title: Interactions of lecithinized superoxide dismutase with serum proteins and cells.
abstract: Superoxide dismutase covalently bound to four lecithin molecules (PC-SOD) is known to be retained in circulating blood for a prolonged period and has a high affinity for cells, resulting in beneficial therapeutic effects in animal disease models. In this study, we evaluated the interaction of PC-SOD with biological components, such as serum proteins and cells, to clarify the mechanism underlying the improved pharmacokinetics of SOD induced by lecithin chemical modification (lecithinization). PC-SOD was distributed in the plasma but not in blood cells after being added to the blood. PC-SOD formed a complex with serum protein(s) such as albumin, whereas unmodified SOD did not. The cellular content of PC-SOD was markedly higher than that of unmodified SOD, and was distributed in lysosomes. The pathway associated with the cellular uptake was found to involve clathrin-/caveolae-independent and cholesterol-sensitive endocytosis. Overall, our data indicated that the increased hydrophobicity of lecithinized SOD enhanced its association to both serum protein(s) and plasma membrane microdomains. The former inhibited SOD excretion and promoted long-term retention in circulating blood, whereas the latter enhanced internalization into cells via endocytosis.
authors.affiliation: Department of Chemical Biology and Applied Chemistry College of Engineering, Nihon University, Fukushima, 963-8642, Japan. Electronic address: ishihara@chem.ce.nihon-u.ac.jp.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Ishihara
authors.affiliation: Department of Chemical Biology and Applied Chemistry College of Engineering, Nihon University, Fukushima, 963-8642, Japan.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Nara
authors.affiliation: Department of Analytical Chemistry, Faculty of Pharmacy, Keio University, Tokyo105-8512, Japan.
authors.forename: Tohru
authors.initials: T
authors.lastname: Mizushima
mesh_terms: D000818:Animals; D001798:Blood Proteins / Q000737:chemistry*; D018929:Cell Culture Techniques; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D016503:Drug Delivery Systems; D004591:Electrophoresis, Polyacrylamide Gel; D004705:Endocytosis / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D008297:Male; D021962:Membrane Microdomains / Q000187:drug effects / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000378:metabolism; D051379:Mice; D010713:Phosphatidylcholines / Q000008:administration & dosage / Q000097:blood* / Q000737:chemistry / Q000494:pharmacology; D017208:Rats, Wistar; D013482:Superoxide Dismutase / Q000008:administration & dosage / Q000097:blood* / Q000737:chemistry / Q000494:pharmacology
chemical_list: D001798:Blood Proteins; D026901:Membrane Transport Proteins; D010713:Phosphatidylcholines; D013482:Superoxide Dismutase; C434045:lecithinized superoxide dismutase
keywords: conjugation; drug delivery systems; macromolecular drug delivery; membrane transport; pharmacokinetics; protein delivery; proteins