An Effective Sodium-Dependent Glucose Transporter 2 Inhibition, Canagliflozin, Prevents Development of Hypertensive Heart Failure in Dahl Salt-Sensitive Rats

Exploring Sirtuins: New Frontiers in Managing Heart Failure with Preserved Ejection Fraction

With increasing research, the sirtuin (SIRT) protein family has become increasingly understood. Studies have demonstrated that SIRTs can aid in metabolism and affect various physiological processes, such as atherosclerosis, heart failure (HF), hypertension, type 2 diabetes, and other related disorders. Although the pathogenesis of HF with preserved ejection fraction (HFpEF) has not yet been clarified, SIRTs have a role in its development. Therefore, SIRTs may offer a fresh approach to the diagnosis, treatment, and prevention of HFpEF as a novel therapeutic intervention target.

Proteomics of the heart

Mass spectrometry-based proteomics is a sophisticated identification tool specializing in portraying protein dynamics at a molecular level. Proteomics provides biologists with a snapshot of context-dependent protein and proteoform expression, structural conformations, dynamic turnover, and protein-protein interactions. Cardiac proteomics can offer a broader and deeper understanding of the molecular mechanisms that underscore cardiovascular disease, and it is foundational to the development of future therapeutic interventions. This review encapsulates the evolution, current technologies, and future perspectives of proteomic-based mass spectrometry as it applies to the study of the heart. Key technological advancements have allowed researchers to study proteomes at a single-cell level and employ robot-assisted automation systems for enhanced sample preparation techniques, and the increase in fidelity of the mass spectrometers has allowed for the unambiguous identification of numerous dynamic posttranslational modifications. Animal models of cardiovascular disease, ranging from early animal experiments to current sophisticated models of heart failure with preserved ejection fraction, have provided the tools to study a challenging organ in the laboratory. Further technological development will pave the way for the implementation of proteomics even closer within the clinical setting, allowing not only scientists but also patients to benefit from an understanding of protein interplay as it relates to cardiac disease physiology.

Canagliflozin combined with aerobic exercise protects against chronic heart failure in rats

To determine the efficacy and potential protective mechanism of canagliflozin combined with aerobic exercise in treating chronic heart failure (CHF). Isoproterenol was injected into rats to create CHF models. The rats were then subsequently divided into saline, canagliflozin (3 mg/kg/d), aerobic exercise training, and canagliflozin combined with aerobic exercise training. Compared to the CHF group, the canagliflozin combined with the aerobic exercise group had superior ventricular remodeling and cardiac function. In rats treated with canagliflozin combined with aerobic exercise, the expression of cytochrome P450 (CYP) 4A3, CYP4A8, COL1A1, COL3A1, and FN1 was reduced, while the expression of CYP26B1, ALDH1A2, and CYP1A1 increased significantly. Additionally, canagliflozin combined with aerobic exercise decreased the phosphorylation of AKT and ERK1/2. Canagliflozin combined with aerobic exercise has a positive effect on the development of CHF via the regulation of retinol metabolism and the AKT/ERK signaling pathway.

The changes of cardiac energy metabolism with sodium-glucose transporter 2 inhibitor therapy

Background/aims

To investigate the specific effects of s odium-glucose transporter 2 inhibitor (SGLT2i) on cardiac energy metabolism.

Methods

A systematic literature search was conducted in eight databases. The retrieved studies were screened according to the inclusion and exclusion criteria, and relevant information was extracted according to the purpose of the study. Two researchers independently screened the studies, extracted information, and assessed article quality.

Results

The results of the 34 included studies (including 10 clinical and 24 animal studies) showed that SGLT2i inhibited cardiac glucose uptake and glycolysis, but promoted fatty acid (FA) metabolism in most disease states. SGLT2i upregulated ketone metabolism, improved the structure and functions of myocardial mitochondria, alleviated oxidative stress of cardiomyocytes in all literatures. SGLT2i increased cardiac glucose oxidation in diabetes mellitus (DM) and cardiac FA metabolism in heart failure (HF). However, the regulatory effects of SGLT2i on cardiac FA metabolism in DM and cardiac glucose oxidation in HF varied with disease types, stages, and intervention duration of SGLT2i.

Conclusion

SGLT2i improved the efficiency of cardiac energy production by regulating FA, glucose and ketone metabolism, improving mitochondria structure and functions, and decreasing oxidative stress of cardiomyocytes under pathological conditions. Thus, SGLT2i is deemed to exert a benign regulatory effect on cardiac metabolic disorders in various diseases.

Systematic review registration

https://www.crd.york.ac.uk/, PROSPERO (CRD42023484295).

Canagliflozin Ameliorates Ventricular Remodeling through Apelin/Angiotensin-Converting Enzyme 2 Signaling in Heart Failure with Preserved Ejection Fraction Rats

INTRODUCTION

The aim of this study was to investigate the effect of canagliflozin (CANA) on ventricular remodeling in patients with preserved ejection fraction (HFpEF) heart failure and to further investigate its possible molecular mechanisms.

METHODS

A high-salt diet was used to induce the formation of HFpEF model in salt-sensitive rats. The rats were fed with CANA and irbesartan, respectively. The mice were divided into control group, model group, CANA group, irbesartan group, and combined drug group. After 12 weeks of feeding, the rats were evaluated by measuring the relevant indexes and echocardiography for cardiac function. Histological analysis was performed using Masson trichrome staining and immunohistochemical staining. RT-qPCR and Western blot were used to quantify the relevant genes and proteins.

RESULTS

In this study, CANA exhibited diuresis, decreased blood pressure, weight loss, and increased food and water intake. Following a high-salt diet, Dahl salt-sensitive rats developed hypertension followed by left ventricular diastolic dysfunction, myocardial fibrosis, and left ventricular remodeling. Myocardial hypertrophy and fibrosis were reduced, and left ventricular diastolic function and ventricular remodeling improved after CANA treatment. The combination of CANA and irbesartan was superior to monotherapy in reducing blood pressure and improving cardiac insufficiency and left ventricular diastolic dysfunction in rats. CANA improves myocardial fibrosis, left ventricular diastolic dysfunction, and ventricular remodeling by upregulating apelin, activating angiotensin-converting enzyme 2 (ACE2), and increasing ACE2/Ang (1-7)/MASR axis levels.

CONCLUSION

CANA improves myocardial fibrosis, left ventricular diastolic dysfunction, and ventricular remodeling in HFpEF rats through upregulation of apelin/ACE2 signaling.

SGLT2 inhibitors: role in protective reprogramming of cardiac nutrient transport and metabolism

Sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce heart failure events by direct action on the failing heart that is independent of changes in renal tubular function. In the failing heart, nutrient transport into cardiomyocytes is increased, but nutrient utilization is impaired, leading to deficient ATP production and the cytosolic accumulation of deleterious glucose and lipid by-products. These by-products trigger downregulation of cytoprotective nutrient-deprivation pathways, thereby promoting cellular stress and undermining cellular survival. SGLT2 inhibitors restore cellular homeostasis through three complementary mechanisms: they might bind directly to nutrient-deprivation and nutrient-surplus sensors to promote their cytoprotective actions; they can increase the synthesis of ATP by promoting mitochondrial health (mediated by increasing autophagic flux) and potentially by alleviating the cytosolic deficiency in ferrous iron; and they might directly inhibit glucose transporter type 1, thereby diminishing the cytosolic accumulation of toxic metabolic by-products and promoting the oxidation of long-chain fatty acids. The increase in autophagic flux mediated by SGLT2 inhibitors also promotes the clearance of harmful glucose and lipid by-products and the disposal of dysfunctional mitochondria, allowing for mitochondrial renewal through mitochondrial biogenesis. This Review describes the orchestrated interplay between nutrient transport and metabolism and nutrient-deprivation and nutrient-surplus signalling, to explain how SGLT2 inhibitors reverse the profound nutrient, metabolic and cellular abnormalities observed in heart failure, thereby restoring the myocardium to a healthy molecular and cellular phenotype.

Targeting epicardial adipose tissue: A potential therapeutic strategy for heart failure with preserved ejection fraction with type 2 diabetes mellitus

Heart failure with preserved ejection fraction (HFpEF) is a heterogeneous syndrome with various comorbidities, multiple cardiac and extracardiac pathophysiologic abnormalities, and diverse phenotypic presentations. Since HFpEF is a heterogeneous disease with different phenotypes, individualized treatment is required. HFpEF with type 2 diabetes mellitus (T2DM) represents a specific phenotype of HFpEF, with about 45%-50% of HFpEF patients suffering from T2DM. Systemic inflammation associated with dysregulated glucose metabolism is a critical pathological mechanism of HFpEF with T2DM, which is intimately related to the expansion and dysfunction (inflammation and hypermetabolic activity) of epicardial adipose tissue (EAT). EAT is well established as a very active endocrine organ that can regulate the pathophysiological processes of HFpEF with T2DM through the paracrine and endocrine mechanisms. Therefore, suppressing abnormal EAT expansion may be a promising therapeutic strategy for HFpEF with T2DM. Although there is no treatment specifically for EAT, lifestyle management, bariatric surgery, and some pharmaceutical interventions (anti-cytokine drugs, statins, proprotein convertase subtilisin/kexin type 9 inhibitors, metformin, glucagon-like peptide-1 receptor agonists, and especially sodium-glucose cotransporter-2 inhibitors) have been shown to attenuate the inflammatory response or expansion of EAT. Importantly, these treatments may be beneficial in improving the clinical symptoms or prognosis of patients with HFpEF. Accordingly, well-designed randomized controlled trials are needed to validate the efficacy of current therapies. In addition, more novel and effective therapies targeting EAT are needed in the future.

Activation of the sirtuin silent information regulator 1 pathway inhibits pathological myocardial remodeling

Myocardial remodeling refers to structural and functional disorders of the heart caused by molecular biological changes in the cardiac myocytes in response to neurological and humoral factors. A variety of heart diseases, such as hypertension, coronary artery disease, arrhythmia, and valvular heart disease, can cause myocardial remodeling and eventually lead to heart failure. Therefore, counteracting myocardial remodeling is essential for the prevention and treatment of heart failure. Sirt1 is a nicotinamide adenine dinucleotide⁺-dependent deacetylase that plays a wide range of roles in transcriptional regulation, energy metabolism regulation, cell survival, DNA repair, inflammation, and circadian regulation. It positively or negatively regulates myocardial remodeling by participating in oxidative stress, apoptosis, autophagy, inflammation, and other processes. Taking into account the close relationship between myocardial remodeling and heart failure and the involvement of SIRT1 in the development of the former, the role of SIRT1 in the prevention of heart failure via inhibition of myocardial remodeling has received considerable attention. Recently, multiple studies have been conducted to provide a better understanding of how SIRT1 regulates these phenomena. This review presents the progress of research involving SIRT1 pathway involvement in the pathophysiological mechanisms of myocardial remodeling and heart failure.

Critical Reanalysis of the Mechanisms Underlying the Cardiorenal Benefits of SGLT2 Inhibitors and Reaffirmation of the Nutrient Deprivation Signaling/Autophagy Hypothesis

SGLT2 (sodium-glucose cotransporter 2) inhibitors produce a distinctive pattern of benefits on the evolution and progression of cardiomyopathy and nephropathy, which is characterized by a reduction in oxidative and endoplasmic reticulum stress, restoration of mitochondrial health and enhanced mitochondrial biogenesis, a decrease in proinflammatory and profibrotic pathways, and preservation of cellular and organ integrity and viability. A substantial body of evidence indicates that this characteristic pattern of responses can be explained by the action of SGLT2 inhibitors to promote cellular housekeeping by enhancing autophagic flux, an effect that may be related to the action of these drugs to produce simultaneous upregulation of nutrient deprivation signaling and downregulation of nutrient surplus signaling, as manifested by an increase in the expression and activity of AMPK (adenosine monophosphate-activated protein kinase), SIRT1 (sirtuin 1), SIRT3 (sirtuin 3), SIRT6 (sirtuin 6), and PGC1-α (peroxisome proliferator-activated receptor γ coactivator 1-α) and decreased activation of mTOR (mammalian target of rapamycin). The distinctive pattern of cardioprotective and renoprotective effects of SGLT2 inhibitors is abolished by specific inhibition or knockdown of autophagy, AMPK, and sirtuins. In the clinical setting, the pattern of differentially increased proteins identified in proteomics analyses of blood collected in randomized trials is consistent with these findings. Clinical studies have also shown that SGLT2 inhibitors promote gluconeogenesis, ketogenesis, and erythrocytosis and reduce uricemia, the hallmarks of nutrient deprivation signaling and the principal statistical mediators of the ability of SGLT2 inhibitors to reduce the risk of heart failure and serious renal events. The action of SGLT2 inhibitors to augment autophagic flux is seen in isolated cells and tissues that do not express SGLT2 and are not exposed to changes in environmental glucose or ketones and may be related to an ability of these drugs to bind directly to sirtuins or mTOR. Changes in renal or cardiovascular physiology or metabolism cannot explain the benefits of SGLT2 inhibitors either experimentally or clinically. The direct molecular effects of SGLT2 inhibitors in isolated cells are consistent with the concept that SGLT2 acts as a nutrient surplus sensor, and thus, its inhibition causes enhanced nutrient deprivation signaling and its attendant cytoprotective effects, which can be abolished by specific inhibition or knockdown of AMPK, sirtuins, and autophagic flux.

The diagnostic value of peroxisome proliferator-activated receptor-γ coactivator-1α in identifying different chronic heart failure phenotypes

Background

Despite advances in diagnosing and treating chronic heart failure (HF), the underlying mechanisms in different HF phenotypes remain unclear. Mitochondrial energy metabolism is crucial in HF etiology. Our study aimed to explore the value of metabolic-associated biomarker peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α) in identifying different HF phenotypes.

Methods

A total of 172 participants were enrolled in the Affiliated Hospital of Xuzhou Medical University and were subsequently divided into four groups based on the European Society of Cardiology HF management guideline: the non-HF control (Control, N = 46), heart failure with reduced ejection fraction (HFrEF, N = 54), heart failure with mildly reduced ejection fraction (HFmrEF, N = 22), and heart failure with preserved ejection fraction (HFpEF, N = 50) groups. Each participant’s baseline data were recorded, blood samples were taken, and echocardiography was conducted. The level of PGC1α expression was determined using an enzyme-linked immunosorbent assay (ELISA) kit. The receiver operative characteristics (ROC) curve was further established in the four groups to assess the diagnostic value for overall HF and each HF phenotype with the calculation of the area under the curve (AUC) and 95% confidence interval (CI).

Results

PGC1α expression was significantly increased in HF patients (315.0 ± 69.58 nmol/L) compared to non-HF participants (233.3 ± 32.69 nmol/L). Considering different HF phenotypes, PGC1α expression was considerably higher in the HFmrEF group (401.6 ± 45.1 nmol/L)than in the other two phenotypes (299.5 ± 62.27 nmol/L for HFrEF and 293.5 ± 56.37 nmol/L for HFpEF, respectively).Furthermore, the AUCs of PGC1α in overall HF and each HF phenotype were all over 0.8, showing the ideal diagnostic value. Additionally, we provided the cut-off criteria for clinical use, which needs further validation. There was no significant correlation between PGC1α and N-terminal (NT)-prohormone B-type natriuretic peptide (BNP)/blood glucose, suggesting that PGC1α might exert a unique function in HF yet in a different pattern.

Conclusion

We discovered that PGC1α could be used as a potential biomarker for differentiating HF patients from those without HF and for distinguishing HFmrEF from HFrEF and HFpEF.

Effect of Sodium-Glucose Co-transporter Protein 2 Inhibitors on Arrhythmia in Heart Failure Patients With or Without Type 2 Diabetes: A Meta-Analysis of Randomized Controlled Trials

Aim

Arrhythmic events such as atrial fibrillation (AF) are tightly associated with an increased risk of heart failure (HF). Previous studies have shown inconsistent results regarding the association between sodium-glucose co-transporter 2 inhibitors (SGLT2i) and the risk of arrhythmia. The purpose of this study was to investigate the association of SGLT2i treatment with arrhythmia outcomes in clinical trials of patients with HF.

Methods

We searched Embase, PubMed, Web of Science, Medline, The Cochrane Library, and JAMA databases to identify appropriate randomized controlled trials (RCTs) of SGLT2i interventions. Endpoint outcomes included AF, atrial flutter (AFL), AF/AFL, ventricular fibrillation (VF), ventricular tachycardia (VT), VF/VT, and bradycardia. A random-effects model was used for the meta-analysis of all outcomes. The risk of bias and quality of evidence was assessed by using the Cochrane tool and assessment framework.

Results

Out of 1,725 citations, 9 trials were included in this study, with follow-up from 4 weeks to 52 weeks for 10,344 participants (mean age 68.27 years; 69.62% of participants were men). Compared with placebo, SGLT2i reduced the incidence of AF by 37% [ratio risk (RR) 0.63; 95% confidence interval (CI) 0.45–0.87; p < 0.05] and AF/AFL by 34% (RR 0.66; 95% CI 0.49–0.90; p < 0.05).

Conclusions

SGLT2i can reduce the risk of cardiac arrhythmias, particularly the AF. Our study provides strong evidence for recommending the use of SGLT2i in patients with HF.

Systematic Review Registration

PROSPERO, identifier: CRD42022296696.