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Chess-Williams R, Sellers DJ. Pathophysiological Mechanisms Involved in Overactive Bladder/Detrusor Overactivity. CURRENT BLADDER DYSFUNCTION REPORTS 2023. [DOI: 10.1007/s11884-023-00690-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
Abstract
Purpose of Review
To examine the latest published findings on the pathophysiological mechanisms involved in the development of overactive bladder (OAB) and detrusor overactivity (DO), and to identify common pathways linked to the risk factors associated with these conditions.
Recent Findings
Evidence is accumulating, both clinical and experimental, that many of the factors linked to the development of OAB/DO, including ageing, bladder outlet obstruction, psychological stress, and obesity are associated with reduced bladder blood flow. This induces local tissue inflammation with cytokine release and enhanced oxidative stress, ultimately resulting in altered detrusor sensitivity, detrusor hypertrophy and fibrosis, together with afferent hypersensitivity. These mechanisms would explain the symptoms of urgency and frequency observed in OAB patients. Although not a characteristic of OAB, undetected low level bacterial infections of the bladder have been proposed to explain the OAB symptoms in patients resistant to standard treatments. In this condition, inflammatory responses without reductions in perfusion activate the inflammatory pathways.
Summary
Evidence is mounting that poor bladder perfusion and local inflammatory responses are central mechanisms involved in the development of OAB/DO. As our understanding of these pathophysiological mechanisms advances, new avenues for drug development will be identified and ultimately treatment may become more individualized depending on the particular pathway involved and the drugs available.
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Heppner TJ, Hennig GW, Nelson MT, Herrera GM. Afferent nerve activity in a mouse model increases with faster bladder filling rates in vitro, but voiding behavior remains unaltered in vivo. Am J Physiol Regul Integr Comp Physiol 2022; 323:R682-R693. [PMID: 36121145 PMCID: PMC9602904 DOI: 10.1152/ajpregu.00156.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Storage and voiding functions in urinary bladder are well-known, yet fundamental physiological events coordinating these behaviors remain elusive. We sought to understand how voiding function is influenced by the rate at which the bladder fills. We hypothesized that faster filling rates would increase afferent sensory activity and increase micturition rate. In vivo, this would mean animals experiencing faster bladder filling would void more frequently with smaller void volumes. To test this hypothesis, we measured afferent nerve activity during different filling rates using an ex vivo mouse bladder preparation and assessed voiding frequency in normally behaving mice noninvasively (UroVoid). Bladder afferent nerve activity depended on the filling rate, with faster filling increasing afferent nerve activity at a given volume. Voiding behavior in vivo was measured in UroVoid cages. Male and female mice were given access to tap water or, to induce faster bladder filling rates, water containing 5% sucrose. Fluid intake increased dramatically in mice consuming 5% sucrose. As expected, micturition frequency was elevated in the sucrose group. However, even with the greatly increased rate of urine production, void volumes were unchanged in both genders. Although faster filling rates generated higher afferent nerve rates ex vivo, this did not translate into more frequent, smaller-volume voids in vivo. This suggests afferent nerve activity is only one factor contributing to the switch from bladder filling to micturition. Together with afferent nerve activity, higher centers in the central nervous system and the state of arousal are likely critical to coordinating the micturition reflex.
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Affiliation(s)
- Thomas J. Heppner
- 1Department of Pharmacology, University of Vermont, Burlington, Vermont
| | - Grant W. Hennig
- 1Department of Pharmacology, University of Vermont, Burlington, Vermont
| | - Mark T. Nelson
- 1Department of Pharmacology, University of Vermont, Burlington, Vermont,2Institute of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Gerald M. Herrera
- 1Department of Pharmacology, University of Vermont, Burlington, Vermont
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Franken J, De Bruyn H, Rietjens R, Segal A, De Ridder D, Everaerts W, Voets T, Vande Velde G. X-ray videocystometry for high-speed monitoring of urinary tract function in mice. SCIENCE ADVANCES 2021; 7:7/30/eabi6821. [PMID: 34301607 PMCID: PMC8302127 DOI: 10.1126/sciadv.abi6821] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 06/08/2021] [Indexed: 06/13/2023]
Abstract
Lower urinary tract dysfunction (LUTd) represents a major health care problem with a high, unmet medical need. Design of additional therapies for LUTd requires precise tools to study bladder storage and voiding (dys)function in animal models. We developed videocystometry in mice, combining intravesical pressure measurements with high-speed fluoroscopy of the urinary tract. Videocystometry substantially outperforms current state-of-the-art methods to monitor the urine storage and voiding process, by enabling quantitative analysis of voiding efficiency, urethral flow, vesicoureteral reflux, and the relation between intravesical pressure and flow, in both anesthetized and awake, nonrestrained mice. Using videocystometry, we identified localized bladder wall micromotions correlated with different states of the filling/voiding cycle, revealed an acute effect of TRPV1 channel activation on voiding efficiency, and pinpointed the effects of urethane anesthesia on urine storage and urethral flow. Videocystometry has broad applications, ranging from the elucidation of molecular mechanisms of bladder control to drug development for LUTd.
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Affiliation(s)
- Jan Franken
- Laboratory of Ion Channel Research (LICR), VIB-KU Leuven Centre for Brain and Disease Research, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Helene De Bruyn
- Laboratory of Ion Channel Research (LICR), VIB-KU Leuven Centre for Brain and Disease Research, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Roma Rietjens
- Laboratory of Ion Channel Research (LICR), VIB-KU Leuven Centre for Brain and Disease Research, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Andrei Segal
- Laboratory of Ion Channel Research (LICR), VIB-KU Leuven Centre for Brain and Disease Research, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Dirk De Ridder
- Laboratory of Organ System, Department of Development and Regeneration, KU Leuven, Leuven, Belgium
| | - Wouter Everaerts
- Laboratory of Organ System, Department of Development and Regeneration, KU Leuven, Leuven, Belgium
| | - Thomas Voets
- Laboratory of Ion Channel Research (LICR), VIB-KU Leuven Centre for Brain and Disease Research, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium.
| | - Greetje Vande Velde
- Biomedical MRI, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
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Andersson KE, Christ GJ, Davies KP, Rovner ES, Melman A. Gene Therapy for Overactive Bladder: A Review of BK-Channel α-Subunit Gene Transfer. Ther Clin Risk Manag 2021; 17:589-599. [PMID: 34113116 PMCID: PMC8187094 DOI: 10.2147/tcrm.s291798] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 04/16/2021] [Indexed: 01/04/2023] Open
Abstract
A need exists for local (ie, bladder-specific) interventions to treat overactive bladder (OAB) with low risk of unwanted postprocedural outcomes. Gene therapy targeted to leverage endogenous physiology in bladder cells may assist in restoring normal cell and organ function. Herein, we review the potential promise of gene therapy for treating OAB, focusing on gene transfer of URO-902, a non-viral naked plasmid DNA expressing the big potassium (BK) channel. We searched PubMed for articles concerning functional aspects of the BK channel and its potential use for gene transfer as local OAB treatment. Results from preclinical, phase 1, and phase 2 studies of URO-902 for erectile dysfunction and phase 1 studies of URO-902 for OAB are included. The BK channel has been extensively studied; however, URO-902 is the first gene therapy used in clinical trials directed toward treating OAB via the BK channel. In both URO-902 studies, there were no serious adverse events considered treatment related and no adverse events leading to early withdrawal. Both studies included secondary efficacy endpoints with promising results suggesting improvement in OAB symptoms, and quality of life, with use of URO-902 versus placebo. Gene therapy involving the BK channel, such as gene transfer with URO-902, has demonstrated promising safety and efficacy results in women with OAB. Findings warrant further investigation of the use of URO-902 for OAB treatment.
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Affiliation(s)
- Karl-Erik Andersson
- Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - George Joseph Christ
- Department of Biomedical Engineering, University of Virginia Medical School, Charlottesville, VA, USA
| | - Kelvin P Davies
- Department of Urology, Albert Einstein College of Medicine, New York, NY, USA
| | - Eric S Rovner
- Department of Urology, Medical University of South Carolina, Charleston, SC, USA
| | - Arnold Melman
- Department of Urology, Albert Einstein College of Medicine, Ardsley, NY, USA
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Nagle AS, Cullingsworth ZE, Li R, Carucci LR, Klausner AP, Speich JE. Bladder wall micromotion measured by non-invasive ultrasound: initial results in women with and without overactive bladder. AMERICAN JOURNAL OF CLINICAL AND EXPERIMENTAL UROLOGY 2021; 9:44-52. [PMID: 33816693 PMCID: PMC8012835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 01/11/2021] [Indexed: 06/12/2023]
Abstract
OBJECTIVE Rhythmic contractions of the bladder wall during filling result from the synchronization of bladder wall micromotion and are often observed in the urodynamic tracings of individuals with urinary overactive bladder (OAB). This study's objective was to develop a novel, non-invasive method to measure bladder wall micromotion and to conduct an initial study to test the hypothesis that elevated micromotion is associated with OAB. METHODS This prospective study enrolled women with OAB and asymptomatic volunteers as measured by the ICIQ-OAB survey. After filling the bladder to 40% cystometric capacity, 85 second cine-loops were obtained using a GE Voluson E8 ultrasound system with an 8 MHz curved, abdominal probe. A custom correlation-based texture tracking MATLAB algorithm was used to measure changes in the bladder wall thickness over time and correlate with changes in vesical pressure. Significant bladder wall micromotion was defined as changes in wall thickness with amplitudes higher than 0.1 mm in the frequency range of 1.75-6 cycles/minute as calculated from Fast Fourier Transform (FFT) analysis. The micromotion algorithm was tested on 30 women including 17 with OAB and 13 asymptomatic volunteers. RESULTS Micromotion was identified in 41% of subjects with OAB and 0% of asymptomatic volunteers, indicating a significant association of micromotion with OAB (Fisher's exact test, P=0.010). Micromotion was also found to have a significant association with a clinical diagnosis of detrusor overactivity (Fisher's exact test, P=0.031). Frequencies with elevated micromotion correlated with frequencies of vesical pressure fluctuations. CONCLUSIONS The feasibility of a non-invasive method to measure bladder wall micromotion was demonstrated using transabdominal anatomical motion mode (M-mode) ultrasound. Presence of micromotion was significantly associated with OAB and with urodynamic-identified rhythm.
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Affiliation(s)
- Anna S Nagle
- Department of Mechanical & Nuclear Engineering, Virginia Commonwealth University College of EngineeringRichmond, VA, USA
| | - Zachary E Cullingsworth
- Department of Mechanical & Nuclear Engineering, Virginia Commonwealth University College of EngineeringRichmond, VA, USA
| | - Rui Li
- Department of Mechanical & Nuclear Engineering, Virginia Commonwealth University College of EngineeringRichmond, VA, USA
| | - Laura R Carucci
- Department of Radiology, Virginia Commonwealth University School of MedicineRichmond, VA, USA
| | - Adam P Klausner
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of MedicineRichmond, VA, USA
- Department of Surgery/Division of Urology Hunter Holmes McGuire Veterans Affairs Medical CenterRichmond, VA, USA
| | - John E Speich
- Department of Mechanical & Nuclear Engineering, Virginia Commonwealth University College of EngineeringRichmond, VA, USA
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