese children. Further studies with larger sample size are required to determine whether suPAR is useful as an inflammatory biomarker in childhood obesity. © 2016 Elsevier Ireland Ltd. All rights reserved.
1. Introduction The prevalence of obesity in children is dramatically increasing even in developing countries [1]. Obesity in children has a wide range of severe potential complications and increases the hazard of mortality and early disorders including hypertension, dyslipidemia, impaired glucose tolerance, diabetes mellitus and metabolic syndrome in later life, and childhood obesity is considered as an independent cardiovascular risk factor that contributes to the development of atherosclerosis [2,3]. Development of atherosclerosis is known to be a chronic, multifactorial, polygenic and very complex process resulting from endothelial dysfunction and excessive inflammatory response to various forms of injurious stimuli to the arterial wall [4,5]. Several studies have evaluated the relationship between some inflammatory biomarkers such as high sensitivity C-reactive protein (hsCRP) and obesity in childhood [6–8].
⁎ Corresponding author. E-mail address: [email protected] (M. Kosecik).
http://dx.doi.org/10.1016/j.ijcard.2016.11.201 0167-5273/© 2016 Elsevier Ireland Ltd. All rights reserved.
Soluble urokinase plasminogen activator receptor (suPAR) has emerged as a relatively new biomarker that reflects increased inflammatory status, and it is positively correlated with other inflammatory biomarkers [9]. suPAR is associated with endothelial dysfunction and atherosclerosis, and released through the cleavage of urokinase plasminogen activator receptor (uPAR), which is found in different cells such as endothelial cells, macrophages, monocytes and T-lymphocytes [10]. Recent studies reported the relationships between increased plasma suPAR levels and pneumonia, sepsis, and glomerulonephritis in pediatric population [11–13]. It is of uttermost importance to identify these early activity markers in order to prevent from the disease progression because of the atherosclerosis associated with inflammatory changes from early stages. Until today, many inflammatory predictive biomarkers were determined such as hsCRP [6–8]. However, to our knowledge, there was not any study investigating suPAR as a predictive inflammatory biomarker in children with obesity in the literature. The purpose of this study was to investigate the predictive value and usefulness of suPAR as an inflammatory biomarker for obese children.
M. Kosecik et al. / International Journal of Cardiology 228 (2017) 158–161 2. Materials and methods 2.1. Study design, participants and blood samples This study was performed on children admitted to outpatient clinics of pediatric endocrinology and pediatric cardiology of Sakarya University, Research and Training Hospital. The study protocol was approved by Sakarya University Local Ethical Committee, and fully informed consents were obtained from the parents of all children. Body weight and height measurements were performed using the same tool. The body mass index (BMI) levels were calculated as weight (kg) divided by height (m) squared. The BMI reference curves established by Bundak et al. [14] for Turkish children were used for determination of corpulence. As defined by the International Obesity Task Force (IOTF), children with a BMI above 95th percentiles were considered as obese, according to the age and sex [15]. Children who had obesity originating from secondary and genetic causes were excluded from the study. Age and gender matched children admitted to outpatient clinic of pediatric cardiology with chest pain or murmur, and in whom pathology was not defined and BMI was within the normal range, were taken into the control group. All control cases were healthy. All children included in the study were non-smoker without any regular medication and no family history of premature cardiovascular diseases. None of the children had symptoms of infection for two weeks before the study. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured twice at the right arm after a 10-min rest in the supine position using the same sphygmomanometer in all participants in this study. All ultrasound studies were performed using a Philips iE33 ultrasound machine with 3 MHz phase transducer. Examinations were performed in the left lateral position on standard parasternal long axis and apical four chamber views. Two-dimensional targeted M-mode echocardiographic tracings were obtained in the parasternal long axis. Left ventricular (LV) mass was calculated by device as automatic using the current standardized formula [16]. Epicardial adipose tissue (EAT) was measured by two-dimensional echocardiography as an echo-free space over the pericardial layers and its thickness was measured on the free wall of the right ventricle, perpendicular to the wall, from parasternal long axis view at end-diastole [17]. The measurements were performed by the same pediatric cardiology specialist. Peripheral venous blood samples were obtained using EDTA-containing blood collector tubes for suPAR and plasma samples through centrifugation. Serum samples were collected for high-sensitivity CRP (hsCRP). Plasma and serum samples were stored at −80 °C in a deep freezer until suPAR and high-sensitivity CRP (hsCRP) assays were performed. 2.2. Detection of suPAR and hsCRP levels The suPAR levels were measured using the suPARnostic® assay (ViroGates®, Birkerød, Denmark) according to the manufacturer's instructions. The ELISA procedure is a double monoclonal antibody sandwich assay. Anti-suPAR precoated microwells were used to mix samples and peroxidase-conjugated anti-suPAR to detect suPAR levels. The suPAR standards were used to prepare a calibration curve and suPAR levels in patient samples were calculated by interpolation. Plasma samples were measured in duplicates. Curve control range was given as 3.0 ng/mL (2.3–3.8 ng/mL) within the kit and we determined the level as 2.99 ng/mL. The kit standard curve was validated to measure suPAR levels between 0.8 and 16.8 ng/mL with a detection limit (LLOD) of 0.1 ng/mL. Serum hsCRP concentration was determined using the Siemens CardioPhase hsCRP (Siemens Healthcare Diagnostics Products GmbH, Marburg, Germany) particleenhanced immune-nephelometric assay on the BN IIanalyzer (Siemens Healthcare Diagnostics Products GmbH, Marburg, Germany). Expected hsCRP levels in healthy individuals were lower than 3.0 mg/L. 2.3. Statistical analysis
159
Table 1 Demographic, clinic, laboratory and echocardiographic data of obese and control groups.
Age (year) Height (cm) Weight (kg) BMI (kg/m2) HR (beat/min) SBP (mmHg) DBP (mmHg) hsCRP (mg/L) suPAR (ng/mL) EAT (mm) LV mass (go)
Obese (n = 76)
Control (n = 60)
p
12.05 (6.16–17.30)⁎ 151.30 (108–178) 64.70 (30.30–129.80) 28.43 (24.38–48.85) 84 (60–110) 125 (100–140) 77.50 (60–95) 1.97 (0.10–15.50) 0.54 (0.00–5.14) 5.10 (3.90–5.70) 112.50 (84.0–230.0)
12.83 (8.00–16.75) 158.00 (115–194) 49.0 (18.0–85.0) 19.54 (13.61–24.21) 80 (69–94) 110 (90–130) 70 (60–85) 0.41 (0.16–7.67) 0.59 (0.22–2.11) 4.80 (5.20–5.20) 94.20 (49.0–150.0)
NS b0.01 b0.01 b0.01 b0.01 b0.01 b0.01 b0.01 =0.26 b0.01 b0.01
BMI: body mass index, HR: heart rate, SBP: systolic blood pressure, DBP: diastolic blood pressure, EAT: epicardial adipose tissue, LV: left ventricular. ⁎ Median (minimum-maximum) value.
hsCRP level in obese group was found statistically significantly higher than in control group (1.97 vs. 0.41, p b 0.01) (Fig. 2). In the obese participants, we found a significant correlation between hsCRP and BMI (r = 0.45, p b 0.01), but a correlation between suPAR and BMI was not found (r = −0.21, p N 0.05). There was a significant correlation between LV mass and BMI (r = 0.25, p b 0.05), but there was not a correlation between EAT and BMI (r = 0.14, p N 0.05). 4. Discussion Obesity in childhood and adolescence is an important public health problem, and its prevalence is approximately 17% in the United States [18]. Childhood obesity is a strong predictor of adulthood obesity, and obese children and adolescents often become obese adults [19]. As in adulthood, obesity in childhood and adolescence is also associated with cardiovascular risk factors leading to early atherosclerosis. Many previous studies demonstrated the relationship of childhood obesity with endothelial dysfunction, inflammation, atherosclerosis, and high cardiovascular risk profile [20–22]. It was indicated that the inflammatory mechanisms have a key role in initiating, advancing and destabilizing of atherosclerotic lesions [4]. Several inflammatory biomarkers were studied in order to determine whether the predictive value in obese children and adolescences, and the most studied inflammatory biomarker is hsCRP for this purpose. The association between hsCRP and childhood obesity and overweight was shown to be wellestablished in the literature [6–8,23,24]. suPAR has gained interest as a novel indicator of low-grade inflammation in recent years. The physiologic function of suPAR is not as well understood, but suPAR levels correlate with other inflammatory
All statistical analyses were conducted out using the Statistical Package for Social Sciences (SPSS) package program (version 21.0, SPSS® Inc., Chicago, IL, USA). Distribution of parametric variables was assessed with one-sample Kolmogorov-Smirnov test. Parametric variables were not distributed normally. Continuous variables were compared with the Mann–Whitney U test for two groups. Correlation analysis of the data obtained from cases in the obese group was calculated using Pearson correlation test. The results were given as median (minimum-maximum) values. For all analyses, the p value b0.05 was considered statistically significant.
3. Results Of the total 136 participants included in the study, 76 (36 male, 40 female) were in obese group and 60 (24 male, 36 female) were in control group. The median age was 12.05 (6.16–17.30) years old for obese group, and 12.83 (8.00–16.75) years old for control group. The median BMI was statistically significantly higher in obese group [28.43 (24.38– 48.85) kg/m2] than in control group [19.54 (13.61–24.21) kg/m2]. Obese children had statistically significantly higher heart rate (HR), systolic and diastolic blood pressure, EAT and LV mass than control group (Table 1). The median suPAR level in obese group was not statistically different than in control group (0.54 vs. 0.59, p = 0.26) (Fig. 1). The median
Fig. 1. Changes in suPAR levels according to groups.
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M. Kosecik et al. / International Journal of Cardiology 228 (2017) 158–161
In conclusion, it was found that suPAR was not associated with obesity, whereas hsCRP was associated with obesity in children. Therefore, our research did not demonstrate the usefulness of suPAR as an inflammatory biomarker and does not possess a predictive value for future atherosclerosis in obese children. Further studies with larger sample size are required to determine whether suPAR is useful as a biomarker in childhood obesity. Long-term prospective studies are needed to demonstrate the predictive value of such inflammatory biomarkers.
Conflicts of interest There are no conflicts of interest.
Acknowledgments
Fig. 2. Changes in hsCRP levels according to groups.
biomarkers such as tumor necrosis factor. It was shown that suPAR is related to endothelial dysfunction, neointimal formation of atherosclerotic lesions and plaque destabilization. However, whether suPAR has a causal role in development of cardiovascular disorders or only reflects the disorder process is also unknown. suPAR is also related to the development, severity and prognosis of several diseases including coronary artery disease, diabetes mellitus, stroke, cancer, infectious diseases and sepsis in adult population [25,26]. In pediatric population, the studies with regard to suPAR are less than adult studies, and have particularly focused to various types of renal and infectious diseases [11–13]. Information with regard to the association between suPAR and childhood obesity is absent in the current literature. Therefore, we designed this study in order to determine whether suPAR is useful as a biological marker in obese children and adolescents. In this present study, we found that the median suPAR level was lower in obese group compared with control group, but this difference was not statistically significant (0.54 vs. 0.59, p = 0.26). The median hsCRP level was higher in obese group along with a statistically significant difference (1.97 vs. 0.41, p b 0.01). Therefore, it was deduced that suPAR levels were not associated with obesity, whereas hsCRP levels were found to be associated with obesity in children. Similar to the results of our study, Lyngbæk et al. [27] reported in their study with large number of participants that suPAR levels were not associated with cardiovascular risk factors like overweight and abdominal obesity (measured as body mass index and waist circumference) as opposed to CRP in adult study population. The authors indicated that suPAR was linked to endothelial dysfunction and existence of atherosclerotic plaques thus potentially representing later occurring processes in the development of cardiovascular diseases. Similarly, Botha et al. [28] also reported that suPAR was not associated with cardiometabolic factors like measures of adiposity in adult black South African population. The precise pathophysiological mechanisms of subclinical inflammation in obese children and adolescents are still unclear. There are just a few studies with small sample size on childhood obesity, which characterize the subclinical inflammation in these youth ages. However, these studies could not entirely explain the features and clinical significance of the subclinical inflammation [29]. To our best knowledge, this case–control study is the first study investigating the relationship between suPAR and childhood obesity in the literature. However, there were several limitations in the interpretation of the results of our study. The major limitations of this present study were the relatively small number of participants and not normally distribution of parametric variables in the study groups and evaluated data were limited. A larger sample could have increased the statistical power of our research.
This work was supported by Sakarya University through its institutional facilities.
References [1] R. Kelishadi, Childhood overweight, obesity, and the metabolic syndrome in developing countries, Epidemiol. Rev. 29 (2007) 62–76. [2] J.C. Han, D.A. Lawlor, S.Y. Kimm, Childhood obesity, Lancet 375 (2010) 1737–1748. [3] D.S. Freedman, W.H. Dietz, S.R. Srinivasan, G.S. Berenson, Risk factors and adult body mass index among overweight children: the Bogalusa Heart Study, Pediatrics 123 (2009) 750–757. [4] I. Manduteanu, M. Simionescu, Inflammation in atherosclerosis: a cause or a result of vascular disorders? J. Cell. Mol. Med. 16 (2012) 1978–1990. [5] M.U. Es, S. Senol, A. Yuksel, K. Kargun, Endothelin-1 gene polymorphisms in patients with peripheral artery disease, Acta Med. Mediterr. 32 (2016) 897–901. [6] S. Semiz, S. Rota, O. Ozdemir, A. Ozdemir, B. Kaptanoğlu, Are C-reactive protein and homocysteine cardiovascular risk factors in obese children and adolescents? Pediatr. Int. 50 (2008) 419–423. [7] K. Kitsios, M. Papadopoulou, K. Kosta, N. Kadoglou, M. Papagianni, K. Tsiroukidou, Highsensitivity C-reactive protein levels and metabolic disorders in obese and overweight children and adolescents, J. Clin. Res. Pediatr. Endocrinol. 5 (2013) 44–49. [8] D. Dayal, H. Jain, S.V. Attri, B. Bharti, A.K. Bhalla, Relationship of high sensitivity Creactive protein levels to anthropometric and other metabolic parameters in Indian children with simple overweight and obesity, J. Clin. Diagn. Res. 8 (2014) 5–8. [9] M. Persson, G. Engström, H. Björkbacka, B. Hedblad, Soluble urokinase plasminogen activator receptor in plasma is associated with incidence of CVD. Results from the Malmö Diet and Cancer Study, Atherosclerosis 220 (2012) 502–505. [10] A. Edsfeldt, M. Nitulescu, H. Grufman, et al., Soluble urokinase plasminogen activator receptor is associated with inflammation in the vulnerable human atherosclerotic plaque, Stroke 43 (2012) 3305–3312. [11] A. Wrotek, T. Jackowska, The role of the soluble urokinase plasminogen activator (suPAR) in children with pneumonia, Respir. Physiol. Neurobiol. 209 (2015) 120–123. [12] M.S. El-Mekkawy, N.Y. Saleh, A.A. Sonbol, Soluble urokinase plasminogen activator receptor: a new biomarker in the pediatric intensive care unit, Indian J. Pediatr. 83 (2016) 661–669. [13] J. Soltysiak, J. Zachwieja, A. Benedyk, M. Lewandowska-Stachowiak, M. Nowicki, D. Ostalska-Nowicka, Circulating suPAR as a biomarker of disease severity in children with proteinuric glomerulonephritis, Minerva Pediatr. (2016 Apr 12) (Epub ahead of print). [14] R. Bundak, A. Furman, H. Gunoz, F. Darendeliler, F. Bas, O. Neyzi, Body mass index references for Turkish children, Acta Paediatr. 95 (2006) 194–198. [15] T.J. Cole, M.C. Bellizzi, K.M. Flegal, W.H. Dietz, Establishing a standard definition for child overweight and obesity worldwide: international survey, BMJ 320 (2000) 1240–1243. [16] N.B. Schiller, P.M. Shah, M. Crawford, et al., Recommendations for quantitation of the left ventricle by two-dimensional echocardiography. American Society of Echocardiography Committee on standards, subcommittee on quantitation of two-dimensional echocardiograms, J. Am. Soc. Echocardiogr. 2 (1989) 358–367. [17] G. Iacobellis, M.C. Ribaudo, A. Zappaterreno, C.V. Iannucci, F. Leonetti, Relation between epicardial adipose tissue and left ventricular mass, Am. J. Cardiol. 94 (2004) 1084–1087. [18] C.L. Ogden, M.D. Carroll, H.G. Lawman, et al., Trends in obesity prevalence among children and adolescents in the United States, 1988–1994 through 2013–2014, JAMA 315 (2016) 2292–2299. [19] S.S. Guo, W. Wu, W.C. Chumlea, A.F. Roche, Predicting overweight and obesity in adulthood from body mass index values in childhood and adolescence, Am. J. Clin. Nutr. 76 (2002) 653–658. [20] O. Elkiran, E. Yilmaz, M. Koc, A. Kamanli, B. Ustundag, N. Ilhan, The association between intima media thickness, central obesity and diastolic blood pressure in obese and overweight children: a cross-sectional school-based study, Int. J. Cardiol. 165 (2013) 528–532. [21] R. Schiel, W. Beltschikow, G. Kramer, G. Stein, Overweight, obesity and elevated blood pressure in children and adolescents, Eur. J. Med. Res. 11 (2006) 97–101.
M. Kosecik et al. / International Journal of Cardiology 228 (2017) 158–161 [22] P. Tounian, Y. Aggoun, B. Dubern, et al., Presence of increased stiffness of the common carotid artery and endothelial dysfunction in severely obese children: a prospective study, Lancet 358 (2001) 1400–1404. [23] E.J. Roh, J.W. Lim, K.O. Ko, E.J. Cheon, A useful predictor of early atherosclerosis in obese children: serum high-sensitivity C-reactive protein, J. Korean Med. Sci. 22 (2007) 192–197. [24] R.P. Namburi, A.R. Ponnala, T.S. Karthik, P. Radha Rani, R. Maheshwari, A study on metabolic variables and its association with high sensitive C-reactive protein in obese children and adolescent, Indian J. Endocrinol. Metab. 17 (Suppl. 1) (2013) 360–362. [25] G.W. Hodges, C.N. Bang, K. Wachtell, J. Eugen-Olsen, J.L. Jeppesen, suPAR: a new biomarker for cardiovascular disease? Can. J. Cardiol. 31 (2015) 1293–1302.
161
[26] N.B. Cyrille, P.A. Villablanca, H. Ramakrishna, Soluble urokinase plasminogen activation receptor–an emerging new biomarker of cardiovascular disease and critical illness, Ann. Card. Anaesth. 19 (2016) 214–216. [27] S. Lyngbæk, T. Sehestedt, J.L. Marott, et al., CRP and suPAR are differently related to anthropometry and subclinical organ damage, Int. J. Cardiol. 167 (2013) 781–785. [28] S. Botha, C.M. Fourie, R. Schutte, A. Kruger, A.E. Schutte, Associations of suPAR with lifestyle and cardiometabolic risk factors, Eur. J. Clin. Investig. 44 (2014) 619–626. [29] C.S. Tam, K. Clément, L.A. Baur, J. Tordjman, Obesity and low-grade inflammation: a pediatric perspective, Obes. Rev. 11 (2010) 118–126.
Contents lists available at ScienceDirect
International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard
Usefulness of soluble urokinase plasminogen activator receptor (suPAR) as an inflammatory biomarker in obese children Mustafa Kosecik a,⁎, Pinar Dervisoglu a, Mehmet Koroglu b, Pinar Isguven c, Bahri Elmas d, Tayfur Demiray b, Mustafa Altindis b a
Department of Pediatric Cardiology, School of Medicine, Sakarya University, Sakarya, Turkey Department of Medical Microbiology, School of Medicine, Sakarya University, Sakarya, Turkey Department of Pediatric Endocrinology, School of Medicine, Sakarya University, Sakarya, Turkey d Department of Pediatrics, School of Medicine, Sakarya University, Sakarya, Turkey b c
a r t i c l e
i n f o
Article history: Received 1 September 2016 Accepted 6 November 2016 Available online 09 November 2016 Keywords: Children Obesity Inflammation Biomarkers suPAR
a b s t r a c t Objective: Soluble urokinase plasminogen activator receptor (suPAR) has emerged as a relatively new biomarker that reflects increased inflammatory status and been associated with cardiovascular risk. We wanted to investigate the predictive value and usefulness of suPAR as an inflammatory biomarker in obese children. Methods and results: Of the total 136 participants, 76 (36 male, 40 female) were in obese group and 60 (24 male, 36 female) were in control group. The median age was 12.05 (6.16–17.30) years old for obese group, and 12.83 (8.00–16.75) years old for control group. Obese children had statistically significantly higher heart rate, systolic and diastolic blood pressure, EAT and LV mass than control group (p b 0.01). The median suPAR level in obese group was not statistically different than in control group (0.54 vs. 0.59, p = 0.26). The median hsCRP level in obese group was found statistically significantly higher than in control group (1.97 vs. 0.41, p b 0.01). A significant positive correlation between hsCRP and BMI in the obese participants was found (r = 0.45, p b 0.01), but not a relationship between suPAR and BMI (r = −0.21, p N 0.05). Conclusion: Our research did not demonstrate the usefulness of suPAR as an inflammatory biomarker and a predictive value for future atherosclerosis in obese children. Further studies with larger sample size are required to determine whether suPAR is useful as an inflammatory biomarker in childhood obesity. © 2016 Elsevier Ireland Ltd. All rights reserved.
1. Introduction The prevalence of obesity in children is dramatically increasing even in developing countries [1]. Obesity in children has a wide range of severe potential complications and increases the hazard of mortality and early disorders including hypertension, dyslipidemia, impaired glucose tolerance, diabetes mellitus and metabolic syndrome in later life, and childhood obesity is considered as an independent cardiovascular risk factor that contributes to the development of atherosclerosis [2,3]. Development of atherosclerosis is known to be a chronic, multifactorial, polygenic and very complex process resulting from endothelial dysfunction and excessive inflammatory response to various forms of injurious stimuli to the arterial wall [4,5]. Several studies have evaluated the relationship between some inflammatory biomarkers such as high sensitivity C-reactive protein (hsCRP) and obesity in childhood [6–8].
⁎ Corresponding author. E-mail address: [email protected] (M. Kosecik).
http://dx.doi.org/10.1016/j.ijcard.2016.11.201 0167-5273/© 2016 Elsevier Ireland Ltd. All rights reserved.
Soluble urokinase plasminogen activator receptor (suPAR) has emerged as a relatively new biomarker that reflects increased inflammatory status, and it is positively correlated with other inflammatory biomarkers [9]. suPAR is associated with endothelial dysfunction and atherosclerosis, and released through the cleavage of urokinase plasminogen activator receptor (uPAR), which is found in different cells such as endothelial cells, macrophages, monocytes and T-lymphocytes [10]. Recent studies reported the relationships between increased plasma suPAR levels and pneumonia, sepsis, and glomerulonephritis in pediatric population [11–13]. It is of uttermost importance to identify these early activity markers in order to prevent from the disease progression because of the atherosclerosis associated with inflammatory changes from early stages. Until today, many inflammatory predictive biomarkers were determined such as hsCRP [6–8]. However, to our knowledge, there was not any study investigating suPAR as a predictive inflammatory biomarker in children with obesity in the literature. The purpose of this study was to investigate the predictive value and usefulness of suPAR as an inflammatory biomarker for obese children.
M. Kosecik et al. / International Journal of Cardiology 228 (2017) 158–161 2. Materials and methods 2.1. Study design, participants and blood samples This study was performed on children admitted to outpatient clinics of pediatric endocrinology and pediatric cardiology of Sakarya University, Research and Training Hospital. The study protocol was approved by Sakarya University Local Ethical Committee, and fully informed consents were obtained from the parents of all children. Body weight and height measurements were performed using the same tool. The body mass index (BMI) levels were calculated as weight (kg) divided by height (m) squared. The BMI reference curves established by Bundak et al. [14] for Turkish children were used for determination of corpulence. As defined by the International Obesity Task Force (IOTF), children with a BMI above 95th percentiles were considered as obese, according to the age and sex [15]. Children who had obesity originating from secondary and genetic causes were excluded from the study. Age and gender matched children admitted to outpatient clinic of pediatric cardiology with chest pain or murmur, and in whom pathology was not defined and BMI was within the normal range, were taken into the control group. All control cases were healthy. All children included in the study were non-smoker without any regular medication and no family history of premature cardiovascular diseases. None of the children had symptoms of infection for two weeks before the study. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured twice at the right arm after a 10-min rest in the supine position using the same sphygmomanometer in all participants in this study. All ultrasound studies were performed using a Philips iE33 ultrasound machine with 3 MHz phase transducer. Examinations were performed in the left lateral position on standard parasternal long axis and apical four chamber views. Two-dimensional targeted M-mode echocardiographic tracings were obtained in the parasternal long axis. Left ventricular (LV) mass was calculated by device as automatic using the current standardized formula [16]. Epicardial adipose tissue (EAT) was measured by two-dimensional echocardiography as an echo-free space over the pericardial layers and its thickness was measured on the free wall of the right ventricle, perpendicular to the wall, from parasternal long axis view at end-diastole [17]. The measurements were performed by the same pediatric cardiology specialist. Peripheral venous blood samples were obtained using EDTA-containing blood collector tubes for suPAR and plasma samples through centrifugation. Serum samples were collected for high-sensitivity CRP (hsCRP). Plasma and serum samples were stored at −80 °C in a deep freezer until suPAR and high-sensitivity CRP (hsCRP) assays were performed. 2.2. Detection of suPAR and hsCRP levels The suPAR levels were measured using the suPARnostic® assay (ViroGates®, Birkerød, Denmark) according to the manufacturer's instructions. The ELISA procedure is a double monoclonal antibody sandwich assay. Anti-suPAR precoated microwells were used to mix samples and peroxidase-conjugated anti-suPAR to detect suPAR levels. The suPAR standards were used to prepare a calibration curve and suPAR levels in patient samples were calculated by interpolation. Plasma samples were measured in duplicates. Curve control range was given as 3.0 ng/mL (2.3–3.8 ng/mL) within the kit and we determined the level as 2.99 ng/mL. The kit standard curve was validated to measure suPAR levels between 0.8 and 16.8 ng/mL with a detection limit (LLOD) of 0.1 ng/mL. Serum hsCRP concentration was determined using the Siemens CardioPhase hsCRP (Siemens Healthcare Diagnostics Products GmbH, Marburg, Germany) particleenhanced immune-nephelometric assay on the BN IIanalyzer (Siemens Healthcare Diagnostics Products GmbH, Marburg, Germany). Expected hsCRP levels in healthy individuals were lower than 3.0 mg/L. 2.3. Statistical analysis
159
Table 1 Demographic, clinic, laboratory and echocardiographic data of obese and control groups.
Age (year) Height (cm) Weight (kg) BMI (kg/m2) HR (beat/min) SBP (mmHg) DBP (mmHg) hsCRP (mg/L) suPAR (ng/mL) EAT (mm) LV mass (go)
Obese (n = 76)
Control (n = 60)
p
12.05 (6.16–17.30)⁎ 151.30 (108–178) 64.70 (30.30–129.80) 28.43 (24.38–48.85) 84 (60–110) 125 (100–140) 77.50 (60–95) 1.97 (0.10–15.50) 0.54 (0.00–5.14) 5.10 (3.90–5.70) 112.50 (84.0–230.0)
12.83 (8.00–16.75) 158.00 (115–194) 49.0 (18.0–85.0) 19.54 (13.61–24.21) 80 (69–94) 110 (90–130) 70 (60–85) 0.41 (0.16–7.67) 0.59 (0.22–2.11) 4.80 (5.20–5.20) 94.20 (49.0–150.0)
NS b0.01 b0.01 b0.01 b0.01 b0.01 b0.01 b0.01 =0.26 b0.01 b0.01
BMI: body mass index, HR: heart rate, SBP: systolic blood pressure, DBP: diastolic blood pressure, EAT: epicardial adipose tissue, LV: left ventricular. ⁎ Median (minimum-maximum) value.
hsCRP level in obese group was found statistically significantly higher than in control group (1.97 vs. 0.41, p b 0.01) (Fig. 2). In the obese participants, we found a significant correlation between hsCRP and BMI (r = 0.45, p b 0.01), but a correlation between suPAR and BMI was not found (r = −0.21, p N 0.05). There was a significant correlation between LV mass and BMI (r = 0.25, p b 0.05), but there was not a correlation between EAT and BMI (r = 0.14, p N 0.05). 4. Discussion Obesity in childhood and adolescence is an important public health problem, and its prevalence is approximately 17% in the United States [18]. Childhood obesity is a strong predictor of adulthood obesity, and obese children and adolescents often become obese adults [19]. As in adulthood, obesity in childhood and adolescence is also associated with cardiovascular risk factors leading to early atherosclerosis. Many previous studies demonstrated the relationship of childhood obesity with endothelial dysfunction, inflammation, atherosclerosis, and high cardiovascular risk profile [20–22]. It was indicated that the inflammatory mechanisms have a key role in initiating, advancing and destabilizing of atherosclerotic lesions [4]. Several inflammatory biomarkers were studied in order to determine whether the predictive value in obese children and adolescences, and the most studied inflammatory biomarker is hsCRP for this purpose. The association between hsCRP and childhood obesity and overweight was shown to be wellestablished in the literature [6–8,23,24]. suPAR has gained interest as a novel indicator of low-grade inflammation in recent years. The physiologic function of suPAR is not as well understood, but suPAR levels correlate with other inflammatory
All statistical analyses were conducted out using the Statistical Package for Social Sciences (SPSS) package program (version 21.0, SPSS® Inc., Chicago, IL, USA). Distribution of parametric variables was assessed with one-sample Kolmogorov-Smirnov test. Parametric variables were not distributed normally. Continuous variables were compared with the Mann–Whitney U test for two groups. Correlation analysis of the data obtained from cases in the obese group was calculated using Pearson correlation test. The results were given as median (minimum-maximum) values. For all analyses, the p value b0.05 was considered statistically significant.
3. Results Of the total 136 participants included in the study, 76 (36 male, 40 female) were in obese group and 60 (24 male, 36 female) were in control group. The median age was 12.05 (6.16–17.30) years old for obese group, and 12.83 (8.00–16.75) years old for control group. The median BMI was statistically significantly higher in obese group [28.43 (24.38– 48.85) kg/m2] than in control group [19.54 (13.61–24.21) kg/m2]. Obese children had statistically significantly higher heart rate (HR), systolic and diastolic blood pressure, EAT and LV mass than control group (Table 1). The median suPAR level in obese group was not statistically different than in control group (0.54 vs. 0.59, p = 0.26) (Fig. 1). The median
Fig. 1. Changes in suPAR levels according to groups.
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In conclusion, it was found that suPAR was not associated with obesity, whereas hsCRP was associated with obesity in children. Therefore, our research did not demonstrate the usefulness of suPAR as an inflammatory biomarker and does not possess a predictive value for future atherosclerosis in obese children. Further studies with larger sample size are required to determine whether suPAR is useful as a biomarker in childhood obesity. Long-term prospective studies are needed to demonstrate the predictive value of such inflammatory biomarkers.
Conflicts of interest There are no conflicts of interest.
Acknowledgments
Fig. 2. Changes in hsCRP levels according to groups.
biomarkers such as tumor necrosis factor. It was shown that suPAR is related to endothelial dysfunction, neointimal formation of atherosclerotic lesions and plaque destabilization. However, whether suPAR has a causal role in development of cardiovascular disorders or only reflects the disorder process is also unknown. suPAR is also related to the development, severity and prognosis of several diseases including coronary artery disease, diabetes mellitus, stroke, cancer, infectious diseases and sepsis in adult population [25,26]. In pediatric population, the studies with regard to suPAR are less than adult studies, and have particularly focused to various types of renal and infectious diseases [11–13]. Information with regard to the association between suPAR and childhood obesity is absent in the current literature. Therefore, we designed this study in order to determine whether suPAR is useful as a biological marker in obese children and adolescents. In this present study, we found that the median suPAR level was lower in obese group compared with control group, but this difference was not statistically significant (0.54 vs. 0.59, p = 0.26). The median hsCRP level was higher in obese group along with a statistically significant difference (1.97 vs. 0.41, p b 0.01). Therefore, it was deduced that suPAR levels were not associated with obesity, whereas hsCRP levels were found to be associated with obesity in children. Similar to the results of our study, Lyngbæk et al. [27] reported in their study with large number of participants that suPAR levels were not associated with cardiovascular risk factors like overweight and abdominal obesity (measured as body mass index and waist circumference) as opposed to CRP in adult study population. The authors indicated that suPAR was linked to endothelial dysfunction and existence of atherosclerotic plaques thus potentially representing later occurring processes in the development of cardiovascular diseases. Similarly, Botha et al. [28] also reported that suPAR was not associated with cardiometabolic factors like measures of adiposity in adult black South African population. The precise pathophysiological mechanisms of subclinical inflammation in obese children and adolescents are still unclear. There are just a few studies with small sample size on childhood obesity, which characterize the subclinical inflammation in these youth ages. However, these studies could not entirely explain the features and clinical significance of the subclinical inflammation [29]. To our best knowledge, this case–control study is the first study investigating the relationship between suPAR and childhood obesity in the literature. However, there were several limitations in the interpretation of the results of our study. The major limitations of this present study were the relatively small number of participants and not normally distribution of parametric variables in the study groups and evaluated data were limited. A larger sample could have increased the statistical power of our research.
This work was supported by Sakarya University through its institutional facilities.
References [1] R. Kelishadi, Childhood overweight, obesity, and the metabolic syndrome in developing countries, Epidemiol. Rev. 29 (2007) 62–76. [2] J.C. Han, D.A. Lawlor, S.Y. Kimm, Childhood obesity, Lancet 375 (2010) 1737–1748. [3] D.S. Freedman, W.H. Dietz, S.R. Srinivasan, G.S. Berenson, Risk factors and adult body mass index among overweight children: the Bogalusa Heart Study, Pediatrics 123 (2009) 750–757. [4] I. Manduteanu, M. Simionescu, Inflammation in atherosclerosis: a cause or a result of vascular disorders? J. Cell. Mol. Med. 16 (2012) 1978–1990. [5] M.U. Es, S. Senol, A. Yuksel, K. Kargun, Endothelin-1 gene polymorphisms in patients with peripheral artery disease, Acta Med. Mediterr. 32 (2016) 897–901. [6] S. Semiz, S. Rota, O. Ozdemir, A. Ozdemir, B. Kaptanoğlu, Are C-reactive protein and homocysteine cardiovascular risk factors in obese children and adolescents? Pediatr. Int. 50 (2008) 419–423. [7] K. Kitsios, M. Papadopoulou, K. Kosta, N. Kadoglou, M. Papagianni, K. Tsiroukidou, Highsensitivity C-reactive protein levels and metabolic disorders in obese and overweight children and adolescents, J. Clin. Res. Pediatr. Endocrinol. 5 (2013) 44–49. [8] D. Dayal, H. Jain, S.V. Attri, B. Bharti, A.K. Bhalla, Relationship of high sensitivity Creactive protein levels to anthropometric and other metabolic parameters in Indian children with simple overweight and obesity, J. Clin. Diagn. Res. 8 (2014) 5–8. [9] M. Persson, G. Engström, H. Björkbacka, B. Hedblad, Soluble urokinase plasminogen activator receptor in plasma is associated with incidence of CVD. Results from the Malmö Diet and Cancer Study, Atherosclerosis 220 (2012) 502–505. [10] A. Edsfeldt, M. Nitulescu, H. Grufman, et al., Soluble urokinase plasminogen activator receptor is associated with inflammation in the vulnerable human atherosclerotic plaque, Stroke 43 (2012) 3305–3312. [11] A. Wrotek, T. Jackowska, The role of the soluble urokinase plasminogen activator (suPAR) in children with pneumonia, Respir. Physiol. Neurobiol. 209 (2015) 120–123. [12] M.S. El-Mekkawy, N.Y. Saleh, A.A. Sonbol, Soluble urokinase plasminogen activator receptor: a new biomarker in the pediatric intensive care unit, Indian J. Pediatr. 83 (2016) 661–669. [13] J. Soltysiak, J. Zachwieja, A. Benedyk, M. Lewandowska-Stachowiak, M. Nowicki, D. Ostalska-Nowicka, Circulating suPAR as a biomarker of disease severity in children with proteinuric glomerulonephritis, Minerva Pediatr. (2016 Apr 12) (Epub ahead of print). [14] R. Bundak, A. Furman, H. Gunoz, F. Darendeliler, F. Bas, O. Neyzi, Body mass index references for Turkish children, Acta Paediatr. 95 (2006) 194–198. [15] T.J. Cole, M.C. Bellizzi, K.M. Flegal, W.H. Dietz, Establishing a standard definition for child overweight and obesity worldwide: international survey, BMJ 320 (2000) 1240–1243. [16] N.B. Schiller, P.M. Shah, M. Crawford, et al., Recommendations for quantitation of the left ventricle by two-dimensional echocardiography. American Society of Echocardiography Committee on standards, subcommittee on quantitation of two-dimensional echocardiograms, J. Am. Soc. Echocardiogr. 2 (1989) 358–367. [17] G. Iacobellis, M.C. Ribaudo, A. Zappaterreno, C.V. Iannucci, F. Leonetti, Relation between epicardial adipose tissue and left ventricular mass, Am. J. Cardiol. 94 (2004) 1084–1087. [18] C.L. Ogden, M.D. Carroll, H.G. Lawman, et al., Trends in obesity prevalence among children and adolescents in the United States, 1988–1994 through 2013–2014, JAMA 315 (2016) 2292–2299. [19] S.S. Guo, W. Wu, W.C. Chumlea, A.F. Roche, Predicting overweight and obesity in adulthood from body mass index values in childhood and adolescence, Am. J. Clin. Nutr. 76 (2002) 653–658. [20] O. Elkiran, E. Yilmaz, M. Koc, A. Kamanli, B. Ustundag, N. Ilhan, The association between intima media thickness, central obesity and diastolic blood pressure in obese and overweight children: a cross-sectional school-based study, Int. J. Cardiol. 165 (2013) 528–532. [21] R. Schiel, W. Beltschikow, G. Kramer, G. Stein, Overweight, obesity and elevated blood pressure in children and adolescents, Eur. J. Med. Res. 11 (2006) 97–101.
M. Kosecik et al. / International Journal of Cardiology 228 (2017) 158–161 [22] P. Tounian, Y. Aggoun, B. Dubern, et al., Presence of increased stiffness of the common carotid artery and endothelial dysfunction in severely obese children: a prospective study, Lancet 358 (2001) 1400–1404. [23] E.J. Roh, J.W. Lim, K.O. Ko, E.J. Cheon, A useful predictor of early atherosclerosis in obese children: serum high-sensitivity C-reactive protein, J. Korean Med. Sci. 22 (2007) 192–197. [24] R.P. Namburi, A.R. Ponnala, T.S. Karthik, P. Radha Rani, R. Maheshwari, A study on metabolic variables and its association with high sensitive C-reactive protein in obese children and adolescent, Indian J. Endocrinol. Metab. 17 (Suppl. 1) (2013) 360–362. [25] G.W. Hodges, C.N. Bang, K. Wachtell, J. Eugen-Olsen, J.L. Jeppesen, suPAR: a new biomarker for cardiovascular disease? Can. J. Cardiol. 31 (2015) 1293–1302.
161
[26] N.B. Cyrille, P.A. Villablanca, H. Ramakrishna, Soluble urokinase plasminogen activation receptor–an emerging new biomarker of cardiovascular disease and critical illness, Ann. Card. Anaesth. 19 (2016) 214–216. [27] S. Lyngbæk, T. Sehestedt, J.L. Marott, et al., CRP and suPAR are differently related to anthropometry and subclinical organ damage, Int. J. Cardiol. 167 (2013) 781–785. [28] S. Botha, C.M. Fourie, R. Schutte, A. Kruger, A.E. Schutte, Associations of suPAR with lifestyle and cardiometabolic risk factors, Eur. J. Clin. Investig. 44 (2014) 619–626. [29] C.S. Tam, K. Clément, L.A. Baur, J. Tordjman, Obesity and low-grade inflammation: a pediatric perspective, Obes. Rev. 11 (2010) 118–126.