Expression of nerve growth factor immunoreactivity and messenger RNA in ischemic urinary bladder

Partners in Crime: NGF and BDNF in Visceral Dysfunction

Neurotrophins (NTs), particularly Nerve Growth Factor (NGF) and Brain-Derived Neurotrophic Factor (BDNF), have attracted increasing attention in the context of visceral function for some years. Here, we examined the current literature and presented a thorough review of the subject. After initial studies linking of NGF to cystitis, it is now well-established that this neurotrophin (NT) is a key modulator of bladder pathologies, including Bladder Pain Syndrome/Interstitial Cystitis (BPS/IC) and Chronic Prostatitis/Chronic Pelvic Pain Syndrome (CP/CPPS. NGF is upregulated in bladder tissue and its blockade results in major improvements on urodynamic parameters and pain. Further studies expanded showed that NGF is also an intervenient in other visceral dysfunctions such as endometriosis and Irritable Bowel Syndrome (IBS). More recently, BDNF was also shown to play an important role in the same visceral dysfunctions, suggesting that both NTs are determinant factors in visceral pathophysiological mechanisms. Manipulation of NGF and BDNF improves visceral function and reduce pain, suggesting that clinical modulation of these NTs may be important; however, much is still to be investigated before this step is taken. Another active area of research is centered on urinary NGF and BDNF. Several studies show that both NTs can be found in the urine of patients with visceral dysfunction in much higher concentration than in healthy individuals, suggesting that they could be used as potential biomarkers. However, there are still technical difficulties to be overcome, including the lack of a large multicentre placebo-controlled studies to prove the relevance of urinary NTs as clinical biomarkers.

Effect of Intravesical Liposome-Based Nerve Growth Factor Antisense Therapy on Bladder Overactivity and Nociception in a Rat Model of Cystitis Induced by Hydrogen Peroxide

The aim of this study was to evaluate whether liposome-based local suppression of nerve growth factor (NGF) in the bladder has effects on bladder hypersensitivity in a rat cystitis model induced by intravesical instillation of hydrogen peroxide (HP). HP (1.5%) was intravesically administered to adult female Sprague-Dawley rats. Liposomes complexed with NGF antisense oligonucleotide (OND) labeled with TYE563 fluorescent tag were intravesically instilled on day 2. Red fluorescence from the TYE 563 tag was observed with fluorescent microscopy on day 3. Four separate groups of rats were used in the following experiments: (a) sham-liposome group, (b) sham-OND group, (c) cystitis-liposome group, and (d) cystitis-OND group. Saline or 1.5% HP was intravesically administered on day 0. Empty liposomes or liposomes-antisense OND were instilled into the bladder on day 2. The following experiments were conducted to evaluate the effect of NGF antisense treatment on day 7: (a) continuous cystometry was performed in an awake condition; (b) pain behavior induced by instillation of resiniferatoxin into the bladder, including licking behavior (lower abdominal licking) and freezing behavior (motionless head-turning toward lower abdomen), was observed; (c) immunohistochemical staining of the bladder and L6 DRG for NGF was performed; (d) the expression of several genes in the bladder was analyzed by reverse transcription polymerase chain reaction (RT-PCR); and (e) after Fast Blue was injected into the bladder wall, Fast Blue-positive or -negative cells in DRG neurons were separately collected by using a laser-capture microdissection method 7 days later. RT-PCR was performed to evaluate gene expressions in captured neuronal cells. The expression of TYE563 was identified only in the urothelial layer. In cystometric investigation, intercontraction intervals (ICI) were significantly (p = 0.001) shorter in the cystitis-liposome group in comparison to the sham-liposome group. ICI was significantly (p = 0.007) longer in the cystitis-OND group compared to the cystitis-liposome group. Comparisons of the sham-liposome and the sham-OND groups showed no significant difference in ICI (p = 0.56). Licking events did not significantly differ among the four groups. In contrast, the cystitis-liposome group showed significantly more freezing events than the sham-liposome group did (p = 0.002). A significant reduction in the number of freezing events was observed in the cystitis-OND group compared to the cystitis-liposome group (p = 0.04). Immunofluorescence staining demonstrated that NGF expression in the mucosa (p = 0.02) and L6 DRG (p = 0.01) was significantly higher in the cystitis-liposome group than it was in the sham-liposome group. The expression of NGF was significantly lower in the mucosa (p = 0.002) and L6 DRG (p = 0.01) in the cystitis-OND group compared to the cystitis-liposome group. RT-PCR showed that the expression of NGF and TRPV1 mRNA in the mucosa was significantly higher in the cystitis-liposome group than it was in the sham-liposome group (p = 0.001 and 0.03, respectively). On the other hand, these gene expressions were significantly lower in the cystitis-OND group than they were in the cystitis-liposome group (p = 0.007 and 0.02, respectively). The cystitis-liposome group showed significantly higher expression of TRPA1, P2X3, and BDNF mRNA in labeled bladder afferent neurons than the sham-liposome group did (p = 0.03, 0.01, and 0.001, respectively). These gene expressions were significantly lower in the cystitis-OND group compared to the cystitis-liposome group (p = 0.04, 0.006, and 0.03, respectively). The study indicated that intravesical application of liposome-NGF antisense OND significantly improved bladder hypersensitivity induced by chemical cystitis in rats. Intravesical treatment with liposome-OND conjugates could be a novel local therapy of hypersensitive bladder disorders such as bladder pain syndrome/interstitial cystitis.

Urinary nerve growth factor in patients with detrusor overactivity

Background

Detrusor overactivity (DO) is one of the most frequent bladder dysfunctions in children up to the age of 18. Nowadays, the only way to confirm DO is by urodynamic investigation, which is an invasive procedure. Among the many mediators influencing bladder function, nerve growth factor (NGF) plays an important role. The present study was designed to measure urinary NGF (uNGF) levels in patients with DO diagnosed by urodynamic study in comparison with healthy controls.

Methods

The investigation was conducted on 44 children, divided into two groups (24 patients with DO, 20 healthy children). Uroflowmetry was performed in all enrolled to the study and cystometry only to patients. uNGF levels were estimated in both studied groups.

Results

The median uNGF level in patients with DO before treatment was higher compared with healthy controls. There were no differences between uNGF levels in patients after anticholinergic treatment and the controls. We found differences in uroflowmetry parameters between the reference group and the patients. We found correlations between uroflowmetry parameters and uNGF/cr. level.

Conclusions

The uNGF level could be used for detecting DO in children and adolescents.

Measuring uNGF level is a simple, noninvasive procedure and very useful for choosing therapy in patients with DO in various clinical conditions.

Urinary bladder mucosal responses to ischemia

PURPOSE

The objectives of this study were to examine the expression of various cellular proteins within the urothelium (UT) and lamina propria (LP) following chronic bladder ischemia in the rat urinary bladder.

MATERIALS AND METHODS

Urinary bladders were removed from adult Sprague-Dawley rats 8 weeks after creation of bladder ischemia and from sham controls. Immunocytochemistry was used to examine distribution of LP-vimentin-immunoreactive (IR) cells and connexins (Cx26; Cx43), and western immunoblotting or ELISA for proteins involved in UT barrier and sensory functions.

RESULTS

Ischemia was associated with a significant increase in LP-vimentin-IR cells and increased expression of the gap junction proteins Cx26 and Cx43 within the bladder UT as compared to sham control. Ischemia also resulted in an increased (p < 0.05) expression level of the junctional marker (ZO-1) and non-significantly increased expressions of the trophic factor nerve growth factor as well as norepinephrine.

CONCLUSIONS

Our findings reveal that chronic ischemia alters a number of proteins within the UT and underlying LP. These proteins are involved in barrier function, remodeling, repair as well as intercellular communication. The increased expression of LP-vimentin-IR cells suggests that changes in cell-cell interactions could play a role in ischemia-induced changes in bladder activity.