Human bladder smooth muscle cell damage in disturbed oxygen tension

Time-dependent arachidonic acid metabolism and functional changes in rats bladder tissue after suprasacral spinal cord injury

BACKGROUND

A critical aspect affecting the quality of life in Traumatic spinal cord injury (TSCI) patients is bladder dysfunction. Metabolities in arachidonic acid are crucial lipid signaling molecules involved innumerous physiological processes. In this study, We are the first use eicosanoid metabolomics detrusor contraction examine, to assess the effect of the arachidonic acid metabolic in bladder dysfunction following TSCI. In additon, we explore the time of inflammatory and function changes in bladder tissue.

METHODS

Adult male Sprague-Dawley rats were subjected to improved Weight Drop method surgeries. Detrusor contraction examination, urodynamic examination, eicosanoid metabolomics, transmission electron microscopy, Elisa and histological staining were performed to assess the change of inflammatory, metabolic and function variation over time after TSCI.

RESULTS

Following TSCI, before the variations of bladder function, inflammatory changes including the increase of inflammatory factors, mitochondrial damage, and slight lipid peroxidation, occurred in bladder tissue. And the inflammatory changes gradually decreases over time. However, From the third day after TSCI, secondary lesions appeared in bladder tissue. Not only did inflammation-related indexes increase again, the degree of mitochondrial damage and lipid peroxidation increased, but also the contractility of detrusor began to change significantly. We also found that the content of metabolites in arachidonic acid metabolic pathway and the degree of detrusor contractility change showed a strong correlation. In addition, we found that rats had moved beyond the spinal shock stage on the seventh day after TSCI.

CONCLUSION

Altogether, we are the first to demonstrate that abnormal arachidonic acid metabolism plays an important role in bladder dysfunction after TSCI. We also demonstrate that 3d is a critical juncture for changes in rat bladder tissue, which indicates it is an important juncture in the treatment of neurogenic bladder.

Molecular Regulation of Concomitant Lower Urinary Tract Symptoms and Erectile Dysfunction in Pelvic Ischemia

Aging correlates with greater incidence of lower urinary tract symptoms (LUTS) and erectile dysfunction (ED) in the male population where the pathophysiological link remains elusive. The incidence of LUTS and ED correlates with the prevalence of vascular risk factors, implying potential role of arterial disorders in concomitant development of the two conditions. Human studies have revealed lower bladder and prostate blood flow in patients with LUTS suggesting that the severity of LUTS and ED correlates with the severity of vascular disorders. A close link between increased prostatic vascular resistance and greater incidence of LUTS and ED has been documented. Experimental models of atherosclerosis-induced chronic pelvic ischemia (CPI) showed increased contractile reactivity of prostatic and bladder tissues, impairment of penile erectile tissue relaxation, and simultaneous development of detrusor overactivity and ED. In the bladder, short-term ischemia caused overactive contractions while prolonged ischemia provoked degenerative responses and led to underactivity. CPI compromised structural integrity of the bladder, prostatic, and penile erectile tissues. Downstream molecular mechanisms appear to involve cellular stress and survival signaling, receptor modifications, upregulation of cytokines, and impairment of the nitric oxide pathway in cavernosal tissue. These observations may suggest pelvic ischemia as an important contributing factor in LUTS-associated ED. The aim of this narrative review is to discuss the current evidence on CPI as a possible etiologic mechanism underlying LUTS-associated ED.

Oxidative Stress Biomarkers in Age-Related Lower Urinary Tract Disorders: A Systematic Review

PURPOSE

To conduct a systematic review of preclinical and clinical peer-reviewed evidence linking alterations in oxidative stress biomarkers or outcome measures that were also prevalent in specific age-related lower urinary tract (LUT) disorders.

METHODS

PubMed, Scopus, CINAHL, and Embase were searched for peer-reviewed studies published between January 2000 and March 2021. Animal and human studies that reported on the impact of oxidative stress in age-related LUT disorders through structural or functional changes in the LUT and changes in biomarkers were included. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) protocol was followed.

RESULTS

Of 882 articles identified, 21 studies (13 animal; 8 human) met inclusion criteria. Across LUT disorders, common structural changes were increased bladder and prostate weights, ischemic damage, nerve damage and detrusor muscle hypertrophy; common functional changes included decreased bladder contraction, increased bladder sensation and excitability, decreased perfusion, and increased inflammation. The disorders were associated with increased levels of biomarkers of oxidative stress that provided evidence of either molecular damage, protective mechanisms against oxidative stress, neural changes, or inflammation. In all cases, the effect on biomarkers and enzymes was greater in aged groups compared to younger groups.

CONCLUSION

Increased oxidative stress, often associated with mitochondrial dysfunction, plays a significant role in the pathogenesis of age-related LUT disorders and may explain their increasing prevalence. This systematic review identifies potential markers of disease progression and treatment opportunities; further research is warranted to evaluate these markers and the mechanisms by which these changes may lead to age-related LUT disorders.

Post-Translational Modification Networks of Contractile and Cellular Stress Response Proteins in Bladder Ischemia

Molecular mechanisms underlying bladder dysfunction in ischemia, particularly at the protein and protein modification levels and downstream pathways, remain largely unknown. Here we describe a comparison of protein sequence variations in the ischemic and normal bladder tissues by measuring the mass differences of the coding amino acids and actual residues crossing the proteome. A large number of nonzero delta masses (11,056) were detected, spanning over 1295 protein residues. Clustering analysis identified 12 delta mass clusters that were significantly dysregulated, involving 30 upregulated (R² > 0.5, ratio > 2, p < 0.05) and 33 downregulated (R² > 0.5, ratio < −2, p < 0.05) proteins in bladder ischemia. These protein residues had different mass weights from those of the standard coding amino acids, suggesting the formation of non-coded amino acid (ncAA) residues in bladder ischemia. Pathway, gene ontology, and protein–protein interaction network analyses of these ischemia-associated delta-mass containing proteins indicated that ischemia provoked several amino acid variations, potentially post-translational modifications, in the contractile proteins and stress response molecules in the bladder. Accumulation of ncAAs may be a novel biomarker of smooth muscle dysfunction, with diagnostic potential for bladder dysfunction. Our data suggest that systematic assessment of global protein modifications may be crucial to the characterization of ischemic conditions in general and the pathomechanism of bladder dysfunction in ischemia.

Oxidative stress in the bladder of men with LUTS undergoing open prostatectomy: a pilot study

Purpose:

This study aims to evaluate the link between preoperative parameters and oxidative stress (OS) markers in the bladder wall of men undergoing open prostatectomy.

Materials and Methods:

From July 2014 to August 2016, men aged ≥ 50 years and presenting with LUTS were prospectively enrolled. Preoperative assessment included validated questionnaires (IPSS and OAB - V8), lower urinary tract ultrasound and urodynamics. Bladder biopsies were taken during open prostatectomy for determination of OS markers. Increased OS was defined by increased concentration of malondialdehyde (MDA) and / or decreased concentration of antioxidant enzymes (superoxide dismutase and / or catalase). P<0.05 was regarded as statistically significant.

Results:

Thirty - eight consecutive patients were included. Mean age was 66.36 ± 6.44 years, mean prostate volume was 77.7 ± 20.63 cm3, and mean IPSS was 11.05 ± 8.72 points. MDA concentration was increased in men with severe bladder outlet obstruction (BOO grade V - VI according to the Schaefer's nomogram) in comparison with BOO grade III - IV (p = 0.022). Patients with severe LUTS also had higher MDA concentration when compared to those with mild LUTS (p = 0.031). There was a statistically significant association between increased post - void residual urine (cut off ≥ 50 mL) and not only higher levels of MDA, but also reduced activity of SOD and catalase (p < 0.05).

Conclusions:

This pilot study showed that severity of LUTS and BOO were associated with increased MDA concentration in the bladder wall of men undergoing open prostatectomy. Further studies are still needed to assess the role of non - invasive biomarkers of OS in predicting bladder dysfunction in men with LUTS.

Mitochondrial stress and activation of PI3K and Akt survival pathway in bladder ischemia

PURPOSE

Detrusor overactivity contributes to bothersome constellation of lower urinary tract symptoms (LUTS) in men and women as they age. However, the underlying mechanisms of non-obstructive detrusor overactivity and LUTS remain largely unknown. Growing evidence suggests that ischemia may be an independent factor in the development of non-obstructive bladder dysfunction. Our goal was to determine the effects of ischemia on detrusor function and voiding behavior and define redox-mediated cellular stress and cell survival signaling in the ischemic bladder.

MATERIALS AND METHODS

Male Sprague Dawley rats were randomly divided into treatment (n=8) and control (n=8) groups. In the treatment group, iliac artery atherosclerosis and chronic bladder ischemia were induced. At 8 weeks after bladder ischemia, voiding patterns were examined in metabolic cages, cystometrograms were recorded in conscious animals, and then bladder blood flow was measured under general anesthesia. Bladder tissues were processed for assessment of transcription factors, markers of cellular and mitochondrial stress, mitochondrial respiration, and cell survival signaling pathway.

RESULTS

Atherosclerotic occlusive disease spread from the common iliac arteries to the internal iliac and vesical arteries and produced sustained bladder ischemia. Studies in metabolic cages showed increased micturition frequency and decreased voided volume in bladder ischemia. Conscious cystometrograms produced consistent data showing significant increase in micturition frequency and decreased voided volume and bladder capacity. Voiding behavior and cystometric changes in bladder ischemia were associated with significant decrease in DNA binding activity of Nrf2, significant increase in cellular levels of stress protein Hsp70 and mitochondrial stress protein GRP75, and significant decrease in mitochondrial oxygen consumption and upregulation of PI3K and Akt expression.

CONCLUSION

Chronic bladder ischemia may be a mediating variable in the development of detrusor overactivity in the non-obstructive bladder. The mechanism may involve ischemia-induced cellular stress, Nrf2 functional deficit, depression of mitochondrial respiration, and upregulation of PI3K/Akt cell survival signaling pathway.

LUTS in pelvic ischemia: a new concept in voiding dysfunction

Lower urinary tract symptoms (LUTS) are a group of voiding symptoms affecting both genders as they age. Traditionally, LUTS in men were commonly attributed to bladder outlet obstruction (BOO) due to benign prostatic enlargement (BPE). It was later shown that, in approximately one-third to more than one-half of cases, LUTS in men are not associated with BOO. Urodynamic changes in the male bladder and symptom scores in aging men were found to be identical to their age-matched female counterparts. These observations suggested that LUTS in the elderly do not necessarily relate to BOO and may result from local changes in bladder muscle, nerves, and blood vessels. However, aging factors predisposing to bladder dysfunction and LUTS remain unknown. Growing evidence suggests that aging-associated pelvic ischemia may be a primary factor in the development of nonobstructed nonneurogenic overactive bladder and LUTS. First identified in experimental models and later in clinical studies, pelvic ischemia has been shown to compromise the lower urinary tract structure and lead to dysfunction. Structural and functional consequences of bladder and prostate ischemia have been documented in animal models. Clinical studies have shown that bladder and prostate blood flow decreases with aging. The severity of LUTS in elderly patients correlates with the degrees of bladder ischemia. LUTS improvement with α blockers has been associated with increased bladder blood flow. Pelvic ischemia may be an independent factor in nonobstructed nonneurogenic bladder instability and LUTS. Further research into the pathophysiology of LUTS in pelvic ischemia may lead to better management of this problem in the elderly population.

Structural modifications of the prostate in hypoxia, oxidative stress, and chronic ischemia

PURPOSE

Clinical studies have reported a correlation between pelvic ischemia and voiding dysfunction in elderly men. The aim of this study was to identify and compare prostate structural modifications in cultured cells and in a rabbit model after exposure to hypoxia, oxidative stress, and chronic ischemia.

MATERIALS AND METHODS

Cultured human prostate smooth muscle cells (SMCs), epithelial cells (ECs), and stromal cells (SCs) were incubated under normoxia, hypoxia, and oxidative stress conditions by use of a computerized oxycycler system. We developed a rabbit model of chronic prostate ischemia by creating aorto-iliac arterial atherosclerosis. Markers of oxidative stress were examined by using fluorometric analysis and enzyme immunoassay. Prostate structure was examined by using Masson's trichrome staining and transmission electron microscopy (TEM).

RESULTS

Lipid peroxidation was found in SMCs exposed to hypoxia and in all cell types exposed to oxidative stress. We identified protein oxidation in ECs exposed to hypoxia and in all cell types exposed to oxidative stress. Markers indicating oxidative damage were present in chronically ischemic rabbit prostate tissue. These reactions were associated with DNA damage. Prostate ischemia resulted in epithelial atrophy, loss of smooth muscle, and diffuse fibrosis. TEM showed swollen mitochondria with degraded cristae, loss of membrane, loss of Golgi bodies, degenerated nerves, and disrupted cell-to-cell junctions.

CONCLUSIONS

Human prostate cells exhibited differential reactions to hypoxia and oxidative stress with widespread DNA damage. Structural modifications in ischemic prostate tissue were similar to those in cells exposed to oxidative stress. Structural changes due to ischemia and oxidative stress may contribute to prostatic noncompliance in aging men.

Effects of ischemia and oxidative stress on bladder purinoceptors expression

OBJECTIVE

To study the effects of chronic ischemia on bladder purinoceptors. A close correlation between bladder ischemia and lower urinary tract symptoms has been reported. Purinoceptors contribute to important aspects of bladder function including sensation, neural signaling, and voiding contraction. Our goal was to examine purinoceptors expression in the ischemic overactive bladder.

MATERIALS AND METHODS

Moderate bladder ischemia was produced in rabbits by creating bilateral iliac artery atherosclerosis. After 8 weeks, bladder blood flow was measured, and cystometrograms were obtained. Bladder tissues from 8-week ischemic and age-matched control bladders were processed for the analysis of oxidative stress markers, P2X and P2Y purinoceptors expression, and transmission electron microscopy.

RESULTS

Arterial atherosclerosis significantly decreased bladder blood flow. Markers of oxidative stress characterized by increased levels of advanced oxidation protein products and malondialdehyde were evident in the ischemic bladder tissues. Chronic ischemia and oxidative stress decreased the bladder capacity and increased spontaneous bladder contractions. Bladder pressure at micturition and intravesical pressure rise during contractions tended to be greater in the ischemic bladder but did not reach significance. Transmission electron microscopy showed smooth muscle cell and microvasculature structural damage and diffuse fibrosis. These changes in the ischemic bladder were associated with significant increases in purinoceptors P2X1, P2X2, P2X3, P2X4, P2X5, and P2X7 expression. The P2Y isoforms were not expressed in the rabbit bladder.

CONCLUSION

Structural and functional changes in the chronically ischemic bladder were associated with upregulation of P2X receptor isoforms. Increased P2X expression may play a role in ischemia-induced bladder overactivity and noncompliance.

Association between physical activity, lower urinary tract symptoms (LUTS) and prostate volume

OBJECTIVES

To determine the association between lower urinary tract symptoms (LUTS) severity and physical activity (PA) across workplace, home, and leisure domains. To determine the mediating role of prostate enlargement on LUTS severity and PA.

PATIENTS AND METHODS

The study included 405 men without prostate cancer or prostatic intraepithelial neoplasia. LUTS severity was ascertained using the American Urological Association Symptom Index and prostate size by ultrasonography. PA was assessed using validated questionnaires, with conversion to metabolic equivalent of task (MET)-h/week to estimate leisure-time PA energy expenditure. Analysis used multivariable linear regression, controlling for body mass index (BMI), age, race, and treatment for benign prostatic hyperplasia, cardiovascular disease and diabetes.

RESULTS

Higher leisure-time PA energy expenditure and light housework activities were significantly associated with lower LUTS severity. Prostate volume was not significantly associated with PA in adjusted analyses, and controlling for prostate volume did not affect the association between LUTS severity and PA. Stratification by BMI showed a moderate interaction (P = 0.052), suggesting that PA was more strongly associated with LUTS severity among obese men.

CONCLUSIONS

In this cross-sectional analysis, leisure-time and home-time PA was inversely associated with LUTS severity. The association between PA and LUTS severity was stronger for irritative symptoms and among obese men, and was not mediated through changes in prostate size. Our results indicate the need for further detailed investigation of PA and LUTS.