Diabetic cardiomyopathy. Clin Sci (Lond). 2009;116:741-760. [PMID: 19364331 PMCID: PMC2782307 DOI: 10.1042/cs20080500]

Effect of advanced glycation end-products in a wide range of medical problems including COVID-19

Glycation is a physiological process that determines the aging of the organism, while in states of metabolic disorders it is significantly intensified. High concentrations of compounds such as reducing sugars or reactive aldehydes derived from lipid oxidation, occurring for example in diabetes, atherosclerosis, dyslipidemia, obesity or metabolic syndrome, lead to increased glycation of proteins, lipids and nucleic acids. The level of advanced glycation end-products (AGEs) in the body depends on rapidity of their production and the rate of their removal by the urinary system. AGEs, accumulated in the extracellular matrix of the blood vessels and other organs, cause irreversible changes in the biochemical and biomechanical properties of tissues. As a consequence, micro- and macroangiopathies appear in the system, and may contribute to the organ failure, like kidneys and heart. Elevated levels of AGEs also increase the risk of Alzheimer's disease and various cancers. In this paper, we propose a new classification due to modified amino acid residues: arginyl-AGEs, monolysyl-AGEs and lysyl-arginyl-AGEs and dilysyl-AGEs. Furthermore, we describe in detail the effect of AGEs on the pathogenesis of metabolic and old age diseases, such as diabetic complications, atherosclerosis and neurodegenerative diseases. We summarize the currently available data on the diagnostic value of AGEs and present the AGEs as a therapeutic goal in a wide range of medical problems, including SARS-CoV-2 infection and so-called long COVID.

GDF11 mitigates high glucose-induced cardiomyocytes apoptosis by inhibiting the ALKBH5-FOXO3-CDR1as/Hippo signaling pathway

Diabetic cardiomyopathy remains a formidable health challenge with a high mortality rate and no targeted treatments. Growth differentiation factor 11 (GDF11) has shown promising effects on cardiovascular diseases; however, its role and the underlying mechanism in regulating diabetic cardiomyopathy remain unclear. In this study, we developed mouse models of diabetic cardiomyopathy using leptin receptor-deficient (db/db) mice and streptozocin-induced C57BL/6 mice. The diabetic cardiomyopathy model mice exhibited apparent structural damage in cardiac tissues and a significant increase in the expression of apoptosis-related proteins. Notably, we observed a significant decreased expression of GDF11 in the myocardium of mice with diabetic cardiomyopathy. Moreover, GDF11 cardiac-specific knock-in mice (transgenic mice) exhibited improved cardiac function and reduced apoptosis. Moreover, exogenous administration of GDF11 mitigated high glucose-induced cardiomyocyte apoptosis. Mechanistically, we demonstrated that GDF11 alleviated high glucose-induced cardiomyocytes apoptosis by inhibiting the activation of the alkylation repair homolog 5 (ALKBH5)-forkhead box group O3a (FOXO3)-cerebellar degeneration-related protein 1 transcript (CDR1as)/Hippo signaling pathway. Consequently, this novel mechanism effectively counteracted myocardial cell apoptosis, providing valuable insights into potential therapeutic strategies for clinical diabetic cardiomyopathy.

Efficacy of adipose-derived mesenchymal stem cell therapy in the treatment of chronic micro- and macrovascular complications of diabetes

Diabetes mellitus is a highly prevalent disease characterized by hyperglycaemia that damages the vascular system, leading to micro- (retinopathy, neuropathy, nephropathy) and macrovascular diseases (cardiovascular disease). There are also secondary complications of diabetes (cardiomyopathy, erectile dysfunction or diabetic foot ulcers). Stem cell-based therapies have become a promising tool targeting diabetes symptoms and its chronic complications. Among all stem cells, adipose-derived mesenchymal stem cells (ADMSCs) are of great importance because of their abundance, non-invasive isolation and no ethical limitations. Characteristics that make ADMSCs good candidates for cell-based therapy are their wide immunomodulatory properties and paracrine activities through the secretion of an array of growth factors, chemokines, cytokines, angiogenic factors and anti-apoptotic molecules. Besides, after transplantation, ADMSCs show great ex vivo expansion capacity and differentiation to other cell types, including insulin-producing cells, cardiomyocytes, chondrocytes, hepatocyte-like cells, neurons, endothelial cells, photoreceptor-like cells, or astrocytes. Preclinical studies have shown that ADMSC-based therapy effectively improved visual acuity, ameliorated polyneuropathy and foot ulceration, arrested the development and progression of diabetic kidney disease, or alleviated the diabetes-induced cardiomyocyte hypertrophy. However, despite the positive results obtained in animal models, there are still several challenges that need to be overcome before the results of preclinical studies can be translated into clinical applications. To date, there are several clinical trials or ongoing trials using ADMSCs in the treatment of diabetic complications, most of them in the treatment of diabetic foot ulcers. This narrative review summarizes the most recent outcomes on the usage of ADMSCs in the treatment of long-term complications of diabetes in both animal models and clinical trials.

A review of the conservative versus invasive management of ischemic heart failure with reduced ejection fraction

Heart failure is increasing in terms of prevalence, morbidity, and mortality rates. Clinical trials and studies are focusing on heart failure as it is the destiny end-stage for several cardiovascular disorders. Recently, medical therapy has dramatically progressed with novel classes of medicines providing better quality of life and survival outcomes. However, heart failure remains a heavy impactful factor on societies and populations. Current guidelines from the American and European cardiac societies are not uniform with respect to the class and level of treatment recommendations for coronary artery disease patients with heart failure and reduced ejection fraction. The discrepancy among international recommendations, stemming from the lack of evidence from adequately powered randomized trials, challenges physicians in choosing the optimal strategy. Hybrid therapy including optimal medical therapy with revascularization strategies are commonly used for the management of ischemic heart failure. Coronary artery bypass graft (CABG) has proved its efficacy on improving long term outcome and prognosis while no large randomized clinical trials for percutaneous coronary intervention (PCI) are still available. Regardless of the lack of data and recommendations, the trends of performing PCI in ischemic heart failure prevailed over CABG whereas lesion complexity, chronic total occlusion and complete revascularization achievement are limiting factors. Lastly, regenerative medicine seems a promising approach for advanced heart failure enhancing cardiomyocytes proliferation, reverse remodeling, scar size reduction and cardiac function restoration.

Ketogenic Diet Regulates Cardiac Remodeling and Calcium Homeostasis in Diabetic Rat Cardiomyopathy

A ketogenic diet (KD) might alleviate patients with diabetic cardiomyopathy. However, the underlying mechanism remains unclear. Myocardial function and arrhythmogenesis are closely linked to calcium (Ca2+) homeostasis. We investigated the effects of a KD on Ca2+ homeostasis and electrophysiology in diabetic cardiomyopathy. Male Wistar rats were created to have diabetes mellitus (DM) using streptozotocin (65 mg/kg, intraperitoneally), and subsequently treated for 6 weeks with either a normal diet (ND) or a KD. Our electrophysiological and Western blot analyses assessed myocardial Ca2+ homeostasis in ventricular preparations in vivo. Unlike those on the KD, DM rats treated with an ND exhibited a prolonged QTc interval and action potential duration. Compared to the control and DM rats on the KD, DM rats treated with an ND also showed lower intracellular Ca2+ transients, sarcoplasmic reticular Ca2+ content, sodium (Na+)-Ca2+ exchanger currents (reverse mode), L-type Ca2+ contents, sarcoplasmic reticulum ATPase contents, Cav1.2 contents. Furthermore, these rats exhibited elevated ratios of phosphorylated to total proteins across multiple Ca2+ handling proteins, including ryanodine receptor 2 (RyR2) at serine 2808, phospholamban (PLB)-Ser16, and calmodulin-dependent protein kinase II (CaMKII). Additionally, DM rats treated with an ND demonstrated a higher frequency and incidence of Ca2+ leak, cytosolic reactive oxygen species, Na+/hydrogen-exchanger currents, and late Na+ currents than the control and DM rats on the KD. KD treatment may attenuate the effects of DM-dysregulated Na+ and Ca2+ homeostasis, contributing to its cardioprotection in DM.

Microvascular arterial disease of the brain and the heart: a shared pathogenesis

Microvascular arterial disease in the heart manifest as coronary microvascular dysfunction. This condition causes microvascular angina and is associated increased morbidity and mortality. Microvascular arterial disease in the brain is referred to as cerebrovascular small vessel disease. This is responsible for 45% of dementias and 25% of ischaemic strokes. The heart and brain share similar vascular anatomy and common pathogenic risk factors are associated with the development of both coronary microvascular dysfunction and cerebrovascular small vessel disease. Microvascular disease in the heart and brain also appear to share common multisystem pathophysiological mechanisms. Further studies on diagnostic approaches, epidemiology and development of disease-modifying therapy seem warranted.

Knowledge domain and emerging trends in diabetic cardiomyopathy: A scientometric review based on CiteSpace analysis

Objective

To review the literature related to diabetic cardiomyopathy (DCM), and investigate research hotspots and development trends of this field in the relevant studies based on CiteSpace software of text mining and visualization in scientific literature.

Methods

The relevant literature from the last 20 years was retrieved from the Web of Science (WoS) Core Collection database. After manual selection, each document record includes title, authors, year, organization, abstract, keywords, citation, descriptors, and identifiers. We imported the downloaded data into CiteSpace V (version 5.8.R2) to draw the knowledge map and conduct cooperative network analysis, cluster analysis, burst keyword analysis, and co-citation analysis.

Results

After manual screening, there were 3,547 relevant pieces of literature published in the last 18 years (from 2004 to 2021), including 2,935 articles and reviews, which contained 15,533 references, and the number was increasing year by year. The publications of DCM were dedicated by 778 authors of 512 institutions in 116 countries. The People's Republic of China dominated this field (1,117), followed by the USA (768) and Canada (176). In general, most articles were published with a focus on “oxidative stress,” “heart failure,” “diabetic cardiomyopathy,” “dysfunction,” “cardiomyopathy,” “expression,” “heart,” “mechanism,” and “insulin resistance.” Then, 10 main clusters were generated with a modularity Q of 0.6442 and a weighted mean silhouette of 0.8325 by the log-likelihood ratio (LLR) algorithm, including #0 heart failure, #1 perfused heart, #2 metabolic disease, #3 protective effect, #4 diabetic patient, #5 cardiac fibrosis, #6 vascular complication, #7 mitochondrial dynamics, #8 sarcoplasmic reticulum, and #9 zinc supplementation. The top five references with the strongest citation bursts include “Boudina and Abel”, “Jia et al.”, “Fang et al.”, “Poornima et al.”, and “Aneja et al.”.

Conclusion

The global field of DCM has expanded in the last 20 years. The People's Republic of China contributes the most. However, there is little cooperation among authors and institutions. Overall, this bibliometric study identified the hotspots in DCM research, including “stress state,” “energy metabolism,” “autophagy,” “apoptosis,” “inflammation,” “fibrosis,” “PPAR,” etc. Thus, further research focuses on these topics that may be more helpful to identify, prevent DCM and improve prophylaxis strategies to bring benefit to patients in the near future.

Role of TSPO/VDAC1 Upregulation and Matrix Metalloproteinase-2 Localization in the Dysfunctional Myocardium of Hyperglycaemic Rats

Clinical management of diabetic cardiomyopathy represents an unmet need owing to insufficient knowledge about the molecular mechanisms underlying the dysfunctional heart. The aim of this work is to better clarify the role of matrix metalloproteinase 2 (MMP-2) isoforms and of translocator protein (TSPO)/voltage-dependent anion-selective channel 1 (VDAC1) modulation in the development of hyperglycaemia-induced myocardial injury. Hyperglycaemia was induced in Sprague-Dawley rats through a streptozocin injection (35 mg/Kg, i.p.). After 60 days, cardiac function was analysed by echocardiography. Nicotinamide Adenine Dinucleotide Phosphate NADPH oxidase and TSPO expression was assessed by immunohistochemistry. MMP-2 activity was detected by zymography. Superoxide anion production was estimated by MitoSOX™ staining. Voltage-dependent anion-selective channel 1 (VDAC-1), B-cell lymphoma 2 (Bcl-2), and cytochrome C expression was assessed by Western blot. Hyperglycaemic rats displayed cardiac dysfunction; this response was characterized by an overexpression of NADPH oxidase, accompanied by an increase of superoxide anion production. Under hyperglycaemia, increased expression of TSPO and VDAC1 was detected. MMP-2 downregulated activity occurred under hyperglycemia and this profile of activation was accompanied by the translocation of intracellular N-terminal truncated isoform of MMP-2 (NT-MMP-2) from mitochondria-associated membrane (MAM) into mitochondria. In the onset of diabetic cardiomyopathy, mitochondrial impairment in cardiomyocytes is characterized by the dysregulation of the different MMP-2 isoforms. This can imply the generation of a “frail” myocardial tissue unable to adapt itself to stress.

Diabetic cardiomyopathy: molecular mechanisms, detrimental effects of conventional treatment, and beneficial effects of natural therapy

ABSTARCT

Diabetic complications are among the largely exigent health problems currently. Cardiovascular complications, including diabetic cardiomyopathy (DCM), account for more than 80% of diabetic deaths. Investigators are exploring new therapeutic targets to slow or abate diabetes because of the growing occurrence and augmented risk of deaths due to its complications. Research on rodent models of type 1 and type 2 diabetes mellitus, and the use of genetic engineering techniques in mice and rats have significantly sophisticated for our understanding of the molecular mechanisms in human DCM. DCM is featured by pathophysiological mechanisms that are hyperglycemia, insulin resistance, oxidative stress, left ventricular hypertrophy, damaged left ventricular systolic and diastolic functions, myocardial fibrosis, endothelial dysfunction, myocyte cell death, autophagy, and endoplasmic reticulum stress. A number of molecular and cellular pathways, such as cardiac ubiquitin proteasome system, FoxO transcription factors, hexosamine biosynthetic pathway, polyol pathway, protein kinase C signaling, NF-κB signaling, peroxisome proliferator-activated receptor signaling, Nrf2 pathway, mitogen-activated protein kinase pathway, and micro RNAs, play a major role in DCM. Currently, there are a few drugs for the management of DCM and some of them have considerable adverse effects. So, researchers are focusing on the natural products to ameliorate it. Hence, in this review, we discuss the pathogical, molecular, and cellular mechanisms of DCM; the current diagnostic methods and treatments; adverse effects of conventional treatment; and beneficial effects of natural product-based therapeutics, which may pave the way to new treatment strategies. Graphical Abstract.

The additive effects of obesity on myocardial microcirculation in diabetic individuals: a cardiac magnetic resonance first-pass perfusion study

BACKGROUND

The microvascular effects of obesity should be considered in diabetic individuals for elucidating underlying mechanisms and developing targeted therapies. This study aims to determine the effect of obesity on myocardial microvascular function in type 2 diabetes mellitus (T2DM) patients using cardiac magnetic resonance (CMR) first-pass perfusion imaging and assessed significant risk factors for microvascular dysfunction.

MATERIALS AND METHODS

Between September 2016 and May 2018, 120 patients with T2DM (45.8% women [55 of 120]; mean age, 56.45 ± 11.97 years) and 79 controls (44.3% women [35 of 79]; mean age, 54.50 ± 7.79 years) with different body mass index (BMI) scales were prospectively enrolled and underwent CMR examination. CMR-derived perfusion parameters, including upslope, time to maximum signal intensity (TTM), maximum signal intensity (MaxSI), MaxSI (-baseline), and SI (baseline), and T2DM related risk factors were analyzed among groups/subgroups both in T2DM patients and controls. Univariable and multivariable linear and logistic regression analyses were performed to assess the potential additive effect of obesity on microvascular dysfunction in diabetic individuals.

RESULTS

Compared with controls with comparable BMIs, patients with T2DM showed reduced upslope and MaxSI and increased TTM. For both T2DM and control subgroups, perfusion function gradually declined with increasing BMI, which was confirmed by all perfusion parameters, except for TTM (all P < 0.01). In multivariable linear regression analysis, BMI (β = - 0.516; 95% confidence interval [CI], - 0.632 to - 0.357; P < 0.001), female sex (β = 0.372; 95% CI, 0.215 to 0.475; P < 0.001), diabetes duration (β = - 0.169; 95% CI, - 0.319 to - 0.025; P = 0.022) and glycated haemoglobin (β = - 0.184; 95% CI, - 0.281 to - 0.039; P = 0.010) were significantly associated with global upslope in the T2DM group. Multivariable logistic regression analysis indicated that T2DM was an independent predictor of microvascular dysfunction in normal-weight (odds ratio[OR], 6.46; 95% CI, 2.08 to 20.10; P = 0.001), overweight (OR, 7.19; 95% CI, 1.67 to 31.07; P = 0.008) and obese participants (OR, 11.21; 95% CI, 2.38 to 52.75; P = 0.002).

CONCLUSIONS

Myocardial microvascular function gradually declined with increasing BMI in both diabetes and non-diabetes status. T2DM was associated with an increased risk of microvascular dysfunction, and obesity exacerbated the adverse effect of T2DM.

Effects of prolactin on ventricular myocyte shortening and calcium transport in the streptozotocin-induced diabetic rat

The physiological role of prolactin (PRL) in the heart, and in particular the diabetic heart, are largely unknown. The effects of PRL on ventricular myocyte shortening and Ca²⁺ transport in the streptozotocin (STZ) – induced diabetic and in age-matched control rats were investigated. PRL receptor protein, myocyte shortening, intracellular [Ca²⁺], L-type Ca²⁺ current were measured by Western blot, cell imaging, fluorescence photometry and whole-cell patch-clamp techniques, respectively. Compared to normal Tyrode solution (NT), PRL (50 ng/ml) significantly (p < 0.05) increased the amplitude of shortening in myocytes from control (7.43 ± 0.38 vs. 9.68 ± 0.46 %) and diabetic (6.57 ± 0.24 vs. 8.91 ± 0.44 %) heart (n = 44–49 cells). Compared to NT, PRL (50 ng/ml) significantly increased the amplitude of Ca²⁺ transients in myocytes from control (0.084 ± 0.004 vs. 0.115 ± 0.007 Fura-2 ratio units) and diabetic (0.087 ± 0.007 vs. 0.112 ± 0.006 Fura-2 ratio units) heart (n = 36–50 cells). PRL did not significantly alter the amplitude of caffeine-evoked Ca²⁺ transients however, PRL significantly increased the fractional release of Ca²⁺ in myocytes from control (21 %) and diabetic (14 %) and heart. The rate of Ca²⁺ transient recovery following PRL treatment was significantly increased in myocytes from diabetic and control heart. Amplitude of L-type Ca²⁺ current was not significantly altered by diabetes or by PRL. PRL increased the amplitude of shortening and Ca²⁺ transients in myocytes from control and diabetic heart. Increased fractional release of sarcoplasmic reticulum Ca²⁺ may partly underlie the positive inotropic effects of PRL in ventricular myocytes from control and STZ-induced diabetic rat.

Impact of liraglutide on microcirculation in experimental diabetic cardiomyopathy

Liraglutide is a new therapy used in diabetes and its effect on diabetic complications particularly cardiovascular ones is still under investigated. In our research, we tried to study the effect of liraglutide on experimental diabetic cardiomyopathy (DCM) induced by streptozotocin. We found that liraglutide nearly preserved normal myocardiac structure and significantly protected against myocardiac inflammation and fibrosis that was found in DCM group, p < 0.05. It also increased the density of coronary arteriolar vasculature markedly indicated by significant increase in α SMA (p < 0.05) compared to both DCM and non-diabetic (ND) groups. Moreover, liraglutide decreased TNFα and increased VEGF proteins expression (P < 0.05) compared to DCM group. Conclusion, liraglutide may have a very important role in protecting against experimentally induced diabetic cardiomyopathy by preventing the degenerative changes in the cardiomyocytes and the associated fibrosis, inflammation and decreased vasculature at structural and molecular levels.

Effect of Exercise Intervention on Cardiac Function in Type 2 Diabetes Mellitus: A Systematic Review

BACKGROUND

The effect of exercise on cardiac function/structure in type 2 diabetes mellitus (T2DM) with or without diabetic cardiomyopathy (DCM) is not yet completely understood. To date, results of studies have been controversial with variable outcomes due to the variety of exercise modalities.

OBJECTIVES

The aim of the present review was to examine the impact of exercise intervention, and different types of exercise, on cardiac function and structure in T2DM through a systematic literature review, combining both pre-clinical and clinical studies.

METHODS

A systematic literature search was performed on PubMed, Web of Science, and PEDro to identify studies up to 2 April 2018. Articles were included when well-defined exercise protocols were provided, and cardiac function in T2DM patients or validated animal models was examined.

RESULTS

In diabetic animals, improvements in both diastolic and systolic function through exercise therapy were mainly attributed to reduced collagen deposition. In T2DM patients, improvements were observed in diastolic function, but not consistently in systolic function, after endurance (and combined resistance) exercise training. Different exercise intervention modalities and exercise types seemed equally effective in improving cardiac structure and function.

CONCLUSION

Exercise training elicits significant improvements in diastolic function and beneficial remodeling in T2DM and DCM animal models, but not necessarily improvements in systolic function and left ventricular structure, regardless of exercise type. Therefore, exercise intervention should be a cornerstone in the treatment of T2DM patients not only to improve glycemic control but also to specifically enhance cardiac function.

Cardiac calcium dysregulation in mice with chronic kidney disease

Cardiovascular complications are leading causes of morbidity and mortality in patients with chronic kidney disease (CKD). CKD significantly affects cardiac calcium (Ca²⁺) regulation, but the underlying mechanisms are not clear. The present study investigated the modulation of Ca²⁺ homeostasis in CKD mice. Echocardiography revealed impaired fractional shortening (FS) and stroke volume (SV) in CKD mice. Electrocardiography showed that CKD mice exhibited longer QT interval, corrected QT (QTc) prolongation, faster spontaneous activities, shorter action potential duration (APD) and increased ventricle arrhythmogenesis, and ranolazine (10 µmol/L) blocked these effects. Conventional microelectrodes and the Fluo‐3 fluorometric ratio techniques indicated that CKD ventricular cardiomyocytes exhibited higher Ca²⁺ decay time, Ca²⁺ sparks, and Ca²⁺ leakage but lower [Ca²⁺]_i transients and sarcoplasmic reticulum Ca²⁺ contents. The CaMKII inhibitor KN93 and ranolazine (RAN; late sodium current inhibitor) reversed the deterioration in Ca²⁺ handling. Western blots revealed that CKD ventricles exhibited higher phosphorylated RyR2 and CaMKII and reduced phosphorylated SERCA2 and SERCA2 and the ratio of PLB‐Thr17 to PLB. In conclusions, the modulation of CaMKII, PLB and late Na⁺ current in CKD significantly altered cardiac Ca²⁺ regulation and electrophysiological characteristics. These findings may apply on future clinical therapies.

Practical Guide to Evaluating Myocardial Disease by Cardiac MRI

OBJECTIVE. A spectrum of pathophysiologic mechanisms can lead to the development of myocardial disorders including ischemia, genetic abnormalities, and systemic disorders. Cardiac MRI identifies different myocardial disorders, provides prognostic information, and directs therapy. In comparison with other imaging modalities, cardiac MRI has the advantage of allowing both functional assessment and tissues characterization in a single examination without the use of ionizing radiation. Newer cardiac MRI techniques including mapping can provide additional information about myocardial disease that may not be detected using conventional techniques. Emerging techniques including MR spectroscopy and finger printing will likely change the way we understand the pathophysiology mechanisms of the wide array of myocardial disorders. CONCLUSION. Imaging of myocardial disorders encompasses a large variety of conditions including both ischemic and nonischemic diseases. Cardiac MRI sequences, such as balanced steady-state free precession and late gadolinium enhancement, play a critical role in establishing diagnosis, determining prognosis, and guiding therapeutic management. Additional sequences-including perfusion imaging, T2*, real-time cine, and T2-weighted sequences-should be performed in specific clinical scenarios. There is emerging evidence for the use of mapping in imaging of myocardial disease. Multiple other new techniques are currently being studied. These novel techniques will likely change the way myocardial disorders are understood and diagnosed in the near future.

Tanshinone IIA ameliorates diabetic cardiomyopathy by inhibiting Grp78 and CHOP expression in STZ-induced diabetes rats

Diabetic cardiomyopathy (DCM), one of the common diabetic complications, causes a high rate of mortality in patients with diabetes. Tanshinone IIA (TSIIA), one of the components of Salvia miltiorrhiza (Danshen), has anti-oxidative stress activity and is widely used to treat diabetes-associated diseases. However, its efficacy on DCM remains unclear. The present study aimed to investigate the potential therapeutic function of TSIIA on DCM in an experimental diabetic rat model. Streptozotocin (STZ)-induced diabetic rats were intraperitoneally injected with TSIIA for 6 weeks. The present results indicated that blood glucose concentration was slightly reduced in the low-dose TSIIA treatment group. TSIIA injection was also noted to improve cardiac function, and restore loss of mitochondrial cristae, swollen mitochondrial matrix and disorganized myofibrils in myocardial cells, which are thought to be characteristics of apoptosis. Furthermore, TSIIA injection could increase the activity of superoxide dismutase in STZ-induced diabetic rats, and suppress the endoplasmic reticulum (ER) stress signaling pathway via reducing the expression of glucose-regulated protein 78 and C/EBP homologous protein. These results provide evidence that TSIIA may ameliorate DCM in diabetic rats, possibly via suppressing oxidative stress and ER stress activation.

Empagliflozin Attenuates Myocardial Sodium and Calcium Dysregulation and Reverses Cardiac Remodeling in Streptozotocin-Induced Diabetic Rats

Diabetes mellitus (DM) has significant effects on cardiac calcium (Ca²⁺) and sodium (Na⁺) regulation. Clinical studies have shown that empagliflozin (Jardiance™) has cardiovascular benefits, however the mechanisms have not been fully elucidated. This study aimed to investigate whether empagliflozin modulates cardiac electrical activity as well as Ca²⁺/Na⁺ homeostasis in DM cardiomyopathy. Electrocardiography, echocardiography, whole-cell patch-clamp, confocal microscopic examinations, and Western blot, were performed in the ventricular myocytes of control and streptozotocin-induced DM rats, with or without empagliflozin (10 mg/kg for 4 weeks). The results showed that the control and empagliflozin-treated DM rats had smaller left ventricular end-diastolic diameters and shorter QT intervals than the DM rats. In addition, the prolonged action potential duration in the DM rats was attenuated in the empagliflozin-treated DM rats. Moreover, the DM rats had smaller sarcoplasmic reticular Ca²⁺ contents, intracellular Ca²⁺ transients, L-type Ca²⁺, reverse mode Na⁺-Ca²⁺exchanger currents, lower protein expressions of sarcoplasmic reticulum ATPase, ryanodine receptor 2 (RyR2), but higher protein expressions of phosphorylated RyR2 at serine 2808 than the control and empagliflozin-treated DM rats. The incidence and frequency of Ca²⁺ sparks, cytosolic and mitochondrial reactive oxygen species, and late Na⁺ current and Na⁺/hydrogen-exchanger currents were greater in the DM rats than in the control and empagliflozin-treated DM rats. Empagliflozin significantly changed Ca²⁺ regulation, late Na⁺ and Na⁺/hydrogen-exchanger currents and electrophysiological characteristics in DM cardiomyopathy, which may contribute to its cardioprotective benefits in DM patients.

Coronary Microvascular Disease Pathogenic Mechanisms and Therapeutic Options: JACC State-of-the-Art Review

Coronary microvascular disease (CMD) refers to the subset of disorders affecting the structure and function of the coronary microcirculation, is prevalent in patients across a broad spectrum of cardiovascular risk factors, and is associated with an increased risk of adverse events. Contemporary evidence supports that most patients with CMD also have macrovessel atherosclerosis, which has important implications for their prognosis and management. In this state-of-the-art review, the authors summarize the pathophysiology of CMD, provide an update of diagnostic testing strategies, and classify CMD into phenotypes according to severity and coexistence with atherosclerosis. They examine emerging data highlighting the significance of CMD in specific populations, including obesity and insulin resistance, myocardial injury and heart failure with preserved ejection fraction, and nonobstructive and obstructive coronary artery disease. Finally, they discuss the role of CMD as a potential target for novel interventions beyond conventional approaches, representing a new frontier in cardiovascular disease reduction.

Long noncoding RNAs: A new player in the prevention and treatment of diabetic cardiomyopathy?

Diabetic cardiomyopathy (DCM) can cause extensive necrosis of the heart muscle by metabolic disorders and microangiopathy, with subclinical cardiac dysfunction, and eventually progress to heart failure, arrhythmia, and cardiogenic shock; severe patients may even die suddenly. Long noncoding RNAs (lncRNAs) are a class of nonprotein-coding RNAs longer than 200 nucleotides. They have critical roles in various biological processes, including gene expression regulation, genomic imprinting, nuclear-cytoplasmic trafficking, RNA splicing, and translational control. Recent studies indicated that lncRNAs extensively participate in the development of diverse cardiac diseases, such as cardiac ischaemia, hypertrophy, and heart failure. Little is known about lncRNA in DCM. In this review, we summarize the current literature on lncRNAs in DCM studies, aiming to provide new methods for DCM's future prevention and treatment strategies.

Thymoquinone Attenuates Cardiomyopathy in Streptozotocin-Treated Diabetic Rats

Diabetic cardiomyopathy is a diabetic complication due to oxidative stress injuries. This study examined the protecting influence of thymoquinone (TQ) on diabetes-caused cardiac complications. The intracellular means by which TQ works against diabetes-caused cardiac myopathy in rats is not completely understood. In this study, Wistar male rats (n = 60) were assigned into four groups: control, diabetic (diabetes induced by IP infusion of streptozotocin, 65 mg/kg), diabetic + TQ (diabetic rats given TQ (50 mg/kg) administered once per day by stomach gavage), and TQ (50 mg/kg) for 12 weeks. TQ supplementation appreciably recovered the cardiac parameters alongside significant declines in plasma nitric oxide concentrations and total superoxide dismutase (T.SOD) activities. Importantly, TQ downgraded expression of cardiac-inducible nitric oxide synthase in addition to significantly upregulating vascular endothelial growth factor and erythropoietin genes and nuclear factor-erythroid-2-related factor 2 (Nrf2) protein. TQ normalized plasma triacylglycerol and low-density lipoprotein-cholesterol and significantly improved the high-density lipoprotein-cholesterol levels. Additionally, TQ administration improved the antioxidant ability of cardiac tissue via significantly increased cardiac T.SOD and decreased cardiac malondialdehyde levels. Oral supplementation with TQ prevented diabetic-induced cardiomyopathy via its inhibitory effect on the E-selectin level, C-reactive protein, and interleukin-6. The TQ protecting effect on the heart tissue was shown by normalization of the plasma cardiac markers troponin I and creatine kinase. This experiment shows the aptitude of TQ to protect cardiac muscles against diabetic oxidative stress, mainly through upregulation of Nrf2, which defeated oxidative damage by improvement of the antioxidant power of cardiac muscle that consequently protected the cardiac muscles and alleviated the inflammatory process.

Left ventricular subclinical myocardial dysfunction in uncomplicated type 2 diabetes mellitus is associated with impaired myocardial perfusion: a contrast-enhanced cardiovascular magnetic resonance study

BACKGROUND

Early detection of subclinical myocardial dysfunction in patients with diabetes mellitus (DM) is essential for recommending therapeutic interventions that can prevent or reverse heart failure, thereby improving the prognosis in such patients. This study aims to quantitatively evaluate left ventricular (LV) myocardial deformation and perfusion using cardiovascular magnetic resonance (CMR) imaging in patients with type 2 diabetes mellitus (T2DM), and to investigate the association between LV subclinical myocardial dysfunction and coronary microvascular perfusion.

METHODS

We recruited 71 T2DM patients and 30 healthy individuals as controls who underwent CMR examination. The T2DM patients were subdivided into two groups, namely the newly diagnosed DM group (n = 31, patients with diabetes for ≤ 5 years) and longer-term DM group (n = 40, patients with diabetes > 5 years). LV deformation parameters, including global peak strain (PS), peak systolic strain rate, and peak diastolic strain rate (PSDR), and myocardial perfusion parameters such as upslope, time to maximum signal intensity (TTM), and max signal intensity (Max SI, were measured and compared among the three groups. Pearson's correlation was used to evaluate the correlation between LV deformation and perfusion parameters.

RESULTS

Pooled data from T2DM patients showed a decrease in global longitudinal, circumferential, and radial PDSR compared to healthy individuals, apart from lower upslope. In addition, increased TTM and reduced Max SI were found in the longer-term diabetics compared to the normal subjects (p < 0.017 for all). Multivariable linear regression analysis showed that T2DM was independently associated with statistically significant CMR parameters, except for TTM (β = 0.137, p = 0.195). Further, longitudinal PDSR was significantly associated with upslope (r = - 0.346, p = 0.003) and TTM (r = 0.515, p < 0.001).

CONCLUSIONS

Our results imply that a contrast-enhanced 3.0T CMR can detect subclinical myocardial dysfunction and impaired myocardial microvascular perfusion in the early stages of T2DM, and that the myocardial dysfunction is associated with impaired coronary microvascular perfusion.

Identification of biomarkers and mechanisms of diabetic cardiomyopathy using microarray data

BACKGROUND

The study aimed to uncover the regulation mechanisms of diabetic cardiomyopathy (DCM) and provide novel prognostic biomarkers.

METHODS

The dataset GSE62203 downloaded from the Gene Expression Omnibus database was utilized in the present study. After pretreatment using the Affy package, differentially expressed genes (DEGs) were identified by the limma package, followed by functional enrichment analysis and protein- protein interaction (PPI) network analysis. Furthermore, module analysis was conducted using MCODE plug-in of Cytoscape, and functional enrichment analysis was also performed for genes in the modules.

RESULTS

A set of 560 DEGs were screened, mainly enriched in the metabolic process and cell cycle related process. Hub nodes in the PPI network were LDHA (lactate dehydrogenase A), ALDOC (aldolase C, fructose-bisphosphate) and ABCE1 (ATP Binding Cassette Subfamily E Member 1), which were also highlighted in Module 1 or Module 2 and predominantly enriched in the processes of glycolysis and ribosome biogenesis. Additionally, LDHA were linked with ALDOC in the PPI network. Besides, activating transcription factor 4 (ATF4) was prominent in Module 3; while myosin heavy chain 6 (MYH6) was highlighted in Module 4 and was mainly involved in muscle cells related biological processes.

CONCLUSIONS

Five potential biomarkers including LDHA, ALDOC, ABCE1, ATF4 and MYH6 were identified for DCM prognosis.

Association of left ventricular myocardial dysfunction with diabetic polyneuropathy

BACKGROUND

The pathogenesis of left ventricular (LV) dysfunction in diabetes has been attracting attention. It has been reported that LV longitudinal systolic myocardial function determined by speckle tracking echocardiography (STE) is associated with diabetic polyneuropathy (DPN). However, the relationship between the severity of peripheral neuropathy and LV myocardial dysfunction is unknown. This study examined the relationship between the severity of DPN and echocardiographic parameters as well as clinical features.

METHODS

The subjects were 166 patients (57 ± 14 years old) with diabetes who had a normal LV ejection fraction (≥ 55%). To assess LV longitudinal systolic function, global longitudinal strain (GLS) was calculated by two-dimensional STE as the average peak strain of 18 LV segments in three standard apical views. A nerve conduction study (NCS) was performed in each subject to assess the severity of neuropathy based on the NCS Baba Classification (Grade 0: no apparent abnormalities-Grade IV: abolition). Three nerves in the lower extremity were examined: tibial nerve (F-wave latency, motor nerve conduction velocity, and amplitude), sural nerve (sensory conduction velocity and amplitude), and peroneal nerve (motor nerve conduction velocity and amplitude).

RESULTS

Of the 166 subjects, 112 subjects (67.5%) were confirmed to have DPN, and all the subjects were divided into two groups according to the presence/absence of DPN. When multivariate analysis was performed using significant factors from univariate logistic regression analysis as explanatory variables, GLS was found to be an independent determinant of DPN (odds ratio: 0.55, p < 0.001). In multivariate analysis of NCS data, F-wave latency was the most important determinant of DPN (odds ratio: 1.43, p < 0.001). There was a significant negative correlation between F-wave latency and GLS (r = - 0.43, p < 0.001). Regarding the relation between GLS and the severity of DPN, GLS was significantly lower in patients with Grade I or higher DPN than in patients without DPN, but showed no significant difference between the grades of neuropathy. In addition, GLS was significantly lower when 2-3 lower extremity nerves were affected by DPN than in patients without DPN.

CONCLUSION

Patients with diabetes may already have subclinical LV myocardial dysfunction when DPN is Grade I. Assessment of LV longitudinal systolic function by GLS may be important in diabetic patients with DPN.

Western diet given to healthy rats mimics the human phenotype of diabetic cardiomyopathy

Diabetes mellitus (DM) is a major problem worldwide. Within this patient group, cardiovascular diseases are the biggest cause of morbidity and mortality. Diabetic cardiomyopathy (DCM) is defined as diabetes-associated structural and functional changes in the myocardium, not directly attributable to other confounding factors such as coronary artery disease or hypertension. Pathophysiology of DCM remains unclear due to a lack of adequate animal models reflecting the current pandemic of diabetes, associated with a high increased sugar intake and the 'Western' lifestyle. The aim of this study was to develop an animal model mimicking this 'Western' lifestyle causing a human-like phenotype of DCM. Twenty-four Sprague-Dawley rats were randomly assigned into a normal or a 'Western' diet group for 18 weeks. Glucose and insulin levels were measured with an OGTT. Heart function was assessed by echocardiography and hemodynamic measurements in vivo. Cardiac fibrosis and inflammation were investigated in vitro. 'Western' diet given to healthy rats for 18 weeks induced hyperglycemia together with increased AGEs levels, insulin levels and hypertriglyceridemia. Heart function was altered with increased end-diastolic pressure, left ventricle hypertrophy. Changes in vivo were associated with increased collagen deposition and increased PAI-1 levels in the heart. High-sugar diet or 'Western' diet causes T2DM and the hallmarks of DCM in rats, reflecting the phenotype of the disease seen in patients. Using this new model of T2DM with DCM might open new insight in understanding the pathophysiology of DCM and on a long term, test targeted therapies for T2DM with DCM patients.

Emerging Actors in Diabetic Cardiomyopathy: Heartbreaker Biomarkers or Therapeutic Targets?

The diabetic heart is characterized by metabolic disturbances that are often accompanied by local inflammation, oxidative stress, myocardial fibrosis, and cardiomyocyte apoptosis. Overall changes result in contractile dysfunction, concentric left ventricular (LV) hypertrophy, and dilated cardiomyopathy, that together affect cardiac output and eventually lead to heart failure, the foremost cause of death in diabetic patients. There are currently several validated biomarkers for the diagnosis and risk assessment of cardiac diseases, but none is capable of discriminating patients with diabetic cardiomyopathy (DCM). In this review we point to several novel candidate biomarkers from new activated molecular pathways (including microRNAs) with the potential to detect or prevent DCM in its early stages, or even to treat it once established. The prospective use of selected biomarkers that integrate inflammation, oxidative stress, fibrosis, and metabolic dysregulation is widely discussed.

Resveratrol Prevents Diabetic Cardiomyopathy by Increasing Nrf2 Expression and Transcriptional Activity

OBJECTIVE

This study investigated if resveratrol ameliorates diabetic cardiomyopathy by targeting associated oxidative stress mechanisms.

METHOD

Type 1 diabetes mellitus (DM) in FVB mice was induced by several intraperitoneal injections of a low dose of streptozotocin. Hyperglycemic and age-matched control mice were given resveratrol (10 mg/kg per day) for 1 month and subsequently monitored for an additional 6 months. Mice were assigned to four groups: control, resveratrol, DM, and DM/resveratrol. Cardiac function and blood pressure were assessed at 1, 3, and 6 months after DM induction. Oxidative damage and cardiac fibrosis were analyzed by histopathology, real-time PCR, and Western blot.

RESULT

Mice in the DM group exhibited increased blood glucose levels, cardiac dysfunction, and high blood pressure at 1, 3, and 6 months after DM induction. Resveratrol did not significantly affect blood glucose levels and blood pressure; however, resveratrol attenuated cardiac dysfunction and hypertrophy in DM mice. Resveratrol also reduced DM-induced fibrosis. In addition, DM mice hearts exhibited increased oxidative damage, as evidenced by elevated accumulation of 3-nitrotyrosine and 4-hydroxynonenal, which were both attenuated by resveratrol. Mechanistically, resveratrol increased NFE2-related factor 2 (Nrf2) expression and transcriptional activity, as well as Nrf2's downstream antioxidative targets.

CONCLUSION

We demonstrated that resveratrol prevents DM-induced cardiomyopathy, in part, by increasing Nrf2 expression and transcriptional activity.

Effect of N-Acetylcysteine on Dyslipidemia and Carbohydrate Metabolism in STZ-Induced Diabetic Rats

Background

Type 1 diabetes mellitus (T1DM) is characterized by insulin-deficient production leading to hyperglycemia, which is associated with diabetic complications such as cardiovascular diseases. Antioxidants have been proving a good alternative to diabetic complications, with N-acetylcysteine (NAC) having antioxidant characteristics. The aim of this study was to assess the effect of NAC on the lipid profile and the atherogenic index (AI) in streptozotocin- (STZ-) induced diabetic rats.

Method

32 male Wistar rats (60 days of age) weighting ±250 g were randomly distributed into four groups (n = 8): CTRL: control rats; CTRL+NAC: control rats treated with NAC; DM: diabetic rats; DM+NAC: diabetic rats treated with NAC. T1DM was induced using STZ (60 mg/kg, ip; single dose), and NAC (25 mg/kg/day) was administrated by gavage, for 37 days. The animals received chow and water ad libitum. After the experimental period, blood and cardiac tissue samples were collected to analyze energetic metabolism, lipid profile, and AI.

Results

NAC decreased (p < 0.01) glycemia, energy intake, carbohydrate, and protein consumption in diabetic rats (DM+NAC), when compared with DM, while the alimentary efficiency was improved (p < 0.01) in treated diabetic rats (DM+NAC). Diabetic rats treated with NAC decreased (p < 0.01) lipid profile and AI in diabetic rats (DM+NAC) when compared to DM.

Conclusion

NAC improves lipid profile and decreases AI in STZ-induced diabetic rats.

Influence of apocynin on cardiac remodeling in rats with streptozotocin-induced diabetes mellitus

Background

Increased reactive oxygen species (ROS) generation in diabetes mellitus (DM) is an important mechanism leading to diabetic cardiomyopathy. Apocynin, a drug isolated from the herb Picrorhiza kurroa, is considered an antioxidant agent by inhibiting NADPH oxidase activity and improving ROS scavenging. This study analyzed the influence of apocynin on cardiac remodeling in diabetic rats.

Methods

Six-month-old male Wistar rats were assigned into 4 groups: control (CTL, n = 15), control + apocynin (CTL + APO, n = 20), diabetes (DM, n = 20), and diabetes + apocynin (DM + APO, n = 20). DM was induced by streptozotocin. Seven days later, apocynin (16 mg/kg/day) or vehicle was initiated and maintained for 8 weeks. Left ventricular (LV) histological sections were used to analyze interstitial collagen fraction. NADPH oxidase activity was evaluated in LV samples. Comparisons between groups were performed by ANOVA for a 2 × 2 factorial design followed by the Bonferroni post hoc test.

Results

Body weight (BW) was lower and glycemia higher in diabetic animals. Echocardiogram showed increased left atrial diameter, LV diastolic diameter, and LV mass indexed by BW in both diabetic groups; apocynin did not affect these indices. LV systolic function was impaired in DM groups and unchanged by apocynin. Isovolumic relaxation time was increased in DM groups; transmitral E/A ratio was higher in DM + APO compared to DM. Myocardial functional evaluation through papillary muscle preparations showed impaired contractile and relaxation function in both DM groups at baseline conditions. After positive inotropic stimulation, developed tension (DT) was lower in DM than CTL. In DM + APO, DT had values between those in DM and CTL + APO and did not significantly differ from either group. Myocardial interstitial collagen fraction was higher in DM than CTL and did not differ between DM + APO and CTL + APO. Serum activity of antioxidant enzymes glutathione peroxidase, superoxide dismutase (SOD), and catalase was lower in DM than CTL; apocynin restored catalase and SOD levels in DM + APO. Myocardial NADPH oxidase activity did not differ between groups.

Conclusion

Apocynin restores serum antioxidant enzyme activity despite unchanged myocardial NADPH oxidase activity in diabetic rats.

Addressing Stem Cell Therapeutic Approaches in Pathobiology of Diabetes and Its Complications

High morbidity and mortality of diabetes mellitus (DM) throughout the human population is a serious threat which needs to be addressed cautiously. Type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) are most prevalent forms. Disruption in insulin regulation and resistance leads to increased formation and accumulation of advanced end products (AGEs), which further enhance oxidative and nitrosative stress leading to microvascular (retinopathy, neuropathy, and nephropathy) and macrovascular complications. These complications affect the normal function of organ and tissues and may cause life-threatening disorders, if hyperglycemia persists and improperly controlled. Current and traditional treatment procedures are only focused on to regulate the insulin level and do not cure the diabetic complications. Pancreatic transplantation seemed a viable alternative; however, it is limited due to lack of donors. Cell-based therapy such as stem cells is considered as a promising therapeutic agent against DM and diabetic complications owing to their multilineage differentiation and regeneration potential. Previous studies have demonstrated the various impacts of both pluripotent and multipotent stem cells on DM and its micro- and macrovascular complications. Therefore, this review summarizes the potential of stem cells to treat DM and its related complications.

Emerging roles of RNA-binding proteins in diabetes and their therapeutic potential in diabetic complications

Diabetes is a debilitating health care problem affecting 422 million people around the world. Diabetic patients suffer from multisystemic complications that can cause mortality and morbidity. Recent advancements in high-throughput next-generation RNA-sequencing and computational algorithms led to the discovery of aberrant posttranscriptional gene regulatory programs in diabetes. However, very little is known about how these regulatory programs are mis-regulated in diabetes. RNA-binding proteins (RBPs) are important regulators of posttranscriptional RNA networks, which are also dysregulated in diabetes. Human genetic studies provide new evidence that polymorphisms and mutations in RBPs are linked to diabetes. Therefore, we will discuss the emerging roles of RBPs in abnormal posttranscriptional gene expression in diabetes. Questions that will be addressed are: Which posttranscriptional mechanisms are disrupted in diabetes? Which RBPs are responsible for such changes under diabetic conditions? How are RBPs altered in diabetes? How does dysregulation of RBPs contribute to diabetes? Can we target RBPs using RNA-based methods to restore gene expression profiles in diabetic patients? Studying the evolving roles of RBPs in diabetes is critical not only for a comprehensive understanding of diabetes pathogenesis but also to design RNA-based therapeutic approaches for diabetic complications. WIREs RNA 2018, 9:e1459. doi: 10.1002/wrna.1459 This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Processing > Splicing Regulation/Alternative Splicing Translation > Translation Regulation.

Diabetic retinopathy is associated with diastolic dysfunction in type 2 diabetic patients with non-ischemic dilated cardiomyopathy

BACKGROUND

To investigate the association between diabetic retinopathy (DR) and myocardial dysfunction in patients with type 2 diabetes and dilated cardiomyopathy (dCMP).

METHODS

Data were collected retrospectively from 89 patients with dCMP (46 with type 2 diabetes and 43 without diabetes) and no evidence of coronary artery disease. Echocardiographic parameters and laboratory data, including lipid profiles and fundus findings, were obtained from medical records. A left ventricular ejection fraction (LVEF) less than 40% was considered impaired systolic function, while an E/E' ratio greater than 15 was considered elevated left ventricular (LV) filling pressure.

RESULTS

Baseline characteristics show that LVEF was not significantly different between patients with and without diabetes or between diabetic patients with and without DR. Among the diastolic function parameters, patients with DR exhibited higher E/E' ratios (left ventricular filling pressures) than patients without DR (23.75 ± 13.37 vs 11.71 ± 3.50, P = 0.022). Logistic regression analysis revealed that statin use lowered the risk of impaired systolic dysfunction in all patients (odds ratio (OR) 0.33, 95% confidence interval (CI) 0.12-0.92, P = 0.034) and in patients with diabetes (OR 0.273, 95% CI 0.08-0.99, P = 0.049), while the presence of DR was associated with a higher risk of elevated LV filling filling pressure in patients with diabetes (OR 18.00, 95% CI 1.50-216.62, P = 0.023).

CONCLUSIONS

In conclusion, DR was associated with elevated LV filling pressure in patients with dCMP. DR may not only represent microvascular long-term complications in patients with diabetes but may also be associated with more advanced form of diastolic dysfunction among diabetic patients with cardiomyopathy.

Transcription Factor CREM Mediates High Glucose Response in Cardiomyocytes and in a Male Mouse Model of Prolonged Hyperglycemia

This study aims at investigating the epigenetic landscape of cardiomyocytes exposed to elevated glucose levels. High glucose (30 mM) for 72 hours determined some epigenetic changes in mouse HL-1 and rat differentiated H9C2 cardiomyocytes including upregulation of class I and III histone deacetylase protein levels and activity, inhibition of histone acetylase p300 activity, increase in histone H3 lysine 27 trimethylation, and reduction in H3 lysine 9 acetylation. Gene expression analysis focused on cardiotoxicity revealed that high glucose induced markers associated with tissue damage, fibrosis, and cardiac remodeling such as Nexilin (NEXN), versican, cyclic adenosine 5'-monophosphate-responsive element modulator (CREM), and adrenoceptor α2A (ADRA2). Notably, the transcription factor CREM was found to be important in the regulation of cardiotoxicity-associated genes as assessed by specific small interfering RNA and chromatin immunoprecipitation experiments. In CD1 mice, made hyperglycemic by streptozotoicin (STZ) injection, cardiac structural alterations were evident at 6 months after STZ treatment and were associated with a significant increase of H3 lysine 27 trimethylation and reduction of H3 lysine 9 acetylation. Consistently, NEXN, CREM, and ADRA2 expression was significantly induced at the RNA and protein levels. Confocal microscopy analysis of NEXN localization showed this protein irregularly distributed along the sarcomeres in the heart of hyperglycemic mice. This evidence suggested a structural alteration of cardiac Z-disk with potential consequences on contractility. In conclusion, high glucose may alter the epigenetic landscape of cardiac cells. Sildenafil, restoring guanosine 3', 5'-cyclic monophosphate levels, counteracted the increase of CREM and NEXN, providing a protective effect in the presence of hyperglycemia.

High-Intensity Exercise Reduces Cardiac Fibrosis and Hypertrophy but Does Not Restore the Nitroso-Redox Imbalance in Diabetic Cardiomyopathy

Diabetic cardiomyopathy refers to the manifestations in the heart as a result of altered glucose homeostasis, reflected as fibrosis, cellular hypertrophy, increased oxidative stress, and apoptosis, leading to ventricular dysfunction. Since physical exercise has been indicated as cardioprotective, we tested the hypothesis that high-intensity exercise training could reverse the cardiac maladaptations produced by diabetes. For this, diabetes was induced in rats by a single dose of alloxan. Diabetic rats were randomly assigned to a sedentary group or submitted to a program of exercise on a treadmill for 4 weeks at 80% of maximal performance. Another group of normoglycemic rats was used as control. Diabetic rat hearts presented cardiomyocyte hypertrophy and interstitial fibrosis. Chronic exercise reduced both parameters but increased apoptosis. Diabetes increased the myocardial levels of the mRNA and proteins of NADPH oxidases NOX2 and NOX4. These altered levels were not reduced by exercise. Diabetes also increased the level of uncoupled endothelial nitric oxide synthase (eNOS) that was not reversed by exercise. Finally, diabetic rats showed a lower degree of phosphorylated phospholamban and reduced levels of SERCA2 that were not restored by high-intensity exercise. These results suggest that high-intensity chronic exercise was able to reverse remodeling in the diabetic heart but was unable to restore the nitroso-redox imbalance imposed by diabetes.

Evaluation of Cardiac Functions in Children and Adolescents with Type 1 Diabetes

Background

Cardiac dysfunction in patients with type 1 diabetes (T1D) represents one of the serious complications. To evaluate the cardiac function in children with T1D by conventional echocardiography and tissue Doppler imaging (TDI).

Methods

The study included 40 T1D patients (age between 6 and 16 years) with > 5 years duration of diabetes and 42 healthy control children. The patients were subjected to clinical evaluation and laboratory investigations [glycosylated hemoglobin A1c (HbA1c), serum lipids and lipoproteins]. Conventional echocardiography and TDI were performed to patients and controls.

Results

The patients had lower early diastolic filling velocity (E wave) of the tricuspid valve and mitral valves with a p value of (0.000 and 0.006, respectively). TDI revealed that patients had lower S′velocity of the T1D, shorter isovolumic contraction time, longer isovolumic relaxation time and lower E/E′ of the right ventricle than controls (p value 0.002, 0.001, 0.004, 0.003, and 0.016, respectively). The left ventricle (LV)-T1D of the patients was significantly higher (p value 0.02). Twenty eight patients had poor glycemic control without significant differences between them and those with good glycemic control regarding echocardiographic data. Patients with dyslipidemia (13 patients) had higher late diastolic filling velocity of the mitral valve (A) and the lower LV late tissue velocity (A′) (p wave 0.047 and 0.015). No correlation existed between the duration of illness or the level of HbA1c and the echocardiographic parameters.

Conclusion

Diabetic children have evidence of echocardiographic diastolic dysfunctions. Periodic cardiac evaluation with both conventional and tissue Doppler echocardiography is recommended for early detection of this dysfunction.

Diagnostic approaches for diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a cardiac dysfunction which affects approximately 12% of diabetic patients, leading to overt heart failure and death. However, there is not an efficient and specific methodology for DCM diagnosis, possibly because molecular mechanisms are not fully elucidated, and it remains asymptomatic for many years. Also, DCM frequently coexists with other comorbidities such as hypertension, obesity, dyslipidemia, and vasculopathies. Thus, human DCM is not specifically identified after heart failure is established. In this sense, echocardiography has been traditionally considered the gold standard imaging test to evaluate the presence of cardiac dysfunction, although other techniques may cover earlier DCM detection by quantification of altered myocardial metabolism and strain. In this sense, Phase-Magnetic Resonance Imaging and 2D/3D-Speckle Tracking Echocardiography may potentially diagnose and stratify diabetic patients. Additionally, this information could be completed with a quantification of specific plasma biomarkers related to related to initial stages of the disease. Cardiotrophin-1, activin A, insulin-like growth factor binding protein-7 (IGFBP-7) and Heart fatty-acid binding protein have demonstrated a stable positive correlation with cardiac hypertrophy, contractibility and steatosis responses. Thus, we suggest a combination of minimally-invasive diagnosis tools for human DCM recognition based on imaging techniques and measurements of related plasma biomarkers.

Factors influencing the longevity and replacement frequency of Provox voice prostheses

INTRODUCTION

This study aimed to assess the factors that influence the longevity and replacement frequency of Provox voice prostheses following their placement.

METHODS

The medical records of 27 patients who received Provox voice prostheses after total laryngectomy and attended follow-up regularly between 1998 and 2012 were retrospectively reviewed. The success rate of the Provox voice prostheses (i.e. whether speech was achieved), quality of speech achieved, number and type of complications encountered, frequency of prostheses replacement and reasons for prostheses replacements were evaluated.

RESULTS

All 27 patients were men and their mean age was 63.0 (range 43-78) years. The mean follow-up period was 60.3 (range 1-168) months. Fluent and understandable speech was achieved in 85.0% of the patients. The mean duration before prosthesis replacement had to be performed was 17.1 (range 1-36) months. The most frequent complication was fluid leakage through the prosthesis. There was a strong positive correlation of 77.1% between the longevity of prostheses and postoperative follow-up duration (r = 0.771; p < 0.01).

CONCLUSION

The voice prosthesis is a tool that can be delivered in a practical fashion and replaced easily with no serious complications. It is a means by which speech can be restored, with a high success rate, after total laryngectomy. In the present study, we found that postoperative follow-up duration was the most important factor influencing the longevity of the Provox voice prosthesis.

BRD7 mediates hyperglycaemia-induced myocardial apoptosis via endoplasmic reticulum stress signalling pathway

Bromodomain-containing protein 7 (BRD7) is a tumour suppressor that is known to regulate many pathological processes including cell growth, apoptosis and cell cycle. Endoplasmic reticulum (ER) stress-induced apoptosis plays a key role in diabetic cardiomyopathy (DCM). However, the molecular mechanism of hyperglycaemia-induced myocardial apoptosis is still unclear. We intended to determine the role of BRD7 in high glucose (HG)-induced apoptosis of cardiomyocytes. In vivo, we established a type 1 diabetic rat model by injecting a high-dose streptozotocin (STZ), and lentivirus-mediated short hairpin RNA (shRNA) was used to inhibit BRD7 expression. Rats with DCM exhibited severe myocardial remodelling, fibrosis, left ventricular dysfunction and myocardial apoptosis. The expression of BRD7 was up-regulated in the heart of diabetic rats, and inhibition of BRD7 had beneficial effects against diabetes-induced heart damage. In vitro, H9c2 cardiomyoblasts was used to investigate the mechanism of BRD7 in HG-induced apoptosis. Treating H9c2 cardiomyoblasts with HG elevated the level of BRD7 via activation of extracellular signal-regulated kinase 1/2 (ERK1/2) and increased ER stress-induced apoptosis by detecting spliced/active X-box binding protein 1 (XBP-1s) and C/EBP homologous protein (CHOP). Furthermore, down-regulation of BRD7 attenuated HG-induced expression of CHOP via inhibiting nuclear translocation of XBP-1s without affecting the total expression of XBP-1s. In conclusion, inhibition of BRD7 appeared to protect against hyperglycaemia-induced cardiomyocyte apoptosis by inhibiting ER stress signalling pathway.

Diabetic Cardiomyopathy: A Forensic Perspective

Diabetes mellitus is a common condition affecting both adults and children. Long-standing diabetes is associated with cardiovascular abnormalities such as coronary artery atherosclerosis, microvascular changes, hypertension, kidney disease, and heart failure. Its association with heart failure in the absence of coronary artery disease and hypertension was termed diabetic cardiomyopathy in the 1970s and is believed to account for some of the cardiac mortality in diabetic patients. This entity may be implicated as the cause of sudden cardiac death in the small percentage of diabetic patients in which the autopsy fails to demonstrate evidence of nonketotic hyperosmolar coma, diabetic ketoacidosis, or atherosclerotic and hypertensive cardiovascular disease. Molecular and metabolic alterations have been studied to explain the pathophysiology of this disease.

Dysregulation of RBFOX2 Is an Early Event in Cardiac Pathogenesis of Diabetes

Alternative splicing (AS) defects that adversely affect gene expression and function have been identified in diabetic hearts; however, the mechanisms responsible are largely unknown. Here, we show that the RNA-binding protein RBFOX2 contributes to transcriptome changes under diabetic conditions. RBFOX2 controls AS of genes with important roles in heart function relevant to diabetic cardiomyopathy. RBFOX2 protein levels are elevated in diabetic hearts despite low RBFOX2 AS activity. A dominant-negative (DN) isoform of RBFOX2 that blocks RBFOX2-mediated AS is generated in diabetic hearts. DN RBFOX2 interacts with wild-type (WT) RBFOX2, and ectopic expression of DN RBFOX2 inhibits AS of RBFOX2 targets. Notably, DN RBFOX2 expression is specific to diabetes and occurs at early stages before cardiomyopathy symptoms appear. Importantly, DN RBFOX2 expression impairs intracellular calcium release in cardiomyocytes. Our results demonstrate that RBFOX2 dysregulation by DN RBFOX2 is an early pathogenic event in diabetic hearts.

Sodium glucose cotransporter SGLT1 as a therapeutic target in diabetes mellitus

INTRODUCTION

Glycemic control is important in diabetes mellitus to minimize the progression of the disease and the risk of potentially devastating complications. Inhibition of the sodium-glucose cotransporter SGLT2 induces glucosuria and has been established as a new anti-hyperglycemic strategy. SGLT1 plays a distinct and complementing role to SGLT2 in glucose homeostasis and, therefore, SGLT1 inhibition may also have therapeutic potential.

AREAS COVERED

This review focuses on the physiology of SGLT1 in the small intestine and kidney and its pathophysiological role in diabetes. The therapeutic potential of SGLT1 inhibition, alone as well as in combination with SGLT2 inhibition, for anti-hyperglycemic therapy are discussed. Additionally, this review considers the effects on other SGLT1-expressing organs like the heart.

EXPERT OPINION

SGLT1 inhibition improves glucose homeostasis by reducing dietary glucose absorption in the intestine and by increasing the release of gastrointestinal incretins like glucagon-like peptide-1. SGLT1 inhibition has a small glucosuric effect in the normal kidney and this effect is increased in diabetes and during inhibition of SGLT2, which deliver more glucose to SGLT1 in late proximal tubule. In short-term studies, inhibition of SGLT1 and combined SGLT1/SGLT2 inhibition appeared to be safe. More data is needed on long-term safety and cardiovascular consequences of SGLT1 inhibition.

Expression of cardiac insulin signalling genes and proteins in rats fed a high-sucrose diet: effect of bilberry anthocyanin extract

Scope

Insulin resistance is associated with impaired cardiac function, but the underlying molecular abnormalities are largely unexplained. Bilberry anthocyanin (BAcn) may be protective, as it appears to potentiate insulin action.

Methods

Rats were randomly allocated to control, sucrose-fed (SF) or sucrose-fed + BAcn diets (SF-A) for 15 weeks. Cardiac insulin signalling genes and proteins were quantified using reverse transcription quantitative real-time polymerase chain reaction and western blots.

Results

Glucose tolerance was not different with treatment. SF showed lower (p < 0.05) ferric reducing antioxidant power, which increased with BAcn. SF resulted in significantly decreased (p < 0.05) expression of 10 genes: acetyl-coenzyme A carboxylase alpha; V-Akt murine thymoma viral oncogene homolog 1; Bcl2-like 1; cytosine-cytosine-adenosine-adenosine-thymidine/enhancer binding protein; FK506 binding protein 12-rapamycin associated; glycerol-3-phosphate dehydrogenase 1 (soluble); solute carrier family 2 (facilitated glucose transporter), member 1, 4; hexokinase 2; and thyroglobulin. SF-A prevented these changes. Compared to SF-A, SF up-regulated (p < 0.05) complement factor D and phosphoinositide-3-kinase, regulatory subunit1 (α); sterol regulatory element binding transcription factor 1 was down-regulated (p < 0.05). SF increased (p < 0.05) cardiac phospholamban and decreased phosphorylated troponin I, which were not attenuated by BAcn. Compared to control or SF, SF-A resulted in significantly lower (p < 0.05) 5′-AMP-activated protein kinase.

Conclusions

SF lowered antioxidant capacity and changed the expression of insulin signalling genes, which were modulated by BAcn.

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.

Ryanodine receptor phosphorylation by CaMKII promotes spontaneous Ca(2+) release events in a rodent model of early stage diabetes: The arrhythmogenic substrate

BACKGROUND

Heart failure and arrhythmias occur more frequently in patients with type 2 diabetes (T2DM) than in the general population. T2DM is preceded by a prediabetic condition marked by elevated reactive oxygen species (ROS) and subclinical cardiovascular defects. Although multifunctional Ca2+ calmodulin-dependent protein kinase II (CaMKII) is ROS-activated and CaMKII hyperactivity promotes cardiac diseases, a link between prediabetes and CaMKII in the heart is unprecedented.

OBJECTIVES

To prove the hypothesis that increased ROS and CaMKII activity contribute to heart failure and arrhythmogenic mechanisms in early stage diabetes.

METHODS-RESULTS

Echocardiography, electrocardiography, biochemical and intracellular Ca2+ (Ca2+i) determinations were performed in fructose-rich diet-induced impaired glucose tolerance, a prediabetes model, in rodents. Fructose-rich diet rats showed decreased contractility and hypertrophy associated with increased CaMKII activity, ROS production, oxidized CaMKII and enhanced CaMKII-dependent ryanodine receptor (RyR2) phosphorylation compared to rats fed with control diet. Isolated cardiomyocytes from fructose-rich diet showed increased spontaneous Ca2+i release events associated with spontaneous contractions, which were prevented by KN-93, a CaMKII inhibitor, or addition of Tempol, a ROS scavenger, to the diet. Moreover, fructose-rich diet myocytes showed increased diastolic Ca2+ during the burst of spontaneous Ca2+i release events. Mice treated with Tempol or with sarcoplasmic reticulum-targeted CaMKII-inhibition by transgenic expression of the CaMKII inhibitory peptide AIP, were protected from fructose-rich diet-induced spontaneous Ca2+i release events, spontaneous contractions and arrhythmogenesis in vivo, despite ROS increases.

CONCLUSIONS

RyR2 phosphorylation by ROS-activated CaMKII, contributes to impaired glucose tolerance-induced arrhythmogenic mechanisms, suggesting that CaMKII inhibition could prevent prediabetic cardiovascular complications and/or evolution.

Heart Failure as a Comorbidity of Diabetes: Role of Dipeptidyl Peptidase 4

Heart failure is a primary cause of death worldwide, and it is notable that heart failure patients exhibit a high incidence of diabetes. On the other hand, comorbid diabetes significantly worsens the prognosis of heart failure, even independently of complicated coronary artery disease.To date, heart failure caused by diabetes has been designated as "diabetic cardiomyopathy (DMC)," and a recent cohort study of the large-scale (1.9 million people) research platform of linked electronic medical records in UK (CALIBER registry) demonstrated that heart failure and peripheral arterial disease are the most common initial manifestations of cardiovascular disease in type 2 diabetes. The underlying pathophysiology has been characterized as microvasculopathy, myocardial hypertrophy, and cardiac fibrosis; however, these evidences are mostly obtained under a preclinical setting, and its clinical application on DMC in terms of its diagnosis and therapeutic intervention yet has reached practical. Our group has focused on and clarified the molecular mechanisms underlying DMC both in preclinical and clinical settings and has found the primary role of "dipeptidyl peptidase-4 (DPP4)" in the pathogenesis of diabetic microvasculopathy in the heart. Moreover, there are evidences implicating the potent role of circulating DPP4 activity in the diagnosis of diastolic heart failure. The present review aimed to review the current comprehension regarding diabetes and heart failure and discuss the therapeutic and diagnostic roles of DPP4.

Diabetes and cardiovascular disease: Epidemiology, biological mechanisms, treatment recommendations and future research

The incidence of diabetes mellitus (DM) continues to rise and has quickly become one of the most prevalent and costly chronic diseases worldwide. A close link exists between DM and cardiovascular disease (CVD), which is the most prevalent cause of morbidity and mortality in diabetic patients. Cardiovascular (CV) risk factors such as obesity, hypertension and dyslipidemia are common in patients with DM, placing them at increased risk for cardiac events. In addition, many studies have found biological mechanisms associated with DM that independently increase the risk of CVD in diabetic patients. Therefore, targeting CV risk factors in patients with DM is critical to minimize the long-term CV complications of the disease. This paper summarizes the relationship between diabetes and CVD, examines possible mechanisms of disease progression, discusses current treatment recommendations, and outlines future research directions.

The Cardioprotective Effects of Hydrogen Sulfide in Heart Diseases: From Molecular Mechanisms to Therapeutic Potential

Hydrogen sulfide (H₂S) is now recognized as a third gaseous mediator along with nitric oxide (NO) and carbon monoxide (CO), though it was originally considered as a malodorous and toxic gas. H₂S is produced endogenously from cysteine by three enzymes in mammalian tissues. An increasing body of evidence suggests the involvement of H₂S in different physiological and pathological processes. Recent studies have shown that H₂S has the potential to protect the heart against myocardial infarction, arrhythmia, hypertrophy, fibrosis, ischemia-reperfusion injury, and heart failure. Some mechanisms, such as antioxidative action, preservation of mitochondrial function, reduction of apoptosis, anti-inflammatory responses, angiogenic actions, regulation of ion channel, and interaction with NO, could be responsible for the cardioprotective effect of H₂S. Although several mechanisms have been identified, there is a need for further research to identify the specific molecular mechanism of cardioprotection in different cardiac diseases. Therefore, insight into the molecular mechanisms underlying H₂S action in the heart may promote the understanding of pathophysiology of cardiac diseases and lead to new therapeutic targets based on modulation of H₂S production.

New insights into the mechanisms of diastolic dysfunction in patients with type 2 diabetes

BACKGROUND

Little is known about the role of advanced glycation end products (AGEs) and their receptor (RAGE) in diabetic cardiovascular complications. Therefore, we aimed to evaluate the association of serum soluble RAGE (sRAGE) levels and left ventricular (LV) diastolic dysfunction in patients with type 2 diabetes.

METHODS

Our study consisted of 40 patients with type 2 diabetes and 40 age- and sex-matched healthy control group. Subjects with age ≥ 50 years old and any cardiovascular risk factors or conditions were excluded from the study. Serum sRAGE levels determined by enzyme-linked immunosorbent assay and LV diastolic dysfunction were evaluated according to current American Society of Echocardiography guidelines.

RESULTS

Baseline characteristics were similar between groups except body mass index, waist-hip ratio, and fasting glucose levels. Serum sRAGE level was significantly lower in diabetic group compared with control group (676 ± 128 vs. 1044 ± 344, p < 0.05). Diastolic dysfunction was observed in 50% of diabetic patients (40% grade I and 10% grade II). Correlation analysis showed that serum sRAGE was negatively correlated with duration of diabetes, septal E'/A', lateral E'/A', and average E/E'. In multivariate regression analysis, serum sRAGE level was strongly associated with diastolic dysfunction in patients with type 2 diabetes.

CONCLUSION

Our study showed that serum sRAGE level was significantly lower in type 2 diabetic patients aged < 50 years old. Also, sRAGE has negative correlation with the duration of diabetes and it was significantly associated with the presence of diastolic dysfunction in type 2 diabetes.