Stress induced circulating catecholamines are hypothesized to selectively activate adrenergic receptors (ARs) on immunocompetent cells modulating their inflammatory response to trauma or environmental toxins. We characterized changes in expression of a pro-inflammatory cytokine modulated by β-AR activation in human primary and immortalized monocytes that had been simultaneously stimulated with lipopolysaccharide (LPS). Results from cytokine antibody arrays demonstrated that half-maximal effective concentrations of the selective β-AR agonist isoproterenol (Iso) qualitatively increased LPS-mediated expression of the soluble cytokine, interleukin-1β (IL-1β). Semi-quantitative immunoblot techniques confirmed a synergistic increase of IL-1β production in both LPS stimulated THP-1 cells and primary human monocytes co-incubated with Iso. Immunoblot techniques as well as radioligand binding studies were also used to characterize the heterogeneous expression of β 1 -and β 2 -AR subtypes on THP-1 cells. β-AR activation is classically associated with generation of cAMP in many tissues and cell types. Therefore, using the method of Schild, we generated Iso concentration-response curves in the presence of fixed subtype-selective β-AR antagonist concentrations to demonstrate that β 1 -AR activation was exclusively linked with the generation of cAMP in THP-1 cells. Furthermore, use of a selective kinase inhibitor demonstrated that Iso potentiated the expression of soluble IL-1β through activation of cAMP-dependent protein kinase A. Finally, discriminating concentrations of subtype-selective β-AR antagonists revealed that β 1 -AR stimulation alone accounted for the synergistic production of IL-1β in LPS stimulated monocytes co-incubated with Iso. These results demonstrate a unique synergistic pro-inflammatory Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. CONFLICT OF INTEREST STATEMENT NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript response mediated through a β 1 -AR cAMP-dependent mechanism in LPS challenged monocytic cells.

Increased circulating catecholamines released from the sympathetic nervous system, selectively activate immune cell receptors, modulating their inflammatory response to stress, injury or environmental toxins. Human monocytic THP‐1 cells were used to measure expression of inflammatory mediators responding to β‐adrenergic receptor (AR) activation in the presence or absence of lipopolysaccharide (LPS). Results from antibody arrays demonstrated that effective concentrations of the selective β‐AR agonist isoproterenol (Iso) synergistically increased LPS‐mediated expression of interleukin‐1β (IL‐1β) in THP‐1 cells. Selective kinase inhibition demonstrated that this β‐AR‐mediated, synergistic IL‐1β response signaled through activation of cAMP‐dependent protein kinase A. Radioligand binding studies further characterized a heterogeneous β‐AR population expressed on these same cells. Schild analysis demonstrated that only the β1‐AR subtype was responsible for generating cAMP in response to Iso. Furthermore, discerning concentrations of subtype‐selective β‐AR antagonists revealed that β1‐AR subtype activation facilitated this potentiated increase in IL‐1β production. Synergistic pro‐inflammatory responses in THP‐1 cells mediated by β1‐AR subtype coupling to cAMP‐dependent protein kinase A, represents a mechanism by which autonomic outflow could modulate immune function in vivo. Funding: NSF Grant 0235146