Burnett, John C.

Introduction: Aldosterone (Aldo) increases sodium and water reabsorption and mediates inflammatory processes. Its relationship to co-morbidities has not been well defined in the general population. Hypothesis: We addressed the hypothesis that plasma aldosterone concentration (PAC) is associated with metabolic and cardiorenal diseases in the general community. Methods: We determined PAC in a general community-based cohort from Olmsted County, MN (n=1,674), and defined correlations with cardiorenal, metabolic diseases and myocardial function and structure. Results: PAC was detected in all subjects and ranged from 2.5 to 91 ng/dl (mean value 6.7 ng/dl, +/- SD 6.6). Multivariate analysis adjusted for age, gender, BMI, ANP and BNP showed highly significant correlations between PAC and hypertension (HTN) (p<.0001, OR=2.28, CI:1.91-2.71), atrial fibrillation (p<.01), chronic kidney disease (CKD) (p<.0001, OR=1.64, CI:1.33-2.02), central obesity (p<.0001, OR=1.61, CI:1.27-2.05), hypertriglyceridemia (p<.003), prevalence of metabolic syndrome (MetS) (p<.0007, OR=1.40, CI=1.15-1.71), obesity (p<.0001, OR=1.48, CI:1.27-1.73), and concentric left ventricular hypertrophy (cLVH) (p=.01). Recognizing that ANP and BNP are known inhibitors of Aldo, we defined the relationship between these cardiac hormones (NTpro-ANP and NT-proBNP) and PAC and observed highly significant inverse relationships with NTpro-ANP (p=0.0009), NTpro-BNP (p=0.0003) in the general population. Conclusions: In conclusion, in the general community, PAC is strongly correlated with renal, metabolic and cardiovascular diseases as well as cardiac remodeling. Specifically, increasing PAC is strongly associated with HTN, CKD, obesity, MetS, cLVH, and lower levels of natriuretic peptides. Our data suggest a key role of Aldo as a possible biomarker and/or mediator of human cardiorenal and metabolic diseases even in the general adult population, prior to overt disease. This study also supports a possible counter regulatory relationship between cardiac natriuretic peptides and PAC. Further studies are warranted to evaluate possible therapeutic interventions targeting Aldo as a strategy to delay disease progression.

Introduction: Cardiorenal fibrotic remodeling (CFR), often in the setting of heart failure (HF) and kidney disease (CKD), is a major cause for increased risk in mortality, for which there are no effective drugs. C-type natriuretic peptide (CNP) is a 22 amino acid (AA) ligand for the particulate guanylyl cyclase receptor-B (GC-B) and exerts anti-fibrotic actions, with little effect on blood pressure (BP) or renal function, via its second messenger cGMP. To overcome CNP’s limited efficacy with its short half-life, we designed 2 novel CNP-based peptides (C53 and CU32). C53 consists of CNP plus a 31 AA N-terminus extension, while CU32 is the CNP ring fused with the N- and C-termini of urodilatin (GC-A agonist). Here we investigated the cGMP generating actions of C53 and CU32, with the goal of advancing novel GC-B/cGMP therapeutics for CFR. Hypotheses: We hypothesized that C53 and CU32 would have cGMP activating actions in vivo, however only C53 would generate cGMP production selectively via GC-B in vitro. We also hypothesize that the addition of the C-termini to CU32 would form a non-selective GC-B/cGMP agonist with renal and BP lowering actions. Methods: HEK293 cells expressing human GC-B or -A and human fibroblasts (hFs), where GC-B is abundant, were stimulated with C53 or CU32 (10-8M) for 10 min. Two groups of normal rats (n=8) received a 75 min equimolar IV infusion of C53 or CU32. Change in mean arterial pressure (ΔMAP), sodium (Na) excretion and plasma and urinary cGMP were assessed. *p<0.05. Results: C53 and CU32 activated cGMP in GC-B cells (C53: 75±9, CU32: 24±2 pmol/well*), while only CU32 activated cGMP in GC-A cells (C53: 0±0, CU32: 50±3 pmol/well*). In hFs, both C53 and CU32 generated cGMP. In vivo, plasma cGMP (C53: 91±4, CU32: 94±6 pmol/ml) and urinary cGMP excretion (C53: 177±28, CU32: 227±28 pmol/min) were similar with both peptides. Yet, CU32 induced a greater reduction in ΔMAP (C53: -7±1, CU32: -16±3 mmHg*) and increased Na excretion (C53: 1.4±0.2, CU32: 2.4±0.2 uEq/m*) compared to C53. Conclusions: We report the engineering of a selective (C53) and non-selective (CU32) GC-B agonist that has favorable cGMP generating action in hFs and in vivo. Thus, C53 and CU32 may represent novel GC-B therapeutics that could be tailored to specific phases of HF or CKD to prevent CFR.

Introduction: As importantly underscored by the SPRINT Trial, innovative blood pressure (BP) lowering and multiorgan protective drugs are needed for treating hypertension (HTN). We engineered a Mayo Clinic designer atrial natriuretic peptide (ANP)-based drug, ZD100, which possesses a unique 12 amino acid (AA) carboxy-terminus (CT) extension while maintaining the N-terminus (NT) of ANP. ZD100 is more potent than ANP in reducing BP, inducing natriuresis and inhibiting aldosterone via pGC-A and its second messenger cGMP. To date, the in vivo actions of ZD100 in a model of essential HTN are undefined. Further, in attempt to enhance and/or minimize pGC-A activation, the importance of specific AAs in the CT and NT of ZD100 is unknown and is critical to define. Hypothesis: We hypothesize that ZD100 is a potent anti-HTN drug activating pGC-A/cGMP system and that specific AA variations in the CT and/or NT of ZD100 will modify the ability of activating pGC-A. Methods: Spontaneously hypertensive rats (SHRs) received intravenous (IV) ZD100 or vehicle and BP, plasma and urinary cGMP and the natriuretic effects were determined. We then engineered 15 strategic ZD100 variants (Vs) consisting of mutated peptides in the CT or NT or both. We stimulated HEK293 cells overexpressing pGC-A with ZD100 and the 15 Vs (10-8 M) and measured intracellular cGMP generation. Results: In SHRs, acute IV ZD100 reduced BP, increased plasma and urinary cGMP generation and induced natriuresis demonstrating efficacy in HTN. In vitro, we found two more potent pGC-A activators (+100% cGMP activation) only among the CT-only mutated ZD100 Vs. Importantly, key mutations of either the CT or NT resulted in 6 loss-of-function Vs identifying importance of peptide-receptor dependency. Conclusions: We demonstrate for the first time in a genetic model of HTN that ZD100 reduces BP, activates systemic and renal pGC-A/cGMP and induces natriuresis. Enhanced or reduced pGC-A activation with targeted AA mutations in the CT and NT of ZD100 provides key structure function insights into ZD100 which may lead to next generation ZD100 therapeutic peptides. These findings support ZD100 as a novel peptide therapeutic strategy for HTN and will help guide the selection of best-in-class ZD100 analogues.

Background: The primary role of natriuretic peptide receptor 3 (NPR3) is clearance of natriuretic peptides. Genetic variation in NPR3 has been associated with blood pressure regulation and obesity. Despite its importance, variation in NPR3 characterizing coding single nucleotide polymorphisms (SNPs) has not been addressed by resequencing the gene. Objective: We set out to identify and functionally characterize common variation in NPR3 in 3 ethnic groups. DNA samples from such subjects are studied because common genetic variation needs to be defined initially in “normal” individuals prior to studying drug effect and response. Also, rare variants identified by sequencing are enriched in complex disease traits. Methods and Results: DNA samples from 96 European-American, 96 African-American, and 96 Han Chinese-American healthy subjects were used to resequence NPR3. There were 105 polymorphisms identified of which 50 were novel, including 8 nonsynonymous (ns) SNPs of which 7 were novel. Expression constructs for the nsSNPs were created and HEK-293 cells were transfected with constructs for wild type (WT) and the variants. Recombinant proteins were analyzed by quantitative Western blot analysis. A significant reduction in NPR3 immunoreactive protein (60% or less of WT) was observed for the following variants Cys3, Arg146, Val499, and Ser477+Asp521. The Arg146 novel polymorphism resulted in the least protein expression (20% of WT). After treatment of WT and Arg146 cells with proteasome (MG132) and autophagy (3MA) inhibtors, it was determined that autophagy and not proteasomes plays an important role in the degradation of the Arg 146 variant protein. Modeling based on the NPR3 x-ray crystallography structure confirmed that the Arg146 variant were not compatible with WT conformation and could result in protein misfolding or instability. Conclusions: Multiple novel polymorphisms of NPR3 were identified in 3 ethnic groups. There were 4 variant receptors that displayed a significant decrease in NPR3 protein quantity, Arg146 being the variant with the least expression. Degradation of the variant Arg146 was mediated predominantly by autophagy. This SNP could have a significant effect on the metabolism of natriuretic peptides with clinical implications.

The Concise Guide to PHARMACOLOGY 2023/24 is the sixth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of approximately 1800 drug targets, and nearly 6000 interactions with about 3900 ligands. There is an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (https://www.guidetopharmacology.org/), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes almost 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point‐in‐time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.16180. Catalytic receptors are one of the six major pharmacological targets into which the Guide is divided, with the others being: G protein‐coupled receptors, ion channels, nuclear hormone receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid‐2023, and supersedes data presented in the 2021/22, 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC‐IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate.

Introduction: Common genetic variation has been linked to an increased risk of developing dilated cardiomyopathy (DCM). However, the phenotypic profile, outcomes, and biological mechanisms by which such genetic background may predispose individuals to DCM are still unknown. Hypothesis: The primary objectives of this study were to develop a DCM polygenic risk score (PRS) based on prior case control-DCM GWAS and to apply this PRS to a well clinical characterized general population. Methods: The DCM-PRS was derived from 13 DCM risk alleles that were assayed in an unselected cohort (n=1897) of unrelated Olmsted County residents age >45 years who did not have a history of heart failure (HF) or CM and underwent physical examination, echocardiography, and blood analyses. Results: The entire population was equally divided into quartiles based on the DCM-PRS. No significant differences were present in terms of age (median 62 years) and sex (48% male). However, a significant correlation was detected between the DCM-PRS and left ventricle ejection fraction (LVEF) (Beta: -2.68, p<0.001), LV end-systolic diameter (Beta: 0.22, p<0.001), and LV end-diastolic diameter (Beta: 0.14, p=0.01). During a follow-up of 16 years (IQR: 15-17), 47 subjects developed DCM. Using a 3:1 non-DCM vs DCM matched cohort, a logistic regression analysis, found a significant correlation between median DCM-PRS and DCM development [OR=2.27 (1.06, 4.85), p=0.03]. However, there was no association between the DCM-PRS and HF biomarkers (aldosterone, natriuretic peptides, ST2, Galectin-3). Conclusions: DCM-PRS correlates with decreased LVEF, increased LV dimensions, and DCM development in a general population without significant differences in baseline clinical features. The absence of correlation between the DCM-PRS and available HF biomarkers suggests that this genetic background affects LV traits and DCM development independent of these biological mechanisms.

Introduction: Excess cardiomyocyte oxidative stress is a major metabolic abnormality in HTN and its progression to HF. Thus, therapies that reduce oxidative stress in the heart may lead to a reduction in CVD related adverse outcomes such as HF and death. Recently, we bioengineered a bispecific peptide NPA7 that co-activates the protective GC-A/cGMP and MasR/cAMP pathways. Previously we showed that NPA7 possesses cardiorenal protective properties. However, the antioxidant effects of NPA7 within the heart is unknown. Hypothesis: NPA7 protects human cardiomyocytes against oxidative stress through the GC-A/Mas Receptor-KEAP1-NRF2 pathway. Methods: HCMs were pretreated with PBS or NPA7 (10 uM) followed by 400 uM hydrogen peroxide (H2O2) to induce oxidative stress. Intracellular ROS was measured by dihydroethidium (DHE) staining and protein levels of KEAP1 and NRF2 via western blot. The ratio of GSH/GSSG were determined by using commercial kit. mRNA levels of G6PD, GCLC, GCLM and GSS in HCMs, which represents antioxidant capacity, were determined by real-time PCR. For knockdown experiments, HCMs were transfected with the siRNA target GC-A and MasR for 24 h and then treated with NPA7 and H2O2 for another 20 h. Results: H2O2 increased DHE staining level, which indicated elevated intracellular ROS levels within HCMs. Notably, treatment with NPA7 decreased DHE level and increased the ratio of GSH/GSSG in HCMs with H2O2. Furthermore, NPA7 significantly increased the mRNA level of NRF2 target genes (G6PD, GCLC, GCLM, GSS) through NRF2 activation and KEAP1 degradation, indicating that NPA7 activates KEAP1-NRF2 pathway, the upstream pathway that regulate antioxidant gene expression, in HCMs. Moreover, these effects were eliminated if GC-A and MasR were silenced by siRNA, thus supporting the protective antioxidant role of both GC-A and MasR. Conclusions: The present study establishes an antioxidant action of NPA7, a novel bispecific designer peptide, on H2O2-induced oxidative stress by the dual targeting of GC-A and MasR through the KEAP1-NRF2 signaling pathway in HCMs. These results advance NPA7 as an innovative therapeutic strategy targeting oxidative stress related to CVD.

Abstract Background/Introduction Hypertension (HTN) and metabolic syndrome (MetS) are both leading risk factors for major cardiovascular diseases, which frequently coexist as a complicated cardiometabolic disorder. The cardiac hormone atrial natriuretic peptide (ANP) plays a key role in both blood pressure and metabolic regulation through activation of the guanylyl cyclase-A receptor (GC-A) and the second messenger 3’,5’ cyclic guanosine monophosphate (cGMP). Indeed, ANP decreases blood pressure, induces lipolysis by increasing plasma levels of non-esterified fatty acids (NEFA) and improves insulin-sensitivity. MANP is a new Mayo Clinic designed natriuretic peptide consisting of the native ANP with a 12-amino-acid C-terminus extension and its biological actions are mediated by the GC-A/cGMP pathway. MANP is less susceptible to neprilysin degradation and exert more sustained cGMP dependent biological actions than ANP. Purpose In a proof-of-principle human study, for the first time we aimed to determine the cardiovascular and metabolic properties of MANP, a novel ANP analog, in the clinical setting of HTN with MetS. Methods We conducted a double-blind, placebo-controlled trial in 22 patients (17 receiving MANP) with HTN and MetS involving single subcutaneous injection of MANP (2.5 µg/kg) or placebo (NCT03781739). Blood pressure (BP) and circulating cGMP were monitored for 24 hours post treatment. Circulating metabolic parameters including insulin, glucose, non-esterified fatty acids (NEFA) and insulin resistance (HOMA-IR) and insulin sensitivity (HOMA-IS) indexes were assessed for the first 4 hours post treatment. Results Compared to baseline, MANP increased plasma cGMP at 30 minutes (delta: 4.8 ± 2.0 pmol/mL, P = 0.02) and 1 hour (delta: 2.9 ± 1.3 pmol/mL, P = 0.03) post injection. At 6 hours, systolic BP decreased by 5.7 ± 2.9 mmHg (P = 0.06) in the MANP group, whereas no reduction in BP was observed in placebo group. Among the 17 subjects receiving MANP, lower baseline cGMP levels were associated with greater mean reductions in systolic BP (ρ = 0.66, P = 0.005). After MANP injection, glucose levels decreased at 2 (delta: -4.7 ± 2.1 mg/mL, P = 0.04) and 4 hours (delta: -13.1 ± 3.9 mg/mL, P = 0.003) compared to baseline while insulin levels remained stable. During the first 4 hours post injection, we also observed a trend of increase in insulin sensitivity index (HOMA2-IS) and decrease in insulin resistance index (HOMA2-IR) with MANP, both were opposite to the trends in placebo. At 1 hour post MANP administration, NEFA increased by 108.2 ± 37.4 µM compared to baseline (P = 0.01). Conclusion(s) Our findings support the favorable cardiovascular and metabolic actions of MANP as a potential therapeutic strategy for HTN with MetS.

Males are characterized by lower ANP and BNP with greater prevalence of cardiometabolic disease. The ANP genetic variant rs5068 was associated with less metabolic dysfunction in males, whereas no metabolic profile was related to the BNP genetic variant rs198389 in the general population. ANP may play a more biological role in metabolic homeostasis compared with BNP in the general population with greater physiological metabolic actions in males compared with females.

Introduction: Previously, miR-425 have been implicated in the inhibition of the cardiac natriuretic peptide (NP) ANP gene expression with their role on BNP undefined. The mechanism by which miR-425 modulates NP expression remains to be explored. In heart failure (HF), adrenergic and neurohormone pathways are aberrantly activated. Our goal was to investigate the role of miR-425 and its downstream target Cofilin 2 (CFL2) on ANP and BNP expression in human CV disease (CVD). Hypothesis: We hypothesized miR-425, via CFL2, supresses NPs expression in vitro. MiR-425, CFL2 and NP levels were also determined in CVD patients. Methods: In vitro, human cardiomyocytes (HCM) were treated with vehicle (Veh), catecholamine isoproterenol (ISO) and cytokine endothelin (ET), miR-425 mimic. Cells were transfected with CFL2 plasmid or CFL2 siRNA. Normal (NM, n=100), Hypertension (HTN, n=30) and Acute HF (AHF, n=74) cohorts were studied. A confirmatory cohort was recruited. Plasma NT-proBNP, miR-425 were measured. In left ventricles (LV) from NM or HF (n=5 each), NP, CFL2 and miR-425 expression were assessed. Data expressed as means±SEM. * p<0.05 vs NM or Veh. Results: In vitro in HCM, treatment with ISO or ET in HCM reduced miR-425 and elevated NP mRNA levels. Furthermore, miR-425 mimic reduced Nppa (Veh: 1.0±0.03, mimic: 0.7±0.02*) and Nppb levels (Veh: 1.0±0.03, mimic: 0.5±0.01*). We showed that a top predicted target of miR-425, CFL2, was also reduced by the mimic. Further, NP mRNA was elevated by CFL2 overexpression and reduced by the knockdown of CFL2. In humans, MiR-425 was lower in HTN and AHF patients (NM: 0.15±0.03, HTN: 0.03±0.005*, HF: 0.01±0.003*) than NM. MiR-425 negatively correlates with NT-proBNP in NM and AHF cohorts. Downregulation of miR-425 was validated in a second AHF cohort. Similarly, in HF LV tissues, miR-425 (NM: 2.5±0.5, HF: 1.0±0.5*) was lower than NM group, while CFL2 and NP gene and protein expression were increased. Conclusion: In vitro, cardiac stress hormones downregulate miR-425 and increase NP gene expression, potentially through a novel target, CFL2. In CVD patients, miR-425 is lower, accompanied by an elevation of CFL2 and NP. Our findings implicate the pathway of stress hormones/miR-425/CFL2/NP production in CVD.