Introduction
Diabetes with its two major types, type 1 (T1DM) and type 2 (T2DM), has long been recognized as a major risk factor for the development of vascular disease [
1]. In adults, macrovascular complications are the leading cause of diabetes-related morbidity and mortality, namely coronary, cerebrovascular, and peripheral arterial disease (PAD) [
2]. However, in childhood T1DM, the role of macrovascular complications is underestimated with more focus on diabetic microvascular complications.
While macrovascular complications are rare until adulthood, early subtle macrovascular changes have been shown to present since childhood, making children with T1DM at risk of early adult-onset vascular disease [
3]. Predictors of PAD include glycemic and lipid derangements, diabetes duration, hypertension, and male gender [
4]. However, not all people with T1DM having poor glycemic and lipid control develop PAD. Moreover, aggressive glycemic control to lower the HbA1c did not appear to reduce the rate of PAD in those at risk as observed in the DCCT/EDIC study [
5]. Hence, understanding the genetic determinants of the risk of PAD among this vulnerable population is of utmost importance.
Ankle–brachial index (ABI), i.e., the ratio of ankle-to-brachial systolic blood pressure, is the gold standard noninvasive method for PAD diagnosis [
6]. According to the AHA, an ABI ≤ 0.90 is considered PAD. ABI can detect PAD, with > 50% stenosis with sensitivity 61–73% and specificity 83–96% [
7].
Increasing evidence suggests a link between adipokines, diabetes, and vascular diseases including PAD [
8]. Two of the most well-known adipokines, adiponectin and chemerin, have been associated with metabolic, inflammatory, and atherosclerotic diseases. Serum adiponectin levels have been associated with vascular events and/or mortality from vascular diseases [
9]. Chemerin, an adipokine highly expressed in the white adipose tissue, is associated with inflammation and adipogenesis. Chemerin not only regulates the expression of adipocyte genes linked with glucose and lipid homeostasis, but also affects innate and adaptive immunity as well as cytokine homeostasis. Furthermore, it has a role in fibrinolysis, coagulation, and inflammation [
10]. Hence, adipokines could serve as a mechanistic link between diabetes, metabolic derangements, and PAD. There remains uncertainty, however, about the strength of associations between PAD and individual adipokines with some studies suggesting that these associations are mediated through diabetes [
11].
Adiponectin level is influenced by the presence of genetic variation in its coding genes. Polymorphisms in ADIPOQ, which codes for adiponectin, have been associated with diabetes and metabolic syndrome in multiple populations [
12]. Nonetheless, genetic variation in the ADIPOQ promoter has been associated with vascular disease independent of adiponectin level [
13].
Variants of retinoic acid receptor responder 2 (RARRES2), the gene encoding chemerin, have been demonstrated to be associated with increased chemerin levels, visceral fat mass in nonobese individuals, and increased incidence of metabolic syndrome [
14]. Several experimental studies suggest an inflammatory role for chemerin during the early stages of vascular diseases [
15]. But it is currently still not clear whether an association between chemerin gene polymorphism and PAD exists. Some case–control studies have shown that higher circulating chemerin levels are associated with clinical and subclinical vascular diseases [
16,
17], whereas others did not confirm these findings [
18,
19].
Hence, this study aims to assess the frequency of adiponectin and chemerin gene polymorphism among children with T1DM in comparison to healthy control and to investigate their potential association with macrovascular complications, namely PAD and hyperlipidemia among this vulnerable cohort.
Results
Fifty children with T1DM (26 males and 24 females; ratio 1.08:1) were studied. Their mean age was 11.09 ± 2.26 years, range 8–16, and their mean HbA1c was 9.72 ± 2.03%, range 6.6–13.7. They were compared to 50 age—and gender-matched healthy controls (
p = 0.07 and
p = 0.42, respectively). The clinical, laboratory, and radiological data of the studied children with T1DM and controls are listed in Table
1.
Table 1
Clinico-laboratory and radiological characteristics of the studied children with T1DM and controls
Clinico-demographic data |
Age (years) | Mean ± SD | 11.09 ± 2.26 | 10.22 ± 2.47 | 0.070• |
Range | 8–16 | 6.08 ± 13.07 |
Gender | Female | 24 (48.0%) | 20 (40.0%) | 0.420* |
Male | 26 (52.0%) | 30 (60.0%) |
Weight Z-score | Median(IQR) | − 0.75 (− 1.09 to − 0.11) | − 0.99 (− 1.12 to − 0.68) | 0.076‡ |
Range | − 1.78 to 0.56 | − 1.2 to − 0.27 |
Height Z-score | Median(IQR) | − 0.59 (− 1.16 to 0.55) | − 0.8 (− 1.54 to − 0.13) | 0.055‡ |
Range | − 2.39 to 1.72 | − 1.73 to 0.73 |
BMI (kg/m2) | Mean ± SD | 16.95 ± 1.85 | 16.39 ± 1.37 | 0.091• |
Range | 13.85–20.93 | 13.85–19.76 |
BMI Z-score | Median(IQR) | − 0.79 (− 0.86 to − 0.58) | − 0.79 (− 0.85 to − 0.72) | 0.403‡ |
Range | − 1.03 to − 0.31 | − 1.03 to − 0.43 |
Systolic blood pressure percentile | Mean ± SD | 60.40 ± 17.72 | 55.60 ± 14.02 | 0.136• |
Range | 50–90 | 50–90 |
Diastolic blood pressure percentile | Mean ± SD | 57.20 ± 15.52 | 55.60 ± 14.02 | 0.590• |
Range | 50–90 | 50–90 |
Laboratory data |
Cholesterol (mg/dl) | Mean ± SD | 179.31 ± 50.58 | 153.12 ± 19.52 | 0.001• |
Range | 35–285 | 123–179 |
HDL (mg/dl) | Mean ± SD | 46.60 ± 11.49 | 58.28 ± 5.56 | < 0.001• |
Range | 30–70 | 48–68 |
LDL (mg/dl) | Mean ± SD | 109.30 ± 40.12 | 101.42 ± 18.96 | 0.212• |
Range | 22–201 | 69–129 |
Triglycerides (mg/dl) | Mean ± SD | 115.49 ± 94.86 | 86.26 ± 16.16 | 0.034• |
Range | 25–503 | 48–114 |
HbA1C% | Mean ± SD | 9.72 ± 2.03 | 4.49 ± 0.50 | < 0.001• |
Range | 6.6–13.7 | 3.7–5.3 |
Chimerin (RS17173608) | TT | 3 (6.0%) | 12 (24.0%) | 0.041* |
TG | 6 (12.0%) | 5 (10.0%) |
GG | 41 (82.0%) | 33 (66.0%) |
T/G | 0.12/0.88 | 0.29/0.71 | 0.003 |
Adiponectin (RS1501299) | GG | 21 (42.0%) | 31 (62.0%) | 0.011* |
GT | 10 (20.0%) | 13 (26.0%) |
TT | 19 (38.0%) | 6 (12.0%) |
G/T | 0.52/0.48 | 0.75/0.25 | 0.001 |
Radiological data |
Ankle–brachial index | Mean ± SD | 0.86 ± 0.26 | 1.05 ± 0.13 | 0.011• |
Range | 0.5–1.5 | 0.92–1.17 |
Peripheral artery disease among children with T1DM
The mean ankle–brachial index of the studied children with T1DM was 0.86 ± 0.26; range 0.5–1.5, while that of the controls was 1.05 ± 0.13; range 0.92–1.17. Children with T1DM had significantly lower ABI than controls (p = 0.011).
Although ABI was significantly correlated to diabetes duration (
r = 0.450), insulin dose (
r = 0.318), cholesterol (
r = 0.336), LDL (
r = 0.441) and negatively correlated to HDL (
r = − 0.280) among the studied children with T1DM, it was not correlated to HbA1C (
r = 0.129), Table
2.
Table 2
Correlation of ankle–brachial index with various clinico-laboratory parameters among the studied children with T1DM
Age (years) | − 0.188 | 0.192 |
Diabetes duration (years) | 0.450** | 0.001 |
Weight z-score | 0.199 | 0.165 |
Height z-score | 0.324* | 0.022 |
BMI z-score | 0.064 | 0.660 |
Insulin dosage (IU/kg/day) | 0.318* | 0.024 |
Cholesterol (mg/dl) | 0.336* | 0.017 |
HDL (mg/dl) | − 0.280* | 0.049 |
LDL (mg/dl) | 0.441** | 0.001 |
Triglycerides (mg/dl) | 0.005 | 0.975 |
HbA1C% | 0.129 | 0.374 |
Chemerin and adiponectin gene polymorphism among children with T1DM
Regarding chemerin and adiponectin gene polymorphisms, GG (mutant) chemerin genotype was detected in 41 children with T1DM (82.0%), while TT (mutant) adiponectin genotype was detected among 19 children with T1DM (38.0%).
Children with T1DM had significantly higher GG (mutant) chemerin polymorphism (
p = 0.041) and TT (mutant) adiponectin polymorphism (
p = 0.011) than controls, Table
1.
Upon assessing the relation of chemerin and adiponectin gene variants and clinico-laboratory and radiological parameters among the studied children with T1DM, those having GG chemerin variant and those having TT adiponectin variant had significantly higher cholesterol (
p < 0.001 and
p < 0.001) with significantly lower HDL-C (
p = 0.012 and
p = 0.023) and ABI (
p = 0.017 and
p = 0.035) than those having the other two variants; Table
3.
Table 3
Distribution of different chimerin and adiponectin gene variants in relation to the clinico-laboratory and radiological parameters among the studied children with T1DM
Diabetes duration (years) | Median (IQR) | 6 (5–7) | 7.5 (5–9) | 7 (5–9) | 0.481‡ | 0.786 | 7 (5–10) | 7 (5–8) | 6 (5–8) | 1.523‡ | 0.467 |
Range | 5–7 | 4–12 | 2–13 | 2–13 | 2–12 | 2–13 |
BMI z score | Median (IQR) | − 0.48 (− 0.58–− 0.43) | -0.34 (-0.43–-0.31) | -0.32 (-0.61–0.02) | 1.007‡ | 0.604 | − 0.27 (− 0.50–0.10) | − 0.44 (− 0.60–− 0.18) | − 0.37 (− 0.61–− 0.18) | 2.428‡ | 0.297 |
Range | − 0.58–− 0.43 | − 0.45–-− 0.18 | − 0.87–1.37 | − 0.87–4.26 | − 0.79–1.33 | − 0.86–4.37 |
Nephropathy | 0 (0.0%) | 1 (16.7%) | 8 (19.5%) | 0.729* | 0.694 | 4 (21.1%) | 1 (10.0%) | 4 (19.0%) | 0.569* | 0.752 |
Neuropathy | 0 (0.0%) | 0 (0.0%) | 4 (9.8%) | 0.954* | 0.621 | 2 (10.5%) | 1 (10.0%) | 1 (4.8%) | 0.518* | 0.772 |
Cholesterol (mg/dl) | Mean ± SD | 96.33 ± 53.35 | 128.33 ± 28.44 | 192.84 ± 42.39 | 12.598• | < 0.001 | 213.00 ± 50.97 | 152.10 ± 30.15 | 161.79 ± 41.83 | 9.253• | < 0.001 |
Range | 35–132 | 78–156 | 138–285 | 132–285 | 78–181 | 35–228 |
HDL (mg/dl) | Mean ± SD | 51.67 ± 16.50 | 58.50 ± 6.02 | 44.49 ± 10.77 | 4.859• | 0.012 | 40.99 ± 9.10 | 50.20 ± 14.53 | 49.95 ± 10.31 | 4.101• | 0.023 |
Range | 35–68 | 50–65 | 30–70 | 30–60 | 30–70 | 35–68 |
LDL (mg/dl) | Mean ± SD | 86.33 ± 10.60 | 79.67 ± 38.40 | 115.32 ± 39.67 | 2.777• | 0.072 | 117.79 ± 36.77 | 91.60 ± 27.88 | 110.05 ± 46.38 | 1.427• | 0.250 |
Range | 75–96 | 30–130 | 22–201 | 52–201 | 30–130 | 22–201 |
Triglycerides (mg/dl) | Mean ± SD | 58.33 ± 30.57 | 78.50 ± 32.56 | 125.08 ± 101.48 | 1.221• | 0.304 | 149.00 ± 135.07 | 88.84 ± 39.50 | 97.86 ± 56.34 | 2.024• | 0.143 |
Range | 29–90 | 25–124 | 29–503 | 56–503 | 29–153 | 25–196 |
HbA1C % | Mean ± SD | 9.20 ± 2.51 | 8.97 ± 2.40 | 9.87 ± 1.97 | 0.612• | 0.546 | 9.73 ± 1.83 | 10.00 ± 1.81 | 9.58 ± 2.35 | 0.140• | 0.870 |
Range | 6.8–11.8 | 7–12 | 6.6–13.7 | 7–12.9 | 7–12 | 6.6–13.7 |
Ankle–brachial index | Mean ± SD | 0.97 ± 0.22 | 0.78 ± 0.23 | 0.65 ± 0.22 | 4.456• | 0.017 | 0.78 ± 0.24 | 0.80 ± 0.14 | 0.98 ± 0.29 | 3.607• | 0.035 |
Range | 0.5–1.5 | 0.53–0.99 | 0.55–0.98 | 0.5–1.49 | 0.53–0.98 | 0.65–1.5 |
Chemerin and adiponectin gene polymorphism in relation to peripheral artery disease
As shown in Fig.
1 and Table
4, the G chemerin allele and the T adiponectin allele were found to be significantly associated with abnormal ABI (
p = 0.017 and
p = 0.022, respectively). Moreover, the chemerin TT polymorphism was found to be significantly related to ABI in the co-dominant and recessive models (
p = 0.017 and
p = 0.030), while the adiponectin TT polymorphism was found to be significantly associated with abnormal ABI in the co-dominant model (
p = 0.044).
Table 4
Associations of chimerin and adiponectin gene polymorphism with the risk of PAD among children with T1DM
Codominant |
TT | 8 (57.1%) | 11 (30.6%) | Ref | | Ref | | TT | 7 (50.0%) | 34 (94.4%) | Ref | | Ref | |
GT | 3 (21.4%) | 6 (16.7%) | 0.217 (0.047–0.993) | 0.049 | 0.198 (0.041–0.956) | 0.044 | TG | 5 (35.7%) | 1 (2.8%) | 0.103 (0.008–1.298) | 0.079 | 0.288 (0.018–4.511) | 0.375 |
GG | 3 (21.4%) | 19 (52.8%) | 0.316 (0.05–1.998) | 0.221 | 0.343 (0.052–2.267) | 0.267 | GG | 2 (14.3%) | 1 (2.8%) | 0.041 (0.004–0.409) | 0.006 | 0.053 (0.005–0.591) | 0.017 |
Recessive |
TT | 8 (57.1%) | 11 (30.6%) | Ref | | Ref | | GG | 2 (14.3%) | 1 (2.8%) | Ref | | Ref | |
GT + GG | 6 (42.9%) | 25 (69.4%) | 3.03 (0.848–10.835) | 0.088 | 3.461 (0.898–13.337) | 0.071 | TG + TT | 12 (85.7%) | 35 (97.2%) | 5.833 (0.484–70.244) | 0.165 | 2.371 (0.159–35.335) | 0.531 |
Dominant |
TG + TT | 11 (78.6%) | 17 (47.2%) | Ref | | Ref | | TG + GG | 7 (50.0%) | 3 (8.3%) | Ref | | Ref | |
GG | 3 (21.4%) | 19 (52.8%) | 4.098 (0.976—17.202) | 0.054 | 4.211 (0.973—18.231) | 0.055 | TT | 7 (50.0%) | 33 (91.7%) | 11.000 (2.267–53.372) | 0.003 | 6.310 (1.195—33.329) | 0.030 |
Allele |
T | 19 (67.9%) | 28 (38.9%) | Ref | | Ref | | T | 19 (67.9%) | 69 (95.8%) | Ref | | Ref | |
G | 9 (32.1%) | 44 (61.1%) | 3.317 (1.317–8.357) | 0.011 | 3.300 (1.191–9.140) | 0.022 | G | 9 (32.1%) | 3 (4.2%) | 10.895 (2.682–44.262) | 0.001 | 5.995 (1.375–26.136) | 0.017 |
Upon performing univariate and multivariate regression analyses for factors associated with chemerin and adiponectin gene polymorphism among children with T1DM, cholesterol and ABI were the significant independent variables related to chemerin (
p = 0.03 and
p = 0.038, respectively); as for adiponectin gene polymorphism, it was independently related to cholesterol, triglycerides, and ABI (
p = 0.016,
p = 0.023, and
p = 0.021), Table
5.
Table 5
Univariate and multivariate logistic regression analysis (using backward Wald method) for factors associated with chimerin GG polymorphism and adiponectin TT polymorphism among children with T1DM
Cholesterol (mg/dl) | 1.143 (1.038–1.259) | 0.007 | 1.212 (1.019–1.440) | 0.030 | 1.032 (1.012–1.053) | 0.002 | 1.028 (1.005–1.052) | 0.016 |
HDL (mg/dl) | 0.907 (0.842–0.978) | 0.011 | | | 0.921 (0.864–0.981) | 0.011 | – | – |
LDL (mg/dl) | 1.027 (1.003–1.052) | 0.031 | | | 1.007 (0.999–1.016) | 0.093 | – | – |
Triglycerides (mg/dl) | 1.017 (0.997–1.038) | 0.094 | | | 23.388 (1.712–319.465) | 0.018 | 17.541 (9.053–44.911) | 0.023 |
Ankle–brachial index | 11.000 (2.267–53.372) | 0.003 | | 6.512 (1.177–31.418) | 0.038 | 16.250 (1.917–137.778) | 0.011 | 13.232 (1.839–127.572) |
Discussion
Subclinical PAD detected as increased ABI has been documented among youth with T1DM. This subclinical vascular affection is recognized as a strong independent predictor for future cardiovascular and cerebrovascular morbidity and mortality [
29,
30]. PAD is a complex dynamic process modified by a variety of molecular signaling pathways and genetic determinants [
31]. An imbalance between pro-inflammatory and anti-inflammatory cytokines is among the suggested pathways.
Polymorphism of the genes encoding these adipokines may play a role in this process. Hence, assessing the role of these adipokines polymorphisms in the occurrence of PAD among children with T1DM is of utmost important aiming to avoid disease progression and prevent patients at high risk from developing cardiovascular and cerebrovascular events.
In the current study, abnormal ABI was detected in 28% of the studied children with T1DM, of which 85.7% had ABI < 0.9 and 14.3% had ABI higher than 1.2. Nattero-Chávez and colleagues reported an overall prevalence of PAD of 12.8% among children with T1DM [
29]. Another study including adults with T1DM described a prevalence of PAD of 27.7% [
32]. The high prevalence of subclinical PAD among this population highlights the importance of addressing its genetic determinants.
Overall, children with T1DM had significantly lower ABI than controls. Low ABI is known to be a strong predictor of cardiovascular morbidity and mortality in people with diabetes [
33]. In agreement with the current results, Pastore and colleagues reported increased subclinical vascular diseases among children with T1DM compared to healthy controls manifested as reduced brachial artery flow-mediated dilatation reactivity and increased carotid–femoral pulse wave velocity [
34].
Although the relation between T1DM and PAD is well established, the determinants of PAD among children with T1DM remains unclear. The proposed predictors of PAD include glycemic and lipid derangements, diabetes duration and hypertension, and male gender [
4]. In the current study, PAD was found to be correlated with diabetes duration, insulin dose, and lipid derangements; interestingly, it was not correlated to HbA1C. This goes in line with the DCCT/EDIC study that observed that lowering HbA1c is not solely enough to reduce the rate of PAD in those at risk [
5].
In the context of adipokines gene polymorphism, children with T1DM were found to have significantly higher GG chemerin and TT adiponectin gene polymorphisms than controls. The pro-inflammatory chemerin and the anti-inflammatory adiponectin gene polymorphisms have been investigated separately in obesity and T2DM. However, data about their role in T1DM is scarce and lacking. Perumalsamy and coworkers found a significant association between chemerin gene polymorphism and insulin resistance and cardiovascular disease among adults with T2DM [
35]. Moreover, the frequency of the G allele of the chemerin rs17173608 polymorphism was found to be significantly higher in people with T2DM than in controls [
36]. Regarding adiponectin rs1501299 polymorphism, it has been linked significantly to T1DM in adults [
37]. In addition, Cui and coworkers found a significant association between adiponectin rs1501299 polymorphism and T2DM among adults [
38].
Interestingly, children with T1DM having GG chemerin variant and those having TT adiponectin variant were found to have significantly higher cholesterol and significantly lower HDL-C than those having the other two variants. Chemerin expression and secretion are reported to increase significantly with adipogenesis. A previous study showed a significant relation between LDL and GG chemerin genotype among adults with metabolic syndrome [
39].
Moreover, chemerin was previously reported to have a strong positive correlation with triglycerides, cholesterol, and LDL with a strong negative correlation with HDL-C [
40]. As for adiponectin, a previous study by Tsuzaki and coworkers found that HDL-C was significantly and independently correlated with adiponectin and adiponectin rs1501299 G allele by multivariate regression analysis [
41].
In the present study, adiponectin and chemerin gene polymorphism was found to be independently associated with PAD among children with T1DM, which suggests a possible role for these polymorphisms in the development of PAD among this population. This goes in agreement with the study by Kennedy and coworkers which identified increased expression of chemerin in atherosclerotic coronary arteries, aorta, and mesenteric arteries [
42]. They found that mRNA and protein of chemerin receptors are widely expressed in smooth muscles and endothelial cells of human vessels, reinforcing the importance of their role in vasculature modulation. Interestingly, the expression of chemerin they found in the vascular smooth muscles is similar to that reported for adiponectin [
43]. Moreover, adiponectin gene mutations were found to be strongly associated with impaired glucose tolerance, diabetes mellitus, and coronary artery disease in humans [
44]. In mice, a high-fat and high-sucrose diet was found to cause marked elevation of plasma glucose and insulin levels, insulin resistance, and an increase in intimal smooth muscle cell proliferation in adiponectin knockout mice [
45].
Conclusion
Subclinical PAD probably starts early in children with T1DM as denoted by abnormal ABI. This abnormal ABI is independently related to chemerin and adiponectin gene polymorphism.
Thus, chemerin and adiponectin gene polymorphisms could have a role in the pathogenesis of PAD among children with T1DM. Moreover, chemerin and adiponectin genes could be used as risk biomarkers for hyperlipidemia and vascular affection among children with T1DM.
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