Urinology Think Tank Writing Group. Urine: Waste product or biologically active tissue?

Metabolic Syndrome and Overactive Bladder Syndrome May Share Common Pathophysiologies

Metabolic syndrome (MetS) is defined by a group of cardiovascular risk factors, including impaired glucose tolerance, central obesity, hypertension, and dyslipidemia. Overactive bladder (OAB) syndrome consists of symptoms such as urinary urgency, frequency, and nocturia with or without urge incontinence. The high prevalences of metabolic syndrome (MetS) and overactive bladder (OAB) worldwide affect quality of life and cause profound negative impacts on the social economy. Accumulated evidence suggests that MetS might contribute to the underlying mechanisms for developing OAB, and MetS-associated OAB could be a subtype of OAB. However, how could these two syndromes interact with each other? Based on results of animal studies and observations in epidemiological studies, we summarized the common pathophysiologies existing between MetS and OAB, including autonomic and peripheral neuropathies, chronic ischemia, proinflammatory status, dysregulation of nutrient-sensing pathways (e.g., insulin resistance at the bladder mucosa and excessive succinate intake), and the probable role of dysbiosis. Since the MetS-associated OAB is a subtype of OAB with distinctive pathophysiologies, the regular and non-specific medications, such as antimuscarinics, beta-3 agonist, and botulinum toxin injection, might lead to unsatisfying results. Understanding the pathophysiologies of MetS-associated OAB might benefit future studies exploring novel biomarkers for diagnosis and therapeutic targets on both MetS and OAB.

Urothelial Calcium-Sensing Receptor Modulates Micturition Function via Mediating Detrusor Activity and Ameliorates Bladder Hyperactivity in Rats

The urothelium displays mechano- and chemosensory functions via numerous receptors and channels. The calcium-sensing receptor (CaSR) detects extracellular calcium and modulates several physiological functions. Nonetheless, information about the expression and the role of CaSR in lower urinary tract has been absent. We aimed to determine the existence of urothelial CaSR in urinary bladder and its effect on micturition function. We utilized Western blot to confirm the expression of CaSR in bladder and used immunofluorescence to verify the location of the CaSR in the bladder urothelium via colocalization with uroplakin III A. The activation of urothelial CaSR via the CaSR agonist, AC-265347 (AC), decreased urinary bladder smooth muscle (detrusor) activity, whereas its inhibition via the CaSR antagonist, NPS-2143 hydrochloride (NPS), increased detrusor activity in in vitro myography experiments. Cystometry, bladder nerve activities recording, and bladder surface microcirculation detection were conducted to evaluate the effects of the urothelial CaSR via intravesical administrations. Intravesical AC inhibited micturition reflex, bladder afferent and efferent nerve activities, and reversed cystitis-induced bladder hyperactivity. The urothelial CaSR demonstrated a chemosensory function, and modulated micturition reflex via regulating detrusor activity. This study provided further evidence of how the urothelial CaSR mediated micturition and implicated the urothelial CaSR as a potential pharmacotherapeutic target in the intervention of bladder disorders.

Metabolomic Profiling of Human Urine Samples Using LC-TIMS-QTOF Mass Spectrometry

The identification of metabolites in biological samples is challenging due to their chemical and structural diversity. Ion mobility spectrometry (IMS) separates ionized molecules based on their mobility in a carrier buffer gas giving information about the ionic shape by measuring the rotationally averaged collision cross-section (CCS) value. This orthogonal descriptor, in combination with the m/z, isotopic pattern distribution, and MS/MS spectrum, has the potential to improve the identification of molecular molecules in complex mixtures. Urine metabolomics can reveal metabolic differences, which arise as a result of a specific disease or in response to therapeutic intervention. It is, however, complicated by the presence of metabolic breakdown products derived from a wide range of lifestyle and diet-related byproducts, many of which are poorly characterized. In this study, we explore the use of trapped ion mobility spectrometry (TIMS) via LC parallel accumulation with serial fragmentation (PASEF) for urine metabolomics. A total of 362 urine metabolites were characterized from 80 urine samples collected from healthy volunteers using untargeted metabolomics employing HILIC and RP chromatography. Additionally, three analytes (Trp, Phe, and Tyr) were selected for targeted quantification. Both the untargeted and targeted data was highly reproducible and reported CCS measurements for identified metabolites were robust in the presence of the urine matrix. A comparison of CCS values among different laboratories was also conducted, showing less than 1.3% ΔCCS values across different platforms. This is the first report of a human urine metabolite database compiled with CCS values experimentally acquired using an LC-PASEF TIMS-qTOF platform.

Comparing Metabolomics Profiles in Various Types of Liquid Biopsies among Screening Participants with and without Advanced Colorectal Neoplasms

Analysis of metabolomics has been suggested as a promising approach for early detection of colorectal cancer and advanced adenomas. We investigated and compared the metabolomics profile in blood, stool, and urine samples of screening colonoscopy participants and aimed to evaluate differences in metabolite concentrations between people with advanced colorectal neoplasms and those without neoplasms. Various types of bio-samples (plasma, feces, and urine) from 400 participants of screening colonoscopy were investigated using the MxP® Quant 500 kit (Biocrates, Innsbruck, Austria). We detected a broad range of metabolites in blood, stool, and urine samples (504, 331, and 131, respectively). Significant correlations were found between concentrations in blood and stool, blood and urine, and stool and urine for 93, 154, and 102 metabolites, of which 68 (73%), 126 (82%), and 39 (38%) were positive correlations. We found significant differences between participants with and without advanced colorectal neoplasms for concentrations of 123, 49, and 28 metabolites in blood, stool and urine samples, respectively. We detected mostly positive correlations between metabolite concentrations in blood samples and urine or stool samples, and mostly negative correlations between urine and stool samples. Differences between subjects with and without advanced colorectal neoplasms were found for metabolite concentrations in each of the three bio-fluids.

Classification of the urinary metabolome using machine learning and potential applications to diagnosing interstitial cystitis

With the advent of artificial intelligence (AI) in biostatistical analysis and modeling, machine learning can potentially be applied into developing diagnostic models for interstitial cystitis (IC). In the current clinical setting, urologists are dependent on cystoscopy and questionnaire-based decisions to diagnose IC. This is a result of a lack of objective diagnostic molecular biomarkers. The purpose of this study was to develop a machine learning-based method for diagnosing IC and assess its performance using metabolomics profiles obtained from a prior study. To develop the machine learning algorithm, two classification methods, support vector machine (SVM) and logistic regression (LR), set at various parameters, were applied to 43 IC patients and 16 healthy controls. There were 3 measures used in this study, accuracy, precision (positive predictive value), and recall (sensitivity). Individual precision and recall (PR) curves were drafted. Since the sample size was relatively small, complicated deep learning could not be done. We achieved a 76%–86% accuracy with leave-one-out cross validation depending on the method and parameters set. The highest accuracy achieved was 86.4% using SVM with a polynomial kernel degree set to 5, but a larger area under the curve (AUC) from the PR curve was achieved using LR with a l₁-norm regularizer. The AUC was greater than 0.9 in its ability to discriminate IC patients from controls, suggesting that the algorithm works well in identifying IC, even when there is a class distribution imbalance between the IC and control samples. This finding provides further insight into utilizing previously identified urinary metabolic biomarkers in developing machine learning algorithms that can be applied in the clinical setting.

Extracellular vesicles enhance oxidative stress through P38/NF-kB pathway in ketamine-induced ulcerative cystitis

Long‐term abuse of ketamine causes ketamine‐induced cystitis. The functional alterations of bladder epithelial cells in microenvironment during cystitis remain poorly understood. Here, we explored extracellular vesicles (EV) alteration in ketamine‐induced toxicity. To simulate the high‐concentration ketamine environment in vivo, we established an in vitro model of high ketamine using human uroepithelial cells (SV‐HUC‐1). Cell viability and proliferation were assessed to evaluate the effects of various concentrations (0, 0.25, 0.5, 1, 2, 4 and 8 mmol/L) of ketamine on SV‐HUC‐1 cells. The cell supernatant cultured at a concentration (0, 1, 2, 4 mmol/L) of ketamine was selected for EV extraction and identified. Subsequently, we assessed different groups (ketamine, ketamine plus EV blocker, EV, EV plus extracellular vesicles blocker) of oxidative stress and expression of inflammation. Last, luciferase reporter assay was performed to study the transcriptional regulation of EV on the NF‐kB and P38 pathway. The results of our study suggested that treatment with 0, 1, 2 or 4 mmol/L ketamine altered the morphology and secretion capacity of extracellular vesicles. As the concentration of ketamine increased, the average particle size of EV decreased, but the crest size, particle concentration and EV protein increased. Moreover, after the addition of EV blocker, EV secreted at different concentrations were blocked outside the cell membrane, and the degree of oxidative stress decreased. Our study provided evidence that ketamine alters the secretion of EV by directly stimulating cells in inflammation microenvironment and EV play significant roles in intercellular signal communication and the formation of KIC.EV

Urine Proteomic Study in OAB Patients-Preliminary Report

Overactive bladder (OAB) is defined by International Urogynecological Association (IUGA)/ International Continence Society (ICS) as urinary urgency, usually accompanied by frequency and nocturia, with or without urgency urinary incontinence, in the absence of urinary tract infection (UTI) or other obvious pathology. The pathophysiology of OAB is not well understood, however a number of different proteins and cytokines including vascular cell adhesion molecule-1 (VCAM-1) were found to be important in regulating structural integrity of the bladder wall. Proteome analysis may thus provide significant information with regard to OAB and may help in discovering novel diagnostic disease biomarkers. Sixteen Caucasian women aged 32-78 were included in the study. Patients were placed within 2 groups: OAB group (n = 8) and control group (n = 8). Urine samples were collected, immediately preserved in a protease inhibitor mixture, and frozen at -80 ℃. All samples were then further processed according to the isobaric tags for relative and absolute quantification (iTRAQ) manual. Proteins were labeled and analyzed in the mass spectrometer conjugated with liquid chromatograph (data are available via ProteomeXchange with the identifier PXD017799). There were no statistically significant differences in demographic data between control and OAB groups. VCAM-1 was the only protein that reached statistical significance as a differentiating protein in both of our experiments assessing the proteomic constitution in OAB patients. Studies involving a larger group of patients may provide further information on urinary bladder proteomics.

Terminology for bladder health research in women and girls: Prevention of Lower Urinary Tract Symptoms transdisciplinary consortium definitions

AIM

To report research terminology and definitions for describing healthy bladder function among women and girls.

METHODS

The Prevention of Lower Urinary tract Symptoms (PLUS) Consortium developed research terminology and definitions for elements of healthy bladder function based on existing understanding of storage and emptying functions of the bladder and accepted definitions of lower urinary tract symptoms (LUTS). The novel concept of a bladder "bioregulatory" function was also proposed. Elements of bladder function corresponding to bladder health (BH) and LUTS were developed and refined using an iterative process. A comprehensive reference table structured by bladder function (Storage, Emptying, and Bioregulatory) and elements of each function was created to document proposed research terminology and definitions.

RESULTS

The BH research definitions for each bladder function are: (1) Storage: the ability to hold urine for a reasonable duration of time and sense bladder fullness without fear of or concern about urgency, discomfort or leakage; (2) Emptying: the ability to empty the bladder completely in a timely, efficient, effortless, comfortable manner; and (3) Bioregulatory: the bladder barrier protects the individual/host from pathogens, chemicals, and malignancy. Research definitions for seven Storage, seven Emptying, and three Bioregulatory elements of function are presented. Novel LUTS research definitions were developed when gaps in existing definitions were identified or nonclinical language was desired.

CONCLUSIONS

PLUS BH definitions reflect a transdisciplinary approach to standardizing research definitions for elements of bladder function from a perspective of health rather than dysfunction and provide a framework for studying BH in clinical practice, public health promotion, and LUTS prevention.

Role of NLRP3 inflammasome in the development of bladder pain syndrome interstitial cystitis

Although it has been proposed that NOD-like receptor protein 3 (NLRP3) inflammasome activation may have an important contribution to the onset of bladder pain syndrome/interstitial cystitis (BPS/IC), as of today there is still insufficient evidence to accept or to reject this hypothesis. However, taking into consideration that inflammasomes have been already shown as important mediators of cyclophosphamide-induced bladder inflammation and that some studies have also revealed human bladder epithelium expresses high levels of NLRP3, such a hypothesis seems to be reasonable. The purpose of this review is to discuss a scenario that NLRP3 inflammasome is a crucial player in the development of this disease. Identification of a novel mediator of bladder inflammation and pain could lead to emerging new therapeutic strategy and the first causative therapy.