title: Enhanced CNS uptake of systemically administered proteins through conjugation with tetanus C-fragment.
abstract: No other exogenous protein enters the central nervous system from the circulation as readily as tetanus toxin. We examined the capability of the non-toxic binding fragment of tetanus toxin (C-Fragment) so serve as a vehicle for transport of other proteins into the mouse CNS. Using periodate oxidation of the enzyme horseradish peroxidase (HRP), we synthesized two separate macromolecular complexes, one containing C-fragment and HRP, and the other C-fragment, HRP and a third "test" protein-human IgG. The distribution of C-fragment-HRP was typical of blood borne proteins including native C-fragment, with labeling of all neurons with known projections outside the blood-brain barrier, particularly large spinal motoneurons. C-fragment-HRP conjugates showed superior neuronal labeling to over 100-fold greater quantities of free HRP. Complexes containing C-fragment, HRP and human IgG were internalized by neurons from both intramuscular and intraperitoneal injections. The efficiency of neuronal uptake of IgG in the C-fragment conjugated form was enhanced over 40-fold compared to free IgG. Linkage of a large protein to C-fragment probably leads to enhanced endocytosis of that protein by neuronal terminals projecting outside the blood-brain barrier. C-fragment can serve as a vehicle to allow selected proteins to bypass the barrier and enter the CNS.
authors.affiliation: Department of Neurology, University of Maryland, School of Medicine, Baltimore 21201.
authors.forename: P S
authors.initials: PS
authors.lastname: Fishman
authors.forename: J M
authors.initials: JM
authors.lastname: Savitt
authors.forename: D A
authors.initials: DA
authors.lastname: Farrand
mesh_terms: D000818:Animals; D001692:Biological Transport; D002490:Central Nervous System / Q000166:cytology / Q000378:metabolism*; D006735:Horseradish Peroxidase / Q000493:pharmacokinetics; D007074:Immunoglobulin G / Q000493:pharmacokinetics; D007273:Injections, Intramuscular; D007274:Injections, Intraperitoneal; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009474:Neurons / Q000378:metabolism; D011506:Proteins / Q000493:pharmacokinetics*; D013744:Tetanus Toxin / Q000737:chemistry / Q000493:pharmacokinetics*
chemical_list: D007074:Immunoglobulin G; D011506:Proteins; D013744:Tetanus Toxin; D006735:Horseradish Peroxidase