Cyclic Guanosine Monophosphate and Risk of Incident Heart Failure and Other Cardiovascular Events: the ARIC Study

Multinomial machine learning identifies independent biomarkers by integrated metabolic analysis of acute coronary syndrome

A multi-class classification model for acute coronary syndrome (ACS) remains to be constructed based on multi-fluid metabolomics. Major confounders may exert spurious effects on the relationship between metabolism and ACS. The study aims to identify an independent biomarker panel for the multiclassification of HC, UA, and AMI by integrating serum and urinary metabolomics. We performed a liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolomics study on 300 serum and urine samples from 44 patients with unstable angina (UA), 77 with acute myocardial infarction (AMI), and 29 healthy controls (HC). Multinomial machine learning approaches, including multinomial adaptive least absolute shrinkage and selection operator (LASSO) regression and random forest (RF), and assessment of the confounders were applied to integrate a multi-class classification biomarker panel for HC, UA and AMI. Different metabolic landscapes were portrayed during the transition from HC to UA and then to AMI. Glycerophospholipid metabolism and arginine biosynthesis were predominant during the progression from HC to UA and then to AMI. The multiclass metabolic diagnostic model (MDM) dependent on ACS, including 2-ketobutyric acid, LysoPC(18:2(9Z,12Z)), argininosuccinic acid, and cyclic GMP, demarcated HC, UA, and AMI, providing a C-index of 0.84 (HC vs. UA), 0.98 (HC vs. AMI), and 0.89 (UA vs. AMI). The diagnostic value of MDM largely derives from the contribution of 2-ketobutyric acid, and LysoPC(18:2(9Z,12Z)) in serum. Higher 2-ketobutyric acid and cyclic GMP levels were positively correlated with ACS risk and atherosclerosis plaque burden, while LysoPC(18:2(9Z,12Z)) and argininosuccinic acid showed the reverse relationship. An independent multiclass biomarker panel for HC, UA, and AMI was constructed using the multinomial machine learning methods based on serum and urinary metabolite signatures.

The evolution of small molecule enzyme activators

There is a myriad of enzymes within the body responsible for maintaining homeostasis by providing the means to convert substrates to products as and when required. Physiological enzymes are tightly controlled by many signaling pathways and their products subsequently control other pathways. Traditionally, most drug discovery efforts focus on identifying enzyme inhibitors, due to upregulation being prevalent in many diseases and the existence of endogenous substrates that can be modified to afford inhibitor compounds. As enzyme downregulation and reduction of endogenous activators are observed in multiple diseases, the identification of small molecules with the ability to activate enzymes has recently entered the medicinal chemistry toolbox to afford chemical probes and potential therapeutics as an alternative means to intervene in diseases. In this review we highlight the progress made in the identification and advancement of non-kinase enzyme activators and their potential in treating various disease states.

Evidence for Angiotensin II as a Naturally Existing Suppressor for the Guanylyl Cyclase A Receptor and Cyclic GMP Generation

The natriuretic peptide system (NPS) and renin-angiotensin-aldosterone system (RAAS) function oppositely at multiple levels. While it has long been suspected that angiotensin II (ANGII) may directly suppress NPS activity, no clear evidence to date supports this notion. This study was designed to systematically investigate ANGII-NPS interaction in humans, in vivo, and in vitro. Circulating atrial, b-type, and c-type natriuretic peptides (ANP, BNP, CNP), cyclic guanosine monophosphate (cGMP), and ANGII were simultaneously investigated in 128 human subjects. Prompted hypothesis was validated in vivo to determine the influence of ANGII on ANP actions. The underlying mechanisms were further explored via in vitro approaches. In humans, ANGII demonstrated an inverse relationship with ANP, BNP, and cGMP. In regression models predicting cGMP, adding ANGII levels and the interaction term between ANGII and natriuretic peptides increased the predictive accuracy of the base models constructed with either ANP or BNP, but not CNP. Importantly, stratified correlation analysis further revealed a positive association between cGMP and ANP or BNP only in subjects with low, but not high, ANGII levels. In rats, co-infusion of ANGII even at a physiological dose attenuated cGMP generation mediated by ANP infusion. In vitro, we found the suppressive effect of ANGII on ANP-stimulated cGMP requires the presence of ANGII type-1 (AT1) receptor and mechanistically involves protein kinase C (PKC), as this suppression can be substantially rescued by either valsartan (AT1 blocker) or Go6983 (PKC inhibitor). Using surface plasmon resonance (SPR), we showed ANGII has low binding affinity to the guanylyl cyclase A (GC-A) receptor compared to ANP or BNP. Our study reveals ANGII is a natural suppressor for the cGMP-generating action of GC-A via AT1/PKC dependent manner and highlights the importance of dual-targeting RAAS and NPS in maximizing beneficial properties of natriuretic peptides in cardiovascular protection.

EVIDENCE FOR ANGIOTENSIN II AS A NATURALLY EXISTING SUPPRESSOR FOR THE NATRIURETIC PEPTIDE SYSTEM

Background

Natriuretic peptide system (NPS) and renin angiotensin aldosterone system (RAAS) function oppositely at multiple levels. While it has long been suspected that angiotensin II (ANGII) may directly suppress NPS activity, no clear evidence to date support this notion.

Objectives

This study was designed to systematically investigate ANGII-NPS interaction in humans, in vivo, and in vitro for translational insights.

Methods

Circulating atrial, b-type, and c-type natriuretic peptides (ANP, BNP, CNP), cyclic guanosine monophosphate (cGMP), and ANGII were simultaneously investigated in 128 human subjects. Prompted hypothesis was validated in rat model to determine influence of ANGII on ANP actions. Multiple engineered HEK293 cells and surface plasmon resonance (SPR) technology were leveraged for mechanistic exploration.

Results

In humans, ANGII showed inverse relationship with ANP, BNP, and cGMP. In regression models predicting cGMP, adding ANGII levels and interaction term between ANGII and natriuretic peptide increased predicting accuracy of base models constructed with either ANP or BNP, but not CNP. Importantly, stratified correlation analysis further revealed positive association between cGMP with ANP or BNP only in subjects with low, but not high, ANGII levels. In rats, co-infusion of ANGII even at physiological dose attenuated blood pressure reduction and cGMP generation triggered by ANP infusion. In vitro, we showed that the suppression effect of ANGII on ANP-stimulated cGMP requires the presence of ANGII type-1 (AT1) receptor and mechanistically involves protein kinase C (PKC), which can be substantially rescued by either valsartan (AT1 blocker) or Go6983 (PKC inhibitor). Using SPR, we showed ANGII has low affinity for particulate guanylyl cyclase A (GC-A) receptor binding compared to ANP or BNP.

Conclusions

Our study reveals ANGII as a natural suppressor for cGMP-generating action of GC-A via AT1/PKC dependent manner and highlights importance of dual-targeting RAAS and NPS in maximizing beneficial properties of natriuretic peptides in cardiovascular disease.

Emerging Biomarkers for Predicting Clinical Outcomes in Patients with Heart Disease

Cardiovascular disease is most frequently caused by the development and progression of atherosclerosis. When coronary arteries are afflicted, and the stenoses caused by atherosclerotic plaques are severe enough, the metabolic supply-and-offer balance is disturbed, leading to myocardial ischemia. If atherosclerotic plaques become unstable and local thrombosis develops, a myocardial infarction occurs. Sometimes, myocardial ischemia and infarction may result in significant and irreversible heart failure. To prevent severe complications, such as acute coronary syndromes and ischemia-related heart failure, extensive efforts have been made for developing biomarkers that would help identify patients at increased risk for cardiovascular events. In this two-part study, we attempted to provide a review of existing knowledge of blood biomarkers that may be used in this setting. The first part of this work was dedicated to conventional biomarkers, which are already used in clinical practice. In the second part, here presented, we discuss emerging biomarkers which have not yet become mainstream.

Visualising and understanding cGMP signals in the cardiovascular system

cGMP is an important signalling molecule in humans. Fluorescent cGMP biosensors have emerged as powerful tools for the sensitive analysis of cGMP pathways at the single-cell level. Here, we briefly outline cGMP's multifaceted role in (patho)physiology and pharmacotherapy. Then we summarise what new insights cGMP imaging has provided into endogenous cGMP signalling and drug action, with a focus on the cardiovascular system. Indeed, the use of cGMP biosensors has led to several conceptual advances, such as the discovery of local, intercellular and mechanosensitive cGMP signals. Importantly, single-cell imaging can provide valuable information about the heterogeneity of cGMP signals within and between individual cells of an isolated cell population or tissue. We also discuss current challenges and future directions of cGMP imaging, such as the direct visualisation of cGMP microdomains, simultaneous monitoring of cGMP and other signalling molecules and, ultimately, cGMP imaging in tissues and animals under close-to-native conditions.

CUTie2: The Attack of the Cyclic Nucleotide Sensor Clones

The detection of small molecules in living cells using genetically encoded FRET sensors has revolutionized our understanding of signaling pathways at the sub-cellular level. However, engineering fluorescent proteins and specific binding domains to create new sensors remains challenging because of the difficulties associated with the large size of the polypeptides involved, and their intrinsically huge conformational variability. Indeed, FRET sensors’ design still relies on vague structural notions, and trial and error combinations of linkers and protein modules. We recently designed a FRET sensor for the second messenger cAMP named CUTie (Cyclic nucleotide Universal Tag for imaging experiments), which granted sub-micrometer resolution in living cells. Here we apply a combination of sequence/structure analysis to produce a new-generation FRET sensor for the second messenger cGMP based on Protein kinase G I (PKGI), which we named CUTie2. Coarse-grained molecular dynamics simulations achieved an exhaustive sampling of the relevant spatio-temporal coordinates providing a quasi-quantitative prediction of the FRET efficiency, as confirmed by in vitro experiments. Moreover, biochemical characterization showed that the cGMP binding module maintains virtually the same affinity and selectivity for its ligand thant the full-length protein. The computational approach proposed here is easily generalizable to other allosteric protein modules, providing a cost effective-strategy for the custom design of FRET sensors.

Cyclic guanosine monophosphate and 10-year change in left ventricular mass: the Multi-Ethnic Study of Atherosclerosis (MESA)

Purpose: Cyclic guanosine monophosphate (cGMP) is a second messenger for natriuretic peptide (NP) and nitric oxide pathways; its enhancement a target for heart failure and cardiovascular disease (CVD). We evaluated whether plasma cGMP was associated with change in left ventricular mass (LVM) among individuals free of CVD and if this differed by sex.Methods and Results: In 611 men and 612 women aged 45-84 years with plasma cGMP measured at baseline and cardiac MRI performed at baseline and 10 years later, we tested associations of cGMP [log-transformed, per 1 SD increment] with LVM, adjusting for CVD risk factors and N-terminal pro-B-type-NP (NT-proBNP). Participants had mean (SD) age of 63.1(8.5) years and cGMP 4.8(2.6) pmol/mL. Cross-sectionally, higher cGMP was associated with lesser LVM, non-lin- early. In contrast, longitudinally, higher cGMP was associated with increase in LVM [1.70g (0.61, 2.78)] over 10 years. Higher cGMP was associated with greater LVM change in men [2.68g (1.57, 3.79)] but not women [0.24g ((-0.92, 1.39); p-interaction < 0.001].Conclusion: In conclusion, in a community-based cohort, higher cGMP levels were associated with increase in LVM over 10 years independent of CVD risk factors and NT-proBNP in men, perhaps reflecting compensatory changes. Further studies are needed to understand mechanistic roles of cGMP in LV remodelling and associated sex differences.

Go Red for Women Strategically Focused Research Network: Summary of Findings and Network Outcomes

The Go Red for Women movement was initiated by the American Heart Association (AHA) in the early 2000s to raise awareness concerning cardiovascular disease (CVD) risk in women. In 2016, the AHA funded 5 research centers across the United States to advance our knowledge of the risks and presentation of CVD that are specific to women. This report highlights the findings of the centers, showing how insufficient sleep, sedentariness, and pregnancy-related complications may increase CVD risk in women, as well as presentation and factors associated with myocardial infarction with nonobstructive coronary arteries and heart failure with preserved ejection fraction in women. These projects were augmented by collaborative ancillary studies assessing the relationships between various lifestyle behaviors, including nightly fasting duration, mindfulness, and behavioral and anthropometric risk factors and CVD risk, as well as metabolomic profiling of heart failure with preserved ejection fraction in women. The Go Red for Women Strategically Focused Research Network enhanced the evidence base related to heart disease in women, promoting awareness of the female-specific factors that influence CVD.

CRD-733, a Novel PDE9 (Phosphodiesterase 9) Inhibitor, Reverses Pressure Overload-Induced Heart Failure

BACKGROUND

Augmentation of NP (natriuretic peptide) receptor and cyclic guanosine monophosphate (cGMP) signaling has emerged as a therapeutic strategy in heart failure (HF). cGMP-specific PDE9 (phosphodiesterase 9) inhibition increases cGMP signaling and attenuates stress-induced hypertrophic heart disease in preclinical studies. A novel cGMP-specific PDE9 inhibitor, CRD-733, is currently being advanced in human clinical studies. Here, we explore the effects of chronic PDE9 inhibition with CRD-733 in the mouse transverse aortic constriction pressure overload HF model.

METHODS

Adult male C57BL/6J mice were subjected to transverse aortic constriction and developed significant left ventricular (LV) hypertrophy after 7 days (P<0.001). Mice then received daily treatment with CRD-733 (600 mg/kg per day; n=10) or vehicle (n=17), alongside sham-operated controls (n=10).

RESULTS

CRD-733 treatment reversed existing LV hypertrophy compared with vehicle (P<0.001), significantly improved LV ejection fraction (P=0.009), and attenuated left atrial dilation (P<0.001), as assessed by serial echocardiography. CRD-733 prevented elevations in LV end diastolic pressures (P=0.037) compared with vehicle, while lung weights, a surrogate for pulmonary edema, were reduced to sham levels. Chronic CRD-733 treatment increased plasma cGMP levels compared with vehicle (P<0.001), alongside increased phosphorylation of Ser²⁷³ of cardiac myosin binding protein-C, a cGMP-dependent protein kinase I phosphorylation site.

CONCLUSIONS

The PDE9 inhibitor, CRD-733, improves key hallmarks of HF including LV hypertrophy, LV dysfunction, left atrial dilation, and pulmonary edema after pressure overload in the mouse transverse aortic constriction HF model. Additionally, elevated plasma cGMP may be used as a biomarker of target engagement. These findings support future investigation into the therapeutic potential of CRD-733 in human HF.

Cyclic Guanosine Monophosphate and Risk of Incident Heart Failure and Other Cardiovascular Events: the ARIC Study

Background

Cyclic guanosine monophosphate (cGMP) is a second messenger regulated through natriuretic peptide and nitric oxide pathways. Stimulation of cGMP signaling is a potential therapeutic strategy for heart failure with preserved ejection fraction (HFpEF) and atherosclerotic cardiovascular disease (ASCVD). We hypothesized that plasma cGMP levels would be associated with lower risk for incident HFpEF, any HF, ASCVD, and coronary heart disease (CHD).

Methods and Results

We conducted a case–cohort analysis nested in the ARIC (Atherosclerosis Risk in Communities) study. Plasma cGMP was measured in 875 participants at visit 4 (1996–1998), with oversampling of incident HFpEF cases. We used Cox proportional hazard models to assess associations of cGMP with incident HFpEF, HF, ASCVD (CHD+stroke), and CHD. The mean (SD) age was 62.4 (5.6) years and median (interquartile interval) cGMP was 3.4 pmol/mL (2.4–4.6). During a median follow‐up of 9.9 years, there were 283 incident cases of HFpEF, 329 any HF, 151 ASCVD, and 125 CHD. In models adjusted for CVD risk factors, the hazard ratios (95% CI) associated with the highest cGMP tertile compared with lowest for HFpEF, HF, ASCVD, and CHD were 1.88 (1.17–3.02), 2.18 (1.18–4.06), 2.84 (1.44–5.60), and 2.43 (1.19–5.00), respectively. In models further adjusted for N‐terminal‐proB‐type natriuretic peptide, associations were attenuated for HFpEF and HF but remained statistically significant for ASCVD (2.56 [1.26–5.20]) and CHD (2.25 [1.07–4.71]).

Conclusions

Contrary to our hypothesis, higher cGMP levels were associated with incident CVD in a community‐based cohort. The associations of cGMP with HF or HFpEF may be explained by N‐terminal‐proB‐type natriuretic peptide, but not for ASCVD and CHD.