Testosterone increases CCL-2 expression in visceral adipose tissue from obese women of reproductive age

Abstract

ContextHyperandrogenic states and obesity in women are associated with insulin-resistance. Androgens reduce glucose uptake in adipose cells and increase TNFα production in peripheral monocytes. Inflammatory cytokines have a known detrimental effect on insulin resistance. The aim of the present study was to explore the role of testosterone in local cytokine production in visceral adipose tissue from women of reproductive age. DesignTwenty-four women 18–40 years old, undergoing elective abdominal surgery for benign and non-inflammatory conditions, were recruited for the study. Women with clinical hyperandrogenism, diabetes, hepatic or renal dysfunction, hypothyroidism, BMI> 40 or drugs known to interfere with hormonal levels or fat metabolism were excluded. Women were classified into two groups according to BMI, non-obese (NO; BMI < 30) and obese (O; BMI 30–40). A basal blood sample was drawn at the time of surgery for the measurement of glucose, insulin, total testosterone, lipid profile and circulating CCL-2, IL-6 and total adiponectin. Omental fat tissue (10 g) was obtained in all women. Samples of 300 mg of minced adipose tissue were incubated with vehicle (CTL) or testosterone (T) 10−9 M to 10−6 M for 24, 48 or 72 h. CCL-2, IL-6, TNFα, androgen Receptor (AR) mRNA levels were measured by Real Time quantitative polymerase chain reaction (qPCR) and normalized to GAPDH expression. Secretion of CCL-2 and IL-6 was measured in conditioned media by ELISA. ResultsExpression of CCL-2 and IL-6 at 24 h in CTLs was significantly higher in the obese group compared to the non-obese group (2.81 ± 0.43 fold for CCL-2; p = 0.005 and 3.26 ± 0.73 fold for IL-6; p = 0.03). At 48 and 72 h there were no differences between both groups in any of the markers. In the total group without T stimulation (CTL) there were significant correlations between: TNFα expression at 24 h and BMI (r = 0.708; p = 0.005), TGC levels (r = 0.904; p = 0.004), total Cholesterol (r = 0.904; p = 0.0046) and IL-6 expression at 24 h (r = 0.642; p = 0.015). CCL-2 expression at 24 h was correlated with BMI (r = 0.637; p = 0.007) and TGC levels (r = 0.700; p = 0.02). Stimulation with T 10−6 M for 72 h produced an increase in CCL-2 expression, which was significantly larger in the obese group compared to the non-obese group (2.04 ± 0.44 in obese vs 0.82 ± 0.11 in non-obese; p = 0.015). Moreover, in the whole group there was a positive correlation between CCL-2 expression in T-treated tissues (10−6 M 72 h) and BMI (r = 0.514; p = 0.017). Cytokine determinations followed the same pattern as mRNA but without significant differences. ConclusionsTestosterone increases CCL-2 expression in visceral adipose tissue from obese women of reproductive age. This response is associated to BMI. These results show new possible mechanisms connecting androgens to insulin resistance and chronic inflammation.