Modulation of interleukin-6 by beta2-adrenoceptor in endotoxin-stimulated renal macrophage cells.
BACKGROUND
Activation of the cAMP signaling pathway by means of beta2-adrenoceptor agonists has been shown to up-regulate interleukin-6 (IL-6) gene expression and to stimulate IL-6 production in macrophage cells. However, whether beta2-adrenoceptor activation can also modify the rate of IL-6 production in macrophage cells activated by the bacterial endotoxins has not yet been determined. Using renal resident macrophage cells treated with endotoxin, lipopolysaccharide (LPS), and beta2-adrenoceptor agonist, terbutaline, we investigated the role of cAMP pathway, tumor necrosis factor (TNF)-alpha and mitogen-activated protein kinase (MAPK) pathway (p42/p44) in regulating IL-6 production.


METHODS
IL-6 protein, mRNA, and promoter activity were measured in these cells exposed to LPS (1 microg/ml) and/or terbutaline (10(-9) to 10(-6) M). Furthermore, the time course effects of terbutaline on cAMP, MAPK (p42/p44), and TNF-alpha release were evaluated in the cells.


RESULTS
Terbutaline at high concentrations (10(-6) M) significantly up-regulated IL-6 by approximately 25% (P<0.05), whereas at a lower concentration (10(-8) M), it down-regulated IL-6 production by 42% (P<0.05). Terbutaline (10(-8) and 10(-6) M) caused a concentration- and time-dependent stimulation of cAMP (P<0.05) and TNF production (P<0.05) and a time-dependent decrease in MAPK activity (P<0.05). Following the addition of a cAMP inhibitor, IL-6 promoter activity was correlated with TNF-alpha levels and MAPK activity.


CONCLUSIONS
A biphasic effect of beta2-adrenoceptor agonist on IL-6 production in renal resident macrophage cells became apparent when LPS was exposed to the cells. The terbutaline-induced down-regulation of IL-6 gene production was mediated by an inhibitory effect of terbutaline on TNF-alpha, which was exerted through the MAPK and cAMP pathways, whereas the up-regulation appeared to be due to a direct action of intracellular cAMP.
Nakamura
A
A
Department of Paediatrics, Teikyo University School of Medicine, Tokyo, Japan. akio@med.teikyo-u.ac.jp
Johns
E J
EJ
Imaizumi
A
A
Yanagawa
Y
Y
Kohsaka
T
T
D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000235:genetics*; D007668:Kidney / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000633:toxicity*; D048369:MAP Kinase Kinase 1; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism*; D020929:Mitogen-Activated Protein Kinase Kinases; D011401:Promoter Regions, Genetic / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D018343:Receptors, Adrenergic, beta-2 / Q000187:drug effects* / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013726:Terbutaline / Q000494:pharmacology; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D000318:Adrenergic beta-Agonists; D004791:Enzyme Inhibitors; D005419:Flavonoids; D015850:Interleukin-6; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D018343:Receptors, Adrenergic, beta-2; D014409:Tumor Necrosis Factor-alpha; D000242:Cyclic AMP; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases; D013726:Terbutaline; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one