Expression of omentin in adipose tissues in obese and type 2 diabetic patients

Abstract

To analyze the mRNA expression of omentin mRNA level in subcutaneous and omental adipose tissues of normal, obese, and type 2 diabetic individuals and to investigate the relationship between omentin mRNA expression and serum omentin level, body fat parameters, glucose and lipid metabolism, and insulin resistance indexes. 36 patients with benign diseases undergoing selective abdominal operation, 19 males and 17 females, aged 20 - 65, included 12 with normal glucose regulation and normal weight (NGR-NW group), 12 with normal glucose regulation and overweight/obesity (NGR-OW/OB group), and 12 with type 2 diabetes and overweight/obesity (T2DM-OW/OB group). Abdominal subcutaneous and omental adipose tissues were obtained during operation. Real-time quantitative PCR was used to measure the omentin mRNA level. The level of fasting serum omentin was measured by ELISA. Meanwhile blood glucose, HbA(1C), lipids and insulin levels were measured. Body weight, BMI and waist hip ratio (WHR) were evaluated and insulin sensitivity was assessed by homeostasis model assessment insulin resistance index (HOMA-IR). The omentin mRNA level in omental adipose tissue of the NGR-NW group was (1.52 +/- 0.32), significantly higher than that in subcutaneous adipose tissue [(0.019 +/- 0.006), P < 0.01]. The omentin mRNA level of the males was (1.46 +/- 0.31), not statistically different from that of the female [(1.58 +/- 0.29), P = 0.416]. The omentin mRNA level of the NGR-OW/OB group was (1.18 +/- 0.29), significantly lower than that of the NGR-NW group [(1.52 +/- 0.32), P < 0.05], and the omentin mRNA level of the T2DM-OW/OB group was (0.98 +/- 0.37), both significantly lower than those of the other 2 groups (both P < 0.05). Partial correlation analysis showed that the omentin mRNA was negatively correlated with HOMA-IR, body weight, WHR, triglyceride, BMI, and fasting insulin, and positively correlated to serum omentin level and HDL-C. Multiple linear regression analysis showed that serum omentin level, HOMA-IR, and body weight were independent variables of omentin. Omentin mRNA is highly expressed in omental adipose tissue. The omentin mRNA expression level decreases in the overweight/obese individuals and decreases further when overweight/obesity is combined with type 2 diabetes. Omentin mRNA is positively correlated to serum omentin level, obese indexes, insulin resistance, and lipid metabolism parameters. Decreased omentin gene expression may contribute to the underlying pathophysiology of insulin resistance syndrome.