Hunner Lesion Interstitial Cystitis: The Bad, The Good, and The Unknown

Purine nucleoside phosphorylase as a target for the treatment of interstitial cystitis/bladder pain syndrome with and without Hunner lesions

Chronic visceral pain disorders, such as interstitial cystitis/bladder pain syndrome (IC/BPS), are difficult to treat, and therapies are limited in number and efficacy. Emerging evidence suggests that alterations in the enzyme purine nucleoside phosphorylase (PNPase) may participate in oxidative injury and cellular damage. PNPase is important for the metabolism of 'tissue-protective' purine metabolites to 'tissue-damaging' purines that generate free radicals. The aim of this study is to test whether patients living with IC/BPS without or with Hunner lesions and irrespective of any therapies exhibit purine dysregulation with higher levels of tissue-damaging purine metabolites as measured by liquid chromatography-tandem mass spectrometry. Our results demonstrate that levels of urotoxic purine metabolites (hypoxanthine and xanthine) in IC/BPS patients with and without Hunner lesions are elevated compared to healthy controls. These findings suggest there may be pathophysiologic commonalities between patient subtypes. Furthermore, the accumulation of uroprotective purines and depletion of urodamaging purines by PNPase inhibition may be therapeutically effective in both groups of patients.

Mendelian randomization study reveals causal effects of specific gut microbiota on the risk of interstitial cystitis/bladder pain syndrome (IC/BPS)

Evidence from previous studies have demonstrated that gut microbiota are closely associated with occurrence of interstitial cystitis/bladder pain syndrome (IC/BPS), yet the causal link between the two is not well known. In this study, we performed a two-sample Mendelian randomization (MR) analysis to determine the possible causal association between gut microbiota with IC/BPS. Gut microbiota summary level data were derived from the genome-wide association study (GWAS) conducted by MiBioGen and the IC/BPS GWAS summary level data were obtained from the GWAS Catalog. Next, we performed an MR study to investigate the causal link between gut microbiota and IC/BPS. The primary method for causal analysis was the inverse variance weighted (IVW), and the MR results were validated through multiple sensitivity analyses. A positive association was found between IC/BPS and eight gut microbial taxa, including genus Bacteroides, genus Haemophilus, genus Veillonella, genus Coprococcus1, genus Butyricimonas, family Bacteroidaceae, family Christensenellaceae, and order Lactobacillales. Sensitivity analysis revealed lack of significant pleiotropy or heterogeneity in the obtained results. This MR analysis reveals that a causal association exists between some gut microbiota with IC/BPS. This finding may is expected to guide future research and development of IC/BPS preventions and treatments based on the bladder-gut axis. However, given the clinical complexity and diagnostic challenges of IC/BPS, along with the limitations of using large-scale GWAS summary data for analysis, our MR results require further validation through additional research.

Quality of life analysis in bladder pain syndrome/interstitial cystitis: implications for a multimodal integrated treatment

BACKGROUND

The aim of this study was to evaluate whether there is a higher prevalence of anxiety-depressive disorders in women with BPS/IC (bladder pain syndrome/interstitial cystitis) than in women with chronic non-neoplastic pain with or without fibromyalgia, to examine possible correlations between urological and psychiatric symptoms.

METHODS

The patients included in the study were divided into two groups: 1) group 0: patients with an existing diagnosis of BPS/IC. BPS/IC was confirmed by reviewing medical record; group 1+2: patients with chronic non-neoplastic pain, suffering from fibromyalgia or other types of chronic pain (chronic arthralgia or lower back pain). Three questionnaires were administered: PHQ-9 to investigate psychological symptoms, O'Leary Saint (ICSI-ICPI) to investigate urological symptoms in women with BPS/IC and BPI to investigate specifically pain.

RESULTS

The survey included 69 patients, 42 patients had a diagnosis of BPS/IC while 27 of them had chronic non-neoplastic pain. The average PHQ-9 Score was 10.3 in BPS/IC group, considered as major depression (score between 10 and 14); the average score of PHQ-9 was 6.9 in group 1+2, as in sub-threshold depression (between 5-9).

CONCLUSIONS

The chronic pain of BPS/IC can affect mood more than in other painful conditions, as more than half of this population has a score that identifies depression with the PHQ-9 questionnaire, confirming the hypothesis that the syndrome is associated with a higher prevalence of an anxious-depressive condition.

Cystoscopy, an indispensable tool for the diagnosis and prognosis of bladder pain syndrome, takes nomograms for predicting recurrence

PURPOSE

We aimed to illustrate the importance of cystoscopy for the diagnosis and prognosis of bladder pain syndrome (BPS) or interstitial cystitis (IC).

METHODS AND MATERIALS

We designed a 4-year prospective follow-up study. Patients who underwent cystoscopy between May 2011 and July 2021 with a diagnosis of BPS/IC before surgery or positive cystoscopic findings during initial surgery at Peking University People's Hospital were enrolled. Data related to symptom recurrence were obtained through clinic visits and telephone follow-up. We compared the differences in clinical features of BPS/IC subtypes differentiated by cystoscopy and first created clinical predictive nomograms for BPS/IC.

RESULTS

A total of 141 patients were included. There was an 8.51% chance of BPS/IC being misdiagnosed as other diseases or other diseases being misdiagnosed as BPS/IC without cystoscopy. Patients with HIC had higher pain scores and ICPI, higher residual urine volume, lower first-sense-to-void, and maximum cystometric bladder capacities than NHIC. Nomogram Models showed that patients who with higher ICPI, ICSI and lower AMBC have a greater recurrence probability, and lesions in the trigone may indicate a greater likelihood of recurrence than lesions in other bladder walls.

CONCLUSIONS

Timely detection of bladder cancer and other diseases using cystoscopy can avoid poor treatment effects. BPS/IC subtypes can be classified according to mucosal changes under cystoscopy. Lesions in the bladder triangle can indicate a higher recurrence risk, which is important in follow-up treatment. We strongly recommend that cystoscopy should be included in the international BPS/IC diagnostic criteria.

Immunogenic Cell Death Associated Molecular Patterns and the Dual Role of IL17RA in Interstitial Cystitis/Bladder Pain Syndrome

The unclear etiology and pathogenesis of interstitial cystitis/bladder pain syndrome (IC/BPS) are responsible for the lack of effective treatment and the poor patient prognosis. Various studies show that chronic inflammation and immune responses are important factors contributing to the pathogenesis of IC/BPS. The process of immunogenic cell death (ICD) involves both the immune response and inflammatory process, and the involvement of ICD in IC/BPS pathogenesis has not been explored. Two IC/BPS transcriptome datasets collected from the Gene Expression Omnibus (GEO) database were used to identify distinct ICD-associated molecular patterns (IAMPs). IAMPs and IC/BPS subtypes were found to be related. The inflammatory immune microenvironments (IIME) in different IAMPs were studied. The potential mechanism by which the interleukin 17 receptor A (IL17RA) influences IC/BPS was examined using in vitro assays. The expression of ICD-related genes (IRGs) was upregulated in IC/BPS bladders, compared with normal bladders. Disease prediction models, based on differentially expressed IRGs, could accurately predict IC/BPS. The IC/BPS patients had two distinct IAMPs, each with its own subtype and clinical features and association with remodeling IIME. IL17RA, a well-established IC/BPS bladder biomarker, mediates both the inflammatory insult and the protective responses. In summary, the current study identified different IAMPs in IC/BPS, which may be involved in the pathogenesis of IC/BPS by remodeling the IIME. The chronic inflammatory process in IC/BPS may be prolonged by IL17RA, which could mediate both pro- and anti-inflammatory responses. The IL17RA-associated pathway may play a significant role in the development of IC/BPS and can be used as a therapeutic target.

Multimodal Single-Cell Analyses Outline the Immune Microenvironment and Therapeutic Effectors of Interstitial Cystitis/Bladder Pain Syndrome

Interstitial cystitis/bladder pain syndrome (IC/BPS) has a significant impact on quality of life, but the etiopathogenesis remains largely unknown. The bladder microenvironment of patients with IC/BPS to obtain biological evidence supporting diagnosis and novel therapy is systematically characterized. Single-cell RNA sequencing (scRNA-seq) and image mass cytometry (IMC) are applied to bladder biopsies of the IC/BPS cohort. A total of 42 distinct cell clusters are identified from different groups. The increased hyperactivated Th1-biased response, but not Th2-biased response, and decreased immunosuppressive Treg are elucidated in the bladder microenvironment of non-Hunner-type IC (NHIC)/Hunner-type IC (HIC). M2/M2-like macrophage extends in the HIC and M1-like macrophage extends in NHIC, all of which secrete a range of chemokines with different pattern. The pro-inflammatory mediators, TNF-α, produced by tissue-resident macrophages and IL6, by the inflammatory fibroblasts are identified as key mediators of IC/BPS pathogenesis. Additionally, a regulatory network between different cell types is observed as a shift from structural cell communication in unaffected normal bladder to a Macrophage-Endothelial-dominated interactome in NHIC/HIC. The results demonstrate the high heterogeneity in NHIC/HIC, and provide an essential resource for diagnosis, and treatment of IC/BPS in the future by highlighting the importance of the microenvironment of bladder mucosa.

Bladder Microbiome in the Context of Urological Disorders—Is There a Biomarker Potential for Interstitial Cystitis?

Since the development of modern cultivation and sequencing techniques, the human microbiome has increasingly become the focus of scientific attention. Even in the bladder, long considered to be a sterile niche, a highly variable and complex microbial colonization has now been demonstrated. Especially in the context of diseases such as interstitial cystitis, whose etiopathogenesis is largely unknown, and whose diagnosis is based on a process of exclusion of confusable diseases, science hopes to gain far-reaching insights for etiology and diagnosis, including the identification of potential biomarkers. While for functional disorders such as urge urinary incontinence and overactive bladder syndrome, initial associations have been demonstrated between reduced microbial diversity and increased symptomatology, as well as shifts in the abundance of specific microorganisms such as Lactobacillus or Proteus, studies in interstitial cystitis show conflicting results and have failed to identify a putative organism or urotype that clearly distinguishes the urinary microbiome of patients with IC/BPS from that of healthy controls. At the present time, therefore, the new insights into the bladder microbiome and its potential influence on urologic disease cannot yet be used in the context of elucidating possible etiopathogenetic causes, as well as in the use of a biomarker for diagnostic or prognostic purposes. Further studies should focus primarily on uniform procedures and detection methods to achieve better comparability of results and increase the likelihood of detecting hidden patterns.

Absence of prostacyclin greatly relieves cyclophosphamide-induced cystitis and bladder pain in mice

Cyclophosphamide (CP) has been widely used in the treatment of various malignancies and autoimmune diseases, but acrolein, a byproduct of CP, causes severe hemorrhagic cystitis as the major side effect of CP. On the other hand, a large amount of prostacyclin (PGI₂ ) is produced in bladder tissues, and PGI₂ has been shown to play a critical role in bladder homeostasis. PGI₂ is biosynthesized from prostaglandin (PG) H₂ , the common precursor of PGs, by PGI₂ synthase (PTGIS) and is known to also be involved in inflammatory responses. However, little is known about the roles of PTGIS-derived PGI₂ in bladder inflammation including CP-induced hemorrhagic cystitis. Using both genetic and pharmacological approaches, we here revealed that PTGIS-derived PGI₂ -IP (PGI₂ receptor) signaling exacerbated CP-induced bladder inflammatory reactions. Ptgis deficiency attenuated CP-induced vascular permeability and chemokine-mediated neutrophil migration into bladder tissues and then suppressed hemorrhagic cystitis. Treatment with RO1138452, an IP selective antagonist, also suppressed CP-induced cystitis. We further found that cystitis-related nociceptive behavior was also relieved in both Ptgis^-/- mice and RO1138452-treated mice. Our findings may provide new drug targets for bladder inflammation and inflammatory pain in CP-induced hemorrhagic cystitis.

The bacterial microbiota of Hunner lesion interstitial cystitis/bladder pain syndrome

OBJECTIVE

To undertake the first comprehensive evaluation of the urinary microbiota associated with Hunner lesion (HL) interstitial cystitis/bladder pain syndrome (IC/BPS). Despite no previous identification of a distinct IC/BPS microbial urotype, HL IC/BPS, an inflammatory subtype of IC/BPS, was hypothesized most likely to be associated with a specific bacterial species or microbial pattern.

PARTICIPANTS AND METHODS

The bacterial microbiota of midstream urine specimens from HL IC/BPS and age- and gender-matched IC/BPS patients without HL (non-HL IC/BPS) were examined using the pan-bacterial domain clinical-level molecular diagnostic Pacific Biosciences full-length 16S gene sequencing protocol, informatics pipeline and database. We characterized the differential presence, abundances, and diversity of species, as well as gender-specific differences between and among HL and non-HL IC/BPS patients.

RESULTS

A total of 59 patients with IC/BPS were enrolled (29 HL, 30 non-HL; 43 women, 16 men) from a single centre and the microbiota in midstream urine specimens was available for comparison. The species abundance differentiation between the HL and non-HL groups (12 species) was not significantly different after Bonferroni adjustments for multiple comparisons. Similarly, the nine differentiating species noted between female HL and non-HL patients were not significantly different after similar statistical correction. However, four species abundances (out of the 10 species differences identified prior to correction) remained significantly different between male HL and non-HL subjects: Negativicoccus succinivorans, Porphyromonas somerae, Mobiluncus curtisii and Corynebacterium renale. Shannon diversity metrics showed significantly higher diversity among HL male patients than HL female patients (P = 0.045), but no significant diversity differences between HL and non-HL patients overall.

CONCLUSIONS

We were not able to identify a unique pathogenic urinary microbiota that differentiates all HL from all non-HL IC/BPS. It is likely that the male-specific differences resulted from colonization/contamination remote from the bladder. We were not able to show that bacteria play an important role in patients with HL IC/BPS.