title: Beta2 adrenergic receptor activation stimulates pro-inflammatory cytokine production in macrophages via PKA- and NF-kappaB-independent mechanisms.
abstract: Activation of the beta(2) adrenergic receptor (beta(2)AR) located on macrophages has been reported to possess anti-inflammatory properties, inhibiting nuclear factor kappaB (NF-kappaB) activation and cytokine production induced by pro-inflammatory stimuli. Here, we show that activation of the beta(2)AR in the absence of pro-inflammatory stimuli produced up to an 80- and 8-fold increase in IL-1beta and IL-6 transcripts, respectively, in the RAW 264.7 murine macrophage cell line. This increase in mRNA expression was accompanied by a significant increase in IL-1beta and IL-6 protein production. Pre-treatment of RAW cells with pharmacological inhibitors of protein kinase A (PKA) or NF-kappaB pathway failed to block this cytokine increase. Instead, the beta(2)AR-mediated increase in cytokines required activation of both the B-raf-ERK1/2 and p38 pathways. Treatment of RAW cells with the exchange protein directly activated by cAMP (EPAC) agonist also resulted in the up-regulation of IL-1beta and IL-6 transcripts. Examination of the main transcription factors downstream of the ERK1/2 and p38 signaling revealed that beta(2)AR activation resulted in the stimulation of CRE-, but not C/EBPbeta-, ETS-, or NF-kappaB-dependent transcription. Western blot analysis further showed that among the transcription factors which recognize the CRE-binding site, ATF-1 and ATF-2 but not CREB proteins were phosphorylated in an ERK1/2- and p38-dependent manner. Collectively, these results demonstrate that beta(2)ARs possess pro-inflammatory properties and that their activation leads to IL-1beta and IL-6 production through ERK1/2- and p38-dependent activation of ATF-1 and ATF-2 transcription factors.
authors.affiliation: The Comprehensive Center for Inflammatory Disorders, School of Dentistry, University of North Carolina, Chapel Hill, NC 27599, USA.
authors.forename: Kai Soo
authors.initials: KS
authors.lastname: Tan
authors.forename: Andrea G
authors.initials: AG
authors.lastname: Nackley
authors.forename: Kathryn
authors.initials: K
authors.lastname: Satterfield
authors.forename: William
authors.initials: W
authors.lastname: Maixner
authors.forename: Luda
authors.initials: L
authors.lastname: Diatchenko
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Flood
mesh_terms: D051696:Activating Transcription Factors / Q000378:metabolism; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D016207:Cytokines / Q000378:metabolism; D006801:Humans; D053583:Interleukin-1beta / Q000378:metabolism*; D015850:Interleukin-6 / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D010766:Phosphorylation; D048493:Proto-Oncogene Proteins B-raf / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D051696:Activating Transcription Factors; D000318:Adrenergic beta-Agonists; D016207:Cytokines; D053583:Interleukin-1beta; D015850:Interleukin-6; D016328:NF-kappa B; D012333:RNA, Messenger; D018343:Receptors, Adrenergic, beta-2; D048493:Proto-Oncogene Proteins B-raf; D017868:Cyclic AMP-Dependent Protein Kinases; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases