Empagliflozin alleviates myocardial I/R injury and cardiomyocyte apoptosis via inhibiting ER stress-induced autophagy and the PERK/ATF4/Beclin1 pathway

Is There a Role for SGLT2 Inhibitors in Patients with End-Stage Kidney Disease?

PURPOSE OF REVIEW

Chronic kidney disease and end-stage kidney disease (ESKD) are well-established risk factors for cardiovascular disease (CVD), the leading cause of mortality in the dialysis population. Conventional therapies, such as statins, blood pressure control, and renin-angiotensin-aldosterone system blockade, have inadequately addressed this cardiovascular risk, highlighting the unmet need for effective treatment strategies. Sodium-glucose transporter 2 (SGLT2) inhibitors have demonstrated significant renal and cardiovascular benefits among patients with type 2 diabetes, heart failure, or CKD at risk of progression. Unfortunately, efficacy data in dialysis patients is lacking as ESKD was an exclusion criterion for all major clinical trials of SGLT2 inhibitors. This review explores the potential of SGLT2 inhibitors in improving cardiovascular outcomes among patients with ESKD, focusing on their direct cardiac effects.

RECENT FINDINGS

Recent clinical and preclinical studies have shown promising data for the application of SGLT2 inhibitors to the dialysis population. SGLT2 inhibitors may provide cardiovascular benefits to dialysis patients, not only indirectly by preserving the remaining kidney function and improving anemia but also directly by lowering intracellular sodium and calcium levels, reducing inflammation, regulating autophagy, and alleviating oxidative stress and endoplasmic reticulum stress within cardiomyocytes and endothelial cells. This review examines the current clinical evidence and experimental data supporting the use of SGLT2 inhibitors, discusses its potential safety concerns, and outlines ongoing clinical trials in the dialysis population. Further research is needed to evaluate the safety and effectiveness of SGLT2 inhibitor use among patients with ESKD.

Cardioprotection of Canagliflozin, Dapagliflozin, and Empagliflozin: Lessons from preclinical studies

Clinical and preclinical studies have elucidated the favorable effects of Inhibitors of Sodium-Glucose Cotransporter-2 (iSGLT2) in patients and animal models with type 2 diabetes. Notably, these inhibitors have shown significant benefits in reducing hospitalizations and mortality among patients with heart failure. However, despite their incorporation into clinical practice for indications beyond diabetes, the decision-making process regarding their use often lacks a systematic approach. The selection of iSGLT2 remains arbitrary, with only a limited number of studies simultaneously exploring the different classes of them. Currently, no unique guideline establishes their application in both clinical and basic research. This review delves into the prevalent use of iSGLT2 in animal models previously subjected to induced cardiac stress. We have compiled key findings related to cardioprotection across various animal models, encompassing diverse dosages and routes of administration. Beyond their established role in diabetes management, iSGLT2 has demonstrated utility as agents for safeguarding heart health and cardioprotection can be class-dependent among the iSGLT2. These findings may serve as valuable references for other researchers. Preclinical studies play a pivotal role in ensuring the safety of novel compounds or treatments for potential human use. By assessing side effects, toxicity, and optimal dosages, these studies offer a robust foundation for informed decisions, identifying interventions with the highest likelihood of success and minimal risk to patients. The insights gleaned from preclinical studies, which play a crucial role in highlighting areas of knowledge deficiency, can guide the exploration of novel mechanisms and strategies involving iSGLT2.

Protective Mechanisms of SGLTi in Ischemic Heart Disease

Ischemic heart disease (IHD) is a common clinical cardiovascular disease with high morbidity and mortality. Sodium glucose cotransporter protein inhibitor (SGLTi) is a novel hypoglycemic drug. To date, both clinical trials and animal experiments have shown that SGLTi play a protective role in IHD, including myocardial infarction (MI) and ischemia/reperfusion (I/R). The protective effects may be involved in mechanisms of energy metabolic conversion, anti-inflammation, anti-fibrosis, ionic homeostasis improvement, immune cell development, angiogenesis and functional regulation, gut microbiota regulation, and epicardial lipids. Thus, this review summarizes the above mechanisms and aims to provide theoretical evidence for therapeutic strategies for IHD.

Targeting translocator protein protects against myocardial ischemia/reperfusion injury by alleviating mitochondrial dysfunction

Ischemic heart disease (IHD) remains a leading cause of mortalities worldwide, necessitating timely reperfusion to reduce acute mortality. Paradoxically, reperfusion can induce myocardial ischemia/reperfusion (I/R) injury, which is primarily characterized by mitochondrial dysfunction. Translocator protein (TSPO) participates in multiple cellular events; however, its role in IHD, especially in the process of myocardial I/R injury, has not been well determined. The aim of the present study was to investigate the functional role of TSPO in myocardial I/R injury and dissect the concomitant cellular events involved. This study utilized small interfering RNA (siRNA) technology to knock down TSPO expression. The I/R process was simulated using an anoxia/reoxygenation (A/R) model. The role of TSPO in H9c2 cardiomyocytes was assessed using various techniques, such as Western blotting, Flow cytometry, Reverse transcription-quantitative PCR (RT-qPCR), Immunofluorescence, Co-immunoprecipitation (co-IP) and similar methods. It was found that A/R markedly upregulated the expression of TSPO in cardiomyocytes. Inhibition of TSPO improved myocardial cell apoptosis and damage following A/R stimulation. Additionally, targeting TSPO alleviated mitochondrial damage, reduced mitochondrial ROS release and enhanced ATP synthesis following A/R stimulation. It was further confirmed that A/R stimulation induced a significant increase in the expression of pivotal markers [phosporylated-PKR-like ER kinase (PERK)/PERK, activating transcription factor 6 (ATF6) and inositol-requiring enzyme 1] involved in the adaptive unfolded protein response, which is accompanied by downstream signaling during endoplasmic reticulum (ER) stress. Notably, TSPO knockdown increased the expression of the aforementioned markers and, subsequently, TSPO was confirmed to interact with ATF6, suggesting that TSPO might play a role in ER stress during myocardial I/R injury. Finally, inhibition of TSPO upregulated mitophagy, as indicated by further decreases in P62 and increases in Parkin and PINK1 levels following A/R stimulation. Together, the results suggest that TSPO plays a multifaceted role in myocardial I/R injury. Understanding TSPO-induced cellular responses could inform targeted therapeutic strategies for patients with IHD.

SGLT2 inhibitors: how do they affect the cardiac cells

The first sodium-glucose cotransporter-2 inhibitor (SGLT2I), canagliflozin, was approved by the U.S. Food and Drug Administration for the treatment of type 2 diabetes in 2013. Since then, other members of this drug class (such as dapagliflozin, empagliflozin, and ertugliflozin) have become widely used. Unlike classical antidiabetic agents, these drugs do not interfere with insulin secretion or action, but instead promote renal glucose excretion. Since their approval, many preclinical and clinical studies have been conducted to investigate the diverse effects of SGLT2Is. While originally introduced as antidiabetic agents, the SGLT2Is are now recognized as pillars in the treatment of heart failure and chronic kidney disease, in patients with or without diabetes. The beneficial cardiac effects of this class have been attributed to several mechanisms. Among these, SGLT2Is inhibit fibrosis, hypertrophy, apoptosis, inflammation, and oxidative stress. They regulate mitochondrial function and ion transport, and stimulate autophagy through several underlying mechanisms. This review details the potential effects of SGLT2Is on cardiac cells.

Cardiovascular outcomes and molecular targets for the cardiac effects of Sodium-Glucose Cotransporter 2 Inhibitors: A systematic review

Sodium-glucose cotransporter 2 inhibitors (SGLT2i), a new class of glucose-lowering drugs traditionally used to control blood glucose levels in patients with type 2 diabetes mellitus, have been proven to reduce major adverse cardiovascular events, including cardiovascular death, in patients with heart failure irrespective of ejection fraction and independently of the hypoglycemic effect. Because of their favorable effects on the kidney and cardiovascular outcomes, their use has been expanded in all patients with any combination of diabetes mellitus type 2, chronic kidney disease and heart failure. Although mechanisms explaining the effects of these drugs on the cardiovascular system are not well understood, their effectiveness in all these conditions suggests that they act at the intersection of the metabolic, renal and cardiac axes, thus disrupting maladaptive vicious cycles while contrasting direct organ damage. In this systematic review we provide a state of the art of the randomized controlled trials investigating the effect of SGLT2i on cardiovascular outcomes in patients with chronic kidney disease and/or heart failure irrespective of ejection fraction and diabetes. We also discuss the molecular targets and signaling pathways potentially explaining the cardiac effects of these pharmacological agents, from a clinical and experimental perspective.

Empagliflozin Alleviates Carfilzomib-Induced Cardiotoxicity in Mice by Modulating Oxidative Stress, Inflammatory Response, Endoplasmic Reticulum Stress, and Autophagy

Carfilzomib is an irreversible proteasome inhibitor used for multiple myeloma patients. However, carfilzomib treatment is associated with cardiovascular complications. Empagliflozin, an Sodium Glucose Co-transporter 2 inhibitor (SGLT-2) inhibitor, is an oral antidiabetic drug with proven antioxidant and anti-inflammatory properties. The aim of the present study was to determine the cardioprotective effects of empagliflozin against carfilzomib-induced cardiotoxicity. C57BL/6 mice were randomly divided into four groups: control, empagliflozin, carfilzomib, and carfilzomib + empagliflozin. Empagliflozin prevented carfilzomib-induced cardiotoxicity by ameliorating histological alterations, CK-MB, and troponin-I. Moreover, it inhibited carfilzomib-induced oxidative damage and inflammation via its action on catalase activity, reduced glutathione levels and superoxide dismutase activity, and reduced nuclear factor-κB (p65) and cytokine levels. Mechanistically, empagliflozin abrogated endoplasmic reticulum stress induced by carfilzomib, as evidenced by the effect on the Glucose Regulated Protein-78 (GRP-78)/Activating Transcription Factor 6 (ATF6)/C/EBP homologous protein (CHOP) axis. Intriguingly, carfilzomib significantly induced autophagy, an effect that was further enhanced by empagliflozin, evidenced by increased LC3B and beclin-1 mRNA expression and reduced p62 expression. The effect of empagliflozin on apoptosis was confirmed by reduced expression of active caspase-3. Importantly, empagliflozin did not alter the cytotoxic effect of carfilzomib on human U266B1 multiple myeloma cells. our findings suggest that empagliflozin may provide a new therapeutic strategy to mitigate carfilzomib-induced cardiotoxicity in multiple myeloma patients.

Sodium glucose cotransporter-2 inhibitors and heart disease: Current perspectives

Sodium glucose cotransporter-2 inhibitors (SGLT-2i) are antidiabetic medications with remarkable cardiovascular (CV) benefits proven by multiple randomised controlled trials and real-world data. These drugs are also useful in the prevention of CV disease (CVD) in patients with diabetes mellitus (DM). Although DM as such is a huge risk factor for CVD, the CV benefits of SGLT-2i are not just because of antidiabetic effects. These molecules have proven beneficial roles in prevention and management of nondiabetic CVD and renal disease as well. There are various molecular mechanisms for the organ protective effects of SGLT-2i which are still being elucidated. Proper understanding of the role of SGLT-2i in prevention and management of CVD is important not only for the cardiologists but also for other specialists caring for various illnesses which can directly or indirectly impact care of heart diseases. This clinical review compiles the current evidence on the rational use of SGLT-2i in clinical practice.

Crosstalk among Reactive Oxygen Species, Autophagy and Metabolism in Myocardial Ischemia and Reperfusion Stages

Myocardial ischemia is the most common cardiovascular disease. Reperfusion, an important myocardial ischemia tool, causes unexpected and irreversible damage to cardiomyocytes, resulting in myocardial ischemia/reperfusion (MI/R) injury. Upon stress, especially oxidative stress induced by reactive oxygen species (ROS), autophagy, which degrades the intracellular energy storage to produce metabolites that are recycled into metabolic pathways to buffer metabolic stress, is initiated during myocardial ischemia and MI/R injury. Excellent cardioprotective effects of autophagy regulators against MI and MI/R have been reported. Reversing disordered cardiac metabolism induced by ROS also exhibits cardioprotective action in patients with myocardial ischemia. Herein, we review current knowledge on the crosstalk between ROS, cardiac autophagy, and metabolism in myocardial ischemia and MI/R. Finally, we discuss the possible regulators of autophagy and metabolism that can be exploited to harness the therapeutic potential of cardiac metabolism and autophagy in the diagnosis and treatment of myocardial ischemia and MI/R.

Empagliflozin and risk of lower respiratory tract infection in heart failure with mildly reduced and preserved ejection fraction: An EMPEROR-Preserved analysis

AIMS

Lower respiratory tract infections (LRTI) are common worldwide. Patients with heart failure and mildly reduced or preserved ejection fraction (HFmrEF/HFpEF) have a high risk of developing LRTI. Prior studies were able to show that sodium-glucose cotransporter 2 inhibitors may reduce the incidence of LRTI in patients with type 2 diabetes. The aim of this study was to evaluate patient characteristics and prognosis according to LRTI status and to assess the effect of empagliflozin on LRTI in 5988 patients with HFmrEF/HFpEF enrolled in the EMPEROR-Preserved trial randomized to either empagliflozin or placebo over a median follow-up of 26 months.

METHODS AND RESULTS

Time-updated models were used to study the mortality risk after a LRTI. Cox regression was used to study the effect of empagliflozin on incident LRTI. Throughout the follow-up, 699 of 5988 (11.7%) patients developed LRTI: these were older, were more frequently hospitalized within the previous year, had type 2 diabetes, chronic kidney disease, and had higher N-terminal pro-B-type natriuretic peptide levels than patients without incident LRTI. Patients who developed LRTI had a 2.7-fold higher risk of subsequent mortality compared to patients without LRTI. The incidence of LRTI was 5.2 (95% confidence interval [CI] 4.6-5.8) events per 100 person-years in the empagliflozin group and 6.2 (95% CI 5.6-6.9) events per 100 person-years in the placebo group (hazard ratio 0.83, 95% CI 0.71-0.96, p = 0.014). The total number of LRTI events was reduced in the empagliflozin group (incidence rate ratio 0.80, 95% CI 0.68-0.94, p = 0.008). No effect of empagliflozin was observed on COVID-19 incidence.

CONCLUSION

In EMPEROR-Preserved, LRTI was frequent and associated with a poor prognosis. Empagliflozin was associated with a reduced risk of LRTI compared to placebo.

The Cardioprotective and Anticancer Effects of SGLT2 Inhibitors: JACC: CardioOncology State-of-the-Art Review

Sodium-glucose cotransporter-2 (SGLT2) inhibitors, originally approved for type 2 diabetes mellitus, have demonstrated efficacy in reducing cardiovascular events, particularly heart failure, in patients with and without diabetes. An intriguing research area involves exploring the potential application of SGLT2 inhibitors in cardio-oncology, aiming to mitigate the cardiovascular adverse events associated with anticancer treatments. These inhibitors present a unique dual nature, offering both cardioprotective effects and anticancer properties, conferring a double benefit for cardio-oncology patients. In this review, the authors first examine the established cardioprotective effects of SGLT2 inhibitors in heart failure and subsequently explore the existing body of evidence, including both preclinical and clinical studies, that supports the use of SGLT2 inhibitors in the context of cardio-oncology. The authors further discuss the mechanisms through which SGLT2 inhibitors protect against cardiovascular toxicity secondary to cancer treatment. Finally, they explore the potential anticancer effects of SGLT2 inhibitors along with their proposed mechanisms.

SGLT2 inhibitors: Beyond glycemic control

Multiple randomized controlled trials have extensively examined the therapeutic effectiveness of sodium-glucose cotransporter 2 (SGLT2) inhibitors, ushering in a transformative approach to treating individuals with type 2 diabetes mellitus (DM). Notably, emerging reports have drawn attention to the potential positive impacts of SGLT2 inhibitors in nondiabetic patients. In an effort to delve into this phenomenon, a comprehensive systematic literature review spanning PubMed (NLM), Medline (Ovid), and Cochrane Library, covering publications from 2000 to 2024 was undertaken. This systematic review encompassed twenty-six randomized control trials (RCTs) involving 35,317 participants. The findings unveiled a multifaceted role for SGLT2 inhibitors, showcasing their ability to enhance metabolic control and yield cardioprotective effects through a reduction in cardiovascular death (CVD) and hospitalization related to heart failure (HF). Additionally, a renalprotective effect was observed, evidenced by a slowdown in chronic kidney disease (CKD) progression and a decrease in albuminuria. Importantly, these benefits were coupled with an acceptable safety profile. The literature also points to various biological plausibility and underlying mechanistic pathways, offering insights into the association between SGLT2 inhibitors and these positive outcomes in nondiabetic individuals. Current research trends indicate a continual exploration of additional role for SGLT2 inhibitors in. Nevertheless, further research is imperative to fully elucidate the mechanisms and long-term outcomes associated with the nondiabetic use of SGLT2 inhibitors.

Induction mechanisms of autophagy and endoplasmic reticulum stress in intestinal ischemia-reperfusion injury, inflammatory bowel disease, and colorectal cancer

In recent years, the incidence of intestinal ischemia-reperfusion injury (II/RI), inflammatory bowel disease (IBD), and colorectal cancer (CRC) has been gradually increasing, posing significant threats to human health. Autophagy and endoplasmic reticulum stress (ERS) play important roles in II/RI. Damage caused by ischemia and cellular stress can activate ERS, which in turn initiates autophagy to clear damaged organelles and abnormal proteins, thereby alleviating ERS and maintaining the intestinal environment. In IBD, chronic inflammation damages intestinal tissues and activates autophagy and ERS. Autophagy is initiated by upregulating ATG genes and downregulating factors that inhibit autophagy, thereby clearing abnormal proteins, damaged organelles, and bacteria. Simultaneously, persistent inflammatory stimulation can also trigger ERS, leading to protein imbalance and abnormal folding in the ER lumen. The activation of ERS can maintain cellular homeostasis by initiating the autophagy process, thereby reducing inflammatory responses and cell apoptosis in the intestine. In CRC, excessive cell proliferation and protein synthesis lead to increased ERS. The activation of ERS, regulated by signaling pathways such as IRE1α and PERK, can initiate autophagy to clear abnormal proteins and damaged organelles, thereby reducing the negative effects of ERS. It can be seen that autophagy and ERS play a crucial regulatory role in the development of intestinal diseases. Therefore, the progress in targeted therapy for intestinal diseases based on autophagy and ERS provides novel strategies for managing intestinal diseases. In this paper, we review the advances in regulation of autophagy and ERS in intestinal diseases, emphasizing the potential molecular mechanisms for therapeutic applications.

The influence of dapagliflozin on cardiac remodeling, myocardial function and metabolomics in type 1 diabetes mellitus rats

BACKGROUND

Sodium-glucose cotransporter (SGLT)2 inhibitors have displayed beneficial effects on the cardiovascular system in diabetes mellitus (DM) patients. As most clinical trials were performed in Type 2 DM, their effects in Type 1 DM have not been established.

OBJECTIVE

To evaluate the influence of long-term treatment with SGLT2 inhibitor dapagliflozin on cardiac remodeling, myocardial function, energy metabolism, and metabolomics in rats with Type 1 DM.

METHODS

Male Wistar rats were divided into groups: Control (C, n = 15); DM (n = 15); and DM treated with dapagliflozin (DM + DAPA, n = 15) for 30 weeks. DM was induced by streptozotocin. Dapagliflozin 5 mg/kg/day was added to chow.

STATISTICAL ANALYSIS

ANOVA and Tukey or Kruskal-Wallis and Dunn.

RESULTS

DM + DAPA presented lower glycemia and higher body weight than DM. Echocardiogram showed DM with left atrium dilation and left ventricular (LV) hypertrophy, dilation, and systolic and diastolic dysfunction. In LV isolated papillary muscles, DM had reduced developed tension, +dT/dt and -dT/dt in basal condition and after inotropic stimulation. All functional changes were attenuated by dapagliflozin. Hexokinase (HK), phosphofructokinase (PFK) and pyruvate kinase (PK) activity was lower in DM than C, and PFK and PK activity higher in DM + DAPA than DM. Metabolomics revealed 21 and 5 metabolites positively regulated in DM vs. C and DM + DAPA vs. DM, respectively; 6 and 3 metabolites were negatively regulated in DM vs. C and DM + DAPA vs. DM, respectively. Five metabolites that participate in cell membrane ultrastructure were higher in DM than C. Metabolites levels of N-oleoyl glutamic acid, chlorocresol and N-oleoyl-L-serine were lower and phosphatidylethanolamine and ceramide higher in DM + DAPA than DM.

CONCLUSION

Long-term treatment with dapagliflozin attenuates cardiac remodeling, myocardial dysfunction, and contractile reserve impairment in Type 1 diabetic rats. The functional improvement is combined with restored pyruvate kinase and phosphofructokinase activity and attenuated metabolomics changes.

Ischemia-reperfusion injury in human AC16 cardiomyocytes is modulated by AXIN1 depending on c-Myc regulation

Objective

A major consequence of acute myocardial infarction is myocardial ischemia-reperfusion (I/R) injury. Collecting proof demonstrates that AXIN1 assume a basic part in different disease; however, the role of AXIN1 in I/R injury remains to a great extent obscure.

Methods

The I/R injury model on AC16 cells was constructed. siRNA transfection was used to knockdown AXIN1. The qRT-PCR assays and western blot assays were used to detect the expression level of AXIN1 and other key proteins. CCK-8 assays and cell apoptosis assays were used to detect cell proliferation and cell apoptosis.

Results

AXIN1 was significantly overexpressed in an in vitro model of I/R injury. Knockdown of AXIN1 significantly restored the cell proliferation inhibition caused by IR injury, while inhibiting apoptosis and inflammation. Further mechanistic studies revealed that the transcription factor c-Myc could regulate the expression of AXIN1. The effects of I/R injury on AC16 cells after overexpression of c-Myc were reversed by knockdown of AXIN1. Meanwhile, AXIN1 could regulate the SIRT1/p53/Nrf 2 pathway.

Conclusion

Our results show an important role for AXIN1 and provide new targets for avoiding and treating I/R injury.

Effects of new hypoglycemic drugs on cardiac remodeling: a systematic review and network meta-analysis

BACKGROUND

In recent years, the incidence of diabetes mellitus has been increasing annually, and cardiovascular complications secondary to diabetes mellitus have become the leading cause of death in diabetic patients. Considering the high incidence of type 2 diabetes (T2DM) combined with cardiovascular disease (CVD), some new hypoglycemic agents with cardiovascular protective effects have attracted extensive attention. However, the specific role of these regimens in ventricular remodeling remains unknown. The purpose of this network meta-analysis was to compare the effects of sodium glucose cotransporter type 2 inhibitor (SGLT-2i), glucagon-like peptide 1 receptor agonist (GLP-1RA) and dipeptidyl peptidase-4 inhibitor (DPP-4i) on ventricular remodeling in patients with T2DM and/or CVD.

METHODS

Articles published prior to 24 August 2022 were retrieved in four electronic databases: the Cochrane Library, Embase, PubMed, and Web of Science. This meta-analysis included randomized controlled trials (RCTs) and a small number of cohort studies. The differences in mean changes of left ventricular ultrasonic parameters between the treatment and control groups were compared.

RESULTS

A total of 31 RCTs and 4 cohort studies involving 4322 patients were analyzed. GLP-1RA was more significantly associated with improvement in left ventricular end-systolic diameter (LVESD) [MD = -0.38 mm, 95% CI (-0.66, -0.10)] and LV mass index (LVMI) [MD = -1.07 g/m2, 95% CI (-1.71, -0.42)], but significantly decreased e' [MD = -0.43 cm/s 95% CI (-0.81, -0.04)]. DPP-4i was more strongly associated with improvement in e' [MD = 3.82 cm/s, 95% CI (2.92,4.7)] and E/e'[MD = -5.97 95% CI (-10.35, -1.59)], but significantly inhibited LV ejection fraction (LVEF) [MD = -0.89% 95% CI (-1.76, -0.03)]. SGLT-2i significantly improved LVMI [MD = -0.28 g/m2, 95% CI (-0.43, -0.12)] and LV end-diastolic diameter (LVEDD) [MD = -0.72 ml, 95% CI (-1.30, -0.14)] in the overall population, as well as E/e' and SBP in T2DM patients combined with CVD, without showing any negative effect on left ventricular function.

CONCLUSION

The results of the network meta-analysis provided high certainty to suggest that SGLT-2i may be more effective in cardiac remodeling compared to GLP-1RA and DPP-4i. While GLP-1RA and DPP-4i may have a tendency to improve cardiac systolic and diastolic function respectively. SGLT-2i is the most recommended drug for reversing ventricular remodeling in this meta-analysis.

Targeting unfolded protein response reverts ER stress and ER Ca2+ homeostasis in cardiomyocytes expressing the pathogenic variant of Lamin A/C R321X

BACKGROUND

We previously demonstrated that an Italian family affected by a severe dilated cardiomyopathy (DCM) with history of sudden deaths at young age, carried a mutation in the Lmna gene encoding for a truncated variant of the Lamin A/C protein (LMNA), R321X. When expressed in heterologous systems, such variant accumulates into the endoplasmic reticulum (ER), inducing the activation of the PERK-CHOP pathway of the unfolded protein response (UPR), ER dysfunction and increased rate of apoptosis. The aim of this work was to analyze whether targeting the UPR can be used to revert the ER dysfunction associated with LMNA R321X expression in HL-1 cardiac cells.

METHODS

HL-1 cardiomyocytes stably expressing LMNA R321X were used to assess the ability of 3 different drugs targeting the UPR, salubrinal, guanabenz and empagliflozin to rescue ER stress and dysfunction. In these cells, the state of activation of both the UPR and the pro-apoptotic pathway were analyzed monitoring the expression levels of phospho-PERK, phospho-eIF2α, ATF4, CHOP and PARP-CL. In addition, we measured ER-dependent intracellular Ca²⁺ dynamics as indicator of proper ER functionality.

RESULTS

We found that salubrinal and guanabenz increased the expression levels of phospho-eIF2α and downregulated the apoptosis markers CHOP and PARP-CL in LMNA R321X-cardiomyocytes, maintaining the so-called adaptive UPR. These drugs also restored ER ability to handle Ca²⁺ in these cardiomyocytes. Interestingly, we found that empagliflozin downregulated the apoptosis markers CHOP and PARP-CL shutting down the UPR itself through the inhibition of PERK phosphorylation in LMNA R321X-cardiomyocytes. Furthermore, upon empagliflozin treatment, ER homeostasis, in terms of ER ability to store and release intracellular Ca²⁺ was also restored in these cardiomyocytes.

CONCLUSIONS

We provided evidence that the different drugs, although interfering with different steps of the UPR, were able to counteract pro-apoptotic processes and to preserve the ER homeostasis in R321X LMNA-cardiomyocytes. Of note, two of the tested drugs, guanabenz and empagliflozin, are already used in the clinical practice, thus providing preclinical evidence for ready-to-use therapies in patients affected by the LMNA R321X associated cardiomyocytes.

Insights into SGLT2 inhibitor treatment of diabetic cardiomyopathy: focus on the mechanisms

Among the complications of diabetes, cardiovascular events and cardiac insufficiency are considered two of the most important causes of death. Experimental and clinical evidence supports the effectiveness of SGLT2i for improving cardiac dysfunction. SGLT2i treatment benefits metabolism, microcirculation, mitochondrial function, fibrosis, oxidative stress, endoplasmic reticulum stress, programmed cell death, autophagy, and the intestinal flora, which are involved in diabetic cardiomyopathy. This review summarizes the current knowledge of the mechanisms of SGLT2i for the treatment of diabetic cardiomyopathy.

Empagliflozin inhibits autophagy and mitigates airway inflammation and remodelling in mice with ovalbumin-induced allergic asthma

Empagliflozin, a selective inhibitor of Na⁺-glucose cotransporter-2, has been reported to exert anti-inflammatory and anti-fibrotic effects in addition to autophagy modulation. Addressing the role of autophagy in allergic asthma revealed controversial results. The potential effect of empagliflozin treatment on airway inflammation and remodelling as well as autophagy modulation in a murine model of allergic asthma was investigated. Over a 7-week period, male BALB/c mice were sensitized and challenged by intraperitoneal injection and inhalation of ovalbumin, respectively. Animals were treated with empagliflozin (10 mg/kg; orally) and/or rapamycin (an autophagy inducer; 4 mg/kg; intraperitoneally) before every challenge. Methacholine-induced airway hyperresponsiveness was evaluated one day after the last challenge. After euthanasia, serum, bronchoalveolar lavage fluid, and lung tissues were collected for biochemical, histopathological, and immunohistochemical assessment. Results revealed that empagliflozin decreased airway hyperresponsiveness, serum ovalbumin-specific immunoglobulin E, and bronchoalveolar lavage total and differential leukocytic counts. Levels of inflammatory and profibrotic cytokines (IL-4, IL-5, IL-13, IL-17, and transforming growth factor-β1) were all inhibited. Moreover, empagliflozin preserved pulmonary microscopic architecture and alleviated bronchiolar epithelial thickening, goblet cell hyperplasia, fibrosis and smooth muscle hypertrophy. These effects were associated with inhibition of ovalbumin-activated autophagic flux, as demonstrated by decreased LC3B expression and LC3BII/I ratio, as well as increased P62 expression. However, the therapeutic potential of empagliflozin was inhibited when rapamycin was co-administered. In conclusion, this study demonstrates that empagliflozin has immunomodulatory, anti-inflammatory, and anti-remodelling properties in ovalbumin-induced allergic asthma and suggests that autophagic flux inhibition may play a role in empagliflozin's anti-asthmatic effects.

Empagliflozin ameliorates cardiac dysfunction in heart failure mice via regulating mitochondrial dynamics

Empagliflozin has cardioprotective effects in patients with heart failure (HF). However, the mechanism by which empagliflozin protects against HF remains controversial. Study aimed to evaluate the effect of empagliflozin on myocardial fibrosis and cardiac function in HF mice and its possible mechanism. C57BL/6 mice were induced with HF by ligation of the left anterior descending coronary artery. At 4 weeks postoperation, mice were randomly given normal saline or empagliflozin for 8 weeks. Echocardiography was used to assess cardiac function. Masson's staining, immunohistochemistry and Western blot analysis were used to detect the degree of myocardial fibrosis. Changes in mitochondria were detected by observing mitochondrial morphology, measuring mitochondrial dynamics-related proteins and analysing the levels of adenosine triphosphate (ATP), adenosine monophosphate (AMP) and adenosine diphosphate (ADP). The mitochondrial fission inhibitor, mdivi1, was used to detect the relationship between mitochondrial dysfunction and cardiac dysfunction in HF mice. HF led to myocardial fibrosis and cardiac dysfunction. However, treatment with empagliflozin reduced these effects. Empagliflozin inhibited mitochondrial fission and improved energy metabolic efficiency in HF mice by regulating the expression of mitochondrial dynamics-related proteins. Similarly, mdivi1 attenuated mitochondrial dysfunction and cardiac dysfunction by inhibiting mitochondrial fission in HF mice. Regulation of mitochondrial dynamics, especially inhibition of mitochondrial fission, may be a potential target for reducing cardiac damage in patients with HF. Empagliflozin improved myocardial fibrosis and cardiac dysfunction by modulating mitochondrial dynamics in HF mice. Thus, the cardiac protective effect of empagliflozin may be related to the normalization of mitochondria and the increase in ATP production.

Diabetes Mellitus and Heart Failure: Epidemiology, Pathophysiologic Mechanisms, and the Role of SGLT2 Inhibitors

Diabetes mellitus (DM) and heart failure (HF) are frequently encountered afflictions that are linked by a common pathophysiologic background. According to landmark studies, those conditions frequently coexist, and this interaction represents a poor prognostic indicator. Based on mechanistic studies, HF can be propagated by multiple pathophysiologic pathways, such as inflammation, oxidative stress, endothelial dysfunction, fibrosis, cardiac autonomic neuropathy, and alterations in substrate utilization. In this regard, DM may augment myocardial inflammation, fibrosis, autonomic dysfunction, and lipotoxicity. As the interaction between DM and HF appears critical, the new cornerstone in DM and HF treatment, sodium-glucose cotransporter-2 inhibitors (SGLT2i), may be able to revert the pathophysiology of those conditions and lead to beneficial HF outcomes. In this review, we aim to highlight the deleterious pathophysiologic interaction between DM and HF, as well as demonstrate the beneficial role of SGLT2i in this field.

Methyltransferase-like 3 aggravates endoplasmic reticulum stress in preeclampsia by targeting TMBIM6 in YTHDF2-dependent manner

BACKGROUND

With the increasing morbidity and mortality of preeclampsia (PE), it has posed a huge challenge to public health. Previous studies have reported endoplasmic reticulum (ER) stress could contribute to trophoblastic dysfunction which was associated with the N⁶-methyladenosine (m⁶A) modification by methyltransferase-like 3 (METTL3), resulting in PE. However, little was known about the relationship between METTL3 and ER stress in PE. Thus, in vitro and in vivo studies were performed to clarify the mechanism about how METTL3 affects the trophoblasts under ER stress in PE and to explore a therapeutic approach for PE.

METHODS

An ER stress model in HTR-8/SVneo cells and a preeclamptic rat model were used to study the mechanism and explore a therapeutic approach for PE. Western blot, immunohistochemistry, quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and methylated RNA immunoprecipitation (MeRIP)-qPCR were performed to detect the protein, RNA, and methylated transmembrane BAX inhibitor motif containing 6 (TMBIM6) expression levels. The m⁶A colorimetric and mRNA stability assays were used to measure the m⁶A levels and TMBIM6 stability, respectively. Short hairpin RNAs (shRNAs) were used to knockdown METTL3 and YTH N6-methyladenosine RNA binding protein 2 (YTHDF2). Flow cytometry and Transwell assays were performed to evaluate the apoptosis and invasion abilities of trophoblasts.

RESULTS

Upregulated METTL3 and m⁶A levels and downregulated TMBIM6 levels were observed in preeclamptic placentas under ER stress. The ER stress model was successfully constructed, and knockdown of METTL3 had a beneficial effect on HTR-8/SVneo cells under ER stress as it decreased the levels of methylated TMBIM6 mRNA. Moreover, overexpression of TMBIM6 was beneficial to HTR-8/SVneo cells under ER stress as it could neutralize the harmful effects of METTL3 overexpression. Similar to the knockdown of METTL3, downregulation of YTHDF2 expression resulted in the increased expression and mRNA stability of TMBIM6. Finally, improved systemic symptoms as well as protected placentas and fetuses were demonstrated in vivo.

CONCLUSIONS

METTL3/YTHDF2/TMBIM6 axis exerts a significant role in trophoblast dysfunction resulting in PE while inhibiting METTL3 may provide a novel therapeutic approach for PE.

Jianpi-Qingchang decoction alleviates ulcerative colitis by modulating endoplasmic reticulum stress-related autophagy in intestinal epithelial cells

Endoplasmic reticulum stress (ERS)-related autophagy is involved in the occurrence and development of ulcerative colitis (UC). Therefore, regulating ERS-related autophagy is a potential therapeutic target for the treatment of UC. Jianpi-Qingchang (JPQC) decoction, consisting of nine Chinese herbal medicines, is used to treat patients with UC. However, its mechanism of action has not been completely elucidated. Here, we aimed to reveal the therapeutic effects and mechanisms of JPQC in UC. We established a colitis model using dextran sulfate sodium (DSS) and an ERS model using thapsigargin (Tg) and administered JPQC. We systematically examined ERS-related autophagy associated protein expression, inflammatory cytokines, apoptotic cells, and autophagic flux. Moreover, the cellular ultrastructure was observed via transmission electron microscopy (TEM). We found that JPQC reduced disease activity index (DAI) scores, counteracted colonic tissue damage, decreased the number of autophagosomes, inhibited proinflammatory cytokines, enhanced anti-inflammatory cytokines, and dampened ERS-related autophagy associated protein gene expression.

SGLT2 inhibitors protect cardiomyocytes from myocardial infarction: a direct mechanism?

SGLT2 inhibitors have been developed as a novel class of glucose-lowering drugs affecting reabsorption of glucose and metabolic processes. They have been recently identified to be remarkably favorable in treating cardiovascular diseases, especially heart failure. Preclinical experiments have shown that SGLT2 inhibitors could hinder the progression of myocardial infarction and alleviate cardiac remodeling by mechanisms of metabolism influence, autophagy induction, inflammation attenuation and fibrosis reduction. Here we summarize the direct mechanism of SGLT2 inhibitors on myocardial infarction and investigate whether it could be applied to the clinic in improving cardiac function and healing after myocardial infarction.

Oleuropein attenuates testicular ischemia-reperfusion by inhibiting apoptosis and inflammation

BACKGROUND

Ischemia-reperfusion injury (IRI) is the key reason of injury after testicular torsion and may eventually lead to male infertility. Oleuropein, a natural antioxidant isolated from Olea europaea, has shown beneficial effects in different models of ischemia. We evaluated the effects of oleuropein on testicular IRI and explored the underlying protective mechanisms.

METHODS

A mouse testicular torsion/detorsion (T/D) model and an oxygen-glucose deprivation/reperfusion (OGD/R) germ cell model were established and treated with oleuropein. H&E staining was used to evaluate testicular pathological changes. Apoptosis and apoptosis-associated protein levels in testis tissues were assessed by TUNEL staining, immunohistochemical staining and western blot. Apoptosis levels and apoptosis-associated protein levels in GC-1 were evaluated by flow cytometry, immunofluorescence and western blot. Oxidative stress levels were assessed by malondialdehyde (MDA) and superoxide dismutase (SOD) kits. Cell viability and inflammatory protein levels were evaluated by CCK-8 assay coupled with qRT-PCR.

RESULTS

Relative to the control group, SOD activity was markedly suppressed, while MDA, Bax, Caspase-3, TNF-α as well as IL-1β levels were significantly increased in the T/D model and OGD/R model. However, all of the aforementioned alterations were relieved by oleuropein treatment.

CONCLUSION

Our findings indicate that oleuropein may be a promising treatment option to attenuate testicular IRI via its anti-oxidant, anti-inflammatory as well as anti-apoptotic properties.

Role of Sodium-Glucose Co-Transporter 2 Inhibitors in the Regulation of Inflammatory Processes in Animal Models

Sodium-glucose co-transporter 2 inhibitors, also known as gliflozins, were developed as a novel class of anti-diabetic agents that promote glycosuria through the prevention of glucose reabsorption in the proximal tubule by sodium-glucose co-transporter 2. Beyond the regulation of glucose homeostasis, they resulted as being effective in different clinical trials in patients with heart failure, showing a strong cardio-renal protective effect in diabetic, but also in non-diabetic patients, which highlights the possible existence of other mechanisms through which gliflozins could be exerting their action. So far, different gliflozins have been approved for their therapeutic use in T2DM, heart failure, and diabetic kidney disease in different countries, all of them being diseases that have in common a deregulation of the inflammatory process associated with the pathology, which perpetuates and worsens the disease. This inflammatory deregulation has been observed in many other diseases, which led the scientific community to have a growing interest in the understanding of the biological processes that lead to or control inflammation deregulation in order to be able to identify potential therapeutic targets that could revert this situation and contribute to the amelioration of the disease. In this line, recent studies showed that gliflozins also act as an anti-inflammatory drug, and have been proposed as a useful strategy to treat other diseases linked to inflammation in addition to cardio-renal diseases, such as diabetes, obesity, atherosclerosis, or non-alcoholic fatty liver disease. In this work, we will review recent studies regarding the role of the main sodium-glucose co-transporter 2 inhibitors in the control of inflammation.