Drug Insight: biological effects of botulinum toxin A in the lower urinary tract. ACTA ACUST UNITED AC. 2008;5:319-328. [PMID: 18461049 DOI: 10.1038/ncpuro1124]

Clinical Conditions Targeted by OnabotulinumtoxinA in Different Ways in Medicine

OnabotulinumtoxinA (BT-A) is used in different medical fields for its beneficial effects. BT-A, a toxin originally produced by the bacterium Clostridium botulinum, is widely known for its ability to temporarily paralyze muscles by blocking the release of acetylcholine, a neurotransmitter involved in muscle contraction. The literature continually reports new hypotheses regarding potential applications that do not consider blockade of acetylcholine release at the neuromuscular junction as a common pathway. In this opinion article, it is our aim to investigate the different pathway targets of BT-A in different medical applications. First of all, the acetylcholine effect of BT-A is used to reduce wrinkles for cosmetic purposes, in the treatment of urological problems, excessive sweating, temporomandibular joint disorders, obesity, migraine, spasticity in neurological diseases, and in various cases of muscle overactivity such as cervical dystonia, blepharospasm, and essential head tremor. In another potential pathway, glutamate A, CGRP, and substance P are targeted for pain inhibition with BT-A application in conditions such as migraine, trigeminal neuralgia, neuropathic pain, and myofascial pain syndrome. On the other hand, as a mechanism different from acetylcholine and pain mediators, BT-A is used in the treatment of hair loss by increasing oxygenation and targeting transforming growth factor-beta 1 cells. In addition, the effect of BT-A on the apoptosis of cancer cells is also known and is being developed. The benefits of BT-A applied in different doses to different regions for different medical purposes are shown in literature studies, and it is also emphasized in those studies that repeating the applications increases the benefits in the long term. The use of BT-A continues to expand as researchers discover new potential therapeutic uses for this versatile toxin.

Evaluation of Botox treatment in patients with chronic scrotal pain: Protocol for a randomized double-blinded control trial

Background

Chronic scrotal pain is a common condition with a prevalence of 2.5-4.8% in male outpatients. Up to 40% of these patients report depressive symptoms and many feel isolated. Minimal invasive treatment is lacking, while spermatic cord injections of Botox® (BTX) have been proposed to offer long-term pain relief.

Study Design

This research protocol comprises a prospective multicentre, randomized, double-blinded clinical trial drawing patients from other urological departments in the region of Southern Denmark.

End Points

The primary end point will be reduction in pain evaluated by visual analogue score for pain at 3 months. Secondary end point will be length of effect of BTX injections along with changes in quality of life.

Patients and Methods

The study will include 50 patients for randomization to either spermatic cord block with 100 IE BTX or sterile saline. All patients will prior to randomization undergo physical examination and will be asked to fulfil multiple questionnaires regarding pain and impact in daily life, that is, (1) visual analogue score for pain, (2) quality of life (EQ-5D-5L), (3) Chronic Prostatitis Symptom Index (NIH-CPSI), (4) ICD-10 depression questionnaire (MDI), (5) Likert global assessment scale, and (6) International Index of Erectile Function questionnaire. Physical examination and fulfilment of the questionnaires will be repeated multiple times throughout the study period of 12 weeks. After this time point, patients will be unblinded, and the control arm will be given the opportunity of cross-over.

Pathophysiology of Overactive Bladder and Pharmacologic Treatments Including β3-Adrenoceptor Agonists -Basic Research Perspectives

Overactive bladder (OAB) is a symptom-based syndrome defined by urinary urgency, frequency, and nocturia with or without urge incontinence. The causative pathology is diverse; including bladder outlet obstruction (BOO), bladder ischemia, aging, metabolic syndrome, psychological stress, affective disorder, urinary microbiome, localized and systemic inflammatory responses, etc. Several hypotheses have been suggested as mechanisms of OAB generation; among them, neurogenic, myogenic, and urothelial mechanisms are well-known hypotheses. Also, a series of local signals called autonomous myogenic contraction, micromotion, or afferent noises, which can occur during bladder filling, may be induced by the leak of acetylcholine (ACh) or urothelial release of adenosine triphosphate (ATP). They can be transmitted to the central nervous system through afferent fibers to trigger coordinated urgency-related detrusor contractions. Antimuscarinics, commonly known to induce smooth muscle relaxation by competitive blockage of muscarinic receptors in the parasympathetic postganglionic nerve, have a minimal effect on detrusor contraction within therapeutic doses. In fact, they have a predominant role in preventing signals in the afferent nerve transmission process. β3-adrenergic receptor (AR) agonists inhibit afferent signals by predominant inhibition of mechanosensitive Aδ-fibers in the normal bladder. However, in pathologic conditions such as spinal cord injury, it seems to inhibit capsaicin-sensitive C-fibers. Particularly, mirabegron, a β3-agonist, prevents ACh release in the BOO-induced detrusor overactivity model by parasympathetic prejunctional mechanisms. A recent study also revealed that vibegron may have 2 mechanisms of action: inhibition of ACh from cholinergic efferent nerves in the detrusor and afferent inhibition via urothelial β3-AR.

An evaluation of onobotulinumtoxinA as a therapeutic option for pediatric neurogenic detrusor overactivity

INTRODUCTION

Neurogenic detrusor overactivity (NDO) results in involuntary detrusor contractions during bladder filling or storage risking transmission of pressure to the upper urinary tracts and/or significant incontinence. The goals of bladder management in children with NDO prioritize the preservation of renal function, prevention of UTIs, and optimizing quality of life. First-line measures include intermittent catheterization and anticholinergic medication. However, when conservative measures fail, surgical intervention may be indicated. Historically, the next step was major reconstructive surgery to create a low-pressure urinary reservoir. The introduction of intravesical botulinum neurotoxin A (BoNT/A) for use in children in 2002 offered a less invasive option for management. However, its exact role is still evolving.

AREAS COVERED

This article summarizes the mechanism of action of BoNT/A for management of NDO and evaluates the current literature defining common practice and clinical efficacy in children with NDO. The findings of the recently completed phase III trial for intravesical onabotulinumtoxinA in children are discussed in detail.

EXPERT OPINION

As the first BoNT/A approved for use in children with NDO, onabotulinumtoxinA appears to be a safe and less invasive alternative to major reconstructive surgery. However, data defining appropriate patient selection and its role as a long-term treatment option continue to develop.

Current approaches for the treatment of ketamine-induced cystitis

AIMS

Ketamine is a dissociative anesthetic, historically used in a clinical setting for the induction and maintenance of anesthesia. Ketamine usage can produce undesirable psychological manifestations including hallucinations and long-term psychotomimetic effects. As a results of its fast onset and short period of action, ketamine is widely used as a recreational drug. Chronic abuse of ketamine can lead to significant urinary system complications including ketamine-induced cystitis (KIC). Common side effects of chronic ketamine abuse are urinary pain and discomfort and decreased bladder compliance and voiding pressure. Cessation of ketamine use is associated with improvement of symptoms however the exact pathophysiology of KIC remains unknown, complicating the ability of clinicians to treat this condition.

METHOD

A literature search was performed using the National Center for Biotechnology Information (NCBI) Pubmed database up to May 2021.

RESULTS

Animal models of KIC are necessary to further our understanding of KIC pathophysiology and explore potential treatment options. In all cases, cessation of ketamine use is the first line of treatment and is most effective in managing KIC. In addition to cessation, treatment plans must be tailored to the individual, based on the severity of symptoms and disease progression, and include options such as: oral anti-inflammatories, intravesical treatment and in the most severe cases, surgical intervention.

CONCLUSION

KIC is a painful condition that currently lacks standardized treatment methods. Both animal models of KIC and clinical trials to further elucidate the mechanism of KIC pathophysiology must be explored to create targeted treatment plans.

Novel botulinum neurotoxin-A tibial nerve perineural injection to alleviate overactive bladder symptoms in male rats

Although tibial nerve modulation has shown to induce positive changes in the overactive bladder (OAB), prolonged therapeutic effects using percutaneous stimulation have not yet been achieved. Intradetrusor onabotulinum toxin A injection can provide prolonged therapeutic effects; however, its delivery requires invasive measures. By applying local relief of tibial nerve neural entrapment with onabotulinum toxin A injection, this study investigated the feasibility and efficacy of combining the abovementioned two therapeutic strategies. An OAB animal model was developed using 12 adult Sprague-Dawley rats with cyclophosphamide intraperitoneal injection. A perineural injection site comparable to the tibial nerve perineural injection site and corresponding to that in humans was identified and developed in rats. The toxin was injected five days after establishing the OAB. The incision was made in the skin on the lateral surface of the thigh. The biceps femoris muscle was cut across, exposing the sciatic nerve and its three terminal branches: the sural, common peroneal, and tibial nerves, and 100 units of onabotulinum toxin A was injected into the surrounding tissue. Five days following injection, cystometry was performed. Inter-contraction time, contraction pressure, and interval of the disease state improved with statistical significance. The OAB animal model showed significant improvement with the tibial nerve perineural injection of botulinum toxin, thereby suggesting the possibility of a comparable treatment adaptation in humans.

Clinical Application of Botulinum Neurotoxin in Lower-Urinary-Tract Diseases and Dysfunctions: Where Are We Now and What More Can We Do?

Botulinum toxin A (Botox) had been considered a promising drug that has an effect on functional disorders of the lower urinary tract. Because Botox exhibits anti-inflammatory and antispasmodic effects, Botox injection into the bladder can decrease detrusor contractility, reduce bladder hypersensitivity, and eliminate painful sensations. Injecting Botox into the bladder outlet can relax the hyperactivity of the bladder neck, and of the urethral smooth and striated muscles. Based on these therapeutic effects, Botox has been widely applied to treat lower-urinary-tract dysfunctions (LUTDs) such as overactive bladder and neurogenic detrusor overactivity. However, this treatment has not been licensed for use in other LUTDs such as interstitial cystitis, voiding dysfunction due to benign prostatic hyperplasia in men, and dysfunctional voiding in women. Botox has also not been approved for the treatment of children with overactive bladder and dysfunctional voiding; in patients with spinal cord injuries with detrusor sphincter dyssynergia and autonomic dysreflexia; or for poorly relaxed external sphincter in non-neurogenic patients. This article reviews the current knowledge regarding Botox treatment for LUTDs and discusses the potential clinical applications of Botox, as well as work that can be conducted in the future.

Use of Botulinum Toxin in the Genitourinary System

Botulinum toxin injection has been widely accepted by the urology and urogynecology medical communities as a safe and effective treatment for refractory urinary incontinence. There are two approved genitourinary indications for botulinum toxin. OnabotulinumtoxinA (onaBoNTA) 200 U for the treatment of urinary incontinence due to detrusor overactivity associated with a neurologic condition (e.g., spinal cord injury, multiple sclerosis) in adults who have an inadequate response to or are intolerant of an anticholinergic medication. In addition, onaBoNTA 100 U is used for the treatment of overactive bladder with symptoms of urinary incontinence, urgency, and frequency, in adult patients who have an inadequate response to or are intolerant of an anticholinergic medication. We will discuss the application of botulinum toxin for genitourinary indications with a focus on bladder injection and on potential use of BoNT use in the prostate and pelvic floor.

How can we improve the diagnosis and management of bladder pain syndrome? Part 2:ICI-RS 2018

BACKGROUND

This paper summarises the discussion in a think tank at the International Consultation on Incontinence-Research Society (ICI-RS) 2018 about the treatment of bladder pain syndrome.

AIMS

To review the treatments of bladder pain syndrome from behavioural treatments to surgical interventions.

MATERIALS AND METHODS

Review the literature in the light of the think tank discussions.

RESULTS

All guidelines recommend different levels of treatment starting with conservative behavioral treatments then introducing oral treatments followed by intravesical instillations. If these treatments fail then more invasive treatments such as botulinum toxin injections, neuromodulation, or surgery could be suggested.

CONCLUSION

Unfortunately for all treatments, the numbers are limited and, therefore, the evidence base is not strong. Further suggestions for research are suggested.

Efficacy and tolerance of botulinum toxin injections after sacral nerve stimulation failure for idiopathic overactive bladder

INTRODUCTION

Management of idiopathic overactive bladder (iOAB) after the failure of sacral nerve modulation (SNM) is very challenging. To the best of our knowledge, no study has evaluated the use of botulinum toxin A (BoNT-A) after SNM failure for iOAB. The aim of this study is to evaluate the tolerance and efficacy of BoNT-A injection after the failure of SNM for iOAB.

METHODS

We conducted a retrospective multicentric analysis of all patients who had received either onabotulinumtoxinA or abobotulinumtoxinA intradetrusor injection for iOAB after SNM failure, between January 2004 and December 2017. The primary outcome was the percentage of success of first BoNT-A injection (either resolution of their urinary incontinence or their frequency or more than 50% reduction in frequency). Secondary outcomes were results of urodynamic studies, complications, total number of injections, causes of withdrawal, and subsequent treatment.

RESULTS

Seventy-six patients (62 female) were included. The percentage of success of first BoNT-A injection was 43.4% (n = 33). All overactive bladder symptoms were significantly improved on the 3-day bladder diary. Twenty-eight patients (36.8%) were put under clean intermittent self-catheterization transitory. After a mean follow-up of 57.7 (±38.5) months, median number of injections was 2 (1-15). Overall, 42 patients (55.2%) stopped injections during follow-up. The estimated 36-months discontinuation-free rate was 48.1%. Mean cause of discontinuation was a primary failure (n = 32; 42.1%).

CONCLUSION

BoNT-A can be used in SNM nonresponders with a success rate of 43.4% but is associated with a high long-term discontinuation rate.

Mechanism of Action of Botulinum Toxin A in Treatment of Functional Urological Disorders

Intravesical botulinum toxin (BoNT) injection is effective in reducing urgency and urinary incontinence. It temporarily inhibits the detrusor muscle contraction by blocking the release of acetylcholine (Ach) from the preganglionic and postganglionic nerves in the efferent nerves. BoNT-A also blocks ATP release from purinergic efferent nerves in the detrusor muscle. In afferent nerves, BoNT-A injection markedly reduces the urothelial ATP release and increases nitric oxide (NO) release from the urothelium. BoNT-A injection in the urethra or bladder has been developed in the past few decades as the treatment method for detrusor sphincter dyssyndergia, incontinence due to neurogenic or idiopathic detrusor overactivity, sensory disorders, including bladder hypersensitivity, overactive bladder, and interstitial cystitis/chronic pelvic pain syndrome. Although the FDA only approved BoNT-A injection treatment for neurogenic detrusor overactivity and for refractory overactive bladder, emerging clinical trials have demonstrated the benefits of BoNT-A treatment in functional urological disorders. Cautious selection of patients and urodynamic evaluation for confirmation of diagnosis are crucial to maximize the successful outcomes of BoNT-A treatment.

Neuronal selectivity of botulinum neurotoxins

Botulinum neurotoxins (BoNTs) are highly potent toxins responsible for a severe disease, called botulism. They are also efficient therapeutic tools with an increasing number of indications ranging from neuromuscular dysfunction to hypersecretion syndrome, pain release, depression as well as cosmetic application. BoNTs are known to mainly target the motor-neurons terminals and to induce flaccid paralysis. BoNTs recognize a specific double receptor on neuronal cells consisting of gangliosides and synaptic vesicle protein, SV2 or synaptotagmin. Using cultured neuronal cells, BoNTs have been established blocking the release of a wide variety of neurotransmitters. However, BoNTs are more potent in motor-neurons than in the other neuronal cell types. In in vivo models, BoNT/A impairs the cholinergic neuronal transmission at the motor-neurons but also at neurons controlling secretions and smooth muscle neurons, and blocks several neuronal pathways including excitatory, inhibitory, and sensitive neurons. However, only a few reports investigated the neuronal selectivity of BoNTs in vivo. In the intestinal wall, BoNT/A and BoNT/B target mainly the cholinergic neurons and to a lower extent the other non-cholinergic neurons including serotonergic, glutamatergic, GABAergic, and VIP-neurons. The in vivo effects induced by BoNTs on the non-cholinergic neurons remain to be precisely investigated. We report here a literature review of the neuronal selectivity of BoNTs.

Effect of Botulinum Toxin A on Bladder Pain-Molecular Evidence and Animal Studies

Botulinum toxin A (BTX-A) is a powerful neurotoxin with long-lasting activity that blocks muscle contractions. In addition to effects on neuromuscular junctions, BTX-A also plays a role in sensory feedback loops, suggesting the potentiality for pain relief. Although the only approved indications for BTX-A in the bladder are neurogenic detrusor overactivity and refractory overactive bladder, BTX-A injections to treat bladder pain refractory to conventional therapies are also recommended. The mechanism of BTX-A activity in bladder pain is complex, with several hypotheses proposed in recent studies. Here we comprehensively reviewed properties of BTX-A in peripheral afferent and efferent nerves, the inhibition of nociceptive neurotransmitter release, the reduction of stretch-related visceral pain, and its anti-inflammatory effects on the bladder urothelium. Studies have also revealed possible effects of BTX-A in the human brain. However, further basic and clinical studies are warranted to provide solid evidence-based support in using BTX-A to treat bladder pain.

The Botulinum Treatment of Neurogenic Detrusor Overactivity: The Double-Face of the Neurotoxin

Botulinum neurotoxin (BoNT) can counteract the highly frequent involuntary muscle contractions and the uncontrolled micturition events that characterize the neurogenic detrusor overactivity (NDO) due to supra-sacral spinal cord lesions. The ability of the toxin to block the neurotransmitter vesicular release causes the reduction of contractions and improves the compliance of the muscle and the bladder filling. BoNT is the second-choice treatment for NDO once the anti-muscarinic drugs have lost their effects. However, the toxin shows a time-dependent efficacy reduction up to a complete loss of activity. The cellular mechanisms responsible for BoNT effects exhaustion are not yet completely defined. Similarly, also the sites of its action are still under identification. A growing amount of data suggest that BoNT, beyond the effects on the efferent terminals, would act on the sensory system recently described in the bladder mucosa. The specimens from NDO patients no longer responding to BoNT treatment displayed a significant increase of the afferent terminals, likely excitatory, and signs of a chronic neurogenic inflammation in the mucosa. In summary, beyond the undoubted benefits in ameliorating the NDO symptomatology, BoNT treatment might bring to alterations in the bladder sensory system able to shorten its own effectiveness.

Efficacy and Safety of Noninvasive Intravesical Instillation of Onabotulinum Toxin-A for Overactive Bladder and Interstitial Cystitis/Bladder Pain Syndrome: Systematic Review and Meta-analysis

OBJECTIVE

To investigate the efficacy and safety of noninvasive intravesical instillation of onabotulinum toxin-A (OBTX-A) through systematic review and meta-analysis. Recently, several studies of noninvasive intravesical instillation of OBTX-A have been published. However, its efficacy is not well validated yet compared to well-known efficacy of minimally invasive intravesical injection of OBTX-A.

METHOD

Systematic review and meta-analysis were performed to evaluate the efficacy of noninvasive intravesical instillation of OBTX-A in patients with overactive bladder and interstitial cystitis/bladder pain syndrome by measuring outcomes such as urgency episode per 72 hours, frequency per 72 hours, urgency urinary incontinence, voided volume (VV), postvoided residual volume, maximum flow rate, and patient perception of bladder condition.

RESULT

Six trials in 4 studies that compared instillation of OBTX-A and placebo involving 248 patients (121 experimental and 127 controls) were included for final data extraction. Instillation of OBTX-A significantly increased VV, with a mean difference of 38.48 (95% confidence interval: 76.05, 0.92) compared to the placebo group. However, other outcomes showed statistically insignificant changes. Major adverse events were not reported in the group receiving intravesical instillation of OBTX-A.

CONCLUSION

Intravesical instillation of OBTX-A showed limited efficacy with improvement of VV for treatment of overactive bladder or interstitial cystitis/bladder pain syndrome. More studies are needed to overcome the efficacy of current noninvasive bladder instillation of OBTX-A regarding effective drug transport.

Safety and Feasibility of Intravesical Instillation of Botulinum Toxin-A in Hydrogel-based Slow-release Delivery System in Patients With Interstitial Cystitis-Bladder Pain Syndrome: A Pilot Study

OBJECTIVE

To assess the feasibility and the safety of a mixture instillation of TC-3 gel, a novel reverse-thermal gelation hydrogel, and botulinum toxin-A (BTX-A) for the treatment of interstitial cystitis-bladder pain syndrome (IC/BPS). TC-3 gel-BTX-A mix is instilled into the bladder as liquid, solidifies because of body heat, and gradually dissolves to release BTX-A for several hours.

METHODS

A single intravesical instillation of 200 U BTX-A premixed with 40 mL TC-3 gel was delivered to the bladder. Adverse events and preliminary efficacy outcome measures were assessed: bladder diary, visual analog scale (VAS) for pain, and Interstitial Cystitis Symptom Index (ICSI) and Interstitial Cystitis Problem Index (ICPI) at baseline and at 2, 6, and 12 weeks.

RESULTS

A total of 15 severely symptomatic patients with IC/BPS (ICSI and ICPI score ranges 12-19 and 12-16, respectively; median VAS = 7) were enrolled (male and female = 4 and 11, ages 24-76). In terms of safety, no increase in VAS score was noted at instillation. All adverse events were transient and mild, the most common being temporary mild constipation (n = 4, 26%). The mean VAS at baseline vs week 12 was 6.6 ± 2.7 vs 5.3 ± 2.8 (P = .044). The mean ICSI and ICPI scores were reduced at week 12 compared with baseline (15.4 ± 2.4 vs 12.9 ± 4.3, P = .004, and 14.8 ± 1.4 vs 11.9 ± 4.0, P = .004, respectively). The mean number of voids per night at baseline decreased for 6 weeks (3.3 ± 2.1 vs 1.8 ± 0.9, P = .046) and then returned to baseline level at week 12.

CONCLUSION

Intravesical instillation of a TC-3 gel-BTX-A mixture is safe and tolerable. Preliminary results suggest temporary efficacy lasting for a few weeks.

The binding of botulinum neurotoxins to different peripheral neurons

Botulinum neurotoxins are the most potent toxins known. The double receptor binding modality represents one of the most significant properties of botulinum neurotoxins and largely accounts for their incredible potency and lethality. Despite the high affinity and the very specific binding, botulinum neurotoxins are versatile and multi-tasking toxins. Indeed they are able to act both at the somatic and at the autonomic nervous system. In spite of the preference for cholinergic nerve terminals botulinum neurotoxins have been shown to inhibit to some extent also the noradrenergic postganglionic sympathetic nerve terminals and the afferent nerve terminals of the sensory neurons inhibiting the release of neuropeptides and glutamate, which are responsible of nociception. Therefore, there is increasing evidence that the therapeutic effect in both motor and autonomic disorders is based on a complex mode of botulinum neurotoxin action modulating the activity of efferent as well as afferent nerve fibres.

Purinergic Signalling: Therapeutic Developments

Purinergic signalling, i.e., the role of nucleotides as extracellular signalling molecules, was proposed in 1972. However, this concept was not well accepted until the early 1990's when receptor subtypes for purines and pyrimidines were cloned and characterised, which includes four subtypes of the P1 (adenosine) receptor, seven subtypes of P2X ion channel receptors and 8 subtypes of the P2Y G protein-coupled receptor. Early studies were largely concerned with the physiology, pharmacology and biochemistry of purinergic signalling. More recently, the focus has been on the pathophysiology and therapeutic potential. There was early recognition of the use of P1 receptor agonists for the treatment of supraventricular tachycardia and A2A receptor antagonists are promising for the treatment of Parkinson's disease. Clopidogrel, a P2Y12 antagonist, is widely used for the treatment of thrombosis and stroke, blocking P2Y12 receptor-mediated platelet aggregation. Diquafosol, a long acting P2Y2 receptor agonist, is being used for the treatment of dry eye. P2X3 receptor antagonists have been developed that are orally bioavailable and stable in vivo and are currently in clinical trials for the treatment of chronic cough, bladder incontinence, visceral pain and hypertension. Antagonists to P2X7 receptors are being investigated for the treatment of inflammatory disorders, including neurodegenerative diseases. Other investigations are in progress for the use of purinergic agents for the treatment of osteoporosis, myocardial infarction, irritable bowel syndrome, epilepsy, atherosclerosis, depression, autism, diabetes, and cancer.

Adolescence transitional care in neurogenic detrusor overactivity and the use of OnabotulinumtoxinA: A clinical algorithm from an Italian consensus statement

AIMS

OnabotulinumtoxinA (onaBNTa) for treating neurogenic detrusor overactivity (NDO) is widely used after its regulatory approval in adults. Although the administration of onaBNTa is still considered off-label in children, data have already been reported on its efficacy and safety. Nowadays, there is a lack of standardized protocols for treatment of NDO with onaBNTa in adolescent patients in their transition from the childhood to the adult age. With the aim to address this issue a consensus panel was obtained.

METHODS

A panel of leading urologists and urogynaecologists skilled in functional urology, neuro-urology, urogynaecology, and pediatric urology participated in a consensus-forming project using a Delphi method to reach national consensus on NDO-onaBNTa treatment in adolescence transitional care.

RESULTS

In total, 11 experts participated. All panelists participated in the four phases of the consensus process. Consensus was reached if ≥70% of the experts agreed on recommendations. To facilitate a common understanding among all experts, a face-to-face consensus meeting was held in Rome in march 2015 and then with a follow-up teleconference in march 2017. By the end of the Delphi process, formal consensus was achieved for 100% of the items and an algorithm was then developed.

CONCLUSIONS

This manuscript represents the first report on the onaBNTa in adolescents. Young adults should be treated as a distinct sub-population in policy, planning, programming, and research, as strongly sustained by national public health care. This consensus and the algorithm could support multidisciplinary communication, reduce the extent of variations in clinical practice and optimize clinical decision making.

Botulinum Neurotoxins: Biology, Pharmacology, and Toxicology

The study of botulinum neurotoxins (BoNT) is rapidly progressing in many aspects. Novel BoNTs are being discovered owing to next generation sequencing, but their biologic and pharmacological properties remain largely unknown. The molecular structure of the large protein complexes that the toxin forms with accessory proteins, which are included in some BoNT type A1 and B1 pharmacological preparations, have been determined. By far the largest effort has been dedicated to the testing and validation of BoNTs as therapeutic agents in an ever increasing number of applications, including pain therapy. BoNT type A1 has been also exploited in a variety of cosmetic treatments, alone or in combination with other agents, and this specific market has reached the size of the one dedicated to the treatment of medical syndromes. The pharmacological properties and mode of action of BoNTs have shed light on general principles of neuronal transport and protein-protein interactions and are stimulating basic science studies. Moreover, the wide array of BoNTs discovered and to be discovered and the production of recombinant BoNTs endowed with specific properties suggest novel uses in therapeutics with increasing disease/symptom specifity. These recent developments are reviewed here to provide an updated picture of the biologic mechanism of action of BoNTs, of their increasing use in pharmacology and in cosmetics, and of their toxicology.

OnabotulinumtoxinA Urethral Sphincter Injection as Treatment for Non-neurogenic Voiding Dysfunction - A Randomized, Double-Blind, Placebo-Controlled Study

Non-neurogenic voiding dysfunction including dysfunctional voiding and detrusor underactivity caused by a spastic or non-relaxing external urethral sphincter can theoretically be treated by injections of botulinum A toxin into the external urethral sphincter. This randomized, double-blind, placebo-controlled trial was designed to determine the clinical efficacy of onabotulinumtoxinA urethral sphincter injections in patients with dysfunctional voiding or detrusor underactivity. Patients with medically refractory dysfunctional voiding (n = 31) or detrusor underactivity (n = 31) were randomly allocated in a 2:1 ratio to receive either onabotulinumtoxinA (100 U) (n = 38) or placebo (normal saline) (n = 24). There were no significant differences in subjective or objective parameters between patients who received onabotulinumtoxinA and those who received saline injection therapy, and the overall success rate was 43.5% (reduction in Patient perception of Bladder Condition by ≥2: onabotulinumtoxinA 36.8% vs placebo 54.2%, p = 0.114). The results were similar between the dysfunctional voiding and detrusor underactivity subgroups; however, a significant reduction in detrusor voiding pressure was only observed in dysfunctional voiding patients who received onabotulinumtoxinA. Repeat urethral sphincter onabotulinumtoxinA injections offered greater therapeutic effects in both dysfunctional voiding and detrusor underactivity patients. For patients with non-neurogenic voiding dysfunction, the success rate of onabotulinumtoxinA urethral sphincter injection was not superior to placebo.

Characterizing the Bladder's Response to Onabotulinum Toxin Type A Using a Rat Model

OBJECTIVES

The aim of this study was to characterize the response of the rat bladder neuromuscular system to intramural injection of onabotulinum toxin type A (BoNT/A) over 9 weeks using in vivo cystometry (CMG) and in vitro contractility (IVC).

METHODS

Chronic bladder catheters were implanted in female Sprague-Dawley rats, and either (1) BoNT/A (10 units in 20 μL saline) or (2) saline (20 μL) was injected in 5 × 4 μL doses throughout the bladder wall. At 1, 3, 6, and 9 weeks after injection, conscious restrained CMG was performed. At each time point, 25% of each group (8 BoNT/A and 4 controls) was euthanized and bladders harvested for IVC. We measured IVC in response to electric field stimulation, carbachol, and potassium chloride.

RESULTS

In total, 47 animals were included; 31 underwent BoNT/A injection, and 16 received sham (saline). Bladder capacities did not differ significantly between groups for each time point. One week after injection BoNT/A animals exhibited significantly longer bladder contraction durations and lower voiding efficiencies compared with controls. By 3 weeks these values returned to control levels. For BoNT/A animals, contractile response to carbachol stimulation was enhanced at 3 weeks. Otherwise, there were no differences in IVC responses.

CONCLUSIONS

One week after BoNT/A injection, prolonged bladder contractions are noted in rats. This may reflect supraspinal compensation for denervation by increasing the duration of efferent drive during voiding. After 3 weeks postinjection, we observed no differences in either CMG or IVC responses suggesting either compensatory efferent sprouting, increased gap junction formation, or loss of BoNT/A effect.

Intravesical Botulinum Toxin A Injections for Bladder Pain Syndrome/Interstitial Cystitis: A Systematic Review and Meta-Analysis of Controlled Studies

Background

The role of intravesical botulinum toxin A (BTX-A) injections in bladder pain syndrome/interstitial cystitis (BPS/IC) has not been clearly defined. The aim of this study was to evaluate high-level evidence regarding the efficacy and safety of BTX-A injections for BPS/IC.

Material/Methods

We conducted a comprehensive search of PubMed, Embase, and Web of Science, and conducted a systematic review and meta-analysis of all available randomized controlled trials (RCTs) and controlled studies assessing BTX-A injections for BPS/IC.

Results

Seven RCTs and 1 retrospective study were identified based on the selection criteria. Pooled analyses showed that although BTX-A was associated with a slightly larger volume of post-void residual urine (PVR) (weighted mean difference [WMD] 10.94 mL; 95% confidence intervals [CI] 3.32 to 18.56; p=0.005), patients in this group might benefit from greater reduction in pelvic pain (WMD −1.73; 95% CI −3.16 to −0.29; p=0.02), Interstitial Cystitis Problem Index (ICPI) scores (WMD −1.25; 95% CI −2.20 to −0.30; p=0.01), and Interstitial Cystitis Symptom Index (ICSI) scores (WMD −1.16; 95% CI −2.22 to −0.11; p=0.03), and significant improvement in daytime frequency of urination (WMD −2.36; 95% CI −4.23 to −0.49; p=0.01) and maximum cystometric capacity (MCC) (WMD 50.49 mL; 95% CI 25.27 to 75.71; p<0.00001). Nocturia, maximal urinary flow rate, dysuria, and urinary tract infection did not differ significantly between the 2 groups.

Conclusions

Intravesical BTX-A injections might offer significant improvement in bladder pain symptoms, daytime urination frequency, and MCC for patients with refractory BPS/IC, with a slightly larger PVR. Further well-designed, large-scale RCTs are required to confirm the findings of this analysis.

Pathophysiology, Clinical Importance, and Management of Neurogenic Lower Urinary Tract Dysfunction Caused by Suprasacral Spinal Cord Injury

Management of persistent lower urinary tract dysfunction resulting from severe thoracolumbar spinal cord injury can be challenging. Severe suprasacral spinal cord injury releases the spinal cord segmental micturition reflex from supraspinal modulation and increases nerve growth factor concentration in the bladder wall, lumbosacral spinal cord, and dorsal root ganglion, which subsequently activates hypermechanosensitive C-fiber bladder wall afferents. Hyperexcitability of bladder afferents and detrusor overactivity can cause urine leaking during the storage phase. During urine voiding, the loss of supraspinal control that normally coordinates detrusor contraction with sphincter relaxation can lead to spinal cord segmental reflex-mediated simultaneous detrusor and sphincter contractions or detrusor-sphincter dyssynergia, resulting in inefficient urine voiding and high residual volume. These disease-associated changes can impact on the quality of life and life expectancy of spinal-injured animals. Here, we discuss the pathophysiology and management considerations of lower urinary tract dysfunction as the result of severe, acute, suprasacral spinal cord injury. In addition, drawing from experimental, preclinical, and clinical medicine, we introduce some treatment options for neurogenic lower urinary tract dysfunction that are designed to: (1) prevent urine leakage arising because of detrusor overactivity during bladder filling, (2) preserve upper urinary tract integrity and function by reducing intravesical pressure and subsequent vesicoureteral reflux, and (3) prevent urinary tract and systemic complications by treating and preventing urinary tract infections.

Efficacy and safety of onabotulinum toxin A for overactive bladder

Overactive bladder (OAB) syndrome is a condition which affects 16.9% of women and 16.2% of men with a significant negative impact on quality of life. It is a condition characterized by urgency, with or without urge incontinence, frequency and nocturia. Behavioral modifications and oral anti-muscurinic medications are first and second-line therapies for OAB but are frequently ineffective or poorly tolerated. For refractory cases of OAB, onabotulinum toxin can be offered and this therapy was approved by the Food and Drug Administration in January of 2013. In this editorial, we will review the indications, usage, efficacy and safety data for intradetrusor injection of onabotulinum toxin A.

Impairment of sensory afferents by intrathecal administration of botulinum toxin A improves neurogenic detrusor overactivity in chronic spinal cord injured rats

Spinal cord injury (SCI) often leads to neurogenic detrusor overactivity (NDO) due to sprouting of sensory afferents on the lumbosacral spinal cord. NDO is characterized by high frequency of voiding contractions and increased intravesical pressure that may lead to urinary incontinence. The latter has been described as one of the consequences of SCI that mostly decreases quality of life. Bladder wall injections of botulinum toxin A (Onabot/A) are an effective option to manage NDO. The toxin strongly impairs parasympathetic and sensory fibres coursing the bladder wall. However the robust parasympathetic inhibition may inhibit voiding contractions and cause urinary retention in patients that retain voluntary voiding. Here, we hypothesised that by restricting the toxin activity to sensory fibres we can improve NDO without impairing voiding contractions. In the present work, we assessed the effect of Onabot/A on sensory neurons in chronic (4weeks) SCI rats by injecting the toxin intrathecally (IT), at lumbosacral spinal cord level. This route of administration was shown before to have an effect on bladder pain and contractility in an animal model of bladder inflammation. We found that IT Onabot/A led to a significant reduction in the frequency of expulsive contractions and a normalization of bladder basal pressure while maintaining voiding contractions of normal amplitude. Cleavage of SNAP-25 protein occurred mainly at the dorsal horn regions where most of the bladder afferents end. Cleaved SNAP-25 was not detected in motor or preganglionic parasympathetic neurons. A significant decrease in CGRP expression, a peptide exclusively present in sensory fibres in the spinal cord, occurred at the L5/L6 segments and associated dorsal root ganglia (DRG) after Onabot/A injection in SCI animals. Onabot/A strongly increased the expression of ATF3, a marker of neuronal stress, in L5/L6 DRG neurons. Taken together, our results suggest that IT Onabot/A has a predominant effect on bladder sensory fibres, and that such effect is enough to control NDO following chronic SCI. The mechanism of action of Onabot/A includes not only the cleavage of SNAP-25 in sensory terminals but also impairment of basic cellular machinery in the cell body of sensory neurons.

Efficacy and safety of botulinum toxin injection for interstitial cystitis/bladder pain syndrome: a systematic review and meta-analysis

PURPOSE

To investigate the overall treatment efficacy and safety of botulinum toxin type A (BoNTA) injections compared with placebo in interstitial cystitis/bladder pain syndrome (IC/BPS).

METHODS

We conducted a systematic review and meta-analysis of the published literature in PubMed, Cochrane Library, and EMBASE on BoNTA use in IC/BPS. Outcome measures included changes of OLS, ICSI, ICPI, VAS, frequency, nocturia, FBC, Qmax, and PVR from baseline and also included adverse events.

RESULTS

A total of five studies were included, with a total sample size of 252 subjects (133 subjects in the experimental group and 119 subjects in the control group). The duration of follow-up ranged from 8 to 12 weeks. The BoNTA dosage was from 50 to 200 U. The pooled overall SMD in the mean change of VAS for the BoNTA group versus the placebo group was -0.49 (95 % CI -0.74, -0.23). There were also significant improvements in ICPI and frequency. The other outcomes (ICSI, nocturia, Qmax, and FBC) were not statistically different between the two groups.

CONCLUSION

Although BoNTA is not regulatory approved indication, this first evidence-based systematic review and meta-analysis of BoNTA injection for IC/BPS showed significant differences in efficacy of treatment compared with placebo, especially for pain control, and also showed no differences in the rate of procedure-related adverse events.

Use of Botulinum Toxin in Urologic Diseases

OnabotulinumtoxinA (onaBoNTA) is approved by the US Food and Drug Administration for the treatment of urinary incontinence due to neurogenic detrusor overactivity and for the treatment of refractory overactive bladder. As a treatment for benign prostatic hyperplasia, onaBoNTA showed no difference over placebo in recently published studies. In contrast, treating interstitial cystitis/bladder pain syndrome with onaBoNTA has shown efficacy, and the current American Urological Association guideline for the diagnosis and treatment of interstitial cystitis/bladder pain syndrome lists onaBoNTA as fourth-line treatment. This comprehensive review will present all studied applications of onaBoNTA within the lower urinary tract.

Botulinum toxin type A induces changes in the chemical coding of substance P-immunoreactive dorsal root ganglia sensory neurons supplying the porcine urinary bladder

Botulinum toxin (BTX) is a potent neurotoxin which blocks acetylcholine release from nerve terminals, and therefore leads to cessation of somatic motor and/or parasympathetic transmission. Recently it has been found that BTX also interferes with sensory transmission, thus, the present study was aimed at investigating the neurochemical characterization of substance P-immunoreactive (SP-IR) bladder-projecting sensory neurons (BPSN) after the toxin treatment. Investigated neurons were visualized with retrograde tracing method and their chemical profile was disclosed with double-labelling immunohistochemistry using antibodies against SP, calcitonin gene-related peptide (CGRP), pituitary adenylate cyclase activating polypeptide (PACAP), neuronal nitric oxide synthase (nNOS), galanin (GAL), calbindin (CB), and somatostatin (SOM). In the control group (n = 6), 45% of the total population of BPSN were SP-IR. Nearly half of these neurons co-expressed PACAP or CGRP (45% and 35%, respectively), while co-localization of SP with GAL, nNOS, SOM or CB was found less frequently (3.7%, 1.8%, 1.2%, and 0.7%, respectively). In BTX-treated pigs (n = 6), toxin-injections caused a decrease in the number of SP-IR cells containing CGRP, SOM or CB (16.2%, 0.5%, and 0%, respectively) and a distinct increase in these nerve cells immunopositive to GAL (27.2%). The present study demonstrates that BTX significantly modifies the chemical phenotypes of SP-IR BPSN.

Efficacy and safety of botulinum toxin injection for benign prostatic hyperplasia: a systematic review and meta-analysis

PURPOSE

The aim of this study was to overcome the limitation of overlooking the placebo effect in previous studies and to demonstrate the overall treatment efficacy and safety of botulinum toxin type A (BTX-A) compared with placebo.

METHODS

We conducted a systematic review and meta-analysis of the published literature in PubMed, Cochrane Library, and Embase reporting on BTX use in lower urinary tract symptoms (LUTS)/benign prostate hyperplasia (BPH). Single-group analysis for the placebo effect and meta-regression analysis for the moderator effect were performed with high-quality RCTs compared with placebo.

RESULTS

A total of three studies were included, with a total sample size of 522 subjects (260 subjects in the experimental group and 262 subjects in the control group). Study duration ranged from 8 to 24 weeks. The pooled overall SMD in the mean change in IPSS for the BTX-A group versus the placebo group was -1.02 (95 % CI -1.97, -0.07). The other outcomes (Q max, prostate volume, and post-voided residual volume) were not statistically different between the two groups. The placebo effect in single-group analysis ranged from 0 to 27.9 % for IPSS, and from -1.1 to 28.7 % for Q max (lowest to highest, respectively).

CONCLUSIONS

This evidence-based systematic review and meta-analysis of the BTX-A injection for LUTS/BPH showed no differences in efficacy compared with placebo and also showed no difference in procedure-related adverse events occurred. Thus, the results of this study do not provide evidence of clinical benefits of using the BTX-A injection for LUTS/BPH in real clinical practice.

Therapeutic Potential of Human Chorionic Gonadotropin Against Overactive Bladder

Overactive bladder (OAB) is a common form of urinary incontinence, resulting from spontaneous and random contractions of the urinary bladder. The affected individuals have an uncontrollable urge to urinate and experience incontinence and nocturia, which can greatly reduce the quality of daily life. There are several drugs for the treatment, and all of them have serious side effects. The following findings suggested that human chorionic gonadotropin (hCG) has a therapeutic potential that is worth investigating for the treatment of OAB. The finding are (1) human detrusor muscle contains hCG receptors, (2) detrusor muscle becomes quiescent during pregnancy, (3) hCG can inhibit detrusor muscle contractions induced by cholinergic stimulation in rats, and (4) hCG can mimic the anticholinergic drug on detrusor muscle contractions.

Current and potential urological applications of botulinum toxin A

Botulinum toxin subtype A (BoNT-A) is a potent neurotoxin that can selectively modulate neurotransmitter release from nerve endings, resulting in muscular paralysis. BoNT-A might also act on sensory nerves, and have an anti-inflammatory effect. In the first urological use of BoNT-A, injection into the urethral sphincters of patients with detrusor-sphincter dyssynergia resulted in a reduction of urethral resistance and improved voiding efficiency. Subsequently, intravesical BoNT-A injections have received regulatory approval for treatment of neurogenic detrusor overactivity owing to spinal cord lesions or multiple sclerosis, and idiopathic overactive bladder in adults. BoNT-A has also been widely used to treat patients with the off-label indications of neurogenic or non-neurogenic voiding dysfunction and male lower urinary tract symptoms owing to BPH and bladder-neck dysfunction. Other indications for which urologists have applied BoNT-A injections include interstitial cystitis/bladder pain syndrome, bladder oversensitivity and chronic pelvic pain syndrome. BoNT-A is currently delivered as an intravesical injection; however, use of liposome encapsulated formulations is also beginning to show some therapeutic potential.

Presence of Cleaved Synaptosomal-Associated Protein-25 and Decrease of Purinergic Receptors P2X3 in the Bladder Urothelium Influence Efficacy of Botulinum Toxin Treatment for Overactive Bladder Syndrome

OBJECTIVES

To evaluate whether botulinum toxin A (BoNT-A) injection and Lipotoxin (liposomes with 200 U of BoNT-A) instillation target different proteins, including P2X3, synaptic vesicle glycoprotein 2A, and SNAP-25, in the bladder mucosa, leading to different treatment outcomes.

MATERIALS AND METHODS

This was a retrospective study performed in a tertiary teaching hospital. We evaluated the clinical results of 27 OAB patients treated with intravesical BoNT-A injection (n = 16) or Lipotoxin instillation (n = 11). Seven controls were treated with saline. Patients were injected with 100 U of BoNT-A or Lipotoxinin a single intravesical instillation. The patients enrolled in this study all had bladder biopsies performed at baseline and one month after BoNT-A therapy. Treatment outcome was measured by the decreases in urgency and frequency episodes at 1 month. The functional protein expressions in the urothelium were measured at baseline and after 1 month. The Wilcoxon signed-rank test and ordinal logistic regression were used to compare the treatment outcomes.

RESULTS

Both BoNT-A injection and Lipotoxin instillation treatments effectively decreased the frequency of urgency episodes in OAB patients. Lipotoxin instillation did not increase post-void residual volume. BoNT-A injection effectively cleaved SNAP-25 (p < 0.01). Liposome encapsulated BoNT-A decreased urothelial P2X3 expression in the five responders (p = 0.04), while SNAP-25 was not significantly cleaved.

CONCLUSIONS

The results of this study provide a possible mechanism for the therapeutic effects of BoNT-A for the treatment of OAB via different treatment forms. BoNT-A and Lipotoxin treatments effectively decreased the frequency of urgency episodes in patients with OAB.

Botulinum neurotoxin type A inhibits synaptic vesicle 2 expression in breast cancer cell lines

AIM

It is known that botulinum neurotoxin type A (BoNTA) improves some kinds of cancer (e.g. prostate) and that synaptic vesicle glycoprotein 2 (SV2) is the molecular target of this neurotoxin. Besides having potential therapeutic value, this glycoprotein has recently been proposed as a molecular marker for several types of cancer. Although the mechanisms of cancer development and the improvement found with botulinum treatment are not well understood, the formation of the botulinum-SV2 complex may influence the presence and distribution of SV2 and the function of vesicles. To date, there are no reports on the possible effect of botulinum on breast cancer of unknown causes, which have a great impact on women's health. Thus we determined the presence of SV2 in three breast cancer cell lines and the alterations found with botulinum application.

MATERIALS AND METHODS

With and without adding 10 units of botulinum, SV2 protein expression was determined by optical densitometry in T47D, MDA-MB-231 and MDA-MB-453 cell lines and the distribution of SV2 was observed with immunochemistry (hematoxylin staining).

RESULTS

The SV2 protein was abundant in the cancer cells herein tested, and maximally so in T47D. In all three cancer cell lines botulinum diminished SV2 expression, which was found mostly in the cell periphery.

CONCLUSION

SV2 could be a molecular marker in breast cancer. Its expression and distribution is regulated by botulinum, suggesting an interesting control mechanism for SV2 expression and a possible alternative therapy. Further studies are needed in this sense.

[Physiopathology of overactive bladder syndrome]

The pathophysiology of OAB is complex, multifactorial and still largely unknown. Several pathophysiological mechanisms have been highlighted that may play a different role in different patient groups. There are now experimental evidences that support both the myogenic and neurogenic hypothesis, but in recent years the "integrative" hypothesis has been gaining more and more acceptance, where a disruption in the multiple interactions between different cell types (neurons, urothelium, interstitial cells, myocytes) and network functions represent a central element of lower urinary tract dysfunctions. Of utmost importance, a disorder in the urothelial sensory function and in the urothelial/suburothelial non-neural cholinergic system, favored by age and comorbidities, appears to be crucial for the development of the OAB. Neuroplastic and detrusor changes in OAB are broadly similar to those observed in bladders exposed to outlet obstruction, neuropathies, inflammation or aging, and may be driven by a common urothelial dysfunction. Several signaling substances and their receptors were found to be involved in central pathways of bidirectional communication between the different cell types in the bladder, and were shown to be modified in several animal models of OAB as well as in human models, indicating new potential therapeutic targets.

P2X3 receptors and sensitization of autonomic reflexes

A great deal of basic and applied physiology and pharmacology in sensory and autonomic neuroscience has teased apart mechanisms that drive normal perception of mechanical, thermal and chemical signals and convey them to CNS, the distinction of fiber types and receptors and channels that mediate them, and how they may become dysfunctional or maladaptive in disease. Likewise, regulation of efferent autonomic traffic to control organ reflexes has been well studied. In both afferent and efferent limbs, a wide array of potential therapeutic mechanisms has surfaced, some of which have progressed into clinic, if not full regrastration. One conversation that has been less well progressed relates to how the afferent limb and its sensitization shapes the efferent outputs, and where modulation may offer new therapeutic avenues, especially for poorly addressed and common signs and symptoms of disease. Therapeutics for CV disease (HF, hypertension), respiratory disease (asthma, COPD), urological disease (OAB), GI disease (IBS), and inter alia, have largely focused on the efferent control of effector cells to modulate movement, contraction and secretion; medicinal needs remain with limits to efficacy, AEs and treatment resistance being common. We now must turn, in the quest for improved therapeutics, to understand how sensation from these organs becomes maladapted and sensitized in disease, and what opportunities may arise for improved therapeutics given the abundance of targets, many pharmacologically untapped, on the afferent side. One might look at the treatment resistant hypertension and the emerging benefit of renal denervation; or urinary bladder overactivity / neurogenic bladder and the emergence of neuromodulation, capsaicin instillation or botox injections to attenuate sensitized reflexes, as examples of merely the start of such progress. This review examines this topic more deeply, as applies to four major organ systems all sharing a great need from unsatisfied patients.

Chapter 3: Molecular basis for the therapeutic effectiveness of botulinum neurotoxin type A

The utility of botulinum neurotoxin type A (BoNT/A) for treating overactive muscles and endocrine glands is attributable to a unique conflation of properties honed to exploit and inactivate synaptic transmission. Specific, high-affinity coincident binding to gangliosides plus an intraluminal loop of synaptic vesicle protein 2 (SV2) by the heavy chain (HC) of BoNT/A confers selectivity for presynaptic nerve terminals and subsequent uptake by endocytosis. Upon vesicle acidification, the HC forms a channel for transmembrane transfer of the light chain to the cytosol, as observed by single channel recordings. The light chain is a Zn(2+) -dependent endoprotease that cleaves and inactivates SNAP-25, thereby blocking exocytotic release of transmitters, a discovery that revealed the pivotal role of the latter in synaptic vesicle fusion. A di-leucine motif in BoNT/A light chain stabilizes this protease, contributing to its longevity inside nerves. The ubiquity of SV2 and SNAP-25 has prompted re-evaluation of the nerve types susceptible to BoNT/A. In urology, there is emerging evidence that BoNT/A blocks neuropeptide release from afferent nerves, exocytosis of acetylcholine and purines from efferent nerves, and possibly ATP release from the urothelium. Suppression by BoNT/A of the surface expression of nociceptor channels on bladder afferents might also contribute to its improvement of urological sensory symptoms.

Chapter 2: Pathophysiology of neurogenic detrusor overactivity and the symptom complex of "overactive bladder"

It is now clearly recognized that the function of the lower urinary tract represents a complex interaction between the bladder and its outlet, acting under the control of the central nervous system. While in the past attention has principally focused on the motor (efferent) control of the bladder, sensory (afferent) innervation is now known to be an important therapeutic target. This change in emphasis is strongly supported by both basic science and clinical evidence demonstrating the efficacy of therapy directed at the afferent system. This chapter summarizes the neurophysiological control mechanism that underpins normal lower urinary tract function, emphasizing the importance of the afferent system as a potential therapeutic target.

Innovative pharmacotherapies for women with overactive bladder: where are we now and what is in the pipeline?

INTRODUCTION AND HYPOTHESIS

The impressive prevalence of overactive bladder (OAB) and the relevant limitations of current treatments urge the need for novel therapeutic approaches.

METHODS

A systematic literature and web search was performed to identify investigational drugs that entered the early and late phases of clinical development for women with OAB symptoms.

RESULTS

Approved pharmacological therapies for OAB (antimuscarinics, beta-3 agonists, and botulinum toxin) are evolving with the development of alternative administration methods, combination strategies, and novel compounds, expected to improve effectiveness, bladder selectivity, and dose flexibility. A wealth of investigational compounds, developed with both public and companies' indoor nonclinical disease-oriented studies, entered the early and late stages of clinical development in the last decade. Most non-anticholinergic compounds in ongoing clinical trials target central and peripheral neurotransmitter receptors involved in neurological modulation of micturition, nonadrenergic-noncholinergic mechanisms, cyclic nucleotide metabolism, different subtypes of ion channels or peripheral receptors of prostaglandins, vanilloids, vitamin D3, and opioids. Fascinating advances are ongoing also in the field of genetic therapy.

CONCLUSIONS

New pharmaceutical formulations and drug combinations are expected to be available in the next decade in order to overcome the limitations of current drugs for OAB. Although proof-of-concept, patient-oriented studies yielded disappointing results for several tentative drugs, a lot of clinical research is ongoing that is expected to provide clinicians with novel therapeutic agents in the near future.

Brain-derived neurotrophic factor in urinary continence and incontinence

Urinary incontinence adversely affects quality of life and results in an increased financial burden for the elderly. Accumulating evidence suggests a connection between neurotrophins, such as brain-derived neurotrophic factor (BDNF), and lower urinary tract function, particularly with regard to normal physiological function and the pathophysiological mechanisms of stress urinary incontinence (SUI) and bladder pain syndrome/interstitial cystitis (BPS/IC). The interaction between BDNF and glutamate receptors affects both bladder and external urethral sphincter function during micturition. Clinical findings indicate reduced BDNF levels in antepartum and postpartum women, potentially correlating with postpartum SUI. Experiments with animal models demonstrate that BDNF is decreased after simulated childbirth injury, thereby impeding the recovery of injured nerves and the restoration of continence. Treatment with exogenous BDNF facilitates neural recovery and the restoration of continence. Serotonin and noradrenaline reuptake inhibitors, used to treat both depression and SUI, result in enhanced BDNF levels. Understanding the neurophysiological roles of BDNF in maintaining normal urinary function and in the pathogenesis of SUI and BPS/IC could lead to future therapies based on these mechanisms.

Purinergic signalling: pathophysiology and therapeutic potential

The article begins with a review of the main conceptual steps involved in the development of our understanding of purinergic signalling, including non-adrenergic, non-cholinergic (NANC) neurotransmission; identification of ATP as a NANC transmitter; purinergic cotransmission; recognition of two families of purinoceptors [P1 (adenosine) and P2 (ATP/ADP)]; and, later, cloning and characterisation of P1 (G protein-coupled), P2X (ion channel) and P2Y (G protein-coupled) receptor subtypes. Further studies have established the involvement of ATP in synaptic neurotransmission in both ganglia and in the central nervous system; long-term (trophic) purinergic signalling in cell proliferation, differentiation and death occurring in development and regeneration; and short-term purinergic signalling in neurotransmission, neuromodulation and secretion. ATP is released from most cell types in response to gentle mechanical stimulation and is rapidly degraded to adenosine by ecto-nucleotidases. This review then focuses on the pathophysiology of purinergic signalling in a wide variety of systems, including urinogenital, cardiovascular, airway, musculoskeletal and gastrointestinal. Consideration is also given to the involvement of purinoceptors in pain, cancer and diseases of the central nervous system. Purinergic therapeutic approaches for the treatment of some of these diseases are discussed.

Purinergic signalling in the urinary tract in health and disease

Purinergic signalling is involved in a number of physiological and pathophysiological activities in the lower urinary tract. In the bladder of laboratory animals there is parasympathetic excitatory cotransmission with the purinergic and cholinergic components being approximately equal, acting via P2X1 and muscarinic receptors, respectively. Purinergic mechanosensory transduction occurs where ATP, released from urothelial cells during distension of bladder and ureter, acts on P2X3 and P2X2/3 receptors on suburothelial sensory nerves to initiate the voiding reflex, via low threshold fibres, and nociception, via high threshold fibres. In human bladder the purinergic component of parasympathetic cotransmission is less than 3 %, but in pathological conditions, such as interstitial cystitis, obstructed and neuropathic bladder, the purinergic component is increased to 40 %. Other pathological conditions of the bladder have been shown to involve purinoceptor-mediated activities, including multiple sclerosis, ischaemia, diabetes, cancer and bacterial infections. In the ureter, P2X7 receptors have been implicated in inflammation and fibrosis. Purinergic therapeutic strategies are being explored that hopefully will be developed and bring benefit and relief to many patients with urinary tract disorders.

Urinary bladder, cystitis and nerve/urothelial interactions

A hallmark of functional pain syndromes, such as bladder pain syndrome/interstitial cystitis (BPS/IC) is pain in the absence of demonstrable infection or pathology of the viscera or associated nerves. There are no clear definitions of this syndrome, no proven etiologies and no effective treatments able to eradicate the symptoms. This condition is characterized by suprapubic pain, associated with bladder filling and can also be accompanied by a persistent strong desire to void, increased frequency of urination and nocturia. Severe cases of this disorder, which affects primarily women, can have considerable impact on the quality of life of patients due to extreme pain and urinary frequency, which are often difficult to treat. In addition, BPS/IC patients may also suffer co-morbid conditions where pain is a common symptom (such as irritable bowel syndrome, fibromyalgia). Theories explaining the pathology of bladder pain syndrome are many and include an altered bladder lining and possible contribution of a bacterial agent.

Effect of botulinum toxin A on urothelial-release of ATP and expression of SNARE targets within the urothelium

AIMS

Botulinum neurotoxin serotype A (BoNT/A) has emerged as an effective treatment of urinary bladder overactivity. Intravesical lipotoxin (BoNT/A delivery using liposomes), which may target the urothelium, is effective in blocking acetic acid induced hyperactivity in animals. The objective of this study was to assess the possible site of toxin action within the urothelium.

METHODS

We examined expression of the toxin receptor (SV2) and its cleavage targets (SNAP-25 and SNAP-23) within urothelium as well as effects of the toxin on mechanically evoked release of ATP from cultured rat urothelial cells. ATP release was measured using the luciferin-luciferase assay; we examined expression of SNAP-23 and -25 in urothelial cells and mucosa of rat and human bladders.

RESULTS

BoNT/A (1.5 U; 1-3 hr) blocked hypotonic evoked release of urothelial ATP, without affecting morphology. The expression of protein targets for BoNT/A binding (SV2) was detected in human and rat bladder mucosa and catalytic action (SNAP-23, -25) in urothelial cells and mucosa (differed in intensity) from rat and human bladder. Incubation of cultured (rat) urothelial cells with BoNT/A decreased expression levels of both SNAP-23 (44%) and SNAP-25 (80%).

CONCLUSIONS

Our findings reveal that the bladder urothelium expresses the intracellular targets and the binding protein for cellular uptake of BoNT/A; and that the toxin is able to suppress the levels of these targets as well as hypotonic-evoked ATP release. These data raise the possibility that intravesical treatment with BoNT/A suppresses bladder reflex and sensory mechanisms by affecting a number of urothelial functions including release of transmitters.

OnobotulinumtoxinA Has No Effects on Growth of LNCaP and PC3 Human Prostate Cancer Cells

OBJECTIVES

Intraprostatic injection of botulinum toxin (BTX) has been reported to have therapeutic effects on lower urinary tract symptoms related to benign prostate hyperplasia (BPH). Patients with BPH are at risk of having prostate cancer. The present study was conducted to assess the effect of onobotulinumtoxinA on prostate cancer in vitro and in vivo.

METHODS

Human prostate cancer cell lines, LNCaP and PC3 were exposed to different doses of onobotulinumtoxinA (0-10 U; Allergan, Irvine, CA, USA). Cell viability, DNA fragmentation and apoptosis assay were subsequently measured. For the in vivo study, LNCaP and PC3 xenografts were introduced into nude mice and treated with intra-tumoral onobotulinumtoxinA or saline injection. Tumor volume, histopathology and apoptosis were assessed. Presence of SNAP-25 protein, the molecular target of onobotulinumtoxinA, was studied in both cell lines by Western blot analysis.

RESULTS

OnobotulinumtoxinA did not significantly affect cell proliferation or apoptosis in LNCaP and PC3 cells. There was no significant difference in tumor size and histopathological findings between the experimental and control groups. There was no detectable SNAP-25 protein in both cell lines.

CONCLUSION

OnobotulinumtoxinA does not affect the growth of LNCaP or PC3 cells in vitro and in vivo or produce significant anti-tumor effects. Intraprostatic BTX injection for BPH might not affect the growth of prostate cancer.

Use of botulinum toxin in individuals with neurogenic detrusor overactivity: state of the art review

BACKGROUND

Botulinum neurotoxin (BoNT) injection into the bladder wall has been shown to be an effective alternative to anticholinergic (antimuscarinic) medications and more invasive surgery in those with multiple sclerosis and spinal cord injury with neurogenic detrusor overactivity (NDO) and urinary incontinence who are not tolerating anticholinergic medications. In August 2011, Botox(®) (onabotulinumtoxinA) received Food and Drug Administration (FDA) approval for this use. Clinically, intradetrusor injection of BoNT has been found to decrease urinary incontinence and improve quality of life. Its impact on urodynamic parameters is an increase in the maximum cystometric (bladder) capacity and decrease in the maximum detrusor pressures. The most common side effects are urinary tract infections and urinary retention. There have been rare reports and a black box warning of distant spread of BoNT. BoNT has gained popularity because of its effectiveness and long duration of action, relative ease of administration, easy learning curve, reproducibility of results on repeated administration, and low incidence of complications.

OBJECTIVE

To discuss the structure and function, mechanisms of action, clinical and urodynamic studies, injection technique, potential beneficial and adverse effects, and potential areas of research of BoNT.

METHODS

Literature search focused on botulinum toxin in MEDLINE/PubMed. Search terms included botulinum toxin, neurogenic bladder, NDO, botox bladder, botox spinal cord injury, botox, FDA, botox side effects. All papers identified were English language, full-text papers. In addition, English abstracts of non-English papers were noted. The reference list of identified articles was also searched for further papers.

CONCLUSION

Botulinum toxin is an alternative treatment for individuals with NDO who fail to tolerate anticholinergic medications. Its popularity has increased because of the literature, which has supported its effectiveness, safety, easy use and learning curve, reproducibility of results on repeated use, and recent FDA approval of Botox(®) (onabotulinumtoxinA).