Urinary nerve growth factor levels are elevated in patients with overactive bladder and do not significantly increase with bladder distention

Temporally complex inflammatory networks in an animal model reveal signatures for interstitial cystitis and bladder pain syndrome phenotype

INTRODUCTION AND OBJECTIVE

Interstitial cystitis and bladder pain syndrome (IC/BPS) presents with symptoms of debilitating bladder pain and is typically a diagnosis of exclusion. The cystoscopic detection of Hunner's lesions increases the likelihood of detecting tissue inflammation on bladder biopsy and increases the odds of therapeutic success with anti-inflammatory drugs. However, the identification of this subgroup remains challenging with the current lack of surrogate biomarkers of IC/BPS. On the path towards identifying biomarkers of IC/BPS, we modeled the dynamic evolution of inflammation in an experimental IC/BPS rodent model using computational biological network analysis of inflammatory mediators (cytokines and chemokines) released into urine. The use of biological network analysis allows us to identify urinary proteins that could be drivers of inflammation and could therefore serve as therapeutic targets for the treatment of IC/BPS.

METHODS

Rats subjected to cyclophosphamide (CYP) injection (150 mg/kg) were used as an experimental model for acute IC/BPS (n = 8). Urine from each void was collected from the rats over a 12-h period and was assayed for 13 inflammatory mediators using Luminex™. Time-interval principal component analysis (TI-PCA) and dynamic network analysis (DyNA), two biological network algorithms, were used to identify biomarkers of inflammation characteristic of IC/BPS over time.

RESULTS

Compared to vehicle-treated rats, nearly all inflammatory mediators were elevated significantly (p < 0.05) in the urine of CYP treated rats. TI-PCA highlighted that GRO-KC, IL-5, IL-18, and MCP-1 account for the greatest variance in the inflammatory response. At early time points, DyNA indicated a positive correlation between IL-4 and IL-1β and between TNF-α and IL-1β. Analysis of TI-PCA and DyNA at later time points showed the emergence of IL-5, IL-6, and IFNγ as additional key mediators of inflammation. Furthermore, DyNA network complexity rose and fell before peaking at 9.5 h following CYP treatment. This pattern of inflammation may mimic the fluctuating severity of inflammation associated with IC/BPS flares.

CONCLUSIONS

Computational analysis of inflammation networks in experimental IC/BPS analysis expands on the previously accepted inflammatory signatures of IC by adding IL-5, IL-18, and MCP-1 to the prior studies implicating IL-6 and GRO as IC/BPS biomarkers. This analysis supports a complex evolution of inflammatory networks suggestive of the rise and fall of inflammation characteristic of IC/BPS flares.

Diagnostic value of nerve growth factor in detrusor overactivity: a study on women with mixed urinary incontinence

OBJECTIVE

Urinary incontinence has a profound impact on women's quality of life. Studies have shown that changes in urinary protein levels could be a potential diagnostic biomarker in some urological diseases. The aim of present study is to determine the diagnostic value of nerve growth factor (NGF) in women with mixed urinary incontinence (MUI) as a diagnostic biomarkers of detrusor overactivity (DO).

METHODS

Seventy women aged between 20 and 75 years with MUI were enrolled in this prospective study. All participants underwent urodynamic study. Urine NGF levels were measured using an ELISA method. NGF level was compared between groups using Mann-Whitney U test. Receiver Operator Characteristic (ROC) analysis was employed to evaluate the diagnostic performance of urinary NGF.

RESULTS

The results showed that the median (min, max) of NGF in patients with DO was significantly higher in comparing to its level in women without DO [184.10 (31, 346.60) pg/ml vs. 151.80 (21, 210.70)], respectively (P = 0.035). Using receiver-operator characteristics analysis, the threshold urinary NGF value of 102.00 pg/ml provided a sensitivity of 88% and specificity of 40% in diagnosing DO, PPV of 39.1%, and NPV of 88.2%, positive likelihood ratio 2.18 and negative likelihood ratio of 0.45 (P = 0.02).

CONCLUSION

Based on high sensitivity and low specificity, we can conclude that NGF can be a good tool for ruling out the OAB when the test is negative. However, the future investigations are needed to expand the observed correlation in larger groups of women with DO.

The urothelium, the urinary microbioma and men LUTS: a systematic review

INTRODUCTION

The pathophysiology and management of male patients with lower urinary tract symptoms (LUTS) is still a matter of debate. In the past few years, the urothelium and the urinary microbiota represented important areas of research to improve the understanding and management of these patients. Aim of the present review was to summarize the available data on the urothelium and the microbiota related to male LUTS.

EVIDENCE ACQUISITION

A National Center for Biotechnology Information (NCBI) PubMed search for relevant articles published between January 2000 and December 2019 was performed using the medical subjects heading "urothelium," "microbioma," "microbiota," "urobioma," "urobiota," "benign prostatic hyperplasia," "benign prostatic enlargement," "lower urinary tract symptoms," "lower urinary tract dysfunction," "men," "male," "overactive bladder," "receptors." Exclusion criteria included: animal studies and studies on muscarinic and adrenergic pathways.

EVIDENCE SYNTHESIS

The urothelium has been recently evaluated in humans to evaluate new possible markers and pathways. New possible targets for the treatment of male LUTS include the neural growth factor, the cannabinoid, the vanilloid and the ATP pathways. However, studies in humans are still needed to elucidate the exact role of these pathways in the management of male patients with LUTS. The available evidence on the urinary microbioma in male is poor. Standing to the available, urinary microbioma is evident in healthy urine in males. Moreover, the urinary microbioma varies depending on the method of collection, sexually transmitted disease status, inflammation and urinary symptoms. A possible role of probiotics in the management of LUTS in women has been proposed and may have a role in male patients as well.

CONCLUSIONS

The urothelium and the urinary microbiota are still poorly studied in men with LUTS. Most of the evidence and the hypothesis on the relationship between urothelium/urinary microbiota and LUTS comes from animal/in-vitro evidence while clinical trials are lacking. These pathways seem interesting even in LUTS pathogenesis in men but their possible role as a new therapeutic target is still an open debate.

Urinary nerve growth factor: a biomarker for detrusor overactivity in children? A meta-analysis and trail sequential analysis

PURPOSE

Based on, previously, a systematic review, urinary nerve growth factor (NGF) has emerged as one potentially noninvasive biomarker for detrusor overactivity (DO) in adults. We performed this systematic review to explore if NGF is a biomarker for DO in children.

METHODS

A literature search was conducted in PubMed, Embase, Web of science, and Cochrane Library. Copies of all relevant articles were retrieved for quality assessment and data abstraction by two reviewers. Primary outcome was pooled standardized mean difference (SMD) for NGF/Cr (NGF normalized to urine creatinine) level between DO group and controls.

RESULTS

Three case-control studies published from 2012 to 2016 were included with 74 patients and 70 controls. Children with DO had a significant higher baseline urinary NGF/Cr level compared to controls (SMD = 2.48, 95%CI = 0.85-4.10, P < 0.01). After treatment, the level of NGF/Cr decreased significantly compared to baseline level at 6th month time points (SMD = 0.94, 95%CI = 0.03-1.86, P = 0.04). We calculated the required information size to 99 patients for comparison of urinary NGF/Cr level between DO and controls by trail sequential analysis (TSA).

CONCLUSION

Based on this systematic review, NGF/Cr may be a noninvasive biomarker for DO in children in the future. However, based on TSA, more original studies are needed to clarify the role of NGF/Cr in the biomarker effect.

PACAP/PAC1 Expression and Function in Micturition Pathways

Neural injury, inflammation, or diseases commonly and adversely affect micturition reflex function that is organized by neural circuits in the CNS and PNS. One neuropeptide receptor system, pituitary adenylate cyclase-activating polypeptide (PACAP; Adcyap1), and its cognate receptor, PAC1 (Adcyap1r1), have tissue-specific distributions in the lower urinary tract. PACAP and associated receptors are expressed in the LUT and exhibit changes in expression, distribution, and function in preclinical animal models of bladder pain syndrome (BPS)/interstitial cystitis (IC), a chronic, visceral pain syndrome characterized by pain, and LUT dysfunction. Blockade of the PACAP/PAC1 receptor system reduces voiding frequency and somatic (e.g., hindpaw, pelvic) sensitivity in preclinical animal models and a transgenic mouse model that mirrors some clinical symptoms of BPS/IC. The PACAP/receptor system in micturition pathways may represent a potential target for therapeutic intervention to reduce LUT dysfunction following urinary bladder inflammation.

PACAP/Receptor System in Urinary Bladder Dysfunction and Pelvic Pain Following Urinary Bladder Inflammation or Stress

Complex organization of CNS and PNS pathways is necessary for the coordinated and reciprocal functions of the urinary bladder, urethra and urethral sphincters. Injury, inflammation, psychogenic stress or diseases that affect these nerve pathways and target organs can produce lower urinary tract (LUT) dysfunction. Numerous neuropeptide/receptor systems are expressed in the neural pathways of the LUT and non-neural components of the LUT (e.g., urothelium) also express peptides. One such neuropeptide receptor system, pituitary adenylate cyclase-activating polypeptide (PACAP; Adcyap1) and its cognate receptor, PAC1 (Adcyap1r1), have tissue-specific distributions in the LUT. Mice with a genetic deletion of PACAP exhibit bladder dysfunction and altered somatic sensation. PACAP and associated receptors are expressed in the LUT and exhibit neuroplastic changes with neural injury, inflammation, and diseases of the LUT as well as psychogenic stress. Blockade of the PACAP/PAC1 receptor system reduces voiding frequency in preclinical animal models and transgenic mouse models that mirror some clinical symptoms of bladder dysfunction. A change in the balance of the expression and resulting function of the PACAP/receptor system in CNS and PNS bladder reflex pathways may underlie LUT dysfunction including symptoms of urinary urgency, increased voiding frequency, and visceral pain. The PACAP/receptor system in micturition pathways may represent a potential target for therapeutic intervention to reduce LUT dysfunction.

Biochemistry of the menopause

The life of a human female is characterized from teenage years by monthly menstruation which ceases (the menopause) typically between the age of 40 and 60 years. The potential for reproduction declines and ceases as the ovaries become depleted of follicles. A transition period in mid-life, for 2 to 10 years, when menstruation is less regular is called the perimenopause. The menopause is associated with a significant decline in plasma concentrations of sex hormones, an increase in the concentrations of the gonadotrophins and changes in other hormones such as the inhibins. These changes are superimposed with effects of aging, social and metabolic factors, daily activity and well-being. Although the menopause is entirely natural, in some cases ovarian failure can occur earlier than usual; this is pathological and warrants careful biochemical investigations to distinguish it from conditions causing infertility. Elderly females are affected by a range of clinical disorders including endocrine, cardiovascular, skeletal, urogenital tract and immunological systems, body mass, vasomotor tone, mood and sleep pattern. Reference intervals for many diagnostic biochemical tests for the menopause need to be used when interpreting results in clinical investigations for patient management. The standardization and harmonization of assays are being addressed. Many women now choose to develop their career before bearing children, and the health service has had to change services around this. This review does not cover screening for and tests during pregnancy. The review is timely since the population is aging and there will be more demand on healthcare services.

MicroRNAs as potential biomarkers to predict the risk of urinary retention following intradetrusor onabotulinumtoxin-A injection

AIMS

MicroRNAs (miRs) control post-transcriptional gene expression, and this is relevant in understanding better chronic diseases and treatment outcomes. The role of miRs in the pathology and treatment outcomes of overactive bladder (OAB) is unknown. In this study, we assessed the differential expression of miRs in OAB patients responding with either normal or elevated post-void residual volumes (PVRs) ≥200 mL following intradetrusor injection of onabotulinumtoxin-A (onaBoNT-A).

METHODS

Female OAB patients refractory to OAB drugs were consented for this study. Cystoscopic-guided punch bladder biopsy was obtained at the time of injection of onaBoNT-A 100 units. The expression of 13 miR species, selected for their known effect on neurotrophin expression and smooth muscle function, was measured. PVRs and urine nerve growth factor (NGF) levels were measured at baseline and at the follow-up visit.

RESULTS

Fourteen patients with mean age of 66 years were consented. Of these patients, nine maintained PVRs <200 mL after onaBoNT-A injection to comprise the low PVR group. The other five patients with PVRs ≥200 mL comprised the high PVR group. The expression of miR221 and miR125b was upregulated by 11- and 2-fold, respectively, in patients who responded with low PVRs after onaBoNT-A (P < 0.05). Urine NGF levels at baseline were not different between the two groups.

CONCLUSIONS

This study suggests that deficiency in the pretreatment expression of miR221 and miR125b may predispose OAB patients to high PVRs following intradetrusor onaBoNT-A. Additional studies are needed to better understand the role of miRs in OAB.

Lower Levels of Urinary Nerve Growth Factor Might Predict Recurrent Urinary Tract Infections in Women

PURPOSE

To investigate the changes in urinary nerve growth factor (uNGF) levels after acute urinary tract infection (UTI) and to assess the role of uNGF in predicting UTI recurrence in women.

METHODS

Women with uncomplicated, symptomatic UTIs were enrolled. Cephalexin 500 mg (every 6 hours) was administered for 7-14 days to treat acute UTIs. Subsequently, the patients were randomized to receive either sulfamethoxazole/trimethoprim 800 mg/160 mg daily at bedtime, or celecoxib 200 mg daily for 3 months and were monitored for up to 12 months. NGF levels in the urine were determined at baseline, 1, 4, and 12 weeks after the initiation of prophylactic therapy, and were compared between women with first-time UTIs and recurrent UTIs, sulfamethoxazole/trimethoprim and celecoxib-treated women, and no UTI recurrence and UTI recurrence that occurred during the follow-up period. Twenty women free of UTIs served as controls.

RESULTS

A total of 139 women with UTI and 20 controls were enrolled in the study, which included 50 women with a first-time UTI and 89 women with recurrent UTIs. Thirty-seven women completed the study. Women with recurrent UTIs (n=23) had a trend of lower uNGF levels than women with first-time UTIs (n=14). During follow-up, 9 women had UTI recurrence. The serial uNGF levels in women with UTI recurrence were significantly lower than those in women who did not have UTI recurrence during the follow-up period.

CONCLUSIONS

The lower levels of uNGF in women with recurrent UTI and the incidence of UTI recurrence during follow-up suggest that lower uNGF might reflect the defective innate immunity in women with recurrent UTI.

Not all neurogenic bladders are the same: a proposal for a new neurogenic bladder classification system

Neurogenic bladder (NGB) has long been defined as a clinical entity that describes a heterogeneous collection of syndromes. The common theme is a bladder disorder concomitant with a neurologic disorder. This definition does not give the clinician much information about the bladder disorder, nor how to treat it, or even what the natural history of the disorder is likely to be. It may be time for a new classification scheme to better define the bladder defect and prognosis, as well as inform treatment. We propose a classification system based on seven categories, each having a neurologic defect in a distinct anatomic location. This is termed SALE (Stratify by Anatomic Location and Etiology). In addition, the presence or absence of bowel dysfunction and autonomic dysreflexia will be reported. In the future, as more definite prognostic information can be gleaned from biomarkers, we anticipate adding urinary nerve growth factor (NGF) and urinary brain-derived neurotrophic factor (BDNF) levels to the definition. We expect the SALE system to efficiently describe a patient suffering from NGB and simultaneously inform the most appropriate treatment, follow-up regimen, and long-term prognosis.

Constitutive expression Of NGF And P75(NTR) affected by bladder distension and NGF antisense treatment

AIMS

It is known that bladder exposure to noxious stimuli elicits nerve growth factor (NGF) expression with region wise differences. Here, we investigated the effect of bladder distension (cystometry) and bladder wall injection of NGF antisense oligonucleotide (ODN) together as well as separately on spontaneous (constitutive) expression of NGF and its cognate p75 neurotrophin receptor (p75(NTR)).

METHOD

Under isoflurane anesthesia, either 15μg of protamine sulfate (vehicle) alone or complexed with 1.5μg of NGF antisense or scrambled ODN was injected (10μL) at 4 sites in bladder wall of 24 adult female Sprague-Dawley rats and 6 rats were left untreated (n=30). Under urethane anesthesia, cystometry (CMG) was performed in treated and control rats. Fluorescent ODN and NGF/p75(NTR) expression was localized in harvested tissue.

KEY FINDINGS

Complexation of ODN with protamine was essential for the retention of ODN in bladder tissue as the uncomplexed ODN was untraceable after injection. Bladder distension from CMG raised the expression of NGF and p75(NTR) relative to CMG naïve rats. The groups treated with vehicle, scrambled and antisense ODN were indistinct with regard to CMG parameters, but the intense immunoreactivity of NGF and p75(NTR) seen in the vehicle and scrambled ODN groups was reduced following treatment with NGF antisense.

SIGNIFICANCE

The constitutive expression of NGF and p75(NTR) is responsive to bladder distension and administration of NGF antisense. Complexation with protamine reduces the clearance of ODN and demonstrates the potential of ODN nanoparticles as an option for reducing the inducible NGF expression in OAB patients following intradetrusor injection.

Measurements of C-reactive protein (CRP) and nerve-growth-factor (NGF) concentrations in serum and urine samples of dogs with neurologic disorders

BACKGROUND

The purpose of this study was to prove the hypothesis that C-reactive protein (CRP) and nerve growth factor (NGF) may be potential biomarkers for lower urinary tract disorders and may be able to distinguish between micturition dysfunctions of different origin in dogs with spinal cord diseases. NGF- and CRP- concentrations were measured in serum and urine samples using specific ELISA-Kits. Results in urine were standardized by urine-creatinine levels.

RESULTS

CRP in serum was detectable in 32/76 and in urine samples in 40/76 patients. NGF could be measured in all serum and in 70/76 urine samples. Urinary CRP concentrations were significantly higher in dogs with micturition dysfunction (p = 0.0009) and in dogs with different neurological diseases (p = 0.0020) compared to the control group. However, comparing dogs with spinal cord disorders with and without associated micturition dysfunction no significant difference could be detected for NGF and CRP values in urine or serum samples. Additionally, levels did not decrease significantly, when measured at the time when the dogs regained the ability to urinate properly (urinary NGF p = 0.7962; urinary CRP p = 0.078). Urine samples with bacteria and/or leukocytes had no significant increase in urinary NGF (p = 0.1112) or CRP (p = 0.0534) concentrations, but higher CRP-levels in urine from dogs with cystitis were found compared to dogs without signs of cystitis.

CONCLUSIONS

From these data we conclude that neither CRP nor NGF in urine or serum can be considered as reliable biomarkers for micturition disorders in dogs with spinal cord disorders in a clinical setting, but their production might be part of the pathogenesis of such disorders. Significantly higher levels of CRP could be found in the urine of dogs with micturition dysfunctions compared to control dogs. This phenomenon could potentially be explained by unspecific extrahepatic CRP production by smooth muscle cells in the dilated bladder.

Urinary nerve growth factor as an oncologic biomarker for prostate cancer aggressiveness

OBJECTIVES

We investigated urinary nerve growth factor (NGF) as a novel urinary biomarker for high-grade prostate cancer (PCa).

METHODS AND MATERIALS

After institutional review board approval for a prospective pilot study, we enrolled men at the preoperative visit before robotic-assisted radical prostatectomy. Demographics, urinary flow parameters, and urine samples were collected. Urinary NGF and urinary creatinine were obtained in the translational science laboratory. Pathologic and postoperative demographics were collected after surgery. NGF is the primary outcome variable (dependent variable). The pathologic Gleason score (ordinal variable ≤6, 7, and ≤8) served as an independent grouping variable. Multivariate analysis using a general linear model was conducted to investigate associations between independent variables and NGF (dependent variable) after adjusting for urinary concentration and volume.

RESULTS

We enrolled and analyzed urine samples and pathologic data from 115 subjects. Patient pathology included 24% (n = 28) Gleason score 6 or less, 68% (n = 78) Gleason score 7, and 8% (n = 9) Gleason score 8 or greater. Perineural invasion was more prevalent in higher-grade disease (P<0.001). The median NGF level was 24.1 pg/ml (range: 0.16-270.5 pg/ml) and was transformed to the log base 10 scale. Total bladder volume, urinary creatinine level, prostate-specific antigen level, and diabetes were correlated with the Log NGF. In a general linear model, adjusting for bladder volume and urinary creatinine, increasing Log10 NGF was associated with higher Gleason score (Gleason category ≤6, 7, and ≥8; P = 0.003).

CONCLUSIONS

Urinary NGF may be a biomarker for higher-grade PCa. Our pilot study suggests further investigation is warranted to determine whether urinary NGF could provide unique additional information in patients with PCa.

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.

Novel multi-system functional gains via task specific training in spinal cord injured male rats

Locomotor training (LT) after spinal cord injury (SCI) is a rehabilitative therapy used to enhance locomotor recovery. There is evidence, primarily anecdotal, also associating LT with improvements in bladder function and reduction in some types of SCI-related pain. In the present study, we determined if a step training paradigm could improve outcome measures of locomotion, bladder function, and pain/allodynia. After a T10 contusive SCI trained animals (adult male Wistar rats), trained animals began quadrupedal step training beginning 2 weeks post-SCI for 1 h/day. End of study experiments (3 months of training) revealed significant changes in limb kinematics, gait, and hindlimb flexor-extensor bursting patterns relative to non-trained controls. Importantly, micturition function, evaluated with terminal transvesical cystometry, was significantly improved in the step trained group (increased voiding efficiency, intercontraction interval, and contraction amplitude). Because both SCI and LT affect neurotrophin signaling, and neurotrophins are involved with post-SCI plasticity in micturition pathways, we measured bladder neurotrophin mRNA. Training regulated the expression of nerve growth factor (NGF) but not BDNF or NT3. Bladder NGF mRNA levels were inversely related to bladder function in the trained group. Monitoring of overground locomotion and neuropathic pain throughout the study revealed significant improvements, beginning after 3 weeks of training, which in both cases remained consistent for the study duration. These novel findings, improving non-locomotor in addition to locomotor functions, demonstrate that step training post-SCI could contribute to multiple quality of life gains, targeting patient-centered high priority deficits.

Urinary nerve growth factor in children with overactive bladder: a promising, noninvasive and objective biomarker

OBJECTIVE

This prospective study was designed to determine urinary nerve growth factor (NGF) levels in children with overactive bladder (OAB), and to evaluate whether this factor can be used as a biomarker for diagnosis and monitoring treatment outcome.

PATIENTS AND METHODS

Urinary NGF levels were determined in 40 children with OAB and in a control group of 20 children with no urinary symptoms. Urine samples were collected from the patients prior to and at 3 and 6 months after the beginning of treatment. The total NGF levels (pg/mL) were further normalized to the concentration of urinary creatinine (NGF/Cr level).

RESULTS

Overall, both NGF and NGF/Cr levels were significantly higher at the beginning of the study. Mean NGF levels were 30.75 ± 8.35 and 9.75 ± 2.11 pg/ml (p = 0.023) and mean NGF/Cr levels were 0.53 ± 0.14 and 0.16 ± 0.04 (p = 0.022) in patients and controls, respectively. After 6 months of therapy, the NGF/Cr level was significantly reduced to almost control levels (0.16 ± 0.02, p = 0.047).

CONCLUSION

NGF and NGF/Cr levels were significantly higher in children with OAB than controls at initial evaluation. Furthermore, the NGF/Cr level was significantly reduced following 6 months of therapy. NGF and NGF/Cr levels show promise as reliable biomarkers for OAB diagnosis and to monitor therapy in the pediatric age group.

Neurotrophins in bladder function: what do we know and where do we go from here?

AIMS

Neurotrophins (NTs) have attracted considerable attention in the urologic community. The reason for this resides in the recognition of their ability to induce plastic changes of the neuronal circuits that govern bladder function. In many pathologic states, urinary symptoms, including urgency and urinary frequency, reflect abnormal activity of bladder sensory afferents that results from neuroplastic changes. Accordingly, in pathologies associated with increased sensory input, such as the overactive bladder syndrome (OAB) or bladder pain syndrome/interstitial cystitis (BPS/IC), significant amounts of NTs have been found in the bladder wall.

METHODS

Here, current knowledge about the importance of NTs in bladder function will be reviewed, with a focus on the most well-studied NTs, nerve growth factor (NGF), and brain-derived neurotrophic factor (BDNF).

RESULTS

Both NTs are present in the bladder and regulate bladder sensory afferents and urothelial cells. Experimental models of bladder dysfunction show that upregulation of these NTs is strongly linked to bladder hyperactivity and, in some cases, pain. NT manipulation has been tested in animal models of bladder dysfunction, and recently, NGF downregulation, achieved by administration of a monoclonal antibody, has also been tested in patients with BPS/IC and chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). NTs have also been found in high quantities in the urine of OAB and BPS/IC patients, raising the possibility of NTs serving as biomarkers.

CONCLUSIONS

Available data show that our knowledge of NTs has greatly increased in recent years and that some results may have future clinical application.

Nerve growth factor (NGF): a potential urinary biomarker for overactive bladder syndrome (OAB)?

WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: The search for a biomarker in overactive bladder syndrome (OAB) is an emerging field of interest, as bladder dysfunction is a common complaint that causes significant morbidity. A biomarker may give us insight as a diagnostic tool, and also inform us about how severe the condition is, how it may progress and how it may best be treated. The protein of interest here is nerve growth factor (NGF) and it has been shown to be a dynamic molecule in the bladder of patients with OAB. Urinary levels have been seen to rise in patients with OAB and fall in those who respond to treatment. However, there have also been many studies that examine this trend in numerous other conditions, e.g. interstitial cystitis, bladder outflow obstruction, renal stone disease and patients with neurological impairment after stroke. As a result the specificity of this as a potential urinary biomarker for OAB is questioned. This is a review of published studies, which discusses the pros and cons of NGF as a potential urinary biomarker. The evidence is examined and the studies are summarised together in a Table. Questions remain about the reliability, practicality and specificity of NGF as a biomarker for OAB. These questions need to be addressed by further studies that could clarify the points raised.

OBJECTIVE

To review the current literature on the use of urinary nerve growth factor (NGF) as a potential biomarker for overactive bladder syndrome (OAB).

METHOD

A comprehensive electronic literature search was conducted using the PubMed database to identify publications relating to urinary NGF.

RESULTS

There are a growing number of publications that have measured urinary NGF levels in different types of bladder dysfunction. These range from OAB, bladder pain syndrome, idiopathic and neurogenic detrusor overactivity, bladder oversensitivity and bladder outflow obstruction. Urinary NGF levels do appear to be raised in these pathological states when compared with healthy control samples. In patients with OAB, these raised urinary NGF levels appear to also reduce after successful treatment with antimuscarinics and botulinum toxin A, which indicates a potential use in monitoring responses to treatment. However, raised levels are not limited to OAB, which questions its specificity. Urinary NGF measurements are performed with an enzyme-linked immunosorbent assay using polyclonal antibodies to NGF. The technique requires standardisation, and the different antibodies to NGF require validating. Also a definition of what is the 'normal' range of NGF in urine is still required before it can be used as a diagnostic and prognostic tool.

CONCLUSIONS

Whilst the evidence for an increased urinary NGF in OAB appears convincing, many questions about its validity remain including: specificity, sensitivity, cost- and time-effectiveness. Many criteria for what constitutes a biomarker still need to be evaluated and met before this molecule can be considered for this role.

Increased urine and serum nerve growth factor levels in interstitial cystitis suggest chronic inflammation is involved in the pathogenesis of disease

Objective

Interstitial cystitis/bladder pain syndrome (IC/BPS) is considered a bladder disorder due to localized chronic inflammation. This study investigated the nerve growth factor (NGF) levels in serum and urine in patients with IC/BPS.

Materials and Methods

Thirty patients with IC/BPS and 28 normal subjects without lower urinary tract symptoms were recruited from an outpatient clinic. IC/BPS was diagnosed by frequency, bladder pain, and the presence of glomerulations during cystoscopic hydrodistention. Serum and urine were collected before any treatment was given. Serum NGF and urinary NGF/Cr levels were compared between IC/BPS and the controls.

Results

Urinary NGF levels were significantly higher in patients with IC/PBS (26.3±11.2 pg/ml) than in controls (1.40±0.63 pg) (p = 0.014). After normalization, the urinary NGF/Cr levels were significantly greater in IC/BPS (0.69±0.38 pg/mg) than controls (0.20±0.01, p = 0.011). Relative to the levels in control subjects (1.90±0.38 pg/mL), the mean serum NGF levels were higher in patients IC/BPS patients (3.48±0.55 pg/mL) (p = 0.015). No significant correlation was found between the serum and urinary NGF levels in IC/BPS patients. However, the clinical characteristics and medical co-morbidities did not show significant difference between IC/BPS patients with a higher and lower serum NGF level.

Conclusions

Increased urinary NGF levels in IC/BPS patients suggest that chronic inflammation is involved in this bladder disorder. Increased circulating serum NGF levels were noted in over half of patients with IC/BPS, however, the urinary and serum NGF were not inter-correlated and elevated serum NGF did not relate with clinical features.

Biomarkers in overactive bladder: a new objective and noninvasive tool?

Overactive bladder syndrome (OAB) is a highly prevalent urinary dysfunction, with considerable economic and human costs. Clinical diagnosis of OAB is still based on subjective symptoms. A new accurate, objective and noninvasive test to diagnose OAB and assess therapeutic outcome is lacking. Recent studies in lower urinary tract (LUT) dysfunctions, particularly in OAB patients, indicate that urinary proteins (neurotrophins, prostaglandins, and cytokines), serum C reactive protein, and detrusor wall thickness are altered, and such changes could be used as biomarkers of the disease. Nowadays, increasing emphasis has been given to the role of urinary neurotrophins, namely nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF), as key players in some urinary dysfunctions. Although recently considered to be a bladder dysfunction biomarker, urinary NGF presents low sensitivity and specificity. Preliminary results suggest that BDNF may serve as a more efficient biomarker. Even though we have to wait for future studies to confirm the potential role of NGF and BDNF as OAB biomarkers, it is already clear that neurotrophins will contribute to elucidate the physiopathological basis of OAB. Herein are reviewed the latest advances in this new and exciting field, the detection and clinical application of emerging OAB biomarkers.

Effect of hyaluronic acid on urine nerve growth factor in cyclophosphamide-induced cystitis

OBJECTIVES

To investigate how hyaluronic acid (HA) affects nerve growth factor (NGF) production and bladder overactivity in a cyclophosphamide (CYP)-induced cystitis rat model.

METHODS

Female Sprague-Dawley rats received three intermittent intraperitoneal injections of CYP (75 mg/kg) or saline. Before or after CYP injection, HA was given intravesically and urine NGF was checked with creatinine correction. Bladder function was evaluated by cystometrograms under Zoletil anesthesia. Furthermore, the effect of HA was counteracted with hyaluronidase (HYAL). Bladder structural change was compared among groups with trichrome stain.

RESULTS

The intercontraction interval (ICI) significantly decreased in CYP-injected rats in comparison to the saline-injected controls. In the CYP-injected groups, bladder HA instillation significantly increased the ICI, but did not change the maximum voiding pressure in comparison to the saline instillation. NGF production significantly increased in CYP-injected rats, but decreased significantly with HA treatment. Treatment with HA had a more significant effect on urine NGF and the use of HYAL would eliminate this effect. Specific staining showed mucosa swelling after CYP treatment. Little HA coating on bladder mucosa could be found in HA-treated rats.

CONCLUSIONS

Present findings raise the possibility that HA could be an effective treatment for CYP-related bladder overactivity through the involvement of NGF signaling.

Promise of Urinary Nerve Growth Factor for Assessment of Overactive Bladder Syndrome

Overactive bladder syndrome (OAB) is highly prevalent bladder disorder in men and women. About 10-15% of the population suffers from urgency frequency with or without urgency urinary incontinence. It is estimated that 50-75% of patients with OAB may have urodynamic detrusor overactivity (DO). Urodynamic study invasive and most of the OAB patients might not accept it as a routine assessment. Therefore, a more objective and non-invasive test for diagnosis and assessing DO from OAB patients is needed. Recently, urinary nerve growth factor (NGF) has gained great interest in detecting DO in patients with OAB. Urinary NGF level was found to increase in OAB and urodynamic DO. Urinary NGF levels correlated with severity of OAB symptoms. Patients with either idiopathic or neurogenic DO may have increased urinary NGF levels. Urinary NGF levels have been shown to decrease in patients with patients with OAB and DO who have been well treated with antimuscarinics or botulinum toxin injection, but not in those with persistent OAB after treatment. Not all patients with OAB can have an elevated urinary NGF level; it may also be increased in patients with interstitial cystitis/painful bladder syndrome and other lower urinary tract diseases, suggesting urinary NGF expression could be a product of bladder inflammation and a limited specificity of urinary NGF for diagnosing DO. The source of urinary NGF has not yet been fully explored yet. Nevertheless, urinary NGF level is likely to be a promising biomarker for diagnosis of DO from OAB patients, to monitor therapeutic outcome and predict disease progression.

Urinary Nerve Growth Factor Levels in Urinary Tract Diseases With or Without Frequency Urgency Symptoms

OBJECTIVES

To measure urinary nerve growth factor (NGF) levels in patients with several urinary tract diseases under different conditions and compare with NGF levels in patients with overactive bladder (OAB) and interstitial cystitis/painful bladder syndrome (IC/PBS).

METHODS

Urinary NGF levels were measured using enzyme-linked immunosorbent assay (ELISA) and normalized by urinary creatinine concentration. Patients with acute bacterial cystitis, urinary tract stone, urothelial cell carcinoma, and OAB patients after antimuscarinic therapy were evaluated. The urinary NGF levels of OAB, IC/PBS and controls from previous studies were used for comparison. NGF levels were compared among subgroups and between urinary tract diseases with or without associated OAB symptoms. The urinary NGF levels were also compared among natural filling, after normal saline filling and after potassium chloride test in a group of OAB and IC/PBS patients.

RESULTS

Patients with acute bacterial cystitis, urinary tract stones or urothelial cell carcinoma had elevated NGF levels that were not associated with the presence of OAB symptoms. Symptomatic cystitis patients who had resolved OAB symptoms after antibiotic treatment had a significant decrease in urinary NGF levels. The urinary NGF levels decreased significantly in OAB patients with effective antimuscarinic treatment for 6 months, but remained stationary and higher than the controls for up to 12 months after treatment.

CONCLUSION

Urinary NGF is not produced solely in patients with OAB or IC/PBS. Acute bacterial cystitis, urinary tract stones and urothelial cell carcinoma can have high urinary NGF production.

Increased cannabinoid receptor 1-immunoreactive nerve fibers in overactive and painful bladder disorders and their correlation with symptoms

OBJECTIVE

To study the expression of cannabinoid receptor 1 (CB1) in human urinary bladder hypersensitivity and overactivity disorders, and correlate changes with symptoms. Cannabinoid receptor agonists have been shown to modulate urinary bladder contractility and reduce pain after bladder inflammation; their clinical efficacy on lower urinary tract symptoms was demonstrated in the Cannabinoids in Multiple Sclerosis study.

METHODS

Bladder tissue specimens were obtained from patients with painful bladder syndrome (PBS, n=13), idiopathic detrusor overactivity (IDO, n=14), and from controls with asymptomatic microscopic hematuria (n=16). The severity of symptoms was assessed using the Pelvic Pain and Urgency/Frequency Questionnaire. Pain score was also recorded on a visual analogue scale. Specimens were immunostained using specific antibodies to CB1 and to neurofilaments as a structural maker. Detrusor and suburothelial nerve fiber density was quantified with a visual grading scale. The immunohistochemistry results were correlated with "Pain, Frequency, and Urgency" scores.

RESULTS

CB1-immunoreative nerve fibers were significantly increased in the suburothelium of PBS (P=.0123) and IDO (P=.0013) specimens, and in detrusor layer in IDO (P=.0003), as compared with controls. CB1-immunoreactive suburothelial nerve fiber density correlated significantly with pain scores (Visual Analogue Scale) in PBS (r=.6878, P=.0347) and urgency scores in IDO (r=.6623, P=.0027). Neurofilaments-immunoreactive suburothelial nerve fibers were significantly increased in PBS (P=.019) and IDO (P=.05).

CONCLUSIONS

The results of this study suggest that increased nerve fibers, which express CB1, may be related to bladder pain in PBS and urgency in IDO. Our findings support clinical trials of CB1 agonists in bladder disorders.

Overexpression of NGF in mouse urothelium leads to neuronal hyperinnervation, pelvic sensitivity, and changes in urinary bladder function

NGF has been suggested to play a role in urinary bladder dysfunction by mediating inflammation, as well as morphological and functional changes, in sensory and sympathetic neurons innervating the urinary bladder. To further explore the role of NGF in bladder sensory function, we generated a transgenic mouse model of chronic NGF overexpression in the bladder using the urothelium-specific uroplakin II (UPII) promoter. NGF mRNA and protein were expressed at higher levels in the bladders of NGF-overexpressing (NGF-OE) transgenic mice compared with wild-type littermate controls from postnatal day 7 through 12-16 wk of age. Overexpression of NGF led to urinary bladder enlargement characterized by marked nerve fiber hyperplasia in the submucosa and detrusor smooth muscle and elevated numbers of tissue mast cells. There was a marked increase in the density of CGRP- and substance P-positive C-fiber sensory afferents, neurofilament 200-positive myelinated sensory afferents, and tyrosine hydroxylase-positive sympathetic nerve fibers in the suburothelial nerve plexus. CGRP-positive ganglia were also present in the urinary bladders of transgenic mice. Transgenic mice had reduced urinary bladder capacity and an increase in the number and amplitude of nonvoiding bladder contractions under baseline conditions in conscious open-voiding cystometry. These changes in urinary bladder function were further associated with an increased referred somatic pelvic hypersensitivity. Thus, chronic urothelial NGF overexpression in transgenic mice leads to neuronal proliferation, focal increases in urinary bladder mast cells, increased urinary bladder reflex activity, and pelvic hypersensitivity. NGF-overexpressing mice may, therefore, provide a useful transgenic model for exploring the role of NGF in urinary bladder dysfunction.

Multiple sclerosis produces significant changes in urinary bladder innervation which are partially reflected in the lower urinary tract functional status-sensory nerve fibers role in detrusor overactivity

BACKGROUND

Detrusor overactivity is often observed in patients with multiple sclerosis (MS), and neurotoxins are emerging as second-line therapies albeit with different degrees of success per patient basis.

OBJECTIVE

To investigate lower urinary tract (LUT) functional status and bladder innervation (calcitonin gene related peptide [CGRP] and substance P [SP] positive nerve fibers) in patients with MS.

METHOD

Eighteen MS patients with LUT symptoms underwent urodynamic investigations, and six non-MS patients undergoing cystoscopy due to microscopic hematuria served as controls. Cold cut bladder biopsies were taken from the bladder trigone region. Neurotransmitter expression was determined by individual immunohistochemical staining.

RESULTS

Two distinct groups could be distinguished: group 1 with pronounced neurogenic detrusor overactivity and mild outflow obstruction; group 2 with some degree of neurogenic detrusor overactivity, detrusor hypocontractility during voiding, and high degree of an outflow obstruction. The presence of SP and CGRP immunoreactive + fiber density was observed in greater numbers in group 1.

CONCLUSION

Density of CGRP and SP positive nerve fibers within the urinary bladder of patients with MS may be suggestive of functional status of the lower urinary tract, namely denser innervation is observed in patients with mild outflow obstruction and strong detrusor overactivity. This observation could be useful when planning second-line treatment (neurotoxins) in these patients. Patients with denser innervation probably will respond better to such a therapy.

Urinary nerve growth factor level is increased in patients with interstitial cystitis/bladder pain syndrome and decreased in responders to treatment

OBJECTIVE

To measure urinary nerve growth factor (NGF) levels in patients with interstitial cystitis/bladder pain syndrome (IC/BPS), and to evaluate the role of urinary NGF in predicting the response to treatment, as the clinical diagnosis of IC/BPS is based on subjective symptoms and recent investigations suggest that urinary NGF is increased in patients with IC/BPS.

PATIENTS, SUBJECTS AND METHODS

Urine samples from 122 patients with IC/BPS and 28 normal controls were measured for NGF levels using an enzyme-linked immunosorbent assay. The diagnosis of IC/BPS was based on bladder pain symptoms and the results of cystoscopic hydrodistension. Patients' perception of pain was assessed by a visual analogue scale (VAS) and a 'global' response assessment after treatment. Urinary NGF levels were further normalized to the concentration of urinary creatinine (NGF/Cr) and compared between control and IC/BPS subgroups at diagnosis and after treatment.

RESULTS

Urinary NGF/Cr levels were very low when the bladder was not distended and significantly elevated with a full bladder in patients with IC/BPS. However, urinary NGF/Cr levels were not correlated with VAS scores or cystometric bladder capacity at diagnosis, or maximum bladder capacity during hydrodistension. Patients who responded to treatment and had an improvement in VAS pain score of > or =2 had significantly lower NGF/Cr levels than nonresponders who had a VAS improvement of <2.

CONCLUSIONS

Patients with IC/BPS had greater urinary NGF/Cr levels than controls. A decrease of urinary NGF level was associated with greater pain reduction and a successful response, suggesting that urinary NGF levels can be a useful biomarker for detecting the severity of the bladder condition in patients with IC/BPS.