A sodium-glucose cotransporter 2 (SGLT2) inhibitor dapagliflozin comparison with insulin shows important effects on Zn2+-transporters in cardiomyocytes from insulin-resistant metabolic syndrome rats through inhibition of oxidative stress 1

Dapagliflozin attenuates LPS-induced myocardial injury by reducing ferroptosis

Septic cardiomyopathy is a severe cardiovascular disease with a poor prognosis. Previous studies have reported the involvement of ferroptosis in the pathogenesis of septic cardiomyopathy. SGLT2 inhibitors such as dapagliflozin have been demonstrated to improve ischemia-reperfusion injury by alleviating ferroptosis in cardiomyocyte. However, the role of dapagliflozin in sepsis remains unclear. Therefore, our study aims to investigate the therapeutic effects of dapagliflozin on LPS-induced septic cardiomyopathy. Our results indicate that dapagliflozin improved cardiac function in septic cardiomyopathy experimental mice. Mechanistically, dapagliflozin works by inhibiting the translation of key proteins involved in ferroptosis, such as GPX4, FTH1, and SLC7A11. It also reduces the transcription of lipid peroxidation-related mRNAs, including PTGS2 and ACSL4, as well as iron metabolism genes TFRC and HMOX1.

SGLT2 inhibitor as a potential therapeutic approach in hyperthyroidism-induced cardiopulmonary injury in rats

Hyperthyroidism-induced cardiac disease is an evolving health, economic, and social problem affecting well-being. Sodium-glucose cotransporter protein 2 inhibitors (SGLT2-I) have been proven to be cardio-protective when administered in cases of heart failure. This study intended to investigate the potential therapeutic effect of SGLT2-I on hyperthyroidism-related cardiopulmonary injury, targeting the possible underlying mechanisms. The impact of the SGLT2-I, dapagliflozin (DAPA), (1 mg/kg/day, p.o) on LT4 (0.3 mg/kg/day, i.p)-induced cardiopulmonary injury was investigated in rats. The body weight, ECG, and serum hormones were evaluated. Also, redox balance, DNA fragmentation, inflammatory cytokines, and PCR quantification in heart and lung tissues were employed to investigate the effect of DAPA in experimentally induced hyperthyroid rats along with histological and immunohistochemical examination. Coadministration of DAPA with LT4 effectively restored all serum biomarkers to nearly average levels, improved ECG findings, and reinstated the redox balance. Also, DAPA could improve DNA fragmentation, elevate mtTFA, and lessen TNF-α and IGF-1 gene expression in both organs of treated animals. Furthermore, DAPA markedly improved the necro-inflammatory and fibrotic cardiopulmonary histological alterations and reduced the tissue immunohistochemical expression of TNF-α and caspase-3. Although further clinical and deep molecular studies are required before transposing to humans, our study emphasized DAPA's potential to relieve hyperthyroidism-induced cardiopulmonary injury in rats through its antioxidant, anti-inflammatory, and anti-apoptotic effects, as well as via antagonizing the sympathetic over activity.

A Study to Evaluate the Effect of Sodium-Glucose Co-transporter 2 (SGLT2) Inhibitors on Oxidative Stress Parameters in Type 2 Diabetes Mellitus Patients

Introduction Diabetes mellitus (DM) is a global health issue with 50 million diabetics currently residing in India. Hyperglycemia causes tissue damage due to mitochondrial overproduction of reactive oxygen species. Sodium-glucose cotransporter-2 (SGLT2) inhibitors (SGLT2i) have shown a decrease in oxidative stress by either amelioration of free-radical generation or potentiation of cellular antioxidative capacity in preclinical studies. However, there is a paucity of published clinical studies. Hence, this study was undertaken to evaluate the effect of co-administration of SGLT2i with other drugs on oxidative stress in type 2 DM (T2DM) patients. Methods A prospective, parallel, open-label study in T2DM patients attending endocrinology OPD was conducted for a period of 12 months. At the clinician's discretion, patients were grouped as SGLT2i as an add-on to standard drugs vs standard drugs alone. Blood samples were collected at baseline and at the end of 12 weeks to estimate malondialdehyde (MDA), nitric oxide (NO), and glutathione (GSH) levels. Secondary parameters - glycemic indices and lipid profile - were estimated every four weeks. Results A total of 32 patients were enrolled in the study (16 per group). There was a significant decrease in MDA (p < 0.05) and NO (p < 0.01) and a highly significant increase in GSH (p < 0.001) at 12 weeks from baseline in the SGLT2i group. A reduction in fasting blood sugar (FBS) and post-prandial blood sugar (PPBS) and a 0.56% difference in HbA1c were also noted in the SGLT2i group. Significant lowering of low-density lipoprotein (LDL, p < 0.05) and elevation in HDL levels (p < 0.05) from baseline was seen in the SGLT2i group.  Conclusion Co-administration of SGLT2i with antidiabetic drugs demonstrated a significant effect in improving oxidative stress biomarkers and glycemic and lipid profiles among T2DM patients.

Effect of SGLT2 Inhibitor on Cardiomyopathy in a Rat Model of T2DM: Possible involvement of Cardiac Aquaporins

Diabetic cardiomyopathy (DCM) causes arrhythmia, heart failure, and sudden death. Empagliflozin, an SGLT-2 (Sodium glucose co-transporter) inhibitor, is an anti-diabetic medication that decreases blood glucose levels by stimulating urinary glucose excretion. Several aquaporins (AQPs) including AQP-1-3 and - 4 and their involvement in the pathogenesis in different cardiac diseases were detected. In the current study the effect of Empagliflozin on diabetic cardiomyopathy and the possible involvement of cardiac AQPs were investigated.

METHODS

56 adult male Sprague-Dawley rats were divided into 4 groups: Control, DCM: type 2 diabetic rats, low EMPA+DCM received empagliflozin (10 mg/kg/day) and high EMPA+DCM received empagliflozin (30 mg/kg/day) for 6 weeks.

RESULTS

Administration of both EMPA doses, especially in high dose group, led to significant improvement in ECG parameters. Also, a significant improvement in biochemical and cardiac oxidative stress markers (significant decrease in serum CK-MB, and malondialdehyde while increasing catalase) with decreased fibrosis and edema in histopathological examination and a significant attenuation in apoptosis (caspase-3) and edema (AQP-1& -4).

CONCLUSION

Both doses of Empagliflozin have a cardioprotective effect and reduced myocardial tissue edema with high dose having a greater effect. This might be due to attenuation of oxidative stress, fibrosis and edema mediated through AQP-1, - 3& - 4 expression.

Effects of Dapagliflozin on Myocardial Gene Expression in BTBR Mice with Type 2 Diabetes

BACKGROUND

Dapagliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor, is approved for the treatment of type 2 diabetes, heart failure, and chronic kidney disease. DAPA-HF and DELIVER trial results demonstrate that the cardiovascular protective effect of dapagliflozin extends to non-diabetic patients. Hence, the mechanism-of-action may extend beyond glucose-lowering and is not completely elucidated. We have previously shown that dapagliflozin reduces cardiac hypertrophy, inflammation, fibrosis, and apoptosis and increases ejection fraction in BTBR mice with type 2 diabetes.

METHODS

We conducted a follow-up RNA-sequencing study on the heart tissue of these animals and performed differential expression and Ingenuity Pathway analysis. Selected markers were confirmed by RT-PCR and Western blot.

RESULTS

SGLT2 had negligible expression in heart tissue. Dapagliflozin improved cardiac metabolism by decreasing glycolysis and pyruvate utilization enzymes, induced antioxidant enzymes, and decreased expression of hypoxia markers. Expression of inflammation, apoptosis, and hypertrophy pathways was decreased. These observations corresponded to the effects of dapagliflozin in the clinical trials.

Overexpression of Slc30a7/ZnT7 increases the mitochondrial matrix levels of labile Zn2+ and modifies histone modification in hyperinsulinemic cardiomyoblasts

BACKGROUND

Cellular free Zn²⁺ concentrations ([Zn²⁺]) are primarily coordinated by Zn²⁺-transporters, although their roles are not well established in cardiomyocytes. Since we previously showed the important contribution of a Zn²⁺-transporter ZnT7 to [Zn²⁺]_i regulation in hyperglycemic cardiomyocytes, here, we aimed to examine a possible regulatory role of ZnT7 not only on [Zn²⁺]_i but also both the mitochondrial-free Zn²⁺ and/or Ca²⁺ in cardiomyocytes, focusing on the contribution of its overexpression to the mitochondrial function.

METHODS

We mimicked either hyperinsulinemia (by 50-μM palmitic acid, PA-cells, for 24-h) or overexpressed ZnT7 (ZnT7OE-cells) in H9c2 cardiomyoblasts.

RESULTS

Opposite to PA-cells, the [Zn²⁺]_i in ZnT7OE-cells was not different from untreated H9c2-cells. An investigation of immunofluorescence imaging by confocal microscopy demonstrated a ZnT7 localization on the mitochondrial matrix. We demonstrated the ZnT7 localization on the mitochondrial matrix by using immunofluorescence imaging. Later, we determined the mitochondrial levels of [Zn²⁺]_Mit and [Ca²⁺]_Mit by using the Zn²⁺ and Ca²⁺ sensitive FRET probe and a Ca²⁺-sensitive dye Fluo4, respectively. The [Zn²⁺]_Mit was found to increase significantly in ZnT7OE-cells, similar to the PA-cells while no significant changes in the [Ca²⁺]_Mit in these cells. To examine the contribution of ZnT7 overexpression on the mitochondria function, we determined the level of reactive oxygen species (ROS) and the mitochondrial membrane potential (MMP) in these cells in comparison to the PA-cells. There were significantly increased production of ROS and depolarization in MMP and increases in marker proteins of mitochondria-associated apoptosis and autophagy in ZnT7-OE cells, similar to the PA-cells, parallel to increases in K-acetylation. Moreover, we determined significant increases in trimethylation of histone H3 lysine27, H3K27me3, and the mono-methylation of histone H3 lysine36, H3K36 in the ZnT7OE-cells, demonstrating the role of [Zn²⁺]_Mit in epigenetic regulation of cardiomyocytes under hyperinsulinemia through histone modification.

CONCLUSIONS

Overall, our data have shown an important contribution of high expression of ZnT7-OE, through its buffering and muffling capacity in cardiomyocytes, on the regulation of not only [Zn²⁺_]i but also both [Zn²⁺]_Mit and [Ca²⁺]_Mit affecting mitochondria function, in part, via histone modification.

The Importance of SGLT-2 Inhibitors as Both the Prevention and the Treatment of Diabetic Cardiomyopathy

According to the 2021 report of the International Diabetes Federation (IDF), there have been approximately 573 million cases of type 2 diabetes mellitus (T2DM) among adults, which sets the disease as a major concern in healthcare worldwide. The development of T2DM is strongly promoted by unhealthy lifestyle factors associated with urbanization and western civilization. The disease is associated with a broad list of systemic complications that can result in premature death, disability and significantly reduced quality of life. The most dramatic in their consequences are cardiovascular complications of T2DM. Our work focuses on one such complication that is specific for diabetes, named diabetic cardiomyopathy (DC). In this condition cardiac dysfunction occurs despite the absence of underlying hypertension, coronary artery disease and valvular disease, which suggest a leading role for metabolic disturbances as a cause. We aimed to establish the role of relatively new hypoglycaemic drugs that have taken the medical world by storm with their broad pleiotropic effects-SGLT-2 inhibitors-in the prevention and treatment of DC at any stage.

Exercise Augments the Effect of SGLT2 Inhibitor Dapagliflozin on Experimentally Induced Diabetic Cardiomyopathy, Possible Underlying Mechanisms

One of the most prevalent cardiovascular problems linked with type 2 diabetes mellitus (T2DM) is diabetic cardiomyopathy (DCM). DCM is associated with myocardial oxidative stress, inflammation, apoptosis, suppressed autophagy, extracellular matrix remodeling, and fibrosis. The current study aims to investigate the protective effect of sodium-glucose transport 2 inhibitor (SGLT2i) dapagliflozin and/or exercise on DCM. Thirty adult male Sprague Dawley rats are used. T2DM is induced by a 6-week high-fat diet (HFD) followed by a single intraperitoneal (IP) injection of 35 mg/kg streptozotocin (STZ). Rats are divided into five groups, control, diabetic (DM), DM + swimming, DM + dapagliflozin, and DM + dapagliflozin and swimming. Serum glucose, insulin, insulin resistance (HOMA-IR), and cardiac enzymes (CK-MB and lactate dehydrogenase (LDH) are measured. Heart specimens are used for evaluation of cellular oxidative stress markers malondialdehyde (MDA), antioxidant enzymes, glutathione (GSH), and catalase (CAT), as well as mRNA expression of TGF-β, MMP9, IL-1β, and TNF-α. Stained sections with haematoxylin and eosin (H & E) and Masson trichrome are used for histopathological evaluation and detection of fibrosis, respectively. Immunohistochemical staining for apoptosis (caspase-3), and autophagy (LC3) are also carried out. The combinations of SGLT2i and exercise exhibited the most significant cardioprotective effect. It improved diabetic-induced histopathological alterations in the myocardium and attenuated the elevation of serum blood glucose, CK-MB, LDH, myocardial MDA, and mRNA expression of TNF-α, IL-1β, TGF-β, MMP9, and the immune expression of caspase-3. Moreover, this combination increased the serum insulin, myocardial antioxidants GSH and CAT, and increase the immune expression of the LC-3. In conclusion, a combination of SGLT2i and exercise exerted a better antioxidant, anti-inflammatory, and antifibrotic effect in DCM. Moreover, the combination enhances the autophagic capacity of the heart.

Mitochondria-Mediated Cardiovascular Benefits of Sodium-Glucose Co-Transporter 2 Inhibitors

Several recent cardiovascular trials of SGLT 2 (sodium-glucose cotransporter 2) inhibitors revealed that they could reduce adverse cardiovascular events in patients with T2DM (type 2 diabetes mellitus). However, the exact molecular mechanism underlying the beneficial effects that SGLT2 inhibitors have on the cardiovascular system is still unknown. In this review, we focus on the molecular mechanisms of the mitochondria-mediated beneficial effects of SGLT2 inhibitors on the cardiovascular system. The application of SGLT2 inhibitors ameliorates mitochondrial dysfunction, dynamics, bioenergetics, and ion homeostasis and reduces the production of mitochondrial reactive oxygen species, which results in cardioprotective effects. Herein, we present a comprehensive overview of the impact of SGLT2 inhibitors on mitochondria and highlight the potential application of these medications to treat both T2DM and cardiovascular diseases.

Bimodal Effects of P2Y12 Antagonism on Matrix Metalloproteinase-Associated Contractile Dysfunction in İnsulin-Resistant Mammalian Heart

The matrix metalloproteinases (MMPs) contribute to matrix remodeling in diabetes via tissue degradation; however, their contributions can be different depending on the pathology. For instance, MMPs are elevated in acute stress hyperglycemia, whereas they can be degraded in chronic hyperglycemia. Since studies emphasize the possible cardioprotective effect of ticagrelor (Tica) beyond its antiplatelet action, we aimed to examine whether Tica treatment can reverse the depressed heart function of metabolic syndrome (MetS) rats via affecting the expression levels of MMPs. Tica treatment of high-carbohydrate-induced MetS rats could not affect significantly the depressed contractile activity of Langendorff-perfused heart preparations. On the other hand, the Tica treatment provided a significant recovery in the reduced relaxation activity of the aortic preparations from the same animals. Histological examination of the hearts demonstrated marked damages in Mets rats, such as increases in the number of foamy cells and accumulation of collagen fiber and increases in the elastic lamellar irregularity of tunica media, while Tica treatment provided a slight improvement in the structure of left ventricle tissue. We also could not obtain a significant reverse in the high cytosolic labile Zn²⁺ ([Zn²⁺]_i) with the treatment of cardiomyocytes with Tica. Furthermore, Tica treatment of MetS rats could not significantly reverse the degraded protein levels of MMP-2 and MMP-9 in the heart, as well. Overall, we demonstrated that Tica treatment of MetS rats has no significant benefits on the depressed heart function, although provide a significant beneficial impact on vascular relaxation. This action of Tica may be through its lack of action on both MMP degradation and high [Zn²⁺]_i, which can further precipitate in cleavage of extracellular matrix in the heart.

Pathophysiological aspects of insulin resistance in Atrial Fibrillation: novel therapeutic approaches

Background

Insulin resistance is associated with metabolic disorders including diabetes, obesity, hypertension, and inflammation which are the risk factors for Atrial Fibrillation. Many studies have reported that type 2 diabetes and AF are related and also their prevalence is increasing globally. Moreover, insulin resistance begins the type 2 diabetes.

Main body

This review explains the pathophysiological aspects of insulin resistance in AF patients and discusses the drugs that are used to manage insulin resistance including Biguanides (metformin), thiazolidinediones (TZDs) [Pioglitazone, rosiglitazone], Sodium-glucose cotransporter 2 (SGLT2) inhibitors, Concentrated Insulin Products, Dipeptidyl peptidase-4 (DPP-4) Inhibitors, Glucagon-like peptide 1 (GLP-1) receptor Agonists, Pramlintide, Sulfonylureas, Meglitinides, α-Glucosidase Inhibitors, Colesevelam, Bromocriptine. This review will highlight a few major drugs that played a significant role in AF patients. For this purpose, many databases were used for reviewing the literature and keywords are used such as Insulin Resistance, Pathophysiology, Atrial Fibrillation, and Drugs.

Conclusion

This review article concludes that insulin resistance is related to AF. It also provides an outlook on the recent pathophysiological aspects of insulin resistance in AF; however, more studies are needed to clarify the management of insulin resistance in AF patients to prevent the development of type 2 diabetes.

Dapagliflozin Alleviates Renal Fibrosis by Inhibiting RIP1-RIP3-MLKL-Mediated Necroinflammation in Unilateral Ureteral Obstruction

Dapagliflozin, a sodium-glucose cotransporter-2 inhibitor, offers renoprotection in diabetes. However, potential for use in nondiabetic kidney disease remains unknown. Herein, we assessed whether dapagliflozin alleviates renal fibrosis by interfering with necroinflammation in a rat model of unilateral ureteral obstruction (UUO) and in vitro. After induction of UUO, rats were administered dapagliflozin daily for seven consecutive days. UUO induced significant renal tubular necrosis and overexpression of RIP1-RIP3-MLKL axis proteins; these coincided with NLRP3 inflammasome activation, and subsequent development of renal fibrosis. Oxidative stress caused by UUO is tightly associated with endoplasmic reticulum stress and mitochondrial dysfunction, leading to apoptotic cell death through Wnt3α/β-catenin/GSK-3β signaling; all of which were abolished by both dapagliflozin and specific RIP inhibitors (necrostatin-1 and GSK872). In H₂O₂-treated HK-2 cells, dapagliflozin and RIP inhibitors suppressed overexpression of RIP1-RIP3-MLKL proteins and pyroptosis-related cytokines, decreased intracellular reactive oxygen species production and apoptotic cell death, whereas cell viability was improved. Moreover, activated Wnt3α/β-catenin/GSK-3β signaling was inhibited by dapagliflozin and Wnt/β-catenin inhibitor ICG-001. Our findings suggest that dapagliflozin ameliorates renal fibrosis by inhibiting RIP1-RIP3-MLKL-mediated necroinflammation via Wnt3α/β-catenin/GSK-3β signaling in UUO.

Dapagliflozin improves steatohepatitis in diabetic rats via inhibition of oxidative stress and inflammation

Type-2 diabetes mellitus and NAFLD are considered as one of the greatest worldwide metabolic disorders with growing incidence. It was found that patients with T2DM have two-fold increase to develop NAFLD. Evidence that some antidiabetic agents improve NAFLD/NASH in patients with T2DM is evolving. However, there are no certain pharmacologic therapies. The current study aimed to investigate the underlying mechanisms for the hepatoprotective effect of dapagliflozin against steatohepatitis in diabetic rats. Type-2 diabetes was induced by HFD followed by a single dose of STZ (30 mg/kg I.P). Fifty rats were randomly divided into 5 groups: Group1; normal control, Group 2; diabetic control, Groups (3-5); diabetic rats received daily dapagliflozin (0.75, 1.5, 3 mg/kg, p.o.) respectively for 6 weeks. At the end of the experiment, blood glucose level and serum insulin were measured. Hepatic tissue homogenization was performed for measuring inflammatory and oxidative stress markers. In addition, histopathological investigation of the hepatic tissue was done. Diabetic rats exhibited remarkable increase in liver weight and liver enzymes, along with histopathological changes, significant elevation in MDA, IL-1 β, TGFβ levels and, NF-κB, alpha-SMA expressions. Dapagliflozin treatment decreased liver weight, liver enzymes, together with marked improvement in histopathological changes. Furthermore, dapagliflozin increased antioxidant enzymes, GSH levels. Interestingly, Dapagliflozin reduced IL-1 β, TGFβ levels and, NF-κB, alpha-SMA expressions. Present data show that dapagliflozin represent a viable approach to protect the liver against diabetes-encouraged steatohepatitis through inhibiting oxidative stress, inflammation and fibrosis progression thus conserving liver function.

Zinc

Since the discovery of manifest Zn deficiency in 1961, the increasing number of studies demonstrated the association between altered Zn status and multiple diseases. In this chapter, we provide a review of the most recent advances on the role of Zn in health and disease (2010-20), with a special focus on the role of Zn in neurodegenerative and neurodevelopmental disorders, diabetes and obesity, male and female reproduction, as well as COVID-19. In parallel with the revealed tight association between ASD risk and severity and Zn status, the particular mechanisms linking Zn2+ and ASD pathogenesis like modulation of synaptic plasticity through ProSAP/Shank scaffold, neurotransmitter metabolism, and gut microbiota, have been elucidated. The increasing body of data indicate the potential involvement of Zn2+ metabolism in neurodegeneration. Systemic Zn levels in Alzheimer's and Parkinson's disease were found to be reduced, whereas its sequestration in brain may result in modulation of amyloid β and α-synuclein processing with subsequent toxic effects. Zn2+ was shown to possess adipotropic effects through the role of zinc transporters, zinc finger proteins, and Zn-α2-glycoprotein in adipose tissue physiology, underlying its particular role in pathogenesis of obesity and diabetes mellitus type 2. Recent findings also contribute to further understanding of the role of Zn2+ in spermatogenesis and sperm functioning, as well as oocyte development and fertilization. Finally, Zn2+ was shown to be the potential adjuvant therapy in management of novel coronavirus infection (COVID-19), underlining the perspectives of zinc in management of old and new threats.

Diagnostic Criteria for Metabolic Syndrome in Diet-Induced Rodent Models: A Systematic Review

BACKGROUND

Thousands of publications in recent years have addressed the induction of metabolic syndrome (MetS) in rodents. However, the criteria and the reference values for diagnosing this disease have not been defined.

OBJECTIVE

Our main objective was to carry out a systematic review to gather evidence about the criteria for biochemical and anthropometric parameters in which scientific studies have relied on to report that rats developed MetS from a previous dietary manipulation.

METHODS

We compiled characteristics and findings of diet-induced MetS with high-fat, high-carbohydrate, high-fat/high-carbohydrates, and cafeteria diet from PubMed and Science Direct databases published in the last 5 years.

RESULTS

The results on the principal determinants for the syndrome, published in the reviewed articles, were chosen to propose reference values in the rat models of food induction.

CONCLUSION

The values obtained will serve as reference cut-of points in the development of the disease; in addition, the compilation of data will be useful in planning and executing research protocols in animal models.

Protective Effects of Sodium-Glucose Transporter 2 Inhibitors on Atrial Fibrillation and Atrial Flutter: A Systematic Review and Meta- Analysis of Randomized Placebo-Controlled Trials

BACKGROUND

Hyperglycemia is associated with an increased risk of developing atrial fibrillation (AF) and atrial flutter (AFL). Sodium-glucose transporter 2 inhibitors (SGLT2i) have been reported to prevent AF/AFL in some studies, but not others. Therefore, a meta-analysis was performed to investigate whether SGLT2i use is associated with lower risks of AF/AFL.

METHODS

PubMed, Scopus, Web of Science, Cochrane library databases were searched for randomized placebo-controlled trials comparing SGLT2i and placebo.

RESULTS

A total of 33 trials involving 66,685 patients were included. The serious adverse events (SAEs) of AF/AFL occurrence were significantly lower in the SGLT2i group than the placebo group (0.96% vs. 1.19%; RR 0.83; 95% CI 0.71-0.96; P = 0.01; I² 25.5%). Similarly, the SAEs of AF occurrence was significantly lower in the SGLT2i group (0.82% vs. 1.06%; RR 0.81; 95% CI 0.69-0.95; P = 0.01; I² 10.2%). The subgroup analysis showed that the reduction in AF/AFL was significant only for dapagliflozin (1.02% vs. 1.49%; RR 0.73; 95% CI 0.59-0.89; P = 0.002; I2 0%), but not for canagliflozin (1.00% vs 1.08%; RR 0.83; 95% CI 0.62-1.12; P = 0.23; I² 0%), empagliflozin (0.88% vs 0.70%; RR 1.20; 95% CI 0.76-1.90; P = 0.43; I² 0%), ertugliflozin (1.01% vs 0.96%; RR 1.08; 95% CI 0.66-1.75; P = 0.76; I² 0%), and sotagliflozin (0.16% vs 0.10%; RR 1.09; 95% CI 0.13-8.86; P = 0.93; I² 0%).

CONCLUSIONS

SGLT2i use is associated with a 19.33% lower SAEs of AF/AFL compared with the placebo. Dapagliflozin users had the lowest SAEs of AF/AFL incidence. Further studies are needed to determine whether canagliflozin, empagliflozin, ertugliflozin, and sotagliflozin similarly exert protective effects against AF/AFL development.

The role of labile Zn2+ and Zn2+-transporters in the pathophysiology of mitochondria dysfunction in cardiomyocytes

An important energy supplier of cardiomyocytes is mitochondria, similar to other mammalian cells. Studies have demonstrated that any defect in the normal processes controlled by mitochondria can lead to abnormal ROS production, thereby high oxidative stress as well as lack of ATP. Taken into consideration, the relationship between mitochondrial dysfunction and overproduction of ROS as well as the relation between increased ROS and high-level release of intracellular labile Zn²⁺, those bring into consideration the importance of the events related with those stimuli in cardiomyocytes responsible from cellular Zn²⁺-homeostasis and responsible Zn²⁺-transporters associated with the Zn²⁺-homeostasis and Zn²⁺-signaling. Zn²⁺-signaling, controlled by cellular Zn²⁺-homeostatic mechanisms, is regulated with intracellular labile Zn²⁺ levels, which are controlled, especially, with the two Zn²⁺-transporter families; ZIPs and ZnTs. Our experimental studies in mammalian cardiomyocytes and human heart tissue showed that Zn²⁺-transporters localizes to mitochondria besides sarco(endo)plasmic reticulum and Golgi under physiological condition. The protein levels as well as functions of those transporters can re-distribute under pathological conditions, therefore, they can interplay among organelles in cardiomyocytes to adjust a proper intracellular labile Zn²⁺ level. In the present review, we aimed to summarize the already known Zn²⁺-transporters localize to mitochondria and function to stabilize not only the cellular Zn²⁺ level but also cellular oxidative stress status. In conclusion, one can propose that a detailed understanding of cellular Zn²⁺-homeostasis and Zn²⁺-signaling through mitochondria may emphasize the importance of new mitochondria-targeting agents for prevention and/or therapy of cardiovascular dysfunction in humans.

SGLT2 Inhibitors: A Novel Player in the Treatment and Prevention of Diabetic Cardiomyopathy

Diabetic cardiomyopathy (DCM) characterized by diastolic and systolic dysfunction independently of hypertension and coronary heart disease, eventually develops into heart failure, which is strongly linked to a high prevalence of mortality in people with diabetes mellitus (DM). Sodium-glucose cotransporter type2 inhibitors (SGLT2Is) are a novel type of hypoglycemic agent in increasing urinary glucose and sodium excretion. Excitingly, the EMPA-REG clinical trial proved that empagliflozin significantly reduced the relative risk of cardiovascular (CV) death and hospitalization for heart failure (HHF) in patients with type 2 DM (T2DM) plus CV disease (CVD). The EMPRISE trial showed that empagliflozin decreased the risk of HHF in T2DM patients with and without a CVD history in routine care. These beneficial effects of SGLT2Is could not be entirely attributed to glucose-lowering or natriuretic action. There could be potential direct mechanisms of SGLT2Is in cardioprotection. Recent studies have shown the effects of SGLT2Is on cardiac iron homeostasis, mitochondrial function, anti-inflammation, anti-fibrosis, antioxidative stress, and renin-angiotensin-aldosterone system activity, as well as GlcNAcylation in the heart. This article reviews the current literature on the effects of SGLT2Is on DCM in preclinical studies. Possible molecular mechanisms regarding potential benefits of SGLT2Is for DCM are highlighted, with the purpose of providing a novel strategy for preventing DCM.

Tropisetron improves pancreas function and increases insulin synthesis and secretion in the STZ-induced diabetic rats: involvement of UCP2/ZnT8 pathway

OBJECTIVES

Diabetes mellitus is one of the most common metabolic diseases. Tropisetron, as a 5-HT3 receptor antagonist, has a considerable role in the inflammation and oxidative stress lowering. This study aimed to investigate the effect of this 5-HT3 receptor antagonist on insulin secretion in male diabetic rats and the possible mechanisms.

METHODS

Animals were divided into five equal groups; the control, tropisetron, diabetes, tropisetron-diabetes and glibenclamide-diabetes (7 in each group). Tropisetron and glibenclamide were administrated for 2 weeks after inducing type 1 diabetes.

KEY FINDINGS

We demonstrated that insulin secretion improved robustly in diabetes-tropisetron compared with the diabetic group. Oxidative stress biomarkers were lower in a diabetes-tropisetron group than in diabetic rats. Simultaneously, tropisetron administration promoted the expression of ZnT8 and GLUT2 and also beta-cell mass in pancreatic tissue, while the expression of uncoupling protein 2 (UCP2) was restrained. The histological evaluation confirmed our results. These effects were equipotent with glibenclamide, indicating that tropisetron can protect islets from the abnormal insulin secretion and morphological changes induced by type 1 diabetes.

CONCLUSIONS

This effect might be partly related to the modulated UCP2/ZnT8 signal pathway and improved oxidative stress-induced damage.

Comparative Study of the Effects of GLP1 Analog and SGLT2 Inhibitor against Diabetic Cardiomyopathy in Type 2 Diabetic Rats: Possible Underlying Mechanisms

The present study investigated the possible cardioprotective effects of GLP1 and SGLT2i against diabetic cardiomyopathy (DCM) in type 2 diabetic rats and the possible underlying mechanisms.

METHODS

Thirty-two male Sprague Dawley rats were randomly subdivided into 4 equal groups: a) control group, b) DM group, type 2 diabetic rats with saline daily for 4 weeks, c) DM+ GLP1, as DM group with GLP1 analogue (liraglutide) at a dose of 75 µg/kg for 4 weeks, and d) DM+ SGLT2i as DM group with SGLT2 inhibitor (dapagliflozin) at a dose of 1mg/kg for 4 weeks. By the end of treatment (4 weeks), serum blood glucose, homeostasis model assessment insulin resistance (HOMA-IR), insulin, and cardiac enzymes (LDH, CK-MB) were measured. Also, the cardiac histopathology, myocardial oxidative stress markers (malondialdehyde (MDA), glutathione (GSH) and CAT) and norepinephrine (NE), myocardial fibrosis, the expression of caspase-3, TGF-β, TNF-α, and tyrosine hydroxylase (TH) in myocardial tissues were measured.

RESULTS

T2DM caused significant increase in serum glucose, HOMA-IR, serum CK-MB, and LDH (p < 0.05). Also, DM caused significant myocardial damage and fibrosis; elevation of myocardial MDA; NE with upregulation of myocardial caspase-3, TNF-α, TGF-β, and TH; and significant decrease in serum insulin and myocardial GSH and CAT (p < 0.05). Administration of either GLP1 analog or SGLT2i caused a significant improvement in all studied parameters (p < 0.05).

CONCLUSION

We concluded that both GLP1 and SGLT2i exhibited cardioprotective effects against DCM in T2DM, with the upper hand for SGLT2i. This might be due to attenuation of fibrosis, oxidative stress, apoptosis (caspase-3), sympathetic nerve activity, and inflammatory cytokines (TNF-α and TGF-β).

Sodium-glucose cotransporter 2 inhibitor Dapagliflozin attenuates diabetic cardiomyopathy

Background

Diabetes mellitus type 2 (DM2) is a risk factor for developing heart failure but there is no specific therapy for diabetic heart disease. Sodium glucose transporter 2 inhibitors (SGLT2I) are recently developed diabetic drugs that primarily work on the kidney. Clinical data describing the cardiovascular benefits of SGLT2Is highlight the potential therapeutic benefit of these drugs in the prevention of cardiovascular events and heart failure. However, the underlying mechanism of protection remains unclear. We investigated the effect of Dapagliflozin—SGLT2I, on diabetic cardiomyopathy in a mouse model of DM2.

Methods

Cardiomyopathy was induced in diabetic mice (db/db) by subcutaneous infusion of angiotensin II (ATII) for 30 days using an osmotic pump. Dapagliflozin (1.5 mg/kg/day) was administered concomitantly in drinking water. Male homozygous, 12–14 weeks old WT or db/db mice (n = 4–8/group), were used for the experiments. Isolated cardiomyocytes were exposed to glucose (17.5–33 mM) and treated with Dapagliflozin in vitro. Intracellular calcium transients were measured using a fluorescent indicator indo-1.

Results

Angiotensin II infusion induced cardiomyopathy in db/db mice, manifested by cardiac hypertrophy, myocardial fibrosis and inflammation (TNFα, TLR4). Dapagliflozin decreased blood glucose (874 ± 111 to 556 ± 57 mg/dl, p < 0.05). In addition it attenuated fibrosis and inflammation and increased the left ventricular fractional shortening in ATII treated db/db mice. In isolated cardiomyocytes Dapagliflozin decreased intracellular calcium transients, inflammation and ROS production. Finally, voltage-dependent L-type calcium channel (CACNA1C), the sodium–calcium exchanger (NCX) and the sodium–hydrogen exchanger 1 (NHE) membrane transporters expression was reduced following Dapagliflozin treatment.

Conclusion

Dapagliflozin was cardioprotective in ATII-stressed diabetic mice. It reduced oxygen radicals, as well the activity of membrane channels related to calcium transport. The cardioprotective effect manifested by decreased fibrosis, reduced inflammation and improved systolic function. The clinical implication of our results suggest a novel pharmacologic approach for the treatment of diabetic cardiomyopathy through modulation of ion homeostasis.

Empagliflozin, a sodium glucose co-transporter-2 inhibitor, alleviates atrial remodeling and improves mitochondrial function in high-fat diet/streptozotocin-induced diabetic rats

Background

Diabetes mellitus is an important risk factor for atrial fibrillation (AF) development. Sodium–glucose co-transporter-2 (SGLT-2) inhibitors are used for the treatment of type 2 diabetes mellitus (T2DM). Their cardioprotective effects have been reported but whether they prevent AF in T2DM patients are less well-explored. We tested the hypothesis that the SGLT-2 inhibitor, empagliflozin, can prevent atrial remodeling in a diabetic rat model.

Methods

High-fat diet and low-dose streptozotocin (STZ) treatment were used to induce T2DM. A total of 96 rats were randomized into the following four groups: (i) control (ii) T2DM, (iii) low-dose empagliflozin (10 mg/kg/day)/T2DM; and (iv) high-dose empagliflozin (30 mg/kg/day)/T2DM by the intragastric route for 8 weeks.

Results

Compared with the control group, left atrial diameter, interstitial fibrosis and the incidence of AF inducibility were significantly increased in the DM group. Moreover, atrial mitochondrial respiratory function, mitochondrial membrane potential, and mitochondrial biogenesis were impaired. Empagliflozin treatment significantly prevented the development of these abnormalities in DM rats, likely via the peroxisome proliferator-activated receptor-c coactivator 1α (PGC-1α)/nuclear respiratory factor-1 (NRF-1)/mitochondrial transcription factor A (Tfam) signaling pathway.

Conclusions

Empagliflozin can ameliorate atrial structural and electrical remodeling as well as improve mitochondrial function and mitochondrial biogenesis in T2DM, hence may be potentially used in the prevention of T2DM-related atrial fibrillation.

SGLT2 inhibition with empagliflozin attenuates myocardial oxidative stress and fibrosis in diabetic mice heart

Background

Hyperglycaemia associated with myocardial oxidative stress and fibrosis is the main cause of diabetic cardiomyopathy. Empagliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor has recently been reported to improve glycaemic control in patients with type 2 diabetes in an insulin-independent manner. The aim of this study was to investigate the effect of empagliflozin on myocardium injury and the potential mechanism in type 2 diabetic KK-Ay mice.

Methods

Thirty diabetic KK-Ay mice were administered empagliflozin (10 mg/kg/day) by oral gavage daily for 8 weeks. After 8 weeks, heart structure and function were evaluated by echocardiography. Oxidants and antioxidants were measured and cardiac fibrosis was analysed using immunohistochemistry, Masson’s trichrome stain and Western blot.

Results

Results showed that empagliflozin improved diabetic myocardial structure and function, decreased myocardial oxidative stress and ameliorated myocardial fibrosis. Further study indicated that empagliflozin suppressed oxidative stress and fibrosis through inhibition of the transforming growth factor β/Smad pathway and activation of Nrf2/ARE signaling.

Conclusions

Glycaemic control with empagliflozin significantly ameliorated myocardial oxidative stress injury and cardiac fibrosis in diabetic mice. Taken together, these results indicate that the empagliflozin is a promising agent for the prevention and treatment of diabetic cardiomyopathy.