To investigate the urothelium function and sensory receptors difference between interstitial cystitis/bladder pain syndrome (IC/BPS) patients with or without Hunner's lesion.

Fourteen female IC/BPS patients with Hunner's lesion (Hunner IC) and 14 age-matched IC/BPS patients without Hunner's lesions (non-Hunner IC) were enrolled. Bladder mucosa biopsies were obtained. Bladder inflammation, eosinophil infiltration, and urothelial denudation were graded on a 4-point scale after staining with hematoxylin and eosin. Adhesive protein E-cadherin, tryptase, and zonula occuldens-1 in the bladder tissues were assessed with immunofluorescence staining. Urothelial muscarinic receptors M2, M3, endothelial nitric oxide synthase (eNOS), and purinergic receptor P2X3 were evaluated by Western blotting.

Hunner IC patients had a significantly higher mean visual analog scale pain score and smaller cystometric bladder capacity than non-Hunner IC patients. The Hunner IC bladder specimens showed more severe or moderate eosinophilic infiltration and urothelial denudation than the non-Hunner IC bladder specimens did. The E-cadherin expression was significantly lower, and eNOS expression was significantly higher in the Hunner IC bladder samples than in the non-Hunner IC samples. The other functional proteins or sensory receptors did not differ between groups.

Bladder inflammation and urothelial cell adhesion defects were more severe in the Hunner IC than that in the non-Hunner IC patients. eNOS was significantly higher in the Hunner IC than in the non-Hunner IC bladder samples, suggesting that eNOS expression difference may implicate different pathogenesis in 2 types of IC.