Empagliflozin Improves Left Ventricular Diastolic Dysfunction in a Genetic Model of Type 2 Diabetes

Purpose

Cardiovascular (CV) diseases in type 2 diabetes (T2DM) represent an enormous burden with high mortality and morbidity. Sodium-glucose cotransporter 2 (SGLT2) inhibitors have recently emerged as a new antidiabetic class that improves glucose control, as well as body weight and blood pressure with no increased risk of hypoglycemia. The first CV outcome study terminated with empagliflozin, a specific SGLT2 inhibitor, has shown a reduction in CV mortality and in heart failure hospitalization, suggesting a beneficial impact on cardiac function which remains to be demonstrated. This study was designed to examine the chronic effect of empagliflozin on left ventricular (LV) systolic and diastolic functions in a genetic model of T2DM, ob/ob mice.

Methods and Results

Cardiac phenotype was characterized by echocardiography, in vivo hemodynamics, histology, and molecular profiling. Our results demonstrate that empagliflozin significantly lowered HbA1c and slightly reduced body weight compared to vehicle treatment with no obvious changes in insulin levels. Empagliflozin also improved LV maximum pressure and in vivo indices of diastolic function. While systolic function was grossly not affected in both groups at steady state, response to dobutamine stimulation was significantly improved in the empagliflozin-treated group, suggesting amelioration of contractile reserve. This was paralleled by an increase in phospholamban (PLN) phosphorylation and increased SERCA2a/PLN ratio, indicative of enhanced SERCA2a function, further supporting improved cardiac relaxation and diastolic function. In addition, empagliflozin reconciled diabetes-associated increase in MAPKs and dysregulated phosphorylation of IRS1 and Akt, leading to improvement in myocardial insulin sensitivity and glucose utilization.

Conclusion

The data show that chronic treatment with empagliflozin improves diastolic function, preserves calcium handling and growth signaling pathways and attenuates myocardial insulin resistance in ob/ob mice, findings suggestive of a potential clinical utility for empagliflozin in the treatment of diastolic dysfunction.

     

抑制法尼基焦磷酸合成酶改善2型糖尿病大鼠左心室重构与心脏功能

目的探讨抑制法尼基焦磷酸合成酶对改善2型糖尿病大鼠左心室重构与心功能的影响。方法采用高脂高糖饮食加一次性腹腔注射小剂量链脲佐菌素(STZ 30mg/kg)建立2型糖尿病模型。健康雄性SD大鼠30只随机分成正常对照组(control组,n=10)、糖尿病组(DM组,n=10)、糖尿病+伊班膦酸钠组(DM+IB组,n=10)。建模成功后DM+IB组SD大鼠连续16周每天皮下注射5微克/千克剂量伊班膦酸钠溶液,control和DM组大鼠在相同位置注射相等剂量的0.9%氯化钠注射液。实验21周后分别对3组SD大鼠行心脏超声和血流动力学测定,HE染色观察心肌细胞形态横截面大小,Masson复合染色检测心肌组织胶原纤维沉积程度。结果与对照组相比,DM组大鼠左心室内径增大、室间隔及左心室后壁显著增厚、心功能降低、心肌细胞明显肥大、心肌间质及心肌血管周围胶原纤维沉积显著增多(P0.01);DM+IB组大鼠虽出现上述结构及功能改变,但与DM组相比上述情况均有明显改善(P0.05)。结论抑制法尼基焦磷酸合成酶在一定程度上可改善糖尿病心肌病大鼠左室重构与心脏功能。     

Alpha-Lipoic Acid Improves Subclinical Left Ventricular Dysfunction in Asymptomatic Patients with Type 1 Diabetes

BACKGROUND: Oxidative stress plays an important role in the development of diabetic cardiomyopathy. Alpha-lipoic acid (ALA) is a powerful antioxidant that may have a protective role in diabetic cardiac dysfunction. AIM: We investigated the possible beneficial effect of alpha-lipoic acid on diabetic left ventricular (LV) dysfunction in children and adolescents with asymptomatic type 1 diabetes (T1D). SUBJECTS AND METHODS: Thirty T1D patients (aged 10-14) were randomized to receive insulin treatment (n = 15) or insulin plus alpha-lipoic acid 300 mg twice daily (n = 15) for four months. Age and sex matched healthy controls (n = 15) were also included. Patients were evaluated with conventional 2-dimensional echocardiographic examination (2D), pulsed tissue Doppler (PTD), and 2-dimensional longitudinal strain echocardiography (2DS) before and after therapy. Glutathione, malondialdhyde (MDA), nitric oxide (NO), tumor necrosis factor-alpha (TNF-alpha), Fas ligand (Fas-L), matrix metalloproteinase 2 (MMP-2), and troponin-I were determined and correlated to echocardiographic parameters. RESULTS: Diabetic patients had significantly lower levels of glutathione and significantly higher MDA, NO, TNF-alpha, Fas-L, MMP-2, and troponin-I levels than control subjects. The expression of transforming growth factor beta (TGF-beta) mRNA in peripheral blood mononuclear cells was also increased in diabetic patients. Significant correlations of mitral e''/a'' ratio and left ventricular global peak systolic strain with glutathione, MDA, NO, TNF-alpha, and Fas-L were observed in diabetic patients. Alpha-lipoic acid significantly increased glutathione level and significantly decreased MDA, NO, TNF-alpha, Fas-L, MMP-2, troponin-I levels, and TGF-beta gene expression. Moreover, alpha-lipoic acid significantly increased mitral e''/a'' ratio and left ventricular global peak systolic strain in diabetic patients. CONCLUSION: These findings suggest that alpha-lipoic acid may have a role in preventing the development of diabetic cardiomyopathy in type 1 diabetes.     

2D and 3D Echocardiography of a Left Ventricular Diverticulum

A real time transthoracic 3D study of a left ventricular diverticulum established through a narrow orifice located between the aortic and mitral valves is presented. Diverticular morphology was reconstructed and its volumes were calculated by this technique for the first time in the literature.     

Subclinical Left Ventricular Longitudinal and Radial Systolic Dysfunction in Children and Adolescents with Type 1 Diabetes Mellitus

Introduction: There are few studies of subclinical systolic dysfunctions in children and adolescents with type 1 diabetes mellitus (DM), and so the available data are limited. The aim of this study was to determine early echocardiographic signs of LV systolic dysfunction in children and adolescents with type 1 DM using two‐dimensional speckle tracking echocardiography (2DSTE). Material and Methods: The study included 84 children and adolescents with type 1 DM and 32 sex‐, age‐, and body mass index–matched healthy subjects. The LV functions were assessed using conventional echocardiography, tissue Doppler imaging, and 2DSTE. Results: The results showed LV diastolic dysfunction as reflected by significantly increased A‐wave velocity, decreased E/A ratio, and increased early filling deceleration time in the patients with diabetes (P = 0.02, P = 0.029, and P = 0.04; respectively). Compared with the control group, patients with diabetes showed significantly lower values for longitudinal systolic strain and strain rate in most segments of the LV; for radial strain values of the LV; for lateral circumferential strain and posterior and anterolateral circumferential strain rate of the LV; and for global longitudinal and radial strain of the LV. Global longitudinal and radial strain values of the LV were significantly lower among patients with poor glycemic control than in the control group. Conclusion: In addition to diastolic dysfunction, LV longitudinal and radial function was found to be impaired in asymptomatic children and adolescents with type 1 DM who have normal LV ejection fraction by 2DSTE. Glycemic control may be the main risk factor for alteration of myocardial function.     

Rosuvastatin Alleviates Diabetic Cardiomyopathy by Inhibiting NLRP3 Inflammasome and MAPK Pathways in a Type 2 Diabetes Rat Model

Purpose

Nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome is important in inflammation of several diabetic complications. However, the potential role of NLRP3 inflammasome in the inflammatory process of diabetic cardiomyopathy (DCM) remains unclear. Although rosuvastatin (RSV) has an anti-inflammatory effect on some cardiovascular diseases, its influence on DCM is incompletely understood. We aimed to explore the effect on and underlying mechanism of RSV in DCM, and whether NLRP3 is a target for RSV.

Methods

Type 2 diabetes was induced in rat. The characteristics of type 2 DCM were evaluated by metabolic tests, echocardiography and histopathology. The expression of factors was determined by real-time RT-PCR and western blot. Eight-week RSV treatment and NLRP3 gene silencing were used to investigate the effect and underlying target of RSV in DCM.

Results

Compared with controls, diabetic rats showed severe metabolic disorder, cardiac dysfunction, fibrosis, disorganized ultrastructure, and excessive activation of thioredoxin interacting/inhibiting protein (TXNIP, p?<?0.05), NLRP3 inflammasome (NLRP3, p?<?0.01; apoptosis-associated speck-like protein containing a caspase recruitment domain [ASC], p?<?0.05; caspase-1, p?<?0.01), interleukin-1β (p?<?0.01) and mitogen-activated protein kinases (MAPKs, all p?<?0.01). Compared with diabetes alone, RSV ameliorated the overexpression of NLRP3 inflammasome (NLRP3, p?<?0.05; ASC, p?<?0.05; pro-caspase-1 p?<?0.05, caspase-1 p20, p?<?0.01) and MAPKs (all p?<?0.05), which paralleled the cardiac protection of RSV. Silencing NLRP3 ameliorated cardiac remodeling and dysfunction. The beneficial effects of RSV in vehicle-treated rats were all abrogated in NLRP3-silenced rats.

Conclusions

The beneficial effect of RSV on DCM depended on inhibited NLRP3 inflammasome, and correlated with suppression of the MAPKs.     

Docosahexaenoic Acid Supplementation Alters Key Properties of Cardiac Mitochondria and Modestly Attenuates Development of Left Ventricular Dysfunction in Pressure Overload-Induced Heart Failure

Purpose

Supplementation with the n3 polyunsaturated fatty acid docosahexaenoic acid (DHA) is beneficial in heart failure patients, however the mechanisms are unclear. DHA is incorporated into membrane phospholipids, which may prevent mitochondrial dysfunction. Thus we assessed the effects of DHA supplementation on cardiac mitochondria and the development of heart failure caused by aortic pressure overload.

Methods

Pathological cardiac hypertrophy was generated in rats by thoracic aortic constriction. Animals were fed either a standard diet or were supplemented with DHA (2.3 % of energy intake).

Results

After 14 weeks, heart failure was evident by left ventricular hypertrophy and chamber enlargement compared to shams. Left ventricle fractional shortening was unaffected by DHA treatment in sham animals (44.1?±?1.6 % vs. 43.5?±?2.2 % for standard diet and DHA, respectively), and decreased with heart failure in both treatment groups, but to a lesser extent in DHA treated animals (34.9?±?1.7 %) than with the standard diet (29.7?±?1.5 %, P?<?0.03). DHA supplementation increased DHA content in mitochondrial phospholipids and decreased membrane viscosity. Myocardial mitochondrial oxidative capacity was decreased by heart failure and unaffected by DHA. DHA treatment enhanced Ca²⁺ uptake by subsarcolemmal mitochondria in both sham and heart failure groups. Further, DHA lessened Ca²⁺-induced mitochondria swelling, an index of permeability transition, in heart failure animals. Heart failure increased hydrogen peroxide-induced mitochondrial permeability transition compared to sham, which was partially attenuated in interfibrillar mitochondria by treatment with DHA.

Conclusions

DHA decreased mitochondrial membrane viscosity and accelerated Ca²⁺ uptake, and attenuated susceptibility to mitochondrial permeability transition and development of left ventricular dysfunction.     

Left Bundle Branch Block in Type 2 Diabetes Mellitus: A Sign of Advanced Cardiovascular Involvement

Objective: To evaluate left bundle branch block (LBBB) as an indicator of advanced cardiovascular involvement in diabetic (DM) patients by examining left ventricular systolic function and proteinurea. Methods: Data of 26 diabetic patients with left bundle branch block (DM with LBBB) were compared with data of 31 diabetic patients without left bundle branch block (DM without LBBB) and 18 nondiabetic patients with left bundle branch block (non‐DM with LBBB). The inclusion criteria were age >45 years, and diabetes mellitus type 2 of >5 years. Results: Mean ages of patients in DM with LBBB, DM without LBBB, and non‐DM with LBBB groups were 67 ± 8, 68 ± 10, and 65 ± 10 years, respectively (P = NS). Females were 65%, 61%, and 61%, respectively (P = NS). Left ventricular ejection fraction in DM with LBBB was significantly lower than in DM without LBBB and non‐DM with LBBB (30 ± 10% vs 49 ± 12% and 47 ± 8%, P < 0.01). Left ventricular end‐diastolic volume was significantly higher in DM with LBBB than in DM without LBBB and non‐DM with LBBB (188.6 ± 16.4 mL vs 147.5 ± 22.3 mL and 165.3 ± 15.2 mL, P < 0.03). Similarly, left ventricular end‐systolic volume was significantly higher in DM with LBBB than in DM without LBBB and non‐DM with LBBB (135.4 ± 14.7 mL vs 83.7 ± 9.5 mL and 96.6 ± 18.4 mL, P < 0.02). No statistically significant difference was seen in left atrial size. Proteinurea in DM with LBBB (79.4 ± 18.9 mg/dL) was significantly higher than in DM without LBBB (35.6 ± 8.5 mg/dL, P < 0.05) and non‐DM with LBBB (12 ± 3.5 mg/dL, P < 0.05); however, there was no significant difference in Hb A1c levels in DM with LBBB and DM without LBBB (9.01% vs 7.81%, P = NS). Conclusions: Left bundle branch block in diabetic patients indicates advanced cardiovascular involvement manifesting with more severe left ventricular systolic dysfunction and proteinurea compared to both diabetic patients without left bundle branch block and nondiabetic patients with left bundle branch block.     

Left Ventricular Diastolic Dysfunction in Type I Gaucher Disease: An Echo Doppler Study

Type I Gaucher disease (GD1) is an autosomal recessive lysosomal storage disease characterized by multiorgan damage. Left ventricular (LV) involvement has been rarely reported. Accordingly, the aim of the study was to evaluate LV geometry and function in a series of patients with GD1. Eighteen patients with GD1, 18 age‐ and sex‐matched normal controls, and 18 age‐ and sex‐matched hypertensive patients (HTN) were compared by standard echo Doppler examination. LV mass index, relative wall thickness and ejection fraction, transmitral E/A ratio, E velocity deceleration time (DT), atrial filling fraction (AFF = time‐velocity integral of A velocity/time‐velocity integral of total diastole × 100), E/e′ ratio, and left atrial volume index were determined. Nine GD1 patients also exhibited arterial hypertension. The intergroup difference of LV mass index and relative wall thickness was not significant. Transmitral E/A ratio was lower in HTN than in normal controls and GD1 (P < 0.05). GD1 exhibited longer DT than NC and HTN (P = 0.009). AFF was higher in GD1 and HTN compared to NC (P = 0.034). After adjustment for heart rate, GD1 was associated with longer DT (P < 0.001) and greater AFF (P = 0.036), while HTN was associated only with AFF (P = 0.013). No interaction was found between GD1 and HTN. In conclusion, GD1 is associated with subclinical LV diastolic dysfunction, which is independent of the coexistence of arterial hypertension. Subclinical LV impaired relaxation in the context of myocardial infiltrative damage could be the mechanism underlying these alterations.     

Prevalence of Left Ventricular Systolic Dysfunction in Myotonic Dystrophy Type 1: A Systematic Review

Cardiac involvement is recorded in about 80% of patients affected by myotonic dystrophy type 1 (DM1). The prevalence of cardiac conduction abnormalities and arrhythmias has been well described. Data regarding the prevalence of left ventricle systolic dysfunction (LVSD) and heart failure (HF) are still conflicting. The primary objective of this review was to assess the prevalence of LVSD and HF in DM1. The secondary aim was to examine the association of clinical features with LVSD and to detect predisposing and influencing prognosis factors. A systematic search was developed in MEDLINE, EMBASE, Cochrane Register of Controlled Trials, and Web of Science databases to identify original reports between January 1, 2009, and September 30, 2017, assessing the prevalence of LVSD and HF in populations with DM1. Retrospective and prospective cohort studies and case series describing the prevalence of LVSD, as evaluated by echocardiography, and HF in patients with DM1 were included. Case reports, simple reviews, commentaries and editorials were excluded. Seven studies were identified as eligible, of which 1 was a retrospective population-based cohort study, and 6 were retrospective single-center-based cohort studies. Echocardiographic data concerning LV function were available for 647 of the 876 patients with DM1 who were included in the analysis. The prevalence of LVSD in patients with DM1, defined as LVEF < 55%, was 13.8%, 4.5-fold higher than in general population. Patients with DM1 and LVSD were older, were more likely to be male, had longer baseline atrioventricular and intraventricular conduction-time durations, had higher incidences of atrial arrhythmias, and were more likely to have undergone device implantation. Also, symptomatic HF is more prevalent in patients with DM1 despite their limited levels of physical activity. Further studies are needed to evaluate the prevalence of LVSD and HF in patients with DM1 and to investigate electrocardiographic abnormalities and other clinical features associated with this condition.     

The Role of Adipose Tissue and Lipotoxicity in the Pathogenesis of Type 2 Diabetes

The widespread epidemics of obesity and type 2 diabetes mellitus (T2DM) suggest that both conditions are closely linked. An increasing body of evidence has shifted our view of adipose tissue from a passive energy depot to a dynamic “endocrine organ” that tightly regulates nutritional balance by means of a complex crosstalk of adipocytes with their microenvironment. Dysfunctional adipose tissue, particularly as observed in obesity, is characterized by adipocyte hypertrophy, macrophage infiltration, impaired insulin signaling, and insulin resistance. The result is the release of a host of inflammatory adipokines and excessive amounts of free fatty acids that promote ectopic fat deposition and lipotoxicity in muscle, liver, and pancreatic β cells. This review focuses on recent work on how glucose homeostasis is profoundly altered by distressed adipose tissue. A better understanding of this relationship offers the best chance for early intervention strategies aimed at preventing the burden of T2DM.