Anti-inflammatory effects of botulinum toxin type A in a rat model of arthritis / 中华物理医学与康复杂志

ABSTRACT

Objective To verify the anti-inflammatory effects of intra-articular injection of botulinum toxin type A (BoNT/A) on adjuvant-induced arthritis using a rat model.Methods A murine model of chronic ankle arthritis was established in 90 Wistar rats by injection of 0.1 ml of complete Freund adjuvant (CFA) into the pads of their left paws.They were then randomly divided into a BoNT group (n =30) which received an intra-articular injection of 0.1 ml (20 IU) of BoNT/A,an NS group (n=30) which received intra-articular injection of0.1 ml of normal saline solution and a sham group (n =30) which were punctured without any injection.In addition,30 normal rats formed a control group.Infrared thermal imaging was performed and an index of arthritis was evaluated every three days.The infrared thermal imaging revealed the expression of interleukin-1β (IL-1β) through hematoxy-eosin (HE) staining.Results The arthritis index began to increase 3 days after the injection of CFA and it had increased significantly after 10 days,reaching a peak value of 18,24 days after the injection.The infrared thermal imaging showed that the temperature in the right paw increased greatly after the injection.Following the development of arthritis,the temperature declined gradually,arriving at a steady temperature of between 37.5 and 38.0 ℃ in both ankles 20 days after the injection.The average temperature in both paws of the BoNT group had decreased significantly more by 7 and 14 days after the injection than in the NS and sham groups.The expression of IL-1β in the synovium of the ankle joint also had decreased significantly more in the BoNT group after 7 and 14 days.HE scoring showed an obvious histopathologic change in the hypertrophic synovium,inflamnatory cell infiltration,cartilage destruction and exposure of subchondral bone after 7 and 14 days compared with right after the injection in all groups except the control group.Moreover,the average HE scores of the BoNT group rats after 7 and 14 days were significantly lower than those seen in the NS and sham groups at the same time points.Conclusion Intra-articular injection of botulinum toxin type A has an anti-inflammatory effect on arthritis induced by complete Freund adjuvant,at least in rats.