Which molecular targets do we need to focus on to improve lower urinary tract dysfunction? ICI-RS 2017

Stress Urinary Incontinence: An Unsolved Clinical Challenge

Stress urinary incontinence is still a frequent problem for women and men, which leads to pronounced impairment of the quality of life and withdrawal from the social environment. Modern diagnostics and therapy improved the situation for individuals affected. But there are still limits, including the correct diagnosis of incontinence and its pathophysiology, as well as the therapeutic algorithms. In most cases, patients are treated with a first-line regimen of drugs, possibly in combination with specific exercises and electrophysiological stimulation. When conservative options are exhausted, minimally invasive surgical therapies are indicated. However, standard surgeries, especially the application of implants, do not pursue any causal therapy. Non-absorbable meshes and ligaments have fallen into disrepute due to complications. In numerous countries, classic techniques such as colposuspension have been revived to avoid implants. Except for tapes in the treatment of stress urinary incontinence in women, the literature on randomized controlled studies is insufficient. This review provides an update on pharmacological and surgical treatment options for stress urinary incontinence; it highlights limitations and formulates wishes for the future from a clinical perspective.

Mechanosensitive Hydrolysis of ATP and ADP in Lamina Propria of the Murine Bladder by Membrane-Bound and Soluble Nucleotidases

Prior studies suggest that urothelium-released adenosine 5′-triphosphate (ATP) has a prominent role in bladder mechanotransduction. Urothelial ATP regulates the micturition cycle through activation of purinergic receptors that are expressed in many cell types in the lamina propria (LP), including afferent neurons, and might also be important for direct mechanosensitive signaling between urothelium and detrusor. The excitatory action of ATP is terminated by enzymatic hydrolysis, which subsequently produces bioactive metabolites. We examined possible mechanosensitive mechanisms of ATP hydrolysis in the LP by determining the degradation of 1,N⁶-etheno-ATP (eATP) at the anti-luminal side of nondistended (empty) or distended (full) murine (C57BL/6J) detrusor-free bladder model, using HPLC. The hydrolysis of eATP and eADP was greater in contact with LP of distended than of nondistended bladders whereas the hydrolysis of eAMP remained unchanged during filling, suggesting that some steps of eATP hydrolysis in the LP are mechanosensitive. eATP and eADP were also catabolized in extraluminal solutions (ELS) that were in contact with the LP of detrusor-free bladders, but removed from the organ chambers prior to addition of substrate. The degradation of both purines was greater in ELS from distended than from nondistended preparations, suggesting the presence of mechanosensitive release of soluble nucleotidases in the LP. The released enzyme activities were affected differently by Ca²⁺ and Mg²⁺. The common nucleotidase inhibitors ARL67156, POM-1, PSB06126, and ENPP1 Inhibitor C, but not the alkaline phosphatase inhibitor (-)-p-bromotetramisole oxalate, inhibited the enzymes released during bladder distention. Membrane-bound nucleotidases were identified in tissue homogenates and in concentrated ELS from distended preparations by Wes immunodetection. The relative distribution of nucleotidases was ENTPD1 >> ENPP1 > ENTPD2 = ENTPD3 > ENPP3 = NT5E >> ENTPD8 = TNAP in urothelium and ENTPD1 >> ENTPD3 >> ENPP3 > ENPP1 = ENTPD2 = NT5E >> ENTPD8 = TNAP in concentrated ELS, suggesting that regulated ectodomain shedding of membrane-bound nucleotidases possibly occurs in the LP during bladder filling. Mechanosensitive degradation of ATP and ADP by membrane-bound and soluble nucleotidases in the LP diminishes the availability of excitatory purines in the LP at the end of bladder filling. This might be a safeguard mechanism to prevent over-excitability of the bladder. Proper proportions of excitatory and inhibitory purines in the bladder wall are determined by distention-associated purine release and purine metabolism.

Relaxin-2 during pregnancy according to glycemia, continence status, and pelvic floor muscle function

INTRODUCTION AND HYPOTHESIS

To investigate relaxin-2 concentration comparing gestational diabetes mellitus (GDM) and non-GDM patients during pregnancy according to urinary incontinence (UI) and pelvic function status.

METHODS

This is a cross-sectional study evaluating 282 pregnant women from 24 weeks of gestation. The participants were divided into two groups, non-GDM and GDM, according to American Diabetes Association's diabetes mellitus gestational threshold. In addition, according to subanalysis, both groups were subdivided according to the presence of pregnancy-specific urinary incontinence: non-GDM continent, non-GDM incontinent, GDM continent, and GDM incontinent. All participants filled in questionnaires on clinical, obstetric, and urinary continence status (International Consultation on Incontinence Questionnaire-Short Form, ICIQ-SF, and Incontinence Severity Index, ISI), followed by pelvic floor muscle evaluation by the PERFECT scheme in which strength, endurance, and speed of contractions were evaluated.

RESULTS

Serum relaxin-2 concentrations were significantly lower in pregnant women with pregnancy-specific urinary incontinence in both non-GDM and GDM patients, but GDM showed the lowest concentration. In addition, the stratification of the groups according to pelvic floor muscle strength showed that pregnant patients with GDM and modified Oxford scale 0-2 had significantly lower levels than those who were non-GDM and GDM with Modified Oxford Scale 3-5. Relaxin-2 level was much lower in GDM incontinent pregnant women with MOS 0-2 compared to the other three groups.

CONCLUSIONS

Lower relaxin-2 concentration was associated with the presence of pregnancy-specific urinary incontinence, but the combination of GDM, pregnancy-specific urinary incontinence, and lower levels of pelvic floor strength led to lower levels of relaxin-2 compared to the other three groups.

Effects of fatty acid metabolites on nocturia

Dysregulation of circadian rhythm can cause nocturia. Levels of fatty acid metabolites, such as palmitoylethanolamide (PEA), 9-hydroxy-10E,12Z-octadecadienoic acid (9-HODE), and 4-hydroxy-5E,7Z,10Z,13Z,16Z,19Z-docosahexaenoic acid (4-HDoHE), are higher in the serum of patients with nocturia; however, the reason remains unknown. Here, we investigated the circadian rhythm of fatty acid metabolites and their effect on voiding in mice. WT and Clock mutant (ClockΔ19/Δ19) mice, a model for nocturia with circadian rhythm disorder, were used. Levels of serum PEA, 9-HODE, and 4-HDoHEl were measured every 8 h using LC/MS. Voiding pattern was recorded using metabolic cages after administration of PEA, 9-HODE, and 4-HDoHE to WT mice. Levels of serum PEA and 9-HODE fluctuated with circadian rhythm in WT mice, which were lower during the light phase. In contrast, circadian PEA and 9-HODE level deteriorated or retreated in ClockΔ19/Δ19 mice. Levels of serum PEA, 9-HODE, and 4-HDoHE were higher in ClockΔ19/Δ19 than in WT mice. Voiding frequency increased in PEA- and 4-HDoHE-administered mice. Bladder capacity decreased in PEA-administered mice. The changes of these bladder functions in mice were similar to those in elderly humans with nocturia. These findings highlighted the novel effect of lipids on the pathology of nocturia. These may be used for development of biomarkers and better therapies for nocturia.

Prostanoid TP receptor stimulation enhances contractile activities in guinea pig urinary bladder smooth muscle through activation of Ca2+ entry channels: Potential targets in the treatment of urinary bladder contractile dysfunction

AIMS

We examined the potential stimulatory effects of U46619 (a prostanoid TP receptor agonist) and five prostanoids on the contractile activities of urinary bladder smooth muscle (UBSM), focusing on the role of the TP receptor and its associated Ca²⁺ influx routes to understand the roles of prostanoids in the regulation of UB contractile activity.

MAIN METHODS

Changes in the basal tone and spontaneous contractile activity (amplitude and frequency) of isolated guinea pig UBSM were measured isotonically. The presence of TP receptors in UBSM was examined by RT-qPCR and immunofluorescence.

KEY FINDINGS

U46619, prostaglandin (PG) E₂, PGF_2α, and PGA₂ enhanced UBSM basal tone and spontaneous contractile activities, which were measured as amplitudes and frequencies. The enhancing effects of U46619 were completely suppressed by SQ 29,548 (a TP receptor antagonist), which also partially suppressed the stimulating effects of other prostanoids. The expression of TP receptors in UBSMs was verified at the mRNA and protein level. The enhancing effects of U46619 completely disappeared in Ca²⁺-free solution. U46619-enhanced basal tone was completely suppressed by verapamil, an inhibitor of voltage-dependent Ca²⁺ channels (VDCCs), and verapamil strongly decreased the spontaneous contraction frequency. The spontaneous contractions remaining in the presence of verapamil were strongly suppressed by SKF-96365 (an inhibitor of receptor-operated Ca²⁺ channels (ROCCs)/store-operated Ca²⁺ channels (SOCCs)), but not by LOE-908 (an inhibitor of ROCCs).

SIGNIFICANCE

Prostanoids can enhance UBSM contractile activities and thus may be endogenous candidates for induction of detrusor overactivity. The TP receptor and TP-receptor-activated VDCCs/SOCCs are key molecules responsible for these effects.

Detrusor underactivity causes neurogenic voiding dysfunction in a rat bilateral accessory nerve-injury model

We aimed to investigate detrusor function in a previously developed rat neurogenic voiding dysfunction model that we have developed previously. We performed sham or bilateral accessory nerve injury (BACNI) surgeries on ten-week-old male Wistar/ST rats. One week after surgery, we evaluated detrusor contractility in the bladder using isometric tension and mRNA expression assays. Cholinergic contraction was attenuated in the injury model, whereas carbachol-evoked contraction was enhanced, and mRNA expression of the cholinergic receptor increased. These findings suggest that there was a reduction in neurotransmitter release causing detrusor underactivity.

MicroRNA-219c-5p regulates bladder fibrosis by targeting FN1

BACKGROUND

We found that the bladders of multiple sclerosis mice were significantly fibrotic. This study aimed to investigate the relationship between fibronectin 1 (FN1) and bladder fibrosis, as well as the microRNAs involved in FN1 regulation.

METHODS

The degree of bladder smooth muscle fibrosis was observed by immunohistochemistry. In addition, we used quantitative real-time polymerase chain reaction (RT-qPCR) and Western blotting to determine FN1 expression in bladders with different grades of fibrosis. Bioinformatics analysis revealed that miR-199a-3p, miR-219c-5p and miR-3572-3p could inhibit FN1 synthesis. Therefore, miR-199a-3p, miR-219c-5p and miR-3572-3p were overexpressed or knocked down in bladder smooth muscle cells (BSMCs), and the respective transfection and FN1 knockdown efficiencies were detected by RT-qPCR. Only miR-219c-5p overexpression and knockdown produced the expected results. A dual luciferase reporter assay was used to determine the targeting relationship between miR-219c-5p and FN1. Flow cytometry and Cell Counting Kit 8 (CCK8) experiments confirmed that miR-219c-5p reduced FN1 expression and affected the biological activity of smooth muscle cells. Agomir and anagomir of miR-219c-5p were transfected in vivo to observe the change of bladder fibrosis in mice.

RESULTS

With increasing bladder fibrosis, FN1 expression increased, while miR-199a-3p, miR-219c-5p, and miR-3572-3p expression levels decreased. The RT-qPCR results after transfection showed that only miR-219c-5p could regulate FN1. Indeed, the dual luciferase reporter assay results indicated that miR-219c-5p targeted FN1 directly. CCK8 and cell cycle assays showed that miR-219c-5p overexpression inhibited BSMC proliferation, while miR-219c-5p knockdown promoted BSMC proliferation. An apoptosis assay showed that miR-219c-5p overexpression promoted apoptosis, while miR-219c-5p knockdown inhibited BSMC apoptosis. The agomir and anagomir transfected with miR-219c-5p in vivo found that the bladder fibrosis of the mice in the agomir group was reduced, and the anagomir group was worse.

CONCLUSIONS

Our findings indicate that FN1 up-regulation and miR-219c-5p down-regulation play an important role in the development of bladder fibrosis, and miR-219c-5p participates in bladder fibrosis by regulating FN1 expression. Thus, a novel antifibrotic function of miR-219c-5p is proposed, which may represent a potential target for the diagnosis and treatment of bladder fibrosis.

International Union of Basic and Clinical Pharmacology. CIX. Differences and Similarities between Human and Rodent Prostaglandin E2 Receptors (EP1-4) and Prostacyclin Receptor (IP): Specific Roles in Pathophysiologic Conditions

Prostaglandins are derived from arachidonic acid metabolism through cyclooxygenase activities. Among prostaglandins (PGs), prostacyclin (PGI2) and PGE2 are strongly involved in the regulation of homeostasis and main physiologic functions. In addition, the synthesis of these two prostaglandins is significantly increased during inflammation. PGI2 and PGE2 exert their biologic actions by binding to their respective receptors, namely prostacyclin receptor (IP) and prostaglandin E2 receptor (EP) 1-4, which belong to the family of G-protein-coupled receptors. IP and EP1-4 receptors are widely distributed in the body and thus play various physiologic and pathophysiologic roles. In this review, we discuss the recent advances in studies using pharmacological approaches, genetically modified animals, and genome-wide association studies regarding the roles of IP and EP1-4 receptors in the immune, cardiovascular, nervous, gastrointestinal, respiratory, genitourinary, and musculoskeletal systems. In particular, we highlight similarities and differences between human and rodents in terms of the specific roles of IP and EP1-4 receptors and their downstream signaling pathways, functions, and activities for each biologic system. We also highlight the potential novel therapeutic benefit of targeting IP and EP1-4 receptors in several diseases based on the scientific advances, animal models, and human studies. SIGNIFICANCE STATEMENT: In this review, we present an update of the pathophysiologic role of the prostacyclin receptor, prostaglandin E2 receptor (EP) 1, EP2, EP3, and EP4 receptors when activated by the two main prostaglandins, namely prostacyclin and prostaglandin E2, produced during inflammatory conditions in human and rodents. In addition, this comparison of the published results in each tissue and/or pathology should facilitate the choice of the most appropriate model for the future studies.

Prostaglandin E2 and F2alpha Modulate Urinary Bladder Urothelium, Lamina Propria and Detrusor Contractility via the FP Receptor

Current pharmacological treatment options for many bladder contractile dysfunctions are not suitable for all patients, thereby bringing interest to the investigation of therapies that target a combination of receptors. This study aimed to compare responses of PGE₂ on the urinary bladder urothelium with lamina propria (U&LP, also called the bladder mucosa) or detrusor smooth muscle and attempt to identify the receptor subtypes mediating PGE₂ contractile responses in these tissues. In the presence of selective EP1 – 4 receptor antagonists, varying concentrations of PGE₂ were applied to isolated strips of porcine U&LP and detrusor that were mounted in organ baths filled with Krebs-bicarbonate solution and gassed with carbogen. The addition of PGE₂ (1 and 10 μM) and PGF_2α (10 μM) to U&LP preparations caused significant increases in the baseline tension and in the spontaneous phasic contractile frequency. In detrusor preparations, significant increases in the baseline tension were observed in response to PGE₂ (1 and 10 μM) and PGF_α (10 μM), and spontaneous phasic contractions were initiated in 83% of preparations. None of the selective PGE₂ receptor antagonists inhibited the increases in baseline tension in both U&LP and detrusor. However, the antagonism of PGF_2α receptor showed significantly inhibited contractile responses in both layers of the bladder. This study presents prostaglandin receptor systems as a potential regulator of urinary bladder contractility. The main contractile effects of PGE₂ in both U&LP and detrusor are mediated via the FP receptor with no observed contribution from any of the four EP receptors.

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

INTRODUCTION

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

EVIDENCE ACQUISITION

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

EVIDENCE SYNTHESIS

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

CONCLUSIONS

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

Inhibition of Female and Male Human Detrusor Smooth Muscle Contraction by the Rac Inhibitors EHT1864 and NSC23766

Introduction

Lower urinary tract symptoms (LUTS) due to overactive bladder (OAB) are caused by spontaneous detrusor contractions. Medical treatment with muscarinic receptor antagonists or β₃-adrenoceptor agonists aims to inhibit detrusor contractions, but overall results are unsatisfactory. Consequently, improved understanding of bladder smooth muscle contraction and identification of novel compounds for its inhibition are needed to develop alternative options. A role of the GTPase Rac1 for smooth muscle contraction has been reported from the prostate, but is unknown in the human detrusor. Here, we examined effects of the Rac inhibitors NSC23766, which may also antagonize muscarinic receptors, and EHT1864 on contraction of human detrusor tissues.

Methods

Female and male human detrusor tissues were obtained from radical cystectomy. Effects of NSC23766 (100 µM) and EHT1864 (100 µM) on detrusor contractions were studied in an organ bath.

Results

Electric field stimulation induced frequency-dependent contractions of detrusor tissues, which were inhibited by NSC23766 and EHT1864. Carbachol induced concentration-dependent contractions. Concentration response curves for carbachol were shifted to the right by NSC23766, reflected by increased EC₅₀ values, but unchanged E_max values. EHT1864 reduced carbachol-induced contractions, resulting in reduced E_max values for carbachol. The thromboxane analog U46619 induced concentration-dependent contractions, which remained unchanged by NSC23766, but were reduced by EHT1864.

Conclusions

NSC23766 and EHT1864 inhibit female and male human detrusor contractions. NSC23766, but not EHT1864 competitively antagonizes muscarinic receptors. In addition to neurogenic and cholinergic contractions, EHT1864 inhibits thromboxane A₂-induced detrusor contractions. The latter may be promising, as the origin of spontaneous detrusor contractions in OAB is noncholinergic. In vivo, both compounds may improve OAB-related LUTS.

Histamine modulation of urinary bladder urothelium, lamina propria and detrusor contractile activity via H1 and H2 receptors

The mechanisms underlying bladder contractile disorders such as overactive bladder are not fully understood, and there is limited understanding of the receptor systems modulating spontaneous bladder contractions. We investigated the potential for histamine to have a role in mediating contractility of the urothelium with lamina propria (U&LP) or detrusor via the H1-H4 histamine receptor subtypes. Isolated strips of porcine U&LP or detrusor smooth muscle were mounted in gassed Krebs-bicarbonate solution and responses to histamine obtained in the absence and presence of selective receptor antagonists. The presence of histamine increases the frequency of U&LP spontaneous phasic contractions and baseline tensions. In response to histamine, H1-antagonists pyrilamine, fexofenadine and cyproheptadine were effective at inhibiting contractile responses. Cimetidine (H2-antagonist) enhanced increases in baseline tension in response histamine, whereas amthamine (H2-agonist) induced relaxation. Although thioperamide (H3/H4-antagonist) increased baseline tension responses to histamine, selective H1/H2-receptor antagonism revealed no influence of these receptors. In detrusor preparations, pyrilamine, fexofenadine and cyproheptadine were effective at inhibiting baseline tension increases in response to histamine. Our findings provide evidence that histamine produces contractile responses both in the U&LP and detrusor via the H1-receptor, and this response is significantly inhibited by activation of the H2-receptor in the U&LP but not the detrusor.