Interstitial cystitis, bladder pain syndrome, hypersensitive bladder, and interstitial cystitis/bladder pain syndrome - clarification of definitions and relationships

Stem cell therapy for interstitial cystitis/bladder pain syndrome

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic disease with limited treatment options. Current multidisciplinary approach targeting bladder inflammation and urothelial dysfunction has limited durable effect that major surgery is ultimately required for both Hunner and non-Hunner type IC. Various investigational attempts are underway to avoid such operations and preserve the urinary bladder. Stem cell therapy is a fascinating option for treating chronic illnesses. Stem cells can self-renew, restore damaged tissue, and have paracrine effects. The therapeutic efficacy and safety of stem cell therapy have been demonstrated in numerous preclinical models, primarily chemically induced cystitis rat models. Only one clinical trial (phase 1 study) has investigated the safety of human embryonic stem cell-derived mesenchymal stem cells in three Hunner-type IC patients. Under general anesthesia, participants underwent cystoscopic submucosal stem cell injection (2.0 × 107 stem cells/5 mL). No safety issues were reported up to 12 months of follow-up and long-term follow-up (up to 3 years). Although there were variations in therapeutic response, all patients reported significant improvement in pain at 1 month postoperatively. One patient underwent fulguration of the Hunner lesion after the trial, but others reported an overall improvement in pain. The analysis on phase 1/2a trial which had several modifications in protocol is currently ongoing. Despite several limitations that need to be overcome, stem cell therapy could be a potential therapeutic option for treating IC/BPS. Clinical outcome on phase 1/2a trial is important and might provide more insight into the clinical application of stem cell therapy for IC/BPS.

Bladder pain syndrome AKA interstitial cystitis - a condition with severe unmet medical need: an exploration of brimapitide as a potential treatment opportunity

PURPOSE OF REVIEW

The purpose of this article is to present recent findings of KU002 (brimapitide) as a novel treatment option for interstitial cystitis/bladder pain syndrome (IC/BPS).

RECENT FINDINGS

IC/BPS is a complex and poorly understood heterogeneous syndrome, with many burdensome symptoms that severely affect patients' quality of life. Treatment options beyond conservative and nonpharmacologic approaches remain limited, and there is an unmet medical need for effective medical treatments. While there are multiple ongoing clinical trials in this area, only a few explore new treatment options. This article summarizes current ongoing development and reports the findings of one such trial.

SUMMARY

In a phase 1/2a exploratory trial, intravesical instillation of brimapitide confirmed local action while eliciting in minimal systemic exposure, resulting in a promising and favorable safety profile. Efficacy exploration suggests that brimapitide reduces pain, improves signs and symptoms of IC/BPS and improves the general wellbeing of the study participants.

Lower Urinary Tract Inflammation and Infection: Key Microbiological and Immunological Aspects

The urinary system, primarily responsible for the filtration of blood and waste, is affected by several infectious and inflammatory conditions. Focusing on the lower tract, this review outlines the physiological and immune landscape of the urethra and bladder, addressing key immunological and microbiological aspects of important infectious/inflammatory conditions. The conditions addressed include urethritis, interstitial cystitis/bladder pain syndrome, urinary tract infections, and urosepsis. Key aspects of each condition are addressed, including epidemiology, pathophysiology, and clinical considerations. Finally, therapeutic options are outlined, highlighting gaps in the knowledge and novel therapeutic approaches.

The expression and distribution of TACAN in human and rat bladders

OBJECTIVES

A lot of ion channels participate in the regulation of bladder function. TACAN, a new mechanosensitive ion channel, was first discovered in 2020. TACAN has been found to be expressed in many tissues, such as the dorsal root ganglia (DRG) and adipose tissue. However, it is unclear whether or not TACAN is expressed in the bladder. In this work, we decided to study the expression and distribution of TACAN in human and rat bladders. Meanwhile, the expression of TACAN in the rat model of interstitial cystitis/bladder pain syndrome (IC/BPS) was studied.

METHODS

Human bladder tissues were obtained from female patients. Cyclophosphamide (CYP) was used to build the rat model of IC/BPS. Real-time polymerase chain reaction, agarose gel electrophoresis, and western blotting were used to assess the expression of TACAN in human and rat bladders. Immunohistochemistry and immunofluorescence were used to observe the distribution of TACAN in human and rat bladders. Hematoxylin-eosin stain, withdrawal threshold, and micturition interval were used to evaluate animal models.

RESULTS

The results of agarose gel electrophoresis and western blotting suggested that TACAN was expressed in human and rat bladders. Immunohistochemical results suggested that TACAN showed positive immunoreaction in the urothelial and detrusor layers. The immunofluorescence results indicated that TACAN was co-stained with UPKIII, α-SMA, and PGP9.5. The IC/BPS model was successfully established with CYP. The mRNA and protein expression of TACAN was upregulated in the CYP-induced rat model of IC/BPS.

CONCLUSIONS

TACAN was found in human and rat bladders. TACAN was mainly distributed in the urothelial and detrusor layers and bladder nerves. The expression of TACAN was upregulated in the CYP-induced rat model of IC/BPS. This new discovery will provide a theoretical basis for future research on the function of TACAN in the bladder and a potential therapeutic target for IC/BPS.

Management of Bladder Pain Syndrome (BPS): A Practical Guide

Bladder pain syndrome (BPS) is a prevalent and pervasive disease. The physical and psychological sequelae can be very burdensome for the patient, and the condition represents a real challenge for the clinician as well. With no simple pathognomonic test, finding harmony in navigating patient care can be demanding. Diagnosis and management rely upon a multidisciplinary and holistic approach. Treatment options include conservative measures and pharmacotherapies as well as bladder instillation therapies. Ultimately, surgery may be offered but only in cases of refractory disease. This article offers a pragmatic guide for clinicians managing this challenging disease.

The effect of intravesical cocktail therapy combined with low-dose amitriptyline on primary bladder pain syndrome

INTRODUCTION AND HYPOTHESIS

We compared the effectiveness of intravesical combination treatment and intravesical treatment plus low-dose amitriptyline in patients with primary bladder pain syndrome (PBPS).

METHODS

A total of 53 patients were included in the study. Demographic data, voiding frequency, nocturia, visual analog scale (VAS) scores, validated O'Leary-Sant IC Symptom Index (ICSI), and IC Problem Index (ICPI) scores and scores on the Short Form-36 (SF-36) questionnaire were collected from the patients at the beginning of the treatment, and at the 6th week and 6th month of the treatment. The patients were divided into two groups. Group 1 received intravesical treatment for 6 weeks. Group 2 received intravesical treatment plus amitriptyline at a dosage of 10 mg/day.

RESULTS

The frequencies of voiding and VAS scores were significantly improved in groups 1 and 2 at the 6th week compared with pretreatment (in group 1 p < 0.001, p < 0.001, and in group 2 p < 0.001, p < 0.001 respectively). The median ICSI and ICPI scores also significantly decreased in groups 1 and 2 (in group 1 p < 0.001, p < 0.001, and in group 2 p < 0.001, p < 0.001 respectively). Scores on the dimensions of the SF-36 questionnaire were significantly improved in both groups. There was no significant change in terms of VAS, nocturia, ICSI or ICPI scores when comparing the 6th week and 6th month results in groups 1 and 2 (all p > 0.05). Only role functioning/emotional achieved a significant improvement in group 2 (p = 0.007).

CONCLUSIONS

Intravesical combination therapies are effective in PBPS treatment. Adding low-dose amitriptyline to intravesical therapy in patients with PBPS improves emotional status.

Urinary Biomarkers in Interstitial Cystitis/Bladder Pain Syndrome and Its Impact on Therapeutic Outcome

Interstitial cystitis/bladder pain syndrome (IC/BPS) is defined as a chronic bladder disorder with suprapubic pain (pelvic pain) and pressure and/or discomfort related to bladder filling accompanied by lower urinary tract symptoms, such as urinary frequency and urgency without urinary tract infection (UTI) lasting for at least 6 weeks. IC/BPS presents significant bladder pain and frequency urgency symptoms with unknown etiology, and it is without a widely accepted standard in diagnosis. Patients’ pathological features through cystoscopy and histologic features of bladder biopsy determine the presence or absence of Hunner lesions. IC/PBS is categorized into Hunner (ulcerative) type IC/BPS (HIC/BPS) or non-Hunner (nonulcerative) type IC/BPS (NHIC/BPS). The pathophysiology of IC/BPS is composed of multiple possible factors, such as chronic inflammation, autoimmune disorders, neurogenic hyperactivity, urothelial defects, abnormal angiogenesis, oxidative stress, and exogenous urine substances, which play a crucial role in the pathophysiology of IC/BPS. Abnormal expressions of several urine and serum specimens, including growth factor, methylhistamine, glycoprotein, chemokine and cytokines, might be useful as biomarkers for IC/BPS diagnosis. Further studies to identify the key molecules in IC/BPS will help to improve the efficacy of treatment and identify biomarkers of the disease. In this review, we discuss the potential medical therapy and assessment of therapeutic outcome with urinary biomarkers for IC/BPS.

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.

Possible Association between Bladder Wall Morphological Changes on Computed Tomography and Bladder-Centered Interstitial Cystitis/Bladder Pain Syndrome

This study aimed to evaluate the clinical significance of urinary bladder wall thickening on computed tomography (CT) among patients with interstitial cystitis/bladder pain syndrome (IC/BPS). Patients with IC/BPS were prospectively enrolled and classified into three groups according to bladder CT finding: smooth bladder wall, focal bladder thickening, and diffuse bladder thickening. Among the 100 patients with IC/BPS, 49, 36, and 15 had smooth bladder wall, focal bladder thickening, and diffuse bladder thickening on CT, respectively. Patients with Hunner’s lesion showed a higher proportion of diffuse and focal bladder thickening compared to those without the same (p < 0.001). Patients with diffuse bladder thickening displayed smaller first sensation of filling, cystometric bladder capacity, and voided volume compared to the rest (all p < 0.001). Patients with focal and diffuse thickening had a higher proportion of inflammatory cell infiltration, uroepithelial cell denudation, and granulation tissue compared to those with smooth bladder wall (p = 0.045, 0.002, and 0.005, respectively). Bladder wall thickening on CT was correlated with clinical phenotypes of IC/BPS, including histopathological findings. Focal or diffuse bladder wall thickening on CT might indicate the presence of chronic bladder wall inflammation and fibrosis and could be used to differentiate bladder-centered IC/BPS.

Immunohistochemistry as a paramount tool in research of normal urothelium, bladder cancer and bladder pain syndrome

The urothelium, an epithelium of the urinary bladder, primarily functions as blood-urine permeability barrier. The urothelium has a very slow turnover under normal conditions but is capable of extremely fast response to injury. During regeneration urothelium either restores normal function or undergoes altered differentiation pathways, the latter being the cause of several bladder diseases. In this review, we describe the structure of the apical plasma membrane that enables barrier function, the role of urothelium specific proteins uroplakins and the machinery for polarized membrane transports in terminally differentiated superficial umbrella cells. We address key markers, such as keratins, cancer stem cell markers, retinoic acid signalling pathway proteins and transient receptor potential channels and purinergic receptors that drive normal and altered differentiation in bladder cancer and bladder pain syndrome. Finally, we discuss uncertainties regarding research, diagnosis and treatment of bladder pain syndrome. Throughout the review, we emphasise the contribution of immunohistochemistry in advancing our understanding of processes in normal and diseased bladder as well as the most promising possibilities for improved bladder cancer and bladder pain syndrome management.

Efficacy and safety of intravesical instillation of KRP-116D (50% dimethyl sulfoxide solution) for interstitial cystitis/bladder pain syndrome in Japanese patients: A multicenter, randomized, double-blind, placebo-controlled, clinical study

Objective

To evaluate the efficacy and safety of intravesical KRP‐116D, 50% dimethyl sulfoxide solution compared with placebo, in interstitial cystitis/bladder pain syndrome patients.

Methods

Japanese interstitial cystitis/bladder pain syndrome patients with an O’Leary‐Sant Interstitial Cystitis Symptom Index score of ≥9, who exhibited the bladder‐centric phenotype of interstitial cystitis/bladder pain syndrome diagnosed by cystoscopy and bladder‐derived pain, were enrolled. Patients were allocated to receive either KRP‐116D (n = 49) or placebo (n = 47). The study drug was intravesically administered every 2 weeks for 12 weeks.

Results

For the primary endpoint, the change in the mean O’Leary‐Sant Interstitial Cystitis Symptom Index score from baseline to week 12 was −5.2 in the KRP‐116D group and −3.4 in the placebo group. The estimated difference between the KRP‐116D and placebo groups was −1.8 (95% confidence interval −3.3, −0.3; P = 0.0188). Statistically significant improvements for KRP‐116D were also observed in the secondary endpoints including O’Leary‐Sant Interstitial Cystitis Problem Index score, micturition episodes/24 h, voided volume/micturition, maximum voided volume/micturition, numerical rating scale score for bladder pain, and global response assessment score. The adverse drug reactions were mild to moderate, and manageable.

Conclusions

This first randomized, double‐blind, placebo‐controlled trial shows that KRP‐116D improves symptoms, voiding parameters, and global response assessment, compared with placebo, and has a well‐tolerated safety profile in interstitial cystitis/bladder pain syndrome patients with the bladder‐centric phenotype.

Bladder pain syndrome/interstitial cystitis in contemporary UK practice: Outcomes of phenotype-directed management

OBJECTIVES

Problem bladder pain syndrome/interstitial cystitis (BPS/IC) is a heterogeneous disorder with variation in management worldwide. Phenotyping aims to personalize therapy and optimize outcomes. The most well-described phenotype is Hunner lesion disease (HLD). The prevalence of HLD and outcome of phenotype-directed management in the UK is not well-studied. We describe the management of a contemporary cohort of patients with BPS/IC in the UK.

METHODS

Retrospective analysis of all patients with BPS/IC from January 2015-November 2018. Outcomes of patients who underwent laser ablation to Hunner lesions were collected using the Global Response Assessment tool.

RESULTS

One hundred and sixty-three patients (mean age of 43 years [20-85]) were included. 78% were female and patients had experienced symptoms for an average 6 years (1-30) prior to specialist assessment. Eighty-three percent of patients had pelvic imaging (44% ultrasound, 42% magnetic resonance imaging and 14% computed tomography), and a relevant abnormality was found in five (4%). Twenty-two patients (14%) had HLD (International Society for the Study of BPS [ESSIC] 3), with a mean bladder capacity of 373 mL (175-650 mL); 77% were ESSIC C on histopathology. All patients with HLD underwent laser ablation, with 55% experiencing a moderate/marked improvement in symptoms, with a mean duration of effect of 10 months (3-36); 27% of patients had a repeat treatment.

CONCLUSIONS

The presence of HLD in patients with BPS/IC is not uncommon. Pelvic imaging rarely identifies any cause for pain and so cystoscopy under anesthesia is essential for accurate phenotyping. Phenotype-directed management with holmium laser ablation to Hunner lesions has good short-term efficacy in improving pain, but re-intervention is often required.

Predictive Factors for a Satisfactory Treatment Outcome with Intravesical Botulinum Toxin A Injection in Patients with Interstitial Cystitis/Bladder Pain Syndrome

A botulinum toxin A (BoNT-A) intravesical injection can improve the symptoms of interstitial cystitis/bladder pain syndrome (IC/BPS). Patients with IC/BPS have different clinical characteristics, urodynamic features, and cystoscopic findings. This study assessed the treatment outcomes of a BoNT-A intravesical injection and aimed to identify the predictive factors of a satisfactory outcome. This retrospective study included IC/BPS patients treated with 100 U BoNT-A. The treatment outcomes were assessed by global response assessment (GRA) at 6 months. We classified patients according to different clinical, urodynamic, and cystoscopic characteristics and evaluated the treatment outcomes and predictive factors. A total of 238 patients were included. Among these patients, 113 (47.5%) had a satisfactory outcome (GRA ≥ 2) and 125 (52.5%) had an unsatisfactory outcome. Improvements in the IC symptom score, IC problem score, O'Leary-Sant symptom score, and visual analog scale score for pain were significantly greater in patients with a satisfactory outcome than in patients with an unsatisfactory outcome (all p = 0.000). The IC disease duration and maximal bladder capacity (MBC) were significantly different between patients with and without a satisfactory outcome. Multivariate analysis revealed that only the MBC was a predictor for a satisfactory outcome. Patients with a MBC of ≥760 mL and glomerulations of 0/1 (58.7%) or glomerulations of 2/3 (75.0%) frequently had a satisfactory outcome. We found that BoNT-A intravesical injection can effectively improve symptoms among patients with IC/BPS, with a remarkable reduction in bladder pain. A MBC of ≥760 mL is a predictive factor for a satisfactory treatment outcome.