Citations

Introduction: The cardiac atrium is an important endocrine organ which also releases natriuretic peptides (NPs). We reported that dysregulation of the proNP convertases, furin and corin, may disrupt NP progressing, causing atrial fibrosis in experimental heart failure (HF). Atrial fibrosis results in atrial arrhythmias and impairs the prognosis of human HF, therefore understanding mechanisms of atrial fibrosis may help in designing treatment strategies for HF. We sought to extend our studies into the entire NP system and global gene profiles including fibrotic and inflammatory pathways in experimental HF. Hypothesis: Components of the NP, pro-fibrotic and inflammatory system will be up-regulated in the atrium in HF. Methods: Experimental canine HF was induced by rapid right ventricular pacing at 240 bpm for 10 days. We examined hemodynamics, echo parameters, circulating neurohumoral factors, and global gene profiles using RT-PCR microarrays related to the NP system, fibrosis, growth factors, inflammation and cardiac hypertrophy in left atrium (LA) from normal and HF canines (n=4 of each). Results: Experimental HF was characterized by decreased % EF and LV radial strain, and increased circulating ANP, cGMP and aldosterone levels. HF LA weight significantly increased with fibrosis and interstitial edema compared to normals. Gene profile analyses showed increases in profibrotic cytokines and extracellular matrix related genes in LA. Increased ANP expression but also increased ANP degrading enzyme IDE and decreased proANP processing enzyme corin were also observed. Genes related to inflammatory cytokines such as TNF-alpha, members of the IL-6 family, MCP-1, and cell adhesion molecules were up-regulated in LA compared to normals. Conclusions: Experimental HF was characterized by on-going atrial fibrosis with increased circulating ANP levels. Although ANP gene expression increased in failing LA, impaired proANP processing and accelerated ANP degradation may impair any anti-fibrotic ANP effects. Further, atrium may be a source of inflammatory cytokines and pro-fibrotic growth factors which may advance organ damage in HF. Our studies suggest NP treatment, perhaps in a form less susceptible to IDE degradation, may be a novel therapeutic for HF.

Introduction: ProANP is a 108 amino acid (AA) prohormone which is produced in the atria and processed to the mature 28 AA ANP which activates the guanylyl cyclase receptor-A (GC-A) and its second messenger cGMP. ProANP is found in the human circulation but its bioavailability is undefined. Hypothesis: ProANP represents a novel cardiac peptide with more sustained natriuretic actions than either carperitide (ANP) or nesiritide (BNP). ProANP itself can activate GC-A in vitro and the proANP can be processed in human serum from normals and in patients with heart failure (HF). Methods: We examined the in vivo cardiorenal actions of proANP compared to ANP, BNP, or placebo in normal canines (667 pmol/kg, n=5/group). We determined cGMP activation of proANP, ANP and BNP in GC-A expressing HEK293 cells. ProANP processing and degradation was also defined in serum from normal subjects (n=13) and patients with HF (n=14) ex vivo. Results: ProANP had significantly greater diuretic and natriuretic properties with increased renal blood flow and sustained renal tubular actions compared to ANP or BNP in canines. ProANP also resulted in greater and more prolonged cardiac unloading than ANP, and much less hypotensive effects than BNP. The plasma half-life of proANP was 4.5 times longer than ANP and 3.8 times longer than BNP. ProANP itself stimulated cGMP generation in GC-A expressing HEK cells which was equal to ANP. ProANP was processed to ANP in fresh serum from normals as well as HF patients ex vivo and the processed peptide activated cGMP in GC-A expressing HEK cells. Conclusions: ProANP represents a novel GC-A activator with a longer half-life and greater natriuresis and diuresis than ANP and BNP and less hypotensive effects than BNP. The bioactivity of exogenous proANP may be through direct stimulation of GC-A, as well as through processing into ANP, as proANP is processed in the circulation of both normal and HF. As proANP circulates in the human circulation, proANP may represent a key circulating hormone in cardiorenal and blood pressure homeostasis as well as a potential innovative therapeutic beyond ANP (carperitide) or BNP (nesiritide) for cardiorenal diseases including HF.

Introduction: Plasma aldosterone (Aldo) increases Na and water reabsorption and mediates inflammation. Our recent findings in a general population cohort showed Aldo strongly associated with hypertension (HTN), obesity, chronic kidney disease (CKD) and lower natriuretic peptide levels (NPs) during a first visit (V1), even when Aldo was within the normal range. It is undefined whether Aldo itself (V1) and/or its increase after 4-year (second visit, V2) can predict new onset cardiovascular and metabolic diseases. Hypotheses: We hypothesized that: 1) Aldo-V1 predicts new onset disease at V2; 2) The increase of Aldo between V1 and V2 predicts new onset disease-V2; and 3) Aldo-V2 remains associated with cardiovascular and metabolic disease-V2. Methods: We defined the correlations between Aldo-V1 and Aldo-V2 with cardiometabolic diseases and medications at V2, in a general community cohort (N=1368) from Olmsted County, MN. Associations were adjusted for age, sex and BMI; Aldo was analyzed as continuous variable and according to tertiles. Results: After 4 years, Aldo-V1 continuous variable predicted new onset of central obesity (p=0.0113, OR=1.36, CI=1.07-1.73), HTN (p=0.0012, OR=1.36, CI=1.13-1.63) and use of antilipemic drugs (p=0.0119, OR=1.25, CI=1.05-1.48); while Aldo-V1 in the 3 rd tertile predicted new onset of type 2 diabetes (T2DM) (p=0.0392, OR=1.96, CI=1.03-3.70), use of antilipemic therapy (p=0.0162, OR=1.59, CI=1.09-2.31) and HTN (p=0.049, OR1.44, CI=1.00-2.08) at V2. Secondly, we observed that the increase in Aldo between V1 and V2 predicted new HTN-V2. Finally, we found higher Aldo-V2, but still within the normal range and Aldo-V2 remained associated with HTN, obesity and CKD, when analyzed as continuous variable and when in the 3 rd tertile. Conclusions: In the general community, Aldo-V1 predicts new onset HTN, central obesity, T2DM and use of antilipemic therapy. Importantly, the increase of aldosterone between V1 and V2 also predicts new onset HTN. Finally, Aldo-V2 correlates with HTN, obesity and CKD as we found at V1. Further studies are warranted to evaluate aldosterone as therapeutic target to delay disease progression, and to support its role as prognostic biomarker to identify high-risk subjects.

Background: In July 2015, the FDA approved the use of sacubitril/ valsartan in patients with heart failure (HF) and reduced ejection fraction. It was shown in a large clinical trial to reduce the risk of both hospitalization and death compared with enalapril, and has since received a class I recommendation for use in the 2016 ACC/ AHA HF guidelines. However, the use of sacubitril/ valsartan in a clinical practice has not been described. We aimed to assess the uptake and cost of sacubitril/ valsartan in its first year following FDA approval. Methods: Using a large U.S. insurance database, we identified privately insured and Medicare Advantage (MA) patients who filled a first prescription for sacubitril/ valsartan between July 1, 2015 and July 31, 2016. We restricted to persons with medical and pharmacy enrollment for 6 months prior to first fill. For reference, we identified all individuals with a diagnosis of HF on a billing claim (ICD9 428.X or ICD-10 I50.X) in the same time period. Results: There were 314,410 individuals with a diagnosis of HF in the study period. In total, 972 filled a new prescription for sacubitril/ valsartan, and the number of new users steadily increased over time (Figure). The mean age of sacubitril/ valsartan users was 68.1±12.3 years, 32.5% were women, 61.1% were white, and 77% were enrolled in MA plans. Most prescribing clinicians were cardiologists (82.5%). A majority of prescription costs were covered by the health plan (mean $324.05, median $335.38, interquartile range [IQR] $266.56-$370.10). Out-of-pocket (OOP) costs per 30-day prescription filled were variable (mean $101.53, median $45.00, IQR $7.40-$97.49), and were similar in beneficiaries enrolled in MA and commercial plans. By comparison, median OOP costs were $2-4 for lisinopril, losartan, carvedilol, and spironolactone per 30-day prescription. Discussion: These finding suggest that the uptake of sacubitril/ valsartan has been slow in the first year after FDA approval. While the majority of prescription costs are covered by the health plan, OOP costs are still much higher than other guideline-recommended HF medications. Further studies are needed to determine if uptake of sacubril/ valsartan continues to rise and if the higher prescription cost is associated with lower downstream costs of hospitalization and mortality benefit.

Significance Statement A higher percentage of the kidney cortex area that exhibits interstitial fibrosis/tubular atrophy (IF/TA) is a feature of poor prognosis on biopsy. This study describes IF/TA density (the number of IF/TA foci per area of cortex) and shows it predicts progressive CKD, independent of both percentage IF/TA and clinical characteristics among patients who have undergone nephrectomy. Other patterns of IF/TA and inflammation were not predictive for progressive CKD and mortality beyond percentage IF/TA and clinical characteristics. At the same percentage IF/TA, a higher IF/TA density suggests more scattered and widespread damage to the nephrons, with a worse kidney prognosis. This information may be helpful for accurate interpretation of the severity of “chronic changes” observed on a kidney biopsy. Background Chronic tubulointerstitial injury on kidney biopsy is usually quantified by the percentage of cortex with interstitial fibrosis/tubular atrophy (IF/TA). Whether other patterns of IF/TA or inflammation in the tubulointerstitium have prognostic importance beyond percentage IF/TA is unclear. Methods We obtained, stained, and digitally scanned full cortical thickness wedge sections of renal parenchyma from patients who underwent a radical nephrectomy for a tumor over 2000–2015, and morphometrically analyzed the tubulointerstitium of the cortex for percentage IF/TA, IF/TA density (foci per mm 2 cortex), percentage subcapsular IF/TA, striped IF/TA, percentage inflammation (both within and outside IF/TA regions), and percentage subcapsular inflammation. Patients were followed with visits every 6–12 months. Progressive CKD was defined as dialysis, kidney transplantation, or 40% decline from the postnephrectomy eGFR. Cox models assessed the risk of CKD or noncancer mortality with morphometric measures of tubulointerstitial injury after adjustment for the percentage IF/TA and clinical characteristics. Results Among 936 patients (mean age, 64 years; postnephrectomy baseline eGFR, 48 ml/min per 1.73m 2 ), 117 progressive CKD events and 183 noncancer deaths occurred over a median 6.4 years. Higher IF/TA density predicted both progressive CKD and noncancer mortality after adjustment for percentage IF/TA and predicted progressive CKD after further adjustment for clinical characteristics. Independent of percentage IF/TA, age, and sex, higher IF/TA density correlated with lower eGFR, smaller nonsclerosed glomeruli, more global glomerulosclerosis, and smaller total cortical volume. Conclusions Higher density of IF/TA foci (a more scattered pattern with more and smaller foci) predicts higher risk of progressive CKD after radical nephrectomy compared with the same percentage of IF/TA but with fewer and larger foci.

Atrial and B-type natriuretic peptides (ANP and BNP) are cardiac hormones secreted as compensatory measures to preserve cardiorenal homeostasis. Treating heart failure (HF) with sacubitril/valsartan increased ANP and not BNP, suggesting the ANP system may confer therapeutic benefit. Thus, the presence of an ANP deficient subgroup of HF patients possibly posing higher risk for HF severity, underscores a need to characterize both, the biologically active and inactive (NT-proANP and NT-proBNP) natriuretic peptides (NPs)(latter resistant to degradation), to highlight the extent of NP production in HF. Characterizing neprilysin (NEP) activity may also provide insights into the degree of NP degradation in HF. This study aims to both highlight the cardiac NP response in acute decompensated HF(ADHF) by measuring molecular forms of ANP and BNP together with defining circulating soluble NEP activity as to assess mechanisms impairing the NP response in HF. We recruited 47 healthy individuals with neither cardiovascular nor metabolic disease and compared ANP, BNP, NT-proANP, NT-proBNP, and NEP activity levels with 107 recruited ADHF patients. In ADHF, compared to a healthy setting, median ANP, BNP, NT-proANP, and NT-proBNP were all elevated (15.7 vs. 118.1 pg/mL , p<0.0001; 23 vs. 515 pg/ml, p<0.0001; 60.1 vs. 651.6 pg/mL, p<0.0001; 46 vs. 3330 pg/mL, p<0.0001, respectively). However, circulating NEP activity was significantly lower in ADHF than in healthy circulation (32 vs. 12.3 nM/mL/min, p<0.0001). NPs did not correlate with NEP activity in healthy circulation. However, only ANP (r = 0.4788, p<0.0001) and NT-proANP (r = 0.6819, p<0.0001) correlated with NEP activity in ADHF. The presence of an impaired ANP response in ADHF, underscored by insufficient increases in NT-proANP than NT-proBNP, suggests decreased ANP production may induce not only an ANP deficient ADHF state, but be characteristic of ADHF. The presence of NEP activity in ADHF circulation, despite lower NEP activity compared to healthy individuals, suggests ANP degradation may second impaired production, further lowering ADHF ANP levels. Our studies support augmenting the ANP system in ADHF through either endogenous stimulation or exogenous supplementation as optimal therapeutic strategies.

Objective B-type natriuretic peptide (BNP) has favourable effects on left ventricular remodelling, including antifibrotic and antiapoptotic properties. We tested the hypothesis that infusion of BNP after an acute myocardial infarction would reduce left ventricular systolic and diastolic volumes and improve left ventricular ejection fraction compared with placebo. Methods A total of 58 patients who underwent successful revascularisation for an acute ST elevation anterior myocardial infarction were randomised to receive 72-hour infusion of BNP at 0.006 µg/kg/min or placebo. Left ventricular end diastolic and systolic volumes and left ventricular ejection fraction were measured at baseline and at 30 days by multigated acquisition scan. Left ventricular infarction size was measured by cardiac MRI. Results BNP infusion led to significantly higher BNP levels and plasma cyclic guanosine monophosphate at 72 hours. No significant difference in change of left ventricular volumes or ejection fraction from baseline to 30 days was observed between groups. Although left ventricular infarction size measured by cardiac MRI was not significantly different between BNP infusion versus placebo (p=0.39), there was a trend towards reduced infarction size in patients with a baseline ejection fraction of <40% (p=0.14). Conclusions Infusion of BNP in patients with an anterior myocardial infarction did not affect parameters of left ventricular remodelling. Patients treated with BNP who had a baseline left ventricular ejection fraction of <40% had a trend towards reduced left ventricular infarction size compared with placebo. These results do not support the use of intravenous BNP in patients after recent myocardial infarction. Trial registration number NCT00573144.

Cardiorenal syndrome (CRS) is a multi‐organ disease, encompassing heart, kidney and vascular system dysfunction. CRS is a worldwide problem, with high morbidity, mortality, and inflicts a significant burden on the health care system. The pathophysiology is complex, involving interactions between neurohormones, inflammatory processes, oxidative stress and metabolic derangements. Therapies remain inadequate, mainly comprising symptomatic care with minimal prospect of full recovery. Challenges include limiting the contradictory effects of multi‐organ targeted drug prescriptions and continuous monitoring of volume overload. Novel strategies such as multi‐organ transplantation and innovative dialysis modalities have been considered but lack evidence in the CRS context. The adjunct use of pharmaceuticals targeting alternative pathways showing positive results in preclinical models also warrants further validation in the clinic. In recent years, studies have identified the involvement of gut dysbiosis, uraemic toxin accumulation, sphingolipid imbalance and other unconventional contributors, which has encouraged a shift in the paradigm of CRS therapy.

Based on the cardiac hormone atrial natriuretic peptide (ANP) and its seminal role in blood pressure (BP) homeostasis, we investigated the chronic BP lowering actions of a novel ANP analog currently entering clinical trials for hypertension. Previous reports demonstrate that this analog MANP activates the guanylyl cyclase A receptor (GC-A) and results in more potent biological actions compared with ANP; thus, it may represent a new therapeutic drug for hypertension. A major goal of this study was to establish that chronic subcutaneous delivery of MANP is feasible and hypotensive together with cGMP effects. We investigated the BP-lowering and cGMP-activating actions of acute and chronic subcutaneous delivery in normal and hypertensive rats. Furthermore, we explored vascular mechanisms of MANP in human aortic smooth muscle cells (HASMC) and ex vivo in isolated arteries. In normal rats with a single subcutaneous injection, MANP promoted robust dose-dependent BP-lowering actions and natriuresis, together with cGMP activation. Most importantly in hypertensive rats, once-a-day subcutaneous injection of MANP for 7 days induced cGMP elevation and long-term BP reduction compared with vehicle. Mechanistically, in HASMC, MANP activated cGMP and attenuated angiotensin II-mediated increases in intracellular Ca2+levels while directly vasorelaxing arterial rings. Our study demonstrates for the first time the effectiveness of subcutaneous administration of MANP for 7 days and provides innovative, vascular mechanisms of BP regulation supporting its continued development as a novel therapeutic for hypertension.

Abstract Introduction The rapid increase of patients of heart failure (HF) is a major health burden worldwide. Most importantly is the need to develop innovative new drugs for treatment of HF, such as sacubitril/valsartan which in part functions by enhancing the natriuretic peptides (NPs). We engineered NPA7 as a novel 30 amino acid bispecific designer peptide which activates the particulate guanylyl cyclase A receptor (pGC-A)/cGMP and for which the NPs both ANP and BNP are ligands and the Mas-receptor (MasR)/cAMP pathways for Angiotensin 1–7 (Ang1–7) is the endogenous ligand. We previously reported that acute intravenous (IV) administration of NPA7 shows cardiorenal protective and renin-aldosterone suppressing actions that go beyond the native peptides, BNP or Ang 1–7, which may have therapeutic potential for HF. Purpose To support the clinical development of NPA7 as a potential therapy in HF which promotes NP and MasR pathways, we investigated the actions and stability of subcutaneous (SQ) administration of NPA7 in normal canines. We also defined NPA7's peptide stability and metabolites in canine plasma. Methods Plasma and urinary cGMP, cardiorenal and renin-aldosterone responses to SQ injection (10μg/kg) were determined over 4 hours in normal canines (n=5) in vivo. Ex vivo, we established stability of NPA7 and key metabolites in canine serum using liquid chromatography-mass spectrometry (LC-MS). Data are expressed as mean ± SEM. * P<0.05 vs. BL. Results In vivo, SQ NPA7 resulted in a sustained increase at 2 hours in plasma (BL: 10±3; 120 min: 30±6* pmol/ml) and urinary (BL: 1033±198; 120 min: 5792±857* pmol/min) cGMP, GFR (BL: 29±6; 120 min: 70±12* ml/min) and sodium excretion (BL: 18±10; 120 min: 144±33* ueq/min). We observed a gradual reduction in BP at 60 min (BL: 109±4; 60 min: 99±7* mmHg) with a sustained decrease in PCWP at 4 hours (BL: 5±0.9; 240 min: 3.1±0.6* mmHg). SQ NPA7 also suppressed plasma renin and aldosterone up to 3 hours after SQ injection. LC-MS revealed that NPA7 was highly stable with both the pGC-A and MasR activating moieties intact ex vivo in canine serum with a disappearance time of 2 hours. We also identified 2 major NPA7 metabolites NPA71–27 and NPA71–28. Conclusions SQ NPA7 possesses cGMP activating, cardiac unloading, diuretic, natriuretic, and renin-aldosterone suppressing actions in normal canines. NPA7 is also highly stable in serum. These studies support SQ administration as an effective delivery strategy for NPA7, a first-in-class innovative bispecific dual pGC-A/MasR activator now in preclinical development for HF.