Uroplakin III-delta4 messenger RNA as a promising marker to identify nonulcerative interstitial cystitis

Interstitial cystitis remains a poorly understood urological condition characterized by chronic pelvic pain and increased urinary frequency in the absence of any known etiology. Urothelial dysfunction and other abnormalities are presumed to be involved in the disease. Uroplakins that are expressed by urothelial cells are thought to have an important role as major barrier proteins on the apical surface of the urothelium.

Gene expression of uroplakin Ia, Ib, II, III and III-delta4 was quantitatively measured in bladder biopsy samples from 29 patients with interstitial cystitis and 16 control subjects using real-time reverse transcriptase-polymerase chain reaction.

The mRNA levels of the uroplakin Ia, Ib and II genes were relatively low and uroplakin III was relatively high in interstitial cystitis bladders compared to normal controls, although not significantly. Uroplakin III-delta4, a splicing variant of uroplakin III, was significantly up-regulated in interstitial cystitis samples (p <0.001). When patients with interstitial cystitis were divided into those with and without ulcerative changes, the uroplakin III and III-delta4 genes were significantly up-regulated only in patients with nonulcerative interstitial cystitis. Even more interesting was the finding that up-regulation of uroplakin III-delta4 was much more prominent than that of uroplakin III, that is 26.5 vs 5.6-fold compared to the median values of normal subjects.

Although the clinical implications of the over expression of uroplakin III and III-delta4 in nonulcerative interstitial cystitis bladders remains to be clarified, from the diagnostic viewpoint uroplakin III-delta4 is a potential marker for identifying nonulcerative interstitial cystitis.