Abstract
BackgroundObesity and low high-density lipoprotein-cholesterol (HDL-C) levels are associated with cardiovascular risk. Surprisingly, despite a greater prevalence of obesity and lower HDL concentrations than white women, black South African women are relatively protected against ischaemic heart disease.MethodsWe investigated whether this apparent discrepancy may be related to different HDL function and subclass distribution in black and white, normal-weight and obese South African women (n = 40). HDL functionality was assessed by measuring paraoxonase (PON) activity, platelet activating factor acetylhydrolase (PAF-AH) activity, Oxygen Radical Absorbance Capacity (ORAC) and quantification of the expression of vascular cell adhesion molecule in endothelial cells. PON-1 and PAF-AH expression was determined in isolated HDL and serum using Western blotting. Levels of large, intermediate and small HDL subclasses were measured using the Lipoprint® system.ResultsPON activity was lower in white compared to black women (0.49 ± 0.09 U/L vs 0.78 ± 0.10 U/L, p < 0.05), regardless of PON-1 protein levels. Obese black women had lower PAF-AH activity (9.34 ± 1.15 U/L vs 13.89 ± 1.21 U/L, p <0.05) and HDL-associated PAF-AH expression compared to obese white women. Compared to normal-weight women, obese women had lower large HDL, greater intermediate and small HDL; an effect that was more pronounced in white women than black women. There were no differences in antioxidant capacity or anti-inflammatory function across groups.ConclusionsOur data show that both obesity and ethnicity are associated with differences in HDL functionality, while obesity was associated with decreases in large HDL subclass distribution. Measuring HDL functionality and subclass may, therefore, be important factors to consider when assessing cardiovascular risk.Electronic supplementary materialThe online version of this article (doi:10.1186/s12944-016-0257-9) contains supplementary material, which is available to authorized users.
Highlights
Obesity and low high-density lipoprotein-cholesterol (HDL-C) levels are associated with cardiovascular risk
Ethnic differences included lower visceral adipose tissue (VAT) and higher subcutaneous adipose tissue (SAT) in obese black women compared to obese white women
A greater proportion of small HDL was associated with increased body mass index (BMI) and fat mass in white women. In this preliminary study we aimed to examine whether ethnicity and obesity may be associated with differences in HDL functionality and subclass distribution
Summary
Obesity and low high-density lipoprotein-cholesterol (HDL-C) levels are associated with cardiovascular risk. Despite a greater prevalence of obesity and lower HDL concentrations than white women, black South African women are relatively protected against ischaemic heart disease. African women and African Americans exhibit protective lipid profiles, characterised by low LDL-C, low triglyceride and low total cholesterol concentrations [13, 14]. It was previously thought that a favourable lipid profile in black populations would be characterised by higher HDL-C concentrations [16, 17]. Recent studies conducted in black South African women highlighted a lower or equivalent level of HDL-C than their white counterparts [6, 12, 14, 18]
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