Influence of the periprostatic adipose tissue in obesity-associated mouse urethral dysfunction and oxidative stress: Effect of resveratrol treatment

Impact of intravascular hemolysis on functional and molecular alterations in the urinary bladder: implications for an overactive bladder in sickle cell disease

Patients with sickle cell disease (SCD) display an overactive bladder (OAB). Intravascular hemolysis in SCD is associated with various severe SCD complications. However, no experimental studies have evaluated the effect of intravascular hemolysis on bladder function. This study aimed to assess the effects of intravascular hemolysis on the micturition process and the contractile mechanisms of the detrusor smooth muscle (DSM) in a mouse model with phenylhydrazine (PHZ)-induced hemolysis; furthermore, it aimed to investigate the role of intravascular hemolysis in the dysfunction of nitric oxide (NO) signaling and in increasing oxidative stress in the bladder. Mice underwent a void spot assay, and DSM contractions were evaluated in organ baths. The PHZ group exhibited increased urinary frequency and increased void volumes. DSM contractile responses to carbachol, KCl, α-β-methylene-ATP, and EFS were increased in the PHZ group. Protein expression of phosphorylated endothelial NO synthase (eNOS) (Ser-1177), phosphorylated neuronal NO synthase (nNOS) (Ser-1417), and phosphorylated vasodilator-stimulated phosphoprotein (VASP) (Ser-239) decreased in the bladder of the PHZ group. Protein expression of oxidative stress markers, NOX-2, 3-NT, and 4-HNE, increased in the bladder of the PHZ group. Our study shows that intravascular hemolysis promotes voiding dysfunction correlated with alterations in the NO signaling pathway in the bladder, as evidenced by reduced levels of p-eNOS (Ser-1177), nNOS (Ser-1417), and p-VASP (Ser-239). The study also showed that intravascular hemolysis increases oxidative stress in the bladder. Our study indicates that intravascular hemolysis promotes an OAB phenotype similar to those observed in patients and mice with SCD.

Methylglyoxal and Advanced Glycation End Products (AGEs): Targets for the Prevention and Treatment of Diabetes-Associated Bladder Dysfunction?

Methylglyoxal (MGO) is a highly reactive α-dicarbonyl compound formed endogenously from 3-carbon glycolytic intermediates. Methylglyoxal accumulated in plasma and urine of hyperglycemic and diabetic individuals acts as a potent peptide glycation molecule, giving rise to advanced glycation end products (AGEs) like arginine-derived hydroimidazolone (MG-H1) and carboxyethyl-lysine (CEL). Methylglyoxal-derived AGEs exert their effects mostly via activation of RAGE, a cell surface receptor that initiates multiple intracellular signaling pathways, favoring a pro-oxidant environment through NADPH oxidase activation and generation of high levels of reactive oxygen species (ROS). Diabetic bladder dysfunction is a bothersome urological complication in patients with poorly controlled diabetes mellitus and may comprise overactive bladder, urge incontinence, poor emptying, dribbling, incomplete emptying of the bladder, and urinary retention. Preclinical models of type 1 and type 2 diabetes have further confirmed the relationship between diabetes and voiding dysfunction. Interestingly, healthy mice supplemented with MGO for prolonged periods exhibit in vivo and in vitro bladder dysfunction, which is accompanied by increased AGE formation and RAGE expression, as well as by ROS overproduction in bladder tissues. Drugs reported to scavenge MGO and to inactivate AGEs like metformin, polyphenols, and alagebrium (ALT-711) have shown favorable outcomes on bladder dysfunction in diabetic obese leptin-deficient and MGO-exposed mice. Therefore, MGO, AGEs, and RAGE levels may be critically involved in the pathogenesis of bladder dysfunction in diabetic individuals. However, there are no clinical trials designed to test drugs that selectively inhibit the MGO-AGEs-RAGE signaling, aiming to reduce the manifestations of diabetes-associated bladder dysfunction. This review summarizes the current literature on the role of MGO-AGEs-RAGE-ROS axis in diabetes-associated bladder dysfunction. Drugs that directly inactivate MGO and ameliorate bladder dysfunction are also reviewed here.

Periprostatic adipose tissue (PPAT) supernatant from obese mice releases anticontractile substances and increases human prostate epithelial cell proliferation: the role of nitric oxide and adenosine

Background: The prostate gland is surrounded by periprostatic adipose tissue (PPAT) that can release mediators that interfere in prostate function. In this study, we examined the effect of periprostatic adipose tissue supernatant obtained from obese mice on prostate reactivity in vitro and on the viability of human prostatic epithelial cell lines. Methods: Male C57BL/6 mice were fed a standard or high-fat diet after which PPAT was isolated, incubated in Krebs-Henseleit solution for 30 min (without prostate) or 60 min (with prostate), and the supernatant was then collected and screened for biological activity. Total nitrate and nitrite (NOx^-) and adenosine were quantified, and the supernatant was then collected and screened for biological activity. NOx^- and adenosine were quantified. Concentration-response curves to phenylephrine (PE) were obtained in prostatic tissue from lean and obese mice incubated with or without periprostatic adipose tissue. In some experiments, periprostatic adipose tissue was co-incubated with inhibitors of the nitric oxide (NO)-cyclic guanosine monophosphate pathway (L-NAME, 1400W, ODQ), adenylate cyclase (SQ22536) or with adenosine A_2A (ZM241385), and A_2B (MRS1754) receptor antagonists. PNT1-A (normal) and BPH-1 (hyperplasic) human epithelial cells were cultured and incubated with supernatant from periprostatic adipose tissue for 24, 48, or 72 h in the absence or presence of these inhibitors/antagonists, after which cell viability and proliferation were assessed. Results: The levels of NOx^- and adenosine were significantly higher in the periprostatic adipose tissue supernatant (30 min, without prostate) when compared to the vehicle. A trend toward an increase in the levels of NOX was observed after 60 min. PPAT supernatant from obese mice significantly reduced the PE-induced contractions only in prostate from obese mice. The co-incubation of periprostatic adipose tissue with L-NAME, 1400W, ODQ, or ZM241385 attenuated the anticontractile activity of the periprostatic adipose tissue supernatant. Incubation with the supernatant of periprostatic adipose tissue from obese mice significantly increased the viability of PNT1-A cells and attenuated expression of the apoptosis marker protein caspase-3 when compared to cells incubated with periprostatic adipose tissue from lean mice. Hyperplastic cells (BPH-1) incubated with periprostatic adipose tissue from obese mice showed greater proliferation after 24 h, 48 h, and 72 h compared to cells incubated with culture medium alone. BPH-1 cell proliferation in the presence of PPAT supernatant was attenuated by NO-signaling pathway inhibitors and by adenosine receptor antagonists after 72 h. Conclusion: NO and adenosine are involved in the anticontractile and pro-proliferative activities of periprostatic adipose tissue supernatant from obese mice. More studies are needed to determine whether the blockade of NO and/or adenosine derived from periprostatic adipose tissue can improve prostate function.

Selective Pharmacological Inhibition of NOX2 by GSK2795039 Improves Bladder Dysfunction in Cyclophosphamide-Induced Cystitis in Mice

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic inflammatory disease without consistently effective treatment. Among the many mediators implicated in cystitis, the overproduction of reactive oxygen species (ROS) seems to play a key role, although the main source of ROS remains unclear. This study aimed to investigate the contribution of NADPH oxidase (NOX) isoforms in ROS generation and the voiding dysfunction of cyclophosphamide (CYP, 300 mg/Kg, ip, 24 h)-induced cystitis in adult female mice, a well-recognized animal model to study IC/BPS, by using GKT137831 (5 mg/Kg, ip, three times in a 24 h period) or GSK2795039 (5 mg/Kg, ip, three times in a 24 h period) to inhibit NOX1/4 or NOX2, respectively. Our results showed that treatment with GSK2795039 improved the dysfunctional voiding behavior induced by CYP, reduced bladder edema and inflammation, and preserved the urothelial barrier integrity and tight junction occludin expression, besides inhibiting the characteristic vesical pain and bladder superoxide anion generation. In contrast, the NOX1/4 inhibitor GKT137831 had no significant protective effects. Taken together, our in vivo and ex vivo data demonstrate that NOX2 is possibly the main source of ROS observed in cystitis-induced CYP in mice. Therefore, selective inhibition of NOX2 by GSK2795039 may be a promising target for future therapies for IC/BPS.

Oxidative Stress: A Putative Link Between Lower Urinary Tract Symptoms and Aging and Major Chronic Diseases

Aging and major chronic diseases are risk factors for lower urinary tract symptoms (LUTS). On the other hand, oxidative stress (OS) is one of the fundamental mechanisms of aging and the development of chronic diseases. Therefore, OS might be a candidate mechanism linking these two clinical entities. This article aims to summarize the studies on the prevalence of LUTS, the role of OS in aging and chronic diseases, and the potential mechanisms supporting the putative link. A comprehensive literature search was performed to identify recent reports investigating LUTS and OS in major chronic diseases. In addition, studies on the impact of OS on the lower urinary tract, including bladder, urethra, and prostate, were collected and summarized. Many studies showed LUTS are prevalent in aging and major chronic diseases, including obesity, metabolic syndrome, diabetes, cardiovascular disease, hypertension, obstructive sleep apnea, autoimmune diseases, Alzheimer’s disease, and Parkinson’s disease. At the same time, OS is a key component in the pathogenesis of those chronic diseases and conditions. Recent studies also provided evidence that exacerbated OS can cause functional and/or structural changes in the bladder, urethra, and prostate, leading to LUTS. The reviewed data support the concept that OS is involved in multiple risk factors-associated LUTS, although further studies are needed to confirm the causative relationship. The specific ROS/RNS and corresponding reactions/pathways involved in chronic diseases and associated LUTS should be identified in the future and could serve as therapeutic targets.

Efficacy of resveratrol in male urogenital tract dysfunctions: an evaluation of pre-clinical data

Resveratrol is a polyphenol found naturally in fruits and plants. Recently, studies in humans and animal models have suggested beneficial properties of this polyphenol, such as improvements to metabolic and lipid profiles, along with antioxidant, anti-inflammatory and anti-proliferative effects. In the urogenital tract (UGT), resveratrol has also been tested clinically and experimentally as a therapeutic drug in several diseases; however, the translational efficacy of resveratrol, especially in UGT, is still a matter of debate. In the present review, we address the pre-clinical efficacy of resveratrol in UGT-related dysfunctions, focusing on lower urinary tract symptoms, non-cancerous prostatic disease (benign prostatic hyperplasia and prostatitis) and erectile dysfunction. In vitro studies indicate that resveratrol reduces inflammatory markers and oxidative stress, and improves endothelial function in UGT organs and cells isolated from humans and animals. Despite displaying low oral bioavailability, in vivo administration of resveratrol largely improves erectile dysfunction, benign prostatic hyperplasia, prostatitis and voiding impairments, as evidenced in different animal models. Resveratrol also acts as a microbiota modulator, which may explain some of its beneficial effects in vivo. In contrast to the large amount of pre-clinical data, there are insufficient clinical trials to establish resveratrol treatment efficacy in human UGT-related diseases. In summary, we provide an overview of the in vivo and in vitro efficacy of resveratrol in animal and human UGT dysfunctions, which may support future clinical trials.

Lipopolysaccharide reduces urethral smooth muscle contractility via cyclooxygenase activation

Lipopolysaccharide (LPS) is a component of gram-negative bacteria wall that elicits inflammatory response in the host through the toll-like receptor 4 (TLR4) activation. In the lower urinary tract (LUT), bacteria-derived LPS has been associated with lower urinary tract symptoms (LUTS); however, little is known about the effects of LPS in the urethral smooth muscle (USM). In the present study, we evaluated the functional and molecular effects of LPS in mouse USM in vitro, focusing on the LPS-induced TLR4-signaling pathway. Male C57BL6/JUnib and TLR4 knockout mice (TLR4 KO) were used. The USM contraction was performed in the presence of LPS (62.5-500 μg/mL), indomethacin (10 μM), L-NAME (100 μM), and TAK 242 (1 μM). The RT-PCR assay for the IL-1β, NF-kB, and COX-2 genes was also evaluated in the presence of LPS (125 μg/mL) and caspase 1 inhibitor (20 μM). Our results showed that LPS reduces mouse USM contraction elicited by phenylephrine and vasopressin. This LPS-induced urethral inhibitory effect was not reversed by the TLR4 inhibition or its absence in the TLR4 KO mice. Conversely, indomethacin (but not L-NAME) reversed the LPS-induced USM hypocontractility. Molecular protocols indicated upregulation of IL-1β, NF-kβ, and COX-2 mRNA upon LPS incubation, which were blunted by caspase 1 inhibition. Our data showed that LPS reduced mouse USM contraction independently of TLR4 activation, involving caspase 1 and IL1β, NF-kB, and COX-2 gene overexpression. Therefore, this alternative pathway might be a valuable target to reduce the LPS-induced urethral dysfunction under infection and inflammatory conditions.

A Brief Overview of Oxidative Stress in Adipose Tissue with a Therapeutic Approach to Taking Antioxidant Supplements

One of the leading causes of obesity associated with oxidative stress (OS) is excessive consumption of nutrients, especially fast-foods, and a sedentary lifestyle, characterized by the ample accumulation of lipid in adipose tissue (AT). When the body needs energy, the lipid is broken down into glycerol (G) and free fatty acids (FFA) during the lipolysis process and transferred to various tissues in the body. Materials secreted from AT, especially adipocytokines (interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α)) and reactive oxygen species (ROS), are impressive in causing inflammation and OS of AT. There are several ways to improve obesity, but researchers have highly regarded the use of antioxidant supplements due to their neutralizing properties in removing ROS. In this review, we have examined the AT response to OS to antioxidant supplements focusing on animal studies. The results are inconsistent due to differences in the study duration and diversity in animals (strain, age, and sex). Therefore, there is a need for different studies, especially in humans.

The Role of Periprostatic Adipose Tissue on Prostate Function in Vascular-Related Disorders

The lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH) are highly prevalent worldwide. Clinical and experimental data suggest that the incidence of LUTS-BPH is higher in patients with vascular-related disorders such as in pelvic ischemia, obesity and diabetes as well as in the ageing population. Obesity is an important risk factor that predisposes to glucose intolerance, insulin resistance, dyslipidemia, type 2 diabetes mellitus and cardiovascular disorders. Prospective studies showed that obese men are more likely to develop LUTS-BPH than non-obese men. Yet, men with greater waist circumferences were also at a greater risk of increased prostate volume and prostate-specific antigen than men with lower waist circumference. BPH is characterized by an enlarged prostate and increased smooth muscle tone, thus causing urinary symptoms. Data from experimental studies showed a significant increase in prostate and epididymal adipose tissue weight of obese mice when compared with lean mice. Adipose tissues that are in direct contact with specific organs have gained attention due to their potential paracrine role. The prostate gland is surrounded by periprostatic adipose tissue (PPAT), which is believed to play a paracrine role by releasing growth factors, pro-inflammatory, pro-oxidant, contractile and anti-contractile substances that interfere in prostate reactivity and growth. Therefore, this review is divided into two main parts, one focusing on the role of adipokines in the context of obesity that can lead to LUTS/BPH and the second part focusing on the mediators released from PPAT and the possible pathways that may interfere in the prostate microenvironment.

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.