β₂-Adrenergic activation enhances interleukin-8 production by human monocytes

Interleukin-8 (IL-8) is an important cytokine in inflammatory processes by functioning as a chemoattractant and as an activator of oxygen metabolism. In the present study we demonstrate that β₂-adrenergic agonists potentiate the lipopolysaccharide (LPS) and IL-1 induced production of IL-8 by human monocytes. In addition, β₂-adrenergic activation enhances IL-8 release and mRNA expression for IL-8 in the human monocytic cell line U937. β₂-adrenergic activation of these cells also results in enhanced production of the anti-inflammatory cytokine IL-10. However, IL-10 is not involved in the regulation of IL-8 production. The effect of the β₂-adrenergic agonist on IL-8 production is presumably mediated via increased cAMP formation, since it can be mimicked by the cAMP analogue dibutyryl-cAMP (db-cAMP). We conclude that enhancement of IL-8 production is one of the pathways via which β₂-adrenergic agonists such as catecholamines can influence inflammatory responses.