Obstruction-induced alterations within the urinary bladder and their role in the pathophysiology of lower urinary tract symptomatology

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.

β-Adrenoceptors regulate urothelial inflammation and zonula occludens in the bladder outlet obstruction model

BACKGROUND

The purpose of this study was to evaluate the effects of β-adrenoceptors (ADRBs) on the urothelial inflammation and zonula occludens (ZO) in a rat PBOO model and in an in vitro model.

METHODS

The PBOO model was established by ligating the bladder neck of rats. Twenty rats were divided into 4 groups: sham operation, PBOO + normal saline, PBOO + ADRB2 agonist, PBOO + ADRB3 agonist. PBOO rats were with treated with ADRBs agonists for 3 weeks. Human urothelial cells (HUCs) were subjected to ADRBs agonist treatment or hydrostatic pressure in an in vitro model.

RESULTS

In the PBOO group, there was a significant increase in the expression of MCP-1, IL-6 and RANTES compared to the sham group. By contrast, there was a post-PBOO decline in the expression of ZO-1 and ZO-2 in the urothelium. ADRB2 or ADRB3 agonists exhibited downregulated inflammatory cytokine expression and increased ZO expression in the PBOO model. The regulation of inflammation and ZO by ADRB2 and ADRB3 agonists in an in vitro model was found consistent with that in the PBOO model. Moreover, RhoA and ROCK inhibitors suppressed the expression of hydrostatic pressure-induced inflammatory cytokines. Additionally, RhoA agonist reversed the inhibitory effect of ADRBs agonists on the inflammatory secretion from HUCs.

CONCLUSIONS

ADRB2 and ADRB3 agonists increased ZO protein expression in HUCs in a rat PBOO model and in an in vitro model. Furthermore, ADRB2 and ADRB3 agonists inhibited the secretion of inflammatory cytokines from HUCs by regulating the RhoA/ROCK signaling pathways.

YAP/Smad3 promotes pathological extracellular matrix microenviroment-induced bladder smooth muscle proliferation in bladder fibrosis progression

Fibrosis is a chronic inflammation process with excess extracellular matrix (ECM) deposition that cannot be reversed. Patients suffer from bladder dysfunction caused by bladder fibrosis. Moreover, the interactive mechanisms between ECM and bladder fibrosis are still obscure. Hence, we assessed the pivotal effect of Yes-associated protein (YAP) on the proliferation of bladder smooth muscle in fibrosis process. We identified that stiff ECM increased the expression and translocation of YAP in the nucleus of human bladder smooth muscle cell (hBdSMC). Sequencings and proteomics revealed that YAP bound to Smad3 and promoted the proliferation of hBdSMC via MAPK/ERK signaling pathway in stiff ECM. Moreover, CUT and TAG sequencing and dual-luciferase assays demonstrated that Smad3 inhibited the transcription of JUN. The YAP inhibitor CA3 was used in a partial bladder outlet obstruction (pBOO) rat model. The results showed that CA3 attenuated bladder smooth muscle proliferation. Collectively, YAP binding with Smad3 in the nucleus inhibited the transcription of JUN, and promoted the proliferation of bladder smooth muscle through the MAPK/ERK signaling pathway. The current study identified a novel mechanism of mechanical force induced bladder fibrosis that provided insights in YAP-associated organ fibrosis.

Survivin knockdown alleviates pathological hydrostatic pressure-induced bladder smooth muscle cell dysfunction and BOO-induced bladder remodeling via autophagy

Aim: Bladder outlet obstruction (BOO) leads to bladder wall remodeling accompanying the progression from inflammation to fibrosis where pathological hydrostatic pressure (HP)-induced alteration of bladder smooth muscle cells (BSMCs) hypertrophic and excessive extracellular matrix (ECM) deposition play a pivotal role. Recently, we have predicted survivin (BIRC5) as a potential hub gene that might be critical during bladder fibrosis by bioinformatics analyses from rat BOO bladder, but its function during BOO progression remains unknown. Here, we investigated the role of survivin protein on bladder dysfunction of BOO both in vitro and in vivo. Methods: Sprague-Dawley female rats were divided into three groups: control group, BOO group, and BOO followed by the treatment with YM155 group. Bladder morphology and function were evaluated by Masson staining and urodynamic testing. To elucidate the underlying mechanism, hBSMCs were subjected to pathological HP of 200 cm H2O and co-cultured with the presence or absence of survivin siRNA and/or autophagy inhibitor 3-MA. Autophagy was evaluated by the detection of Beclin1 and LC3B-II expression, proliferation was conducted by the EdU analysis and PCNA expression, and fibrosis was assessed by the examination of Col 1 and Fn expression. Results: BOO led to a gradual alteration of hypertrophy and fibrosis of the bladder, and subsequently induced bladder dysfunction accompanied by increased survivin expression, while these histological and function changes were attenuated by the treatment with YM155. HP significantly increased survivin expression, upregulated Col1 and Fn expression, enhanced proliferation, and downregulated autophagy markers, but these changes were partially abolished by survivin siRNA treatment, which was consistent with the results of the BOO rat experiment. In addition, the anti-fibrotic and anti-proliferative effects of the survivin siRNA treatment on hBSMCs were diminished after the inhibition of autophagy by the treatment with 3-MA. Conclusion: In summary, the upregulation of survivin increased cell proliferation and fibrotic protein expression of hBSMC and drove the onset of bladder remodeling through autophagy during BOO. Targeting survivin in pathological hBSMCs could be a promising way to anti-fibrotic therapeutic approach in bladder remodeling secondary to BOO.

Human amniotic fluid stem cells can alleviate detrusor dysfunction caused by bladder outlet obstruction in rats

The present study examined whether bladder detrusor dysfunction due to partial bladder outlet obstruction (pBOO) could be improved after the treatment of human amniotic fluid stem cells (hAFSCs). 72 female rats were grouped into sham operation, pBOO, and pBOO with hAFSCs treatment (pBOO + hAFSCs) for in vitro and in vivo studies. Bladder weight, bladder wall thickness, the ratio of collagen to smooth muscle and the levels of positive CD11b/c and HIS48 cells was significantly increased after pBOO but improved after hAFSCs treatment. Cystometries showed impaired bladder function after pBOO. Protein and mRNA levels of hypoxia inducible factor-1α, CCL2, interleukin-1β, transforming growth factor-β1 (TGF-β1), connective tissue growth factor (CTGF), α-smooth muscle actin, collagen I and collagen III were increased at 2 and/or 6 weeks, but proteins and mRNA expressions of protein gene product 9.5 were decreased at 2 and 6 weeks after pBOO. These abnormalities were improved after hAFSCs treatment. The expressions of TGF-β1 and CTGF in cultured detrusor cells of pBOO rats were increased but were improved after hAFSCs treatment. The present results showed hAFSCs treatment could improve bladder detrusor dysfunction in pBOO rats, which may be related to the reduction of inflammatory and pro-fibrotic markers in detrusor muscle cells.

Inhibition of DNA methylation during chronic obstructive bladder disease (COBD) improves function, pathology and expression

Partial bladder outlet obstruction due to prostate hyperplasia or posterior urethral valves, is a widespread cause of urinary dysfunction, patient discomfort and also responsible for immense health care costs. Even after removal or relief of obstruction, the functional and pathologic aspects of obstruction remain as a chronic obstructive bladder disease (COBD). Epigenetic changes, such as DNA methylation, contribute to the persistent character of many chronic diseases, and may be altered in COBD. We tested whether candidate genes and pathways and the pathophysiology of COBD were affected by a hypomethylating agent, decitabine (DAC). COBD was created in female Sprague-Dawley rats by surgical ligation of the urethra for 6 weeks, followed by removal of the suture. Sham ligations were performed by passing the suture behind the urethra. After removal of the obstruction or sham removal, animals were randomized to DAC treatment (1 mg/kg/3-times/week intraperitoneally) or vehicle (normal saline). Bladder function was non-invasively tested using metabolic cages, both one day prior to de-obstruction at 6 weeks and prior to sacrifice at 10 weeks. Residual volume and bladder mass were measured for each bladder. Bladders were examined by immunostaining as well as qPCR. The effects of DNA methyltransferase (DNMT)-3A knockout or overexpression on smooth muscle cell (SMC) function and phenotype were also examined in bladder SMC and ex vivo culture. Residual volumes of the DAC treated group were not significantly different from the NS group. Compared to COBD NS, COBD DAC treatment helped preserve micturition volume with a significant recovery of the voiding efficiency (ratio of the maximum voided volume/maximum bladder capacity) by one third (Fig. 1, p > 0.05). Brain-derived neurotrophic factor (BDNF) variants 1 and 5 were upregulated by COBD and significantly reduced by DAC treatment. Deposition of collagen in the COBD bladder was reduced by DAC, but gross hypertrophy remained. In bladder SMC, DNMT3A overexpression led to a loss of contractile function and phenotype. In bladders, persistently altered by COBD, inhibition of DNA-methylation enhances functional recovery, unlike treatment during partial obstruction, which exacerbates obstructive pathology. The underlying mechanisms may relate to the gene expression changes in BDNF and their effects on signaling in the bladder.

Dietary reversal reverts diet-induced alterations in obstructed bladders of Wistar rats

OBJECTIVES

The aim of this study was to investigate the effects of diet reversal to standard chow on diet-induced changes in structure and function of normal and obstructed bladders in male Wistar rats.

METHODS

Eighty animals were equally divided into sham-surgery and bladder outlet obstruction (BOO) dietary groups and fed standard chow (control), high-carbohydrate, high-fat, and high-protein diets. BOO groups had surgically induced BOO, whereas sham surgery was performed on sham groups at the end of week 8. Animals were continued on the treatment diets for 4 wk after surgery, then the diets were all changed to standard chow for the remainder of the study period. Bladder weight, detrusor contractility, Rho-associated protein kinase (Rho-kinase), and myosin light chain kinase were determined. Polymerase chain reaction was used to assay for transforming growth factor-β, connecting tissue growth factor, hypoxia-inducible factor-1α, and platelet-derived growth factor subunit A levels in the bladder. C-reactive protein, insulin-like growth factor-1, nerve growth factor, and C-X-C motif chemokine ligand 12 concentrations were determined by enzyme-linked immunosorbent assay. The collagen content of the bladder was estimated by liquid chromatography/mass spectrometry.

RESULTS

Reversal of diet to standard chow resulted in reversal of diet-induced changes in all variables measured in obstructed bladders. High-fat-diet-induced alterations in normal bladders were also reversed.

CONCLUSION

The results suggested that in obstructed bladders of animals, reversal of the diet could reverse all diet-associated changes that increase inflammation and fibrosis in obstructed bladders. This is especially important in changes related to high consumption of fatty diets and associated lower urinary tract symptoms.

Can Botulinum Toxin A Still Have a Role in Treatment of Lower Urinary Tract Symptoms/Benign Prostatic Hyperplasia Through Inhibition of Chronic Prostatic Inflammation?

Patients with benign prostatic hyperplasia (BPH) can exhibit various lower urinary tract symptoms (LUTS) owing to bladder outlet obstruction (BOO), prostatic inflammation, and bladder response to BOO. The pathogenesis of BPH involves an imbalance of internal hormones and chronic prostatic inflammation, possibly triggered by prostatic infection, autoimmune responses, neurogenic inflammation, oxidative stress, and autonomic dysfunction. Botulinum toxin A (BoNT-A) is well recognized for its ability to block acetylcholine release at the neuromuscular junction by cleaving synaptosomal-associated proteins. Although current large clinical trials have shown no clinical benefits of BoNT-A for the management of LUTS due to BPH, BoNT-A has demonstrated beneficial effects in certain subsets of BPH patients with LUTS, especially in males with concomitant chronic prostatitis/chronic pelvic pain syndrome and smaller prostate. We conducted a review of published literature in Pubmed, using Botulinum toxin, BPH, BOO, inflammation, LUTS, and prostatitis as the key words. This article reviewed the mechanisms of BPH pathogenesis and anti-inflammatory effects of BoNT-A. The results suggested that to achieve effectiveness, the treatment of BPH with BoNT-A should be tailored according to more detailed clinical information and reliable biomarkers.

Augmentation Cystoplasty of Diseased Porcine Bladders with Bi-Layer Silk Fibroin Grafts

IMPACT STATEMENT

The search for an ideal "off-the-shelf" biomaterial for augmentation cystoplasty remains elusive and current scaffold configurations are hampered by mechanical and biocompatibility restrictions. In addition, preclinical evaluations of potential scaffold designs for bladder repair are limited by the lack of tractable large animal models of obstructive bladder disease that can mimic clinical pathology. The results of this study describe a novel, minimally invasive, porcine model of partial bladder outlet obstruction that simulates clinically relevant phenotypes. Utilizing this model, we demonstrate that acellular, bi-layer silk fibroin grafts can support the formation of vascularized, innervated bladder tissues with functional properties.

Progressive bladder remodeling due to bladder outlet obstruction: a systematic review of morphological and molecular evidences in humans

BACKGROUND

Bladder outlet obstruction is a common urological condition. We aimed to summarize available evidences about bladder outlet obstruction-induced molecular and morphological alterations occurring in human bladder.

METHODS

We performed a literature search up to December 2017 including clinical and preclinical basic research studies on humans. The following search terms were combined: angiogenesis, apoptosis, bladder outlet obstruction, collagen, electron microscopy, extracellular matrix, fibrosis, hypoxia, histology, inflammation, innervation, ischemia, pressure, proliferation, remodeling, suburothelium, smooth muscle cells, stretch, urothelium.

RESULTS

We identified 36 relevant studies. A three-stages model of bladder wall remodeling can be hypothesized involving an initial hypertrophy phase, a subsequent compensation phase and a later decompensation. Histological and molecular alterations occur in the following compartments: urothelium, suburothelium, detrusor smooth muscle cells, detrusor extracellular matrix, nerves. Cyclic stretch, increased hydrostatic and cyclic hydrodynamic pressure and hypoxia are stimuli capable of modulating multiple signaling pathways involved in this remodeling process.

CONCLUSIONS

Bladder outlet obstruction leads to progressive bladder tissue remodeling in humans. Multiple signaling pathways are involved.

High glucose induces the proliferation of prostatic cells via downregulating MRE11

The aim of the present study was to investigate the candidate genes and pathways associated with benign prostatic hyperplasia (BPH) and diabetes. In vitro experiments were performed using normal prostatic epithelial RWPE-1 and HPr-1 cells. The cell lines were treated with a high-glucose solution and MTS and bromodeoxyuridine assays were used to assess cell viability. Transcriptome sequencing was used to screen the candidate genes. The expression of candidate genes was further verified by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting. A meiotic recombination 11 (MRE11) overexpression vector was designed and transfected into RWPE-1 cells to verify the function of MRE11. A streptozotocin-induced diabetic rat model was established and rat MRE11 levels were determined by RT-qPCR and immunohistochemical staining. High concentrations of glucose resulted in RWPE-1 and HPr-1 cells with high viability. Transcriptome sequencing revealed that MRE11 was downregulated when RWPE-1 cells were exposed to high-glucose conditions. When MRE11 was overexpressed, cell viability decreased and cell apoptosis was induced under high-glucose conditions. Prostatic tissues from rats were collected and assessed; MRE11 expression was observed to be decreased, which was consistent with the in vitro cell experiments. BPH may be associated with diabetes, as MRE11 expression in prostatic cells was decreased when exposed to high-glucose conditions. Therefore, MRE11 may have potential as a biomarker for the early diagnosis of BPH and diabetes.

Experience of a Tertiary-Level Urology Center in the Clinical Urological Events of Rare and Very Rare Incidence. VI. Unusual Events in Urolithiasis: 1. Long-Standing Urethral Stones without Underlying Anatomical Abnormalities in Male Children

OBJECTIVES

The study aimed to present our center's experience with long-standing urethral stones in male children with normal urethra.

MATERIALS AND METHODS

Retrospective search of our center data was done for the cases of long-standing urethral stones with normal urethra in male children during the period July 2001 - June 2016. Demographic and clinical data were studied.

RESULTS

Of more than 54,000 urolithiasis procedures, 17 male children (0.031%) were operated for long-standing urethral stones with normal urethra. In 14 cases (82.4%), residence was rural and parental education levels were low or none. All children were regularly prompted voiding with a history of difficulty or dysuria. All the stones lodged in the posterior urethra with an approximate mean duration of 2 months. The mean stone size of 11.29 ± 3.88 mm and rough surfaces in 88.2% of cases represented the main predisposing factors. Major complications included rectal prolapse in 1 case and vesicoureteral reflux in 3 cases. Endoscopic push-back was followed by disintegration in 76.5% or cystolithotomy in 17.7%, while it failed in 1 case that was treated by cystolithotomy.

CONCLUSIONS

Long-standing urethral stones in male children with normal urethra are very rare misdiagnoses. Stone topography and sociocultural factors predisposed to their lodgments and negligence. Endoscopic treatment is the best approach.

Effects of varying degrees of partial bladder outlet obstruction on urinary bladder function of rats: A novel link to inflammation, oxidative stress and hypoxia

OBJECTIVES

The aim of the present study was to investigate the effects of different degrees of obstruction, and the roles of inflammation, oxidative stress, and hypoxia parameters on bladder function.

METHODS

Thirty male Sprague-Dawley rats were divided into 3 groups (n = 10 in each group): (i) sham-operated control; (ii) severe partial bladder outlet obstruction (PBOO); and (iii) moderate PBOO. Severe and moderate PBOO were induced by urethral ligation using 3-Fr and 4-Fr catheters, respectively, for 6 weeks. After 6 weeks, the in vitro contractile responses to carbachol, electrical field stimulation, ATP and KCl were measured in bladder strips. In addition, mRNA and protein expression of nuclear factor kappa B (NF-κB) hypoxia-inducible factor (HIF) and nuclear factor, erythroid 2-like 2 (Nrf2) in bladder were determined by real-time polymerase chain reaction and western blotting. Malondialdehyde (MDA) levels in bladder tissues were also determined.

RESULTS

Rats in the severe PBOO group had the highest bladder weight. Detrusor strips from rats in the severe PBOO group exhibited 61%-82% smaller contractile responses to all four stimuli than those from the sham-operated group. Activity of NF-κB as an inflammatory marker was increased in the severe PBOO group, whereas HIF-1α and HIF-2β protein levels were increased significantly in the moderate PBOO group. A master regulator of oxidative stress, Nrf2 expression was increased in all obstructed rats. MDA levels were higher in the severe PBOO group than in sham-operated group.

CONCLUSION

The results of the present study reveal the importance of oxidative stress-induced NF-κB signaling in bladder dysfunction with severe obstruction. Altered HIF signaling may contribute to the functional impairment after PBOO. Novel and evolving therapies targeting oxidative and/or inflammatory pathways may be a reasonable strategy for the management of lower urinary tract symptoms or benign prostatic hyperplasia.

Sulforaphane Ameliorates Bladder Dysfunction through Activation of the Nrf2-ARE Pathway in a Rat Model of Partial Bladder Outlet Obstruction

Purpose. We evaluated the effect of sulforaphane (SFN) treatment on the function and changes of expression of Nrf2-ARE pathway in the bladder of rats with bladder outlet obstruction (BOO). Materials and Methods. A total of 18 male Sprague-Dawley rats at age of 8 weeks were divided into 3 groups (6 of each): the sham operated group, the BOO group, and the BOO+SFN group. We examined histological alterations and the changes of oxidative stress markers and the protein expression of the Nrf2-ARE pathway. Results. We found that SFN treatment could prolong micturition interval and increase bladder capacity and bladder compliance. However, the peak voiding pressure was lower than BOO group. SFN treatment can ameliorate the increase of collagen fibers induced by obstruction. SFN treatment also increased the activity of SOD, GSH-Px, and CAT compared to the other groups. The level of bladder cell apoptosis was decreased in BOO rats with SFN treatment. Moreover, SFN could reduce the ratio of Bax/Bcl-2 expression. Furthermore, SFN could activate the Nrf2 expression with elevation of its target antioxidant proteins. Conclusions. The sulforaphane-mediated decrease of oxidative stress and activation of the Nrf2-ARE pathway may ameliorate bladder dysfunction caused by bladder outlet obstruction.

Bladder wall thickness in the assessment of neurogenic bladder: a translational discussion of current clinical applications

The prospective trial by Kim et al. "Can Bladder Wall Thickness Predict Videourodynamic Findings in Children with Spina Bifida?" published in Journal of Urology investigated the measurement of bladder wall thickness (BWT) as a non-invasive assessment tool for lower urinary tract changes in neurogenic bladder (NGB). In this study, no significant association was observed between BWT and high-risk urodynamic parameters. This editorial discusses the basic science of bladder wall thickening as well as prior studies relating wall thickness to clinical parameters. Although Kim et al. provide a unique literature contribution in terms of assessment of BWT at defined percent cystometric capacity, specific aspects of study methodology and population may have contributed to a lack of correlation with high-risk urodynamic findings. The application of non-invasive modalities to lower urinary tract assessment of NGB remains a promising and relevant area of future research to prevent progression to end stage lower urinary tract changes for all individuals with spina bifida.

New intraprostatic injectables and prostatic urethral lift for male LUTS

Treatment modalities for male lower urinary tract symptoms (LUTS) comprise a broad spectrum of medical and surgical options. Interest is growing in minimally invasive treatment options, which should ideally be performed in an outpatient setting and have a short recovery time, durable efficacy and a good safety profile. The preservation of all aspects of sexual function, including antegrade ejaculation, seems to be increasingly important for patients. Initial experimental data on new minimally invasive procedures-such as the intraprostatic injection of novel agents including botulinum neurotoxin A (BoNT-A), NX-1207 and PRX302-were promising, but clinical trials have not confirmed the findings. Trials of the mechanical prostatic urethral lift device-Urolift(®) (Neotract, Inc., USA)-have been positive, but further long-term results are needed to confirm its beneficial effects.