The effect of alpha-blocker treatment on bladder hypoxia inducible factor-1 alpha regulation during lower urinary tract obstruction

Metabolic Syndrome and Overactive Bladder Syndrome May Share Common Pathophysiologies

Metabolic syndrome (MetS) is defined by a group of cardiovascular risk factors, including impaired glucose tolerance, central obesity, hypertension, and dyslipidemia. Overactive bladder (OAB) syndrome consists of symptoms such as urinary urgency, frequency, and nocturia with or without urge incontinence. The high prevalences of metabolic syndrome (MetS) and overactive bladder (OAB) worldwide affect quality of life and cause profound negative impacts on the social economy. Accumulated evidence suggests that MetS might contribute to the underlying mechanisms for developing OAB, and MetS-associated OAB could be a subtype of OAB. However, how could these two syndromes interact with each other? Based on results of animal studies and observations in epidemiological studies, we summarized the common pathophysiologies existing between MetS and OAB, including autonomic and peripheral neuropathies, chronic ischemia, proinflammatory status, dysregulation of nutrient-sensing pathways (e.g., insulin resistance at the bladder mucosa and excessive succinate intake), and the probable role of dysbiosis. Since the MetS-associated OAB is a subtype of OAB with distinctive pathophysiologies, the regular and non-specific medications, such as antimuscarinics, beta-3 agonist, and botulinum toxin injection, might lead to unsatisfying results. Understanding the pathophysiologies of MetS-associated OAB might benefit future studies exploring novel biomarkers for diagnosis and therapeutic targets on both MetS and OAB.

DU Is Induced by Low Levels of Urinary ATP in a Rat Model of Partial Bladder Outlet Obstruction: The Incidence of Both Events Decreases after Deobstruction

Objectives. To investigate, in initial phases of bladder outlet obstruction (BOO), the urinary ATP levels, the incidence of detrusor underactivity (DU), and if they change after deobstruction. Methods. Adult female Wistar rats submitted to partial BOO (pBOO) and sham-obstruction were used. Cystometry was performed 3 or 15 days after pBOO and fluid was collected from the urethra for ATP determination. Bladders were harvested for morphological evaluation of the urothelium. DU was defined as the average of voiding contractions (VC) of sham-operated animals, with 3 SD at 15 days after the sham surgery. In another group of animals in which pBOO was relieved at 15 days and bladders were let to recover for 15 days, the incidence of DU and ATP levels were also accessed. The Kruskal–Wallis test was followed by Dunn’s multiple comparisons test, and Spearman’s correlation test was used. Results. DU was present in 13% and 67% of the bladders at 3 and 15 days after pBOO, respectively, and in 20% of the bladders at 15 days after deobstruction. ATP levels were significantly lower in DU/pBOO versus sham and non-DU/pBOO rats. A strong positive correlation between ATP levels and VC/min was obtained (r = 0.63). DU bladders had extensive areas in which umbrella cells appeared stretched, the width exceeding that presented by sham animals. Conclusions. Low urothelial ATP parallels with a high incidence of DU early after pBOO.

The Use of 5-Alpha Reductase Inhibitors and Alpha-1 Blockers Does Not Improve Clinical Outcome in Male Patients Undergoing Radical Cystectomy for Bladder Cancer in Quebec, Canada

BACKGROUND

Existing literature suggests that bladder cancer (BC) outcome may be improved when patients use 5α-reductase inhibitors and/or α₁-blockers, but such a conclusion may be subject to publication bias. We evaluated whether preoperative use of 5α-reductase inhibitors or α₁-blockers was associated with improved clinical outcomes in a cohort of patients with BC undergoing radical cystectomy (RC).

PATIENTS AND METHODS

Using provincial health administrative databases, we retrospectively identified male BC patients undergoing RC in Quebec province between 2000 and 2015, and we collected data from 2 years before RC until December 2016 or death. Survival analyses were conducted using Kaplan-Meier curves, log-rank tests, propensity score matching, and uni- and multivariable Cox proportional hazards models. Covariates included age, Charlson's comorbidity index, region of residence, year of RC, distance to hospital, hospital type, annual RC volume of each hospital and surgeon, neoadjuvant chemotherapy use, and type of bladder diversion.

RESULTS

Of the 2822 patients included, 284 patients used 5α-reductase inhibitors and 1001 patients used α₁-blockers prior to surgery. Median follow-up time was 7.7 years. Patients who used 5α-reductase inhibitors or α₁-blockers were generally older, had more comorbidities, and were treated more recently in academic centers. Overall, bladder cancer-specific and recurrence-free survival did not differ significantly between those using 5α-reductase inhibitors prior to surgery and controls who never used 5α-reductase inhibitors. Adjusted hazard ratios were 1.03 (95% confidence interval [CI], 0.88-1.21) for overall survival, 1.12 (95% CI, 0.92-1.36) for bladder cancer-specific survival, and 1.19 (95% CI, 0.99-1.42) for recurrence-free survival. The aforementioned outcomes were significantly worse in patients who used α1-blockers prior to surgery compared to controls, with respective adjusted hazard ratios of 1.15 (95% CI, 1.04-1.27), 1.19 (95% CI, 1.05-1.35), and 1.18 (95% CI, 1.05-1.33).

CONCLUSION

Preoperative use of 5α-reductase inhibitors and α₁-blockers did not improve clinical outcome in our cohort of male patients undergoing radical cystectomy for bladder cancer.

Evaluation of HIF-1α and VEGF-A expression in radiation-induced cystitis: A case-control study

The standard treatment for locally advanced cervical cancer (CC) is chemoradiotherapy. Once the bladder receives part of the radiation, a typical inflammatory condition that configures radiation-induced cystitis may develop. Chronic radiation-induced cystitis is commonly characterized by the bladder new submucosal vascularization, which is typically fragile and favors hematuria. The current study aims to investigate if Hypoxia-Induced Factor (HIF-1α) and its transcriptional target Vascular Endothelial Growth Factor A (VEGF-A) could be a primary pathway leading to increased submucosal vascularization. HIF-1α and VEGF-A mRNA levels in bladder core biopsies from CC patients treated with radiotherapy versus untreated (non-irradiated) patients were analyzed using a droplet digital polymerase chain reaction technology. Gene expression results showed that HIF-1α and VEGF-A had no significant differences between bladder samples from patients previously irradiated and untreated patient samples. However, a direct relationship between the degree of late morbidity and the expression of HIF-1α and VEGF-A has been demonstrated. Despite the lack of statistical significance precludes a definitive conclusion, the data presented herein suggests that further studies investigating the role of HIF-1α in bladder neovascularization in radiation-induced cystitis are highly recommended.

Effects of varying degrees of partial bladder outlet obstruction on urinary bladder function of rats: A novel link to inflammation, oxidative stress and hypoxia

OBJECTIVES

The aim of the present study was to investigate the effects of different degrees of obstruction, and the roles of inflammation, oxidative stress, and hypoxia parameters on bladder function.

METHODS

Thirty male Sprague-Dawley rats were divided into 3 groups (n = 10 in each group): (i) sham-operated control; (ii) severe partial bladder outlet obstruction (PBOO); and (iii) moderate PBOO. Severe and moderate PBOO were induced by urethral ligation using 3-Fr and 4-Fr catheters, respectively, for 6 weeks. After 6 weeks, the in vitro contractile responses to carbachol, electrical field stimulation, ATP and KCl were measured in bladder strips. In addition, mRNA and protein expression of nuclear factor kappa B (NF-κB) hypoxia-inducible factor (HIF) and nuclear factor, erythroid 2-like 2 (Nrf2) in bladder were determined by real-time polymerase chain reaction and western blotting. Malondialdehyde (MDA) levels in bladder tissues were also determined.

RESULTS

Rats in the severe PBOO group had the highest bladder weight. Detrusor strips from rats in the severe PBOO group exhibited 61%-82% smaller contractile responses to all four stimuli than those from the sham-operated group. Activity of NF-κB as an inflammatory marker was increased in the severe PBOO group, whereas HIF-1α and HIF-2β protein levels were increased significantly in the moderate PBOO group. A master regulator of oxidative stress, Nrf2 expression was increased in all obstructed rats. MDA levels were higher in the severe PBOO group than in sham-operated group.

CONCLUSION

The results of the present study reveal the importance of oxidative stress-induced NF-κB signaling in bladder dysfunction with severe obstruction. Altered HIF signaling may contribute to the functional impairment after PBOO. Novel and evolving therapies targeting oxidative and/or inflammatory pathways may be a reasonable strategy for the management of lower urinary tract symptoms or benign prostatic hyperplasia.

The link between vascular dysfunction, bladder ischemia, and aging bladder dysfunction

The vascular supply to the human bladder is derived mainly from the superior and inferior vesical arteries, the latter being directly connected to the internal iliac artery. Aging is associated with an impairment of blood vessel function and changes may occur in the vasculature at the molecular, cellular and functional level. Pelvic arterial insufficiency may play an important role in the development of bladder dysfunctions such as detrusor overactivity (DO) and the overactive bladder syndrome. Chronic ischemia-related bladder dysfunction may progress to bladder underactivity and it would be desirable to treat not only lower urinary tract symptoms (LUTS) induced by chronic ischemia, but also the progression of the morphological bladder changes. Studies in experimental models in rabbits and rats have shown that pelvic arterial insufficiency may result in significant bladder ischemia with reduced bladder wall oxygen tension. In turn, this will lead to oxidative stress associated with upregulation of oxidative stress-sensitive genes, increased muscarinic receptor activity, ultrastructural damage, and neurodegeneration. The phosphodiesterase type 5 (PDE5) inhibitor tadalafil, the α₁-adrenoceptor (AR) blocker silodosin, the β₃-AR agonist mirabegron, and the free radical scavenger melatonin, exerted a protecting effect on urodynamic parameters, and on functional and morphological changes of the bladder demonstrable in vitro. Since the agents tested are used clinically for relieving LUTS, the results from the animal models seem to have translational value, and may be of relevance for designing clinical studies to demonstrate if the drugs may prevent progression of ischemia-related functional and morphological bladder changes.

Is there a link between overactive bladder and the metabolic syndrome in women? A systematic review of observational studies

OBJECTIVES

To conduct a systematic review to determine whether there is an association between metabolic syndrome (MetS) and lower urinary tract symptoms (LUTS) or overactive bladder (OAB) in women.

METHODS

We systematically reviewed English language observational studies on the effect of MetS (or component factors) on the presence of OAB or LUTS in women. We searched PubMed, Web of Science and The Cochrane Library with no date restrictions, checked reference lists and undertook citation searches in PubMed and Google Scholar. Studies were assessed for risk of bias. Because of heterogeneity, results were not pooled, but are reported narratively.

RESULTS

Of 27 included studies, only three looked at the link between MetS and OAB. The rest looked at links between OAB and components of MetS such as obesity or insulin resistance (n = 10), between MetS and urinary symptoms (n = 3) and between urinary symptoms and components of MetS, such as obesity (n = 14). Evidence is currently limited, but it does suggest that there may be important links between MetS and OAB and components of MetS such as obesity.

CONCLUSIONS

The literature on MetS and OAB or LUTS in women is limited, and poor quality. However, the evidence available on obesity appears to support MetS as a contributor and predictor of LUTS in women. Many of the women with LUTS will be overweight and will have features of the MetS, if looked for. This provides not only an opportunity to encourage weight loss as an adjunct to therapy for the OAB symptoms but also a window of opportunity to address cardiovascular risk factors and prevent future cardiovascular morbidity and mortality.

Functional consequences of chronic bladder ischemia

The pathophysiology of lower urinary tract symptoms (LUTS), particularly in the elderly, seems to be multifactorial. One of the factors involved may be chronic ischemia of the bladder caused by bladder outflow obstruction (male) or atherosclerosis (male/female). The mechanisms by which chronic ischemia initiates and causes LUTS and progressive bladder dysfunction, and the time course of the effects, are incompletely known. Bladder ischemia and repeated ischemia/reperfusion during a micturition cycle may produce oxidative stress, leading to denervation of the bladder and the expression of tissue damaging molecules in the bladder wall. This may be responsible for the development of detrusor overactivity progressing to detrusor underactivity and inability to empty the bladder. The extent of bladder dysfunction in chronic bladder ischemia may depend on the degree and duration of ischemia. To prevent chronic bladder ischemia caused by atherosclerosis and to treat its consequences, more pathophysiological knowledge is needed. Several animal models of atherosclerosis-induced chronic bladder ischemia are available and should be useful tools for further research.