A pilot study to investigate the associations of urinary concentrations of NO, ATP and derivatives with overactive bladder symptom severity.

NEW FINDINGS: What is the central question of this study? Are the urinary concentrations of NO and ATP, and their metabolites, associated with the severity of symptoms of overactive bladder? What is the main finding and its importance? The urinary ratios of [ATP/NO], [ADP/NO] and a combination of these, [ATP/Cr*ADP/Cr]/[NO/Cr], were correlated with overall OAB symptom severity, with the latter combination also being correlated with the severity of urinary frequency and urgency symptoms individually. Together, these data reveal changes in urothelial signalling that accompany the transition from physiology to pathology. ABSTRACT: Overactive bladder (OAB) is a highly prevalent symptom complex characterized by symptoms of urinary urgency and increased frequency and waking to void (nocturia), with or without urge incontinence and in the absence of proven infection or other obvious pathology. The underlying pathophysiology of idiopathic OAB is not clearly known, and the existence of several phenotypes has been proposed. Current diagnostic approaches are based on discordant measures, suffer from subjectivity and are incapable of detecting the proposed OAB phenotypes. Nitric oxide, ATP and their metabolites have previously been shown to underlie the perception of bladder fullness, with their release modifying the pathological perception of urgency. Therefore, in this study we assessed the concentrations of NO, ATP and associated metabolites in the urine of 113 consenting participants recruited from the general population. Recruited participants completed a questionnaire to measure the severity of OAB-associated urinary symptoms and provided a mid-stream urine sample. After identification of infection and haematuria using microbiology and microscopy, 95 samples were subjected to assays to measure NO, NO2- , NO3- , ATP, ADP and creatinine (Cr). There was no correlation between [NO/Cr], [NO2- /Cr] or [NO3- /Cr] and overall OAB symptom severity. In contrast, [ATP/NO], [ADP/NO] and a combination of these, [ATP/Cr*ADP/Cr]/[NO/Cr], were correlated with OAB symptom severity, and [ATP/Cr*ADP/Cr]/[NO/Cr] was also correlated with the severity of urinary frequency and urgency. This study adds to a growing literature that demonstrates the potential of urinary biomarkers and provides a foundation for a larger, longitudinal study.

New participant stratification and combination of urinary biomarkers and confounders could improve diagnostic accuracy for overactive bladder.

Overactive bladder (OAB) is a highly prevalent symptom complex characterised by symptoms of urinary urgency, increased frequency, nocturia, with or without urge incontinence; in the absence of proven infection or other obvious pathology. The underlying pathophysiology of idiopathic OAB is not clearly known and the existence of several phenotypes has been proposed. Current diagnostic approaches are based on discordant measures, suffer from subjectivity and are incapable of detecting the proposed OAB phenotypes. In this study, cluster analysis was used as an objective approach for phenotyping participants based on their OAB characteristic symptoms and led to the identification of a low OAB symptomatic score group (cluster 1) and a high OAB symptomatic score group (cluster 2). Furthermore, the ability of several potential OAB urinary biomarkers including ATP, ACh, nitrite, MCP-1 and IL-5 and participants' confounders, age and gender, in predicting the identified high OAB symptomatic score group was assessed. A combination of urinary ATP and IL-5 plus age and gender was shown to have clinically acceptable and improved diagnostic accuracy compared to urodynamically-observed detrusor overactivity. Therefore, this study provides the foundation for the development of novel non-invasive diagnostic tools for OAB phenotypes that may lead to personalised treatment.

Investigating the associations of mucosal P2Y6 receptor expression and urinary ATP and ADP concentrations, with symptoms of overactive bladder.

AIM: To characterize purinergic signaling in overactive bladder (OAB). METHODS: Mucosal biopsies were taken by flexible cystoscopy from patients with storage symptoms referred to Urology Departments of collaborating hospitals. Immunohistochemistry (n = 12) and Western blot analysis (n = 28) were used to establish the qualitative and quantitative expression profile of P2Y6 in human mucosa. Participants from the general population provided a mid-stream urine sample. Bioluminescent assays were used to quantify adenosine triphosphate (ATP; n = 66) and adenosine diphosphate (ADP; n = 60) concentrations, which were normalized to creatinine (Cr) concentration. All participants completed a questionnaire (International Consultation on Incontinence Questionnaire - Overactive Bladder) to score urinary symptoms of OAB. RESULTS: P2Y6 immunoreactivity, more prominent in the urothelium (colocalized with the uroepithelial marker pan-cytokeratin), was more greatly expressed in OAB compared to age- and sex-matched controls (benign prostatic hyperplasia) without OAB symptoms. Mucosal P2Y6 was positively correlated only with incontinence (P = .009). Both urinary ATP and its hydrolysis product, ADP, an agonist to P2Y6, were positively correlated with total OAB symptom score (P = .010 and P = .042, respectively). CONCLUSIONS: The positive correlation of P2Y6 only with incontinence may indicate a different phenotype in OAB wet and warrants further investigation. Positive correlations of ATP and ADP with total OAB symptom score demonstrate upregulation in purinergic signaling in OAB; shown previously only in animal models. Further research is required to validate whether purinoceptors are indeed new therapeutic targets for this highly prevalent symptom complex.

Evolutionary, ecological and biotechnological perspectives on plasmids resident in the human gut mobile metagenome.

Numerous mobile genetic elements (MGE) are associated with the human gut microbiota and collectively referred to as the gut mobile metagenome. The role of this flexible gene pool in development and functioning of the gut microbial community remains largely unexplored, yet recent evidence suggests that at least some MGE comprising this fraction of the gut microbiome reflect the co-evolution of host and microbe in the gastro-intestinal tract. In conjunction, the high level of novel gene content typical of MGE coupled with their predicted high diversity, suggests that the mobile metagenome constitutes an immense and largely unexplored gene-space likely to encode many novel activities with potential biotechnological or pharmaceutical value, as well as being important to the development and functioning of the gut microbiota. Of the various types of MGE that comprise the gut mobile metagenome, plasmids are of particular importance since these elements are often capable of autonomous transfer between disparate bacterial species, and are known to encode accessory functions that increase bacterial fitness in a given environment facilitating bacterial adaptation. In this article current knowledge regarding plasmids resident in the human gut mobile metagenome is reviewed, and available strategies to access and characterize this portion of the gut microbiome are described. The relative merits of these methods and their present as well as prospective impact on our understanding of the human gut microbiota is discussed.