The SGLT2 inhibitor empagliflozin improves the primary diabetic complications in ZDF rats

SGLT-2 Inhibitors and Peripheral Artery Disease: A Statistical Hoax or Reality?

Inhibitors of sodium-glucose cotransporters type-2 are the most recent addition to the armamentarium of oral antidiabetic agents. This class of drugs has shown promising results in glycemic control and most importantly to reduce cardiovascular disease (CVD) mortality risk. Despite the encouraging data, there is concern regarding their potential for causing or worsening peripheral artery disease (PAD), which may increase the risk of lower extremity amputations. Following the publication of results of CANVAS and CANVAS-R trials, which revealed that leg and mid-foot amputations occurred about twice as often in patients treated with canagliflozin compared to placebo, the Food and Drug Administration (FDA) in the United States issued a black box warning of leg and foot amputations associated with canagliflozin use. In this article, our main aim is to review the available evidence in preclinical and clinical studies regarding SGLT-2 inhibitors and PAD events, the possible mechanisms related to increased risk of amputation, to evaluate whether it is a class effect or individual drug effect, and most importantly, implications for their continued use as antidiabetic agents. It also raises the issue of including PAD events among the end-points when assessing future antihyperglycemic agents. Thus, we also tried to analyze whether outcomes of SGLT2 inhibitors trials mostly focused on stroke, myocardial infarction, heart failure, and peripheral vascular disease-related outcomes remained underrated.

Molecular Mechanisms Underlying the Cardiovascular Benefits of SGLT2i and GLP-1RA

PURPOSE OF REVIEW

In addition to their effects on glycemic control, two specific classes of relatively new anti-diabetic drugs, namely the sodium glucose co-transporter-2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP-1RA) have demonstrated reduced rates of major adverse cardiovascular events (MACE) in subjects with type 2 diabetes (T2D) at high risk for cardiovascular disease (CVD). This review summarizes recent experimental results that inform putative molecular mechanisms underlying these benefits.

RECENT FINDINGS

SGLT2i and GLP-1RA exert cardiovascular effects by targeting in both common and distinctive ways (A) several mediators of macro- and microvascular pathophysiology: namely (A1) inflammation and atherogenesis, (A2) oxidative stress-induced endothelial dysfunction, (A3) vascular smooth muscle cell reactive oxygen species (ROS) production and proliferation, and (A4) thrombosis. These agents also exhibit (B) hemodynamic effects through modulation of (B1) natriuresis/diuresis and (B2) the renin-angiotensin-aldosterone system. This review highlights that while GLP-1RA exert direct effects on vascular (endothelial and smooth muscle) cells, the effects of SGLT2i appear to include the activation of signaling pathways that prevent adverse vascular remodeling. Both SGLT2i and GLP-1RA confer hemodynamic effects that counter adverse cardiac remodeling.

Empagliflozin rescues diabetic myocardial microvascular injury via AMPK-mediated inhibition of mitochondrial fission

Impaired cardiac microvascular function contributes to diabetic cardiovascular complications although effective therapy remains elusive. Empagliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor recently approved for treatment of type 2 diabetes, promotes glycosuria excretion and offers cardioprotective actions beyond its glucose-lowering effects. This study was designed to evaluate the effect of empagliflozin on cardiac microvascular injury in diabetes and the underlying mechanism involved with a focus on mitochondria. Our data revealed that empagliflozin improved diabetic myocardial structure and function, preserved cardiac microvascular barrier function and integrity, sustained eNOS phosphorylation and endothelium-dependent relaxation, as well as improved microvessel density and perfusion. Further study suggested that empagliflozin exerted its effects through inhibition of mitochondrial fission in an adenosine monophosphate (AMP)-activated protein kinase (AMPK)-dependent manner. Empagliflozin restored AMP-to-ATP ratio to trigger AMPK activation, suppressed Drp1S616 phosphorylation, and increased Drp1S637 phosphorylation, ultimately leading to inhibition of mitochondrial fission. The empagliflozin-induced inhibition of mitochondrial fission preserved cardiac microvascular endothelial cell (CMEC) barrier function through suppressed mitochondrial reactive oxygen species (mtROS) production and subsequently oxidative stress to impede CMEC senescence. Empagliflozin-induced fission loss also favored angiogenesis by promoting CMEC migration through amelioration of F-actin depolymerization. Taken together, these results indicated the therapeutic promises of empagliflozin in the treatment of pathological microvascular changes in diabetes.

Diabetes, Hypertension, and Cardiovascular Disease: Clinical Insights and Vascular Mechanisms

Hypertension and type 2 diabetes are common comorbidities. Hypertension is twice as frequent in patients with diabetes compared with those who do not have diabetes. Moreover, patients with hypertension often exhibit insulin resistance and are at greater risk of diabetes developing than are normotensive individuals. The major cause of morbidity and mortality in diabetes is cardiovascular disease, which is exacerbated by hypertension. Accordingly, diabetes and hypertension are closely interlinked because of similar risk factors, such as endothelial dysfunction, vascular inflammation, arterial remodelling, atherosclerosis, dyslipidemia, and obesity. There is also substantial overlap in the cardiovascular complications of diabetes and hypertension related primarily to microvascular and macrovascular disease. Common mechanisms, such as upregulation of the renin-angiotensin-aldosterone system, oxidative stress, inflammation, and activation of the immune system likely contribute to the close relationship between diabetes and hypertension. In this article we discuss diabetes and hypertension as comorbidities and discuss the pathophysiological features of vascular complications associated with these conditions. We also highlight some vascular mechanisms that predispose to both conditions, focusing on advanced glycation end products, oxidative stress, inflammation, the immune system, and microRNAs. Finally, we provide some insights into current therapies targeting diabetes and cardiovascular complications and introduce some new agents that may have vasoprotective therapeutic potential in diabetes.

Protective role of melatonin in cardiac ischemia-reperfusion injury: From pathogenesis to targeted therapy

Acute myocardial infarction (MI) is a major cause of mortality and disability worldwide. In patients with MI, the treatment option for reducing acute myocardial ischemic injury and limiting MI size is timely and effective myocardial reperfusion using either thombolytic therapy or primary percutaneous coronary intervention (PCI). However, the procedure of reperfusion itself induces cardiomyocyte death, known as myocardial reperfusion injury, for which there is still no effective therapy. Recent evidence has depicted a promising role of melatonin, which possesses powerful antioxidative and anti-inflammatory properties, in the prevention of ischemia-reperfusion (IR) injury and the protection against cardiomyocyte death. A number of reports explored the mechanism of action behind melatonin-induced beneficial effects against myocardial IR injury. In this review, we summarize the research progress related to IR injury and discuss the unique actions of melatonin as a protective agent. Furthermore, the possible mechanisms responsible for the myocardial benefits of melatonin against reperfusion injury are listed with the prospect of the use of melatonin in clinical application.

Canagliflozin inhibits interleukin-1β-stimulated cytokine and chemokine secretion in vascular endothelial cells by AMP-activated protein kinase-dependent and -independent mechanisms

Recent clinical trials of the hypoglycaemic sodium-glucose co-transporter-2 (SGLT2) inhibitors, which inhibit renal glucose reabsorption, have reported beneficial cardiovascular outcomes. Whether SGLT2 inhibitors directly affect cardiovascular tissues, however, remains unclear. We have previously reported that the SGLT2 inhibitor canagliflozin activates AMP-activated protein kinase (AMPK) in immortalised cell lines and murine hepatocytes. As AMPK has anti-inflammatory actions in vascular cells, we examined whether SGLT2 inhibitors attenuated inflammatory signalling in cultured human endothelial cells. Incubation with clinically-relevant concentrations of canagliflozin, but not empagliflozin or dapagliflozin activated AMPK and inhibited IL-1β-stimulated adhesion of pro-monocytic U937 cells and secretion of IL-6 and monocyte chemoattractant protein-1 (MCP-1). Inhibition of MCP-1 secretion was attenuated by expression of dominant-negative AMPK and was mimicked by the direct AMPK activator, A769662. Stimulation of cells with either canagliflozin or A769662 had no effect on IL-1β-stimulated cell surface levels of adhesion molecules or nuclear factor-κB signalling. Despite these identical effects of canagliflozin and A769662, IL-1β-stimulated IL-6/MCP-1 mRNA was inhibited by canagliflozin, but not A769662, whereas IL-1β-stimulated c-jun N-terminal kinase phosphorylation was inhibited by A769662, but not canagliflozin. These data indicate that clinically-relevant canagliflozin concentrations directly inhibit endothelial pro-inflammatory chemokine/cytokine secretion by AMPK-dependent and -independent mechanisms without affecting early IL-1β signalling.

Anti-inflammatory effects of empagliflozin in patients with type 2 diabetes and insulin resistance

BACKGROUND

Inflammation might be a pathological mediator of cardiovascular events in patients with type 2 diabetes and high cardiovascular risk.

METHODS

We investigated whether empagliflozin (EMPA) exerts anti-inflammatory effects that are reflected in decreased high-sensitivity C-reactive protein (hsCRP) values. Patients were allocated to receive a placebo (n = 51) or EMPA (n = 51) as an add-on treatment. Fasting blood samples were collected before and every 3 months after this intervention for 1 year.

RESULTS

Empagliflozin tended to elicit reductions in BMI, HbA1c, aspartate aminotransferase, alanine aminotransferase (ALT), and gamma-glutamyl transpeptidase compared with the placebo, but the differences did not reach statistical significance. Levels of LDL-cholesterol, HDL-cholesterol, and triglycerides were unaltered, significantly increased, and decreased, respectively, by EMPA, but the differences were not statistically significant compared with the placebo. Empagliflozin for 12 months notably reduced the homeostatic model assessment of insulin resistance (HOMA-IR), remnant-like particle cholesterol (RLP-C), and hsCRP by 43%, 52% and 54%, respectively. The time courses of these reductions significantly differed from those of the placebo. Systolic and diastolic blood pressure were also significantly reduced by EMPA compared with the placebo. We applied multiple linear regression analysis to determine which factors were associated with changes in hsCRP induced by EMPA. The results revealed that alterations in hsCRP values (log [hsCRP at 12 months] minus log [hsCRP at month 0]) were significantly associated with changes in HOMA-IR, RLP-C, systolic blood pressure, HDL-C and ALT.

CONCLUSION

Empagliflozin decreased hs-CRP and lowered levels of remnant related lipoproteins probably via ameliorating insulin resistance. The cardiovascular benefits conferred by EMPA might be driven at least partly by anti-inflammatory effects, and this mechanism might cooperate with other EMPA-induced changes including reduced blood pressure, to achieve the degree of cardioprotection revealed by the EMPA-REG OUTCOME trial.Trial registration UMIN Clinical Registry (UMIN000021552). Registered 21 March 2016, https://upload.umin.ac.jp/UMIN000021552.

Potent Oral Hypoglycemic Agents for Microvascular Complication: Sodium-Glucose Cotransporter 2 Inhibitors for Diabetic Retinopathy

The purpose of this study was to investigate the effects of sodium-glucose cotransporter 2 inhibitors (SGLT2i) on the progression of diabetic retinopathy (DR) in patients with type 2 diabetes. The medical records of 21 type 2 diabetic patients who used a SGLT2i and 71 patients with sulfonylurea (control) were reviewed retrospectively. The severity of DR was assessed using the Early Treatment Diabetic Retinopathy Study (ETDRS) scale. Fewer patients who used a SGLT2i than control patients with sulfonylurea showed progression of DR based on ETDRS scale (44% versus 14%, P = 0.014). Moreover, treatment with a SGLT2i was associated with a significantly lower risk of DR progression (P = 0.021), and this effect remained significant after adjusting for the age, duration of diabetes, initial DR grade, and HbA1c level by propensity score matching (P = 0.013). Treatment of type 2 diabetic patients with a SGLT2i slowed the progression of DR compared to sulfonylurea, which is independent of its effect on glycemic control. This study provides a foundation for further evaluation of the effect of SGLT2i on the progression of DR.

Empagliflozin Limits Myocardial Infarction in Vivo and Cell Death in Vitro: Role of STAT3, Mitochondria, and Redox Aspects

Empagliflozin (EMPA), a drug approved for type 2 diabetes management, reduced cardiovascular death but is unknown if it reduces myocardial infarction. We sought to investigate: (i) the effect of EMPA on myocardial function and infarct size after ischemia/reperfusion in mice fed with western diet (WD), (ii) the underlying signaling pathways, (iii) its effects on cell survival in rat embryonic-heart-derived cardiomyoblasts (H9C2) and endothelial cells (ECs). To facilitate the aforementioned aims, mice were initially randomized in Control and EMPA groups and were subjected to 30 min ischemia and 2 h reperfusion. EMPA reduced body weight, blood glucose levels, and mean arterial pressure. Cholesterol, triglyceride, and AGEs remained unchanged. Left ventricular fractional shortening was improved (43.97 ± 0.92 vs. 40.75 ± 0.61%) and infarct size reduced (33.2 ± 0.01 vs. 17.6 ± 0.02%). In a second series of experiments, mice were subjected to the above interventions up to the 10th min of reperfusion and myocardial biopsies were obtained for assessment of the signaling cascade. STAT3 was increased in parallel with reduced levels of malondialdehyde (MDA) and reduced expression of myocardial iNOS and interleukin-6. Cell viability and ATP content were increased in H9C2 and in ECs. While, STAT3 phosphorylation is known to bestow infarct sparing properties through interaction with mitochondria, we observed that EMPA did not directly alter the mitochondrial calcium retention capacity (CRC); therefore, its effect in reducing myocardial infarction is STAT3 dependent. In conclusion, EMPA improves myocardial function and reduces infarct size as well as improves redox regulation by decreasing iNOS expression and subsequently lipid peroxidation as shown by its surrogate marker MDA. The mechanisms of action implicate the activation of STAT3 anti-oxidant and anti-inflammatory properties.

[Empagliflozin alleviates cardiac microvascular ischemia/reperfusion injury by maintaining myocardial mitochondrial homeostasis]

OBJECTIVE

To evaluate the effect of empagliflozin (EMPA) in mitigating microvascular and endothelial damage induced by myocardial ischemia-reperfusion (I/R) injury.

METHODS

Fifteen male C57BL/6J mice were randomized into shamoperated group, I/R group and I/R+EMPA group, and in the latter two groups, myocardial I/R injury was induced by ligating the left anterior descending coronary artery followed by reperfusion for 2 h. EMPA treatment was administered at the daily dose of 10 mg/kg for 7 days. After the treatment, the changes in myocardial microvascular structure of the mice were observed under electron microscopy. In the cell experiment, cultured human coronary artery endothelial cells (HCAECs) were treated with 10 μmol/L EMPA before exposure to hypoxia for 45 min followed normoxic culture for 2 h. Western blotting and immunofluorescence assay were performed to observe fibrin accumulation and endothelial cell protein expressions in the myocardial tissues of the mice and in HCAECs, and RT-qPCR was used to detect the expressions of pro-inflammatory cytokines.

RESULTS

Electron microscopy revealed significant myocardial microvascular wall thickening and lumen narrowing in mice with myocardial I/R injury. Fibrin accumulation and ICAM1 expression in the microvessels were more pronounced in I/R group than in the sham-operated and I/R + EMPA groups (P < 0.05). EMPA treatment obviously alleviated microvascular occlusion and microthrombus formation induced by I/R injury. At the cellular level, the protein levels of p-eNOS, Fak, and Src kinases in hypoxic exposure group were significantly lower than those in the control and EMPA treatment groups (P < 0.05). Hypoxic exposure significantly reduced mitochondrial DNA replication and transcription and lowered the expression levels of Cox-Ⅰ and Cox-Ⅱ in HCAECs, and these changes were obviously improved by EMPA treatment (P < 0.05).

CONCLUSION

EMPA can alleviate myocardial I/R injury by maintaining mitochondrial homeostasis to protect the microvascular system.