title: Transport of arylsulfatase A across the blood-brain barrier in vitro.
abstract: Enzyme replacement therapy is an option to treat lysosomal storage diseases caused by functional deficiencies of lysosomal hydrolases as intravenous injection of therapeutic enzymes can correct the catabolic defect within many organ systems. However, beneficial effects on central nervous system manifestations are very limited because the blood-brain barrier (BBB) prevents the transfer of enzyme from the circulation to the brain parenchyma. Preclinical studies in mouse models of metachromatic leukodystrophy, however, showed that arylsulfatase A (ASA) is able to cross the BBB to some extent, thus reducing lysosomal storage in brain microglial cells. The present study aims to investigate the routing of ASA across the BBB and to improve the transfer in vitro using a well established cell culture model consisting of primary porcine brain capillary endothelial cells cultured on Transwell filter inserts. Passive apical-to-basolateral ASA transfer was observed, which was not saturable up to high ASA concentrations. No active transport could be determined. The passive transendothelial transfer was, however, charge-dependent as reduced concentrations of negatively charged monosaccharides in the N-glycans of ASA or the addition of polycations increased basolateral ASA levels. Adsorptive transcytosis is therefore considered to be the major transport pathway. Partial inhibition of the transcellular ASA transfer by mannose 6-phosphate indicated a second route depending on the insulin-like growth factor II/mannose 6-phosphate receptor, MPR300. We conclude that cationization of ASA and an increase of the mannose 6-phosphate content of the enzyme may promote blood-to-brain transfer of ASA, thus leading to an improved therapeutic efficacy of enzyme replacement therapy behind the BBB.
authors: Rheinische Friedrich-Wilhelms Universität, Institut für Biochemie und Molekularbiologie, D-53115 Bonn, Germany.
authors: Frank
authors: F
authors: Matthes
authors: Philipp
authors: P
authors: Wölte
authors: Annika
authors: A
authors: Böckenhoff
authors: Sabine
authors: S
authors: Hüwel
authors: Mareike
authors: M
authors: Schulz
authors: Pia
authors: P
authors: Hyden
authors: Jens
authors: J
authors: Fogh
authors: Volkmar
authors: V
authors: Gieselmann
authors: Hans-Joachim
authors: HJ
authors: Galla
authors: Ulrich
authors: U
authors: Matzner
mesh_terms: D000818:Animals; D001812:Blood-Brain Barrier / Q000378:metabolism* / Q000473:pathology; D002412:Cations / Q000378:metabolism; D002553:Cerebroside-Sulfatase / Q000378:metabolism* / Q000627:therapeutic use; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000378:metabolism* / Q000473:pathology; D056947:Enzyme Replacement Therapy / Q000379:methods; D006801:Humans; D007966:Leukodystrophy, Metachromatic / Q000188:drug therapy / Q000201:enzymology; D008360:Mannosephosphates / Q000378:metabolism*; D051379:Mice; D021381:Protein Transport / Q000187:drug effects; D013552:Swine
chemical_list: D002412:Cations; D008360:Mannosephosphates; C027693:mannose-6-phosphate; D002553:Cerebroside-Sulfatase