Biomarker and transcriptomics profiles of serum selenium concentrations in patients with heart failure are associated with immunoregulatory processes.

BACKGROUND: Low selenium concentrations are associated with worse outcomes in heart failure (HF). However, the underlying pathophysiologic mechanisms remain incompletely understood. Therefore, we aimed to contrast serum selenium concentrations to blood biomarker and transcriptomic profiles in patients with HF. METHODS: Circulating biomarkers, whole blood transcriptomics and serum selenium measurements in a cohort of 2328 patients with HF were utilized. Penalized linear regression and gene expression analysis were used to assess biomarker and transcriptomics profiles, respectively. As a proof-of-principle, potential causal effects of selenium on excreted cytokines concentrations were investigated using human peripheral blood mononuclear cells (PBMCs). RESULTS: Mean selenium levels were 60.6 µg/L in Q1 and 122.0 µg/L in Q4. From 356 biomarkers and 20 clinical features, the penalized linear regression model yielded 44 variables with <5 % marginal false discovery rate as predictors of serum selenium. Biomarkers associated positively with selenium concentrations included: epidermal growth factor receptor (EGFR), IFN-gamma-R1, CD4, GDF15, and IL10. Biomarkers associated negatively with selenium concentrations included: PCSK9, TNFSF13, FGF21 and PAI. Additionally, 148 RNA transcripts were found differentially expressed between high and low selenium status (Padj.<0.05; log-fold-change<|0.25|). Enrichment analyses of the selected biomarkers and RNA transcripts identified similar enriched processes, including regulation processes of leukocyte differentiation and activation, as well as cytokines production. The mRNA expression of two selenoproteins (MSRB1 and GPX4) were strongly correlated with serum selenium, while GPX4, SELENOK, and SELENOS were associated with prognosis. In the in-vitro setting, PBMCs supplemented with selenium showed significantly lower abundance of several (pro-)inflammatory cytokines. CONCLUSION: These data suggest that immunoregulation is an important mechanism through which selenium might have beneficial roles in HF. The beneficial effects of higher serum selenium concentrations are likely because of global immunomodulatory effects on the abundance of cytokines. MSRB1 and GPX4 are potential modulators of and should be pursued in future research.

Sexual dimorphism in selenium deficiency is associated with metabolic syndrome and prevalence of heart disease.

BACKGROUND: Serum selenium levels have been associated with the incidence of heart failure (HF) and signs of the metabolic syndrome. In addition, notable differences have been reported between males and females in food intake and micronutrient metabolism, possibly explaining different health outcomes. OBJECTIVE: Our objective was to elucidate sex-specific, cross-sectional phenotypic differences in the association of serum selenium concentrations with parameters of metabolic syndrome and HF. METHODS: We investigated data from individuals from a community-based cohort (PREVEND; N = 4288) and heart failure cohort (BIOSTAT-CHF; N = 1994). In both populations, cross-sectional analyses were performed for potential interaction (p < 0.1) between sex and serum selenium with overlapping signs and clinical parameters of the metabolic syndrome and HF. RESULTS: Baseline selenium levels of the total cohort were similar between PREVEND (85.7 µg/L) and BIOSTAT-CHF (89.1 µg/L). Females with lower selenium levels had a higher BMI and increased prevalence of diabetes than females with higher selenium, in both PREVEND (pinteraction < 0.001; pinteraction = 0.040, resp.) and BIOSTAT-CHF (pinteraction = 0.021; pinteraction = 0.024, resp.), while opposite associations were observed for males. Additionally, in females, but not in males, lower selenium was associated with a higher prevalence of myocardial infarction (MI) in PREVEND (pinteraction = 0.021) and BIOSTAT-CHF (pinteraction = 0.084). CONCLUSION: Lower selenium was associated with a higher BMI and increased prevalence of diabetes in females, opposite to males, and was also associated with more MI in females. Interventional studies are needed to validate this observation.

Patiromer for the management of hyperkalemia in heart failure with reduced ejection fraction: the DIAMOND trial.

AIMS: To investigate the impact of patiromer on the serum potassium level and its ability to enable specified target doses of renin-angiotensin-aldosterone system inhibitor (RAASi) use in patients with heart failure and reduced ejection fraction (HFrEF). METHODS AND RESULTS: A total of 1642 patients with HFrEF and current or a history of RAASi-related hyperkalemia were screened and 1195 were enrolled in the run-in phase with patiromer and optimization of the RAASi therapy [≥50% recommended dose of angiotensin-converting enzyme inhibitor/angiotensin receptor blocker/angiotensin receptor-neprilysin inhibitor, and 50 mg of mineralocorticoid receptor antagonist (MRA) spironolactone or eplerenone]. Specified target doses of the RAASi therapy were achieved in 878 (84.6%) patients; 439 were randomized to patiromer and 439 to placebo. All patients, physicians, and outcome assessors were blinded to treatment assignment. The primary endpoint was between-group difference in the adjusted mean change in serum potassium. Five hierarchical secondary endpoints were assessed. At the end of treatment, the median (interquartile range) duration of follow-up was 27 (13-43) weeks, the adjusted mean change in potassium was +0.03 mmol/l in the patiromer group and +0.13 mmol/l in the placebo group [difference in the adjusted mean change between patiromer and placebo: -0.10 mmol/l (95% confidence interval, CI -0.13, 0.07); P < 0.001]. Risk of hyperkalemia >5.5 mmol/l [hazard ratio (HR) 0.63; 95% CI 0.45, 0.87; P = 0.006), reduction of MRA dose (HR 0.62; 95% CI 0.45, 0.87; P = 0.006), and total adjusted hyperkalemia events/100 person-years (77.7 vs. 118.2; HR 0.66; 95% CI 0.53, 0.81; P < 0.001) were lower with patiromer. Hyperkalemia-related morbidity-adjusted events (win ratio 1.53, P < 0.001) and total RAASi use score (win ratio 1.25, P = 0.048) favored the patiromer arm. Adverse events were similar between groups. CONCLUSION: Concurrent use of patiromer and high-dose MRAs reduces the risk of recurrent hyperkalemia (ClinicalTrials.gov: NCT03888066).

Micronutrient deficiencies in heart failure: Mitochondrial dysfunction as a common pathophysiological mechanism?

Heart failure is a devastating clinical syndrome, but current therapies are unable to abolish the disease burden. New strategies to treat or prevent heart failure are urgently needed. Over the past decades, a clear relationship has been established between poor cardiac performance and metabolic perturbations, including deficits in substrate uptake and utilization, reduction in mitochondrial oxidative phosphorylation and excessive reactive oxygen species production. Together, these perturbations result in progressive depletion of cardiac adenosine triphosphate (ATP) and cardiac energy deprivation. Increasing the delivery of energy substrates (e.g., fatty acids, glucose, ketones) to the mitochondria will be worthless if the mitochondria are unable to turn these energy substrates into fuel. Micronutrients (including coenzyme Q10, zinc, copper, selenium and iron) are required to efficiently convert macronutrients to ATP. However, up to 50% of patients with heart failure are deficient in one or more micronutrients in cross-sectional studies. Micronutrient deficiency has a high impact on mitochondrial energy production and should be considered an additional factor in the heart failure equation, moving our view of the failing myocardium away from an "an engine out of fuel" to "a defective engine on a path to self-destruction." This summary of evidence suggests that supplementation with micronutrients-preferably as a package rather than singly-might be a potential therapeutic strategy in the treatment of heart failure patients.

High selenium levels associate with reduced risk of mortality and new-onset heart failure: data from PREVEND.

AIM: To elucidate the relationship between serum selenium levels and the risk of mortality and new-onset heart failure (HF) in the general adult population. METHODS AND RESULTS: Selenium was measured in a Dutch cohort and a retrospective analysis of prospectively assessed data was performed. Main outcome measures were all-cause mortality and incidence of new-onset HF separately, and combined as a composite endpoint. Serum selenium was measured in 5973 subjects and mean selenium concentration was 84.6 (±19.5) µg/L. Mean age was 53.6 (±12.1) years and 3103 subjects (52%) were female. Median follow-up was 8.4 years. Selenium levels associated positively with female sex, higher total cholesterol and glucose concentrations, and associated negatively with incidence of anaemia, iron deficiency, current smoking, increased C-reactive protein levels, and higher body mass index. Univariate analysis on all subjects showed no association of continuous selenium concentrations, per 10 µg/L increase, with the composite endpoint (hazard ratio [HR] 0.96, 95% confidence interval [CI] 0.87-1.06, p = 0.407). However, significant interaction with smoking status was observed. In non-smoking subjects (n = 4288), continuous selenium concentrations were independently associated with reduced mortality risk (HR 0.87, 95% CI 0.79-0.96, p = 0.005), lower risk of new-onset HF (HR 0.82, 95% CI 0.69-0.96, p = 0.017), as well as reduced risk of the composite endpoint (HR 0.86, 95% CI 0.79-0.94, p = 0.001). In smoking subjects, no associations were found. CONCLUSION: Serum selenium was independently associated with multiple indicators of the metabolic syndrome. In addition, high selenium levels were independently associated with reduced mortality and new-onset HF in non-smokers. Well-powered interventional studies are necessary to evaluate the potential benefit of repleting selenium, especially in non-smoking subjects.

Selenium, Selenoproteins, and Heart Failure: Current Knowledge and Future Perspective.

PURPOSE OF REVIEW: (Mal-)nutrition of micronutrients, like selenium, has great impact on the human heart and improper micronutrient intake was observed in 30-50% of patients with heart failure. Low selenium levels have been reported in Europe and Asia and thought to be causal for Keshan disease. Selenium is an essential micronutrient that is needed for enzymatic activity of the 25 so-called selenoproteins, which have a broad range of activities. In this review, we aim to summarize the current evidence about selenium in heart failure and to provide insights about the potential mechanisms that can be modulated by selenoproteins. RECENT FINDINGS: Suboptimal selenium levels (<100 µg/L) are prevalent in more than 70% of patients with heart failure and were associated with lower exercise capacity, lower quality of life, and worse prognosis. Small clinical trials assessing selenium supplementation in patients with HF showed improvement of clinical symptoms (NYHA class), left ventricular ejection fraction, and lipid profile, while governmental interventional programs in endemic areas have significantly decreased the incidence of Keshan disease. In addition, several selenoproteins are found impaired in suboptimal selenium conditions, potentially aggravating underlying mechanisms like oxidative stress, inflammation, and thyroid hormone insufficiency. While the current evidence is not sufficient to advocate selenium supplementation in patients with heart failure, there is a clear need for high level evidence to show whether treatment with selenium has a place in the contemporary treatment of patients with HF to improve meaningful clinical endpoints. Graphical summary summarizing the potential beneficial effects of the various selenoproteins, locally in cardiac tissues and systemically in the rest of the body. In short, several selenoproteins contribute in protecting the integrity of the mitochondria. By doing so, they contribute indirectly to reducing the oxidative stress as well as improving the functionality of immune cells, which are in particular vulnerable to oxidative stress. Several other selenoproteins are directly involved in antioxidative pathways, next to excreting anti-inflammatory effects. Similarly, some selenoproteins are located in the endoplasmic reticulum, playing roles in protein folding. With exception of the protection of the mitochondria and the reduction of oxidative stress, other effects are not yet investigated in cardiac tissues. The systemic effects of selenoproteins might not be limited to these mechanisms, but also may include modulation of endothelial function, protection skeletal muscles, in addition to thyroid metabolism. ABBREVIATIONS: DIO, iodothyronine deiodinase; GPx, glutathione peroxidase; MsrB2, methionine-R-sulfoxide reductase B2; SELENOK, selenoprotein K; SELENON, selenoprotein N; SELENOP, selenoprotein P; SELENOS, selenoprotein S; SELENOT, selenoprotein T; TXNRD, thioredoxin reductase.

A Clinical Tool to Predict Low Serum Selenium in Patients with Worsening Heart Failure.

Selenium is an essential micronutrient, and a low selenium concentration (<100 µg/L) is associated with a poorer quality of life and exercise capacity, and an impaired prognosis in patients with worsening heart failure. Measuring selenium concentrations routinely is laborious and costly, and although its clinical utility is yet to be proven, an easy implemented model to predict selenium status is desirable. A stepwise multivariable logistic regression analysis was performed using routinely measured clinical factors. Low selenium was independently predicted by: older age, lower serum albumin, higher N-terminal pro-B-type natriuretic peptide levels, worse kidney function, and the presence of orthopnea and iron deficiency. A 10-points risk-model was developed, and a score of ≥6 points identified >80% of patients with low selenium (sensitivity of 44%, specificity of 80%). Given that selenium and iron overlap in their physiological roles, we evaluated the shared determinants and prognostic associates. Both deficiencies shared similar clinical characteristics, including the model risk factors and, in addition, a low protein intake and high levels of C-reactive protein. Low selenium was associated with a similar or worse prognosis compared to iron deficiency. In conclusion, although it is difficult to exclude low selenium based on clinical characteristics alone, we provide a prediction tool which identifies heart failure patients at higher risk of having a low selenium status.

Red-light-sensitive BODIPY photoprotecting groups for amines and their biological application in controlling heart rhythm.

Control of biological function by the use of photoremovable protecting groups (PPGs) is a gateway towards many new medical developments. Herein, we report the synthesis and application of efficient and biocompatible BODIPY-based photoprotecting groups for amines, which are cleavable with red light in the phototherapeutic window region (λ > 650 nm). We use the most promising PPG for the protection of dopamine and apply it to control the beating frequency of human cardiomyocytes.

Selenium and outcome in heart failure.

AIMS: Severe deficiency of the essential trace element selenium can cause myocardial dysfunction although the mechanism at cellular level is uncertain. Whether, in clinical practice, moderate selenium deficiency is associated with worse symptoms and outcome in patients with heart failure is unknown. METHODS AND RESULTS: BIOSTAT-CHF is a multinational, prospective, observational cohort study that enrolled patients with worsening heart failure. Serum concentrations of selenium were measured by inductively coupled plasma mass spectrometry. Primary endpoint was a composite of all-cause mortality and hospitalization for heart failure; secondary endpoint was all-cause mortality. To investigate potential mechanisms by which selenium deficiency might affect prognosis, human cardiomyocytes were cultured in absence of selenium, and mitochondrial function and oxidative stress were assessed. Serum selenium concentration (deficiency) was <70 µg/L in 485 (20.4%) patients, who were older, more often women, had worse New York Heart Association class, more severe signs and symptoms of heart failure and poorer exercise capacity (6-min walking test) and quality of life (Kansas City Cardiomyopathy Questionnaire). Selenium deficiency was associated with higher rates of the primary endpoint [hazard ratio (HR) 1.23; 95% confidence interval (CI) 1.06-1.42] and all-cause mortality (HR 1.52; 95% CI 1.26-1.86). In cultured human cardiomyocytes, selenium deprivation impaired mitochondrial function and oxidative phosphorylation, and increased intracellular reactive oxygen species levels. CONCLUSIONS: Selenium deficiency in heart failure patients is independently associated with impaired exercise tolerance and a 50% higher mortality rate, and impaired mitochondrial function in vitro, in human cardiomyocytes. Clinical trials are needed to investigate the effect of selenium supplements in patients with heart failure, especially if they have low plasma concentrations of selenium.

Rationale and design of the AFFIRM-AHF trial: a randomised, double-blind, placebo-controlled trial comparing the effect of intravenous ferric carboxymaltose on hospitalisations and mortality in iron-deficient patients admitted for acute heart failure.

AIMS: Iron deficiency (ID) is a common co-morbidity in heart failure (HF), associated with impaired functional capacity, poor quality of life and increased morbidity and mortality. Treatment with intravenous (i.v.) ferric carboxymaltose (FCM) has shown improvements in functional capacity, symptoms and quality of life in stable HF patients with reduced ejection fraction. The effect of i.v. iron supplementation on morbidity and mortality in patients hospitalised for acute HF (AHF) and who have ID has yet to be established. The objective of the present article is to present the rationale and design of the AFFIRM-AHF trial (ClinicalTrials.gov NCT02937454) which will investigate the effect of i.v. FCM (vs. placebo) on recurrent HF hospitalisations and cardiovascular (CV) mortality in iron-deficient patients hospitalised for AHF. METHODS: AFFIRM-AHF is a multicentre, randomised (1:1), double-blind, placebo-controlled trial which recruited 1100 patients hospitalised for AHF and who had iron deficiency ID defined as serum ferritin <100 ng/mL or 100-299 ng/mL if transferrin saturation <20%. Eligible patients were randomised (1:1) to either i.v. FCM or placebo and received the first dose of study treatment just prior to discharge for the index hospitalisation. Patients will be followed for 52 weeks. The primary outcome is the composite of recurrent HF hospitalisations and CV mortality. The main secondary outcomes include the composite of recurrent CV hospitalisations and CV mortality, recurrent HF hospitalisations and safety-related outcomes. CONCLUSION: The AFFIRM-AHF trial will evaluate, compared to placebo, the effect of i.v. FCM on morbidity and mortality in iron-deficient patients hospitalised for AHF.

Metabolic Maturation of Human Pluripotent Stem Cell-Derived Cardiomyocytes by Inhibition of HIF1α and LDHA.

RATIONALE: Human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) are a readily available, robustly reproducible, and physiologically appropriate human cell source for cardiac disease modeling, drug discovery, and toxicity screenings in vitro. However, unlike adult myocardial cells in vivo, hPSC-CMs cultured in vitro maintain an immature metabolic phenotype, where majority of ATP is produced through aerobic glycolysis instead of oxidative phosphorylation in the mitochondria. Little is known about the underlying signaling pathways controlling hPSC-CMs' metabolic and functional maturation. OBJECTIVE: To define the molecular pathways controlling cardiomyocytes' metabolic pathway selections and improve cardiomyocyte metabolic and functional maturation. METHODS AND RESULTS: We cultured hPSC-CMs in different media compositions including glucose-containing media, glucose-containing media supplemented with fatty acids, and glucose-free media with fatty acids as the primary carbon source. We found that cardiomyocytes cultured in the presence of glucose used primarily aerobic glycolysis and aberrantly upregulated HIF1α (hypoxia-inducible factor 1α) and its downstream target lactate dehydrogenase A. Conversely, glucose deprivation promoted oxidative phosphorylation and repressed HIF1α. Small molecule inhibition of HIF1α or lactate dehydrogenase A resulted in a switch from aerobic glycolysis to oxidative phosphorylation. Likewise, siRNA inhibition of HIF1α stimulated oxidative phosphorylation while inhibiting aerobic glycolysis. This metabolic shift was accompanied by an increase in mitochondrial content and cellular ATP levels. Furthermore, functional gene expressions, sarcomere length, and contractility were improved by HIF1α/lactate dehydrogenase A inhibition. CONCLUSIONS: We show that under standard culture conditions, the HIF1α-lactate dehydrogenase A axis is aberrantly upregulated in hPSC-CMs, preventing their metabolic maturation. Chemical or siRNA inhibition of this pathway results in an appropriate metabolic shift from aerobic glycolysis to oxidative phosphorylation. This in turn improves metabolic and functional maturation of hPSC-CMs. These findings provide key insight into molecular control of hPSC-CMs' metabolism and may be used to generate more physiologically mature cardiomyocytes for drug screening, disease modeling, and therapeutic purposes.

Iron deficiency impairs contractility of human cardiomyocytes through decreased mitochondrial function.

AIMS: Iron deficiency is common in patients with heart failure and associated with a poor cardiac function and higher mortality. How iron deficiency impairs cardiac function on a cellular level in the human setting is unknown. This study aims to determine the direct effects of iron deficiency and iron repletion on human cardiomyocytes. METHODS AND RESULTS: Human embryonic stem cell-derived cardiomyocytes were depleted of iron by incubation with the iron chelator deferoxamine (DFO). Mitochondrial respiration was determined by Seahorse Mito Stress test, and contractility was directly quantified using video analyses according to the BASiC method. The activity of the mitochondrial respiratory chain complexes was examined using spectrophotometric enzyme assays. Four days of iron depletion resulted in an 84% decrease in ferritin (P < 0.0001) and significantly increased gene expression of transferrin receptor 1 and divalent metal transporter 1 (both P < 0.001). Mitochondrial function was reduced in iron-deficient cardiomyocytes, in particular ATP-linked respiration and respiratory reserve were impaired (both P < 0.0001). Iron depletion affected mitochondrial function through reduced activity of the iron-sulfur cluster containing complexes I, II and III, but not complexes IV and V. Iron deficiency reduced cellular ATP levels by 74% (P < 0.0001) and reduced contractile force by 43% (P < 0.05). The maximum velocities during both systole and diastole were reduced by 64% and 85%, respectively (both P < 0.001). Supplementation of transferrin-bound iron recovered functional and morphological abnormalities within 3 days. CONCLUSION: Iron deficiency directly affects human cardiomyocyte function, impairing mitochondrial respiration, and reducing contractility and relaxation. Restoration of intracellular iron levels can reverse these effects.

Finerenone : third-generation mineralocorticoid receptor antagonist for the treatment of heart failure and diabetic kidney disease.

INTRODUCTION: The mineralocorticoid receptor antagonists (MRAs) spironolactone and eplerenone reduce the risk of hospitalizations and mortality in patients with heart failure (HF) with reduced ejection fraction (HFrEF), and attenuate progression of diabetic kidney disease. However, their use is limited by the fear of inducing hyperkalemia, especially in patients with renal dysfunction. Finerenone is a novel nonsteroidal MRA, with higher selectivity toward the mineralocorticoid receptor (MR) compared to spironolactone and stronger MR-binding affinity than eplerenone. AREAS COVERED: This paper discusses the chemistry, pharmacokinetics, clinical efficacy and safety of finerenone. EXPERT OPINION: The selectivity and greater binding affinity of finerenone to the MR may reduce the risk of hyperkalemia and renal dysfunction and thereby overcome the reluctance to start and uptitrate MRAs in patients with HF and diabetic kidney disease. Studies conducted in patients with HFrEF and moderate chronic kidney disease and diabetic kidney disease, showed promising results. Phase III trials will have to show whether finerenone might become the third-generation MRA for the treatment of HF and diabetic kidney disease.