Adipocyte Hypertrophy, Fatty Liver and Metabolic Risk Factors in South Asians: The Molecular Study of Health and Risk in Ethnic Groups (mol-SHARE)

Sonia S Anand,Dipika Desai,Hertzel C Gerstein,Karleen M Schulze,Andrew Mente,Arya M Sharma,Salim Yusuf,Shirya Rashid,Mark A Tarnopolsky,Sandy Rao,Sanja Stanojevic

doi:10.1371/journal.pone.0022112

Abstract

ObjectiveWe sought to determine if differences in the distribution and characteristics of adipose tissue between South Asians and white Caucasians account for differences in risk factors for cardiovascular disease.Research Design and MethodsWe recruited 108 healthy South Asians (36.8 years) and white Caucasians (34.2 years) within three BMI strata. Body composition, adipocyte size, abdominal fat area, and hepatic adiposity were assessed and related to fasting glucose, insulin, lipids and adiponectin.ResultsAfter adjustment for age, sex, and BMI, South Asians compared to white Caucasians had higher ln fasting insulin (mean difference (md): 0.44; 95% CI: 0.20–0.69), lower HDL cholesterol (md: −0.13; 95% CI:−0.26 to −0.01), and lower adiponectin (md: −2.38; 95% CI: −3.59 to −1.17). South Asians also had more body fat (md: 2.69; 95% CI: 0.70 to 4.69), lower lean muscle mass (md: −3.25; 95%CI: −5.35 to −1.14), increased waist to hip ratio (md: 0.03; 95% CI: 0.01–0.05), less superficial subcutaneous abdominal adipose tissue (md: −2.94; 95% CI: −5.56 to−0.32), more deep/visceral to superficial adipose tissue ratio (md 0.34; 95% CI: 0.02 to 0.65), and more liver fat (md: 7.43%; 95% CI: 2.30 to 12.55%). Adipocyte area was increased in South Asians compared to white Caucasians (md: 64.26; 95% CI: 24.3 to 104.1) units2. Adjustment for adipocyte area attenuated the ethnic differences in insulin (md: 0.22; 95% CI: −0.07 to 0.51), HDL (md: −0.01; 95% CI: −0.16 to 0.13) and adiponectin (md: −1.11; 95% CI: −2.61 to 0.39). Adjustment for differences in adipocyte area and fat distribution attenuated the ethnic difference in liver fat (md: 5.19; 95% CI: 0.31 to 10.06).ConclusionSouth Asians have an increased adipocyte area compared to white Caucasians. This difference accounts for the ethnic differences in insulin, HDL cholesterol, adiponectin, and ectopic fat deposition in the liver.

Highlights

South Asians are more likely to develop type 2 diabetes and myocardial infarction (MI) at younger ages compared to white Caucasians of European origin [1,2,3]
After adjustment for age, sex, and BMI, South Asians compared to white Caucasians had higher ln fasting insulin (mean difference: 0.44; 95% CI: 0.20–0.69), lower HDL cholesterol, and lower adiponectin
Adipocyte area was increased in South Asians compared to white Caucasians units2

Summary

Introduction

South Asians (people who originate from the Indian subcontinent) are more likely to develop type 2 diabetes and myocardial infarction (MI) at younger ages compared to white Caucasians of European origin [1,2,3]. Recent evidence suggests that South Asians develop changes in metabolic risk factors for cardiovascular disease (CVD), such as glucose, insulin, lipid levels and adipokines at significantly lower body mass indices than white Caucasians [4]. This may be due to a higher total body fat, and higher ectopic fat deposition in the abdomen, liver and elsewhere. We investigated whether differences in the amount of total fat, its distribution and adipocyte characteristics can account for differences in metabolic risk factors for CVD (i.e. glucose, insulin, lipids, adiponectin) in South Asians compared to white Caucasians

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Conclusion