Symptomatic treatment of botulism with a clinically approved small molecule
Edwin Vazquez-Cintron, James Machamer, Celinia Ondeck, Kathleen Pagarigan, Brittany Winner, Paige Bodner, Kyle Kelly, M. Ross Pennington, Patrick McNutt
Edwin Vazquez-Cintron, James Machamer, Celinia Ondeck, Kathleen Pagarigan, Brittany Winner, Paige Bodner, Kyle Kelly, M. Ross Pennington, Patrick McNutt
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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 3

Multiple-dose administration of 3,4-DAP improves oxygen consumption and survival during terminal stages of BoNT/A-induced respiratory botulism in mice.

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Multiple-dose administration of 3,4-DAP improves oxygen consumption and ...
Mice were intoxicated with 1.5 LD50, 3 LD50, or 5 LD50 BoNT/A, and 3,4-DAP (2 mg/kg) or vehicle was administered at 90-minute intervals, as represented by vertical dashed lines. (A, D, and G) Longitudinal changes in VO2 measured before and after 8 or 15 administrations of vehicle or 3,4-DAP. Horizontal dashed lines represent experimentally determined resting VO2 for purposes of comparison. (B, E, and H) Comparisons of mean peak VO2 measured between 17 and 51 minutes after 3,4-DAP or vehicle administration. Mean peak VO2 values were normalized to resting VO2 values to indicate how effective each treatment of 3,4-DAP was in restoring baseline oxygen consumption. Statistical comparisons were made using 2-way repeated measures ANOVA with Sidak’s multiple comparisons test. **P < 0.01. (C, F, and I) Kaplan-Meier survival curves were compared using log rank tests for significance between 3,4-DAP and vehicle. Vertical dashed lines represent treatment with vehicle or 3,4-DAP. The number of mice in each experimental group is summarized in Table 1.