Pathophysiology of interstitial cystitis

Safety and efficacy of pentosan polysulfate in patients with bladder pain syndrome/interstitial cystitis: a multicenter, double-blind, placebo-controlled, randomized study

Introduction

Bladder pain syndrome/interstitial cystitis (BPS/IC) is a condition that is characterized by urgency, frequency and/or pelvic pain. The disease occurs mainly in women. BPS/IC can be severe enough to have a significant impact on patients' quality of life, but it can also be associated with moderate symptoms that are equally debilitating.

The aim of this article was to evaluate the possibility of the use of pentosan polysulfate sodium in patients in the complex treatment of BPS/IC.

Material and methods

A multicenter, double-blind, placebo-controlled, randomized study was conducted in parallel groups in 7 Russian medical centers.

Results

Efficacy and safety have been established as the main criteria. A total of 93 patients were screened. Statistical analysis was performed. It has been shown that pentosan therapy is more effective than in the placebo. Average change in the number of points on the scale O'Leary-Santa Interstitial Cystitis Symptom Index compared to baseline data in the pentosan group 4.93 ±3, 03, in the placebo group 1.66 ±3.19 (p = 0.014), and the adverse events and safety of pentosan are comparable to the placebo group.

Conclusions

Oral glycosaminoglycan (pentosan polusulfate sodium) is an effective and safe drug and should be included in the complex treatment of patients with bladder pain syndrome/interstitial cystitis.

Clinical presentation and treatment of bladder pain syndrome/interstitial cystitis (BPS/IC) in India

Bladder pain syndrome/interstitial cystitis (BPS/IC) is a chronic disease characterized by pelvic pain urgency and frequency. Patients with severe symptoms lead a very miserable life. North American, European and Asian guidelines have been recently promulgated but they differ on many important issues. There is no consensus on its name, definition, investigations and management. Indian guidelines have also been developed and they give more importance to the symptoms in relation to micturition. Though initially believed to be rare or non-existent in India the situation has changed. In Indian patients the presentation is more or less same as the rest of the world but a large percentage have obstructive symptoms and unusual urinary symptoms. Anal discomfort is also common. In India the commonest investigation in all cases of lower urinary tract (LUT) dysfunction is ultrasonography of kidney ureter and bladder with measurement of the post void residual urine volume. Cystoscopy is also done in all the cases to rule out presence of tuberculosis or carcinoma in situ. Bladder pain syndrome/interstitial cystitis (BPS/IC) is not considered to be a clinical disease as it is difficult to rule out all differential diagnosis only from history. Hunner’s lesion is very rare. Cystoscopy with hydro distension, oral therapy, intravesical therapy and surgical therapy form the back bone of management. It is difficult to know which treatment is best for a given patient. A staged protocol is followed and all the treatment modalities are applied to the patients in a sequential fashion—starting from the non-invasive to more invasive. Intravesical botox has not been found to be effective and there is no experience with interstim neuromodulation.

Angiogenic factors, bladder neuroplasticity and interstitial cystitis-new pathobiological insights

Vascular endothelial growth factor (VEGF) is essential for normal embryonic development, and maintenance of adult vascular function. Originally described as a vascular permeability factor, VEGF alters tight cell junctions and contributes to maintenance of bladder permeability. VEGF and its receptors are not only expressed in bladder blood vessels but also in apical cells and intramural ganglia. VEGF receptors are fundamentally altered by inflammation and bladder diseases such as interstitial cystitis (IC). Experimental results indicate that VEGF exerts direct effects on bladder nerve density and function. Regardless of the etiology or initiating cause for IC, it is hypothesized that the urinary bladder responds to injury by increasing the production of VEGF that acts initially as a survival mechanism. However, VEGF also has the capacity to increase vascular permeability leading to glomerulations, edema, and inflammation. Moreover, due to elevated numbers of VEGF receptors in the urothelium, the increased levels of VEGF further increase bladder permeability and establish a vicioCus cycle of disease pathophysiology.

Neuropilins: expression and roles in the epithelium

Initially found expressed in neuronal and then later in endothelial cells, it is well established that the transmembrane glycoproteins neuropilin-1 (NRP1) and neuropilin-2 (NRP2) play essential roles in axonal growth and guidance and in physiological and pathological angiogenesis. Neuropilin expression and function in epithelial cells has received little attention when compared with neuronal and endothelial cells. Overexpression of NRPs is shown to enhance growth, correlate with invasion and is associated with poor prognosis in various tumour types, especially those of epithelial origin. The contribution of NRP and its ligands to tumour growth and metastasis has spurred a strong interest in NRPs as novel chemotherapy drug targets. Given NRP's role as a multifunctional co-receptor with an ability to bind with disparate ligand families, this has sparked new areas of research implicating NRPs in diverse biological functions. Here, we review the growing body of research demonstrating NRP expression and role in the normal and neoplastic epithelium.

The overlap of interstitial cystitis/painful bladder syndrome and overactive bladder

Results of this study suggest that patients who have failed therapies for overactive bladder might be more effectively treated using therapies directed towards uroepithelial dysfunction and neural upregulation associated with interstitial cystitis.

Objective:

We evaluated the prevalence of positive potassium sensitivity and cystoscopy with hydrodistention findings in patients with overactive bladder.

Method:

This was a prospective cohort study of 98 patients who presented with overactive bladder symptoms. The diagnosis of overactive bladder is established by the presence of irritable voiding symptoms. All patients completed a PUF questionnaire and underwent potassium sensitivity testing. Eighty patients underwent urodynamic testing, and 42 patients underwent cystoscopic hydrodistention while under general anesthesia.

Results:

The Potassium Sensitivity Test was positive in 59 (60.2%) of the 98 patients, 37 (56%) of wet overactive bladder patients, and 22 (68.8%) of dry overactive bladder patients. Their mean PUF score was 7. Thirty-three (78.5%) of the patients who underwent cystoscopic hydrodistention had glomerulations consistent with NIH criteria for interstitial cystitis, and 26 of these patients tested positive for potassium sensitivity. Fifty-one (63.8%) of the patients who underwent urodynamics tested positive for potassium sensitivity.

Conclusion:

Many patients with symptoms of overactive bladder with little or no pain have cystoscopic evidence of interstitial cystitis and a positive Potassium Sensitivity Test. Therapies directed toward the uroepithelial dysfunction and neural upregulation associated with interstitial cystitis/painful bladder syndrome may be an important adjunct for patients who have failed or have had a partial response to anticholinergic therapy and behavior modification.

Urothelial expression of neuropilins and VEGF receptors in control and interstitial cystitis patients

Interstitial cystitis (IC) is a chronic and painful bladder syndrome of unknown cause with no reliable biological marker or effective therapy. Vascular endothelial growth factor (VEGF), which plays a key role in bladder inflammation, is closely associated with the vascular alterations observed in patients with IC. However, our recent findings of VEGF receptors (VEGF-Rs) and VEGF coreceptors on nonendothelial cells in human and mouse urothelium suggest that additional VEGF targets and functions are possible in IC bladders. We report here that VEGF-Rs and coreceptors (neuropilins; NRP) are strongly expressed in both the human bladder urothelium and in the human bladder cancer cell line (J82) and that the expression of NRP2 and VEGF-R1 is significantly downregulated in IC compared with control subjects. In addition, treatment of J82 cells with bacillus Calmette-Guérin (BCG), a novel treatment strategy for IC, upregulates the messages for NRPs and VEGF-Rs. Furthermore, intravesical instillation of an internalizable VEGF fluorescent tracer (scVEGF/Cy5.5) into mouse urinary bladders results in a marked ligand accumulation in the urothelium and bladder parenchyma, indicating that urothelial VEGF-Rs are functionally active and capable of ligand interaction and internalization. Our results suggest that the VEGF pathway is altered in IC, that urinary VEGF may gain access to the bladder wall via these receptors, and that BCG treatment may replenish the missing VEGF-Rs/NRP receptors. Together, these results suggest that levels of NRPs, VEGF-Rs, and VEGF are new putative markers for the diagnosis of IC and that modulating these receptors can be exploited as therapeutic strategies.

PACAP-mediated ATP release from rat urothelium and regulation of PACAP/VIP and receptor mRNA in micturition pathways after cyclophosphamide (CYP)-induced cystitis

Pituitary adenylate cyclase-activating peptide (PACAP) peptides are expressed in micturition pathways, and PACAP expression is regulated by urinary bladder inflammation. Previous physiological studies have demonstrated roles for PACAP27 and PACAP38 in detrusor smooth muscle (DSM) contraction and a PAC1 receptor antagonist reduced cyclophosphamide (CYP)-induced bladder hyperreflexia. To gain insight into PACAP signaling in micturition and regulation with cystitis, receptor characterization by real-time quantitative polymerase chain reaction and physiological assays were performed. PACAP receptors were identified in tissues of rat micturition pathway, including DSM, urothelium (U), and dorsal root ganglia (DRG) after acute (4 h), intermediate (48 h) or chronic (8 days) CYP-induced cystitis. PAC1 messenger RNA expression significantly (p < or = 0.05) increased in U and DSM after 48 h and chronic CYP-induced cystitis after an initial decrease at 4 h. VPAC1 and VPAC2 transcripts increased in U and DSM after acute and intermediate CYP-induced cystitis followed by a decrease in VPAC2 expression with chronic cystitis. Application of PACAP27 (100 nM) to cultured urothelial cells evoked adenosine triphosphate (ATP) release that was blocked by the PAC1 specific antagonist, M65 (1 microM). PACAP38 (100 nM) also evoked ATP release from cultured urothelial cells, but ATP release was less than that observed with PACAP27. PACAP transcripts were increased in the U with intermediate and chronic cystitis, whereas vasoactive intestinal polypeptide (VIP) expression in both tissues was very low and showed no regulation with cystitis. Regulation of PACAP, galanin, and substance P transcripts expression was observed in lumbosacral DRG, but no regulation for VIP was observed. The current data demonstrate PACAP and PAC1 regulation in micturition pathways with inflammation and PACAP-mediated ATP release from urothelium.

Role for pituitary adenylate cyclase activating polypeptide in cystitis-induced plasticity of micturition reflexes

Pituitary adenylate cyclase activating polypeptide (PACAP) peptides are expressed and regulated in sensory afferents of the micturition pathway. Although these studies have implicated PACAP in bladder control, the physiological significance of these observations has not been firmly established. To clarify these issues, the roles of PACAP and PACAP signaling in micturition and cystitis were examined in receptor characterization and physiological assays. PACAP receptors were identified in various tissues of the micturition pathway, including bladder detrusor smooth muscle and urothelium. Bladder smooth muscle expressed heterogeneously PAC(1)null, PAC(1)HOP1, and VPAC(2) receptors; the urothelium was more restricted in expressing preferentially the PAC(1) receptor subtype only. Immunocytochemical studies for PAC(1) receptors were consistent with these tissue distributions. Furthermore, the addition of 50-100 nM PACAP27 or PACAP38 to isolated bladder strips elicited transient contractions and sustained increases in the amplitude of spontaneous phasic contractions. Treatment of the bladder strips with tetrodotoxin (1 muM) did not alter the spontaneous phasic contractions suggesting direct PACAP effects on bladder smooth muscle. PACAP also increased the amplitude of nerve-evoked contractions. By contrast, vasoactive intestinal polypeptide had no direct effects on bladder smooth muscle. In a rat cyclophosphamide (CYP)-induced cystitis paradigm, intrathecal or intravesical administration of PAC(1) receptor antagonist, PACAP6-38, reduced cystitis-induced bladder overactivity. In summary, these studies support roles for PACAP in micturition and suggest that inflammation-induced plasticity in PACAP expression in peripheral and central micturition pathways contribute to bladder dysfunction with cystitis.

Randomized, double-blind, dose-ranging study of pentosan polysulfate sodium for interstitial cystitis

OBJECTIVES

To compare the current recommended dose of pentosan polysulfate sodium (PPS) with doses two to three times higher.

METHODS

We evaluated three dosages (300, 600, and 900 mg) of PPS in a randomized, double-blind, double-dummy, parallel-group, multicenter, 32-week study. Adults (n = 380) with a diagnosis of interstitial cystitis (IC) as determined by a positive cystoscopic examination combined with bladder pain and urgency or a history of IC symptoms for at least 6 months were enrolled. Participants completed the Patient's Overall Rating of Symptom Index (PORIS) and the O'Leary-Sant Interstitial Cystitis Symptom Index (ICSI) at baseline (ICSI only) and during follow-up visits at 4, 8, 12, 16, 24, and 32 weeks.

RESULTS

Mean ICSI scores improved significantly during the 32 weeks for all dosages (baseline 11.2, 11.9, and 11.9 to endpoint 8.2, 8.1, 8.6 for 300, 600, and 900 mg, respectively; P <0.001) but the response to treatment was not dose dependent (no statistically significant difference in response among the three dosages). At baseline, 3.2%, 62.2%, and 34.6% reported mild, moderate, and severe symptoms, respectively, as assessed by the ICSI. At study end, 27.5%, 56.9%, and 15.7% reported mild, moderate, and severe symptoms, respectively. The PORIS scores improved within 4 weeks with 15.8% to 21.1% of all patients classified as responders (50% or greater improvement on PORIS). At 32 weeks, 49.6%, 49.6%, and 45.2% of all patients were responders at a dose of 300, 600, and 900 mg, respectively. Most adverse events were mild and resolved without intervention.

CONCLUSIONS

For all three dosages of PPS, a clinically significant but similar response was demonstrated. The duration of therapy appears to be more important than the dosage.

TRANSDERMAL POSTERIOR TIBIAL NERVE LASER THERAPY IS NOT EFFECTIVE IN WOMEN WITH INTERSTITIAL CYSTITIS

PURPOSE

Interstitial cystitis (IC) is a debilitating condition which causes irritative bladder symptoms, pain and a decrease in health status. The pathophysiology is poorly understood so therapeutic options are diverse. Percutaneous posterior tibial nerve stimulation is an effective treatment and pulsed transdermal laser stimulation is an established technique for pain management. We evaluated the efficacy of transdermal laser stimulation of the posterior tibial nerve for patients with IC.

MATERIALS AND METHODS

Women meeting the National Institutes of Health National Institute for Diabetes and Digestive and Kidney Diseases criteria for IC were prospectively recruited and randomized to treatment (29) or placebo (27) cohorts in a double-blind trial. At home the patient performed laser therapy daily for 30 seconds over the SP6 acupuncture point for 12 weeks. Measures at baseline and at 84-day followup included the 7-day voiding diary, the Interstitial Cystitis Problem Index, Interstitial Cystitis Symptom Index and RAND 36-Item Health Survey questionnaires.

RESULTS

There were no significant differences between the treatment and control cohorts on any of the measures. However, there was a significant decrease between baseline and 12-week followup in the amount voided, symptom problems and severity, and on all 8 SF-36 scales. There was no significant effect of fluid intake.

CONCLUSIONS

This study demonstrated no difference between the active and sham device. However, it is interesting that treatment and control cohorts experienced similar improvements, suggesting that the control cohort improvements may have been due to participants' belief that they were receiving active treatment from the stimulator. These findings provide support for investigating placebo effects in randomized trials.

COX-2 and prostanoid expression in micturition pathways after cyclophosphamide-induced cystitis in the rat

The purpose of this study was to determine the role of cyclooxygenase-2 (COX-2) and its metabolites in lower urinary tract function after induction of acute (4 h), intermediate (48 h), or chronic (10 day) cyclophosphamide (CYP)-induced cystitis. Bladders were harvested from euthanized female rats for analyses. Conscious cystometry was used to assess the effects of a COX-2-specific inhibitor, 5,5-dimethyl-3-(3-fluorophenyl)-4-(4-methylsulfonyl)phenyl2(5H)-furanone (DFU, 5 mg/kg sc), a disubstituted furanone, in CYP-induced cystitis. COX-2 mRNA was increased in inflamed bladders after acute (12-fold) and chronic (9-fold) treatment. COX-2 protein expression in inflamed bladders paralleled COX-2 mRNA expression. Prostaglandin D2-methoxime expression in the bladder was significantly (P < or = 0.01) increased in acute (3-fold) and chronic (5.5-fold) cystitis. Prostaglandin E2 was significantly (P < or = 0.01) increased (2-fold) in the bladder with intermediate (1.7-fold) and chronic (2.6-fold) cystitis. COX-2-immunoreactive cell profiles were distributed throughout the inflamed bladder and coexpressed histamine immunoreactivity. Conscious cystometry in rats treated with CYP + DFU showed increased micturition intervals 4 and 48 h after CYP treatment and decreased intravesical pressures during filling and micturition compared with rats treated with CYP + vehicle. These studies suggest an involvement of urinary bladder COX-2 and its metabolites in altered micturition reflexes with CYP-induced cystitis.

The epidemiology of interstitial cystitis: is it time to expand our definition?

Very few epidemiologic studies of interstitial cystitis (IC) have been published over the past 5 years. One population-based study focused only on women and suggested that the prevalence of the IC symptom complex in the United States is much higher than previously reported. Future epidemiologic studies of IC must overcome major obstacles to obtain more accurate population-based estimates. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) criteria used to assist in identifying patients with IC have proven to be cumbersome and too restrictive. Other obstacles include (1) the relative infrequency of the condition; (2) the long duration between development of symptoms and diagnosis; and (3) the perception that the disorder occurs predominantly in white women. Evidence suggests men with the IC symptom complex are often misdiagnosed by physicians and identified as having chronic prostatitis (also called the chronic pelvic pain syndrome) or benign prostatic hyperplasia. Children who present with the IC symptom complex are often thought to have voiding dysfunction. We propose that the more inclusive, less restrictive term chronic pelvic pain of the bladder (CPPB) be used in future epidemiologic studies of persons with the characteristic IC symptoms of urinary frequency, urgency, and pain. Early studies of chronic pelvic pain in general suggest that it is most common in women, of unknown etiology, and, in many patients, is associated with urinary bladder symptoms. It is necessary to develop case definitions for CPPB to accurately identify those patients with symptoms currently identified as IC.