Arterial stiffness and its association with advanced glycation end-products in 6-8 year old boys : the ASOS study

Abstract

Motivation : Early vascular changes are suggested to develop prematurely in the black population even in the absence of vascular disease, therefore increasing their risk for hypertension and arterial stiffness development. Different factors are known to contribute to the development of arterial stiffness, including biological ageing, adiposity and advanced glycation end-products (AGEs). AGEs are formed through non-enzymatic oxidation and glycation of free amino acid groups of lipids, nucleic acids and proteins. Formation of AGEs is stimulated by hyperglycemia and is associated with conditions such as diabetes mellitus. AGEs have received scientific interest regarding their role in arterial stiffness and cardiovascular related diseases such as type 2 diabetes mellitus. Information regarding the influence of AGEs on arterial stiffness in children is scant, and no previous comparative studies regarding the contribution of body composition and AGEs on arterial stiffness development in black and white children have been conducted. Aim : To compare different estimates of arterial stiffness in 6–8 year old black and white South African boys and investigate the links between arterial stiffness indices, body composition and advanced glycation end-products (AGEs). Methodology : We included 40 black and 41 white South African boys aged from 6–8 years in this study. This study obtained approval from the Provincial Department of Education and the Health Research Ethics Committee of the North-West University (NWU-00007-15-A1). We excluded obese children and those using any chronic medication, with type 1 diabetes mellitus, renal disease or cancer. AGEs, specifically pentosidine, in urine was analysed by a trained biochemist. Trained postgraduate students measured blood pressure in triplicate and continuous arterial blood pressure with participants in a sitting position. The SonoSite MicroMaxx (SonoSite Micromaxx, Bothell, WA) and a 6-13 MHz linear array probe were used to determine the carotid artery distensibility. Pulse wave velocity (PWV) was determined across various sections (carotidradial; carotid-dorsalis pedis; carotid-femoral) of the arterial tree in duplicate. Anthropometric measurements included body height, weight, hip, waist and neck circumferences and were measured in triplicate. Body mass index z-scores were used to classify body composition of the boys according to appropriate age, height and weight cut-offs. Results : Age and body composition were comparable between the groups except for white boys with higher neck circumference (p=0.003) and waist-to-hip ratio (p<0.0001) than black boys. Pentosidine levels were higher in black boys (p=0.039), as well as diastolic blood pressure (p=0.001), mean arterial pressure (p=0.003) and total peripheral resistance (p=0.044) compared to white boys. After adjusting for mean arterial pressure, carotid-to-radial pulse wave velocity, carotid-to-femoral pulse wave velocity and carotid-to-dorsalis pedis pulse wave velocity (all p<0.002) as well as carotid intima-media thickness (p=0.007) were higher in black compared to white boys. Correlations between measures of arterial stiffness and body composition were evident in white boys only. Carotid-to-femoral PWV correlated inversely with BMI (r =–0.32; p=0.049), only in black boys. Pentosidine inversely correlated with body composition variables including body mass index (p=0.015), body surface area (p=0.017), weight (p=0.018), waist circumference (p=0.022) and hip circumference (p=0.010) in black boys only. Arterial stiffness indices did not correlate with AGEs in any group. General conclusion : In conclusion, pulse wave velocity of black boys was higher in all sections of the arterial tree, along with higher diastolic blood pressure, intima-media thickness and AGEs, suggesting that early arterial changes are already present in young black boys. This phenotype may have an impact on the increasing trend of hypertension in the black population of South Africa.