[beta]-Adrenergic regulation of proinflammatory cytokines in humans

Objectives: To investigate the effects of [beta]-adrenergic stimulation on IL-6 secretion in humans, and to determine the potential contribution to this response of adipocytes and peripheral blood cells (PBC). Design: Experimental study in 8 human volunteers, and in vitro studies on murine adipocyte cell-line, 3T3.L1 and 3T3.F442A, and human PBC. Measurements: Plasma IL-6 and TNF[alpha] responses to isoprenaline infusion. Cytokine secretion from differentiated adipocyte cell-lines and PBC in response to isoprenaline. Results: Plasma IL-6 levels increased ninefold (median) by 180 min (baseline median 0.51 [interquartile range 0.47-1.4] vs 180 mins 4.53 [2.58-5.69] pg ml-1 , P=0.01). One hour after infusion, IL-6 levels (2.9 [1.27-3.98]) were lower than at 180 min (P=0.05), but higher than baseline (P=0.01). TNF[alpha] levels were unchanged. Differentiated adipocytes incubated in isoprenaline (0-0.1 μM) released significantly increased amounts of IL-6 whereas no response was elicited from PBC. Conclusions: The induction of IL-6 observed in vivo may be attributed to the [beta]-adrenergic stimulation of IL-6 release specifically from adipocytes, as opposed to circulating blood cells. INTERNATIONAL JOURNAL OF OBESITY: (2000) 24, Suppl 2, S154-S155