The urothelial barrier in interstitial cystitis/bladder pain syndrome: its form and function, an overview of preclinical models.

PURPOSE OF REVIEW: Investigating bladder pain syndrome/interstitial cystitis (IC/BPS) preclinically is challenging. Various research models have been used to mimic the urothelial barrier closely and replicate the disease. The aim of this review is to discuss preclinical research related to the urothelial barrier in context of IC/BPS. RECENT FINDINGS: In vivo models mimic IC/BPS mainly with toxic substances in the urine, with protaminesulfate and proteoglycan deglycolysation resembling a temporary impaired barrier as seen in IC/BPS. This temporary increased permeability has also been found in vitro models. Glycosaminoglycan replenishment therapy has been described, in vivo and in vitro, to protect and enhance recover properties of the urothelium. The roles of immune and neurogenic factors in the pathogenesis of IC/BPS remains relatively understudied. SUMMARY: Preclinical studies provide opportunities to identify the involvement of specific pathologic pathways in IC/BPS. For further research is warranted to elucidate the primary or secondary role of permeability, together with inflammatory and neurogenic causes of the disease.

Restoring the barrier of chronically damaged urothelium using chondroitin sulfate glycosaminoglycan-replenishment therapy.

PURPOSE OF REVIEW: This study aims to further understand the physiological mechanism of chondroitin sulfate treatment on the urinary bladder in cases of inflammation, by investigating the effect of chondroitin sulfate therapy on recovery of urothelial barrier in an in-vitro chronic injury model. RECENT FINDINGS: With inflammatory bladder conditions, the urothelial barrier seems decreased. Glycosaminoglycan (GAG) replacement therapy is supposed to help restore this barrier. Clinical studies on inflammatory bladder conditions are complicated because of the heterogeneous patient population, hence the need for preclinical models. SUMMARY: In a model using porcine urothelial cells, functional barrier (TEER) and barrier markers were assessed. Chronic urothelial damage was simulated through protamine sulfate instillations with and without subsequent chondroitin sulfate instillations during 3 days. Chondroitin sulfate instillations significantly improved TEER compared to protamine sulfate treatment only (TEER difference 310 Ω.cm 2 , P  < 0.001). This consistent effect over 3 days resulted in a significant higher mean TEER value in the chondroitin sulfate treated group (difference 1855 Ω.cm 2 , P  < 0.001). Enhanced recovery of chondroitin sulfate and other barrier markers was observed.Chondroitin sulfate therapy shows promise in facilitating the recovery of the urothelial barrier in cases of chronic damage. This preclinical study lends support to the use of clinical GAG replenishment therapy for patients with a chronically impaired urothelium.

The Burden of Urinary Tract Infections on Quality of Life and Healthcare in Patients with Interstitial Cystitis.

BACKGROUND: Interstitial cystitis/bladder pain syndrome (IC/BPS) patients are more susceptible to urinary tract infections (UTIs), likely worsening pre-existing symptoms. However, this receives limited attention in guidelines. This study aimed to explore the burden of UTIs on IC/BPS patients' quality of life and their healthcare. METHODS: Two quantitative retrospective database studies were conducted in cystoscopically proven IC/BPS patients: one compiled existing patient survey data (n = 217) from July 2021 to examine physical and emotional UTI burden, and the other used a patient file database (n = 100) from January 2020 to May 2022, focusing on UTI prevalence, healthcare use, urine cultures and antibiotic resistance. RESULTS: A delay in diagnosis was seen in 70% of patients, due to doctors confusing IC/BPS symptoms with UTIs. The UTI prevalence was over 50%; these patients also report anxiety for new UTIs (70%) and worsening of IC/BPS symptoms (60%). Additionally, for UTI+ patients, healthcare consumption was significantly increased in both studies. Antibiotic resistance (80% of cultures) and prophylactic antibiotic use were common. CONCLUSIONS: These findings highlight the burden of UTIs on quality of life in IC/BPS patients and the healthcare system. These results emphasize the need for improved UTI guidelines concerning diagnosis, management and prevention for IC/BPS patients to improve quality of life and care.

Study protocol of a multicentre double-blind RCT, comparing a traditional RCT with an aggregated N-of-1 trial: GAG therapy Efficacy Trial Solution for Bladder pain syndrome/Interstitial cystitis (GETSBI study).

INTRODUCTION: Obtaining level 1 evidence on efficacy of glycosaminoglycan (GAG) therapy is difficult, due to low incidence of bladder pain syndrome/interstitial cystitis (BPS/IC) and heterogeneous symptoms experienced by patients with BPS/IC. Currently, because of a lack of high-grade evidence, the recommendation for applying GAG therapy in most guidelines is 'low grade'. An aggregated N-of-1 trial is a multicrossover design that yields similar level 1 evidence as a traditional randomised controlled trial (RCT), while requiring far less patients. The goal of this study is to investigate the efficacy of intravesical GAG therapy (Ialuril) for patients with BPS/IC with Hunner lesions using a dual RCT and aggregated N-of-1 trial design to obtain level 1 evidence. METHODS AND ANALYSIS: The GETSBI study is a double-blind multidesign multicentre randomised placebo-controlled study to assess the short-term and long-term efficacy of hyaluronic acid (1.6%) + chondroitin sulfate (2%) therapy (Ialuril Prefill, IBSA, Goodlife) in patients with symptomatic BPS/IC with Hunner lesions. It starts as a standard RCT (n=80), but continues as an aggregated N-of-1 trial. There are three parallel arms, receiving blinded treatment for three periods (1 x/week for 6 weeks, ratio placebo to intervention in periods of 2:1). Followed by an open prospective part for the long-term efficacy. The primary study outcome is the maximum bladder pain experienced in the last 3 days measured using the visual analogue pain scale (0-10).This study is a collaboration with the Dutch government and will deliver evidence for the decision to reimburse the therapy. Furthermore, this multidesign study will allow us to compare the two main methods to evaluate applicability for future study designs for BPS/IC research. ETHICS AND DISSEMINATION: Ethical approval was given by METC Oost-Nederland, file number: 2020-7265, NL-number: NL76290.091.20. Findings from this study will be disseminated via publication, reports and conference presentations. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov identifier (NCT number): NCT05518864.

The functioning and the complication rate of extreme long existing urinary diversions.

PURPOSE OF REVIEW: This review is timely and relevant because many patients live many years with urinary diversions. Knowledge about the long term outcome with respect to function and complications are important for patient counseling and for the manner to follow-up patients. This study was performed to investigate the functioning of urinary diversions constructed > 25 years earlier. RECENT FINDINGS: Most studies have a relatively shorter follow-up, mainly focussing on short term postoperative complications. Focussing on the long term, urinary tract infections (UTI) including pyelonephritis are common. Mild kidney function deterioration is described. SUMMARY: Retrospective study (2018-2019); 43 patients with regular follow-up at the Radboud University Medical Centre Nijmegen the Netherlands. Ileal conduit (n = 19) and ureterosigmoidostomy (n = 11) are the most common diversion types for reasons such as: bladder exstrophy (n = 15), urinary incontinence (n = 9) and malignancy (n = 8). This series with a median follow-up of 40 years, shows it is possible to live and cope with a urinary diversion for a very long time. Ureterosigmoidostomies give relatively good results. Ileal conduits are functioning properly with acceptable complication rates. 95% suffers from chronic UTI's. Kidney function deterioration was mild. Diversions for benign reasons have more complex complications compared to diversion constructed for malignant reasons. VIDEO ABSTRACT: http://links.lww.com/COU/A32.

Knockout of Na+-glucose cotransporter SGLT1 mitigates diabetes-induced upregulation of nitric oxide synthase NOS1 in the macula densa and glomerular hyperfiltration.

Na+-glucose cotransporter (SGLT)1 mediates glucose reabsorption in late proximal tubules. SGLT1 also mediates macula densa (MD) sensing of an increase in luminal glucose, which increases nitric oxide (NO) synthase 1 (MD-NOS1)-mediated NO formation and potentially glomerular filtratrion rate (GFR). Here, the contribution of SGLT1 was tested by gene knockout (-/-) in type 1 diabetic Akita mice. A low-glucose diet was used to prevent intestinal malabsorption in Sglt1-/- mice and minimize the contribution of intestinal SGLT1. Hyperglycemia was modestly reduced in Sglt1-/- versus littermate wild-type Akita mice (480 vs. 550 mg/dl), associated with reduced diabetes-induced increases in GFR, kidney weight, glomerular size, and albuminuria. Blunted hyperfiltration was confirmed in streptozotocin-induced diabetic Sglt1-/- mice, associated with similar hyperglycemia versus wild-type mice (350 vs. 385 mg/dl). Absence of SGLT1 attenuated upregulation of MD-NOS1 protein expression in diabetic Akita mice and in response to SGLT2 inhibition in nondiabetic mice. During SGLT2 inhibition in Akita mice, Sglt1-/- mice had likewise reduced blood glucose (200 vs. 300 mg/dl), associated with lesser MD-NOS1 expression, GFR, kidney weight, glomerular size, and albuminuria. Absence of Sglt1 in Akita mice increased systolic blood pressure, associated with suppressed renal renin mRNA expression. This may reflect fluid retention due to blunted hyperfiltration. SGLT2 inhibition prevented the blood pressure increase in Sglt1-/- Akita mice, possibly due to additive glucosuric/diuretic effects. The data indicate that SGLT1 contributes to diabetic hyperfiltration and limits diabetic hypertension. Potential mechanisms include its role in glucose-driven upregulation of MD-NOS1 expression. This pathway may increase GFR to maintain volume balance when enhanced MD glucose delivery indicates upstream saturation of SGLTs and thus hyperreabsorption.

SGLT2 inhibition and renal urate excretion: role of luminal glucose, GLUT9, and URAT1.

Inhibitors of the Na+-glucose cotransporter SGLT2 enhance urinary glucose and urate excretion and lower plasma urate levels. The mechanisms remain unclear, but a role for enhanced glucose in the tubular fluid, which may interact with tubular urate transporters, such as the glucose transporter GLUT9 or the urate transporter URAT1, has been proposed. Studies were performed in nondiabetic mice treated with the SGLT2 inhibitor canagliflozin and in gene-targeted mice lacking the urate transporter Glut9 in the tubule or in mice with whole body knockout of Sglt2, Sglt1, or Urat1. Renal urate handling was assessed by analysis of urate in spontaneous plasma and urine samples and normalization to creatinine concentrations or by renal clearance studies with assessment of glomerular filtration rate by FITC-sinistrin. The experiments confirmed the contribution of URAT1 and GLUT9 to renal urate reabsorption, showing a greater contribution of the latter and additive effects. Genetic and pharmacological inhibition of SGLT2 enhanced fractional renal urate excretion (FE-urate), indicating that a direct effect of the SGLT2 inhibitor on urate transporters is not absolutely necessary. Consistent with a proposed role of increased luminal glucose delivery, the absence of Sglt1, which by itself had no effect on FE-urate, enhanced the glycosuric and uricosuric effects of the SGLT2 inhibitor. The SGLT2 inhibitor enhanced renal mRNA expression of Glut9 in wild-type mice, but tubular GLUT9 seemed dispensable for the increase in FE-urate in response to canagliflozin. First evidence is presented that URAT1 is required for the acute uricosuric effect of the SGLT2 inhibitor in mice.