Abstract
Catecholamines released from the sympathetic nervous system in response to stress or injury affect expression of inflammatory cytokines generated by immune cells. α1-Adrenergic receptors (ARs) are expressed on innate immune cell populations, but their subtype expression patterns and signaling characteristics are not well characterized. Primary human monocytes, a human monocytic cell line, and monocyte-derived macrophage cells were used to measure expression of the proinflammatory mediator interleukin (IL)-1β responding to lipopolysaccharide (LPS) in the presence or absence of α1-AR activation. Based on our previous findings, we hypothesized that α1-AR stimulation on innate immune cells positively regulates LPS-initiated IL-1β production. IL-1β production in response to LPS was synergistically higher for both monocytes and macrophages in the presence of the selective α1-AR agonist (R)-(−)-phenylephrine hydrochloride (PE). This synergistic IL-1β response could be blocked with a selective α1-AR antagonist as well as inhibitors of protein kinase C (PKC). Radioligand binding studies characterized a homogenous α1B-AR subtype population on monocytes, which changed to a heterogeneous receptor subtype expression pattern when differentiated to macrophages. Furthermore, increased p38 mitogen-activated protein kinase (MAPK) activation was observed only with concurrent PE and LPS stimulation, peaking after 120 and 30 min in monocytes and macrophages, respectively. Blocking the PKC/p38 MAPK signaling pathway in both innate immune cell types inhibited the synergistic IL-1β increase observed with concurrent PE and LPS treatments. This study characterizes α1-AR subtype expression on both human monocyte and macrophage cells and illustrates a mechanism by which increased IL-1β production can be modulated by α1-AR input.
Footnotes
This study was supported by the National Science Foundation [Grant 0235146]; the National Institutes of Health National Institute of General Medical Sciences [Grant GM066726]; the National Institutes of Health National Institute of Diabetes and Digestive and Kidney Diseases [Grant DK62865]; the National Institutes of Health Centers of Biomedical Research Excellence program [Grant RR016471]; and the North Dakota Experimental Program to Stimulate Competitive Research program through the National Science Foundation [Grant EPS-0447679] (to J.E.P). The Integrative and Organ Systems Pharmacology internship of L.A.G. at the University of Nebraska Medical Center was supported by the National Institutes of Health National Institute of General Medical Sciences [Grant R25-GM074089].
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
doi:10.1124/jpet.110.178012.
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ABBREVIATIONS:
- AR
- adrenergic receptor
- BE 2254
- 2-{[β-(hydroxyphenyl)ethyl]aminomethyl}-1-tetralone hydrochloride
- Bis II
- bisindolylmaleimide II
- BMY 7378
- 8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4.5]decane-7,9-dione dihydrochloride
- DN
- dominant-negative
- ELISA
- enzyme-linked immunosorbent assay
- ERK
- extracellular signal-regulated kinase
- 125I-HEAT
- (±)-β-([125]Iodo-4-hydroxyphenyl)-ethyl-aminomethyl-tetralone
- HEM buffer
- 20 mM HEPES, 1.4 mM EGTA, 12.5 mM MgCl2, pH 7.4
- IL
- interleukin
- JNK
- c-Jun N-terminal kinase
- Kd
- radioligand equilibrium dissociation constant
- Ki
- competitive receptor antagonist equilibrium dissociation constant
- LPS
- lipopolysaccharide
- MAPK
- mitogen-activated protein kinase
- 5-MU
- 5-methylurapidil
- NF-κB
- nuclear factor κ-light-chain-enhancer of activated B cells
- PE
- (R)-(−)-phenylephrine hydrochloride
- PKC
- protein kinase C
- PMA
- phorbol 12-myristate 13-acetate
- SB 203580
- 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)-1H-imidazole
- STS
- staurosporine
- THP-1
- human monocyte cell line
- TLR
- Toll-like receptor
- WB-4101
- 2-[(2,6-dimethoxyphenoxyethyl)aminomethyl]-1,4-benzodioxane hydrochloride.
- Received December 8, 2010.
- Accepted May 12, 2011.
- Copyright © 2011 by The American Society for Pharmacology and Experimental Therapeutics
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