Long-lasting breaches in the bladder epithelium lead to storage dysfunction with increase in bladder PGE2 levels in the rat

Update on Overactive Bladder Therapeutic Options

BACKGROUND

Millions of Americans are burdened by overactive bladder (OAB) syndrome and the psychogenic and economic hardships that accompany it. Several theories attempt to explain OAB as a neurogenic dysfunction, myogenic dysfunction, urothelial dysfunction, or decreased expression of a channel protein secondary to bladder outlet obstruction. Given that the etiology of OAB is a working theory, the management of OAB is also an evolving subject matter in medicine. There are uncertainties surrounding the pathophysiology of OAB, the strength of a clinical diagnosis, and accurate reporting because of the disease's stigma and decreased use of health care.

DATA SOURCES

This is a narrative review that used PubMed, Google Scholar, Medline, and ScienceDirect to review literature on current and future OAB therapies.

RESULTS

Currently, first-line treatment for OAB is behavioral therapy that uses lifestyle modifications, bladder-control techniques, and psychotherapy. Second-line therapy includes antimuscarinic agents or beta 3 adrenergic agonists, and studies have shown that combination therapy with antimuscarinics and beta 3 adrenergic agonists provides even greater efficacy than monotherapy. Third-line therapies discussed include onabotulinumtoxinA, posterior tibial nerve stimulation, and sacral neuromodulation. OnabotulinumtoxinA has been FDA-approved as a nonpharmaceutical treatment option for refractory OAB with minimal side effects restricted to the urinary tract. Posterior tibial nerve modulation and sacral neuromodulation are successful in treating refractory OAB, but the costs and complication rates make them high-risk procedures. Therefore, surgical intervention should be a last resort. Estrogen therapy is effective in alleviating urinary incontinence in postmenopausal women, consistent with the association between estrogen deficiency and genitourinary syndrome. Potassium channel activators, voltage-gated calcium channel blockers, and phosphodiesterase inhibitors look to be promising options for the future of OAB management. As new therapies are developed, individuals with OAB can better personalize their treatment to maximize their quality of life and cost-effective care.

Urogynaecology and Ehlers-Danlos syndrome

Ehlers-Danlos syndrome (EDS) can lead to a presentation to urogynaecology services with multiple symptoms including vaginal prolapse, overactive bladder symptoms, voiding dysfunction, bladder pain syndrome, recurrent urinary tracts infections, stress urinary incontinence, recurring bladder diverticula, vesicoureteral reflux, pelvic floor pain or spasms, and complicated postnatal perineal wounds. This article explores the pathophysiology of these conditions in causing urinary urgency, incontinence, and infections; highlighting the key investigations and management considerations for women with EDS including conservative, pharmacological, and surgical.

Urinary biomarkers in patients with detrusor underactivity with and without bladder function recovery

PURPOSE

Detrusor underactivity (DU) is frequently encountered in elderly patients. Part of patients with DU might have bladder function recovery after treatment. This study investigated urinary proteins in these DU patients with and without bladder function recovery.

METHODS

A total of 37 patients with chronic urinary retention and urodynamically proven DU were enrolled. After treatment, 24 DU patients had bladder function recovery whereas 13 had not, after 1-year follow-up. Urine collection at baseline was performed, and the urinary protein including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and prostaglandin E2 (PGE2) were measured by ELISA. Twenty urodynamically normal, 34 detrusor overactivity (DO) and 15 detrusor hyperactivity and inadequate contractility (DHIC) patients served as comparative groups.

RESULTS

Urinary NGF levels were significantly higher than normal in patients with DU (9.2 ± 20.3 vs 1.85 ± 2.9 pg/ml, p = 0.037). Urinary BDNF level was only significantly higher in patients with DU than that of the control group (153 ± 199 vs 77.4 ± 47.7 pg/ml, p = 0.033) but not in patients with DHIC or DO. Compared with the control group, the urinary BDNF level was significantly higher in DU patients with bladder function recovery (190 ± 239 pg/ml, p = 0.033) but not in patients without recovery (85.8 ± 43.7 pg/ml, p = 0.612). The PGE2 level was significantly higher than the control group in DU patients with bladder function recovery (1290 ± 836 pg/ml, p < 0.0001) but not in patients without recovery (383 ± 237 pg/ml, p = 0.130).

CONCLUSION

Patients with DU and higher urinary PGE2 and BDNF levels might have a chance to recover bladder function than those with a lower protein level.

In the absence of overt urothelial damage, chondroitinase ABC digestion of the GAG layer increases bladder permeability in ovariectomized female rats

Loss of integrity of the protective impermeability barrier in the urothelium has been identified as significant in bladder dysfunction. In this study, we tested the theory that the luminal layer of glycosaminoglycans (GAG) serves as an important component of barrier function. The peptide polycation protamine sulfate (PS), 1 mg/ml, was instilled intravesically for 10 min into rat bladders. Chondroitinase ABC (ChABC), 63 IU/ml, was instilled into an additional six rats for 30 min to digest the GAG layer. Unmanipulated controls and sham-injected controls were also performed. After 24 h, the rats were euthanized, the bladders were removed, and permeability was assessed in the Ussing chamber and by diffusion of FITC-labeled dextran (4 kDa) to measure macromolecular permeability. The status of tight junctions was assessed by immunofluorescence and electron microscopy. In control and sham treated rat bladders, the transepithelial electrical resistance were means of 2.5 ± 1.1 vs. 2.6 ± 1.1 vs 1.2 ± 0.5 and 1.01 ± 0.7 kΩ·cm(2) in the PS-treated and ChABC-treated rat bladders (P = 0.0016 and P = 0.0039, respectively). Similar differences were seen in dextran permeability. Histopathology showed a mild inflammation following PS treatment, but the ChABC-treated bladders were indistinguishable from controls. Tight junctions generally remained intact. ChABC digestion alone induced bladder permeability, confirming the importance of the GAG layer to bladder barrier function and supports that loss of the GAG layer seen in bladder biopsies of interstitial cystitis patients could be a significant factor producing symptoms for at least some interstitial cystitis/painful bladder syndrome patients.

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.

Potential Biomarkers Utilized to Define and Manage Overactive Bladder Syndrome

Clinical diagnosis of overactive bladder (OAB) syndrome has great variation and usually can only be based on subjective symptoms. Measurement of urgency severity score in adjunct with voiding diary may reflect the occurrence of OAB and incontinence severity in daily life. Urodynamic study can detect detrusor overactivity (DO), but not in all OAB patients. A more objective way and less invasive tool to diagnose and assess therapeutic outcome in OAB patients is needed. Recent investigations of the potential biomarkers for OAB include urinary and serum biomarkers and bladder wall thickness. Evidence has also shown that urinary proteins, such as nerve growth factor (NGF) and prostaglandin E2 (PGE2 ) levels increase in patients with OAB, bladder outlet obstruction (BOO) and DO. Patients with OAB have significantly higher urinary NGFlevels and urinary NGF levels decrease after antimuscarinic therapy and further decrease after detrusor botulinum toxin injections. However, the sensitivity of single urinary protein in the diagnosis of OAB is not high and several lower urinary tract diseases may also have elevated urinary NGF levels. Searching for a group of inflammatory biomarkers by microsphere-based array in urine might be a better method in differential diagnosis of OAB from interstitial cystitis, urinary tract infection (UTI) or urolithiasis. Bladder wall thickness has been widely investigated in the diagnosis of BOO and pediatric voiding dysfunction.The role of bladder wall thickness in the diagnosis of OAB, however, has not reach a consistent conclusion. We hereby review the latest medical advances in this field.

A new concept of endometriosis and adenomyosis: tissue injury and repair (TIAR)

Pelvic endometriosis, deeply infiltrating endometriosis and uterine adenomyosis share a common pathophysiology and may be integrated into the physiological mechanism and new nosological concept of 'tissue injury and repair' (TIAR) and may, in this context, just represent the extreme of a basically physiological, estrogen-related mechanism that is pathologically exaggerated in an extremely estrogen-sensitive reproductive organ. The acronym TIAR describes a fundamental and apparently ubiquitous biological system that becomes operative in mesenchymal tissues following tissue injury and, upon activation, results in the local production of estradiol. Endometriosis and adenomyosis are caused by trauma. In the spontaneously developing disease, chronic uterine peristaltic activity or phases of hyperperistalsis induce, at the endometrial-myometrial interface near the fundo-cornual raphe, microtraumatisations, with activation of the TIAR mechanism. With ongoing traumatisations, such sites of inflammation might accumulate and the increasingly produced estrogens interfere in a paracrine fashion with ovarian control over uterine peristaltic activity, resulting in permanent hyperperistalsis and a self-perpetuation of the disease process. Overt autotraumatisation of the uterus with dislocation of fragments of basal endometrium into the peritoneal cavity and infiltration of basal endometrium into the depth of the myometrial wall ensues. In most cases of endometriosis/adenomyosis a causal event early in the reproductive period of life must be postulated, rapidly leading to archimetral hyperestrogenism and uterine hyperperistalsis. In late premenopausal adenomyosis such an event might not have occurred. However, as indicated by the high prevalence of the disease, it appears to be unavoidable that, with time, chronic normoperistalsis throughout the reproductive period of life accumulates to the same extent of microtraumatisation. With activation of the TIAR mechanism followed by chronic inflammation and infiltrative growth, endometriosis/adenomyosis of the younger woman and premenopausal adenomyosis share in principal the same pathophysiology.

Chronic Pelvic Ischemia: Contribution to the Pathogenesis of Lower Urinary Tract Symptoms (LUTS): A New Target for Pharmacological Treatment?

The incidence of lower urinary tract symptoms, including overactive bladder (OAB), is continuing to rise, and is associated with a negative impact on quality of life and a heavy economic burden. A major risk factor for OAB is advancing age. The etiology of OAB is multifactorial and appears to involve myogenic, neurogenic, and urotheliogenic factors. In this article, we review the strengthening preclinical evidence supporting the contribution of chronic pelvic ischemia to the pathogenesis of OAB. In animal models, chronic ischemia induced by arterial injury and a high-fat diet upregulates markers of oxidative stress and proinflammatory cytokines in the urothelium and lamina propria, and leads to increased expression of nerve growth factor. These processes result in increased afferent activity and an increased frequency of micturition, reflecting a state of bladder hyperactivity. In severe, prolonged cases, bladder overactivity may develop into underactivity. Antimuscarinic therapies are the mainstay of OAB treatment, but their usefulness is limited by modest efficacy and troublesome side-effects. Our increasing understanding of the contribution of chronic ischemia to OAB is leading toward novel therapeutic options targeting chronic pelvic ischemia and its morphological, functional, and oxidative consequences. Preclinical trials have demonstrated encouraging results with α1 -adrenoreceptor blockade, phosphodiesterase type 5 inhibition, β3 -adrenoreceptor agonism, free radical scavenging, and stem cell therapy, in preventing morphological, biochemical and functional changes induced by chronic bladder ischemia.

Changes in prostaglandin E2 in patients with idiopathic overactive bladder syndrome after botulinum toxin type A treatment: is there a clinical benefit?

BACKGROUND

The causality of overactive bladder syndrome (OAB) is still not fully understood. Several studies indicate a significant increase of prostaglandin E2 (PGE2) in patients with OAB. However, in order to clarify whether these compounds can help to objectify the clinical diagnosis, further studies are needed. This prospective study aims to analyze PGE2 blood levels (sPGE2) in patients with OAB before and after botulinum toxin type A (BoNT-A) therapy.

METHODS

Blood samples were obtained from 56 patients (52y, 18-87) with idiopathic OAB. sPGE2 levels were measured before and 4 weeks after BoNT-A treatment by enzyme linked immunosorbent assay (ELISA). 31 healthy persons with normal bladder function served as control group (59 y, 21-72). sPGE2 was set in relation to clinical data and the severity of OAB (wet/dry). The statistical data analysis was performed by using the non-parametric Mann-Whitney U test and paired t-test.

RESULTS

Significant higher sPGE2 levels were detected in patients with OAB compared to members of the control group (2750 pg/ml vs. 1674 pg/ml, p < 0.005). Furthermore sPGE2 levels were increased in patients with OAB wet compared to OAB dry (p <0.01). In 30 patients sPGE2 levels decreased significantly after BoNT-A treatment compared to baseline (2995 pg/ml vs. 1486 pg/ml, p <0.005). Patients reported an average drug effect of 9 month (0-19); incontinence pads were needed significantly less frequent (p < 0.05). 3 patients reported no postoperative effect. sPGE2 increased in two patients compared to initial levels, a single patient showed a remotely decreased sPGE2. Six patients were treated repeatedly with BoNT-A after showing an sPGE2 re-rise.

CONCLUSIONS

sPGE2-level is increased in patients with OAB. We could prove a significant decrease of sPGE2 after BoNT-A treatment. In this small cohort we could demonstrate a correlation between OAB and sPGE2, especially in the non-responder group. The use of sPGE2 as a biomarker in diagnostics and follow-up after therapy seems promising. To what extent sPGE2 can be useful as such needs to be examined prospectively in a larger population.

Novel biomarkers for overactive bladder

Biomarkers constitute any objectively measurable indicator of a biological process. The classic biomarker used in the diagnosis of overactive bladder (OAB) has been detrusor overactivity, which is assessed urodynamically. In the search for a reliable, noninvasive alternative to urodynamics, interest has focused on genetic, imaging, and urinary factors. Along with other cytokines detectable in urine, prostaglandin E2 and nerve growth factor are indicators of low-grade inflammation. Although they correlate with OAB symptom severity, they have not been shown to have independent prognostic benefit. Imaging biomarkers have been investigated since the earliest days of video urodynamics. Despite extensive research on the ultrasonographic estimation of bladder wall thickness, further standardization of the technique is required before conclusions can be reached regarding diagnostic accuracy. Genetic factors contribute approximately half of the total risk for urgency incontinence. Functional polymorphisms of the cytochrome P450 IID6 gene significantly alter the metabolism of some commonly used anticholinergic drugs, but no genetic loci that influence risk of OAB have been definitively identified. The first genome-wide association studies for OAB are in progress, and should identify new susceptibility genes. Although current putative biomarkers correlate with OAB severity, much future work is required to assess their prognostic value, and establish their role in clinical practice.

Effects of the gonadotropin-releasing hormone antagonist ganirelix on normal micturition and prostaglandin E(2)-induced detrusor overactivity in conscious female rats

BACKGROUND

Gonadotropin-releasing hormone (GnRH) antagonists have been reported to have beneficial effects on lower urinary tract symptoms in patients with benign prostatic hyperplasia.

OBJECTIVE

Our aim was to investigate the effects of ganirelix, a GnRH receptor antagonist, on bladder function and detrusor overactivity (DO) in female rats.

DESIGN, SETTING, AND PARTICIPANTS

Female Sprague-Dawley rats received 2 wk of daily systemic (0.1 mg/kg) or acute intravesical administration (IVES; 0.14 mg/l or 1.4 mg/l) ganirelix or vehicle (controls).

MEASUREMENTS

Assessments were obtained using cystometry in awake rats, organ bath studies, enzyme-linked immunosorbent assay, and western blot (WB).

RESULTS AND LIMITATIONS

Luteinising hormone levels were lower in rats treated systemically with ganirelix than in controls. No differences were observed in body or bladder weights. Micturition interval (MI), micturition volume (MV), residual volume, and bladder capacity (BC) were similar in both groups at baseline. No differences in urodynamic pressure parameters were observed between groups at baseline. Intravesical prostaglandin E(2) reduced MI, MV, and BC, and it increased basal pressure (BP), threshold pressure (TP), flow pressure (FP), and maximum pressure (MP) in all rats. MI, MV, and BC were reduced by 43%±4%, 50%±4%, and 43%±4% (controls) versus 22%±3%, 23%±3%, and 21%±3% (ganirelix-treated rats; p<0.001). TP and FP increased by 38%±8% and 30%±4% (controls) versus 16%±7% and 16%±5% (ganirelix; p<0.05). The maximal force of contractions for carbachol was larger in detrusor from ganirelix-treated rats (231% vs 177% of 60 mM K+-induced contractions). At 0.14 mg/l, but not 0.14 mg/l, IVES ganirelix increased MI, MV, and BC and decreased BP, TP, FP, and MP. In vitro, ganirelix had no effect on detrusor function. The gonadotropin-releasing hormone receptor was expressed (by WB) in the bladder mucosa.

CONCLUSIONS

Systemic treatment with ganirelix counteracted experimental DO in female rats. Because bladder preparations from these rats exhibited larger contractions to carbachol and because intravesical ganirelix affected both micturition intervals and urodynamic pressure profiles, a peripheral site of action of ganirelix in the urinary bladder cannot be excluded.

The pathophysiology of endometriosis and adenomyosis: tissue injury and repair

INTRODUCTION

This study presents a unifying concept of the pathophysiology of endometriosis and adenomyosis. In particular, a physiological model is proposed that provides a comprehensive explanation of the local production of estrogen at the level of ectopic endometrial lesions and the endometrium of women affected with the disease.

METHODS

In women suffering from endometriosis and adenomyosis and in normal controls, a critical analysis of uterine morphology and function was performed using immunohistochemistry, MRI, hysterosalpingoscintigraphy, videohysterosonography, molecular biology as well as clinical aspects. The relevant molecular biologic aspects were compared to those of tissue injury and repair (TIAR) mechanisms reported in literature.

RESULTS AND CONCLUSIONS

Circumstantial evidence suggests that endometriosis and adenomyosis are caused by trauma. In the spontaneously developing disease, chronic uterine peristaltic activity or phases of hyperperistalsis induce, at the endometrial-myometrial interface near the fundo-cornual raphe, microtraumatizations with the activation of the mechanism of 'tissue injury and repair' (TIAR). This results in the local production of estrogen. With ongoing peristaltic activity, such sites might increase and the increasingly produced estrogens interfere in a paracrine fashion with the ovarian control over uterine peristaltic activity, resulting in permanent hyperperistalsis and a self-perpetuation of the disease process. Overt auto-traumatization of the uterus with dislocation of fragments of basal endometrium into the peritoneal cavity and infiltration of basal endometrium into the depth of the myometrial wall ensues. In most cases of endometriosis/adenomyosis, a causal event early in the reproductive period of life must be postulated leading rapidly to uterine hyperperistalsis. In late premenopausal adenomyosis, such an event might not have occurred. However, as indicated by the high prevalence of the disease, it appears to be unavoidable that, with time, chronic normoperistalsis throughout the reproductive period of life leads to the same extent of microtraumatization. With the activation of the TIAR mechanism followed by infiltrative growth and chronic inflammation, endometriosis/adenomyosis of the younger woman and premenopausal adenomyosis share in principle the same pathophysiology. In conclusion, endometriosis and adenomyosis result from the physiological mechanism of 'tissue injury and repair' (TIAR) involving local estrogen production in an estrogen-sensitive environment normally controlled by the ovary.