[Echocardiography in diabetic cardiomyopathy]

Application of three-dimensional speckle tracking technique in measuring left ventricular myocardial function in patients with diabetes

BACKGROUND

Diabetic cardiomyopathy is considered as a chronic complication of diabetes mellitus (DM). Therefore, early detection of left ventricular systolic function (LVSF) damage in DM is essential.

AIM

To explore the use of the three-dimensional speckle tracking technique (3D-STI) for measuring LVSF in DM patients via meta-analysis.

METHODS

The electronic databases were retrieved from the initial accessible time to 29 April 2023. The current study involved 9 studies, including 970 subjects. We carried out this meta-analysis to estimate myocardial function in DM compared with controls according to myocardial strain attained by 3D-STI.

RESULTS

Night articles including 970 subjects were included. No significant difference was detected in the left ventricular ejection fraction between the control and the diabetic group (P > 0.05), while differences in global longitudinal strain, global circumferential strain, global radial strain, and global area strain were markedly different between the controls and DM patients (all P < 0.05).

CONCLUSION

The 3D-STI could be applied to accurately measure early LVSF damage in patients with DM.

Animal Models of Type 2 Diabetes Complications: A Review

Diabetes mellitus is a multifactorial metabolic disease, of which type 2 diabetes (T2D) is one of the most common. The complications of diabetes are far more harmful than diabetes itself. Type 2 diabetes complications include diabetic nephropathy (DN), diabetic heart disease, diabetic foot ulcers (DFU), diabetic peripheral neuropathy (DPN), and diabetic retinopathy (DR) et al. Many animal models have been developed to study the pathogenesis of T2D and discover an effective strategy to treat its consequences. In this sense, it is crucial to choose the right animal model for the corresponding diabetic complication. This paper summarizes and classifies the animal modeling approaches to T2D complications and provides a comprehensive review of their advantages and disadvantages. It is hopeful that this paper will provide theoretical support for animal trials of diabetic complications.

Hyperglycemia promotes myocardial dysfunction via the ERS-MAPK10 signaling pathway in db/db mice

Recent studies have demonstrated that hyperglycemia is a major risk factor for the development and exacerbation of cardiovascular disease (CVD). However, the molecular mechanisms involved in diabetic cardiomyopathy (DCM) have not been fully elucidated. In this study, we focused on the underlying mechanism of DCM. Leptin receptor-deficient db/db mice were used to model a type 2 diabetes mellitus (T2DM) model in our study. WT mice and db/db mice received 4-phenylbutyric acid (4-PBA) (25 mg/kg/day) and saline by intraperitoneal injection every other day for 4 weeks. WT and db/db mice were given tail vein injections of 100 μL of rAAV9-Sh-MAPK10 and rAAV9-Sh-GFP at the age of 6-8 weeks. Echocardiography was performed to measure cardiac function, histological examinations were used to evaluate ventricular hypertrophy and fibrosis. Quantitative RT-qPCR was used to assess the mRNA expression of Jun N-terminal kinase 3 (JNK3, MAPK10), atrial natriuretic factor (ANF), brain natriuretic peptide (BNP), and collagen I and III. Immunoblotting was performed to measure the levels of cardiac hypertrophy-related proteins, fibrosis-related proteins, endoplasmic reticulum stress (ERS)-related proteins and apoptosis-related proteins. TUNEL staining was performed to examine cardiomyocyte apoptosis. In contrast to 12-week-old db/db mice, 16-week-old db/db mice showed the most severe myocardial dysfunction. The DCM induced by hyperglycemia was largely alleviated by 4-PBA (25 mg/kg/day, intraperitoneal injection). Similarly, tail vein injection of rAAV9-Sh-MAPK10 reversed the phenotype of the heart in db/db mice including cardiac hypertrophy and apoptosis in db/db mice. The mechanistic findings suggested that hyperglycemia initiated the ERS response through the negative regulation of sirtuin 1 (SIRT1), leading to the occurrence of myocardial dysfunction, and specific knockdown of MAPK10 in the heart directly reversed myocardial dysfunction induced by hyperglycemia. We demonstrated that hyperglycemia promotes DCM in db/db mice through the ERS-MAPK10 signaling pathway in diabetic mice.

Ectopic accumulation of ceramide in cardiomyocytes modulates alcoholic cardiomyopathy via the TLR4-dependent pathway

BACKGROUND AND AIMS

Excessive alcohol consumption predisposes drinkers to develop alcoholic cardiomyopathy. Although cardiomyocyte loss is the hallmark of cardiomyopathy, the underlying mechanism remains elusive. This study examined the potential mechanism of alcohol-induced cardiomyocyte death in a mouse model of alcoholic cardiomyopathy.

METHODS

We established the alcoholic cardiomyopathy mouse model using C57BL/6J mice and confirmed it via echocardiography and histological examination. The cardiac ceramide content and profile were analyzed with a triple-quadrupole mass spectrometer. The molecular mechanism underlying the accumulation of ceramide due to chronic alcohol consumption and ceramide-induced cardiomyocyte death were investigated by in vivo and in vitro models. Finally, we established a TLR4 mutation model to explore the function of TLR4 in CH3/HeJ mice.

RESULTS

Cardiac lipotoxicity that followed alcohol exposure resulted mainly in C16:0-, C18:0-, and C24:1-ceramide aggregation. Genes encoding the sphingosine hydrolysis enzymes (SMPD1 and SMPD2) rather than de novo synthetic biomarkers were markedly upregulated. Exogenous ceramide mimics (C6-ceramide) werenderlying the accumulation of ceramide observed to cause H9C2 cardiomyocyte-like cell death, which was consistent with results under palmate acid (PA) treatment. As a ceramide precursor, PA induces intracellular ceramide generation through TLR4 signaling, which can be abolished by an inhibitor of ceramide synthesis. Furthermore, mechanistic investigations demonstrated that pharmacological or genetic inhibition of TLR4 attenuated PA-induced cell death and corresponding ceramide production. Moreover, global mutation of TLR4 in CH3/HeJ mice significantly reduced the accumulation of C24:0, C24:1, OH_C24:1, and total ceramide following alcohol challenge.

CONCLUSIONS

Our findings demonstrate that ceramide accumulation plays a crucial role in alcoholic cardiomyopathy, effects that are partially mediated through the TLR4-dependent pathway.

H2S attenuates the myocardial fibrosis in diabetic rats through modulating PKC-ERK1/2MAPK signaling pathway

OBJECTIVE

To investigate the roles and underlying mechanism of exogenous H2S (hydrogen sulfide) in attenuating the myocardial fibrosis in diabetic rats.

METHODS:

A total of 40 SD rats were randomly divided into 4 groups: control group, STZ group, STZ + H2S group and H2S group. To build the DM rat model , the rats in the STZ group and STZ + H2S group were injected streptozotocin (STZ) intraperitoneally, While the rats in the STZ + H2S group and the H2S group received sodium hydrosulfide (NaHS), which provides exogenous H2S. Eight weeks later, the myocardial tissues of rats were used to detecting the collagen deposition through Masson staining, as well as some protein expressions related to myocardial fibrosis and signaling pathway by western blotting.

RESULTS:

Comparing to control group, the collagen deposition of myocardial matrix remarkably increased in the STZ group, and almost all the proteins that are relative to myocardial fibrosis, inflammatory and signaling pathway show an overexpression, except for PPARG and NF-κBp65. When Compared with the STZ group, the collagen deposition was obviously attenuated in STZ + H2S group, as well as the protein expressions above-mentioned, While PPARG was up-regulated.

CONCLUSION:

The myocardial fibrosis in DM rats can be attenuated effectively by exogenous H2S, and the underlying mechanism is likely to regulating PKC-ERK1/2MAPK signaling pathway, improving the MMPs/TIMPs expression dysregulation and inhibiting inflammatory reaction.

Annexin A1 attenuates microvascular complications through restoration of Akt signalling in a murine model of type 1 diabetes

AIMS/HYPOTHESIS

Microvascular complications in the heart and kidney are strongly associated with an overall rise in inflammation. Annexin A1 (ANXA1) is an endogenous anti-inflammatory molecule that limits and resolves inflammation. In this study, we have used a bedside to bench approach to investigate: (1) ANXA1 levels in individuals with type 1 diabetes; (2) the role of endogenous ANXA1 in nephropathy and cardiomyopathy in experimental type 1 diabetes; and (3) whether treatment with human recombinant ANXA1 attenuates nephropathy and cardiomyopathy in a murine model of type 1 diabetes.

METHODS

ANXA1 was measured in plasma from individuals with type 1 diabetes with or without nephropathy and healthy donors. Experimental type 1 diabetes was induced in mice by injection of streptozotocin (STZ; 45 mg/kg i.v. per day for 5 consecutive days) in C57BL/6 or Anxa1 -/- mice. Diabetic mice were treated with human recombinant (hr)ANXA1 (1 μg, 100 μl, 50 mmol/l HEPES; 140 mmol/l NaCl; pH 7.4, i.p.) or vehicle (100 μl, 50 mmol/l HEPES; 140 mmol/l NaCl; pH 7.4, i.p.).

RESULTS

Plasma levels of ANXA1 were elevated in individuals with type 1 diabetes with/without nephropathy compared with healthy individuals (66.0 ± 4.2/64.0 ± 4 ng/ml vs 35.9 ± 2.3 ng/ml; p < 0.05). Compared with diabetic wild-type (WT) mice, diabetic Anxa1 -/- mice exhibited a worse diabetic phenotype and developed more severe cardiac (ejection fraction; 76.1 ± 1.6% vs 49.9 ± 0.9%) and renal dysfunction (proteinuria; 89.3 ± 5.0 μg/mg vs 113.3 ± 5.5 μg/mg). Mechanistically, compared with non-diabetic WT mice, the degree of the phosphorylation of mitogen-activated protein kinases (MAPKs) p38, c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) was significantly higher in non-diabetic Anxa1 -/- mice in both the heart and kidney, and was further enhanced after STZ-induced type 1 diabetes. Prophylactic treatment with hrANXA1 (weeks 1-13) attenuated both cardiac (ejection fraction; 54.0 ± 1.6% vs 72.4 ± 1.0%) and renal (proteinuria; 89.3 ± 5.0 μg/mg vs 53.1 ± 3.4 μg/mg) dysfunction associated with STZ-induced diabetes, while therapeutic administration of hrANXA1 (weeks 8-13), after significant cardiac and renal dysfunction had already developed, halted the further functional decline in cardiac and renal function seen in diabetic mice administered vehicle. In addition, administration of hrANXA1 attenuated the increase in phosphorylation of p38, JNK and ERK, and restored phosphorylation of Akt in diabetic mice.

CONCLUSIONS/INTERPRETATION

Overall, these results demonstrate that ANXA1 plasma levels are elevated in individuals with type 1 diabetes independent of a significant impairment in renal function. Furthermore, in mouse models with STZ-induced type 1 diabetes, ANXA1 protects against cardiac and renal dysfunction by returning MAPK signalling to baseline and activating pro-survival pathways (Akt). We propose ANXA1 to be a potential therapeutic option for the control of comorbidities in type 1 diabetes.

[Stress dobutamine echocardiography or resting strain rate imaging to unveil an early symptomatic diabetic cardiomyopathy?]

Diabetes mellitus has been associated with changes in the structure and function of the myocardium manifesting in the early stages of the disease as subtle systolic and diastolic dysfunction; myocardial strain imaging has recently been favored over dobutamine stress echocardiography for early detection of diabetic cardiomyopathy. We report a case of an elderly diabetic patient presenting with pulmonary edema in whom at rest echocardiographic parameters including strain rate were all within normal range, while dobutamine stress echocardiography induced a deep systolic deterioration unmasking an early-stage diabetic cardiomyopathy.

Updating experimental models of diabetic cardiomyopathy

Diabetic cardiomyopathy entails a serious cardiac dysfunction induced by alterations in structure and contractility of the myocardium. This pathology is initiated by changes in energy substrates and occurs in the absence of atherothrombosis, hypertension, or other cardiomyopathies. Inflammation, hypertrophy, fibrosis, steatosis, and apoptosis in the myocardium have been studied in numerous diabetic experimental models in animals, mostly rodents. Type I and type II diabetes were induced by genetic manipulation, pancreatic toxins, and fat and sweet diets, and animals recapitulate the main features of human diabetes and related cardiomyopathy. In this review we update and discuss the main experimental models of diabetic cardiomyopathy, analysing the associated metabolic, structural, and functional abnormalities, and including current tools for detection of these responses. Also, novel experimental models based on genetic modifications of specific related genes have been discussed. The study of specific pathways or factors responsible for cardiac failures may be useful to design new pharmacological strategies for diabetic patients.