MP60-18 POTENTIAL ROLES OF WNT-β CATENIN PATHWAY AND EPITHELIAL TO MESENCHYMAL TRANSITION IN URETHRAL FIBROGENESIS

INTRODUCTION AND OBJECTIVE: Iatrogenic injuries to urethral mucosa result in fibrosis, causing luminal constriction leading to scarring and stricture. The precise cellular and molecular mechanisms that underlie urethral fibrogenesis remain elusive. A clear understanding of these mechanisms would help to optimize therapies for prevention of stricture disease and its recurrence. Our objectives are to evaluate molecular mechanisms of urethral fibrogenesis consequent to mucosal injury in a pre-clinical animal model. METHODS: To understand this, we employed endoluminal electrocautery in a male rabbit (using Karl Storz 10 Fr. pediatric urethroscope) to create mucosal injury (n=6; Fig A-B). Retrograde urethrogram (RUG) and endoluminal ultrasound techniques were used to assess severity and changes in luminal cross-sectional area. Six control rabbits were subjected to sham injury. Urethral tissues were harvested 30 days post-injury and subjected to RNA sequencing and quantitative PCR to determine changes in gene expression. Histological, immunostaining, Western blot studies were used to determine changes in protein expression of known markers of fibrosis (e.g. Collagen, Integrinαv, GIV/Girdin and TGF-β, pSMAD1,2,3). RESULTS: RNA sequencing (Fig C-F) and qPCR (Fig G) studies suggest a potential role for Wnt- β catenin signaling pathways in urethral fibrogenesis. Immunostaining revealed potential role for epithelial to mesenchymal cell transition and positive labelling for all fibrotic markers (e.g. Collagen-1, Integrin αv, GIV/Girdin and TGF-β, SMAD1,2,3). Western blot analysis confirmed increased protein levels of these fibrotic markers. CONCLUSIONS: Our results suggest urethral mucosal fibrogenesis is possibly mediated by novel fibrogenic signaling cascade pathways involving Wnt, TGF- β and GIV/Girdin leading to increased collagen deposition. Therapeutic strategies targeting these pathways may be beneficial in attenuating fibrogenesis and stricture progression.Source of Funding: VA Merit Award