Time-dependent functional, morphological, and molecular changes in diabetic bladder dysfunction in streptozotocin-induced diabetic mice

Long non-coding RNA H19 mediates the miR-29b/transforming growth factor-β1/Drosophila mothers against decapentaplegic 3 signalling pathway to promote bladder fibrosis in diabetic rats

PURPOSE

Diabetic bladder fibrosis is a common comorbidity. Altered expression of some long non-coding RNAs (LncRNAs) has been associated with bladder fibrosis. LncRNA H19 has been reported to regulate bladder cancer through miR-29b. However, the action mechanism of LncRNA H19 in bladder fibrosis is unclear.

METHODS

In vitro, human bladder smooth muscle cells (HBSMCs) were cultured with transforming growth factor-β1 (TGF-β1) for 48 h to construct cell model of bladder fibrosis. HBSMCs were then transfected with si-LncRNA H19, si-NC, miR-29b-mimic, mimic-NC, or miR-29b-inhibitor. In vivo, Sprague-Dawley (SD) rats were given a high-sucrose-high-fat (HSHF) diet for 4 weeks and injected with streptozotocin (STZ, 50 mg/kg) to induce bladder fibrosis model in diabetic rats, followed by injection of lentiviral particles knocking down LncRNA H19 expression, empty vector, or miR-29b-inhibitor, respectively.

RESULTS

LncRNA H19 was up-regulated in TGF-β1-induced HBSMC fibrosis and STZ-induced diabetic rat bladder fibrosis, whereas miR-29b was down-regulated. si-LncRNA H19 reduced blood glucose levels and improved histopathological damage of bladder tissue in rats. In addition, si-LncRNA H19 or miR-29b-mimic increased the expression of E-cadherin, but decreased the expression of N-cadherin, vimentin, fibronectin (FN) in bladder tissues, and HBSMCs. si-LncRNA H19 reduced TGF-β1/p-drosophila mothers against decapentaplegic 3 (Smad3) protein in HBSMCs and in rat bladder tissues, while miR-29b-inhibitor reversed the effect of si-LncRNA H19.

CONCLUSION

This study indicated that LncRNA H19 may inhibit bladder fibrosis in diabetic rats by targeting miR-29b via the TGF-β1/Smad3 signalling pathway.

Long-term aspirin administration suppresses inflammation in diabetic cystopathy

Diabetic cystopathy (DCP) is one of the most common and troublesome urologic complications of diabetes mellitus, characterized by chronic low-grade inflammatory response. However, the correlation between inflammation and disease progression remains ambiguous and effective drugs interventions remain deficient. Herein, during 12-week study, 48 male Sprague-Dawley rats were randomly assigned to four groups: negative control (NC), NC treated with aspirin (NC+Aspirin), DCP, and DCP treated with aspirin (DCP+Aspirin). Type 1 diabetes mellitus was established by intraperitoneal injection of streptozotocin (65 mg/kg). After 2 weeks modeling, the rats in treatment groups received daily oral aspirin (100 mg/kg/d). After 10 weeks of treatment, aspirin ameliorated pathological weight loss and bladder weight increase in diabetic rats, accompanied by a 16.5% decrease in blood glucose concentrations. H&E, Masson, immunohistochemistry and transmission electron microscopy revealed that a dilated bladder with thickened detrusor smooth muscle (DSM) layer, inflammatory infiltration, fibrosis and ultrastructural damage were observed in diabetic rats, which were obviously ameliorated by aspirin. The dynamic investigations at 4, 7 and 10 weeks revealed inflammation gradually increased as the disease progresses. After 10 weeks of treatment, the expression of TNF-α, IL-1β, IL-6, and NF-κB has been decreased to 78%, 39.7%, 44.1%, 33.3% at mRNA level and 67.6%, 76.7%, 71.4%, 67.1% at protein level, respectively (DCP+Aspirin vs. DCP, p < 0.01). Aspirin partially restored the increased expression of inflammatory mediators in bladder DSM of diabetic rats. The study provided insight into long-term medication therapies, indicating that aspirin might serve as a potential strategy for DCP treatment.

A Spectrum of Age- and Gender-Dependent Lower Urinary Tract Phenotypes in Three Mouse Models of Type 2 Diabetes

Lower urinary tract symptoms are extremely common in people with diabetes and obesity, but the causes are unclear. Furthermore, it has proven difficult to reliably demonstrate bladder dysfunction in diabetic mouse models, thus limiting the ability to gain mechanistic insights. Therefore, the main objective of this experimental study was to characterize diabetic bladder dysfunction in three promising polygenic mouse models of type 2 diabetes. We performed periodic assessments of glucose tolerance and micturition (void spot assay) for eight to twelve months. Males and females and high-fat diets were tested. NONcNZO10/LtJ mice did not develop bladder dysfunction over twelve months. TALLYHO/JngJ males were severely hyperglycemic from two months of age (fasted blood glucose ~550 mg/dL), while females were moderately so. Although males exhibited polyuria, neither they nor the females exhibited bladder dysfunction over nine months. KK.Cg-Ay/J males and females were extremely glucose intolerant. Males exhibited polyuria, a significant increase in voiding frequency at four months (compensation), followed by a rapid drop in voiding frequency by six months (decompensation) which was accompanied by a dramatic increase in urine leakage, indicating loss of outlet control. At eight months, male bladders were dilated. Females also developed polyuria but compensated with larger voids. We conclude KK.Cg-Ay/J male mice recapitulate key symptoms noted in patients and are the best model of the three to study diabetic bladder dysfunction.

SLC17A9-PTHLH-EMT axis promotes proliferation and invasion of clear renal cell carcinoma

SLC17A9 is a vesicular ATP transport protein that plays an important role in determining cell functions and the onset and progression of different diseases. In this study, SLC17A9 was initially identified as a potential diagnostic and prognostic risk biomarker for clear cell renal cell carcinoma (ccRCC). Then, the aberrant expression levels of SLC17A9 were confirmed in both the cell lines and clinical tissues. Mechanistically, SLC17A9 could upregulate the expression of PTHLH, thus promoting epithelial-mesenchymal transition (EMT) in ccRCC. Functionally, SLC17A9 knockdown inhibited the proliferation, migration, and invasion activity of renal cancer cells, whereas its overexpression led to stronger cell viability and more malignant phenotype in vitro. The overexpression of SLC17A9 in vivo could significantly contribute to the growth of tumors. Finally, we found that SLC17A9 might be related to the drug resistance of vorinostat. Cumulatively, this study demonstrated that the SLC17A9-PTHLH-EMT axis could promote the progression of ccRCC.

Inflammation triggered by the NLRP3 inflammasome is a critical driver of diabetic bladder dysfunction

Diabetes is a rapidly expanding epidemic projected to affect as many as 1 in 3 Americans by 2050. This disease is characterized by devastating complications brought about high glucose and metabolic derangement. The most common of these complications is diabetic bladder dysfunction (DBD) and estimates suggest that 50-80% of patients experience this disorder. Unfortunately, the Epidemiology of Diabetes Interventions and Complications Study suggests that strict glucose control does not decrease ones risk for incontinence, although it does decrease the risk of other complications such as retinopathy, nephropathy and neuropathy. Thus, there is a significant unmet need to better understand DBD in order to develop targeted therapies to alleviate patient suffering. Recently, the research community has come to understand that diabetes produces a systemic state of low-level inflammation known as meta-inflammation and attention has focused on a role for the sterile inflammation-inducing structure known as the NLRP3 inflammasome. In this review, we will examine the evidence that NLRP3 plays a central role in inducing DBD and driving its progression towards an underactive phenotype.

Functional and Immunofluorescence Evaluations of Vascular and Neural Integrities in Urinary Bladder of Streptozotocin-Induced Diabetic Mice

Purpose

To assess functional and structural changes in vascular and neural structures associated with diabetic bladder dysfunction (DBD) in the bladders of streptozotocin (STZ)-induced diabetic mice.

Methods

Eight-week-old C57BL/6 mice were injected with STZ at 50 mg/kg daily for 5 consecutive days. Catheters were inserted 12 weeks later, and 5 days after catheter placement bladder functions were assessed by conscious cystometry. Neurovascular and extracellular matrix marker changes in harvested urinary bladders were investigated by immunofluorescent staining. Body weights and fasting and postprandial blood glucose levels were measured 12 weeks after STZ injection.

Results

STZ-induced diabetic mice had significantly lower body weights and significantly higher blood glucose levels. Assessment of bladder function in STZ-induced diabetic mice revealed a nearly 3-fold increase in bladder capacity and intercontractile interval compared to controls. However, basal pressure, maximal bladder pressure, and threshold pressure were not significantly different. Morphological and structural analysis showed that STZ-induced diabetic mice had significantly reduced microvascular density in lamina propria (33% of the nondiabetic control values), and severely decreased nerve contents in the detrusor region (42% of the nondiabetic control values).

Conclusions

STZ-induced diabetic mice exhibit functional and structural derangements in urinary bladder. The present study provides a foundation and describes a useful means of evaluating the efficacies of therapeutic targets and exploring the detailed mechanism of DBD.

Myosin 5a in the Urinary Bladder: Localization, Splice Variant Expression, and Functional Role in Neurotransmission

Dysregulation of neurotransmission is a feature of several prevalent lower urinary tract conditions, but the mechanisms regulating neurotransmitter release in the bladder are not completely understood. The unconventional motor protein, Myosin 5a, transports neurotransmitter-containing synaptic vesicles along actin fibers towards the varicosity membrane, tethering them at the active zone prior to reception of a nerve impulse. Our previous studies indicated that Myosin 5a is expressed and functionally relevant in the peripheral nerves of visceral organs such as the stomach and the corpora cavernosa. However, its potential role in bladder neurotransmission has not previously been investigated. The expression of Myosin 5a was examined by quantitative PCR and restriction analyses in bladders from DBA (dilute-brown-nonagouti) mice which express a Myosin 5a splicing defect and in control mice expressing the wild-type Myosin 5a allele. Functional differences in contractile responses to intramural nerve stimulation were examined by ex vivo isometric tension analysis. Data demonstrated Myosin 5a localized in cholinergic nerve fibers in the bladder and identified several Myosin 5a splice variants in the detrusor. Full-length Myosin 5a transcripts were less abundant and the expression of splice variants was altered in DBA bladders compared to control bladders. Moreover, attenuation of neurally-mediated contractile responses in DBA bladders compared to control bladders indicates that Myosin 5a facilitates excitatory neurotransmission in the bladder. Therefore, the array of Myosin 5a splice variants expressed, and the abundance of each, may be critical parameters for efficient synaptic vesicle transport and neurotransmission in the urinary bladder.

Diabetic bladder dysfunction progresses from an overactive to an underactive phenotype in a type-1 diabetic mouse model (Akita female mouse) and is dependent on NLRP3

AIMS

Diabetic bladder dysfunction (DBD) is a prevalent diabetic complication thought to progress from overactive (OAB) to underactive (UAB) bladder. Previously we found OAB at 15 weeks in the Akita mouse, a genetic model of Type 1 diabetes. The first aim of this study assesses bladder function at 30 weeks to assess progression. In addition, inflammation triggered by the NLRP3 inflammasome is implicated in DBD. In a second aim we assessed a role for NLRP3 by crossing Akita mice with NLRP3-/- mice.

MAIN METHODS

Akita mice were bred with NLRP3-/- mice. The effect of diabetes was assessed by comparing nondiabetic to diabetic mice (all NLRP3+/+). The effect of diabetes in the absence of the NLRP3 inflammasome was assessed by comparing nondiabetic/NLRP3-/- to diabetic/NLRP3-/- mice. Mice were assessed at 30 weeks for blood glucose (glucometer), inflammation (Evans blue), bladder morphology (histology) and bladder function (urodynamics).

KEY FINDINGS

At 30 weeks blood glucose of nondiabetics and diabetics was not affected by the presence of absence of NLRP3. Diabetic/NLRP3+/+ mice showed bladder inflammation and detrusor hypertrophy which was blocked in the diabetic/NLRP3-/- mice, clearly showing a role for NLRP3. When bladder function was examined, diabetic/NLRP3+/+ showed an increase in voiding volume and a decrease in frequency, two signs of underactive bladder. However, in the NLRP3-/- mice, diabetes was unable to effectuate these changes, demonstrating that NLRP3-induced inflammation is responsible for UAB symptoms in these mice.

SIGNIFICANCE

Akita diabetic mice progress from OAB to UAB. NLRP3 is a possible target to treat DBD.

Enhanced RAGE Expression and Excess Reactive-Oxygen Species Production Mediates Rho Kinase-Dependent Detrusor Overactivity After Methylglyoxal Exposure

Methylglyoxal (MGO) is a highly reactive dicarbonyl compound implicated in diabetes-associated diseases. In vascular tissues, MGO induces the formation of advanced glycation end products (AGEs) that bounds its receptor RAGE, initiating the downstream tissue injury. Outside the cardiovascular system, MGO intake produces mouse voiding dysfunction and bladder overactivity. We have sought that MGO-induced bladder overactivity is due to activation of AGE-RAGE-reactive-oxygen species (ROS) signaling cascade, leading to Rho kinase activation. Therefore, female mice received 0.5% MGO orally for 12 weeks, after which in vitro bladder contractions were evaluated in the presence or not of superoxide dismutase (PEG-SOD) or the Rho kinase inhibitor Y27632. Treatment with MGO significantly elevated the serum levels of MGO and fluorescent AGEs, as well as the RAGE immunostaining in the urothelium, detrusor, and vascular endothelium. RAGE mRNA expression in the bladder was also higher in the MGO group. Methylglyoxal significantly increased the ROS production in both urothelium and detrusor smooth muscle, with the increases in detrusor markedly higher than urothelium. The bladder activity of superoxide dismutase (SOD) was significantly reduced in the MGO group. Gene expressions of L-type Ca²⁺ channels, RhoA, ROCK-1, and ROCK-2 in bladder tissues were significantly elevated in the MGO group. Increased bladder contractions to electrical-field stimulation, carbachol α,β-methylene ATP, and extracellular Ca²⁺ were observed after MGO exposure, which was significantly reduced by prior incubation with either PEG-SOD or Y27632. Overall, our data indicate serum MGO accumulation elevates the AGEs levels and activates the RAGE-ROS signaling leading to Rho kinase-induced muscle sensitization, ultimately leading to detrusor overactivity.

Metformin abrogates the voiding dysfunction induced by prolonged methylglyoxal intake

Methylglyoxal (MGO) is a reactive carbonyl species found at high levels in blood of diabetic patients. The anti-hyperglycemic drug metformin can scavenger MGO and reduce the formation of advanced glycation end products (AGEs). Here, we aimed to investigate if MGO-induced bladder dysfunction can be reversed by metformin. Male C57/BL6 mice received 0.5% MGO in drinking water for 12 weeks, and metformin (300 mg/kg, daily gavage) was given in the last two weeks. The bladder functions were evaluated by performing voiding behavior assays, cystometry and in vitro bladder contractions. MGO intake markedly elevated the levels of MGO and fluorescent AGEs in serum and reduced the mRNA expression and activity of glyoxalase (Glo1) in bladder tissues. Glucose levels were unaffected among groups. MGO intake also increased the urothelium thickness and collagen content of the bladder. Void spot assays in conscious mice revealed an increased void volume in MGO group. The cystometric assays in anesthetized mice revealed increases of basal pressure, non-voiding contractions frequency, bladder capacity, inter-micturition pressure and residual volume, which were accompanied by reduced voiding efficiency in MGO group. In vitro bladder contractions to carbachol, α,β-methylene ATP and electrical-field stimulation were significantly greater in MGO group. Metformin normalized the changes of MGO and AGEs levels, Glo1 expression and activity, urothelium thickness and collagen content. The MGO-induced voiding dysfunction were all restored by metformin treatment. Our findings strongly suggest that the amelioration of MGO-induced voiding dysfunction by metformin relies on its ability to scavenger MGO, preventing its accumulation in blood.

Intravesical Instillation of Norketamine, a Ketamine Metabolite, and Induced Bladder Functional Changes in Rats

This study aimed to determine the mechanism of ketamine-induced cystitis without metabolism. A total of 24 adult male Sprague-Dawley rats were separated into control, ketamine, and norketamine groups. To induce cystitis, rats in the ketamine and norketamine groups were treated with intravesical instillation of ketamine and norketamine by mini-osmotic pump, which was placed in subcutaneous space, daily for 24 h for 4 weeks. After 4 weeks, all rats were subjected to bladder functional tests. The bladders were collected for histological and pathological evaluation. Compared to control, ketamine treatment demonstrated an increase in the bladder weight, high bladder/body coefficient, contractive pressure, voiding volume, collagen deposition, reduced smooth muscle content, damaged glycosaminoglycan layer, and low bladder compliance. Compared to ketamine, norketamine treatment showed more severe collagen deposition, smooth muscle loss, damaged glycosaminoglycan layer, and increased residual urine. Intravesical administration of ketamine and norketamine induced cystitis with different urodynamic characteristics. Norketamine treatment caused more severe bladder dysfunction than ketamine treatment. Direct treatment of the bladder with norketamine induced symptoms more consistent with those of bladder outlet obstruction than ketamine cystitis. Detailed studies of cellular mechanisms are required to determine the pathogenesis of ketamine cystitis.

IR-61 Improves Voiding Function via Mitochondrial Protection in Diabetic Rats

Diabetic bladder dysfunction (DBD) afflicts nearly half of diabetic patients, but effective treatment is lacking. In this study, IR-61, a novel heptamethine cyanine dye with potential antioxidant effects, was investigated to determine whether it can alleviate DBD. Rats were intraperitoneally injected with IR-61 or vehicle after diabetes was induced with streptozotocin. Before evaluating the effects of IR-61 in improving DBD by filling cystometry, we detected its distribution in tissues and subcellular organelles by confocal fluorescence imaging. Near infrared (NIR) imaging showed that IR-61 could accumulate at high levels in the bladders of diabetic rats, and confocal images demonstrated that it was mainly taken up by bladder smooth muscle cells (BSMCs) and localized in mitochondria. Then, filling cystometry illustrated that IR-61 significantly improved the bladder function of diabetic rats. The histomorphometry results showed that IR-61 effectively mitigated the pathological changes in bladder smooth muscle (BSM) in diabetic rats. Furthermore, IR-61 remarkably reduced the number of apoptotic BSMCs and the unfavorable expression of proteins related to the mitochondrial apoptotic pathway (Bcl-2, BAX, Cytochrome C, and cleaved Caspase-9) in diabetic rats. Moreover, the frozen section staining and transmission electron microscopy results proved that IR-61 significantly reduced the reactive oxygen species (ROS) levels and prevented the mitochondrial mass and morphology damage in the BSM of diabetic rats. In addition, IR-61 upregulated the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and its associated antioxidant proteins in the BSM of diabetic rats. Together, these results indicate that IR-61 can improve the voiding function of rats with DBD by protecting the mitochondria of BSMCs from oxidative stress, which is possibly mediated through the activation of the Nrf2 pathway.

Urethral dysfunction in a rat model of chemically induced prostatic inflammation: potential involvement of the MRP5 pump

Prostate inflammation (PI) is a clinical condition associated with infection and/or inflammation of the prostate. It is a common disease frequently associated to lower urinary tract (LUT) symptoms. The urethra is an understudied structure in the LUT and plays a fundamental role in the urinary cycle. Here, we proposed to evaluate the effect of PI on the urethra tissue. Male Sprague-Dawley rats were used, and PI was induced by formalin injection into the ventral lobes of the prostate. The pelvic urethra at the prostatic level was harvested for histological analysis, contraction (electrical field stimulation and phenylephrine), and relaxation (sodium nitroprusside/MK-571) experiments. Various gene targets [cytochrome c oxidase subunit 2, transforming growth factor-β₁, interleukin-1β, hypoxia-inducible factor-1α, α_1A-adrenoceptor, inositol 1,4,5-trisphosphate receptor type 1, voltage-gated Ca²⁺ channel subunit-α_1D, neuronal nitric oxide synthase, soluble guanylyl cyclase, phosphodiesterase 5A, protein kinase CGMP-dependent 1, and multidrug resistance-associated protein 5 (MRP5; ATP-binding cassette subfamily C member 5)] were quantified, and cGMP levels were measured. No histological changes were detected, and functional assays revealed decreased contraction and increased relaxation of urethras from the PI group. The addition of MK-571 to functional assays increased urethral relaxation. Genes associated with inflammation were upregulated in urethras from the PI group, such as cytochrome oxidase c subunit 2, transforming growth factor-β₁, interleukin-1β, and hypoxia-inducible factor-1α. We also found increased expression of L-type Ca²⁺ channels and the neuronal nitric oxide synthase enzyme and decreased expression of the MRP5 pump. Finally, cGMP production was enhanced in urethral tissue of PI animals. The results indicate that PI is associated with proinflammatory gene expression in the urethra without histologically evident inflammation and that PI produces a dysfunctional urethra and MRP5 pump downregulation, which results in cGMP accumulation inside the cell. These findings would help to better understand LUT dysfunctions associated with PI and the role of MRP pumps in the control of LUT function.

Time-dependent functional, morphological, and molecular changes in diabetic bladder dysfunction in streptozotocin-induced diabetic mice

AIM

Diabetic bladder dysfunction (DBD) is one of the most common and bothersome complications of diabetes mellitus (DM). This study aimed to investigate the functional, structural, and molecular changes of the bladder at 0, 3, 6, 9, and 12 weeks after DM induction by streptozotocin (STZ) in male C57BL/6 mice.

METHODS

Male C57BL/6J mice were injected with STZ (130 mg/kg). Then, diabetic general characteristics, cystometry test, histomorphometry, and contractile responses to α, β-methylene ATP, KCl, electrical-field stimulation, carbachol were performed at 0, 3, 6, 9, and 12 weeks after induction. Finally, protein and messenger RNA (mRNA) expressions of myosin Va and SLC17A9 were quantified.

RESULTS

DM mice exhibited lower body weight, voiding efficiency and higher water intake, urine production, fasting blood glucose, oral glucose tolerance test, bladder wall thickness, maximum bladder capacity, residual volume, bladder compliance. In particular, nonvoiding contractions has increased more than five times at 6 weeks. And the amplitudes of spontaneous activity, contractile responses to all stimulus was about two times higher at 6 weeks but cut almost in half at 12 weeks. The protein and mRNA expressions of myosin Va and SLC17A9 were about two times higher at 6 weeks, but myosin Va was reverted nearly 40% while SLC17A9 is still higher at 12 weeks.

CONCLUSIONS

DBD transitioned from a compensated state to a decompensated state in STZ-induced DM mice at 9 to 12 weeks after DM induction. Our molecular data suggest that the transition may be closely related to the alterations of myosin Va and SLC17A9 expression levels in the bladder with time.