Bladder outlet obstruction: progression from inflammation to fibrosis

Role of PAR2 in the Development of Lower Urinary Tract Dysfunction

PURPOSE

Lower urinary tract symptoms are a common finding in patients with chronic prostatitis/chronic pelvic pain syndrome. We previously reported that the mast cell-tryptase-PAR2 (protease activated receptor 2) axis has a critical role in the development of chronic pain in experimental autoimmune prostatitis, a mouse model of chronic prostatitis/chronic pelvic pain syndrome. Therefore, we examined whether PAR2 activation mediates lower urinary tract dysfunction.

MATERIALS AND METHODS

Functional cystometry was done in male B6 mice along with immunoblotting and immunohistochemistry for the expression of COL1A1 (collagen type I α I) and α-SMA (α-smooth muscle actin). Flow cytometry analysis was performed on single cell suspensions of the prostate, bladder, lymph nodes and spleen.

RESULTS

Experimental autoimmune prostatitis resulted in increased urinary voiding frequency and decreased bladder capacity 30 days after initiation. Concurrently, there was increased expression of COL1A1 and α-SMA in the prostates and bladders. In contrast, induction of experimental autoimmune prostatitis in PAR2 knockout mice did not result in altered urodynamics or increased markers of fibrosis in the prostate or the bladder. Single cell suspensions of the prostate, bladder, lymph nodes and spleen demonstrated that in the absence of PAR2 cellular inflammatory mechanisms were still initiated in experimental autoimmune prostatitis but PAR2 expression may be required to maintain chronic inflammation. Finally, antibody mediated PAR2 neutralization normalized urinary voiding frequency and bladder capacity, and attenuated chronic pelvic pain.

CONCLUSIONS

PAR2 activation in the prostate may contribute to the development of lower urinary tract dysfunction through proinflammatory as well as profibrotic pathways.

Benefits of mesenchymal stem cells after partial bladder outlet obstruction

INTRODUCTION

Partial bladder outlet obstruction (pBOO) results in significant morbidity and mortality in the pediatric and adult populations. Mesenchymal stem cells (MSC) have been widely studied in many organ systems for the treatment and prevention of fibrotic and inflammatory conditions. Therefore, we hypothesize that systemic administration of MSC will demonstrate short-term biochemical, histological, and urodynamic benefits in an animal model for pBOO.

METHODS

After University ethics approval, 5 × 106 green fluorescent protein GFP-labeled MSC were intravenously injected concurrently with pBOO in adult Sprague-Dawley rats. Five groups (n=3/group) were analyzed: a) unobstructed controls; b) pBOO for seven days with intravenous MSC (7d+MSC); c) pBOO for seven days without intravenous MSC (7d-MSC); d) pBOO for 14 days with intravenous MSC (14d+MSC), e) pBOO for 14 days without MSC (14d-MSC). Urodynamics were performed at the end of the experimental period and bladders were weighed. Immunohistochemistry was performed for GFP detection and reverse transcription polymerase chain reaction (RT-PCR) to detect mRNA of: TGF-B, HIF-1a, RhoA, GRP-78, lumican, and decorin.

RESULTS

All animals remained healthy. GFP was detected in all treatment groups. MSC treatment resulted in a significant decrease in bladder capacity (0.91 cc vs. 2.15 cc, p=0.04). Treatment also resulted in significant decreases in mRNA levels of: TGF-B, HIF-1a, Rho-A, and GRP-78.

CONCLUSIONS

Systemic treatment with MSC was well tolerated and resulted in MSC accumulation after pBOO. Despite our low numbers, we were able to successfully demonstrate short-term urodynamic improvements and widespread, significant decreases in inflammatory mediators. We believe that this decreased inflammatory cascade will help prevent long-term detrusor deterioration.

Bladder dysfunction in 2015: Novel findings continue to challenge researchers and clinicians

2015 has seen advances in various bladder conditions. MicroRNAs might become therapeutic targets, the MAPP network characterized central neurological changes in chronic pelvic pain syndrome, and urologists were reminded to consider cognitive effects of long-term anticholinergics use. A study of obstetric vesicovaginal fistula repair shows how evidence-based research might improve public health in poorly resourced countries.

The NLRP3 Inflammasome Mediates Inflammation Produced by Bladder Outlet Obstruction

PURPOSE

While bladder outlet obstruction is well established to elicit an inflammatory reaction in the bladder that leads to overactive bladder and fibrosis, little is known about the mechanism by which this is initiated. NLRs (NOD-like receptors) and the structures that they form (inflammasomes) have been identified as sensors of cellular damage, including pressure induced damage, and triggers of inflammation. Recently we identified these structures in the urothelium. In this study we assessed the role of the NLRP3 (NACHT, LRR and PYD domains-containing protein 3) inflammasome in bladder dysfunction resulting from bladder outlet obstruction.

MATERIALS AND METHODS

Bladder outlet obstruction was created in female rats by inserting a 1 mm outer diameter transurethral catheter, tying a silk ligature around the urethra and removing the catheter. Untreated and sham operated rats served as controls. Rats with bladder outlet obstruction were given vehicle (10% ethanol) or 10 mg/kg glyburide (a NLRP3 inhibitor) orally daily for 12 days. Inflammasome activity, bladder hypertrophy, inflammation and bladder function (urodynamics) were assessed.

RESULTS

Bladder outlet obstruction increased urothelial inflammasome activity, bladder hypertrophy and inflammation, and decreased voided volume. Glyburide blocked inflammasome activation, reduced hypertrophy and prevented inflammation. The decrease in voided volume was also attenuated by glyburide mechanistically as an increase in detrusor contraction duration and voiding period.

CONCLUSION

Results suggest the importance of the NLRP3 inflammasome in the induction of inflammation and bladder dysfunction secondary to bladder outlet obstruction. Arresting these processes with NLRP3 inhibitors may prove useful to treat the symptoms that they produce.

Mast Cell Accumulation and Degranulation in Rat Bladder with Partial Outlet Obstruction

INTRODUCTION

Benign prostatic hyperplasia causes partial bladder outlet obstruction (pBOO), and many patients with pBOO are affected by not only voiding symptoms but also storage symptoms. We previously suggested that enhancement of 5-hydroxytryptamine (5-HT)-induced bladder contraction in the pBOO bladder may be one cause of storage symptoms. However, little is known about the presence of 5-HT in rat bladders. In this study, we hypothesized that mast cells are a source of 5-HT and investigated the distribution of mast cells and 5-HT in the bladders of rats with pBOO.

METHODS

The bladders of female Sprague-Dawley rats were subjected to pBOO and sham operations for 1 week, were isolated, and were fixed for light or electron microscopy. Mast cells and 5-HT in the bladders were detected by toluidine blue staining and immunohistochemical staining, respectively. The mast cells were counted under a light microscope. Degranulated mast cells were observed under an electron microscope and counted under a light microscope.

RESULTS

Mast cells were present in the mucosa/submucosa region in sham rat bladders. Their number was increased in the detrusor muscle/subserosa/serosa region, especially the subserosal layer, in pBOO rat bladders. The localization of mast cells almost matched that of 5-HT-positive cells in consecutive sections. Degranulated mast cells were present in sham and pBOO rat bladders, but the proportion of degranulated mast cells was significantly increased in every region in pBOO rat bladders compared with that in sham rat bladders.

CONCLUSION

These results suggest that mast cells contain 5-HT and are more abundant locally in the subserosal layer of pBOO rat bladders. 5-HT released from mast cells could stimulate 5-HT2 receptors on the detrusor muscle, and this may underlie storage symptoms.

FUNDING

Asahi Kasei Pharma Corp.

Activation of common signaling pathways during remodeling of the heart and the bladder

The heart and the urinary bladder are hollow muscular organs, which can be afflicted by pressure overload injury due to pathological conditions such as hypertension and bladder outlet obstruction. This increased outflow resistance induces hypertrophy, marked by dramatic changes in the organs' phenotype and function. The end result in both the heart and the bladder can be acute organ failure due to advanced fibrosis and the subsequent loss of contractility. There is emerging evidence that microRNAs (miRNAs) play an important role in the pathogenesis of heart failure and bladder dysfunction. MiRNAs are endogenous non-coding single-stranded RNAs, which regulate gene expression and control adaptive and maladaptive organ remodeling processes. This Review summarizes the current knowledge of molecular alterations in the heart and the bladder and highlights common signaling pathways and regulatory events. The miRNA expression analysis and experimental target validation done in the heart provide a valuable source of information for investigators working on the bladder and other organs undergoing the process of fibrotic remodeling. Aberrantly expressed miRNA are amendable to pharmacological manipulation, offering an opportunity for development of new therapies for cardiac and bladder hypertrophy and failure.

Research Findings on Overactive Bladder

Several physiopathologic conditions lead to the manifestation of overactive bladder (OAB). These conditions include ageing, diabetes mellitus, bladder outlet obstruction, spinal cord injury, stroke and brain injury, Parkinson's disease, multiple sclerosis, interstitial cystitis, stress and depression. This review has discussed research findings in human and animal studies conducted on the above conditions. Several structural and functional changes under these conditions have not only been observed in the lower urinary tract, but also in the brain and spinal cord. Significant changes were observed in the following areas: neurotransmitters, prostaglandins, nerve growth factor, Rho-kinase, interstitial cells of Cajal, and ion and transient receptor potential channels. Interestingly, alterations in these areas showed great variation in each of the conditions of the OAB, suggesting that the pathophysiology of the OAB might be different in each condition of the disease. It is anticipated that this review will be helpful for further research on new and specific drug development against OAB.

Proteomic profile of an acute partial bladder outlet obstruction

INTRODUCTION

Partial bladder outlet obstruction (pBOO) is a ubiquitous problem in urology. From posterior urethral valves to prostatic hypertrophy, pBOO results in significant morbidity and mortality. However, the pathophysiology is not completely understood. Proteomics uses mass spectrometry to accurately quantify change in tissue protein concentration. Therefore, we have applied proteomic analysis to a rodent model to assess for protein changes after a surgically induced pBOO. We hypothesize that proteomic analysis after an acute obstruction will determine the most prevalent initial protein response and, potentially, novel molecular pathways.

METHODS

Sprague Dawley rats underwent a surgically induced pBOO (n = 3 per group) for 3, 7, or 14 days. Bladders were assessed for weight and urodynamic parameters. Proteomics used liquid-chromatography based mass spectrometry. Polymerase chain reaction (PCR) was performed on tissue samples to confirm increased mRNA transcription.

RESULTS

Bladder weight and capacity increased over the experimental period, but no changes were seen in bladder pressure. Statistically significant increases in protein quantities were seen in 3 proteins related to endoplasmic reticulum stress: GRP-78 (3.66-fold), RhoA (1.90-fold), and RhoA-GDP (1.95-fold), and 2 cytoskeleton molecules: actin (1.7-fold) and tubulin a/b (3.01-fold). Decorin and lumican, members of the small leucine rich proteoglycan (SLRP) family, were also elevated (0.35- and 0.34-fold, respectively). Real-time PCR data confirmed protein elevation.

CONCLUSION

Our experiment confirms that molecular changes occur very soon after the initiation of pBOO, and implicates several molecular pathways. We believe these insights may provide insight into novel prevention and treatment strategies targeted at the pathophysiology of pBOO.

Botulinum injection is useless on fibrotic neuropathic bladders

OBJECTIVE

Studies on the use of intradetrusor botulinum toxin A injection for children with neuropathic bladders are insufficient and the results are controversial. The aim of the present study was to evaluate the effect of intradetrusor botulinum toxin A injection for children with neuropathic bladders that are resistant to anticholinergic treatment, and to reveal any criteria indicating treatment success.

PATIENTS/METHODS

Hospital records were reviewed of 16 children with neuropathic bladders due to myelomeningocele, and who had botulinum toxin A injections between 2007 and 2010. Botulinum toxin A (10 units/kg) was injected endoscopically into various sites of the detrusor, except the trigone. The success was defined as complete dryness between clean intermittent catheterizations. Urodynamic studies before and after the application were evaluated and parameters, including bladder capacity (measured/expected) and compliance, were also analyzed. Reviewing the results, patients were then classified into two groups: as having fibrotic bladders (noncompliant, acontractile bladders with high pressures) or overactive bladders. Urodynamic findings and therapy success were then compared between the groups.

RESULTS

A total of 19 injections, including repeat injections in three patients, were performed. Results of the 16 initial injections were evaluated. Nine patients had detrusor overactivity, and five out of nine (56%) applications in this group resulted in complete dryness between clean intermittent catheterizations. In bladders with typical detrusor overactivity, there was a significant increase in both the capacity (from 0.53 to 0.74) and compliance (from 4.7 to 8.6 ml/cm H2O). Looking at the seven patients that displayed fibrotic bladders with very low compliance and no contraction at all, none of them presented with notable clinical improvement from injections. Comparing the urodynamic findings, there was no significant difference in compliance (3.1 ml/cm H2O before and 3.5 ml/cm H2O after) and bladder capacity (0.58 before and 0.52 after the treatment) in the fibrotic bladders.

DISCUSSION

Despite its worldwide usage and FDA approval, studies on the effectiveness of botulinumtoxin A on neuropathic bladders in children are controversial. There are now numerous studies attesting to the good results of BoNTA in neuropathic detrusor overactivity; however, only scarce reports comment on the specific features of the disease process among patients and reasons for failure in some. In our study, reviewing the urodynamic findings carefully, it was observed that the patients who did not respond to injections were the ones with no contractions, despite high pressures and low compliance. Therefore, describing the indications of BoNTA as neuropathic detrusor overactivity and urinary incontinence despite anticholinergic medications may lead to mistreatment of patients in the decompensated phase of a hyper-reflexive detrusor. Pretreatment urodynamic evaluation might be a good indicator, without biopsies, of estimating the degree of fibrosis and the patients who will benefit from the injection.

CONCLUSION

Botulinum toxin A injection in the neuropathic bladder of myelomeningocele patients was found to be ineffective if the detrusor was fibrotic, of low compliance and had lost contractility. Urodynamic findings should be carefully analyzed in order to select appropriate patients that may benefit from Botulinum injection.

The inflammatory cytokine IL-1β is involved in bladder remodeling after bladder outlet obstruction in mice

AIMS

We investigated the relationship between IL-1β and morphological and functional changes following partial bladder outlet obstruction (pBOO).

METHODS

Female wild-type C57/BL6 mice (WT) and IL-1β-/- mice (KO) were used. Animals were sacrificed either 1 or 3 weeks after pBOO or sham surgery, and their bladders were harvested to determine bladder weight, for RT-PCR to measure interleukin-1β (IL-1β), insulin growth factor-1 (IGF-1), and transforming growth factor-β (TGF-β) levels, and for histological analysis with Hematoxylin-Eosin (HE) staining. Cystometry was performed on conscious animals 3 weeks after surgery to evaluate urodynamic parameters. IGF-1 was also administered intraperitoneally to KO with pBOO, and bladder weight was then investigated.

RESULTS

IL-1β-mRNA levels were significantly higher in WT-pBOO than in WT-sham. IGF-1-mRNA and TGF-β-mRNA levels were also significantly higher in WT-pBOO than in WT-sham; however, these increases were smaller in KO-pBOO than in WT-pBOO. Bladder weight was significantly higher in WT-pBOO than in WT-sham, while increases in bladder weight were significantly suppressed in KO-pBOO. HE staining revealed the thickened bladder wall in WT-pBOO, and this phenomenon was less in KO-pBOO than in WT-pBOO. Regarding the urodynamic parameters examined, micturition pressure and bladder capacity were significantly higher in WT-pBOO than in WT-sham, but remained unchanged in KO-pBOO. The administration of IGF-1 to KO-pBOO led to similar increases in bladder weight and the thickened bladder wall as those observed in WT-pBOO.

CONCLUSION

IL-1β has the potential to induce bladder remodeling and deteriorate urodynamic parameters in pBOO.

A mouse model of urofacial syndrome with dysfunctional urination

Urofacial syndrome (UFS) is an autosomal recessive disease with severe dysfunctional urination including urinary incontinence (UI). Biallelic mutations of HPSE2 are discovered from UFS patients, suggesting that HPSE2 is a candidate disease gene. Here, we show that deletion of Hpse2 is sufficient to cause the UFS-like phenotype in mice. Hpse2 knockout mutants display a distended bladder (megacystis) phenotype and abnormal voiding behavior similar to that found in patients. While Hpse2 is largely dispensable for detrusor smooth muscle and urothelial cell fate determination, the mutants have significantly lower rates of cell proliferation than wild-type littermate controls. All Hpse2 mutants have a growth retardation phenotype and die within a month after birth. Comprehensive blood chemistry and urinalysis indicate that Hpse2 mutants have renal dysfunction and malnutrition. We provide evidence that transforming growth factor beta (Tgfβ) signaling is attenuated at birth. However, Tgfβ activity is significantly enhanced at later stages when the urological phenotype is severe, and the mutant bladders have accumulated excessive amount of fibrotic tissue. Together, these findings strongly suggest that Hpse2 is a causative gene of human UFS and further uncover unexpected roles of Hpse2 in bladder physiology, tissue remodeling and Tgfβ signaling.

Suppression of the PI3K pathway in vivo reduces cystitis-induced bladder hypertrophy and restores bladder capacity examined by magnetic resonance imaging

This study utilized magnetic resonance imaging (MRI) to monitor the real-time status of the urinary bladder in normal and diseased states following cyclophosphamide (CYP)-induced cystitis, and also examined the role of the phosphoinositide 3-kinase (PI3K) pathway in the regulation of urinary bladder hypertrophy in vivo. Our results showed that under MRI visualization the urinary bladder wall was significantly thickened at 8 h and 48 h post CYP injection. The intravesical volume of the urinary bladder was also markedly reduced. Treatment of the cystitis animals with a specific PI3K inhibitor LY294002 reduced cystitis-induced bladder wall thickening and enlarged the intravesical volumes. To confirm the MRI results, we performed H&E stain postmortem and examined the levels of type I collagen by real-time PCR and western blot. Inhibition of the PI3K in vivo reduced the levels of type I collagen mRNA and protein in the urinary bladder ultimately attenuating cystitis-induced bladder hypertrophy. The bladder mass calculated according to MRI data was consistent to the bladder weight measured ex vivo under each drug treatment. MRI results also showed that the urinary bladder from animals with cystitis demonstrated high magnetic signal intensity indicating considerable inflammation of the urinary bladder when compared to normal animals. This was confirmed by examination of the pro-inflammatory factors showing that interleukin (IL)-1α, IL-6 and tumor necrosis factor (TNF)α levels in the urinary bladder were increased with cystitis. Our results suggest that MRI can be a useful technique in tracing bladder anatomy and examining bladder hypertrophy in vivo during disease development and the PI3K pathway has a critical role in regulating bladder hypertrophy during cystitis.

The urinary bladder of spontaneously hypertensive rat demonstrates bladder hypertrophy, inflammation, and fibrosis but not hyperplasia

AIMS

The present study aims to systemically characterize the factors that are associated with urinary bladder organ enlargement in spontaneously hypertensive rats (SHR).

MAIN METHODS

We compared the SHR to age-matched normotensive Wistar-Kyoto (WKY) control rats in the levels of bladder pro-inflammatory factors, collagen expression (type I), and detrusor smooth muscle growth.

KEY FINDINGS

Our results showed that enhanced inflammatory responses and fibrosis were key factors that were closely associated with bladder wall thickening in SHR. Specifically the mRNA levels of inflammatory factors interleukin (IL)-1α, IL-6 and TNFα were significantly higher in SHR than those in WKY rats. The SHR also had a higher number of mast cells in the suburothelium space. Type I collagen production was also significantly higher in SHR when compared to that in control rats. However, the smooth muscle content stayed the same in SHR and WKY rats. This was shown by the results that the ratio of α-smooth muscle actin (SMA) to the nuclear protein histone H3 had no difference between these two rat strains. The mRNA and protein levels of proliferating cell nuclear antigen (PCNA) also showed no change in the urinary bladder of SHR and WKY rats. Further study showed that the phosphorylation level of Akt in the urinary bladder was not changed in SHR when compared to WKY rats. In contrast, the phosphorylation level of ERK1/2 was significantly higher in SHR bladder when compared to that of WKY rats.

SIGNIFICANCE

These results suggest that inflammation and fibrosis are primary factors that may lead to urinary bladder hypertrophy in SHR.

Transient increase in circulating myeloid-derived suppressor cells after partial bladder outlet obstruction

PURPOSE

Partial bladder outlet obstruction causes a significant increase in tissue and systemic oxidative stress markers and tissue inflammatory cytokine levels. Myeloid-derived suppressor cells, IFN-γ, IL-10 and aldosterone are believed to be associated with oxidative stress and inflammation. We investigated alterations in plasma myeloid-derived suppressor cells, IFN-γ, IL-10 and aldosterone levels in partial bladder outlet obstruction and after its reversal.

MATERIALS AND METHODS

Rats with surgically induced partial bladder outlet obstruction were divided into 4 groups of 3 each, including sham treated, 4-week obstruction, and 4 and 8-week obstruction with relief. Plasma levels of circulating myeloid-derived suppressor cells, IFN-γ, IL-10 and aldosterone were assessed by flow cytometry or enzyme-linked immunosorbent assay.

RESULTS

The circulating myeloid-derived suppressor cell level was markedly increased in the obstruction group compared to the sham treated group and it returned to normal in the 4 and 8-week obstruction with relief groups. Plasma IFN-γ, IL-10 and aldosterone were similarly increased in the obstruction group and returned to normal in the 4 and 8-week obstruction with relief groups.

CONCLUSIONS

Levels of circulating myeloid-derived suppressor cells, IFN-γ, IL-10 and aldosterone were increased in rats with partial bladder outlet obstruction but returned to normal after reversal. This suggests that an increase in these parameters may be a good predictive indicator of patients at increased risk for urinary symptoms.

Alteration of Urothelial Inflammation, Apoptosis, and Junction Protein in Patients with Various Bladder Conditions and Storage Bladder Symptoms Suggest Common Pathway Involved in Underlying Pathophysiology

OBJECTIVE

Lower urinary tract symptoms (LUTS) are common in various bladder disorders. This study investigated urothelial dysfunction and chronic inflammation in the urothelium in different types of lower urinary tract dysfunction (LUTD), which causes bladder storage symptoms.

METHODS

Bladder tissues were obtained from patients with LUTD including 17 with interstitial cystitis/bladder pain syndrome (IC/BPS), 15 with bladder outlet obstruction (BOO), 12 with spinal cord injury (SCI), 12 with recurrent urinary tract infection (UTI), 13 with ketamine related cystitis (KC) and 10 controls. The bladder specimens were investigated using immunofluorescence (IF) staining of the urothelial junction protein E-cadherin and the TUNEL assay for urothelial apoptosis. Mast cell activation was also measured by IF using tryptase for mucosal inflammation. Statistical analysis was performed using the Kruskal-Wallis and Wilcoxon rank-sum test and P-values less than 0.05 were considered significant.

RESULTS

Highly significant increases of mast cell infiltration were observed in patients with KC (7.8 ± 3.7), IC/BPS (4.6 ± 3.0), recurrent UTI (2.4 ± 1.2), SCI (3.7 ± 2.7), and BOO (5.1 ± 2.0) compared with controls (1.3 ± 1.2) (all p < 0.05). Statistically significant increases of apoptotic cells were observed in patients with KC (4.2 ± 1.5), IC/BPS (2.4 ± 1.7), SCI (2.4 ± 1.4), recurrent UTI (1.9 ± 2.4), and BOO (1.2 ± 1.1) compared with controls (0.08 ± 0.3) (all p < 0.05). Significantly decreased expression of E-cadherin in patients with IC/BPS (25.1 ± 16.3), KC (11.0 ± 11.3), and recurrent UTI (26.2 ± 5.0) was found compared to controls (42.4 ± 16.7) and patients with SCI (44.4 ± 18.8) or BOO (42.8 ± 14.3) (all P < 0.05).

CONCLUSION

Increased urothelial inflammation and urothelial cell apoptosis seem to share common pathophysiologies of various LUTDs that cause similar bladder symptoms.

TGF-β1 induces EMT reprogramming of porcine bladder urothelial cells into collagen producing fibroblasts-like cells in a Smad2/Smad3-dependent manner

Activation of fibroblasts and their differentiation into myofibroblasts, excessive collagen production and fibrosis occurs in a number of bladder diseases. Similarly, conversion of epithelial cells into mesenchymal cells (EMT) has been shown to increase fibroblasts like cells. TGF-β1 can induce the EMT and the role of TGF-β1-induced EMT during bladder injury leading to fibrosis and possible organ failure is gaining increasing interest. Here we show that EMT and fibrosis in porcine bladder urothelial (UC) cells are Smad dependent. Fresh normal porcine bladder urothelial cells were grown in culture with or without TGF-β1 and EMT markers were assessed. TGF-β1 treatment induced changes in cellular morphology as depicted by a significant decrease in the expression of E-cadherin and corresponding increase in N-cadherin and α-SMA. We knocked down Smad2 and Smad3 by Smad specific siRNA. Downregulation of E-cadherin expression by TGF-β1 was Smad3-dependent, whereas N-cadherin and α-SMA were dependent on both Smad2 and Smad3. Connective tissue growth factor (CTGF/CCN2), matrix metalloproteinase-2 and -9 (MMP-2, MMP-9) has been shown to play important roles in the pathogenesis of fibrosis. Induction of these genes by TGF-β1 was found to be time dependent. Upregulation of CTGF/CCN2 by TGF-β1 was Smad3 dependent; whereas MMP-2 was Smad2 dependent. Smad2 and Smad3 both participated in MMP-9 expression. TGF-β1 reprogrammed mesenchymal fibroblast like cells robustly expressed collagen I and III and these was inhibited by SB-431542, a TGF-β receptor inhibitor. Our results indicate that EMT of porcine bladder UC cells is TGF-β1 dependent and is mediated through Smad2 and Smad3. TGF-β1 may be an important factor in the development of bladder fibrosis via an EMT mechanism. This identifies a potential amenable therapeutic target.

Skp2-mediated degradation of p27 regulates cell cycle progression in compressed human bladder smooth muscle cells

Bladder outlet obstruction (BOO) results in smooth muscle cell hyperplasia, decreased bladder wall compliance, and lower and upper urinary tract pathology. Mechanical stimulus on detrusor tissue is critical to BOO disease progression. Our previous studies confirm that mechanical stimulus triggers human bladder smooth muscle cell (HBSMC) proliferation. To better understand the signal transduction mechanisms for this process we detected cell cycle machinery of HBSMC (Bose ® Biodynamic, Minnetonka, MN, USA). HBSMCs cultured in scaffolds were subjected to four different pressures (0 cmH2O, 100 cmH2O, 200 cmH2O, and 300 cmH2O) for 24 hours, which were controlled by a BOSE BioDynamic bioreactor. Then we used flow cytometry to examine cell cycle distribution, polymerase chain reaction, and immunoblotting to quantify Skp2, p27, and p21 expression in each group. Additionally, Skp2 was silenced in HBSMCs using small interfering RNA to validate the role of Skp2 in mediating pressure-induced cell cycle progression. Compared with the 0 cmH2O control, HBSMCs in the 200 cmH2O and 300 cmH2O groups exhibited high-level expression of Skp2 gene and low-level expression of p27 protein. However, p21, another downstream signal of Skp2, showed no significant change between groups. In addition, Skp2 silencing abolished increases in cell proliferation induced by pressure. To the best of our knowledge, this is the first report on the functional importance of Skp2 in cyclic hydrodynamic pressure stimulated HBSMC proliferation. The signal transduction mechanism for this process involves p27 as well as p21 signaling pathway.

Phenotypic switching induced by damaged matrix is associated with DNA methyltransferase 3A (DNMT3A) activity and nuclear localization in smooth muscle cells (SMC)

Extracellular matrix changes are often crucial inciting events for fibroproliferative disease. Epigenetic changes, specifically DNA methylation, are critical factors underlying differentiated phenotypes. We examined the dependency of matrix-induced fibroproliferation and SMC phenotype on DNA methyltransferases. The cooperativity of matrix with growth factors, cell density and hypoxia was also examined. Primary rat visceral SMC of early passage (0–2) were plated on native collagen or damaged/heat-denatured collagen. Hypoxia was induced with 3% O₂ (balanced 5% CO₂ and 95% N₂) over 48 hours. Inhibitors were applied 2–3 hours after cells were plated on matrix, or immediately before hypoxia. Cells were fixed and stained for DNMT3A and smooth muscle actin (SMA) or smooth muscle myosin heavy chain. Illumina 450 K array of CpG sites was performed on bisulfite-converted DNA from smooth muscle cells on damaged matrix vs native collagen. Matrix exquisitely regulates DNMT3A localization and expression, and influences differentiation in SMCs exposed to denatured matrix +/− hypoxia. Analysis of DNA methylation signatures showed that Matrix caused significant DNA methylation alterations in a discrete number of CpG sites proximal to genes related to SMC differentiation. Matrix has a profound effect on the regulation of SMC phenotype, which is associated with altered expression, localization of DNMTs and discrete changes DNA methylation.

Future direction in pharmacotherapy for non-neurogenic male lower urinary tract symptoms

BACKGROUND

The pathophysiology of male lower urinary tract symptoms (LUTS) is highly complex and multifactorial. The shift in perception that LUTS are not sex or organ specific has not been followed by significant innovations regarding the available drug classes.

OBJECTIVE

To review pathophysiologic mechanisms and clinical and experimental data related to the development of new pharmacologic treatments for male LUTS.

EVIDENCE ACQUISITION

The PubMed database was used to identify articles describing experimental and clinical studies of pathophysiologic mechanisms contributing to male LUTS and, supported by them, new pharmacotherapies with clinical or experimental evidence in the field.

EVIDENCE SYNTHESIS

Several pathologic processes (eg, androgen signaling, inflammation, and metabolic factors) and targets (eg, the urothelium, prostate, interstitial cells, detrusor, neurotransmitters, neuromodulators, and receptors) have been implicated in male LUTS. Some newly introduced drugs, such as phosphodiesterase type 5 inhibitors and β3-adrenergic agonists, have just started broad use in clinical practice. Drugs with potential benefit, such as vitamin D3 receptor analogs, gonadotropin-releasing hormone antagonists, cannabinoids, and drugs injected into the prostate, have been evaluated in experimental studies and have progressed to clinical trials. However, safety and efficacy data for these drugs are still scarce. Some compounds with interesting profiles have only been tested in experimental settings (eg, transient receptor potential channel blockers, Rho-kinase inhibitors, purinergic receptor blockers, and endothelin-converting enzyme inhibitors).

CONCLUSIONS

New pathophysiologic mechanisms of male LUTS are described that lead to the continuous development of new pharmacotherapies. To date, few drugs have been added to the current armamentarium, and several are in various phases of clinical or experimental investigation.

Rapamycin attenuates bladder hypertrophy during long-term outlet obstruction in vivo: tissue, matrix and mechanistic insights

PURPOSE

Previous molecular studies showed that the mTOR inhibitor rapamycin prevents bladder smooth muscle hypertrophy in vitro. We investigated the effect of rapamycin treatment in vivo on bladder smooth muscle hypertrophy in a rat model of partial bladder outlet obstruction.

MATERIALS AND METHODS

A total of 48 female Sprague-Dawley® rats underwent partial bladder outlet obstruction and received daily subcutaneous injections of rapamycin (1 mg/kg) or vehicle commencing 2 weeks postoperatively. A total of 36 rats underwent sham surgery and received rapamycin or vehicle. Rats were sacrificed 3, 6 and 12 weeks after surgery. Before sacrifice, voiding was observed in a metabolic cage for 24 hours. Bladder-to-body weight in gm bladder weight per kg body weight and post-void residual urine were assessed. We evaluated Col1a1, Col3a1, Eln and Mmp7 mRNA expression and histology. Two-factor ANOVA and the post hoc t test were applied.

RESULTS

Bladder outlet obstruction caused a significant increase in bladder weight in all obstructed groups. Three weeks postoperatively (1 week of treatment) there was no difference in the bladder-to-body weight ratio in the obstructed group. However, at 6 and 12 weeks (4 and 10 weeks of treatment, respectively) the bladder-to-body weight ratio of rats with obstruction plus rapamycin was significantly lower than that of rats with obstruction plus vehicle. Post-void residual urine volume after 6 and 12 weeks of obstruction was lower in obstructed rats with rapamycin compared to that in obstructed rats with vehicle. Rapamycin decreased the obstruction induced expression of Col1a1, Col3a1, Eln and Mmp7.

CONCLUSIONS

Rapamycin prevents mechanically induced hypertrophy in cardiovascular smooth muscle. In vivo mTOR inhibition may attenuate obstruction induced detrusor hypertrophy and help preserve bladder function.

Stromal Cell-Derived Factor 1α Induces Accumulation of Intraveneously Administered Marrow-Derived Stromal Cells in the Partially Obstructed Rat Bladder

OBJECTIVES

We investigated the time course of the stromal cell-derived factor 1α (SDF1α) expression and behavior of intravenously administered bone marrow-derived stromal (BMS) cells in the urinary bladder of partial bladder outlet obstruction (PBOO) rats.

METHODS

Study 1: Recombinant SDF1α or saline was directly injected into the bladder wall of female rats followed by intravenous administration of BMS cells isolated from green fluorescent protein (GFP) transgenic rats. The bladder was examined with immunohistochemistry to determine whether SDF1α would enhance migration of BMS cells to the bladder. Study 2: Following surgery of PBOO or sham in female rats, bladders were removed on days 1-14, and expression of hypoxia inducible factor 1α (HIF1α) and SDF1α were examined with real-time polymerase chain reaction (PCR) to determine if PBOO preferentially increased their expression. Study 3: Female rats underwent PBOO or sham surgery followed by intravenous administration of GFP-positive BMS cells. Bladders were examined with immunohistochemistry on days 1-14 to determine whether BMS cells preferentially accumulated in the bladder.

RESULTS

BMS cells were accumulated in the injection site of SDF1α but not saline in the bladder. SDF1α and HIF1α increased at day 1 after PBOO compared to sham. More BMS cells accumulated in the bladder of PBOO on day 1, and some BMS cells expressed smooth muscle phenotypes by day 14.

CONCLUSION

SDF1α induced with ischemia/hypoxia due to PBOO is implicated in the accumulation of BMS cells in the bladder and regeneration of the bladder for PBOO.

Differential expression of class I small leucine-rich proteoglycans in an animal model of partial bladder outlet obstruction

PURPOSE

Partial bladder outlet obstruction has been shown in a rat model to progress from inflammation to hypertrophy to fibrosis. Small leucine-rich proteoglycans are extracellular matrix components associated with collagen fibrillogenesis and resultant scar formation. Two such critical small leucine-rich proteoglycans are decorin and biglycan. We hypothesized that in keeping with other scar models, decorin would be down-regulated and biglycan would be up-regulated with the onset of fibrosis compared to sham.

MATERIALS AND METHODS

We challenged our hypothesis with female Fisher rats that underwent ligation of the bladder neck or sham surgery. Animals were sacrificed at 4, 8 and 12 weeks, and bladders were harvested. Frozen sections were stained for immunofluorescence for decorin and biglycan. mRNA expression for decorin and biglycan was analyzed using quantitative reverse transcriptase polymerase chain reaction.

RESULTS

All rats survived to specified experimental end points in good health. Immunofluorescent stains showed progressive down-regulation of decorin and up-regulation of biglycan during the 12-week course by 0.36 and 1.82-fold, respectively (p = 0.02 and p = 0.02), compared to shams. Quantitative real-time reverse transcriptase polymerase chain reaction confirmed these findings in 12-week specimens, showing a down-regulation of decorin by a factor of 0.45 (p = 0.02) and up-regulation of biglycan by a factor of 2.04-fold (p = 0.08).

CONCLUSIONS

We present the first identification to our knowledge of small leucine-rich proteoglycans in normal and abnormal bladder tissue, and their differential expression in the process of bladder fibrosis, consistent with experimental findings in other anatomical sites. Further investigation into small leucine-rich proteoglycan expression and regulation may allow for the development of new antifibrotic therapeutics.

Identification of PDGFRα positive populations of interstitial cells in human and guinea pig bladders

PURPOSE

The bladder wall comprises a complex array of cells, including urothelium, smooth muscle, nerves and interstitial cells. Interstitial cells have several subtypes based on site, morphology and differential expression of markers such as anti-vimentin and anti-KIT. We examined whether a subpopulation of interstitial cells immunopositive for PDGFRα exists in human and guinea pig bladders.

MATERIALS AND METHODS

Human and guinea pig bladder tissues were processed for immunohistochemistry and examined by bright field or confocal microscopy. Whole mount tissues and paraffin sections were labeled with antibodies to PDGFRα, vimentin, KIT and PGP9.5. Protein expression was assessed by Western blot.

RESULTS

PDGFRα(+) cells were present in human and guinea pig bladders. In the guinea pig PDGFRα(+) cells had a branched stellate morphology and formed networks in the lamina propria. In human and guinea pig detrusors PDGFRα(+) cells were elongated on the boundary of smooth muscle bundles or were seen as groups of stellate cells in the interbundle spaces. PDGFRα(+) cells were located close to nerves labeled by PGP9.5. Double labeling revealed that PDGFRα(+) cells were a subgroup of the vimentin(+) population. A significant proportion of PDGFRα(+) cells were also KIT(+). Bands corresponding to PDGFRα, KIT and vimentin proteins were detected on Western blot.

CONCLUSIONS

To our knowledge this study is the first to identify PDGFRα(+)/KIT(+) cells in the bladder lamina propria and detrusor layers. These cells are a subgroup of the vimentin(+) population, showing the complexity of bladder interstitial cells. PDGFRα(+) cells are apparently structurally associated with intramural nerves, indicating integration with bladder control mechanisms.

Adjustable passive stiffness in mouse bladder: regulated by Rho kinase and elevated following partial bladder outlet obstruction

Detrusor smooth muscle (DSM) contributes to bladder wall tension during filling, and bladder wall deformation affects the signaling system that leads to urgency. The length-passive tension (L-T(p)) relationship in rabbit DSM can adapt with length changes over time and exhibits adjustable passive stiffness (APS) characterized by a L-T(p) curve that is a function of both activation and strain history. Muscle activation with KCl, carbachol (CCh), or prostaglandin E(2) at short muscle lengths can increase APS that is revealed by elevated pseudo-steady-state T(p) at longer lengths compared with prior T(p) measurements at those lengths, and APS generation is inhibited by the Rho Kinase (ROCK) inhibitor H-1152. In the current study, mouse bladder strips exhibited both KCl- and CCh-induced APS. Whole mouse bladders demonstrated APS which was measured as an increase in pressure during passive filling in calcium-free solution following CCh precontraction compared with pressure during filling without precontraction. In addition, CCh-induced APS in whole mouse bladder was inhibited by H-1152, indicating that ROCK activity may regulate bladder compliance during filling. Furthermore, APS in whole mouse bladder was elevated 2 wk after partial bladder outlet obstruction, suggesting that APS may be relevant in diseases affecting bladder mechanics. The presence of APS in mouse bladder will permit future studies of APS regulatory pathways and potential alterations of APS in disease models using knockout transgenetic mice.

From urgency to frequency: facts and controversies of TRPs in the lower urinary tract

The members of transient receptor potential (TRP) superfamily of cationic ion channels represent universal sensors, which convert multiple exogenous and endogenous chemical and physical stimuli into electrical and functional cellular responses. TRPs are widely distributed in many different tissues, and expression of numerous TRP types has been reported in lower urinary tract (LUT) tissues, neuronal fibers innervating the bladder and urethra, and epithelial and muscular layers of the bladder and urethral walls, where they are mainly involved in nociception and mechanosensory transduction. As such, they represent attractive targets for treating LUT disorders. Although information on the functional significance of many of the TRP proteins in the LUT remains very limited, compelling evidence has accumulated for a pivotal role of TRPV1, TRPV2, TRPV4, TRPM8, and TRPA1 in normal and pathological LUT function, mainly as sensors of stretch and chemical irritation. Further studies into these and other TRPs in the LUT will facilitate the development of improved therapeutic strategies to target these channels in LUT disorders.

Molecular reactions and ultrastructural damage in the chronically ischemic bladder

PURPOSE

Clinical and basic research data suggest that pelvic ischemia may contribute to bladder overactivity. We characterized the molecular and ultrastructural reactions of the chronically ischemic bladder.

MATERIALS AND METHOD

A model of pelvic ischemia was developed by creating iliohypogastric/pudendal arterial atherosclerosis in rabbits. At 12 weeks conscious urinary frequency was examined, bladder blood flow was recorded and cystometrograms were done using general anesthesia. Bladder tissue was processed for molecular and ultrastructural analysis using quantitative real-time polymerase chain reaction, Western blot and transmission electron microscopy.

RESULTS

Conscious urinary frequency and the frequency of spontaneous bladder contractions significantly increased in animals with pelvic ischemia. Bladder ischemia up-regulated the gene and protein expression of hypoxia inducible factor-1α, transforming growth factor-β and nerve growth factor B. Vascular endothelial growth factor gene expression also increased but protein levels were unchanged. Transmission electron microscopy of ischemic bladder samples showed swollen mitochondria with degraded granules, thickened epithelium, deformed muscle fascicles, collagen deposition and impaired microvasculature with thickened intima and disrupted endothelial cell junctions. Degenerating axonal and Schwann cell profiles, and myelin sheath splitting around axons and Schwann cells were evident in ischemic bladders.

CONCLUSIONS

Interrupting pelvic blood flow resulted in an ischemic overactive bladder and significant increase in conscious urinary frequency. Molecular responses involving hypoxia inducible factor, transforming growth factor-β, vascular endothelial growth factor and nerve growth factor were associated with mitochondrial injury, fibrosis, microvasculature damage and neurodegeneration. Ischemia may have a key role in bladder overactivity and lower urinary tract symptoms.

A murine model of inflammatory bladder disease: cathelicidin peptide induced bladder inflammation and treatment with sulfated polysaccharides

PURPOSE

Studies show that LL-37 is a naturally occurring urinary defensin peptide that is up-regulated during urinary tract infections. Although normal urinary LL-37 levels are antimicrobial, we propose that increased LL-37 may trigger bladder inflammation. We further suggest that anti-inflammatory sulfated polysaccharides known as semi-synthetic glycosaminoglycan ether compounds can treat/prevent LL-37 mediated bladder inflammation.

MATERIALS AND METHODS

C57BL/6 mice were catheterized/instilled with LL-37 (320 μM, 150 μl) for 45 minutes. Animals were sacrificed at 12 and 24 hours, and tissues were examined using hematoxylin and eosin. Separate experiments were performed for myeloperoxidase to quantify inflammation. GM-1111 semi-synthetic glycosaminoglycan ether treatments involved instillation of 10 mg/ml for 45 minutes directly before or after LL-37. Tissues were harvested at 24 hours. To compare semi-synthetic glycosaminoglycan ether efficacy, experiments were performed using 10 mg/ml heparin. Finally, tissue localization of semi-synthetic glycosaminoglycan ether was examined using a fluorescent GM-1111-Alexa Fluor® 633 conjugate.

RESULTS

Profound bladder inflammation developed after LL-37. Greater tissue inflammation occurred after 24 hours compared to that at 12 hours. Myeloperoxidase assays revealed a 21 and 61-fold increase at 12 and 24 hours, respectively. Semi-synthetic glycosaminoglycan ether treatment after LL-37 showed mild attenuation of inflammation with myeloperoxidase 2.5-fold below that of untreated bladders. Semi-synthetic glycosaminoglycan ether treatment before LL-37 demonstrated almost complete attenuation of inflammation. Myeloperoxidase results mirrored those in controls. In heparin treated bladders minimal attenuation of inflammation occurred. Finally, instillation of GM-1111-Alexa Fluor 633 revealed urothelial coating, significant tissue penetration and binding to endovasculature.

CONCLUSIONS

We developed what is to our knowledge a new model of inflammatory bladder disease by challenge with the naturally occurring urinary peptide LL-37. We also noted that a new class of anti-inflammatory sulfated polysaccharides prevents and mitigates bladder inflammation.