Differences in mast cell infiltration, E-cadherin, and zonula occludens-1 expression between patients with overactive bladder and interstitial cystitis/bladder pain syndrome

Abstract

Objective: To investigate the difference of infiltration of mast cells and the distribution of protein involved in the urothelial barrier function between patients with overactive bladder syndrome (OAB) and interstitial cystitis/bladder pain syndrome (IC/BPS).

Methods: Bladder wall biopsies were performed in 27 patients with OAB, 18 patients with IC/BPS, and 19 controls. The expression of junction protein E-cadherin, tight junction protein zonula occludens (ZO-1), and activated mast cells in the bladder wall were evaluated quantitatively using immunofluorescence staining.

Results: The numbers of mast cells in the urothelium and suburothelium areas were low in the control group (mean ± standard error 1.77 ± 0.47). A highly significant increase in mast cell infiltration was observed in OAB (4.00 ± 0.55, P = .002) and IC/BPS specimens (4.64 ± 0.72, P = .000). ZO-1 expression was significantly decreased in IC/PBS (7.45 ± 0.99) compared with OAB (13.46 ± 1.32, P = .004) and control bladder samples (14.55 ± 2.08, P = .004). The E-cadherin expression was also significantly decreased in IC/BPS bladder samples (59.05 ± 9.48) compared with the controls (96.30 ± 9.15, P = .001). No significant difference was found in E-cadherin or ZO-1 levels between the OAB and control bladders (P = .170 and P = .763, respectively).

Conclusion: Mast cell infiltration was found in both OAB and IC/BPS bladder wall, but E-cadherin and ZO-1 expression was only decreased in IC/BPS, suggesting the urothelial barrier function was not affected in the OAB bladder.