Guanylate Cyclase Research Articles

Mechanisms of GTN-induced migraine: Role of NOS isoforms, sGC and peroxynitrite in a migraine relevant mouse model.

Migraine research has highlighted the pivotal role of nitric oxide (NO) in migraine pathophysiology. Nitric oxide donors such as glyceryl trinitrate (GTN) induce migraine attacks in humans, whereas spontaneous migraine attacks can be aborted by inhibiting NO production. The present study aimed to investigate how GTN triggers migraine through its three nitric oxide synthase (NOS) isoforms (neuronal NOS (nNOS), endothelial NOS (eNOS) and inducible NOS (iNOS)) via a suspected feed-forward phenomenon. Migraine-relevant hypersensitivity was induced by repeated injection of GTN in an in vivo mouse model. Cutaneous tactile sensitivity was assessed using von Frey filaments. Signaling pathways involved in this model were dissected using non-selective and selective NOS inhibitors, knockout mice lacking eNOS or nNOS and their wild-type control mice. Also, we tested a soluble guanylate cyclase inhibitor and a peroxynitrite decomposition catalyst (Ntotal = 312). Non-selective NOS inhibition blocked GTN-induced hypersensitivity. This response was partially associated with iNOS, and potentially nNOS and eNOS conjointly. Furthermore, we found that the GTN response was largely dependent on the generation of peroxynitrite and partly soluble guanylate cyclase. Migraine-relevant hypersensitivity induced by GTN is mediated by a possible feed-forward phenomenon of NO driven mainly by iNOS but with contributions from other isoforms. The involvement of peroxynitrite adds to the notion that oxidative stress reactions are also involved.

Soluble Guanylate Cyclase α1 Gene Influences Egg-Laying Amount and Hatching Rate in Bombyx mori.

Soluble guanylate cyclase (sGC) serves as a receptor of nitric oxide (NO) and is the core metalloenzyme in the NO signal transduction pathway. sGC plays a key role in the NO-cGMP signal transduction pathway and participates in various physiological processes, including cell differentiation, neuron transmission, and internal environment homeostasis. sGC consists of two subunits, α and β, each subunit containing multiple isoforms. In this study, we cloned and analyzed the sGC-α1 gene in the silkworm Bombyx mori (BmsGC-α1). The BmsGC-α1 gene was expressed highest at the pupal stages. The highest BmsGC-α1 mRNA expression was observed in the head of fifth instar larvae and in fat body during the wandering stage of B. mori. Furthermore, we observed that feeding fifth instar larvae with thyroid hormone and nitroglycerin induced the expression of the BmsGC-α1 gene. Injection of BmsGC-α1 siRNA into silkworms at the prepupal stage resulted in a significant decrease in BmsGC-α1 expression levels at 48 and 72 h postinjection. After silencing BmsGC-α1, both the egg-laying amount and hatching rate of silkworm eggs were significantly reduced compared to the control group. These results suggest that BmsGC-α1 plays an important role in regulating the reproductive system of silkworms. This finding enhances our understanding of the functional diversity of sGC in insects.

Inhibition of P-Glycoprotein Asymmetrically Alters the In Vivo Exposure Profile of SGC003F: A Novel Guanylate Cyclase Stimulator.

As a novel guanylate cyclase stimulator, SGC003F is being developed for the treatment of heart failure with a reduced ejection fraction (HFrEF). This study aimed to assess the effect of P-glycoprotein (P-gp) inhibition on SGC003F exposure in vivo, comparing plasma and tissue levels, and evaluating the role of P-gp in the small intestine, blood-brain barrier (BBB), and kidney in impacting the tissue exposure. Tariquidar, a P-gp inhibitor, was added to monolayer transport assays to observe the changes in the transmembrane characteristics of SGC003F. Rats were given SGC003F with tariquidar via various routes to measure plasma, tissue, urine, and fecal concentrations. The inclusion of tariquidar significantly altered the pharmacokinetics of SGC003F. In LLC-PK1-MDR1 cells, tariquidar reduced the efflux ratio of SGC003F from 6.56 to 1.28. In rats, it enhanced the plasma AUC by 3.05 or 1.61 times, increased the Cmax by 2.13 or 1.07 times, and notably improved bioavailability from 46.4% to 95%. Additionally, co-administration with tariquidar led to a decrease in fecal excretion and an increase in tissue exposure, with only a moderate effect on the partition ratios in the small intestine and brain. P-gp inhibition impacts SGC003F exposure, with plasma levels not fully reflecting tissue levels. P-gp in the small intestine and BBB affects SGC003F's pharmacokinetics, warranting further clinical drug-drug interaction (DDI) studies.

Supramolecular complexes of GCAP1: implications for inherited retinal dystrophies

Guanylate Cyclase Activating Protein 1 (GCAP1) is a calcium sensor that regulates the enzymatic activity of retinal Guanylate Cyclase 1 (GC1) in photoreceptors in a Ca2+/Mg2+ dependent manner. While point mutations in GCAP1 have been associated with inherited retinal dystrophies (IRDs), their impact on protein dimerization or on the possible interaction with the potent GC1 inhibitor RD3 (retinal degeneration protein 3) has never been investigated. Here, we integrate exhaustive in silico investigations with biochemical assays to evaluate the effects of the p.(E111V) substitution, associated with a severe form of IRD, on GCAP1 homo- and hetero-dimerization, and demonstrate that wild type (WT) GCAP1 directly interacts with RD3. Although inducing constitutive activation in GC1, the E111V substitution only slightly affects the dimerization of GCAP1. Both WT- and E111V-GCAP1 are predominantly monomeric in the absence of the GC1 target, however E111V-GCAP1 shows a stronger tendency to be monomeric in the Ca2+-bound form, corresponding to GC1 inhibiting state. Reconstitution experiments performed in the co-presence of WT-GCAP1, E111V-GCAP1 and RD3 restored nearly physiological regulation of the GC1 enzymatic activity in terms of cGMP synthesis and Ca2+-sensitivity, suggesting new scenarios for biologics-mediated treatment of GCAP1-associated IRDs.

Allosteric Communication of the Dimerization and the Catalytic Domain in Photoreceptor Guanylate Cyclase.

Phototransduction in vertebrate photoreceptor cells is controlled by Ca2+-dependent feedback loops involving the membrane-bound guanylate cyclase GC-E that synthesizes the second messenger guanosine-3',5'-cyclic monophosphate. Intracellular Ca2+-sensor proteins named guanylate cyclase-activating proteins (GCAPs) regulate the activity of GC-E by switching from a Ca2+-bound inhibiting state to a Ca2+-free/Mg2+-bound activating state. The gene GUCY2D encodes for human GC-E, and mutations in GUCY2D are often associated with an imbalance of Ca2+ and cGMP homeostasis causing retinal disorders. Here, we investigate the Ca2+-dependent inhibition of the constitutively active GC-E mutant V902L. The inhibition is not mediated by GCAP variants but by Ca2+ replacing Mg2+ in the catalytic center. Distant from the cyclase catalytic domain is an α-helical domain containing a highly conserved helix-turn-helix motif. Mutating the critical amino acid position 804 from leucine to proline left the principal activation mechanism intact but resulted in a lower level of catalytic efficiency. Our experimental analysis of amino acid positions in two distant GC-E domains implied an allosteric communication pathway connecting the α-helical and the cyclase catalytic domains. A computational connectivity analysis unveiled critical differences between wildtype GC-E and the mutant V902L in the allosteric network of critical amino acid positions.

Molsidomine provides neuroprotection against vincristine-induced peripheral neurotoxicity through soluble guanylyl cyclase activation

Peripheral neurotoxicity is a dose-limiting adverse reaction of primary frontline chemotherapeutic agents, including vincristine. Neuropathy can be so disabling that patients drop out of potentially curative therapy, negatively impacting cancer prognosis. The hallmark of vincristine neurotoxicity is axonopathy, yet its underpinning mechanisms remain uncertain. We developed a comprehensive drug discovery platform to identify neuroprotective agents against vincristine-induced neurotoxicity. Among the hits identified, SIN-1—an active metabolite of molsidomine—prevents vincristine-induced axonopathy in both motor and sensory neurons without compromising vincristine anticancer efficacy. Mechanistically, we found that SIN-1’s neuroprotective effect is mediated by activating soluble guanylyl cyclase. We modeled vincristine-induced peripheral neurotoxicity in rats to determine molsidomine therapeutic potential in vivo. Vincristine administration induced severe nerve damage and mechanical hypersensitivity that were attenuated by concomitant treatment with molsidomine. This study provides evidence of the neuroprotective properties of molsidomine and warrants further investigations of this drug as a therapy for vincristine-induced peripheral neurotoxicity.

Phosphodiesterase-5 Expression in Buccal Mucosa of Patients with Erectile Dysfunction One Year after Radical Prostatectomy.

(1) Background: Radical prostatectomy has a high incidence of erectile dysfunction (ED). The aim was to determine if the expression of the nitric oxide synthase-3/soluble guanylate cyclase/phosphodiesterase 5 axis could be detected in buccal mucosa and if it could be differently expressed in patients with and without ED; (2) Methods: Erectile function from 38 subjects subjected to prostatectomy was evaluated using the International Index of Erectile Function-Erectile Function Domain before and one year after surgery. Nitric oxide synthase (NOS3), β1-subunit of soluble guanylate cyclase (sGC), phosphodiesterase-5 (PDE-5) expressions, and interleukin-6 and interleukin-10 content were measured in the buccal mucosa. PDE5A rs3806808 gene polymorphism was genotyped; (3) Results: One year after prostatectomy, 15 patients had recovered functional erection, and 23 showed ED. NOS3, β1-sGC, interleukin-6, and interleukin-10 expressions were not different between patients with and without ED after radical prostatectomy. Buccal mucosa levels of PDE-5 were higher in patients with ED compared to those who recovered erectile functionality. There were no differences found in the genotype of PDE5A polymorphism; (4) Conclusions: One year after prostatectomy, patients with ED had higher PDE5 levels in their buccal mucosa than patients who had recovered erectile function. Rs3806808 PDE5A gene polymorphism was not associated with increased PDE5 expression in buccal mucosa.

Salidroside enhances NO bioavailability and modulates arginine metabolism to alleviate pulmonary arterial hypertension

BackgroundSalidroside (SAL), derived from Rhodiola, shows protective effects in pulmonary arterial hypertension (PAH) models, but its mechanisms are not fully elucidated.ObjectivesInvestigate the therapeutic effects and the mechanism of SAL on PAH.MethodsMonocrotaline was used to establish a PAH rat model. SAL’s impact on oxidative stress and inflammatory responses in lung tissues was analyzed using immunohistochemistry, ELISA, and Western blot. Untargeted metabolomics explored SAL’s metabolic regulatory mechanisms.ResultsSAL significantly reduced mean pulmonary artery pressure, right ventricular hypertrophy, collagen deposition, and fibrosis in the PAH rats. It enhanced antioxidant enzyme levels, reduced inflammatory cytokines, and improved NO bioavailability by upregulating endothelial nitric oxide synthase (eNOS), soluble guanylate cyclase (sGC), cyclic guanosine monophosphate (cGMP), and protein kinase G (PKG) and decreases the expression of endothelin-1 (ET-1). Metabolomics indicated SAL restored metabolic balance in PAH rats, particularly in arginine metabolism.ConclusionsSAL alleviates PAH by modulating arginine metabolism, enhancing NO synthesis, and improving pulmonary vascular remodeling.

Basal release and relaxation responses to 6-nitrodopamine in swine carotid, coronary, femoral, and renal arteries

Mammalian and reptilian vascular tissues present basal release of 6-nitrodopamine, which is reduced when the tissues are pre-incubated with the NO synthase inhibitor L-NG-Nitro arginine methyl ester (L-NAME), or when the endothelium is mechanically removed. 6-Nitrodopamine induces vasorelaxation in pre-contracted vascular rings by antagonizing the dopaminergic D2-like receptor. Here it was investigated whether male swine vessels (including carotid, left descendent coronary, renal, and femoral arteries) release 6-nitrodopamine, dopamine, noradrenaline, and adrenaline, as measured by liquid chromatography coupled to tandem mass spectrometry. The in vitro vasorelaxant action of 6-nitrodopamine was evaluated in carotid, coronary, renal, and femoral arteries precontracted by U-46619 (3 nM), and compared to that induced by the dopamine D2-receptor antagonist L-741,626. Expression of tyrosine hydroxylase and the neuromaker calretinin was investigated by immunohistochemistry. All vascular tissues presented basal release of endothelium-derived catecholamines. The relaxation induced by 6-nitrodopamine was not affected by preincubation of the tissues with either L-NAME (100 μM, 30-min preincubation) or the heme-site inhibitor of soluble guanylyl cyclase ODQ (100 μM, 30-min preincubation). Electrical field stimulation (EFS)-induced contractions were significantly potentiated by previous incubation with L-NAME, but unaffected by ODQ preincubation. The contractions induced by EFS were reduced by preincubation with either 6-nitrodopamine or L-741,626. Immunohistochemistry in all arteries revealed the presence of tyrosine hydroxylase in the endothelium, whereas immunoreactivity for calretinin was negative. Swine vessels present basal release of endothelium-derived catecholamines and expression of tyrosine hydroxylase in the endothelium. The vasodilation induced by 6-nitrodopamine is due to blockade of dopaminergic D2-like receptors.

Effectiveness of Vericiguat on right ventricle to pulmonary artery uncoupling associated with heart failure with reduced ejection fraction

BackgroundsA soluble guanylyl cyclase stimulator vericiguat has been shown to reduce cardiovascular mortality or hospitalization for heart failure in patients with worsening heart failure in the VICTORIA study. However, little is known about the effects of vericiguat on biventricular structure and function. Methods and resultsA retrospective analysis of 63 consecutive patients with heart failure with reduced ejection fraction (HFrEF) who were treated with vericiguat was performed. Clinical data and echocardiographic parameters were compared between baseline and follow-up after the initiation of vericiguat. The median follow-up duration was 266 days. Treatment with vericiguat significantly reduced the plasma BNP levels (log-transformed) compared to baseline (2.46 ± 0.51 vs. 2.14 ± 0.58, p < 0.0001). Left ventricular end-diastolic volume index and left ventricular end-systolic volume index were significantly reduced (LVEDVI, 113.5 ± 46.3 vs. 103.6 ± 51.0, p = 0.0056; LVESVI, 82.0 ± 41.9 vs. 72.8 ± 44.7, p = 0.0077; respectively). The tricuspid annular plane systolic excursion to pulmonary artery systolic pressure (TAPSE/PASP) ratio, an indicator of right ventricle-pulmonary artery (RV-PA) coupling, increased significantly after the treatment (0.56 ± 0.29 vs. 0.92 ± 1.09, p < 0.0001). Univariate and multivariate analyses showed that the treatment effects of vericiguat on BNP levels, LV reverse remodeling, and RV-PA coupling were not correlated with the achievement of the quadruple therapy with beta-blockers, renin-angiotensin system inhibitors, mineralocorticoid inhibitors, and sodium-glucose cotransporter-2 inhibitors, nor with worsening heart failure (WHF). ConclusionTreatment with vericiguat improved adverse LV remodeling and RV-PA uncoupling in HFrEF patients. These effects were independent of WHF and achieving the quadruple therapy. Patients with HFrEF may benefit from early initiation of vericiguat to prevent biventricular adverse remodeling.

A photothermal responsive system accelerating nitric oxide release to enhance bone repair by promoting osteogenesis and angiogenesis

Managing bone defects remains a formidable clinical hurdle, primarily attributed to the inadequate orchestration of vascular reconstruction and osteogenic differentiation in both spatial and temporal dimensions. This challenge persists due to the constrained availability of autogenous grafts and the limited regenerative capacity of allogeneic or synthetic bone substitutes, thus necessitating continual exploration and innovation in the realm of functional and bioactive bone graft materials. While synthetic scaffolds have emerged as promising carriers for bone grafts, their efficacy is curtailed by deficiencies in vascularization and osteoinductive potential. Nitric oxide (NO) plays a key role in revascularization and bone tissue regeneration, yet studies related to the use of NO for the treatment of bone defects remain scarce. Herein, we present a pioneering approach leveraging a photothermal-responsive system to augment NO release. This system comprises macromolecular mPEG-P nanoparticles encapsulating indocyanine green (ICG) (NO-NPs@ICG) and a mPEG-PA-PP injectable thermosensitive hydrogel carrier. By harnessing the synergistic photothermal effects of near-infrared radiation and ICG, the system achieves sustained NO release, thereby activating the soluble guanylate cyclase (SGC)-cyclic guanosine monophosphate (cGMP) signaling pathway both in vitro and in vivo. This orchestrated cascade culminates in the facilitation of angiogenesis and osteogenesis, thus expediting the reparative processes in bone defects. In a nutshell, the NO release-responsive system elucidated in this study presents a pioneering avenue for refining the bone tissue microenvironment and fostering enhanced bone regeneration.

Discovery and Optimization of Hsp110 and sGC Dual-Target Regulators for the Treatment of Pulmonary Arterial Hypertension.

Currently, bifunctional agents with vasodilation and ameliorated vascular remodeling effects provide more advantages for the treatment of pulmonary arterial hypertension (PAH). In this study, we first screened the hit 1 with heat shock protein 110 (Hsp110) inhibition effect from our in-house compound library with soluble guanylate cyclase (sGC) activity. Subsequently, a series of novel bisamide derivatives were designed and synthesized as Hsp110/sGC dual-target regulators based on hit 1. Among them, 17i exhibited optimal Hsp110 and sGC molecular activities as well as remarkable cell malignant phenotypes inhibitory and vasodilatory effects in vitro. Moreover, compared to riociguat, 17i showed superior efficacy in attenuating pulmonary vascular remodeling and right ventricular hypertrophy via Hsp110 suppression in hypoxia-induced PAH rat models (i.g.). Notably, our study successfully demonstrated that the simultaneous regulation of Hsp110 and sGC dual targets was a novel and feasible strategy for PAH therapy, providing a promising lead compound for anti-PAH drug discovery.

Vasorelaxant mechanisms of the antidiabetic anagliptin in rabbit aorta: roles of Kv channels and SERCA pump.

The present study investigated the vasorelaxant mechanisms of an oral antidiabetic drug, anagliptin, using phenylephrine (Phe)-induced pre-contracted rabbit aortic rings. Arterial tone measurement was performed in rabbit thoracic aortic rings. Anagliptin induced vasorelaxation in a dose-dependent manner. Pre-treatment with the classical voltagedependent K+ (Kv) channel inhibitors 4-aminopyridine and tetraethylammonium significantly decreased the vasorelaxant effect of anagliptin, whereas pre-treatment with the inwardly rectifying K+ (Kir) channel inhibitor Ba2+, the ATP-sensitive K+ (KATP) channel inhibitor glibenclamide, and the large-conductance Ca2+-activated K+ (BKCa) channel inhibitor paxilline did not attenuate the vasorelaxant effect. Furthermore, the vasorelaxant response of anagliptin was effectively inhibited by pre-treatment with the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) pump inhibitors thapsigargin and cyclopiazonic acid. Neither cAMP/protein kinase A (PKA)-related signaling pathway inhibitors (adenylyl cyclase inhibitor SQ 22536 and PKA inhibitor KT 5720) nor cGMP/protein kinase G (PKG)-related signaling pathway inhibitors (guanylyl cyclase inhibitor ODQ and PKG inhibitor KT 5823) reduced the vasorelaxant effect of anagliptin. Similarly, the anagliptin-induced vasorelaxation was independent of the endothelium. Based on these results, we suggest that anagliptin-induced vasorelaxation in rabbit aortic smooth muscle occurs by activating Kv channels and the SERCA pump, independent of other vascular K+ channels, cAMP/PKA- or cGMP/PKG-related signaling pathways, and the endothelium.

Podocyte cell-specific Npr1 is required for blood pressure and renal homeostasis in male and female mice: role of sex-specific differences.

Atrial and brain natriuretic peptides (ANP and BNP) bind to guanylyl cyclase A/natriuretic peptide receptor A (GC-A/NPRA), stimulating natriuresis and diuresis and reducing blood pressure (BP), but the role of ANP/NPRA signaling in podocytes (highly specialized epithelial cells covering the outer surfaces of renal glomerular capillaries) remains unclear. This study aimed to determine the effect of conditional deletion of podocyte-specific Npr1 (encoding NPRA) gene knockout (KO) in male and female mice. Tamoxifen-treated wild-type control (PD Npr1 f/f; WT), heterozygous (PD-Cre-Npr1 f/+; HT), and KO (PD-Cre-Npr1 f/-) mice were fed a normal-, low-, or high-salt diet for 4 wk. Podocytes isolated from HT and KO male and female mice showed complete absence of Npr1 mRNA and NPRA protein compared with WT mice. BP, plasma creatinine, plasma sodium, urinary protein, and albumin/creatinine ratio were significantly increased, whereas plasma total protein, albumin, creatinine clearance, and urinary sodium levels were significantly reduced in the HT and KO male and female mice compared with WT mice. These changes were significantly greater in males than in females. On a normal-salt diet, glomerular filtration rate was significantly decreased in PD Npr1 HT and KO male and female mice compared with WT mice. Immunofluorescence of podocin and synaptopodin was also significantly reduced in HT and KO mice compared with WT mice. These observations suggest that in podocytes, ANP/NPRA signaling may be crucial in the maintenance and regulation of glomerular filtration and BP and serve as a biomarker of renal function in a sex-dependent manner.NEW & NOTEWORTHY Our results demonstrate that the podocyte-specific deletion of Npr1 showed increased blood pressure (BP) and altered biomarkers of renal functions, with greater magnitudes in animals fed a high-salt diet in a sex-dependent manner. The results suggest a direct and sex-dependent effect of Npr1 ablation in podocytes on the regulation of BP and renal function and reveal that podocytes may be considered an important target for the ANP-BNP/NPRA/cGMP signaling cascade.

Investigation of electrochemical behaviour and determination of Riociguat with bare GCE and molecularly imprinted polymer-based electrochemical sensor

Pulmonary Arterial Hypertension (PAH) causes death due to ventricular overload and heart failure. Calcium channel blockers, anticoagulants, digoxin and diuretics are the standards of care for PAH. Riociguat (RIO) is an oral soluble guanylate cyclase stimulator approved for the treatment of PAH by World Health Organization (WHO) Group 1 patients. In this study, the electrochemical behavior of RIO was investigated using a bare glassy carbon electrode (GCE). In addition, RIO was determined using GCE and a molecularly imprinted polymer (MIP)-based electrochemical sensor. The MIP-based electrochemical sensor was prepared by photopolymerization of methacrylic acid in the presence of a basic monomer, crosslinker, target molecule, and photoinitiator. The polymer film was characterised by a scanning electron microscope (SEM) and cyclic voltammetry (CV). Under the optimized conditions, the results obtained with GCE and MIP sensor were compared. The analytical performance of GCE and MIP-based electrochemical sensors was evaluated. The linear ranges of RIO were 1.0 × 10–6 – 1.0 × 10–4 M and 1.0 × 10–13 – 1.0 × 10–12 M, with a limit of detection (LOD) of 1.40 × 10–8 M and 2.12 × 10–14 by bare GCE and MIP-based electrochemical sensor using differential pulse voltammetry (DPV), respectively. The results show that the MIP sensor has higher sensitivity than the bare GCE. Both were applied to commercial human serum samples and pharmaceutical dosage forms. The recovery studies were performed, and the recovery% and RSD% results are within the acceptable range. Therefore, the GCE and MIP sensors have good selectivity, accuracy and precision.

Neuroprotective Potential of a Novel Soluble Guanylate Cyclase Stimulator the Riociguat Alone or in a Combination Manner with Resveratrol in Experimental Stroke Model in Rats

Neuroprotective Potential of a Novel Soluble Guanylate Cyclase Stimulator the Riociguat Alone or in a Combination Manner with Resveratrol in Experimental Stroke Model in Rats

New and Emerging Therapeutic Drugs for the Treatment of Pulmonary Arterial Hypertension: A Systematic Review.

Pulmonary arterial hypertension (PAH) is a serious, progressive, and potentially fatal lung disease characterized by a gradual increase in mean pulmonary arterial pressure to over 20 mmHg at rest. The pathogenesis of PAH is multifactorial. It involves dynamic obstruction of the pulmonary vasculature through vasoconstriction, structural obstruction due to adverse vascular remodeling, and pathological obstruction caused by vascular fibrosis and stiffening, which reduces compliance. PAH often presents with vague initial symptoms and is frequently diagnosed at an advanced stage. The increased pulmonary arterial pressure leads to vascular remodeling, eventually resulting in right ventricular hypertrophy and failure. PAH is a rare condition with a median life expectancy of three years, underscoring the need for effective treatment alternatives. Several FDA-approved therapeutic options are available, including prostacyclin analogs (epoprostenol, iloprost, and treprostinil), the non-prostanoid IP receptor agonist selexipag, selective endothelin receptor antagonists (ERA) (ambrisentan, bosentan, and macitentan), phosphodiesterase 5 inhibitors (sildenafil and tadalafil), and the soluble guanylate cyclase (sGC) stimulator riociguat. Despite these advancements, current medications do not provide a permanent cure. This study presents an overview of current and emerging PAH therapies through a systematic literature review. It involved an analysis of nine studies and a review of 800 papers from reputable journals published between 2013 and June 2023. The research focused on drug effects on the six-minute walk distance (6-MWD) and associated side effects in randomized controlled trials. The review found that while udenafil, imatinib, racecadotril, sotatercept, anastrozole, riociguat, tacrolimus, and ralinepag were evaluated, imatinib was notably associated with adverse side effects. Conversely, udenafil, racecadotril, sotatercept, anastrozole, riociguat, tacrolimus, and ralinepag were found to be safe, well-tolerated, and effective in improving hemodynamic measures and 6-MWDs. This study aims to summarize the developing treatment options currently under clinical trials, highlighting the need for further trials before their application in clinical practice.

Who Can Receive Clinical Benefit from Mid-Term Vericiguat Add-on Therapy Among Patients with Systolic Heart Failure Receiving Quadruple Medical Therapy?

Vericiguat, a soluble guanylate cyclase stimulator known for augmenting cyclic guanosine monophosphate production, has garnered substantial clinical attention in patients with systolic heart failure. Despite its proven efficacy, discerning the specific subset of individuals who can enjoy clinical advantages from vericiguat therapy in contemporary real-world clinical practice, particularly among the individuals undergoing "quadruple medical therapy" comprising administration of a beta-blocker, angiotensin receptor neprilysin inhibitor, mineralocorticoid receptor antagonist, and sodium-glucose co-transporter 2 inhibitor, remains an unresolved query. This study involved patients undergoing 3-month vericiguat therapy alongside complete quadruple medical therapy in a contemporary real-world clinical practice. Baseline characteristics associated with the primary outcome, defined as a reduction in serum NT pro-B-type natriuretic peptide (BNP) levels over the 3-month therapeutic duration, were scrutinized. A cohort of 24 patients (median age: 66 years; 20 males) were included. All participants diligently adhered to the 3-month vericiguat therapy in conjunction with the quadruple medical regimen. A higher baseline systolic blood pressure emerged as an independent factor linked to the primary outcome, yielding an adjusted odds ratio of 1.31 (95% confidence interval: 1.03-1.65, P = 0.026) at a threshold of 105 mmHg. This threshold notably stratified the trajectories of serum NT pro-BNP levels during the 3-month vericiguat therapy. In conclusion, preservation of baseline systolic blood pressure emerged as a pivotal determinant for reaping the clinical benefits from mid-term vericiguat therapy among patients with systolic heart failure receiving quadruple medical therapy.

The Promoter Polymorphism rs3918226 of the Endothelial Nitric Oxide Synthase Gene as a Novel Susceptibility Marker for Peripheral Artery Disease

This pilot study aimed to investigate the association between the single nucleotide polymorphism (SNP) rs3918226 in the promoter of the nitric oxide synthase (NOS3) gene and the risk of peripheral artery disease (PAD). DNA samples from 1,263 unrelated subjects of Slavic origin, including 620 patients with PAD and 643 controls, were genotyped for the SNP rs3918226 using the MassArray-4 system. The rs3918226 polymorphism was found to be strongly associated with an increased risk of PAD regardless of coronary artery disease, hypertension, or cigarette smoking (odds ratio [OR]=2.86; 95% confidence interval [CI] 1.89-4.32; Pperm < 0.0001). The SNP-PAD association was almost 3 times stronger in females (OR=8.31; 95% CI 3.07-22.48) than in males (OR=1.79; 95% CI 1.10-2.93). SNP rs3918226 was correlated with ankle-brachial index and total plasma cholesterol in patients with PAD (Рperm < 0.05). The NOS3 polymorphism was closely associated with SNPs rs7692387 and rs13139571 in guanylate cyclase soluble subunit alpha-3 (GUCY1A3) to determine the risk of PAD, suggesting that the rs3918226 polymorphism may disrupt signaling in the NO-soluble guanylyl cyclase pathway. Diplotypes with wild-type alleles, such as NOS3 rs3918226-C/C×GUCY1A1 rs7692387G/G and NOS3 rs3918226-C/C×GUCY1A1 rs13139571C/C, showed strong protection against disease risk (false discovery rate ≤ 0.001). Functional SNP annotation revealed that the allele rs3918226-T was associated with decreased expression of NOS3, most strongly in the tibial arteries than in the coronary artery or aorta. The present study is the first to show that the rs3918226 polymorphism of NOS3 is a novel susceptibility marker for PAD. Further research in independent populations is necessary to reproduce the association between polymorphism rs3918226 and disease risk.

Vericiguat in heart failure with reduced ejection fraction: hope or solid reality?

In recent years, thanks to the advent of new classes of drugs (ARNI and SGLT2-i), the prognosis of patients suffering from heart failure with reduced ejection fraction (HFrEF) has gradually improved. Nonetheless, there is a residual risk that is not targeted by these therapies. Currently, it is recognized that vericiguat, an oral stimulator of soluble guanylate cyclase (sGC), can restore the NO-sGC-cGMP pathway, through stimulation and activation of sGC, aiming to increase cGMP levels with a reduction in heart failure-related oxidative stress and endothelial dysfunction. Even though the Victoria trial demonstrated that HFrEF patients in treatment with vericiguat showed a 10% reduction in the composite of cardiovascular mortality and rehospitalization for heart failure, statistically significantly reducing heart failure hospitalization, the international guidelines limit its use as a second-line drug for patients with worsening symptomatology despite optimized medical therapy. Furthermore, vericiguat has proved to be a valid therapeutic ally especially in those patients with comorbidities such that they cannot receive the classic four-pillar therapy of HF (in particular renal failure). In this review, the authors report on randomized clinical trials, substudies, and meta-analysis about vericiguat in HFrEF, emphasizing the strengths that would suggest the possible role of vericiguat as the fifth pillar of the HFrEF treatment, acknowledging that there are still gaps in the evidence that need to be clarified.