Comparison of novel pro-BNP1–108 and standard BNP assays in heart failure patients

Impact of high intensity interval and moderate continuous training on plasma ratios of ProBNP1-108/BNP1-32 and NT-pro-BNP1-76/BNP1-32 after coronary artery bypass grafting surgery

Background: ProBNP1-108/BNP1-32, and NT-pro-BNP1-76/BNP1-32 ratios are significant indices for predicting complications after coronary artery bypass grafting (CABG) surgery. However, the effect of aerobic training types on these biomarkers has not been fully understood. So, the current study aimed to determine the impact of aerobic interval and continuous training programs on plasma ratios of ProBNP1-108/BNP1-32 and NT-pro-BNP1-76/BNP1-32 after coronary artery bypass grafting surgery. Method: 36 patients were selected purposive (27 men and 9 women with mean of age 60.32 ± 5.81 years, height 164.64 ± 9.25 cm, weight 73.86 ± 14.23 kg, fat 32.30 ± 4.28, SBP 142.67 ± 6.49, DBP 84.5 ± 5.16 mmHg in seated position at rest situation and functional capacity of 7.08 ± 2.49 METs) and then divided randomly into three groups: control (C) group (without training program) moderate continuous training (MCT) and high intensity interval training (HIIT) (exercise training program was performed 3 days/week for 8 weeks) with intensities 65%-80% and 80%-95% of reserve heart rate in order. Blood samples were taken 48 h before the first session and 48 h after the last training session to measure the plasma levels of ProBNP1-108, corin enzyme, BNP1-32, and NT-pro-BNP1-76 using the enzyme-linked immunosorbent assay (ELISA) technique. Wilcoxin and kruskal wallis tests were used for analyzing data. Results: The plasma corin enzyme was increased, and the ratios of proBNP1-108/BNP1-32 and NT-pro-BNP1-76/BNP1-32 were reduced in both training groups in compared with control group (p = 0.004, p = 0000, p = 0.016, p = 0.003, p = 0.009, and p = 0.016) when there was no significant difference was found between training groups (p = 0.074, p = 450, and p = 0.295). Conclusion: Both high intensity interval training and moderate continuous training in compared with inactivity have positive effects on ratios of ProBNP1-108/BNP1-32, NT-pro-BNP1-76/BNP1-32 and could be effective to promote the health of coronary arteries and prevention of HF in post-CABG patients.

Biomarkers assessment in patients with Chagas disease and systemic arterial hypertension

Chagas disease (ChD) and systemic arterial hypertension (SAH) are two severe comorbidities that lead to mortality and a reduction in people's quality of life, with an impact on public health. The aim of this study was to quantify the biomarkers of cardiac injury in patients with ChD and SAH. Eighty patients were divided into four groups: 20 hypertensive patients, 20 ChD-hypertensive patients, 20 ChD patients, and 20 normotensive volunteers; all of them came from outpatient's public health services. Among the evaluated markers for cardiac lesions (creatine kinase, creatine kinase-MB isoform, myoglobin, high-sensitive cardiac troponin T[hs-cTnT], B-type natriuretic peptide [BNP], and C-reactive protein), hs-cTnT and BNP were the most appropriate. Importantly, our results showed that the cut off point for hs-cTnT could be < 0.007 ng/mL, which could lead to the early detection of myocardial lesions. The BNP and hs-cTnT levels were high only in the ChD and ChD-hypertensive patient groups, suggesting that Chagas' disease may play an important role in the increase of these biomarkers. ChD patients, hypertensive or not, with cardiac or cardiodigestive involvement presented significantly higher values of hs-cTnT (p < 0.001) and BNP (p = 0.001) than ChD patients with indeterminate and digestive forms, which strengthens the validation of these markers for the follow-up of clinical cardiac form of ChD. This study suggests that the BNP and hs-cTnT can be used as possible indirect biomarkers of cardiac damage. In addition, the reference values of these biomarkers in Chagas and hypertensive cardiomyopathies should be better understood with further studies.

B-type Natriuretic Peptide circulating forms: Analytical and bioactivity issues

B-type Natriuretic Peptide (BNP), A-type and C-type Natriuretic Peptides (ANP and CNP) comprise a family of peptides that retain a common ring structure and conserved amino acid sequences. All are present in the heart, but only BNP and ANP are regarded as primarily cardiac secretory products. BNP and ANP, acting through a guanylyl cyclase receptor, increase sodium and water excretion by the kidney, induce vasodilation, reduce blood pressure, counteract the bioactivity of the renin-angiotensin-aldosterone and sympathetic nervous systems and possess anti-hypertrophic and anti-fibrotic properties. BNP is synthesised in cardiomyocytes first as the precursor peptide preproBNP. Removal of the signal peptide from preproBNP produces proBNP which is cleaved to produce the biologically active carboxy-terminal BNP peptide and the inactive N-terminal fragment, NT-proBNP. BNP, NT-proBNP, proBNP and the C-terminal portion of the BNP signal peptide have been detected in human plasma as well as multiple sub-forms including truncated forms of BNP and NT-proBNP, as well as variable glycosylation of NT-proBNP and proBNP. The origin of these circulating forms, their potential bioactivity and their detection by current analytical methods are presented in this review.

Depletion of proBNP1-108 in patients with heart failure prevents cross-reactivity with natriuretic peptides

BACKGROUND

After synthesis by cardiomyocytes, precursor proBNP1-108 is cleaved into NT-proBNP and BNP. Recently, cross-reactivity between these assays was discussed. The aim of this study was to characterize the cross-reactivities, through a new biochemical innovative approach consisting in the total depletion of the circulating proBNP1-108 in patients with heart failure (HF).

METHODS

This prospective study included 180 patients with chronic HF. BNP and NT-proBNP were dosed with commercial kits. ProBNP1-108 was determined using an ELISA research assay specific to the precursor. ProBNP1-108 depletion was performed by immunocapture with a specific antibody targeting exclusively the ProBNP1-108 hinge region. ProBNP1-108, BNP and NT-proBNP levels were determined before and after depletion using this process in HF patients.

RESULTS

Mean age was 74.34 +/-12.5 y, and 69% of patients were males. NYHA classes II and III were the most frequent (32% and 45% respectively). Before depletion, ProBNP1-108, NT-proBNP and BNP levels were 316.8+/-265.9 pg/ml; 6,054.0+/-11,539 pg/ml and 684.3+/-82.1 pg/ml respectively, and were closely correlated with NHYA classes. After immuno-depletion, proBNP1-108 was decreased in mean by 96% (p<0.0001), BNP by 53% (p<0.0001) and NT-proBNP by 5%. The relationship between BNP or NT-proBNP and NHYA classes remained unchanged.

CONCLUSION

Current BNP and NT-proBNP assays measured as well proBNP molecule. This cross reactivity percentage has been controversial. Thanks to the removal of circulating proBNP1-108 with our immunodepletion process, we are now able to assess the remaining "true" BNP and NT-proBNP molecules and further evaluate their clinical relevance.

Phenotypic profiling of cognitive impairment risk among patients with heart failure: a literature review of the usefulness of cardiac-related variables

BACKGROUND

Mild cognitive impairment among patients with heart failure can be subtle. Heart failure-related variables such as ejection fraction, low systolic blood pressure and functional status are reportedly associated with cognitive impairment among heart failure patients. The purpose of this literature review was to examine the value of cardiac variables commonly assessed during heart failure-related hospitalizations for a phenotypic profile of the risk of cognitive impairment.

METHOD

A literature review of primary research studies was conducted. Electronic databases (PubMed and CINAHL) were searched using the keywords heart failure, blood pressure, ejection fraction, functional status, and B-type natriuretic peptide (BNP) in combination with the terms cognition, cognitive function, cognitive dysfunction, and cognitive impairment.

RESULTS

Thirty-seven studies met the inclusion criteria. Evidence supports the potential utility of lower ejection fraction, lower blood pressure and functional status and elevated B-type natriuretic peptide as a phenotypic profile for an increased risk of cognitive impairment.

IMPLICATIONS

If the risk for cognitive impairment is suspected, specific evaluations of cognition can be performed. For community-dwelling heart failure patients with mild cognitive impairment, more intense interventions to support self-care, increased family involvement and more frequent follow up may be necessary.

BNP molecular forms and processing by the cardiac serine protease corin

The cardiac hormone, B-type natriuretic peptide (BNP), is one of human natriuretic peptides which possesses cardiorenal protective actions and is used as a therapeutic and a biomarker for heart failure (HF). Its prohormone, proBNP1_108, is processed by the proNPs convertases, corin or furin, to inactive NT-proBNP1_76 and active BNP1-32. Paradoxically, circulating NT-proBNP and BNP are elevated in HF leading to the use of BNP as a sensitive and predictive marker of HF. This paradox may be explained by the "nonspecific" nature of conventional assays and/or a relative deficiency state of "active BNP" as characterized by an increase in inactive proBNP_108 and a decrease in active BNP1-32. Therefore, understanding the regulation of proBNP1_108 processing and the role of the convertase corin may be important in understanding the physiology of HF. Corin is expressed in heart and kidney and may play an important role in regulating blood pressure and remodeling of the heart. The processing of proBNP1_108 by corin may be controlled by O-linked glycosylation of proBNP1-108. A potential impairment of proBNP1lo8 processing in HF may be linked to dysregulation of the convertase corin, which may offer therapeutic opportunities to control proBNPlo0s processing and its activation in HF.