Caffeine reduces TNFα up-regulation in human adipose tissue primary culture

Abstract

Adipose tissue secretions play an important role in the development of obesity-related pathologies such as diabetes. Through inflammatory cytokines production, adipose tissue stromavascular fraction cells (SVF), and essentially macrophages, promote adipocyte insulin resistance by a paracrine way. Since xanthine family compounds such as caffeine were shown to decrease inflammatory production by human blood cells, we investigated the possible effect of caffeine on Tumor Necrosis Factor alpha (TNFalpha) and Interleukin-6 (IL-6) expression by human adipose tissue primary culture. For that purpose, human subcutaneous adipose tissue obtained from healthy non-obese women (BMI: 26.7 +/- 2.2 kg/m2) after abdominal dermolipectomy, was split into explants and cultured for 6 hours with or without caffeine. Three different concentrations of caffeine were tested (0.5 microg/mL, 5 microg/mL and 50 microg/mL). After 6 hours of treatment, explants were subjected to collagenase digestion in order to isolate adipocytes and SVF cells. Then, TNFalpha and IL-6 mRNA were analysed by real-time PCR alternatively in adipocytes and SVF cells. In parallel, we checked gene expression of markers involved in adipocyte differenciation and in SVF cells inflammation and proliferation. Our findings show a strong and dose dependent down-regulation of TNF-alpha gene expression in both adipocyte and SVF cells whereas IL-6 was only down regulated in SVF cells. No effect of caffeine was noticed on the other genes studied. Thus, caffeine, by decreasing TNFalpha expression, could improve adipose tissue inflammation during obesity.