title: Inhibitory effects of benzodiazepines on the adenosine A(2B) receptor mediated secretion of interleukin-8 in human mast cells.
abstract: The activation of adenosine A(2B) receptors in human mast cells causes pro-inflammatory responses such as the secretion of interleukin-8. There is evidence for an inhibitory effect of benzodiazepines on mast cell mediated symptoms in patients with systemic mast cell activation disease. Therefore, we investigated the effects of benzodiazepines on adenosine A(2B) receptor mediated interleukin-8 production in human mast cell leukaemia (HMC1) cells by an enzyme linked immunosorbent assay. The adenosine analogue N-ethylcarboxamidoadenosine (NECA, 0.3-3 μM) increased interleukin-8 production about 5-fold above baseline. This effect was attenuated by the adenosine A(2B) receptor antagonist MRS1754 (N-(4-cyanophenyl)-2-{4-(2,3,6,7-tetrahydro-2,6-dioxo-1,3-dipropyl-1H-purin-8-yl)phenoxy}-acetamide) 1 μM. In addition, diazepam, 4'-chlorodiazepam and flunitrazepam (1-30 μM) markedly reduced NECA-induced interleukin-8 production in that order of potency, whereas clonazepam showed only a modest inhibition. The inhibitory effect of diazepam was not altered by flumazenil 10 μM or PK11195 (1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinolinecarboxamide) 10 μM. Diazepam attenuated the NECA-induced expression of mRNA encoding for interleukin-8. Moreover, diazepam and flunitrazepam reduced the increasing effects of NECA on cAMP-response element- and nuclear factor of activated t-cells-driven luciferase reporter gene activities in HMC1 cells. Neither diazepam nor flunitrazepam affected NECA-induced increases in cellular cAMP levels in CHO Flp-In cells stably expressing recombinant human adenosine A(2B) receptors, excluding a direct action of benzodiazepines on human adenosine A(2B) receptors. In conclusion, this is the first study showing an inhibitory action of benzodiazepines on adenosine A(2B) receptor mediated interleukin-8 production in human mast (HMC1) cells. The rank order of potency indicates the involvement of an atypical benzodiazepine binding site.
authors.affiliation: Pharma Center Bonn, Department of Pharmacology and Toxicology, Biomedical Research Center, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany.
authors.forename: Kristina
authors.initials: K
authors.lastname: Hoffmann
authors.forename: Rosa Altarcheh
authors.initials: RA
authors.lastname: Xifró
authors.forename: Julia Lisa
authors.initials: JL
authors.lastname: Hartweg
authors.forename: Petra
authors.initials: P
authors.lastname: Spitzlei
authors.forename: Kirsten
authors.initials: K
authors.lastname: Meis
authors.forename: Gerhard J
authors.initials: GJ
authors.lastname: Molderings
authors.forename: Ivar
authors.initials: I
authors.lastname: von Kügelgen
mesh_terms: D000818:Animals; D001569:Benzodiazepines / Q000378:metabolism / Q000494:pharmacology*; D001665:Binding Sites; D016466:CHO Cells; D045744:Cell Line, Tumor; D006224:Cricetinae; D003412:Cricetulus; D000242:Cyclic AMP / Q000096:biosynthesis; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism*; D008407:Mast Cells / Q000187:drug effects* / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D043704:Receptor, Adenosine A2B / Q000378:metabolism*
chemical_list: D016209:Interleukin-8; D012333:RNA, Messenger; D043704:Receptor, Adenosine A2B; D001569:Benzodiazepines; D000242:Cyclic AMP