Symptomatic treatment of botulism with a clinically approved small molecule
Edwin Vazquez-Cintron, … , M. Ross Pennington, Patrick McNutt
Edwin Vazquez-Cintron, … , M. Ross Pennington, Patrick McNutt
Published January 30, 2020
Citation Information: JCI Insight. 2020;5(2):e132891. https://doi.org/10.1172/jci.insight.132891.
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Research Article Neuroscience Therapeutics

Symptomatic treatment of botulism with a clinically approved small molecule

Abstract

Botulinum neurotoxins (BoNTs) are potent neuroparalytic toxins that cause mortality through respiratory paralysis. The approved medical countermeasure for BoNT poisoning is infusion of antitoxin immunoglobulins. However, antitoxins have poor therapeutic efficacy in symptomatic patients; thus, there is an urgent need for treatments that reduce the need for artificial ventilation. We report that the US Food and Drug Administration–approved potassium channel blocker 3,4-diaminopyridine (3,4-DAP) reverses respiratory depression and neuromuscular weakness in murine models of acute and chronic botulism. In ex vivo studies, 3,4-DAP restored end-plate potentials and twitch contractions of diaphragms isolated from mice at terminal stages of BoNT serotype A (BoNT/A) botulism. In vivo, human-equivalent doses of 3,4-DAP reversed signs of severe respiratory depression and restored mobility in BoNT/A-intoxicated mice at terminal stages of respiratory collapse. Multiple-dosing administration of 3,4-DAP improved respiration and extended survival at up to 5 LD50 BoNT/A. Finally, 3,4-DAP reduced gastrocnemius muscle paralysis and reversed respiratory depression in sublethal models of serotype A–, B–, and E–induced botulism. These findings make a compelling argument for repurposing 3,4-DAP to symptomatically treat symptoms of muscle paralysis caused by botulism, independent of serotype. Furthermore, they suggest that 3,4-DAP is effective for a range of botulism symptoms at clinically relevant time points.

Authors

Edwin Vazquez-Cintron, James Machamer, Celinia Ondeck, Kathleen Pagarigan, Brittany Winner, Paige Bodner, Kyle Kelly, M. Ross Pennington, Patrick McNutt

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Figure 2

Single administration of 3,4-DAP transiently reverses severe physiological symptoms of botulism.

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Single administration of 3,4-DAP transiently reverses severe physiologic...
Mice were intoxicated with 2 LD50 BoNT/A and administered 3,4-DAP 16–20 hours later, when they presented with severe clinical signs of respiratory depression and neuromuscular weakness (n = 14). (A) Images demonstrating longitudinal changes in physiological appearance following 3,4-DAP treatment. Note transition from generalized muscle weakness and severe abdominal paradox to mice that are erect and ambulatory with reduced abdominal paradox. (B) Effects of 3,4-DAP treatment on respiratory rate (measured as breaths per minute; bpm). (C) Effects of 3,4-DAP treatment on clinical severity scores. (D) Representative trajectories reflecting total mouse mobility in 30-minute bins. Presented times represent the midpoint of each bin. (E) Grouped effects of 3,4-DAP treatment on overall mobility. Mouse mobility was summed across 30-minute bins to match clinical data and normalized to the 30-minute bin prior to 3,4-DAP treatment. Time points represent the start of each bin. For B, C, and E, statistical comparisons were made to mean values collected 30 minutes prior to 3,4-DAP administration using 1-way repeated measures ANOVA with Dunnett’s multiple comparisons test.