Possibility of a New Therapeutic Strategy for Left Ventricular Dysfunction in Type 2 Diabetes

Relationship Between Circulating MicroRNAs and Left Ventricular Hypertrophy in Hypertensive Patients

Objective

Left ventricular hypertrophy (LVH) is a common complication of hypertension and microRNAs (miRNAs) are considered to play an important role in cardiac hypertrophy development. This study evaluated the relationship between circulating miRNAs and LVH in hypertensive patients.

Methods

Two cohorts [exploratory (n = 42) and validation (n = 297)] of hypertensive patients were evaluated by clinical, laboratory and echocardiography analysis. The serum expression of 754 miRNAs in the exploratory cohort and 6 miRNAs in the validation cohort was evaluated by the TaqMan OpenArray^® system and quantitative polymerase chain reaction, respectively.

Results

Among the 754 analyzed miRNAs, ten miRNAs (miR-30a-5p, miR-let7c, miR-92a, miR-451, miR-145-5p, miR-185, miR-338, miR-296, miR-375, and miR-10) had differential expression between individuals with and without LVH in the exploratory cohort. Results of multivariable regression analysis adjusted for confounding variables showed that three miRNAs (miR-145-5p, miR-451, and miR-let7c) were independently associated with LVH and left ventricular mass index in the validation cohort. Functional enrichment analysis demonstrated that these three miRNAs can regulate various genes and pathways related to cardiac remodeling. Furthermore, in vitro experiments using cardiac myocytes demonstrated that miR-145-5p mimic transfection up-regulated the expression of brain and atrial natriuretic peptide genes, which are markers of cardiac hypertrophy, while anti-miR-145-5p transfection abrogated the expression of these genes in response to norepinephrine stimulus.

Conclusions

Our data demonstrated that circulating levels of several miRNAs, in particular miR-145-5p, miR-451, and let7c, were associated with LVH in hypertensive patients, indicating that these miRNAS may be potential circulating biomarkers or involved in hypertension-induced LV remodeling.

Imeglimin prevents heart failure with preserved ejection fraction by recovering the impaired unfolded protein response in mice subjected to cardiometabolic stress

The pathogenesis of heart failure with preserved ejection fraction (HFpEF) in obese diabetic patients has been implicated in metainflammation. Increased expression of inducible nitric oxide synthase (iNOS) and dysfunction of the unfolded protein response (UPR), especially inositol-requiring enzyme 1α-X-box binding protein 1 (IRE1α-Xbp1s) signaling in the heart, have been associated with HFpEF. We investigated the effect of imeglimin, a potential new treatment for type 2 diabetes, on the pathogenesis of HFpEF. We induced obesity, impaired glucose tolerance, and cardiac hypertrophy with fibrosis, fat accumulation, and diastolic dysfunction in wild-type mice with a high-fat diet (HFD) and the nitric oxide synthase (NOS) inhibitor l-NAME for 16 weeks. Treatment with imeglimin starting at 10 weeks not only improved their abnormal systemic glucose metabolism and visceral obesity but also their cardiac abnormalities. We found that imeglimin suppressed the upregulation of iNOS, and restored the expression of Xbp1s and the expression of the E3 ubiquitin ligase STIP1 homology and U-box-containing protein 1 (STUB1), which is responsible for the degradation of Forkhead box protein O1 (FoxO1), a direct transcriptional target of Xbp1s. It also suppressed the excessive transcriptional activity of FoxO1, which is located downstream of Xbp1s and is involved in the form development of HFpEF and cardiac adipogenesis. Imeglimin also restored the expression of Glutathione peroxidase 4 (GPX4), which protects cells against excess lipid peroxidation and governs a novel form of programmed cell death, called ferroptosis.

Assessment of real-time three-dimensional echocardiography as a tool for evaluating left atrial volume and function in patients with type 2 diabetes mellitus

Objective: To assess the value of real-time three-dimensional echocardiography (RT-3DE) in evaluating changes in left atrial volume and function in type 2 diabetes mellitus (DM) and type 2 diabetic nephropathy (DN) patients.

Method: 104 control subjects, 109 DN patients, and 111 DM patients were recruited and underwent RT-3DE. Data pertaining to the left atrium were analyzed using the 3DQA software in order to determine left atrial maximum volume index (LAVImax), left atrial pre-systolic volume index (LAVIp), left atrial minimum volume index (LAVImin), total left atrial ejection fraction (LAEFt), passive left atrial ejection fraction (LAEFp), and active left atrial ejection fraction (LAEFa). Differences between these three groups and correlations between individual index values and E/e' ratios were additionally assessed.

Result: LAVImax, LAVIp, and LAVImin were higher in the DN and DM groups relative to controls, whereas LAEFt and LAEFp were higher in controls relative to DM and DN patients (P < 0.05). LAVImax, LAVIp, and LAVImin in the DN group were significantly higher than those in the DM group, while LAEFt, LAEFp were higher in DM patients relative to DN patients (P < 0.05). The E/e' ratio was also found to be significantly correlated with LAVImax, LAVIp, and LAVImin.

Conclusion: Our results indicate that RT-3DE can be used to assess changes in left atrial volume and function in patients with diabetes and can be used to monitor disease progression-related damage to such left atrial functionality.

Short-and long-term administration of imeglimin counters cardiorenal dysfunction in a rat model of metabolic syndrome

INTRODUCTION

Imeglimin, a glucose-lowering agent targeting mitochondrial bioenergetics, decreases reactive oxygen species (ROS) overproduction and improves glucose homeostasis. We investigated whether this is associated with protective effects on metabolic syndrome-related left ventricular (LV) and vascular dysfunctions.

METHODS

We used Zucker fa/fa rats to assess the effects on LV function, LV tissue perfusion, LV oxidative stress and vascular function induced by imeglimin administered orally for 9 or 90 days at a dose of 150 mg/kg twice daily.

RESULTS

Compared to untreated animals, 9- and 90-day imeglimin treatment decreased LV end-diastolic pressure and LV end-diastolic pressure-volume relation, increased LV tissue perfusion and decreased LV ROS production. Simultaneously, imeglimin restored acetylcholine-mediated coronary relaxation and mesenteric flow-mediated dilation. One hour after imeglimin administration, when glucose plasma levels were not yet modified, imeglimin reduced LV mitochondrial ROS production and improved LV function. Ninety-day imeglimin treatment reduced related LV and kidney fibrosis and improved kidney function.

CONCLUSION

In a rat model, mimicking Human metabolic syndrome, imeglimin immediately countered metabolic syndrome-related cardiac diastolic and vascular dysfunction by reducing oxidative stress/increased NO bioavailability and improving myocardial perfusion and after 90-day treatment myocardial and kidney structure, effects that are, at least in part, independent from glucose control.

Effect of sodium glucose cotransporter 2 inhibitors on cardiac function and cardiovascular outcome: a systematic review

A high incidence of left ventricular diastolic dysfunction and increased risk of cardiovascular events have been reported in patients with diabetes mellitus. Sodium glucose cotransporter 2 (SGLT2) inhibitors selectively inhibit kidney glucose and sodium reabsorption, and cardiovascular benefits of SGLT2 inhibitors beyond other antidiabetic drugs have been reported in type 2 diabetes mellitus (T2DM) clinical trials. However, underlying mechanisms contributing to the improvement of cardiovascular outcomes have not been clearly identified. In this review, likely mechanisms of SGLT2 inhibitors contributing to a favorable cardiovascular outcomes are discussed based on experimental and clinical studies on cardiac function.

Left Ventricular Diastolic Dysfunction in Type 2 Diabetes-Progress and Perspectives

In-depth understanding of early cardiovascular manifestations in diabetes is high on international research and prevention agendas given that cardiovascular events are the leading cause of death for diabetic patients. Our aim was to review recent developments in the echocardiographic assessment of left ventricular diastolic dysfunction (LVDD) as a telltale pre-clinical disturbance preceding diabetic cardiomyopathy. We analyzed papers in which patients had been comprehensively assessed echocardiographically according to the latest LVDD guidelines (2016), and those affording comparisons with previous, widely used recommendations (2009). We found that the updated algorithm for LVDD is more effective in predicting adverse cardiovascular events in patients with established LVDD, and less specific in grading other patients (labelled "indeterminate"). This may prove instrumental for recruiting "indeterminate" LVDD cases among patients with type 2 diabetes mellitus (T2DM) in future screening programs. As an interesting consideration, the elevated values of the index E/e' can point to early diastolic impairment, foretelling diabetic cardiomyopathy. Identifying subclinical signs early makes clinical sense, but the complex nature of T2DM calls for further research. Specifically, longitudinal studies on rigorously selected cohorts of diabetic patients are needed to better understand and predict the subtle, slow onset of cardiac manifestations with T2DM as a complicating backdrop.

Left ventricular diastolic dysfunction in diabetes mellitus and the therapeutic role of exercise training

Abstract Left ventricular diastolic dysfunction (LVDD) with normal ejection fraction is considered common among people with diabetes mellitus (DM). LVDD is a progressive condition and an independent predictor of mortality in diabetic patients. The etiopathogenesis of LVDD is multifactorial, including diabetes associated comorbidities, such as hypertension, coronary atherosclerosis and obesity, as well as myocardial vascular and metabolic disturbances which lead to diabetic cardiomyopathy. Early stages of LVDD may be detected using echocardiographic techniques. Treatment strategies evolve, based on a better understanding of pathogenic mechanisms, although it is still difficult to efficiently control LVDD evolution. This review synthesizes the main pathophysiological processes and clinical features that characterize DM associated LVDD. Among treatment options, the therapeutic relevance of exercise training programs is underlined. Key words: diabetes mellitus, left ventricular diastolic dysfunction, physical training,