Background: The metabolic syndrome describes the association between obesity and co-morbidities including insulin resistance, hypertension, dyslipidemia, and cardiovascular (CV) disease. Adipokines produced from omentum contribute to the risk of CV disease and increase the inflammatory state. This study examines the gene expression differences in the omental tissue of morbidly obese diabetic and non-diabetic patients.
Methods: Twenty morbidly obese patients undergoing bariatric surgery were included. Ten patients were diabetic and 10 were non-diabetic. Omental samples were collected intraoperatively and snap frozen. Total RNA was extracted using the Trizol reagent and purified with the RNeasy kit (Qiagen). Microarray experiments were performed using the Affymetrix Gene 1.0 ST array and data was analyzed with the Partek 6.3 program using an unpaired t-test (P<0.05). The gene expression profiles of the diabetic group were compared with the non-diabetic group. Using the Ingenuity program, the gene list generated from the microarray analysis was evaluated and real-time quantitative PCR (qPCR) was used to validate the array data.
Results: Compared with the non-diabetic group, the diabetic obese patients showed 79 upregulated genes and 4 downregulated genes with >1.4-fold difference in expression. Ingenuity analysis showed numerous dysregulated genes associated with CV disease including leptin, Von Willebrand factor, P-selectin, angiopoietin-1 (ANGPT1), phospholipase A2 (group VII), and periostin osteoblast specific factor. Microarray results for the earlier mentioned genes were confirmed with qPCR. The results were analyzed with respect to the presence or absence of hyperlipidemia, hypertension, and coronary artery disease. In patients with hyperlipidemia, ANGPT1 and P-selectin were upregulated 1.9- and 2.9-fold, respectively.
Conclusions: This microarray analysis of omental tissue from morbidly obese diabetic patients documents a host of upregulated genes related to CV disease. This study provides further evidence that diabetic status predisposes obese patients to a higher risk of developing CV disease.