Urinary and Serologic Markers forInterstitial Cystitis: An Update

Feline Idiopathic Cystitis: Pathogenesis, Histopathology and Comparative Potential

Bladder pain syndrome (BPS) is a debilitating disease in humans, particularly women, with patients experiencing chronic, intractable, lower urinary and pelvic pain. Although rodent models have been used, feline idiopathic cystitis (FIC) is a naturally occurring bladder disease of cats that is frequently considered to be the preferred model for BPS. Histologically, FIC is most similar to the non-Hunner BPS subtype. Histology is unnecessary for the clinical diagnosis of FIC but is of great value in elucidating the pathogenesis of this disease so that prevention and therapeutic interventions can be optimized. Further study of the histological features of FIC and BPS is required to determine the significance of Von Brunn's nests, which are invaginations of hyperplastic urothelium that have been associated with irritative bladder stimuli in animals and have been observed in FIC. We review the possible pathogenesis, histopathological similarities and differences between FIC and BPS, and highlight the potential of FIC as a model of BPS.

Metabolomics in Central Sensitivity Syndromes

Central sensitization syndromes are a collection of frequently painful disorders that contribute to decreased quality of life and increased risk of opiate abuse. Although these disorders cause significant morbidity, they frequently lack reliable diagnostic tests. As such, technologies that can identify key moieties in central sensitization disorders may contribute to the identification of novel therapeutic targets and more precise treatment options. The analysis of small molecules in biological samples through metabolomics has improved greatly and may be the technology needed to identify key moieties in difficult to diagnose diseases. In this review, we discuss the current state of metabolomics as it relates to central sensitization disorders. From initial literature review until Feb 2020, PubMed, Embase, and Scopus were searched for applicable studies. We included cohort studies, case series, and interventional studies of both adults and children affected by central sensitivity syndromes. The majority of metabolomic studies addressing a CSS found significantly altered metabolites that allowed for differentiation of CSS patients from healthy controls. Therefore, the published literature overwhelmingly supports the use of metabolomics in CSS. Further research into these altered metabolites and their respective metabolic pathways may provide more reliable and effective therapeutics for these syndromes.

Implications for bidirectional signaling between afferent nerves and urothelial cells-ICI-RS 2014

AIMS

To present a synopsis of the presentations and discussions from Think Tank I, "Implications for afferent-urothelial bidirectional communication" of the 2014 International Consultation on Incontinence-Research Society (ICI-RS) meeting in Bristol, UK.

METHODS

The participants presented what is new, currently understood or still unknown on afferent-urothelial signaling mechanisms. New avenues of research and experimental methodologies that are or could be employed were presented and discussed.

RESULTS

It is clear that afferent-urothelial interactions are integral to the regulation of normal bladder function and that its disruption can have detrimental consequences. The urothelium is capable of releasing numerous signaling factors that can affect sensory neurons innervating the suburothelium. However, the understanding of how factors released from urothelial cells and afferent nerve terminals regulate one another is incomplete. Utilization of techniques such as viruses that genetically encode Ca(2+) sensors, based on calmodulin and green fluorescent protein, has helped to address the cellular mechanisms involved. Additionally, the epithelial-neuronal interactions in the urethra may also play a significant role in lower urinary tract regulation and merit further investigation.

CONCLUSION

The signaling capabilities of the urothelium and afferent nerves are well documented, yet how these signals are integrated to regulate bladder function is unclear. There is unquestionably a need for expanded methodologies to further our understanding of lower urinary tract sensory mechanisms and their contribution to various pathologies.

Pathomechanism of Interstitial Cystitis/Bladder Pain Syndrome and Mapping the Heterogeneity of Disease

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a heterogeneous syndrome which is usually characterized by urinary frequency, nocturia, and bladder pain. Several pathomechanisms have been proposed, including uroepithelial dysfunction, mast cell activation, neurogenic inflammation, autoimmunity, and occult urinary tract infections. It is possible that an inflammatory process alters regulation of urothelial homeostasis and results in dysfunction of the bladder epithelium. Different phenotypes of IC/BPS have been explored including Hunner and non-Hunner type IC, hypersensitive bladder, and bladder pain both with and without functional somatic syndrome. Different gene expressions have also been found in different IC phenotypes. Abnormal expressions of uroplakin, chondroitin sulfate and adhesive protein E-cadherin, tight junction protein zonula occludens-1 in IC/BPS bladder suggest abnormal epithelial differentiation in this bladder disease. Analysis of inflammatory proteins, or cytokines in the urine or serum provides another diagnostic foundation forIC/BPS subtypes. The involvement of IC/BPS in systemic functional somatic syndrome and other pelvic organ diseases might also subdivide subtypes of IC/BPS. Chronic inflammation, increased urothelial apoptosis, and abnormal urothelial function are closely associated in IC bladders. This article reviews recent research on the pathomechanisms of IC, which might help us in mapping the heterogeneity of the disease.

The Challenges of Interstitial Cystitis: Current Status and Future Prospects

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a syndrome of unpleasant bladder sensations and lower urinary tract symptoms. The three main proposed etiologies are bladder urothelial dysfunction, bladder inflammation (possible neurogenic), and neuropathic pain. Despite decades of basic and clinical research, IC/BPS remains difficult to treat. A variety of treatments are used, each aimed towards one etiology. For example, glycosaminoglycans are thought to improve the urothelial permeability barrier, anti-inflammatory agents are used to decrease general inflammation, and mast cell stabilizers and/or antagonists of mast cell products are used in the treatment of neurogenic inflammation. In the (unfortunately frequent) event that a treatment fails, possible reasons are that (1) the clinician is aiming towards the wrong etiology for that patient (i.e., the treatment is off target) or (2) the correct etiology is being targeted, but the treatment is not ameliorating it (i.e., the treatment is sub-therapeutic). This is a crucial distinction, because an off-target treatment should be abandoned, but a sub-therapeutic treatment should be escalated. Currently, our inability to make this crucial distinction is the greatest obstacle to effective treatment. An important future advance would be to identify urine or serum biomarkers specific to each etiologic target. Then, each biomarker could be used to select appropriate patients for each treatment and monitor the treatment's effect on its intended target.

Clinical guidelines for interstitial cystitis and hypersensitive bladder updated in 2015

Clinical guidelines for interstitial cystitis and hypersensitive bladder have been updated as of 2015. The guidelines define interstitial cystitis by the presence of hypersensitive bladder symptoms (discomfort, pressure or pain in the bladder usually associated with urinary frequency and nocturia) and bladder pathology, after excluding other diseases explaining symptoms. Interstitial cystitis is further classified by bladder pathology; either Hunner type interstitial cystitis with Hunner lesions or non-Hunner type interstitial cystitis with mucosal bleeding after distension in the absence of Hunner lesions. Hypersensitive bladder refers to a condition, where hypersensitive bladder symptoms are present, but bladder pathology or other explainable diseases are unproven. Interstitial cystitis and hypersensitive bladder severely affect patients' quality of life as a result of disabling symptoms and/or comorbidities. Reported prevalence suggestive of these disorders varies greatly from 0.01% to >6%. Pathophysiology would be an interaction of multiple factors including urothelial dysfunction, inflammation, neural hyperactivity, exogenous substances and extrabladder disorders. Definite diagnosis of interstitial cystitis and hypersensitive bladder requires cystoscopy with or without hydrodistension. Most of the therapeutic options lack a high level of evidence, leaving a few as recommended therapeutic options.

Potential urine and serum biomarkers for patients with bladder pain syndrome/interstitial cystitis

There is a lack of consensus on the pathophysiology of bladder pain syndrome/interstitial cystitis. The chronic pain symptoms of bladder pain syndrome/interstitial cystitis refractory to local treatment could be a result of central nervous system sensitization and persisting abnormalities in the bladder wall, which activate the afferent sensory system. Evidence also shows that bladder pain syndrome/interstitial cystitis is a heterogeneous syndrome and that the two subtypes, the ulcerative (classic) and non-ulcerative types, represent different disease entities. There is a need for non-invasive markers for the differential diagnoses of the subtypes of bladder pain syndrome/interstitial cystitis, and between bladder pain syndrome/interstitial cystitis and bladder sensory disorders, such as hypersensitive bladder syndrome or overactive bladder. Bladder pain syndrome/interstitial cystitis, but not overactive bladder, involves an aberrant differentiation program in the bladder urothelium that leads to altered synthesis of several proteoglycans, cell adhesion and tight junction proteins, and bacterial defense molecules. These findings have led to the rationale for identifying urinary biomarkers to detect bladder pain syndrome/interstitial cystitis in patients with frequency urgency syndrome. Recently, the markers that have been the focus of the most research are antiproliferative factor, epidermal growth factor, heparin-binding epidermal growth factor, glycosaminoglycans and bladder nitric oxide. In addition, inflammatory proteins in the urine and serum play important roles in the pathogenesis of bladder pain syndrome/interstitial cystitis. The urinary proteome is an easily accessible source of biomarkers for differentiation between inflammatory bladder disorders. Analysis of multiple urinary proteins and serum cytokines could provide a diagnostic basis for bladder pain syndrome/interstitial cystitis, and could be a tool for the differential diagnosis of bladder pain syndrome/interstitial cystitis and other sensory bladder disorders.

Increased pro-inflammatory cytokines, C-reactive protein and nerve growth factor expressions in serum of patients with interstitial cystitis/bladder pain syndrome

Objective

The etiology and pathogenesis of interstitial cystitis/bladder pain syndrome (IC/BPS) are unclear. Chronic inflammation is considered the main pathology of IC/BPS. This study measured the serum c-reactive protein (CRP), nerve growth factor (NGF) and pro-inflammatory cytokine/chemokine interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, and IL-8 expression in patients with IC/BPS to elucidate the involvement of systemic inflammation in IC/BPS.

Methods

Serum samples were collected from 30 IC/BPS patients and 26 control subjects. The concentrations of serum nerve growth factor (NGF), IL-1β, IL-6, TNF-α, and IL-8 were quantified using a bead-based, human serum adipokine panel kit. Serum C-reactive protein (CRP) was also assessed. Differences of serum CRP, NGF, IL-1β, IL-6, TNF-α, and IL-8 levels between the IC/BPS patients and controls were compared, and correlations between CRP and pro-inflammatory cytokines and chemokine were also evaluated.

Results

The results showed that CRP level (p = 0.031), NGF (p = 0.015) and pro-inflammatory cytokines/chemokine IL-1β, IL-6, TNF-α, and IL-8 levels were significantly higher in the patients with IC/BPS than among controls (all p<0.001). Significant associations were observed between IL-1β and IL-8 (p<0.001), IL-6 and CRP (p = 0.01), IL-6 and IL-8 (p = 0.02), and IL-6 and TNF-α (p = 0.03).

Conclusion

Increased pro-inflammatory cytokines/chemokine (IL-1β, IL-6, TNF-α, and IL-8) expression in the sera of IC/BPS patients implies not only mast cell activation, but also that other inflammatory mediators play important roles in the pathogenesis of IC/BPS. Thus, for some patients, IC/BPS is considered a chronic inflammatory disease.

A candidate serum biomarker for bladder pain syndrome/interstitial cystitis

Reliable diagnostic markers for Bladder Pain Syndrome/Interstitial Cystitis (IC) currently are not available. This study evaluated the feasibility of diagnosing IC in humans and domestic cats from the spectra of dried serum films (DSFs) using infrared microspectroscopy. Spectra were obtained from films from 29 humans and 34 domestic cats to create classification models using Soft Independent Modeling by Class Analogy (SIMCA). Ultrafiltration of serum improved discrimination capability. The classification models for both species successfully classified spectra based on condition (healthy/sick), and a different set of masked spectra correctly predicted the condition of 100% of the subjects. Classification required information from the 1500-1800 cm(-1) spectral region to discriminate between subjects with IC, other disorders, and healthy subjects. Analysis of cat samples using liquid chromatography-mass spectroscopy revealed differences in the concentration of tryptophan and its metabolites between healthy and affected cats. These results demonstrate the potential utility of infrared microspectroscopy to diagnose IC in both humans and cats.

Quantitative determination and comparison of the glycosaminoglycan Delta-disaccharide composition in 22 different human cell lines

Changes in proteoglycan and glycosaminoglycan (GAG) content and distribution may play an important role in the development of many diseases, atherosclerosis, cancer and diabetes. Human cell lines act as models for the underlying pathomechanisms. Despite the importance of proteoglycans for cell functioning, information on the GAG composition of most human cell lines is limited. Comparative analysis of the GAG Deltadisaccharide amount in 22 human cell lines yielded a mean value of 94 +/- 58 pmol/10(6) cells (mean+/-SEM). Total GAG amount and heparan sulfate/heparin Deltadisaccharide composition, but not chondroitin sulfate/dermatan sulfate Deltadisaccharide composition, differed significantly between the investigated adherent and suspension cell lines. We provide a novel overview of GAG Deltadisaccharide composition in 22 different human cell lines.

Increased concentration of neutrophil elastase in urine from patients with interstitial cystitis

OBJECTIVE

To identify proteins associated with interstitial cystitis (IC), protein profiles were analyzed using a proteomics-based approach. The study tested whether neutrophil elastase in urine correlates with the symptomatic condition of IC.

MATERIAL AND METHODS

Proteins in urine from IC patients and healthy subjects were analyzed through a comparative proteomics approach using two-dimensional difference in-gel electrophoresis and nano-liquid chromatography-tandem mass spectrometry. Neutrophil elastase activity was measured by the digestion of peptide substrate.

RESULTS

The urinary neutrophil elastase concentration was significantly higher in IC patients with pain than in healthy subjects. It was significantly increased in patients with small bladder capacity (median 6.31 ng/ml in IC with a bladder capacity < 200 ml vs 1.15 ng/ml in IC with a bladder capacity > or = 200 ml and 0.18 ng/ml in healthy bladders, p < 0.01). The concentration of neutrophil elastase did not correlate with the neutrophil count in the urine of IC patients.

CONCLUSION

The concentration of neutrophil elastase increased in the urine of the IC patient subset with bladder pain and small bladder capacity.

Interstitial cystitis: bladder pain and beyond

BACKGROUND

Interstitial cystitis is characterized by over 6 months of chronic pain, pressure and discomfort felt in the lower pelvis or bladder. It is often relieved with voiding, along with daytime frequency and nocturia in the absence of a urinary tract infection. Interstitial cystitis occurs primarily in females including adolescents and its diagnosis is still one of exclusion. It is now recognized as a serious medical condition associated with significant disability.

OBJECTIVE

The aim of this paper was to review the pathogenesis and treatment of interstitial cystitis with emphasis on new pathogenetic trends and therapeutic modalities.

METHODS

About 713 mostly original papers were reviewed in Medline from 1990 to August. 2008. All authors independently reviewed the literature. Large, double-blind, placebo-controlled, clinical trials were few and the medical histories of the patients used varied considerably making conclusions difficult. Promising pilot trials turned out mostly negative on follow-up.

RESULTS

Increasing evidence of co-morbid diseases, neurogenic inflammation and the effect of stress are promising as new targets for pathophysiology. No new effective treatments have emerged. Oral pentosanpolysulfate, amitriptyline, hydroxyzine and quercetin, as well as intravesical heparin/bicarbonate/lidocaine solutions, are still used with variable success. Some pilot open-label trials presented encouraging findings.

CONCLUSION

Interstitial cystitis contributes substantially to chronic pelvic pain and to poor quality of life. Oral or intravesical administration of solutions containing sodium hyaluronate, chondroitin sulfate and quercetin to both reduce bladder inflammation and 'replenish' the glycosaminoglycan layer should be tried. There is a clear need for therapeutic modalities. New potential translational research areas are suggested.

The xylosyltransferase Iota gene polymorphism c.343G>T (p.A115S) is associated with decreased serum glycosaminoglycan levels

OBJECTIVES

The xylosyltransferases I and II (XT-I, XT-II, EC 2.4.2.26) are the chain-initiating enzymes in the biosynthesis of glycosaminoglycans (GAGs). This is the first investigation of changes in the serum GAG amount and composition in association with polymorphisms in XYLT1 and XYLT2.

DESIGN AND METHODS

Genotyping of three genetic variations in the genes XYLT1 and XYLT2 was performed in 223 healthy blood donor samples. Serum samples were analyzed for their GAG Delta-disaccharide content by reversed-phase high-performance liquid chromatography (RP-HPLC). Furthermore serum XT activity was determined by a radiochemical assay.

RESULTS

The single nucleotide polymorphism (SNP) c.343G>T in XYLT1 exon 1 correlated with a significantly decreased GAG content in the serum (p<0.01). For the other two investigated XYLT2 variations (c.166G>A in exon 2 and c.1253C>T in exon 6) no changes in the serum GAG amount were detected. No investigated SNPs were associated with changes to serum XT activities.

CONCLUSIONS

The XYLT1 SNP c.343G>T is associated with a decreased GAG amount in the serum of healthy blood donors.