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Sources of Funding: SNSF Grant 320030_156161/1, Velux Foundation Grant 895, R01 DK077195-07

Introduction

Bladder outlet obstruction (BOO) leads to lower urinary tract symptoms (LUTS) and urodynamic changes. Previously we identified microRNA (miRNA) and mRNA expression profiles associated with different states of BOO-induced LUTD in human patients. Animal models of experimentally-induced partial BOO are widely used to study bladder wall remodeling. Here we determined the expression profiles of miRNAs and selected mRNAs in pBOO mice and compared the observed changes to human patients.

Methods

All experiments were performed using 10-to-12-week-old male mice that underwent microsurgical creation of pBOO and sham-operated control animals. Bladders were harvested 2, 4, 6 and 8 weeks after pBOO and total RNA isolated. Muscle contractility was assessed in parallel cohorts at 1, 2, 4 and 6 weeks. Expression profiles of 598 miRNAs were established using NanoString nCounter Analysis System mouse miRNA assay kit. Levels of selected mouse mRNAs were determined by QPCR. Bladder dome biopsies were collected from controls and patients with urodynamically established BOO and miRNA and mRNA expression profiles determined by Next Generation Sequencing (NGS) analysis.

Results

Similar to human patients&[prime] results, we observed a down-regulation of smooth muscle-associated miRNAs mmu-miR-1, mmu-miR-143, mmu-miR-145, mmu-miR-486 and mmu-miR-133a in pBOO mouse bladders. Pro-fibrotic mmu-miR-142-3p and mmu-miR-21 were up-regulated, and anti-fibrotic mmu-miR-29c down-regulated. Surprisingly, the expression levels of other miRNAs including miR-22, -26b, -10a and -342-3p, which were strongly regulated in human BOO patients, did not change in the mouse model. Pathway analysis in human BOO patients identified TNF-alpha as the top upstream regulator, and revealed signalling molecules, including MYC, FOS, CTGF, PIK3R5, which were strongly induced in different urodynamic states of BOO. In pBOO mice there was evidence of hypertrophic changes (MYBL2, MYH11 and MYC up-regulation) at 2 weeks pBOO, and CTGF was significantly increased at 4 and 6 weeks post-obstruction. Contrary to human data, we observed no regulation of TNF-responsive genes in the mouse model.

Conclusions

Experimentally-induced pBOO in mice led to significant gene expression changes, including alteration of pro-fibrotic mRNAs and miRNAs resembling human BOO patients. Lack of evidence of TNF-alpha-induced miRNA and mRNA regulation might indicate a different pathophysiological mechanism of organ remodelling in pBOO model compared to human disease.

Funding

SNSF Grant 320030_156161/1, Velux Foundation Grant 895, R01 DK077195-07