Vardenafil modulates bladder contractility through cGMP-mediated inhibition of RhoA/Rho kinase signaling pathway in spontaneously hypertensive rats

The Cannabinoid Ligand Arachidonyl-2'-Chloroethylamide (ACEA) Ameliorates Depressive and Overactive Bladder Symptoms in a Corticosterone-Induced Female Wistar Rat Model

There is growing need to increase the knowledge on the cannabinoid ligands in the treatment of overactive bladder. Among potential candidates, arachidonyl-2'-chloroethylamide (ACEA), a selective cannabinoid CB1 receptor agonist is proposed. The aim of this paper was to determine if ACEA, a selective cannabinoid CB1 receptor agonist, could reverse the effects of corticosterone (CORT), characteristic of depressive and bladder overactivity potential. The animals (48 female rats) were divided into four groups: I-control, II-received CORT, III-received ACEA, and IV-received the combination of CORT and ACEA. The conscious cystometry, forced swim test (FST), and locomotor activity measurements were performed 3 days after the last dose of ACEA, followed by ELISA measurements. In group IV, ACEA restored urodynamic parameters that were altered by CORT. CORT prolonged the immobility time in FST and the values were lowered by ACEA. ACEA normalized the expression of c-Fos in all the analyzed central micturition centers (group IV vs. group II). ACEA restored the CORT-induced changes in the biomarkers in urine (BDNF, NGF), bladder detrusor (VAChT, Rho kinase), bladder urothelium (CGRP, ATP, CRF, OCT-3, TRPV1), and hippocampus (TNF-α, IL-1β and Il-6, CRF, IL-10, BDNF, NGF). In conclusion, ACEA was proven to reverse CORT-induced changes in both cystometric and biochemical parameters that are determinants of OAB/depression, which represents an example of an existing link between OAB and depression via cannabinoid receptors.

The regulatory effect of sex steroids on the RhoA/ROCK pathway in the rat distal vagina

BACKGROUND

Sex steroids have been demonstrated as important modulators of vaginal function. The RhoA/ROCK calcium-sensitizing pathway plays a role in genital smooth muscle contractile mechanism, but its regulation has never been elucidated.

AIM

This study investigated the sex steroid regulation of the vaginal smooth muscle RhoA/ROCK pathway using a validated animal model.

METHODS

Ovariectomized (OVX) Sprague-Dawley rats were treated with 17β-estradiol (E2), testosterone (T), and T with letrozole (T + L) and compared with intact animals. Contractility studies were performed to test the effect of the ROCK inhibitor Y-27632 and the nitric oxide (NO) synthase inhibitor L-NAME. In vaginal tissues, ROCK1 immunolocalization was investigated; mRNA expression was analyzed by semiquantitative reverse transcriptase-polymerase chain reaction; and RhoA membrane translocation was evaluated by Western blot. Finally, rat vaginal smooth muscle cells (rvSMCs) were isolated from the distal vagina of intact and OVX animals, and quantification of the RhoA inhibitory protein RhoGDI was performed after stimulation with NO donor sodium nitroprusside, with or without administration of the soluble guanylate cyclase inhibitor ODQ or PRKG1 inhibitor KT5823.

OUTCOMES

Androgens are critical in inhibiting the RhoA/ROCK pathway of the smooth muscle compartment in the distal vagina.

RESULTS

ROCK1 was immunolocalized in the smooth muscle bundles and blood vessel wall of the vagina, with weak positivity detected in the epithelium. Y-27632 induced a dose-dependent relaxation of noradrenaline precontracted vaginal strips, decreased by OVX and restored by E2, while T and T + L decreased it below the OVX level. In Western blot analysis, when compared with control, OVX significantly induced RhoA activation, as revealed by its membrane translocation, with T reverting it at a level significantly lower than in controls. This effect was not exerted by E2. Abolishing NO formation via L-NAME increased Y-27632 responsiveness in the OVX + T group; L-NAME had partial effects in controls while not modulating Y-27632 responsiveness in the OVX and OVX + E2 groups. Finally, stimulation of rvSMCs from control animals with sodium nitroprusside significantly increased RhoGDI protein expression, counteracted by ODQ and partially by KT5823 incubation; no effect was observed in rvSMCs from OVX rats.

CLINICAL IMPLICATIONS

Androgens, by inhibiting the RhoA/ROCK pathway, could positively contribute to vaginal smooth muscle relaxation, favoring sexual intercourse.

STRENGTHS AND LIMITATIONS

This study describes the role of androgens in maintaining vaginal well-being. The absence of a sham-operated animal group and the use of the only intact animal as control represented a limitation to the study.

Tissue Kallikrein Protects Rat Prostate against the Inflammatory Damage in a Chronic Autoimmune Prostatitis Model via Restoring Endothelial Function in a Bradykinin Receptor B2-Dependent Way

Objective

The aim of this study was to investigate whether tissue kallikrein (KLK1) can protect the prostate from inflammatory damage and the mechanism involved in it.

Methods

A total of 50 male Wistar rats were used in this study. Initially, 20 rats were sacrificed to obtain the prostate antigen to induce experimental autoimmune prostatitis (EAP), and the remaining 30 rats were randomly divided into 5 experimental groups (normal control group (NC group), NC+KLK1 group (NCK group), EAP group, EAP+KLK1 group (EAPK group), and EAP+KLK1+HOE140 group (EAPKH group); n = 6). It should be explained that KLK1 mainly exerts its biological effects through bradykinin, and HOE140 is a potent and selective bradykinin receptor B2 (BDKRB2) antagonist. EAP was induced by intradermal injection of 15 mg/ml prostate antigen and complete Freund's adjuvant on days 0, 14, and 28. KLK1 was injected via tail vein at a dose of 1.5 × 10⁻³ PAN U/kg once a day, and HOE140 was administered by intraperitoneal injection at 20 μg/kg once every two days. Rats were sacrificed on day 42. The RNA and protein of the rat prostate were extracted to analyze the expression differences of KLK1, as well as the inflammation-, fibrosis-, and oxidative stress-related genes. The inflammatory cell infiltration and microvessel density of the prostate were also analyzed by pathological examination. In addition, pathological analysis was performed on prostate samples from patients undergoing benign prostate hyperplasia (BPH) surgery.

Results

The expression of KLK1 in the prostate decreased in the EAP group as well as BPH patients with obvious inflammation. KLK1 administration significantly inhibited inflammatory cell infiltration and reduced the production of inflammatory cytokines in the EAPK group. Prostate samples from the EAP group showed increased infiltration of T cells and macrophages, as well as gland atrophy, hypoxia, fibrosis, and angiogenesis. KLK1 administration upregulated endothelial nitric oxide synthase (eNOS) expression and suppressed oxidative stress, as well as transforming growth factor β1 (TGF-β) signaling pathways and the proangiogenic vascular endothelial growth factor (VEGF) in the EAPK group. However, in the EAPKH group in which HOE140 blocked BDKRB2, the beneficial effects of KLK1 were all cancelled. In addition, KLK1 intervention in normal rats had no obvious side effects.

Conclusion

The KLK1 expression is inhibited in the inflamed prostates of humans and rats. Exogenous KLK1 restored endothelial function via a BDKRB2-dependent way and then played a role in improving microcirculation and exerted anti-inflammatory, antifibrotic, and antioxidative stress effects in the rat chronic-inflamed prostate.

Efficacy and Safety of 12-week Monotherapy With Once Daily 5 mg Tadalafil for Lower Urinary Tract Symptoms of Benign Prostatic Hyperplasia: Evidence-based Analysis

Background: Tadalafil has been approved for the treatment of benign prostatic hyperplasia (BPH) for nearly 10 years. However, there are insufficient evidence-based studies of the efficacy and safety of tadalafil in treating lower urinary tract symptoms of BPH (LUTS/BPH). Objective: To evaluate the therapeutic effect and clinical safety of tadalafil monotherapy (5 mg once daily for 12 weeks) for LUTS/BPH. Methods: A total of 13 studies (15 randomized clinical trials [RCTs]) were extracted from the following databases: PubMed, Cochrane Central Register of Controlled Trials, Embase, and Web of Science for the period up to July 2021. The quality of the included RCTs was evaluated independently by two authors, who, respectively, extracted data according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses principles. Conflicts were settled by a discussion with two-third of senior authors. All data analyses were conducted by the Review Manager, version 5.4. Results: Regarding efficacy, 12-week trials indicated that 5 mg once daily tadalafil showed a significantly lower and, consequently, better total International Prostate Symptom Score (IPSS) than the placebo did (mean difference [MD]: -1.97, 95% CI: -2.24 to -1.70; P < 0.00001). In addition, significant differences were found between the tadalafil regimen and the placebo in the IPSS voiding subscore (MD: -1.30, 95% CI: -1.48 to -1.11; P < 0.00001), the IPSS storage subscore (MD: -0.70, 95% CI: -0.82 to -0.58; P < 0.00001), the IPSS quality of life (MD: -0.29, 95% CI: -0.35 to -0.22; P < 0.00001), and BPH impact index (MD: -0.58, 95% CI: -0.76 to -0.40; P < 0.00001). The safety analysis did not show a significant difference in serious adverse events between the two groups (risk ratio: 1.27, 95% CI: 0.80-2.01; P = 0.31), although the adverse events occurred at a higher incidence in the tadalafil group than in the placebo. Conclusions: This study demonstrates that once daily 5 mg tadalafil is a potentially effective and safe treatment choice with excellent tolerability for patients with LUTS/BPH. Systematic Review Registration: Identifier (CRD42021228840).

Review - Nutraceuticals Can Target Asthmatic Bronchoconstriction: NADPH Oxidase-Dependent Oxidative Stress, RhoA and Calcium Dynamics

Activation of various isoforms of NADPH oxidase contributes to the pathogenesis of asthma at multiple levels: promoting hypercontractility, hypertrophy, and proliferation of airway smooth muscle; enabling lung influx of eosinophils via VCAM-1; and mediating allergen-induced mast cell activation. Free bilirubin, which functions physiologically within cells as a feedback inhibitor of NADPH oxidase complexes, has been shown to have a favorable impact on each of these phases of asthma pathogenesis. The spirulina chromophore phycocyanobilin (PhyCB), a homolog of bilirubin’s precursor biliverdin, can mimic the inhibitory impact of biliverdin/bilirubin on NADPH oxidase activity, and spirulina’s versatile and profound anti-inflammatory activity in rodent studies suggests that PhyCB may have potential as a clinical inhibitor of NADPH oxidase. Hence, spirulina or PhyCB-enriched spirulina extracts merit clinical evaluation in asthma. Promoting biosynthesis of glutathione and increasing the expression and activity of various antioxidant enzymes – as by supplementing with N-acetylcysteine, Phase 2 inducers (eg, lipoic acid), selenium, and zinc – may also blunt the contribution of oxidative stress to asthma pathogenesis. Nitric oxide (NO) and hydrogen sulfide (H₂S) work in various ways to oppose pathogenic mechanisms in asthma; supplemental citrulline and high-dose folate may aid NO synthesis, high-dose biotin may mimic and possibly potentiate NO’s activating impact on soluble guanylate cyclase, and NAC and taurine may boost H₂S synthesis. The amino acid glycine has a hyperpolarizing effect on airway smooth muscle that is bronchodilatory. Insuring optimal intracellular levels of magnesium may modestly blunt the stimulatory impact of intracellular free calcium on bronchoconstriction. Nutraceutical regimens or functional foods incorporating at least several of these agents may have utility as nutraceutical adjuvants to standard clinical management of asthma.

H2S protects hippocampal neurons against hypoxia-reoxygenation injury by promoting RhoA phosphorylation at Ser188

Inhibition of RhoA-ROCK pathway is involved in the H₂S-induced cerebral vasodilatation and H₂S-mediated protection on endothelial cells against oxygen-glucose deprivation/reoxygenation injury. However, the inhibitory mechanism of H₂S on RhoA-ROCK pathway is still unclear. The aim of this study was to investigate the target and mechanism of H₂S in inhibition of RhoA/ROCK. GST-RhoA^wild and GST-RhoA^S188A proteins were constructed and expressed, and were used for phosphorylation assay in vitro. Recombinant RhoA^wild-pEGFP-N1 and RhoA^S188A-pEGFP-N1 plasmids were constructed and transfected into primary hippocampal nerve cells (HNCs) to evaluate the neuroprotective mechanism of endothelial H₂S by using transwell co-culture system with endothelial cells from cystathionine-γ-lyase knockout (CSE^-/-) mice and 3-mercaptopyruvate sulfurtransferase knockout (3-MST^-/-) rats, respectively. We found that NaHS, exogenous H₂S donor, promoted RhoA phosphorylation at Ser188 in the presence of cGMP-dependent protein kinase 1 (PKG1) in vitro. Besides, both exogenous and endothelial H₂S facilitated the RhoA phosphorylation at Ser188 in HNCs, which induced the reduction of RhoA activity and membrane transposition, as well as ROCK₂ activity and expression. To further investigate the role of endothelial H₂S on RhoA phosphorylation, we detected H₂S release from ECs of CSE^+/+ and CSE^-/- mice, and 3-MST^+/+ and 3-MST^-/- rats, respectively, and found that H₂S produced by ECs in the culture medium is mainly catalyzed by CSE synthase. Moreover, we revealed that both endothelial H₂S, mainly catalyzed by CSE, and exogenous H₂S protected the HNCs against hypoxia-reoxygenation injury via phosphorylating RhoA at Ser188.

Age-related differences in responses to hydrogen sulfide in the bladder of spontaneously hypertensive rats

OBJECTIVES

To investigate whether a response to hydrogen sulfide donors (GYY4137 and sodium hydrosulfide) and the endogenous hydrogen sulfide system (hydrogen sulfide level and expression of cysteine aminotransferase, cystathionine β-synthase, cystathionine γ-lyase, and 3-mercaptopyruvate sulfurtransferase) in the spontaneously hypertensive rat bladder differ with age, we compared the responses of hydrogen sulfide donors to micturition and bladder relaxation, and the endogenous hydrogen sulfide system in the bladder of 18-week versus 12-week-old spontaneously hypertensive rats.

METHODS

GYY4137 was intravesically administered and cystometry was performed in anesthetized rats. The responses of sodium hydrosulfide were evaluated in carbachol-mediated precontracted bladder strips. Bladder hydrogen sulfide levels and expression levels of each enzyme were investigated using the methylene blue method and Western blotting, respectively.

RESULTS

GYY4137 treatment significantly prolonged intercontraction intervals only in 12-week-old rats. Sodium hydrosulfide-induced bladder relaxation was significantly attenuated in the strips of 18-week-old rats compared with that in 12-week-old rats. In the bladder dome, significant increases in hydrogen sulfide levels and in the expression of cystathionine β-synthase, 3-mercaptopyruvate sulfurtransferase, and cysteine aminotransferase were observed in 18-week-old rats compared with 12-week-old rats. However, cystathionine γ-lyase bands were not detected in bladder tissues of either group.

CONCLUSIONS

Bladder relaxation induced by hydrogen sulfide may be attenuated in spontaneously hypertensive rats in an age-dependent manner.

Tadalafil Alone or in Combination with Tamsulosin for the Management for LUTS/BPH and ED

Purpose of Review

Aim of our systematic review is to evaluate and summarize the efficacy and safety of tadalafil alone or in combination with tamsulosin for the management of lower urinary tract symptoms (LUTS)/benign prostatic hyperplasia (BPH) and erectile dysfunction (ED).

Recent Findings

Daily tadalafil, in particular 5 mg, according to retrieved studies, appears to be both safe and effective in treating LUTS/BPH and ED, compared with placebo or tamsulosin. The combination of daily tadalafil 5 mg and tamsulosin 0.4 mg allows a better improvement of LUTS compared with both the monotherapies, even if with an increased, but acceptable and tolerated, adverse events rate. After discontinuation of tamsulosin or tadalafil in patients previously treated with their combination, the improvement of LUTS retains significance compared with baseline.

Summary

Tadalafil 5 mg should be considered a primary treatment option for patients with LUTS/BPH and ED. Evidence highlight an excellent tolerability, safety, and effectiveness profile, both alone or in combination with tamsulosin 0.4 mg. A better efficacy on LUTS relief has been observed for combination therapy, preserving also sexual function. The further switch to monotherapy allows to preserve LUTS relief, but tadalafil only is able to retain ED improvement. Our results support the evidence for a more and more tailored and modular LUTS treatment.

Persistence Rate with Tadalafil for Treatment of Male Lower Urinary Tract Symptoms

OBJECTIVES

We examined the persistence rate with tadalafil for treatment of male lower urinary tract symptoms (LUTS) and explored the factors relevant to withdrawal.

PATIENTS AND METHODS

We retrospectively collected the data of male patients who received tadalafil treatment for LUTS. The persistence rate and the reason for withdrawal were investigated.

RESULTS

A total of 155 patients were examined. Mean age and mean observation period were 71.9 (48-93) years and 15.1 (1-52) months, respectively. During the observation period, 74 patients (48%) withdrew tadalafil. The Kaplan-Meier curve indicated a 58% persistence rate at 1 year. The reasons for withdrawal included insufficient efficacy (31 patients, 42%), adverse events (21 patients, 28%), or symptom improvement (8 patients, 11%). Patients who continued tadalafil were significantly younger than those who withdrew it due to insufficient efficiency (71.4 ± 9.6 vs. 74.9 ± 9.1 years).

CONCLUSIONS

Most patients withdrew tadalafil due to insufficient efficacy. Older patients are likely to withdraw the treatment because of insufficient efficacy, thus, tadalafil for male LUTS could be more effective for younger patients.

Stimulation of atypical cannabinoid receptor GPR55 abolishes the symptoms of detrusor overactivity in spontaneously hypertensive rats

Overactive bladder is a troublesome disease that affects 15% of the population in developed countries. Since pharmacotherapy of this condition is frequently associated with side effects, the better tolerated drugs are being searched for. The main objective of our study was to check whether activation of the atypical cannabinoid receptor GPR55 would normalize the changes in cystometric, cardiovascular and biochemical parameters in the hypertensive female Wistar-Kyoto rats presenting the symptoms of overactive bladder accompanied by inflammation and oxidative damage in the urinary tracts. A 14-day intra-arterial administration of O-1602 (0.25 mg/kg/day), a potent agonist of GRP55 receptors, was able to abolish the signs of detrusor overactivity, inflammation and oxidative damage in the urinary bladder of the spontaneously hypertensive animals. Moreover, it increased their heart rate, reduced the mean blood pressure, and normalized the levels of several proteins that play a significant role in the proper functioning of the urinary bladder (i.e., calcitonin gene related peptide, organic cation transporter 3, extracellular signal-regulated kinase 1/2, vesicular acetylcholine transporter, RhoA). Based on the outcomes of our experiments, the atypical cannabinoid receptor GPR55 has emerged as a potential drug target for the treatment of overactive bladder in female subjects. It could be particularly attractive in the cases in which this condition is accompanied with elevated blood pressure, though further studies on this subject are needed.

Trend analysis of the role of circular RNA in goat skeletal muscle development

Background

Circular RNA (circRNA) is produced during the splicing of mRNA (in addition to linear splicing) and is part of the gene regulatory network. The temporal expression patterns the different developmental stages were inseparable from these molecules’ function.

Results

Skeletal muscles of Anhui white goat (AWG) across seven fetal to postnatal development stages were sequenced and 21 RNA sequencing libraries were constructed. We thereby identified 9090 circRNAs and analyzed their molecular properties, temporal expression patterns, and potential functions at the different stages. CircRNAs showed complexities and diversity of formation as the same host gene produces multiple isoforms of these nucleic acids with different expression profiles. The differential expression of 2881 circRNAs (DECs, P < 0.05) was identified and four were randomly selected and validated by qPCR. Moreover, 1118 DECs under strict selected (SDECs, |log2^FC| > 2 and P-adj value < 0.01) showed 4 expression trends (Clusters 0, 19, 16 and 18). Cluster 0 molecules had increasing expression at all stages with effects on muscle through metabolism, regulation of enzyme activity, and biosynthesis. Cluster 16 circRNAs had high expression in the early and late stages and are involved in “Wnt signaling pathway”, “AMPK signaling pathway” and others. Cluster 18 molecules were mainly expressed at F120 and participate in “cytoskeletal protein binding”, “Notch signaling pathway” and so on. Cluster 19 circRNAs were down-regulated at all stages and related to muscle structure and development. Lastly, the SDECs divided the period of skeletal muscle development into three transitional stages: stage 1 (F45 to F90), which related to muscle satellite cell proliferation and muscle fiber structure; stage 2 (F90 to B1), in which the attachment of the cytoplasmic surface to the actin cytoskeleton initiates; and stage 3, which involved the “cGMP-PKG signaling pathway”. Moreover, the paraffin sections messages also validated that there are three transitional stages of skeletal muscle development.

Conclusion

Our current study provides a catalog of goat muscle-related circRNAs that can stratify skeletal muscle development fetus 45 days to newborn 90 days into three developmental stages. These findings better our understanding of functional transitions during mammalian muscle development.

Inhibition of Multidrug Resistance Proteins by MK 571 Enhances Bladder, Prostate, and Urethra Relaxation through cAMP or cGMP Accumulation

The biologic effect of cAMP and cGMP is terminated by phosphodiesterases and multidrug resistance proteins MRP4 and MRP5, which pump cyclic nucleotides out of the cell. Therefore, this study aimed to characterize the role of MRP inhibitor, MK 571 (3-[[[3-[(1E)-2-(7-chloro-2-quinolinyl)ethenyl]phenyl][[3-(dimethylamino)-3-oxopropyl]thio]methyl]thio]propanoic acid), in the bladder, prostate, and urethra of male mice by means of functional assays, protein expression, and cyclic nucleotide quantification. The cumulative addition of MK 571 (1-30 µM) produced only small relaxation responses (approximately 25%) in all studied tissues. In the bladder, isoprenaline/fenoterol and forskolin concentration-dependently relaxed and MK 571 (20 µM) increased the maximal response values by 37% and 24%, respectively. When MK 571 was coincubated with fenoterol or forskolin, intracellular levels of cAMP and protein expression of phospho-vasodilator-stimulated phosphoprotein (p-VASP) Ser157 were significantly greater compared with bladders stimulated with fenoterol or forskolin alone. In the prostate and urethra, sodium nitroprusside concentration-dependently relaxed and MK 571 (20 µM) significantly increased relaxation responses by 70% and 56%, respectively, accompanied by greater intracellular levels of cGMP and protein expression of p-VASP Ser239 in the prostate. Tadalafil and BAY 41-2272 (5-cyclopropyl-2-[1-[(2-fluorophenyl)methyl]-1H-pyrazolo[3,4-b]pyridin-3-yl]-4-pyrimidinamine) also relaxed the prostate and urethra, respectively, and MK 571 markedly enhanced this response. The stable analog of cGMP (8-Br-cGMP) induced concentration-dependent relaxation responses in the prostate and urethra, and MK 571 significantly increased the relaxation response. In conclusion, to our knowledge, this is the first study to show that efflux transporters are physiologically active in the bladder, prostate, and urethra to control intracellular levels of cAMP or cGMP.

The use of antimuscarinics, phosphodiesterase type V inhibitors and phytotherapy for lower urinary tract symptoms in men

Besides the mainstay of α-blockers and 5α-reductase inhibitors, other forms of medical therapy complete the armamentarium in the treatment of lower urinary tract symptoms (LUTS) in men. These treatments can target specific symptoms as well as associated symptoms that would affect the quality of life of the patients. Many patients are bothered by storage symptoms, more so than the voiding symptoms. Antimuscarinics are efficacious and safe, provided the patients do not have high post void residual urine. Many patients with LUTS also have erectile dysfunction, and phosphodiesterase type V inhibitors are effective in relieving both LUTS as well as erectile dysfunction for such patients. Phytotherapy provides a popular and safe treatment for LUTS, however, the efficacy of the treatment has not been proven in well conducted prospective randomized controlled studies.

Lower urinary tract symptoms/benign prostatic hypertrophy and vascular function: Role of the nitric oxide-phosphodiesterase type 5-cyclic guanosine 3',5'-monophosphate pathway

It is well known that there is an association of lower urinary tract symptoms/benign prostatic hypertrophy with cardiovascular disease, suggesting that lower urinary tract symptoms/benign prostatic hypertrophy is a risk factor for cardiovascular events. Vascular function, including endothelial function and vascular smooth muscle function, is involved in the pathogenesis, maintenance and development of atherosclerosis, leading to cardiovascular events. Vascular dysfunction per se should also contribute to lower urinary tract symptoms/benign prostatic hypertrophy. Both lower urinary tract symptoms/benign prostatic hypertrophy and vascular dysfunction have cardiovascular risk factors, such as hypertension, dyslipidemia, diabetes mellitus, aging, obesity and smoking. Inactivation of the phosphodiesterase type 5-cyclic guanosine 3',5'-monophosphate-nitric oxide pathway causes lower urinary tract symptoms/benign prostatic hypertrophy through an enhancement of sympathetic nervous activity, endothelial dysfunction, increase in Rho-associated kinase activity and vasoconstriction, and decrease in blood flow of pelvic viscera. Both endogenous nitric oxide and exogenous nitric oxide act as vasodilators on vascular smooth muscle cells through an increase in the content of cyclic guanosine 3',5'-monophosphate, which is inactivated by phosphodiesterase type 5. In a clinical setting, phosphodiesterase type 5 inhibitors are widely used in patients with lower urinary tract symptoms/benign prostatic hypertrophy. Phosphodiesterase type 5 inhibitors might have beneficial effects on vascular function through not only inhibition of cyclic guanosine 3',5'-monophosphate degradation, but also increases in testosterone levels and nitric oxide bioavailability, increase in the number and improvement of the function of endothelial progenitor cells, and decrease in insulin resistance. In the present review, the relationships between lower urinary tract symptoms/benign prostatic hypertrophy, the phosphodiesterase type 5-nitric oxide-cyclic guanosine 3',5'-monophosphate pathway, vascular function and cardiovascular outcomes are examined.

Sildenafil citrate in combination with tamsulosin versus tamsulosin monotherapy for management of male lower urinary tract symptoms due to benign prostatic hyperplasia: A randomised, double-blind, placebo-controlled trial

Objective

To assess the additive effect of sildenafil citrate to tamsulosin in the treatment of lower urinary tract symptoms due to benign prostatic hyperplasia (LUTS/BPH) in men with or without erectile dysfunction (ED).

Patients and methods

In all, 150 men with untreated LUTS/BPH with or without ED were randomised to receive sildenafil 25 mg once daily (OD) or placebo OD (night time) combined with tamsulosin 0.4 mg OD (day time) for 6 months. Changes from pre-treatment scores in International Prostate Symptom Score (IPSS), IPSS-quality of life (QoL) score, maximum urinary flow rate (Q_max), and the five-item version of the International Index of Erectile Function questionnaire (IIEF-5) were assessed at 3 and 6 months. Safety profiles were assessed by physical examination and monitoring clinical adverse events.

Results

Group A comprised of men who received tamsulosin and sildenafil (75 men), whilst those in Group B received tamsulosin and placebo (75). The IPSS was significantly improved in Group A compared to Group B, at −29.3% vs −13.7% (P = 0.039) at 3 months and −37% vs −19.6% (P = 0.043) at 6 months after treatment. Q_max significantly improved in both groups compared with before treatment (P < 0.001). The IIEF-5 scores improved more in Group A than in Group B, at 58.7% vs 11.7% at 3 months and 62.4% vs 12.4% at 6 months after treatment (both P < 0.001).

Conclusion

Sildenafil citrate combined with tamsulosin improved LUTS, erectile function, and patient QoL more than tamsulosin monotherapy with the merit of a comparable safety profile in patients with LUTS/BPH.

Latest Evidence on the Use of Phosphodiesterase Type 5 Inhibitors for the Treatment of Lower Urinary Tract Symptoms Secondary to Benign Prostatic Hyperplasia

CONTEXT

Several preclinical reports, randomized controlled trials, systematic reviews, and posthoc analyses corroborate the role of phosphodiesterase type 5 inhibitors (PDE5-Is) in the treatment of men with lower urinary tract symptoms (LUTS) associated with benign prostatic enlargement (BPE).

OBJECTIVE

Update of the latest evidence on the mechanisms of action, evaluate the current meta-analyses, and emphasize the results of pooled data analyses of PDE5-Is in LUTS/BPE.

EVIDENCE ACQUISITION

Literature analysis of basic researches on PDE5-Is, systematic literature search in PubMed and Scopus until May 2015 on reviews of trials on PDE5-Is, and collection of pooled data available on tadalafil 5mg.

EVIDENCE SYNTHESIS

Latest evidences on the pathophysiology of LUTS/BPE has provided the rationale for use of PDE5-Is: (1) improvement of LUT oxygenation, (2) smooth muscle relaxation, (3) negative regulation of proliferation and transdifferentiation of LUT stroma, (4) reduction of bladder afferent nerve activity, and (5) down-regulation of prostate inflammation are the proven mechanisms of action of PDE5-Is. Data from eight systematic reviews demonstrated that PDE5-Is allow to improve LUTS (International Prostate Symptom Score mean difference vs placebo: 2.35-4.21) and erectile function (International Index of Erectile Function mean difference vs placebo: 2.25-5.66), with negligible change in flow rate (Qmax mean difference vs placebo: 0.01-1.43). Pooled data analyses revealed that tadalafil 5mg once daily allows the clinically-meaningful improvement of LUTS and nocturnal voiding frequency independent of both erectile dysfunction severity and improvement.

CONCLUSIONS

PDE5-Is are safe and effective in improving both LUTS and erectile function in appropriately selected men with LUTS/BPE. Data on the reduction of disease progression, long-term outcomes, and cost-effectiveness analyses are still lacking.

PATIENT SUMMARY

We reviewed recent literature on phosphodiesterase type 5 inhibitors in men with lower urinary tract symptoms associated with prostatic enlargement. We found evidence to confirm that phosphodiesterase type 5 inhibitors are a valid treatment option for men affected by bothersome urinary symptoms with or without erectile dysfunction.

Expression and Function of Phosphodiesterase Type 5 in Human Breast Cancer Cell Lines and Tissues: Implications for Targeted Therapy

PURPOSE

By catalyzing cGMP hydrolysis, phosphodiesterase (PDE) 5 is a critical regulator of its concentration and effects in different (patho)physiologic processes, including cancers. As PDE5 is a known druggable target, we investigated the clinical significance of its expression in breast cancer and the underlying mechanisms by which it may contribute to tumor progression.

EXPERIMENTAL DESIGN

PDE5 expression was evaluated in seven breast cancer cell lines by RT-PCR and immunoblotting. To examine the impact of PDE5 on cancer phenotype, MCF-7 cells expressing lower levels of the enzyme were engineered to stably overexpress PDE5. Proliferation was evaluated by MTT assays, motility and invasion by wound-healing/transmigration/invasion assays, transcriptome-profiling by RNA-sequencing, and Rho GTPase signaling activation by GST-pulldown assays and immunoblotting. Clinical relevance was investigated by IHC on tissues and retrospective studies from METABRIC cohort.

RESULTS

PDE5 is differentially expressed in each molecular subtype of both breast cancer cell lines and tissues, with higher levels representing a startling feature of HER2-positive and triple-negative breast cancers. A positive correlation was established between elevated PDE5 levels and cancers of high histologic grade. Higher PDE5 expression correlated with shorter patient survival in retrospective analyses. On molecular level, stable PDE5 overexpression in Luminal-A-like MCF-7 cells resulted in enhanced motility and invasion through Rho GTPase signaling activation. Treatment of PDE5-stable clones with selective ROCK or PDE5 inhibitors completely restored the less motile and weak invasive behavior of control vector cells.

CONCLUSIONS

PDE5 expression enhances breast cancer cell invasive potential, highlighting this enzyme as a novel prognostic candidate and an attractive target for future therapy in breast cancers. Clin Cancer Res; 22(9); 2271-82. ©2015 AACR.

The role of phosphodiesterase-5 inhibitors in prostatic inflammation: a review

Clinical and basic experimental evidence indicates that chronic inflammation is the greatest factor in benign prostatic hyperplasia (BPH) progression, which is the most common cause of Lower Urinary Tract Symptoms (LUTS). The use of anti-inflammatory agents such as steroids, cyclooxygenase-2 (COX-2) and phytotherapics have been investigated as forms of treatment for various prostate diseases. Recent evidence has demonstrated that PDE5 inhibitors (PDE5Is) improve symptoms of BPH/LUTS, possibly as a result of the relaxing of the smooth muscle fibers of the bladder and prostate by NO/cGMPc signaling, or by improving RhoA/Rho-kinase (ROCK), and reduction of the hyperactivity of the autonomic nervous system. However, some results have suggested that besides vasodilatation and their anti-proliferative effect, PDE5Is exert a direct anti-inflammatory effect, by raising cGMP. Given that inflammation is major factor in benign prostatic hyperplasia (BPH) progression, PDE5Is could act also restore prostatic function as they act as potent anti-inflammatory drugs. This review aims to provide a comprehensive summary of the use of phosphodiesterase-5 inhibitors to treat prostatic inflammation.

Are phosphodiesterase type 5 inhibitors effective for the management of lower urinary symptoms suggestive of benign prostatic hyperplasia?

AIM: To review the efficacy of phosphodiesterase type 5 inhibitors (PDE5-Is) in lower urinary tract symptoms (LUTS) suggestive of benign prostate hyperplasia (LUTS/BPH).

METHODS: A comprehensive research was conducted to identify all publications relating to benign prostate hyperplasia and treatment with sildenafil, vardenafil and tadalafil. To assess the efficacy, the changes in total international prostate symptom score (IPSS), IPSS subscore including voiding, storage and quality of life (QoL), Benign prostatic hyperplasia Impact Index (BII), maximum urinary flow rate (Qmax) and the International Index of Erectile Function (IIEF) were extracted. A meta-analytical technique was used for the analysis of integrated data from the included studies to evaluate the mean difference in the results.

RESULTS: Total IPSS score, IIEF and BII showed a significant improvement in trials in which LUTS/BPH with or without erectile dysfunction (ED) were compared with the placebo. For LUTS/BPH, the mean differences of total IPSS score, IIEF and BII are -2.17, 4.88 and -0.43, P < 0.00001, respectively. For LUTS/BPH with comorbid ED, the mean difference are -1.97, 4.54 and -0.52, P < 0.00001, respectively. PDE5-Is appear to improve IPSS storage, voiding and QoL subscore (mean difference = -0.71, -1.23 and -0.33, P < 0.00001, respectively). Although four doses of tadalafil (2.5, 5, 10 and 20 mg) failed to reach significance in Qmax (mean difference = 0.22, P = 0.10), the 5 mg dose of tadalafil significantly improved the Qmax (mean difference = 0.33, P = 0.03).

CONCLUSION: PED5-Is demonstrated efficacy for improving LUTS in BPH patients with or without ED and could be considered to be the first line treatment for LUTS/BPH.

Management of benign prostatic hyperplasia: role of phosphodiesterase-5 inhibitors

Several studies have highlighted a strong association between benign prostatic hyperplasia/lower urinary tract symptoms (BPH/LUTS) and erectile dysfunction (ED), particularly in elderly men. Many epidemiological trials, such as in vitro and in vivo studies, have reported the emerging role of metabolic syndrome, including abdominal obesity, impaired glucose metabolism, hypertriglyceridemia, low high-density lipoprotein cholesterol, and hypertension, in the development and progression of urinary and sexual symptoms. Moreover, many authors have focused their studies on the identification of all the shared pathogenetic mechanisms of LUTS/BPH and ED, including alteration of cyclic guanosine monophosphate and RhoA-ROCK pathways or vascular and neurogenic dysfunction. All these are potential targets for proposed phosphodiesterase type 5 inhibitors (PDE5-Is). Therefore, several trials have recently been designed to evaluate the role of PDE5-Is alone or in combination with conventional treatment for BPH, such as α-adrenergic blockers, in men affected by LUTS/BPH, with or without ED. Different PDE5-Is are in clinical use worldwide and currently six of them are licensed for the oral treatment of ED. All these compounds differ in pharmacokinetic factors, with influence on drug action, and subsequently in the overall safety and efficacy profile.

Effects of three-times-per-week versus on-demand tadalafil treatment on erectile function and continence recovery following bilateral nerve sparing radical prostatectomy: results of a prospective, randomized, and single-center study

Erectile dysfunction (ED) and urinary incontinence after bilateral nerve-sparing radical prostatectomy (BNSRP) still remain major causes of morbidity. Phosphodiesterase type 5 inhibitors (PDE5-Is) have a role in the treatment of ED after BNSRP. Several studies in patients with ED and lower urinary tract symptoms demonstrated that PDE5-Is could improve both erectile function and urinary symptoms. The aim of this study was to compare the efficacies of two dosing regimens of 20 mg tadalafil (on-demand and 3 times per week) and to assess the role of tadalafil in recovery of erectile function and continence after BNSRP. We conducted a single-center, prospective, randomized controlled trial of three times per week versus on-demand tadalafil 20 mg and a control group after BNSRP. A total of 129 preoperatively potent and continent patients were included in the study. The patients were evaluated at 6 weeks and 12 months postoperatively for erectile function and continence status. There was no significant difference between all three groups with respect to erectile function at 6 weeks after the surgery. Twelve months after the surgery, the International Index of Erectile Function score was significantly higher in the group using tadalafil 20 mg three times per week. However, there was no significant difference between the treated groups and the control group with respect to the continence status at 12 months after the surgery. There was no correlation between incontinence and ED after the surgery in all groups. Tadalafil 20 mg three times per week is an efficacious and well-tolerated treatment option for ED after BNSRP. Treatment with 20 mg tadalafil either three times per week or on demand cannot improve continence recovery after BNSRP compared with the control group.

Chronic Pelvic Ischemia: Contribution to the Pathogenesis of Lower Urinary Tract Symptoms (LUTS): A New Target for Pharmacological Treatment?

The incidence of lower urinary tract symptoms, including overactive bladder (OAB), is continuing to rise, and is associated with a negative impact on quality of life and a heavy economic burden. A major risk factor for OAB is advancing age. The etiology of OAB is multifactorial and appears to involve myogenic, neurogenic, and urotheliogenic factors. In this article, we review the strengthening preclinical evidence supporting the contribution of chronic pelvic ischemia to the pathogenesis of OAB. In animal models, chronic ischemia induced by arterial injury and a high-fat diet upregulates markers of oxidative stress and proinflammatory cytokines in the urothelium and lamina propria, and leads to increased expression of nerve growth factor. These processes result in increased afferent activity and an increased frequency of micturition, reflecting a state of bladder hyperactivity. In severe, prolonged cases, bladder overactivity may develop into underactivity. Antimuscarinic therapies are the mainstay of OAB treatment, but their usefulness is limited by modest efficacy and troublesome side-effects. Our increasing understanding of the contribution of chronic ischemia to OAB is leading toward novel therapeutic options targeting chronic pelvic ischemia and its morphological, functional, and oxidative consequences. Preclinical trials have demonstrated encouraging results with α1 -adrenoreceptor blockade, phosphodiesterase type 5 inhibition, β3 -adrenoreceptor agonism, free radical scavenging, and stem cell therapy, in preventing morphological, biochemical and functional changes induced by chronic bladder ischemia.

Changes in nerve-mediated contractility of the lower urinary tract in a mouse model of premature ageing

BACKGROUND AND PURPOSE

A high incidence of lower urinary tract disorders is associated with ageing. In the senescent-accelerated prone (SAMP8) mouse strain and the senescent-accelerated resistant (SAMR1) strain, we compared smooth muscle contractility in responses to intrinsic neurotransmitters, both in the bladder and urethra.

EXPERIMENTAL APPROACH

We analysed micturition frequency, the changes in muscle tension induced by electrical field stimulation or agonist administration, the density of nerves (adrenergic, cholinergic and nitrergic) and interstitial cells (ICs), as well as cGMP accumulation in bladder and urethral preparations.

KEY RESULTS

Senescent mice of the SAMP8 strain displayed increased micturition frequency and excitatory contractility of neurogenic origin in the bladder. While cholinergic nerve density remained unchanged, there was a mild sensitization to ACh in male mice. Potentiation in the detrusor may be also provoked by the stronger contribution of ATP, together with reduced adrenergic innervation in males and COX-derived prostanoid production in females. The greater excitatory contractility in the urethra was probably due to the sensitization to noradrenaline, in conjunction with attenuated nitrergic relaxation. There were also fewer neuronal NOS immunoreactive (ir) nerves and vimentin-positive ICs, although the sildenafil- and diethylamine-NONOate-induced relaxations and cGMP-ir remained unchanged.

CONCLUSIONS AND IMPLICATIONS

Premature senescent mice exhibit bladder and urethral hyperexcitability, coupled with reduced urethral relaxation of neurogenic origin, which could model the impaired urinary function in elderly humans. We propose that senescence-accelerated mice provide a useful tool to analyse the basic mechanisms of age-related changes in bladder and urethral function.

Rho-kinase as a therapeutic target in vascular diseases: striking nitric oxide signaling

Rho GTPases are a globular, monomeric group of small signaling G-protein molecules. Rho-associated protein kinase/Rho-kinase (ROCK) is a downstream effector protein of the Rho GTPase. Rho-kinases are the potential therapeutic targets in the treatment of cardiovascular diseases. Here, we have primarily discussed the intriguing roles of ROCK in cardiovascular health in relation to nitric oxide signaling. Further, we highlighted the biphasic effects of Y-27632, a ROCK inhibitor under shear stress, which acts as an agonist of nitric oxide production in endothelial cells. The biphasic effects of this inhibitor raised the question of safety of the drug usage in treating cardiovascular diseases.

Metformin in vitro and in vivo increases adenosine signaling in rabbit corpora cavernosa

INTRODUCTION

In subjects with erectile dysfunction responding poorly to sildenafil, metformin was reported to improve erections.

AIMS

The aim of this study is to investigate metformin's mechanism of action on erectile function, particularly focusing on adenosine (ADO) and nitric oxide (NO) signaling in an animal model of high-fat diet (HFD)-induced metabolic syndrome.

METHODS

In vitro contractility studies of penile strips. Penile expression of genes related to ADO or NO signaling was also evaluated.

MAIN OUTCOME MEASURE

In vitro contractility studies were used to investigate the effect of in vivo and ex vivo metformin administration on ADO- or acetylcholine (Ach)-induced relaxation of penile strips from HFD as compared with animals fed a regular diet (RD).

RESULTS

Expression of ADO receptor type 3 (A3 R), ADO deaminase (ADA), AMP deaminase type 1 (AMPD1), and 2 (AMPD2) was decreased in HFD as compared with RD. Accordingly, in HFD the ADO relaxant effect was potentiated as compared with RD (P < 0.02). In vivo metformin treatment in both RD and HFD significantly increased the ADO relaxing effect (P < 0.0001 and P < 0.01, respectively, vs. relative untreated groups) although to a different extent. In fact, the half-maximal inhibitory concentration (IC50 )/IC50 ratio in RD increased fourfold vs. HFD (RD IC50 ratio = 13.75 ± 2.96; HFD IC50 ratio = 2.85 ± 0.52). In corpora cavernosa (CC) from HFD, in vivo metformin (i) normalized A3 R, ADA, and AMPD1; (ii) further decreased AMPD2; (iii) increased dimethylarginine dimethylamino-hydrolase; and (iv) partially restored impaired Ach-induced relaxation. Ex vivo metformin time and dose dependently increased the relaxant effect of ADO in RD. The potentiating effect of metformin on ADO-induced relaxation was significantly reduced by preincubation with NO synthase inhibitor N(ω) -Nitro-L-arginine methyl ester hydrochloride (L-NAME). Interestingly, in vivo testosterone supplementation in HFD rabbits (i) increased penile expression of endothelial NO synthase and AMPD2 and (ii) restored metformin's potentiating effect on ADO-induced relaxation up to RD level.

CONCLUSION

Metformin in vivo and ex vivo increases ADO signaling in CC, most probably interfering with NO formation and ADO breakdown.

Tadalafil effect on metabolic syndrome-associated bladder alterations: an experimental study in a rabbit model

INTRODUCTION

Metabolic syndrome (MetS) and lower urinary tract symptoms (LUTS) are often associated. Bladder detrusor hyper-contractility-a major LUTS determinant-is characterized by increased Ras homolog gene family, member A/Rho-associated protein kinase (RhoA/ROCK) signaling, which is often upregulated in MetS.

AIM

This study investigated the effects of tadalafil dosing on RhoA/ROCK signaling in bladder, in a rabbit model of high-fat diet (HFD)-induced MetS.

METHODS

Adult male rabbits feeding a HFD for 12 weeks. A subset of HFD animals was treated with tadalafil (2 mg/kg/day, 1 week: the last of the 12 weeks) and compared with HFD and control (feeding a regular diet) rabbits.

MAIN OUTCOME MEASURES

In vitro contractility studies to evaluate the relaxant effect of the selective ROCK inhibitor, Y-27632, in carbachol precontracted bladder strips. Evaluation of RhoA activation by its membrane translocation. Immunohistochemistry for ROCK expression has been performed to evaluate ROCK expression in bladder from the different experimental groups. mRNA expression of inflammation, pro-fibrotic markers by quantitative RT-PCR has been performed to evaluate the effect of tadalafil on MetS-induced inflammation and fibrosis within the bladder. The in vitro effect of tadalafil on RhoA/ROCK signaling in bladder smooth muscle cells was evaluated by using chemotaxis assay.

RESULTS

Bladder strips from HFD rabbits showed hyper-responsiveness to Y-27632, indicating RhoA/ROCK overactivity in HFD bladder compared with matched controls. Accordingly, the fraction of activated (translocated to the membrane) RhoA as well as ROCK expression are increased in HFD bladder. Tadalafil dosing normalized HFD-induced bladder hypersensitivity to Y-27632, by reducing RhoA membrane translocation and ROCK overexpression. Tadalafil dosing reduced mRNA expression of inflammatory, pro-fibrotic, and hypoxia markers. A direct inhibitory effect of tadalafil on RhoA/ROCK signaling in bladder smooth muscle cell was demonstrated by using chemotaxis assay. Pre-treatment with tadalafil inhibited both basal and PDGF-induced migration of bladder smooth muscle cells.

CONCLUSIONS

Tadalafil dosing reduced RhoA/ROCK signaling and smooth muscle overactivity in an animal model of MetS-associated bladder alterations. Our findings suggest a novel mechanism of action of tadalafil in alleviating LUTS in MetS patients.

Benign prostatic hyperplasia: a new metabolic disease of the aging male and its correlation with sexual dysfunctions

Metabolic syndrome (MetS) is a well-recognized cluster of cardiovascular (CV) risk factors including obesity, hypertension, dyslipidemia, and hyperglycaemia, closely associated with an increased risk of forthcoming cardiovascular disease and type 2 diabetes mellitus. Emerging evidence indicates that benign prostate hyperplasia (BPH) and its related lower urinary tract symptoms (LUTS) represent other clinical conditions frequently observed in subjects with MetS. Several modifiable factors involved in MetS determinism, such as inadequate diet, lack of physical exercise, and smoking and drinking behaviours are emerging as main contributors to the development of BPH. The pathogenetic mechanisms underlying the connection between MetS and BPH have not been completely clarified. MetS and its components, hypogonadism, and prostate inflammation probably play an important role in inducing BPH/LUTS. Although historically considered as a "normal" consequence of the aging process, BPH/LUTS should now be faced proactively, as a preventable disorder of the elderly. Type of diet and level of physical activity are now considered important factors affecting prostate health in the aging male. However, whether physical exercise, weight loss, and modifications of dietary habit can really alter the natural history of BPH/LUTS remains to be determined. Further research is advisable to better clarify these points.

Opposite effects of tamoxifen on metabolic syndrome-induced bladder and prostate alterations: a role for GPR30/GPER?

BACKGROUND

BPH and LUTS have been associated to obesity, hypogonadism, and metabolic syndrome (MetS). MetS-induced prostate and bladder alterations, including inflammation and tissue remodeling, have been related to a low-testosterone and high-estrogen milieu. In addition to ERs, GPR30/GPER is able to mediate several estrogenic non-genomic actions.

METHODS

Supplementing a subgroup of MetS rabbits with tamoxifen, we analyzed the in vivo effects on MetS-induced prostate and bladder alterations. The effects of selective ER/GPER ligands and GPER silencing on prostate inflammation were also studied in vitro using hBPH cells.

RESULTS

ERα, ERβ, and PR expression was upregulated in MetS bladder, where tamoxifen decreased ERα and PR expression, further stimulating ERβ. In addition, tamoxifen-dosing decreased MetS-induced overexpression of inflammatory and tissue remodeling genes. In prostate, sex steroid receptors, pro-inflammatory and pro-fibrotic genes were upregulated in MetS. However, tamoxifen did not affect them and even increased COX-2. In hBPH cells, 17β-estradiol increased IL-8 secretion, an effect blunted by co-treatment with GPER antagonist G15 but not by ER antagonist ICI 182,780, which further increased it. GPER agonist G1 dose-dependently (IC50  = 1.6 nM) induced IL-8 secretion. In vitro analysis demonstrated that GPER silencing reverted these stimulatory effects.

CONCLUSIONS

GPER can be considered the main mediator of estrogen action in prostate, whereas in bladder the mechanism appears to rely on ERα, as indicated by in vivo experiments with tamoxifen dosing. Limiting the effects of the MetS-induced estrogen action via GPER could offer new perspectives in the management of BPH/LUTS, whereas tamoxifen dosing showed potential benefits in bladder.

PDE5 inhibitors blunt inflammation in human BPH: a potential mechanism of action for PDE5 inhibitors in LUTS

BACKGROUND

Metabolic syndrome (MetS) and benign prostate hyperplasia (BPH)/low urinary tract symptoms (LUTS) are often comorbid. Chronic inflammation is one of the putative links between these diseases. Phosphodiesterase type 5 inhibitors (PDE5i) are recognized as an effective treatment of BPH-related LUTS. One proposed mechanism of action of PDE5 is the inhibition of intraprostatic inflammation. In this study we investigate whether PDE5i could blunt inflammation in the human prostate.

METHODS

Evaluation of the effect of tadalafil and vardenafil on secretion of interleukin 8 (IL-8, a surrogate marker of prostate inflammation) by human myofibroblast prostatic cells (hBPH) exposed to different inflammatory stimuli. We preliminary evaluate histological features of prostatic inflammatory infiltrates in BPH patients enrolled in a randomized, double bind, placebo controlled study aimed at investigating the efficacy of vardenafil (10 mg/day, for 12 weeks) on BPH/LUTS.

RESULTS

In vitro treatment with tadalafil or vardenafil on hBPH reduced IL-8 secretion induced by either TNFα or metabolic factors, including oxidized low-density lipoprotein, oxLDL, to the same extent as a PDE5-insensitive PKG agonist Sp-8-Br-PET-cGMP. These effects were reverted by the PKG inhibitor KT5823, suggesting a cGMP/PKG-dependency. Treatment with tadalafil or vardenafil significantly suppressed oxLDL receptor (LOX-1) expression. Histological evaluation of anti-CD45 staining (CD45 score) in prostatectomy specimens of BPH patients showed a positive association with MetS severity. Reduced HDL-cholesterol and elevated triglycerides were the only MetS factors significantly associated with CD45 score. In the MetS cohort there was a significant lower CD45 score in the vardenafil-arm versus the placebo-one.

Effects of Rho-kinase inhibition on myosin light chain phosphorylation and obstruction-induced detrusor overactivity

OBJECTIVES

To study the relationship between myosin light chain phosphorylation of the detrusor muscle and spontaneous smooth muscle contractions in a rabbit model of partial outlet obstruction.

METHODS

New Zealand white rabbit urinary bladders were partially obstructed for 2 weeks. Rabbits were euthanized, detrusor muscle strips were hung on a force transducer and spontaneous activity was measured at varying concentrations (0-0.03 μM/L) of the Rho-kinase inhibitors GSK 576371 or 0.01 μM/L Y27632. Basal myosin light chain phosphorylation was measured by 2-D gel electrophoresis in control and GSK 576371-treated strips.

RESULTS

Both drugs suppressed the force of spontaneous contractions, whereas GSK 576371 had a more profound effect on the frequency of the contractions. The IC₅₀ values for the inhibition of frequency and force of spontaneous contractions were 0.17 μM/L and 0.023 μM/L for GSK 576371, respectively. The compound significantly decreased the basal myosin light chain phosphorylation from 28.0 ± 3.9% to 13.5 ± 1.9% (P < 0.05). At 0.01 μM/L, GSK 576371 inhibited spontaneous bladder overactivity by 50%, but inhibited carbachol-elicited contractions force by just 25%.

CONCLUSIONS

These data suggest that Rho-kinase regulation of myosin light chain phosphorylation contributes to the spontaneous detrusor activity induced by obstruction. This finding could have therapeutic implications by providing another therapeutic option for myogenic, overactive bladder.

PDE5-Is for the Treatment of Concomitant ED and LUTS/BPH

Epidemiologic data in adult men exhibit a strong relationship between erectile dysfunction (ED) and lower urinary tract symptoms suggestive of benign prostatic hyperplasia (LUTS/BPH), indicating that men affected by ED should also be investigated for LUTS/BPH and those presenting with storage or voiding LUTS should be investigated for co-morbid ED. Common pathophysiolgical mechanisms underlying both LUTS/BPH and ED, including alteration of NO/cGMP or RhoA/Rho-kinase signaling and/or vascular or neurogenic dysfunction, are potential targets for proposed phosphodiesterase type 5 inhibitors (PDE5-Is). Several randomized controlled trials and only a few reviews including all commercially available PDE5-Is demonstrated the safety and efficacy of these drugs in the improvement of erectile function and urinary symptoms, in patients affected either by ED, LUTS, or both conditions.

The use of a single daily dose of tadalafil to treat signs and symptoms of benign prostatic hyperplasia and erectile dysfunction

A strong and independent association between lower urinary tract symptoms suggestive of benign prostatic hyperplasia (LUTS/BPH) and erectile dysfunction (ED) has been widely evidenced in several clinical epidemiologic studies. Preclinical animal models have provided a great deal of information on potential common pathogenic mechanisms underlying these two clinical identities. Although the efficacy of the most commonly used treatments for LUTS/BPH is well defined, the negative impact of these treatments on sexual function – in particular, on ED – has triggered the search for new treatment options. In this regard, a new role for phosphodiesterase type 5 inhibitors in the treatment of LUTS/BPH and ED has been claimed. Tadalafil is one of the most extensively investigated phosphodiesterase type 5 inhibitors for this new indication. All evidence reported to date suggests that tadalafil 5 mg once daily is a safe and effective treatment option for both LUTS/BPH and ED.

Mechanism of action of phosphodiesterase type 5 inhibition in metabolic syndrome-associated prostate alterations: an experimental study in the rabbit

BACKGROUND

Phosphodiesterase type 5 (PDE5) inhibitors improve benign prostatic hyperplasia (BPH)-related lower urinary tract symptoms (LUTS), often associated with metabolic syndrome (MetS). This study investigated the effects of PDE5 inhibition in the prostate of rabbits fed a high fat diet (HFD) for 12 weeks. HFD-rabbits develop the most important features of human MetS (glucose intolerance, dyslipidemia, increased abdominal adiposity, and hypertension), along with hypogonadism and LUT abnormalities (prostate and bladder inflammation/tissue remodeling).

METHODS

Gene expression was evaluated by quantitative RT-PCR. Prostate morphological changes and oxygenation were evaluated by immunohistochemistry.

RESULTS

HFD prostates showed increased PDE5 expression, suggesting a peculiar sensitivity of prostate to the action of PDE5 inhibitors during MetS. Accordingly, prostate PDE5 mRNA was negatively associated to plasma testosterone/estradiol ratio, whose reduction characterizes MetS, and positively with the expression in prostate of several genes exploring pathogenetic processes for BPH/LUTS, such as inflammation, leukocyte infiltration, and fibrosis/myofibroblast activation. Most of these genes was up-regulated by HFD, and significantly reduced by PDE5 inhibition, through either chronic (12 weeks) or, at a lower extent, acute (1-week) tadalafil dosing. Tadalafil was also able to reduce blood pressure and visceral fat in HFD rabbits, without changing any other MetS parameter. Interestingly, 1-week tadalafil administration to HFD rabbits, significantly blunted prostate inflammation (increased CD45 immunopositivity), fibrosis (reduced muscle/fiber ratio) and hypo-oxygenation, thus suggesting a potential curative effect of PDE5 inhibition on MetS-related prostate alterations.

CONCLUSIONS

Our data provide the experimental evidences to support the multiple potentiality of PDE5 inhibitors as a useful therapeutic tool in LUTS.

Phosphodiesterase type 5 inhibition reverts prostate fibroblast-to-myofibroblast trans-differentiation

Phosphodiesterase type 5 (PDE5) inhibitors have been demonstrated to improve lower urinary tract symptoms secondary to benign prostatic hyperplasia (BPH). Because BPH is primarily driven by fibroblast-to-myofibroblast trans-differentiation, this study aimed to evaluate the potential of the PDE5 inhibitor vardenafil to inhibit and reverse trans-differentiation of primary human prostatic stromal cells (PrSC). Vardenafil, sodium nitroprusside, lentiviral-delivered short hairpin RNA-mediated PDE5 knockdown, sodium orthovanadate, and inhibitors of MAPK kinase, protein kinase G, Ras homolog family member (Rho) A, RhoA/Rho kinase, phosphatidylinositol 3 kinase and protein kinase B (AKT) were applied to PrSC treated with basic fibroblast growth factor (fibroblasts) or TGFβ1 (myofibroblasts) in vitro, in chicken chorioallantoic membrane xenografts in vivo, and to prostatic organoids ex vivo. Fibroblast-to-myofibroblast trans-differentiation was monitored by smooth muscle cell actin and IGF binding protein 3 mRNA and protein levels. Vardenafil significantly attenuated TGFβ1-induced PrSC trans-differentiation in vitro and in chorioallantoic membrane xenografts. Enhancement of nitric oxide/cyclic guanosine monophosphate signaling by vardenafil, sodium nitroprusside, or PDE5 knockdown reduced smooth muscle cell actin and IGF binding protein 3 mRNA and protein levels and restored fibroblast-like morphology in trans-differentiated myofibroblast. This reversal of trans-differentiation was not affected by MAPK kinase, protein kinase G, RhoA, or RhoA/Rho kinase inhibition, but vardenafil attenuated phospho-AKT levels in myofibroblasts. Consistently, phosphatidylinositol 3 kinase or AKT inhibition induced reversal of trans-differentiation, whereas the tyrosine phosphatase inhibitor sodium orthovanadate abrogated the effect of vardenafil. Treatment of prostatic organoids with vardenafil ex vivo reduced expression of myofibroblast markers, indicating reverse remodeling of stroma towards a desired higher fibroblast/myofibroblast ratio. Thus, enhancement of the nitric oxide/cyclic guanosine monophosphate signaling pathway by vardenafil attenuates and reverts fibroblast-to-myofibroblast trans-differentiation, hypothesizing that BPH patients might benefit from long-term therapy with PDE5 inhibitors.

Postoperative phosphodiesterase type 5 inhibitor administration increases the rate of urinary continence recovery after bilateral nerve-sparing radical prostatectomy

OBJECTIVES

To investigate the effect of phosphodiesterase type 5 inhibitor on urinary continence recovery after bilateral nerve-sparing radical prostatectomy.

METHODS

We analyzed data of 393 open bilateral nerve-sparing radical prostatectomies carried out between 2005 and 2010. Patients who recovered urinary continence within the first month after catheter removal (n = 52) were excluded. This resulted in 341 evaluable patients. Urinary continence recovery was defined as being completely pad free over a period of 24 h. Patients were stratified according to postoperative daily (n = 58; 17%), on-demand (n = 112; 32.8%) and no (n = 171; 50.1%) phosphodiesterase type 5 inhibitor use. The effect of phosphodiesterase type 5 inhibitor use on urinary continence was assessed using the Kaplan-Meier method. Uni- and multivariable Cox regression analyses were used to test the association between phosphodiesterase type 5 inhibitor and urinary continence recovery after adjusting for cofounders.

RESULTS

At a mean follow up of 36.4 months after surgery (median: 33), 288 patients (84.5%) recovered urinary continence after bilateral nerve-sparing radical prostatectomy. Patients who did not use phosphodiesterase type 5 inhibitor after surgery had lower rates of urinary continence recovery at 1- and 2-year follow up as compared with patients taking phosphodiesterase type 5 inhibitor (67.1 vs 86.7% and 76 vs 94.4%, respectively; P < 0.001). After adjusting for all confounders, multivariable analysis showed that phosphodiesterase type 5 inhibitor use, either on demand or daily, had a positive impact on urinary continence recovery (P = 0.03).

CONCLUSIONS

Patients taking phosphodiesterase type 5 inhibitor have higher urinary continence recovery rates as compared with patients left untreated after bilateral nerve-sparing radical prostatectomy. An improvement in sphincteric and pelvic floor blood supply might be responsible for this beneficial effect associated with the use of phosphodiesterase type 5 inhibitor.

Les inhibiteurs de la phosphodiestérase de type 5 : une révolution dans le traitement des symptômes du bas appareil urinaire?

Contexte

L’incidence des symptômes du bas appareil urinaire (SBAU) liés à une hypertrophie bénigne de prostate (HBP) augmente avec l’âge puisqu’ils touchent 50 % des patients âgés de plus de 50 ans et 90 % de ceux âgés de plus de 80 ans. La prévalence et la sévérité de la dysfonction érectile (DE) augmentent également avec l’âge. Sa prévalence est évaluée à 31,6 % dans une population générale d’adultes âgés de plus de 40 ans. Les SBAU comme la DE altèrent de façon significative la qualité de vie (QdV) des patients et de leur partenaire. Plusieurs études ont montré que les SBAU constituent un facteur de risque de DE indépendant de l’âge et des autres comorbidités. La sévérité des SBAU est corrélée à celle de la DE. Les hypothèses physiopathologiques pour expliquer le lien entre SBAU et DE sont : une augmentation du tonus sympathique, une altération du système NO/cGMP, une altération du système rho-kinase et une athéromatose pelvienne.

Objectif

Évaluer les résultats et comprendre le mécanisme d’action de l’administration d’un inhibiteur de la phosphodiestérase de type 5 (IPDE 5) sur les SBAU liés à une HBP.

Matériels et méthodes

Une revue de la littérature a été réalisée à partir des articles originaux et des articles de synthèse déjà disponibles, sélectionnés par le moteur de recherche Pubmed de la National Library of Medecine. Les mots clés utilisés pour cette recherche ont été : benign prostatic hyperplasia; cyclic nucleotide phosphodiesterase type 5; LUTS; erectile dysfunction.

Résultats

Cette revue de la littérature montre que l’administration d’un inhibiteur de la phosphodiestérase de type 5 améliore les SBAU de manière significative dans 12 essais cliniques randomisés, avec un bénéfice également sur la DE et l’absence d’effets secondaires indésirables graves rapportés.

Conclusion

Le traitement des SBAU par les IPDEs 5 semble très prometteur, même s’il ne dispose pas d’une AMM dans cette indication en France. Récemment, le tadalafil à la posologie de 5 mg a été approuvé aux États-Unis par la FDA dans les troubles mictionnels liés à l’HBP, avec ou sans DE.

A randomized, placebo-controlled study to assess safety and efficacy of vardenafil 10 mg and tamsulosin 0.4 mg vs. tamsulosin 0.4 mg alone in the treatment of lower urinary tract symptoms secondary to benign prostatic hyperplasia

INTRODUCTION

Safety and efficacy of tamsulosin and vardenafil are well established: however, there is no report regarding combined therapy with these drugs for lower urinary tract symptoms (LUTSs) secondary to benign prostatic hyperplasia (BPH).

AIM

To compare the safety and efficacy of tamsulosin 0.4 mg/day vs. tamsulosin 0.4 mg/day plus vardenafil 10 mg/day in patients with LUTS/BPH in a randomized trial with 12-week follow-up.

METHODS

We conducted a randomized, double-blind, placebo-controlled study on 60 men with persistent storage LUTS after 2-week run-in with tamsulosin.

MAIN OUTCOME MEASURES

International Prostate Symptom Score (IPSS), IPSS-bother, International Index of Erectile Function, Version 5 (IIEF-5) and Over Active Bladder questionnaire (OAB-q) scores, uroflowmetry data (Qmax, Qave), and postvoiding residual urine were recorded after run-in (baseline), and 2 and 12 weeks after treatment. Differences between vardenafil and placebo at different times were calculated with unpaired samples t-test. Between-group differences in change from baseline to 2 and 12 weeks were evaluated with analysis of variance.

RESULTS

We found a between-group significant difference from baseline to 12 weeks in the following: (i) Qmax (placebo: +0.07, vardenafil: +2.56, P = 0.034); (ii) Qave (placebo: -0.15, vardenafil: +1.02, P = 0.031); (iii) irritative-IPSS subscores (placebo: -1.67, vardenafil: -3.11, P = 0.039); and (iv) IIEF (placebo: +0.06, vardenafil: +2.61, P = 0.030). No patient reported any serious (grade ≥ 2) adverse event (AE). There were no differences in the incidence of common, treatment-related AEs between men undergoing combined therapy or tamsulosin alone.

CONCLUSIONS

The combination of tamsulosin and vardenafil for 12 weeks was well tolerated and more effective to improve both LUTS and erectile function, as compared with tamsulosin alone. Further studies are needed to assess the role of combined therapy of phosphodiesterase type 5 inhibitors and alpha blockers in treating LUTS/BPH.