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IP66-14 VALIDATION AND TESTING OF AN IN VITRO MODEL TO STUDY MEDICAL TREATMENTS FOR ANTERIOR URETHRAL STRICTURE DISEASE: ASSESSING THE POTENTIAL EFFICACY OF PHOSPHODIESTERASE-4 (PDE-4) INHIBITION
Abstract   Peer reviewed

IP66-14 VALIDATION AND TESTING OF AN IN VITRO MODEL TO STUDY MEDICAL TREATMENTS FOR ANTERIOR URETHRAL STRICTURE DISEASE: ASSESSING THE POTENTIAL EFFICACY OF PHOSPHODIESTERASE-4 (PDE-4) INHIBITION

Lola P. Lozano, Michael J. Volk, Chantal Allamargot, Jane T. Kurtzman, M. Ben Christensen, Jeremy B. Myers, Alexandria M. Hertz and Bradley A. Erickson
The Journal of urology, Vol.215(5S), p.e1316
05/2026
DOI: 10.1097/01.JU.0001191672.88727.3a.14

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Abstract

INTRODUCTION AND OBJECTIVES: Paclitaxel-coated urethral dilating balloons have changed anterior urethral stricture disease (aUSD) treatments and renewed interest in endoscopic management of aUSD with medical augmentation. The purpose of this study was to design and validate an in vitro model to test the potential efficacy of other drugs. We assess the efficacy of roflumilast which provides non-specific inhibition of phosphodiesterase-4 (PDE4) and is an FDA approved anti-inflammatory for chronic obstructive pulmonary disease (oral) and psoriasis (topical). METHODS: Step 1: We use cadaveric urethral specimens (<24 hours post-mortem) to determine the distribution of the potential drug targets. We use immunohistochemistry (IHC) to stain for all PDE4 isozymes (A-D). Step 2: We culture human urethral epithelial cells (HUEC) and expose to transforming growth factor-β1 (TGF-β1 - 10 ng/mL) to replicate a cell environment known to induce fibrosis. Gene expression was assessed for all PDE4 isozymes and genes involved in stricture pathophysiology. Step 3: TGF-β1 exposed HUEC were exposed to the treatment drug - roflumilast (10 uM) - to determine its effect on cell survival. Step 4: We compare HUEC survival between study drug and the gold standard paclitaxel (0.01 uM and 0.1 uM). RESULTS: All five anterior urethral locations showed equivalent IHC staining intensity for PDE4 A, B, and D and weak staining for PDE-4C (Figure 1 A-C). Exposure of HUEC to TGF-β1 increased the expression of several genes including a significant rise in PDE4-C mRNA (Figure 1D). When HUEC were exposed to roflumilast, there was no cytotoxicity, whereas exposure of HUEC to paclitaxel led to significant cell death. Notably, addition of roflumilast was cytoprotective in the paclitaxel environment (Figure 1E). CONCLUSIONS: We intend to use this reproducible in vitro urethral stricture model in future studies to determine if other drugs may be effective in treating aUSD. This model can be used prior to costly in vivo work. We show that PDE4 is expressed in the normal urethra, is upregulated in pro-fibrotic environments, and is cytoprotective. Thus, its inhibition after trauma (e. g. urethral dilation) could potentially decrease the TGF-β1 induced fibrotic response without the potentially negative cytotoxic effects of paclitaxel. As roflumilast is commercially available in both oral and topical forms, further investigation with this drug appears to be both feasible and warranted.

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