Depot-specific and sex-specific secretion of leptin and interleukin 6: higher leptin release in women and lower interleukin-6 release from femoral adipose tissue in vivo

Abstract

BackgroundThe female fat distribution pattern of gluteofemoral fat mass accumulation is associated with protection from cardiovascular disease and diabetes. Furthermore, women are known to have higher systemic leptin concentrations than men. Differential adipokine secretion from subcutaneous adipose tissue depots may be responsible for these differences. We aimed to study the physiological release of leptin and interleukin (IL) 6, a pro-inflammatory adipokine, from abdominal and femoral adipose tissue in vivo. MethodsDepot-specific leptin and IL-6 release were measured in 42 healthy volunteers (23 men and 19 women), matched for age and body-mass index (mean 25·4 kg/m2). Measurements were carried out after an overnight fast. Leptin and IL-6 release were studied with the arteriovenous difference technique across abdominal and femoral adipose tissue. FindingsLeptin release showed a strong sex dichotomy with 3·5-fold higher systemic plasma concentrations (p<0·001) and a 3-fold higher leptin release rate per unit fat mass across abdominal and femoral adipose tissue in women than in men (p<0·05). In both men and women, abdominal and femoral leptin release were positively correlated with each other (r=0·54, p<0·001), and negatively correlated with waist-to-hip ratio (p<0·001, controlled for sex). Abdominal IL-6 release was higher than femoral IL-6 release (p=0·001), which was a consistent finding in both men and women. InterpretationAdipose tissue is characterised by differential adipokine secretion between sexes and subcutaneous fat depots. The widely observed higher systemic leptin concentration in women is a result of a high leptin production rate and large gluteofemoral fat mass compared with men. Femoral adipose tissue is characterised by a lower IL-6 release rate, which may suggest that gluteofemoral fat is resistant to low-grade inflammation. FundingHigher Education Funding Council for England.