Differential expression of histamine receptors in the bladder wall tissues of patients with bladder pain syndrome/interstitial cystitis - significance in the responsiveness to antihistamine treatment and disease symptoms

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.

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.

Effectiveness of intravesical ozone in interstitial cystitis by the O'Leary-Sant symptom index

Introduction and hypothesis

A prospective clinical, preliminary study was performed in patients with interstitial cystitis/bladder pain syndrome (IC/BPS) who were nonresponders to conventional treatment and received intravesical ozone as a therapeutic alternative.

Methods

Sixteen patients received six applications of intravesical ozone at a concentration of 41 μg/mL. We evaluated therapeutic efficacy by the percentage reduction of Interstitial Cystitis Symptom and Problem Index scores (ICSI/ICPI—the O'Leary–Sant symptom index), recurrence rate, nonresponse, and side effects in scores collected on admission (pre-treatment), at the end of the therapeutic protocol (post-treatment), and 180 days (follow-up) after the last ozone application.

Results

The mean age of women was 52.9 years (SD: 15.5), and the duration of symptoms was 5.7 years (SD: 7.1). The median ICSI on admission was 17 (IQR: 14.25–19.5) and at follow-up was 0.5 (IQR: 0–2), with a reduction of 97.5% (CI: 85.7–100). The median ICSI/ICPI on admission was 31.5 (IQR: 29–35.2) and at follow-up was 2.0 (IQR: 0–3.75), with a reduction of 92.3% (CI: 88.8–100). The recurrence rate was only 6.25%, and no patients were nonresponders to the treatment.

Conclusions

The application of intravesical ozone was effective in the treatment of patients with IC/BPS who were nonresponders to conventional therapy, showing a progressive and safe effect, at least in the short term.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00192-022-05383-3.

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.

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.

P2X7 Receptor Blockade Protects Against Acrolein-Induced Bladder Damage: A Potential New Therapeutic Approach for the Treatment of Bladder Inflammatory Diseases

Inflammatory conditions of the urinary bladder have been shown to be associated with urothelial damage and loss of function. The purinergic P2X7 receptor has been implicated in several inflammatory conditions. The aim of this study was to investigate the role of the P2X7 receptor in acrolein-induced inflammatory damage using the porcine urinary bladder. For this purpose, an ex-vivo model of porcine urothelial damage induced by direct instillation of acrolein into the whole bladder lumen was used. To determine the role of the P2X7 receptor, the bladders were pre-incubated with a selective P2X7 receptor antagonist, A804598 (10 μM), for 1 h. The effects of the acrolein-induced urothelial damage on the bladder’s function were assessed by examining the bladder wall contractile response, structure changes, apoptosis, and oxidative stress in the bladder tissues. The acrolein treatment led to significant damage to the urothelium histology, tight junction expression, and contractile responses. Acrolein also induced apoptosis in the mucosa layer. All these acrolein-induced responses were attenuated by pre-treatment with the P2X7 receptor antagonist A804598. Acrolein also significantly induced DNA oxidation in the submucosal layer; however, the P2X7 receptor antagonism did not show any protective effect towards the acrolein-induced oxidative stress. These findings suggested that the P2X7 receptor is involved in the acrolein-induced damage to the urothelium; therefore, the P2X7 receptor antagonists may be a new therapeutic option for the treatment of bladder inflammation.

Does cystoscopy method affect the investigation of bladder pain syndrome/interstitial cystitis?

INTRODUCTION AND HYPOTHESIS

Cystoscopic investigation to identify associated histological findings of increased mast cells in the detrusor muscle has been recommended by the European Society for the Study of Bladder Pain Syndrome (ESSIC) in the investigation of bladder pain syndrome/interstitial cystitis (BPS/IC). The aim of this study was to identify if the cystoscopy approach impacts the biopsy results when investigating women presenting with symptoms of BPS/IC.

METHODS

We performed a single-centre retrospective analysis of 300 bladder biopsy reports from 2015 to 2018 from women undergoing cystoscopy for BPS/IC. Biopsies obtained using closed cup forceps through a flexible (FC) or rigid cystoscope (RC) were compared.

RESULTS

Fifty-eight FC biopsies were compared with 242 RC biopsies. FC biopsies had a smaller mean diameter (1.6 mm vs 2.9 mm p < 0.01) and volume (4.1 mm3 vs 9.6 mm3 p < 0.001) compared with RC biopsies. There was no significant difference in the histological depth of sampling to the muscularis propria. A total of 292 samples had CD117 immunohistochemical staining for mast cell count (MCC) analysis. The MCC/mm2 was significantly lower in FC biopsies (p < 0.01). Sixteen percent of FC samples compared with 60% of RC samples had a high MCC >28/mm2 (p < 0.01). There was no significant difference in positive microbiology culture between FC (21%) and RC (28%) sampling.

CONCLUSION

Rigid and flexible cystoscopy can be used to investigate BPS/IC as recommended by international societies. However, the biopsy method impacts the mast cell count analysis, which can influence diagnosis and management. Therefore, RC would be the optimal investigation.

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.

Biomaterial-assisted drug delivery for interstitial cystitis/bladder pain syndrome treatment

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic and painful bladder condition afflicting patients with increased urinary urgency and frequency as well as incontinence. Owing to the elusive pathogenesis of IC/BPS, obtaining effective therapeutic outcomes remains challenging. Current administrational routes such as intravesical-bladder injection improve the treatment efficacy and reduce systemic side effects. However, the bladder permeability barrier hinders drug penetration into the bladder wall to meet the desired therapeutic expectation. These issues can be addressed by encapsulating drugs into biomaterials. When appropriately exploited, they would increase the drug dwelling time in the bladder, enhance the penetration of mucosa and improve the therapeutic response of IC/BPS. In this review, we first elucidate the pathogenesis and animal models of IC/BPS. Then, we highlight recent representative biomaterial-assisted drug delivery systems for IC/BPS treatment. Finally, we discuss the challenges and outlook for further developing biomaterial-based delivery systems for IC/BPS management.

Phenotypes of BPS/IC

Purpose of Review

The aim of this review is to summarise the latest research related to different phenotypes of BPS/IC, addressing the evidence for current well-defined phenotypes as well as identifying novel potential phenotypes and highlighting areas for future study.

Recent Findings

Two distinct phenotypes of BPS/IC are well-recognised: Hunner’s lesion disease and non-Hunner’s lesion BPS/IC. Recent studies have shown these phenotypes exhibit distinct clinical, pathological and cystoscopic features, and targeted treatment to Hunner’s lesions can prove effective. Recent studies have also identified new potential phenotypes based on biochemical, molecular and histological markers, pathophysiological mechanisms of disease, clinical features, cystoscopic findings, radiological features and urodynamic factors. This evidence has improved our understanding of the underlying mechanism of disease and may enable more personalised and targeted therapy in the future.

Summary

Novel phenotypes of BPS/IC relate to the presence of certain biomarkers, alterations in the urinary microbiome, the characteristics of pain and presence of co-existing somatic and psychosocial conditions, altered patterns of brain white matter changes and urodynamic features. Further study is required to evaluate whether these potential phenotypes are clinically useful based on their ability to guide treatment selection and predict outcome from therapy, and therefore optimise therapeutic outcomes.