Stimulation of liver-directed cholesterol flux in mice by novel N-acetylgalactosamine-terminated glycolipids with high affinity for the asialoglycoprotein receptor.
OBJECTIVE
Interventions that promote liver-directed cholesterol flux can suppress atherosclerosis, as demonstrated for scavenger receptor-BI overexpression in hypercholesterolemic mice. In analogy, we speculate that increasing lipoprotein flux to the liver via the asialoglycoprotein receptor (ASGPr) may be of therapeutic value in hypercholesterolemia.


RESULTS
A bifunctional glycolipid (LCO-Tyr-GalNAc3) with a high-nanomolar affinity for the ASGPr (inhibition constant 2.1+/-0.2 nmol/L) was synthesized that showed rapid association with lipoproteins on incubation with serum. Prior incubation of LCO-Tyr-GalNAc3 with radiolabeled low-density lipoprotein or high-density lipoprotein (0.5 microg/microg of protein) resulted in a dramatic induction of the liver uptake of these lipoproteins when injected intravenously into mice (70+/-3% and 78+/-1%, respectively, of the injected dose at 10 minutes of low-density lipoprotein and high-density lipoprotein), as mediated by the ASGPr on hepatocytes. Intravenously injected LCO-Tyr-GalNAc3 quantitatively incorporated into serum lipoproteins and evoked a strong and persistent (> or =48 hour) cholesterol-lowering effect in normolipidemic mice (37+/-2% at 6 hours) and hyperlipidemic apoE(-/-) mice (32+/-2% at 6 hours). The glycolipid was also effective on subcutaneous administration.


CONCLUSIONS
LCO-Tyr-GalNAc3 is very effective in promoting cholesterol uptake by hepatocytes and, thus, may be a promising alternative for the treatment of those hyperlipidemic patients who do not respond sufficiently to conventional cholesterol-lowering therapies.
Rensen
Patrick C N
PC
Division of Biopharmaceutics, Leiden/Amsterdam Center for Drug Research, University of Leiden, Leiden, The Netherlands. P.C.N.Rensen@lumc.nl
Sliedregt
Leo A J M
LA
van Santbrink
Peter J
PJ
Ferns
Michiel
M
Schifferstein
Hendrik N J
HN
van Leeuwen
Steven H
SH
Souverijn
John H M
JH
van Berkel
Theo J C
TJ
Biessen
Erik A L
EA
D000116:Acetylgalactosamine / Q000031:analogs & derivatives* / Q000138:chemical synthesis; D000818:Animals; D001057:Apolipoproteins E / Q000235:genetics; D037263:Asialoglycoprotein Receptor / Q000378:metabolism*; D050197:Atherosclerosis / Q000188:drug therapy* / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism*; D006017:Glycolipids / Q000138:chemical synthesis / Q000494:pharmacology* / Q000633:toxicity; D006949:Hyperlipidemias / Q000188:drug therapy* / Q000378:metabolism; D008075:Lipoproteins, HDL / Q000097:blood / Q000493:pharmacokinetics; D008077:Lipoproteins, LDL / Q000097:blood / Q000493:pharmacokinetics; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D013154:Spleen / Q000187:drug effects / Q000378:metabolism
D001057:Apolipoproteins E; D037263:Asialoglycoprotein Receptor; D006017:Glycolipids; C507464:LCO-Tyr-GalNAc3; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D002784:Cholesterol; D000116:Acetylgalactosamine