title: Cyclosporin A induces hyperpermeability of the blood-brain barrier by inhibiting autocrine adrenomedullin-mediated up-regulation of endothelial barrier function.
abstract: Cyclosporin A, a potent immunosuppressant, can often produce neurotoxicity in patients, although its penetration into the brain is restricted by the blood-brain barrier (BBB). Brain pericytes and astrocytes, which are periendothelial accessory structures of the BBB, can be involved in cyclosporin A-induced BBB disruption. However, the mechanism by which cyclosporin A causes BBB dysfunction remains unknown. Here, we show that in rodent brain endothelial cells, cyclosporin A decreased transendothelial electrical resistance (TEER) by inhibiting intracellular signal transduction downstream of adrenomedullin, an autocrine regulator of BBB function. Cyclosporin A stimulated adrenomedullin release from brain endothelial cells, but did not affect binding of adrenomedullin to its receptors. This cyclosporin A-induced decrease in TEER was attenuated by exogenous addition of adrenomedullin. Cyclosporin A dose-dependently decreased the total cAMP concentration in brain endothelial cells. A combination of cyclosporin A (1microM) with an adenylyl cyclase inhibitor, 9-(tetrahydro-2-furanyl)-9H-purin-6-amine (SQ22536; 10microM), or a protein kinase A (PKA) inhibitor, N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide dihydrochloride (H89; 1microM), markedly increased sodium fluorescein permeability in brain endothelial cells, whereas each drug alone had no effect. Thus, these data suggest that cyclosporin A inhibits the adenylyl cyclase/cyclic AMP/PKA signaling pathway activated by adrenomedullin, leading to impairment of brain endothelial barrier function.
authors.affiliation: Department of Pharmaceutical Care and Health Sciences, Faculty of Pharmaceutical Sciences, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Dohgu
authors.forename: Noriko
authors.initials: N
authors.lastname: Sumi
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Nishioku
authors.forename: Fuyuko
authors.initials: F
authors.lastname: Takata
authors.forename: Takuya
authors.initials: T
authors.lastname: Watanabe
authors.forename: Mikihiko
authors.initials: M
authors.lastname: Naito
authors.forename: Hideki
authors.initials: H
authors.lastname: Shuto
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yamauchi
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Kataoka
mesh_terms: D000262:Adenylyl Cyclases / Q000187:drug effects / Q000378:metabolism; D053607:Adrenomedullin / Q000008:administration & dosage / Q000378:metabolism; D000818:Animals; D019898:Autocrine Communication; D001812:Blood-Brain Barrier / Q000187:drug effects* / Q000378:metabolism; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D016572:Cyclosporine / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D017097:Electric Impedance; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D007166:Immunosuppressive Agents / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000633:toxicity*; D051379:Mice; D008807:Mice, Inbred BALB C; D010539:Permeability; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D007166:Immunosuppressive Agents; D053607:Adrenomedullin; D016572:Cyclosporine; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D000262:Adenylyl Cyclases