PURPOSE:
Overexpression of nerve growth factor (NGF) in the bladder has been shown to play a role in symptoms of overactive bladder through mediation of functional changes in bladder afferent pathways. We studied whether the blockade of NGF overexpression in the bladder urothelium by sequence-specific gene-silencing mechanism suppresses bladder overactivity as well as chemokine expression induced by acetic acid (AA).
METHOD:
Female Sprague-Dawley rats anaesthetized with isoflurane were instilled with 0.5mL of either saline, scrambled or TYE563 labeled antisense oligonucleotide (OND) targeting NGF (12μM) alone or complexed with cationic liposomes for 30min. The efficacy of NGF antisense treatments for AA i... More
PURPOSE:
Overexpression of nerve growth factor (NGF) in the bladder has been shown to play a role in symptoms of overactive bladder through mediation of functional changes in bladder afferent pathways. We studied whether the blockade of NGF overexpression in the bladder urothelium by sequence-specific gene-silencing mechanism suppresses bladder overactivity as well as chemokine expression induced by acetic acid (AA).
METHOD:
Female Sprague-Dawley rats anaesthetized with isoflurane were instilled with 0.5mL of either saline, scrambled or TYE563 labeled antisense oligonucleotide (OND) targeting NGF (12μM) alone or complexed with cationic liposomes for 30min. The efficacy of NGF antisense treatments for AA induced bladder overactivity (BO) was assessed by cystometry. The expression levels and cellular distribution of NGF in the bladder was quantified by immunofluorescence staining and ELISA. Effects on bladder chemokine expression were measured by Luminex xMAP analysis.
RESULTS:
Liposomes were demonstrated to be necessary for bladder uptake of OND by absence of bright red fluorescence of TYE 563 in rats instilled with OND alone. At 24h after the liposome-OND treatment, baseline bladder activity during saline infusion was indistinct in the sham and antisense treated groups with mean intercontraction interval (ICI) of 348±55 sec and 390±120 sec, respectively. AA induced BO is demonstrated by an ICI reduction to 33.2±4.0% of baseline values in sham rats; however the ICI reduction was blunted to 75.8±3.4% of baseline values (p<0.05) in rats treated with liposomal antisense OND. AA induced elevation of NGF in the urothelium of sham rats was reduced by antisense treatment as revealed by ELISA and reduced NGF immunoreactivity in the urothelium. Elevation of NGF in bladder tissue was associated with overexpression of sICAM-1, sE-Selectin, CXCL-10, CXCL-1, leptin, MCP-1 and VEGF, which was significantly reduced by NGF antisense treatment (p<0.01).
CONCLUSIONS:
Acetic acid induced BO is associated with overexpression of NGF in the urothelium and chemokine upregulation. Treatment with liposomal antisense suppresses BO, as well as NGF and chemokine expression. Local suppression of NGF in bladder could be an attractive approach for overactive bladder, which can avoid systemic side effects that may be associated with non-specific blockade of NGF expression.
