Prognostic significance of active and modified forms of endothelin 1 in patients with heart failure with reduced ejection fraction

Endothelin and the Cardiovascular System: The Long Journey and Where We Are Going

Simple Summary

In this review, we describe the basic functions of endothelin and related molecules, including their receptors and enzymes. Furthermore, we discuss the important role of endothelin in several cardiovascular diseases, the relevant clinical evidence for targeting the endothelin pathway, and the scope of endothelin-targeting treatments in the future. We highlight the present uses of endothelin receptor antagonists and the advancements in the development of future treatment options, thereby providing an overview of endothelin research over the years and its future scope.

Abstract

Endothelin was first discovered more than 30 years ago as a potent vasoconstrictor. In subsequent years, three isoforms, two canonical receptors, and two converting enzymes were identified, and their basic functions were elucidated by numerous preclinical and clinical studies. Over the years, the endothelin system has been found to be critical in the pathogenesis of several cardiovascular diseases, including hypertension, pulmonary arterial hypertension, heart failure, and coronary artery disease. In this review, we summarize the current knowledge on endothelin and its role in cardiovascular diseases. Furthermore, we discuss how endothelin-targeting therapies, such as endothelin receptor antagonists, have been employed to treat cardiovascular diseases with varying degrees of success. Lastly, we provide a glimpse of what could be in store for endothelin-targeting treatment options for cardiovascular diseases in the future.

Circulating endothelin-1 levels are positively associated with chronic kidney disease in women but not in men: a longitudinal study in the Vara-Skövde cohort

Background

The vasoconstricting peptide endothelin-1 (ET-1) is associated with endothelial dysfunction. The aim of this paper was to investigate whether circulating ET-1 levels predicts chronic kidney disease (CKD) in a prospective population study.

Methods

In 2002–2005, 2816 participants (30–74 years) were randomly selected from two municipalities in South-Western Sweden and followed up in a representative sample of 1327 individuals after 10 years. Endothelin-1 levels were assessed at baseline. Outcome was defined as CKD stage 3 or above based on eGFR < 60 mL/min/1.73m². Those 1314 participants with successful analysis of ET-1 were further analyzed using binary logistic regression.

Results

At follow-up, 51 (8%) men and 47 (7,8%) women had CKD stage 3 and above. Based on levels of ET-1 the population was divided into quintiles showing that women in the highest quintile (n = 132) had a significantly increased risk of developing CKD during the follow up period (OR = 2.54, 95% CI:1.19–5.45, p = 0.02) compared with the other quintiles (1–4). The association was borderline significant after adjusted for age, current smoking, alcohol consumption, hypertension, diabetes, BMI, high- sensitive CRP and LDL-cholesterol (OR = 2.25, 95% CI:0.97–5.24, p = 0.06). No significant differences were observed between quintiles of ET-1 and development of CKD in men (NS).

Conclusions

High levels of ET-1 are associated with development of CKD in women.

Cardiac biomarkers for risk stratification of arrhythmic death in patients with heart failure and reduced ejection fraction

Objectives. Patients with heart failure and reduced left ventricular ejection fraction (HFrEF) are prone to ventricular tachyarrhythmias. We tested whether biomarkers C-terminal Endothelin 1 (CT-ET1), midregional pro atrial natriuretic peptide (MR-proANP) and midregional pro adrenomedullin (MR-proADM) might improve risk stratification for arrhythmic death.Methods: This prospective observational study included 160 heart failure patients with ischaemic cardiomyopathy (ICM) or non-ischaemic, dilated cardiomyopathy (DCM) and 30 control patients without heart disease. Primary endpoint was arrhythmic death (ArD) or resuscitated cardiac arrest (resCA).Results: A total of 61 patients died during the median follow-up of 7.0 [5.2-8.4] years. An ArD or resCA was observed in 48 patients. Plasma levels of CT-ET1 (p = 0.002), MR-proANP (p < 0.001) and MR-proADM (p = 0.013) were significantly higher in ICM or DCM patients compared to controls. MR-proANP levels in ICM patients were associated with a significantly increased risk for ArD or resCA (hazard ratio (HR) = 1.42, [95%CI: 1.08-1.85], p = 0.011) in a multivariable Cox regression model. Plasma levels of CT-ET1 (HR = 1.07 [0.98-1.17], p = 0.113) and MR-proADM (HR = 1.80 [0.92-3.55], p = 0.087) were not associated with ArD or resCA in ICM patients. No significant association with ArD or resCA was found in DCM patients. Multivariable Cox regression showed that CT-ET1 (HR = 1.14 [1.07-1.22], p < 0.001), MR-proANP (HR = 1.64 [1.29-2.08], p < 0.001) and MR-pro ADM (HR = 2.06 [1.12-3.77], p = 0.020) were associated with a higher risk for overall mortality.Conclusion: Patients with HFrEF had elevated levels of CT-ET1, MR-proANP and MR-proADM. Plasma levels of MR-proANP are useful as predictor for arrhythmic death in patients with ICM.

Leg heat therapy improves perceived physical function but does not enhance walking capacity or vascular function in patients with peripheral artery disease

A single session of leg heat therapy (HT) has been shown to elicit increases in leg blood flow and reduce blood pressure (BP) and the circulating levels of endothelin-1 (ET-1) in patients with symptomatic peripheral artery disease (PAD). We assessed whether 6 wk of supervised leg HT (3 times/wk) with water-circulating trousers perfused with water at 48°C improved 6-min walk distance in individuals with PAD compared with a sham treatment. Secondary outcomes included the assessment of leg vascular function, BP, quality of life, and serum ET-1 and nitrite plus nitrate (NOx) levels. Of 32 PAD patients randomized, 30 [age: 68 ± 8 yr; ankle-brachial index (ABI): 0.6 ± 0.1] completed the 3- and 6-wk follow-ups. Participants completed 98.7% of the treatment sessions. Compared with the sham treatment, exposure to HT did not improve 6-min walk distance, BP, popliteal artery reactive hyperemia, cutaneous microvascular reactivity, resting ABI, or serum NOx levels. The change from baseline to 6 wk in scores of the physical functioning subscale of the 36-item Short Form Health Survey was significantly higher in the HT group (control -6.9 ± 10 vs. HT 6.8 ± 15; 95% confidence interval: 2.5-24.3, P = 0.017). Similarly, the change in ET-1 levels after 6 wk was different between groups, with the HT group experiencing a 0.4 pg/mL decrease (95% confidence interval: -0.8-0.0, P = 0.03). These preliminary results indicate that leg HT may improve perceived physical function in symptomatic PAD patients. Additional, larger studies are needed to confirm these findings and determine the optimal treatment regimen for symptomatic PAD patients.NEW & NOTEWORTHY This is the first sham-controlled study to investigate the effects of leg heat therapy (HT) on walking performance, vascular function, and quality of life in patients with peripheral artery disease (PAD). Adherence to HT was high, and the treatment was well tolerated. Our findings revealed that HT applied with water-circulating trousers evokes a clinically meaningful increase in perceived physical function and reduces the serum concentration of the potent vasoconstrictor endothelin-1 in patients with PAD.

[Role of markers of inflammation and endothelial dysfunction in the prognosis of the development of cardiovascular complications in patients with coronary artery disease and metabolic syndrome after coronary stenting]

Aim To study the role of inflammation markers and endothelial dysfunction in predicting the risk of cardiovascular event following a percutaneous coronary intervention (PCI) in patients with ischemic heart disease (IHD) and metabolic syndrome (MS).Materials and methods 80 patients (72 men; median age, 56 (50;63) years) with IHD and PCI were evaluated. Based on the presence of MS according to NCEP-ATP III criteria, patients were divided into two groups, group 1 without MS (n=32) and group 2 with MS (n=48). The control age- and sex-matched group included 15 people without cardiovascular diseases. Serum concentrations of tumor necrosis factor α (TNFα), interleukin 6 (IL-6), IL-10, lipoprotein-associated phospholipase A2 (LP-PLA2), and endothelin 1 were measured by enzyme-linked immunosorbent assay (ELISA). Patients were followed up for 12 months after PCI with evaluation of the incidence of adverse cardiovascular events. Statistical analysis was performed with Statistica 10.0 and Medcalc 19.2.6 software. Differences between variables were considered statistically significant at р&lt;0.05. Potential predictors were determined by the ROC analysis with construction of ROC curves, calculation of AUC (area under the curve), identification of COP (cut-off point by the Youden's index), and sensitivity (Se) and specificity corresponding to the COP.Results Patients with MS had statistically significantly higher serum levels of inflammatory markers than patients of the control group. Concentration of the intravascular inflammation marker, PL-PLA2, was 2.7 times higher in group 1 and 5.1 times higher in group 2 than in the control group (р&lt;0.001). Concentrations of endothelin 1 were 1.9 times higher in group 1 and 3.7 times higher in the MS group compared to the control. At one year after PCI, the incidence of adverse outcomes in the form of cardiovascular events was higher for patients with MS: 10 (20.8 %) cases of stent restenosis and 13 (27.1 %) episodes of coronary atherosclerosis progression according to results of repeated coronarography vs. 2 (6.3%) restenosis cases (χ2-10.853; р=0.002) and 2 (6.3%) episodes of atherosclerosis progression (χ2-23.651; р=0.001) for patients without MS. The groups did not differ in rates of myocardial infarction and cardiac death. The most significant predictors of unfavorable prognosis were LP-PLA2 concentration &gt;983.83 ng/ml (area under the ROC curve, 0.867; sensitivity, 80 %; specificity, 100%; р&lt;0.001) and endothelin 1 overexpression &gt;0.852 fmol/ml (area under the ROC curve, 0.885; sensitivity, 85.5 %; specificity, 83.6 %; р&lt;0.001).Conclusion Patients with MS were characterized by more pronounced imbalance of pro- and anti-inflammatory factors. Concentrations of LP-PLA2 &gt;983.83 ng/ml and endothelin 1 &gt;0.852 fmol/ml were shown to be predictors of unfavorable prognosis for patients with IHD and MS after PCI with coronary stenting.

Endothelin-1, cardiac morphology, and heart failure: the MESA angiogenesis study

BACKGROUND

Circulating levels of endothelin-1 (ET1) are elevated in heart failure and predict poor prognosis. However, it is not clear whether ET1 elevation is an adaptive response, maladaptive response, or an epiphenomenon of heart failure. In this study, we evaluated the relationships between ET1, cardiac morphology, and incident heart failure or cardiovascular death in participants with no evidence of clinical cardiovascular disease at the time ET1 was measured.

METHODS AND RESULTS

ET1 was measured in 1,361 participants in the Multi-Ethnic Study of Atherosclerosis Angiogenesis Sub-Study. As suggested by linear regression, participants with lower circulating ET1 levels tended to be older, non-white, more likely to have smoked heavily, and less likely to report intentional exercise. Participants with higher ET1 levels had smaller left ventricular end-diastolic volumes (8.9 ml smaller per log increase in ET1, 95% confidence interval 17.1-0.7, p = 0.03) with an increased left ventricular ejection fraction (2.8% per log increase in ET1, 95% confidence interval 0.5%-5.2%, p = 0.02). As suggested by Cox Proportional Hazards estimates, participants with higher ET1 levels had a lower risk for the composite outcome of heart failure or cardiovascular death in models that were unadjusted or had limited adjustment (p = 0.03 and p = 0.05, respectively). Lower risk for heart failure with higher ET1 levels could not be clearly shown in a model including health behaviors.

CONCLUSIONS

These results suggest, but do not confirm, that elevated levels of circulating ET1 are associated with a more favorable cardiac phenotype. The relationship between ET1 and outcomes was not fully independent of one or more covariates.

Endothelin: 30 Years From Discovery to Therapy

Discovered in 1987 as a potent endothelial cell-derived vasoconstrictor peptide, endothelin-1 (ET-1), the predominant member of the endothelin peptide family, is now recognized as a multifunctional peptide with cytokine-like activity contributing to almost all aspects of physiology and cell function. More than 30 000 scientific articles on endothelin were published over the past 3 decades, leading to the development and subsequent regulatory approval of a new class of therapeutics-the endothelin receptor antagonists (ERAs). This article reviews the history of the discovery of endothelin and its role in genetics, physiology, and disease. Here, we summarize the main clinical trials using ERAs and discuss the role of endothelin in cardiovascular diseases such as arterial hypertension, preecclampsia, coronary atherosclerosis, myocardial infarction in the absence of obstructive coronary artery disease (MINOCA) caused by spontaneous coronary artery dissection (SCAD), Takotsubo syndrome, and heart failure. We also discuss how endothelins contributes to diabetic kidney disease and focal segmental glomerulosclerosis, pulmonary arterial hypertension, as well as cancer, immune disorders, and allograft rejection (which all involve ET_A autoantibodies), and neurological diseases. The application of ERAs, dual endothelin receptor/angiotensin receptor antagonists (DARAs), selective ET_B agonists, novel biologics such as receptor-targeting antibodies, or immunization against ET_A receptors holds the potential to slow the progression or even reverse chronic noncommunicable diseases. Future clinical studies will show whether targeting endothelin receptors can prevent or reduce disability from disease and improve clinical outcome, quality of life, and survival in patients.

Sildenafil Treatment in Heart Failure With Preserved Ejection Fraction: Targeted Metabolomic Profiling in the RELAX Trial

Importance

Phosphodiesterase-5 inhibition with sildenafil compared with a placebo had no effect on the exercise capacity or clinical status of patients with heart failure with preserved ejection fraction (HFpEF) in the PhosphodiesteRasE-5 Inhibition to Improve Clinical Status and Exercise Capacity in Diastolic Heart Failure with Preserved Ejection Fraction (RELAX) clinical trial. Metabolic impairments may explain the neutral results.

Objective

To test the hypothesis that profiling metabolites in the RELAX trial would clarify the mechanisms of sildenafil effects and identify metabolites associated with clinical outcomes in HFpEF.

Design, Setting, and Participants

Paired baseline and 24-week plasma samples of 160 stable outpatient individuals with HFpEF enrolled in the RELAX clinical trial were analyzed using flow injection tandem mass spectrometry (60 metabolites) and conventional assays (5 metabolites).

Interventions

Sildenafil (n = 79) or a placebo (n = 81) administered orally at 20 mg, 3 times daily for 12 weeks, followed by 60 mg, 3 times daily for 12 weeks.

Main Outcomes and Measures

The primary measure was metabolite level changes between baseline and 24 weeks stratified by treatments. Secondary measures included correlations between metabolite level changes and clinical biomarkers and associations between baseline metabolite levels and the composite clinical score.

Results

No metabolites changed between baseline and 24 weeks in the group treated with a placebo; however, 7 metabolites changed in the group treated with sildenafil, including decreased amino acids (alanine and proline; median change [25th-75th], -38.26 [-100.3 to 28.19] and -28.24 [-56.29 to 12.08], respectively; false discovery rate-adjusted P = .01 and .03, respectively), and increased short-chain dicarboxylacylcarnitines glutaryl carnitine, octenedioyl carnitine, and adipoyl carnitine (median change, 6.19 [-3.37 to 14.18], 2.72 [-3 to 12.57], and 10.72 [-11.23 to 29.57], respectively; false discovery rate-adjusted P = .01, .04, and .05, respectively), and 1 long-chain acylcarnitine metabolite (palmitoyl carnitine; median change, 7.83 [-5.64 to 26.99]; false discovery rate-adjusted P = .03). The increases in long-chain acylarnitine metabolites and short-chain dicarboxylacylcarnitines correlated with increases in endothelin-1 and creatinine/cystatin C, respectively. Higher baseline levels of short-chain dicarboxylacylcarnitine metabolite 3-hydroxyisovalerylcarnitine/malonylcarnitine and asparagine/aspartic acid were associated with worse clinical rank scores in both treatment groups (β, -96.60, P = .001 and β, -0.02, P = .01; after renal adjustment, P = .09 and .02, respectively).

Conclusions and Relevance

Our study provides a potential mechanism for the effects of sildenafil that, through adverse effects on mitochondrial function and endoplasmic reticulum stress, could have contributed to the neutral trial results in RELAX. Short-chain dicarboxylacylcarnitine metabolites and asparagine/aspartic acid could serve as biomarkers associated with adverse clinical outcomes in HFpEF.

Endothelin-1 levels and cardiovascular events

Circulating plasma levels of endothelin-1 and related peptides generated during the synthesis of endothelin-1 from its precursor molecule pre-proendothelin-1 have been widely studied as potential risk markers for cardiovascular events. The associations of endothelin-1 with aging, blood pressure, lung function, and chronic kidney disease have been described, as have relations between endothelin-1 levels and evidence of cardiac remodeling, including increased left atrial diameter and increased left ventricular mass. Endothelin-1 has been studied as a predictor of and prognostic marker in coronary artery disease, myocardial infarction, and heart failure. The relationship of endothelin-1 levels to mortality in the general population has also been explored. This review examines the current state of knowledge of circulating endothelin-1 levels as they relate to cardiovascular events and prognosis, and explores future directions for research, including using endothelin-1 or related peptide levels to guide personalized treatment regimens and to select patients for primary prevention strategies.

Circulating biomarkers of left ventricular hypertrophy in pediatric coarctation of the aorta

OBJECTIVE

Patients undergoing surgical repair of aortic coarctation have a 50% risk of pathologic left ventricular remodeling (increased left ventricular mass or relative wall thickness). Endothelin 1, ST2, galectin 3, norepinephrine and B-natriuretic peptide are biomarkers that have been associated with pathologic LV change in adult populations but their predictive value following pediatric coarctation repair are not known.

HYPOTHESIS

Biomarker levels at coarctation repair will predict persistent left ventricular remodeling at 1-year follow up.

DESIGN

Prospective, cohort study of 27 patients' age 2 days-12 years with coarctation of the aorta undergoing surgical repair. Echocardiograms were performed preoperation, postoperation, and at 1-year follow-up. Plasma biomarker levels were measured at the peri-operative time points. Association between biomarker concentrations and echocardiographic parameters was assessed.

RESULTS

Neither left ventricular mass index nor relative wall thickness varied from pre-op to post-op. At pre-op, relative wall thickness was elevated in 52% and left ventricular mass index was elevated in 22%; at follow-up, relative wall thickness was elevated in 13% and left ventricular mass index was elevated in 8%. Presence of residual coarctation did not predict left ventricular remodeling (AUC 0.59; P > .05). Multivariable receiver operating characteristic curve combining pre-op ST2 and endothelin 1 demonstrated significant predictive ability for late pathologic left ventricular remodeling (AUC 0.85; P = .02).

CONCLUSIONS

Persistent left ventricular hypertrophy and abnormal relative wall thickness at intermediate-term follow-up was rare compared to previous studies. A model combining pre-op endothelin 1 and ST2 level demonstrated reasonable accuracy at predicting persistent abnormalities in this cohort. Larger studies will be needed to validate this finding and further explore the mechanism of persistent left ventricular remodeling in this population.

Endothelin-1 Measurement in Patients Undergoing Diagnostic Coronary Angiography—Results from the Catheter Sampled Blood Archive in Cardiovascular Diseases (CASABLANCA) Study

BACKGROUND

Endothelin-1 (ET-1) is a vasoconstrictor produced by vascular endothelial cells and may play a role in risk for development of coronary artery disease (CAD) and heart failure (HF). In a cohort of 1084 patients referred for coronary angiography, we investigated cross-sectional associations between ET-1 concentrations and prevalent CAD, as well as value of ET-1 for prognostication of future cardiovascular events.

METHODS

Associations between ET-1 and presence/severity of CAD were assessed. Patients were followed for a median of 4 years for outcomes including incident HF, myocardial infarction (MI), cardiovascular mortality, and all-cause mortality.

RESULTS

The median concentration of ET-1 was 2.57 ng/L. Patients with ET-1 concentrations above the median were more likely to have higher risk clinical features. Among those without prevalent MI at presentation, ET-1 concentrations were not associated with presence or severity of CAD. In adjusted Cox proportional hazards analyses, log-transformed ET-1 concentrations predicted incident HF [hazard ratio (HR) = 1.51 per increase in log-SD; 95% CI, 1.06–2.15; P = 0.02] and all-cause mortality (HR = 1.61 per increase in log-SD; 95% CI, 1.03–2.53; P = 0.04). Concentrations of ET-1 above the median were associated with shorter time to incident HF, MI, cardiovascular mortality, all-cause mortality, and the composite of incident HF/MI/cardiovascular mortality (all log-rank P &lt; 0.001).

CONCLUSIONS

Despite epidemiologic links to CAD, we found no cross-sectional association between biologically active ET-1 and prevalent coronary atherosclerosis in an at-risk population referred for coronary angiography. Increased ET-1 concentrations independently predict incident HF and death and are associated with more near-term cardiovascular events.

Topiramate Reduces Aortic Cross-Clamping-Induced Lung Injury in Male Rats

BACKGROUND

Topiramate (TPM) decreases cytokine release and generation of reactive oxygen species (ROS). Cytokine and endothelin-1 (ET-1) secretion and ROS formation play an important role in ischemia-reperfusion (I/R) injury. We aimed to evaluate whether TPM prevents damage occurring in lung tissue during I/R.

MATERIALS AND METHODS

A total of 27 Wistar albino rats were divided into three groups of nine. To the I/R group, two hours of ischemia via infrarenal abdominal aorta cross-ligation and then two hours of reperfusion process were applied. TPM (100 mg/kg/day) orally for seven days was administered in the TPM treatment group. After the last dose of TPM treatment, respectively, two hours of ischemia and two hours of reperfusion were applied in this group.

RESULTS

Tumor necrosis factor-alpha (TNF-α) (p < 0.05), malondialdehyde (MDA) (p < 0.05), myeloperoxidase (MPO) (p < 0.05) and ET-1 (p < 0.05) levels of TPM treatment group's lung tissue were significantly lower than for the I/R group. Caspase-3 and histopathological damage were rather lower than that of the I/R group.

CONCLUSIONS

During I/R, lung damage occurs due to excessive TNF-α and ET-1 release and ROS generation. TPM could well reduce development of lung damage by decreasing cytokine and ET-1 release and levels of ROS produced.

Plasma endothelin-1-related peptides as the prognostic biomarkers for heart failure: A PRISMA-compliant meta-analysis

BACKGROUND

Most studies reported that high plasma endothelin-1 (ET-1), big ET-1, and C-terminal proET-1 (CT-proET-1) were correlated with poor prognosis of heart failure (HF). However, available evidence remains controversial. To help solve the debate, we collected all the available studies and performed a meta-analysis.

METHODS

We searched the databases covering Embase, PubMed, Ovid, and Web of Science on June 28, 2017. The hazard ratio (HR) or risk ratio (RR) and its 95% confidence intervals (CIs) were collected and calculated by use of a random-effect model. Heterogeneity was assessed by Cochran's Q test, and publication bias was assessed by funnel plots with Egger's and Begg's linear regression test.

RESULTS

Thirty-two studies with 18,497 patients were included in the analysis. Results showed that circulating ET-1, big ET-1, and CT-proET-1 were positively correlated with high risk of adverse outcomes, with pooled RRs (95% CIs) of 2.22 (1.82-2.71, P < .001), 2.47 (1.93-3.17, P < .001), and 2.27 (1.57-3.29, P < .001), respectively. In the subgroup of death as primary outcome, the pooled RRs (95% CIs) were 2.13 (1.68-2.70, P < .001), 2.55 (1.82-3.57, P < .001), and 2.02 (1.39-2.92, P < .001) for ET-1, big ET-1, and CT-proET-1, respectively. No significant publication bias was observed in this study.

CONCLUSION

Our meta-analysis provided evidence that increased plasma levels of ET-1, big ET-1, and CT-proET-1 were associated with poor prognosis or mortality for HF populations.

Involvement of Cytokines in the Pathogenesis of Salt and Water Imbalance in Congestive Heart Failure

Congestive heart failure (CHF) has become a major medical problem in the western world with high morbidity and mortality rates. CHF adversely affects several systems, mainly the kidneys and the lungs. While the involvement of the renin–angiotensin–aldosterone system and the sympathetic nervous system in the progression of cardiovascular, pulmonary, and renal dysfunction in experimental and clinical CHF is well established, the importance of pro-inflammatory mediators in the pathogenesis of this clinical setting is still evolving. In this context, CHF is associated with overexpression of pro-inflammatory cytokines, such as tumor necrosis factor-α, interleukin (IL)-1, and IL-6, which are activated in response to environmental injury. This family of cytokines has been implicated in the deterioration of CHF, where it plays an important role in initiating and integrating homeostatic responses both at the myocardium and circulatory levels. We and others showed that angiotensin II decreased the ability of the lungs to clear edema and enhanced the fibrosis process via phosphorylation of the mitogen-activated protein kinases p38 and p42/44, which are generally involved in cellular responses to pro-inflammatory cytokines. Literature data also indicate the involvement of these effectors in modulating ion channel activity. It has been reported that in heart failure due to mitral stenosis; there were varying degrees of vascular and other associated parenchymal changes such as edema and fibrosis. In this review, we will discuss the effects of cytokines and other inflammatory mediators on the kidneys and the lungs in heart failure; especially their role in renal and alveolar ion channels activity and fluid balance.

A New Clinically Applicable Measure of Functional Status in Patients With Heart Failure: The 60-Foot Walk Test

OBJECTIVES

This study reports the development and predictive value of the 60-foot walk test (60ftWT), a brief functional status measure for patients with heart failure (HF). The goal was to develop a test suitable for clinical settings and appropriate for patients with walking impairments.

BACKGROUND

The 6-min walk test (6MWT) has considerable predictive value, but requires a long walking course and has limited utility in patients with mobility-related comorbidities. A shorter, more clinically practical test is therefore needed.

METHODS

A total of 144 patients (age 57.4 ± 11.4 years; 111 males) with symptomatic HF received baseline assessments using the 60ftWT, 6MWT, and self-reported symptom and health status. Patients were tested 3 months later to determine stability of assessments. HF hospitalizations or death from any cause were recorded for 3.5 years following baseline.

RESULTS

Median 60ftWT completion time was 26 s (interquartile range: 22 to 31 s). Longer 60ftWT time was associated with shorter 6MWT distance (r = -0.75; p < 0.001), and with higher symptom severity at baseline (r = -0.40; p < 0.001). Longer 60ftWT times also predicted increases in 6MWT and symptoms from baseline to 3 months (p < 0.01). Both WTs predicted long-term clinical outcomes, with patients taking longer than 31 s to complete the 60ftWT at greatest risk for HF hospitalization or death (hazard ratio: 2.13; 95% confidence interval: 1.18 to 3.84; p = 0.01).

CONCLUSIONS

The 60ftWT is an easily administered functional status measure that predicts adverse events, symptoms, and health status. It has the potential for considerable clinical utility to help identify patients at risk for future events and to calibrate treatments designed to improve functional status and quality of life.

The association of heart failure-related microRNAs with neurohormonal signaling

Heart failure (HF) is a widely prevalent syndrome imposing a significant burden of morbidity and mortality world-wide. Differential circulating microRNA profiles observed in HF cohorts suggest the diagnostic utility of microRNAs as biomarkers. Given their function in fine tuning gene expression, alternations in microRNA landscape could reflecting the underlying mechanisms of disease and present potential therapeutic targets. Using multiple computational target predicting algorithms together with the luciferase-based reporting platform, the interactions between HF-related microRNAs and the 3' untranslated regions (3'UTRs) of neurohormone associated genes were examined and compared. Our results indicate that although in silico prediction provides an overview of possible microRNA-mRNA target pairs, less than half of the predicted interactions were experimentally confirmed by reporter assays in HeLa cells. Thus, the establishment of microRNA/3'UTR reporters is essential to systemically evaluate the roles of microRNAs for signaling cascades of interest, including cardiovascular neurohormonal signaling. The physiological relevance of HF-related microRNAs on the expression of putative gene targets was further established by using gain-of-function assays in two human cardiac-derived cells. Our findings, for the first time, provide direct evidence of the regulatory effects of HF-related microRNAs on the neurohormonal signaling in cardiac cells. More importantly, our study presents a rational approach to further exploring microRNA profiling data in deciphering the role of microRNA in complex syndromes such as HF. This article is part of a Special Issue entitled: Genetic and epigenetic control of heart failure - edited by Jun Ren & Megan Yingmei Zhang.

Endothelial dysfunction and vascular disease - a 30th anniversary update

The endothelium can evoke relaxations of the underlying vascular smooth muscle, by releasing vasodilator substances. The best-characterized endothelium-derived relaxing factor (EDRF) is nitric oxide (NO) which activates soluble guanylyl cyclase in the vascular smooth muscle cells, with the production of cyclic guanosine monophosphate (cGMP) initiating relaxation. The endothelial cells also evoke hyperpolarization of the cell membrane of vascular smooth muscle (endothelium-dependent hyperpolarizations, EDH-mediated responses). As regards the latter, hydrogen peroxide (H₂ O₂ ) now appears to play a dominant role. Endothelium-dependent relaxations involve both pertussis toxin-sensitive G_i (e.g. responses to α₂ -adrenergic agonists, serotonin, and thrombin) and pertussis toxin-insensitive G_q (e.g. adenosine diphosphate and bradykinin) coupling proteins. New stimulators (e.g. insulin, adiponectin) of the release of EDRFs have emerged. In recent years, evidence has also accumulated, confirming that the release of NO by the endothelial cell can chronically be upregulated (e.g. by oestrogens, exercise and dietary factors) and downregulated (e.g. oxidative stress, smoking, pollution and oxidized low-density lipoproteins) and that it is reduced with ageing and in the course of vascular disease (e.g. diabetes and hypertension). Arteries covered with regenerated endothelium (e.g. following angioplasty) selectively lose the pertussis toxin-sensitive pathway for NO release which favours vasospasm, thrombosis, penetration of macrophages, cellular growth and the inflammatory reaction leading to atherosclerosis. In addition to the release of NO (and EDH, in particular those due to H₂ O₂ ), endothelial cells also can evoke contraction of the underlying vascular smooth muscle cells by releasing endothelium-derived contracting factors. Recent evidence confirms that most endothelium-dependent acute increases in contractile force are due to the formation of vasoconstrictor prostanoids (endoperoxides and prostacyclin) which activate TP receptors of the vascular smooth muscle cells and that prostacyclin plays a key role in such responses. Endothelium-dependent contractions are exacerbated when the production of nitric oxide is impaired (e.g. by oxidative stress, ageing, spontaneous hypertension and diabetes). They contribute to the blunting of endothelium-dependent vasodilatations in aged subjects and essential hypertensive and diabetic patients. In addition, recent data confirm that the release of endothelin-1 can contribute to endothelial dysfunction and that the peptide appears to be an important contributor to vascular dysfunction. Finally, it has become clear that nitric oxide itself, under certain conditions (e.g. hypoxia), can cause biased activation of soluble guanylyl cyclase leading to the production of cyclic inosine monophosphate (cIMP) rather than cGMP and hence causes contraction rather than relaxation of the underlying vascular smooth muscle.

The Effect of Wenxin Keli on the mRNA Expression Profile of Rabbits with Myocardial Infarction

Aims. The molecular mechanisms of Chinese traditional medicine Wenxin Keli (WXKL) were unknown. This study was aimed at exploring the effects of WXKL on the gene expression profile and pathological alteration of rabbits with myocardial infarction. Methods. Twenty male adult rabbits were randomly divided into 4 groups: sham, model, WXKL, and captopril groups. Model, WXKL, and captopril groups underwent the ligation of the left anterior descending coronary artery while sham group went through an identical procedure without ligation. WXKL (817 mg/kg/d), captopril (8 mg/kg/d), and distilled water (to model and sham groups) were administered orally to each group. After 4 weeks, the rabbits were examined with echocardiography and the hearts were taken for expression chip and pathological staining (H&E, Masson, and Tunel) studies. Results. The data revealed that WXKL downregulated genes associated with inflammation (CX3CR1, MRC1, and FPR1), apoptosis (CTSC and TTC5), and neurohumoral system (ACE and EDN1) and upregulated angiogenesis promoting genes such as RSPO3. Moreover, the results also showed that WXKL improved cardiac function and prevented histopathological injury and apoptosis. Conclusion. The present study demonstrated that WXKL might play an important role in inhibiting inflammation, renin-angiotensin system, and apoptosis. It might be a promising Chinese medicine in the treatment of patients with myocardial infarction.

High Altitude and Acute Mountain Sickness and Changes in Circulating Endothelin-1, Interleukin-6, and Interleukin-17a

INTRODUCTION

Hypoxia induces an inflammatory response, which is enhanced by exercise. High altitude (HA) leads to endothelial activation and may be proinflammatory. The relationship between endothelial activation, inflammation, and acute mountain sickness (AMS) and its severity has never been examined.

METHODS

Forty-eight trekkers were studied during a progressive trek at 3833, 4450, and 5129 m at rest postascent (exercise), and then again at rest 24 hours later. Twenty of the subjects were also tested at rest pre- and postexercise at sea level (SL) at 6 weeks preascent. We examined plasma levels of the interleukin 6 (IL-6), 17a (IL-17a), and endothelin-1 (ET-1) along with oxygen saturation (SpO2) and Lake Louise scores (LLS).

RESULTS

ET-1 (5.7 ± 2.1 vs. 4.3 ± 1.9 pg/mL; p < 0.001), IL-6 (3.3 ± 3.3 vs. 2.4 ± 2.3 pg/mL; p = 0.007), and IL-17a (1.3 ± 3.0 vs. 0.46 ± 0.4 pg/mL; p < 0.001) were all overall significantly higher at HA versus SL. There was a paired increase in ET-1 and IL-6 with exercise versus rest at SL, 3833, 4450, and 5129 m (p < 0.05). There was a negative correlation between LLS and SpO2 (r = -0.32; 95% confidence interval [CI] -0.21 to -0.42; p < 0.001) and a positive correlation between LLS and IL-6 (r = 0.16; 0.0-0.27; p = 0.007) and ET-1 levels (r = 0.29; 0.18-0.39; p < 0.001. Altitude, ET-1, IL-6, and SpO2 were all univariate predictors of AMS. On multivariate analysis, ET-1 (p = 0.002) and reducing SpO2 (p = 0.02) remained as the only independent predictors (overall r(2) = 0.16; p < 0.001) of AMS. ET-1 (p = 03) and SpO2 were (p = 0.01) also independent predictors of severe AMS (overall r(2) = 0.19; p < 0.001).

CONCLUSIONS

HA leads to endothelial activation and an inflammatory response. The rise in ET-1 and IL-6 is heavily influenced by the degree of exercise and hypoxia. ET-1 is an independent predictor of both AMS and its severity.