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

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.