Histamine induces peripheral and central hypersensitivity to bladder distension via the histamine H1 receptor and TRPV1

Characterization of human iPSC-derived sensory neurons and their functional assessment using multi electrode array

Sensory neurons are afferent neurons in sensory systems that convert stimuli and transmit information to the central nervous system as electrical signals. Primary afferent neurons that are affected by non-noxious and noxious stimuli are present in the dorsal root ganglia (DRG), and the DRG sensory neurons are used as an in vitro model of the nociceptive response. However, DRG derived from mouse or rat give a low yield of neurons, and they are difficult to culture. To help alleviate this problem, we characterized human induced pluripotent stem cell (hiPSC) derived sensory neurons. They can solve the problems of interspecies differences and supply stability. We investigated expressions of sensory neuron related proteins and genes, and drug responses by Multi-Electrode Array (MEA) to analyze the properties and functions of sensory neurons. They expressed nociceptor, mechanoreceptor and proprioceptor related genes and proteins. They constitute a heterogeneous population of their subclasses. We confirmed that they could respond to both noxious and non-noxious stimuli. We showed that histamine inhibitors reduced histamine-induced neuronal excitability. Furthermore, incubation with a ProTx-II and Nav1.7 inhibitor reduced the spontaneous neural activity in hiPSC-derived sensory neurons. Their responsiveness was different from each drug. We have demonstrated that hiPSC-derived sensory neurons combined with MEA are good candidates for drug discovery studies where DRG in vitro modeling is necessary.

Recurrent infections drive persistent bladder dysfunction and pain via sensory nerve sprouting and mast cell activity

Urinary tract infections (UTIs) account for almost 25% of infections in women. Many are recurrent (rUTI), with patients frequently experiencing chronic pelvic pain and urinary frequency despite clearance of bacteriuria after antibiotics. To elucidate the basis for these bacteria-independent bladder symptoms, we examined the bladders of patients with rUTI. We noticed a notable increase in neuropeptide content in the lamina propria and indications of enhanced nociceptive activity. In mice subjected to rUTI, we observed sensory nerve sprouting that was associated with nerve growth factor (NGF) produced by recruited monocytes and tissue-resident mast cells. Treatment of rUTI mice with an NGF-neutralizing antibody prevented sprouting and alleviated pelvic sensitivity, whereas instillation of native NGF into naïve mice bladders mimicked nerve sprouting and pain behavior. Nerve activation, pain, and urinary frequency were each linked to the presence of proximal mast cells, because mast cell deficiency or treatment with antagonists against receptors of several direct or indirect mast cell products was each effective therapeutically. Thus, our findings suggest that NGF-driven sensory sprouting in the bladder coupled with chronic mast cell activation represents an underlying mechanism driving bacteria-independent pain and voiding defects experienced by patients with rUTI.

Latest insights into the pathophysiology of bladder pain syndrome/interstitial cystitis

PURPOSE OF REVIEW

Bladder pain syndrome/interstitial cystitis (BPS/IC) is a common medical problem in both sexes affecting people of all ages. Patients might report overactive bladder symptoms with additional bladder pain at maximum bladder filling, during and after micturition. This review aims to highlight pathophysiological mechanisms associated with this disease.

RECENT FINDINGS

Latest literature exposes different pathophysiological mechanisms such as impaired urothelial barrier function, alteration of urothelial factors and cytokines, chronic inflammation, vascular lesions, neurogenic inflammation and processes in the central nervous system leading to central sensitization. According to the involved mechanisms, BPS/IC may be arranged in clusters according to the clinical phenotype thus helping in clinical decision-making and treatment. Moreover, patients with BPS/IC suffer from other comorbidities such as fibromyalgia, irritable bowel syndrome, chronic pain and functional syndromes and psychosomatic diseases making the management challenging for medical professionals.

SUMMARY

Bladder pain syndrome/interstitial cystitis is a complex heterogeneous medical condition involving different pathomechanisms leading to bladder pain and dysfunction, consequently, impairing quality-of-life in affected individuals. However, these mechanisms are still not fully understood, so that patient treatments often remain unsatisfactory. For this reason, continuing research is important to understand the underlying pathomechanisms to discover biomarkers and treatment targets eventually improving diagnostic and therapeutic measures of BPS/IC.

Mechanisms of oxidative stress in interstitial cystitis/bladder pain syndrome

Interstitial cystitis/bladder pain syndrome (IC/BPS) is characterized by bladder and/or pelvic pain, increased urinary urgency and frequency and nocturia. The pathophysiology of IC/BPS is poorly understood, and theories include chronic inflammation, autoimmune dysregulation, bacterial cystitis, urothelial dysfunction, deficiency of the glycosaminoglycan (GAG) barrier and urine cytotoxicity. Multiple treatment options exist, including behavioural interventions, oral medications, intravesical instillations and procedures such as hydrodistension; however, many clinical trials fail, and patients experience an unsatisfactory treatment response, likely owing to IC/BPS phenotype heterogeneity and the use of non-targeted interventions. Oxidative stress is implicated in the pathogenesis of IC/BPS as reactive oxygen species impair bladder function via their involvement in multiple molecular mechanisms. Kinase signalling pathways, nociceptive receptors, mast-cell activation, urothelial dysregulation and circadian rhythm disturbance have all been linked to reactive oxygen species and IC/BPS. However, further research is necessary to fully uncover the role of oxidative stress in the pathways driving IC/BPS pathogenesis. The development of new models in which these pathways can be manipulated will aid this research and enable further investigation of promising therapeutic targets.

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.

Comparative localization of colorectal sensory afferent central projections in the mouse spinal cord dorsal horn and caudal medulla dorsal vagal complex

The distal colon and rectum (colorectum) are innervated by spinal and vagal afferent pathways. The central circuits into which vagal and spinal afferents relay colorectal nociceptive information remain to be comparatively assessed. To address this, regional colorectal retrograde tracing and colorectal distension (CRD)-evoked neuronal activation were used to compare the circuits within the dorsal vagal complex (DVC) and dorsal horn (thoracolumbar [TL] and lumbosacral [LS] spinal levels) into which vagal and spinal colorectal afferents project. Vagal afferent projections were observed in the nucleus tractus solitarius (NTS), area postrema (AP), and dorsal motor nucleus of the vagus (DMV), labeled from the rostral colorectum. In the NTS, projections were opposed to catecholamine and pontine parabrachial nuclei (PbN)-projecting neurons. Spinal afferent projections were labeled from rostral through to caudal aspects of the colorectum. In the dorsal horn, the number of neurons activated by CRD was linked to pressure intensity, unlike in the DVC. In the NTS, 13% ± 0.6% of CRD-activated neurons projected to the PbN. In the dorsal horn, at the TL spinal level, afferent input was associated with PbN-projecting neurons in lamina I (LI), with 63% ± 3.15% of CRD-activated neurons in LI projecting to the PbN. On the other hand, at the LS spinal level, only 18% ± 0.6% of CRD-activated neurons in LI projected to the PbN. The collective data identify differences in the central neuroanatomy that support the disparate roles of vagal and spinal afferent signaling in the facilitation and modulation of colorectal nociceptive responses.

BCG induced lower urinary tract symptoms during treatment for NMIBC-Mechanisms and management strategies

Non-muscle invasive bladder cancer (NMIBC) accounts for ~70-75% of total bladder cancer tumors and requires effective early intervention to avert progression. The cornerstone of high-risk NMIBC treatment involves trans-urethral resection of the tumor followed by intravesical Bacillus Calmette-Guerin (BCG) immunotherapy. However, BCG therapy is commonly accompanied by significant lower urinary tract symptoms (LUTS) including urinary urgency, urinary frequency, dysuria, and pelvic pain which can undermine treatment adherence and clinical outcomes. Despite this burden, the mechanisms underlying the development of BCG-induced LUTS have yet to be characterized. This review provides a unique perspective on the mechanisms thought to be responsible for the development of BCG-induced LUTS by focussing on the sensory nerves responsible for bladder sensory transduction. This review focuses on how the physiological response to BCG, including inflammation, urothelial permeability, and direct interactions between BCG and sensory nerves could drive bladder afferent sensitization leading to the development of LUTS. Additionally, this review provides an up-to-date summary of the latest clinical data exploring interventions to relieve BCG-induced LUTS, including therapeutic targeting of bladder contractions, inflammation, increased bladder permeability, and direct inhibition of bladder sensory signaling. Addressing the clinical burden of BCG-induced LUTS holds significant potential to enhance patient quality of life, treatment compliance, and overall outcomes in NMIBC management. However, the lack of knowledge on the pathophysiological mechanisms that drive BCG-induced LUTS has limited the development of novel and efficacious therapeutic options. Further research is urgently required to unravel the mechanisms that drive BCG-induced LUTS.

Uroprotective and pain-relieving effect of dietary supplementation with micronized palmitoyl-glucosamine and hesperidin in a chronic model of cyclophosphamide-induced cystitis

Introduction

Feline idiopathic cystitis is a common, chronic-relapsing disorder of the lower urinary tract. In addition to environmental modification/enrichment, long-term and safe treatment targeting specific pathophysiological changes may be of help. In this context, effective dietary interventions hold clinical promise. Palmitoyl-glucosamine (PGA) and hesperidin (HSP) are safe and authorized feed ingredients for animal nutrition under European regulations.

Methods

The current study aimed to investigate whether a 3:1 mixture of micronized PGA and HSP could represent a novel mechanism-oriented approach to chronic cystitis management. A newly validated rat model of cyclophosphamide (CYP)-induced chronic cystitis was used (40 mg/kg, three intraperitoneal injections every 3rd day). Animals were randomized to orally receive either vehicle or PGA-HSP at a low (72 + 24 mg/kg) or high (doubled) dose for 13 days, starting 3 days before the chronic CYP protocol, with mesna (2-mercaptoethane-sulfonate) being used as a reference drug.

Results

Higher PGA-HSP dose was effective at relieving chronic visceral pain, as measured by mechanical allodynia test (von Frey test). The severity of cystitis was also significantly improved, as shown by the reduced sonographic thickening of the bladder wall, as well as the decrease in edema, bleeding and bladder to body weight ratio compared to the vehicle treated group. A significant decrease of MPO activity, MDA level and fibrosis at Masson's trichrome staining was also observed in animals administered PGA-HSP in comparison to vehicle treated ones. The CYP-induced increase in bladder mRNA expression of pro-inflammatory cytokines was also significantly counteracted by the study mixture. Moreover, CYP-induced bladder mast cell accumulation and releasability were significantly decreased by PGA-HSP (even at the low dose), as determined by metachromatic staining, chymase and tryptase immunostaining as well as enzyme-linked immunosorbent assay for histamine and 5-hydoxytriptamine.

Discussion

PGA-HSP is able to block CYP-induced decrease of tight junction proteins, claudin-1 and occludin, thus preserving the urothelial bladder function. Finally, neuroinflammatory changes were investigated, showing that dietary supplementation with PGA-HSP prevented the activation of neurons and non-neuronal cells (i.e., microglia, astrocytes and mast cells) at the spinal level, and counteracted CYP-induced increase of spinal mRNA encoding for pro-inflammatory cytokines. Altogether, the present findings confirm the uroprotective and pain-relieving effect of PGA-HSP and pave the way to potential and relevant clinical applications of the study supplement in feline idiopathic cystitis.

Lower Urinary Tract Symptoms (LUTS) as a New Clinical Presentation of Histamine Intolerance: A Prevalence Study of Genetic Diamine Oxidase Deficiency

Lower urinary tract symptoms (LUTS) are highly prevalent, and their treatment is mainly focused on the control of symptoms. Histamine intolerance (HIT) has been related to a variety of systemic symptoms. DAO deficiency has been identified as a significant factor contributing to histamine intolerance (HIT). Preclinical evidence indicates the involvement of histamine in the lower urinary tract. This study aimed to assess the prevalence of diamine oxidase deficiency (DAO) in a prospective cohort of 100 patients with at least moderate LUTS. A genetic study of four single nucleotide polymorphisms (SNPs) (c.-691G>T, c.47C>T, c.995C>T, and c.1990C>G) was performed. HIT was found in 85.9% of patients. The prevalence of at least one minor allele in the SNPs analyzed was 88%, without gender differences. Storage symptoms were more intense in the presence of HIT as well as asthenia and neurological and musculoskeletal symptoms. The presence of minor alleles of the AOC1 gene was associated with a higher intensity of symptoms. Minor alleles from c.-691G>T and c.47C>T SNPs were also associated with a greater severity of obstructive symptoms. Thirty-one percent of patients presented the four SNPS with at least one associated minor allele. The relationship between HIT and LUTS in a mixed population of men and women found in this study supports further investigations to define the pathophysiology of histamine in LUTS.

Animal models of interstitial cystitis/bladder pain syndrome

Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS) is a chronic disorder characterized by pelvic and/or bladder pain, along with lower urinary tract symptoms that have a significant impact on an individual's quality of life. The diverse range of symptoms and underlying causes in IC/BPS patients pose a significant challenge for effective disease management and the development of new and effective treatments. To facilitate the development of innovative therapies for IC/BPS, numerous preclinical animal models have been developed, each focusing on distinct pathophysiological components such as localized urothelial permeability or inflammation, psychological stress, autoimmunity, and central sensitization. However, since the precise etiopathophysiology of IC/BPS remains undefined, these animal models have primarily aimed to replicate the key clinical symptoms of bladder hypersensitivity and pain to enhance the translatability of potential therapeutics. Several animal models have now been characterized to mimic the major symptoms of IC/BPS, and significant progress has been made in refining these models to induce chronic symptomatology that more closely resembles the IC/BPS phenotype. Nevertheless, it's important to note that no single model can fully replicate all aspects of the human disease. When selecting an appropriate model for preclinical therapeutic evaluation, consideration must be given to the specific pathology believed to underlie the development of IC/BPS symptoms in a particular patient group, as well as the type and severity of the model, its duration, and the proposed intervention's mechanism of action. Therefore, it is likely that different models will continue to be necessary for preclinical drug development, depending on the unique etiology of IC/BPS being investigated.

Evaluation of the association between asthma and non-neurogenic urinary incontinence in children; a case-control study

BACKGROUND

Asthma is the most common chronic disease in children. Asthma can lead to sleep disorders and psychiatric issues, which are often accompanied by urinary incontinence in children. Furthermore, several studies have shown a relationship between allergic diseases and urinary incontinence. This study aims to examine the association between asthma and non-neurogenic urinary incontinence.

MATERIALS AND METHODS

This case-control study included 314 children over three years old referred to Amir Kabir Hospital; 157 with asthma and 157 without asthma. After explaining each urinary disorder in accordace with the International Children's Continence Society's definitions, parents and children were asked about their presence. The disorders included monosymptomatic nocturnal enuresis(MNE), nonmonosymptomatic nocturnal enuresis (NMNE), vaginal reflux (VR), pollakiuria, infrequent voiding, giggle incontinence (GI), and overactive bladder (OAB). The analysis was performed using Stata 16.

RESULTS

The average age of the children was 8.19 ± 3.15 years. Patients with asthma (p = 0.0001) and GI (p = 0.027) had a considerably lower average age than patients without these disorders. Asthma and urinary incontinence, including NMNE, Infrequent voiding, and OAB, were significantly correlated (p = 0.017, 0.013, and 0.0001, respectively). Moreover, the association between MNE and asthma was significant in males (p = 0.047).

CONCLUSION

Due to the relationship between asthma and urinary incontinence, children with asthma must be evaluated for the presence of urinary disorders and, if present, receive the proper treatment in order to improve their quality of life.

Pathophysiological Mechanisms Involved in Overactive Bladder/Detrusor Overactivity

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.

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.

The T-type calcium channel Ca V 3.2 regulates bladder afferent responses to mechanical stimuli

ABSTRACT

The bladder wall is innervated by a complex network of afferent nerves that detect bladder stretch during filling. Sensory signals, generated in response to distension, are relayed to the spinal cord and brain to evoke physiological and painful sensations and regulate urine storage and voiding. Hyperexcitability of these sensory pathways is a key component in the development of chronic bladder hypersensitivity disorders including interstitial cystitis/bladder pain syndrome and overactive bladder syndrome. Despite this, the full array of ion channels that regulate bladder afferent responses to mechanical stimuli have yet to be determined. Here, we investigated the role of low-voltage-activated T-type calcium (Ca V 3) channels in regulating bladder afferent responses to distension. Using single-cell reverse-transcription polymerase chain reaction and immunofluorescence, we revealed ubiquitous expression of Ca V 3.2, but not Ca V 3.1 or Ca V 3.3, in individual bladder-innervating dorsal root ganglia neurons. Pharmacological inhibition of Ca V 3.2 with TTA-A2 and ABT-639, selective blockers of T-type calcium channels, dose-dependently attenuated ex-vivo bladder afferent responses to distension in the absence of changes to muscle compliance. Further evaluation revealed that Ca V 3.2 blockers significantly inhibited both low- and high-threshold afferents, decreasing peak responses to distension, and delayed activation thresholds, thereby attenuating bladder afferent responses to both physiological and noxious distension. Nocifensive visceromotor responses to noxious bladder distension in vivo were also significantly reduced by inhibition of Ca V 3 with TTA-A2. Together, these data provide evidence of a major role for Ca V 3.2 in regulating bladder afferent responses to bladder distension and nociceptive signalling to the spinal cord.

A syngeneic inoculation mouse model of endometriosis that develops multiple comorbid visceral and cutaneous pain like behaviours

ABSTRACT

Endometriosis is a chronic and debilitating condition, commonly characterised by chronic pelvic pain (CPP) and infertility. Chronic pelvic pain can be experienced across multiple pelvic organs, with comorbidities commonly effecting the bowel, bladder, and vagina. Despite research efforts into endometriosis pathophysiology, little is known about how endometriosis induces CPP, and as such, therapeutic interventions are lacking. The aim of this study was to characterise a syngeneic mouse model of endometriosis that mimics naturally occurring retrograde menstruation, thought to precede endometriosis development in patients, and determine whether these mice exhibit signs of CPP and altered behaviour. We characterised the development of endometriosis over 10 weeks following uterine tissue inoculation, measured in vivo and ex vivo hypersensitivity to mechanical stimuli across multiple visceral organs, and assessed alterations in animal spontaneous behaviour. We confirmed that inoculated uterine horn tissue formed into endometriosis lesions throughout the peritoneal cavity, with significant growth by 8 to 10 weeks post inoculation. Additionally, we found that mice with fully developed endometriosis displayed hypersensitivity evoked by (1) vaginal distension, (2) colorectal distension, (3) bladder distension, and (4) cutaneous thermal stimulation, compared to their sham counterparts. Moreover, endometriosis mice displayed alterations in spontaneous behaviour indicative of (5) altered bladder function and (6) anxiety. This model creates a foundation for mechanistical studies into the diffuse CPP associated with endometriosis and the development of targeted therapeutic interventions to improve the quality of life of women with endometriosis.

Urinary Tract Infection in Overactive Bladder: An Update on Pathophysiological Mechanisms

Overactive bladder (OAB) is a clinical syndrome defined by urinary urgency, increased daytime urinary frequency and/or nocturia, with or without urinary incontinence, that affects approximately 11% of the western population. OAB is accepted as an idiopathic disorder, and is charactersied clinically in the absence of other organic diseases, including urinary tract infection. Despite this, a growing body of research provides evidence that a significant proportion of OAB patients have active bladder infection. This review discusses the key findings of recent laboratory and clinical studies, providing insight into the relationship between urinary tract infection, bladder inflammation, and the pathophysiology of OAB. We summarise an array of clinical studies that find OAB patients are significantly more likely than control patients to have pathogenic bacteria in their urine and increased bladder inflammation. This review reveals the complex nature of OAB, and highlights key laboratory studies that have begun to unravel how urinary tract infection and bladder inflammation can induce urinary urgency and urinary frequency. The evidence presented in this review supports the concept that urinary tract infection may be an underappreciated contributor to the pathophysiology of some OAB patients.

Potential Neuroimmune Interaction in Chronic Pain: A Review on Immune Cells in Peripheral and Central Sensitization

Chronic pain is a long-standing unpleasant sensory and emotional feeling that has a tremendous impact on the physiological functions of the body, manifesting itself as a dysfunction of the nervous system, which can occur with peripheral and central sensitization. Many recent studies have shown that a variety of common immune cells in the immune system are involved in chronic pain by acting on the peripheral or central nervous system, especially in the autoimmune diseases. This article reviews the mechanisms of regulation of the sensory nervous system by neutrophils, macrophages, mast cells, B cells, T cells, and central glial cells. In addition, we discuss in more detail the influence of each immune cell on the initiation, maintenance, and resolution of chronic pain. Neutrophils, macrophages, and mast cells as intrinsic immune cells can induce the transition from acute to chronic pain and its maintenance; B cells and T cells as adaptive immune cells are mainly involved in the initiation of chronic pain, and T cells also contribute to the resolution of it; the role of glial cells in the nervous system can be extended to the beginning and end of chronic pain. This article aims to promote the understanding of the neuroimmune mechanisms of chronic pain, and to provide new therapeutic ideas and strategies for the control of chronic pain at the immune cellular level.

TGR5 agonists induce peripheral and central hypersensitivity to bladder distension

The mechanisms underlying chronic bladder conditions such as interstitial cystitis/bladder pain syndrome (IC/BPS) and overactive bladder syndrome (OAB) are incompletely understood. However, targeting specific receptors mediating neuronal sensitivity to specific stimuli is an emerging treatment strategy. Recently, irritant-sensing receptors including the bile acid receptor TGR5, have been identified within the viscera and are thought to play a key role in neuronal hypersensitivity. Here, in mice, we identify mRNA expression of TGR5 (Gpbar1) in all layers of the bladder as well as in the lumbosacral dorsal root ganglia (DRG) and in isolated bladder-innervating DRG neurons. In bladder-innervating DRG neurons Gpbar1 mRNA was 100% co-expressed with Trpv1 and 30% co-expressed with Trpa1. In vitro live-cell calcium imaging of bladder-innervating DRG neurons showed direct activation of a sub-population of bladder-innervating DRG neurons with the synthetic TGR5 agonist CCDC, which was diminished in Trpv1-/- but not Trpa1-/- DRG neurons. CCDC also activated a small percentage of non-neuronal cells. Using an ex vivo mouse bladder afferent recording preparation we show intravesical application of endogenous (5α-pregnan-3β-ol-20-one sulphate, Pg5α) and synthetic (CCDC) TGR5 agonists enhanced afferent mechanosensitivity to bladder distension. Correspondingly, in vivo intravesical administration of CCDC increased the number of spinal dorsal horn neurons that were activated by bladder distension. The enhanced mechanosensitivity induced by CCDC ex vivo and in vivo was absent using Gpbar1-/- mice. Together, these results indicate a role for the TGR5 receptor in mediating bladder afferent hypersensitivity to distension and thus may be important to the symptoms associated with IC/BPS and OAB.

Partial recovery of voiding function in female mice following repeated psychological stress exposure

Psychological stress causes bladder dysfunction in humans and in rodent models, with increased urinary frequency and altered contractile responses evident following repeated environmental stress exposure. However, whether these changes persist after removal of the stressor is unknown, and the aim of this study was to determine if stress-induced changes in voiding behaviour and bladder function recover following removal of the stressor. Adult female mice were allocated to three groups: Unstressed, Stressed or Stressed + Recovery. Animals in the stressed groups were exposed to water avoidance stress for 1h/day for 10-days, with unstressed animals age-matched and housed under normal conditions. For recovery studies, animals were housed without stress exposure for an additional 10-days. Voiding behaviour was assessed periodically and animals sacrificed on day 10 (Unstressed and Stressed) or day 20 (Unstressed and Stressed + Recovery). Isolated whole bladder studies were used to assess compliance, urothelial mediator release and contractile responses. Exposure to stress increased plasma corticosterone levels almost three-fold (P<0.05) but this returned to baseline during the recovery period. Contractile responses of the bladder to carbachol and KCl were also increased following stress, and again fully recovered after a 10-day stress-free period. In contrast, stress increased urinary frequency four-fold (P<0.001), but this did not return fully to baseline during the recovery period. Bladder compliance was unchanged by stress; however, it was increased in the stressed + recovery group (P<0.05). Thus, following a stress-free period there is partial recovery of voiding behaviour, with an increase in bladder compliance possibly contributing to the compensatory mechanisms.

Histamine Sensitization of the Voltage-Gated Sodium Channel Nav1.7 Contributes to Histaminergic Itch in Mice

Itch, a common clinical symptom of many skin diseases, severely impairs the life quality of patients. Nav1.7, a subtype of voltage-gated sodium channels mainly expressed in primary sensory neurons, is responsible for the amplification of threshold currents that trigger action potential (AP) generation. Gain-of-function mutation of Nav1.7 leads to paroxysmal itch, while pharmacological inhibition of Nav1.7 alleviates histamine-dependent itch. However, the crosstalk between histamine and Nav1.7 that leads to itch is unclear. In the present study, we demonstrated that in the dorsal root ganglion (DRG) neurons from histamine-dependent itch model mice induced by compound 48/80, tetrodotoxin-sensitive (TTX-S) but not TTX-resistant Na⁺ currents were activated at more hyperpolarized membrane potentials compared to those on DRG neurons from vehicle-treated mice. Meanwhile, bath application of histamine shifted the activation voltages of TTX-S Na⁺ currents to the hyperpolarized direction, increased the AP frequency, and reduced the current threshold required to elicit APs. Further mechanistic studies demonstrated that selective activation of H1 but not H2 and H4 receptors mimicked histamine effect on TTX-S Na⁺ channels in DRG neurons. The protein kinase C (PKC) inhibitor GO 8963, but not the PKA inhibitor H89, normalized histamine-sensitized TTX-S Na⁺ channels. We also demonstrated that histamine shifted the activation voltages of Na⁺ currents to the hyperpolarized direction in Chinese hamster ovary (CHO) cells expressing Nav1.7. Importantly, selective inhibition of Nav1.7 by PF-05089771 significantly relieved the scratching frequency in a histamine-dependent itch model induced by compound 48/80. Taken together, these data suggest that activation of H1 receptors by histamine sensitizes Nav1.7 channels through the PKC pathway in DRG neurons that contributes to histamine-dependent itch.

Histamine receptors rapidly desensitize without altering nerve-evoked contractions in murine urinary bladder smooth muscle

Histamine has been implicated in urinary bladder dysfunction as an inflammatory mediator driving sensory nerve hypersensitivity. However, the direct influence of histamine on smooth muscle has not been thoroughly investigated. We hypothesized that histamine directly contracts urinary bladder smooth muscle (UBSM) independent of effects on nerves. Single cell quantitative RT-PCR determined that only histamine H1 and H2 receptors were expressed on UBSM cells. In isolated tissue bath experiments, histamine (200 µM) caused a highly variable and rapidly desensitizing contraction that was completely abolished by the H1 receptor antagonist fexofenadine (5 µM) and the Gq/11 inhibitor YM254890 (1 µM). Neither the muscarinic receptor antagonist atropine (1 µM), the Na+ channel blocker tetrodotoxin (1 µM), nor the transient receptor potential vanilloid type 1 antagonist capsazepine (10 µM) altered responses to histamine, suggesting that nerve activation was not involved. UBSM desensitization to histamine was not due to receptor internalization, as neither the cholesterol-depleting agent methyl-β-cyclodextrin (10 mM), the dynamin-mediated endocytosis inhibitor dynasore (100 µM), nor the clathrin-mediated endocytosis inhibitor pitstop2 (15 µM) augmented or prolonged histamine contractions. Buffer from desensitized tissues still contracted histamine-naïve tissues, revealing that histamine was not metabolized. Prolonged exposure to histamine also had no effect on contractions due to electrical field stimulation, suggesting that both efferent nerve and UBSM excitability were unchanged. Together, these data suggest that histamine, although able to transiently contract UBSM, does not have a lasting effect on UBSM excitability or responses to efferent nerve input. Thus, any acute effects of histamine directly on UBSM contractility are unlikely to alter urinary bladder function.NEW & NOTEWORTHY Histamine is commonly associated with inflammatory bladder pathologies. We sought to investigate the role of histamine on urinary bladder contractility. Histamine contracts the bladder, but this response is highly variable and desensitizes completely in minutes. This desensitization is not due to internalization of the receptor or metabolism of histamine. Because nerve-evoked contractions are also not increased in the presence of histamine, our findings suggest that histamine is not directly acting to change contractility.

TRPM3 Is Expressed in Afferent Bladder Neurons and Is Upregulated during Bladder Inflammation

The cation channel TRPM3 is activated by heat and the neurosteroid pregnenolone sulfate. TRPM3 is expressed on sensory neurons innervating the skin, where together with TRPV1 and TRPA1, it functions as one of three redundant sensors of acute heat. Moreover, functional upregulation of TRPM3 during inflammation contributes to heat hyperalgesia. The role of TRPM3 in sensory neurons innervating internal organs such as the bladder is currently unclear. Here, using retrograde labeling and single-molecule fluorescent RNA in situ hybridization, we demonstrate expression of mRNA encoding TRPM3 in a large subset of dorsal root ganglion (DRG) neurons innervating the mouse bladder, and confirm TRPM3 channel functionality in these neurons using Fura-2-based calcium imaging. After induction of cystitis by injection of cyclophosphamide, we observed a robust increase of the functional responses to agonists of TRPM3, TRPV1, and TRPA1 in bladder-innervating DRG neurons. Cystometry and voided spot analysis in control and cyclophosphamide-treated animals did not reveal differences between wild type and TRPM3-deficient mice, indicating that TRPM3 is not critical for normal voiding. We conclude that TRPM3 is functionally expressed in a large proportion of sensory bladder afferent, but its role in bladder sensation remains to be established.

The effect of amino acids on the bladder cycle: a concise review

The human bladder maintains a cycle of filling, storing, and micturating throughout an individual's lifespan. The cycle relies on the ability of the bladder to expand without increasing the intravesical pressure, which is only possible with the controlled relaxation of well-complaint muscles and the congruously organized construction of the bladder wall. A competent bladder outlet, which functions in a synchronous fashion with the bladder, is also necessary for this cycle to be completed successfully without deterioration. In this paper, we aimed to review the contemporary physiological findings on bladder physiology and examine the effects of amino acids on clinical conditions affecting the bladder, with special emphasis on the available therapeutic evidence and possible future roles of the amino acids in the treatment of the bladder-related disorders.

WAO-ARIA consensus on chronic cough - Part 1: Role of TRP channels in neurogenic inflammation of cough neuronal pathways

BACKGROUND

Cough features a complex peripheral and central neuronal network. The function of the chemosensitive and stretch (afferent) cough receptors is well described but partly understood. It is speculated that chronic cough reflects a neurogenic inflammation of the cough reflex, which becomes hypersensitive. This is mediated by neuromediators, cytokines, inflammatory cells, and a differential expression of neuronal (chemo/stretch) receptors, such as transient receptor potential (TRP) and purinergic P2X ion channels; yet the overall interaction of these mediators in neurogenic inflammation of cough pathways remains unclear.

OBJECTIVES

The World Allergy Organization/Allergic Rhinitis and its Impact on Asthma (WAO/ARIA) Joint Committee on Chronic Cough reviewed the current literature on neuroanatomy and pathophysiology of chronic cough. The role of TRP ion channels in pathogenic mechanisms of the hypersensitive cough reflex was also examined.

OUTCOMES

Chemoreceptors are better studied in cough neuronal pathways compared to stretch receptors, likely due to their anatomical overabundance in the respiratory tract, but also their distinctive functional properties. Central pathways are important in suppressive mechanisms and behavioral/affective aspects of chronic cough. Current evidence strongly suggests neurogenic inflammation induces a hypersensitive cough reflex marked by increased expression of neuromediators, mast cells, and eosinophils, among others. TRP ion channels, mainly TRP V1/A1, are important in the pathogenesis of chronic cough due to their role in mediating chemosensitivity to various endogenous and exogenous triggers, as well as a crosstalk between neurogenic and inflammatory pathways in cough-associated airways diseases.

[Rehabilitation of patients with interstitial cystitis/bladder pain syndrome (IC/BPS)]

After unsuccessful outpatient conservative treatment or invasive inpatient treatment and after cystectomy in interstitial cystitis/bladder pain syndrome (IC/BPS), an inpatient discipline-specific urological rehabilitation (rehab) should be proposed according to the German guideline on IC/BPS. During rehab, diagnostic results will be completed. Multimodal therapy includes the optimisation of lifestyle and medication. Intensive psychotherapy may frequently improve the processing of the disease. Various forms of exercise therapy and physical therapy with water applications, thermotherapy, several forms of massage and electrical or magnetic therapies as well as nutritional advice frequently alleviate complaints in IC/BPS. The different therapies are modified during rehab, if necessary. Social medicine evaluation and advice, e.g. on grade of handicap or ability to work, are also important issues in rehab. Two-thirds of patients show an essential improvement after rehab, which lasts for a prolonged period in about 50% of patients.

Activation of GPR18 by Resolvin D2 Relieves Pain and Improves Bladder Function in Cyclophosphamide-Induced Cystitis Through Inhibiting TRPV1

Purpose

Hyperalgesia and bladder overactivity are two main symptoms of interstitial cystitis/bladder pain syndrome (IC/BPS). Cannabinoid receptors participate in the modulation of pain and bladder function. GPR18, a member of the cannabinoid receptor family, also participates in the regulation of pain and bladder function, but its underlying mechanisms are unknown. In this work, we sought to study the role of GPR18 in IC/BPS.

Methods

A rat model of IC/BPS was established with cyclophosphamide (CYP). Paw withdrawal threshold (PWT) measurement and cystometry were used to evaluate pain and bladder function, respectively. RT-PCR, Western blotting and immunofluorescence were used to assess the expression and distribution of GPR18. The role of GPR18 in pain and bladder function was studied by intrathecal injection of resolvin D2 (RvD2, a GPR18 agonist) and O-1918 (a GPR18 antagonist). Calcium imaging was used to study the relationship between GPR18 and TRPV1.

Results

A rat model of IC/BPS, which exhibited a decreased PWT and micturition interval, was successfully established with CYP. The mRNA and protein expression of GPR18 was reduced in the bladder and dorsal root ganglia (DRG) in rats with CYP-induced cystitis. Intrathecal injection of RvD2 increased the PWT and micturition interval. However, O-1918 blocked the therapeutic effect of RvD2. GPR18 was present in bladder afferent nerves and colocalized with TRPV1 in DRG, and RvD2 decreased capsaicin-induced calcium influx in DRG.

Conclusion

Activation of GPR18 by RvD2 alleviated hyperalgesia and improved bladder function, possibly by inhibiting TRPV1 in rats with CYP-induced cystitis.

A Systematic Review of Therapeutic Approaches Used in Experimental Models of Interstitial Cystitis/Bladder Pain Syndrome

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a multifactorial, chronic bladder disorder with limited therapeutic options currently available. The present review provides an extensive overview of therapeutic approaches used in in vitro, ex vivo, and in vivo experimental models of IC/BPS. Publications were identified by electronic search of three online databases. Data were extracted for study design, type of treatment, main findings, and outcome, as well as for methodological quality and the reporting of measures to avoid bias. A total of 100 full-text articles were included. The majority of identified articles evaluated therapeutic agents currently recommended to treat IC/BPS by the American Urological Association guidelines (21%) and therapeutic agents currently approved to treat other diseases (11%). More recently published articles assessed therapeutic approaches using stem cells (11%) and plant-derived agents (10%), while novel potential drug targets identified were proteinase-activated (6%) and purinergic (4%) receptors, transient receptor potential channels (3%), microRNAs (2%), and activation of the cannabinoid system (7%). Our results show that the reported methodological quality of animal studies could be substantially improved, and measures to avoid bias should be more consistently reported in order to increase the value of preclinical research in IC/BPS for potential translation to a clinical setting.

ASIC2 Synergizes with TRPV1 in the Mechano-Electrical Transduction of Arterial Baroreceptors

Mechanosensitive ion channels (MSCs) are key molecules in the mechano-electrical transduction of arterial baroreceptors. Among them, acid-sensing ion channel 2 (ASIC2) and transient receptor potential vanilloid subfamily member 1 (TRPV1) have been studied extensively and documented to play important roles. In this study, experiments using aortic arch-aortic nerve preparations isolated from rats revealed that both ASIC2 and TRPV1 are functionally necessary, as blocking either abrogated nearly all pressure-dependent neural discharge. However, whether ASIC2 and TRPV1 work in coordination remained unclear. So we carried out cell-attached patch-clamp recordings in HEK293T cells co-expressing ASIC2 and TRPV1 and found that inhibition of ASIC2 completely blocked stretch-activated currents while inhibition of TRPV1 only partially blocked these currents. Immunofluorescence staining of aortic arch-aortic adventitia from rats showed that ASIC2 and TRPV1 are co-localized in the aortic nerve endings, and co-immunoprecipitation assays confirmed that the two proteins form a compact complex in HEK293T cells and in baroreceptors. Moreover, protein modeling analysis, exogenous co-immunoprecipitation assays, and biotin pull-down assays indicated that ASIC2 and TRPV1 interact directly. In summary, our research suggests that ASIC2 and TRPV1 form a compact complex and function synergistically in the mechano-electrical transduction of arterial baroreceptors. The model of synergism between MSCs may have important biological significance beyond ASIC2 and TRPV1.

Chronic psychological stress and lower urinary tract symptoms

It is well established that lower urinary tract symptoms (LUTS), particularly urinary urgency and incontinence, cause stress and anxiety for patients. However, there is mounting evidence that the relationship between these two factors is bidirectional and that chronic psychological stress itself can result in the development of symptoms such as urinary frequency, urgency, incontinence, and pelvic pain. This review considers the evidence that such a relationship exists and reviews the literature from clinical and animal studies to identify some of the mechanisms that might be involved. Inflammatory responses induced by chronic stress appear to offer the strongest link to bladder dysfunction. There is overwhelming evidence, both in patients and animal models, for a release of pro-inflammatory cytokines and chemokines during periods of chronic stress. Furthermore, cytokines have been shown to cause bladder dysfunction and pain via actions in the central nervous system and locally in the bladder. In the brain and spinal cord, pro-inflammatory cytokines influence the regulation of micturition pathways by corticotropin-releasing factor (CRF) and its receptors, while peripherally cytokines affect bladder function, directly causing detrusor hypertrophy and afferent nerve hypersensitivity. There is little information on which treatments may have most benefit for stressed/anxious patients with LUTS, but animal studies suggest traditional drugs for overactive bladder (solifenacin, mirabegron) are more effective on LUTS than anxiolytic drugs (fluoxetine, imipramine). The preliminary preclinical data for CRF receptor antagonists is not consistent. A clearer understanding of the mechanisms involved in stress-induced LUTS should provide a basis for improved treatment of this condition.

Comparative safety review of current pharmacological treatments for interstitial cystitis/ bladder pain syndrome

Introduction: Interstitial cystitis (IC)/bladder pain syndrome (BPS) is a frustrating disease of chronic bladder pain associated with lower urinary tract symptoms. Although there are many proposed treatment algorithms, the uncertainty as to their etiology has a negative impact on the therapeutic outcome. Oftentimes combination therapy of drugs with different mechanisms of action will be utilized to relieve the symptoms. With the various treatment options available to patients and providers, there is an ever-growing need to implement drug efficacy as well as safety to promote best practice in use of the approved drug.Areas covered: This review will focus on guideline-based pharmacotherapies as described by the AUA and EAU, specifically oral, and intravesical therapies with the most up-to-date published literature. Pharmacotherapies targeting bladder, and/or systemic factors in the overall treatment of IC/BPS are discussed with a particular focus on efficacy and drug safety evaluation.Expert opinion: IC/BPS is a syndrome that requires bladder targeting agents to restore the urothelium barrier function and inhibit bladder hypersensitivity as well as various drugs with anti-inflammatory effects, and immune modulation effects. Current pharmacotherapies for IC/BPS have various therapeutic effects and adverse effects depending on the dose and individual response.

Activation of MrgprA3 and MrgprC11 on Bladder-Innervating Afferents Induces Peripheral and Central Hypersensitivity to Bladder Distension

Understanding the sensory mechanisms innervating the bladder is paramount to developing efficacious treatments for chronic bladder hypersensitivity conditions. The contribution of Mas-gene-related G protein-coupled receptors (Mrgpr) to bladder signaling is currently unknown. Using male and female mice, we show with single-cell RT-PCR that subpopulations of DRG neurons innervating the mouse bladder express MrgprA3 (14%) and MrgprC11 (38%), either individually or in combination, with high levels of coexpression with Trpv1 (81%-89%). Calcium imaging studies demonstrated MrgprA3 and MrgprC11 agonists (chloroquine, BAM8-22, and neuropeptide FF) activated subpopulations of bladder-innervating DRG neurons, showing functional evidence of coexpression between MrgprA3, MrgprC11, and TRPV1. In ex vivo bladder-nerve preparations, chloroquine, BAM8-22, and neuropeptide FF all evoked mechanical hypersensitivity in subpopulations (20%-41%) of bladder afferents. These effects were absent in recordings from Mrgpr-clusterΔ^-/- mice. In vitro whole-cell patch-clamp recordings showed that application of an MrgprA3/C11 agonist mixture induced neuronal hyperexcitability in 44% of bladder-innervating DRG neurons. Finally, in vivo instillation of an MrgprA3/C11 agonist mixture into the bladder of WT mice induced a significant activation of dorsal horn neurons within the lumbosacral spinal cord, as quantified by pERK immunoreactivity. This MrgprA3/C11 agonist-induced activation was particularly apparent within the superficial dorsal horn and the sacral parasympathetic nuclei of WT, but not Mrgpr-clusterΔ^-/- mice. This study demonstrates, for the first time, functional expression of MrgprA3 and MrgprC11 in bladder afferents. Activation of these receptors triggers hypersensitivity to distension, a critically valuable factor for therapeutic target development.SIGNIFICANCE STATEMENT Determining how bladder afferents become sensitized is the first step in finding effective treatments for common urological disorders such as overactive bladder and interstitial cystitis/bladder pain syndrome. Here we show that two of the key receptors, MrgprA3 and MrgprC11, that mediate itch from the skin are also expressed on afferents innervating the bladder. Activation of these receptors results in sensitization of bladder afferents, resulting in sensory signals being sent into the spinal cord that prematurely indicate bladder fullness. Targeting bladder afferents expressing MrgprA3 or MrgprC11 and preventing their sensitization may provide a novel approach for treating overactive bladder and interstitial cystitis/bladder pain syndrome.

Transient receptor potential channels in sensory mechanisms of the lower urinary tract

Disruptions to sensory pathways in the lower urinary tract commonly occur and can give rise to lower urinary tract symptoms (LUTS). The unmet clinical need for treatment of LUTS has stimulated research into the molecular mechanisms that underlie neuronal control of the bladder and transient receptor potential (TRP) channels have emerged as key regulators of the sensory processes that regulate bladder function. TRP channels function as molecular sensors in urothelial cells and afferent nerve fibres and can be considered the origin of bladder sensations. TRP channels in the lower urinary tract contribute to the generation of normal and abnormal bladder sensations through a variety of mechanisms, and have demonstrated potential as targets for the treatment of LUTS in functional disorders of the lower urinary tract.

Clinical Observation of the Correlation Between Overactive Bladder and Atopic Constitution in Children

Objective: The present study aimed to analyze the risk factors correlated with overactive bladder (OAB), observe the effects of desloratadine in the treatment of OAB, and explore the correlation between OAB and atopic constitution in children. Methods: Correlation and binary logistic regression analysis of the medical data from 447 children clinically diagnosed with OAB from June 2019 to June 2020 were conducted. The data included a history of urticaria, eczema, itchy skin, and allergic rhinitis or allergic cough. The OABSS scores before and after treatment with desloratadine were compared to evaluate the effectiveness of desloratadine for OAB. Results: The risk factors for OAB in children included eczema, allergic rhinitis or allergic cough, itchy skin, and the levels of total blood IgE. Desloratadine was 96.5% effective in treating cases with risk factors including eczema, allergic rhinitis or allergic cough, and itchy skin. There existed statistical significance in the difference in OABSS scores before and after the treatment of desloratadine (P < 0.05). Conclusion: OAB in children was correlated with atopic manifestations such as eczema, itchy skin, allergic rhinitis, or allergic cough. Desloratadine was safe and effective in the treatment of OAB in children with atopic manifestations.

Clinical Correlation Between Overactive Bladder and Allergy in Children

BACKGROUND

The International Children's Continence Society defines overactive bladder (OAB) as a clinical syndrome characterized by urgency of urination usually accompanied by frequent urination and nocturia symptoms. This study aims to explore the correlation between overactive bladder (OAB) and allergy in children.

METHOD

The clinical characteristics of 918 patients diagnosed with OAB from January 2020 to March 2021 were retrospectively analyzed. Risk factors for OAB were analyzed using logistic regression analysis, and the effect of desloratadine in the treatment of OAB was evaluated.

RESULTS

The incidence of allergic cough or allergic rhinitis in the mild OAB group was higher than the moderate-severe group. Urodynamics demonstrated that the proportion of patients with a sensitive bladder in the overactive detrusor group was significantly higher than the non-overactive detrusor group. The effective rate of treatment of OAB in patients complicated with allergies and taking desloratadine was 90.14%, which was significantly higher than in patients who were not taking desloratadine, and blood IgE level was a risk factor of ineffective treatment with desloratadine.

CONCLUSION

OAB is correlated with allergies in children, and desloratadine can effectively improve OAB symptoms.

Experimentally Induced Bladder Permeability Evokes Bladder Afferent Hypersensitivity in the Absence of Inflammation

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic urological condition characterised by urinary urgency, frequency and pelvic pain, that significantly impacts the quality of life for ∼5% of women. Bladder sensation is coordinated by primary afferent sensory neurons that innervate the bladder wall, translating bladder stretch into signals that travel to the brain via the spinal cord. Whilst the pathophysiology of IC/BPS remains unknown, an increase in the permeability of the bladder urothelium has been proposed as an initiating cause. Here we experimentally increased bladder permeability and tracked bladder afferent sensitivity for up to 28 days. We found that one day after increasing bladder epithelial permeability with in vivo bladder infusion of protamine sulfate, mechanosensitive bladder afferents exhibited significant hypersensitivity to bladder filling. This mechanical hypersensitivity was characterised by significantly increased peak afferent firing rates and a decrease in the activation threshold of individual afferents. Bladder afferent hypersensitivity occurred in the absence of inflammation and changes in bladder muscle compliance, indicating a direct sensitisation of peripheral afferent endings. Bladder afferent mechanosensitive responses to distension returned to control levels by day 7 post-protamine sulfate treatment and remained at control levels at 28-days post-treatment. Here we demonstrate, contrary to the prevailing hypothesis, that increased bladder permeability alone does not induce chronic bladder afferent sensitisation. Whilst experimentally induced changes in bladder permeability are able to induce transient bladder afferent hypersensitivity in the absence of inflammation, highly regulated homeostatic mechanisms exist to rapidly repair the urothelial barrier and normalise bladder afferent mechanosensitivity. Together, these data suggest that additional pathophysiology is required to induce chronic bladder dysfunction.

Therapeutic Efficacy of Human Embryonic Stem Cell-Derived Multipotent Stem/Stromal Cells in Diabetic Detrusor Underactivity: A Preclinical Study

Mesenchymal stem/stromal cell (MSC) therapy is a promising approach for treatment of as yet incurable detrusor underactivity (DUA), which is characterized by decreased detrusor contraction strength and/or duration, leading to prolonged bladder emptying. In the present study, we demonstrated the therapeutic potential of human embryonic stem cell (ESC)-derived multipotent MSCs (M-MSCs) in a diabetic rat model of DUA. Diabetes mellitus (DM) was induced by intraperitoneal injection of streptozotocin (STZ) (50 mg/kg) into 8-week-old female Sprague-Dawley rats. Three weeks later, various doses of M-MSCs (0.25, 0.5, and 1 × 10⁶ cells) or an equivalent volume of PBS were injected into the outer layer of the bladder. Awake cystometry, organ bath, histological, and gene expression analyses were evaluated 1 week (short-term) or 2 and 4 weeks (long-term) after M-MSC transplantation. STZ-induced diabetic rats developed DUA, including phenotypes with significantly longer micturition intervals, increased residual urine amounts and bladder capacity, decreased micturition pressure on awake cystometry, and contractile responses to various stimuli in organ bath studies. Muscle degeneration, mast cell infiltration, fibrosis, and apoptosis were present in the bladders of DM animals. A single local transplantation of M-MSCs ameliorated DUA bladder pathology, including functional changes and histological evaluation, and caused few adverse outcomes. Immunostaining and gene expression analysis revealed that the transplanted M-MSCs supported myogenic restoration primarily by engrafting into bladder tissue via pericytes, and subsequently exerting paracrine effects to prevent apoptotic cell death in bladder tissue. The therapeutic efficacy of M-MSCs was superior to that of human umbilical cord-derived MSCs at the early time point (1 week). However, the difference in efficacy between M-MSCs and human umbilical cord-derived MSCs was statistically insignificant at the later time points (2 and 4 weeks). Collectively, the present study provides the first evidence for improved therapeutic efficacy of a human ESC derivative in a preclinical model of DM-associated DUA.

Alterations in histamine responses between juvenile and adult urinary bladder urothelium, lamina propria and detrusor tissues

Inflammatory mediators may have a role in various lower urinary tract disorders. Histamine is known to induce significant increases in both the tension and frequency of spontaneous phasic contractions in both urothelium with lamina propria (U&LP) and detrusor muscle via the activation of H1 receptor in juvenile animal models. However, it is unclear whether age affects these contractile responses to histamine. This study assessed the histamine receptor subtypes mediating contraction in juvenile and adult porcine bladders and compared the urothelium with lamina propria and detrusor responses to histamine. Isolated tissue bath studies were conducted using strips of porcine U&LP and detrusor obtained from juvenile (6 months) and adult (3 years) animals exposed to histamine receptor agonists and antagonists. Treatment with histamine (100 µM) in U&LP of juvenile animals caused increases in baseline tension by 47.84 ± 6.52 mN/g (p < 0.001, n = 51) and by 50.76 ± 4.10 mN/g (p < 0.001, n = 55) in adult animals. Furthermore, the frequency of spontaneous phasic contractions was significantly enhanced in response to histamine in U&LP of both juvenile and adult tissues (p < 0.001 for both age groups). Treatment with an H2 agonist in U&LP of juvenile animals decreased baseline tension by 13.97 ± 3.45 mN/g (n = 12, p < 0.05), but had no effect in adult animals. Inhibition of H1 receptors resulted in significantly reduced contractile responses of U&LP and detrusor to histamine in both juvenile and adult animals (p < 0.05). Treatment with an H2 receptor antagonist significantly enhanced contractions in juvenile preparations (n = 10, p < 0.05) but had no effect in adult preparations (n = 8). In detrusor, treatment with histamine (100 µM) in juvenile tissues showed a significantly higher increase in baseline tension of 19.10 ± 4.92 mN/g (n = 51) when compared to adult tissues exhibiting increases of 8.21 ± 0.89 mN/g (n = 56, p < 0.05). The increases in the baseline tension were significantly inhibited by the presence of H1 receptor antagonists in both juvenile and adult detrusor preparations. Treatment with either the H2 receptor antagonist or agonist in detrusor had no effect on both juvenile and adult tissues. Therefore, the histamine receptor system may play an essential role in the maintenance of bladder function or in bladder dysfunction observed in some lower urinary tract disorders.