title: The role of mannosylated enzyme and the mannose receptor in enzyme replacement therapy.
abstract: Lysosomal acid lipase (LAL) is the critical enzyme for the hydrolysis of triglycerides (TGs) and cholesteryl esters (CEs) in lysosomes. LAL defects cause Wolman disease (WD) and CE storage disease (CESD). An LAL null (lal-/-) mouse model closely mimics human WD/CESD, with hepatocellular, Kupffer cell and other macrophage, and adrenal cortical storage of CEs and TGs. The effect on the cellular targeting of high-mannose and complex oligosaccharide-type oligosaccharide chains was tested with human LAL expressed in Pichia pastoris (phLAL) and CHO cells (chLAL), respectively. Only chLAL was internalized by cultured fibroblasts, whereas both chLAL and phLAL were taken up by macrophage mannose receptor (MMR)-positive J774E cells. After intraperitoneal injection into lal-/- mice, phLAL and chLAL distributed to macrophages and macrophage-derived cells of various organs. chLAL was also detected in hepatocytes. Ten injections of either enzyme over 30 d into 2- and 2.5-mo-old lal-/- mice produced normalization of hepatic color, decreased liver weight (50%-58%), and diminished hepatic cholesterol and TG storage. Lipid accumulations in macrophages were diminished with either enzyme. Only chLAL cleared lipids in hepatocytes. Mice double homozygous for the LAL and MMR deficiences (lal-/-;MMR-/-) showed phLAL uptake into Kupffer cells and hepatocytes, reversal of macrophage histopathology and lipid storage in all tissues, and clearance of hepatocytes. These results implicate MMR-independent and mannose 6-phosphate receptor-independent pathways in phLAL uptake and delivery to lysosomes in vivo. In addition, these studies show specific cellular targeting and physiologic effects of differentially oligosaccharide-modified human LALs mediated by MMR and that lysosomal targeting of mannose-terminated glycoproteins occurs and storage can be eliminated effectively without MMR.
authors.affiliation: Division and Program in Human Genetics, Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229-3039, USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Du
authors.forename: Mark
authors.initials: M
authors.lastname: Levine
authors.forename: Chandrashekar
authors.initials: C
authors.lastname: Ganesa
authors.forename: David P
authors.initials: DP
authors.lastname: Witte
authors.forename: Edward S
authors.initials: ES
authors.lastname: Cole
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Grabowski
mesh_terms: D000818:Animals; D016466:CHO Cells; D002478:Cells, Cultured; D015217:Cholesterol Ester Storage Disease / Q000097:blood / Q000188:drug therapy* / Q000209:etiology / Q000473:pathology; D002788:Cholesterol Esters / Q000097:blood / Q000378:metabolism; D006224:Cricetinae; D003433:Crosses, Genetic; D004195:Disease Models, Animal; D005347:Fibroblasts / Q000378:metabolism; D022781:Hepatocytes / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007274:Injections, Intraperitoneal; D007728:Kupffer Cells / Q000378:metabolism; D037181:Lectins, C-Type / Q000378:metabolism*; D008049:Lipase / Q000008:administration & dosage / Q000097:blood / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use*; D008247:Lysosomes / Q000201:enzymology / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D009929:Organ Size / Q000187:drug effects; D010843:Pichia / Q000235:genetics; D011956:Receptors, Cell Surface / Q000378:metabolism*; D014018:Tissue Distribution; D014280:Triglycerides / Q000097:blood / Q000378:metabolism; D015223:Wolman Disease / Q000097:blood / Q000188:drug therapy* / Q000209:etiology / Q000473:pathology
chemical_list: D002788:Cholesterol Esters; D037181:Lectins, C-Type; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D011956:Receptors, Cell Surface; D014280:Triglycerides; D008049:Lipase