Serum Resistin (FIZZ3) Protein Is Increased in Obese Humans

Abstract

The role of resistin in obesity and insulin resistance in humans is controversial. Therefore, resistin protein was quantitated by ELISA in serum of 27 lean [13 women/14 men, body mass index (BMI) 21.7 +/- 0.4 kg/m(2), age 33 +/- 2 yr] and 50 obese (37 women/13 men, BMI 49.8 +/- 1.5 kg/m(2), age 47 +/- 1 yr) subjects. There was more serum resistin protein in the obese (mean +/- SEM: 5.3 +/- 0.4 ng/ml; range 1.8-17.9) than lean subjects (3.6 +/- 0.4 ng/ml; range 1.5-9.9; P = 0.001). The elevation of serum resistin in obese humans was confirmed by Western blot as was expression of resistin protein in human adipose tissue and isolated adipocytes. There was a significant positive correlation between resistin and BMI (r = 0.37; P = 0.002). Multiple regression analysis with predictors BMI and resistin explained 25% of the variance in homeostasis model assessment of insulin resistance score. BMI was a significant predictor of insulin resistance (P = 0.0002), but resistin adjusted for BMI was not (P = 0.11). The data demonstrate that resistin protein is present in human adipose tissue and blood, and that there is significantly more resistin in the serum of obese subjects. Serum resistin is not a significant predictor of insulin resistance in humans.

Resistin concentrations before and after weight loss in obese children

“…In contrast to some studies in adults, [6][7][8]18 the resistin levels did not differ between obese and lean children. The sample sizes in the studies in adults were similar 6 or smaller 7,8,18 as compared to our study.…”

“…The sample sizes in the studies in adults were similar 6 or smaller 7,8,18 as compared to our study. A too small sample size in our study to detect significant differences was excluded by a power analysis.…”

“…2,3 Studies in humans are even more controversial. 4,5 In crosssectional studies in adulthood, serum resistin was reported to be related to fat mass [6][7][8] and to insulin resistance, [9][10][11][12] while other reports reveal no correlations to BMI, percent body fat 11,[13][14][15] or to insulin sensitivity. 13,14,16,17 Longitudinal data are necessary to analyze the relationships between resistin, obesity, and insulin resistance.…”

Regulation of insulin signalling, glucose uptake and metabolism in rat skeletal muscle cells upon prolonged exposure to resistin

“…Nevertheless, despite the species differences outlined above, an increased plasma resistin concentration was observed in the serum of obese [16] or type 2 diabetics [17] and thiazolidinedione treatment resulted in decreased plasma resistin levels in patients with type 2 diabetes [18]. Furthermore, although some studies suggest a link between resistin and insulin sensitivity [19] others have failed to show an association with insulin resistance [16,20,21].…”

Increased serum resistin in elite endurance athletes with high insulin sensitivity

“…The identity of resistin amino acid sequences in mouse and human proteins is only 59% [6] and because of this incomplete homology resistin may have different physiological roles in different species [7]. In fact, studies in humans reported conflicting results, indicating decreased or increased resistin levels in obesity, opposite responses to insulin-sensitisers and contradictory correlations between resistin and markers of insulin resistance [8][9][10][11][12][13][14][15]. It has also been suggested that resistin plays a role in inflammatory conditions, because it is expressed in human macrophages [16] and because recent data have supported the existence of an independent association of resistin with the inflammatory factors IL-6 and C-reactive protein [17].…”