Lifelong LUTS: Understanding the bladder's role and implications across transition phases, a comprehensive review.

INTRODUCTION: Lower urinary tract symptoms (LUTSs) are a diverse array of urinary and pelvic dysfunctions that can emerge from childhood, extend through adulthood, and persist into older age. This narrative review aims to provide a comprehensive perspective on the continuum of LUTS and shed light on the underlying mechanisms and clinical implications that span across the lower urinary tract. METHODS: A panel of five experts from Belgium, the Netherlands, India, Denmark, and the United States participated in an intensive research to explore and pinpoint existing insights into the lifelong concept of LUTS, particularly at the pelvic level. The experts reviewed the existing literature and held a webinar to discuss their findings. RESULTS: Childhood LUTS can persist, resolve, or progress into bladder underactivity, dysfunctional voiding, or pain syndromes. The Lifelong character can be explained by pelvic organ cross-talk facilitated through complex neurological and nonneurological interactions. At the molecular level, the role of vasopressin receptors in the bladder's modulation and their potential relevance to therapeutic strategies for LUTS are explored. Frailty emerges as a parallel concept to lifelong LUTS, with a complex and synergistic relationship. Frailty, not solely an age-related condition, accentuates LUTS severity with insufficient evidence regarding the effectiveness and safety profile of the available therapeutic modalities. CONCLUSION: Understanding lifelong LUTSs offers insights into genetic, anatomical, neurological, and molecular mechanisms. Further research could identify predictive biomarkers, elucidate the role of clinically translatable elements in pelvic cross-talk, and uncover molecular signatures for personalized management.

Benign prostatic hyperplasia/obstruction ameliorated using a soluble guanylate cyclase activator.

Benign prostatic hyperplasia (BPH) is a feature of ageing males. Up to half demonstrate bladder outlet obstruction (BOO) with associated lower urinary tract symptoms (LUTS) including bladder overactivity. Current therapies to reduce obstruction, such as α1-adrenoceptor antagonists and 5α-reductase inhibitors, are not effective in all patients. The phosphodiesterase-5 inhibitor (PDE5I) tadalafil is also approved to treat BPH and LUTS, suggesting a role for nitric oxide (NO• ), soluble guanylate cyclase (sGC), and cGMP signalling pathways. However, PDE5I refractoriness can develop for reasons including nitrergic nerve damage and decreased NO• production, or inflammation-related oxidation of the sGC haem group, normally maintained in a reduced state by the cofactor cytochrome-b5-reductase 3 (CYB5R3). sGC activators, such as cinaciguat (BAY 58-2667), have been developed to enhance sGC activity in the absence of NO• or when sGC is oxidised. Accordingly, their effects on the prostate and LUT function of aged mice were evaluated. Aged mice (≥24 months) demonstrated a functional BPH/BOO phenotype, compared with adult animals (2-12 months), with low, delayed voiding responses and elevated intravesical pressures as measured by telemetric cystometry. This was consistent with outflow tract histological and molecular data that showed urethral constriction, increased prostate weight, greater collagen deposition, and cellular hyperplasia. All changes in aged animals were attenuated by daily oral treatment with cinaciguat for 2 weeks, without effect on serum testosterone levels. Cinaciguat had only transient (1 h) cardiovascular effects with oral gavage, suggesting a positive safety profile. The benefit of cinaciguat was suggested by its reversal of an overactive cystometric profile in CYB5R3 smooth muscle knockout mice that mirrors a profile of oxidative dysfunction where PDE5I may not be effective. Thus, the aged male mouse is a suitable model for BPH-induced BOO and cinaciguat has a demonstrated ability to reduce prostate-induced obstruction and consequent effects on bladder function. © 2021 The Pathological Society of Great Britain and Ireland.

Sensory Receptor, Inflammatory, and Apoptotic Protein Expression in the Bladder Urothelium of Patients with Different Subtypes of Interstitial Cystitis/Bladder Pain Syndrome.

The aim of this study was to investigate the expression levels of sensory receptors, inflammatory proteins, and pro-apoptotic proteins in the urothelium of non-Hunner's interstitial cystitis (NHIC) bladders of patients with different clinical and cystoscopic phenotypes. The urothelia from the bladders of 52 NHIC patients were harvested. The expression of sensory receptors, including TRPV1, TRPV4, TRPA1, H1-receptors, and sigma-1 receptors; the inflammatory proteins p38 and tryptase; and the pro-apoptotic proteins, such as caspase-3, BAD, and BAX in the urothelium, were investigated using immunohistochemistry and Western blotting. We compared the expression levels of these proteins in NHIC subtypes according to IC symptom scores, visual analog scores of bladder pain, maximal bladder capacity, glomerulation grades, and combined maximal bladder capacity and glomerulations after cystoscopic hydrodistention. The expression levels of TRPV1, TRPV4, sigma-1, P38, tryptase, caspase-3, and BAD were significantly increased in the urothelium of IC/BPS patients compared with the expression levels in the controls. TRPV1 was significantly associated with IC symptom severity. However, no significant differences in sensory receptor expression in the IC/BPS bladders with different bladder conditions were detected. Inflammatory and pro-apoptotic protein expression levels in the urothelium were similar among the IC/BPS subgroups. This study concluded that IC/BPS patients with frequency and bladder pain complaints have higher levels of urothelial sensory receptors, and inflammatory and pro-apoptotic proteins. The expression levels of these sensory receptors, inflammatory proteins, and pro-apoptotic proteins are not significantly different among IC/BPS bladders with different conditions.

8-Aminoinosine and 8-Aminohypoxanthine Inhibit Purine Nucleoside Phosphorylase and Exert Diuretic and Natriuretic Activity.

8-Aminoguanine and 8-aminoguanosine (via metabolism to 8-aminoguanine) are endogenous 8-aminopurines that induce diuresis, natriuresis, and glucosuria by inhibiting purine nucleoside phosphorylase (PNPase); moreover, both 8-aminopurines cause antikaliuresis by other mechanisms. Because 8-aminoinosine and 8-aminohypoxanthine are structurally similar to 8-aminoguanosine and 8-aminoguanine, respectively, we sought to define their renal excretory effects. First, we compared the ability of 8-aminoguanine, 8-aminohypoxanthine, and 8-aminoinosine to inhibit recombinant PNPase. These compounds inhibited PNPase with a potency order of 8-aminoguanine > 8-aminohypoxanthine = 8-aminoinosine. Additional studies showed that 8-aminoinosine is a competitive substrate that is metabolized to a competitive PNPase inhibitor, namely 8-aminohypoxanthine. Administration of each 8-aminopurine (33.5 µmol/kg) reduced the guanine-to-guanosine and hypoxanthine-to-inosine ratios in urine, a finding confirming their ability to inhibit PNPase in vivo. All three 8-aminopurines induced diuresis, natriuresis, and glucosuria; however, the glucosuric effects of 8-aminohypoxanthine and 8-aminoinosine were less pronounced than those of 8-aminoguanine. Neither 8-aminohypoxanthine nor 8-aminoinosine altered potassium excretion, whereas 8-aminoguanine caused antikaliuresis. In vivo administration of 8-aminoinosine increased 8-aminohypoxanthine excretion, indicating that 8-aminohypoxanthine mediates, in part, the effects of 8-aminoinosine. Finally, 8-aminohypoxanthine was metabolized to 8-aminoxanthine by xanthine oxidase. Using ultraperformance liquid chromatography-tandem mass spectrometry, we identified 8-aminoinosine as an endogenous 8-aminopurine. In conclusion, 8-aminopurines have useful pharmacological profiles. To induce diuresis, natriuresis, glucosuria, and antikaliuresis, 8-aminoguanine (or its prodrug 8-aminoguanosine) would be preferred. If only diuresis and natriuresis, without marked glucosuria or antikaliuresis, is desired, 8-aminohypoxanthine or 8-aminoinosine might be useful. Finally, here we report the in vivo existence of another pharmacologically active 8-aminopurine, namely 8-aminoinosine. SIGNIFICANCE STATEMENT: Here, we report that a family of 8-aminopurines affects renal excretory function: effects that may be useful for treating multiple diseases including hypertension, heart failure, and chronic kidney disease. For diuresis and natriuresis accompanied by glucosuria and antikaliuresis, 8-aminoguanine (or its prodrug 8-aminoguanosine) would be useful; if only diuresis and natriuresis is called for, 8-aminohypoxanthine or 8-aminoinosine would be useful. Previously, we identified 8-aminoguanine and 8-aminoguanosine as endogenous 8-aminopurines; here, we extend the family of endogenous 8-aminopurines to include 8-aminoinosine.

A uro-protective agent with restorative actions on urethral and striated muscle morphology.

PURPOSE: Aging increases oxidative stress, which can have delirious effects on smooth and striated muscle resulting in bladder dysfunction. Consequently, in women aged over 60 years, urinary incontinence (UI) is a prevalent health problem. Despite the prevalence and consequences, UI continues to be undertreated simply because there are few therapeutic options. METHODS: Here we investigated whether 8-aminoguanine (8-AG), a purine nucleoside phosphorylase (PNPase inhibitor), would restore urethra and external sphincter (EUS) muscle morphology in the aged rat. Aged (> 25 months) female Fischer 344 rats were randomized to oral treatment with 8-AG (6 weeks) or placebo, and the urethra and EUS were evaluated by electron microscopy and protein expression (western immunoblotting). RESULTS: Aging was associated with mitochondrial degeneration in smooth and striated muscle cells as compared to young rats. We also observed a significant increase in biomarkers such as PARP, a downstream activator of oxidative/nitrosative stress. Treatment of aged rats with 8-AG normalized all abnormalities to that of a younger state. CONCLUSIONS: 8-AG, a potent inhibitor of PNPase, reverses age-related lower urinary tract morphological and biochemical changes. Our observations support the concept that 8-AG will reverse age-induced lower urinary tract disorders such as UI. These initial findings could have therapeutic implications for the prevention and treatment of age-related UI.

First voided volume: A novel approach to characterize nocturia.

AIMS: Nocturnal polyuria syndrome (NPS) denotes nocturnal polyuria (NP) in the absence of identifiable contributory factors. The trajectory of nocturnal urine production (NUP; typically expressed as ml/hour) may be useful in delineating between NP patients with versus without NPS, but changes in absolute urine volume, the directly measured substrate for behavioral and pharmacologic interventions targeting nocturnal urine production, have not been well characterized. This study compares the ratio of the first nocturnal voided volume (FNVV) to the nocturnal average voided volume (NAVV) in patients with versus without NPS. METHODS: Secondary analysis of 24-h voiding diaries from male patients greater than or equal to 18 years of age with two or more nocturnal voids and NP using two different criteria for NP: NUP greater than or equal to 90 ml/h and nocturnal polyuria index (NPi) greater than or equal to 0.33. Patients with diabetes insipidus and CPAP-adherent obstructive sleep apnea (OSA) were excluded. Patients were divided into 2 groups: secondary NP (OSA, congestive heart failure, and chronic kidney disease) and NPS (absence of edema, diuretic use, and the aforementioned comorbidities). FNVV was defined as the volume of urine accompanying the first nocturic episode. NAVV was defined as nocturnal urine volume/(number of nocturnal voids + 1). The nocturnal urine trajectory ratio (NUTR) was defined as FNVV/NAVV. RESULTS: At NUP greater than or equal to 90 ml/h, NUTR was significantly greater in patients with (n = 73) versus without (n = 28) NPS (1.10 [0.89-1.33] vs. 0.91 [0.55-1.15], p = .012). At NPi greater than or equal to 0.33, NUTR was likewise significantly greater in patients with (n = 92) versus without (n = 32) NPS (1.09 [0.90-1.33] vs. 0.91 [0.57-1.17], p = .010). CONCLUSIONS: The volume of urine produced in the early hours of sleep is central to identification of NPS in patients with nocturia.

Urothelial signaling.

The urothelium, which lines the inner surface of the renal pelvis, the ureters, and the urinary bladder, not only forms a high-resistance barrier to ion, solute and water flux, and pathogens, but also functions as an integral part of a sensory web which receives, amplifies, and transmits information about its external milieu. Urothelial cells have the ability to sense changes in their extracellular environment, and respond to chemical, mechanical and thermal stimuli by releasing various factors such as ATP, nitric oxide, and acetylcholine. They express a variety of receptors and ion channels, including P2X3 purinergic receptors, nicotinic and muscarinic receptors, and TRP channels, which all have been implicated in urothelial-neuronal interactions, and involved in signals that via components in the underlying lamina propria, such as interstitial cells, can be amplified and conveyed to nerves, detrusor muscle cells, and ultimately the central nervous system. The specialized anatomy of the urothelium and underlying structures, and the possible communication mechanisms from urothelial cells to various cell types within the bladder wall are described. Changes in the urothelium/lamina propria ("mucosa") produced by different bladder disorders are discussed, as well as the mucosa as a target for therapeutic interventions.

Are there relevant animal models to set research priorities in LUTD? ICI-RS 2019.

AIM: To discuss animal models of lower urinary tract disorders (LUTD) and their translational impact. METHODS: Report of discussions based on presented literature-search based reviews relevant for the purpose. RESULTS: Animal models can be used to investigate fundamental biological mechanisms, but also as tools to elucidate aspects of the pathogenesis of disease and to provide early evidence of any safety risk. Several different models may be required to obtain information that can have a translational impact. The term "translational research" covers not only the process of directly transferring knowledge from basic sciences to human trials to produce new drugs, devices, and treatment options for patients (T1 type translation) but also the implementation of early clinical research findings (phases I-III) into practice to improve care for patients (T2 type). Direct transfer of animal data to T2 is rarely possible, and the process often does not continue after the first trials in humans (phase I). It should be emphasized that many preclinical observations do not have (and do not need to have) immediate translational impact. CONCLUSIONS: No single animal model can mimic the complexity of the human disease. Still, animal models can be useful for gaining information on LUT function in humans, for elucidating pathophysiological mechanisms, and for the definition of targets for future drugs to treat LUT disorders.

Should we be revisiting LUT basic science and clinical measurement of LUT sensation to improve patient care? ICI-RS 2019.

AIMS: This article reviews current knowledge of the underpinning mechanisms of how the bladder senses fullness locally and also revisits clinical measurements of lower urinary tract sensation. The former represents cellular sensing during bladder filling whereas the latter describes the sensations leading to conscious perception of bladder fullness. METHODS: The topic was discussed in a "think tank" session at the 2019 International Consultation on Incontinence-Research Symposium in Bristol, UK; summarized in the present review. RESULTS: Recent advances in the basic science of bladder sensing relating to (a) the bladder wall-urothelial cells, sensory nerves, interstitial cells, and smooth muscle cells and (b) putative chemo/mechanosensors in the urethra-paraneurons or "brush cells" are discussed. Validated clinical measurement of lower urinary tract sensation is reviewed in the context of how this could be better harnessed for patient benefit. We discuss the potential of app/tablet/mobile technology based on triggers and distractors to override aberrant local sensing/higher sensation and how these technologies could be utilized in treatment. CONCLUSIONS: We conclude that a better understanding of bladder sensation is essential to inform clinical management of lower urinary tract symptoms.

Associations between nighttime and daytime maximum voided volumes: Relevance for nocturia?

AIM: The relationship between maximum voided volumes (MVV) during the night and day is poorly understood. Such measurements are important because they are often used to indicate functional bladder capacity (FBC), a relevant parameter for nocturia. This study examined the association of such nighttime and daytime measurements in men with nocturia. METHODS: We retrospectively analyzed 356 24-hour voiding diaries showing ≥2 nocturnal voids from 220 men at an outpatient urology clinic. We defined small FBC as MVV ≤ 200 mL. RESULTS: A total of 131 entries demonstrated a nocturnal MVV ≤ 200 mL, of which a majority (98 [74.8%]) also showed a 24-hour MVV ≤ 200 mL (ie, global small FBC), and 33 (25.2%) exceeded the 200 mL threshold during the day (ie, nocturnal-specific small FBC). Correspondingly, among voiding diaries without global small FBC (n = 258), most (225/258 [87.2%]) showed a nocturnal MVV > 200 mL. Data were similar when analyzing only the first complete voiding diary per case, when limiting analyses to those without benign prostatic obstruction, and when limiting analyses to cases with nocturnal polyuria. CONCLUSION: Nocturia may be attributable to nocturnal-specific small FBC or global small FBC. Although the etiology of nocturnal-specific small FBC remains unclear, it was present in a significant minority of patients with small FBC, thus necessitating more directed research. Conversely, diminished nocturnal MVV was nevertheless relatively uncommon in the absence of global small FBC, such that nocturnal-only voiding diaries may provide a rational alternative for follow-up evaluation in patients with nocturia due to global small bladder capacity.

Are oxidative stress and ischemia significant causes of bladder damage leading to lower urinary tract dysfunction? Report from the ICI-RS 2019.

Several studies indicate that pelvic ischemia and oxidative stress may play a significant role in lower urinary tract dysfunction (LUTD), including detrusor overactivity (DO)/overactive bladder (OAB) and detrusor underactivity (DU)/underactive bladder (UAB). The present article addresses proposal 1: "Are oxidative stress and ischemia significant causes of bladder damage leading to LUTD?" from the 2019 International Consultation on Incontinence-Research Society (ICI-RS) meeting. Bladder ischemia in animals and humans is briefly described, along with the proposed progression from ischemia to LUTD. Bladder ischemia is compared with ischemia of other organs, and the ongoing development of pelvic ischemia animal models is discussed. In addition, the distribution of blood within the bladder during filling and voiding and the challenges of quantification of blood flow in vivo are described. Furthermore, oxidative stress, including potential biomarkers and treatments, and challenges regarding antioxidant therapy for the treatment of LUTD are discussed. Finally, seven critical research questions and proposed studies to answer those questions were identified as priorities that would lead to major advances in the understanding and treatment of lower urinary tract symptoms (LUTS)/LUTD associated with pelvic ischemia and oxidative stress.

The role of prostaglandin and E series prostaglandin receptor type 4 receptors in the development of bladder overactivity in a rat model of chemically induced prostatic inflammation.

OBJECTIVES: To evaluate, using a rat model of non-bacterial prostatic inflammation, the prostaglandin production and expression profiles of E-series prostaglandin (EP) receptor subtypes, which are reportedly implicated in the development of overactive bladder, in the bladder mucosa, and to investigate the effect of EP receptor type 4 (EP4) blockade on bladder overactivity after prostatic inflammation. METHODS: Male Sprague-Dawley rats were used. Prostatic inflammation was induced by formalin injection (5%; 50 µL per lobe) into the bilateral ventral lobes of the prostate. At 10 days after induction of prostatic inflammation or vehicle injection, bladder tissues from the deeply anaesthetized rats were harvested and separated into mucosal and detrusor layers. Then, prostaglandin E2 (PGE2) concentrations and protein levels of PGE2 receptors (EP1-4) in the bladder mucosa and detrusor were measured by ELISA and Western blotting, respectively. In separate groups of control and formalin-treated rats, awake cystometry was performed to evaluate the changes in bladder activity after prostatic inflammation. In addition, the effect of intravesical administration of a selective EP4 antagonist (ONO-AE3-208; 30 µm) on bladder activity was evaluated in control rats and rats with prostatic inflammation. RESULTS: PGE2 concentration and protein levels of EP4, but not other EP receptor subtypes, in the bladder mucosa and detrusor layers were significantly increased in formalin-injected rats vs vehicle-injected control rats. In cystometry, rats with prostatic inflammation exhibited a significant decrease in intercontraction intervals (ICIs) compared with control rats. Intravesical application of ONO-AE3-208 (30 µm), but not vehicle application, significantly increased ICIs in rats with prostatic inflammation, whereas ONO-AE3-208 at this concentration did not significantly affect any cystometric values in control rats. CONCLUSIONS: Because intravesical administration of an EP4 antagonist effectively improved bladder overactivity after prostatic inflammation, EP4 activation, along with increased PGE2 production in the bladder mucosa, seems to be an important contributing factor to bladder overactivity induced by prostatic inflammation. Thus, blockade of EP4 in the bladder could be a therapeutic approach to male lower urinary tract symptoms attributable to benign prostatic hyperplasia with prostatic inflammation.

Upregulation of neurotrophins and transforming growth factor-ß expression in the bladder may lead to nerve hyperplasia and fibrosis in patients with severe ketamine-associated cystitis.

AIMS: To investigate the mechanism of bladder nerve hyperplasia and fibrosis in the patients with ketamine-associated cystitis (KC). METHODS: Sixteen patients with severe KC, six patients with mild KC, and five patients with localized invasive bladder cancer served as control patients. Bladder mucosa specimens were taken during the operations, and the specimens were stained for nerve growth factor (NGF) and S-100 to evaluated nerve hyperplasia. The quantitative Western blot analysis was performed for NGF, brain-derived neurotrophic factor (BDNF), growth-associated protein 43 (GAP-43), tropomyosin receptor kinase A and B (TrkA and TrkB), transforming growth factor-ß (TGF-ß), phosphorylated extracellular signal-regulated kinases (p-ERK), protein kinase B (p-Akt), and glycogen synthase kinase 3ß (p-GSK-3ß). RESULTS: The results demonstrated diffuse NGF expression in KC bladder epithelium, lamina propria, and muscle. The GAP-43, NGF, BDNF, TrkA, TGF-ß, p-ERK, P-AKT, and p-GSK-3ß expression in the bladder mucosa specimens of patients with severe KC was significantly higher than in patients with mild KC and control patients. Expression of neurotrophins was significantly correlated with bladder capacity and pain. NGF and BDNF expression were significantly higher in the KC bladder specimens with strongly positive S-100 staining. TGF-ß expression in the bladder specimens was significantly correlated with neurotrophins, p-ERK, P-AKT, and p-GSK-3ß levels. CONCLUSION: Our findings indicate upregulation of neurotrophins, TGF-ß, and activation of the cell proliferation kinases plays an important role in nerve hyperplasia and fibrosis mechanisms in severe KC bladders. The neurotrophins and TGF-ß interact as cause and effect, leading to bladder hypersensitivity and fibrosis in severe KC.

Aging increases the expression of vasopressin receptors in both the kidney and urinary bladder.

AIMS: The goal of this study was to determine whether aging effects the expression of V1a and V2 vasopressin receptors in the urinary bladder mucosa (UBM) and kidney. METHODS: UBM and kidneys were obtained from young (3 months-of-age) and old (25-30 months-of-age) female Fisher 344 rats. Tissue samples were analyzed by western blotting for V1a and V2 receptor expression, and rat plasma levels of vasopressin levels were measured by ELISA. RESULTS: V1a and V2 receptors were detected in both the UBM and kidneys. Aging significantly (P < 0.05) increased the expression of V2 receptors by 2.80 ± 0.52 and 6.52 ± 1.24-fold in the UBM and kidneys, respectively. Aging also increased V1a receptor expression in the kidneys (5.52 ± 1.05 fold; P < 0.05), but not in the UBM. To the best of our knowledge, because this is the first detection of V2 receptors in the mammalian bladder mucosa, we also probed human UBM for V2 receptors and observed high expression in human UBM. Unlike V1a and V2 receptors, aging had only a minor effect on plasma vasopressin levels (8% increase). CONCLUSIONS: V2 receptors are substantially increased in the aging UBM. The role of these receptors in UBM is as yet undefined, but given their presence and action in the kidneys, the possible effect of these receptors in free water regulation should be considered. The large age-related increase in the expression of V2 receptors in both the UBM and kidney may contribute to the effectiveness of desmopressin in age-related nocturia.

Stress-induced autonomic dysregulation of mitochondrial function in the rat urothelium.

AIM: Chronic stress exacerbates the symptoms of most pain disorders including interstitial cystitis/bladder pain syndrome (IC/BPS). Abnormalities in urothelial cells (UTC) occur in this debilitating bladder condition. The sequence of events that might link stress (presumably through increased sympathetic nervous system-SNS activity) to urothelial dysfunction are unknown. Since autonomic dysregulation, mitochondrial dysfunction, and oxidative stress all occur in chronic pain, we investigated whether chronic psychological stress initiated a cascade linking these three dysfunctions. METHODS: Adult female Wistar Kyoto rats were exposed to 10 days of water avoidance stress (WAS). Bladders were then harvested for Western blot and single cell imaging in UTC cultures. RESULTS: UTC from WAS rats exhibited depolarized mitochondria membrane potential (Ψm ∼30% more depolarized compared to control), activated AMPK and altered UT mitochondria bioenergetics. Expression of the fusion protein mitofusion-2 (MFN-2) was upregulated in the mucosa, suggesting mitochondrial structural changes consistent with altered cellular metabolism. Intracellular calcium levels were elevated in cultured WAS UTC, consistent with impaired cellular function. Stimulation of cultured UTC with alpha-adrenergic (α-AR) receptor agonists increased reactive oxidative species (ROS) production, suggesting a direct action of SNS activity on UTC. Treatment of rats with guanethidine to block SNS activity prevented most of WAS-induced changes. CONCLUSIONS: Chronic stress results in persistent sympathetically mediated effects that alter UTC mitochondrial function. This may impact the urothelial barrier and signaling, which contributes to bladder dysfunction and pain. This is the first demonstration, to our knowledge, of a potential autonomic mechanism directly linking stress to mitochondrial dysfunction.

Acute spinal cord injury is associated with mitochondrial dysfunction in mouse urothelium.

AIM: To characterize the effects of acute spinal cord injury (SCI) on mitochondrial morphology and function in bladder urothelium and to test the therapeutic efficacy of early treatment with the mitochondrially targeted antioxidant, MitoTempo. METHODS: We used a mouse model of acute SCI by spinal cord transection between the T8-T9 vertebrae with or without MitoTempo delivery at the time of injury followed by tissue processing at 3 days after SCI. Control, SCI, and SCI-MitoTempo-treated mice were compared in all experimental conditions. Assessments included analysis of markers of mitochondrial health including accumulation of reactive oxygen species (ROS), morphological changes in the ultrastructure of mitochondria by transmission electron microscopy, and Western blot analysis to quantify protein levels of markers for autophagy and altered mitochondrial dynamics. RESULTS: SCI resulted in an increase in oxidative stress markers and ROS production, confirming mitochondrial dysfunction. Mitochondria from SCI mice developed large electron-dense inclusions and these aberrant mitochondria accumulated throughout the cytoplasm suggesting an inability to clear dysfunctional mitochondria by mitophagy. SCI mice also exhibited elevated levels of dynamin-related protein 1 (DRP1), consistent with a disruption of mitochondrial dynamics. Remarkably, treatment with MitoTempo reversed many of the SCI-induced abnormalities that we observed. CONCLUSIONS: Acute SCI negatively and severely affects mitochondrial health of bladder urothelium. Early treatment of SCI with MitoTempo may be a viable therapeutic agent to mitigate these deleterious effects.

Pathophysiology of interstitial cystitis.

Interstitial cystitis/bladder pain syndrome is a chronic pain syndrome whose causes remains elusive with no generally accepted treatment. A hallmark of functional pain syndromes such as interstitial cystitis/bladder pain syndrome is pain in the absence of demonstrable pathology of the viscera or associated nerves. Patients with chronic pain experience a greater impairment in quality of life than healthy controls. In addition, interstitial cystitis/bladder pain syndrome symptoms can frequently overlap with other conditions including irritable bowel syndrome, fibromyalgia, chronic fatigue syndrome, anxiety disorders, and a number of other syndromes not directly related to the urinary bladder. Because of the complex pathophysiology, a number of animal models have been studied over the years to better understand mechanisms underlying patient symptoms. These models can include: bladder centric, complex mechanisms and psychological and physical stress models. Such animal models can aid in the investigation of aspects of interstitial cystitis/bladder pain syndrome that cannot be pursued in humans as well as to develop and test potential therapies. In addition, the search for urinary factors that may be a cause of interstitial cystitis/bladder pain syndrome has resulted in the discovery of a number of potential targets that could serve as predictive biomarkers which can aid in early diagnosis and treatment of this chronic disorder.

Relaxin-2 therapy reverses radiation-induced fibrosis and restores bladder function in mice.

AIM: To determine the efficacy of human relaxin-2 (hRLX2) in reversing radiation-induced bladder fibrosis and lower urinary tract dysfunction (LUTD). Radiation cystitis is a consequence of radiotherapy for pelvic malignancies. Acutely, irradiation leads to reactive oxygen/nitrogen species in urothelial cells, apoptosis, barrier disruption, and inflammation. Chronically, this results in collagen deposition, bladder fibrosis, and attenuated storage and voiding functions. In severe cases, cystectomies are performed as current therapies do not reverse fibrosis. METHODS: We developed a mouse model for selective bladder irradiation (10 Gray; 1 Gy = 100 rads) resulting in chronic fibrosis within 6 weeks, with decreased bladder compliance, contractility, and overflow incontinence. Seven weeks post-irradiation, female C57Bl/6 mice were continuously infused with hRLX2 (400 µg/kg/day/14 days) or vehicle (saline) via subcutaneous osmotic pumps. Mice were evaluated in vivo using urine spot analysis, cystometrograms and external urethral sphincter electromyograms; and in vitro using length-tension measurements, Western blots, histology, and immunohistochemistry. RESULTS: hRLX2 reversed fibrosis, decreased collagen content, improved bladder wall architecture, and increased bladder compliance, detrusor smooth muscle Cav1.2 expression and detrusor contractility in mice with chronic radiation cystitis. hRLX2 treatment outcomes were likely caused by the activation of RXFP1/2 receptors which are expressed on the detrusor. CONCLUSION: hRLX2 may be a new therapeutic option for rescuing bladders with chronic radiation cystitis.

Targeting p75 neurotrophin receptors ameliorates spinal cord injury-induced detrusor sphincter dyssynergia in mice.

AIMS: To determine the role of p75 neurotrophin receptor (p75NTR ) and the therapeutic effect of the selective small molecule p75NTR modulator, LM11A-31, in spinal cord injury (SCI) induced lower urinary tract dysfunction (LTUD) using a mouse model. METHODS: Adult female T8 -T9 transected mice were gavaged daily with LM11A-31 (100 mg/kg) for up to 6 weeks, starting 1 day before, or 7 days following injury. Mice were evaluated in vivo using urine spot analysis, cystometrograms (CMGs), and external urethral sphincter (EUS) electromyograms (EMGs); and in vitro using histology, immunohistochemistry, and Western blot. RESULTS: Our studies confirm highest expression of p75NTRs in the detrusor layer of the mouse bladder and lamina II region of the dorsal horn of the lumbar-sacral (L6 -S1 ) spinal cord which significantly decreased following SCI. LM11A-31 prevented or ameliorated the detrusor sphincter dyssynergia (DSD) and detrusor overactivity (DO) in SCI mice, significantly improving bladder compliance. Furthermore, LM11A-31 treatment blocked the SCI-related urothelial damage and bladder wall remodeling. CONCLUSION: Drugs targeting p75NTRs can moderate DSD and DO in SCI mice, may identify pathophysiological mechanisms, and have therapeutic potential in SCI patients.

Urothelial proliferation and regeneration after spinal cord injury.

The basal, intermediate, and superficial cell layers of the urothelium undergo rapid and complete recovery following acute injury; however, the effects of chronic injury on urothelial regeneration have not been well defined. To address this discrepancy, we employed a mouse model to explore urothelial changes in response to spinal cord injury (SCI), a condition characterized by life-long bladder dysfunction. One day post SCI there was a focal loss of umbrella cells, which are large cells that populate the superficial cell layer and normally express uroplakins (UPKs) and KRT20, but not KRT5, KRT14, or TP63. In response to SCI, regions of urothelium devoid of umbrella cells were replaced with small superficial cells that lacked KRT20 expression and appeared to be derived in part from the underlying intermediate cell layer, including cells positive for KRT5 and TP63. We also observed KRT14-positive basal cells that extended thin cytoplasmic extensions, which terminated in the bladder lumen. Both KRT14-positive and KRT14-negative urothelial cells proliferated 1 day post SCI, and by 7 days, cells in the underlying lamina propria, detrusor, and adventitia were also dividing. At 28 days post SCI, the urothelium appeared morphologically patent, and the number of proliferative cells decreased to baseline levels; however, patches of small superficial cells were detected that coexpressed UPKs, KRT5, KRT14, and TP63, but failed to express KRT20. Thus, unlike the rapid and complete restoration of the urothelium that occurs in response to acute injuries, regions of incompletely differentiated urothelium were observed even 28 days post SCI.