NO-independent stimulators and activators of soluble guanylate cyclase: discovery and therapeutic potential

Novel drug design and repurposing: An opportunity to improve translational research in cardiovascular diseases?

Drug repurposing is defined as the use of approved therapeutic drugs for indications different from those for which they were originally designed. Repositioning diminishes both the time and cost for drug development by omitting the discovery stage, the analysis of absorption, distribution, metabolism, and excretion routes, as well as the studies of the biochemical and physiological effects of a new compound. Besides, drug repurposing takes advantage of the increased bioinformatics knowledge and availability of big data biology. There are many examples of drugs with repurposed indications evaluated in in vitro studies, and in pharmacological, preclinical, or retrospective clinical analyses. Here, we briefly review some of the experimental strategies and technical advances that may improve translational research in cardiovascular diseases. We also describe exhaustive research from basic science to clinical studies that culminated in the final approval of new drugs and provide examples of successful drug repurposing in the field of cardiology.

Vericiguat attenuates doxorubicin-induced cardiotoxicity through the PRKG1/PINK1/STING axis

Doxorubicin (DOX) is restricted due to its severe cardiotoxicity. There is still a lack of viable and effective drugs to prevent or treat DOX-induced cardiotoxicity(DIC). Vericiguat is widely used to treat heart failure with reduced ejection fraction. However, it is not clear whether vericiguat can improve DIC. In the present study, we constructed a DIC model using mice and neonatal rat cardiomyocytes and found that vericiguat ameliorated DOX-induced cardiac insufficiency in mice, restored DOX-induced mitochondrial dysfunction in neonatal rat cardiomyocytes, and inhibited the expression of inflammatory factors. Further studies showed that vericiguat improved mitochondrial dysfunction and reduced mtDNA leakage into the cytoplasm by up-regulating PRKG1, which activated PINK1 and then inhibited the STING/IRF3 pathway to alleviate DIC. These findings demonstrate for the first time that vericiguat has therapeutic potential for the treatment of DIC.

Modified Zhenwu Decoction improved intestinal barrier function of experimental colitis through activation of sGC-mediated cGMP/PKG signaling

BACKGROUND

The invasion of luminal antigens and an aberrant immune response resulting from a disrupted physical epithelial barrier are the key characteristics of ulcerative colitis (UC). The restoration of damaged epithelial function is crucial for maintaining mucosal homeostasis and disease quiescence. Current therapies for UC primarily focus on suppressing inflammation. However, most patients fail to respond to therapy or develop secondary resistance over time, emphasizing the need to develop novel therapeutic targets for UC. Our study aimed to identify the potential targets of a novel modified herbal formula from the Zhen Wu Decoction, namely CDD-2103, which has demonstrated promising efficacy in treating chronic colitis.

METHODS

The effect of CDD-2103 on epithelial barrier function was examined using in vitro and ex vivo models of tissue injury, as well as a chronic colitis C57BL/6 mouse model. Transcriptomic analysis was employed to profile gene expression changes in colonic tissues following treatment with CDD-2103.

RESULTS

Our in vivo experiments demonstrated that CDD-2103 dose-dependently reduced disease severity in mice with chronic colitis. The efficacy of CDD-2103 was mediated by a reduction in goblet cell loss and the enhancement of tight junction protein integrity. Mechanistically, CDD-2103 suppressed epithelial cell apoptosis and tight junction protein breakdown by activating the soluble guanynyl cyclase (sGC)-mediated cyclic guanosine monophosphate (cGMP)/PKG signaling cascade. Molecular docking analysis revealed strong sGC ligand recognition by the CDD-2103-derived molecules, warranting further investigation.

CONCLUSION

Our study revealed a novel formulation CDD-2103 that restores intestinal barrier function through the activation of sGC-regulated cGMP/PKG signaling. Furthermore, our findings suggest that targeting sGC can be an effective approach for promoting mucosal healing in the management of UC.

S-nitrosylation-triggered unfolded protein response maintains hematopoietic progenitors in Drosophila

The Drosophila lymph gland houses blood progenitors that give rise to myeloid-like blood cells. Initially, blood progenitors proliferate, but later, they become quiescent to maintain multipotency before differentiation. Despite the identification of various factors involved in multipotency maintenance, the cellular mechanism controlling blood progenitor quiescence remains elusive. Here, we identify the expression of nitric oxide synthase in blood progenitors, generating nitric oxide for post-translational S-nitrosylation of protein cysteine residues. S-nitrosylation activates the Ire1-Xbp1-mediated unfolded protein response, leading to G2 cell-cycle arrest. Specifically, we identify the epidermal growth factor receptor as a target of S-nitrosylation, resulting in its retention within the endoplasmic reticulum and blockade of its receptor function. Overall, our findings highlight developmentally programmed S-nitrosylation as a critical mechanism that induces protein quality control in blood progenitors, maintaining their undifferentiated state by inhibiting cell-cycle progression and rendering them unresponsive to paracrine factors.

Identification of new multi-substituted 1H-pyrazolo[3,4-c]pyridin-7(6H)-ones as soluble guanylyl cyclase (sGC) stimulators with vasoprotective and anti-inflammatory activities

Herein, we describe the rational design, synthesis and in vitro functional characterization of new heme-dependent, direct soluble guanylyl cyclase (sGC) agonists. These new compounds bear a 1H-pyrazolo[3,4-c]pyridin-7(6H)-one skeleton, modified to enable efficient sGC binding and stimulation. To gain insights into structure-activity relationships, the N6-alkylation of the skeleton was explored, while a pyrimidine ring, substituted with various C5'-polar groups, was installed at position C3. Among the newly synthesized 1H-pyrazolo[3,4-c]pyridin-7(6H)-ones, derivatives 14b, 15b and 16a display characteristic features of sGC "stimulators" in A7r5 vascular smooth muscle cells in vitro. They strongly synergize with the NO donor, sodium nitroprusside (SNP) in inducing cGMP generation in a manner that requires the presence of a reduced heme moiety associated with sGC, and elevate the cGMP-responsive phosphorylation of the protein VASP at Ser239. In line with their sGC stimulating capacity, docking calculations of derivatives 16a, 15(a-c) on a cryo-EM structure of human sGC (hsGC) in an ΝΟ-activated state indicated the implication of 1H-pyrazolo[3,4-c]pyridin-7(6H)-one skeleton in efficient bonding interactions with the recently identified region that binds known sGC stimulators, while the presence of either a N6-H or N6-methyl group pointed to enhanced binding affinity. Moreover, the in vitro functional effects of our newly identified sGC stimulators were compatible with a beneficial role in vascular homeostasis. Specifically, derivative 14b reduced A7r5 cell proliferation, while 16a dampened the expression of adhesion molecules ICAM-1 and P/E-Selectin in Human Umbilical Vein Endothelial Cells (HUVECs), as well as the subsequent adhesion of U937 leukocytes to the HUVECs, triggered by tumor necrosis factor alpha (TNF-α) or interleukin-1 beta (IL-1β). The fact that these compounds elevate cGMP only in the presence of NO may indicate a novel way of interaction with the enzyme and may make them less prone than other direct sGC agonists to induce characteristic hypotension in vivo.

Per-ARNT-Sim Domains in Nitric Oxide Signaling by Soluble Guanylyl Cyclase

Nitric oxide (NO) regulates large swaths of animal physiology including wound healing, vasodilation, memory formation, odor detection, sexual function, and response to infectious disease. The primary NO receptor is soluble guanyly/guanylate cyclase (sGC), a dimeric protein of ∼150 kDa that detects NO through a ferrous heme, leading to a large change in conformation and enhanced production of cGMP from GTP. In humans, loss of sGC function contributes to multiple disease states, including cardiovascular disease and cancer, and is the target of a new class of drugs, sGC stimulators, now in clinical use. sGC evolved through the fusion of four ancient domains, a heme nitric oxide / oxygen (H-NOX) domain, a Per-ARNT-Sim (PAS) domain, a coiled coil, and a cyclase domain, with catalysis occurring at the interface of the two cyclase domains. In animals, the predominant dimer is the α1β1 heterodimer, with the α1 subunit formed through gene duplication of the β1 subunit. The PAS domain provides an extensive dimer interface that remains unchanged during sGC activation, acting as a core anchor. A large cleft formed at the PAS-PAS dimer interface tightly binds the N-terminal end of the coiled coil, keeping this region intact and unchanged while the rest of the coiled coil repacks, and the other domains reposition. This interface buries ∼3000 Å2 of monomer surface and includes highly conserved apolar and hydrogen bonding residues. Herein, we discuss the evolutionary history of sGC, describe the role of PAS domains in sGC function, and explore the regulatory factors affecting sGC function.

The biological role and future therapeutic uses of nitric oxide in extracorporeal membrane oxygenation, a narrative review

BACKGROUND

Nitric oxide (NO) is a gas naturally produced by the human body that plays an important physiological role. Specifically, it binds guanylyl cyclase to induce smooth muscle relaxation. NO's other protective functions have been well documented, particularly its protective endothelial functions, effects on decreasing pulmonary vascular resistance, antiplatelet, and anticoagulation properties. The use of nitric oxide donors as vasodilators has been known since 1876. Inhaled nitric oxide has been used as a pulmonary vasodilator and to improve ventilation perfusion matching since the 1990s. It is currently approved by the United States Food and Drug Administration for neonates with hypoxic respiratory failure, however, it is used off-label for acute respiratory distress syndrome, acute bronchiolitis, and COVID-19.

PURPOSE

In this article we review the currently understood biological action and therapeutic uses of NO through nitric oxide donors such as inhaled nitric oxide. We will then explore recent studies describing use of NO in cardiopulmonary bypass and extracorporeal membrane oxygenation and speculate on NO's future uses.

Vericiguat protects against cardiac damage in a pig model of ischemia/reperfusion

BACKGROUND

The purpose of this research was to verify that vericiguat, a soluble guanylate cyclase (sGC) stimulator, reduces myocardial ischemic reperfusion injury (MIRI), and to learn how this reduction happens.

METHODS AND RESULTS

To develop an ischaemia/reperfusion (I/R) model, the left anterior descending artery was blocked in minipigs under anesthesia for 90 minutes, followed by 180 minutes of reperfusion. Vericiguat is administered three hours before surgery. Two weeks after receiving therapy, pigs underwent cardiovascular magnetic resonance imaging (MRI) to evaluate the results. The MRI results suggest improvement in the myocardial infarct after vericiguat treatment. Vericiguat treatment for two weeks enhanced vascularity, inhibited pro-inflammatory cells, and decreased collagen deposition in the infarct zone of pigs. Short-term experiments investigating possible explanations have indicated that vericiguat has antiapoptotic effects on cardiomyocytes and increases levels of autophagy.

CONCLUSIONS

Vericiguat, an SGC activator, reduces MIRI in pigs by boosting autophagy, preventing apoptosis, and promoting angiogenesis.

Decoding signaling mechanisms: unraveling the targets of guanylate cyclase agonists in cardiovascular and digestive diseases

Soluble guanylate cyclase agonists and guanylate cyclase C agonists are two popular drugs for diseases of the cardiovascular system and digestive systems. The common denominator in these conditions is the potential therapeutic target of guanylate cyclase. Thanks to in-depth explorations of their underlying signaling mechanisms, the targets of these drugs are becoming clearer. This review explains the recent research progress regarding potential drugs in this class by introducing representative drugs and current findings on them.

Promising Cerebral Blood Flow Enhancers in Acute Ischemic Stroke

Ischemic stroke presents a major global economic and public health burden. Although recent advances in available endovascular therapies show improved functional outcome, a good number of stroke patients are either ineligible or do not have access to these treatments. Also, robust collateral flow during acute ischemic stroke independently predicts the success of endovascular therapies and the outcome of stroke. Hence, adjunctive therapies for cerebral blood flow (CBF) enhancement are urgently needed. A very clear overview of the pial collaterals and the role of genetics are presented in this review. We review available evidence and advancement for potential therapies aimed at improving CBF during acute ischemic stroke. We identified heme-free soluble guanylate cyclase activators; Sanguinate, remote ischemic perconditioning; Fasudil, S1P agonists; and stimulation of the sphenopalatine ganglion as promising potential CBF-enhancing therapeutics requiring further investigation. Additionally, we outline and discuss the critical steps required to advance research strategies for clinically translatable CBF-enhancing agents in the context of acute ischemic stroke models.

Randomized placebo-controlled crossover study to assess tolerability and pharmacodynamics of zagociguat, a soluble guanylyl cyclase stimulator, in healthy elderly

AIMS

Dysfunction of nitric oxide-soluble guanylate cyclase (sGC)-cyclic guanosine monophosphate signalling is implicated in the pathophysiology of cognitive impairment. Zagociguat is a central nervous system (CNS) penetrant sGC stimulator designed to amplify nitric oxide-cyclic guanosine monophosphate signalling in the CNS. This article describes a phase 1b study evaluating the safety and pharmacodynamic effects of zagociguat.

METHODS

In this randomized crossover study, 24 healthy participants aged ≥65 years were planned to receive 15 mg zagociguat or placebo once daily for 2 15-day periods separated by a 27-day washout. Adverse events, vital signs, electrocardiograms and laboratory tests were conducted to assess safety. Pharmacokinetics of zagociguat were evaluated in blood and cerebrospinal fluid (CSF). Pharmacodynamic assessments included evaluation of cerebral blood flow, CNS tests, pharmaco-electroencephalography, passive leg movement and biomarkers in blood, CSF and brain.

RESULTS

Twenty-four participants were enrolled; 12 participants completed both treatment periods, while the other 12 participants completed only 1 treatment period. Zagociguat was well-tolerated and penetrated the blood-brain barrier, with a CSF/free plasma concentration ratio of 0.45 (standard deviation 0.092) measured 5 h after the last dose of zagociguat on Day 15. Zagociguat induced modest decreases in blood pressure. No consistent effects of zagociguat on other pharmacodynamic parameters were detected.

CONCLUSION

Zagociguat was well-tolerated and induced modest blood pressure reductions consistent with other sGC stimulators. No clear pharmacodynamic effects of zagociguat were detected. Studies in participants with proven reduced cerebral blood flow or CNS function may be an avenue for further evaluation of the compound.

Soluble guanylyl cyclase: A novel target for the treatment of vascular cognitive impairment?

Vascular cognitive impairment (VCI) describes neurodegenerative disorders characterized by a vascular component. Pathologically, it involves decreased cerebral blood flow (CBF), white matter lesions, endothelial dysfunction, and blood-brain barrier (BBB) impairments. Molecularly, oxidative stress and inflammation are two of the major underlying mechanisms. Nitric oxide (NO) physiologically stimulates soluble guanylate cyclase (sGC) to induce cGMP production. However, under pathological conditions, NO seems to be at the basis of oxidative stress and inflammation, leading to a decrease in sGC activity and expression. The native form of sGC needs a ferrous heme group bound in order to be sensitive to NO (Fe(II)sGC). Oxidation of sGC leads to the conversion of ferrous to ferric heme (Fe(III)sGC) and even heme-loss (apo-sGC). Both Fe(III)sGC and apo-sGC are insensitive to NO, and the enzyme is therefore inactive. sGC activity can be enhanced either by targeting the NO-sensitive native sGC (Fe(II)sGC), or the inactive, oxidized sGC (Fe(III)sGC) and the heme-free apo-sGC. For this purpose, sGC stimulators acting on Fe(II)sGC and sGC activators acting on Fe(III)sGC/apo-sGC have been developed. These sGC agonists have shown their efficacy in cardiovascular diseases by restoring the physiological and protective functions of the NO-sGC-cGMP pathway, including the reduction of oxidative stress and inflammation, and improvement of vascular functioning. Yet, only very little research has been performed within the cerebrovascular system and VCI pathology when focusing on sGC modulation and its potential protective mechanisms on vascular and neural function. Therefore, within this review, the potential of sGC as a target for treating VCI is highlighted.

Nitric oxide and thiols: Chemical biology, signalling paradigms and vascular therapeutic potential

Nitric oxide (• NO) interactions with biological thiols play crucial, but incompletely determined, roles in vascular signalling and other biological processes. Here, we highlight two recently proposed signalling paradigms: (1) the formation of a vasodilating labile nitrosyl ferrous haem (NO-ferrohaem) facilitated by thiols via thiyl radical generation and (2) polysulfides/persulfides and their interaction with • NO. We also describe the specific (bio)chemical routes in which • NO and thiols react to form S-nitrosothiols, a broad class of small molecules, and protein post-translational modifications that can influence protein function through catalytic site or allosteric structural changes. S-Nitrosothiol formation depends upon cellular conditions, but critically, an appropriate oxidant for either the thiol (yielding a thiyl radical) or • NO (yielding a nitrosonium [NO+ ]-donating species) is required. We examine the roles of these collective • NO/thiol species in vascular signalling and their cardiovascular therapeutic potential.

Investigation of NO Role in Neural Tissue in Brain and Spinal Cord Injury

Nitric oxide (NO) production in injured and intact brain regions was compared by EPR spectroscopy in a model of brain and spinal cord injury in Wistar rats. The precentral gyrus of the brain was injured, followed by the spinal cord at the level of the first lumbar vertebra. Seven days after brain injury, a reduction in NO content of 84% in injured brain regions and 66% in intact brain regions was found. The difference in NO production in injured and uninjured brain regions persisted 7 days after injury. The copper content in the brain remained unchanged one week after modeling of brain and spinal cord injury. The data obtained in the experiments help to explain the problems in the therapy of patients with combined brain injury.

Ligand Control of Dinitrosyl Iron Complexes for Selective Superoxide-Mediated Nitric Oxide Monooxygenation and Superoxide-Dioxygen Interconversion

Through nitrosylation of [Fe-S] proteins, or the chelatable iron pool, a dinitrosyl iron unit (DNIU) [Fe(NO)2] embedded in the form of low-molecular-weight/protein-bound dinitrosyl iron complexes (DNICs) was discovered as a metallocofactor assembled under inflammatory conditions with elevated levels of nitric oxide (NO) and superoxide (O2-). In an attempt to gain biomimetic insights into the unexplored transformations of the DNIU under inflammation, we investigated the reactivity toward O2- by a series of DNICs [(NO)2Fe(μ-MePyr)2Fe(NO)2] (1) and [(NO)2Fe(μ-SEt)2Fe(NO)2] (3). During the superoxide-induced conversion of DNIC 1 into DNIC [(K-18-crown-6-ether)2(NO2)][Fe(μ-MePyr)4(μ-O)2(Fe(NO)2)4] (2-K-crown) and a [Fe3+(MePyr)x(NO2)y(O)z]n adduct, stoichiometric NO monooxygenation yielding NO2- occurs without the transient formation of peroxynitrite-derived •OH/•NO2 species. To study the isoelectronic reaction of O2(g) and one-electron-reduced DNIC 1, a DNIC featuring an electronically localized {Fe(NO)2}9-{Fe(NO)2}10 electronic structure, [K-18-crown-6-ether][(NO)2Fe(μ-MePyr)2Fe(NO)2] (1-red), was successfully synthesized and characterized. Oxygenation of DNIC 1-red leads to the similar assembly of DNIC 2-K-crown, of which the electronic structure is best described as paramagnetic with weak antiferromagnetic coupling among the four S = 1/2 {FeIII(NO-)2}9 units and S = 5/2 Fe3+ center. In contrast to DNICs 1 and 1-red, DNICs 3 and [K-18-crown-6-ether][(NO)2Fe(μ-SEt)2Fe(NO)2] (3-red) display a reversible equilibrium of "3 + O2- ⇋ 3-red + O2(g)", which is ascribed to the covalent [Fe(μ-SEt)2Fe] core and redox-active [Fe(NO)2] unit. Based on this study, the supporting/bridging ligands in dinuclear DNIC 1/3 (or 1-red/3-red) control the selective monooxygenation of NO and redox interconversion between O2- and O2 during reaction with O2- (or O2).

Vericiguat: The Fifth Harmony of Heart Failure with Reduced Ejection Fraction

Heart failure with reduced ejection fraction is a chronic and progressive syndrome that continues to be a substantial financial burden for health systems in Western countries. Despite remarkable advances in pharmacologic and device-based therapy over the last few years, patients with heart failure with reduced ejection fraction have a high residual risk of adverse outcomes, even when treated with optimal guideline-directed medical therapy and in a clinically stable state. Worsening heart failure episodes represent a critical event in the heart failure trajectory, carrying high residual risk at discharge and dismal short- or long-term prognosis. Recently, vericiguat, a soluble guanylate cyclase stimulator, has been proposed as a novel drug whose use is already associated with a reduction in heart failure-related hospitalizations in patients in guideline-directed medical therapy. In this review, we summarized the pathophysiology of the nitric oxide-soluble guanylate cyclase-cyclic guanosine monophosphate cascade in patients with heart failure with reduced ejection fraction, the pharmacology of vericiguat as well as the evidence regarding their use in patients with HFrEF. Finally, tips and tricks for its use in standard clinical practice are provided.

The sGC Activator Runcaciguat Has Kidney Protective Effects and Prevents a Decline of Kidney Function in ZSF1 Rats

Chronic kidney disease (CKD) progression is associated with persisting oxidative stress, which impairs the NO-sGC-cGMP signaling cascade through the formation of oxidized and heme-free apo-sGC that cannot be activated by NO. Runcaciguat (BAY 1101042) is a novel, potent, and selective sGC activator that binds and activates oxidized and heme-free sGC and thereby restores NO-sGC-cGMP signaling under oxidative stress. Therefore, runcaciguat might represent a very effective treatment option for CKD/DKD. The potential kidney-protective effects of runcaciguat were investigated in ZSF1 rats as a model of CKD/DKD, characterized by hypertension, hyperglycemia, obesity, and insulin resistance. ZSF1 rats were treated daily orally for up to 12 weeks with runcaciguat (1, 3, 10 mg/kg/bid) or placebo. The study endpoints were proteinuria, kidney histopathology, plasma, urinary biomarkers of kidney damage, and gene expression profiling to gain information about relevant pathways affected by runcaciguat. Furthermore, oxidative stress was compared in the ZSF1 rat kidney with kidney samples from DKD patients. Within the duration of the 12-week treatment study, kidney function was significantly decreased in obese ZSF1 rats, indicated by a 20-fold increase in proteinuria, compared to lean ZSF1 rats. Runcaciguat dose-dependently and significantly attenuated the development of proteinuria in ZSF1 rats with reduced uPCR at the end of the study by -19%, -54%, and -70% at 1, 3, and 10 mg/kg/bid, respectively, compared to placebo treatment. Additionally, average blood glucose levels measured as HbA1C, triglycerides, and cholesterol were increased by five times, twenty times, and four times, respectively, in obese ZSF1 compared to lean rats. In obese ZSF1 rats, runcaciguat reduced HbA1c levels by -8%, -34%, and -76%, triglycerides by -42%, -55%, and -71%, and cholesterol by -16%, -17%, and -34%, at 1, 3, and 10 mg/kg/bid, respectively, compared to placebo. Concomitantly, runcaciguat also reduced kidney weights, morphological kidney damage, and urinary and plasma biomarkers of kidney damage. Beneficial effects were accompanied by changes in gene expression that indicate reduced fibrosis and inflammation and suggest improved endothelial stabilization. In summary, the sGC activator runcaciguat significantly prevented a decline in kidney function in a DKD rat model that mimics common comorbidities and conditions of oxidative stress of CKD patients. Thus, runcaciguat represents a promising treatment option for CKD patients, which is in line with recent phase 2 clinical study data, where runcaciguat showed promising efficacy in CKD patients (NCT04507061).

Clinical Applications for Gasotransmitters in the Cardiovascular System: Are We There Yet?

Ischemia is the underlying mechanism in a wide variety of acute and persistent pathologies. As such, understanding the fine intracellular events occurring during (and after) the restriction of blood supply is pivotal to improving the outcomes in clinical settings. Among others, gaseous signaling molecules constitutively produced by mammalian cells (gasotransmitters) have been shown to be of potential interest for clinical treatment of ischemia/reperfusion injury. Nitric oxide (NO and its sibling, HNO), hydrogen sulfide (H2S), and carbon monoxide (CO) have long been proven to be cytoprotective in basic science experiments, and they are now awaiting confirmation with clinical trials. The aim of this work is to review the literature and the clinical trials database to address the state of development of potential therapeutic applications for NO, H2S, and CO and the clinical scenarios where they are more promising.

First-in-human trial to assess safety, tolerability, pharmacokinetics, and pharmacodynamics of zagociguat (CY6463), a CNS-penetrant soluble guanylyl cyclase stimulator

Soluble guanylate cyclase (sGC) and its product, cyclic guanosine monophosphate, play a role in learning and memory formation. Zagociguat (CY6463) is a novel stimulator of sGC being developed for the treatment of neurodegenerative disease. Single zagociguat doses of 0.3, 1, 3, 10, 20, 30, and 50 mg were administered once to healthy participants in a single-ascending-dose phase; then zagociguat 2, 5, 10, and 15 mg was administered q.d. for 14 days in a multiple-ascending-dose phase; and, finally, zagociguat 10 mg was administered once in both fed and fasted state in a food-interaction phase. Safety of zagociguat was evaluated by monitoring treatment-emergent adverse events, suicide risk, vital signs, electrocardiography, and laboratory tests. Pharmacokinetics of zagociguat were assessed through blood, urine, and cerebrospinal fluid sampling. Pharmacodynamic effects of zagociguat were evaluated with central nervous system (CNS) tests and pharmaco-electroencephalography. Zagociguat was well-tolerated across all doses evaluated. Zagociguat exposures increased in a dose-proportional manner. Median time to maximum concentration ranged from 0.8 to 5 h and mean terminal half-life from 52.8 to 67.1 h. CNS penetration of the compound was confirmed by cerebrospinal fluid sampling. Zagociguat induced up to 6.1 mmHg reduction in mean systolic and up to 7.5 mmHg reduction in mean diastolic blood pressure. No consistent pharmacodynamic (PD) effects on neurocognitive function were observed. Zagociguat was well-tolerated, CNS-penetrant, and demonstrated PD activity consistent with other sGC stimulators. The results of this study support further development of zagociguat.

A Systematic Review of the Effect of Vericiguat on Patients with Heart Failure

Despite recent advances in heart failure (HF) therapy, the risk of cardiovascular (CV) mortality, morbidity, and HF hospitalization (HFH) are major challenges in HF treatment. We aimed to review the potential of vericiguat as a treatment option for HF. A systematic literature review was performed using the PubMed database and ClinicalTrials.gov. Four randomized controlled trials were identified, which study the safety and efficacy of vericiguat in HF patients. Vericiguat activates soluble guanylate cyclase (sGC) by binding to the beta-subunit, bypassing the requirement for NO-induced activation. The nitric oxide (NO)-sGC-cyclic guanosine monophosphate (cGMP) pathway plays an essential role in cardiovascular (CV) regulation and the protection of healthy cardiac function but is impaired in HF. Vericiguat reduced the risk of CV death and HFH in HF patients with reduced ejection fraction (HFrEF) but showed no therapeutic effect on HF with preserved ejection fraction (HFpEF). The trials demonstrated a favorable safety profile with most common adverse events such as hypotension, syncope, and anemia. Therefore, vericiguat is recommended for patients with HFrEF and a minimum systolic blood pressure of 100 mmHg. Treatment with vericiguat is considered when the individual patient experiences decompensation despite being on guideline-recommended medication, e.g., angiotensin-converting inhibitor/AT1 receptor antagonist, beta-adrenoceptor antagonist, spironolactone, and sodium-glucose transporter 2 inhibitors. Furthermore, larger studies are required to investigate any potential effect of vericiguat in HFpEF patients. Despite the limitations, vericiguat can be recommended for patients with HFrEF, where standard-of-care is insufficient, and the disease worsens.

Endothelial TAZ inhibits capillarization of liver sinusoidal endothelium and damage-induced liver fibrosis via nitric oxide production

Background: Endothelial dysfunction is a systemic disorder and is involved in the pathogenesis of several human diseases. Hemodynamic shear stress plays an important role in vascular homeostasis including nitric oxide (NO) production. Impairment of NO production in endothelial cells stimulates the capillarization of liver sinusoidal endothelial cells, followed by hepatic stellate cell activation, inducing liver fibrosis. However, the detailed mechanism underlying NO production is not well understood. In hepatocytes, transcriptional co-activator with PDZ-binding motif (TAZ) has been reported to be involved in liver fibrosis. However, the role of endothelial TAZ in liver fibrosis has not been investigated. In this study, we uncovered the role TAZ in endothelial cell NO production, and its subsequent effects on liver fibrosis. Methods: TAZ-floxed mice were crossed with Tie2-cre transgenic mice, to generate endothelium-specific TAZ-knockout (eKO) mice. To induce liver damage, a 3,5-diethoxycarboncyl-1,4-dihydrocollidine, methionine-choline-deficient diet, or partial hepatectomy was applied. Liver fibrosis and endothelial dysfunction were analyzed in wild-type and eKO mice after liver damage. In addition, liver sinusoidal endothelial cell (LSEC) was used for in vitro assays of protein and mRNA levels. To study transcriptional regulation, chromatin immunoprecipitation and luciferase reporter assays were performed. Results: In liver of eKO mice, LSEC capillarization was observed, evidenced by loss of fenestrae and decreased LSEC-specific marker gene expression. LSEC capillarization of eKO mouse is caused by downregulation of endothelial nitric oxide synthase expression and subsequent decrease in NO concentration, which is transcriptionally regulated by TAZ-KLF2 binding to Nos3 promoter. Diminished NO concentration by TAZ knockout in endothelium accelerates liver fibrosis induced by liver damages. Conclusions: Endothelial TAZ inhibits damage-induced liver fibrosis via NO production. This highlights an unappreciated role of TAZ in vascular health and liver diseases.

Drug repurposing-a promising approach for patients with angina but non-obstructive coronary artery disease (ANOCA)

In today's era of individualized precision medicine drug repurposing represents a promising approach to offer patients fast access to novel treatments. Apart from drug repurposing in cancer treatments, cardiovascular pharmacology is another attractive field for this approach. Patients with angina pectoris without obstructive coronary artery disease (ANOCA) report refractory angina despite standard medications in up to 40% of cases. Drug repurposing also appears to be an auspicious option for this indication. From a pathophysiological point of view ANOCA patients frequently suffer from vasomotor disorders such as coronary spasm and/or impaired microvascular vasodilatation. Consequently, we carefully screened the literature and identified two potential therapeutic targets: the blockade of the endothelin-1 (ET-1) receptor and the stimulation of soluble guanylate cyclase (sGC). Genetically increased endothelin expression results in elevated levels of ET-1, justifying ET-1 receptor blockers as drug candidates to treat coronary spasm. sGC stimulators may be beneficial as they stimulate the NO-sGC-cGMP pathway leading to GMP-mediated vasodilatation.

Novelties in the pharmacological approaches for chronic heart failure: new drugs and cardiovascular targets

Despite recent advances in chronic heart failure (HF) management, the prognosis of HF patients is poor. This highlights the need for researching new drugs targeting, beyond neurohumoral and hemodynamic modulation approach, such as cardiomyocyte metabolism, myocardial interstitium, intracellular regulation and NO-sGC pathway. In this review we report main novelties on new possible pharmacological targets for HF therapy, mainly on new drugs acting on cardiac metabolism, GCs-cGMP pathway, mitochondrial function and intracellular calcium dysregulation.

Nitric oxide augments signaling for contraction in hypoxic pulmonary arterial smooth muscle—Implications for hypoxic pulmonary hypertension

Introduction: Hypoxic persistent pulmonary hypertension in the newborn (PPHN) is usually treated with oxygen and inhaled nitric oxide (NO), both pulmonary arterial relaxants. But treatment failure with NO occurs in 25% of cases. We previously demonstrated that 72 h exposure to hypoxia, modeling PPHN, sensitized pulmonary artery smooth muscle cells (PASMC) to the contractile agonist thromboxane and inhibited relaxant adenylyl cyclase (AC) activity.

Methods: In this study, we examined the effects of sodium nitroprusside (SNP), as NO donor, on the thromboxane-mediated contraction and NO-independent relaxation pathways and on reactive oxygen species (ROS) accumulation in PASMC. In addition, we examined the effect of the peroxynitrite scavenger 5,10,15,20-Tetrakis (4-sulfonatophenyl)porphyrinato Iron (III) (FeTPPS) on these processes.

Results: Exposure of PASMC to 72 h hypoxia increased total intracellular ROS compared to normoxic control cells and this was mitigated by treatment of cells with either SNP or FeTPPS. Total protein nitrosylation was increased in hypoxic PASMC compared to controls. Both normoxic and hypoxic cells treated with SNP exhibited increased total protein nitrosylation and intracellular nitrite; this was reduced by treatment with FeTPPS. While cell viability and mitochondrial number were unchanged by hypoxia, mitochondrial activity was decreased compared to controls; addition of FeTPPS did not alter this. Basal and maximal mitochondrial metabolism and ATP turnover were reduced in hypoxic PASMC compared to controls. Hypoxic PASMC had higher basal Ca2+, and a heightened peak Ca2+ response to thromboxane challenge compared to controls. Addition of SNP further elevated the peak Ca2+ response, while addition of FeTPPS brought peak Ca2+ response down to control levels. AC mediated relaxation was impaired in hypoxic PASMC compared to controls but was normalized following treatment with FeTPPS. Addition of SNP inhibited adenylyl cyclase activity in both normoxic and hypoxic PASMC. Moreover, addition of the Ca2+ chelator BAPTA improved AC activity, but the effect was minimal.

Discussion: We conclude that NO independently augments contraction and inhibits relaxation pathways in hypoxic PASMC, in part by a mechanism involving nitrogen radical formation and protein nitrosylation. These observations may partially explain impaired effectiveness of NO when treating hypoxic pulmonary hypertension.

Stimulation of soluble guanylate cyclase activity with riociguat promotes angiogenesis and improves neovascularization after limb ischemia

BACKGROUND AND AIMS

The NO-cGMP pathway is essential for angiogenesis, vasculogenesis and post-natal neovascularization. The key enzyme responsible for the synthesis of cGMP following binding of NO is soluble guanylate cyclase (sGC). Riociguat is the first member of a novel class of compounds known as sGC stimulators. We tested the hypothesis that stimulation of sGC with riociguat might improve neovascularization in response to ischemia.

METHODS

In vitro, the angiogenic effect of riociguat was tested in human umbilical vein endothelial cells (HUVECs). In vivo, neovascularization was investigated in a mouse model of limb ischemia. C57Bl/6 mice were treated by gavage with 3 mg/kg/day of riociguat for a total of 28 days. After two weeks of treatment, hindlimb ischemia was surgically induced by femoral artery removal.

RESULTS

In a matrigel assay in vitro, riociguat dose-dependently stimulates tubule formation in HUVECs. Cell migration (scratch assay) is also increased in HUVECs treated with riociguat. At the molecular level, riociguat treatment leads to rapid activation of the p44/p42 MAP kinase pathway in HUVECs. Inhibition of protein kinase G (PKG) activity supresses both p44/p42 MAP kinase activation and angiogenesis in HUVECs treated with riociguat. In vivo, treatment with riociguat improves blood flow recovery after ischemia (Laser Doppler imaging), and increases capillary density in ischemic muscles (CD31 immunostaining). Clinically, this is associated with a significant decrease of ambulatory impairment and ischemic damages. Interestingly, mice treated with riociguat also show a 94% increase in the number of bone marrow-derived pro-angiogenic cells (PACs) compared to control mice. Moreover, riociguat treatment is associated with a significant improvement of PAC functions including migratory capacity, adhesion to an endothelial monolayer, and integration into endothelial tubular networks.

CONCLUSIONS

The sGC stimulator riociguat promotes angiogenesis and improves neovascularization after ischemia. The mechanism involves PKG-dependent activation of p44/p42 MAP kinase pathway, together with an improvement of PAC number and functions. sGC stimulation could constitute a novel therapeutic strategy to reduce tissue ischemia in patients with severe atherosclerotic diseases.

Emerging Therapy for Diabetic Cardiomyopathy: From Molecular Mechanism to Clinical Practice

Diabetic cardiomyopathy is characterized by abnormal myocardial structure or performance in the absence of coronary artery disease or significant valvular heart disease in patients with diabetes mellitus. The spectrum of diabetic cardiomyopathy ranges from subtle myocardial changes to myocardial fibrosis and diastolic function and finally to symptomatic heart failure. Except for sodium–glucose transport protein 2 inhibitors and possibly bariatric and metabolic surgery, there is currently no specific treatment for this distinct disease entity in patients with diabetes. The molecular mechanism of diabetic cardiomyopathy includes impaired nutrient-sensing signaling, dysregulated autophagy, impaired mitochondrial energetics, altered fuel utilization, oxidative stress and lipid peroxidation, advanced glycation end-products, inflammation, impaired calcium homeostasis, abnormal endothelial function and nitric oxide production, aberrant epidermal growth factor receptor signaling, the activation of the renin–angiotensin–aldosterone system and sympathetic hyperactivity, and extracellular matrix accumulation and fibrosis. Here, we summarize several important emerging treatments for diabetic cardiomyopathy targeting specific molecular mechanisms, with evidence from preclinical studies and clinical trials.

Emerging concepts in heart failure management and treatment: focus on vericiguat

The nitric oxide (NO)-soluble guanylate cyclase (sGC)-cyclic guanosine monophosphate (cGMP) pathway is dysregulated in patients with heart failure (HF) resulting in myocardial and vascular dysfunction that contributes to its progression. Vericiguat is a novel direct sGC stimulator that targets in at least two ways the NO-sGC-cGMP pathway with the subsequent restoration of cGMP activity. The VICTORIA trial assessed the effects of vericiguat (versus placebo) in 5050 patients with chronic HF (NYHA class II-IV), left ventricular ejection fraction (LVEF) <45%, elevated natriuretic peptide levels and a recent HF decompensation (hospitalized or outpatient intravenous diuretics). After a median follow-up of 10.8 months, a lower risk (10% reduction) of the primary combined outcome (cardiovascular death or HF hospitalization) was achieved (HR 0.90, 95% CI 0.83-0.98; p=0.02). The composite endpoint was driven by HF hospitalizations (HR 0.9, 95% CI 0.81-1.00; p=0.048) whilst CV death reduction was not statistically significant on its own. The target dose was achieved in 89% of patients treated with vericiguat, and no significant differences were observed in the rates of syncope or hypotension. The VICTORIA trial showed that vericiguat was safe, well tolerated and without need of laboratory testing. The aim of this review is to provide comprehensive information about vericiguat in terms of its differential mechanism of action and clinical data particularly focused on the VICTORIA trial. A comparison is also made with DAPA-HF and EMPEROR-Reduced considering that, in all these contemporary trials, a new study medication was added to the standard triple HF therapy. This is a relevant issue because the VICTORIA trial had a significant but less powerful effect than DAPA-HF and EMPEROR-Reduced on HF outcomes in a setting of more severe disease, higher event rate and shorter follow-up. In addition, relevant data on other previous studies are also provided in both HF with reduced LVEF (SOCRATES-Reduced) and HF with preserved LVEF (SOCRATES-Preserved and VITALITY-Preserved). This article is part of the Emerging concepts in heart failure management and treatment Special Issue: https://www.drugsincontext.com/special_issues/emerging-concepts-in-heart-failure-management-and-treatment.

Combination therapy of newly diagnosed intermediate-risk pulmonary arterial hypertension: A review

Advancements in the specific therapy of pulmonary arterial hypertension (PAH) and new combination therapy strategies and escalation treatment over the past decade have significantly improved disease control, slowed its progression, and improved quality of life and patient survival. This review provides a detailed discussion of current strategies for PAH-specific therapy available in the Russian Federation for patients with classical and non-classical PAH who fail to achieve treatment goals and remain at intermediate risk of disease progression/mortality.

Safety and Feasibility of Riociguat Therapy for the Treatment of Chronic Pulmonary Arterial Hypertension in Infancy

The effects of riociguat, an oral-soluble guanylate-cyclase stimulator, were studied in 10 infants with chronic pulmonary arterial hypertension. Respiratory status (n = 8/10), right heart dilation (n = 7/10), function (n = 9/10), and chronic pulmonary arterial hypertension (n = 8/10) improved. Median decrement in systolic (12 [4, 14]), diastolic (14 [7, 20]), and mean arterial (14 [10, 17]) pressures were noted; no critical hypotension or hypoxemia occurred.

Activating NO-sGC crosstalk in the mouse vascular niche promotes vascular integrity and mitigates acute lung injury

Disruption of endothelial cell (ECs) and pericytes interactions results in vascular leakage in acute lung injury (ALI). However, molecular signals mediating EC-pericyte crosstalk have not been systemically investigated, and whether targeting such crosstalk could be adopted to combat ALI remains elusive. Using comparative genome-wide EC-pericyte crosstalk analysis of healthy and LPS-challenged lungs, we discovered that crosstalk between endothelial nitric oxide and pericyte soluble guanylate cyclase (NO-sGC) is impaired in ALI. Indeed, stimulating the NO-sGC pathway promotes vascular integrity and reduces lung edema and inflammation-induced lung injury, while pericyte-specific sGC knockout abolishes this protective effect. Mechanistically, sGC activation suppresses cytoskeleton rearrangement in pericytes through inhibiting VASP-dependent F-actin formation and MRTFA/SRF-dependent de novo synthesis of genes associated with cytoskeleton rearrangement, thereby leading to the stabilization of EC-pericyte interactions. Collectively, our data demonstrate that impaired NO-sGC crosstalk in the vascular niche results in elevated vascular permeability, and pharmacological activation of this crosstalk represents a promising translational therapy for ALI.

Synthesis and Vasorelaxant Activity of Nitrate-Coumarin Derivatives

Due to the need for new chemical entities for cardiovascular diseases, we have synthesized a new series of nitrate-coumarins and evaluated their vasorelaxant activity in contraction-relaxation studies using rat aorta rings precontracted with phenylephrine or by depolarization with a high concentration of potassium chloride. Four of the new compounds were able to relax smooth vascular muscle with a similar profile and potency to glyceryl trinitrate (IC50 =12.73 nM) and sodium nitroprusside (IC50 =4.32 nM). Coumarin-7-yl-methyl nitrate (4), the best compound within the series, was able to relax smooth vascular muscle in the low nanomolar range (IC50 =1.92 nM). The mechanisms of action have been explored, being the activation of sGC and the opening of K+ channels involved. Our studies indicate that the new nitrate derivatives are reversible and not deleterious for aortic rings, suggesting that these compounds have a potential interest for the development of new and highly efficient vasodilator drugs.

Compartmentation of cGMP Signaling in Induced Pluripotent Stem Cell Derived Cardiomyocytes during Prolonged Culture

The therapeutic benefit of stimulating the cGMP pathway as a form of treatment to combat heart failure, as well as other fibrotic pathologies, has become well established. However, the development and signal compartmentation of this crucial pathway has so far been overlooked. We studied how the three main cGMP pathways, namely, nitric oxide (NO)-cGMP, natriuretic peptide (NP)-cGMP, and β3-adrenoreceptor (AR)-cGMP, mature over time in culture during cardiomyocyte differentiation from human pluripotent stem cells (hPSC-CMs). After introducing a cGMP sensor for Förster Resonance Energy Transfer (FRET) microscopy, we used selective phosphodiesterase (PDE) inhibition to reveal cGMP signal compartmentation in hPSC-CMs at various times of culture. Methyl-β-cyclodextrin was employed to remove cholesterol and thus to destroy caveolae in these cells, where physical cGMP signaling compartmentalization is known to occur in adult cardiomyocytes. We identified PDE3 as regulator of both the NO-cGMP and NP-cGMP pathway in the early stages of culture. At the late stage, the role of the NO-cGMP pathway diminished, and it was predominantly regulated by PDE1, PDE2, and PDE5. The NP-cGMP pathway shows unrestricted locally and unregulated cGMP signaling. Lastly, we observed that maturation of the β3-AR-cGMP pathway in prolonged cultures of hPSC-CMs depends on the accumulation of caveolae. Overall, this study highlighted the importance of structural development for the necessary compartmentation of the cGMP pathway in maturing hPSC-CMs.

Vericiguat in Heart Failure: Characteristics, Scientific Evidence and Potential Clinical Applications

Despite recent advances in heart failure (HF) management, the risk of death and hospitalizations remains high in the long term. HF is characterized by endothelial dysfunction, inflammation and increased oxidative stress, due to a reduction in the activity of the nitric oxide (NO)-soluble guanylate cyclase (sGC)-cyclic guanosine monophosphate (cGMP) signaling pathway. All these factors contribute to direct damage at the myocardial, vascular and renal level. Vericiguat restores the deficiency in this signaling pathway, through stimulation and activation of sGC, aiming to increase cGMP levels, with a reduction in HF-related oxidative stress and endothelial dysfunction. Two main clinical trials were developed in this setting: the SOCRATES-REDUCED phase II study and the VICTORIA phase III study. They found that vericiguat is safe, well tolerated and effective with an absolute event-rate reduction in patients affected by HF with reduced ejection fraction (HFrEF) and recent cardiac decompensation. In patients with HF with preserved ejection fraction (HfpEF), the SOCRATES-PRESERVED trial demonstrated an improvement in quality of life and health status, but the proven beneficial effects with vericiguat are still limited. Further studies are needed to correctly define the role of this drug in heart failure syndromes. Our paper reviews the potential applications and pharmacological characteristics of vericiguat in HFrEF and HFpEF.

Inhaled mosliciguat (BAY 1237592): targeting pulmonary vasculature via activating apo-sGC

Background

Oxidative stress associated with severe cardiopulmonary diseases leads to impairment in the nitric oxide/soluble guanylate cyclase signaling pathway, shifting native soluble guanylate cyclase toward heme-free apo-soluble guanylate cyclase. Here we describe a new inhaled soluble guanylate cyclase activator to target apo-soluble guanylate cyclase and outline its therapeutic potential.

Methods

We aimed to generate a novel soluble guanylate cyclase activator, specifically designed for local inhaled application in the lung. We report the discovery and in vitro and in vivo characterization of the soluble guanylate cyclase activator mosliciguat (BAY 1237592).

Results

Mosliciguat specifically activates apo-soluble guanylate cyclase leading to improved cardiopulmonary circulation. Lung-selective effects, e.g., reduced pulmonary artery pressure without reduced systemic artery pressure, were seen after inhaled but not after intravenous administration in a thromboxane-induced pulmonary hypertension minipig model. These effects were observed over a broad dose range with a long duration of action and were further enhanced under experimental oxidative stress conditions. In a unilateral broncho-occlusion minipig model, inhaled mosliciguat decreased pulmonary arterial pressure without ventilation/perfusion mismatch. With respect to airway resistance, mosliciguat showed additional beneficial bronchodilatory effects in an acetylcholine-induced rat model.

Conclusion

Inhaled mosliciguat may overcome treatment limitations in patients with pulmonary hypertension by improving pulmonary circulation and airway resistance without systemic exposure or ventilation/perfusion mismatch. Mosliciguat has the potential to become a new therapeutic paradigm, exhibiting a unique mode of action and route of application, and is currently under clinical development in phase Ib for pulmonary hypertension.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02189-1.

Misuse of Cardiac Lipid upon Exposure to Toxic Trace Elements-A Focused Review

Heavy metals and metalloids like cadmium, arsenic, mercury, and lead are frequently found in the soil, water, food, and atmosphere; trace amounts can cause serious health issues to the human organism. These toxic trace elements (TTE) affect almost all the organs, mainly the heart, kidney, liver, lungs, and the nervous system, through increased free radical formation, DNA damage, lipid peroxidation, and protein sulfhydryl depletion. This work aims to advance our understanding of the mechanisms behind lipid accumulation via increased free fatty acid levels in circulation due to TTEs. The increased lipid level in the myocardium worsens the heart function. This dysregulation of the lipid metabolism leads to damage in the structure of the myocardium, inclusive fibrosis in cardiac tissue, myocyte apoptosis, and decreased contractility due to mitochondrial dysfunction. Additionally, it is discussed herein how exposure to cadmium decreases the heart rate, contractile tension, the conductivity of the atrioventricular node, and coronary flow rate. Arsenic may induce atherosclerosis by increasing platelet aggregation and reducing fibrinolysis, as exposure interferes with apolipoprotein (Apo) levels, resulting in the rise of the Apo-B/Apo-A1 ratio and an elevated risk of acute cardiovascular events. Concerning mercury and lead, these toxicants can cause hypertension, myocardial infarction, and carotid atherosclerosis, in association with the generation of free radicals and oxidative stress. This review offers a complete overview of the critical factors and biomarkers of lipid and TTE-induced cardiotoxicity useful for developing future protective interventions.

An update on the current status and future prospects of erectile dysfunction following radical prostatectomy

BACKGROUND

Radical prostatectomy (RP) and radiation treatment are standard options for localized prostate cancer. Even though nerve-sparing techniques have been increasingly utilized in RP, erectile dysfunction (ED) due to neuropraxia remains a frequent complication. Erectile function recovery rates after RP remain unsatisfactory, and many men still suffer despite the availability of various therapies.

OBJECTIVE

This systematic review aims to summarize the current treatments for post-RP-ED, assess the underlying pathological mechanisms, and emphasize promising therapeutic strategies based on the evidence from basic research.

METHOD

Evaluation and review of articles on the relevant topic published between 2010 and 2021, which are indexed and listed in the PubMed database.

RESULTS

Phosphodiesterase type 5 inhibitors, intracavernosal and intraurethral injections, vacuum erection devices, pelvic muscle training, and surgical procedures are utilized for penile rehabilitation. Clinical trials evaluating the efficacy of erectogenic drugs in this setting are conflicting and far from being conclusive. The use of androgen deprivation therapy in certain scenarios after RP further exacerbates the already problematic situation and emphasizes the need for effective treatment strategies.

CONCLUSION

This article is a detailed overview focusing on the pathophysiology and mechanism of the nerve injury developed during RP and a compilation of various strategies to induce cavernous nerve regeneration to improve erectile function (EF). These strategies include stem cell therapy, gene therapy, growth factors, low-intensity extracorporeal shockwave therapy, immunophilins, and various pharmacological approaches that have induced improvements in EF in experimental models of cavernous nerve injury. Many of the mentioned strategies can improve EF following RP if transformed into clinically applicable safe, and effective techniques with reproducible outcomes.

Bibliometric study of soluble guanylate cyclase stimulators in cardiovascular research based on web of science from 1992 to 2021

Background: Several studies have shown that soluble guanylate cyclase (sGC) stimulators have cardiovascular (CV) benefits. However, few bibliometric analyses have examined this field systematically. Our study aimed to examine the publications to determine the trends and hotspots in CV research on sGC stimulators.

Methods: Publications on sGC stimulators in CV research were retrieved from the Web of Science Core Collection. VOSviewer and CiteSpace visualization software were used to analyze publication trends, countries (regions) and institutions, journals and cited journals, authors and cited references, as well as keywords.

Results: A total of 1,212 literatures were obtained. From its first appearance in 1992–2021 (based on WOSCC record), the overall volume of publications has shown a gradual increasing trend. Nearly one-third were authored by American scholars, and most were published in Circulation, Circulation Research, and Proceedings of the National Academy of Sciences of the United States of America. Bayer Agency in Germany was the leading driving force, and has a high academic reputation in this field. Stasch JP has published the most related articles and been cited most frequently. Half of the top 10 co-cited references were published in the leading highly co-cited journal Circulation and New England Journal of Medicine. “NO,” “allosteric regulation” and “free radicals” were the focus of previous research, “chronic thromboembolic pulmonary hypertension,” “pulmonary hypertension” and “heart failure” were the main research hotspots. The key words “chronic thromboembolic pulmonary hypertension,” “Pulmonary hypertension,” “preserved ejection fraction” and “heart failure” appeared most recently as research frontiers.

Conclusion: The research in the CV field of sGC stimulators was relatively comprehensive, and there was a close relationship among countries, research institutions and authors, but it is still in the exploratory stage in the treatment of CV disease. At present, most studies focus on the results of clinical trials. sGC stimulators in the treatment of heart failure, especially heart failure with preserved ejection fraction, may be the hotpots and Frontier at present and in the future, and should be closely monitored.

Oxidative stress - Complex pathological issues concerning the hallmark of cardiovascular and metabolic disorders

Oxidative stress is a complex biological process characterized by the excessive production of reactive oxygen species (ROS) that act as destroyers of the REDOX balance in the body and, implicitly, inducing oxidative damage. All the metabolisms are impaired in oxidative stress and even nucleic acid balance is influenced. ROS will promote structural changes of the tissues and organs due to interaction with proteins and phospholipids. The constellation of the cardiovascular risk factors (CVRFs) will usually develop in subjects with predisposition to cardiac disorders. Oxidative stress is usually related with hypertension (HTN), diabetes mellitus (DM), obesity and cardiovascular diseases (CVDs) like coronary artery disease (CAD), cardiomyopathy or heart failure (HF), that can develop in subjects with the above-mentioned diseases. Elements describing the complex relationship between CVD and oxidative stress should be properly explored and described because prevention may be the optimal approach. Our paper aims to expose in detail the complex physiopathology of oxidative stress in CVD occurrence and novelties regarding the phenomenon. Biomarkers assessing oxidative stress or therapy targeting specific pathways represent a major progress that actually change the outcome of subjects with CVD. New antioxidants therapy specific for each CVD represents a captivating and interesting future perspective with tremendous benefits on subject's outcome.

Investigational drugs in early clinical development for portal hypertension

INTRODUCTION

Advanced chronic liver disease is considered a reversible condition after removal of the primary aetiological factor. This has led to a paradigm shift in which portal hypertension (PH) is a reversible complication of cirrhosis. The pharmacologic management of PH is centered on finding targets to modify the natural history of cirrhosis and PH.

AREAS COVERED

This paper offers an overview of the use of pharmacological strategies in early clinical development that modify PH. Papers included were selected from searching clinical trials sites and PubMed from the last 10 years.

EXPERT OPINION

A paradigm shift has generated a new concept of PH in cirrhosis as a reversible complication of a potentially curable disease. Decreasing portal pressure to prevent decompensation and further complications of cirrhosis that may lead liver transplantation or death is a goal. Therapeutic strategies also aspire achieve total or partial regression of fibrosis thus eliminating the need for treatment or screening of PH.

Mapping of the sGC Stimulator BAY 41-2272 Binding Site on H-NOX Domain and Its Regulation by the Redox State of the Heme

Soluble guanylate cyclase (sGC) is the main receptor of nitric oxide (NO) and by converting GTP to cGMP regulates numerous biological processes. The β1 subunit of the most abundant, α1β1 heterodimer, harbors an N-terminal domain called H-NOX, responsible for heme and NO binding and thus sGC activation. Dysfunction of the NO/sGC/cGMP axis is causally associated with pathological states such as heart failure and pulmonary hypertension. Enhancement of sGC enzymatic function can be effected by a class of drugs called sGC “stimulators,” which depend on reduced heme and synergize with low NO concentrations. Until recently, our knowledge about the binding mode of stimulators relied on low resolution cryo-EM structures of human sGC in complex with known stimulators, while information about the mode of synergy with NO is still limited. Herein, we couple NMR spectroscopy using the H-NOX domain of the Nostoc sp. cyanobacterium with cGMP determinations in aortic smooth muscle cells (A7r5) to study the impact of the redox state of the heme on the binding of the sGC stimulator BAY 41-2272 to the Ns H-NOX domain and on the catalytic function of the sGC. BAY 41-2272 binds on the surface of H-NOX with low affinity and this binding is enhanced by low NO concentrations. Subsequent titration of the heme oxidant ODQ, fails to modify the conformation of H-NOX or elicit loss of the heme, despite its oxidation. Treatment of A7r5 cells with ODQ following the addition of BAY 41-2272 and an NO donor can still inhibit cGMP synthesis. Overall, we describe an analysis in real time of the interaction of the sGC stimulator, BAY 41-2272, with the Ns H-NOX, map the amino acids that mediate this interaction and provide evidence to explain the characteristic synergy of BAY 41-2272 with NO. We also propose that ODQ can still oxidize the heme in the H-NOX/NO complex and inhibit sGC activity, even though the heme remains associated with H-NOX. These data provide a more-in-depth understanding of the molecular mode of action of sGC stimulators and can lead to an optimized design and development of novel sGC agonists.

Pharmacological developments in antihypertensive treatment through nitric oxide-cGMP modulation

Treatment of hypertension until now has been directed at inhibition of vasoconstriction, of cardiac contractility and of blood volume regulation. Despite the arsenal of drugs available for this purpose, the control of target blood pressure is still a difficult goal to reach in outpatients. The nitric oxide-cyclic guanosine monophosphate signaling is one of the most important mediators of vasodilation. It might therefore be a potential and most welcome drug target for optimization of the treatment of hypertension. In this chapter we review the problems that can occur in this signaling system, the attempts that have been made to correct these problems, and those that are still under investigation. Recently developed, clinically safe medicines that are currently approved for other applications, such as myocardial infarction, await to be tested for essential systemic hypertension. We conclude that despite many years of research without translation, stimulation of nitric oxide-cyclic guanosine monophosphate is still a viable strategy in the prevention of the health risk posed by chronic hypertension.

Angiotensin II augments renal vascular smooth muscle soluble GC expression via an AT1 receptor-forkhead box subclass O transcription factor signalling axis

BACKGROUND AND PURPOSE

Reduced renal blood flow triggers activation of the renin-angiotensin-aldosterone system (RAAS) leading to renovascular hypertension. Renal vascular smooth muscle expression of the NO receptor, soluble GC (sGC), modulates the vasodilator response needed to control renal vascular tone and blood flow. Here, we tested if angiotensin II (Ang II) affects sGC expression via an AT1 receptor-forkhead box subclass O (FoxO) transcription factor dependent mechanism.

EXPERIMENTAL APPROACH

Using a murine two-kidney-one-clip (2K1C) renovascular hypertension model, we measured renal artery vasodilatory function and sGC expression. Additionally, we conducted cell culture studies using rat renal pre-glomerular smooth muscle cells (RPGSMCs) to test the in vitro mechanistic effects of Ang II treatment on sGC expression and downstream function.

KEY RESULTS

Contralateral, unclipped renal arteries in 2K1C mice showed increased NO-dependent vasorelaxation compared to sham control mice. Immunofluorescence studies revealed increased sGC protein expression in 2K1C contralateral renal arteries over sham controls. RPGSMCs treated with Ang II caused a significant up-regulation of sGC mRNA and protein expression as well as downstream sGC-dependent signalling. Ang II signalling effects on sGC expression occurred through an AT1 receptor and FoxO transcription factor-dependent mechanism at both the mRNA and protein expression levels.

CONCLUSION AND IMPLICATIONS

Renal artery smooth muscle, in vivo and in vitro, up-regulates expression of sGC following RAAS activity. In both cases, up-regulation of sGC leads to increased downstream cGMP signalling, suggesting a previously unrecognized protective mechanism to improve renal blood flow in the uninjured contralateral renal artery.

LINKED ARTICLES

This article is part of a themed issue on cGMP Signalling in Cell Growth and Survival. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v179.11/issuetoc.

Nitric-Oxide-Mediated Signaling in Podocyte Pathophysiology

Nitric oxide (NO) is a potent signaling molecule involved in many physiological and pathophysiological processes in the kidney. NO plays a complex role in glomerular ultrafiltration, vasodilation, and inflammation. Changes in NO bioavailability in pathophysiological conditions such as hypertension or diabetes may lead to podocyte damage, proteinuria, and rapid development of chronic kidney disease (CKD). Despite the extensive data highlighting essential functions of NO in health and pathology, related signaling in glomerular cells, particularly podocytes, is understudied. Several reports indicate that NO bioavailability in glomerular cells is decreased during the development of renal pathology, while restoring NO level can be beneficial for glomerular function. At the same time, the compromised activity of nitric oxide synthase (NOS) may provoke the formation of peroxynitrite and has been linked to autoimmune diseases such as systemic lupus erythematosus. It is known that the changes in the distribution of NO sources due to shifts in NOS subunits expression or modifications of NADPH oxidases activity may be linked to or promote the development of pathology. However, there is a lack of information about the detailed mechanisms describing the production and release of NO in the glomerular cells. The interaction of NO and other reactive oxygen species in podocytes and how NO-calcium crosstalk regulates glomerular cells’ function is still largely unknown. Here, we discuss recent reports describing signaling, synthesis, and known pathophysiological mechanisms mediated by the changes in NO homeostasis in the podocyte. The understanding and further investigation of these essential mechanisms in glomerular cells will facilitate the design of novel strategies to prevent or manage health conditions that cause glomerular and kidney damage.

Highly Diluted Antibodies to eNOS Restore Endothelium Function in Aortic Rings From Hypertensive Rats

Background

Nitric oxide (NO) as a vaso- and cardio-protective agent could reduce vasomotor dysfunction in different cardiovascular diseases. One of the current therapeutics targeted at NO availability in the vascular wall are highly diluted antibodies to endothelial NO-synthase (eNOS). This drug has previously shown its endothelium-protective effect and effectiveness in reducing hypertension. Current study was dedicated to evaluate the direct impact of highly diluted antibodies to eNOS on the vessel constriction and dilation ex vivo.

Methods

For that purpose, we used thoracic aortas dissected from spontaneously hypertensive (SHR) rats. Endothelium-dependent relaxation in the presence of highly diluted antibodies to eNOS (1 mL) was examined after phenylephrine-induced pre-constriction of the aorta rings in response to gradually increased acetylcholine concentration (1 nM to 10 µM).

Results

Highly diluted antibodies to eNOS enhanced acetylcholine-induced relaxation in a statistically significant manner. Moreover, it was demonstrated that observed effect was similar to perindopril, a well-known angiotensin-converting-enzyme inhibitor, which works through relaxing and widening blood vessels.

Conclusions

Our findings indicate that highly diluted antibodies to eNOS restored impaired endothelium function, as demonstrated by increased relaxation of SHR rats aorta rings. The revealed results suggest beneficial effect of highly diluted antibodies to eNOS to ameliorate hypertension and related diseases.

Development of vericiguat: The first soluble guanylate cyclase (sGC) stimulator launched for heart failure with reduced ejection fraction (HFrEF)

In recent years, with improvements in treatments for heart failure (HF), the survival period of patients has been extended. However, the emergence of some patients with repeated hospitalizations due to their worsening conditions and low survival rates followed. Currently, few drugs are available for such patients. Vericiguat was first drug approved for the treatment of symptomatic patients with chronic HF with reduced ejection fraction (HFrEF) to reduce the occurrence of worsening HF. This article provides comprehensive information about vericiguat in terms of drug design and development, structure-activity relationship (SAR), synthesis, pharmacological efficacy, and clinical practice. In addition, insights into the current vericiguat trials and treatments of HF are also discussed.

Cyclic GMP and PKG Signaling in Heart Failure

Cyclic guanosine monophosphate (cGMP), produced by guanylate cyclase (GC), activates protein kinase G (PKG) and regulates cardiac remodeling. cGMP/PKG signal is activated by two intrinsic pathways: nitric oxide (NO)-soluble GC and natriuretic peptide (NP)-particulate GC (pGC) pathways. Activation of these pathways has emerged as a potent therapeutic strategy to treat patients with heart failure, given cGMP-PKG signaling is impaired in heart failure with reduced ejection fraction (HFrEF) and preserved ejection fraction (HFpEF). Large scale clinical trials in patients with HFrEF have shown positive results with agents that activate cGMP-PKG pathways. In patients with HFpEF, however, benefits were observed only in a subgroup of patients. Further investigation for cGMP-PKG pathway is needed to develop better targeting strategies for HFpEF. This review outlines cGMP-PKG pathway and its modulation in heart failure.