Sodium Glucose Cotransporter 1 (SGLT1) Inhibitors in Cardiovascular Protection: Mechanism Progresses and Challenges

A Human Engineered Heart Tissue-Derived Lipotoxic Diabetic Cardiomyopathy Model Revealed Early Benefits of Empagliflozin

Diabetic cardiomyopathy (DbCM) is increasingly prevalent, but intervention targets remain unclear due to the lack of appropriate models and the complexity of risk factors. Here, this work establishes an in vitro assessment system for DbCM function using cardiomyocytes derived from human pluripotent stem cells and engineered heart tissue. This work finds high-fat status in complex diabetes risk factors majorly contributes most to cardiomyocyte death and contractile dysfunction. Notably, PA induced early electrophysiological abnormalities, and lately is associated with cardiac fibrosis, mitochondrial fission, and systolic and diastolic dysfunction at tissue level. Using this in vitro assessment system, this work finds that empagliflozin (EMPA), a first-line glucose-lowering drug, effectively alleviated early PA-induced cardiomyocyte injury. Treatment with EMPA enhanced abnormal diastolic and electrophysiological functions in the PA-hEHT model and significantly reduced endoplasmic reticulum stress, and apoptosis. Furthermore, these promising results are confirmed in a type 2 diabetes mellitus mouse model, reinforcing the potential of EMPA as a therapeutic option to alleviate cardiomyocyte injury under diabetic conditions. These findings suggest that this work has developed an engineered model of diabetic cardiomyopathy that mimics the various stages of lipotoxic myocardial injury and support the use of EMPA as a potential therapeutic option for diabetic or lipotoxic cardiomyopathy.

Intestinal Gastrin/CCKBR Axis Protects against Type 2 Diabetes by Reducing Intestinal Glucose Absorption through the PI3K/Akt/eIF4B Signaling Pathway

The Gastrin/CCKBR axis is essential for inhibiting intestinal sodium absorption, but its effects on intestinal glucose metabolism remain elusive. This study aims to determine the role of intestinal Gastrin/CCKBR on glucose absorption in the development of type 2 diabetes (T2D). Intestinal epithelial cell-specific Cckbr knockout mice and control wild-type mice are fed normal diet (ND, 10% fat) or high fat diet (HFD, 60% fat) to study the effect of intestinal Gastrin/CCKBR on blood glucose levels. Gastrin-SiO2 microspheres (20 mg kg-1 d-1) are designed so that gastrin specifically stimulates intestinal CCKBR, without its absorption into the circulation. Mice with silenced intestinal Cckbr has pre-diabetes mellitus (Pre-DM) that rapidly progressed into T2D when fed HFD. Moreover, Gastrin-SiO2 microspheres markedly reduce glucose absorption in duodenum obtained from patients with T2D. In mice with HFD-induced T2D, Gastrin-SiO2 microspheres reduce intestinal glucose absorption by down-regulating intestinal SGLT1 and GLUT2 expressions and stimulating incretin secretion. This study shows the important role of intestinal Gastrin/CCKBR in intestinal glucose absorption. Gastrin-SiO2 microspheres may be a promising strategy for the treatment of patients with T2D.

The role of SGLT1 in atrial fibrillation and its relationship with endothelial-mesenchymal transition

Atrial fibrillation (AF) is a prevalent arrhythmia closely associated with atrial fibrosis, posing significant challenges to cardiovascular health. Recent studies have identified the sodium-glucose co-transporter 1 (SGLT1) as a potential key player in the pathophysiology of heart diseases, particularly in the context of AF and atrial fibrosis. This review aims to synthesize current knowledge regarding the mechanisms by which SGLT1 influences the development of AF and atrial fibrosis, with a specific focus on its relationship with endothelial-mesenchymal transition (EMT). By analyzing the latest research findings, this paper discusses how SGLT1 may modulate structural and functional changes in the atria, thereby enhancing our understanding of the underlying mechanisms driving AF.

Rationale and Design of the SOTA-P-CARDIA Trial (ATRU-V): Sotagliflozin in HFpEF Patients Without Diabetes

Heart failure with preserved ejection fraction (HFpEF) is now the most common form of heart failure (HF). This syndrome is associated with an elevated morbi-mortality, and effective therapies are urgently needed. Sodium-glucose co-transporter 2 inhibitors (SGLT2i) are the first pharmacological class that has demonstrated to reduce hospitalization and cardiovascular mortality in large clinical trials in HFpEF. Furthermore, the dual SGLT 1/2 inhibitor sotagliflozin has shown a reduction in cardiovascular outcomes in diabetic HF patients, regardless of ejection fraction Sotagliflozin on Cardiovascular Events in Patients with Type 2 Diabetes Post Worsening Heart Failure (SOLOIST-WHF) Trial, and prevents the development of HF in patients with diabetes and chronic kidney disease Sotagliflozin on Cardiovascular and Renal Events in Patients with Type 2 Diabetes and Moderate Renal Impairment Who Are at Cardiovascular Risk (SCORED) trial. The major objective of the Sotagliflozin in Heart Failure With Preserved Ejection Fraction Patients (SOTA-P-CARDIA) trial (NCT05562063) is to investigate whether the observed cardiorenal benefits of sotagliflozin in HF patients with diabetes can be extended to a non-diabetic population. The SOTA-P-CARDIA is a prospective, randomized, double-blinded, placebo-controlled study that will randomize non-diabetic patients with the universal definition of HFpEF (ejection fraction > 50% assessed the day of randomization). Qualifying patients will be randomized, in blocks of 4, to receive either sotagliflozin or placebo for a period of 6 months. The primary outcome is changes in left ventricular mass by cardiac magnetic resonance from randomization to end of the study between the groups. Secondary end points include changes in peak VO2; myocardial mechanics, interstitial myocardial fibrosis, and volume of epicardial adipose tissue; distance in the 6-min walk test; and quality of life. Finally, the authors expect that this trial will help to clarify the potential benefits of the use of sotagliflozin in non-diabetic HFpEF patients.

Synthesis of a Small Library of Glycoderivative Putative Ligands of SGLT1 and Preliminary Biological Evaluation

Sodium-glucose co-transporter 1 (SGLT1) is primarily expressed on the membrane of enterocytes, a type of epithelial cell found in the intestines, where it mediates the unidirectional absorption of glucose and galactose. Beyond its well-established role in nutrient absorption, SGLT1 also plays a protective role in maintaining the integrity of the intestinal barrier. Specifically, the natural ligand of SGLT1 (d-glucose) and a synthetic C-glucoside developed by our group can induce a protective anti-inflammatory effect on the intestinal epithelium. In this paper, we report the creation of a small library of C-glycoside, putative ligands for SGLT1, to gain further insights into its unclear mechanism of action. Preliminary biological experiments performed on an in vitro model of doxorubicin-induced mucositis, a severe intestinal inflammatory condition, indicate that the aromatic moiety present in all the compounds of the library is crucial for biological activity, while the sugar component appears to have less influence. These findings will be exploited to develop new, more potent anti-inflammatory compounds and to better understand and rationalize the protective mechanism of action.

Evolution of translational control and the emergence of genes and open reading frames in human and non-human primate hearts

Evolutionary innovations can be driven by changes in the rates of RNA translation and the emergence of new genes and small open reading frames (sORFs). In this study, we characterized the transcriptional and translational landscape of the hearts of four primate and two rodent species through integrative ribosome and transcriptomic profiling, including adult left ventricle tissues and induced pluripotent stem cell-derived cardiomyocyte cell cultures. We show here that the translational efficiencies of subunits of the mitochondrial oxidative phosphorylation chain complexes IV and V evolved rapidly across mammalian evolution. Moreover, we discovered hundreds of species-specific and lineage-specific genomic innovations that emerged during primate evolution in the heart, including 551 genes, 504 sORFs and 76 evolutionarily conserved genes displaying human-specific cardiac-enriched expression. Overall, our work describes the evolutionary processes and mechanisms that have shaped cardiac transcription and translation in recent primate evolution and sheds light on how these can contribute to cardiac development and disease.

The Off-Target Cardioprotective Mechanisms of Sodium-Glucose Cotransporter 2 Inhibitors: An Overview

Sodium-glucose cotransporter 2 inhibitors (SGLT2i), a novel class of glucose-lowering drugs, have revolutionized the management of heart failure with reduced and preserved ejection fraction, regardless of the presence of diabetes, and are currently incorporated in the heart failure guidelines. While these drugs have consistently demonstrated their ability to decrease heart failure hospitalizations in several landmark clinical trials, their cardioprotective effects are far from having been completely elucidated. In the past decade, a growing body of experimental research has sought to address the molecular and cellular mechanisms of SGLT2i in order to provide a better understanding of the off-target acute and chronic cardiac benefits, beyond the on-target renal effect responsible for blood glucose reduction. The present narrative review addresses the direct cardioprotective effects of SGLT2i, delving into the off-target mechanisms of the drugs currently approved for heart failure therapy, and provides insights into future perspectives.

Sodium-glucose cotransporter 1/2 inhibition and risk of neurodegenerative disorders: A Mendelian randomization study

INTRODUCTION

This study aims to evaluate the effects of sodium-glucose cotransporter 1 inhibitors (SGLT1i) and sodium-glucose cotransporter 2 inhibitors (SGLT2i) on neurodegenerative disorders and to investigate the role of hemoglobin A1c (HbA1c) levels.

METHODS

Utilizing drug target Mendelian randomization, we employed single nucleotide polymorphisms (SNPs) proximal to the SLC5A1 and SLC5A2 genes to analyze the influence of SGLT1i and SGLT2i on Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), frontotemporal dementia (FTD), Lewy body dementia (LBD), and amyotrophic lateral sclerosis (ALS), with type 2 diabetes (T2D) as a positive control. An additional analysis examined the impact of HbA1c levels on the same disorders.

RESULTS

SGLT1i exhibited a significant association with decreased risk for ALS and MS. Conversely, SGLT2i were linked to an increased risk of AD, PD, and MS. Elevated HbA1c levels, independent of SGLT1 and SGLT2 effects, were associated with an increased risk of PD. Sensitivity analyses supported the robustness of these findings.

CONCLUSION

Our study suggests that SGLT1i may confer protection against ALS and MS, whereas SGLT2i could elevate the risk of AD, PD, and MS. Additionally, elevated HbA1c levels emerged as a risk factor for PD. These findings underscore the importance of personalized approaches in the utilization of SGLT inhibitors, considering their varying impacts on the risks of neurodegenerative diseases.

Canagliflozin inhibits PASMCs proliferation via regulating SGLT1/AMPK signaling and attenuates artery remodeling in MCT-induced pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) was a devastating disease characterized by artery remodeling, ultimately resulting in right heart failure. The aim of this study was to investigate the effects of canagliflozin (CANA), a sodium-glucose cotransporter 2 inhibitor (SGLT2i) with mild SGLT1 inhibitory effects, on rats with PAH, as well as its direct impact on pulmonary arterial smooth muscle cells (PASMCs). PAH rats were induced by injection of monocrotaline (MCT) (40 mg/kg), followed by four weeks of treatment with CANA (30 mg/kg/day) or saline alone. Pulmonary artery and right ventricular (RV) remodeling and dysfunction in PAH were alleviated with CANA, as assessed by echocardiography. Hemodynamic parameters and structural of pulmonary arteriole, including vascular wall thickness and wall area, were reduced by CANA. RV hypertrophy index, cardiomyocyte hypertrophy, and fibrosis were decreased with CANA treatment. PASMCs proliferation was inhibited by CANA under stimulation by platelet-derived growth factor (PDGF)-BB or hypoxia. Activation of AMP kinase (AMPK) was induced by CANA treatment in cultured PASMCs in a time- and concentration-dependent manner. These effects of CANA were attenuated when treatment with compound C, an AMPK inhibitor. Abundant expression of SGLT1 was observed in PASMCs and pulmonary arteries, while SGLT2 expression was undetectable. SGLT1 increased in response to PDGF-BB or hypoxia stimulation, while PASMCs proliferation was inhibited and beneficial effects of CANA were counteracted by knockdown of SGLT1. Our research demonstrated for the first time that CANA inhibited the proliferation of PASMCs by regulating SGLT1/AMPK signaling and thus exerted an anti-proliferative effect on MCT-induced PAH.

mTORC1 and SGLT2 Inhibitors-A Therapeutic Perspective for Diabetic Cardiomyopathy

Diabetic cardiomyopathy is a critical diabetes-mediated co-morbidity characterized by cardiac dysfunction and heart failure, without predisposing hypertensive or atherosclerotic conditions. Metabolic insulin resistance, promoting hyperglycemia and hyperlipidemia, is the primary cause of diabetes-related disorders, but ambiguous tissue-specific insulin sensitivity has shed light on the importance of identifying a unified target paradigm for both the glycemic and non-glycemic context of type 2 diabetes (T2D). Several studies have indicated hyperactivation of the mammalian target of rapamycin (mTOR), specifically complex 1 (mTORC1), as a critical mediator of T2D pathophysiology by promoting insulin resistance, hyperlipidemia, inflammation, vasoconstriction, and stress. Moreover, mTORC1 inhibitors like rapamycin and their analogs have shown significant benefits in diabetes and related cardiac dysfunction. Recently, FDA-approved anti-hyperglycemic sodium-glucose co-transporter 2 inhibitors (SGLT2is) have gained therapeutic popularity for T2D and diabetic cardiomyopathy, even acknowledging the absence of SGLT2 channels in the heart. Recent studies have proposed SGLT2-independent drug mechanisms to ascertain their cardioprotective benefits by regulating sodium homeostasis and mimicking energy deprivation. In this review, we systematically discuss the role of mTORC1 as a unified, eminent target to treat T2D-mediated cardiac dysfunction and scrutinize whether SGLT2is can target mTORC1 signaling to benefit patients with diabetic cardiomyopathy. Further studies are warranted to establish the underlying cardioprotective mechanisms of SGLT2is under diabetic conditions, with selective inhibition of cardiac mTORC1 but the concomitant activation of mTORC2 (mTOR complex 2) signaling.

Effects of the Sodium-Glucose Cotransporter Inhibitors on Cardiovascular Death and All-Cause Mortality: A Systematic Review and Meta-analysis of Randomized Placebo-Controlled Clinical Trials

BACKGROUND

Patients with diabetes mellitus are at an increased risk of cardiovascular morbidity and all-cause mortality. Heart failure and type 2 diabetes often occur concomitantly, and each disease independently increases the risk for the other.

OBJECTIVE

Emerging data have revealed that some sodium-glucose cotransporter inhibitors (SGLTi) improve cardiovascular and renal outcomes, particularly in patients with type 2 diabetes. The magnitude of this effect in patients without any underlying condition remains unclear. As a result, we conducted a meta-analysis of the mortality outcomes of available SGLTi in patients with or without cardiovascular diseases, type 2 diabetes, cardiovascular risk factors, and heart failure.

METHODS

We performed a systematic review and meta-analysis of randomized, placebo-controlled major cardiovascular outcome trials of SGLTi in patients regardless of their cardiovascular disease or risk status. PubMed, Cochrane, Google Scholar, MEDLINE, and EMBASE were searched for the relevant studies. Three reviewers extracted study data and three reviewers summarized the strength of the evidence. Efficacy outcomes included all-cause mortality, major adverse cardiovascular events (myocardial infarction, stroke, or cardiovascular death), the composite of all-cause mortality, cardiovascular death, or hospitalization for heart failure. Odds ratios with 95% confidence intervals were pooled across trials to calculate the overall effect size.

RESULTS

A total of 5043 all-cause mortality events were observed in the study groups. In 42,050 patients who received SGLTi, 2581 events were reported, and 2462 events were reported in 35,491 patients who received placebo (odds ratio = 0.86, 95% confidence interval 0.80-0.93, p = 0.0003). The use of SGLTi significantly reduced cardiovascular mortality compared with control across the patients' population (odds ratio = 0.86, 95% confidence interval 0.79-0.93, p = 0.0001). There was a consistent pattern of mortality beneficial estimates for all patients with different co-morbid conditions in the SGLTi-treated arm compared with the placebo-treated group. The presence or absence of significant cardiovascular disease risk factors (including a family history of premature coronary artery disease, baseline estimated glomerular filtration rate, dyslipidemia, hypertension, smoking, history of cardiovascular disease, and older age) did not affect the estimated mortality benefits.

CONCLUSIONS

Sodium-glucose cotransporter inhibitors significantly reduced major adverse cardiovascular events, including hospitalization and all-cause mortality in patients with or without established atherosclerotic cardiovascular disease. We observed a beneficial trend in patients with heart failure with preserved ejection fraction, and no benefits in patients with stroke or myocardial infarction.

MTHFR epigenetic derepression protects against diabetes cardiac fibrosis

BACKGROUND

Diabetes cardiac fibrosis is associated with altered DNA methylation of fibrogenic genes; however, the underlying mechanisms remain unclear.

OBJECTIVES

In this study, we investigate the critical role of DNA methylation aberration-associated suppression of MTHFR in diabetes cardiac fibrosis, and the protective effects of folate on diabetes cardiac fibrosis, using cultured cells, animal models, and clinical samples.

METHODS AND RESULTS

Herein, we report that DNA methylation repression of MTHFR, critically involved in diabetes cardiac fibrosis, mediates the significant protective effects of folate in a mouse model of diabetes cardiac fibrosis induced by STZ. Heart MTHFR expression was markedly suppressed in diabetes cardiac fibrosis patients and mice, accompanied by increased DNMT3A and MTHFR promoter methylation. Knockdown of DNMT3A demethylated MTHFR promoter, recovered the MTHFR loss, and alleviated the diabetes cardiac fibrosis pathology and cardiac fibroblasts pyroptosis. Mechanistically, DNMT3A epigenetically repressed MTHFR expression via methylation of the promoter. Interestingly, folate supplementation can rescue the effect of MTHFR loss in diabetes cardiac fibrosis, suggesting that inactivation of MTHFR through epigenetics is a critical mediator of diabetes cardiac fibrosis.

CONCLUSIONS

The current study identifies that MTHFR repression due to aberrant DNMT3A elevation and subsequent MTHFR promoter hypermethylation is likely an important epigenetic feature of diabetes cardiac fibrosis, and folate supplementation protects against diabetes cardiac fibrosis.

Beneficial cardiovascular and remodeling effects of SGLT2 inhibitors: pathophysiologic mechanisms

INTRODUCTION

The intent of this paper is to review the data regarding the multipotential effects of the sodium-glucose cotransporter 2 (SGLT 2) inhibitors, their cardiovascular protective effects, and their mechanism of action.

AREAS COVERED

The SGLT2 inhibitors exert their beneficial antidiabetic and cardioprotective effects through increased glucose excretion from the kidneys, blood pressure and weight lowering, vasodilation and other potential beneficial effects. They have been used for the treatment of patients with type 2 diabetes mellitus (T2DM) as well as in patients with cardiovascular disease (CVD), coronary artery disease (CAD),and heart failure with reduced ejection fraction (HFrEF) and heart failure with preserved ejection fraction (HFpEF). In order to get a better understanding of their mechanism of action for their multiple cardiovascular protective effects, a Medline search of the English language literature was conducted between 2015 and February 2022 and 46 pertinent papers were selected.

EXPERT OPINION

The analysis of data clearly demonstrated that the use of the SGLT2 inhibitors besides their antidiabetic effects, provide additional protection against CVD, CAD, and HFrEF and HFpEF, and death, but not stroke, in both diabetic and non-diabetic patients. Therefore, they should be preferably used for the treatment of patients with T2DM with preexisting CVD, CAD, and HFrEF and HFpEF.