High Molecular Weight Adiponectin Levels are Neither Influenced by Adiponectin Polymorphisms Nor Associated with Insulin Resistance in Mixed-ancestry Hyperglycemic Subjects from South Africa.

Annalise E Zemlin,Gloudina Hon,Andre P Kengne,Tandi E Matsha,Rajiv T Erasmus

doi:10.1515/jomb-2016-0024

Abstract

SummaryBackgroundHigh molecular weight (HMW) adiponectin has antiatherogenic, antiinflammatory and antidiabetic properties and these effects have been linked to its effect on high density lipoprotein cholesterol (HDL-c). Single nucleotide polymorphisms (SNPs) in the adiponectin gene influence adiponectin levels. We examined the relationship between HMW-adiponectin levels and cardiometabolic traits in normo- and hyperglycemic mixed ancestry South Africans and correlated these levels to two common polymorphisms.MethodsHMW-adiponectin was determined in 101 subjects from the Cape Town Bellville South community-based study on a mixed ancestry population. Comparisons were made between individuals with normo- and hyperglycemia. Two common SNPs, ADIPOQ SNPs rs17300539 and rs266729, known to affect adiponectin levels were also tested for. Levels of HMW-adiponectin were then correlated with cardiometabolic traits in all groups.ResultsLevels of HMW-adiponectin were not significantly different in the normo- and hyperglycemic groups (median 11.6 vs. 10.5 μg/mL, p=0.3060) and in men and women (8.44 vs. 11.34 μg/mL, p=0.67). ADIPOQ SNPs rs17300539 and rs266729 did not influence levels of HMW-adiponectin. Robust correlation analyses revealed a significant positive correlation between HMW-adiponectin and HDL-c (r=0.45; 95%CI: 0.27–0.59), similarly in normo- and hyperglycemic participants (p > 0.99). This association was substantially attenuated in robust linear regressions adjusted for age, gender and adiposity.ConclusionsAdiponectin levels in this population were not determined by the commonest SNPs of the adiponectin gene, were unaffected by glycemic status; but were significantly correlated with HDL-c levels. Previous studies have attributed some of the beneficial effects of adiponectin to its effect on HDL-c.

Highlights

Adiponectin is the most common adipokine secreted by adipose tissue and increased visceral fat accumulation inhibits its secretion [1,2,3]
Using robust correlation statistics to eliminate the effect of outliers and account for possible non-linear correlation, we found that high density lipoprotein cholesterol (HDL-c) was significantly correlated with High molecular weight (HMW)-adiponectin in overall, normoglycemic and hyperglycemic groups
We investigated the relationship between two common polymorphisms reported in the adiponectin gene and HMW-adiponectin in mixed ancestry South Africans, and further examined its relationship with insulin resistance and cardiometabolic traits in normo- and hyperglycemic subjects

Summary

Introduction

Adiponectin is the most common adipokine secreted by adipose tissue and increased visceral fat accumulation inhibits its secretion [1,2,3]. It plays an important role in regulating glucose levels and fatty acid oxidation by enhancing insulin sensitivity and decreasing free fatty acid production [2, 4]. Higher circulating adiponectin concentrations are associated with reduced plasma glucose and serum triglyceride levels and increased high density lipoprotein cholesterol concentrations, decreased blood pressure and a lower risk of obesity and type 2 diabetes [2, 4, 6,7,8]. Several studies have described a paradox where raised adiponectin levels are associated with increased mortality especially in subjects with preexisting cardiovascular disease [11,12,13,14,15,16,17,18]

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