Insulin Signaling and Heart Failure

The role of epicardial adipose tissue remodelling in heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) is a growing global health problem characterized by high morbidity and mortality, with limited effective therapies available. Obesity significantly influences haemodynamic and structural changes in the myocardium and vasculature, primarily through the accumulation and action of visceral adipose tissue. Particularly, epicardial adipose tissue (EAT) contributes to HFpEF through inflammation and lipotoxic infiltration of the myocardium. However, the precise signalling pathways leading to diastolic stiffness in HFpEF require further elucidation. This review explores the dynamic role of EAT in health and disease. Drawing upon insights from studies in other conditions, we discuss potential EAT-mediated inflammatory pathways in HFpEF and how they may contribute to functional and structural myocardial and endothelial derangements, including intramyocardial lipid infiltration, fibrosis, endothelial dysfunction, cardiomyocyte stiffening, and left ventricular hypertrophy. Lastly, we propose potential targets for novel therapeutic avenues.

Associations between the triglyceride-glucose index and the risk of heart failure in patients undergoing maintenance hemodialysis: a retrospective cohort study

Background

Although the triglyceride-glucose (TyG) index levels have been shown to be a reliable predictor of major adverse cardiovascular events (MACE), few studies have investigated their association with heart failure (HF), especially in patients on dialysis. We therefore aimed to investigate the relationship between the TyG index and the incidence of HF in patients undergoing maintenance hemodialysis (MHD).

Methods

A total of 183 participants who underwent MHD in the Blood Purification Center of the Affiliated Hospital of Xuzhou Medical University from September 2008 to October 2023 were included and followed up until March 2024. The TyG index was calculated as ln [fasting triglycerides (mg/dL) × fasting blood glucose (mg/dL)/2]. Participants were divided into two different groups according to the TyG index. The primary endpoint of this study was newly diagnosed HF events during the follow-up period. Cox proportional hazard models were used to examine the association between the TyG index and the risk of incident HF. To assess the dose-response relationship between TyG index and risk of HF, restricted cubic spline analysis was used.

Results

Among the 183 participants, there were 61 incident cases of HF during a median follow-up period of 57 months. In comparison to the group with a lower TyG index, participants with a higher TyG index had a higher risk of HF (HR=2.590, 95%CI=1.490-4.500), regardless of whether a variety of potential confounders were adjusted. The association between TyG index and HF (P for non-linearity > 0.05) was confirmed by restricted cubic spline analysis.

Conclusion

The TyG index was positively associated with the risk of incident HF in patients undergoing MHD, which indicates that the TyG index might be useful to identify people at high-risk for developing HF.

Association between Triglyceride-Glucose indices and ischemic stroke risk across different glucose metabolism statuses

BACKGROUND

Triglyceride-glucose (TyG) related indices, including TyG, TyG-body mass index (TyG-BMI), and TyG-waist circumference (TyG-WC), have been identified as promising biomarkers for assessing insulin resistance (IR), a known risk factor for ischemic stroke. While previous research has highlighted the relevance of these indices in various metabolic disorders, their predictive utility for ischemic stroke across different glucose metabolic statuses has not been extensively explored.

METHOD

This study utilized data from the UK Biobank, analyzing 392,733 participants free from ischemic stroke at baseline, categorized into normal glucose, prediabetes, and diabetes groups based on American Diabetes Association criteria. TyG-related indices were computed using baseline measures of fasting blood glucose and triglycerides. Participants were followed for a median of 14.68 years to assess the incidence of ischemic stroke. Cox proportional hazards models adjusted for demographic and clinical covariates were used to explore the associations between TyG indices and stroke risk.

RESULTS

Over the follow-up period, 8033 participants experienced an ischemic stroke. Higher TyG-related indices were associated with an increased stroke risk in all glucose metabolism groups, with the strongest associations observed in the prediabetes and normal glucose groups. The risk of stroke increased progressively across quartiles of TyG, TyG-BMI, and TyG-WC indices. The analysis revealed that each unit increase in the TyG index significantly elevated stroke risk in diabetic individuals, while TyG-BMI and TyG-WC indices showed significant predictive power in the prediabetes and normal glucose groups.

CONCLUSION

TyG-related indices, particularly TyG-BMI and TyG-WC, are effective in predicting the risk of ischemic stroke, especially among individuals with prediabetes and normal glucose levels. These findings underscore the utility of TyG indices as tools for early detection and preventive strategies in stroke risk management across various states of glucose metabolism.

Metabolic and Mitochondrial Dysregulations in Diabetic Cardiac Complications

The growing prevalence of diabetes highlights the urgent need to study diabetic cardiovascular complications, specifically diabetic cardiomyopathy, which is a diabetes-induced myocardial dysfunction independent of hypertension or coronary artery disease. This review examines the role of mitochondrial dysfunction in promoting diabetic cardiac dysfunction and highlights metabolic mechanisms such as hyperglycaemia-induced oxidative stress. Chronic hyperglycaemia and insulin resistance can activate harmful pathways, including advanced glycation end-products (AGEs), protein kinase C (PKC) and hexosamine signalling, uncontrolled reactive oxygen species (ROS) production and mishandling of Ca2+ transient. These processes lead to cardiomyocyte apoptosis, fibrosis and contractile dysfunction. Moreover, endoplasmic reticulum (ER) stress and dysregulated RNA-binding proteins (RBPs) and extracellular vesicles (EVs) contribute to tissue damage, which drives cardiac function towards heart failure (HF). Advanced patient-derived induced pluripotent stem cell (iPSC) cardiac organoids (iPS-COs) are transformative tools for modelling diabetic cardiomyopathy and capturing human disease's genetic, epigenetic and metabolic hallmarks. iPS-COs may facilitate the precise examination of molecular pathways and therapeutic interventions. Future research directions encourage the integration of advanced models with mechanistic techniques to promote novel therapeutic strategies.

The predictive value of estimated glucose disposal rate and its association with myocardial infarction, heart failure, atrial fibrillation and ischemic stroke

AIMS

The relationship between the incidence of major cardiovascular diseases (CVDs) and estimated glucose disposal rate (eGDR), a proxy measurement for insulin resistance (IR), is not well understood in the general population. The predictive value of eGDR and other proxies of IR for CVD incidents have not been examined in previous studies. This study aimed to investigate the association between eGDR and various CVD events, including myocardial infarction (MI), heart failure (HF), atrial fibrillation (AF) and ischemic stroke. Additionally, the predictive values of eGDR, triglyceride-glucose (TyG) index, TyG-waist circumference (WC), TyG-body mass index (BMI), TyG-waist-to-height ratio (WHtR), triglyceride (TG)-to-high density lipoprotein cholesterol (HDL-C) ratio (TG/HDL-C) and the metabolic score for insulin resistance (METS-IR) for CVD events were compared.

METHODS

The study population was extracted from the UK Biobank, and the CVD events were documented by linking to hospital records. Cox proportional hazards model and the restricted cubic spline model were used to assess the association between eGDR and the risk of CVDs with adjustment for potential confounders. The receiver operating characteristic (ROC) curve and the area under the curve (AUC) were used to compare the predictive values of eGDR, TyG, TyG-WC, TyG-BMI, TyG-WHtR, TG/HDL-C and METS-IR.

RESULTS

A total of 360 953 participants were included in this study. During a median follow-up of 13.8 years, 12 698 MI, 10 360 HF, 23 638 AF and 6512 ischemic stroke events were documented. Compared with participants in the lowest quartile category of eGDR, those in the highest quartile category had the adjusted hazard ratio (HR) and 95% confidence interval (CI) of 0.59 (0.51-0.67) for MI, 0.66 (0.56-0.76) for HF, 0.88 (0.80-0.98) for AF and 0.73 (0.61-0.89) for ischemic stroke. eGDR outperformed TyG, TyG-WC, TyG-BMI, TyG-WHtR, TG/HDL-C and METS-IR in terms of predicting MI (AUC: 0.661), HF (AUC: 0.690), AF (AUC: 0.653) and ischemic stroke (AUC: 0.646).

CONCLUSIONS

eGDR was inversely associated with the incidence of MI, HF, AF and ischemic stroke in the general population. eGDR could serve as a more valuable predictive indicator than TyG, TyG-WC, TyG-BMI, TyG-WHtR, TG/HDL-C and METS-IR for CVD events in clinical practice.

Finerenone and new-onset diabetes in heart failure: a prespecified analysis of the FINEARTS-HF trial

BACKGROUND

Data on the effect of mineralocorticoid receptor antagonist therapy on HbA1c levels and new-onset diabetes are conflicting. We aimed to examine the effect of oral finerenone, compared with placebo, on incident diabetes in the Finerenone Trial to Investigate Efficacy and Safety Superior to Placebo in Patients with Heart Failure (FINEARTS-HF) trial.

METHODS

In this randomised, double-blind, placebo-controlled trial, 6001 participants with heart failure with New York Heart Association functional class II-IV, left ventricular ejection fraction 40% or higher, evidence of structural heart disease, and elevated N-terminal pro-B-type natriuretic peptide levels were randomly assigned to finerenone or placebo, administered orally. Randomisation was performed with concealed allocation. The primary outcome of the trial was the composite of cardiovascular death and total (first and recurrent) heart failure events (ie, heart failure hospitalisation or urgent heart failure visit). In the present analysis, participants with diabetes at baseline (investigator-reported history of diabetes or baseline HbA1c ≥6·5%) were excluded. New-onset diabetes was defined as a HbA1c measurement of 6·5% or higher on two consecutive follow-up visits or new initiation of glucose-lowering therapy. The full-analysis set comprised all participants randomly assigned to study treatment, analysed according to their treatment assignment irrespective of the treatment received (ie, intention to treat). The safety analysis set comprised participants randomly assigned to study treatment who took at least one dose of the investigational product, analysed according to the treatment actually received. This trial is registered with ClinicalTrials.gov, NCT04435626, and is closed to new participants.

FINDINGS

Between Sept 14, 2020, and Jan 10, 2023, 6001 participants were recruited and randomly assigned to finerenone or placebo. 3222 (53·7%) participants did not have diabetes at baseline and comprised the study population. During a median duration of follow-up of 31·3 months (IQR 21·5-36·3), 115 (7·2%) participants in the finerenone group and 147 (9·1%) in the placebo group developed new-onset diabetes, corresponding to a rate of 3·0 events per 100 person-years (95% CI 2·5-3·6) in the finerenone group and 3·9 events per 100 person-years (3·3-4·6) in the placebo group. Compared with placebo, finerenone significantly reduced the hazard of new-onset diabetes by 24% (hazard ratio [HR] 0·76 [95% CI 0·59-0·97], p=0·026). Fine-Gray competing risk analysis, accounting for the competing risk of death, yielded a similar finding (subdistribution HR 0·75 [0·59-0·96], p=0·024). Results were similar in sensitivity analyses, in which the definition of new-onset diabetes was expanded to include initiation of SGLT2 inhibitor treatment with diabetes as indication, restricted to HbA1c measurements only, and restricted to new initiation of glucose-lowering drugs only (excluding SGLT2 inhibitor treatment). Findings were similar when participants treated with glucose-lowering drugs at baseline were excluded (n=15). The effect of finerenone, compared with placebo, on new-onset diabetes was consistent across key participant subgroups. Seven participants had an adverse event of new diabetes not captured by any of the definitions above.

INTERPRETATION

In participants with heart failure with mildly reduced or preserved ejection fraction without diabetes, oral finerenone reduced the hazard of new-onset diabetes, representing a meaningful additional clinical benefit of this treatment in these individuals.

FUNDING

Bayer.

Association Between Triglyceride/High-Density Lipoprotein Ratio and Incidence Risk of Heart Failure: A Population-Based Cohort Study

Background/Objectives: The triglyceride/high-density lipoprotein (TG/HDL) ratio serves as a simple marker for insulin resistance. We investigated whether the TG/HDL ratio would be associated with the incidence risk of heart failure (HF). Methods: The study utilized data from the National Health Insurance Service-Health Screening Cohort database of South Korea from 2002 to 2019. The TG/HDL ratio was utilized as a time-dependent covariate or average value of at least three times throughout the follow-up period. The outcome of interest was incident heart failure (HF) corresponding with the International Classification of Disease, Tenth Revision code of I50. Results: A total of 293,968 individuals were included in this study. During the median 9.6 years (interquartile range 9.2-10.13), 27,852 individuals (9.47%) had a cumulative incidence of HF. Considering the multivariable time-dependent Cox proportional hazard model with the repeated measures of the TG/HDL ratio, per unit increase in the TG/HDL ratio significantly increased the risk of HF in the entire cohort (hazard ratio (HR): 1.007, 95% confidence interval (CI): 1.002-1.011), diabetes mellitus (DM) cohort (HR: 1.006. 95% CI: 1.002-1.010), and non-DM cohort (HR: 1.008, 95% CI: 1.003-1.013). Regarding average TG/HDL ratio quartiles, compared to the lowest quartiles (Q1), the highest quartiles (Q4) were positively associated with the incidence risk of HF accompanied by a significant p for trend (HR: 1.114, 95% CI: 1.075-1.155) in fully adjusted multivariable analysis. Conclusions: Our study demonstrated that the repeatedly measured TG/HDL ratio was associated with the incidence risk of HF regardless of the presence of DM history in the general population.

The Impact of Obesity on Cardiac Energy Metabolism and Efficiency in Heart Failure With Preserved Ejection Fraction

The incidence and prevalence of heart failure with preserved ejection fraction (HFpEF) continues to rise, and now comprises more than half of all heart failure cases. There are many risk factors for HFpEF, including older age, hypertension, diabetes, dyslipidemia, sedentary behaviour, and obesity. The rising prevalence of obesity in society is a particularly important contributor to HFpEF development and severity. Obesity can adversely affect the heart, including inducing marked alterations in cardiac energy metabolism. This includes obesity-induced impairments in mitochondrial function, and an increase in fatty acid uptake and mitochondrial fatty acid β-oxidation. This increase in myocardial fatty acid metabolism is accompanied by an impaired myocardial insulin signaling and a marked decrease in glucose oxidation. This switch from glucose to fatty acid metabolism decreases cardiac efficiency and can contribute to severity of HFpEF. Increased myocardial fatty acid uptake in obesity is also associated with the accumulation of fatty acids, resulting in cardiac lipotoxicity. Obesity also results in dramatic changes in the release of adipokines, which can negatively impact cardiac function and energy metabolism. Obesity-induced increases in epicardial fat can also increase cardiac insulin resistance and negatively affect cardiac energy metabolism and HFpEF. However, optimizing cardiac energy metabolism in obese subjects may be one approach to preventing and treating HFpEF. This review discusses what is presently known about the effects of obesity on cardiac energy metabolism and insulin signaling in HFpEF. The clinical implications of obesity and energy metabolism on HFpEF are also discussed.

Association between glyphosate exposure and cardiovascular health using "Life's Essential 8" metrics in US adults

BACKGROUND

Glyphosate, as one of the most widely used herbicides worldwide, has been reclassified as a potential carcinogen and linked to multiple health problems. Recent data from animal experiments have proved its potential cardiovascular toxicity. However, whether glyphosate exposure influences human cardiovascular health at the population levels remains unknown. This study aims to elucidate the correlation between glyphosate exposure and Cardiovascular Health (CVH) by utilizing comprehensive Life's Essential 8 (LE8) metrics.

METHODS

Data from 2842 participants, approximating 155.24 million U.S. adults, from 2013 to 2018 in National Health and Nutrition Examination Survey were analyzed. The association between natural logarithm (ln)-transformed glyphosate exposure in urine and CVH was examined using weighted linear regression and restricted cubic spline (RCS) models. Mediation analysis was used to determine potential mediators correlated with glyphosate and CVH. Further subgroup analysis and sensitive analysis were conducted to confirm the results.

RESULTS

In fully adjusted models, the total CVH score decreased by 1.33 points for every unit increase in continuous ln-transformed glyphosate [β = -1.33, 95 % confidence interval (CI) (-2.25, -0.41)]. There was a negative correlation between the total CVH score and the lowest quantiles of ln-transformed glyphosate (Q1), Q2, Q3, and Q4 with p for trend < 0.05. A non-linear relationship between glyphosate and total CVH emerged (p for non-linear<0.001, p for overall = 0.003), and no safe threshold of glyphosate was observed. Serum insulin was an important mediator in the adverse effects of glyphosate on CVH with an 18.73 % mediation proportion. Moreover, higher serum insulin levels and higher homeostasis model assessment of insulin resistance were associated with higher glyphosate exposure but negatively correlated with total CVH score.

CONCLUSIONS

Glyphosate exposure may pose a risk to cardiovascular health at the population levels, with elevated serum insulin levels acting as a crucial mediating element. Further studies are required to investigate the safe threshold and underlying mechanism of glyphosate impairment.

The role of the triglyceride-glucose index as a biomarker of cardio-metabolic syndromes

BACKGROUND

The Triglyceride-glucose (TyG) index represents a simple, cost-effective, and valid proxy for insulin resistance. This surrogate marker has also been proposed as a predictor of metabolic and cardiovascular disease (CVD). In this descriptive review, we aimed to assess the utility of the TyG index as a predictive biomarker of cardiometabolic diseases.

METHODS

A search was conducted in PubMed, and Web of Science to identify cross-sectional and more importantly prospective studies examining the use of the TyG index as a predictive biomarker. The following terms were utilized in addition to the TyG index: "insulin resistance", "metabolic syndrome", "diabetes"; "cardiovascular diseases".

RESULTS

This descriptive review included thirty prospective studies in addition to cross-sectional studies. Following adjustment for confounding variables, an elevated TyG index was associated with a significantly increased risk for the development of Metabolic Syndrome (MetS), Type 2 Diabetes, hypertension, and CVD. Also in limited studies, the TyG index was associated with endothelial dysfunction, increased oxidative stress and a pro-inflammatory phenotype.

CONCLUSION

Overall, our findings support the use of the TyG index as a valid biomarker to assess the risk of developing MetS, T2DM, as well as atherosclerotic cardiovascular disease.

IRS2 Signaling Protects Against Stress-Induced Arrhythmia by Maintaining Ca2+ Homeostasis

BACKGROUND

The docking protein IRS2 (insulin receptor substrate protein-2) is an important mediator of insulin signaling and may also regulate other signaling pathways. Murine hearts with cardiomyocyte-restricted deletion of Irs2 (cIRS2-KO) are more susceptible to pressure overload-induced cardiac dysfunction, implying a critical protective role of IRS2 in cardiac adaptation to stress through mechanisms that are not fully understood. There is limited evidence regarding the function of IRS2 beyond metabolic homeostasis regulation, particularly in the context of cardiac disease.

METHODS

A retrospective analysis of an electronic medical record database was conducted to identify patients with IRS2 variants and assess their risk of cardiac arrhythmias. Arrhythmia susceptibility was examined in cIRS2-KO mice. The underlying mechanisms were investigated using confocal calcium imaging of ex vivo whole hearts and isolated cardiomyocytes to assess calcium handling, Western blotting to analyze the involved signaling pathways, and pharmacological and genetic interventions to rescue arrhythmias in cIRS2-KO mice.

RESULTS

The retrospective analysis identified patients with IRS2 variants of uncertain significance with a potential association to an increased risk of cardiac arrhythmias compared with matched controls. cIRS2-KO hearts were found to be prone to catecholamine-sensitive ventricular tachycardia and reperfusion ventricular tachycardia. Confocal calcium imaging of ex vivo whole hearts and single isolated cardiomyocytes from cIRS2-KO hearts revealed decreased Ca²⁺ transient amplitudes, increased spontaneous Ca²⁺ sparks, and reduced sarcoplasmic reticulum Ca²⁺ content during sympathetic stress, indicating sarcoplasmic reticulum dysfunction. We identified that overactivation of the AKT1/NOS3 (nitric oxide synthase 3)/CaMKII (Ca²⁺/calmodulin-dependent protein kinase II)/RyR2 (type 2 ryanodine receptor) signaling pathway led to calcium mishandling and catecholamine-sensitive ventricular tachycardia in cIRS2-KO hearts. Pharmacological AKT inhibition or genetic stabilization of RyR2 rescued catecholamine-sensitive ventricular tachycardia in cIRS2-KO mice.

CONCLUSIONS

Cardiac IRS2 inhibits sympathetic stress-induced AKT/NOS3/CaMKII/RyR2 overactivation and calcium-dependent arrhythmogenesis. This novel IRS2 signaling axis, essential for maintaining cardiac calcium homeostasis under stress, presents a promising target for developing new antiarrhythmic therapies.

Triglyceride glucose index is a risk factor for heart failure: A prospective cohort study

AIMS

This study aimed to investigate the relationship between the triglyceride glucose (TyG) index and all-cause mortality in patients with heart failure (HF).

METHODS AND RESULTS

A total of 1274 patients with HF diagnosed at Hebei General Hospital were enrolled in this study. The patients were divided into four groups by quartiles based on the TyG index. The endpoint was all-cause mortality during the follow-up period. The median follow-up period was 1079 days, with a total of 543 (42.7%) patients experiencing all-cause mortality. The survival curves showed no significant difference in endpoint events among the four groups (log-rank P = 0.329). The adjusted survival curves revealed that after adjusting for the variables in Model 3, the group with a higher TyG index exhibited a higher risk of death (log-rank P < 0.001). The multivariate-adjusted Cox proportional hazard models revealed a positive correlation between the TyG index and all-cause mortality. After complete adjustment, patients with the highest TyG index exhibited a higher risk of all-cause mortality than those in the lowest quartile [hazard ratio (HR) = 1.6, 95% confidence interval (CI): 1.22-2.09; P = 0.001]. Restricted cubic spline analysis showed that the risk of all-cause mortality increased linearly with the TyG index (P for non-linear = 0.207). Exploratory subgroup analyses revealed that, as a continuous variable, the TyG index was significantly associated with all-cause mortality in female patients (HR = 1.31, 95% CI: 1.08-1.58, P = 0.029) and older patients (HR = 1.25, 95% CI: 1.1-1.43, P = 0.027).

CONCLUSIONS

The TyG index was positively associated with increased all-cause mortality in hospitalized patients with HF. Subgroup analyses indicated that the TyG index was strongly associated with all-cause mortality in older and female patients.

Recent advances associated with cardiometabolic remodeling in diabetes-induced heart failure

Diabetes mellitus (DM) is characterized by chronic hyperglycemia, and despite intensive glycemic control, the risk of heart failure in patients with diabetes remains high. Diabetes-induced heart failure (DHF) presents a unique metabolic challenge, driven by significant alterations in cardiac substrate metabolism, including increased reliance on fatty acid oxidation, reduced glucose utilization, and impaired mitochondrial function. These metabolic alterations lead to oxidative stress, lipotoxicity, and energy deficits, contributing to the progression of heart failure. Emerging research has identified novel mechanisms involved in the metabolic remodeling of diabetic hearts, such as autophagy dysregulation, epigenetic modifications, polyamine regulation, and branched-chain amino acid (BCAA) metabolism. These processes exacerbate mitochondrial dysfunction and metabolic inflexibility, further impairing cardiac function. Therapeutic interventions targeting these pathways-such as enhancing glucose oxidation, modulating fatty acid metabolism, and optimizing ketone body utilization-show promise in restoring metabolic homeostasis and improving cardiac outcomes. This review explores the key molecular mechanisms driving metabolic remodeling in diabetic hearts, highlights advanced methodologies, and presents the latest therapeutic strategies for mitigating the progression of DHF. Understanding these emerging pathways offers new opportunities to develop targeted therapies that address the root metabolic causes of heart failure in diabetes.

Obesity, Metabolic Syndrome, and Obesity Paradox in Heart Failure: A Critical Evaluation

PURPOSE OF REVIEW

Since the turn of the millennium, obesity has been on the rise worldwide, and particularly so throughout the United States. Even more concerning is the rate at which persons with severe obesity continue to trend upwards. Given the detrimental effects of obesity on cardiac structure and function, it is not surprising that obesity stands as one of the leading risk factors for developing heart failure (HF). This state-of-the-art article aims to review the updated literature on the obesity paradox to help further understand its relationship to body composition, weight loss, fitness, and exercise.

RECENT FINDINGS

An intriguing phenomenon appears to exist in which obesity is associated with a better prognosis in those with HF, compared to patients with lesser body mass. Recent studies suggest, however, that weight loss induced by pharmacologic strategies might be beneficial in patients with HF with preserved ejection fraction. Despite the presence of an obesity paradox, recent data suggest that obesity could be targeted in HF, however, long-term data are currently lacking. Consequently, definitive guidelines for managing obesity, and specifically the body composition of these patients, remain amiss.

Screening of key genes related to M6A methylation in patients with heart failure

OBJECTIVE

This study aims to identify m6A methylation-related and immune cell-related key genes with diagnostic potential for heart failure (HF) by leveraging various bioinformatics techniques.

METHODS

The GSE116250 and GSE141910 datasets were sourced from the Gene Expression Omnibus (GEO) database. Correlation analysis was conducted between differentially expressed genes (DEGs) in HF and control groups, alongside differential m6A regulatory factors, to identify m6A-related DEGs (m6A-DEGs). Subsequently, candidate genes were narrowed down by intersecting key module genes derived from weighted gene co-expression network analysis (WGCNA) with m6A-DEGs. Key genes were then identified through the Least Absolute Shrinkage and Selection Operator (LASSO) analysis. Correlation analyses between key genes and differentially expressed immune cells were performed, followed by the validation of key gene expression levels in public datasets. To ensure clinical applicability, five pairs of blood samples were collected for quantitative real-time fluorescence PCR (qRT-PCR) validation.

RESULTS

A total of 93 m6A-DEGs were identified (|COR| > 0.6, P < 0.05), and five key genes (LACTB2, NAMPT, SCAMP5, HBA1, and PRKAR2A) were selected for further analysis. Correlation analysis revealed that differential immune cells were negatively associated with the expression of LACTB2, NAMPT, and PRKAR2A (P < 0.05), while positively correlated with SCAMP5 and HBA1 (P < 0.05). Subsequent expression validation confirmed significant differences in key gene expression between the HF and control groups, with consistent expression trends observed across both training and validation sets. The expression trends of LACTB2, PRKAR2A, and HBA1 in blood samples from the qRT-PCR assay aligned with the results derived from public databases.

CONCLUSION

This study successfully identified five m6A methylation-related key genes with diagnostic significance, providing a theoretical foundation for further exploration of m6A methylation's molecular mechanisms in HF.

Association between single-point insulin sensitivity estimator and heart failure in older adults: A cross-sectional study

BACKGROUND

Heart failure (HF) is a condition caused by a malfunction of the heart's pumping function. The single-point insulin sensitivity estimator (SPISE) index is a novel indicator for assessing insulin resistance in humans. However, the connection between the SPISE index and the risk of HF in the elderly is unknown. Therefore, our study aims to evaluate the connection between the SPISE index and HF in older adults.

METHODS

The study was based on data collected from the 1999-2020 National Health and Nutrition Examination Survey database and included 6165 participants aged ≥60 years. The multivariable linear regression model and the smooth fitting curve model were applied to investigate the connection between the SPISE index and HF in the elderly. Furthermore, the subgroup analysis was performed to investigate the interactive factors.

RESULTS

In this study, the mean age of the population was 69.38 years. After adjusting for all covariates, we observed that the SPISE index was inversely related to the prevalence of HF (OR = 0.87, 95 % CI = 0.80-0.94, P < 0.001) in older adults. The interaction analysis showed that the association might be affected by diabetes mellitus and smoking status. Additionally, an inflection point between the SPISE index and HF was found among older women.

CONCLUSIONS

An inverse correlation was detected between the SPISE index and HF in the elderly. This could provide new insight into the prevention and management of HF in the elderly population.

Differential expression of cardiometabolic and inflammation markers and signaling pathways between overweight/obese Qatari adults with high and low plasma salivary α-amylase activity

BACKGROUND

The relationship between salivary α-amylase activity (sAAa) and susceptibility to cardiovascular disorders lacks a definitive consensus in available studies. To fill this knowledge gap, the present study endeavors to investigate this association among overweight/obese otherwise healthy Qatari adults. The study specifically categorizes participants based on their sAAa into high and low subgroups, aiming to provide a more comprehensive understanding of the potential link between sAAa levels and cardiovascular and inflammation markers in this population.

METHODS

Plasma samples of 264 Qatari overweight/obese (Ow/Ob) participants were used to quantify the sAAa and to profile the proteins germane to cardiovascular, cardiometabolic, metabolism, and organ damage in low sAAa (LsAAa) and high sAAa (HsAAa) subjects using the Olink technology. Comprehensive statistical tools as well as chemometric and enrichments analyses were used to identify differentially expressed proteins (DEPs) and their associated signaling pathways and cellular functions.

RESULTS

A total of ten DEPs were detected, among them five were upregulated (QPCT, LCN2, PON2, DPP7, CRKL) while five were down regulated in the LsAAa subgroup compared to the HsAAa subgroup (ARG1, CTSH, SERPINB6, OSMR, ALDH3A). Functional enrichment analysis highlighted several relevant signaling pathways and cellular functions enriched in the DEPs, including myocardial dysfunction, disorder of blood pressure, myocardial infraction, apoptosis of cardiomyocytes, hypertension, chronic inflammatory disorder, immunes-mediated inflammatory disease, inflammatory response, activation of leukocytes and activation of phagocytes.

CONCLUSION

Our study unveils substantial alterations within numerous canonical pathways and cellular or molecular functions that bear relevance to cardiometabolic disorders among Ow/Ob Qatari adults exhibiting LsAAa and HsAAa in the plasma. A more comprehensive exploration of these proteins and their associated pathways and functions offers the prospect of elucidating the mechanistic underpinnings inherent in the documented relationship between sAAa and metabolic disorders.

Tissue-specific activation of insulin signaling as a potential target for obesity-related metabolic disorders

The incidence of obesity is rapidly increasing worldwide. Obesity-associated insulin resistance has long been established as a significant risk factor for obesity-related disorders such as type 2 diabetes and atherosclerosis. Insulin plays a key role in systemic glucose metabolism, with the liver, skeletal muscle, and adipose tissue as the major acting tissues. Insulin receptors and the downstream insulin signaling-related molecules are expressed in various tissues, including vascular endothelial cells, vascular smooth muscle cells, and monocytes/macrophages. In obesity, decreased insulin action is considered a driver for associated disorders. However, whether insulin action has a positive or negative effect on obesity-related disorders depends on the tissue in which it acts. While an enhancement of insulin signaling in the liver increases hepatic fat accumulation and exacerbates dyslipidemia, enhancement of insulin signaling in adipose tissue protects against obesity-related dysfunction of various organs by increasing the capacity for fat accumulation in the adipose tissue and inhibiting ectopic fat accumulation. Thus, this "healthy adipose tissue expansion" by enhancing insulin sensitivity in adipose tissue, but not in the liver, may be an effective therapeutic strategy for obesity-related disorders. To effectively address obesity-related metabolic disorders, the mechanisms of insulin resistance in various tissues of obese patients must be understood and drugs that enhance insulin action must be developed. In this article, we review the potential of interventions that enhance insulin signaling as a therapeutic strategy for obesity-related disorders, focusing on the molecular mechanisms of insulin action in each tissue.

Associations between metabolic overweight/obesity phenotypes and mortality risk among patients with chronic heart failure

Background

Metabolic disorders and overweight or obesity are highly prevalent and intricately linked in patients with chronic heart failure (CHF). However, it remains unclear whether there is an interactive effect between these conditions and the prognosis of heart failure, and whether such an interaction is influenced by stratification based on age and sex.

Methods

A total of 4,955 patients with CHF were enrolled in this study. Metabolic status was assessed according to the presence or absence of metabolic syndrome (MetS). BMI categories included normal weight and overweight or obesity (BMI < 24, ≥ 24 kg/m2). Patients were divided into four phenotypes according to their metabolic status and BMI: metabolically healthy with normal weight (MHNW), metabolically unhealthy with normal weight (MUNW), metabolically healthy with overweight or obesity (MHO), and metabolically unhealthy with overweight or obesity (MUO). The incidence of primary outcomes, including all-cause and cardiovascular (CV) death, was recorded.

Results

During a mean follow-up of 3.14 years, a total of 1,388 (28.0%) all-cause deaths and 815 (16.4%) CV deaths were documented. Compared to patients with the MHNW phenotype, those with the MUNW (adjusted hazard ratio [aHR], 1.66; 95% confidence interval [CI], 1.38-2.00) or MUO (aHR, 1.42 [95% CI, 1.24-1.63]) phenotypes had a greater risk of all-cause death, and those with the MHO phenotype (aHR, 0.61 [95% CI, 0.51-0.72]) had a lower risk of all-cause death. Moreover, the above phenomenon existed mainly among males and elderly females (aged ≥ 60 years). In nonelderly females (aged < 60 years), the detrimental effects of MetS were lower (aHR, 1.05 [95% CI, 0.63-1.75] among MUNW group and aHR, 0.52 [95% CI, 0.34-0.80] among MUO group), whereas the protective effects of having overweight or obesity persisted irrespective of metabolic status (aHR, 0.43 [95% CI, 0.26-0.69] among MHO group and aHR, 0.52 [95% CI, 0.34-0.80] among MUO group). Similar results were obtained in the Cox proportional risk analysis of the metabolic overweight/obesity phenotypes and CV death.

Conclusions

In male and elderly female patients with CHF, the detrimental effects of MetS outweighed the protective benefits of having overweight or obesity. Conversely, in nonelderly females, the protective effects of having overweight or obesity were significantly greater than the adverse impacts of MetS.

Metabolic score for insulin resistance as a predictor of mortality in heart failure with preserved ejection fraction: results from a multicenter cohort study

BACKGROUND

The metabolic score for insulin resistance (METS-IR) has been validated as a novel, simple, and reliable surrogate marker for insulin resistance; however, its utility for evaluating the prognosis of heart failure with preserved ejection fraction (HFpEF) remains to be elucidated. Therefore, we aimed to analyze the association between METS-IR and the long-term prognosis of HFpEF.

METHODS

We enrolled a total of 4,702 participants with HFpEF in this study. The participants were divided into three groups according to METS-IR tertiles: (Ln [2 × fasting plasma glucose + fasting triglycerides] × body mass index) / (Ln [high-density lipoprotein cholesterol]). The occurrence of primary endpoints, including all-cause mortality and cardiovascular (CV) death, was documented.

RESULTS

There were 3,248 participants with HFpEF (mean age, 65.7 ± 13.8 years; male, 59.0%) in total who were included in the final analysis. The incidence of primary outcomes from the lowest to the highest METS-IR tertiles were 46.92, 86.01, and 124.04 per 1000 person-years for all-cause death and 26.75, 49.01, and 64.62 per 1000 person-years for CV death. The multivariate Cox hazards regression analysis revealed hazard ratios for all-cause and CV deaths of 2.48 (95% CI 2.10-2.93; P < 0.001) and 2.29 (95% CI 1.83-2.87; P < 0.001) when the highest and lowest METS-IR tertiles were compared, respectively. In addition, the predictive efficacy of METS-IR remained significant across various comorbidity subgroups (all P < 0.05). Further, adding the METS-IR to the baseline risk model for all-cause death improved the C-statistic value (0.690 for the baseline model vs. 0.729 for the baseline model + METS-IR, P < 0.01), the integrated discrimination improvement value (0.061, P < 0.01), the net reclassification improvement value (0.491, P < 0.01), and the clinical net benefit.

CONCLUSIONS

An elevated METS-IR, which is associated with an increased mortality risk, is a potential valuable prognostic marker for individuals with HFpEF.

Exploring the impact of metabolites function on heart failure and coronary heart disease: insights from a Mendelian randomization (MR) study

BACKGROUND

Heart failure (HF) and coronary heart disease (CHD) are major causes of morbidity and mortality worldwide. While traditional risk factors such as hypertension, diabetes, and smoking have been extensively studied, the role of metabolite functions in the development of these cardiovascular conditions has been less explored. This study employed a Mendelian randomization (MR) approach to investigate the impact of metabolite functions on HF and CHD.

METHODS

To assess the causal impacts of specific metabolite risk factors on HF and CHD, this study utilized genetic variants associated with these factors as instrumental variables. Comprehensive genetic and phenotypic data from diverse cohorts, including genome-wide association studies (GWAS) and cardiovascular disease registries, were incorporated into the research.

RESULTS

Our results encompass 61 metabolic cell phenotypes, with ten providing strong evidence of the influence of metabolite functions on the occurrence of HF and CHD. We found that elevated levels of erucate (22:1n9), lower levels of α-tocopherol, an imbalanced citrulline-to-ornithine ratio, elevated γ-glutamyl glycine levels, and elevated 7-methylguanine levels independently increased the risk of these cardiovascular conditions. These findings were consistent across different populations and robust to sensitivity analyses.

CONCLUSION

This MR study provides valuable insights into the influence of metabolite functions on HF and CHD. However, further investigation is needed to fully understand the precise mechanisms by which these metabolite factors contribute to the onset of these conditions. Such research could pave the way for the development of targeted therapeutic strategies.

Relationship of the trajectory of the triglyceride-glucose index with heart failure: the Kailuan study

BACKGROUND

A high triglyceride-glucose index (TyG) is associated with a higher risk of incident heart failure. However, the effects of longitudinal patterns of TyG index on the risk of heart failure remain to be characterized. Therefore, in the present study, we aimed to characterize the relationship between the trajectory of TyG index and the risk of heart failure.

METHODS

We performed a prospective study of 56,149 participants in the Kailuan study who attended three consecutive surveys in 2006-2007, 2008-2009, and 2010-2011 and had no history of heart failure or cancer before the third wave survey (2010-2011). The TyG index was calculated as ln [fasting triglycerides (mg/dL) × fasting plasma glucose (mg/dL)/2], and we used latent mixture modeling to characterize the trajectory of the TyG index over the period 2006-2010. Additionally, Cox proportional risk models were used to calculate the hazard ratio (HR) and 95% confidence interval (CI) for incident heart failure for the various TyG index trajectory groups.

RESULTS

From 2006 to 2010, four different TyG trajectories were identified: low-stable (n = 13,554; range, 7.98-8.07), moderate low-stable (n = 29,435; range, 8.60-8.65), moderate high-stable (n = 11,262; range, 9.31-9.30), and elevated-stable (n = 1,898; range, 10.04-10.25). A total of 1,312 new heart failure events occurred during a median follow-up period of 10.04 years. After adjustment for potential confounders, the hazard ratios (HRs) and 95% confidence intervals (CIs) for incident heart failure for the elevated-stable, moderate high-stable, and moderate low-stable groups were 1.55 (1.15, 2.08), 1.32 (1.08, 1.60), and 1.17 (0.99, 1.37), respectively, compared to the low-stable group.

CONCLUSIONS

Higher TyG index trajectories were associated with a higher risk of heart failure. This suggests that monitoring TyG index trajectory may help identify individuals at high risk for heart failure and highlights the importance of early control of blood glucose and lipids for the prevention of heart failure.

Usefulness of estimated glucose disposal rate in detecting heart failure: results from national health and nutrition examination survey 1999-2018

BACKGROUND

Estimated glucose disposal rate (eGDR) is a novel, clinically available, and cost-effective surrogate of insulin resistance. The current study aimed to assess the association between eGDR and prevalent heart failure (HF), and further evaluate the value of eGDR in detecting prevalent HF in a general population.

METHODS

25,450 subjects from the National Health and Nutrition Examination Survey 1999-2018 were included. HF was recorded according to the subjects' reports. Logistic regression was employed to analyze the association between eGDR and HF, the results were summarized as Per standard deviation (SD) change. Then, subgroup analysis tested whether the main result from logistic regression was robust in several conventional subpopulations. Finally, receiver-operating characteristic curve (ROC) and reclassification analysis were utilized to evaluate the potential value of eGDR in improving the detection of prevalent HF.

RESULTS

The prevalence of reported HF was 2.96% (753 subjects). After adjusting demographic, laboratory, anthropometric, and medical history data, each SD increment of eGDR could result in a 43.3% (P < 0.001) risk reduction for prevalent HF. In the quartile analysis, the top quartile had a 31.1% (P < 0.001) risk of prevalent HF compared to the bottom quartile in the full model. Smooth curve fitting demonstrated that the association was linear in the whole range of eGDR (P for non-linearity = 0.313). Subgroup analysis revealed that the association was robust in age, sex, race, diabetes, and hypertension subgroups (All P for interaction > 0.05). Additionally, ROC analysis displayed a significant improvement in the detection of prevalent HF (0.869 vs. 0.873, P = 0.008); reclassification analysis also confirmed the improvement from eGDR (All P < 0.001).

CONCLUSION

Our study indicates that eGDR, a costless surrogate of insulin resistance, may have a linear and robust association with the prevalent HF. Furthermore, our findings implicate the potential value of eGDR in refining the detection of prevalent HF in the general population.

The treatment of chronic anemia in heart failure: a global approach

Chronic anemia is an independent risk factor for mortality in patients with heart failure (HF). Restoring physiological hemoglobin (Hb) levels is essential to increase oxygen transport capacity to tissues and improve cell metabolism as well as physical and cardiac performance. Nutritional deficits and iron deficiency are the major causes of chronic anemia, but other etiologies include chronic kidney disease, inflammatory processes, and unexplained anemia. Hormonal therapy, including erythropoietin (EPO) and anabolic treatment in chronic anemia HF patients, may contribute to improving Hb levels and clinical outcomes. Although preliminary studies showed a beneficial effect of EPO therapy on cardiac efficiency and in HF, more recent studies have not confirmed this positive impact of EPO, alluding to its side effect profile. Physical exercise significantly increases Hb levels and the response of anemia to treatment. In malnourished patients and chronic inflammatory processes, low levels of anabolic hormones, such as testosterone and insulin-like growth factor-1, contribute to the development of chronic anemia. This paper aims to review the effect of nutrition, EPO, anabolic hormones, standard HF treatments, and exercise as regulatory mechanisms of chronic anemia and their cardiovascular consequences in patients with HF.

Limiting extracellular matrix expansion in diet-induced obese mice reduces cardiac insulin resistance and prevents myocardial remodelling

OBJECTIVE

Obesity increases deposition of extracellular matrix (ECM) components of cardiac tissue. Since obesity aggregates with insulin resistance and heart disease, it is imperative to determine whether the increased ECM deposition contributes to this disease cluster. The hypotheses tested in this study were that in cardiac tissue of obese mice i) increased deposition of ECM components (collagens and hyaluronan) contributes to cardiac insulin resistance and that a reduction in these components improves cardiac insulin action and ii) reducing excess collagens and hyaluronan mitigates obesity-associated cardiac dysfunction.

METHODS

Genetic and pharmacological approaches that manipulated collagen and hyaluronan contents were employed in obese C57BL/6 mice fed a high fat (HF) diet. Cardiac insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp and cardiac function was measured by pressure-volume loop analysis in vivo.

RESULTS

We demonstrated a tight association between increased ECM deposition with cardiac insulin resistance. Increased collagen deposition by genetic deletion of matrix metalloproteinase 9 (MMP9) exacerbated cardiac insulin resistance and pirfenidone, a clinically available anti-fibrotic medication which inhibits collagen expression, improved cardiac insulin resistance in obese mice. Furthermore, decreased hyaluronan deposition by treatment with PEGylated human recombinant hyaluronidase PH20 (PEGPH20) improved cardiac insulin resistance in obese mice. These relationships corresponded to functional changes in the heart. Both PEGPH20 and pirfenidone treatment in obese mice ameliorated HF diet-induced abnormal myocardial remodelling.

CONCLUSION

Our results provide important new insights into the role of ECM deposition in the pathogenesis of cardiac insulin resistance and associated dysfunction in obesity of distinct mouse models. These findings support the novel therapeutic potential of targeting early cardiac ECM abnormalities in the prevention and treatment of obesity-related cardiovascular complications.

Insulin-Heart Axis: Bridging Physiology to Insulin Resistance

Insulin signaling is vital for regulating cellular metabolism, growth, and survival pathways, particularly in tissues such as adipose, skeletal muscle, liver, and brain. Its role in the heart, however, is less well-explored. The heart, requiring significant ATP to fuel its contractile machinery, relies on insulin signaling to manage myocardial substrate supply and directly affect cardiac muscle metabolism. This review investigates the insulin-heart axis, focusing on insulin's multifaceted influence on cardiac function, from metabolic regulation to the development of physiological cardiac hypertrophy. A central theme of this review is the pathophysiology of insulin resistance and its profound implications for cardiac health. We discuss the intricate molecular mechanisms by which insulin signaling modulates glucose and fatty acid metabolism in cardiomyocytes, emphasizing its pivotal role in maintaining cardiac energy homeostasis. Insulin resistance disrupts these processes, leading to significant cardiac metabolic disturbances, autonomic dysfunction, subcellular signaling abnormalities, and activation of the renin-angiotensin-aldosterone system. These factors collectively contribute to the progression of diabetic cardiomyopathy and other cardiovascular diseases. Insulin resistance is linked to hypertrophy, fibrosis, diastolic dysfunction, and systolic heart failure, exacerbating the risk of coronary artery disease and heart failure. Understanding the insulin-heart axis is crucial for developing therapeutic strategies to mitigate the cardiovascular complications associated with insulin resistance and diabetes.

In-depth phosphoproteomic profiling of the insulin signaling response in heart tissue and cardiomyocytes unveils canonical and specialized regulation

BACKGROUND

Insulin signaling regulates cardiac substrate utilization and is implicated in physiological adaptations of the heart. Alterations in the signaling response within the heart are believed to contribute to pathological conditions such as type-2 diabetes and heart failure. While extensively investigated in several metabolic organs using phosphoproteomic strategies, the signaling response elicited in cardiac tissue in general, and specifically in the specialized cardiomyocytes, has not yet been investigated to the same extent.

METHODS

Insulin or vehicle was administered to male C57BL6/JRj mice via intravenous injection into the vena cava. Ventricular tissue was extracted and subjected to quantitative phosphoproteomics analysis to evaluate the insulin signaling response. To delineate the cardiomyocyte-specific response and investigate the role of Tbc1d4 in insulin signal transduction, cardiomyocytes from the hearts of cardiac and skeletal muscle-specific Tbc1d4 knockout mice, as well as from wildtype littermates, were studied. The phosphoproteomic studies involved isobaric peptide labeling with Tandem Mass Tags (TMT), enrichment for phosphorylated peptides, fractionation via micro-flow reversed-phase liquid chromatography, and high-resolution mass spectrometry measurements.

RESULTS

We quantified 10,399 phosphorylated peptides from ventricular tissue and 12,739 from isolated cardiomyocytes, localizing to 3,232 and 3,128 unique proteins, respectively. In cardiac tissue, we identified 84 insulin-regulated phosphorylation events, including sites on the Insulin Receptor (InsrY1351, Y1175, Y1179, Y1180) itself as well as the Insulin receptor substrate protein 1 (Irs1S522, S526). Predicted kinases with increased activity in response to insulin stimulation included Rps6kb1, Akt1 and Mtor. Tbc1d4 emerged as a major phosphorylation target in cardiomyocytes. Despite limited impact on the global phosphorylation landscape, Tbc1d4 deficiency in cardiomyocytes attenuated insulin-induced Glut4 translocation and induced protein remodeling. We observed 15 proteins significantly regulated upon knockout of Tbc1d4. While Glut4 exhibited decreased protein abundance consequent to Tbc1d4-deficiency, Txnip levels were notably increased. Stimulation of wildtype cardiomyocytes with insulin led to the regulation of 262 significant phosphorylation events, predicted to be regulated by kinases such as Akt1, Mtor, Akt2, and Insr. In cardiomyocytes, the canonical insulin signaling response is elicited in addition to regulation on specialized cardiomyocyte proteins, such as Kcnj11Y12 and DspS2597. Details of all phosphorylation sites are provided.

CONCLUSION

We present a first global outline of the insulin-induced phosphorylation signaling response in heart tissue and in isolated adult cardiomyocytes, detailing the specific residues with changed phosphorylation abundances. Our study marks an important step towards understanding the role of insulin signaling in cardiac diseases linked to insulin resistance.

Impact of Diabetes and Glycemia on Cardiac Improvement and Adverse Events Following Mechanical Circulatory Support

BACKGROUND

Type 2 diabetes is prevalent in cardiovascular disease and contributes to excess morbidity and mortality. We sought to investigate the effect of glycemia on functional cardiac improvement, morbidity, and mortality in durable left ventricular assist device (LVAD) recipients.

METHODS AND RESULTS

Consecutive patients with an LVAD were prospectively evaluated (n=531). After excluding patients missing pre-LVAD glycated hemoglobin (HbA1c) measurements or having inadequate post-LVAD follow-up, 375 patients were studied. To assess functional cardiac improvement, we used absolute left ventricular ejection fraction change (ΔLVEF: LVEF post-LVAD-LVEF pre-LVAD). We quantified the association of pre-LVAD HbA1c with ΔLVEF as the primary outcome, and all-cause mortality and LVAD-related adverse event rates (ischemic stroke/transient ischemic attack, intracerebral hemorrhage, gastrointestinal bleeding, LVAD-related infection, device thrombosis) as secondary outcomes. Last, we assessed HbA1c differences pre- and post-LVAD. Patients with type 2 diabetes were older, more likely men suffering ischemic cardiomyopathy, and had longer heart failure duration. Pre-LVAD HbA1c was inversely associated with ΔLVEF in patients with nonischemic cardiomyopathy but not in those with ischemic cardiomyopathy, after adjusting for age, sex, heart failure duration, and left ventricular end-diastolic diameter. Pre-LVAD HbA1c was not associated with all-cause mortality, but higher pre-LVAD HbA1c was shown to increase the risk of intracerebral hemorrhage, LVAD-related infection, and device thrombosis by 3 years on LVAD support (P<0.05 for all). HbA1c decreased from 6.68±1.52% pre-LVAD to 6.11±1.33% post-LVAD (P<0.001).

CONCLUSIONS

Type 2 diabetes and pre-LVAD glycemia modify the potential for functional cardiac improvement and the risk for adverse events on LVAD support. The degree and duration of pre-LVAD glycemic control optimization to favorably affect these outcomes warrants further investigation.

Human cardiac metabolism

The heart is the most metabolically active organ in the human body, and cardiac metabolism has been studied for decades. However, the bulk of studies have focused on animal models. The objective of this review is to summarize specifically what is known about cardiac metabolism in humans. Techniques available to study human cardiac metabolism are first discussed, followed by a review of human cardiac metabolism in health and in heart failure. Mechanistic insights, where available, are reviewed, and the evidence for the contribution of metabolic insufficiency to heart failure, as well as past and current attempts at metabolism-based therapies, is also discussed.

Association between TyG index and long-term prognosis of patients with ST-segment elevated myocardial infarction undergoing percutaneous coronary intervention: a retrospective cohort study

OBJECTIVE

To assess the association between the serum triglyceride-glucose product index (TyG index) and the risk for all-cause mortality in patients with ST-segment elevated myocardial infarction (STEMI).

DESIGN

Retrospective.

SETTING AND PARTICIPANTS

This retrospective study included 896 patients with STEMI who underwent percutaneous coronary intervention (PCI) at a comprehensive university-affiliated hospital between January 2016 and January 2019.

METHODS

Patients were equally divided into quartiles (Q1, Q2, Q3 and Q4 group) according to TyG index values.

PRIMARY ENDPOINT

All-cause mortality.

RESULTS

After a median follow-up of 3 years, 108 (17.1%) patients died. TyG index was independently associated with increased all-cause mortality (OR, 1.39; 95% CI, 1.22 to 1.58) after adjusting for age, sex, low-density lipoprotein cholesterol (LDL-c), cardiac troponin I, B-type natriuretic peptide, delayed PCI, post-PCI complications, medication and left ventricular ejection fraction. The adjusted OR was 1.31 (95% CI, 0.62 to 2.77) for Q2, 2.12 (95% CI, 1.01 to 4.53) for Q3 and 4.02 (95% CI, 1.90 to 8.78) for Q4 compared with the lowest quartile (Q1) (p for trend<0.001). In the restricted cubic spline regression model, the relationship between the TyG index and the risk of all-cause mortality was linear (p for non-linear=0.575). Each unit increase in the TyG index was associated with a 68% increase in the multivariate risk for all-cause mortality (OR 1.68; 95% CI, 1.20 to 2.38). In the subgroup analysis, there was an interaction between LDL-c and the TyG index on the risk of all-cause mortality (p for interaction=0.007).

CONCLUSION

The TyG index was significantly associated with the long-term all-cause mortality among patients with STEMI who underwent PCI.

Loss of mitochondrial pyruvate transport initiates cardiac glycogen accumulation and heart failure

Background

Heart failure involves metabolic alterations including increased glycolysis despite unchanged or decreased glucose oxidation. The mitochondrial pyruvate carrier (MPC) regulates pyruvate entry into the mitochondrial matrix, and cardiac deletion of the MPC in mice causes heart failure. How MPC deletion results in heart failure is unknown.

Methods

We performed targeted metabolomics and isotope tracing in wildtype (fl/fl) and cardiac-specific Mpc2-/- (CS-Mpc2-/-) hearts after in vivo injection of U-13C-glucose. Cardiac glycogen was assessed biochemically and by transmission electron microscopy. Cardiac uptake of 2-deoxyglucose was measured and western blotting performed to analyze insulin signaling and enzymatic regulators of glycogen synthesis and degradation. Isotope tracing and glycogen analysis was also performed in hearts from mice fed either low-fat diet or a ketogenic diet previously shown to reverse the CS-Mpc2-/- heart failure. Cardiac glycogen was also assessed in mice infused with angiotensin-II that were fed low-fat or ketogenic diet.

Results

Failing CS-Mpc2-/- hearts contained normal levels of ATP and phosphocreatine, yet these hearts displayed increased enrichment from U-13C-glucose and increased glycolytic metabolite pool sizes. 13C enrichment and pool size was also increased for the glycogen intermediate UDP-glucose, as well as increased enrichment of the glycogen pool. Glycogen levels were increased ~6-fold in the failing CS-Mpc2-/- hearts, and glycogen granules were easily detected by electron microscopy. This increased glycogen synthesis occurred despite enhanced inhibitory phosphorylation of glycogen synthase and reduced expression of glycogenin-1. In young, non-failing CS-Mpc2-/- hearts, increased glycolytic 13C enrichment occurred, but glycogen levels remained low and unchanged compared to fl/fl hearts. Feeding a ketogenic diet to CS-Mpc2-/- mice reversed the heart failure and normalized the cardiac glycogen and glycolytic metabolite accumulation. Cardiac glycogen levels were also elevated in mice infused with angiotensin-II, and both the cardiac hypertrophy and glycogen levels were improved by ketogenic diet.

Conclusions

Our results indicate that loss of MPC in the heart causes glycogen accumulation and heart failure, while a ketogenic diet can reverse both the glycogen accumulation and heart failure. We conclude that maintaining mitochondrial pyruvate import and metabolism is critical for the heart, unless cardiac pyruvate metabolism is reduced by consumption of a ketogenic diet.

Deleting the ribosomal prolyl hydroxylase OGFOD1 protects mice against diet-induced obesity and insulin resistance

Type 2 diabetes predisposes patients to heart disease, which is the primary cause of death across the globe. Type 2 diabetes often accompanies obesity and is defined by insulin resistance and abnormal glucose handling. Insulin resistance impairs glucose uptake and results in hyperglycemia, which damages tissues such as kidneys, liver, and heart. 2-oxoglutarate (2-OG)- and iron-dependent oxygenases (2-OGDOs), a family of enzymes regulating various aspects of cellular physiology, have been studied for their role in obesity and diet-induced insulin resistance. However, nothing is known of the 2-OGDO family member 2-oxoglutarate and iron-dependent prolyl hydroxylase domain containing protein 1 (OGFOD1) in this setting. OGFOD1 deletion leads to protection in cardiac ischemia-reperfusion injury and cardiac hypertrophy, which are two cardiac events that can lead to heart failure. Considering the remarkable correlation between heart disease and diabetes, the cardioprotection observed in OGFOD1-knockout mice led us to challenge these knockouts with high-fat diet. Wildtype mice fed a high-fat diet developed diet-induced obesity, insulin resistance, and glucose intolerance, but OGFOD1 knockout mice fed this same diet were resistant to diet-induced obesity and insulin resistance. These results support OGFOD1 down-regulation as a strategy for preventing obesity and insulin handling defects.

Association between triglyceride glucose-waist to height ratio and coronary heart disease: a population-based study

BACKGROUND

The Triglyceride glucose (TyG) index-related indicators improve risk stratification by identifying individuals prone to atherosclerosis early in life. This study aimed to examine the relation between TyG-waist circumference-to-height ratio (TyG-WHtR) and coronary heart disease.

METHODS

Data from four National Health and Nutrition Examination Surveys (NHANES) cycles between 2011 and 2018 were used for a cross-sectional study. The association between TyG-WHtR and coronary heart disease risk was examined using a multifactorial logistic regression model, and corresponding subgroup analyses were performed. Nonlinear correlations were analyzed using smooth curve fitting and threshold effects analysis. When nonlinear connections were discovered, appropriate inflection points were investigated using recursive methods.

RESULTS

TyG-WHtR and coronary heart disease were significantly positively correlated in the multifactorial logistic regression analysis. Subgroup analyses and interaction tests revealed that gender, age, smoking status, and cancer were not significantly associated with this correlation (P for interaction > 0.05). Furthermore, utilizing threshold effect analysis and smooth curve fitting, a nonlinear connection with an inflection point of 0.36 was observed between TyG-WHtR and coronary heart disease.

CONCLUSIONS

According to this study, the American population is far more likely to have coronary heart disease if they have higher TyG-WHtR levels.

Insulin resistance in Takotsubo syndrome

AIMS

Takotsubo syndrome (TTS) is an acute heart failure (AHF) syndrome mimicking the symptoms of acute myocardial infarction. Impaired outcome has been shown, making risk stratification and novel therapeutic concepts a necessity. We hypothesized insulin resistance with elevated plasma glucose and potentially myocardial glucose deprivation to contribute to the pathogenesis of TTS and investigated the therapeutic benefit of insulin in vivo.

METHODS AND RESULTS

First, we retrospectively analysed patient data of n = 265 TTS cases (85.7% female, mean age 71.1 ± 14.1 years) with documented initial plasma glucose from the Department of Cardiology of the University Hospital Heidelberg in Germany (May 2011 to May 2021). Median split of the study population according to glucose levels (≤123 mg/dL vs. >123 mg/dL) yielded significantly elevated mean heart rate (80.75 ± 18.96 vs. 90.01 ± 22.19 b.p.m., P < 0.001), left ventricular end-diastolic pressure (LVEDP, 18.51 ± 8.35 vs. 23.09 ± 7.97 mmHg, P < 0.001), C-reactive protein (26.14 ± 43.30 vs. 46.4 ± 68.6 mg/L, P = 0.006), leukocyte count (10.12 ± 4.29 vs. 15.05 ± 9.83/nL, P < 0.001), peak high-sensitive Troponin T (hs-TnT, 515.44 ± 672.15 vs. 711.40 ± 736.37 pg/mL, P = 0.005), reduced left ventricular ejection fraction (EF, 34.92 ± 8.94 vs. 31.35 ± 8.06%, P < 0.001), and elevated intrahospital mortality (2.3% vs. 12.1%, P = 0.002) in the high-glucose group (Student's t-test, Mann-Whitney U test, or chi-squared test). Linear regression indicated a significant association of glucose with HR (P < 0.001), LVEDP (P = 0.014), hs-TnT kinetics from admission to the next day (P < 0.001), hs-TnT the day after admission (P < 0.001), as well as peak hsTnT (P < 0.001). Logistic regression revealed significant association of glucose with a composite intrahospital outcome including catecholamine use, respiratory support, and resuscitation [OR 1.010 (1.004-1.015), P = 0.001]. To further investigate the potential role of glucose in TTS pathophysiology experimentally, we utilized an in vivo murine model of epinephrine (EPI)-driven reversible AHF. For this, male mice underwent therapeutic injection of insulin (INS, 1 IU/kg) or/and glucose (GLU, 0.5 g/kg) after EPI (2.5 mg/kg), both of which markedly improved mean EF (EPI 34.3% vs. EPI + INS + GLU 43.7%, P = 0.025) and significantly blunted mean hs-TnT (EPI 14 393 pg/mL vs. EPI + INS 6864 pg/mL at 24 h, P = 0.039). Particularly, insulin additionally ameliorated myocardial pro-inflammatory gene expression, suggesting an anti-inflammatory effect of acute insulin therapy.

CONCLUSIONS

Elevated initial plasma glucose was associated with adverse outcome-relevant parameters in TTS and may present a surrogate parameter of heightened catecholaminergic drive. In mice, insulin- and glucose injection both improved EPI-induced AHF and myocardial damage, indicating insulin resistance rather than detrimental effects of hyperglycaemia itself as the underlying cause. Future studies will investigate the role of HbA1c as a risk stratifier and of insulin-based therapy in TTS.

Triglyceride-glucose index is associated with myocardial ischemia and poor prognosis in patients with ischemia and no obstructive coronary artery disease

BACKGROUND

Ischemia and no obstructive coronary artery disease (INOCA) is increasingly recognized and associated with poor outcomes. The triglyceride-glucose (TyG) index is a reliable alternative measure of insulin resistance significantly linked to cardiovascular disease and adverse prognosis. We investigated the association between the TyG index and myocardial ischemia and the prognosis in INOCA patients.

METHODS

INOCA patients who underwent both coronary angiography and myocardial perfusion imaging (MPI) were included consecutively. All participants were divided into three groups according to TyG tertiles (T1, T2, and T3). Abnormal MPI for myocardial ischemia in individual coronary territories was defined as summed stress score (SSS) ≥ 4 and summed difference score (SDS) ≥ 2. SSS refers to the sum of all defects in the stress images, and SDS is the difference of the sum of all defects between the rest images and stress images. All patients were followed up for major adverse cardiac events (MACE).

RESULTS

Among 332 INOCA patients, 113 (34.0%) had abnormal MPI. Patients with higher TyG index had a higher rate of abnormal MPI (25.5% vs. 32.4% vs. 44.1%; p = 0.012). Multivariate logistic analysis showed that a high TyG index was significantly correlated with abnormal MPI in INOCA patients (OR, 1.901; 95% CI, 1.045-3.458; P = 0.035). During the median 35 months of follow-up, 83 (25%) MACE were recorded, and a higher incidence of MACE was observed in the T3 group (T3 vs. T2 vs. T1: 36.9% vs. 21.6% vs. 16.4%, respectively; p = 0.001). In multivariate Cox regression analysis, the T3 group was significantly associated with the risk of MACE compared to the T1 group (HR, 2.338; 95% CI 1.253-4.364, P = 0.008).

CONCLUSION

This study indicates for the first time that the TyG index is significantly associated with myocardial ischemia and poor prognosis among INOCA patients.

Association between the triglyceride-glucose index and in-hospital major adverse cardiovascular events in patients with acute coronary syndrome: results from the Improving Care for Cardiovascular Disease in China (CCC)-Acute Coronary Syndrome project

OBJECTIVE

Although the TyG index is a reliable predictor of insulin resistance (IR) and cardiovascular disease, its effectiveness in predicting major adverse cardiac events in hospitalized acute coronary syndrome (ACS) patients has not been validated in large-scale studies. In this study, we aimed to explore the association between the TyG index and the occurrence of MACEs during hospitalization.

METHODS

We recruited ACS patients from the CCC-ACS (Improving Cardiovascular Care in China-ACS) database and calculated the TyG index using the formula ln(fasting triglyceride [mg/dL] × fasting glucose [mg/dL]/2). These patients were classified into four groups based on quartiles of the TyG index. The primary endpoint was the occurrence of MACEs during hospitalization, encompassing all-cause mortality, cardiac arrest, myocardial infarction (MI), and stroke. We performed Cox proportional hazards regression analysis to clarify the correlation between the TyG index and the risk of in-hospital MACEs among patients diagnosed with ACS. Additionally, we explored this relationship across various subgroups.

RESULTS

A total of 101,113 patients were ultimately included, and 2759 in-hospital MACEs were recorded, with 1554 (49.1%) cases of all-cause mortality, 601 (21.8%) cases of cardiac arrest, 251 (9.1%) cases of MI, and 353 (12.8%) cases of stroke. After adjusting for confounders, patients in TyG index quartile groups 3 and 4 showed increased risks of in-hospital MACEs compared to those in quartile group 1 [HR = 1.253, 95% CI 1.121-1.400 and HR = 1.604, 95% CI 1.437-1.791, respectively; p value for trend < 0.001], especially in patients with STEMI or renal insufficiency. Moreover, we found interactions between the TyG index and age, sex, diabetes status, renal insufficiency status, and previous PCI (all p values for interactions < 0.05).

CONCLUSIONS

In patients with ACS, the TyG index was an independent predictor of in-hospital MACEs. Special vigilance should be exercised in females, elderly individuals, and patients with renal insufficiency.

The association between triglyceride-glucose index and the likelihood of cardiovascular disease in the U.S. population of older adults aged ≥ 60 years: a population-based study

BACKGROUND

The association between the triglyceride-glucose (TyG) index and the likelihood of developing cardiovascular disease (CVD) in the general elderly population in the United States aged 60 and above is not well understood. The objective of our study was to examine the relationship between the TyG index and CVD likelihood in the general elderly population over 60 years of age in the United States.

METHODS

Data for this cross-sectional study were sourced from the 2003-2018 National Health and Nutrition Examination Survey. Weighted multivariable regression analysis and subgroup analysis were conducted to estimate the independent relationship between the TyG index and the likelihood of CVD. Non-linear correlations were explored using restricted cubic splines.

RESULTS

A total of 6502 participants were included, with a mean TyG index of 8.75 ± 0.01. The average prevalence of CVD was 24.31% overall. Participants in the higher TyG quartiles showed high rates of CVD (Quartile 1: 19.91%; Quartile 2: 21.65%; Quartile 3: 23.82%; Quartile 4: 32.43%). For CVD, a possible association between the TyG index and the odds of CVD was observed. Our findings suggest a nonlinear association between the TyG index and the odds of CVD. The threshold of 8.73 for the likelihood of CVD. Interaction terms were employed to assess heterogeneities among each subgroup, revealing a significant difference specifically in alcohol consumption. This suggests that the positive association between the TyG index and the likelihood of CVD is dependent on the drinking status of the participants.

CONCLUSION

A higher TyG index is linked to an increased likelihood of CVD in US adults aged ≥ 60 years. TyG index is anticipated to emerge as a more effective metric for identifying populations at early likelihood of CVD.

Association of non-insulin-based insulin resistance indices with disease severity and adverse outcome in idiopathic pulmonary arterial hypertension: a multi-center cohort study

BACKGROUND

Insulin resistance (IR) plays an important role in the pathophysiology of cardiovascular disease. Recent studies have shown that diabetes mellitus and impaired lipid metabolism are associated with the severity and prognosis of idiopathic pulmonary arterial hypertension (IPAH). However, the relationship between IR and pulmonary hypertension is poorly understood. This study explored the association between four IR indices and IPAH using data from a multicenter cohort.

METHODS

A total of 602 consecutive participants with IPAH were included in this study between January 2015 and December 2022. The metabolic score for IR (METS-IR), triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio, triglyceride and glucose (TyG) index, and triglyceride-glucose-body mass index (TyG-BMI) were used to quantify IR levels in patients with IPAH. The correlation between non-insulin-based IR indices and long-term adverse outcomes was determined using multivariate Cox regression models and restricted cubic splines.

RESULTS

During a mean of 3.6 years' follow-up, 214 participants experienced all-cause death or worsening condition. Compared with in low to intermediate-low risk patients, the TG/HDL-C ratio (2.9 ± 1.7 vs. 3.3 ± 2.1, P = 0.003) and METS-IR (34.5 ± 6.7 vs. 36.4 ± 7.5, P < 0.001) were significantly increased in high to intermediate-high risk patients. IR indices correlated with well-validated variables that reflected the severity of IPAH, such as the cardiac index and stroke volume index. Multivariate Cox regression analyses indicated that the TyG-BMI index (hazard ratio [HR] 1.179, 95% confidence interval [CI] 1.020, 1.363 per 1.0-standard deviation [SD] increment, P = 0.026) and METS-IR (HR 1.169, 95% CI 1.016, 1.345 per 1.0-SD increment, P = 0.030) independently predicted adverse outcomes. Addition of the TG/HDL-C ratio and METS-IR significantly improved the reclassification and discrimination ability beyond the European Society of Cardiology (ESC) risk score.

CONCLUSIONS

IR is associated with the severity and long-term prognosis of IPAH. TyG-BMI and METS-IR can independently predict clinical worsening events, while METS-IR also provide incremental predictive performance beyond the ESC risk stratification.

Salubrinal promotes phospho-eIF2α-dependent activation of UPR leading to autophagy-mediated attenuation of iron-induced insulin resistance

Identification of new mechanisms mediating insulin sensitivity is important to allow validation of corresponding therapeutic targets. In this study, we first used a cellular model of skeletal muscle cell iron overload and found that endoplasmic reticulum (ER) stress and insulin resistance occurred after iron treatment. Insulin sensitivity was assessed using cells engineered to express an Akt biosensor, based on nuclear FoxO localization, as well as western blotting for insulin signaling proteins. Use of salubrinal to elevate eIF2α phosphorylation and promote the unfolded protein response (UPR) attenuated iron-induced insulin resistance. Salubrinal induced autophagy flux and its beneficial effects on insulin sensitivity were not observed in autophagy-deficient cells generated by overexpressing a dominant-negative ATG5 mutant or via knockout of ATG7. This indicated the beneficial effect of salubrinal-induced UPR activation was autophagy-dependent. We translated these observations to an animal model of systemic iron overload-induced skeletal muscle insulin resistance where administration of salubrinal as pretreatment promoted eIF2α phosphorylation, enhanced autophagic flux in skeletal muscle and improved insulin responsiveness. Together, our results show that salubrinal elicited an eIF2α-autophagy axis leading to improved skeletal muscle insulin sensitivity both in vitro and in mice.

Novel molecular mechanisms of doxorubicin cardiotoxicity: latest leading-edge advances and clinical implications

Doxorubicin (Dox) is among the most widely used cancer chemotherapeutic drugs. The clinical use of Dox is, however, limited due to its cardiotoxicity. Studies over the past several decades have suggested various mechanisms of Dox-induced cardiotoxicity (DIC). Among them are oxidative stress, topoisomerase inhibition, and mitochondrial damage. Several novel molecular targets and signaling pathways underlying DIC have emerged over the past few years. The most notable advances include discovery of ferroptosis as a major form of cell death in Dox cytotoxicity, and elucidation of the involvement of cardiogenetics and regulatory RNAs as well as multiple other targets in DIC. In this review, we discuss these advances, focusing on latest cutting-edge research discoveries from mechanistic studies reported in influential journals rather than surveying all research studies available in the literature.

Mitochondrial energy metabolism in diabetic cardiomyopathy: Physiological adaption, pathogenesis, and therapeutic targets

ABSTRACT

Diabetic cardiomyopathy is defined as abnormal structure and function of the heart in the setting of diabetes, which could eventually develop heart failure and leads to the death of the patients. Although blood glucose control and medications to heart failure show beneficial effects on this disease, there is currently no specific treatment for diabetic cardiomyopathy. Over the past few decades, the pathophysiology of diabetic cardiomyopathy has been extensively studied, and an increasing number of studies pinpoint that impaired mitochondrial energy metabolism is a key mediator as well as a therapeutic target. In this review, we summarize the latest research in the field of diabetic cardiomyopathy, focusing on mitochondrial damage and adaptation, altered energy substrates, and potential therapeutic targets. A better understanding of the mitochondrial energy metabolism in diabetic cardiomyopathy may help to gain more mechanistic insights and generate more precise mitochondria-oriented therapies to treat this disease.

Insulin Resistance/Hyperinsulinemia, Neglected Risk Factor for the Development and Worsening of Heart Failure with Preserved Ejection Fraction

Heart failure (HF) has become a subject of continuous interest since it was declared a new pandemic in 1997 because of the exponential increase in hospitalizations for HF in the latest years. HF is the final state to which all heart diseases of different etiologies lead if not adequately treated. It is highly prevalent worldwide, with a progressive increase with age, reaching a prevalence of 10% in subjects over the age of 65 years. During the last two decades, it was possible to see that the prevalence of heart failure with preserved ejection fraction (HFpEF) was increasing while that of heart failure with reduced ejection fraction (HFrEF) was decreasing. HFpEF is typically characterized by concentric remodeling of the left ventricle (LV) with impaired diastolic function and increased filling pressures. Over the years, also the prevalence of insulin resistance (IR)/hyperinsulinemia (Hyperins) in the general adult population has progressively increased, primarily due to lifestyle changes, particularly in developed and developing countries, with a range that globally ranges between 15.5% and 46.5%. Notably, over 50% of patients with HF also have IR/Hyperins, and the percentage is even higher in those with HFpEF. In the scientific literature, it has been well highlighted that the increased circulating levels of insulin, associated with conditions of insulin resistance, are responsible for progressive cardiovascular alterations over the years that could stimulate the development and/or the worsening of HFpEF. The aim of this manuscript was to review the scientific literature that supports a pathophysiologic connection between IR/Hyperins and HFpEF to stimulate the scientific community toward the identification of hyperinsulinemia associated with insulin resistance as an independent cardiovascular risk factor in the development and worsening of HF, believing that its adequate screening in the general population and an appropriate treatment could reduce the prevalence of HFpEF and improve its progression.

Lithium downregulates phosphorylated acetyl‑CoA carboxylase 2 and attenuates mitochondrial fatty acid utilization and oxidative stress in cardiomyocytes

Acetyl-CoA carboxylase 2 plays a crucial role in regulating mitochondrial fatty acid oxidation in cardiomyocytes. Lithium, a monovalent cation known for its cardioprotective potential, has been investigated for its influence on mitochondrial bioenergetics. The present study explored whether lithium modulated acetyl-CoA carboxylase 2 and mitochondrial fatty acid metabolism in cardiomyocytes and the potential therapeutic applications of lithium in alleviating metabolic stress. Mitochondrial bioenergetic function, fatty acid oxidation, reactive oxygen species production, membrane potential and the expression of proteins involved in fatty acid metabolism in H9c2 cardiomyocytes treated with LiCl for 48 h was measured by using a Seahorse extracellular flux analyzer, fluorescence microscopy and western blotting. Small interfering RNA against glucose transporter type 4 was transfected into H9c2 cardiomyocytes for 48 h to induce metabolic stress mimicking insulin resistance. The results revealed that LiCl at a concentration of 0.3 mM (but not at a concentration of 0.1 or 1.0 mM) upregulated the expression of phosphorylated (p-)glycogen synthase kinase-3 beta and downregulated the expression of p-acetyl-CoA carboxylase 2 but did not affect the expression of adenosine monophosphate-activated protein kinase or calcineurin. Cotreatment with TWS119 (8 µM) and LiCl (0.3 mM) downregulated p-acetyl-CoA carboxylase 2 expression to a similar extent as did treatment with TWS119 (8 µM) alone. Moreover, LiCl (0.3 mM) inhibited mitochondrial fatty acid oxidation, improved coupling efficiency and the cellular respiratory control ratio, hindered reactive oxygen species production and proton leakage and restored mitochondrial membrane potential in glucose transporter type 4 knockdown-H9c2 cardiomyocytes. These findings suggested that low therapeutic levels of lithium can downregulate p-acetyl-CoA carboxylase 2, thus reducing mitochondrial fatty acid oxidation and oxidative stress in cardiomyocytes.

Post-translational modifications in diabetic cardiomyopathy

The increasing attention towards diabetic cardiomyopathy as a distinctive complication of diabetes mellitus has highlighted the need for standardized diagnostic criteria and targeted treatment approaches in clinical practice. Ongoing research is gradually unravelling the pathogenesis of diabetic cardiomyopathy, with a particular emphasis on investigating various post-translational modifications. These modifications dynamically regulate protein function in response to changes in the internal and external environment, and their disturbance of homeostasis holds significant relevance for the development of chronic ailments. This review provides a comprehensive overview of the common post-translational modifications involved in the initiation and progression of diabetic cardiomyopathy, including O-GlcNAcylation, phosphorylation, methylation, acetylation and ubiquitination. Additionally, the review discusses drug development strategies for targeting key post-translational modification targets, such as agonists, inhibitors and PROTAC (proteolysis targeting chimaera) technology that targets E3 ubiquitin ligases.

Cholecalciferol ameliorates insulin signalling and insulin regulation of enzymes involved in glucose metabolism in the rat heart

CONTEXT

The evidence on potential cross-talk of vitamin D and insulin in the regulation of cardiac metabolism is very scanty.

OBJECTIVE

Cholecalciferol was administered to male Wistar rats for six weeks to study its effects on cardiac glucose metabolism regulation.

MATERIALS AND METHODS

An expression, phosphorylation and/or subcellular localisation of insulin signalling molecules, glucose transport and metabolism key proteins were studied.

RESULTS

Circulating non-esterified fatty acids (NEFA) level was lower after cholecalciferol administration. Cholecalciferol decreased cardiac insulin receptor substrate 1 Ser307 phosphorylation, while insulin-stimulated Akt Thr308 phosphorylation was increased. Cardiac 6-phosphofructo-2-kinase protein, hexokinase 2 mRNA level and insulin-stimulated glycogen synthase kinase 3β Ser9 phosphorylation were also increased. Finally, FOXO1 transcription factor cytosolic level was reduced.

CONCLUSION

Vitamin D-related improvement of insulin signalling and insulin regulation of glucose metabolism in the rat heart is accompanied by the decrease of blood NEFA level and dysregulation of cardiac FOXO1 signalling.

Impaired Ischemia-Reperfusion Responses in the Hearts of Aged Male and Female Offspring of Obese Rats

Maternal obesity predisposes offspring (F1) to cardiovascular disease. To evaluate basal heart function and ischemia-reperfusion (IR) responses in F1 males and females of obese mothers, female Wistar rats (F0) were fed chow or an obesogenic (MO) diet from weaning through pregnancy and lactation. Non-sibling F1 males and females were weaned to chow at postnatal day (PND) 21 and euthanized at PND 550. Offspring of MO mothers (MOF1) rarely survive beyond PND 650. Hearts were immediately isolated from euthanized F1s and subjected to 30 min ischemia with 20 min reperfusion. Retroperitoneal fat, serum triglycerides, glucose, insulin, and insulin resistance were measured. Baseline left ventricular developed pressure (LVDP) was lower in male and female MOF1 than in controls. After global ischemia, LVDP in control (C) male and female F1 recovered 78 and 83%, respectively, while recovery in MO male and female F1 was significantly lower at 28 and 52%, respectively. Following the IR challenge, MO hearts showed a higher functional susceptibility to reperfusion injury, resulting in lower cardiac reserve than controls in both sexes. Female hearts were more resistant to IR. Retroperitoneal fat was increased in male MOF1 vs. CF1. Circulating triglycerides and insulin resistance were increased in male and female MOF1 vs. CF1. These data show that MO programming reduces F1 cardiac reserve associated with age-related insulin resistance in a sex-specific manner.

The JMJD family of histone demethylase and their intimate links to cardiovascular disease

The incidence rate and mortality rate of cardiovascular disease rank first in the world. It is associated with various high-risk factors, and there is no single cause. Epigenetic modifications, such as DNA methylation or histone modification, actively participate in the initiation and development of cardiovascular diseases. Histone lysine methylation is a type of histone post-translational modification. The human Jumonji C domain (JMJD) protein family consists of more than 30 members. JMJD proteins participate in many key nuclear processes and play a key role in the specific regulation of gene expression, DNA damage and repair, and DNA replication. Importantly, increasing evidence shows that JMJD proteins are abnormally expressed in cardiovascular diseases, which may be a potential mechanism for the occurrence and development of these diseases. Here, we discuss the key roles of JMJD proteins in various common cardiovascular diseases. This includes histone lysine demethylase, which has been studied in depth, and less-studied JMJD members. Furthermore, we focus on the epigenetic changes induced by each JMJD member, summarize recent research progress, and evaluate their relationship with cardiovascular diseases and therapeutic potential.

The Role of Gut Microbiota and the Potential Effects of Probiotics in Heart Failure

Heart failure (HF) remains a significant global health challenge, affecting millions of individuals worldwide and posing a substantial burden on healthcare systems. HF is a syndrome of intricate pathophysiology, involving systemic inflammation, oxidative stress, metabolic perturbations, and maladaptive structural changes in the heart. It is influenced by complex interactions between cardiac function, systemic physiology, and environmental factors. Among these factors, the gut microbiota has emerged as a novel and intriguing player in the landscape of HF pathophysiology. The gut microbiota, beyond its role in digestion and nutrient absorption, impacts immune responses, metabolic processes, and, as suggested by evidence in the literature, the development and progression of HF. There is a bidirectional communication between the gut and the heart, often known as the gut-heart axis, through which gut microbiota-derived metabolites, immune signals, and microbial products exert profound effects on cardiovascular health. This review aims to provide a comprehensive overview of the intricate relationship between the gut microbiota and HF. Additionally, we explore the potential of using probiotics as a therapeutic strategy to modulate the gut microbiota's composition and attenuate the adverse effects observed in HF. Conventional therapeutic approaches targeting hemodynamic and neurohormonal dysregulation have substantially improved the management of HF, but emerging research is exploring the potential implications of harnessing the gut microbiota for innovative approaches in HF treatment.

Advances in Metabolic Remodeling and Intervention Strategies in Heart Failure

The heart is the most energy-demanding organ throughout the whole body. Perturbations or failure in energy metabolism contributes to heart failure (HF), which represents the advanced stage of various heart diseases. The poor prognosis and huge economic burden associated with HF underscore the high unmet need to explore novel therapies targeting metabolic modulators beyond conventional approaches focused on neurohormonal and hemodynamic regulators. Emerging evidence suggests that alterations in metabolic substrate reliance, metabolic pathways, metabolic by-products, and energy production collectively regulate the occurrence and progression of HF. In this review, we provide an overview of cardiac metabolic remodeling, encompassing the utilization of free fatty acids, glucose metabolism, ketone bodies, and branched-chain amino acids both in the physiological condition and heart failure. Most importantly, the latest advances in pharmacological interventions are discussed as a promising therapeutic approach to restore cardiac function, drawing insights from recent basic research, preclinical and clinical studies.

Immunomodulation and immunopharmacology in heart failure

The immune system is intimately involved in the pathophysiology of heart failure. However, it is currently underused as a therapeutic target in the clinical setting. Moreover, the development of novel immunomodulatory therapies and their investigation for the treatment of patients with heart failure are hampered by the fact that currently used, evidence-based treatments for heart failure exert multiple immunomodulatory effects. In this Review, we discuss current knowledge on how evidence-based treatments for heart failure affect the immune system in addition to their primary mechanism of action, both to inform practising physicians about these pleiotropic actions and to create a framework for the development and application of future immunomodulatory therapies. We also delineate which subpopulations of patients with heart failure might benefit from immunomodulatory treatments. Furthermore, we summarize completed and ongoing clinical trials that assess immunomodulatory treatments in heart failure and present several therapeutic targets that could be investigated in the future. Lastly, we provide future directions to leverage the immunomodulatory potential of existing treatments and to foster the investigation of novel immunomodulatory therapeutics.