Reno-protective effects of Phosphodiesterase 5 inhibitors

Investigation of PDE5 effect on NOS in nasal polyp pathophysiology

PURPOSE

Nasal polyps are masses resulting from chronic mucosal inflammation. Nitric oxide (NO) has recently attracted attention in nasal polyps as it plays an important role in both acute and chronic inflammation. One of the important mechanisms controlling NO production is phosphodiesterase (PDE) enzymes. The enzyme phosphodiesterase type 5 (PDE5) is an important regulator of cyclic guanosine 3'-5'-monophosphate (cGMP) signalling. PDE5 inhibitors increase intracellular cGMP concentration by inhibiting cGMP degradation and prolong NO signalling. NO is thought to cause nasal congestion because it increases microvascular permeability and causes mucosal oedema. The aim of our study was to investigate the role of PDE5, inducible nitric oxide synthase (iNOS), and endothelial nitric oxide synthase (eNOS) in the pathophysiology of nasal polyps with mucosal oedema in histopathology.

METHODS

Nasal mucosal tissues were obtained from 25 patients with nasal polyps who underwent endoscopic sinus surgery as the study group and 25 patients who underwent rhinoplasty as the control group. eNOS, iNOS and PDE5 levels were measured in nasal mucosal tissues.

RESULTS

The mean age was 47.40 ± 16.33 years in the nasal polyp group and 35.44 ± 12.47 years in the normal group, and 64.0% (n = 16) of both groups were male. ELISA measurements showed that PDE5 levels were significantly decreased and iNOS and eNOS levels were significantly increased in the nasal polyp group compared with the control group. CONCLUSıON: This study suggest that iNOS, eNOS, and PDE5 may play important roles in the pathophysiology of nasal polyps.

Benefits of Tadalafil and Sildenafil on Mortality, Cardiovascular Disease, and Dementia

BACKGROUND

Erectile dysfunction and lower urinary tract symptoms, from benign prostatic hyperplasia and bladder neck obstructions, are prevalent in men and associated with an increased risk of cardiovascular diseases. Phosphodiesterase-5 (PDE-5) inhibitors, such as tadalafil and sildenafil, are used to treat erectile dysfunction and may also offer cardiovascular benefits due to their vasodilatory effects. This study evaluates the impact of these PDE-5 inhibitors on all-cause mortality, cardiovascular disease, and dementia in middle-aged men with erectile dysfunction and lower urinary tract symptoms over a 3 year follow-up period.

METHODS

This longitudinal study analyzed data from 50 million US men using the TriNetX database. Men at least 40 years of age prescribed tadalafil or sildenafil after an erectile dysfunction diagnosis, or tadalafil after lower urinary tract symptom diagnoses, from 2004 to 2021 were included. Three-year outcomes assessed included all-cause mortality, cardiovascular disease, and dementia, comparing men on PDE-5 inhibitors to those not on these medications. Propensity matching was performed for demographics and eight pre-existing conditions.

RESULTS

The final cohort included 509,788 men with erectile dysfunction and 1,075,908 with lower urinary tract symptoms. Tadalafil and sildenafil were associated with significantly reduced risks of all-cause mortality (RR 0.66/0.76), myocardial infarction (0.73/0.83), stroke (0.66/0.78), venous thromboembolism (0.79/0.80), and dementia (0.68/0.75) in erectile dysfunction patients, with tadalafil showing more significant benefits. In lower urinary tract symptom patients, tadalafil was similarly associated with reduced mortality, cardiovascular disease, and dementia.

CONCLUSIONS

In conclusion, tadalafil and sildenafil use in erectile dysfunction patients reduced mortality, cardiovascular disease, and dementia risks, with tadalafil providing more benefits. Tadalafil also conferred similar benefits to patients with lower urinary tract symptoms.

Phosphodiesterase Type 5 Inhibitors in Male Reproduction: Molecular Mechanisms and Clinical Implications for Fertility Management

Phosphodiesterases, particularly the type 5 isoform (PDE5), have gained recognition as pivotal regulators of male reproductive physiology, exerting significant influence on testicular function, sperm maturation, and overall fertility potential. Over the past several decades, investigations have expanded beyond the original therapeutic intent of PDE5 inhibitors for erectile dysfunction, exploring their broader reproductive implications. This narrative review integrates current evidence from in vitro studies, animal models, and clinical research to clarify the roles of PDEs in effecting the male reproductive tract, with an emphasis on the mechanistic pathways underlying cyclic nucleotide signaling, the cellular specificity of PDE isoform expression, and the effects of PDE5 inhibitors on Leydig and Sertoli cell functions. Although certain findings suggest potential improvements in sperm motility, semen parameters, and a more favorable biochemical milieu for spermatogenesis, inconsistencies in study design, limited sample sizes, and inadequate long-term data temper definitive conclusions. Addressing these gaps through standardized protocols, larger and more diverse patient cohorts, and explorations of mechanistic biomarkers could pave the way for incorporating PDE5 inhibitors into evidence-based fertility treatment strategies. In the future, such targeted approaches may inform individualized regimens, optimize male reproductive outcomes, and refine the clinical application of PDE5 inhibitors as part of comprehensive male fertility management.

An overview on pharmaceutical applications of phosphodiesterase enzyme 5 (PDE5) inhibitors

Phosphodiesterase enzyme 5 (PDE5) inhibitors have emerged as one of the leading molecules for the treatment of erectile dysfunction (ED). PDE5 inhibitors are categorized structurally into several classes. PDE5 inhibitors have been a multidisciplinary endeavor that attracts the attention of researchers because of their multiple pharmaceutical applications. Beyond their action on ED, PDE5 inhibitors are widely used in treatment of benign prostatic hypertrophy (BPH), Eisenmenger's syndrome, Raynaud's Disease, Intrauterine growth retardation (IUGR), Mountain sickness, Bladder pain syndrome/interstitial cystitis (BPS/IC), pulmonary arterial hypertension and type II diabetes (insulin resistance). In addition, PDE5 inhibitors also show promising antiproliferative activity, anti-Alzheimer and COX-1/COX-2 inhibitory activity (anti-inflammatory). Pharmacokinetics, Pharmacogenetics and toxicity of PDE5 inhibitors were finally explored. The diverse therapeutic applications, the high feasibility of structural modification and the appropriate pharmacokinetic properties of PDE5 inhibitors have motivated researchers to develop new scaffolds that have been either under clinical trials or approved by FDA and utilize them to overcome some recent global concerns, such as COVID-19.

Sildenafil and furosemide nanoparticles as a novel pharmacological treatment for acute renal failure in rats

Hospitalized patients often develop acute renal failure (ARF), which causes severe morbidity and death. This research investigates the potential renoprotective benefits of sildenafil and furosemide in glycerol-induced ARF, and measures kidney function metrics in response to nanoparticle versions of these medications. Inducing ARF is commonly done by injecting 50% glycerol intramuscularly. Rats underwent a 24-h period of dehydration and starvation before slaughter for renal function testing. We investigated urine analysis, markers of oxidative stress, histology of kidney tissue, immunohistochemistry analysis of caspase-3 and interleukin-1 beta (IL-1 β), kidney injury molecule-1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL), which are specific indicators of kidney tissue damage. The results of our study showed that the combination of sildenafil and furosemide, using both traditional and nanoparticle formulations, had a greater protective effect on the kidneys compared to using either drug alone. The recovery of renal tissue indicators, serum markers, and urine markers, which are indicative of organ damage, provides evidence of improvement. This was also indicated by the reduction in KIM-1 and NGAL tubular expression. The immunohistochemistry tests showed that the combination therapy, especially with the nanoforms, greatly improved the damaged cellular changes in the kidneys, as shown by higher levels of caspase-3 and IL-1β. According to the findings, a glycerol-induced rat model demonstrates that sildenafil and furosemide, either alone or in combination, in conventional or nanoparticulate forms, improve ARF dysfunction. The synergistic nanoparticulate compositions show remarkable effectiveness. This observation highlights the possible therapeutic implications for ARF treatment.

Cyclic Adenosine Monophosphate Signaling in Chronic Kidney Disease: Molecular Targets and Therapeutic Potentials

Chronic kidney disease (CKD) is characterized by a steady decline in kidney function and affects roughly 10% of the world's population. This review focuses on the critical function of cyclic adenosine monophosphate (cAMP) signaling in CKD, specifically how it influences both protective and pathogenic processes in the kidney. cAMP, a critical secondary messenger, controls a variety of cellular functions, including transcription, metabolism, mitochondrial homeostasis, cell proliferation, and apoptosis. Its compartmentalization inside cellular microdomains ensures accurate signaling. In kidney physiology, cAMP is required for hormone-regulated activities, particularly in the collecting duct, where it promotes water reabsorption through vasopressin signaling. Several illnesses, including Fabry disease, renal cell carcinoma, nephrogenic diabetes insipidus, Bartter syndrome, Liddle syndrome, diabetic nephropathy, autosomal dominant polycystic kidney disease, and renal tubular acidosis, have been linked to dysfunction in the cAMP system. Both cAMP analogs and phosphodiesterase inhibitors have the potential to improve kidney function and reduce kidney damage. Future research should focus on developing targeted PDE inhibitors for the treatment of CKD.

Inonotus obliquus (Chaga) against HFD/STZ-induced glucolipid metabolism disorders and abnormal renal functions by regulating NOS-cGMP-PDE5 signaling pathway

Our prior investigations have established that Inonotus obliquus (Chaga) possesses hypoglycemic effects. Persistent hyperglycemia is known to precipitate renal function abnormalities. The functionality of the kidneys is intricately linked to the levels of cyclic guanosine-3',5'-monophosphate (cGMP), which are influenced by the activities of nitric oxide synthase (NOS) and phosphodiesterase (PDE). Enhanced cGMP levels can be achieved either through the upregulation of NOS activity or the downregulation of PDE activity. The objective of the current study is to elucidate the effects of Chaga on disorders of glucolipid metabolism and renal abnormalities in rats with type 2 diabetes mellitus (T2DM), while concurrently examining the NOS-cGMP-PDE5 signaling pathway. A model of T2DM was developed in rats using a high-fat diet (HFD) combined with streptozotocin (STZ) administration, followed by treatment with Chaga extracts at doses of 50 and 100 mg·kg-1 for eight weeks. The findings revealed that Chaga not only mitigated metabolic dysfunctions, evidenced by improvements in fasting blood glucose, total cholesterol, triglycerides, and insulin resistance, but also ameliorated renal function markers, including serum creatinine, urine creatinine (UCr), blood urea nitrogen, 24-h urinary protein, and estimated creatinine clearance. Additionally, enhancements in glomerular volume, GBM thickness, podocyte foot process width (FPW), and the mRNA and protein expressions of podocyte markers, such as nephrin and wilms tumor-1, were observed. Chaga was found to elevate cGMP levels in both serum and kidney tissues by increasing mRNA and protein expressions of renal endothelial NOS and neural NOS, while simultaneously reducing the expressions of renal inducible NOS and PDE5. In summary, Chaga counteracts HFD/STZ-induced glucolipid metabolism and renal function disturbances by modulating the NOS-cGMP-PDE5 signaling pathway. This research supports the potential application of Chaga in the clinical prevention and treatment of T2DM and diabetic nephropathy (DN), with cGMP serving as a potential therapeutic target.

Current treatment options for erectile dysfunction in kidney transplant recipients

INTRODUCTION

Erectile dysfunction (ED) and kidney dysfunction share common risk factors linked to conditions involving endothelial impairment, such as coronary artery disease, dyslipidemia, diabetes mellitus, hypertension, smoking, and obesity. Men with chronic kidney disease experience a high incidence and prevalence of ED. While a functional renal graft can alleviate the issue for some patients, a significant portion of recipients still experience ED (20%-50%).

OBJECTIVES

This narrative review describes the variety of current treatments modalities on ED in kidney transplant recipients (KTRs) and their clinical outcomes.

METHODS

MEDLINE, Web of Science, PubMed, and Google Scholar were used to find eligible articles pertaining to the treatment options of ED in KTRs. A total of 64 articles were evaluated.

RESULTS

In KTRs, ED stems from a multifaceted etiology: anxiety, drug side effects, interference with penile vascularity, or the response of cavernosal muscle to neurotransmitters, along with changes in the endocrine milieu. A diverse range of treatments to restore erectile function has proven to be safe and effective for KTRs. Options include drug therapy, surgical interventions, intracavernosal injection therapies, vacuum erection devices, and extracorporeal shockwave therapy.

CONCLUSION

The initial treatment approach may involve the use of a phosphodiesterase type 5 inhibitors at a low dosage, especially if testosterone-circulating levels align with the diagnosis of hypogonadism. The consideration of a combination therapy involving testosterone and phosphodiesterase type 5 inhibitors should be contemplated due to the associated beneficial effects. Extracorporeal shockwave therapy has shown positive short-term clinical and physiological effects on erectile function in patients who did not respond to first-line treatments, resulting in spontaneous erections sufficient for sexual penetration in 50% of cases. Penile implants should be considered as third-line options based on specific patient needs and compliance with clinical conditions.

Advancements in Phosphodiesterase 5 Inhibitors: Unveiling Present and Future Perspectives

Phosphodiesterase 5 (PDE5) inhibitors presented themselves as important players in the nitric oxide/cGMP pathway, thus exerting a profound impact on various physiological and pathological processes. Beyond their well-known efficacy in treating male erectile dysfunction (ED) and pulmonary arterial hypertension (PAH), a plethora of studies have unveiled their significance in the treatment of a myriad of other diseases, including cognitive functions, heart failure, multiple drug resistance in cancer therapy, immune diseases, systemic sclerosis and others. This comprehensive review aims to provide an updated assessment of the crucial role played by PDE5 inhibitors (PDE5-Is) as disease-modifying agents taking their limiting side effects into consideration. From a medicinal chemistry and drug discovery perspective, the published PDE5-Is over the last 10 years and their binding characteristics are systemically discussed, and advancement in properties is exposed. A persistent challenge encountered with these agents lies in their limited isozyme selectivity; considering this obstacle, this review also highlights the breakthrough development of the recently reported PDE5 allosteric inhibitors, which exhibit an unparalleled level of selectivity that was rarely achievable by competitive inhibitors. The implications and potential impact of these novel allosteric inhibitors are meticulously explored. Additionally, the concept of multi-targeted ligands is critically evaluated in relation to PDE5-Is by inspecting the broader spectrum of their molecular interactions and effects. The objective of this review is to provide insight into the design of potent, selective PDE5-Is and an overview of their biological function, limitations, challenges, therapeutic potentials, undergoing clinical trials, future prospects and emerging uses, thus guiding upcoming endeavors in both academia and industry within this domain.

Understanding human aging and the fundamental cell signaling link in age-related diseases: the middle-aging hypovascularity hypoxia hypothesis

Aging-related hypoxia, oxidative stress, and inflammation pathophysiology are closely associated with human age-related carcinogenesis and chronic diseases. However, the connection between hypoxia and hormonal cell signaling pathways is unclear, but such human age-related comorbid diseases do coincide with the middle-aging period of declining sex hormonal signaling. This scoping review evaluates the relevant interdisciplinary evidence to assess the systems biology of function, regulation, and homeostasis in order to discern and decipher the etiology of the connection between hypoxia and hormonal signaling in human age-related comorbid diseases. The hypothesis charts the accumulating evidence to support the development of a hypoxic milieu and oxidative stress-inflammation pathophysiology in middle-aged individuals, as well as the induction of amyloidosis, autophagy, and epithelial-to-mesenchymal transition in aging-related degeneration. Taken together, this new approach and strategy can provide the clarity of concepts and patterns to determine the causes of declining vascularity hemodynamics (blood flow) and physiological oxygenation perfusion (oxygen bioavailability) in relation to oxygen homeostasis and vascularity that cause hypoxia (hypovascularity hypoxia). The middle-aging hypovascularity hypoxia hypothesis could provide the mechanistic interface connecting the endocrine, nitric oxide, and oxygen homeostasis signaling that is closely linked to the progressive conditions of degenerative hypertrophy, atrophy, fibrosis, and neoplasm. An in-depth understanding of these intrinsic biological processes of the developing middle-aged hypoxia could provide potential new strategies for time-dependent therapies in maintaining healthspan for healthy lifestyle aging, medical cost savings, and health system sustainability.

Effect of phosphodiesterase type 5 inhibitors on major adverse cardiovascular events and overall mortality in a large nationwide cohort of men with erectile dysfunction and cardiovascular risk factors: A retrospective, observational study based on healthcare claims and national death index data

BACKGROUND

Treatment with phosphodiesterase type 5 inhibitors (PDE-5is) is effective in treating erectile dysfunction (ED).

AIM

The objective of this study was to determine the effect of PDE-5is on the incidence of major adverse cardiovascular (CV) events (MACE; composite outcome of CV death, hospitalization for myocardial infarction, coronary revascularization, stroke, heart failure, and unstable angina pectoris) and overall mortality.

METHODS

A retrospective observational cohort study was conducted in a large US claims database in men with ≥1 diagnosis of ED without prior MACE within 1 year, from January 1, 2006, to October 31, 2020. The exposed group had ≥1 claim for PDE-5i and the unexposed group had no claims for PDE-5i, and the groups were matched up to 1:4 on baseline risk variables.

OUTCOME

The primary outcome was MACE and the secondary outcomes were overall mortality and individual components of MACE, determined by multivariable Cox proportional hazard modeling.

RESULTS

Matched plus multivariable analyses showed that MACE was lower by 13% in men exposed (n = 23 816) to PDE-5is (hazard ratio [HR] 0.87; 95% CI 0.79-0.95; P = .001) vs nonexposure (n = 48 682) over mean follow-up periods of 37 and 29 months, respectively, with lower incidence of coronary revascularization (HR 0.85; 95% CI 0.73-0.98; P = .029), heart failure (HR 0.83; 95% CI 0.72-0.97; P = .016), unstable angina (HR 0.78; 95% CI 0.64-0.96; P = .021), and CV death (HR 0.61; 95% CI 0.41-0.90; P = .014) with PDE-5i exposure. Phosphodiesterase type 5 inhibitor-exposed men had a 25% lower incidence of overall mortality (HR 0.75; 95% CI 0.65-0.87; P < .001). Men without coronary artery disease (CAD) but with CV risk factors at baseline showed a similar pattern. In the main study cohort, men in the highest quartile of PDE-5i exposure had the lowest incidence of MACE (HR 0.45; 95% CI 0.37-0.54; P < .001) and overall mortality (HR 0.51; 95% CI 0.37-0.71; P < .001) vs the lowest exposure quartile. In a subgroup with baseline type 2 diabetes (n = 6503), PDE-5i exposure was associated with a lower MACE risk (HR 0.79; 95% CI 0.64-0.97; P = .022).

CLINICAL IMPLICATIONS

PDE-5is may have cardioprotective effects.

STRENGTHS AND LIMITATIONS

Strengths are the large numbers of participants and consistency of the data; limitations include the retrospective nature of the study and unknown confounders.

CONCLUSIONS

In a large population of US men with ED, PDE-5i exposure was associated with lower incidence of MACE, CV death, and overall mortality risk compared to non-exposure. Risk reduction correlated with PDE-5i exposure level.

The PDE5 inhibitor, vardenafil, ameliorates progressive pathological changes in a focal segmental glomerulosclerosis mouse model

AIMS

Phosphodiesterase 5 inhibitors (PDE5is) inhibit the hydrolysis of cyclic guanosine 5'-monophosphate in smooth muscle cells and are a widely known treatment for erectile dysfunction. Accumulating evidence also suggests that PDE5is exhibit potential benefits in cardiovascular and chronic kidney diseases. In this study, we examined the therapeutic effects of a PDE5i, vardenafil (VAR), in a focal segmental glomerulosclerosis (FSGS) mouse model.

MATERIALS AND METHODS

FSGS was induced in BALB/c mice by the intravenous administration of Adriamycin (AD, 11 mg/kg of body weight). After 24 h, VAR (at 12.5 μg/ml) was given in drinking water ad libitum until the animals were sacrificed. At the end of the experiment, plasma and kidney samples were harvested to evaluate clinical parameters, histopathological changes, and alterations in transcriptome and protein expressions.

KEY FINDINGS

In this study, VAR treatment attenuated the deterioration of proteinuria, renal dysfunction, and hypercholesterolemia in AD-induced FSGS. Treatment with VAR exhibited reductions in the severity of both glomerulosclerosis and tubulointerstitial injury in the histological analysis. In addition to relieving AD-induced podocyte loss, VAR also preserved endothelial cells in glomerular capillaries and ameliorated the accumulation of collagen fibers in the mesangial area and Bowman's capsule basement membrane. In addition, VAR showed an ability to suppress transforming growth factor-β-induced fibroblast-to-myofibroblast transdifferentiation.

SIGNIFICANCE

Our data suggest that VAR exhibited reno-therapeutic effects via attenuating podocyte loss, preserving the integrity of the glomerular vasculature, and ameliorating fibrotic changes. These findings suggest that PDE5is might be a promising treatment modality for nephrotic syndrome.

Effects of phosphodiesterase 5 inhibition on cardiovascular function in resistant hypertension: A systematic review

Approximately 12-18% of hypertensive patients are diagnosed with resistant hypertension (RH). The risk of having worse cardiovascular outcomes is twice higher in those patients. The low effectiveness of conventional antihypertensive drugs in RH emphasizes the need to evaluate complementary drug therapies to achieve blood pressure (BP) control. Previous studies have demonstrated that phosphodiesterase 5 (PDE-5) inhibitors improve hemodynamics and reduce BP on essential hypertension. So, the authors aimed to summarize current clinical trials-based evidence published concerning the use of PDE-5 inhibitors on BP, cardiovascular function, and hemodynamics of patients with RH. We searched MEDLINE, EMBASE, LILACS, ClinicalTrials.gov, and WHO International Clinical Trials Registry databases on May 15th, 2020 using pre-defined search terms. Two independent reviewers assessed and extracted data from clinical trials that evaluated the effect of PDE-5 inhibitors on BP. We have included five articles in this systematic review. Four of them developed a single-day protocol, while one has developed a 14-day study. The main findings indicate that PDE-5 inhibitors ameliorate BP, vascular hemodynamics, and diastolic function parameters. Some data demonstrated improvement of endothelial function, but it was not a consensus. The side effects seemed to be limited and well-tolerated. In brief, our systematic review highlights the potential of PDE-5 inhibitors as a therapeutic alternative in addition to the multiple-drug regime for RH. Larger studies are still needed to determine whether the beneficial effects of PDE-5 inhibitors on RH would be maintained with chronic administration.