Post-intoxication inhibition of botulinum neurotoxin serotype A within neurons by small-molecule, non-peptidic inhibitors

• Published in: Toxins 2011-03, Vol.3 (3), p.207-217
• Main Authors: Ruthel, Gordon, Burnett, James C, Nuss, Jonathan E, Wanner, Laura M, Tressler, Lyal E, Torres-Melendez, Edna, Sandwick, Sarah J, Retterer, Cary J, Bavari, Sina
• Format: Article
• Language: English
• Subjects: Acidification; Aconitine - administration & dosage; Aconitine - analogs & derivatives; Aconitine - chemistry; Aconitine - pharmacology; Animals; Bafilomycin A1; Blotting, Western; botulinum neurotoxin; Botulinum Toxins, Type A - antagonists & inhibitors; Cell Culture Techniques; Cells, Cultured; Chick Embryo; Cytosol - drug effects; Cytosol - metabolism; Imidazoles - administration & dosage; Imidazoles - chemistry; Imidazoles - pharmacology; Macrolides - administration & dosage; Macrolides - pharmacology; Molecular Structure; Motor Neurons - drug effects; Motor Neurons - metabolism; Neurotoxins; neutralizing antibody; Phthalimides - administration & dosage; Phthalimides - chemistry; Phthalimides - pharmacology; Small Molecule Libraries - administration & dosage; Small Molecule Libraries - chemistry; Small Molecule Libraries - pharmacology; small molecule non-peptidic inhibitor; Spinal Cord - cytology; Spinal Cord - embryology; Spinal Cord - metabolism; Synaptosomal-Associated Protein 25 - metabolism; Synaptosomes - drug effects; Synaptosomes - metabolism
• ISSN: 2072-6651; 2072-6651
• DOI: 10.3390/toxins3030207

Botulinum neurotoxins (BoNTs) comprise seven distinct serotypes that inhibit the release of neurotransmitter across neuromuscular junctions, resulting in potentially fatal flaccid paralysis. BoNT serotype A (BoNT/A), which targets synaptosomal-associated protein of 25kDa (SNAP-25), is particularly long-lived within neurons and requires a longer time for recovery of neuromuscular function. There are currently no treatments available to counteract BoNT/A after it has entered the neuronal cytosol. In this study, we examined the ability of small molecule non-peptidic inhibitors (SMNPIs) to prevent SNAP-25 cleavage post-intoxication of neurons. The progressive cleavage of SNAP-25 observed over 5 h following 1 h BoNT/A intoxication was prevented by addition of SMNPIs. In contrast, anti-BoNT/A neutralizing antibodies that strongly inhibited SNAP-25 cleavage when added during intoxication were completely ineffective when added post-intoxication. Although Bafilomycin A1, which blocks entry of BoNT/A into the cytosol by preventing endosomal acidification, inhibited SNAP-25 cleavage post-intoxication, the degree of inhibition was significantly reduced versus addition both during and after intoxication. Post-intoxication application of SMNPIs, on the other hand, was nearly as effective as application both during and after intoxication. Taken together, the results indicate that competitive SMNPIs of BoNT/A light chain can be effective within neurons post-intoxication.