title: Distribution and functional activity of P-glycoprotein and multidrug resistance-associated proteins in human brain microvascular endothelial cells in hippocampal sclerosis.
abstract: Multidrug resistance protein, also referred as P-glycoprotein (P-gp, MDR1; ABCB1) and multidrug resistance-associated protein (MRP) 1 (ABCC1) and 2 (ABCC2) are, thus far, candidates to cause antiepileptic drug (AED) resistance epilepsy. In this study, we investigated P-gp, MRP1 and MRP2 expression, localization and functional activity on cryosections and isolated human brain-derived microvascular endothelial cells (HBMEC) from epileptic patients (HBMEC-EPI) with hippocampal sclerosis (HS), as compared with HBMEC isolated from normal brain cortex (HBMEC-CTR). We examined the expression and distribution of three transporters, P-gp, MRP1 and MRP2 on two major parts of the resected tissue, the hippocampus and the parahippocampal gyrus (Gph). P-gp showed diffuse expression not only in endothelium but also by parenchymal cells in both the hippocampus and the Gph. MRP1 labeling was observed in parenchymal cells in the Gph. By contrast, MRP2 was mainly found in endothelium of the hippocampus. P-gp and MRP1 expression in the Gph was relatively high in the patient with long-term seizure history. Quantitative RT-PCR analysis of HBMEC revealed that MDR1, MRP1 as well as MRP5 (ABCC5) and MRP6 (ABCC6) were overexpressed in HBMEC-EPI at the mRNA level. HBMEC from both normal and epilepsy groups displayed protein expression of P-gp, whereas MRP1 and MRP2 were seen only in HBMEC-EPI. Accordingly, it is of particular interest that MRP functional activities were observed in HBMEC-EPI, but not in HBMEC-CTR. Our results suggest that complex MDR expression changes not only in the hippocampus but in the Gph may play a role in AED pharmacoresistance in intractable epilepsy patients with mesial temporal lobe epilepsy (MTLE) by altering the permeability of AEDs across the blood-brain barrier (BBB).
authors.affiliation: Department of Neurosurgery, University Hospital Zurich, Frauenklinikstr. 10, CH-8091 Zurich, Switzerland.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Kubota
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Ishihara
authors.forename: Thomas
authors.initials: T
authors.lastname: Langmann
authors.forename: Gerd
authors.initials: G
authors.lastname: Schmitz
authors.forename: Bruno
authors.initials: B
authors.lastname: Stieger
authors.forename: Heinz-Gregor
authors.initials: HG
authors.lastname: Wieser
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Yonekawa
authors.forename: Karl
authors.initials: K
authors.lastname: Frei
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D000293:Adolescent; D000328:Adult; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D002648:Child; D018432:Drug Resistance, Multiple / Q000502:physiology*; D042783:Endothelial Cells / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D004833:Epilepsy, Temporal Lobe / Q000378:metabolism* / Q000601:surgery; D005260:Female; D006624:Hippocampus / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000378:metabolism*; D012333:RNA, Messenger; D012598:Sclerosis
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D012333:RNA, Messenger; C000715087:ABCC2 protein, human