DECREASED EXPRESSION OF A GLYCOPROTEIN COMPONENT OF BLADDER SURFACE MUCIN (GP1) IN INTERSTITIAL CYSTITIS

Interstitial cystitis is a disease of unknown etiology characterized b y unremitting urinary frequency, urgency and suprapubic pain. Recently , a change in urothelial permeability has been identified in interstit ial cystitis patients that is presumably mediated by aberrations in bl adder surface mucin. For this study we evaluated qualitative changes i n a previously defined glycoprotein component of this layer (GP1) as i t occurs in interstitial cystitis patients and normal controls. Paraff inized bladder biopsies were obtained from 23 interstitial cystitis pa tients (all meeting National Institutes of Health inclusion criteria) and 11 normal controls. All biopsy tissue was stained with hematoxylin and eosin, and periodic acid, Schiff reaction. The tissues were exami ned immunohistochemically for GP1 using an anti-GP1 serum. Periodic ac id, Schiff staining clearly identified bladder surface proteoglycans i n all specimens. Moderate GPI reactivity was noted in all normal contr ol specimens. Alternatively, GPI expression was absent in 35% of the i nterstitial cystitis patient biopsies and decreased in 61%. These data demonstrate qualitative GPI changes in a majority of interstitial cys titis patients. It is unknown whether these differences have an impact on the pathogenesis of interstitial cystitis. However, our findings s uggest that the absence or decreased expression of GP1 in interstitial cystitis bladder biopsies may serve as a marker to characterize the d isease further in conjunction with clinical findings.