Histopathological characteristics of interstitial cystitis/bladder pain syndrome without Hunner lesion

Patterns and predictors of Hunner lesion recurrence in patients with interstitial cystitis

AIMS

To evaluate the patterns and predictive factors associated with Hunner lesions (HLs) recurrence in patients with interstitial cystitis (IC).

METHODS

This study was a retrospective analysis of data from patients with IC who underwent transurethral resection and cauterization (TUR-C) of HLs between October 2011 and December 2017. Symptoms were evaluated using the Pelvic Pain and Urgency/Frequency Patient Symptom Scale (PUF), O'Leary-Sant Interstitial Cystitis Symptom Index, and Visual Analogue Scale (VAS). Patients attended follow-up visits every 3 months; cystoscopy was performed immediately in patients with aggravated symptoms. Recurrence was defined as a VAS score greater than or equal to 4 and HLs recurrence on cystoscopy.

RESULTS

A total of 91 patients were enrolled (25 male, 66 female): median follow-up was 30.6 months. HLs recurrence occurred in 101 sites (53 patients), 21.8% in the previous TUR-C site, 18.8% de novo, and 59.4% at both previous and de novo sites. The recurrence rate was approximately 12.7%, 40%, and 55.2% at 6, 12, and 18 months, respectively. A higher PUF bother score was the only predictive factor of recurrence (odds ratio: 1.142, 95% confidence interval: 1.016-1.284, P = 0.026), with a cut-off value of 7.5 (sensitivity: 67.9%, specificity: 62.5%). In case of late recurrence (>18 months), there was no predictive factor.

CONCLUSIONS

The HLs recurrence pattern was unpredictable, involving both previous TUR-C and de novo areas. More accurately defining the HLs resection margin may lead to better surgical outcomes but this remains to be proven.

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.

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.

Downregulation of WNT11 is associated with bladder tissue fibrosis in patients with interstitial cystitis/bladder pain syndrome without Hunner lesion

This study assessed the functional role of WNT genes and the association between WNT signalling cascades and fibrosis in interstitial cystitis/bladder pain syndrome (IC/BPS) patients. Twenty-five patients (3 males, 22 females; mean age 59.7 ± 10.9 years), included 7 non-Hunner-type IC (NHIC), 18 Hunner-type IC (HIC), and 5 non-IC (control) groups. The expression of sonic hedgehog, WNT gene family, and genes previously reported as biomarkers for IC/BPS were examined using RT-PCR in biopsy specimens from the mucosa and submucosa layer of the bladder. WNT2B, WNT5A, WNT10A, and WNT11 functions in the urothelium were evaluated by silencing in an HBlEpC cell line. Pelvic Pain and Urgency/Frequency Patient Symptom Scale scores, O’Leary-Sant Symptom and Problem Index scores, and Visual Analogue Scores did not differ between the NHIC and HIC groups. However, HIC patients had significantly shorter symptom duration (30.9 vs 70.8 months, p = 0.046), higher daily urinary frequency (16.1 versus 8.5 times, p = 0.006), and smaller bladder capacity (208.6 versus 361.4 ml, p = 0.006) than NHIC patients. Overall WNT gene expression was lower in NHIC than HIC patients. Bladder epithelial tissues from HIC patients were characterised by the downregulation of WNT11. Silencing of WNT11, WNT2B, WNT5A, and WNT10A in HBlEpCs resulted in fibrotic changes, indicated by fibrotic morphology, increased fibrosis-related gene expression, and nuclear localisation of phosphorylated SMAD2, and increased vimentin and fibronectin levels. Downregulation of WNT11 results in fibrotic changes of bladder epithelial cells and is associated with the pathogenesis and differential diagnosis of NHIC. Decreased expression of WNT11 is a potential biomarker for predicting NHIC.

Peroxisome proliferator-activated receptor gamma agonist as a novel treatment for interstitial cystitis: A rat model

Purpose

To understand the therapeutic potential of pioglitazone, a peroxisome proliferator-activated receptor gamma (PPAR-γ) agonist with a propensity to cause bladder mucosal proliferation, on interstitial cystitis (IC) in a rat model.

Materials and Methods

Using a previously described animal model for IC, Sprague-Dawley rats were treated with biweekly cyclophosphamide injections (35 mg/kg) to induce cystitis. Animals were divided into 4 groups (n=6 for each group): IC plus daily sham saline gavage (IC⁺Pio⁻), IC plus daily pioglitazone gavage (15 mg/kg) (IC⁺Pio⁺), normal rats with daily pioglitazone (IC⁻Pio⁺), and normal rats with neither IC nor pioglitazone (IC⁻Pio⁻ or Control). At the end of four weeks, urinary frequency and bladder capacity were measured. Histologic examination of urothelial integrity was also performed.

Results

Average voids per hour were significantly lower in IC⁺Pio⁺ (4.0±1.9) vs. IC⁺Pio⁻ (10.0±2.4) rats (p<0.01) and were similar to IC⁻Pio⁺ (6.0±1.4) and IC⁻Pio⁻ (6.0±1.5) controls. Cystometric capacity was significantly higher in IC⁺Pio⁺ (0.945±0.122 mL) vs. IC⁺Pio⁻ rats (0.588±0.165 mL, p=0.01) and was comparable to IC⁻Pio⁻ capacity (0.817±0.196 mL) and IC⁻Pio⁺ capacity (0.941±0.188 mL). Urothelial structural integrity was improved in IC⁺Pio⁺ rats versus IC⁺Pio⁻ rats upon histologic observation.

Conclusions

Pioglitazone, a PPAR-γ agonist, improved bladder function in cyclophosphamide-induced cystitis by both observed urinary frequency and measured cystometric capacity. Urothelial structural integrity was also improved. Pioglitazone, due to a propensity to cause bladder mucosal proliferation, may prove useful for treating IC, and deserves further investigation.

Electron microscopic characteristics of interstitial cystitis/bladder pain syndrome and their association with clinical condition

Background

Electron microscopy (EM) characteristics of the urothelium in interstitial cystitis/bladder pain syndrome (IC/BPS) and their association with clinical condition are unclear.

Methods

Ten IC/BPS patients who were admitted for hydrodistention and 5 patients with stress urinary incontinence (control patients) were enrolled. All patients provided detailed clinical histories and underwent urodynamic studies. Cystoscopic bladder biopsies were obtained and processed for transmission EM (TEM) and scanning EM (SEM). The severity of the urothelium findings was graded on a 4-point scale (0: none, 1: mild, 2: moderate, and 3: severe). The EM findings between IC/BPS and control patients were compared; the results were analyzed using the chi-square test.

Results

Compared with the urothelium of control patients, the urothelium of IC/BPS patients had more severe defects of the urothelial cell layers and integrity of umbrella cells in TEM (p = 0.045 and 0.01, respectively). In SEM, umbrella cell pleomorphism increased and microplicae of the cell membrane decreased in the IC/BPS group, and both were more severe than in the control group (p = 0.022 and 0.007, respectively). The patients with moderate to severe defects of umbrella cell integrity had more severe bladder pain and smaller maximal bladder capacity (MBC) (both p = 0.010). Patients with moderate to severe defects in microplicae of the cell membrane had smaller cystometric bladder capacity and MBC (p = 0.037 and 0.047, respectively).

Conclusions

The results revealed significant urothelium defects in IC/BPS, especially in the umbrella cells. Defects of umbrella cells may play an important role in the pathogenesis of IC/BPS.

Inflammation and Tissue Remodeling in the Bladder and Urethra in Feline Interstitial Cystitis

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a debilitating chronic disease of unknown etiology. A naturally occurring disease termed feline interstitial cystitis (FIC) reproduces many features of IC/BPS patients. To gain insights into mechanisms underlying IC/BPS, we investigated pathological changes in the lamina propria (LP) of the bladder and proximal urethra in cats with FIC, using histological and molecular methods. Compared to control cat tissue, we found an increased number of de-granulated mast cells, accumulation of leukocytes, increased cyclooxygenase (COX)-1 expression in the bladder LP, and increased COX-2 expression in the urethra LP from cats with FIC. We also found increased suburothelial proliferation, evidenced by mucosal von Brunn’s nests, neovascularization and alterations in elastin content. Scanning electron microscopy revealed normal appearance of the superficial urethral epithelium, including the neuroendocrine cells (termed paraneurons), in FIC urethrae. Together, these histological findings suggest the presence of chronic inflammation of unknown origin leading to tissue remodeling. Since the mucosa functions as part of a “sensory network” and urothelial cells, nerves and other cells in the LP are influenced by the composition of the underlying tissues including the vasculature, the changes observed in the present study may alter the communication of sensory information between different cellular components. This type of mucosal signaling can also extend to the urethra, where recent evidence has revealed that the urethral epithelium is likely to be part of a signaling system involving paraneurons and sensory nerves. Taken together, our data suggest a more prominent role for chronic inflammation and tissue remodeling than previously thought, which may result in alterations in mucosal signaling within the urinary bladder and proximal urethra that may contribute to altered sensations and pain in cats and humans with this syndrome.

Expression of programmed death ligand-1 on bladder tissues is detected in a clinically and histologically well-defined interstitial cystitis cohort

OBJECTIVE

To investigate the expression of programmed death ligand-1 (PD-L1) in interstitial cystitis (IC).

METHODS

We reviewed the data of IC patients underwent hydrodistension plus bladder biopsy. Follow-ups were performed. We assessed the degree of inflammation of the bladder wall on slides stained with hematoxylin and eosin (H&E). We performed immunohistochemistry for PD-L1 expression detection and for counting T lymphocytes and B lymphocytes.

RESULTS

The present study included eight men and 32 women. With H&E staining, we detected 13, 15, and 12 patients with mild, moderate, and severe inflammation. The degree of inflammation was negatively correlated with disease course (P = 0.018) and positively correlated with bladder pain (P < 0.001). Hydrodistension was found effective at postoperative 3-month for 19 patients. Overall, 17, 15, 7, and 1 subject had no, mild, moderate, and high PD-L1 expression, that correlated positively with the degree of inflammation. Compared with patients with no and mild PD-L1 expression, patients with moderate and high PD-L1 expression tended to have more effective hydrodistension outcomes (12 of 32 vs 7 of 8; P = 0.017). In the subset of 12 patients with severe inflammation, there were five of six patients (83.3%) with moderate or high PD-L1 expression and one of six patients (16.7%) with no and mild PD-L1 expression with an effective hydrodistension outcome.

CONCLUSIONS

Expression of PD-L1 on bladder is detected in a cohort of IC patients presented with diffuse global glomerulation or Hunner ulcer. PD-L1 expression is more common in IC patients with severe bladder inflammation.