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Original Article |
Correspondence to: Lydia M. Sorokin, Interdisciplinary Center for Clinical Research (IZKF), Nikolaus Fiebiger Center for Molecular Medicine, Glückstr. 6, 91054 Erlangen, Germany. Tel:(49) 9131-853-9301 Fax:(49) 9131-853-9311 E-mail:lsorokin{at}molmed.uni-erlangen.de.
An active involvement of bloodbrain barrier endothelial cell basement membranes in development of inflammatory lesions in the central nervous system (CNS) has not been considered to date. Here we investigated the molecular composition and possible function of the extracellular matrix encountered by extravasating T lymphocytes during experimental autoimmune encephalomyelitis (EAE).
Endothelial basement membranes contained laminin 8 (
4ß1
1) and/or 10 (
5ß1
1) and their expression was influenced by proinflammatory cytokines or angiostatic agents. T cells emigrating into the CNS during EAE encountered two biochemically distinct basement membranes, the endothelial (containing laminins 8 and 10) and the parenchymal (containing laminins 1 and 2) basement membranes. However, inflammatory cuffs occurred exclusively around endothelial basement membranes containing laminin 8, whereas in the presence of laminin 10 no infiltration was detectable. In vitro assays using encephalitogenic T cell lines revealed adhesion to laminins 8 and 10, whereas binding to laminins 1 and 2 could not be induced. Downregulation of integrin
6 on cerebral endothelium at sites of T cell infiltration, plus a high turnover of laminin 8 at these sites, suggested two possible roles for laminin 8 in the endothelial basement membrane: one at the level of the endothelial cells resulting in reduced adhesion and, thereby, increased penetrability of the monolayer; and secondly at the level of the T cells providing direct signals to the transmigrating cells.
Key Words: laminin, experimental autoimmune encephalomyelitis, endothelium, basement membranes, inflammation
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