Correlative studies on the effects of obesity, diabetes and hypertension on gene expression in omental adipose tissue of obese women.

J N Fain

doi:10.1038/nutd.2011.14

Abstract

Objective:A major consequence of obesity is the enormous expansion of and enhanced inflammatory response seen in visceral adipose tissue. I hypothesized that the expression of inflammatory markers in visceral omental fat would correlate with the extent of visceral adiposity as measured by waist circumference or body mass index and that diabetes and hypertension, defined as subjects taking anti-hypertensive drugs, would be associated with changes in mRNA expression in visceral fat.Design and methods:The expression of 106 mRNAs by RT-PCR was examined in observational studies using extracts of omental fat of obese women undergoing bariatric surgery as well as the circulating levels of some adipokines. We also compared the mRNA levels of 65 proteins in omental fat removed during gastric bypass surgery of women with and without hypertension and those with type 2 diabetes.Results:Out of 106 mRNAs the expression of 10 mRNAs in omental fat of women not taking anti-hypertensive drugs correlated with waist circumference while 7 different mRNAs had significant correlations with circulating glucose. The correlations of waist circumference with mRNA expression were abolished, except for interleukin (IL)-1 receptor antagonist (IL-1RA), in women taking anti-hypertensive drugs. The correlations of blood glucose with omental fat mRNA expression were abolished, except for that of Akt1 and Akt2, in women taking anti-hypertensive drugs. However, the expression of 4 different mRNAs in omental fat was affected by circulating glucose in subjects taking anti-hypertensive drugs. The circulating levels of IL-1 RA, but not fatty acid binding protein 4, adipsin and phospholipase A2, correlated with both waist circumference and mRNA expression in omental fat.Conclusion:In female bariatric surgery patients, the mRNA expression of some proteins in omental fat was affected by the degree of obesity, whereas hypertension and diabetes affected a separate set of mRNAs.

Highlights

The current paradigm is that extreme obesity results in increased risk for hypertension and/or diabetes.[1,2] The type 2 diabetes is reversible as, after weight loss of approximately 40 kg or more of weight due to bariatric surgery, the diabetes disappears in over 80% of humans.[1]
Waist circumference is arguably the best inexpensive marker for visceral obesity.[6]. It appears to be better marker than body mass index (BMI) in the sense that more of the mRNAs examined in this observational report using human omental fat showed greater positive correlations between their gene expression and waist circumference as compared with BMI
The reasons for these differences are unclear and just the opposite was seen with regard to cell death-inducing DFFA-like effector A (CIDEA) whose gene expression better correlated with BMI than with waist circumference

Summary

Introduction

The current paradigm is that extreme obesity results in increased risk for hypertension and/or diabetes.[1,2] The type 2 diabetes is reversible as, after weight loss of approximately 40 kg or more of weight due to bariatric surgery, the diabetes disappears in over 80% of humans.[1]. One study found that half of the extremely obese women with a mean waist circumference of 102 cm developed diabetes mellitus/hypertension, and their visceral fat mass was 26% greater than those not at risk with a waist circumference that averaged 96 cm.[4] Since these women had more visceral fat, this could account for the differences in diabetes/hypertension. There is increasing evidence that the accumulation of visceral omental fat is associated with the development of diabetes/hypertension.[5] It is recognized that waist circumference is an effective and inexpensive measure of visceral fat accumulation.[6,7,8,9,10] Waist circumference in women is a better predictor of coronary heart disease than is body mass index (BMI) 8–10 and correlates with visceral fat accumulation as measured by magnetic resonance imaging,[6] dual-emission x-ray absorptiometry 7 or fat mass measured by bioelectrical impedance.[11] it is

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Results

Conclusion