Normalization of proliferation and paracellular permeability of bladder epithelial cells from interstitial cystitis patients by a synthetic inhibitor of antiproliferative factor

Abstract

Objectives: Interstitial cystitis (IC) is a chronic disorder with bladder epithelial thinning or ulceration, pain, urinary frequency and urgency. Bladder epithelial cells from IC patients make an antiproliferative factor (APF) that inhibits cell growth, decreases tight junctions, and increases paracellular permeability. We screened inactive synthetic APF derivatives for their ability to inhibit APF, then determined the ability of an inhibitory derivative to normalize proliferation and permeability of IC cells.Methods: Normal bladder cells were pretreated with inactive APF derivatives, then incubated with active synthetic APF. IC cells were incubated with varying concentrations of D‐proline APF. Cell proliferation was determined by 3H‐thymidine incorporation. Gene expression was determined by quantitative RT‐PCR. Paracellular permeability was determined by 14C mannitol and 3H‐inulin flux on Transwell plates.Results: One of 28 inactive derivatives (D‐proline APF) blocked APF activity in normal bladder cells. D‐proline APF also significantly increased cell proliferation, increased zonula occludens‐1 and claudin 1, 4 and 8 expression, and decreased permeability of IC cells.Conclusions: D‐proline APF can normalize IC cell proliferation and paracellular permeability in vitro, making it a potential therapy for IC. Supported by NIH R01 DK52596 and the Intramural Research Program of the NCI, NIH