Normalization of Proliferation and Tight Junction Formation in Bladder Epithelial Cells from Patients with Interstitial Cystitis/Painful Bladder Syndrome by d-Proline and d-Pipecolic Acid Derivatives of Antiproliferative Factor

Interstitial cystitis/painful bladder syndrome is a chronic bladder disorder with epithelial thinning or ulceration, pain, urinary frequency and urgency, for which there is no reliably effective therapy. We previously reported that interstitial cystitis/painful bladder syndrome bladder epithelial cells make a glycopeptide antiproliferative factor or 'APF' (Neu5Ac alpha 2-3Gal beta 1-3GalNAc alpha-O-TVPAAVVVA) that induces abnormalities in normal cells similar to those in interstitial cystitis/painful bladder syndrome cells in vitro, including decreased proliferation, decreased tight junction formation, and increased paracellular permeability. We screened inactive APF derivatives for their ability to block antiproliferative activity of asialylated-APF ('as-APF') in normal bladder cells and determined the ability of as-APF-blocking derivatives to normalize tight junction protein expression, paracellular permeability, and/or proliferation of interstitial cystitis/painful bladder syndrome cells. Only two of these derivatives [Gal beta 1-3GalNAc alpha-O-TV-(d-pipecolic acid)-AAVVVA and Gal beta 1-3GalNAc alpha-O-TV-(d-proline)-AAVVVA] blocked as-APF antiproliferative activity in normal cells (p < 0.001 for both). Both of these antagonists also 1) significantly increased mRNA expression of ZO-1, occludin, and claudins 1, 4, 8, and 12 in interstitial cystitis/painful bladder syndrome cells by qRT-PCR; 2) normalized interstitial cystitis/painful bladder syndrome epithelial cell tight junction protein expression and tight junction formation by confocal immunofluorescence microscopy; and 3) decreased paracellular permeability of 14C-mannitol and 3H-inulin between confluent interstitial cystitis/painful bladder syndrome epithelial cells on Transwell plates, suggesting that these potent APF antagonists may be useful for the development as interstitial cystitis/painful bladder syndrome therapies.