Gene expression profile of omental adipose tissue in human obesity

Abstract

The aim of the present study was to gain insight into the pathophysiology of obesity by comparing the pattern of gene expression of omental adipose tissue of obese and lean volunteers using DNA microarrays. Omental adipose tissue biopsies were obtained by laparoscopic surgery from six male patients (44.2+/-6.3 yr). RNA was extracted and pooled for the obese (BMI: 37.3+/-2.5 kg/m2) and lean (BMI: 23.4+/-0.8 kg/m2) groups. From the total number of genes analyzed (1,152 well-characterized human genes), 41% were expressed at sufficient levels in human adipose tissue for detection in the microarray experiments, finding that 89 genes were up-regulated while 64 were down-regulated at least twofold in the omental adipose tissue obtained from obese patients. We found a general tendency to blunt lipolysis inducer genes and a global down-regulation of genes encoding growth factors. Moreover, an up-regulation in the expression of several mitogen-activated protein kinases (MAPKs) was observed. The down-regulation of genes involved in lipolysis activation may be involved in the etiopathogenesis of obesity. In addition, down-regulation of growth factors and the up-regulation of MAPKs may indicate an attempt to restrain adipocyte proliferation and differentiation. Furthermore, obesity is accompanied by an altered expression in omental adipose tissue of genes involved not only in energy homeostasis but also in quite diverse biological functions, such as immune response. The genomic approach underlines the importance of adipose tissue beyond energy metabolism.

Macrophage gene expression is related to obesity and the metabolic syndrome in human subcutaneous fat as well as in visceral fat

“…Indeed, although abdominal SAT and VAT are associated with metabolic risk profile [7], it has previously been reported [7][8][9] and recently confirmed in the Framingham Heart Study [10] that high VAT has a stronger correlation with metabolic risk factors and the metabolic syndrome than SAT. Several studies report depot-specific differences in inflammatory function based on higher number of macrophages [11][12][13], macrophage crown-like structures [14] and/or elevated levels of inflammatory molecules in VAT compared with SAT of obese individuals [11,[15][16][17].…”

Microarray profiling of isolated abdominal subcutaneous adipocytes from obese vs non-obese Pima Indians: increased expression of inflammation-related genes

“…The role of adipose tissue in the aetiology of obesity [7], as well as its pathophysiological consequences [8], is increasingly being recognised. A few studies in rodents and humans have used microarray gene expression profiling of whole adipose tissue to investigate its role in obesity [9,10]. Unfortunately, the heterogeneous cell composition of adipose tissue does not provide information on the potentially diverse functions of the specific cell types of the tissue.…”

The Sir David Cuthbertson Medal Lecture Hunting for new pieces to the complex puzzle of obesity

“…VEGF mRNA expression has been identified in various cell types, including endothelial, epithelial and mesenchymal cells. Interestingly, one of these microarray studies (Gómez-Ambrosi et al 2004b) has provided evidence for increased expression of VEGF-B mRNA in omental adipose tissue of obese patients, in accordance with the need for enhanced vascularisation to support adipose mass enlargement. In particular, the mRNA of VEGF-B 167 and VEGF-B 186 , the two known isoforms of VEGF-B, were shown to be up regulated 1 .…”

“…Consequently, attention has been focused on the changes observed in angiogenic factors (Gómez-Ambrosi et al 2004b). VEGF is known to promote angiogenesis, inducing migration and proliferation of vascular endothelial cells (Berg & Scherer, 2005).…”