Prevalence of autoimmune disorders among bladder pain syndrome patients' relatives

Causal role of common autoimmune diseases in interstitial cystitis/bladder pain syndrome: Mendelian randomization (MR) study

Observational studies suggest that interstitial cystitis/bladder pain syndrome (IC/BPS) indices might be influenced by autoimmune diseases (AIDs), though it is difficult to infer causal relationships based on observational data due to risk of residual confounding. We utilized Mendelian randomization (MR) to explore causal relevance of multiple AIDs on IC/BPS. Our bidirectional two-sample MR analysis was based on summary statistics from the most recent and comprehensive genome-wide association studies. This particular approach was used to delve into the relationships of cause and effect between IC/BPS and a group of 14 AIDs. We examined a range of AIDs such as ulcerative colitis, Crohn disease, celiac disease, Sjogren syndrome, rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, primary biliary cirrhosis, psoriasis, asthma, eczema, ankylosing spondylitis, type 1 diabetes, and primary sclerosing cholangitis. Our primary analytical approach involved using the inverse variance weighting method to establish causal relationships across various AIDs and IC/BPS conditions. Furthermore, we carried out additional examinations, such as utilizing the weighted median technique, MR-Egger regression, MR-PRESSO, and evaluating reverse causality, in order to strengthen the dependability of our results. Our findings indicate a strong association between genetically predicted asthma and the risk of developing IC/BPS with a weighted odds ratio of 1.692, a confidence interval of 1.147 to 2.496, and P = .008, while the Cochran Q test P = .589 and the MR-Egger intercept test P = .554, MR-PRESSO global test P = .600. No evidence was found for causal relationships between other AIDs and IC/BPS. Individuals with asthma show an increased vulnerability to IC/BPS according to our findings. More randomized controlled trials are necessary to validate these results. These results underscore the importance for healthcare providers to assess the potential risk in asthma patients, offering a novel genetic perspective on studying interstitial cystitis.

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.

Serum anandamide and lipids associated with linoleic acid can distinguish interstitial cystitis/bladder pain syndrome from overactive bladder: An exploratory study

OBJECTIVES

Diagnosing interstitial cystitis/bladder pain syndrome presents a major challenge because it relies on subjective symptoms and empirical cystoscopic findings. A practical biomarker should discriminate diseases that cause increased urinary frequency, particularly overactive bladder. Therefore, we aimed to identify blood biomarkers that can discriminate between interstitial cystitis/bladder pain syndrome and overactive bladder.

METHODS

We enrolled patients with Hunner-type interstitial cystitis (n = 20), bladder pain syndrome (n = 20), and overactive bladder (n = 20) and without lower urinary tract symptoms (controls, n = 15) at Ueda Clinic and Nara Medical University Hospital from February 2020 to August 2021. The degree of interstitial cystitis/bladder pain syndrome symptoms was evaluated using the interstitial cystitis symptom and problem indices. Metabolomics analysis was performed on 323 serum metabolites using liquid chromatography time-of-flight mass spectrometry.

RESULTS

In the Hunner-type interstitial cystitis or bladder pain syndrome group, we observed smaller relative areas, including anandamide, acylcarnitine (18:2), linoleoyl ethanolamide, and arachidonic acid, compared to those in the overactive bladder or control group. Notably, the differences in the relative areas of anandamide were statistically significant (median: 3.950e-005 and 4.150e-005 vs. 8.300e-005 and 9.800e-005), with an area under the curve of 0.9321, demonstrating its ability to discriminate interstitial cystitis/bladder pain syndrome.

CONCLUSIONS

Serum anandamide may be a feasible diagnostic biomarker for interstitial cystitis/bladder pain syndrome. Reduced serum anandamide levels may be associated with pain and inflammation initiation, reflecting the pathology of interstitial cystitis/bladder pain syndrome. Furthermore, our findings suggest that abnormal linoleic acid metabolism may be involved in the pathogenesis of interstitial cystitis/bladder pain syndrome.

[Interstitial cystitis: the latest findings on its aetiopathogenesis]

New findings provide progress in the understanding of the complicated aetiopathogenesis of interstitial cystitis/bladder pain syndrome (IC/BPS), whose causalities have only been deciphered in fragments so far. An increasingly complex network of pathomechanisms is emerging, in which the frequently mentioned mast cells and urothelial changes seem to be only a fragment of the pathological changes. The latest findings regarding a possible genetic and epigenetic predisposition are based on pedigree analyses, detection of single nucleotide polymorphisms and significant changes in differentially expressed genes. Multiple alterations can be detected at the molecular level. Platelet-activating factor, VEGF, corticotropin-releasing hormone and the inflammasome are important players in understanding the disease, but the pathomechanism underlying the "activation" of IC remains unclear. New starting points could be the detection of viruses (Epstein-Barr virus, BK polyomaviruses) or bacterial inflammation by pathogens that cannot be detected in standard cultures.

Biomarkers in the Light of the Etiopathology of IC/BPS

In this review, we focused on putatively interesting biomarkers of interstitial cystitis/bladder pain syndrome (IC/BPS) in relation to the etiopathology of this disease. Since its etiopathology is still under discussion, the development of novel biomarkers is critical for the correct classification of the patients in order to open personalized treatment options, on the one hand, and to separate true IC/BPS from the numerous confusable diseases with comparable symptom spectra on the other hand. There is growing evidence supporting the notion that the classical or Hunner-type IC (HIC) and the non-Hunner-type IC (NHIC) are different diseases with different etiopathologies and different pathophysiology at the full-blown state. While genetic alterations indicate close relationship to allergic and autoimmune diseases, at present, the genetic origin of IC/BPS could be identified. Disturbed angiogenesis and impairment of the microvessels could be linked to altered humoral signaling cascades leading to enhanced VEGF levels which in turn could enhance leucocyte and mast cell invasion. Recurrent or chronic urinary tract infection has been speculated to promote IC/BPS. New findings show that occult virus infections occurred in most IC/BPS patients and that the urinary microbiome was altered, supporting the hypothesis of infections as major players in IC/BPS. Environmental and nutritional factors may also influence IC/BPS, at least at a late state (e.g., cigarette smoking can enhance IC/BPS symptoms). The damage of the urothelial barrier could possibly be the result of many different causality chains and mark the final state of IC/BPS, the causes of this development having been introduced years ago. We conclude that the etiopathology of IC/BPS is complex, involving regulatory mechanisms at various levels. However, using novel molecular biologic techniques promise more sophisticated analysis of this pathophysiological network, resulting in a constantly improvement of our understanding of IC/BPS and related diseases.

Risk of Autoimmune Diseases in Patients With Interstitial Cystitis/Bladder Pain Syndrome: A Nationwide Population-Based Study in Taiwan

Objective: The association between autoimmune diseases (ADs) and interstitial cystitis/bladder pain syndrome (IC/BPS) has long been investigated. However, the lack of comprehensive descriptions of patients in the literature has made comparison and evaluation impossible. We aim to investigate the risk of systemic ADs in patients with IC/BPS in Taiwan using a population-based administrative database.

Methods: This study evaluated 1,095 patients newly diagnosed with IC/BPS between 2000 and 2013, using data from Taiwan's National Health Insurance Research Database. These patients were randomly matched by demographic characteristics with a comparison cohort of individuals without IC/BPS at a ratio of 1:20. Cox proportional hazards regression analysis was used to analyze the risk of ADs, adjusting for age, sex, urbanization, length of hospital stay, and comorbidities adjustment. Sensitivity analysis by propensity score was used to adjust for confounding factors.

Results: The adjusted Hazard Ratio (aHR) of ADs for IC/BPS patients was 1.409 (95% CI 1.152–1.725). The subgroup analysis indicated that female or 45–60 years of age had a greater risk of ADs. Furthermore, the subgroup analysis of primary outcomes indicated that IC/BPS had greater incidence with Hashimoto's thyroiditis (aHR = 2.767, 95% CI 1.039–7.368), ankylosing spondylitis (aHR = 2.429, 95% CI 1.264–4.67), rheumatoid arthritis (aHR = 1.516, 95% CI 1.001–2.296), and Sjogren's syndrome (aHR = 1.962, 95% CI 1.37–2.809).

Conclusion: IC/BPS was associated with the development of ADs in our study population, especially Hashimoto's thyroiditis, ankylosing spondylitis, rheumatoid arthritis, and Sjogren's syndrome. Clinicians are recommended to be alert to the increased likelihood of developing ADs, particularly for middle-aged women.