Diabetic cardiomyopathy: Pathophysiology, theories and evidence to date

The change of epicardial adipose tissue characteristics and vulnerability for atrial fibrillation upon drastic weight loss

BACKGROUND

Obesity increases the risk of atrial fibrillation (AF). We hypothesize that 'obese' epicardial adipose tissue (EAT) is, regardless of comorbidities, associated with markers of AF vulnerability.

METHODS

Patients >40y of age undergoing bariatric surgery and using <2 antihypertensive drugs and no insulin were prospectively included. Study investigations were conducted before and 1y after surgery. Heart rhythm and p-wave duration were measured through ECGs and 7-d-holters. EAT-volume and attenuation were determined on non-enhanced CT scans. Serum markers were quantified by ELISA.

RESULTS

Thirty-seven patients underwent surgery (age: 52.1 ± 5.9y; 27 women; no AF). Increased p-wave duration correlated with higher BMI, larger EAT volumes, and lower EAT attenuations (p < 0.05). Post-surgery, p-wave duration decreased from 109 ± 11 to 102 ± 11ms. Concurrently, EAT volume decreased from 132 ± 49 to 87 ± 52ml, BMI from 43.2 ± 5.2 to 28.9 ± 4.6kg/m2, and EAT attenuation increased from -76.1 ± 4.0 to -71.7 ± 4.4HU (p <0.001). Adiponectin increased from 8.7 ± 0.8 to 14.2 ± 1.0 μg/ml (p <0.001). However, decreased p-wave durations were not related to changed EAT characteristics, BMI or adiponectin.

CONCLUSION

In this explorative study, longer p-wave durations related to higher BMIs, larger EAT volume, and lower EAT attenuations. P-wave duration and EAT volume decreased, and EAT attenuation increased upon drastic weightloss. However, there was no relation between decreased p-wave duration and changed BMI or EAT characteristics.

The mechanism and promising therapeutic strategy of diabetic cardiomyopathy dysfunctions: Focus on pyroptosis

Diabetes is a major risk factor for cardiovascular diseases, and myocardial damage caused by hyperglycemia is the main cause of heart failure. However, there is still a lack of systematic understanding of myocardial damage caused by diabetes. At present, we believe that the cellular inflammatory damage caused by hyperglycemia is one of the causes of diabetic cardiomyopathy. Pyroptosis, as a proinflammatory form of cell death, is closely related to the occurrence and development of diabetic cardiomyopathy. Therefore, this paper focuses on the important role of inflammation in the occurrence and development of diabetic cardiomyopathy. From the perspective of pyroptosis, we summarize the pyroptosis of different types of cells in diabetic cardiomyopathy and its related signaling pathways. It also summarizes the treatment of diabetic cardiomyopathy, hoping to provide methods for the prevention and treatment of diabetic cardiomyopathy by inhibiting pyroptosis.

Endogenous adenine is a potential driver of the cardiovascular-kidney-metabolic syndrome

Mechanisms underlying the cardiovascular-kidney-metabolic (CKM) syndrome are unknown, although key small molecule metabolites may be involved. Bulk and spatial metabolomics identified adenine to be upregulated and specifically enriched in coronary blood vessels in hearts from patients with diabetes and left ventricular hypertrophy. Single nucleus gene expression studies revealed that endothelial methylthioadenosine phosphorylase (MTAP) was increased in human hearts with hypertrophic cardiomyopathy. The urine adenine/creatinine ratio in patients was predictive of incident heart failure with preserved ejection fraction. Heart adenine and MTAP gene expression was increased in a 2-hit mouse model of hypertrophic heart disease and in a model of diastolic dysfunction with diabetes. Inhibition of MTAP blocked adenine accumulation in the heart, restored heart dysfunction in mice with type 2 diabetes and prevented ischemic heart damage in a rat model of myocardial infarction. Mechanistically, adenine-induced impaired mitophagy was reversed by reduction of mTOR. These studies indicate that endogenous adenine is in a causal pathway for heart failure and ischemic heart disease in the context of CKM syndrome.

CircRNA_012164/MicroRNA-9-5p axis mediates cardiac fibrosis in diabetic cardiomyopathy

Noncoding RNAs play a part in many chronic diseases and interact with each other to regulate gene expression. MicroRNA-9-5p (miR9) has been thought to be a potential inhibitor of diabetic cardiomyopathy. Here we examined the role of miR9 in regulating cardiac fibrosis in the context of diabetic cardiomyopathy. We further expanded our studies through investigation of a regulatory circularRNA, circRNA_012164, on the action of miR9. We showed at both the in vivo and in vitro level that glucose induced downregulation of miR9 and upregulation of circRNA_012164 resulted in the subsequent upregulation of downstream fibrotic genes. Further, knockdown of circRNA_012164 shows protective effects in cardiac endothelial cells and reverses increased transcription of genes associated with fibrosis and fibroblast proliferation through a regulatory axis with miR9. This study presents a novel regulatory axis involving noncoding RNA that is evidently important in the development of cardiac fibrosis in diabetic cardiomyopathy.

Unveiling the crucial role of intercellular adhesion molecule-1 in secondary diabetic complications

Diabetes mellitus is associated with secondary complications such as diabetic retinopathy (DR), nephropathy (DN), and cardiomyopathy (DCM), all of which significantly impact patient health. Intercellular adhesion molecule-1 (ICAM-1) has been implicated in inflammatory responses and endothelial dysfunction, both crucial in the pathogenesis of these complications. The goal of this review is to investigate at potential therapy methods that target ICAM-1 pathways and to better understand the multifaceted role of ICAM-1 in secondary diabetic problems. A meticulous analysis of scholarly literature published globally was conducted to examine ICAM-1involvement in inflammatory processes, endothelial dysfunction, and oxidative stress related to diabetes and its complications. Elevated ICAM-1 levels are strongly associated with augmented leukocyte adhesion, compromised microvascular function, and heightened oxidative stress in diabetes. These pathways contribute significantly to DR, DN, and DCM pathogenesis, highlighting ICAM-1 as a key player in their progression. Understanding ICAM-1 role in secondary diabetic complications offers insights into novel therapeutic strategies. Targeting ICAM-1 pathways may mitigate inflammation, improve endothelial function, and ultimately attenuate diabetic complications, thereby enhancing patient health outcomes. Continued research in this area is crucial for developing effective targeted therapies.

The effect of bariatric surgery type on cardiac reverse remodelling

INTRODUCTION

Bariatric surgery is effective in reversing adverse cardiac remodelling in obesity. However, it is unclear whether the three commonly performed operations; Roux-en-Y Gastric Bypass (RYGB), Laparoscopic Sleeve Gastrectomy (LSG) and Laparoscopic Adjustable Gastric Band (LAGB) are equal in their ability to reverse remodelling.

METHODS

Fifty-eight patients underwent CMR to assess left ventricular mass (LVM), LV mass:volume ratio (LVMVR) and LV eccentricity index (LVei) before and after bariatric surgery (26 RYGB, 22 LSG and 10 LAGB), including 46 with short-term (median 251-273 days) and 43 with longer-term (median 983-1027 days) follow-up. Abdominal visceral adipose tissue (VAT) and epicardial adipose tissue (EAT) were also assessed.

RESULTS

All three procedures resulted in significant decreases in excess body weight (48-70%). Percentage change in VAT and EAT was significantly greater following RYGB and LSG compared to LAGB at both timepoints (VAT:RYGB -47% and -57%, LSG -47% and -54%, LAGB -31% and -25%; EAT:RYGB -13% and -14%, LSG -16% and -19%, LAGB -5% and -5%). Patients undergoing LAGB, whilst having reduced LVM (-1% and -4%), had a smaller decrease at both short (RYGB: -8%, p < 0.005; LSG: -11%, p < 0.0001) and long (RYGB: -12%, p = 0.009; LSG: -13%, p < 0.0001) term timepoints. There was a significant decrease in LVMVR at the long-term timepoint following both RYGB (-7%, p = 0.006) and LSG (-7%, p = 0.021), but not LAGB (-2%, p = 0.912). LVei appeared to decrease at the long-term timepoint in those undergoing RYGB (-3%, p = 0.063) and LSG (-4%, p = 0.015), but not in those undergoing LAGB (1%, p = 0.857). In all patients, the change in LVM correlated with change in VAT (r = 0.338, p = 0.0134), while the change in LVei correlated with change in EAT (r = 0.437, p = 0.001).

CONCLUSIONS

RYGB and LSG appear to result in greater decreases in visceral adiposity, and greater reverse LV remodelling with larger reductions in LVM, concentric remodelling and pericardial restraint than LAGB.

Hypoglycemic Drugs in Patients with Diabetes Mellitus and Heart Failure: A Narrative Review

Over the last few years, given the increase in the incidence and prevalence of both type 2 diabetes mellitus (T2DM) and heart failure (HF), it became crucial to develop guidelines for the optimal preventive and treatment strategies for individuals facing these coexisting conditions. In patients aged over 65, HF hospitalization stands out as the predominant reason for hospital admissions, with their prognosis being associated with the presence or absence of T2DM. Historically, certain classes of glucose-lowering drugs, such as thiazolidinediones (rosiglitazone), raised concerns due to an observed increased risk of myocardial infarction (MI) and cardiovascular (CV)-related mortality. In response to these concerns, regulatory agencies started requiring CV outcome trials for all novel antidiabetic agents [i.e., dipeptidyl peptidase-4 inhibitors (DPP-4 inhibitors), glucagon-like peptide-1 receptor agonists (GLP-1 RAs), and sodium-glucose cotransporter-2 inhibitors (SGLT2is)] with the aim to assess the CV safety of these drugs beyond glycemic control. This narrative review aims to address the current knowledge about the impact of glucose-lowering agents used in T2DM on HF prevention, prognosis, and outcome.

Exosomes derived from mesenchymal stem cells in diabetes and diabetic complications

Diabetes, a group of metabolic disorders, constitutes an important global health problem. Diabetes and its complications place a heavy financial strain on both patients and the global healthcare establishment. The lack of effective treatments contributes to this pessimistic situation and negative outlook. Exosomes released from mesenchymal stromal cells (MSCs) have emerged as the most likely new breakthrough and advancement in treating of diabetes and diabetes-associated complication due to its capacity of intercellular communication, modulating the local microenvironment, and regulating cellular processes. In the present review, we briefly outlined the properties of MSCs-derived exosomes, provided a thorough summary of their biological functions and potential uses in diabetes and its related complications.

Diabetic Cardiomyopathy-From Basics through Diagnosis to Treatment

Diabetic cardiomyopathy (DCM) is the development of myocardial dysfunction in patients with diabetes despite the absence of comorbidities such as hypertension, atherosclerosis or valvular defect. The cardiovascular complications of poorly controlled diabetes are very well illustrated by the U.K. Prospective Diabetes Study (UKPDS), which showed a clear association between increasing levels of glycated hemoglobin and the development of heart failure (HF). The incidence of HF in patients with diabetes is projected to increase significantly, which is why its proper diagnosis and treatment is so important. Providing appropriate therapy focusing on antidiabetic and hypolipemic treatment with the consideration of pharmacotherapy for heart failure reduces the risk of CMD and reduces the incidence of cardiovascular complications. Health-promoting changes made by patients such as a low-carbohydrate diet, regular exercise and weight reduction also appear to be important in achieving appropriate outcomes. New hope for the development of therapies for DCM is offered by novel methods using stem cells and miRNA, which, however, require more thorough research to confirm their efficacy.

Underlying mechanisms and cardioprotective effects of SGLT2i and GLP-1Ra: insights from cardiovascular magnetic resonance

Originally designed as anti-hyperglycemic drugs, Glucagon-Like Peptide-1 receptor agonists (GLP-1Ra) and Sodium-glucose cotransporter-2 inhibitors (SGLT2i) have demonstrated protective cardiovascular effects, with significant impact on cardiovascular morbidity and mortality. Despite several mechanisms have been proposed, the exact pathophysiology behind these effects is not yet fully understood. Cardiovascular imaging is key for the evaluation of diabetic patients, with an established role from the identification of early subclinical changes to long-term follow up and prognostic assessment. Among the different imaging modalities, CMR may have a key-role being the gold standard for volumes and function assessment and having the unique ability to provide tissue characterization. Novel techniques are also implementing the possibility to evaluate cardiac metabolism through CMR and thereby further increasing the potential role of the modality in this context. Aim of this paper is to provide a comprehensive review of changes in CMR parameters and novel CMR techniques applied in both pre-clinical and clinical studies evaluating the effects of SGLT2i and GLP-1Ra, and their potential role in better understanding the underlying CV mechanisms of these drugs.

Role of proprotein convertase subtilisin/kexin type 9 (PCSK9) in diabetic complications

Cardiovascular disease (CVD) complications have remained a major cause of death among patients with diabetes. Hence, there is a need for effective therapeutics against diabetes-induced CVD complications. Since its discovery, proprotein convertase subtilisin/kexin type 9 (PCSK9) has been reported to be involved in the pathology of various CVDs, with studies showing a positive association between plasma levels of PCSK9, hyperglycemia, and dyslipidemia. PCSK9 regulates lipid homeostasis by interacting with low-density lipoprotein receptors (LDLRs) present in hepatocytes and subsequently induces LDLR degradation via receptor-mediated endocytosis, thereby reducing LDL uptake from circulation. In addition, PCSK9 also induces pro-inflammatory cytokine expression and apoptotic cell death in diabetic-CVD. Furthermore, therapies designed to inhibit PCSK9 effectively reduces diabetic dyslipidemia with clinical studies reporting reduced cardiovascular events in patients with diabetes and no significant adverse effect on glycemic controls. In this review, we discuss the role of PCSK9 in the pathogenesis of diabetes-induced CVD and the potential mechanisms by which PCSK9 inhibition reduces cardiovascular events in diabetic patients.

Acute Exercise Promptly Normalizes Myocardial Myosin Heavy-Chain Isoform mRNA Composition in Diabetic Rats: Implications for Diabetic Cardiomyopathy

Background and Objectives: The acute effects of exercise on the myosin heavy-chain (MHC) isoform mRNA expression and the upstream transcription factors in diabetic and non-diabetic hearts remain unexplored. We aimed to determine the acute effect of a single exercise session on the expression of left ventricular MHC, MHC-α and MHC-β, and thyroid receptor (TR), TR-α1 and TR-β, isoform mRNA in diabetic and non-diabetic rats. Materials and Methods: Sprague-Dawley rats were assigned to four groups: non-diabetic control (CS), diabetic exercise (DIEX), sedentary diabetic (DIS), and non-diabetic exercise (CEX). Diabetes was induced via streptozotocin injection (55 mg/kg). DIEX and CEX rats performed an exercise session (60 min at 50 m/min and 0% grade) 6-7 weeks after diabetes induction. Results: MHC-α mRNA was lower in DIS (p = 0.03) and not different in DIEX (p = 0.1) relative to CS. DIS showed higher MHC-β mRNA than the non-diabetic rats, CS and CEX (p = 0.02 and p = 0.009, respectively). MHC-β mRNA in DIEX was normalized to non-diabetic levels in CS (p = 0.3). TR-α1 was higher in DIS and not different in DIEX relative to CS and CEX (p = 0.03 and p = 1.0, respectively). In CEX, exercise did not change MHC-α, MHC-β, and TR-α1 relative to CS (p = 1.0). TR-β was not different between groups. Conclusion: In conclusion, exercise appears to acutely normalize the myocardial MHC and TR isoform mRNA expression only in the diabetic heart. These responses may induce therapeutic mechanisms other than changing the MHC isoform composition.

Effects of a low carbohydrate diet on heart failure symptoms and quality of life in patients with diabetic cardiomyopathy: A randomised controlled trial pilot study

BACKGROUND AND AIMS

Heart failure, insulin resistance and/or type 2 diabetes mellitus coexist in the syndrome that is diabetic cardiomyopathy. Patients with diabetic cardiomyopathy experience high symptom burden and poor quality of life. We tested the hypothesis that a low carbohydrate diet improves heart failure symptoms and quality of life in patients with diabetic cardiomyopathy.

METHODS AND RESULTS

We conducted a 16-week randomised controlled pilot trial comparing the effects of a low carbohydrate diet (LC) to usual care (UC) in 17 adult patients with diabetic cardiomyopathy. New York Heart Association classification, weight, thirst distress and quality of life scores as well as blood pressure and biochemical data were assessed at baseline and at 16 weeks. Thirteen (n = 8 LC; n = 5 UC) patients completed the trial. The low carbohydrate diet induced significant weight loss in completers (p = 0.004). There was a large between-group difference in systolic blood pressure at the end of the study (Hedges's g 0.99[-014,2.08]). There were no significant differences in thirst or quality of life between groups.

CONCLUSION

This is the first clinical trial utilising the low carbohydrate dietary approach in patients with diabetic cardiomyopathy in an outpatient setting. A low carbohydrate diet can lead to significant weight loss in patients with diabetic cardiomyopathy. Future clinical trials with larger samples and that focus on fluid and sodium requirements of patients with diabetic cardiomyopathy who engage in a low carbohydrate diet are warranted.

CLINICAL TRIAL REGISTRATION NUMBER

Australian New Zealand Clinical Trial Registry (ANZCTR): ACTRN12620001278921.

DATE OF REGISTRATION

26th November 2020.

Non-coding RNA-mediated endothelial-to-mesenchymal transition in human diabetic cardiomyopathy, potential regulation by DNA methylation

AIMS

Diabetic cardiomyopathy (DCM) is a major complication of diabetes and a risk factor for cardiovascular disease. Endothelial dysfunction is central to DCM, and endothelial-to-mesenchymal transition (EndMT) is a key form of endothelial dysfunction in diabetes. EndMT in DCM has been well-studied in model systems and has been found to be epigenetically regulated by non-coding RNAs (ncRNAs). However, EndMT in DCM and its associated epigenetic changes need further characterization in human patients. It is also not known if ncRNAs are affected by changes in DNA methylation in DCM. This study aims to confirm in human hearts, the findings from animal and cell studies, and potentially provide novel insight into interactions between DNA methylation and ncRNAs in EndMT in DCM.

METHODS AND RESULTS

Heart tissues were collected from autopsy patients, fixed in formalin, and embedded in paraffin. Thin sections from paraffin-embedded tissues were used for histology and immunofluorescence analyses, where we confirmed that diabetic patients showed increased cardiac fibrosis that EndMT had occurred. Tissue curls from the paraffin-embedded tissues were used for RT-qPCR and methylation analyses. RT-qPCR quantitatively showed that EndMT occurs in the hearts of diabetics, and that EndMT in human hearts corresponded to changes in key ncRNAs. Methylation analysis showed that some of the EndMT-related ncRNAs were regulated by DNA promoter methylation, while others may be regulated through different epigenetic mechanisms.

CONCLUSIONS

We show that EndMT is a relevant pathological process in human hearts during DCM, and that its occurrence coincides with changes in relevant ncRNAs. We further find that interplay between DNA methylation and certain ncRNAs involved in the regulation of EndMT may contribute to the observed changes in ncRNA expression. These findings reinforce the role of EndMT in patients afflicted with DCM and underscore the complexities and importance of the interactions between different facets of epigenetic regulation.

Glucose-Responsive Microgel Comprising Conventional Insulin and Curcumin-Laden Nanoparticles: a Potential Combination for Diabetes Management

Successful management of type 2 diabetes mellitus (T2DM), a complex and chronic disease, requires a combination of anti-hyperglycemic and anti-inflammatory agents. Here, we have conceptualized and tested an integrated "closed-loop mimic" in the form of a glucose-responsive microgel (GRM) based on chitosan, comprising conventional insulin (INS) and curcumin-laden nanoparticles (nCUR) as a potential strategy for effective management of the disease. In addition to mimicking the normal, on-demand INS secretion, such delivery systems display an uninterrupted release of nCUR to combat the inflammation, oxidative stress, lipid metabolic abnormality, and endothelial dysfunction components of T2DM. Additives such as gum arabic (GA) led to a fivefold increased INS loading capacity compared to GRM without GA. The GRMs showed excellent in vitro on-demand INS release, while a constant nCUR release is observed irrespective of glucose concentrations. Thus, this study demonstrates a promising drug delivery technology that can simultaneously, and at physiological/pathophysiological relevance, deliver two drugs of distinct physicochemical attributes in the same formulation.

Impact of the Remission of Type 2 Diabetes on Cardiovascular Structure and Function, Exercise Capacity and Risk Profile: A Propensity Matched Analysis

Type 2 diabetes (T2D) confers a high risk of heart failure frequently with evidence of cardiovascular structural and functional abnormalities before symptom onset. The effects of remission of T2D on cardiovascular structure and function are unknown. The impact of the remission of T2D, beyond weight loss and glycaemia, on cardiovascular structure and function and exercise capacity is described. Adults with T2D without cardiovascular disease underwent multimodality cardiovascular imaging, cardiopulmonary exercise testing and cardiometabolic profiling. T2D remission cases (Glycated hemoglobin (HbA1c) < 6.5% without glucose-lowering therapy, ≥3 months) were propensity score matched 1:4 based on age, sex, ethnicity and time of exposure to those with active T2D (n = 100) with the nearest-neighbour method and 1:1 with non-T2D controls (n = 25). T2D remission was associated with a lower leptin-adiponectin ratio, hepatic steatosis and triglycerides, a trend towards greater exercise capacity and significantly lower minute ventilation/carbon dioxide production (VE/VCO2 slope) vs. active T2D (27.74 ± 3.95 vs. 30.52 ± 5.46, p < 0.0025). Evidence of concentric remodeling remained in T2D remission vs. controls (left ventricular mass/volume ratio 0.88 ± 0.10 vs. 0.80 ± 0.10, p < 0.025). T2D remission is associated with an improved metabolic risk profile and ventilatory response to exercise without concomitant improvements in cardiovascular structure or function. There is a requirement for continued attention to risk factor control for this important patient population.

Obesity and heart failure with preserved ejection fraction: new insights and pathophysiological targets

Obesity and heart failure with preserved ejection fraction (HFpEF) represent two intermingling epidemics driving perhaps the greatest unmet health problem in cardiovascular medicine in the 21st century. Many patients with HFpEF are either overweight or obese, and recent data have shown that increased body fat and its attendant metabolic sequelae have widespread, protean effects systemically and on the cardiovascular system leading to symptomatic HFpEF. The paucity of effective therapies in HFpEF underscores the importance of understanding the distinct pathophysiological mechanisms of obese HFpEF to develop novel therapies. In this review, we summarize the current understanding of the cardiovascular and non-cardiovascular features of the obese phenotype of HFpEF, how increased adiposity might pathophysiologically contribute to the phenotype, and how these processes might be targeted therapeutically.

Investigating microRNAs in diabetic cardiomyopathy as tools for early detection and therapeutics

To profile microRNAs population of glucose-induced cardiomyoblast cell line and identify the differentially expressed microRNAs and their role under pre-diabetes and diabetes condition in vitro. Rat fetal ventricular cardiomyoblast cell line H9c2 was treated with D-glucose to mimic pre-diabetic, diabetic, and high-glucose conditions. Alteration in cellular, nuclear morphology, and change in ROS generation was analyzed through fluorescent staining. Small RNA sequencing was performed using Illumina NextSeq 550 sequencer and was validated using stem-loop qRT-PCR. A large number (~ 100) differential miRNAs were detected in each treated samples as compared to control; however, a similar expression pattern was observed between pre-diabetes and diabetes conditions with the exception for miR-429, miR-101b-5p, miR-503-3p, miR-384-5p, miR-412-5p, miR-672-5p, and miR-532-3p. Functional annotation of differential expressed target genes revealed their involvement in significantly enriched key pathways associated with diabetic cardiomyopathy. For the first time, we report the differential expression of miRNAs (miR-1249, miR-3596d, miR- 3586-3p, miR-7b-3p, miR-191, miR-330-3p, miR-328a, let7i-5p, miR-146-3p, miR-26a-3p) in diabetes-induced cardiac cells. Hyperglycemia threatens the cell homeostasis by dysregulation of miRNAs that begins at a glucose level 10 mM and remains undetected. Analysis of differential expressed miRNAs in pre-diabetes and diabetes conditions and their role in regulatory mechanisms of diabetic cardiomyopathy holds high potential in the direction of using miRNAs as minimally invasive diagnostic and therapeutic tools.

Rationale and design of the Aldose Reductase Inhibition for Stabilization of Exercise Capacity in Heart Failure Trial (ARISE-HF) in patients with high-risk diabetic cardiomyopathy

BACKGROUND

Diabetic cardiomyopathy (DbCM) is a specific form of heart muscle disease that may result in substantial morbidity and mortality in individuals with type 2 diabetes mellitus (T2DM). Hyperactivation of the polyol pathway is one of the primary mechanisms in the pathogenesis of diabetic complications, including development of DbCM. There is an unmet need for therapies targeting the underlying metabolic abnormalities that drive this form of Stage B heart failure (HF).

METHODS

Aldose reductase (AR) catalyzes the first and rate-limiting step in the polyol pathway, and AR inhibition has been shown to reduce diabetic complications, including DbCM in animal models and in patients with DbCM. Previous AR inhibitors (ARIs) were limited by poor specificity resulting in unacceptable tolerability and safety profile. AT-001 is a novel investigational highly specific ARI with higher binding affinity and greater selectivity than previously studied ARIs. ARISE-HF (NCT04083339) is an ongoing Phase 3 randomized, placebo-controlled, double blind, global clinical study to investigate the efficacy of AT-001 (1000 mg twice daily [BID] and 1500 mg BID) in 675 T2DM patients with DbCM at high risk of progression to overt HF. ARISE-HF assesses the ability of AT-001 to improve or prevent decline in exercise capacity as measured by functional capacity (changes in peak oxygen uptake [peak VO₂]) over 15 (and possibly 27) months of treatment. Additional endpoints include percentage of patients progressing to overt HF, health status metrics, echocardiographic measurements, and changes in cardiacbiomarkers.

RESULTS

The ARISE-HF Trial is fully enrolled.

CONCLUSIONS

This report describes the rationale and study design of ARISE-HF.

Changes in epicardial and visceral adipose tissue depots following bariatric surgery and their effect on cardiac geometry

Introduction

Obesity affects cardiac geometry, causing both eccentric (due to increased cardiac output) and concentric (due to insulin resistance) remodelling. Following bariatric surgery, reversal of both processes should occur. Furthermore, epicardial adipose tissue loss following bariatric surgery may reduce pericardial restraint, allowing further chamber expansion. We investigated these changes in a serial imaging study of adipose depots and cardiac geometry following bariatric surgery.

Methods

62 patients underwent cardiac magnetic resonance (CMR) before and after bariatric surgery, including 36 with short-term (median 212 days), 37 medium-term (median 428 days) and 32 long-term (median 1030 days) follow-up. CMR was used to assess cardiac geometry (left atrial volume (LAV) and left ventricular end-diastolic volume (LVEDV)), LV mass (LVM) and LV eccentricity index (LVei - a marker of pericardial restraint). Abdominal visceral (VAT) and epicardial (EAT) adipose tissue were also measured.

Results

Patients on average had lost 21kg (38.9% excess weight loss, EWL) at 212 days and 36kg (64.7% EWL) at 1030 days following bariatric surgery. Most VAT and EAT loss (43% and 14%, p<0.0001) occurred within the first 212 days, with non-significant reductions thereafter. In the short-term LVM (7.4%), LVEDV (8.6%) and LAV (13%) all decreased (all p<0.0001), with change in cardiac output correlated with LVEDV (r=0.35,p=0.03) and LAV change (r=0.37,p=0.03). Whereas LVM continued to decrease with time (12% decrease relative to baseline at 1030 days, p<0.0001), both LAV and LVEDV had returned to baseline by 1030 days. LV mass:volume ratio (a marker of concentric hypertrophy) reached its nadir at the longest timepoint (p<0.001). At baseline, LVei correlated with baseline EAT (r=0.37,p=0.0040), and decreased significantly from 1.09 at baseline to a low of 1.04 at 428 days (p<0.0001). Furthermore, change in EAT following bariatric surgery correlated with change in LVei (r=0.43,p=0.0007).

Conclusions

Cardiac volumes show a biphasic response to weight loss, initially becoming smaller and then returning to pre-operative sizes by 1030 days. We propose this is due to an initial reversal of eccentric remodelling followed by reversal of concentric remodelling. Furthermore, we provide evidence for a role of EAT contributing to pericardial restraint, with EAT loss improving markers of pericardial restraint.

Heart Failure And Type 2 Diabetes Mellitus: Neurohumoral, Histological And Molecular Interconnections

Heart failure (HF) is a global healthcare burden and a leading cause of morbidity and mortality worldwide. Type 2 diabetes mellitus (T2DM) appears to be one of the major risk factors that significantly worsen HF prognosis and increase the risk of fatal cardiovascular outcomes. Despite a great knowledge of pathophysiological mechanisms involved in HF development and progression, hospitalization rates in patients with HF and concomitant T2DM remain elevated. In this review, we discuss the complex interplay between systemic neurohumoral regulation and local cardiac mechanisms participating in myocardial remodeling and HF development in T2DM with special attention to cardiomyocyte energy metabolism, mitochondrial function and calcium metabolism, cardiomyocyte hypertrophy and death, extracellular matrix remodeling.

Diabetes complications and extracellular vesicle therapy

Diabetes is a chronic disorder characterized by dysregulated glycemic conditions. Diabetic complications include microvascular and macrovascular abnormalities and account for high morbidity and mortality rates in patients. Current clinical approaches for diabetic complications are limited to symptomatic treatments and tight control of blood sugar levels. Extracellular vesicles (EVs) released by somatic and stem cells have recently emerged as a new class of potent cell-free therapeutic delivery packets with a great potential to treat diabetic complications. EVs contain a mixture of bioactive molecules and can affect underlying pathological processes in favor of tissue healing. In addition, EVs have low immunogenicity and high storage capacity while maintaining nearly the same regenerative and immunomodulatory effects compared to current cell-based therapies. Therefore, EVs have received increasing attention for diabetes-related complications in recent years. In this review, we provide an outlook on diabetic complications and summarizes new knowledge and advances in EV applications. Moreover, we highlight recommendations for future EV-related research.

Low Carbohydrate Diets for Diabetic Cardiomyopathy: A Hypothesis

Elevated blood glucose levels, insulin resistance (IR), hyperinsulinemia and dyslipidemia the key aspects of type 2 diabetes mellitus (T2DM), contribute to the development of a certain form of cardiomyopathy. This cardiomyopathy, also known as diabetic cardiomyopathy (DMCM), typically occurs in the absence of overt coronary artery disease (CAD), hypertension or valvular disease. DMCM encompasses a variety of pathophysiological processes impacting the myocardium, hence increasing the risk for heart failure (HF) and significantly worsening outcomes in this population. Low fat (LF), calorie-restricted diets have been suggested as the preferred eating pattern for patients with HF. However, LF diets are naturally higher in carbohydrates (CHO). We argue that in an insulin resistant state, such as in DMCM, LF diets may worsen glycaemic control and promote further insulin resistance (IR), contributing to a physiological and functional decline in DMCM. We postulate that CHO restriction targeting hyperinsulinemia may be able to improve tissue and systemic IR. In recent years low carbohydrate diets (LC) including ketogenic diets (KD), have emerged as a safe and effective tool for the management of various clinical conditions such as T2DM and other metabolic disorders. CHO restriction achieves sustained glycaemic control, lower insulin levels and successfully reverses IR. In addition to this, its pleiotropic effects may present a metabolic stress defense and facilitate improvement to cardiac function in patients with HF. We therefore hypothesize that patients who adopt a LC diet may require less medications and experience improvements in HF-related symptom burden.

HDL Composition, Heart Failure, and Its Comorbidities

Although research on high-density lipoprotein (HDL) has historically focused on atherosclerotic coronary disease, there exists untapped potential of HDL biology for the treatment of heart failure. Anti-oxidant, anti-inflammatory, and endothelial protective properties of HDL could impact heart failure pathogenesis. HDL-associated proteins such as apolipoprotein A-I and M may have significant therapeutic effects on the myocardium, in part by modulating signal transduction pathways and sphingosine-1-phosphate biology. Furthermore, because heart failure is a complex syndrome characterized by multiple comorbidities, there are complex interactions between heart failure, its comorbidities, and lipoprotein homeostatic mechanisms. In this review, we will discuss the effects of heart failure and associated comorbidities on HDL, explore potential cardioprotective properties of HDL, and review novel HDL therapeutic targets in heart failure.

Microvascular Dysfunction in Heart Failure with Preserved Ejection Fraction: Pathophysiology, Assessment, Prevalence and Prognosis

Heart failure with preserved ejection fraction (HFpEF) currently accounts for approximately half of all new heart failure cases in the community. HFpEF is closely associated with chronic lifestyle-related diseases, such as obesity and type 2 diabetes, and clinical outcomes are worse in those with than without comorbidities. HFpEF is pathophysiologically distinct from heart failure with reduced ejection fraction, which may explain, in part, the disparity of treatment options available between the two heart failure phenotypes. The mechanisms underlying HFpEF are complex, with coronary microvascular dysfunction (MVD) being proposed as a potential key driver in its pathophysiology. In this review, the authors highlight the evidence implicating MVD in HFpEF pathophysiology, the diagnostic approaches for identifying MVD (both invasive and non-invasive) and the prevalence and prognostic significance of MVD.

Cardioprotective effects of phytopigments via multiple signaling pathways

BACKGROUND

Cardiovascular diseases (CVDs) are among the deadliest non-communicable diseases, and millions of dollars are spent every year to combat CVDs. Unfortunately, the multifactorial etiology of CVDs complicates the development of efficient therapeutics. Interestingly, phytopigments show significant pleiotropic cardioprotective effects both in vitro and in vivo.

PURPOSE

This review gives an overview of the cardioprotective effects of phytopigments based on in vitro and in vivo studies as well as clinical trials.

METHODS

A literature-based survey was performed to collect the available data on cardioprotective activities of phytopigments via electronic search engines such as PubMed, Google Scholar, and Scopus.

RESULTS

Different classes of phytopigments such as carotenoids, xanthophylls, flavonoids, anthocyanins, anthraquinones alleviate major CVDs (e.g., cardiac hypertrophy, atherosclerosis, hypertension, cardiotoxicities) via acting on signaling pathways related to AMPK, NF-κB, NRF2, PPARs, AKT, TLRs, MAPK, JAK/STAT, NLRP3, TNF-α, and RA.

CONCLUSION

Phytopigments represent promising candidates to develop novel and effective CVD therapeutics. More randomized, placebo-controlled clinical studies are recommended to establish the clinical efficacy of phytopigments.

Energy metabolism homeostasis in cardiovascular diseases

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in the general population. Energy metabolism disturbance is one of the early abnormalities in CVDs, such as coronary heart disease, diabetic cardiomyopathy, and heart failure. To explore the role of myocardial energy homeostasis disturbance in CVDs, it is important to understand myocardial metabolism in the normal heart and their function in the complex pathophysiology of CVDs. In this article, we summarized lipid metabolism/lipotoxicity and glucose metabolism/insulin resistance in the heart, focused on the metabolic regulation during neonatal and ageing heart, proposed potential metabolic mechanisms for cardiac regeneration and degeneration. We provided an overview of emerging molecular network among cardiac proliferation, regeneration, and metabolic disturbance. These novel targets promise a new era for the treatment of CVDs.

Cardiovascular Risk Factors and Physical Activity for the Prevention of Cardiovascular Diseases in the Elderly

Cardiovascular diseases create an important burden on the public health systems, especially in the elderly, mostly because this group of patients frequently suffer from multiple comorbidities. Accumulating cardiovascular risk factors during their lifetime has a detrimental effect on an older adult's health status. The modifiable and non-modifiable cardiovascular risk factors are very diverse, and are frequently in a close relationship with the metabolic comorbidities of the elderly, mainly obesity and Diabetes Mellitus. In this review, we aim to present the most important cardiovascular risk factors which link aging and cardiovascular diseases, starting from the pathophysiological links between these factors and the aging process. Next, we will further review the main interconnections between obesity and Diabetes Mellitus and cardiovascular diseases of the elderly. Lastly, we consider the most important aspects related to prevention through lifestyle changes and physical activity on the occurrence of cardiovascular diseases in the elderly.

Interrelationship between micronutrients and cardiovascular structure and function in type 2 diabetes

Micronutrients are important for normal cardiovascular function. They may play a role in the increased risk of cardiovascular disease observed in people with type 2 diabetes (T2D) and T2D-related heart failure. The aims of this study were to (1) examine micronutrient status in people with T2D v. healthy controls; (2) assess any changes following a nutritionally complete meal replacement plan (MRP) compared with routine care; (3) determine if any changes were associated with changes in cardiovascular structure/function. This was a secondary analysis of data from a prospective, randomised, open-label, blinded end-point trial of people with T2D, with a nested case-control [NCT02590822]. Anthropometrics, cardiac resonance imaging and fasting blood samples (to quantify vitamins B1, B6, B12, D and C; and iron and ferritin) were collected at baseline and 12 weeks following the MRP or routine care. Comparative data in healthy controls were collected at baseline. A total of eighty-three people with T2D and thirty-six healthy controls were compared at baseline; all had micronutrient status within reference ranges. Vitamin B1 was higher (148⋅9 v. 131⋅7; P 0⋅01) and B6 lower (37⋅3 v. 52⋅9; P 0⋅01) in T2D v. controls. All thirty participants randomised to routine care and twenty-four to the MRP completed the study. There was an increase in vitamins B1, B6, D and C following the MRP, which were not associated with changes in cardiovascular structure/function. In conclusion, changes in micronutrient status following the MRP were not independently associated with improvements in cardiovascular structure/function in people with T2D.

The protective effects of S14G-humanin (HNG) against streptozotocin (STZ)-induced cardiac dysfunction

Excessive oxidative stress, inflammation, and myocardial hypertrophy have been associated with diabetic cardiomyopathy (DCM). S14G-humanin (HNG) is a potent humanin analogue that has demonstrated cytoprotective effects in a variety of cells and tissues. However, the pharmacological function of HNG in diabetic cardiomyopathy has not yet been reported. In the present study, we investigated the protective effects of HNG against streptozotocin (STZ)-induced cardiac dysfunction in diabetic mice. Myocardial hypertrophy in diabetic mice was determined using Wheat Gem Agglutinin (WGA) staining. The heart function was measured with Echocardiographic imaging. Levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) proteins in plasma were measured using enzyme-linked immunosorbent assay (ELISA) kits. Protein expression of Phosphorylated p38/p38 was determined using western blots. We found that HNG treatment attenuated the STZ-induced myocardial hypertrophy and significantly improved heart function. Also, its treatment proved effective as it reduced the levels of several myocardial injury indicators, including creatine kinase-MB (CK-MB), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and both the cardiac and plasma levels of TNF-α and IL-6, highlighting its effect on the STZ-induced myocardial injury. Lastly, HNG suppressed the activation of the p38/nuclear factor kappa-B (NF-κB) signaling pathway. S14G humanin possesses protective effects against streptozotocin-induced cardiac dysfunction through inhibiting the activation of the p38/NF-κB signaling pathway.

Adipose tissue-heart crosstalk as a novel target for treatment of cardiometabolic diseases

Cardiometabolic disorders, such as diabetes, obesity, or metabolic syndrome, are often considered as key comorbidities, leading to the development of different forms of cardiovascular diseases such as heart failure or diabetic cardiomyopathy. Although the causal relationship between the pathophysiological status of white adipose tissue (WAT) and cardiac lipotoxicity is still elusive, elevated lipolytic rate in WAT has been demonstrated to participate in the overall augmentation of plasma lipid levels, as observed in most of the patients suffering from heart failure. In the present overview, we discuss current therapeutic approaches, as well as new treatment options targeting lipolysis and cardiac lipid metabolism in different forms of heart failure and diabetic cardiomyopathy.

Experimental animal models for diabetes and its related complications-a review

Diabetes mellitus, a very common and multifaceted metabolic disorder is considered as one of the fastest growing public health problems in the world. It is characterized by hyperglycemia, a condition with high glucose level in the blood plasma resulting from defects in insulin secretion or its action and in some cases both the impairment in secretion and also action of insulin coexist. Historically, animal models have played a critical role in exploring and describing malady pathophysiology and recognizable proof of targets and surveying new remedial specialists and in vivo medicines. In the present study, we reviewed the experimental models employed for diabetes and for its related complications. This paper reviews briefly the broad chemical induction of alloxan and streptozotocin and its mechanisms associated with type 1 and type 2 diabetes. Also we highlighted the different models in other species and other animals.

The role of microneedle arrays in drug delivery and patient monitoring to prevent diabetes induced fibrosis

Diabetes affects approximately 450 million adults globally. If not effectively managed, chronic hyperglycaemia causes tissue damage that can develop into fibrosis. Fibrosis leads to end-organ complications, failure of organ systems occurs, which can ultimately cause death. One strategy to tackle end-organ complications is to maintain normoglycaemia. Conventionally, insulin is administered subcutaneously. Whilst effective, this delivery route shows several limitations, including pain. The transdermal route is a favourable alternative. Microneedle (MN) arrays are minimally invasive and painless devices that can enhance transdermal drug delivery. Convincing evidence is provided on MN-mediated insulin delivery. MN arrays can also be used as a diagnostic tool and monitor glucose levels. Furthermore, sophisticated MN array-based systems that integrate glucose monitoring and drug delivery into a single device have been designed. Therefore, MN technology has potential to revolutionise diabetes management. This review describes the current applications of MN technology for diabetes management and how these could prevent diabetes induced fibrosis.

Cell death-inducing DFFA-like effector C/CIDEC gene silencing alleviates diabetic cardiomyopathy via upregulating AMPKa phosphorylation

Cell death-inducing DFFA-like effector C (CIDEC) is responsible for metabolic disturbance and insulin resistance, which are considered to be important triggers in the development of diabetic cardiomyopathy (DCM). To investigate whether CIDEC plays a critical role in DCM, DCM rat model was induced by a high-fat diet and a single injection of low-dose streptozotocin (27.5 mg/kg). DCM rats showed severe metabolic disturbance, insulin resistance, myocardial hypertrophy, interstitial fibrosis, ectopic lipid deposition, inflammation and cardiac dysfunction, accompanied by CIDEC elevation. With CIDEC gene silencing, the above pathophysiological characteristics were significantly ameliorated accompanied by significant improvements in cardiac function in DCM rats. Enhanced AMP-activated protein kinase (AMPK) α activation was involved in the underlying pathophysiological molecular mechanisms. To further explore the underlying mechanisms that CIDEC facilitated collagen syntheses in vitro, insulin-resistant cardiac fibroblast (CF) model was induced by high glucose (15.5 mmol/L) and high insulin (10⁴  μU/mL). We observed that insulin-resistant stimulation dramatically raised CIDEC expression and promoted CIDEC nuclear translocation in CFs. Meanwhile, AMPKα2 was observed to distribute almost completely inside CF nucleus. The results further proved that CIDEC biochemically interacted and co-localized with AMPKα2 rather than AMPKα1 in CF nucleus, which provided a novel mechanism of CIDEC in promoting collagen syntheses. This study suggested that CIDEC gene silencing alleviates DCM via AMPKα signaling both in vivo and in vitro, implicating CIDEC may be a promising target for treatment of human DCM.

Therapeutic Effects of Traditional Chinese Medicine on Cardiovascular Diseases: the Central Role of Calcium Signaling

Calcium, as a second messenger, plays an important role in the pathogenesis of cardiovascular diseases (CVDs). The malfunction of calcium signaling in endothelial cells and vascular smooth muscle cells promotes hypertension. In cardiomyocytes, calcium overload induces apoptosis, leading to myocardial infarction and arrhythmias. Moreover, the calcium–calcineurin–nuclear factor of activated T cells (NFAT) pathway is essential for expressing the cardiac pro-hypertrophic gene. Heart failure is also characterized by reduced calcium transient amplitude and enhanced sarcoplasmic reticulum (SR) calcium leakage. Traditional Chinese medicine (TCM) has been used to treat CVDs for thousands of years in China. Because of its multicomponent and multitarget characteristics, TCM's unique advantages in CVD treatment are closely related to the modulation of multiple calcium handling proteins and calcium signaling pathways in different types of cells involved in distinct CVDs. Thus, we systematically review the diverse mechanisms of TCM in regulating calcium pathways to treat various types of CVDs, ranging from hypertrophic cardiomyopathy to diabetic heart disease.

Guan Xin Dan Shen formulation protects db/db mice against diabetic cardiomyopathy via activation of Nrf2 signaling

Guan Xin Dan Shen formulation (GXDSF) is a widely used treatment for the management of coronary heart disease in China and is composed of three primary components: Dalbergiae odoriferae Lignum, Salviae miltiorrhizae Radix et Rhizoma and Panax notoginseng Radix et Rhizoma. However, the potential use of GXDSF for the management of diabetic cardiomyopathy (DCM) has not been previously assessed. The present study aimed to assess the effects of GXDSF on DCM, as well as the underlying mechanism. In the present study, db/db mice were used. Following treatment with GXDSF for 10 weeks, fasting blood glucose, insulin sensitivity, serum lipid levels and cardiac enzyme levels were detected. Cardiac pathological alterations and cardiac function were assessed by performing hematoxylin and eosin staining and echocardiograms, respectively. TUNEL assays were conducted to assess cardiomyocyte apoptosis. Additionally, reverse transcription‑quantitative PCR and western blotting were performed to evaluate the expression of apoptosis‑associated genes and proteins, respectively. In the model group, the db/db mice displayed obesity, hyperlipidemia and hyperglycemia, accompanied by noticeable myocardial hypertrophy and diastolic dysfunction. Following treatment with GXDSF for 10 weeks, serum triglyceride levels were lower and insulin sensitivity was enhanced in db/db mice compared with the model group, which indicated improvement in condition. Cardiac hypertrophy and dysfunction were also improved in db/db mice following treatment with GXDSF, resulting in significantly increased left ventricular ejection fraction and fractional shortening compared with the model group. Following treatment with metformin or GXDSF, model‑induced increases in levels of myocardial enzymes were decreased in the moderate and high dose groups. Moreover, the results indicated that, compared with the model group, GXDSF significantly inhibited cardiomyocyte apoptosis in diabetic heart tissues by increasing Bcl‑2 expression and decreasing the expression levels of Bax, cleaved caspase‑3 and cleaved caspase‑9. Mechanistically, GXDSF enhanced Akt phosphorylation, which upregulated antioxidant enzymes mediated by nuclear factor erythroid 2‑related factor 2 (Nrf2) signaling. Collectively, the results of the present study indicated that GXDSF attenuated cardiac dysfunction and inhibited cardiomyocyte apoptosis in diabetic mice via activation of Akt/Nrf2 signaling. Therefore, GXDSF may serve as a potential therapeutic agent for the management of DCM.

Mitochondrial remodelling-a vicious cycle in diabetic complications

Diabetes mellitus (DM) is a chronic, metabolic condition characterized by excessive blood glucose that causes perturbations in physiological functioning of almost all the organs of human body. This devastating metabolic disease has its implications in cognitive decline, heart damage, renal, retinal and neuronal complications that severely affects quality of life and associated with decreased life expectancy. Mitochondria possess adaptive mechanisms to meet the cellular energy demand and combat cellular stress. In recent years mitochondrial homeostasis has been point of focus where several mechanisms regulating mitochondrial health and function are evaluated. Mitochondrial dynamics plays crucial role in maintaining healthy mitochondria in cell under physiological as well as stress condition. Mitochondrial dynamics and corresponding regulating mechanisms have been implicated in progression of metabolic disorders including diabetes and its complications. In current review we have discussed about role of mitochondrial dynamics under physiological and pathological conditions. Also, modulation of mitochondrial fission and fusion in diabetic complications are described. The available literature supports mitochondrial remodelling as reliable target for diabetic complications.

Canagliflozin attenuates lipotoxicity in cardiomyocytes and protects diabetic mouse hearts by inhibiting the mTOR/HIF-1α pathway

Lipotoxicity plays an important role in the development of diabetic heart failure (HF). Canagliflozin (CAN), a marketed sodium-glucose co-transporter 2 inhibitor, has significantly beneficial effects on HF. In this study, we evaluated the protective effects and mechanism of CAN in the hearts of C57BL/6J mice induced by high-fat diet/streptozotocin (HFD/STZ) for 12 weeks in vivo and in HL-1 cells (a type of mouse cardiomyocyte line) induced by palmitic acid (PA) in vitro. The results showed that CAN significantly ameliorated heart functions and inflammatory responses in the hearts of the HFD/STZ-induced diabetic mice. CAN significantly attenuated the inflammatory injury induced by PA in the HL-1 cells. Furthermore, CAN seemed to bind to the mammalian target of rapamycin (mTOR) and then inhibit mTOR phosphorylation and hypoxia-inducible factor-1α (HIF-1α) expression. These results indicated that CAN might attenuate lipotoxicity in cardiomyocytes by inhibiting the mTOR/HIF-1α pathway and then show protective effects on diabetic hearts.

Diabetic heart disease: A clinical update

Diabetes mellitus (DM) significantly increases the risk of heart disease, and DM-related healthcare expenditure is predominantly for the management of cardiovascular complications. Diabetic heart disease is a conglomeration of coronary artery disease (CAD), cardiac autonomic neuropathy (CAN), and diabetic cardiomyopathy (DCM). The Framingham study clearly showed a 2 to 4-fold excess risk of CAD in patients with DM. Pathogenic mechanisms, clinical presentation, and management options for DM-associated CAD are somewhat different from CAD among nondiabetics. Higher prevalence at a lower age and more aggressive disease in DM-associated CAD make diabetic individuals more vulnerable to premature death. Although common among diabetic individuals, CAN and DCM are often under-recognised and undiagnosed cardiac complications. Structural and functional alterations in the myocardial innervation related to uncontrolled diabetes result in damage to cardiac autonomic nerves, causing CAN. Similarly, damage to the cardiomyocytes from complex pathophysiological processes of uncontrolled DM results in DCM, a form of cardiomyopathy diagnosed in the absence of other causes for structural heart disease. Though optimal management of DM from early stages of the disease can reduce the risk of diabetic heart disease, it is often impractical in the real world due to many reasons. Therefore, it is imperative for every clinician involved in diabetes care to have a good understanding of the pathophysiology, clinical picture, diagnostic methods, and management of diabetes-related cardiac illness, to reduce morbidity and mortality among patients. This clinical review is to empower the global scientific fraternity with up-to-date knowledge on diabetic heart disease.

Assessment of subclinical diabetic cardiomyopathy by speckle-tracking imaging

BACKGROUND

Diastolic dysfunction is traditionally believed to be the first subclinical manifestation of diabetic cardiomyopathy (DCM), leading to systolic dysfunction and then overt heart failure. However, in the last few years, several studies suggested that systolic subclinical dysfunction measured by speckle-tracking echocardiography (STE) may appear ahead of diastolic dysfunction. In this review, the main endpoint is to show whether subclinical myocardial systolic dysfunction appears ahead of diastolic dysfunction and the implication this may have on the evolution and management of DCM.

MATERIALS AND METHODS

We performed a search in PubMed for all relevant publications on the assessment of DCM by STE from 1 June 2015 to 1 June 2020.

RESULTS AND CONCLUSIONS

The results illustrate that subclinical systolic dysfunction assessed by STE is present in early DCM stages, with or without the association of diastolic dysfunction. This could be a promising perspective for the early management of patients with DCM leading to the prevention of the overt form of disease.

FoxO1 is required for high glucose-dependent cardiac fibroblasts into myofibroblast phenoconversion

In the normal heart, cardiac fibroblasts (CFs) maintain extracellular matrix (ECM) homeostasis, whereas in pathological conditions, such as diabetes mellitus (DM), CFs converse into cardiac myofibroblasts (CMFs) and this CFs phenoconversion increase the synthesis and secretion of ECM proteins, promoting cardiac fibrosis and heart dysfunction. High glucose (HG) conditions increase TGF-β1 expression and FoxO1 activity, whereas FoxO1 is crucial to CFs phenoconversion induced by TGF-β1. In addition, FoxO1 increases CTGF expression, whereas CTGF plays an active role in the fibrotic process induced by hyperglycemia. However, the role of FoxO1 and CTGF in CFs phenoconversion induced by HG is not clear. In this study, we investigated the effects of FoxO1 pharmacological inhibition on CFs phenoconversion in both in vitro and ex vivo models of DM. Our results demonstrate that HG induces CFs phenoconversion and FoxO1 activation. Moreover, AS1842856, a pharmacological inhibitor of FoxO1 activity, prevents CFs phenoconversion and CTGF expression increase induced by HG, whereas these results were corroborated by FoxO1 silencing. Additionally, K252a, a pharmacological blocker of CTGF receptor, prevents HG-induced CFs phenoconversion, which was corroborated with CTGF expression knockdown. Furthermore, through CFs isolation from heart of diabetic rats, we showed that hyperglycemia induces FoxO1 activation, the increase of CTGF expression and CFs phenoconversion, whereas the FoxO1 activity inhibition reverses the effects induced by hyperglycemia on CFs. Altogether, our results demonstrate that FoxO1 and CTGF are necessary for CFs phenoconversion induced by HG and suggest that both proteins are likely to become a potential targeted drug for fibrotic response induced by hyperglycemic conditions.

miR-34a attenuates myocardial fibrosis in diabetic cardiomyopathy mice via targeting Pin-1

Diabetic cardiomyopathy (DCM) is characterized by myocardial hypertrophy and fibrosis. This study aimed to investigate the effects of microRNA (miR)-34a on myocardial fibrosis in DCM and its potential mechanism of targeting Pin-1 signaling. Vimentin and Pin-1 proteins in mouse cardiac tissues were detected by immunohistochemical staining. Locked nucleic acid in situ hybridization was used to measure miR-34a expression in cardiac tissues. Primary mouse cardiac fibroblasts (CFs) were transfected with a mimics control/miR-34a mimics or Pin-1 plasmid and cultured in high-glucose (HG) Dulbecco's modified Eagle's medium. The miR-34a levels were measured by quantitative polymerase chain reaction. The apoptosis and viability of transfected cells were detected by the terminal deoxynucleotidyl transferase dUTP nick end labeling and Cell Counting Kit-8 assays respectively. A cell migration experiment and dual-luciferase reporter assay were also performed. The body weight and fasting blood glucose of DCM mice were significantly higher than those in the control (CTL) group. In addition, DCM mice had decreased serum insulin levels and impaired cardiac function. The number of CFs in the DCM group was higher than in the CTL group and Pin-1 expression was upregulated. The expression level of miR-34a in the cardiac tissue of mice in the DCM group was obviously downregulated compared with the CTL group. The HG stimulation of CFs for 48 h significantly downregulated the expression level of miR-34a and was associated with increased Type I collagen expression, cell viability, and migration and decreased apoptosis. However, these effects could be reversed by overexpressing miR-34a in HG-induced CFs. Furthermore, we found that Pin-1 was a direct target of miR-34a. Our results suggest that miR-34a can attenuate myocardial fibrosis in DCM by reducing Type I collagen production, cell viability, and migration and increasing the apoptosis of CFs by targeting Pin-1 signaling.

Sirtuin 3 deficiency exacerbates diabetic cardiomyopathy via necroptosis enhancement and NLRP3 activation

Sirtuin 3 (SIRT3) is a potential therapeutic target for cardiovascular, metabolic, and other aging-related diseases. In this study, we investigated the role of SIRT3 in diabetic cardiomyopathy (DCM). Mice were injected with streptozotocin (STZ, 60 mg/kg, ip) to induce diabetes mellitus. Our proteomics analysis revealed that SIRT3 expression in the myocardium of diabetic mice was lower than that of control mice, as subsequently confirmed by real-time PCR and Western blotting. To explore the role of SIRT3 in DCM, SIRT3-knockout mice and 129S1/SvImJ wild-type mice were injected with STZ. We found that diabetic mice with SIRT3 deficiency exhibited aggravated cardiac dysfunction, increased lactate dehydrogenase (LDH) level in the serum, decreased adenosine triphosphate (ATP) level in the myocardium, exacerbated myocardial injury, and promoted myocardial reactive oxygen species (ROS) accumulation. Neonatal rat cardiomyocytes were transfected with SIRT3 siRNA, then exposed to high glucose (HG, 25.5 mM). We found that downregulation of SIRT3 further increased LDH release, decreased ATP level, suppressed the mitochondrial membrane potential, and elevated oxidative stress in HG-treated cardiomyocytes. SIRT3 deficiency further raised expression of necroptosis-related proteins including receptor-interacting protein kinase 1 (RIPK1), RIPK3, and cleaved caspase 3, and upregulated the expression of inflammation-related proteins including NLR family pyrin domain-containing protein 3 (NLRP3), caspase 1 p20, and interleukin-1β both in vitro and in vivo. Collectively, SIRT3 deficiency aggravated hyperglycemia-induced mitochondrial damage, increased ROS accumulation, promoted necroptosis, possibly activated the NLRP3 inflammasome, and ultimately exacerbated DCM in the mice. These results suggest that SIRT3 can be a molecular intervention target for the prevention and treatment of DCM.

Forskolin Protected against Streptozotocin-Induced Diabetic Cardiomyopathy via Inhibition of Oxidative Stress and Cardiac Fibrosis in Mice

Background

Diabetic cardiomyopathy is one of the cardiac complications in diabetes patients, eventually resulting in heart failure and increasing morbidity and mortality. Oxidative stress is a critical pathological feature in diabetic hearts, contributing to the development of DCM. Forskolin (FSK) was shown to reduce oxidative stress. This study was aimed at investigating the effects of FSK on diabetic hearts and the relevant molecular mechanisms.

Methods

Streptozotocin- (STZ-) induced diabetes in mice was treated with FSK through intraperitoneal injection. Cardiac functions were evaluated by echocardiography. Hematoxylin-eosin and Masson trichrome staining was employed to determine heart morphological changes and cardiac fibrosis, respectively. Cardiac fibrosis-related markers were detected by western blot. Superoxide dismutase activity, reduced/oxidized glutathione ratio, and malondialdehyde concentration in left ventricles were determined using respective commercial kits.

Results

Abnormal cardiac diastolic dysfunction and cardiac fibrosis were observed in diabetic hearts. FSK treatment significantly improved the cardiac diastolic function and attenuated the abnormal morphological change in diabetic hearts. Moreover, FSK treatment in diabetic mice decreased the expression of fibronectin, collagen I, TGF-β, and α-SMA and reduced myocardial fibrosis. Furthermore, we observed that FSK significantly blocked oxidative stress in diabetic hearts.

Conclusions

Our study demonstrates that FSK protects against the development of DCM in STZ-induced diabetes in mice. Our study suggests that FSK might be a potential target for drug development in treating DCM.

Immunomodulatory Approaches in Diabetes-Induced Cardiorenal Syndromes

Immunomodulatory approaches are defined as all interventions that modulate and curb the immune response of the host rather than targeting the disease itself with the aim of disease prevention or treatment. A better understanding of the immune system continues to offer innovative drug targets and methods for immunomodulatory interventions. Cardiorenal syndrome is a clinical condition that defines disorders of the heart and kidneys, both of which communicate with one another through multiple pathways in an interdependent relationship. Cardiorenal syndrome denotes the confluence of heart-kidney relationships across numerous interfaces. As such, a dysfunctional heart or kidney has the capacity to initiate disease in the other organ via common hemodynamic, neurohormonal, immunological, and/or biochemical feedback pathways. Understanding how immunomodulatory approaches are implemented in diabetes-induced cardiovascular and renal diseases is important for a promising regenerative medicine, which is the process of replacing cells, tissues or organs to establish normal function. In this article, after a brief introduction on the immunomodulatory approaches in diseases, we will be reviewing the epidemiology and classifications of cardiorenal syndrome. We will be emphasizing on the hemodynamic factors and non-hemodynamic factors linking the heart and the kidneys. In addition, we will be elaborating on the immunomodulatory pathways involved in diabetes-induced cardiorenal syndrome namely, RAS, JAK/STAT, and oxidative stress. Moreover, we will be addressing possible therapeutic approaches that target the former pathways in an attempt to modulate the immune system.

Cardiovascular and systemic determinants of exercise capacity in people with type 2 diabetes mellitus

The global burden of heart failure (HF) is on the rise owing to an increasing incidence of lifestyle related diseases, predominantly type 2 diabetes mellitus (T2D). Diabetes is an independent risk factor for cardiovascular disease, and up to 75% of those with T2D develop HF in their lifetime. T2D leads to pathological alterations within the cardiovascular system, which can progress insidiously and asymptomatically in the absence of conventional risk factors. Reduced exercise tolerance is consistently reported, even in otherwise asymptomatic individuals with T2D, and is the first sign of a failing heart. Because aggressive modification of cardiovascular risk factors does not eliminate the risk of HF in T2D, it is likely that other factors play a role in the pathogenesis of HF. Early identification of individuals at risk of HF is advantageous, as it allows for modification of the reversible risk factors and early initiation of treatment with the aim of improving clinical outcomes. In this review, cardiac and extra-cardiac contributors to reduced exercise tolerance in people with T2D are explored.

Impact of peroxisome proliferator-activated receptor-α on diabetic cardiomyopathy

The prevalence of cardiomyopathy is higher in diabetic patients than those without diabetes. Diabetic cardiomyopathy (DCM) is defined as a clinical condition of abnormal myocardial structure and performance in diabetic patients without other cardiac risk factors, such as coronary artery disease, hypertension, and significant valvular disease. Multiple molecular events contribute to the development of DCM, which include the alterations in energy metabolism (fatty acid, glucose, ketone and branched chain amino acids) and the abnormalities of subcellular components in the heart, such as impaired insulin signaling, increased oxidative stress, calcium mishandling and inflammation. There are no specific drugs in treating DCM despite of decades of basic and clinical investigations. This is, in part, due to the lack of our understanding as to how heart failure initiates and develops, especially in diabetic patients without an underlying ischemic cause. Some of the traditional anti-diabetic or lipid-lowering agents aimed at shifting the balance of cardiac metabolism from utilizing fat to glucose have been shown inadequately targeting multiple aspects of the conditions. Peroxisome proliferator-activated receptor α (PPARα), a transcription factor, plays an important role in mediating DCM-related molecular events. Pharmacological targeting of PPARα activation has been demonstrated to be one of the important strategies for patients with diabetes, metabolic syndrome, and atherosclerotic cardiovascular diseases. The aim of this review is to provide a contemporary view of PPARα in association with the underlying pathophysiological changes in DCM. We discuss the PPARα-related drugs in clinical applications and facts related to the drugs that may be considered as risky (such as fenofibrate, bezafibrate, clofibrate) or safe (pemafibrate, metformin and glucagon-like peptide 1-receptor agonists) or having the potential (sodium-glucose co-transporter 2 inhibitor) in treating DCM.

Escitalopram Ameliorates Cardiomyopathy in Type 2 Diabetic Rats via Modulation of Receptor for Advanced Glycation End Products and Its Downstream Signaling Cascades

Type 2 diabetes mellitus (T2DM) has been recognized as a known risk factor for cardiovascular diseases. Additionally, studies have shown the prevalence of depression among people with diabetes. Thus, the current study aimed to investigate the possible beneficial effects of escitalopram, a selective serotonin reuptake inhibitor, on metabolic changes and cardiac complications in type 2 diabetic rats. Diabetes was induced by feeding the rats high fat-high fructose diet (HFFD) for 8 weeks followed by a subdiabetogenic dose of streptozotocin (STZ) (35 mg/kg, i. p.). Treatment with escitalopram (10 mg/kg/day; p. o.) was then initiated for 4 weeks. At the end of the experiment, electrocardiography was performed and blood samples were collected for determination of glycemic and lipid profiles. Animals were then euthanized and heart samples were collected for biochemical and histopathological examinations. Escitalopram alleviated the HFFD/STZ-induced metabolic and cardiac derangements as evident by improvement of oxidative stress, inflammatory, fibrogenic and apoptotic markers in addition to hypertrophy and impaired conduction. These results could be secondary to its beneficial effects on the glycemic control and hence the reduction of receptor for advanced glycation end products content as revealed in the present study. In conclusion, escitalopram could be considered a favorable antidepressant medication in diabetic patients as it seems to positively impact the glycemic control in diabetes in addition to prevention of its associated cardiovascular complications.

A Role of Glucose Overload in Diabetic Cardiomyopathy in Nonhuman Primates

Type 2 diabetes (T2D) plays a major role in the development of heart failure. Patients with T2D have an increased risk to develop HF than healthy subjects, and they always have very poor outcomes and survival rates. However, the underlying mechanisms for this are still unclear. To help develop new therapeutic interventions, well-characterized animal models for preclinical and translational investigations in T2D and HF are urgently needed. Although studies in rodents are more often used, the research findings in rodents have often failed to be translated into humans due to the significant metabolic differences between rodents and humans. Nonhuman primates (NHPs) serve as valuable translational models between basic studies in rodent models and clinical studies in humans. NHPs can recapitulate the natural progress of these diseases in humans and study the underlying mechanism due to their genetic similarity and comparable spontaneous T2D rates to humans. In this review, we discuss the importance of using NHPs models in understanding diabetic cardiomyopathy (DCM) in humans with aspects of correlations between hyperglycemia and cardiac dysfunction progression, glucose overload, and altered glucose metabolism promoting cardiac oxidative stress and mitochondria dysfunction, glucose, and its effect on cardiac resynchronization therapy with defibrillator (CRT-d), the currently available diabetic NHPs models and the limitations involved in the use of NHP models.

[Rosmarinic acid inhibits high glucose-induced cardiomyocyte hypertrophy by activating Parkin-mediated mitophagy]

OBJECTIVE

To evaluate the effect of rosmarinic acid (RA) on mitophagy and hypertrophy of cardiomyocytes exposed to high glucose (HG).

METHODS

Rat cardiomyocytes (H9c2) exposed to HG (25 mmol/L) were treated with 50 μmol/L RA or with both RA treatment and Parkin siRNA transfection, with the cells cultured in normal glucose (5.5 mmol/L) and HG as the controls. The expressions of PINK1, Parkin and LC3II/LC3I in the cells were detected by Western blotting. The formation of mitochondrial autophagosomes was observed by transmission electron microscope. Flow cytometry was employed to detect the level of reactive oxygen species (ROS) and apoptotic rate of the cells. The activities of respiratory chain complex enzymes were measured by spectrophotometry. Fluorescence enzyme labeling and 3H-leucine labeling were used for determining the level of membrane potential and protein synthesis rate, respectively. The cell surface area was observed by light microscopy.

RESULTS

RA treatment significantly increased the expression levels of PINK1, Parkin and LC3-II/I (P < 0.05), promoted the formation of mitochondrail autophagosome, inhibited the production of reactive oxygen species (P < 0.05), restored the activities of mitochondrial respiratory chain complex enzymes and mitochondrial membrane potential (P < 0.05), inhibited apoptosis (P < 0.05), and reduced the cell surface area and protein synthesis rate of H9c2 cells induced by HG exposure (P < 0.05). The protective effects of RA against HG-induced oxidative stress and cardiomyocyte hypertrophy was obviously blocked by inhibition of mitophagy mediated by transfection with Parkin siRNA (P < 0.05).

CONCLUSIONS

RA can protect rat cardiomyocytes against oxidative stress injury and cardiomyocyte hypertrophy induced by HG by activating Parkin-mediated mitophagy.