Empagliflozin decreases myocardial cytoplasmic Na+ through inhibition of the cardiac Na+/H+ exchanger in rats and rabbits

Predicted Cardiac Functional Responses to Renal Actions of SGLT2i in the DAPACARD Trial Population: A Mathematical Modeling Analysis

Sodium-glucose cotransporter-2 inhibitors (SGLT2is) have been shown to reduce the risk of worsening heart failure (HF) in subjects with HF and a reduced ejection fraction (HFrEF) in multiple clinical trials. The DAPACARD clinical trial was conducted to examine the effects of DAPAgliflozin on CARDiac substrate uptake, myocardial efficiency, and myocardial contractile work in type 2 diabetes mellitus (T2DM) subjects. As a complement to the clinical study, a mechanistic mathematical model of cardiorenal physiology was used to quantify the influence of established natriuretic/diuretic effects of SGLT2i on cardiac function (myocardial efficiency and global longitudinal strain). Virtual participants reflecting the participant-level characteristics in the DAPACARD trial were produced by varying model parameters over physiologically plausible ranges. A second virtual population was generated by inducing a state of HFrEF in the DAPACARD T2DM virtual participants (DAPACARD-HFrEF virtual participants) for comparison. Cardiac responses to placebo and SGLT2i were simulated over 42 days. Cardiac hemodynamic improvements were predicted in DAPACARD-HFrEF virtual participants but not in DAPACARD virtual participants. In particular, the natriuresis/diuresis induced by SGLT2i improved the global longitudinal strain and myocardial efficiency in DAPACARD-HFrEF virtual participants within the first 14 days (change from baseline: global longitudinal strain: -0.95% and myocardial efficiency: 0.34%), whereas the global longitudinal strain and myocardial efficiency in DAPACARD virtual participants were slightly worse (change from baseline: global longitudinal strain: 0.35% and myocardial efficiency: -0.01%). The results of the DAPACARD virtual participants modeling were in line with the clinical data but do not preclude additional effects from other mechanisms of SGLT2i. This article is protected by copyright. All rights reserved.

Cardiovascular Benefits from Gliflozins: Effects on Endothelial Function

Type 2 diabetes mellitus (T2DM) is a known independent risk factor for atherosclerotic cardiovascular disease (CVD) and solid epidemiological evidence points to heart failure (HF) as one of the most common complications of diabetes. For this reason, it is imperative to consider the prevention of CV outcomes as an effective goal for the management of diabetic patients, as important as lowering blood glucose. Endothelial dysfunction (ED) is an early event of atherosclerosis involving adhesion molecules, chemokines, and leucocytes to enhance low-density lipoprotein oxidation, platelet activation, and vascular smooth muscle cell proliferation and migration. This abnormal vascular phenotype represents an important risk factor for the genesis of any complication of diabetes, contributing to the pathogenesis of not only macrovascular disease but also microvascular damage. Gliflozins are a novel class of anti-hyperglycemic agents used for the treatment of Type 2 diabetes mellitus (T2DM) that selectively inhibit the sodium glucose transporter 2 (SGLT2) in the kidneys and have provoked large interest in scientific community due to their cardiovascular beneficial effects, whose underlying pathophysiology is still not fully understood. This review aimed to analyze the cardiovascular protective mechanisms of SGLT2 inhibition in patients T2DM and their impact on endothelial function.

Effects of SGLT2 Inhibitors on Ion Homeostasis and Oxidative Stress associated Mechanisms in Heart Failure

Sodium-glucose cotransporter 2 (SGLT2) inhibitors present a class of antidiabetic drugs, which inhibit renal glucose reabsorption resulting in the elevation of urinary glucose levels. Within the past years, SGLT2 inhibitors have become increasingly relevant due to their effects beyond glycemic control in patients with type 2 diabetes (T2DM). Although dedicated large trials demonstrated cardioprotective effects of SGLT2 inhibitors, the exact mechanisms responsible for those benefits have not been fully identified. Alterations in Ca²⁺ signaling and oxidative stress accompanied by excessive reactive oxygen species (ROS) production, fibrosis and inflammatory processes form cornerstones of potential molecular targets for SGLT2 inhibitors. This review focused on three hypotheses for SGLT2 inhibitor-mediated cardioprotection: ion homeostasis, oxidative stress and endothelial dysfunction.

Similarities and Differences Between HFmrEF and HFpEF

The new guidelines classify heart failure (HF) into three subgroups based on the ejection fraction (EF): HF with reduced EF (HFrEF), HF with mid-range EF (HFmrEF), and HF with preserved EF (HFpEF). The new guidelines regarding the declaration of HFmrEF as a unique phenotype have achieved the goal of stimulating research on the basic characteristics, pathophysiology, and treatment of HF patients with a left ventricular EF of 40-49%. Patients with HFmrEF have more often been described as an intermediate population between HFrEF and HFpEF patients; however, with regard to etiology and clinical indicators, they are more similar to the HFrEF population. Concerning clinical prognosis, they are closer to HFpEF because both populations have a good prognosis and quality of life. Meanwhile, growing evidence indicates that HFmrEF and HFpEF show heterogeneity in presentation and pathophysiology, and the emergence of this heterogeneity often plays a crucial role in the prognosis and treatment of the disease. To date, the exact mechanisms and effective treatment strategies of HFmrEF and HFpEF are still poorly understood, but some of the current evidence, from observational studies and post-hoc analyses of randomized controlled trials, have shown that patients with HFmrEF may benefit more from HFrEF treatment strategies, such as beta-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, mineralocorticoid receptor antagonists, and sacubitril/valsartan. This review summarizes available data from current clinical practice and mechanistic studies in terms of epidemiology, etiology, clinical indicators, mechanisms, and treatments to discuss the potential association between HFmrEF and HFpEF patients.

SGLT2 Inhibitors and Their Mode of Action in Heart Failure-Has the Mystery Been Unravelled?

PURPOSE OF REVIEW

SGLT2 inhibitors (SGLT2i) are new drugs for patients with heart failure (HF) irrespective of diabetes. However, the mechanisms of SGLT2i in HF remain elusive. This article discusses the current clinical evidence for using SGLT2i in different types of heart failure and provides an overview about the possible underlying mechanisms.

RECENT FINDINGS

Clinical and basic data strongly support and extend the use of SGLT2i in HF. Improvement of conventional secondary risk factors is unlikely to explain the prognostic benefits of these drugs in HF. However, different multidirectional mechanisms of SGLT2i could improve HF status including volume regulation, cardiorenal mechanisms, metabolic effects, improved cardiac remodelling, direct effects on cardiac contractility and ion-homeostasis, reduction of inflammation and oxidative stress as well as an impact on autophagy and adipokines. Further translational studies are needed to determine the mechanisms of SGLT2i in HF. However, basic and clinical evidence encourage the use of SGLT2i in HFrEF and possibly HFpEF.

Effects of canagliflozin on NT-proBNP stratified by left ventricular diastolic function in patients with type 2 diabetes and chronic heart failure: a sub analysis of the CANDLE trial

Background

Identification of the effective subtypes of treatment for heart failure (HF) is an essential topic for optimizing treatment of the disorder. We hypothesized that the beneficial effect of SGLT2 inhibitors (SGLT2i) on the levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) might depend on baseline diastolic function. To elucidate the effects of SGLT2i in type 2 diabetes mellitus (T2DM) and chronic HF we investigated, as a post-hoc sub-study of the CANDLE trial, the effects of canagliflozin on NT-proBNP levels from baseline to 24 weeks, with the data stratified by left ventricular (LV) diastolic function at baseline.

Methods

Patients (n = 233) in the CANDLE trial were assigned randomly to either an add-on canagliflozin (n = 113) or glimepiride treatment groups (n = 120). The primary endpoint was a comparison between the two groups of the changes from baseline to 24 weeks in NT-pro BNP levels, stratified according to baseline ventricular diastolic function.

Results

The change in the geometric mean of NT-proBNP level from baseline to 24 weeks was 0.98 (95% CI 0.89–1.08) in the canagliflozin group and 1.07 (95% CI 0.97–1.18) in the glimepiride group. The ratio of change with canagliflozin/glimepiride was 0.93 (95% CI 0.82–1.05). Responder analyses were used to investigate the response of an improvement in NT-proBNP levels. Although the subgroup analyses for septal annular velocity (SEP-e′) showed no marked heterogeneity in treatment effect, the subgroup with an SEP-e′ < 4.7 cm/s indicated there was an association with lower NT-proBNP levels in the canagliflozin group compared with that in the glimepiride group (ratio of change with canagliflozin/glimepiride (0.83, 95% CI 0.66–1.04).

Conclusions

In the subgroup with a lower LV diastolic function, canagliflozin showed a trend of reduced NT-pro BNP levels compared to that observed with glimepiride. This study suggests that the beneficial effects of canagliflozin treatment may be different in subgroups classified by the severity of LV diastolic dysfunction.

Sodium-Glucose Cotransporter 2 (SGLT-2) Inhibitors: Delving Into the Potential Benefits of Cardiorenal Protection Beyond the Treatment of Type-2 Diabetes Mellitus

Diabetes mellitus is a leading cause of morbidity and mortality and a significant risk factor for the early onset of chronic kidney disease and heart disease. Hyperglycemia and insulin resistance are key factors that play a role in the pathogenesis of type 2 diabetes. Renal glucose reabsorption is a critical component of glycemic regulation. Sodium-glucose cotransporter 2 (SGLT2) inhibitors, commonly known as gliflozins, lower blood sugar levels by inhibiting glucose absorption in the proximal tubule of the kidney. SGLT2 inhibitors are currently used primarily as antidiabetic medications; however, their advantages go well beyond just glycemic control. This article has reviewed the mechanisms behind cardiac and renal involvement in type 2 diabetes and their inseparable interconnections. This article has also discussed the pharmacokinetic and pharmacodynamic profile of different SGLT2 inhibitors available in the market. Finally, this review has provided a perspective on the outcome trials, which provide evidence supporting a potential benefit of SGLT2 inhibitors in reducing cardiovascular and renal risks and possible mechanisms that mediate the renal and cardiovascular protection conferred.

Effects of SGLT2 Inhibitors beyond Glycemic Control-Focus on Myocardial SGLT1

Selective sodium-glucose cotransporter 2 (SGLT2) inhibitors reduced the risk of hospitalization for heart failure in patients with or without type 2 diabetes (T2DM) in large-scale clinical trials. The exact mechanism of action is currently unclear. The dual SGLT1/2 inhibitor sotagliflozin not only reduced hospitalization for HF in patients with T2DM, but also lowered the risk of myocardial infarction and stroke, suggesting a possible additional benefit related to SGLT1 inhibition. In fact, several preclinical studies suggest that SGLT1 plays an important role in cardiac pathophysiological processes. In this review, our aim is to establish the clinical significance of myocardial SGLT1 inhibition through reviewing basic research studies in the context of SGLT2 inhibitor trials.

2021 Consensus Pathway of the Taiwan Society of Cardiology on Novel Therapy for Type 2 Diabetes

Type 2 diabetes is a major threat to human health in the 21st century. More than half a billion people may suffer from this pandemic disease in 2030, leading to a huge burden of cardiovascular complications. Recently, 2 novel antidiabetic agents, glucagon-like peptide 1 receptor agonists and sodium-glucose cotransporter 2 inhibitors, reduced cardiovascular complications in a number of randomized control trials. To integrate new information and to achieve a streamlined process for better patient care, a working group was appointed by the Taiwan Society of Cardiology to formulate a stepwise consensus pathway for these therapies to reduce cardiovascular events in patients with type 2 diabetes. This consensus pathway is complementary to clinical guidelines, acting as a reference to improve patient care.

Empagliflozin Significantly Prevents the Doxorubicin-induced Acute Cardiotoxicity via Non-antioxidant Pathways

Empagliflozin (EMPA) is a SGLT-2 inhibitor that has positive effects on cardiovascular outcomes. In this study, we aim to evaluate the possible protective effects of EMPA against doxorubicin (DOX)-induced acute cardiotoxicity. Non-diabetic Sprague-Dawley rats were randomized into four groups. The control group received serum physiologic (1 ml), the EMPA group received EMPA, the DOX group was administered cumulatively 18 mg/kg body weight DOX. The DOX+EMPA group was administered DOX and EMPA. In the DOX group, LVDED (P < 0.05) and LVSED (P < 0.01), QTc interval (P < 0.001), the ratio of karyolysis and karyorrhexis (P < 0.001) and infiltrative cell proliferation (P < 0.001) were found to be higher than; EF, FS and normal cell morphology were lower than the control group (P < 0.001). In the DOX+EMPA group, LVEDD (P < 0.05) and LVESD (P < 0.01) values, QTc interval (P < 0.001), karyolysis and karyorrhexis ratios (P < 0.001) and infiltrative cell proliferation were lower (P < 0.01); normal cell morphology and EF were higher compared to the DOX group (P < 0.001). Our results showed that empagliflozin significantly ameliorated DOX-induced acute cardiotoxicity.

CARDIOVASCULAR EFFECTS OF NON-INSULIN GLUCOSE-LOWERING AGENTS: A COMPREHENSIVE REVIEW OF TRIAL EVIDENCE AND POTENTIAL CARDIOPROTECTIVE MECHANISMS

Type 2 diabetes mellitus (T2DM) is highly prevalent and associated with a 2-fold increased mortality, mostly explained by cardiovascular diseases. Trial evidence on older glucose-lowering agents such as metformin and sulfonylureas is limited in terms of cardiovascular efficacy. Since 2008, after rosiglitazone was observed to increase the risk of myocardial infarction and heart failure (HF), cardiovascular outcome trials (CVOT) have been required by regulators for licensing new glucose-lowering agents. In the following CVOTs, dipeptidyl peptidase 4 inhibitors (DPP4i) have been shown to be safe but not to improve morbidity/mortality, except for saxagliptin which increased the risk of HF. Several glucagon-like peptide-1 receptor agonists (GLP1-Ra) and sodium-glucose cotransporter-2 inhibitors (SGLT2i) have been demonstrated to reduce the risk of cardiovascular morbidity and mortality. SGLT2i have shown a class effect for the reduction in risk of HF events in patients with T2DM, leading to trials testing their efficacy/safety in HF regardless of T2DM. In the DAPA-HF and the EMPEROR-Reduced trials dapagliflozin and empagliflozin, respectively, improved cardiovascular mortality/morbidity in patients with HF and reduced ejection fraction (HFrEF), with and without T2DM. Therefore, these drugs are now key part of HFrEF pharmacotherapy. In the SOLOIST-WHF, sotagliflozin reduced cardiovascular mortality/morbidity in patients with T2DM and a recent acute episode of HF regardless of EF. The DELIVER and the EMPEROR-Preserved are testing dapagliflozin and empagliflozin, respectively, in patients with HF with mildly reduced and preserved EF. A strong renal protective role of SGLT2i has also emerged in trials enrolling patients with and without T2DM.

Redox signaling in heart failure and therapeutic implications

Heart failure is a growing health burden worldwide characterized by alterations in excitation-contraction coupling, cardiac energetic deficit and oxidative stress. While current treatments are mostly limited to antagonization of neuroendocrine activation, more recent data suggest that also targeting metabolism may provide substantial prognostic benefit. However, although in a broad spectrum of preclinical models, oxidative stress plays a causal role for the development and progression of heart failure, no treatment that targets reactive oxygen species (ROS) directly has entered the clinical arena yet. In the heart, ROS derive from various sources, such as NADPH oxidases, xanthine oxidase, uncoupled nitric oxide synthase and mitochondria. While mitochondria are the primary source of ROS in the heart, communication between different ROS sources may be relevant for physiological signalling events as well as pathologically elevated ROS that deteriorate excitation-contraction coupling, induce hypertrophy and/or trigger cell death. Here, we review the sources of ROS in the heart, the modes of pathological activation of ROS formation as well as therapeutic approaches that may target ROS specifically in mitochondria.

Cardiac, renal, and metabolic effects of sodium-glucose co-transporter 2 inhibitors: a position paper from the European Society of Cardiology ad-hoc task force on sodium-glucose co-transporter 2 inhibitors

In 2015, the first large-scale placebo-controlled trial designed to assess cardiovascular safety of glucose-lowering with sodium-glucose co-transporter 2 (SGLT2) inhibition in type 2 diabetes mellitus raised hypotheses that the class could favourably modify not only risk of atherosclerotic cardiovascular disease, but also hospitalization for heart failure, and the development or worsening of nephropathy. By the start of 2021, results from 10 large SGLT2 inhibitor placebo-controlled clinical outcome trials randomizing ∼71 000 individuals have confirmed that SGLT2 inhibitors can provide clinical benefits for each of these types of outcome in a range of different populations. The cardiovascular and renal benefits of SGLT2 inhibitors appear to be larger than their comparatively modest effect on glycaemic control or glycosuria alone would predict, with three trials recently reporting that clinical benefits extend to individuals without diabetes mellitus who are at risk due to established heart failure, or albuminuric chronic kidney disease. This European Society of Cardiology position paper summarizes reported results from these 10 large clinical outcome trials considering separately each of the different types of cardiorenal benefit, summarizes key molecular and pathophysiological mechanisms, and provides a synopsis of metabolic effects and safety. We also describe ongoing placebo-controlled trials among individuals with heart failure with preserved ejection fraction and among individuals with chronic kidney disease.

Differential Pathophysiological Mechanisms in Heart Failure With a Reduced or Preserved Ejection Fraction in Diabetes

Diabetes promotes the development of both heart failure with a reduced ejection fraction and heart failure with a preserved ejection fraction through diverse mechanisms, which are likely mediated through hyperinsulinemia rather than hyperglycemia. Diabetes promotes nutrient surplus signaling (through Akt and mammalian target of rapamycin complex 1) and inhibits nutrient deprivation signaling (through sirtuin-1 and its downstream effectors); this suppresses autophagy and promotes endoplasmic reticulum and oxidative stress and mitochondrial dysfunction, thereby undermining the health of diabetic cardiomyocytes. The hyperinsulinemia of diabetes may also activate sodium-hydrogen exchangers in cardiomyocytes (leading to injury and loss) and in the proximal renal tubules (leading to sodium retention). Diabetes may cause epicardial adipose tissue expansion, and the resulting secretion of proinflammatory adipocytokines onto the adjoining myocardium can lead to coronary microcirculatory dysfunction and myocardial inflammation and fibrosis. Interestingly, sodium-glucose cotransporter 2 (SGLT2) inhibitors-the only class of antidiabetic medication that reduces serious heart failure events-may act to mitigate each of these mechanisms. SGLT2 inhibitors up-regulate sirtuin-1 and its downstream effectors and autophagic flux, thus explaining the actions of these drugs to reduce oxidative stress, normalize mitochondrial structure and function, and mute proinflammatory pathways in the stressed myocardium. Inhibition of SGLT2 may also lead to a reduction in the activity of sodium-hydrogen exchangers in the kidney (leading to diuresis) and in the heart (attenuating the development of cardiac hypertrophy and systolic dysfunction). Finally, SGLT2 inhibitors reduce the mass and mute the adverse biology of epicardial adipose tissue (and reduce the secretion of leptin), thus explaining the capacity of these drugs to mitigate myocardial inflammation, microcirculatory dysfunction, and fibrosis, and improve ventricular filling dynamics. The pathophysiological mechanisms by which SGLT2 inhibitors may benefit heart failure likely differ depending on ejection fraction, but each represents interference with distinct pathways by which hyperinsulinemia may adversely affect cardiac structure and function.

Cardioprotection by SGLT2 Inhibitors-Does It All Come Down to Na+?

Sodium-glucose co-transporter 2 inhibitors (SGLT2i) are emerging as a new treatment strategy for heart failure with reduced ejection fraction (HFrEF) and—depending on the wistfully awaited results of two clinical trials (DELIVER and EMPEROR-Preserved)—may be the first drug class to improve cardiovascular outcomes in patients suffering from heart failure with preserved ejection fraction (HFpEF). Proposed mechanisms of action of this class of drugs are diverse and include metabolic and hemodynamic effects as well as effects on inflammation, neurohumoral activation, and intracellular ion homeostasis. In this review we focus on the growing body of evidence for SGLT2i-mediated effects on cardiac intracellular Na⁺ as an upstream mechanism. Therefore, we will first give a short overview of physiological cardiomyocyte Na⁺ handling and its deterioration in heart failure. On this basis we discuss the salutary effects of SGLT2i on Na⁺ homeostasis by influencing NHE1 activity, late I_Na as well as CaMKII activity. Finally, we highlight the potential relevance of these effects for systolic and diastolic dysfunction as well as arrhythmogenesis.

The Na/K-ATPase Signaling and SGLT2 Inhibitor-Mediated Cardiorenal Protection: A Crossed Road?

In different large-scale clinic outcome trials, sodium (Na⁺)/glucose co-transporter 2 (SGLT2) inhibitors showed profound cardiac- and renal-protective effects, making them revolutionary treatments for heart failure and kidney disease. Different theories are proposed according to the emerging protective effects other than the original purpose of glucose-lowering in diabetic patients. As the ATP-dependent primary ion transporter providing the Na⁺ gradient to drive other Na⁺-dependent transporters, the possible role of the sodium–potassium adenosine triphosphatase (Na/K-ATPase) as the primary ion transporter and its signaling function is not explored.

The SGLT-2 inhibitor empagliflozin improves myocardial strain, reduces cardiac fibrosis and pro-inflammatory cytokines in non-diabetic mice treated with doxorubicin

BACKGROUND

Empagliflozin (EMPA), a selective inhibitor of the sodium glucose co-transporter 2, reduced the risk of hospitalization for heart failure and cardiovascular death in type 2 diabetic patients in the EMPA-REG OUTCOME trial. Recent trials evidenced several cardio-renal benefits of EMPA in non-diabetic patients through the involvement of biochemical pathways that are still to be deeply analysed. We aimed to evaluate the effects of EMPA on myocardial strain of non-diabetic mice treated with doxorubicin (DOXO) through the analysis of NLRP3 inflammasome and MyD88-related pathways resulting in anti-apoptotic and anti-fibrotic effects.

METHODS

Preliminary cellular studies were performed on mouse cardiomyocytes (HL-1 cell line) exposed to doxorubicin alone or combined to EMPA. The following analysis were performed: determination of cell viability (through a modified MTT assay), study of intracellular ROS production, lipid peroxidation (quantifying intracellular malondialdehyde and 4-hydroxynonenal), intracellular Ca2+ homeostasis. Moreover, pro-inflammatory studies were also performed: expression of NLRP3 inflammasome, MyD88 myddosome and p65/NF-κB associated to secretion of cytokines involved in cardiotoxicity (Interleukins 1β, 8, 6). C57Bl/6 mice were untreated (Sham, n = 6) or treated for 10 days with doxorubicin (DOXO, n = 6), EMPA (EMPA, n = 6) or doxorubicin combined to EMPA (DOXO-EMPA, n = 6). DOXO was injected intraperitoneally. Ferroptosis and xanthine oxidase were studied before and after treatments. Cardiac function studies, including EF, FS and radial/longitudinal strain were analysed through transthoracic echocardiography (Vevo 2100). Cardiac fibrosis and apoptosis were histologically studied through Picrosirius red and TUNEL assay, respectively and quantified through pro-collagen-1α1, MMP-9 and Caspase-3 expression. Tissue NLRP3, MyD88 and cytokines were also quantified before and after treatments through ELISA methods.

RESULTS

Cardiomyocytes exposed to doxorubicin increased the intracellular Ca2+ content and expression of several pro-inflammatory markers associated to cell death; co-incubation with EMPA reduced significantly the magnitude of the effects. In preclinical study, EMPA increased EF and FS compared to DOXO groups (p < 0.05), prevented the reduction of radial and longitudinal strain after 10 days of treatment with doxorubicin (RS) 30.3% in EMPA-DOXO vs 15.7% in DOXO mice; LS - 17% in EMPA-DOXO vs - 11.7% in DOXO mice (p < 0.001 for both). Significant reductions in ferroptosis, xanthine oxidase expression, cardiac fibrosis and apoptosis in EMPA associated to DOXO were also seen. A reduced expression of pro-inflammatory cytokines, NLRP3, MyD88 and NF-kB in heart, liver and kidneys was also seen in DOXO-EMPA group compared to DOXO (p < 0.001).

CONCLUSION

EMPA reduced ferroptosis, fibrosis, apoptosis and inflammation in doxorubicin-treated mice through the involvement of NLRP3 and MyD88-related pathways, resulting in significant improvements in cardiac functions. These findings provides the proof of concept for translational studies designed to reduce adverse cardiovascular outcomes in non-diabetic cancer patients treated with doxorubicin.

The Potential Roles of Osmotic and Nonosmotic Sodium Handling in Mediating the Effects of Sodium-Glucose Cotransporter 2 Inhibitors on Heart Failure

Concomitant type 2 diabetes and chronic kidney disease increases the risk of heart failure. Recent studies demonstrate beneficial effects of sodium-glucose cotransporter 2 (SGLT2) inhibitors on chronic kidney disease progression and heart failure hospitalization in patients with and without diabetes. In addition to inhibiting glucose reabsorption, SGLT2 inhibitors decrease proximal tubular sodium reabsorption, possibly leading to transient natriuresis. We review the hypothesis that SGLT2 inhibitor’s natriuretic and osmotic diuretic effects mediate their cardioprotective effects. The degree to which these benefits are related to changes in sodium, independent of the kidney, is currently unknown. Aside from effects on osmotically active sodium, we explore the intriguing possibility that SGLT2 inhibitors could also modulate nonosmotic sodium storage. This alternative hypothesis is based on emerging literature that challenges the traditional 2-compartment model of sodium balance to provide support for a 3-compartment model that includes the binding of sodium to glycosaminoglycans, such as those in muscles and skin. This recent research on nonosmotic sodium storage, as well as direct cardiac effects of SGLT2 inhibitors, provides possibilities for other ways in which SGLT2 inhibitors might mitigate heart failure risk. Overall, we review the effects of SGLT2 inhibitors on sodium balance and sensitivity, cardiac tissue, interstitial fluid and plasma volume, and nonosmotic sodium storage.

SGLT2 inhibitors have cardiovascular benefits that include HF outcomes in patients with and without diabetes. Because the underlying mechanisms are only partly explained by improvements in BP, body weight, or glucose control, other mechanisms have been proposed. We focus here on a central role for effects on sodium as underlying the positive benefits of SGLT2 inhibitors in HF. We explore the new (although still unconfirmed) idea that SGLT2 inhibitors exert some of their positive effects by affecting nonosmotic sodium (ie, sodium bound to muscles and skin and not dissolved in the blood).

SGLT2 inhibitors have emerged as a class of drugs, previously prescribed for patients with T2D, that have in more recent years been shown to have substantial heart and kidney clinical benefits in patients with and without T2D.

The degree to which these benefits are related to kidney-independent changes in sodium homeostasis is currently unknown.

A better understanding of the nonosmotic mechanisms underpinning the benefits of SGLT2 inhibition on HF (with reduced or preserved left ventricular ejection fraction) may allow researchers to assess the effects of SGLT2 inhibitors in combination with other treatments that affect sodium balance.

Efficacy of Continuing SGLT2 Inhibitors on Outcomes in Patients with Acute Decompensated Heart Failure

Sodium-glucose cotransporter 2 inhibitor (SGLT2i) reduces mortality and morbidity in patients with chronic heart failure (HF). However, the clinical implication of SGLT2i therapy in patients with acute decompensated HF remains uncertain. We prospectively studied 86 type 2 diabetic mellitus (T2DM) patients (71.8 ± 12.1 years, 55 men) who were hospitalized for acute decompensated HF and received SGLT2i during the index hospitalization. Among the patients, 56 continued SGLT2i at discharge and 30 did not. The continued group experienced fewer HF re-hospitalizations than the discontinued group (24% versus 39%, P = 0.008) with a hazard ratio of 0.29 (95% confidence interval 0.10-0.85) adjusted for other significant potential confounders. In conclusion, long-term SGLT2i therapy might prevent unplanned HF re-hospitalization in patients with T2DM and acute decompensated HF.

Cardio-Renal Benefits of SGLT2 Inhibitors in Heart Failure with Reduced Ejection Fraction: Mechanisms and Clinical Evidence

The heart and the kidneys are closely interconnected, and disease in one organ system can lead to disease in the other. This interdependence is illustrated in heart failure with reduced ejection fraction (HFrEF), where worsening heart failure can lead to renal dysfunction and vice versa. Further complicating this situation is the fact that drugs that serve as guideline directed medical therapy (GDMT) for HFrEF can affect renal function. Sodium glucose co-transporter 2 (SGLT2) inhibitors are a new class of medication with an evolving role in heart failure (HF) and chronic kidney disease (CKD). Initially found to have benefits in diabetics, new research established potential cardiovascular and renal benefits in patients with HF independent of their diabetic status and in populations with CKD. This has been established by landmark trials such as EMPEROR-Reduced, EMPA-TROPISM, CREDENCE, DAPA-CKD, DAPA-HF, and DEFINE-HF. Multiple mechanisms responsible for these benefits have been suggested by clinical and non-clinical studies, and involve cardiac and renal energetic efficiency, cardiac remodeling, preservation of renal function, immunomodulation, changes in hematocrit, and control of risk factors. As such, SGLT2 inhibitors have tremendous potential to improve outcomes in populations with HF and CKD. The purpose of this review is to discuss the current evidence and underlying mechanisms for the cardio-renal benefits of SGLT2 inhibitors in patients with HFrEF.

Dapagliflozin attenuates arrhythmic vulnerabilities by regulating connexin43 expression via the AMPK pathway in post-infarcted rat hearts

We have demonstrated that dapagliflozin, a sodium-glucose cotransporter (SGLT) 2 inhibitor, attenuates reactive oxygen species (ROS) production. Connexin43 playing a role in ventricular arrhythmia is sensitive to redox status. No data are available on the effects of dapagliflozin on arrhythmogenesis. This study was to determine whether dapagliflozin attenuated arrhythmias through modulating AMP-activated protein kinase (AMPK)/free radicals-induced connexin43 after myocardial infarction. After coronary ligation, normoglycemic male Wistar rats were randomized to either vehicle or dapagliflozin (0.1 mg/kg per day) for 4 weeks. Myocardial ROS levels were significantly increased (p < 0.05) and connexin43 levels were substantially decreased after myocardial infarction (p < 0.05). Dapagliflozin administration was associated with increased SGLT1, attenuated ROS and increased connexin43 levels in myocardium (all p < 0.05). During programmed electrical stimulation, arrhythmic severity was significantly improved in the dapagliflozin-treated infarcted rats than those in the vehicle-treated infarcted rats (p < 0.05). Dapagliflozin significantly increased AMPK phosphorylation compared to vehicle after infarction (p < 0.05). Inhibition of AMPK signaling by SBI-0206965 prevented increased SGLT1 and blocked the effects of dapagliflozin on attenuated ROS levels and increased connexin43 phosphorylation (all p < 0.05). SGLT1 inhibited by KGA-2727 showed attenuated ROS levels and increased connexin43 phosphorylation (both p < 0.05) although AMPK phosphorylation was not changed, implying SGLT1 activation was mediated by AMPK in dapagliflozin-treated hearts. Dapagliflozin-treated hearts had significantly increased connexin43 phosphorylation (p < 0.05), which was significantly decreased after adding 3-morpholinosydnonimine (p < 0.05). These data indicate that clinically-relevant dapagliflozin concentrations decreased free radicals content and increased connexin43 levels through AMPK-dependent and SGLT1-independent mechanisms, which attenuated ventricular arrhythmias in the normoglycemic infarcted rats.

Electrical Features of the Diabetic Myocardium. Arrhythmic and Cardiovascular Safety Considerations in Diabetes

Diabetes is a chronic metabolic disease characterized by hyperglycemia in the absence of treatment. Among the diabetes-associated complications, cardiovascular disease is the major cause of mortality and morbidity in diabetic patients. Diabetes causes a complex myocardial dysfunction, referred as diabetic cardiomyopathy, which even in the absence of other cardiac risk factors results in abnormal diastolic and systolic function. Besides mechanical abnormalities, altered electrical function is another major feature of the diabetic myocardium. Both type 1 and type 2 diabetic patients often show cardiac electrical remodeling, mainly a prolonged ventricular repolarization visible in the electrocardiogram as a lengthening of the QT interval duration. The underlying mechanisms at the cellular level involve alterations on the expression and activity of several cardiac ion channels and their associated regulatory proteins. Consequent changes in sodium, calcium and potassium currents collectively lead to a delay in repolarization that can increase the risk of developing life-threatening ventricular arrhythmias and sudden death. QT duration correlates strongly with the risk of developing torsade de pointes, a form of ventricular tachycardia that can degenerate into ventricular fibrillation. Therefore, QT prolongation is a qualitative marker of proarrhythmic risk, and analysis of ventricular repolarization is therefore required for the approval of new drugs. To that end, the Thorough QT/QTc analysis evaluates QT interval prolongation to assess potential proarrhythmic effects. In addition, since diabetic patients have a higher risk to die from cardiovascular causes than individuals without diabetes, cardiovascular safety of the new antidiabetic drugs must be carefully evaluated in type 2 diabetic patients. These cardiovascular outcome trials reveal that some glucose-lowering drugs actually reduce cardiovascular risk. The mechanism of cardioprotection might involve a reduction of the risk of developing arrhythmia.

Effects of Sodium-Glucose Linked Transporter 2 Inhibition With Ertugliflozin on Mitochondrial Function, Energetics, and Metabolic Gene Expression in the Presence and Absence of Diabetes Mellitus in Mice

Background Inhibitors of the sodium-glucose linked transporter 2 improve cardiovascular outcomes in patients with or without type 2 diabetes mellitus, but the effects on cardiac energetics and mitochondrial function are unknown. We assessed the effects of sodium-glucose linked transporter 2 inhibition on mitochondrial function, high-energy phosphates, and genes encoding mitochondrial proteins in hearts of mice with and without diet-induced diabetic cardiomyopathy. Methods and Results Mice fed a control diet or a high-fat, high-sucrose diet received ertugliflozin mixed with the diet (0.5 mg/g of diet) for 4 months. Isolated mitochondria were assessed for functional capacity. High-energy phosphates were assessed by 31P nuclear magnetic resonance spectroscopy concurrently with contractile performance in isolated beating hearts. The high-fat, high-sucrose diet caused myocardial hypertrophy, diastolic dysfunction, mitochondrial dysfunction, and impaired energetic response, all of which were prevented by ertugliflozin. With both diets, ertugliflozin caused supernormalization of contractile reserve, as measured by rate×pressure product at high work demand. Likewise, the myocardial gene sets most enriched by ertugliflozin were for oxidative phosphorylation and fatty acid metabolism, both of which were enriched independent of diet. Conclusions Ertugliflozin not only prevented high-fat, high-sucrose-induced pathological cardiac remodeling, but improved contractile reserve and induced the expression of oxidative phosphorylation and fatty acid metabolism gene sets independent of diabetic status. These effects of sodium-glucose linked transporter 2 inhibition on cardiac energetics and metabolism may contribute to improved structure and function in cardiac diseases associated with mitochondrial dysfunction, such as heart failure.

Minireview: are SGLT2 inhibitors heart savers in diabetes?

Sodium-glucose cotransporter 2 (SGLT2) inhibitors, a class of drugs that promote urinary glucose excretion in the treatment of diabetes, have provoked large interest of scientific and professional community due to their positive and, somehow, unexpected results in the three major cardiovascular outcome trials (EMPA-REG OUTCOME trial with empagliflozin, CANVAS Program with canagliflozin, and DECLARE-TIMI 58 with dapagliflozin). In fact, along with the reduction of major adverse cardiovascular events, SGLT2 inhibitors reduced significantly hospitalization for heart failure regardless of existing atherosclerotic cardiovascular disease or a history of heart failure. The latter have reminded us of the frequent but neglected entity of diabetic cardiomyopathy which is currently poorly understood despite its great clinical importance. Physiological mechanisms responsible for the benefits of SGLT2 inhibitors are complex and multifactorial and still not well defined. Interestingly, the time frame of their effect excludes a glucose- and antiatherosclerotic-mediated effect. It would be of great importance to better understand SGLT2 inhibitor mechanisms of action since they could have a potential to be used in early stages of diabetes as cardioprotective agents. There are widely available biomarkers as well as echocardiography that are used in everyday clinical practice and could elucidate physiological mechanisms in the heart protection with SGLT2 inhibitors treatment but studies are still lacking. The purpose of this minireview is to summarize the latest concepts about SGLT2 inhibitors and its benefits regarding diabetic cardiomyopathy especially on its early stage development and to discuss controversies and potential future developments in the field.

Efficacy and safety of dapagliflozin in the treatment of chronic heart failure: A protocol for systematic review and meta-analysis

BACKGROUND

As the last link in the chain of cardiovascular events, chronic heart failure (CHF) has high morbidity, high mortality, and poor prognosis. It is one of the main causes of death and disability worldwide. As a new drug for the treatment of chronic cardiovascular disease, dapagliflozin, the efficacy, and safety issues are still the focus of attention. Therefore, we conducted a meta-analysis to evaluate the efficacy and safety of dapagliflozin in the treatment of CHF.

METHODS

According to the search strategy, regardless of publication date or language, randomized controlled trials (RCTs) of dapagliflozin for CHF will be retrieved from 8 databases. First of all, the literature was screened according to the eligibility criteria, and use the Cochrane Collaboration's tool to assess the quality of the included literature. Then, using Rev Man 5.3 and STATA 14.2 software for traditional meta-analysis. Finally, the evaluation of the quality of the evidence and the strength of the recommendations will adopt the Grading of Recommendations, Assessment, Development and Evaluation method.

RESULTS

This study will evaluate the efficacy and safety of dapagliflozin for CHF, thereby providing more evidence support for clinical decision-making in CHF.

CONCLUSION

Our research will provide more references for the clinical medication of patients with CHF.

PROTOCOL REGISTRATION NUMBER

INPLASY202150046.

The impact of empagliflozin on cardiac physiology and fibrosis early after myocardial infarction in non-diabetic rats

BACKGROUND

Myocardial fibrosis is a multistep process, which results in collagen deposition in the injured muscle. Empagliflozin, a sodium-glucose cotransporter 2 inhibitor (SGLT2i), decreases cardiovascular events risk. Little is known on the effects of empagliflozin in non-diabetic patients early post myocardial infarction.

METHODS

Fourteen non-diabetic rats underwent myocardial infarction induction, and treated or not (control)immediately after myocardial infarction by daily empagliflozin (30 mg/kg/day). We evaluated cardiac function at baseline, 2 and 4 weeks after myocardial infarction by echocardiography, and prior to sacrifice by Millar pressure-volume system. We performed histological and biochemical evaluation of fibrosis and humoral factors promoting fibrosis.

RESULTS

Baseline ejection fractions were 69.9 ± 5.3% and 76.4 ± 5.4%, and dropped to final values of 40.1 ± 5.8% and 39.4 ± 5.4% in the control and empagliflozin groups, respectively (P < 0.001 vs. baseline, P > 0.05 between groups). Collagen deposition, measured as collagen volume fraction, was higher in both the scar and the remote cardiac areas of the control group 79.1 ± 6.2% and 4.6 ± 2.5% for control, and 53.8 ± 5.4% and 2.5 ± 1.3% for empagliflozin group, respectively (P < 0.05 for each). Remote cardiac muscle collagen, measured by hydroxyproline, was 4.1 ± 0.4 μg/μl and 3.6 ± 0.2 μg/μl (P = 0.07). TGF-β1 and Smad3 expression decreased by empagliflozin-18.73 ± 16.32%, 9.16 ± 5.69% and 16.32 ± 5.4%, 7.00 ± 5.28% in the control and empagliflozin groups, respectively (P < 0.05).

CONCLUSION/INTERPRETATION

Empagliflozin administered early after myocardial infarction reduce myocardial fibrosis and inhibit the TGF-β1/Smad3 fibrotic pathway, probably prior to exerting any hemodynamic or physiological effect.

The Effects of Dapagliflozin in Patients With Heart Failure Complicated With Type 2 Diabetes: A Meta-Analysis of Placebo-Controlled Randomized Trials

Background

Cardiovascular disease threatens the health and quality of life of individuals, particularly those with type II diabetes. Recently, some studies have reported the effect of sodium-glucose cotransporter 2 (SGLT2) inhibitors in reducing the rates of hospitalization or urgent visits, resulting in IV therapy for heart failure in patients with type 2 diabetes mellitus (T2DM).

Methods

We did a comprehensive search in electronic databases from inception through July 2020 for randomized-controlled trials, using the keywords “sodium-glucose cotransporter-2 inhibitor”, “dapagliflozin”, “heart failure”, “cardiovascular outcomes”, “major adverse cardiovascular events”, “all-cause mortality”, and “cardiovascular death”. Random-effects summary odds ratios (OR) were constructed using M-L heterogeneity model.

Results

Five trials with 5,252 patients were ultimately included. The incidence of hospitalization for heart failure (HHF) (n=4, OR=0.74; 95% CI, 0.61 to 0.88; I2 = 0%) and all-cause mortality (ACM, n=4, OR=0.76; 95% CI, 0.66 to 0.94; I2 = 0%); was reduced by dapagliflozin, respectively, in all heart failure patients, without obvious heterogeneity. The incidence of cardiovascular death in dapagliflozin was lower than that in placebo without statistically significant (CVD, n=5, OR=0.84; 95% CI, 0.69 to 1.03; I2 = 0%). In HFrEF subgroup, dapagliflozin was associated with a reduced incidence of hospitalization for heart failure (n=4, OR=0.74; 95% CI, 0.60 to 0.91; I2 = 0%), cardiovascular death (n=4, OR=0.72; 95% CI, 0.58 to 0.91; I2 = 8%), and all-cause mortality (n=3, OR=0.70; 95% CI, 0.50 to 0.99; I2 = 43%) without significant heterogeneity. In contrast, in the HFpEF subgroup, there was no difference in the incidence of cardiovascular death (n=2, OR=1.45; 95% CI, 0.95 to 2.22; I2 = 0%) and all-cause mortality (n=2, OR=1.04; 95% CI, 0.76 to 1.43; I2 = 0%) between dapagliflozin and placebo.

Conclusion

In our study, dapagliflozin performed a statistical reduction in the rate of heart failure hospitalization, cardiovascular death, and all-cause mortality in patients with HFrEF and diabetes. However, in the HFpEF subgroup, dapagliflozin did not show a significant cardiovascular protective effect.

Cellular mechanisms and recommended drug-based therapeutic options in diabetic cardiomyopathy

Diabetes mellitus (DM) is associated with a specific cardiac phenotype characterized by structural and functional alterations. This so-called diabetic cardiomyopathy (DM CM) is clinically relevant as patients with DM show high incidence of heart failure. Mechanistically, several parameters interact on the cardiomyocyte level leading to increased inflammation, apoptosis, reactive oxygen species and altered calcium signaling. This in turn provokes functional myocardial changes that might inter alia play into the worsened clinical outcome in DM patients. Therefore, efficient therapeutic options are urgently needed. This review focuses on mechanistic effects of currently recommended antidiabetic treatment and heart failure therapy for DM CM.

Comparison of cardiovascular outcomes and cardiometabolic risk factors between patients with type 2 diabetes treated with sodium-glucose cotransporter-2 inhibitors and dipeptidyl peptidase-4 inhibitors: a meta-analysis

AIMS 

Prevention of cardiovascular outcomes is a goal of the management of patients with type 2 diabetes mellitus patients as important as lowering blood glucose levels. Among the various glucose-lowering agents, the effects of sodium-glucose cotransporter-2 inhibitors (SGLT-2Is) and dipeptidyl peptidase-4 inhibitors (DPP-4Is) on cardiovascular outcomes have become the focus of recent researches.

METHODS AND RESULTS 

A systematic search was performed through several online database. All studies that compared the effects of SGLT-2Is and DPP-4Is on cardiovascular outcomes and cardiometabolic risk factors were reviewed. A total of 30 studies were included. Compared with DPP-4Is, SGLT-2Is treatment reduced the risk of stroke [risk ratio (RR) = 0.80; 95% confidence interval (CI), 0.76-0.84], myocardial infarction (RR = 0.85; 95% CI, 0.81-0.89), heart failure (RR = 0.58; 95% CI, 0.54-0.62), cardiovascular mortality (RR = 0.55; 95% CI, 0.51-0.60), and all-cause mortality (RR = 0.60; 95% CI, 0.57-0.63). In addition, SGLT-2Is presented favourable effects on hemoglobinA1c, fasting plasma glucose, systolic blood pressure, and diastolic blood pressure. The differences in blood lipids were also compared.

CONCLUSION

Sodium-glucose cotransporter-2 inhibitors are superior to DPP-4Is in terms of cardiovascular outcomes. Sodium-glucose cotransporter-2 inhibitors bring more benefits with respect to the cardiometabolic risk factors.

Effects of dapagliflozin and gliclazide on the cardiorenal axis in people with type 2 diabetes

OBJECTIVES

There is a bidirectional relationship between cardiovascular and renal disease. The drug-class of SGLT2 inhibitors improves outcomes at both ends of this so called cardiorenal axis. We assessed the effects of SGLT2 inhibition and sulfonylurea treatment on systemic hemodynamic function and investigated whether SGLT2 inhibitor-induced changes in systemic hemodynamics correlate with changes in renal hemodynamics.

METHODS

Forty-four people with type 2 diabetes were randomized to 12 weeks of dapagliflozin 10 mg/day or gliclazide 30 mg/day treatment. Systemic hemodynamic function, autonomic nervous system activity, and vascular stiffness were measured noninvasively, whereas renal hemodynamics, glomerular filtration rate (GFR) and effective renal plasma flow, were assessed with gold-standard urinary clearances of inulin or iohexol and para-aminohippuric acid, respectively. Correlation analyses were performed to assess relationships between dapagliflozin-induced changes in cardiovascular and renal variables.

RESULTS

Dapagliflozin reduced stroke volume by 4%, cardiac output by 5%, vascular stiffness by 11%, and mean arterial pressure by 5% from baseline, without increasing heart rate or sympathetic activity, while simultaneously lowering glomerular filtration rate by 8%. Despite similar improvements in glycemic control by dapagliflozin and gliclazide (-0.5 ± 0.5 versus-0.7 ± 0.5%; P = 0.12), gliclazide did not affect any of these measurements. There was no clear association between the dapagliflozin-induced changes in cardiovascular and renal physiology.

CONCLUSION

Dapagliflozin seemingly influences systemic and renal hemodynamics independently and beyond glucose lowering in people with type 2 diabetes.This clinical trial was registered at https://clinicalTrials.gov (ID: NCT02682563).

Sodium-glucose co-transporter 2 inhibitor therapy: mechanisms of action in heart failure

Patients with type 2 diabetes mellitus are at a higher risk of developing heart failure compared with the healthy population. In recent landmark clinical trials, sodium-glucose co-transporter 2 (SGLT2) inhibitor therapies improve blood glucose control and also reduce cardiovascular events and heart failure hospitalisations in patients with type 2 diabetes. Intriguingly, such clinical benefits have also been seen in patients with heart failure in the absence of type 2 diabetes although the underlying mechanisms are not clearly understood. Potential pathways include improved glycaemic control, diuresis, weight reduction and reduction in blood pressure, but none fully explain the observed improvements in clinical outcomes. More recently, novel mechanisms have been proposed to explain these benefits that include improved cardiomyocyte calcium handling, enhanced myocardial energetics, induced autophagy and reduced epicardial fat. We provide an up-to-date review of cardiac-specific SGLT2 inhibitor-mediated mechanisms and highlight studies currently underway investigating some of the proposed mechanisms of action in cardiovascular health and disease.

Empagliflozin Protects Cardiac Mitochondrial Fatty Acid Metabolism in a Mouse Model of Diet-Induced Lipid Overload

PURPOSE

Sodium-glucose cotransporter 2 (SGLT2) inhibitors prevent heart failure and decrease cardiovascular mortality in patients with type 2 diabetes. Heart failure is associated with detrimental changes in energy metabolism, and the preservation of cardiac mitochondrial function is crucial for the failing heart. However, to date, there are no data to support the hypothesis that treatment with a SGLT2 inhibitor might alter mitochondrial bioenergetics in diabetic failing hearts. Thus, the aim of this study was to investigate the protective effects of empagliflozin on mitochondrial fatty acid metabolism.

METHODS

Mitochondrial dysfunction was induced by 18 weeks of high-fat diet (HFD)-induced lipid overload. Empagliflozin was administered at a dose of 10 mg/kg in a chow for 18 weeks. Palmitate metabolism in vivo, cardiac mitochondrial functionality and biochemical parameters were measured.

RESULTS

In HFD-fed mice, palmitate uptake was 1.7, 2.3, and 1.9 times lower in the heart, liver, and kidneys, respectively, compared with that of the normal chow control group. Treatment with empagliflozin increased palmitate uptake and decreased the accumulation of metabolites of incomplete fatty acid oxidation in cardiac tissues, but not other tissues, compared with those of the HFD control group. Moreover, empagliflozin treatment resulted in fully restored fatty acid oxidation pathway-dependent respiration in permeabilized cardiac fibers. Treatment with empagliflozin did not affect the biochemical parameters related to hyperglycemia or hyperlipidemia.

CONCLUSION

Empagliflozin treatment preserves mitochondrial fatty acid oxidation in the heart under conditions of chronic lipid overload.

Sodium-Glucose Co-transporter-2 Inhibitors and Nephroprotection in Diabetic Patients: More Than a Challenge

Diabetic nephropathy is the most common cause of end-stage renal disease worldwide. Control of blood glucose and blood pressure (BP) reduces the risk of developing this complication, but once diabetic nephropathy is established, it is then only possible to slow its progression. Sodium-glucose cotransporter-2 inhibitors (SGLT2is) are a novel class of oral hypoglycemic agents that increase urinary glucose excretion by suppressing glucose reabsorption at the renal proximal tubule. SGLT2is lower glycated hemoglobin (HbA1c) without increasing the risk of hypoglycemia, induce weight loss and improve various metabolic parameters including BP, lipid profile, albuminuria and uric acid. Several clinical trials have shown that SGLT2is (empagliflozin, dapagliflozin canagliflozin, and ertugliflozin) improve cardiovascular and renal outcomes and mortality in patients with type 2 diabetes. Effects of SGLT2is on the kidney can be explained by multiple pathways. SGLT2is may improve renal oxygenation and intra-renal inflammation thereby slowing the progression of kidney function decline. Additionally, SGLT2is are associated with a reduction in glomerular hyperfiltration, an effect which is mediated by the increase in natriuresis, the re-activation of tubule-glomerular feedback and independent of glycemic control. In this review, we will focus on renal results of major cardiovascular and renal outcome trials and we will describe direct and indirect mechanisms through which SGLT2is confer renal protection.

Sodium Glucose Co-Transporter 2 Inhibitors Ameliorate Endothelium Barrier Dysfunction Induced by Cyclic Stretch through Inhibition of Reactive Oxygen Species

SGLT-2i's exert direct anti-inflammatory and anti-oxidative effects on resting endothelial cells. However, endothelial cells are constantly exposed to mechanical forces such as cyclic stretch. Enhanced stretch increases the production of reactive oxygen species (ROS) and thereby impairs endothelial barrier function. We hypothesized that the SGLT-2i's empagliflozin (EMPA), dapagliflozin (DAPA) and canagliflozin (CANA) exert an anti-oxidative effect and alleviate cyclic stretch-induced endothelial permeability in human coronary artery endothelial cells (HCAECs). HCAECs were pre-incubated with one of the SGLT-2i's (1 µM EMPA, 1 µM DAPA and 3 µM CANA) for 2 h, followed by 10% stretch for 24 h. HCAECs exposed to 5% stretch were considered as control. Involvement of ROS was measured using N-acetyl-l-cysteine (NAC). The sodium-hydrogen exchanger 1 (NHE1) and NADPH oxidases (NOXs) were inhibited by cariporide, or GKT136901, respectively. Cell permeability and ROS were investigated by fluorescence intensity imaging. Cell permeability and ROS production were increased by 10% stretch; EMPA, DAPA and CANA decreased this effect significantly. Cariporide and GKT136901 inhibited stretch-induced ROS production but neither of them further reduced ROS production when combined with EMPA. SGLT-2i's improve the barrier dysfunction of HCAECs under enhanced stretch and this effect might be mediated through scavenging of ROS. Anti-oxidative effect of SGLT-2i's might be partially mediated by inhibition of NHE1 and NOXs.

The Mystery of Diabetic Cardiomyopathy: From Early Concepts and Underlying Mechanisms to Novel Therapeutic Possibilities

Diabetic patients are predisposed to diabetic cardiomyopathy, a specific form of cardiomyopathy which is characterized by the development of myocardial fibrosis, cardiomyocyte hypertrophy, and apoptosis that develops independently of concomitant macrovascular and microvascular diabetic complications. Its pathophysiology is multifactorial and poorly understood and no specific therapeutic guideline has yet been established. Diabetic cardiomyopathy is a challenging diagnosis, made after excluding other potential entities, treated with different pharmacotherapeutic agents targeting various pathophysiological pathways that need yet to be unraveled. It has great clinical importance as diabetes is a disease with pandemic proportions. This review focuses on the potential mechanisms contributing to this entity, diagnostic options, as well as on potential therapeutic interventions taking in consideration their clinical feasibility and limitations in everyday practice. Besides conventional therapies, we discuss novel therapeutic possibilities that have not yet been translated into clinical practice.

Cardiac Late Sodium Channel Current Is a Molecular Target for the Sodium/Glucose Cotransporter 2 Inhibitor Empagliflozin

BACKGROUND

SGLT2 (sodium/glucose cotransporter 2) inhibitors exert robust cardioprotective effects against heart failure in patients with diabetes, and there is intense interest to identify the underlying molecular mechanisms that afford this protection. Because the induction of the late component of the cardiac sodium channel current (late-INa) is involved in the etiology of heart failure, we investigated whether these drugs inhibit late-INa.

METHODS

Electrophysiological, in silico molecular docking, molecular, calcium imaging, and whole heart perfusion techniques were used to address this question.

RESULTS

The SGLT2 inhibitor empagliflozin reduced late-INa in cardiomyocytes from mice with heart failure and in cardiac Nav1.5 sodium channels containing the long QT syndrome 3 mutations R1623Q or ΔKPQ. Empagliflozin, dapagliflozin, and canagliflozin are all potent and selective inhibitors of H2O2-induced late-INa (half maximal inhibitory concentration = 0.79, 0.58, and 1.26 µM, respectively) with little effect on peak sodium current. In mouse cardiomyocytes, empagliflozin reduced the incidence of spontaneous calcium transients induced by the late-INa activator veratridine in a similar manner to tetrodotoxin, ranolazine, and lidocaine. The putative binding sites for empagliflozin within Nav1.5 were investigated by simulations of empagliflozin docking to a three-dimensional homology model of human Nav1.5 and point mutagenic approaches. Our results indicate that empagliflozin binds to Nav1.5 in the same region as local anesthetics and ranolazine. In an acute model of myocardial injury, perfusion of isolated mouse hearts with empagliflozin or tetrodotoxin prevented activation of the cardiac NLRP3 (nuclear-binding domain-like receptor 3) inflammasome and improved functional recovery after ischemia.

CONCLUSIONS

Our results provide evidence that late-INa may be an important molecular target in the heart for the SGLT2 inhibitors, contributing to their unexpected cardioprotective effects.

Implications of SGLT Inhibition on Redox Signalling in Atrial Fibrillation

Atrial fibrillation (AF) is the most common sustained (atrial) arrhythmia, a considerable global health burden and often associated with heart failure. Perturbations of redox signalling in cardiomyocytes provide a cellular substrate for the manifestation and maintenance of atrial arrhythmias. Several clinical trials have shown that treatment with sodium-glucose linked transporter inhibitors (SGLTi) improves mortality and hospitalisation in heart failure patients independent of the presence of diabetes. Post hoc analysis of the DECLARE-TIMI 58 trial showed a 19% reduction in AF in patients with diabetes mellitus (hazard ratio, 0.81 (95% confidence interval: 0.68-0.95), n = 17.160) upon treatment with SGLTi, regardless of pre-existing AF or heart failure and independent from blood pressure or renal function. Accordingly, ongoing experimental work suggests that SGLTi not only positively impact heart failure but also counteract cellular ROS production in cardiomyocytes, thereby potentially altering atrial remodelling and reducing AF burden. In this article, we review recent studies investigating the effect of SGLTi on cellular processes closely interlinked with redox balance and their potential effects on the onset and progression of AF. Despite promising insight into SGLTi effect on Ca²⁺ cycling, Na⁺ balance, inflammatory and fibrotic signalling, mitochondrial function and energy balance and their potential effect on AF, the data are not yet conclusive and the importance of individual pathways for human AF remains to be established. Lastly, an overview of clinical studies investigating SGLTi in the context of AF is provided.

Impact of SGLT2 Inhibitors on Heart Failure: From Pathophysiology to Clinical Effects

Heart failure (HF) affects up to over 20% of patients with type 2 diabetes (T2DM), even more in the elderly. Although, in T2DM, both hyperglycemia and the proinflammatory status induced by insulin resistance are crucial in cardiac function impairment, SGLT2i cardioprotective mechanisms against HF are several. In particular, these beneficial effects seem attributable to the significant reduction of intracellular sodium levels, well-known to exert a cardioprotective role in the prevention of oxidative stress and consequent cardiomyocyte death. From a molecular perspective, patients’ exposure to gliflozins’ treatment mimics nutrient and oxygen deprivation, with consequent autophagy stimulation. This allows to maintain the cellular homeostasis through different degradative pathways. Thus, since their introduction in the clinical practice, the hypotheses on SGLT2i mechanisms of action have changed: from simple glycosuric drugs, with consequent glucose lowering, erythropoiesis enhancing and ketogenesis stimulating, to intracellular sodium-lowering molecules. This provides their consequent cardioprotective effect, which justifies its significant reduction in CV events, especially in populations at higher risk. Finally, the updated clinical evidence of SGLT2i benefits on HF was summarized. Thus, this review aimed to analyze the cardioprotective mechanisms of sodium glucose transporter 2 inhibitors (SGLT2i) in patients with HF, as well as their clinical impact on cardiovascular events.

Low-Dose Empagliflozin Improves Systolic Heart Function after Myocardial Infarction in Rats: Regulation of MMP9, NHE1, and SERCA2a

The effects of the selective sodium-glucose cotransporter 2 (SGLT2) inhibitor empagliflozin in low dose on cardiac function were investigated in normoglycemic rats. Cardiac parameters were measured by intracardiac catheterization 30 min after intravenous application of empagliflozin to healthy animals. Empagliflozin increased the ventricular systolic pressure, mean pressure, and the max dP/dt (p < 0.05). Similarly, treatment with empagliflozin (1 mg/kg, p.o.) for one week increased the cardiac output, stroke volume, and fractional shortening (p < 0.05). Myocardial infarction (MI) was induced by ligation of the left coronary artery. On day 7 post MI, empagliflozin (1 mg/kg, p.o.) improved the systolic heart function as shown by the global longitudinal strain (−21.0 ± 1.1% vs. −16.6 ± 0.7% in vehicle; p < 0.05). In peri-infarct tissues, empagliflozin decreased the protein expression of matrix metalloproteinase 9 (MMP9) and favorably regulated the cardiac transporters sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA2a) and sodium hydrogen exchanger 1 (NHE1). In H9c2 cardiac cells, empagliflozin decreased the MMP2,9 activity and prevented apoptosis. Empagliflozin did not alter the arterial stiffness, blood pressure, markers of fibrosis, and necroptosis. Altogether, short-term treatment with low-dose empagliflozin increased the cardiac contractility in normoglycemic rats and improved the systolic heart function in the early phase after MI. These effects are attributed to a down-regulation of MMP9 and NHE1, and an up-regulation of SERCA2a. This study is of clinical importance because it suggests that a low-dose treatment option with empagliflozin may improve cardiovascular outcomes post-MI. Down-regulation of MMPs could be relevant to many remodeling processes including cancer disease.

From Systemic Inflammation to Myocardial Fibrosis: The Heart Failure With Preserved Ejection Fraction Paradigm Revisited

In accordance with the comorbidity-inflammation paradigm, comorbidities and especially metabolic comorbidities are presumed to drive development and severity of heart failure with preserved ejection fraction through a cascade of events ranging from systemic inflammation to myocardial fibrosis. Recently, novel experimental and clinical evidence emerged, which strengthens the validity of the inflammatory/profibrotic paradigm. This evidence consists among others of (1) myocardial infiltration by immunocompetent cells not only because of an obesity-induced metabolic load but also because of an arterial hypertension-induced hemodynamic load. The latter is sensed by components of the extracellular matrix like basal laminin, which also interact with cardiomyocyte titin; (2) expression in cardiomyocytes of inducible nitric oxide synthase because of circulating proinflammatory cytokines. This results in myocardial accumulation of degraded proteins because of a failing unfolded protein response; (3) definition by machine learning algorithms of phenogroups of patients with heart failure with preserved ejection fraction with a distinct inflammatory/profibrotic signature; (4) direct coupling in mediation analysis between comorbidities, inflammatory biomarkers, and deranged myocardial structure/function with endothelial expression of adhesion molecules already apparent in early preclinical heart failure with preserved ejection fraction (HF stage A, B). This new evidence paves the road for future heart failure with preserved ejection fraction treatments such as biologicals directed against inflammatory cytokines, stimulation of protein ubiquitylation with phosphodiesterase 1 inhibitors, correction of titin stiffness through natriuretic peptide-particulate guanylyl cyclase-PDE9 (phosphodiesterase 9) signaling and molecular/cellular regulatory mechanisms that control myocardial fibrosis.

SGLT-2 Inhibitors in Heart Failure: Guide for Prescribing and Future Perspectives

PURPOSE OF REVIEW

Heart failure is responsible for a significant part of diabetes-associated cardiovascular mortality and morbidity. Sodium-glucose cotransporter-2 (SGLT-2) inhibitors are novel agents approved for the treatment of diabetes mellitus; in recent clinical trials, these agents have shown a significant reduction in cardiovascular death and hospitalization secondary to heart failure.

RECENT FINDINGS

Clinical trials with specific heart failure outcomes have shown the benefit of SGLT-2 inhibitors in reducing the mortality and morbidity associated with heart failure. The guidelines for the management of diabetes mellitus recommend the preferential use of SGLT-2 inhibitors in patients with a history of cardiovascular disease. SGLT-2 inhibitors are potential game changers in the treatment of heart failure. Guidelines for prescription of these agents help assess risk-benefit analysis and personalize treatment for maximal benefit.

Roles of Sodium-Glucose Cotransporter 2 of Mesangial Cells in Diabetic Kidney Disease

We have been studying the presence of sodium-glucose cotransporter 2 (SGLT2) in mesangial cells and pericytes since 1992. Recent large placebo-controlled studies of SGLT2 inhibitors in patients with type 2 diabetes mellitus have reported desirable effects of the inhibitors on the diabetic kidney and the diabetic heart. Most studies have indicated that these effects of SGLT2 inhibitors could be mediated by the tubuloglomerular feedback system. However, a recent study about urine sodium excretion in the presence of an SGLT2 inhibitor did not show any increases in urine sodium excretion. A very small dose of an SGLT2 inhibitor did not inhibit SGLT2 at the S1 segment of proximal tubules. Moreover, SGLT2 inhibition protects against progression in chronic kidney disease with and without type 2 diabetes. In these circumstances, the tubuloglomerular feedback hypothesis involves several theoretical concerns that must be clarified. The presence of SGLT2 in mesangial cells seems to be very important for diabetic nephropathy. We now propose a novel mechanism by which the desirable effects of SGLT2 inhibitors on diabetic nephropathy are derived from the direct effect on SGLT2 expressed in mesangial cells.

Pathophysiology of diabetic kidney disease: impact of SGLT2 inhibitors

Diabetic kidney disease is the leading cause of kidney failure worldwide; in the USA, it accounts for over 50% of individuals entering dialysis or transplant programmes. Unlike other complications of diabetes, the prevalence of diabetic kidney disease has failed to decline over the past 30 years. Hyperglycaemia is the primary aetiological factor responsible for the development of diabetic kidney disease. Once hyperglycaemia becomes established, multiple pathophysiological disturbances, including hypertension, altered tubuloglomerular feedback, renal hypoxia, lipotoxicity, podocyte injury, inflammation, mitochondrial dysfunction, impaired autophagy and increased activity of the sodium-hydrogen exchanger, contribute to progressive glomerular sclerosis and the decline in glomerular filtration rate. The quantitative contribution of each of these abnormalities to the progression of diabetic kidney disease, as well as their role in type 1 and type 2 diabetes mellitus, remains to be determined. Sodium-glucose co-transporter 2 (SGLT2) inhibitors have a beneficial impact on many of these pathophysiological abnormalities; however, as several pathophysiological disturbances contribute to the onset and progression of diabetic kidney disease, multiple agents used in combination will likely be required to slow the progression of disease effectively.

Sodium-glucose transporter inhibition in heart failure: from an unexpected side effect to a novel treatment possibility

Sodium-glucose transporter-2 inhibitors (SGLT2i), originally launched as glucose-lowering drugs, have been studied in large cardiovascular outcome trials to ascertain safety. Surprisingly, these compounds reduced the risk of cardiovascular events (cardiovascular death, non-fatal myocardial and non-fatal stroke) and total mortality. The mechanisms behind this benefit are only partly understood, but a major contributor is the reduction of heart failure hospitalisations, evident already within weeks after the initiation of the SGLT2i. SGLT2 inhibition increases urinary glucose excretion, thereby improving glycaemic control in an insulin-independent manner. Moreover, SGLT2i potentially impact the cardiovascular system both indirectly via weight loss and blood pressure lowering and directly through osmotic diuresis and increased sodium excretion and presumably by improving myocardial energetics. The aim of this review is to summarise evidence from all major outcome trials investigating SGLT2i in patients with diabetes, as well as recent evidence from trials in heart failure patients without glucose perturbations, which pave the way for novel treatment of large groups of patients. The results of these studies have been taken into account in recently issued guidelines for the management of diabetes and cardiovascular disease. An important task for diabetologists, cardiologists and general practitioners is to incorporate them into clinical practice to the benefit of many patients.

Effects of Dapagliflozin on Cardiovascular Events, Death, and Safety Outcomes in Patients with Heart Failure: A Meta-Analysis

BACKGROUND

Several clinical trials of dapagliflozin in patients with type 2 diabetes mellitus (T2DM) at elevated cardiovascular risk have observed reduced hospitalization for heart failure (HHF). Several studies have also suggested cardiovascular benefits for patients with HF regardless of whether or not they have T2DM.

OBJECTIVE

This meta-analysis was conducted to evaluate the therapeutic effects of dapagliflozin in patients with HF.

METHODS

The PubMed, Embase, Cochrane Library, and Web of Science databases were systematically searched from database inception to 15 February 2020. Clinical studies of dapagliflozin use in patients with HF were included. Data on HHF, all-cause mortality, cardiovascular death, major adverse cardiovascular events (MACE), systolic blood pressure, body weight, glycated hemoglobin (HbA1c), and adverse events were collected for analysis.

RESULTS

Four randomized controlled trials involving 6738 patients with HF were included in this meta-analysis. Patients receiving dapagliflozin showed a significantly lower incidence of HHF [risk ratio (RR) 0.72; P < 0.00001], all-cause mortality (RR 0.83; P = 0.004), cardiovascular death (RR 0.86; P = 0.03), and MACE (RR 0.88; P = 0.03). Moreover, patients receiving dapagliflozin also showed significant improvements in systolic blood pressure and body weight. However, no statistical difference was observed in HbA1c. In addition, hypoglycemia, volume depletion, and renal impairment was not more frequent with dapagliflozin than with placebo.

CONCLUSION

This meta-analysis suggests that dapagliflozin could be a therapeutic strategy for patients with HF regardless of the presence or absence of T2DM.

SGLT2-inhibitors; more than just glycosuria and diuresis

Heart failure (HF) continues to be a serious public health challenge despite significant advancements in therapeutics and is often complicated by multiple other comorbidities. Of particular concern is type 2 diabetes mellitus (T2DM) which not only amplifies the risk, but also limits the treatment options available to patients. The sodium-glucose linked cotransporter subtype 2 (SGLT2)-inhibitor class, which was initially developed as a treatment for T2DM, has shown great promise in reducing cardiovascular risk, particularly around HF outcomes - regardless of diabetes status.There are ongoing efforts to elucidate the true mechanism of action of this novel drug class. Its primary mechanism of inducing glycosuria and diuresis from receptor blockade in the renal nephron seems unlikely to be responsible for the rapid and striking benefits seen in clinical trials. Early mechanistic work around conventional therapeutic targets seem to be inconclusive. There are some emerging theories around its effect on myocardial energetics and calcium balance as well as on renal physiology. In this review, we discuss some of the cutting-edge hypotheses and concepts currently being explored around this drug class in an attempt better understand the molecular mechanics of this novel agent.