Botulinum neurotoxin A alleviates Deinagkistrodon acutus venom-induced limb injury through promoting macrophage polarization in rabbits.

OBJECTIVE

Envenomation by Deinagkistrodon acutus (D. acutus) often results in severe limb damage, but therapeutic strategies to counteract the damage are limited. Botulinum neurotoxin A (BoNT/A) has shown protective effects in various models of tissue damage. The present study employed a rabbit model of D. acutus-induced limb damage to investigate the potential therapeutic use and underlying mechanisms of BoNT/A.

METHODS

Twenty-two New Zealand white rabbits were randomly assigned to three groups: Sham (S, n = 6), Snake Venom (SV, n = 8), and Snake Venom plus BoNT/A (SV + BoNT/A, n = 8). D. acutus venom was injected intramuscularly into the left thigh to cause limb injury. Antivenom (80 U/kg) was given intravenously 2 h later. In the SV + BoNT/A group, BoNT/A was injected subcutaneously around the venom injection site immediately after modeling. The myoglobin, serum creatine kinase, and limb circumference were monitored. After 24 h, muscle tissue near the injection site was collected for histological evaluation, assessment of apoptosis (cleaved caspase-3), analysis of TNF-α, IL-6, and IL-10, and examination of macrophage polarization markers.

RESULTS

Both SV and SV + BoNT/A groups displayed significant increases in limb swelling, inflammatory cytokines, apoptosis, histological damage, macrophage polarization in comparison to the Sham group. Treatment with BoNT/A reduced pro-inflammatory cytokines (TNF-α, IL-6) while increasing IL-10 (P < 0.05). Moreover, BoNT/A decreased the proportion of CD86+ and iNOS + cells (M1 phenotype) while increasing the proportion of CD206+ and Arg1+ cells (M2 phenotype).

CONCLUSION

BoNT/A alleviates D. acutus -induced limb injury in rabbits potentially through promoting macrophage polarization.