Beyond Erectile Dysfunction: cGMP-Specific Phosphodiesterase 5 Inhibitors for Other Clinical Disorders

A Phase I Study to Evaluate the Pharmacokinetics and Safety of TPN171 (a PDE5 Inhibitor) in Adults with Renal Impairment

TPN171, a phosphodiesterase 5 inhibitor, is under development for the treatment of male erectile dysfunction and pulmonary arterial hypertension in China. To investigate the pharmacokinetic properties and safety of TPN171 in individuals with severe renal impairment and normal renal function, an open-label, single-dose, parallel-group phase 1 study was conducted in 8 participants with severe renal impairment (glomerular filtration rate within 15-29 mL/min) and 8 participants having normal renal function, who received TNP171 tablets (10 mg) in the fasting state. As compared with those with normal renal function, the geometric mean ratios for maximum plasma concentration (Cmax), the area under the plasma concentration-time curve from time zero to the last quantifiable concentration (AUC0-t), and AUC extrapolated to infinite time (AUC0-∞) were 74.3%, 138%, and 137%, respectively. Elimination half-life was prolonged and clearance was decreased in severe renal impairment group. The adverse reaction rate showed no significant difference. All adverse events were mild intensity, and no participant was discontinued in this study. In conclusion, TPN171 can be cautiously used in patients with mild to severe renal impairment.

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.

Ovarian cancer and the heart: pathophysiology, chemotherapy-induced cardiotoxicity, and new therapeutic strategies

Ovarian Cancer (OC) is recognized as the most lethal gynecologic malignancy, characterized by numerous genetic mutations that trigger uncontrolled cellular growth and replication. Emerging evidence suggests that non-coding RNAs including miRNAs and lncRNAs significantly influence OC through their multiple roles including tumor initiation, progression, metastasis, immune evasion, and chemoresistance, making them promising diagnostic markers and therapeutic targets. The primary approach to treating OC typically involves cytoreductive surgery followed by chemotherapy. However, the chemotherapeutic agents, particularly the anthracyclines such as doxorubicin (DOX), are known for their cardiotoxic effects, which can range from acute to chronic, potentially leading to heart failure and death. To enhance the overall treatment response and to minimize cardiotoxicity, alternative strategies have been explored. These include the use of liposomal doxorubicin (DOXIL) as a substitute for DOX, various radiotherapies, immunotherapies, and the co-administration of angiotensin-converting enzyme inhibitors and/or beta-blockers. Phosphodiesterase-5 inhibitors (PDE5i) have also demonstrated efficacy in reducing cardiotoxicity linked to cancer treatments and in promoting apoptosis in cancer cells across multiple cancer types. Although there is no current clinical trial directly examining the impact of PDE5i on reducing cardiotoxicity in OC, however emerging therapies such as Withaferin A, PARP inhibitors, and nanoparticle combination therapy show promise. Additional research is essential to develop treatments that are both effective against OC and less harmful to the heart.

Role of interaction mode of phenanthrene derivatives as selective PDE5 inhibitors using molecular dynamics simulations and quantum chemical calculations

Phosphodiesterase type 5 (PDE5) inhibitors play a crucial role in blocking PDE5 to improve erectile dysfunction (ED). However, most PDE5 drugs revealed side effects including the loss of vision due to the PDE6 inhibition. Phenanthrene derivatives isolated from E. macrobulbon were previously reported as PDE5 inhibitors. Two phenanthrene derivatives (cpds 1-2) revealed better inhibition to PDE5 than PDE6 and cpd 1 is more selective to PDE5 than cpd 2. To elucidate why the phenanthrene derivatives could inhibit PDE5 and PDE6, their binding modes were investigated using molecular dynamics simulations and quantum chemical calculations, as compared to the PDE5 drugs. From the results, all four drugs and phenanthrene derivatives revealed similar π-π interactions to Phe820 in PDE5. Additional H-bond interaction to Gln817 in PDE5 resulted in better PDE5 inhibition of vardenafil and tadalafil. Moreover, cpds 1-2 were able to form the H-bond interaction with Asp764 in PDE5. In the case of the PDE6, the loss of π-π interaction to Phe776 and H-bond interaction to Gln773 indicated the important points for losing the PDE6 inhibition. In conclusion, to develop the new potent PDE5 inhibitors, not only the important interaction with PDE5 but also the interaction with PDE6 should be considered. In phenanthrene derivatives, the middle ring was significant to form π-π interactions to Phe820 in PDE5 and hydroxyl substituent was also the key part to form the H-bond interaction with Asp764 in PDE5. Principal component analysis (PCA) and free energy landscape (FEL) analysis indicated the stability of the system. The bioavailability, drug-likeness, and pharmacokinetics of phenanthrene derivatives were also predicted. These derivatives revealed good drug-likeness and GI absorption. The obtained results showed that phenanthrene derivatives could be interesting for the development of PDE5 inhibitors in the future.

Structure-based method for the discovery of selective inhibitors of PED 5 in erectile dysfunction therapy from the Pacific oyster peptides (Crassostrea gigas): Peptidomic analysis, molecular docking, and activity validation

Erectile dysfunction (ED) is a male sexual disorder mainly caused by a reduction in the cellular concentration of cyclic guanosine monophosphate (cGMP), which is degraded by phosphodiesterase type-5 (PDE-5). Oyster protein (OP) and its hydrolysates have been used for centuries to address male erectile dysfunction, however the mechanisms and evidence supporting their efficacy remain unclear. In this study, OP was hydrolyzed using trypsin to produce peptides that inhibit PDE-5. Following separation by ultrafiltration and Sephadex G-25, a total of 3202 peptides were identified. Virtual screening and molecular docking were employed to identify PDE-5 inhibitory peptides and elucidate their interaction mechanisms with PDE-5. Five peptides with the sequences FLF, LMF, LLW, FGPF, and IPW demonstrated strong interactions with PED5. The results indicated that the key binding sites critical for docking included Phe820, Gln817 and Val782 of the target receptor PED-5. The highest inhibition rate observed for FGPF was 94.6 %, while the inhibition rates for IPW and FLF were 89.0 % and 87.6 %, respectively. The lowest inhibition rate was recorded for LLW at 68 %. These findings suggest that these five peptides have the potential to serve as PDE-5 inhibitors in the health food industry and medicine.

Effect of long and short half-life PDE5 inhibitors on HbA1c levels: a systematic review and meta-analysis

Background

Phosphodiesterase 5 (PDE5) inhibitors, owing to their mechanism of action, have been gaining recognition as a potential case of drug repurposing and combination therapy for diabetes treatment. We aimed to examine the effect of long and short half-life PDE5 inhibitors have on Haemoglobin A1c (HbA1c) levels.

Methods

A systematic review and meta-analysis was conducted of randomised controlled trials (RCTs) in people with elevated HbA1c (>6%) to assess mean difference in HbA1c levels from baseline versus controls after any PDE5 inhibitor intervention of ≥4 weeks, excluding multiple interventions. Cochrane CENTRAL, PMC Medline, ClinicalTrials.gov, and WHO ICTRP were searched without language restrictions up to September 30, 2024. Summary data from published data were extracted. PRISMA and Cochrane guidelines used to extract and assess data using a random-effects meta-analysis. This study is registered with the Research Registry, reviewregistry1733.

Findings

Among 1096 studies identified, in analysis of 13 studies with 1083 baseline patients, long half-life PDE5 inhibitors (tadalafil, PF-00489791) had decreases in HbA1c while short half-life PDE5 inhibitors (sildenafil, avanafil) had no change. Five (38.5%) studies had a low risk of bias, and eight (61.5%) had some concerns. Long half-life inhibitors had significant mean decrease of -0.40% ([-0.66, -0.14], p = 0.002, I2 = 82%, 7.70% baseline HbA1c). Short half-life inhibitors had insignificant mean difference of +0.08% ([-0.16, 0.33], p = 0.51, I2 = 40%, 7.73% baseline HbA1c). In ≥8-week trials with participants with type 2 diabetes (T2D) and mean HbA1c ≥ 6.5%, long half-life inhibitors had significant mean decrease of -0.50% ([-0.83, -0.17], I2 = 88%, p = 0.003); short half-life inhibitors had significant mean increase of +0.36% ([0.03, 0.68], I2 = 3%, p = 0.03).

Interpretation

At the well-controlled HbA1c of the participants, previous literature shows current diabetes treatments have similar HbA1c decreases, so the HbA1c mean difference of long half-life PDE5 inhibitors may indeed be clinically relevant. This suggests future investigation into PDE5 inhibitors as part of combination therapy or as therapy for high HbA1c individuals is needed, especially because of variable risk of biases, homogeneity, and sample sizes in our study.

Funding

None.

Cyclic nucleotide phosphodiesterases as drug targets

Cyclic nucleotides are synthesized by adenylyl and/or guanylyl cyclase, and downstream of this synthesis, the cyclic nucleotide phosphodiesterase families (PDEs) specifically hydrolyze cyclic nucleotides. PDEs control cyclic adenosine-3',5'monophosphate (cAMP) and cyclic guanosine-3',5'-monophosphate (cGMP) intracellular levels by mediating their quick return to the basal steady state levels. This often takes place in subcellular nanodomains. Thus, PDEs govern short-term protein phosphorylation, long-term protein expression, and even epigenetic mechanisms by modulating cyclic nucleotide levels. Consequently, their involvement in both health and disease is extensively investigated. PDE inhibition has emerged as a promising clinical intervention method, with ongoing developments aiming to enhance its efficacy and applicability. In this comprehensive review, we extensively look into the intricate landscape of PDEs biochemistry, exploring their diverse roles in various tissues. Furthermore, we outline the underlying mechanisms of PDEs in different pathophysiological conditions. Additionally, we review the application of PDE inhibition in related diseases, shedding light on current advancements and future prospects for clinical intervention. SIGNIFICANCE STATEMENT: Regulating PDEs is a critical checkpoint for numerous (patho)physiological conditions. However, despite the development of several PDE inhibitors aimed at controlling overactivated PDEs, their applicability in clinical settings poses challenges. In this context, our focus is on pharmacodynamics and the structure activity of PDEs, aiming to illustrate how selectivity and efficacy can be optimized. Additionally, this review points to current preclinical and clinical evidence that depicts various optimization efforts and indications.

Repurposing of phosphodiesterase-5 inhibitor sildenafil as a therapeutic agent to prevent gastric cancer growth through suppressing c-MYC stability for IL-6 transcription

Phosphodiesterase-5 (PDE5) inhibitors have shown promise as anti-cancer agents in malignancies. However, their specific effects on gastric cancer (GC) and the underlying mechanisms remain elusive. Our aim was to investigate this by combining evidence from population-based studies with data obtained from in vivo and in vitro experiments. By combing a couple of nationwide Swedish registers, GC patients who received PDE5 inhibitors were compared to matched controls while adjusting for confounding factors. The anti-tumor effect and mechanism of the PDE5 inhibitor sildenafil were evaluated via using tumor cells, patient-derived tumor organoids and xenograft animal models in GC. A total of 161 Swedish GC patients from a nationwide population-based cohort who received post-diagnostic PDE5 inhibitors demonstrated lower cancer-specific mortality compared to the controls (HR = 0.66, 95% CI = 0.47-0.92, P = 0.016). Functionally, the PDE5 inhibitor sildenafil exhibited the suppressive ability to prevent oncogenic growth in GC. Mechanistically, sildenafil restrained GC growth by directly activating PKG through PDE5 inhibition for regulating c-MYC expression via its phosphorylation and ubiquitination degradation, thereby suppressing c-MYC stability for IL-6 transcription within the downstream IL-6/JAK/STAT3 signalling pathway. The PDE5 inhibitor sildenafil may serve as a promising adjuvant for GC therapy if further randomized clinical trials confirm its efficacy.

Activation of the 26S Proteasome to Reduce Proteotoxic Stress and Improve the Efficacy of PROTACs

The 26S proteasome degrades the majority of cellular proteins and affects all aspects of cellular life. Therefore, the 26S proteasome abundance, proper assembly, and activity in different life contexts need to be precisely controlled. Impaired proteasome activity is considered a causative factor in several serious disorders. Recent advances in proteasome biology have revealed that the proteasome can be activated by different factors or small molecules. Thus, activated ubiquitin-dependent proteasome degradation has effects such as extending the lifespan in different models, preventing the accumulation of protein aggregates, and reducing their negative impact on cells. Increased 26S proteasome-mediated degradation reduces proteotoxic stress and can potentially improve the efficacy of engineered degraders, such as PROTACs, particularly in situations characterized by proteasome malfunction. Here, emerging ideas and recent insights into the pharmacological activation of the proteasome at the transcriptional and posttranslational levels are summarized.

Hallmarks of aging: middle-aging hypovascularity, tissue perfusion and nitric oxide perspective on healthspan

Aging is a complex process marked by various changes at both cellular and systemic levels, impacting the functioning and lifespan of organisms. Over time, researchers have pinpointed several significant hallmarks of aging that lead to the gradual deterioration of tissue function, regulation, and homeostasis associated with aging in humans. Despite this, the intricate interactions and cumulative effects of these hallmarks are still mostly uncharted territory. Understanding this complex web is a major challenge in Geroscience, yet it is crucial for developing effective strategies that promote healthy aging, reduce medical costs, and ensure the sustainability of health systems. Gaining insights in this area is essential for creating interventions that can slow the aging process, enhance healthspan, and decrease the likelihood of age-related diseases. The integration of knowledge from various fields concerning the middle-aging nitric oxide (NO)-mediated hypovascularity hypoxia hemodynamic hypothesis points to a systems-based approach to the biological hallmarks of aging. Key evidence suggests a systemic connection between the endocrine system (specifically sex hormones), endogenous NO deficiency, and the vascular system, which serves as a network of microvascular structures crucial for tissue perfusion functions at cellular level. These processes also involve oxidative stress and inflammation triggered by hypoxia.

Phosphodiesterases: Evolving Concepts and Implications for Human Therapeutics

Phosphodiesterases (PDEs) are a superfamily of enzymes that hydrolyze cyclic nucleotides. While the 11 PDE subfamilies share common features, key differences confer signaling specificity. The differences include substrate selectivity, enzymatic activity regulation, tissue expression, and subcellular localization. Selective inhibitors of each subfamily have elucidated the protean role of PDEs in normal cell function. PDEs are also linked to diseases, some of which affect the immune, cardiac, and vascular systems. Selective PDE inhibitors are clinically used to treat these specific disorders. Ongoing preclinical studies and clinical trials are likely to lead to the approval of additional PDE-targeting drugs for therapy in human disease. In this review, we discuss the structure and function of PDEs and examine current and evolving therapeutic uses of PDE inhibitors, highlighting their mechanisms and innovative applications that could further leverage this crucial family of enzymes in clinical settings.

Inhibitors of malaria parasite cyclic nucleotide phosphodiesterases block asexual blood-stage development and mosquito transmission

Cyclic nucleotide-dependent phosphodiesterases (PDEs) play essential roles in regulating the malaria parasite life cycle, suggesting that they may be promising antimalarial drug targets. PDE inhibitors are used safely to treat a range of noninfectious human disorders. Here, we report three subseries of fast-acting and potent Plasmodium falciparum PDEβ inhibitors that block asexual blood-stage parasite development and that are also active against human clinical isolates. Two of the inhibitor subseries also have potent transmission-blocking activity by targeting PDEs expressed during sexual parasite development. In vitro drug selection experiments generated parasites with moderately reduced susceptibility to the inhibitors. Whole-genome sequencing of these parasites detected no mutations in PDEβ but rather mutations in downstream effectors: either the catalytic or regulatory subunits of cyclic adenosine monophosphate-dependent protein kinase (PKA) or in the 3-phosphoinositide-dependent protein kinase that is required for PKA activation. Several properties of these P. falciparum PDE inhibitor series make them attractive for further progression through the antimalarial drug discovery pipeline.

Sildenafil citrate induces prostatic hyperplasia in BPH model rats and aged rats

Erectile dysfunction (ED), a prevalent disease among middle-aged and elderly males, significantly impacts both patient and partner quality of life. Phosphodiesterase type 5 inhibitor (PDE5i) represents an effective therapeutic method for ED. Given their widespread global utilization, concerns arise regarding potential reproduction-related problems arising from clinical use. During the extensive development of PDE5i, we speculated that the potential of these inhibitors to variably induce prostatic hyperplasia, but this field remains unexplored. In order to verify the male reproductive toxicity of PDE5i, sildenafil citrate at doses of 5, 10 and 20 mg/kg was administered in BPH model rats and aged rats. Anatomical and pathological analyses indicate a compelling association between sildenafil citrate administration and the promotion of prostatic hyperplasia in both BPH model rats and aged rats. Serum analysis showed that serum prostate-binding protein (PBP) exhibited a non-significant but increasing trend following administration of sildenafil citrate to BPH model rats. Furthermore, significant increase in serum levels of E2 and T, as well as T in dorsal lobe prostate tissue of aged rats, were observed compared to the model control group. These results confirm the hypothesis that sildenafil citrate has reproductive toxicity in males.

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.

3DSTarPred: A Web Server for Target Prediction of Bioactive Small Molecules Based on 3D Shape Similarity

Target identification plays a critical role in preclinical drug development. The in silico approach has been developed and widely applied to assist medicinal chemists and pharmacologists in drug target identification. There are many target prediction web servers available today that have revealed both advantages and shortcomings in practical applications. Here, we present 3DSTarPred, a web server for three-dimensional (3D) shape similarity-based target prediction of small molecules. A benchmark study showed that 3DSTarPred achieved a target prediction success rate of 76.27%, which was higher than that of existing target prediction web servers. In addition, the performance of 3DSTarPred in the target prediction of diverse substructures/superstructures was also better than that of the existing target prediction web servers. In case studies, 3DSTarPred was used to identify the potential targets of two small molecules, one being kaempferol, a natural lead compound for the treatment of Alzheimer's disease (AD), and the other being sildenafil, a candidate for drug repurposing in AD. The case studies further demonstrated the reliability and success of 3DSTarPred in practice. The 3DSTarPred server is freely available at http://3dstarpred.pumc.wecomput.com.

The aging heart in focus: The advanced understanding of heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) accounts for 50 % of heart failure (HF) cases, making it the most common type of HF, and its prevalence continues to increase in the aging society. HFpEF is a systemic syndrome resulting from many risk factors, such as aging, metabolic syndrome, and hypertension, and its clinical features are highly heterogeneous in different populations. HFpEF syndrome involves the dysfunction of multiple organs, including the heart, lung, muscle, and vascular system. The heart shows dysfunction of various cells, including cardiomyocytes, endothelial cells, fibroblasts, adipocytes, and immune cells. The complex etiology and pathobiology limit experimental research on HFpEF in animal models, delaying a comprehensive understanding of the mechanisms and making treatment difficult. Recently, many scientists and cardiologists have attempted to improve the clinical outcomes of HFpEF. Recent advances in clinically related animal models and systemic pathology studies have improved our understanding of HFpEF, and clinical trials involving sodium-glucose cotransporter 2 inhibitors have significantly enhanced our confidence in treating HFpEF. This review provides an updated comprehensive discussion of the etiology and pathobiology, molecular and cellular mechanisms, preclinical animal models, and therapeutic trials in animals and patients to enhance our understanding of HFpEF and improve clinical outcomes.

Challenging the Norm: The Unrecognized Impact of Soluble Guanylyl Cyclase Subunits in Cancer

Since the discovery of nitric oxide (NO), a long journey has led us to the present, during which much knowledge has been gained about its pathway members and their roles in physiological and various pathophysiological conditions. Soluble guanylyl cyclase (sGC), the main NO receptor composed of the sGCα1 and sGCβ1 subunits, has been one of the central figures in this narrative. However, the sGCα1 and sGCβ1 subunits remained obscured by the focus on sGC's enzymatic activity for many years. In this review, we restore the significance of the sGCα1 and sGCβ1 subunits by compiling and analyzing available but previously overlooked information regarding their roles beyond enzymatic activity. We delve into the basics of sGC expression regulation, from its transcriptional regulation to its interaction with proteins, placing particular emphasis on evidence thus far demonstrating the actions of each sGC subunit in different tumor models. Exploring the roles of sGC subunits in cancer offers a valuable opportunity to enhance our understanding of tumor biology and discover new therapeutic avenues.

Pharmacokinetics and Bioequivalence of Vardenafil Hydrochloride in Healthy Chinese Volunteers

Vardenafil hydrochloride tablet is an inhibitor of phosphodiesterase type 5, primarily for the treatment of erectile dysfunction. This postprandial study evaluated the pharmacokinetics and bioequivalence of the test and reference formulations of vardenafil hydrochloride tablets in healthy Chinese volunteers. An open, randomized, single-center, single-dose, 2-period, 2-sequence bioequivalence test was conducted on 66 healthy subjects under fed conditions. Subjects were randomly assigned to a 20-mg test or reference formulation with a 7-day washout period. Venous blood samples (4 mL) were collected from each subject 25 times spanning predose (0 hour) to 24 hours after dosing. The plasma concentration of vardenafil was determined by high-performance liquid chromatography-tandem mass spectrometry. Sixty-two volunteers completed the study. Under fed conditions, the maximum plasma concentration was 29.1 ng/mL, the area under the concentration-time curve (AUC) from time 0 to the time of the last measurable concentration was 85.3 ng•h/mL, and AUC from time 0 to infinity was 87.1 ng•h/mL. The 90% confidence intervals of the geometric mean ratio of AUC time 0 to the time of the last measurable concentration and AUC from time 0 to infinity were within the bioequivalence acceptance range of 0.80-1.25. The test formulation was a bioequivalent alternative to the reference formulation when taken under fed conditions in healthy Chinese subjects.

Exosomes secreted by adipose mesenchymal stem cells overexpressing circPIP5K1C exert

BACKGROUND

Erectile dysfunction (ED) seriously affects men's normal life, and obstructive sleep apnoea (OSA) has been diagnosed as a causative factor. Currently, exosomes secreted by adipose mesenchymal stem cells (ADSC) have been used in the non-clinical experimental treatment of ED disease with prominent efficacy due to the advantages of high stability and no immune exclusion.

METHODS

In this study, chronic intermittent hypoxia (CIH) exposure was used to induce ED-corresponding phenotypes in Sprague Dawley (SD) rats as well as in cavernous smooth muscle cells (CCSMCs). ED symptoms were treated using exosomes secreted by ADSCs overexpressing circPIP5K1C (EXO-circ) injected into the rat corpus cavernosum.

RESULTS

EXO-circ has the effect of ameliorating ED induced by CIH exposure in rats, the mechanism of which is to promote the expression of the downstream target gene SMURF1 after adsorption of miR-153-3p through the sponge so that SMURF1 and PFKFB3 occur protein-protein binding and ubiquitination degradation of PFKFB3 appears to inhibit the occurrence of spongiotic smooth muscle cells glycolysis, and to restore the function of the smooth muscle.

CONCLUSIONS

These findings show that EXO-circ have a promising therapeutic potential in OSA-induced ED.

Update on clinical and experimental management of diabetic cardiomyopathy: addressing current and future therapy

Diabetic cardiomyopathy (DCM) is a severe secondary complication of type 2 diabetes mellitus (T2DM) that is diagnosed as a heart disease occurring in the absence of any previous cardiovascular pathology in diabetic patients. Although it is still lacking an exact definition as it combines aspects of both pathologies - T2DM and heart failure, more evidence comes forward that declares DCM as one complex disease that should be treated separately. It is the ambiguous pathological phenotype, symptoms or biomarkers that makes DCM hard to diagnose and screen for its early onset. This re-view provides an updated look on the novel advances in DCM diagnosis and treatment in the experimental and clinical settings. Management of patients with DCM proposes a challenge by itself and we aim to help navigate and advice clinicians with early screening and pharmacotherapy of DCM.

Dietary Beetroot Juice - Effects in Patients with COPD: A Review

Chronic Obstructive Pulmonary Disease (COPD) exerts a severe toll on human health and the economy, with high prevalence and mortality rates. The search for bioactive components effective in the treatment of COPD has become a focal point of research. Beetroot juice, readily accessible and cost-effective, is noted for its ability to enhance athletic performance and for its preventive and therapeutic impact on hypertension. Beetroot juice is a rich source of dietary nitrates and modulates physiological processes via the nitrate-nitrite- nitric oxide pathway, exerting multiple beneficial effects such as antihypertensive, bronchodilatory, anti-inflammatory, antioxidant, hypoglycemic, and lipid-lowering actions. This paper provides a review of the existing research on the effects of beetroot juice on COPD, summarizing its potential in enhancing exercise capacity, lowering blood pressure, improving vascular function, and ameliorating sleep quality among patients with COPD. The review serves as a reference for the prospective use of beetroot juice in the symptomatic improvement of COPD, as well as in the prevention of exacerbations and associated comorbidities.

Differences in ocular adverse events associated with phosphodiesterase-5 inhibitors: a real-world pharmacovigilance study

OBJECTIVE

Our study aims to characterize the ocular safety profiles of phosphodiesterase type 5 (PDE5) inhibitors and explore the differences among different PDE5 inhibitors.

METHODS

We analyzed reports on ocular adverse events associated with sildenafil, vardenafil and tadalafil submitted to the FDA Adverse Event Reporting System (FAERS) database from the first quarter of 2004 to the first quarter of 2023. Disproportionality analysis was conducted to evaluate reporting risk profiles.

RESULTS

Among 61,211 reports qualifying for analysis, 5,127 involved sildenafil, 832 vardenafil, and 3,733 tadalafil. All PDE5 inhibitors showed increased reporting odds ratios (ROR) for ocular adverse events, with vardenafil highest (ROR 4.47) followed by sildenafil and tadalafil. Key ocular adverse events included cyanopsia, optic ischemic neuropathy, visual field defects, unilateral blindness and blindness. Sildenafil showed the highest disproportionality for cyanopsia (ROR 1148.11) while vardenafil and tadalafil showed the highest disproportionality for optic ischemic neuropathy. Time-to-onset analysis also revealed significant differences, with sildenafil having a later median time-to-onset compared to vardenafil and tadalafil.

CONCLUSIONS

This comprehensive pharmacovigilance study reveals distinct patterns of ocular adverse events associated with PDE5 inhibitors. These findings contribute to a better understanding of the safety profiles of PDE5 inhibitors and may guide healthcare professionals in clinical decision-making.

Anti-inflammatory and anti-oxidant action of tadalafil in testicular regeneration process after heat stress

Tadalafil, a potent phosphodiesterase inhibitor 5 (PDE-5), is commonly used for the management of erectile dysfunction. However, its therapeutic potential extends beyond this indication. This study aimed to investigate the impact of tadalafil on the recovery of testicular parenchyma in male Wistar rats exposed to testicular thermal stress. Fifty-four Wistar rats were subjected to testicular thermal stress and randomly assigned to receive either tadalafil treatment (TAD) or no treatment (control). TAD was administered intraperitoneally at a dose of either 0.9 mg/kg or 1.8 mg/kg. Biometric parameters, histopathological assessment of the testis, serum testosterone levels, oxidative stress, and interleukin levels were evaluated on days 7, 15, and 30 after thermal shock. The animals were euthanized at the end of each experimental period, and samples were collected. TAD treatment maintained testicular weight and reduced the testicular degenerative process up to day 7 post-injury. However, despite TAD therapy, serum testosterone levels were decreased in the treated groups at days 7 and 15 post-thermal stress. TAD also decreased TNF-α and NO levels at different doses but had no effect on IL-6. The treatment with TAD after heat shock demonstrated anti-inflammatory and antioxidant properties but did not prevent the aggravation of testicular lesions in subsequent periods, even with the systematic reduction in TNF-α and NO levels. Therefore, this selective PDE-5 inhibitor, at the dosages used, did not have a positive impact on testosterone levels during the post-thermal stress period, which could compromise the resumption of the spermatogenic process.

Alzheimer's disease increases the risk of erectile dysfunction independent of cardiovascular diseases: A mendelian randomization study

BACKGROUND

Previous research has underscored the correlation between Alzheimer's disease (AD) and erectile dysfunction (ED). However, due to inherent limitations of observational studies, the causative relationship remains inconclusive.

METHODS

Utilizing publicly available data from genome-wide association studies (GWAS) summary statistics, this study probed the potential causal association between AD and ED using univariate Mendelian randomization (MR). Further, the multivariable MR assessed the confounding effects of six cardiovascular diseases (CVDs). The primary approach employed was inverse variance weighted (IVW), supplemented by three additional methods. A series of sensitivity analyses were conducted to ensure the robustness of the results.

RESULTS

In the forward MR analysis, the IVW method revealed causal evidence of genetically predicted AD being a risk factor for ED (OR = 1.077, 95% CI 1.007∼1.152, P = 0.031). Reverse analysis did not demonstrate any causal evidence linking ED to AD (OR = 1.018, 95% CI 0.974∼1.063, P = 0.430). Multivariable MR analysis showed that after adjusting for coronary heart disease (OR = 1.082, 95% CI 0.009∼1.160, P = 0.027), myocardial infarction (OR = 1.085, 95% CI 1.012∼1.163, P = 0.022), atrial fibrillation (OR = 1.076, 95% CI 1.002∼1.154, P = 0.043), heart failure (OR = 1.103, 95% CI 1.024∼1.188, P = 0.010), ischemic stroke (OR = 1.079, 95% CI 1.009∼1.154, P = 0.027), hypertension (OR = 1.092, 95% CI 1.011∼1.180, P = 0.025), and all models (OR = 1.115, 95% CI 1.024∼1.214, P = 0.012), the causal association between AD and ED persisted. Sensitivity analyses confirmed the absence of pleiotropy, heterogeneity, and outliers, validating the robustness of our results (P > 0.05).

CONCLUSIONS

This MR study consistently evidences a causal effect of genetically predicted AD on the risk of ED, independent of certain CVDs, yet offers no evidence for a reverse effect from ED.

Role of Phosphodiesterases in Biology and Pathology 2.0

Phosphodiesterases (PDEs) are ubiquitous enzymes that hydrolyse cAMP and cGMP second messengers temporally, spatially, and integratedly according to their expression and compartmentalization inside the cell [...].

Adapting nitric oxide: A review of its foundation, uses in austere medical conditions, and emerging applications

Nitric oxide was first identified as a novel and effective treatment for persistent pulmonary hypertension of the newborn (PPHN), and has since been found to be efficacious in treating acute respiratory distress syndrome (ARDS) and pulmonary hypertension. Physicians and researchers have also found it shows promise in resource-constrained settings, both within and outside of the hospital, such as in high altitude pulmonary edema (HAPE) and COVID-19. The treatment has been well tolerated in these settings, and is both efficacious and versatile when studied across a variety of clinical environments. Advancements in inhaled nitric oxide continue, and the gas is worthy of investigation as physicians contend with new respiratory and cardiovascular illnesses, as well as unforeseen logistical challenges.

Age-related pharmacokinetics differences were observed between young and elderly populations of a novel PDE5 inhibitor, youkenafil, and its metabolite M459

PURPOSE

Youkenafil is a novel oral selective PDE5 inhibitor for treating Erectile Dysfunction. This investigation assessed pharmacokinetics (PK), safety, and tolerability of youkenafil and its main metabolite (M459) after taking 100 mg youkenafil hydrochloride tablets in elderly and young subjects.

METHODS

This Phase I, single-center, open-label, parallel-group, single-dose study was conducted on 24 individuals (12 elders and 12 youngsters). Each subject received a single oral 100 mg youkenafil hydrochloride tablets. Blood samples were collected before medication and up to 48 h after medication for PK analysis. Safety and tolerability were also assessed, including treatment-emergent adverse events (TEAEs), laboratory tests, 12-lead ECG, vital sign inspections, color vision examinations, and physical examinations.

RESULTS

Plasma concentrations of youkenafil and M459 were quantified. PK parameters were determined by non-compartmental analysis. Median Tmax of elderly and young groups were both 0.733 h. However, Cmax, AUC0-t, and AUC0-∞ of youkenafil were separately 16.8 %, 37.2 %, and 37.5 % higher in elders and t1/2 of youkenafil was 2.1 h longer in elders. More great differences were observed for M459. T1/2 values were 4.05 h longer in elders, with Cmax, AUC0-t and AUC0-∞ 73.7 %, 81.1 %, and 81.4 % higher in elders. Two (8.3 %) elderly subjects reported TEAEs (all grade Ⅰ in severity) and both recovered without any treatment. No serious adverse reactions (SAEs) or serious unexpected suspected adverse reactions (SUSARs) occurred in this study.

CONCLUSIONS

This was the first PK research of youkenafil and M459 in elderly men. PK parameters differences between youkenafil and M459 were comparable between elderly and young groups. Moreover, safety and tolerability of youkenafil were favorable in both groups.

Phosphodiesterase type 5 inhibitors related hearing impairment: a real world study based on the FDA adverse event reporting system

Recent studies focused on exploring phosphodiesterase type 5 inhibitors (PDE5Is)-related hearing impairment. This study aimed to comprehensively explore real-world hearing impairment associated with PDE5Is based on the US Food and Drug Administration Adverse Event Reporting System (FAERS). The characteristics and correlation of PDE5Is-related hearing impairment reported in the FAERS database from the fourth quarter of 2003 to the second quarter of 2023 were analyzed using disproportionality analysis. The Standardized Medical Dictionary for Regulatory Activities (MedDRA) Queries (SMQs) were used to analyze the adverse events (AEs) of hearing impairment. A total of 1,438 reported cases of hearing impairment were associated with four PDE5Is, revealing statistically significant reporting odds ratio (ROR), proportional reporting ratio (PRR), and information component (IC) with the SMQ. The average age of all patients was more than 55 years, over 70% of AEs were reported in men. Most of the reported cases were from the United States. Reports for all the drugs indicated an increase since 2008, except for avanafil. This study showed that the disability rates of PDE5Is were 8.14-40%, the rates of initial or prolonged hospitalization were 6.21-10.24%, and the rates of required intervention were 3.31-9.45%. The pharmacovigilance study identified a potential risk of hearing impairment associated with PDE5Is, indicating the need for continuous monitoring and appropriate management.

LC-MS/MS methods for simultaneous determination of youkenafil and its metabolite M1 in human seminal plasma and plasma: Application to evaluate the acute effect of youkenafil on semen quality and its pharmacokinetics in human

Youkenafil is a novel Phosphodiesterase type 5 inhibitor used for treating erectile dysfunction. N-desethyl compound of youkenafil (M1) is its main active metabolite. In this study, two methods were developed and validated for the simultaneous determination of youkenafil and M1 by HPLC-MS/MS in human matrices including seminal plasma and plasma, in which the multiple reaction monitoring and electrospray ionization in positive mode were adopted, and the deuterated youkenafil (youkenafil-d5) was selected as the internal standard. The collected semen sample was kept at room temperature for approximately 30 min until fully liquefied. The volume of the liquefied semen was measured and then divided into two parts. One part was centrifuged to obtain the seminal plasma for the content detection of youkenafil and M1, while the other part was used for routine semen analysis. The chromatographic separation was accomplished with the column of Poroshell 120 EC-C18 (5 × 2.1 mm, 2.7 μm, Agilent). Protein precipitation with methanol was used for the pretreatment of seminal plasma and plasma. The intra-run and inter-run precisions were less than 6.4 % (relative standard deviation) and accuracies were all within -4.7 %-6.8 % (relative error) in both matrices. All other validated bioanalytical parameters were within the acceptance criteria set by the FDA. The methods were successfully applied to different clinical studies of youkenafil. In the clinical study of the acute effect of youkenafil on semen quality in healthy males, the content of youkenafil in seminal plasma was extremely low. Concentrations of youkenafil and M1 in seminal plasma were lower than those in plasma, at 20.7 % and 4.49 % of the plasma concentration, respectively. There was no significant acute effect of youkenafil on semen quality. In the pharmacokinetic study of youkenafil after single dose-escalation administration, the exposure to youkenafil and M1 was non-linear with the dose in the range of 100-400 mg.

Novel drug therapy of acute hepatic failure induced in rats by a combination of tadalafil and Lepidium sativum

BACKGROUND

Hepatocyte death and a systemic inflammatory response are the outcome of a complex chain of events mediated by numerous inflammatory cells and chemical mediators. The point of this study was to find out if tadalafil and/or Lepidium sativum (L. sativum) could help people who have been exposed to carbon tetrachloride (CCL4) and are experiencing acute moderate liver failure. This was especially true when the two were used together.

METHOD AND MATERIALS

To cause mild liver failure 24 h before sacrifice, a single oral dosage of CCL4 (2.5 mL/kg b.w.) (50% in olive oil) was utilized. Furthermore, immunohistochemical expression of nuclear factor kappa B (NF-κB) as well as histological abnormalities were performed on liver tissue.

RESULTS

The results showed that tadalafil and/or L. sativum, especially in combination, performed well to cure acute mild liver failure caused by CCL4. This was demonstrated by a decrease in NF-κB expression in the liver tissue and an improvement in organ damage markers observed in the blood and liver tissues. Furthermore, such therapy reduced interleukin1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) levels in the liver tissue. It's worth noting that the tested combination resulted in greater liver improvement.

CONCLUSIONS

According to the findings, tadalafil and L. sativum, particularly in combination, have the ability to protect the liver from the negative effects of CCL4 exposure. Because of its capacity to improve liver function, restore redox equilibrium, and decrease inflammatory mediators, it is a prospective option for mitigating the negative effects of common environmental pollutants such as CCL4.

Fibroblasts enable penile erection

Perivascular fibroblasts may underlie erectile dysfunction.

A drug target for erectile dysfunction to help improve fertility, sexual activity, and wellbeing: mendelian randomisation study

OBJECTIVE

To investigate the association of genetically proxied (using a surrogate biomarker) inhibition of phosphodiesterase 5 (PDE5), an established drug target for erectile dysfunction, with fertility, sexual behaviour, and subjective wellbeing.

DESIGN

Two sample cis-mendelian randomisation study.

SETTING

Summary data on genetic associations obtained from the International Consortium for Blood Pressure and UK Biobank.

PARTICIPANTS

Individuals of European ancestry from the International Consortium for Blood Pressure (n=757 601) for estimating PDE5 inhibition (using the surrogate biomarker of diastolic blood pressure reduction), and UK Biobank (n=211 840) for estimating the fertility, sexual behaviour, and subjective wellbeing outcomes in male participants.

INTERVENTION

Genetically proxied PDE5 inhibition.

MAIN OUTCOME MEASURES

Number of children fathered, number of sexual partners, probability of never having had sexual intercourse, and subjective wellbeing.

RESULTS

Genetically proxied PDE5 inhibition was associated with male participants having 0.28 (95% confidence interval 0.16 to 0.39) more children (false discovery rate corrected P<0.001). This association was not identified in female participants. No evidence was found of an association between genetically proxied PDE5 inhibition and number of sexual partners, probability of never having had sexual intercourse, or self-reported wellbeing in male participants.

CONCLUSIONS

The findings of this study provide genetic support for PDE5 inhibition potentially increasing the number of children fathered by male individuals. Absence of this association in female participants supports increased propensity for sustained and robust penile erections as a potential underlying mechanism. Further studies are required to confirm this, however, and these findings should not promote indiscriminate use of PDE5 inhibitors, which can also have harmful adverse effects.

Counteracting Immunosenescence-Which Therapeutic Strategies Are Promising?

Aging attenuates the overall responsiveness of the immune system to eradicate pathogens. The increased production of pro-inflammatory cytokines by innate immune cells under basal conditions, termed inflammaging, contributes to impaired innate immune responsiveness towards pathogen-mediated stimulation and limits antigen-presenting activity. Adaptive immune responses are attenuated as well due to lowered numbers of naïve lymphocytes and their impaired responsiveness towards antigen-specific stimulation. Additionally, the numbers of immunoregulatory cell types, comprising regulatory T cells and myeloid-derived suppressor cells, that inhibit the activity of innate and adaptive immune cells are elevated. This review aims to summarize our knowledge on the cellular and molecular causes of immunosenescence while also taking into account senescence effects that constitute immune evasion mechanisms in the case of chronic viral infections and cancer. For tumor therapy numerous nanoformulated drugs have been developed to overcome poor solubility of compounds and to enable cell-directed delivery in order to restore immune functions, e.g., by addressing dysregulated signaling pathways. Further, nanovaccines which efficiently address antigen-presenting cells to mount sustained anti-tumor immune responses have been clinically evaluated. Further, senolytics that selectively deplete senescent cells are being tested in a number of clinical trials. Here we discuss the potential use of such drugs to improve anti-aging therapy.

A methane-cGMP module positively influences adventitious rooting

KEY MESSAGE

Endogenous cGMP operates downstream of CH₄ control of adventitious rooting, following by the regulation in the expression of cell cycle regulatory and auxin signaling-related genes. Methane (CH₄) is a natural product from plants and microorganisms. Although exogenously applied CH₄ and cyclic guanosine monophosphate (cGMP) are separately confirmed to be involved in the control of adventitious root (AR) formation, the possible interaction still remains elusive. Here, we observed that exogenous CH₄ not only rapidly promoted cGMP synthesis through increasing the activity of guanosine cyclase (GC), but also induced cucumber AR development. These responses were obviously impaired by the removal of endogenous cGMP with two GC inhibitors. Anatomical evidence showed that the emerged stage (V) among AR primordia development might be the main target of CH₄-cGMP module. Genetic evidence revealed that the transgenic Arabidopsis that overexpressed the methyl-coenzyme M reductase gene (MtMCR) from Methanobacterium thermoautotrophicum not only increased-cGMP production, but also resulted in a pronounced AR development compared to wild-type (WT), especially with the addition of CH₄ or the cell-permeable cGMP derivative 8-Br-cGMP. qPCR analysis confirmed that some marker genes associated with cell cycle regulatory and auxin signaling were closely related to the brand-new CH₄-cGMP module in AR development. Overall, our results clearly revealed an important function of cGMP in CH₄ governing AR formation by modulating auxin-dependent pathway and cell cycle regulation.

Androgen-deprivation therapy with leuprolide increases abdominal adiposity without causing cardiac dysfunction in middle-aged male mice: effect of sildenafil

Androgen-deprivation therapy (ADT) is the primary systemic therapy for treating advanced or metastatic prostate cancer (PCa), which has improved survival outcomes in patients with PCa. However, ADT may develop metabolic and cardiovascular adverse events that impact the quality of life and lifespan in PCa survivors. The present study was designed to establish a murine model of ADT with a gonadotropin-releasing hormone (GnRH) agonist leuprolide and to investigate its effects on metabolism and cardiac function. We also examined the potential cardioprotective role of sildenafil (inhibitor of phosphodiesterase 5) under chronic ADT. Middle-aged male C57BL/6J mice received a 12-wk subcutaneous infusion via osmotic minipumps containing either saline or 18 mg/4 wk leuprolide with or without 1.3 mg/4 wk sildenafil cotreatment. Compared with saline controls, leuprolide treatment significantly reduced prostate weight and serum testosterone levels, confirming chemical castration in these mice. The ADT-induced chemical castration was not affected by sildenafil. Leuprolide significantly increased the weight of abdominal fat after 12-wk treatment without a change in total body weight, and sildenafil did not block the proadipogenic effect of leuprolide. No signs of left ventricular systolic and diastolic dysfunction were observed throughout the leuprolide treatment period. Interestingly, leuprolide treatment significantly elevated serum levels of cardiac troponin I (cTn-I), a biomarker of cardiac injury, and sildenafil did not abolish this effect. We conclude that long-term ADT with leuprolide increases abdominal adiposity and cardiac injury biomarker without cardiac contractile dysfunction. Sildenafil did not prevent ADT-associated adverse changes.

The Effects of Different Doses of Sildenafil on Coronary Blood Flow and Oxidative Stress in Isolated Rat Hearts

The dose-response relationship of sildenafil effects on cardiac function is not completely elucidated. The aim of this study was to assess the effects of different doses of sildenafil on coronary flow and oxidative stress in isolated rat hearts. Coronary flow and markers of oxidative stress, including nitrite outflow, and superoxide anion production in coronary effluent, were determined for isolated rat hearts. The experiments were performed during control conditions and in the presence of sildenafil (10, 20, 50, 200 nM) alone or with Nω-nitro-L-arginine monomethyl ester (L-NAME) (30 μM). Sildenafil was shown to result in a significant increase in coronary flow at lower coronary perfusion pressure (CPP) values at all administered doses, whereas, with an increase in CPP, a reduction in coronary flow was observed. An increase in nitric oxide (NO) was most pronounced in the group treated with the lowest dose of sildenafil at the highest CPP value. After the inhibition of the NO-cyclic guanosine monophosphate (cGMP) signaling (NOS) system by L-NAME, only a dose of 200 nM sildenafil was high enough to overcome the inhibition and to boost release of O2-. That effect was CPP-dependent, with statistical significance reached at 80, 100 and 120 mmHg. Our findings indicate that sildenafil causes changes in heart vasculature in a dose-dependent manner, with a shift from a vasodilatation effect to vasoconstriction with a pressure increase. The highest dose administered is capable of producing superoxide anion radicals in terms of NOS system inhibition.