Contrast enhanced magnetic resonance imaging as a diagnostic tool to assess bladder permeability and associated colon cross talk: preclinical studies in a rat model

Development of a unique crosslinked glycosaminoglycan for soft tissue repair: Treatment of interstitial cystitis/bladder pain syndrome

Chemical modification of naturally derived glycosaminoglycans (GAGs) expands their potential utility for applications in soft tissue repair and regenerative medicine. Here we report the preparation of a novel crosslinked chondroitin sulfate (~200 to 2000 kilodaltons) that is both soluble in aqueous solution and microfilterable. We refer to these materials as "SuperGAGs." One can further conjugate these materials with diverse capture agents to further modify polymer properties and add new capabilities. A representative material (GLX-100) demonstrated durable restoration of bladder impermeability in a gold standard animal model of Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS). Histologic examination of the animal bladders treated with a GLX-100 SuperGAG conjugated to biotin as a reporter demonstrated that the residence time of GLX-100 is superior to chondroitin sulfate (a product that is currently used for clinical treatment of patients with IC/BPS). As expected, this novel crosslinked GAG biopolymer was restricted to the luminal surface of the bladder wall. In this communication we describe a simple and versatile synthesis of a crosslinked glycosaminoglycan (GAG) biopolymer for soft tissue repair. Chondroitin sulfate (~12 kD) was crosslinked to form a water soluble and microfilterable polymer with approximately 200 to 2000 kD molecular weight. The synthesis presented here allows for control of molecular weight while avoiding formation of an extended block gel. Moreover, the procedure enables further chemical modification of the SuperGAG through the selection of a capture agent. A set of agents have been used, demonstrating the preparation of a family of SuperGAGs with diverse capabilities. We can optimize polymer properties, adjust adherence to various tissues, add reporters, and engage the biochemistry of surrounding tissues with peptides and other bioactives.

The Neural Frontier of Future Medical Imaging: A Review of Deep Learning for Brain Tumor Detection

Brain tumor detection is crucial in medical research due to high mortality rates and treatment challenges. Early and accurate diagnosis is vital for improving patient outcomes, however, traditional methods, such as manual Magnetic Resonance Imaging (MRI) analysis, are often time-consuming and error-prone. The rise of deep learning has led to advanced models for automated brain tumor feature extraction, segmentation, and classification. Despite these advancements, comprehensive reviews synthesizing recent findings remain scarce. By analyzing over 100 research papers over past half-decade (2019-2024), this review fills that gap, exploring the latest methods and paradigms, summarizing key concepts, challenges, datasets, and offering insights into future directions for brain tumor detection using deep learning. This review also incorporates an analysis of previous reviews and targets three main aspects: feature extraction, segmentation, and classification. The results revealed that research primarily focuses on Convolutional Neural Networks (CNNs) and their variants, with a strong emphasis on transfer learning using pre-trained models. Other methods, such as Generative Adversarial Networks (GANs) and Autoencoders, are used for feature extraction, while Recurrent Neural Networks (RNNs) are employed for time-sequence modeling. Some models integrate with Internet of Things (IoT) frameworks or federated learning for real-time diagnostics and privacy, often paired with optimization algorithms. However, the adoption of eXplainable AI (XAI) remains limited, despite its importance in building trust in medical diagnostics. Finally, this review outlines future opportunities, focusing on image quality, underexplored deep learning techniques, expanding datasets, and exploring deeper learning representations and model behavior such as recurrent expansion to advance medical imaging diagnostics.

Visualising and quantifying intestinal permeability -where do we stand

Intestinal permeability is getting more and more attention in gastrointestinal research. Although well recognized, its exact role in health and disease is yet to be defined. There are many methods of quantifying intestinal permeability, but most of them fail to deliver tangible information about the morphological integrity of the intestinal barrier. In this review we aim to describe imaging options for the assessment of intestinal barrier integrity and their potential relevance for clinical practice. Our focus is on confocal laser endomicroscopy, which is at this time the only method for visualizing not only functional but also morphological aspects of the gut barrier in vivo.

Inhibition of CXCR4 in Spinal Cord and DRG with AMD3100 Attenuates Colon-Bladder Cross-Organ Sensitization

Background

Cross-sensitization of pelvic organs is one theory for why symptoms of gut sickness and interstitial cystitis/bladder pain syndrome overlap. Experimental colitis has been shown to trigger bladder hyperactivity and hyperalgesia in rats. The chemokine receptor CXCR4 plays a key role in bladder function and central sensitization. We aim to study the role of CXCR4 and its inhibitor AMD3100 in colon-bladder cross-organ sensitization.

Methods

The colitis model was established by rectal infusion of trinitrobenzene sulfonic acid. Western blot and immunofluorescence were used to assess the expression and distribution of CXCR4. Intrathecal injection of AMD3100 (a CXCR4 inhibitor) and PD98059 (an ERK inhibitor) were used to inhibit CXCR4 and downstream extracellular signal-regulated kinase (ERK) in the spinal cord and dorsal root ganglion (DRG). Intravesical perfusion of resiniferatoxin was performed to measure the pain behavior counts of rats, and continuous cystometry was performed to evaluate bladder voiding function.

Results

Compared to the control group, CXCR4 was expressed more in bladder mucosa and colon mucosa, L6-S1 dorsal root ganglion (DRG), and the corresponding segment of the spinal dorsal horn (SDH) in rats with colitis. Moreover, intrathecal injection of the AMD3100 suppressed bladder overactivity, bladder hyperalgesia, and mastocytosis symptoms caused by colitis. Furthermore, AMD3100 effectively inhibited ERK activation in the spinal cord induced by experimental colitis. Finally, treatment with PD98059 alleviated bladder overactivity and hyperalgesia caused by colitis.

Conclusion

Increased CXCR4 in the DRG and SDH contributes to colon inflammation-induced bladder overactivity and hyperalgesia partly via the phosphorylation of spinal ERK. Treatment targeting the CXCR4/ERK pathway might provide a potential new approach for the comorbidity between the digestive system and the urinary system.

MRI as a Tool to Assess Interstitial Cystitis Associated Bladder and Brain Pathologies

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic, often incapacitating condition characterized by pain seeming to originate in the bladder in conjunction with lower urinary tract symptoms of frequency and urgency, and consists of a wide range of clinical phenotypes with diverse etiologies. There are currently no diagnostic tests for IC/BPS. Magnetic resonance imaging (MRI) is a relatively new tool to assess IC/BPS. There are several methodologies that can be applied to assess either bladder wall or brain-associated alterations in tissue morphology and/or pain. IC/BPS is commonly associated with bladder wall hyperpermeability (BWH), particularly in severe cases. Our group developed a contrast-enhanced magnetic resonance imaging (CE-MRI) approach to assess BWH in preclinical models for IC/BPS, as well as for a pilot study for IC/BPS patients. We have also used the CE-MRI approach to assess possible therapies to alleviate the BWH in preclinical models for IC/BPS, which will hopefully pave the way for future clinical trials. In addition, we have used molecular-targeted MRI (mt-MRI) to quantitatively assess BWH biomarkers. Biomarkers, such as claudin-2, may be important to assess and determine the severity of BWH, as well as to assess therapeutic efficacy. Others have also used other MRI approaches to assess the bladder wall structural alterations with diffusion-weighted imaging (DWI), by measuring changes in the apparent diffusion coefficient (ADC), diffusion tensor imaging (DTI), as well as using functional MRI (fMRI) to assess pain and morphological MRI or DWI to assess anatomical or structural changes in the brains of patients with IC/BPS. It would be beneficial if MRI-based diagnostic tests could be routinely used for these patients and possibly used to assess potential therapeutics.

SuperGAG biopolymers for treatment of excessive bladder permeability

Few therapeutic options exist for treatment of IC/BPS. A novel high MW GAG biopolymer ("SuperGAG") was synthesized by controlled oligomerization of CS, purified by TFF and characterized by SEC-MALLS and 1H-NMR spectroscopy. The modified GAG biopolymer was tested in an OVX female rat model in which bladder permeability was induced by a 10-minute intravesicular treatment with dilute (1 mg/ml) protamine sulfate and measured by classical Ussing Chamber TEER measurements following treatment with SuperGAG, chondroitin sulfate, or saline. The effect on abrogating the abdominal pain response was assessed using von Frey filaments. The SuperGAG biopolymer was then investigated in a second, genetically modified mouse model (URO-MCP1) that increasingly is accepted as a model for IC/BPS. Permeability was induced with a brief exposure to a sub-noxious dose of LPS and was quantified using contrast-enhanced MRI (CE-MRI). The SuperGAG biopolymer restored impermeability to normal levels in the OVX rat model as measured by TEER in the Ussing chamber and reduced the abdominal pain response arising from induced permeability. Evaluation in the URO-MCP1 mouse model also showed restoration of bladder impermeability and showed the utility of CE-MRI imaging for evaluating the efficacy of agents to restore bladder impermeability. We conclude novel high MW SuperGAG biopolymers are effective in restoring urothelial impermeability and reducing pain produced by loss of the GAG layer on the urothelium. SuperGAG biopolymers could offer a novel and effective new therapy for IC/BPS, particularly if combined with MRI to assess the efficacy of the therapy.

In vivo and ex vivo assessment of bladder hyper-permeability and using molecular targeted magnetic resonance imaging to detect claudin-2 in a mouse model for interstitial cystitis

OBJECTIVES

To determine if the URO-MCP-1 mouse model for bladder IC/BPS is associated with in vivo bladder hyper-permeability, as measured by contrast-enhanced MRI (CE-MRI), and assess whether molecular-targeted MRI (mt-MRI) can visualize in vivo claudin-2 expression as a result of bladder hyper-permeability. Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic, painful condition of the bladder that affects primarily women. It is known that permeability plays a substantial role in IC/BPS. Claudins are tight junction membrane proteins that are expressed in epithelia and endothelia and form paracellular barriers and pores that determine tight junction permeability. Claudin-2 is a molecular marker that is associated with increased hyperpermeability in the urothelium.

MATERIALS AND METHODS

CE-MRI was used to measure bladder hyper-permeability in the URO-MCP-1 mice. A claudin-2-specific mt-MRI probe was used to assess in vivo levels of claudin-2. The mt-MRI probe consists of an antibody against claudin-2 conjugated to albumin that had Gd-DTPA (gadolinium diethylenetriamine pentaacetate) and biotin attached. Verification of the presence of the mt-MRI probe was done by targeting the biotin moiety for the probe with streptavidin-horse radish peroxidase (SA-HRP). Trans-epithelial electrical resistance (TEER) was also used to assess bladder permeability.

RESULTS

The URO-MCP-1 mouse model for IC/BPS was found to have a significant increase in bladder permeability, following liposaccharide (LPS) exposure, compared to saline-treated controls. mt-MRI- and histologically-detectable levels of the claudin-2 probe were found to increase with LPS -induced bladder urothelial hyper-permeability in the URO-MCP-1 IC mouse model. Levels of protein expression for claudin-2 were confirmed with immunohistochemistry and immunofluorescence imaging. Claudin-2 was also found to highly co-localize with zonula occlidens-1 (ZO-1), a tight junction protein.

CONCLUSION

The combination of CE-MRI and TEER approaches were able to demonstrate hyper-permeability, a known feature associated with some IC/BPS patients, in the LPS-exposed URO-MCP-1 mouse model. This MRI approach could be clinically translated to establish which IC/BPS patients have bladder hyper-permeability and help determine therapeutic options. In addition, the in vivo molecular-targeted imaging approach can provide invaluable information to enhance our understanding associated with bladder urothelium hyper-permeability in IC/BPS patients, and perhaps be used to assist in developing further therapeutic strategies.

Assessing bladder hyper-permeability biomarkers in vivo using molecularly-targeted MRI

The objective was to investigate if some of the key molecular players associated with bladder hyper-permeability in interstitial cystitis/bladder pain syndrome (IC/BPS) could be visualized with molecularly-targeted magnetic resonance imaging (mt-MRI) in vivo. IC/BPS is a chronic, painful condition of the bladder that affects primarily women. It has been demonstrated over the past several decades that permeability plays a substantial role in IC/BPS. There are several key molecular markers that have been associated with permeability, including glycolsaminoglycan (GAG), biglycan, chondroitin sulfate, decorin, E-cadherin, keratin 20, uroplakin, vascular endothelial growth factor receptor 1 (VEGF-R1), claudin-2 and zonula occludens-1 (ZO-1). We used in vivo molecularly-targeted MRI (mt-MRI) to assess specific urothelial biomarkers (decorin, VEGF-R1, and claudin-2) associated with bladder hyper-permeability in a protamine sulfate (PS)-induced rat model. The mt-MRI probes consisted of an antibody against either VEGF-R1, decorin or claudin-2 conjugated to albumin that had also Gd-DTPA (gadolinium diethylene triamine penta acetic acid) and biotin attached. mt-MRI- and histologically-detectable levels of decorin and VEGF-R1 were both found to decrease following PS-induced bladder urothelial hyper-permeability, whereas claudin-2, was found to increase in the rat PS model. Verification of the presence of the mt-MRI probes were done by targeting the biotin moiety for each respective probe with streptavidin-hose radish peroxidase (HRP). Levels of protein expression for VEGF-R1, decorin and claudin-2 were confirmed with immunohistochemistry. In vivo molecularly-targeted MRI (mt-MRI) was found to successfully detect alterations in the expression of decorin, VEGFR1 and claudin-2 in a PS-induced rat bladder permeability model. This in vivo molecularly-targeted imaging approach has the potential to provide invaluable information to enhance our understanding of bladder urothelium hyper-permeability in IC/BPS patients, and perhaps be used to assist in developing novel therapeutic strategies.

GAG replenishment therapy for bladder pain syndrome/interstitial cystitis

AIMS

To present a rationale for the inclusion of urothelial coating dysfunction in the etipathogenesis of bladder pain syndrome/interstitial cystitis (BPS/IC) and the preclinical and clinical evidence in support of glycosaminoglycan (GAG) replenishment therapy in the treatment of BPS/IC, supplemented by the clinical experience of medical experts in the field and patient advocates attending a symposium on GAG replenishment at ESSIC'17, the annual Meeting of the International Society for the Study of Bladder Pain Syndrome, held in Budapest, Hungary in 2017.

RESULTS

The urothelial GAG layer has a primary role in providing a permeability barrier to prevent penetration of urinary toxins and pathogens into the bladder wall. Disruption of the GAG layer contributes to the development of BPS/IC. The evidence shows that replenishment of GAGs can restore the GAG layer in BPS/IC, reducing inflammation, pain, and other symptoms.

CONCLUSIONS

Although data from large randomized controlled studies are limited, long clinical observation and the experience of clinicians and patients support the beneficial effects of intravesical GAG replenishment therapy for providing symptomatic relief for patients with BPS/IC.

Recent advances in imaging and understanding interstitial cystitis

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a debilitating condition associated with intense pelvic pain and bladder storage symptoms. Since diagnosis is difficult, prevalence estimates vary with the methodology used. There is also a lack of proven imaging tools and biomarkers to assist in differentiation of IC/BPS from other urinary disorders (overactive bladder, vulvodynia, endometriosis, and prostatitis). Current uncertainty regarding the etiology and pathology of IC/BPS ultimately impacts its timely and successful treatment, as well as hampers future drug development. This review will cover recent developments in imaging methods, such as magnetic resonance imaging, that advance the understanding of IC/BPS and guide drug development.

Preclinical Animal Studies of Intravesical Recombinant Human Proteoglycan 4 as a Novel Potential Therapy for Diseases Resulting From Increased Bladder Permeability

OBJECTIVE

To test in an animal model the hypothesis that recombinant human proteoglycan 4 (rhPRG4; lubricin), a highly O-glycosylated mucin-like glycoprotein, may be a novel surface-active therapeutic for treating bladder permeability with comorbid bowel permeability. Previously we showed that inducing bladder permeability in rats with dilute protamine sulfate (PS) produced colonic permeability and visceral hypersensitivity, suggesting increased bladder permeability could represent an etiologic factor in both interstitial cystitis-bladder pain syndrome and irritable bowel syndrome.

METHODS

We used an animal model of catheterized ovariectomized female rats instilled intravesically with 1 mg/mL PS for 10 minutes that after 24 hours were treated with 1.2 mg/mL lubricin or with vehicle alone. After 24 hours the bladder and colon were removed and permeability assessed electrophysiologically with the Ussing chamber to measure the transepithelial electrical resistance. A second set of rats was treated identically, except permeability was assessed on day 3 and on day 5 using contrast-enhanced magnetic resonance imaging with gadolinium diethylenetriamine penta-acetic acid instilled into the bladder.

RESULTS

Intravesical lubricin reversed bladder permeability induced by PS and prevented the concomitant increase in permeability induced in the bowel (organ crosstalk). The protective effect was confirmed with magnetic resonance imaging, and because individual rats could be followed over time, the impermeability of the bladder restored by rhPRG4 remained for 5 days.

CONCLUSION

These data indicate that instillation of rhPRG4 into a permeable bladder can restore its normally impermeable state, and that the effect lasts for 5 days and also prevents bowel symptoms often comorbid with interstitial cystitis-bladder pain syndrome.

Novel contrast mixture improves bladder wall contrast for visualizing bladder injury

Here, we tested whether combined contrast-enhanced magnetic resonance imaging (CCE-MRI), using a mixture of gadolinium- and iron oxide-based contrast agents, can segment the bladder wall from the bladder lumen. CCE-MRI relies on the differences in particle size and contrast mechanisms of two agents for improved image contrast. Under isoflurane anesthesia, T1-weighted imaging of adult female Sprague-Dawley rat bladder was performed using standard turbospin echo sequences at 7 Tesla, before and after transurethral instillation of 0.3 ml of single-contrast MRI or CCE-MRI composed of 0.4-64 mM of gadolinium chelate (Gd-DTPA/Gadavist) and 5 mM ferumoxytol. Bladder wall contrast was assessed in the control group exposed to saline and in the bladder injury group exposed to 0.5 ml of protamine sulfate (10 mg/ml) for 30 min. CCE-MRI following instillation of 0.4-4 mM Gd-DTPA and 5 mM ferumoxytol mixture achieved segmentation between the bladder lumen and bladder wall. Hyperintensity in the bladder wall combined with hypointensity in the lumen is consistent with the increased diffusion of the dissolved Gd-DTPA and simultaneous localization of the larger nanoparticles of ferumoxytol in the lumen. The normalized hyperintense signal in the bladder wall increased from 0.46 ± 0.07 in control group to 0.73 ± 0.14 in the protamine sulfate-exposed group (P < 0.0001). CCE-MRI following instillation of contrast mixture identifies bladder wall changes likely associated with bladder injury with improved image contrast.

In the absence of overt urothelial damage, chondroitinase ABC digestion of the GAG layer increases bladder permeability in ovariectomized female rats

Loss of integrity of the protective impermeability barrier in the urothelium has been identified as significant in bladder dysfunction. In this study, we tested the theory that the luminal layer of glycosaminoglycans (GAG) serves as an important component of barrier function. The peptide polycation protamine sulfate (PS), 1 mg/ml, was instilled intravesically for 10 min into rat bladders. Chondroitinase ABC (ChABC), 63 IU/ml, was instilled into an additional six rats for 30 min to digest the GAG layer. Unmanipulated controls and sham-injected controls were also performed. After 24 h, the rats were euthanized, the bladders were removed, and permeability was assessed in the Ussing chamber and by diffusion of FITC-labeled dextran (4 kDa) to measure macromolecular permeability. The status of tight junctions was assessed by immunofluorescence and electron microscopy. In control and sham treated rat bladders, the transepithelial electrical resistance were means of 2.5 ± 1.1 vs. 2.6 ± 1.1 vs 1.2 ± 0.5 and 1.01 ± 0.7 kΩ·cm(2) in the PS-treated and ChABC-treated rat bladders (P = 0.0016 and P = 0.0039, respectively). Similar differences were seen in dextran permeability. Histopathology showed a mild inflammation following PS treatment, but the ChABC-treated bladders were indistinguishable from controls. Tight junctions generally remained intact. ChABC digestion alone induced bladder permeability, confirming the importance of the GAG layer to bladder barrier function and supports that loss of the GAG layer seen in bladder biopsies of interstitial cystitis patients could be a significant factor producing symptoms for at least some interstitial cystitis/painful bladder syndrome patients.

A Feasibility Study to Determine Whether Clinical Contrast Enhanced Magnetic Resonance Imaging can Detect Increased Bladder Permeability in Patients with Interstitial Cystitis

PURPOSE

Interstitial cystitis/bladder pain syndrome is a bladder pain disorder associated with voiding symptomatology and other systemic chronic pain disorders. Currently diagnosing interstitial cystitis/bladder pain syndrome is complicated as patients present with a wide range of symptoms, physical examination findings and clinical test responses. One hypothesis is that interstitial cystitis symptoms arise from increased bladder permeability to urine solutes. This study establishes the feasibility of using contrast enhanced magnetic resonance imaging to quantify bladder permeability in patients with interstitial cystitis.

MATERIALS AND METHODS

Permeability alterations in bladder urothelium were assessed by intravesical administration of the magnetic resonance imaging contrast agent Gd-DTPA (Gd-diethylenetriaminepentaacetic acid) in a small cohort of patients. Magnetic resonance imaging signal intensity in patient and control bladders was compared regionally and for entire bladders.

RESULTS

Quantitative assessment of magnetic resonance imaging signal intensity indicated a significant increase in signal intensity in anterior bladder regions compared to posterior regions in patients with interstitial cystitis (p <0.01) and significant increases in signal intensity in anterior bladder regions (p <0.001). Kurtosis (shape of probability distribution) and skewness (measure of probability distribution asymmetry) were associated with contrast enhancement in total bladders in patients with interstitial cystitis vs controls (p <0.05). Regarding symptomatology interstitial cystitis cases differed significantly from controls on the SF-36®, PUF (Pelvic Pain and Urgency/Frequency) and ICPI (Interstitial Cystitis Problem Index) questionnaires with no overlap in the score range in each group. ICSI (Interstitial Cystitis Symptom Index) differed significantly but with a slight overlap in the range of scores.

CONCLUSIONS

Data suggest that contrast enhanced magnetic resonance imaging provides an objective, quantifiable measurement of bladder permeability that could be used to stratify bladder pain patients and monitor therapy.

Urodynamic and Immunohistochemical Evaluation of Intravesical Botulinum Toxin A Delivery Using Low Energy Shock Waves

PURPOSE

We investigated the feasibility of using low energy shock waves for intravesical botulinum toxin A delivery. We also evaluated its efficacy for acetic acid induced bladder hyperactivity in rats.

MATERIALS AND METHODS

In study 1 magnetic resonance imaging with intravesical administration of Gd-DTPA (Gd-diethylenetriamine pentaacetic acid) contrast medium was performed to visualize increased bladder urothelial permeability after low energy shock waves. In study 2 saline (1 ml) or botulinum toxin A (20 U/1 ml saline) was administered in the bladder with or without low energy shock waves (300 pulses at 0.12 mJ/mm(2)) and retained for 1 hour on day 1. Continuous cystometrograms were performed on day 8 by filling the bladder with saline followed by 0.3% acetic acid. The bladder was harvested for histology, and SNAP-25, SNAP-23 and COX-2 expression by Western blot or immunostaining.

RESULTS

Magnetic resonance imaging established bladder urothelial leakage of Gd-DTPA after low energy shock waves, which was not seen in controls. The intercontraction interval was decreased 71.9%, 72.6% and 70.6% after intravesical instillation of acetic acid in saline, saline plus low energy shock wave and botulinum toxin A pretreated rats, respectively. However, rats that received botulinum toxin A plus low energy shock waves showed a significantly reduced response (48.6% decreased intercontraction interval) to acetic acid instillation without compromising voiding function. Rats pretreated with botulinum toxin A plus low energy shock waves showed a decreased inflammatory reaction (p <0.05), and decreased expression of SNAP-23 (p <0.05), SNAP-25 (p = 0.061) and COX-2 (p <0.05) compared with the control group.

CONCLUSIONS

Low energy shock waves increased urothelial permeability, facilitated intravesical botulinum toxin A delivery and blocked acetic acid induced hyperactive bladder. These results support low energy shock waves as a promising method to deliver botulinum toxin A without the need for injection.

Assessment of colon and bladder crosstalk in an experimental colitis model using contrast-enhanced magnetic resonance imaging

BACKGROUND

Inflammatory bowel disease (IBD) consists of two chronic remitting-relapsing inflammatory disorders in the colon referred to as ulcerative colitis and Crohn's disease (CD). Inflammatory bowel disease affects about 1.4 million Americans. 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis is a widely used model of experimental intestinal inflammation with characteristic transmural and segmental lesions that are similar to CD.

METHODS

Here, we report on the use of contrast-enhanced magnetic resonance imaging (CE-MRI) to monitor in vivo bladder permeability changes resulting from bladder crosstalk following colon TNBS exposure, and TNBS-induced colitis. Changes in MRI signal intensities and histology were evaluated for both colon and bladder regions.

KEY RESULTS

Uptake of contrast agent in the colon demonstrated a significant increase in signal intensity (SI) for TNBS-exposed rats (p < 0.01) compared to controls. In addition, a significant increase in bladder SI for colon TNBS-exposed rats (p < 0.001) was observed compared to saline controls. Histological damage within the colon was observed, however, bladder histology indicated a normal urothelium in rats with TNBS-induced colitis, despite increased permeability seen by CE-MRI.

CONCLUSIONS & INFERENCES

Contrast-enhanced MRI was able to quantitatively measure inflammation associated with TNBS-induced colitis, and assess bladder crosstalk measured as an increase in urothelial permeability. Although CE-MRI is routinely used to assess inflammation with IBD, currently there is no diagnostic test to assess bladder crosstalk with this disease, and our developed method may be useful in providing crosstalk information between organ and tissue systems in IBD patients, in addition to colitis.

From bladder to systemic syndrome: concept and treatment evolution of interstitial cystitis

Interstitial cystitis, presently known as bladder pain syndrome, has been recognized for over a century but is still far from being understood. Its etiology is unknown and the syndrome probably harbors different diseases. Autoimmune dysfunction, urothelial leakage, infection, central and peripheral nervous system dysfunction, genetic disease, childhood trauma/abuse, and subsequent stress response system dysregulation might be implicated. Management is slowly evolving from a solo act by the end-organ specialist to a team approach based on new typing and phenotyping of the disease. However, oral and invasive treatments are still largely aimed at the bladder and are based on currently proposed pathophysiologic mechanisms. Future research will better define the disease, permitting individualization of treatment.

Mechanisms of Visceral Organ Crosstalk: Importance of Alterations in Permeability in Rodent Models

PURPOSE

The pathophysiology of painful bladder syndrome is poorly understood. However, there is evidence of female predominance and comorbidity with irritable bowel syndrome. Our hypothesis is that cross-sensitization between bladder and colon is due to altered permeability in 1 organ, which affects the other organ.

MATERIALS AND METHODS

Experiments were performed in anesthetized, ovariectomized female rats. In separate groups protamine sulfate was infused in the bladder or trinitrobenzene sulfonic acid was infused in the colon. Untreated rats served as controls. Bladder and colonic tissue were harvested from all rats 1, 3 and 5 days after treatment. Permeability was assessed in vitro in Ussing chambers by measuring transepithelial electrical resistance and macromolecular flux of fluorescein isothiocyanate-dextran.

RESULTS

Exposing the bladder to protamine sulfate induced a significant decrease in bladder transepithelial electrical resistance and an increase in the translocation of fluorescein isothiocyanate across the tissue compared to controls at 1 and 3 days (p <0.05). Colonic tissue from rats with enhanced bladder permeability showed a significant decrease in transepithelial electrical resistance and increase in fluorescein isothiocyanate compared to untreated controls at all time points (p <0.05). Conversely when colonic permeability was increased with trinitrobenzene sulfonic acid, we observed an increase in bladder permeability in the absence of any changes to the bladder urothelium.

CONCLUSIONS

Changes in epithelial permeability may represent a novel mechanism for visceral organ crosstalk. It may explain the overlapping symptomology of painful bladder syndrome and irritable bowel syndrome.