Broaden Horizons: The Advancement of Interstitial Cystitis/Bladder Pain Syndrome

Innovative applications of natural polysaccharide polymers in intravesical therapy of bladder diseases

Natural polysaccharide polymers, characterized by their remarkable biocompatibility, biodegradability, and structural versatility, hold great promise for intravesical therapy in treating of bladder diseases. Conditions such as bladder cancer and interstitial cystitis compromise drug efficacy by affecting the permeability of the bladder wall. Traditional therapeutic approaches are often hindered by physiological challenges, including rapid drug clearance and the intrinsic permeability barrier of the bladder. Polysaccharides like hyaluronic acid (HA) and chitosan (CS) have emerged as promising materials for intravesical drug delivery systems (IDDS), owing to their ability to repair tight junctions in the bladder wall, mitigate inflammation, and enhance permeability. This review provides a comprehensive overview of the mechanisms through which polysaccharide-based natural polymers regulate bladder wall permeability and highlights their advancements in delivery platforms, including nanoparticles, hydrogels, floating systems, and composite materials. By improving drug retention, enhancing bioavailability, and promoting patient adherence, these materials offer a solid foundation for the development of innovative therapeutic strategies for bladder diseases.

Platelet-rich plasma improves cyclophosphamide-induced interstitial cystitis in rat models through the toll-like receptor 4/nuclear factor-kappa B signalling pathway

OBJECTIVE

To investigate the therapeutic effect of platelet-rich plasma (PRP) on a cyclophosphamide (CYP)-induced interstitial cystitis (IC) rat model.

METHODS

A CYP-induced IC rat model (75 mg/kg every 3 days, with a total of five injections) was used to evaluate the therapeutic effects of PRP. Here, PRP was administered via bladder irrigation (every 2 days, with a total of three irrigations), and bladder tissue was analysed for inflammation and histological changes. The toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signalling pathway was assessed using real-time quantitative polymerase chain reaction and ribonucleic acid sequencing. In addition, lipopolysaccharide (LPS)-induced SV-HUC-1 cells (10 μg/LPS and 2.5 mM adenosine triphosphate) were employed to investigate the inflammatory response and the effects of PRP on the TLR4/NF-κB signalling pathway.

RESULTS

The PRP treatment significantly improved the bladder tissue condition in the CYP-induced IC rat model, as evidenced by reduced inflammation and histological damage. The damage and shedding of the superficial epithelium of the bladder mucosa were notably decreased following PRP bladder instillation. Importantly, the expression of ZO-1, a key marker of epithelial integrity, was upregulated in PRP-treated rats, indicating enhanced bladder epithelial function. High-throughput analysis revealed that PRP alleviated bladder mucosal injury in the IC rat model through the TLR4/NF-κB signalling pathway. In LPS-induced SV-HUC-1 cells, PRP treatment also increased ZO-1 expression, decreased CDH1 expression and regulated the TLR4/NF-κB signalling pathway.

CONCLUSION

Platelet-rich plasma treatment may improve the expression of ZO-1 and CDH1 in urinary epithelium in vitro by mediating the TLR4/NF-κB pathway, which is effective in the treatment of IC.

Electroacupuncture Neural Stimulation Mitigates Bladder Dysfunction and Mechanical Allodynia in Cyclophosphamide Induced Cystitis through Downregulation of the BDNF-TrkB Signaling Pathway

Central sensitization plays a critical role in bladder pain syndrome/interstitial cystitis (BPS/IC). Electroacupuncture (EA) nerve stimulation therapy has been broadly acknowledged as an effective means of alleviating chronic pathological pain. However, it remains to be explored whether EA is effective in mitigating pain-sensitive symptoms of BPS/IC and the mechanisms involved. This study aims to investigate the analgesic effect and mechanism of EA therapy. To achieve this goal, we employed several techniques: mechanical pain threshold tests to assess pain sensitivity, urodynamic studies to evaluate bladder function, Western blotting (WB) for protein analysis, immunofluorescence for visualizing, and transcriptomics. A rat cystitis model was established through a systemic intraperitoneal injection with cyclophosphamide (CYP). EA therapy was executed by stimulating the deep part of the hypochondriac point, where the 2nd-4th sacral nerves traverse. EA treatment was observed to effectively reduce mechanical allodynia, enhance urinary function, suppress the activation of microglial cells, and alleviate neuroinflammation. Additionally, EA demonstrated the capability to downregulate BDNF-TrkB signal transduction in the spinal dorsal horn. Transcriptome sequencing has indicated that EA therapy potentially inhibits excitatory neural transmission and modulates several pathways related to longevity. Furthermore, EA therapy has shown efficacy in treating conditions such as Huntington's disease, amyotrophic lateral sclerosis, and prion diseases. In conclusion, by regulating the BDNF-TrkB signaling, EA nerve stimulation can effectively alleviate bladder dysfunction and mechanical allodynia in cyclophosphamide-induced cystitis model. Our research elucidates the underlying mechanisms of EA therapy in treating bladder dysfunction and offers new theoretical insights for addressing painful sensitization in BPS.Significance Statement Central sensitization is a major factor in bladder pain syndrome/interstitial cystitis (BPS/IC), making effective pain management crucial. This study explores the potential of electroacupuncture (EA) as a therapeutic approach to alleviate pain and improve bladder function in a rat model of BPS/IC induced by cyclophosphamide. Our findings demonstrate that EA therapy significantly reduces mechanical allodynia, enhances urinary function, and decreases neuroinflammation by modulating BDNF-TrkB signaling in the spinal dorsal horn. The research highlights EA's capability to inhibit excitatory neural transmission and provide relief in chronic pain conditions. These results offer new insights into the mechanisms of EA therapy, potentially improving treatment strategies for BPS/IC and similar pain syndromes.

Exploring the anti-inflammatory effects of phytochemicals in attenuating interstitial cystitis-a literature review

Interstitial cystitis is a fierce syndrome affecting the quality of life of thousands of individuals around the globe. It causes immense pain in the bladder and associated viscera along with inflammation-like lesions. The current medicinal and pharmacological research focuses on the protective and curative effects of phytochemicals in several ailments. Phytochemicals derived from many medicinal plants have shown potent outcomes in protection against various pathological conditions including interstitial cystitis. This review has summarized the insights of in vitro and in vivo studies regarding the effects of phytochemicals in fading the inflammation in bladder tissue and exhibiting a protective effect on the urothelium. Hemorrhagic cystitis is a common manifestation in patients undergoing chemotherapy with cyclophosphamide and related alkylating agents. Sodium 2-mercaptoethane sulfonate (Mesna) has traditionally been employed in clinical practice to counter cyclophosphamide-induced cystitis in humans. However, cyclophosphamide has been employed in developing animal models of interstitial cystitis in in vivo studies. Phytochemicals including quercetin, beta-caryophyllene, curcumol, boswellic acid, caftaric acid, some flavonoids and other secondary metabolites being a consequential component of numerous medicinal plants, have displayed a significant reduction in the levels of proinflammatory cytokines including TNF-α, NFĸB, IL-1β, NLRP3 inflammasome, IL-6, IL-2, matrix metalloproteinases etc. Uroprotective outcomes of these phytochemicals have been found to result in diminished oxidative stress and restoration of glutathione, superoxide dismutase, and related proteins in the inflamed bladder tissue. Many in vivo studies involving cyclophosphamide-induced interstitial cystitis have confirmed these findings. The coupling of phytotherapy with novel drug delivery systems such as nanoparticles, liposomes, nanotubes, quantum dots, etc. can help translate these beneficial effects of phytochemicals into clinical practice. Further investigations of these phytochemicals can provide intuition regarding the development of newer drug molecules having exclusive activity for attenuating interstitial cystitis.

Identification and validation of immune and diagnostic biomarkers for interstitial cystitis/painful bladder syndrome by integrating bioinformatics and machine-learning

Background

The etiology of interstitial cystitis/painful bladder syndrome (IC/BPS) remains elusive, presenting significant challenges in both diagnosis and treatment. To address these challenges, we employed a comprehensive approach aimed at identifying diagnostic biomarkers that could facilitate the assessment of immune status in individuals with IC/BPS.

Methods

Transcriptome data from IC/BPS patients were sourced from the Gene Expression Omnibus (GEO) database. We identified differentially expressed genes (DEGs) crucial for gene set enrichment analysis. Key genes within the module were revealed using weighted gene co-expression network analysis (WGCNA). Hub genes in IC/BPS patients were identified through the application of three distinct machine-learning algorithms. Additionally, the inflammatory status and immune landscape of IC/BPS patients were evaluated using the ssGSEA algorithm. The expression and biological functions of key genes in IC/BPS were further validated through in vitro experiments.

Results

A total of 87 DEGs were identified, comprising 43 up-regulated and 44 down-regulated genes. The integration of predictions from the three machine-learning algorithms highlighted three pivotal genes: PLAC8 (AUC: 0.887), S100A8 (AUC: 0.818), and PPBP (AUC: 0.871). Analysis of IC/BPS tissue samples confirmed elevated PLAC8 expression and the presence of immune cell markers in the validation cohorts. Moreover, PLAC8 overexpression was found to promote the proliferation of urothelial cells without affecting their migratory ability by inhibiting the Akt/mTOR/PI3K signaling pathway.

Conclusions

Our study identifies potential diagnostic candidate genes and reveals the complex immune landscape associated with IC/BPS. Among them, PLAC8 is a promising diagnostic biomarker that modulates the immune response in patients with IC/BPS, which provides new insights into the future diagnosis of IC/BPS.

The Efficacy of Micro-Radiofrequency Therapy for Treating Non-Hunner Lesion Interstitial Cystitis/Bladder Pain Syndrome: A Retrospective Cohort Study

INTRODUCTION AND HYPOTHESIS

The objective was to explore the efficacy of micro-radiofrequency (micro-RF) therapy for treating non-Hunner interstitial cystitis (NHIC).

METHODS

Forty female NHIC patients were enrolled in this retrospective study from December 2021 to December 2023, with 20 receiving intravesical micro-RF therapy and 20 undergoing hydrodistension (HD). The primary evaluation index was the treatment success rate using the Global Response Assessment (GRA) scale. Secondary indexes included changes from baseline in the visual analog scale (VAS) for pain, Interstitial Cystitis Symptom Index (ICSI) and Interstitial Cystitis Problem Index (ICPI), Pelvic Pain and Urgency/Frequency (PUF) patient symptom scale, and urination parameters. Outcomes were analyzed via t or nonparametric tests.

RESULTS

All 40 patients completed the treatment and follow-up; the treatment success rate of the micro-RF group (70%, 14 out of 20) was slightly higher than that of the HD group (50%, 10 out of 20) at 12 weeks post-treatment, with no significant difference (20%, p = 0.197). The VAS, ICSI, ICPI, PUF, day-time frequency, urgency episodes, and nocturia significantly decreased in both groups after treatment (p < 0.05). Further, the median decline ranges of VAS (-4.0 vs -3.0; p = 0.017; 95% CI -1.45, -0.15) and ICPI (-5.0 vs -4.0; p = 0.011; 95% CI -2.02, -0.283) were significantly larger in the micro-RF group. There were no significant differences in ICSI (-6.5 vs -6.0, p = 0.407), PUF (-10.0 vs. -8.0; p = 0.071), and urgency episodes (-5.5 vs -4.5; p = 0.570).

CONCLUSIONS

Our study showed that the short-term overall efficacy of micro-RF therapy was better than hydrodistension, particularly in managing pain, and might be a new alternative treatment option for patients with NHIC.

Modulation of persistent bladder pain in mice: The role of macrophage migration inhibitory factor, high mobility group box-1, and downstream signaling pathways

Background

Repeated intravesical activation of protease-activated receptor-4 (PAR4) serves as a model of persistent bladder hyperalgesia (BHA) in mice, which lasts several days after the final stimulus. Spinal macrophage migration inhibitory factor (MIF) and high mobility group box 1 (HMGB1) are critical mediators in the persistence of BHA.

Objective

We aimed to identify effective systemic treatments for persistent BHA using antagonists or transgenic deletions.

Methods

Persistent BHA was induced through transurethral instillations of a PAR4-activating peptide (PAR4-AP; 100 μM, 1 h; scrambled peptide, control) under anesthesia, administered on Days 0, 2, and 4. Lower abdominal hypersensitivity was measured on Days 0-4 and 7-9. Systemic injections from Days 2-8 included ISO-1 (a MIF antagonist), ethyl pyruvate (an inhibitor of HMGB1 release), phosphate-buffered saline, or 10% DMSO (vehicle control) in C57BL/6 mice. To examine the role of HMGB1 receptors, Toll-like receptor-4 (TLR4)-null mice or systemic treatment with FPS-ZM1 (receptor for advanced glycation end product [RAGE] antagonist) were used. In addition, TIR-domain-containing adaptor-inducing interferon-β (TRIF)-null mice were tested to assess the involvement of TLR4 signaling pathways. Micturition volume and frequency were assessed on Day 9, and the bladder was histopathologically examined to assess inflammation and edema.

Results

MIF antagonism significantly reversed persistent BHA, whereas HMGB1 antagonism led to a partial reduction of persistent BHA. TLR4 deficiency or systemic administration of FPS-ZM1 significantly mitigated persistent BHA, while TRIF-deficient mice experienced a faster onset of BHA. Only MIF or HMGB1 inhibition resulted in increased micturition volume. The histopathological examination revealed no changes in inflammation or edema.

Conclusion

MIF and HMGB1, acting through TLR4 and RAGE, mediated persistent BHA, while TRIF might modulate its onset. Further exploration of downstream TLR4 signaling may uncover novel therapeutic targets for treating persistent bladder pain.

Comparative analysis of surgical prognostic between HIC and NHIC patients after cystoscopy with hydrodistention

This study aims to clarify the pathogenic mechanism of interstitial cystitis (IC), which has led to uncertainty in its diagnosis and treatment. We examined data from 18 interstitial cystitis with Hunner lesions (HIC) and 18 interstitial cystitis without Hunner lesions (NHIC) patients, including their clinical information, urodynamic test results, and maximum bladder capacity. A 1-year follow-up tracked disease progression. Postoperative recovery showed that HIC patients experienced significantly greater improvements in Visual Analog Scale pain scores compared to NHIC patients (P = .0049). This trend continued at the 6-month mark (P = .0056). Over the 1-year follow-up, NHIC patients exhibited a statistically significant improvement in Pain and Urgency/Frequency scores, while HIC patients had a gradual overall score increase from preoperative to postoperative stages. However, no significant differences were observed in either group at 1 year postoperatively compared to preoperative scores. This study revealed distinct differences between HIC and NHIC patients, including reduced bladder volumes and more severe nociceptive pain in HIC patients. Early analgesic interventions effectively alleviated discomfort in HIC patients. The combination of cystoscopic hydrodistention and water dilatation was highly effective in relieving pain symptoms in HIC patients but increased the risk of recurrence, necessitating recurrent bladder infusion and timely therapeutic adjustments. In contradiction to prior paradigms, the surgical intervention of cystoscopic water hydrodistention also yielded favorable outcomes among NHIC patients.

Intravesical Instillations of Hyaluronic Acid as First-Line Treatment in Patients with Interstitial Cystitis/Bladder Pain Syndrome: Use, Efficacy and Effects on Quality of Life

The efficacy of hyaluronic acid instillations as therapy for patients with Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS) has been demonstrated in some clinical studies, with response rates up to 70%. The aim of the study is to investigate the change in symptoms and quality of life in female patients with IC/BPS after intravesical instillations of hyaluronic acid used as first-line treatment. A retrospective single-center cohort study was conducted. Female patients, whose symptoms were compatible with the diagnosis of IC/BPS as defined by the International Continence Society, were treated with a variable number of intravesical instillations of a hyaluronic acid-based drug. Three validated questionnaires were administered by telephone to all patients, before the beginning of the treatment and 6 months after the last administration of the drug. A total of 50 patients with symptoms compatible with the diagnosis of IC/BPS were included in the study. The median number of instillations performed is 4. For all questionnaires, the median value was significantly reduced following treatment with intravesical instillations (p = 0.000). The present study has shown that intravesical hyaluronic acid treatment results in both statistically and clinically significant symptomatic improvement, thereby improving the quality of life of patients with IC/BPS.

MIF-Modulated Spinal Proteins Associated with Persistent Bladder Pain: A Proteomics Study

Bladder pain is a prominent symptom in Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS). We studied spinal mechanisms of bladder pain in mice using a model where repeated activation of intravesical Protease Activated Receptor-4 (PAR4) results in persistent bladder hyperalgesia (BHA) with little or no bladder inflammation. Persistent BHA is mediated by spinal macrophage migration inhibitory factor (MIF), and is associated with changes in lumbosacral proteomics. We investigated the contribution of individual spinal MIF receptors to persistent bladder pain as well as the spinal proteomics changes associated with relief of persistent BHA by spinal MIF antagonism. Female mice with persistent BHA received either intrathecal (i.t.) MIF monoclonal antibodies (mAb) or mouse IgG1 (isotype control antibody). MIF antagonism temporarily reversed persistent BHA (peak effect: 2 h), while control IgG1 had no effect. Moreover, i.t. antagonism of the MIF receptors CD74 and C-X-C chemokine receptor type 4 (CXCR4) partially reversed persistent BHA. For proteomics experiments, four separate groups of mice received either repeated intravesical scrambled peptide and sham i.t. injection (control, no pain group) or repeated intravesical PAR4 and: sham i.t.; isotype IgG1 i.t. (15 μg); or MIF mAb (15 μg). L6-S1 spinal segments were excised 2 h post-injection and examined for proteomics changes using LC-MS/MS. Unbiased proteomics analysis identified and relatively quantified 6739 proteins. We selected proteins that showed significant changes compared to control (no pain group) after intravesical PAR4 (sham or IgG i.t. treatment) and showed no significant change after i.t. MIF antagonism. Six proteins decreased during persistent BHA (V-set transmembrane domain-containing protein 2-like confirmed by immunohistochemistry), while two proteins increased. Spinal MIF antagonism reversed protein changes. Therefore, spinal MIF and MIF receptors mediate persistent BHA and changes in specific spinal proteins. These novel MIF-modulated spinal proteins represent possible new targets to disrupt spinal mechanisms that mediate persistent bladder pain.

MiR-9-enriched mesenchymal stem cells derived exosomes prevent cystitis-induced bladder pain via suppressing TLR4/NLRP3 pathway in interstitial cystitis mice

BACKGROUND

Inflammatory response of central nervous system is an important component mechanism in the bladder pain of interstitial cystitis/bladder pain syndrome (IC/BPS). Exosomes transfer with microRNAs (miRNA) from mesenchymal stem cell (MSCs) might inhibit inflammatory injury of the central nervous system. Herein, the purpose of our study was to explore the therapeutic effects by which extracellular vesicles （EVs） derived from miR-9-edreched MSCs in IC/BPS and further investigate the potential mechanism to attenuate neuroinflammation.

METHODS

On the basis of IC/BPS model, we used various techniques including bioinformatics, cell and molecular biology, and experimental zoology, to elucidate the role and molecular mechanism of TLR4 in regulating the activation of NLRP3 inflammasome in bladder pain of IC/BPS, and investigate the mechanism and feasibility of MSC-EVs enriched with miR-9 in the treatment of bladder pain of IC/BPS.

RESULTS

The inflammatory responses in systemic and central derived by TLR4 activation were closely related to the cystitis-induced pelvic/bladder nociception in IC/BPS model. Intrathecal injection of miR-9-enreched MSCs derived exosomes were effective in the treatment of cystitis-induced pelvic/bladder nociception by inhibiting TLR4/NF-κb/NLRP3 signal pathway in central nervous system of IC/BPS mice.

CONCLUSIONS

This study demonstrated that miR-9-enreched MSCs derived exosomes alleviate neuroinflammaiton and cystitis-induced bladder pain by inhibiting TLR4/NF-κb/NLRP3 signal pathway in interstitial cystitis mice, which is a promising strategy against cystitis-induced bladder pain.

Molecular Links between Sensory Nerves, Inflammation, and Pain 2.0

Capsaicin-sensitive peptidergic sensory nerves mediate triple actions: besides transmitting sensory and pain signals to the central nervous system (afferent function), they also have local and systemic efferent functions [...].

Molecular Profiling of Inflammatory Processes in a Mouse Model of IC/BPS: From the Complete Transcriptome to Major Sex-Related Histological Features of the Urinary Bladder

Animal models are invaluable in the research of the pathophysiology of interstitial cystitis/bladder pain syndrome (IC/BPS), a chronic aseptic urinary bladder disease of unknown etiology that primarily affects women. Here, a mouse model of IC/BPS was induced with multiple low-dose cyclophosphamide (CYP) applications and thoroughly characterized by RNA sequencing, qPCR, Western blot, and immunolabeling to elucidate key inflammatory processes and sex-dependent differences in the bladder inflammatory response. CYP treatment resulted in the upregulation of inflammatory transcripts such as Ccl8, Eda2r, and Vegfd, which are predominantly involved in innate immunity pathways, recapitulating the crucial findings in the bladder transcriptome of IC/BPS patients. The JAK/STAT signaling pathway was analyzed in detail, and the JAK3/STAT3 interaction was found to be most activated in cells of the bladder urothelium and lamina propria. Sex-based data analysis revealed that cell proliferation was more pronounced in male bladders, while innate immunity and tissue remodeling processes were the most distinctive responses of female bladders to CYP treatment. These processes were also reflected in prominent histological changes in the bladder. The study provides an invaluable reference dataset for preclinical research on IC/BPS and an insight into the sex-specific mechanisms involved in the development of IC/BPS pathology, which may explain the more frequent occurrence of this disease in women.

TrkA inhibition alleviates bladder overactivity in cyclophosphamide-induced cystitis by targeting hyperpolarization-activated cyclic nucleotide-gated channels

Objectives

To investigate the potential of Tropomyosin receptor kinase A (TrkA) for the treatment of interstitial cystitis/ bladder pain syndrome (IC/BPS).

Materials and Methods

Sixty-four female rats were randomly assigned to the control and cyclophosphamide (CYP) groups. Quantitative reverse transcription polymerase chain reaction was utilized to detect the mRNA level of TrkA. Western blot analysis was used to measure the protein levels of TNF-α, IL-6, and TrkA. Immunostaining was used to detect the expression of TrkA in bladder sections. Contractility studies and urodynamic measurements were utilized to test the spontaneous contractions of detrusor muscle strips and the global bladder activity, respectively.

Results

Rat models of chronic cystitis were successfully established. The mRNA and protein levels of TrkA were significantly increased in the bladders of CYP-treated rats. Also, results of immunohistochemical staining and immunofluorescence staining showed that increased TrkA expression in the CYP group was mainly observed in the urothelium layer and bladder interstitial Cajal-like cells (ICC-LCs) but not in the detrusor smooth muscle cells. The specific inhibitor of TrkA, GW441756 (10 μM), significantly suppressed the robust spontaneous contractions of detrusor muscle strips in the CYP group and alleviated the overall bladder overactivity of CYP-treated rats. However, the inhibitory effects of GW441756 (10 μM) on the spontaneous contractions of detrusor muscle strips and the overall bladder activity were eliminated after pretreatments with the specific blocker of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, ZD7288 (50 μM).

Conclusion

Our results suggested that increased TrkA expression during chronic cystitis promotes the development of bladder overactivity by targeting the HCN channels.