sGC Activity Research Articles

A novel soluble guanylate cyclase activator, avenciguat, in combination with empagliflozin, protects against renal and hepatic injury in diabetic db/db mice.

Diabetic complications are linked to oxidative stress, which hampers the cyclic guanosine monophosphate production by inhibiting nitric oxide /soluble guanylate cyclase (sGC) signalling. This study aimed to determine whether administration of a novel sGC activator avenciguat alone or in combination with a SGLT2 inhibitor could slow the progression of renal and liver fibrosis in the type 2 diabetic and uninephrectomized db/db mouse model. Experiment groups included normal controls, untreated db/db mice terminated at 12 and 18 weeks of age, and db/db mice treated with either one of two doses of avenciguat alone, empagliflozin (Empa) alone, or a combination of both from weeks 12 to 18 of age. Untreated db/db mice exhibited obesity, hyperglycemia, elevated levels of HbA1c and triglycerides (TG) and developed progressive albuminuria, glomerulosclerosis, fatty liver and liver fibrosis between weeks 12 and 18 of age, accompanied by increased renal and liver production of fibronectin, type-IV collagen, laminin, and increased oxidative stress markers. Avenciguat had no effect on body weight but reduced both blood HbA1c and TG levels, while Empa reduced HbA1c but not TG levels as compared to untreated db/db. Both avenciguat and Empa alone effectively slowed the progression of diabetes-associated glomerulosclerosis and liver fibrosis. Importantly, avenciguat, especially at high dose in combination with Empa, further lowered these progression markers compared to baseline measurements. These results suggested that either avenciguat alone or in combination with Empa is therapeutic. Avenciguat in combination with Empa shows promise in halting the progression of diabetic complications.

Unveiling the interplay between soluble guanylate cyclase activation and redox signalling in stroke pathophysiology and treatment.

Soluble guanylate cyclase (sGC) stands as a pivotal regulatory element in intracellular signalling pathways, mediating the formation of cyclic guanosine monophosphate (cGMP) and impacting diverse physiological processes across tissues. Increased formation of reactive oxygen species (ROS) is widely recognized to modulate cGMP signalling. Indeed, oxidatively damaged, and therefore inactive sGC, contributes to poor vascular reactivity and more severe neurological damage upon stroke. However, the specific involvement of cGMP in redox signalling remains elusive. Here, we demonstrate a significant cGMP-dependent reduction of reactive oxygen and nitrogen species upon sGC activation under hypoxic conditions, independent of any potential scavenger effects. Importantly, this reduction is directly mediated by downregulating NADPH oxidase (NOX) 4 and 5 during reperfusion. Using an in silico simulation approach, we propose a mechanistic link between increased cGMP signalling and reduced ROS formation, pinpointing NF-κB1 and RELA/p65 as key transcription factors regulating NOX4/5 expression. In vitro studies revealed that p65 translocation to the nucleus was reduced in hypoxic human microvascular endothelial cells following sGC activation. Altogether, these findings unveil the intricate regulation and functional implications of sGC, providing valuable insights into its biological significance and ultimately therapeutic potential.

Soluble guanylyl cyclase stimulators and activators: promising drugs for the treatment of hypertension?

Nitric oxide (NO)-stimulated cyclic guanosine monophosphate (cGMP) is a key regulator of cardiovascular health, as NO-cGMP signalling is impaired in diseases like pulmonary hypertension, heart failure and chronic kidney disease. The development of NO-independent sGC stimulators and activators provide a novel therapeutic option to restore altered NO signalling. sGC stimulators have been already approved for the treatment of pulmonary arterial hypertension (PAH), chronic thromboembolic pulmonary hypertension (CTEPH), and chronic heart failure (HFrEF), while sGC activators are currently in phase-2 clinical trials for CKD.The best characterized effect of increased cGMP via the NO-sGC-cGMP pathway is vasodilation. However, to date, none of the sGC agonists are in development for hypertension (HTN). According to WHO, the global prevalence of uncontrolled HTN continues to rise, contributing significantly to cardiovascular mortality. While there are effective antihypertensive treatments, many patients require multiple drugs, and some remain resistant to all therapies. Thus, in addition to improved diagnosis and lifestyle changes, new pharmacological strategies remain in high demand.In this review we explore the potential of sGC stimulators and activators as novel antihypertensive agents, starting with the overview of NO-sGC-cGMP signalling, followed by potential mechanisms by which the increase in cGMP may regulate vascular tone and BP. These effects may encompass not only acute vasodilation, but also mid-term and chronic effects, such as the regulation of salt and water balance, as well as mitigation of vascular ageing and remodelling. The main section summarizes the preclinical and clinical evidence supporting the BP-lowering efficacy of sGC agonists.

Runcaciguat activates soluble guanylyl cyclase via the histidine essential for heme binding and nitric oxide activation.

Soluble guanylyl cyclase (sGC) is a well-established pharmacological target for the treatment of acute angina pectoris, pulmonary hypertension and heart failure. Histidine 105 in the heme binding pocket of sGC is a crucial residue for heme binding and natural enzyme activation by NO. It was assumed that the heme-free sGC mutants α1/β1H105F and α1/β1H105A were valuable research tools for studying NO independent sGC activators. These mutants have been used in drug screening and animal models. We confirm that the first generation of sGC activators cinaciguat and BAY 60-2770 activate the α1/β1H105F and α1/β1H105A mutants. In contrast, we show that the second generation sGC activators runcaciguat and BAY 543 only activate heme-free sGC when the β1H105 residue is present. By testing runcaciguat in β1 H105F knock-in mice, we confirm this histidine-dependency in vivo. We propose a novel classification of sGC activators, distinguishing between the histidine-dependent activators runcaciguat and BAY 543 and the histidine-independent activators cinaciguat, BAY 60-2770 and BI703704. The histidine-dependency of some of the sGC activators provides a compelling rationale for a re-evaluation of previous research and drug development programs based on sGC histidine mutants. Whether the classification of sGC activators based on the activation mechanism also makes a therapeutic difference needs to be clarified in the future.

The soluble guanylate cyclase activator runcaciguat significantly improves albuminuria in patients with chronic kidney disease: a randomized placebo-controlled clinical trial.

In chronic kidney disease (CKD) the nitric oxide (NO)-soluble guanylate cyclase (sGC)-cyclic guanosine monophosphate (cGMP) pathway is impaired. Runcaciguat, an sGC activator, activates heme-free sGC, restoring cGMP production. This phase 2a trial studied the efficacy, safety, and tolerability of runcaciguat in CKD patients with or without sodium-glucose co-transporter-2 inhibitor (SGLT2i). Patients with CKD and established atherosclerotic cardiovascular disease or heart failure, plus type 2 diabetes (T2D) and/or hypertension, were enrolled. All were receiving stable maximum tolerated renin-angiotensin system inhibitors with or without SGLT2i. They were randomized 3:1 to runcaciguat once daily, titrated weekly (30-120mg if tolerated), or placebo for 8 weeks. The primary efficacy endpoint was urine albumin-to-creatinine ratio (UACR) (average of post-randomization Days 22, 29, and 57vs baseline). CONCORD was separately powered for CKD and T2D with stable SGLT2i comedication, CKD and T2D without SGLT2i, and non-diabetic CKD. Of 243 patients randomized, 229 were included in the full analysis set (FAS) and 170 in the per-protocol set (PPS). In the PPS, UACR decreased by-45.2% versus placebo with runcaciguat in patients with CKD without SGLT2i (P<0.001) and by-48.1% versus placebo in patients with CKD taking SGLT2i (P=0.02) In the FAS, the relative reductions were-46.9% (P<0.001) and-44.8% (P=0.01), respectively. No significant difference was observed between patients with or without SGLT2i. In non-diabetic CKD, UACR was reduced versus baseline with runcaciguat, but the change was not statistically significant (P=0.10). Serious treatment-emergent adverse events were reported in 7% of patients receiving runcaciguat and 8% receiving placebo. Runcaciguat improved albuminuria in patients with CKD, irrespective of concomitant SGLT2i. Runcaciguat was well tolerated. sGC activation may represent a novel kidney-protective treatment in CKD patients (funded by Bayer AG; ClinicalTrials.gov number, NCT04507061).

Controlling the trans effect induced by nitric oxide and carbon monoxide: H93C myoglobin versus H-NOX sensors and soluble guanylate cyclase.

Myoglobin (Mb) has been engineered to replace the proximal histidine (His93) with a cysteine in order to investigate the trans effect induced by diatomic ligands using time-resolved electronic absorption spectroscopy. This single mutation induces a change of heme coordination state and bonding character which change carbon monoxide (CO) and nitric oxide (NO) dynamics. In H93C Mb the increased Fe2+-S distance weakens this bond which is replaced with a distal Fe2+-His64 ligation. We measured dynamics very different from wild type Mb but similar with those measured in soluble guanylate cyclase (sGC). Whereas NO induces a direct negative trans effect, the strain on His64 ligation is sufficient to counteract the positive trans effect due to CO. After photodissociation, geminate recombination of NO to the transient 4-coordinate heme of H93C occurred with a fast time constant (6.9 ps) identical to that in sGC. Remarkably, we also observed picosecond geminate rebinding of CO to H93C Mb, similarly with sGC in the simultaneous presence of CO and an allosteric stimulator. This CO rebinding dynamics to the 4c-heme in H93C Mb was never measured in other Mb mutants and demonstrates the existence of 5-coordinate heme with CO, explaining the synergistic activation of sGC in presence of CO and a stimulator.

Alanine mutation of the targeting subunit of the myosin phosphatase, MYPT1 at threonine 696 reduces cGMP responsiveness of mouse femoral arteries

The femoral artery (FA) is the largest vessel in the hindlimb circulation and its proper tone regulation ensures adequate blood supply to muscle tissue. We investigated whether an alanine mutation of the targeting subunit of myosin-light-chain-phosphatase (MLCP), MYPT1, at threonine 696 (MYPT1-T696A/+), decisive for enzyme acivity, affects the responsiveness of young and old FAs (y-FAs and o-FAs) to activation of nitric-oxide/soluble-guanylate-cyclase/protein-kinase-G cascade (NO/sGC/PKG). Contractile responses of the vessels were measured by wire myography. Phosphorylation of the regulatory myosin-light-chain at serine 19 (MLC20-S19), the myosin-light-chain-phosphatase targeting subunit, MYPT1-T696, the PKG-sensitive site of MYPT1 at S695 (MYPT1-S695) and S668 (MYPT1-S668), and the regulatory phosphorylation of eNOS at S1177 (eNOS-S1177) were determined in arterial homogenates by Western blot. In FAs of all ages, the MYPT1-T696A-mutation did not alter vessel diameter and the contractile reactivity to the thromboxaneA2-analogue, U46619 and the RhoA kinase inhibitor, Y27632. In contrast, the mutation T696 into alanine attenuated the relaxing effect of exogenous NO (DEA-NONOate) in y-FAs. The effect of a direct sGC activation by cinaciguat was also attenuated in both age groups of MYPT1-T696A/+, but strongly in o-FA . The MYPT1-T696A-mutation also attenuated acetylcholine-induced relaxation, but only in o-FAs. Similary, the alanine mutation attenuated the acetylcholine effect on MLC20-S19- and MYPT1-T696 only in WT o-FAs. Interestingly, neither eNOS-S1177 nor the phosphorylation of the PKG phosphospecific sites, MYPT1-S695 and MYPT1-S668 were altered by MYPT1-T696A-mutation or aging. These findings suggest that the alanine mutation of MYPT1-T696 reduces the ability of the NO/cGMP/PKG-system to relax FAs in aging.

Different sensitivities of porcine coronary arteries and veins to BAY 60–2770, a soluble guanylate cyclase activator

Nitric oxide (NO)-donor drugs, which stimulate reduced form of soluble guanylate cyclase (sGC), have different efficacy to the arteries and veins. This study examined whether sGC activators, which activate oxidized/apo sGC, also have arteriovenous selectivity similar to that of NO-donor drugs. The mechanical responses of the isolated blood vessels were assessed using the organ chamber technique and protein expression was verified using western blotting. BAY 60–2770 (sGC activator) caused concentration-dependent relaxation in both porcine coronary arteries and veins, with the response being slightly more pronounced in the arteries. In contrast, sodium nitroprusside (NO-donor drug)-induced relaxation of the arteries was slightly weaker than that of the veins. Vasorelaxant responses to 8-Br-cGMP (cGMP analog) did not differ between the arteries and veins. In the presence of ODQ (heme oxidant), the heterogeneities in the responses to BAY 60–2770 and sodium nitroprusside between the arteries and veins disappeared. The sGC expression in the arteries did not differ from that in the veins. These findings suggest that sGC activators, in contrast to NO-donor drugs, have greater effects on the arteries than on the veins. This may be due to differences in the balance of sGC forms expressed in the arteries and veins.

Expression of soluble guanylate cyclase (sGC) and its ability to form a functional heterodimer are crucial for reviving the NO-sGC signaling in PAH

In order to determine the underpinnings of a dysfunctional NO-sGC signal pathway which occurs in pulmonary arterial hypertension (PAH), we investigated pulmonary arterial smooth muscle cells (PASMCs) derived from PAH patients. We found low expression of sGC, a poor sGCα1β1 heterodimer and this correlated with low expression of its facilitator chaperon, hsp90. Treating PASMCs overnight (16 h) with low micromolar doses of a slow release NO donor DETANONOate, reinstated the sGCα1β1 heterodimer and restored its NO-heme dependent activity. Transwell co-culture of HEK cells stably expressing eNOS with PAH PASMCs also restored the sGC heterodimer and its heme-dependent activity with sGC stimulator, BAY 41–2272. To determine whether the dysfunctionality in the NO-sGC pathway stems from a dysfunctional eNOS producing negligible NO, we did transwell co-cultures of pulmonary arterial endothelial cells (PAECs) with PASMCs. Our results indicated that PAECs from both control and PAH samples when activated for eNOS restored both sGC heterodimer and its heme-dependent sGC activity in the corresponding PASMCs, suggesting that PAECs from PAH can also generate NO. In line with these results expression of eNOS, its support chaperon hsp90, its specific kinase Akt, p-Akt or post-translational modifications (PTMs) like OGlcNAc or phospho-tyrosine were unchanged in PAH relative to controls. Additionally there was uniform expression of Hbα/β and Mb in PASMCs or PAECs in PAH or controls and these globins can effectively scavenge the eNOS generated NO, as there was evidence of strong eNOS-Hb/Mb interactions. Our studies suggest that factors such as globin NO scavenging along with vascular remodeling in PAH can cause hampered vasodilation which in the face of poor NO levels as occurs in PAH are additional impediments for effective vasodilation. However importantly our studies suggests that future therapies can use low doses of NO along with sGC stimulators as a potential drug for PAH subjects.

Think Tank 2: How Do We Precisely Define the "High Risk Bladder" and What Are the Interrelationships Between Inflammation, Blood Flow, Fibrosis, and Loss of Bladder Compliance?

Defining "high-risk bladder" or "high-pressure bladder" involves recognizing the potential for an unsafe lower urinary tract, where dysfunction in storage and micturition can threaten upper urinary tract health, leading to unfavorable outcomes like dialysis, recurrent infections, systemic impact, or mortality. ICI-RS was held in Bristol in June 2024, and Think Tank 2 aimed to define research priorities including identifying clinical predictors and developing prevention and monitoring strategies. Risk factors encompass both congenital and neurogenic lower urinary tract dysfunction, bladder outlet obstruction, vascular diseases, and inflammatory disorders, but a validated stratification risk is lacking. Reduced compliance and detrusor overactivity lead to high filling pressures and raised detrusor leak point pressure, playing urodynamic studies a crucial role in risk assessment, though further research is needed for different neurogenic populations. Congenital conditions such as spina bifida, posterior urethral valves, and bladder exstrophy also contribute to a high-risk bladder through fibrosis and reduced compliance. Inflammation and ischemia are key factors, with inflammation leading to fibrosis and impaired bladder storage and voiding function. Novel treatments, including sGC activators, PDE5 inhibitors, and regenerative therapies like stem cell injections and extracorporeal shock wave treatment, show promise in mitigating fibrosis and improving bladder compliance. Identifying and validating clinical risk stratification models, precise biomarkers and therapeutic windows remains essential for effective management and reversal of bladder fibrosis and dysfunction.

Control of nerve-mediated and urothelial ATP release by a protein kinase G-dependent pathway in the mouse bladder

Aim:ATP signalling is involved in urinary bladder motor and sensory pathways, including stimulation-mediated release from parasympathetic varicosities to detrusor muscle and from urothelial cells when mechanically stressed. Both modalities are present in humans and other mammals but are especially prominent in overactive bladder syndromes. There is therefore an unmet need to understand how to regulate such release. This study tested the hypothesis that the nitric oxide (NO•)/ soluble guanylate cyclase (sGC)/ cyclic GMP/ protein kinase-G (PKG) pathway has a central role. Methods:In vitro nerve-mediated contractions and ATP/acetylcholine (ACh) release were measured from bladder wall strips, as was ATP release from urothelial cell suspensions subject to mechanical stresses. Enhanced spontaneous contractile activity was also measured in bladder wall preparations of spinal cord-injured mice. Interventions were designed to increase cellular cGMP levels (a cell-permeable cGMP analogue, a NO• donor, a phosphodiesterase inhibitor (PDEI), a sGC activator), or agents to reduce activity of pathway enzymes (sCG or PKG). Results:ATP-dependent contractions were reduced by the above interventions, as was ATP release; but ACh-dependent contractions and ACh release were unaffected. Spontaneous contractile activity was also reduced by the cGMP analogue and by a PDEI. ATP release from urothelial cell suspensions was also reduced by similar interventions. Conclusions:ATP release from efferent nerves and from urothelial cells were selectively reduced by upregulating the NO•/sGC/cGMP/PKG pathway. Translational aspects are discussed with respect to purinergic pathways and overactive bladder pathologies.

Comparison of sGC activator and sGC stimulator in 5/6 nephrectomized rats on high-salt-diet.

Soluble guanylate cyclase (sGC) stimulators and activators are known to enhance kidney function in various models of chronic kidney disease (CKD) by increasing cyclic guanosine monophosphate (cGMP). Their differential effects on CKD progression, particularly under conditions of oxidative stress, remain unexplored by direct comparative studies. We conducted a side-by-side comparison using 5/6 nephrectomized rats on a high salt diet (5/6Nx+HSD) to evaluate the efficacy of the sGC stimulator BAY 41-8543 and the sGC activator BAY 60-2770 in CKD progression. BAY 41-8543 (1mg/kg; twice daily) and BAY 60-2770 (1mg/kg; once daily) were administered by gavage for 11 weeks. The 5/6Nx+HSD model led to increased plasma creatinine, proteinuria, and blood pressure. Both BAY 41-8543 and BAY 60-2770 significantly reduced systolic and diastolic blood pressure to a similar extent but did not improve renal function parameters. Notably, BAY 60-2770 reduced renal fibrosis, including interstitial fibrosis and glomerulosclerosis, whereas BAY 41-8543 did not. These antifibrotic effects of BAY 60-2770 were independent of blood pressure reduction. Proteomic analysis revealed that BAY 60-2770 corrected the upregulation of 9 proteins associated with apoptosis and fibrosis, including Caspase-3, MKK6 (Mitogen-Activated Protein Kinase Kinase 6), Prdx5 (Peroxiredoxin-5), in the 5/6Nx+HSD group. In contrast, BAY 41-8543 had no significant impact on these proteins. sGC activators were more effective than sGC stimulators in reducing renal fibrosis in 5/6 nephrectomized rats on a high salt diet, and this effect was due to modulation of apoptosis-associated proteins beyond the control of blood pressure.

Stimulating Soluble Guanylyl Cyclase with the Clinical Agonist Riociguat Restrains the Development and Progression of Castration-Resistant Prostate Cancer.

Castration-resistant prostate cancer (CRPC) is incurable and fatal, making prostate cancer the second-leading cancer-related cause of death for American men. CRPC results from therapeutic resistance to standard-of-care androgen deprivation (AD) treatments, through incompletely understood molecular mechanisms, and lacks durable therapeutic options. Here, we identified enhanced soluble guanylyl cyclase (sGC) signaling as a mechanism that restrains CRPC initiation and growth. Patients with aggressive, fatal CRPC exhibited significantly lower serum levels of the sGC catalytic product cyclic GMP (cGMP) compared to their castration-sensitive stage. In emergent castration-resistant cells isolated from castration-sensitive prostate cancer (CSPC) populations, the obligate sGC heterodimer was repressed via methylation of its beta subunit. Genetically abrogating sGC complex formation in CSPC cells promoted evasion of AD-induced senescence and concomitant castration-resistant tumor growth. In established castration-resistant cells, the sGC complex was present but in a reversibly oxidized and inactive state. Subjecting CRPC cells to AD regenerated the functional complex, and co-treatment with riociguat, an FDA-approved sGC agonist, evoked redox stress-induced apoptosis. Riociguat decreased castration-resistant tumor growth and increased apoptotic markers, with elevated cGMP levels correlating significantly with lower tumor burden. Riociguat treatment reorganized tumor vasculature and eliminated hypoxic tumor niches, decreasing CD44+ tumor progenitor cells and increasing the radiosensitivity of castration-resistant tumors. Thus, this study showed that enhancing sGC activity can inhibit CRPC emergence and progression through tumor cell-intrinsic and extrinsic effects. Riociguat can be repurposed to overcome CRPC, with noninvasive monitoring of cGMP levels as a marker for on-target efficacy.

Sciatic nerve stimulation alleviates neuropathic pain and associated neuroinflammation in the dorsal root ganglia in a rodent model

BackgroundSatellite glial cells (SGCs) in the dorsal root ganglia (DRG) play a pivotal role in the formation of neuropathic pain (NP). Sciatic nerve stimulation (SNS) neuromodulation was reported to alleviate NP and reduce neuroinflammation. However, the mechanisms underlying SNS in the DRG remain unclear. This study aimed to elucidate the mechanism of electric stimulation in reducing NP, focusing on the DRG.MethodsL5 nerve root ligation (NRL) NP rat model was studied. Ipsilateral SNS performed 1 day after NRL. Behavioral tests were performed to assess pain phenotypes. NanoString Ncounter technology was used to explore the differentially expressed genes and cellular pathways. Activated SGCs were characterized in vivo and in vitro. The histochemical alterations of SGCs, macrophages, and neurons in DRG were examined in vivo on post-injury day 8.ResultsNRL induced NP behaviors including decreased pain threshold and latency on von Frey and Hargreaves tests. We found that following nerve injury, SGCs were hyperactivated, neurotoxic and had increased expression of NP-related ion channels including TRPA1, Cx43, and SGC-neuron gap junctions. Mechanistically, nerve injury induced reciprocal activation of SGCs and M1 macrophages via cytokines including IL-6, CCL3, and TNF-α mediated by the HIF-1α-NF-κB pathways. SNS suppressed SGC hyperactivation, reduced the expression of NP-related ion channels, and induced M2 macrophage polarization, thereby alleviating NP and associated neuroinflammation in the DRG.ConclusionsNRL induced hyperactivation of SGCs, which had increased expression of NP-related ion channels. Reciprocal activation of SGCs and M1 macrophages surrounding the primary sensory neurons was mediated by the HIF-1α and NF-κB pathways. SNS suppressed SGC hyperactivation and skewed M1 macrophage towards M2. Our findings establish SGC activation as a crucial pathomechanism in the gliopathic alterations in NP, which can be modulated by SNS neuromodulation.

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.

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.

New Therapeutics for Heart Failure Worsening: Focus on Vericiguat.

Heart failure (HF) is a syndrome characterized by signs and symptoms resulting from structural or functional cardiac abnormalities, confirmed by elevated natriuretic peptides or evidence of congestion. HF patients are classified according to left ventricular ejection fraction (LVEF). Worsening HF (WHF) is associated with increased short- and long-term mortality, re-hospitalization, and healthcare costs. The standard treatment of HF includes angiotensin-converting enzyme inhibitors, angiotensin receptor-neprilysin inhibitors, mineralocorticoid-receptor antagonists, beta-blockers, and sodium-glucose-co-transporter 2 inhibitors. To manage systolic HF by reducing mortality and hospitalizations in patients experiencing WHF, treatment with vericiguat, a direct stimulator of soluble guanylate cyclase (sGC), is indicated. This drug acts by stimulating sGC enzymes, part of the nitric oxide (NO)-sGC-cyclic guanosine monophosphate (cGMP) signaling pathway, regulating the cardiovascular system by catalyzing cGMP synthesis in response to NO. cGMP acts as a second messenger, triggering various cellular effects. Deficiencies in cGMP production, often due to low NO availability, are implicated in cardiovascular diseases. Vericiguat stimulates sGC directly, bypassing the need for a functional NO-sGC-cGMP axis, thus preventing myocardial and vascular dysfunction associated with decreased sGC activity in heart failure. Approved by the FDA in 2021, vericiguat administration should be considered, in addition to the four pillars of reduced EF (HFrEF) therapy, in symptomatic patients with LVEF < 45% following a worsening event. Cardiac rehabilitation represents an ideal setting where there is more time to implement therapy with vericiguat and incorporate a greater number of medications for the management of these patients. This review covers vericiguat's metabolism, molecular mechanisms, and drug-drug interactions.

Abstract 1100: Soluble Guanylate Cyclase Activators As Potential Novel Pad Therapeutics

Introduction: Peripheral arterial disease (PAD) is major cause of limb loss in the United States with limited treatment modalities. Understanding the genetic etiology of PAD may provide rationale for novel therapeutic strategies. Here, we report a novel association between PAD and a likely endothelial cell specific cis-regulatory element of Nitric Oxide Synthase 3 ( NOS3 ). We hypothesize that targeting of the nitric oxide (NO)-cyclic GMP (cGMP) axis with Riociguat, an FDA-approved soluble guanylate cyclase (sGC) activator, will improve perfusion and exercise capacity in a murine PAD model. Methods: We meta-analyzed genetic associations with PAD using summary statistics from European participants in the UK Biobank (UKB), Copenhagen Hospital Biobank - Cardiovascular Disease Cohort and Danish Blood Donor Study (CHB-CVDC/DBDS), and the Million Veteran Program (MVP). Human NOS3 deficiency was modeled using Enos +/- mice with C57/B6 controls. We induced hindlimb ischemia (HLI) via double ligation of the femoral artery as described previously. Riociguat (3mg/kg/day) was administered 4 days prior and 28 days after HLI induction. We measured exercise capacity by placing animals on a treadmill with increasing speed and incline. We measured hindlimb perfusion using laser doppler perfusion imaging and assessed relative perfusion of the ischemic limb to the contralateral control limb. Results: We identified novel association of the minor allele of rs3918226, which lies within the promoter of NOS3, with PAD (OR: 1.06; 95% CI: 1.04-1.09; P = 1.3 x 10-9). Induction of hindlimb ischemia in Enos +/- animals resulted in impaired exercise capacity compared to wild-type controls. In Riociguat-treated Enos +/- mice, we observed a significant increase in distance traveled during exercise testing at 14 days which was sustained for the duration of the study period (276 vs 156 meters, p&lt;0.05). We did not find a significant improvement in hindlimb perfusion over the course of the study period. Conclusion: Here, we identify a novel genetic association with PAD and demonstrate that in a genetic model of PAD we can improve exercise capacity by targeting the NO-cGMP axis with Riociguat. Future studies will assess the clinical utility of sGC activators like Riociguat in humans.

Heme oxidation of NO-receptor soluble guanylyl cyclase is an important contributor to cerebrovascular and cognitive dysfunctions

Introduction: Decreased cerebral blood flow (CBF) is one of the major hemodynamic alterations leading to neurodegeneration and age-related cognitive decline. Nitric Oxide (NO)-dependent vasomotor reactivity is central in regulating cerebrovascular hemodynamics and adequate brain blood perfusion. NO receptor Soluble Guanylyl Cyclase (sGC) is the primary mediator of NO-dependent vasodilation. Oxidative stress, often persisting in diseased vasculature, renders sGC insensitive to NO and impairs the NO signaling. The objective of our study was to investigate the role of sGC oxidation in regulation CBF and brain function. Hypothesis: Oxidative stress disrupts NO/cGMP signaling in brain by decreasing sGC activity via oxidation of sGC heme. Approach: To assess causal effect of sGC oxidation on NO signaling function we administered ODQ, a sGC-specific heme oxidizing agent, to simulate long-term effect of sGC oxidation in cerebral vasculature. Two groups of young wild-type male and female mice (4 months old C57BL/6) were treated intraperitoneally (IP) twice a week for one month with ODQ (20 mg/kg) or a solvent as control. Changes in cerebrovascular reactivity and memory function were assessed and compared in treated and control groups. Using a non-invasive pulsed Doppler ultrasound-based system we assessed the changes in blood flow velocity (PVF, % of baseline) in the mouse middle cerebral artery (MCA) of male and female groups. MCA vasodilation was induced by bolus IP injection of NO-donor sodium nitroprusside (SNP) or BAY 58-2667, an allosteric NO-independent sGC activator. Memory function was assessed by the Novel Object Recognition Task (NORT, RI, recognition index) in all experimental groups. Western blotting and densitometry assessed the expression of major sGC subunits (α1, α2 and β1) in cleared brain lysates from ODQ-treated and control groups. Results: We observed a significantly blunted vasodilative response to SNP (1 mg/kg) in ODQ-treated mice vs controls of both genders (PVF, max response at 2 min post-injection, males 73.9 ± 10.4% (n=7/7) vs 58.5 ± 8.6 %, p=0.01; females (n=6/6) 77.4 ± 10.6 % vs 61.9 ± 5.4 %, p=0.01). Changes in response to NO-donor were more pronounced in males than females. The difference in BAY 58-2667 response between ODQ-treated and control groups was not statistically significant. ODQ significantly reduced the long-term memory in males but not female, according to NORT (RI, males (n=7/7) 0.58 ± 0.13 vs 0.69 ± 0.05; p=0.01; females (n=6/6) ODQ 0.59 ± 0.17 vs 0.73 ± 0.1, p=0.13). No statistically significant difference in expression of sGC subunits between control and ODQ-treated (n= 4/4) of male and female groups was determined. Conclusions: ODQ treatment significantly impairs vasodilation response to NO-donor but not to NO-independent sGC activator in mice MCA. ODQ treatment negatively affects long-term memory function in male, but not female mice. ODQ treatment does not significantly affect the expression of sGC subunits. Together our data suggest that the oxidation of sGC heme moiety impairs the regulation of cerebral blood flow of both genders and impairs long-term memory function gender-specifically in young mice. This research was supported by National Institute of Health grants RAG071999A (Iraida Sharina), HL139838, and American Heart Association 23TPA1070711 (Emil Martin). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Regional variations in allergen-induced airway inflammation correspond to changes in soluble guanylyl cyclase heme and expression of heme oxygenase-1.

Asthma is characterized by airway remodeling and hyperreactivity. Our earlier studies determined that the nitric oxide (NO)-soluble guanylyl cyclase (sGC)-cGMP pathway plays a significant role in human lung bronchodilation. However, this bronchodilation is dysfunctional in asthma due to high NO levels, which cause sGC to become heme-free and desensitized to its natural activator, NO. In order to determine how asthma impacts the various lung segments/lobes, we mapped the inflammatory regions of lungs to determine whether such regions coincided with molecular signatures of sGC dysfunction. We demonstrate using murine models of asthma (OVA and CFA/HDM) that the inflamed segments of these murine lungs can be tracked by upregulated expression of HO1 and these regions in turn overlap with regions of heme-free sGC as evidenced by a decreased sGC-α1β1 heterodimer and an increased response to heme-independent sGC activator, BAY 60-2770, relative to naïve uninflamed regions. We also find that NO generated from iNOS upregulation in the inflamed segments has a higher impact on developing heme-free sGC as increasing iNOS activity correlates linearly with elevated heme-independent sGC activation. This excess NO works by affecting the epithelial lung hemoglobin (Hb) to become heme-free in asthma, thereby causing the Hb to lose its NO scavenging function and exposing the underlying smooth muscle sGC to excess NO, which in turn becomes heme-free. Recognition of these specific lung segments enhances our understanding of the inflamed lungs in asthma with the ultimate aim to evaluate potential therapies and suggest that regional and not global inflammation impacts lung function in asthma.