title: Specific targeting of high density lipoproteins to liver hepatocytes by incorporation of a tris-galactoside-terminated cholesterol derivative.
abstract: A triantennary galactose-terminated cholesterol derivative, N-(tris(beta-D-galactopyranosyloxymethyl) methyl)-N alpha-(4(5-cholesten-3 beta-yloxy)succinyl)glycinamide (Tris-Gal-Chol), which dissolves easily in water, was added to human apolipoprotein E-free high density lipoproteins (HDL) in varying quantities. Incorporation of 5 or 13 micrograms of Tris-Gal-Chol into HDL (20 micrograms of protein) stimulates the liver association of the HDL apoprotein radioactivity 24- and 55-fold, respectively, at 10 min after intravenous injection into rats. The increased interaction of Tris-Gal-Chol HDL with the liver is blocked by preinjection of asialofetuin or N-acetylgalactosamine but not influenced by N-acetylglucosamine. The parenchymal liver cell uptake of HDL is stimulated 42- or 105-fold, respectively, by incorporation of 5 or 13 micrograms of Tris-Gal-Chol into HDL (20 micrograms of protein), while the association with nonparenchymal cells is stimulated only 1.7- or 5-fold. It can be calculated that 98.0% of the Tris-Gal-Chol HDL is associated with parenchymal cells. In contrast, incorporation of 13 micrograms of Tris-Gal-Chol into LDL (20 micrograms of protein) leads to a selective association of LDL with nonparenchymal cells (92.3% of the total liver uptake). It is concluded that Tris-Gal-Chol incorporation into HDL leads to a specific interaction of HDL with the asialoglycoprotein (galactose) receptor on parenchymal cells whereas Tris-Gal-Chol incorporation into LDL leads mainly to an interaction with a galactose receptor from Kupffer cells. Probably this highly selective cellular targeting of LDL and HDL by Tris-Gal-Chol is caused by the difference in size between these lipoproteins. The increased interaction of HDL with the parenchymal cells upon Tris-Gal-Chol incorporation is followed by degradation of the apolipoprotein in the lysosomes. It is concluded that Tris-Gal-Chol incorporation into LDL or HDL leads to a markedly increased catabolism of LDL by way of the Kupffer cells and HDL by parenchymal cells which might be used for lowering serum cholesterol levels. The use of Tris-Gal-Chol might also find application for targeting drugs or other compounds of interest to either Kupffer or parenchymal liver cells.
mesh_terms: D000818:Animals; D002738:Chloroquine / Q000494:pharmacology; D002788:Cholesterol Esters / Q000378:metabolism* / Q000494:pharmacology; D004727:Endothelium / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D007728:Kupffer Cells / Q000378:metabolism; D007976:Leupeptins / Q000494:pharmacology; D008075:Lipoproteins, HDL / Q000378:metabolism*; D008077:Lipoproteins, LDL / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011973:Receptors, LDL / Q000187:drug effects / Q000378:metabolism*
chemical_list: D002788:Cholesterol Esters; D007976:Leupeptins; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D011973:Receptors, LDL; D002738:Chloroquine; C042924:N-(tris((beta-galactopyranosyloxy)methyl)methyl)-N(alpha)-(4-(5-cholesten-3 beta-yloxy)succinyl)glycinamide; C032854:leupeptin