BTK Mediates Inflammation, Mast Cell Activation, and Urothelial Barrier Disruption in IC/BPS model

Background Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic urinary disorder with unclear pathogenesis. Previous studies identified BTK as a hub gene potentially involved in IC/BPS. This study investigates BTK’s role in mast cell (MC) activation and bladder inflammation. Methods An LL-37-induced IC/BPS rat model and an in vitro MC model were established. BTK expression was modulated via adenoviral vectors and cell transfection. Bladder inflammation, MC degranulation, and urothelial barrier function were assessed using histology, ELISA, RT-qPCR, Western blot, IHC, TEM, and IF. MC function was evaluated via CCK-8, flow cytometry, Transwell, and TEM. Results LL-37 upregulated BTK in IC/BPS rats, promoting inflammation, cytokine release, collagen deposition, MC degranulation, and urothelial damage. BTK overexpression exacerbated, while knockdown alleviated these effects. In vitro, LL-37 stimulated MC proliferation, invasion, and degranulation, and reduced apoptosis. Co-culture with activated MCs decreased glycosaminoglycan (GAG) and tight junction (TJ) proteins in SV-HUC-1 cells, enhanced by BTK overexpression and reversed by knockdown. Conclusions BTK promotes LL-37-induced MC activation and urothelial barrier disruption by suppressing GAGs and TJ proteins, contributing to IC/BPS pathophysiology.