Regulation of interleukin 8 production and gene expression in human adipose tissue in vitro

A variety of cytokines and other compounds are produced in the human adipos e tissue and may have autocrine functions in the adipose tissue as well as be involved in the complications seen in association with obesity. Because it recently has been reported that interleukin 8 (IL-8), through its effect s on the macrophage and endothelial cell, may be involved in the pathogenes is of atherosclerosis, we found it of interest to investigate whether IL-8 is produced in human adipose tissue in vitro. Human sc adipose tissue was i nvestigated both in incubations with whole adipose tissue fragments as well as with isolated mature adipocytes: In adipose tissue fragments, IL-1 beta (3 nM) and tumor necrosis factor alpha (0.6 nM) were able to stimulate IL- 8 production by 12-fold and 5-fold, respectively (P < 0.001), when incubate d for 48 h. Incubations with isolated adipocytes were performed up to 6 h, and IL-1<beta> and tumor necrosis factor a significantly increased IL-8 pro duction by 50-60% (P < 0.05). Dexamethasone (50 nM) decreased IL-8 producti on from adipose tissue fragments by 57% (P < 0.01) and from adipocytes by 3 7% (P < 0.05). IL-8 messenger RNA expression in adipocytes incubated with I L-1<beta> was increased already after 2 h (P < 0.05). Thus, the effect of p roinflammatory cytokines and dexamethasone on IL-8 production in adipose ti ssue seems to be mediated at the transcriptional level. In conclusion, it i s demonstrated for the first time that IL-8 is produced and released from h uman adipose tissue and from isolated adipocytes in vitro, which may indica te that IL-8 from adipose tissue could be involved in some of the obesity-r elated complications.