A hypothesis for the etiology of interstitial cystitis based upon inhibition of bladder epithelial repair

Interstitial cystitis (IC) is a chronic bladder disease characterized by distinct bladder mucosal abnormalities, for which the etiology is unknown. Although the epidemiology of this disorder is similar to that of bacterial cystitis, prospective studies using sensitive culture techniques and polymerase chain reaction assay for a variety of microorganisms have failed to identify a specific infectious etiology for IC. We have identified a low-molecular-weight peptide in the urine of IC patients that inhibits the proliferation of normal bladder epithelial cells in vitro. We therefore propose a model of IC, in which this peptide inhibits bladder epithelial regeneration following damage (such as that caused by bacterial cystitis). The chronically damaged epithelium is prone to colonization with various microorganisms, and the resulting exposure to these microorganisms, other urinary antigens, and/or damaged epithelial cells prompts the low-level inflammatory response commonly seen in this disorder.