cGMP manipulation in cardiometabolic disease: chances and challenges

Vericiguat improves cardiac remodelling and function in rats with doxorubicin-induced cardiomyopathy

PURPOSE

Vericiguat, a soluble guanylate cyclase (sGC) stimulator, has been demonstrated effective in improving prognosis of patients with heart failure with reduced ejection fraction. However, there are limited data concerning the effect of vericiguat in patients with doxorubicin (DOX)-induced cardiomyopathy (DIC). In this study, we investigated the effects of vericiguat on cardiac structure and function in rats with DIC as well as their potential mechanisms of action.

METHODS

DIC rats were established by intraperitoneal injection of DOX (1 mg/kg) twice a week for 6 weeks, followed by intragastric administration of vericiguat 1 mg/kg/day or an equal volume of normal saline for 8 weeks. Cardiac histology and function, circulating levels of amino-terminal pro-B-type natriuretic peptide (NT-proBNP), nitric oxide (NO), and oxidative indices, as well as myocardial cyclic guanosine monophosphate (cGMP)-protein kinase G (PKG) signalling, oxidative and apoptosis-associated protein were measured.

RESULTS

Compared with the control group, rats treated with DOX exhibited significantly increased heart size, reduced systolic function and elevated plasma levels of NT-proBNP. Histological findings revealed myocardial cell atrophy, fibrosis and apoptosis. Vericiguat treatment effectively reversed DOX-induced cardiac remodelling and improved systolic function. Mechanistically, Vericiguat attenuated the inhibitory effects of DOX on the myocardial cGMP-PKG axis and nuclear factor erythroid 2-related factor 2 (Nrf2) protein, thereby alleviating oxidative stress and apoptosis.

CONCLUSIONS

Vericiguat improved cardiac remodelling and contractile function in rats with DIC through upregulation of cGMP-PKG signalling and inhibition of oxidative stress and myocardial apoptosis.

The role of compartmentalized β-AR/cAMP signaling in the regulation of lipolysis in white and brown adipocytes

White and brown adipocytes are central mediators of lipid metabolism and thermogenesis, respectively. Their function is tightly regulated by all three β-adrenergic receptor (β-AR) subtypes which are coupled to the production of the second messenger 3',5'-cyclic adenosine monophosphate (cAMP). While known for decades in other cell types, compartmentation of adipocyte β-AR/cAMP signaling by spatial organization of the pathway and by cAMP degrading phosphodiesterases (PDEs) as well as its role in the regulation of lipolysis is only beginning to emerge. Here, we provide a short overview of recent findings which shed light on compartmentalized signaling using live cell imaging of cAMP in adipocytes and discuss possible future directions of research which could open up new avenues for the treatment of metabolic disorders.

Acute Hemodynamic Effects and Tolerability of Phosphodiesterase-1 Inhibition With ITI-214 in Human Systolic Heart Failure

BACKGROUND

PDE1 (phosphodiesterase type 1) hydrolyzes cyclic adenosine and guanosine monophosphate. ITI-214 is a highly selective PDE1 inhibitor that induces arterial vasodilation and positive inotropy in larger mammals. Here, we assessed pharmacokinetics, hemodynamics, and tolerability of single-dose ITI-214 in humans with stable heart failure with reduced ejection fraction.

METHODS

Patients with heart failure with reduced ejection fraction were randomized 3:1 to 10, 30, or 90 mg ITI-214 single oral dose or placebo (n=9/group). Vital signs and electrocardiography were monitored predose to 5 hours postdose and transthoracic echoDoppler cardiography predose and 2-hours postdose.

RESULTS

Patient age averaged 54 years; 42% female, and 60% Black. Mean systolic blood pressure decreased 3 to 8 mm Hg (P<0.001) and heart rate increased 5 to 9 bpm (P≤0.001 for 10, 30 mg doses, RM-ANCOVA). After 4 hours, neither blood pressure or heart rate significantly differed among cohorts (supine or standing). ITI-214 increased mean left ventricular power index, a relatively load-insensitive inotropic index, by 0.143 Watts/mL²·10⁴ (P=0.03, a +41% rise; 5-71 CI) and cardiac output by 0.83 L/min (P=0.002, +31%, 13-49 CI) both at the 30 mg dose. Systemic vascular resistance declined with 30 mg (-564 dynes·s/cm-⁵, P<0.001) and 90 mg (-370, P=0.016). Diastolic changes were minimal, and no parameters were significantly altered with placebo. ITI-214 was well-tolerated. Five patients had mild-moderate hypotension or orthostatic hypotension recorded adverse events. There were no significant changes in arrhythmia outcome and no serious adverse events.

CONCLUSIONS

Single-dose ITI-214 is well-tolerated and confers inodilator effects in humans with heart failure with reduced ejection fraction. Further investigations of its therapeutic utility are warranted. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03387215.

Association Between Cardiac Natriuretic Peptides and Lipid Profile: a Systematic Review and Meta-Analysis

Cardiac natriuretic peptides (NPs) play a fundamental role in maintaining cardiovascular (CV) and renal homeostasis. Moreover, they also affect glucose and lipid metabolism. We performed a systematic review and meta-analysis of studies investigating the association of NPs with serum lipid profile. A PubMed and Scopus search (2005–2018) revealed 48 studies reporting the association between NPs and components of lipid profile [total cholesterol (TC), low-density lipoprotein cholesterol (LDLc), high-density lipoprotein cholesterol (HDLc) and triglycerides (TG)]. Despite high inconsistency across studies, NPs levels were inversely associated with TC [k = 32; pooled r = −0.09; I² = 90.26%], LDLc [k = 31; pooled r = −0.09; I² = 82.38%] and TG [k = 46; pooled r = −0.11; I² = 94.14%], while they were directly associated with HDLc [k = 41; pooled r = 0.06; I² = 87.94%]. The relationship with LDLc, HDLc and TG lost significance if only studies on special populations (works including subjects with relevant acute or chronic conditions that could have significantly affected the circulating levels of NPs or lipid profile) or low-quality studies were taken into account. The present study highlights an association between higher NP levels and a favorable lipid profile. This confirms and extends our understanding of the metabolic properties of cardiac NPs and their potential in CV prevention.