Presence of cleaved synaptosomal-associated protein-25 and decrease of purinergic receptors p2x3 in the bladder urothelium influence efficacy of botulinum toxin treatment for overactive bladder syndrome

Abstract

Objectives To evaluate whether botulinum toxin A (BoNT-A) injection and Lipotoxin (liposomes with 200 U of BoNT-A) instillation target different proteins, including P2X3, synaptic vesicle glycoprotein 2A, and SNAP-25, in the bladder mucosa, leading to different treatment outcomes. Materials and Methods This was a retrospective study performed in a tertiary teaching hospital. We evaluated the clinical results of 27 OAB patients treated with intravesical BoNT-A injection (n = 16) or Lipotoxin instillation (n = 11). Seven controls were treated with saline. Patients were injected with 100 U of BoNT-A or Lipotoxinin a single intravesical instillation. The patients enrolled in this study all had bladder biopsies performed at baseline and one month after BoNT-A therapy. Treatment outcome was measured by the decreases in urgency and frequency episodes at 1 month. The functional protein expressions in the urothelium were measured at baseline and after 1 month. The Wilcoxon signed-rank test and ordinal logistic regression were used to compare the treatment outcomes. Results Both BoNT-A injection and Lipotoxin instillation treatments effectively decreased the frequency of urgency episodes in OAB patients. Lipotoxin instillation did not increase postvoid residual volume. BoNT-A injection effectively cleaved SNAP-25 (p < 0.01). Liposomeencapsulated BoNT-A decreased urothelial P2X3 expression in the five responders (p = 0.04). while SNAP-25 was not significantly cleaved. Conclusions The results of this study provide a possible mechanism for the therapeutic effects of BoNTA for the treatment of OAB via different treatment forms. BoNT-A and Lipotoxin treatments effectively decreased the frequency of urgency episodes in patients with OAB.