An efficient drug delivery vehicle for botulism countermeasure.
BACKGROUND
Botulinum neurotoxin (BoNT) is the most potent poison known to mankind. Currently no antidote is available to rescue poisoned synapses. An effective medical countermeasure strategy would require developing a drug that could rescue poisoned neuromuscular synapses and include its efficient delivery specifically to poisoned presynaptic nerve terminals. Here we report a drug delivery strategy that could directly deliver toxin inhibitors into the intoxicated nerve terminal cytosol.


RESULTS
A targeted delivery vehicle was developed for intracellular transport of emerging botulinum neurotoxin antagonists. The drug delivery vehicle consisted of the non-toxic recombinant heavy chain of botulinum neurotoxin-A coupled to a 10-kDa amino dextran via the heterobifunctional linker 3-(2-pyridylthio)-propionyl hydrazide. The heavy chain served to target botulinum neurotoxin-sensitive cells and promote internalization of the complex, while the dextran served as a platform to deliver model therapeutic molecules to the targeted neurons. Our results indicated that the drug delivery vehicle entry into neurons was via BoNT-A receptor mediated endocytosis. Once internalized into neurons, the drug carrier component separated from the drug delivery vehicle in a fashion similar to the separation of the BoNT-A light chain from the holotoxin. This drug delivery vehicle could be used to deliver BoNT-A antidotes into BoNT-A intoxicated cultured mouse spinal cord cells.


CONCLUSIONS
An effective BoNT-based drug delivery vehicle can be used to directly deliver toxin inhibitors into intoxicated nerve terminal cytosol. This approach can potentially be utilized for targeted drug delivery to treat other neuronal and neuromuscular disorders. This report also provides new knowledge of endocytosis and exocytosis as well as of BoNT trafficking.
Division of Experimental Therapeutic, Walter Reed Army Institute of Research, Silver Spring, Maryland, USA. peng.zhang3@us.army.mil
Peng
P
Zhang
Radharaman
R
Ray
Bal Ram
BR
Singh
Dan
D
Li
Michael
M
Adler
Prabhati
P
Ray
D000818:Animals; D019274:Botulinum Toxins, Type A / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000737:chemistry; D001906:Botulism / Q000188:drug therapy / Q000378:metabolism; D002478:Cells, Cultured; D003911:Dextrans / Q000008:administration & dosage / Q000737:chemistry; D016503:Drug Delivery Systems / Q000379:methods*; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology; D005260:Female; D051379:Mice; D008810:Mice, Inbred C57BL; D011247:Pregnancy; D017729:Presynaptic Terminals / Q000187:drug effects / Q000378:metabolism; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000138:chemical synthesis / Q000627:therapeutic use
D003911:Dextrans; D011994:Recombinant Proteins; D019274:Botulinum Toxins, Type A