Cardiovascular diseases (CVD) remain a major global health challenge. Early markers of disease initiation and progression are urgently needed. We, and others, have previously shown changes in the gut microbiome in association with metabolic and CVD. Here, we demonstrate that gut microbiome-related changes can be detected in association with subclinical variations in heart and kidney function. Markers related to gut microbial metabolism of aromatic amino acids, phenylalanine and tyrosine, associate with circulating pro-atrial natriuretic peptide and estimated glomerular filtration rate in a metabolically healthy European population. Observational and genetic evidence further identify microbiome-related metabolites as mediators of this gut microbiome-kidney axis, with their baseline levels associating with incident CVD in an external Canadian population. Altogether, our work suggests that the gut microbiome interacts with the cardiorenal axis and participates in an interorgan crosstalk affecting host physiology and risk of CVD.

Background: Circulating C-type natriuretic peptides (CNPs) predict adverse outcome in women presenting with ST-elevation myocardial infarction. Objectives: The purpose of this study was to determine the prognostic impact of a high proCNP concentration in women with angina pectoris but no obstructive coronary artery disease (ANOCA). Methods: In a prospective cohort of women with ANOCA, we assessed the baseline associations between proCNP concentrations in plasma and clinical data. Moreover, we performed exploratory partial least squares regression (PLS) analyses for correlation patterns of proCNP with 185 cardiovascular plasma markers. We included 1,508 women in baseline/follow-up analyses and 1,598 women in PLS analyses. Follow-up analyses included all-cause death and a composite endpoint of cardiovascular events, where we calculated HR estimates from crude and adjusted (age, creatinine) Cox proportional hazards models. Results: A high proCNP concentration (223 women) was associated with hypertension (P = 0.001), diabetes mellitus (P < 0.001), and postmenopausal status (P < 0.001) but not age (P = 0.13). PLS analyses showed that proCNP concentrations were positively associated with atherosclerotic markers and negatively associated with pro-inflammatory markers. For high proCNP, we found an increased risk of all-cause mortality (HRcrude: 1.73 [95% CI: 1.10-2.73]; P = 0.02 and HRadjusted: 1.57 [95% CI: 0.99-2.49]; P = 0.06), whereas hazard rates of cardiovascular events were comparable (HRcrude: 1.08 [95% CI: 0.72-1.62]; P = 0.71 and HRadjusted: 1.03 [95% CI: 0.68-1.56]; P = 0.90). Conclusions: In women with ANOCA, a high circulating proCNP concentration is associated with a distinct cardiovascular risk profile beyond pro-inflammatory biomarkers and an increased risk of all-cause mortality.

BACKGROUND:It remains unknown whether estimation of the relative stress perfusion deficit offers added value in the prediction of significant coronary artery stenosis in myocardial perfusion imaging with [15O]H2O positron emission tomography (PET) in a population with high prevalence of established cardiac disease. METHODS:During eight months, we consecutively included all patients undergoing [15O]H2O PET and subsequent invasive coronary angiography (ICA). Significant stenosis was defined from ICA as fractional flow reserve ≤.8 or coronary artery narrowing of ≥70%. We calculated absolute and relative total perfusion deficits (aTPD and rTPD, respectively) as semiquantitative measures of the extent and severity of reduced stress perfusion. A multivariate logistic regression analysis was performed to test the adjusted associations (odds ratio (OR) with 95% CI) with significant coronary artery stenosis. RESULTS:Of 800 patients undergoing [15O]H2O PET, 144 underwent ICA, where 142 patients had aTPD of ≥3% and 79 (55%) of these had at least one significant stenosis. In an adjusted analysis, rTPD (OR10% increase = 2.12 (1.44-3.12), P < .001), previous coronary artery bypass grafting (CABG) (OR = .11 (.03-.36), P < .001) and reduced left ventricular ejection fraction (LVEF) (OR = .25 (.08-.84), P = .02) were independently associated with significant stenosis, whereas the association with aTPD (OR10% increase = 1.14 (.98-1.32), P = .08) was modest. CONCLUSIONS:In the presence of an absolute perfusion deficit (aTPD of ≥3%), rTPD may improve the prediction of significant stenosis in a heterogeneous population of patients examined with [15O]H2O PET. Furthermore, previous CABG and reduced LVEF are associated with nonstenotic perfusion deficiencies, suggesting caution when interpreting myocardial perfusion imaging in such patients.

Measurement of natriuretic peptides (NPs) has proven its clinical value as biomarker, especially in the context of heart failure (HF). In contrast, a state of partial NP deficiency appears integral to several conditions in which lower NP concentrations in plasma presage overt cardiometabolic disease. Here, obesity and type 2 diabetes have attracted considerable attention. Other factors-including age, sex, race, genetics, and diurnal regulation-affect the NP "armory" and may leave some individuals more prone to development of cardiovascular disease. The molecular maturation of NPs has also proven complex, with highly variable O-glycosylation within the biosynthetic precursors. The relevance of this regulatory step in post-translational propeptide maturation has recently become recognized in biomarker measurement/interpretation and cardiovascular pathophysiology. An important proportion of people appear to have reduced effective net NP bioactivity in terms of receptor activation and physiological effects. The state of NP deficiency both entails a potential for further biomarker development and could also offer novel pharmacological possibilities. Alleviating the state of NP deficiency before development of overt cardiometabolic disease in selected patients could be a future path for improving precision medicine.

BACKGROUND:C-type natriuretic peptide (CNP) is a cardioprotective peptide with high affinity for the ectoenzyme neutral endopeptidase (neprilysin). We aimed to determine whether angiotensin receptor-neprilysin inhibitor treatment acutely affects circulating concentrations of bioactive CNP and its molecular amino-terminal precursor (NT-proCNP).METHODS:We included 9 and 10 healthy young men in 2 randomized crossover trials with sacubitril/valsartan vs control (Trial 1) and sacubitril/valsartan and sitagliptin vs sitagliptin (Trial 2). The participants were randomized to a single dose of sacubitril/valsartan (194/206 mg) or control at the first visit 30 min prior to a standardized meal intake. We obtained blood samples at 12 time points over 5 h and measured plasma concentrations of NT-proCNP in both trials and CNP in Trial 2.RESULTS:NT-proCNP concentrations increased 3.5 h after sacubitril/valsartan treatment, and at 4.5 h concentrations were 42% and 65% higher compared with control in Trial 1 and Trial 2, respectively. The total area under the curve (tAUC)15-270 min was 22% higher (P = 0.007) in Trial 1 and 17% higher with treatment (P = 0.017) in Trial 2. Concentrations of bioactive CNP followed a similar temporal pattern with an increase of 93% at 4.5 h and a 31% higher tAUC15-270 min compared with control (P = 0.001) in Trial 2.CONCLUSIONS:Sacubitril/valsartan augments circulating concentrations of both bioactive CNP and NT-proCNP in healthy young men. The increase in bioactive CNP is most likely caused by de novo synthesis and secretion rather than diminished breakdown through neprilysin inhibition.ClinicalTrials.gov registration number NCT03717688.

Objective To determine the predictive value of pro-C-type natriuretic peptide (pro-CNP) measurement in plasma sampled on admission from patients presenting with ST-elevation myocardial infarction (STEMI). Design Prospective cohort study. Setting Two University Hospitals in Denmark. Participants 1760 consecutive patients (470 females and 1290 males) with confirmed STEMI. Main outcomes and measures The main outcome was all-cause mortality at 1 year after presentation and the primary measure was pro-CNP concentration in plasma at admission in all patients and longitudinal measurements in a consecutive subgroup of 287 patients. A reference population (n=688) defined cut-off values of increased pro-CNP concentrations. Results In all patients, an increased pro-CNP concentration was associated with a higher all-cause mortality after 1 year (HR 1.6, 95% CI 1.1 to 2.4, P logrank =0.009) including an interaction of sex (p=0.03). In separate sex-stratified analyses, female patients showed increased all-cause mortality (HR 1 year 2.6, 95% CI 1.5 to 4.6), P logrank <0.001), whereas no differences were found in male patients (HR 1 year 1.1, 95% CI 0.7 to 1.9, P logrank =0.66). After adjusting for potential risk factors, we found increased pro-CNP concentrations≥the median value to be independently associated with increased risk of mortality in female patients within 1 year (HR per 1 pmol/L increase: 1.04, 95% CI 1.01 to 1.06, p=0.007). Moreover, we found indications of sex differences in pro-CNP concentrations over time (higher pro-CNP in males (4.4, 95% CI −0.28 to 9.1 pmol/L, p=0.07) and interaction of sex and time (p=0.13)), and that hypertension was independently associated with higher pro-CNP (4.5, 95% CI 0.6 to 8.4 pmol/L, p=0.03). Conclusions In female but not male patients presenting with STEMI, high concentrations of pro-CNP (≥median) at admission independently indicate a higher risk of all-cause mortality. The findings are remarkably specific for female patients, suggesting a different vascular phenotype beyond traditional measures of coronary artery flow compared with male patients.

ABSTRACT In patients with ST-elevation myocardial infarction (STEMI) the immune system is activated with an inflammatory response to follow. In STEMI patients with a severe inflammatory response, risk of development of cardiogenic shock (CS) seems increased. Neutrophil Gelatinase-Associated Lipocalin (NGAL) is a glycoprotein released from mature neutrophils and plasma concentration may increase immediately after STEMI. We therefore aimed to assess whether admission NGAL plasma concentration in patients with STEMI was associated with CS development after leaving the catheterization laboratory (late CS) and 30-day all-cause mortality. Patients and Methods: From 1,892 consecutive patients with STEMI 1,626 (86%) had plasma NGAL concentration measured upon hospital admission before angiography throughout a 1-year period at two tertiary heart centers in Denmark. Patients were stratified according to NGAL quartiles (Q1–4). To assess late CS development, we adjusted for the Observatoire Régional Breton sur l’Infarctus risk score for late CS. For mortality assessment, we adjusted for gender, age, post-PCI culprit Thrombolysis in myocardial infarction flow, left ventricular ejection fraction (LVEF), kidney dysfunction, and being comatose after cardiac arrest. Results: Increasing NGAL concentration was associated with higher age, more comorbidities, and more critical patient conditions including lower blood pressure and LVEF. When adjusted for factors associated with poor outcome, NGAL remained independently associated with both late CS development (Q4 vs. Q1–3) (OR (95% CI) 3.64 (1.79–7.41) and 30-day mortality (HR (95% CI) 3.18 (1.73–5.84)). Conclusion: Admission plasma concentration of NGAL in STEMI patients is independently associated with 30-day all-cause mortality and predictive of late CS development.

Abstract Context Inhibitors of the protease neprilysin (NEP) are used for treating heart failure, but are also linked to improvements in metabolism. NEP may cleave proglucagon-derived peptides, including the glucose and amino acid (AA)-regulating hormone glucagon. Studies investigating NEP inhibition on glucagon metabolism are warranted. Objective This work aims to investigate whether NEP inhibition increases glucagon levels. Methods Plasma concentrations of glucagon and AAs were measured in eight healthy men during a mixed meal with and without a single dose of the NEP inhibitor/angiotensin II type 1 receptor antagonist, sacubitril/valsartan (194 mg/206 mg). Long-term effects of sacubitril/valsartan (8 weeks) were investigated in individuals with obesity (n = 7). Mass spectrometry was used to investigate NEP-induced glucagon degradation, and the derived glucagon fragments were tested pharmacologically in cells transfected with the glucagon receptor (GCGR). Genetic deletion or pharmacological inhibition of NEP with or without concomitant GCGR antagonism was tested in mice to evaluate effects on AA metabolism. Results In healthy men, a single dose of sacubitril/valsartan significantly increased postprandial concentrations of glucagon by 228%, concomitantly lowering concentrations of AAs including glucagonotropic AAs. Eight-week sacubitril/valsartan treatment increased fasting glucagon concentrations in individuals with obesity. NEP cleaved glucagon into 5 inactive fragments (in vitro). Pharmacological NEP inhibition protected both exogenous and endogenous glucagon in mice after an AA challenge, while NEP-deficient mice showed elevated fasting and AA-stimulated plasma concentrations of glucagon and urea compared to controls. Conclusion NEP cleaves glucagon, and inhibitors of NEP result in hyperglucagonemia and may increase postprandial AA catabolism without affecting glycemia.

AIMS:Neprilysin degrades natriuretic peptides in circulation and is also suggested to degrade the gut hormones gastrin and cholecystokinin. Neprilysin inhibition has become a therapeutic strategy and thus a regimen in need of further testing in terms of other hormonal axes besides natriuretic peptides. The aim of this study was to examine whether acute inhibition of neprilysin affects meal-induced responses in gastrin and cholecystokinin concentrations in healthy individuals.METHODS AND RESULTS:Nine healthy young men were included in an open-labelled, randomized cross-over clinical trial. The participants received a standardized meal (25 g fat, 26 g protein, 42 g carbohydrate) on two separate days with or without a one-time dosage of sacubitril ((194 mg)/valsartan (206 mg)). Blood pressure, heart rate and blood samples were measured and collected during the experiment. Statistical differences between groups were assessed using area under the curve together with an ANOVA with a Bonferroni post hoc test. Sacubitril/valsartan increased the postprandial plasma concentrations of both gastrin and cholecystokinin (80% (AUC0-270 min, P = 0.004) and 60% (AUC0-270 min, P = 0.003), respectively) compared with the control meal. No significant hemodynamic effects were noted (blood pressure, AUC0-270 min, P = 0.86, heart rate, AUC0-270 min, P = 0.96).CONCLUSION:Our study demonstrates that sacubitril/valsartan increases the postprandial plasma concentrations of gastrin and cholecystokinin in healthy individuals. The results thus suggest that neprilysin-mediated degradation of gastrin and cholecystokinin is physiologically relevant and may have a role in heart failure patients treated with sacubitril/valsartan.

Glucagon (gcg) regulates hepatic glucose and amino acid (AA) metabolism, and increased gcg levels (hyperglucagonemia) contribute to hyperglycemia in diabetes. We hypothesized that the enzyme neprilysin (NEP) contributes to gcg degradation. We measured plasma gcg levels during a mixed meal in nine healthy men after a single dose of the NEP-inhibitor/angiotensin II receptor blocker (194 mg sacubitril/206 mg valsartan, 30 min prior to meal), a DPP-4 inhibitor (sitagliptin, 2x100mg), these combined, or the meal alone. Postprandial gcg levels were 2.7-fold higher in sacubitril/valsartan treated individuals compared to controls (P=0.005) and this was not significantly altered by the addition of sitagliptin (P=0.28). Sacubitril/valsartan also lowered postprandial plasma AA levels (P=0.01), but glucose levels were unaffected (P=0.76). In obese individuals (n=7), eight weeks sacubitril/valsartan treatment increased fasting gcg levels (P=0.02). To test whether NEP degrades gcg and diminishes its signaling, we performed mass-spectrometry and assessed cells transfected with the gcg receptor (gcgr). We found that NEP cleaves gcg and that the gcg fragments produced were unable to activate the gcgr. In non-sedated C57BL/6JRj female mice (n=8) NEP inhibition (sacubitril, 0.7 nmol/g) increased gcg levels (P=0.02) and tended to increase AA disappearance (P=0.076) and urea formation (P=0.08) during an AA challenge. A gcgr antagonist (Novo Nordisk; 25-2648, 100 mg/kg) abolished the increase in urea formation observed with sacubitril alone. Gcg levels were increased 1.9-fold (P<0.002) with sacubitril compared to without, after a single injection of gcg (96 ng/g). In mice with genetic ablation of NEP (n=10), fasting plasma urea (P=0.003) but surprisingly not gcg levels (P=0.57) were increased compared to controls. NEP degrades gcg and thus inhibitors of NEP may result in hyperglucagonemia with potential metabolic perturbations on hepatic AA metabolism. Disclosure S. Kjeldsen: None. S. Zraika: Research Support; Self; Novartis Pharmaceuticals Corporation. S.M. Mongovin: None. L.H. Hansen: None. D. Terzic: None. P.D. Mark: None. P. Plomgaard: None. J.P. Gøtze: None. M. Winther-Soerensen: None. J. Hunt: None. K.D. Galsgaard: None. M.M. Rosenkilde: Board Member; Self; Synklino. Consultant; Self; Antag Therapeutics, Bainan Biotech. G.H. Goossens: None. E.E. Blaak: None. J.J. Holst: Advisory Panel; Self; AstraZeneca, Merck Sharp & Dohme Corp., Novo Nordisk A/S, Zealand Pharma A/S. Other Relationship; Spouse/Partner; Antag Therapeutics. N.J. Wewer Albrechtsen: Research Support; Self; Mercodia, Novo Nordisk A/S, Novo Nordisk Foundation. Speaker’s Bureau; Self; Merck Sharp & Dohme Corp. Funding Novo Nordisk Foundation (NNF19OC0055001)

Context: Combined inhibition of neprilysin and dipeptidyl peptidase 4 (DPP-4) has been shown to augment plasma concentrations of glucagon-like peptide-1(GLP-1) in animal models, but whether this occurs in humans is unknown. Objective: To investigate the effects of inhibition of neprilysin by sacubitril/valsartan alone or in combination with a DPP-4 inhibitor (sitagliptin) on plasma concentrations of GLP-1 in healthy men. Design: Two open-labeled crossover studies were performed in human subjects. Setting: General community. Participants: Nine and 10 healthy young men were included in study 1 and study 2, respectively. Intervention: Study participants received a standardized meal (34% carbohydrates, 45% fat, 21 % protein; total caloric content, 2106 kJ) combined with a prior dose of either sacubitril/valsartan (194/ 206 mg) or control in study 1 and in study 2, with a prior dose of sitagliptin (2 x100 mg, given similar to 10 hours apart) either alone or with sacubitril/valsartan (194/206 mg). Main Outcome Measures: Plasma concentrations of total and intact GLP-1. Results: Sacubitril/valsartan increased postprandial plasma concentrations of total GLP-1 by 67% [total area under the curve (tAUC)(0-)(240min): 3929 +/- 344 vs 2348 +/- 181 minutes x pmol/L, P = 0.0023] and increased concentrations of intact GLP-1 plasma concentrations more than sitagliptin alone (t-AUC(0-)(240min): 1021 +/- 114 vs 660 +/- 80 minutes x pmol/L, P = 0.01). Plasma concentrations of glucose, insulin, and GIP were not significantly (P > 0.10) changed upon sacubitril/valsartan treatment. Conclusions: Sacubitril/valsartan combined with a DPP-4 inhibitor led to markedly higher concentrations of intact GLP-1 than DPP-4 inhibition alone, supporting a role for both neprilysin and DPP-4 in the metabolism of GLP-1 in humans, a finding that may have therapeutic implications.

Diabetes is an independent risk factor for heart failure. Treatment with a neprilysin inhibitor-angiotensin receptor blocker (sacubitril/valsartan) was demonstrated to improve glycemia and reduce time to initiation of insulin therapy but the underlying mechanism(s) are unknown. We hypothesized that sacubitril/valsartan attenuates neprilysin-dependent degradation of GLP-1, and that combined inhibition of the other enzyme cleaving intact GLP-1, dipeptidyl peptidase 4 (DPP-4), would have synergistic effects on levels of intact GLP-1. In two open-labeled clinical trials, a total of 16 healthy men received a standardized meal (34% carbohydrates, 45% fat, 21% protein) combined with a prior single dose of sacubitril (194mg)/valsartan(206mg), sitagliptin (2x100mg), sacubitril(194mg)/valsartan(206mg) and sitagliptin (2x100mg), or control. Sacubitril/valsartan increased postprandial plasma concentrations of total GLP-1 by 67% and had synergistic effects on intact GLP-1 when combined with sitagliptin. Concentrations of glucose, insulin, and GIP were not significantly changed upon sacubitril/valsartan treatment. Sacubitril/valsartan synergistically protects intact GLP-1 when combined with a DPP-4 inhibitor pointing to a therapeutic potential for the combination in patients with cardiovascular disease and diabetes. Disclosure N.J. Wewer Albrechtsen: Research Support; Self; Mercodia, Novo Nordisk A/S. Speaker's Bureau; Self; Merck Sharp & Dohme Corp. P.D. Mark: None. L.H. Hansen: None. U.Ø. Andersen: None. B. Hartmann: None. R.D. Carr: Employee; Self; Merck & Co., Inc. Speaker's Bureau; Spouse/Partner; Eli Lilly and Company, Merck & Co., Inc. F. Gustafsson: Advisory Panel; Self; Abbott, Corvia Medical, Inc. Consultant; Self; Bayer AG. Employee; Spouse/Partner; Novo Nordisk A/S. Research Support; Self; Novo Nordisk Foundation. Speaker's Bureau; Self; Novartis AG, Novo Nordisk A/S. C.F. Deacon: Employee; Spouse/Partner; Merck Sharp & Dohme Corp. Stock/Shareholder; Spouse/Partner; Merck & Co., Inc. Other Relationship; Self; Eli Lilly and Company, Merck Sharp & Dohme Corp. J.J. Holst: Advisory Panel; Self; Novo Nordisk A/S. J.P. Gøtze: None. P. Plomgaard: None. Funding Rigshopitalet

Biomarkers in MedicineVol. 12, No. 9 CommentaryCommentary: measurement of biomarkers in medicineJens P Goetze, Lasse H Hansen, Dijana Terzic, Peter D Mark, Nicolai J Wewer Albrechtsen, Peter Plomgaard & Jens F RehfeldJens P Goetze*Author for correspondence: Tel.: +45 3545 2202; Fax: +45 3545 2880; E-mail Address: JPG@dadlnet.dk Department of Clinical Biochemistry, Faculty of Health & Medical Sciences, University of Copenhagen, Copenhagen, DenmarkSearch for more papers by this author, Lasse H Hansen Department of Clinical Biochemistry, Faculty of Health & Medical Sciences, University of Copenhagen, Copenhagen, DenmarkSearch for more papers by this author, Dijana Terzic Department of Clinical Biochemistry, Faculty of Health & Medical Sciences, University of Copenhagen, Copenhagen, DenmarkSearch for more papers by this author, Peter D Mark Department of Clinical Biochemistry, Faculty of Health & Medical Sciences, University of Copenhagen, Copenhagen, DenmarkSearch for more papers by this author, Nicolai J Wewer Albrechtsen Department of Clinical Biochemistry, Faculty of Health & Medical Sciences, University of Copenhagen, Copenhagen, DenmarkSearch for more papers by this author, Peter Plomgaard Department of Clinical Biochemistry, Faculty of Health & Medical Sciences, University of Copenhagen, Copenhagen, DenmarkSearch for more papers by this author & Jens F Rehfeld Department of Clinical Biochemistry, Faculty of Health & Medical Sciences, University of Copenhagen, Copenhagen, DenmarkSearch for more papers by this authorPublished Online:25 Jul 2018https://doi.org/10.2217/bmm-2018-0210AboutSectionsView ArticleView Full TextPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinkedInReddit View articleKeywords: chromogranin Agastrinimmunoassaymeasurementnatriuretic peptideReferences1 Rehfeld JF, Gingras MH, Bardram L, Hilsted L, Goetze JP, Poitras P. The Zollinger–Ellison syndrome and mismeasurement of gastrin. Gastroenterol. 140, 1444–1453 (2011).Crossref, CAS, Google Scholar2 Rehfeld JF, Bardram L, Hilsted L, Poitras P, Goetze JP. Pitfalls in diagnostic gastrin measurements. Clin. Chem. 58, 831–836 (2012).Crossref, Medline, CAS, Google Scholar3 Saenger AK, Rodriguez-Fraga O, Ler R et al. Specificity of B-type natriuretic peptide assays: cross-reactivity with different BNP, NT-proBNP, and proBNP Peptides. Clin. Chem. 63, 351–358 (2017).Crossref, Medline, CAS, Google Scholar4 Goetze JP, Rehfeld JF. Impact of assay epitope specificity in gastrinoma diagnosis. Clin. Chem. 49, 333–334 (2003).Crossref, Medline, CAS, Google Scholar5 Yandle T, Fisher S, Espiner E, Richards M, Nicholls G. Validating aminoterminal BNP assays: a word of caution. Lancet 353, 1068–1069 (1999).Crossref, Medline, CAS, Google Scholar6 Rehfeld JF, Hansen JS, Sonne DP, Goetze JP. Biomarkers and immunoassay kits: a matter of growing concern. Biomarkers Med. 9, 623–624 (2015).Link, CAS, Google ScholarFiguresReferencesRelatedDetails Vol. 12, No. 9 Follow us on social media for the latest updates Metrics Downloaded 79 times History Received 18 June 2018 Accepted 21 June 2018 Published online 25 July 2018 Published in print September 2018 Information© 2018 Future Medicine LtdKeywordschromogranin Agastrinimmunoassaymeasurementnatriuretic peptideFinancial & competing interests disclosureThe authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.No writing assistance was utilized in the production of this manuscript.PDF download

BACKGROUND:Decreased concentrations of pro-atrial-derived natriuretic peptides (proABP) in plasma have been associated with obesity and suggested as a predictor of type 2 diabetes. However, assays for measuring proANP are generally aimed to quantitate higher concentrations of proANP associated with cardiac disease. Therefore, we aimed to measure plasma proANP concentrations in a non-obese Scandinavian reference material and evaluate potential associations of plasma proANP with body mass index (BMI) and plasma glucose, respectively. METHODS:We report an optimized processing-independent assay (PIA) for proANP in the lower concentration range. The assay was optimized by raising the amount of radioactive tracer and modifying the mixing ratio of resuspended plasma and buffer. Blood samples from a Scandinavian plasma cohort of 693 healthy subjects were then analyzed and age and gender-specific reference intervals were determined. RESULTS:Simple linear regression analyses of proANP and both BMI and plasma glucose in fasting subjects displayed insignificant associations. Multiple regression analyses supported these findings. However, a higher median plasma concentration of proANP was noted among women <50 years compared to men, whereas no gender-specific differences were seen in other age groups. CONCLUSIONS:Our results show that in a healthy non-obese population, BMI and plasma glucose in fasting subjects do not affect plasma proANP concentrations. Our method should be considered for future studies on low proANP concentration studies, e.g. in obesity and diabetes.