Diabetes-related cardiomyopathy: The sweet story of glucose overload from epidemiology to cellular pathways

Mitochondrial complex I inhibition triggers NAD+-independent glucose oxidation via successive NADPH formation, "futile" fatty acid cycling, and FADH2 oxidation

Inhibition of mitochondrial complex I (NADH dehydrogenase) is the primary mechanism of the antidiabetic drug metformin and various unrelated natural toxins. Complex I inhibition can also be induced by antidiabetic PPAR agonists, and it is elicited by methionine restriction, a nutritional intervention causing resistance to diabetes and obesity. Still, a comprehensible explanation to why complex I inhibition exerts antidiabetic properties and engenders metabolic inefficiency is missing. To evaluate this issue, we have systematically reanalyzed published transcriptomic datasets from MPP-treated neurons, metformin-treated hepatocytes, and methionine-restricted rats. We found that pathways leading to NADPH formation were widely induced, together with anabolic fatty acid biosynthesis, the latter appearing highly paradoxical in a state of mitochondrial impairment. However, concomitant induction of catabolic fatty acid oxidation indicated that complex I inhibition created a "futile" cycle of fatty acid synthesis and degradation, which was anatomically distributed between adipose tissue and liver in vivo. Cofactor balance analysis unveiled that such cycling would indeed be energetically futile (-3 ATP per acetyl-CoA), though it would not be redox-futile, as it would convert NADPH into respirable FADH2 without any net production of NADH. We conclude that inhibition of NADH dehydrogenase leads to a metabolic shift from glycolysis and the citric acid cycle (both generating NADH) towards the pentose phosphate pathway, whose product NADPH is translated 1:1 into FADH2 by fatty acid cycling. The diabetes-resistant phenotype following hepatic and intestinal complex I inhibition is attributed to FGF21- and GDF15-dependent fat hunger signaling, which remodels adipose tissue into a glucose-metabolizing organ.

Update on clinical and experimental management of diabetic cardiomyopathy: addressing current and future therapy

Diabetic cardiomyopathy (DCM) is a severe secondary complication of type 2 diabetes mellitus (T2DM) that is diagnosed as a heart disease occurring in the absence of any previous cardiovascular pathology in diabetic patients. Although it is still lacking an exact definition as it combines aspects of both pathologies - T2DM and heart failure, more evidence comes forward that declares DCM as one complex disease that should be treated separately. It is the ambiguous pathological phenotype, symptoms or biomarkers that makes DCM hard to diagnose and screen for its early onset. This re-view provides an updated look on the novel advances in DCM diagnosis and treatment in the experimental and clinical settings. Management of patients with DCM proposes a challenge by itself and we aim to help navigate and advice clinicians with early screening and pharmacotherapy of DCM.

Diabetes cardiomyopathy: targeted regulation of mitochondrial dysfunction and therapeutic potential of plant secondary metabolites

Diabetic cardiomyopathy (DCM) is a specific heart condition in diabetic patients, which is a major cause of heart failure and significantly affects quality of life. DCM is manifested as abnormal cardiac structure and function in the absence of ischaemic or hypertensive heart disease in individuals with diabetes. Although the development of DCM involves multiple pathological mechanisms, mitochondrial dysfunction is considered to play a crucial role. The regulatory mechanisms of mitochondrial dysfunction mainly include mitochondrial dynamics, oxidative stress, calcium handling, uncoupling, biogenesis, mitophagy, and insulin signaling. Targeting mitochondrial function in the treatment of DCM has attracted increasing attention. Studies have shown that plant secondary metabolites contribute to improving mitochondrial function and alleviating the development of DCM. This review outlines the role of mitochondrial dysfunction in the pathogenesis of DCM and discusses the regulatory mechanism for mitochondrial dysfunction. In addition, it also summarizes treatment strategies based on plant secondary metabolites. These strategies targeting the treatment of mitochondrial dysfunction may help prevent and treat DCM.

SGLT2 inhibitor as a potential therapeutic approach in hyperthyroidism-induced cardiopulmonary injury in rats

Hyperthyroidism-induced cardiac disease is an evolving health, economic, and social problem affecting well-being. Sodium-glucose cotransporter protein 2 inhibitors (SGLT2-I) have been proven to be cardio-protective when administered in cases of heart failure. This study intended to investigate the potential therapeutic effect of SGLT2-I on hyperthyroidism-related cardiopulmonary injury, targeting the possible underlying mechanisms. The impact of the SGLT2-I, dapagliflozin (DAPA), (1 mg/kg/day, p.o) on LT4 (0.3 mg/kg/day, i.p)-induced cardiopulmonary injury was investigated in rats. The body weight, ECG, and serum hormones were evaluated. Also, redox balance, DNA fragmentation, inflammatory cytokines, and PCR quantification in heart and lung tissues were employed to investigate the effect of DAPA in experimentally induced hyperthyroid rats along with histological and immunohistochemical examination. Coadministration of DAPA with LT4 effectively restored all serum biomarkers to nearly average levels, improved ECG findings, and reinstated the redox balance. Also, DAPA could improve DNA fragmentation, elevate mtTFA, and lessen TNF-α and IGF-1 gene expression in both organs of treated animals. Furthermore, DAPA markedly improved the necro-inflammatory and fibrotic cardiopulmonary histological alterations and reduced the tissue immunohistochemical expression of TNF-α and caspase-3. Although further clinical and deep molecular studies are required before transposing to humans, our study emphasized DAPA's potential to relieve hyperthyroidism-induced cardiopulmonary injury in rats through its antioxidant, anti-inflammatory, and anti-apoptotic effects, as well as via antagonizing the sympathetic over activity.

The study of the mechanism of non-coding RNA regulation of programmed cell death in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) represents a distinct myocardial disorder elicited by diabetes mellitus, characterized by aberrations in myocardial function and structural integrity. This pathological condition predominantly manifests in individuals with diabetes who do not have concurrent coronary artery disease or hypertension. An escalating body of scientific evidence substantiates the pivotal role of programmed cell death (PCD)-encompassing apoptosis, autophagy, pyroptosis, ferroptosis, and necroptosis-in the pathogenic progression of DCM, thereby emerging as a prospective therapeutic target. Additionally, numerous non-coding RNAs (ncRNAs) have been empirically verified to modulate the biological processes underlying programmed cell death, consequently influencing the evolution of DCM. This review systematically encapsulates prevalent types of PCD manifest in DCM as well as nascent discoveries regarding the regulatory influence of ncRNAs on programmed cell death in the pathogenesis of DCM, with the aim of furnishing novel insights for the furtherance of research in PCD-associated disorders relevant to DCM.

Exploring the mechanism of diabetic cardiomyopathy treated with Qigui Qiangxin mixture based on UPLC-Q/TOF-MS, network pharmacology and experimental validation

Despite its effectiveness in treating diabetic cardiomyopathy (DCM), Qigui Qiangxin Mixture (QGQXM) remains unclear in terms of its active ingredients and specific mechanism of action. The purpose of this study was to explore the active ingredients and mechanism of action of QGQXM in the treatment of DCM through the comprehensive strategy of serum pharmacology, network pharmacology and combined with experimental validation. The active ingredients of QGQXM were analyzed using Ultra-performance liquid chromatography coupled with quadrupole time of flight mass spectrometry (UPLC-Q/TOF-MS). Network pharmacology was utilized to elucidate the mechanism of action of QGQXM for the treatment of DCM. Finally, in vivo validation was performed by intraperitoneal injection of STZ combined with high-fat feeding-induced DCM rat model. A total of 25 active compounds were identified in the drug-containing serum of rats, corresponding to 121 DCM-associated targets. GAPDH, TNF, AKT1, PPARG, EGFR, CASP3, and HIF1 were considered as the core therapeutic targets. Enrichment analysis showed that QGQXM mainly treats DCM by regulating PI3K-AKT, MAPK, mTOR, Insulin, Insulin resistance, and Apoptosis signaling pathways. Animal experiments showed that QGQXM improved cardiac function, attenuated the degree of cardiomyocyte injury and fibrosis, and inhibited apoptosis in DCM rats. Meanwhile, QGQXM also activated the PI3K/AKT signaling pathway, up-regulated Bcl-2, and down-regulated Caspase9, which may be an intrinsic mechanism for its anti-apoptotic effect. This study preliminarily elucidated the mechanism of QGQXM in the treatment of DCM and provided candidate compounds for the development of new drugs for DCM.

Schisandrin A Alleviates Spatial Learning and Memory Impairment in Diabetic Rats by Inhibiting Inflammatory Response and Through Modulation of the PI3K/AKT Pathway

Clinical and epidemiological research shows that people with diabetes mellitus frequently experience diabetic cognitive impairment. Schisandrin A (SchA), one of the lignans found in the dried fruit of Schisandra chinensis, has a variety of pharmacological effects on immune system control, apoptosis suppression, anti-oxidation and anti-inflammation. The goal of the current investigation was to clarify the probable neuro-protective effects of SchA against streptozotocin-induced diabetes deficiencies of the spatial learning and memory in rats. The outcomes show that SchA therapy effectively improved impaired glucose tolerance, fasting blood glucose level and serum insulin level in diabetic rats. Additionally, in the Morris water maze test, diabetic rats showed deficits in spatial learning and memory that were ameliorated by SchA treatment. Moreover, giving diabetic rats SchA reduced damage to the hippocampus structure and increased the production of synaptic proteins. Further research revealed that SchA therapy reduced diabetic-induced hippocampus neuron damage and the generation of Aβ, as demonstrated by the upregulated phosphorylation levels of insulin signaling pathway connected proteins and by the decreased expression levels of inflammatory-related factors. Collectively, these results suggested that SchA could improve diabetes-related impairments in spatial learning and memory, presumably by reducing inflammatory responses and regulating the insulin signaling system.

SGLT2 inhibitor improves the prognosis of patients with coronary heart disease and prevents in-stent restenosis

Coronary heart disease is a narrowing or obstruction of the vascular cavity caused by atherosclerosis of the coronary arteries, which leads to myocardial ischemia and hypoxia. At present, percutaneous coronary intervention (PCI) is an effective treatment for coronary atherosclerotic heart disease. Restenosis is the main limiting factor of the long-term success of PCI, and it is also a difficult problem in the field of intervention. Sodium-glucose cotransporter 2 (SGLT2) inhibitor is a new oral glucose-lowering agent used in the treatment of diabetes in recent years. Recent studies have shown that SGLT2 inhibitors can effectively improve the prognosis of patients after PCI and reduce the occurrence of restenosis. This review provides an overview of the clinical studies and mechanisms of SGLT2 inhibitors in the prevention of restenosis, providing a new option for improving the clinical prognosis of patients after PCI.

Targeting the programmed cell death (PCD) signaling mechanism with natural substances for the treatment of diabetic cardiomyopathy (DCM)

Diabetic cardiomyopathy (DCM) is one of the severe complications of diabetes, characterized by structural and functional abnormalities in the hearts of diabetic patients without hypertension, coronary heart disease, or valvular heart disease. DCM can progress to heart failure, which is a significant cause of death in diabetic patients, but currently, there is no effective treatment available. Programmed cell death (PCD) is a genetically regulated form of cell death that includes apoptosis, autophagy, necroptosis, ferroptosis, and pyroptosis. PCD is essential for tissue homeostasis and normal development of the body. DCM is a complex condition, and abnormalities in the cascade of PCD signaling have been observed in its pathological process, suggesting that targeting PCD could be a potential therapeutic strategy. Studies have shown that natural substances can effectively modulate PCD to intervene in the treatment of DCM, and their use is safe. This review explores the role of different forms of PCD in the pathogenesis of DCM and summarizes the research progress in targeting PCD with natural substances to treat DCM. It can serve as a basis for further research and drug development to provide new treatment strategies for DCM patients.

CD38 Deficiency Alleviates Diabetic Cardiomyopathy by Coordinately Inhibiting Pyroptosis and Apoptosis

Diabetic cardiomyopathy is one of the diabetes mellitus-induced cardiovascular complications that can result in heart failure in severe cases, which is characterized by cardiomyocyte apoptosis, local inflammation, oxidative stress, and myocardial fibrosis. CD38, a main hydrolase of NAD+ in mammals, plays an important role in various cardiovascular diseases, according to our previous studies. However, the role of CD38 in diabetes-induced cardiomyopathy is still unknown. Here, we report that global deletion of the CD38 gene significantly prevented diabetic cardiomyopathy induced by high-fat diet plus streptozotocin (STZ) injection in CD38 knockout (CD38-KO) mice. We observed that CD38 expression was up-regulated, whereas the expression of Sirt3 was down-regulated in the hearts of diabetic mice. CD38 deficiency significantly promoted glucose metabolism and improved cardiac functions, exemplified by increased left ventricular ejection fraction and fractional shortening. In addition, we observed that CD38 deficiency markedly decreased diabetes or high glucose and palmitic acid (HG + PA)-induced pyroptosis and apoptosis in CD38 knockout hearts or cardiomyocytes, respectively. Furthermore, we found that the expression levels of Sirt3, mainly located in mitochondria, and its target gene FOXO3a were increased in CD38-deficient hearts and cardiomyocytes with CD38 knockdown under diabetic induction conditions. In conclusion, we demonstrated that CD38 deficiency protected mice from diabetes-induced diabetic cardiomyopathy by reducing pyroptosis and apoptosis via activating NAD+/Sirt3/FOXO3a signaling pathways.

Impact of inflammation and anti-inflammatory modalities on diabetic cardiomyopathy healing: From fundamental research to therapy

Diabetic cardiomyopathy (DCM) is a prevalent cardiovascular complication of diabetes mellitus, characterized by high morbidity and mortality rates worldwide. However, treatment options for DCM remain limited. For decades, a substantial body of evidence has suggested that the inflammatory response plays a pivotal role in the development and progression of DCM. Notably, DCM is closely associated with alterations in inflammatory cells, exerting direct effects on major resident cells such as cardiomyocytes, vascular endothelial cells, and fibroblasts. These cellular changes subsequently contribute to the development of DCM. This article comprehensively analyzes cellular, animal, and human studies to summarize the latest insights into the impact of inflammation on DCM. Furthermore, the potential therapeutic effects of current anti-inflammatory drugs in the management of DCM are also taken into consideration. The ultimate goal of this work is to consolidate the existing literature on the inflammatory processes underlying DCM, providing clinicians with the necessary knowledge and tools to adopt a more efficient and evidence-based approach to managing this condition.

Iron accumulation and lipid peroxidation: implication of ferroptosis in diabetic cardiomyopathy

Diabetic cardiomyopathy (DC) is a serious heart disease caused by diabetes. It is unrelated to hypertension and coronary artery disease and can lead to heart insufficiency, heart failure and even death. Currently, the pathogenesis of DC is unclear, and clinical intervention is mainly symptomatic therapy and lacks effective intervention objectives. Iron overdose mediated cell death, also known as ferroptosis, is widely present in the physiological and pathological processes of diabetes and DC. Iron is a key trace element in the human body, regulating the metabolism of glucose and lipids, oxidative stress and inflammation, and other biological processes. Excessive iron accumulation can lead to the imbalance of the antioxidant system in DC and activate and aggravate pathological processes such as excessive autophagy and mitochondrial dysfunction, resulting in a chain reaction and accelerating myocardial and microvascular damage. In-depth understanding of the regulating mechanisms of iron metabolism and ferroptosis in cardiovascular vessels can help improve DC management. Therefore, in this review, we summarize the relationship between ferroptosis and the pathogenesis of DC, as well as potential intervention targets, and discuss and analyze the limitations and future development prospects of these targets.

High Glucose Activates Prolyl Hydroxylases and Disrupts HIF-α Signaling via the P53/TIGAR Pathway in Cardiomyocyte

The induction of hypoxia tolerance has emerged as a novel therapeutic strategy for the treatment of ischemic diseases. The disruption of hypoxic signaling by hyperglycemia has been shown to contribute to diabetic cardiomyopathy. In this study, we explored the potential molecular mechanisms by which high glucose (HG) impairs hypoxia-inducible factor-α (HIF-α) signaling in cardiomyocytes. The exposure of H9c2 cell lines to HG resulted in time- and concentration-dependent decreases in HIF-1α and HIF-2α expression together with an increase in prolyl hydroxylase-1,2 (PHD1 and PHD2) expression, the main regulators of HIF-α destabilization in the heart. The exposure of H9c2 cells to normal glucose (5.5 mM) and high glucose (15, 30, and 45 mM) led to dose-dependent increases in p53 and TIGAR and a decrease in SIRT3 expression. The pretreatment of H9c2 with p53 siRNA to knockdown p53 attenuated PHD1 and PHD2 expression, thus significantly enhancing HIF-1α and HIF-2α expression in H9c2 cells under HG conditions. Interestingly, pretreatment with p53 siRNA altered H9c2 cell metabolism by reducing oxygen consumption rate and increasing glycolysis. Similarly, pretreatment with TIGAR siRNA blunted HG-induced PHD1 and PHD2 expression. This was accompanied by an increase in HIF-1α and HIF-2α expression with a reduction in oxygen consumption rate in H9c2 cells. Furthermore, pretreatment with adenovirus-SIRT3 (Ad-SIRT3) significantly reduced the HG-induced expression of p53 and PHDs and increased HIF-1α levels in H9c2 cells. Ad-SIRT3 treatment also regulated PHDs-HIF-1α levels in the hearts of diabetic db/db mice. Our study revealed a novel role of the HG-induced disruption of PHDs-HIF-α signaling via upregulating p53 and TIGAR expression. Therefore, the p53/TIGAR signaling pathway may be a novel target for diabetic cardiomyopathy.

Danlou tablet inhibits high-glucose-induced cardiomyocyte apoptosis via the miR-34a-SIRT1 axis

Diabetic cardiomyopathy (DCM) is highly prevalent and increases the risk of heart failure and sudden death. Therefore, proper and effective treatments for DCM are in urgent demand. Danlou tablet (Dan) is reported to confer protective effects on several heart diseases. However, to our knowledge, whether Dan provides protection against DCM is unclear. In this study, we explored the effect of Dan on DCM with the in vitro DCM model using AC16 cardiomyocytes. We found that Dan treatment significantly reduced cardiomyocyte apoptosis and oxidative stress in high-glucose (HG)-treated cardiomyocytes, as evidenced by decreased Annexin V-FITC+ cardiomyocytes, intracellular reactive oxygen species (ROS) levels, Bax/Bcl2 ratio, and cleaved-Caspase3/Caspase3 ratio. Interestingly, Dan treatment caused a decreased level of microRNA-34a (miR-34a), which could enhance cardiomyocyte apoptosis. Furthermore, miR-34a mimic blocked Dan's effect in apoptosis prevention. Finally, we observed that the miR-34a mimic effectively decreased the level of sirtuin 1 (SIRT1), while the miR-34a inhibitor increased the level of SIRT1. And downregulation of SIRT1 effectively reversed the effect of miR-34a inhibitor on cardiomyocyte apoptosis. Taken together, our study showed that Dan prevented HG-induced cardiomyocyte apoptosis through downregulating miR-34a and upregulating SIRT1. Our study has provided experimental support for the potential use of Dan in treating DCM. Further detailed study of Dan and the underlying mechanisms may shed light on the prevention and treatment of DCM.

Mitochondrial Transfer Induced by Adipose-Derived Mesenchymal Stem Cell Transplantation Improves Cardiac Function in Rat Models of Ischemic Cardiomyopathy

Although mesenchymal stem cell transplantation has been successful in the treatment of ischemic cardiomyopathy, the underlying mechanisms remain unclear. Herein, we investigated whether mitochondrial transfer could explain the success of cell therapy in ischemic cardiomyopathy. Mitochondrial transfer in co-cultures of human adipose-derived mesenchymal stem cells and rat cardiomyocytes maintained under hypoxic conditions was examined. Functional recovery was monitored in a rat model of myocardial infarction following human adipose-derived mesenchymal stem cell transplantation. We observed mitochondrial transfer in vitro, which required the formation of cell-to-cell contacts and synergistically enhanced energy metabolism. Rat cardiomyocytes exhibited mitochondrial transfer 3 days following human adipose-derived mesenchymal stem cell transplantation to the ischemic heart surface post-myocardial infarction. We detected donor mitochondrial DNA in the recipient myocardium concomitant with a significant improvement in cardiac function. Mitochondrial transfer is vital for successful cell transplantation therapies and improves treatment outcomes in ischemic cardiomyopathy.

Ferroptosis: roles and molecular mechanisms in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a serious complication of type 1 and type 2 diabetes, which leads to the aggravation of myocardial fibrosis, disorders involving systolic and diastolic functions, and increased mortality of patients with diabetes through mechanisms such as glycolipid toxicity, inflammatory response, and oxidative stress. Ferroptosis is a form of iron-dependent regulatory cell death that is attributed to the accumulation of lipid peroxides and an imbalance in redox regulation. Increased production of lipid reactive oxygen species (ROS) during ferroptosis promotes oxidative stress and damages myocardial cells, leading to myocardial systolic and diastolic dysfunction. Overproduction of ROS is an important bridge between ferroptosis and DCM, and ferroptosis inhibitors may provide new targets for the treatment of patients with DCM.

The association between health-related quality of life, self-reported characteristics and 1- and 3-year mortality amongst cardiac patients with and without type 2 diabetes

PURPOSE

The objectives amongst cardiac patients with and without type 2 diabetes were to (i) describe self-reported characteristics as health-related quality of life (HRQoL), health behaviour, body mass index (BMI) and physical shape and to (ii) investigate the association between self-reported characteristics and 1- and 3-year mortality.

METHODS

Adult patients (≥ 18 years) discharged with a cardiac diagnosis were invited to participate in a national survey, DenHeart. Self-reported characteristics included HRQoL (EQ-5D-5L and HeartQol), health behaviour (alcohol and smoking), BMI and physical shape. Data were linked to national registries. The association between self-reported characteristics and 1- and 3-year mortality were investigated using the Cox Proportional Hazard Regression model, reported as hazard ratios (HR) with 95% confidence intervals (CI).

RESULTS

In total, 16,659 cardiac responders were included (n = 2,205 with type 2 diabetes, n = 14,454 without type 2 diabetes). Self-reported characteristics were worse amongst cardiac patients with type 2 diabetes compared to those without. After three years, the mortality rate was 14% amongst responders with diabetes and 7% amongst responders without type 2 diabetes (p ≤ 0.001). Better HRQoL was associated with a reduced risk of mortality amongst both groups. "Never been smoking" significantly reduced the risk of 1- and 3-year mortality amongst cardiac patients without diabetes, whereas good physical shape was associated with a reduced risk across both groups.

CONCLUSION

HRQoL, health behaviour, BMI and physical shape are significantly worse amongst cardiac patients with type 2 diabetes. Better HRQoL was associated with a reduced risk of mortality amongst both groups, whereas other self-reported characteristics and the mortality risk varied.

Homeostasis at different backgrounds: The roles of overlayed feedback structures in vertebrate photoadaptation

We have studied the resetting behavior of eight basic integral controller motifs with respect to different but constant backgrounds. We found that the controllers split symmetrically into two classes: one class, based on derepression of the compensatory flux, leads to more rapid resetting kinetics as backgrounds increase. The other class, which directly activates the compensatory flux, shows a slowing down in the resetting at increased backgrounds. We found a striking analogy between the resetting kinetics of vertebrate photoreceptors and controllers based on derepression, i.e. vertebrate rod or cone cells show decreased sensitivities and accelerated response kinetics as background illuminations increase. The central molecular model of vertebrate photoadaptation consists of an overlay of three negative feedback loops with cytosolic calcium ([Formula: see text]), cyclic guanosine monophosphate (cGMP) and cyclic nucleotide-gated (CNG) channels as components. While in one of the feedback loops the extrusion of [Formula: see text] by potassium-dependent sodium-calcium exchangers (NCKX) can lead to integral control with cGMP as the controlled variable, the expected robust perfect adaptation of cGMP is lost, because of the two other feedback loops. They avoid that [Formula: see text] levels become too high and toxic. Looking at psychophysical laws, we found that in all of the above mentioned basic controllers Weber's law is followed when a "just noticeable difference" (threshold) of 1% of the controlled variable's set-point was considered. Applying comparable threshold pulses or steps to the photoadaptation model we find, in agreement with experimental results, that Weber's law is followed for relatively high backgrounds, while Stephens' power law gives a better description when backgrounds are low. Limitations of our photoadaption model, in particular with respect to potassium/sodium homeostasis, are discussed. Finally, we discuss possible implication of background perturbations in biological controllers when compensatory fluxes are based on activation.

Diabetes mellitus — metabolic preconditioning in protecting the heart from ischemic damage?

The negative impact of diabetes mellitus (DM) on the cardiovascular system has been confirmed by numerous clinical studies. However, there are experimental studies that show an increase in the resistance of the heart to ischemic and reperfusion damage in animals with DM. This phenomenon is characterized by a smaller size of the infarct zone, better preservation of the contractile function of the myocardium, and a lower incidence of ischemic and reperfusion arrhythmias. It is assumed that at a certain stage in the development of DM, a “metabolic window” is formed, in which metabolic alterations at the cellular level trigger adaptive mechanisms that increase the viability of cardiomyocytes. Published data confirm that the magnitude of the protective effect induced by DM is comparable to, and in some cases even exceeds, the effect of the preconditioning phenomenon. It is recognized that the mechanisms that protect the heart from ischemic and reperfusion damage against the background of DM are universal and are associated with the modulation of the antioxidant system, apoptosis factors, pro-inflammatory cytokines, and signaling systems that ensure cell survival. The one of the main pathogenic factor in DM is hyperglycemia, but under stress it plays the role of an adaptive mechanism aimed at meeting the increased energy demand in pathological conditions. Probably, at a certain stage of DM, hyperglycemia becomes a trigger for the development of protective effects and activates not only signaling pathways, but also the restructuring of energy metabolism, which makes it possible to maintain ATP production at a sufficient level to maintain the vital activity of heart cells under ischemia/reperfusion conditions. It is possible that an increased level of glucose, accompanied by the activation of insulin-independent mechanisms of its entry into cells, as well as the availability of this energy substrate, will contribute to a better restoration of energy production in heart cells after a infarction, which, in turn, will significantly reduce the degree of myocardial damage and will help preserve the contractile function of the heart. Identification of the conditions and mechanisms of the cardioprotective phenomenon induced by DM will make it possible to simulate the metabolic state in which the protection of cardiomyocytes from damaging factors is realized.

The Importance of SGLT-2 Inhibitors as Both the Prevention and the Treatment of Diabetic Cardiomyopathy

According to the 2021 report of the International Diabetes Federation (IDF), there have been approximately 573 million cases of type 2 diabetes mellitus (T2DM) among adults, which sets the disease as a major concern in healthcare worldwide. The development of T2DM is strongly promoted by unhealthy lifestyle factors associated with urbanization and western civilization. The disease is associated with a broad list of systemic complications that can result in premature death, disability and significantly reduced quality of life. The most dramatic in their consequences are cardiovascular complications of T2DM. Our work focuses on one such complication that is specific for diabetes, named diabetic cardiomyopathy (DC). In this condition cardiac dysfunction occurs despite the absence of underlying hypertension, coronary artery disease and valvular disease, which suggest a leading role for metabolic disturbances as a cause. We aimed to establish the role of relatively new hypoglycaemic drugs that have taken the medical world by storm with their broad pleiotropic effects-SGLT-2 inhibitors-in the prevention and treatment of DC at any stage.

Unveiling the Vital Role of Long Non-Coding RNAs in Cardiac Oxidative Stress, Cell Death, and Fibrosis in Diabetic Cardiomyopathy

Diabetes mellitus is a burdensome public health problem. Diabetic cardiomyopathy (DCM) is a major cause of mortality and morbidity in diabetes patients. The pathogenesis of DCM is multifactorial and involves metabolic abnormalities, the accumulation of advanced glycation end products, myocardial cell death, oxidative stress, inflammation, microangiopathy, and cardiac fibrosis. Evidence suggests that various types of cardiomyocyte death act simultaneously as terminal pathways in DCM. Long non-coding RNAs (lncRNAs) are a class of RNA transcripts with lengths greater than 200 nucleotides and no apparent coding potential. Emerging studies have shown the critical role of lncRNAs in the pathogenesis of DCM, along with the development of molecular biology technologies. Therefore, we summarize specific lncRNAs that mainly regulate multiple modes of cardiomyopathy death, oxidative stress, and cardiac fibrosis and provide valuable insights into diagnostic and therapeutic biomarkers and strategies for DCM.

Functional components of Chinese rice wine can ameliorate diabetic cardiomyopathy through the modulation of autophagy, apoptosis, gut microbiota, and metabolites

Background

Dietary polyphenols, polypeptides, and oligosaccharides modulate inflammation and immunity by altering the composition of gut microbiota. The polyphenols and polypeptides in Chinese rice wine have protective effects against cardiovascular disease. In this study, we hypothesized that the polyphenols, polypeptides, and oligosaccharides in Chinese rice wine can ameliorate diabetic cardiomyopathy (DCM) by altering gut microbiota and metabolites.

Methods

Mice with DCM and high glucose cells were treated with rice wine polyphenols (RWPH), rice wine polypeptides (RWPE), and rice wine oligosaccharides. Cardiac function was evaluated by echocardiography and detection of myocardial injury markers. We observed the pathological structures using hematoxylin and eosin staining, Masson's trichrome staining, and transmission electron microscopy. The expression levels of autophagy-related proteins and stubRFP-sensGFP-LC3 fluorescence were measured to evaluate autophagy. We performed TUNEL staining and measured the levels of Bax, Bcl-2, and p53 to assess apoptosis. To analyze the effects of the rice wine functional components on the gut microbiota and metabolites of DCM mice, we performed fecal 16S-rDNA gene sequencing and serum untargeted metabolomics.

Results

Our results showed an increase in cardiac and mitochondrial function, promotion of autophagy, and inhibition of cardiomyocyte apoptosis, which indicates that RWPH and RWPE can ameliorate DCM. The abundance of Akkermansia and Desulfovibrio were reduced by the presence of RWPH and RWPE. The growth of the Lachnospiraceae_NK4A136_group and Clostridiales-unclassified were promoted by the presence of RWPH. Tryptophan metabolism-associated metabolites were increased and phenylalanine levels were reduced by the presence of RWPH and RWPE. The biosynthesis of primary bile acids was enhanced by the presence of RWPH.

Conclusion

Both RWPH and RWPE provided a protective effect against DCM by promoting autophagy, inhibiting apoptosis, and reversing both gut microbiota dysbiosis and metabolic dysregulation.

Nr2f2 Overexpression Aggravates Ferroptosis and Mitochondrial Dysfunction by Regulating the PGC-1α Signaling in Diabetes-Induced Heart Failure Mice

Diabetes is well recognized to increase the risk of heart failure, which is associated with higher mortality and morbidity. It is important for the development of novel therapeutic methods targeting heart failure in diabetic patients. Ferroptosis, an iron-dependent regulated cell death, has been implicated in the progression of diabetes-induced heart failure (DIHF). This study was designed to investigate the contribution of Nr2f2 to the activation of ferroptosis and mitochondrial dysfunction in DIHF. We established a diabetic model by a high-fat feeding diet combined with an intraperitoneal injection of streptozotocin. After 16 weeks, Nr2f2 expression was increased in heart tissue of DIHF mice. In vivo, DIHF mice overexpressing Nr2f2 (AAV9-cTNT-Nr2f2) exhibited severe heart failure and enhanced cardiac ferroptosis compared with DIHF control mice (AAV9-cTNT-ctrl), accompanied by mitochondrial dysfunction and aggravated oxidative stress reaction. In vitro, Nr2f2 knockdown ameliorated ferroptosis and mitochondrial dysfunction by negatively regulating PGC-1α, a crucial metabolic regulator. PGC-1α knockdown counteracted the protective effect of Nr2f2 knockdown. These data suggest that Nr2f2 promotes heart failure and ferroptosis in DIHF by modulating the PGC-1α signaling. Our study provides a new idea for the treatment of diabetes-induced heart failure.

Exercise Augments the Effect of SGLT2 Inhibitor Dapagliflozin on Experimentally Induced Diabetic Cardiomyopathy, Possible Underlying Mechanisms

One of the most prevalent cardiovascular problems linked with type 2 diabetes mellitus (T2DM) is diabetic cardiomyopathy (DCM). DCM is associated with myocardial oxidative stress, inflammation, apoptosis, suppressed autophagy, extracellular matrix remodeling, and fibrosis. The current study aims to investigate the protective effect of sodium-glucose transport 2 inhibitor (SGLT2i) dapagliflozin and/or exercise on DCM. Thirty adult male Sprague Dawley rats are used. T2DM is induced by a 6-week high-fat diet (HFD) followed by a single intraperitoneal (IP) injection of 35 mg/kg streptozotocin (STZ). Rats are divided into five groups, control, diabetic (DM), DM + swimming, DM + dapagliflozin, and DM + dapagliflozin and swimming. Serum glucose, insulin, insulin resistance (HOMA-IR), and cardiac enzymes (CK-MB and lactate dehydrogenase (LDH) are measured. Heart specimens are used for evaluation of cellular oxidative stress markers malondialdehyde (MDA), antioxidant enzymes, glutathione (GSH), and catalase (CAT), as well as mRNA expression of TGF-β, MMP9, IL-1β, and TNF-α. Stained sections with haematoxylin and eosin (H & E) and Masson trichrome are used for histopathological evaluation and detection of fibrosis, respectively. Immunohistochemical staining for apoptosis (caspase-3), and autophagy (LC3) are also carried out. The combinations of SGLT2i and exercise exhibited the most significant cardioprotective effect. It improved diabetic-induced histopathological alterations in the myocardium and attenuated the elevation of serum blood glucose, CK-MB, LDH, myocardial MDA, and mRNA expression of TNF-α, IL-1β, TGF-β, MMP9, and the immune expression of caspase-3. Moreover, this combination increased the serum insulin, myocardial antioxidants GSH and CAT, and increase the immune expression of the LC-3. In conclusion, a combination of SGLT2i and exercise exerted a better antioxidant, anti-inflammatory, and antifibrotic effect in DCM. Moreover, the combination enhances the autophagic capacity of the heart.

STAT4 regulates cardiomyocyte apoptosis in rat models of diabetic cardiomyopathy

OBJECTIVE

This study aimed to investigate the protective role of the signal transducer and activator of transcription 4 (STAT4) in diabetic cardiomyopathy.

MATERIALS AND METHODS

Male Sprague-Dawley (SD) rats (6-8 weeks old) were purchased from the Experimental Animal Center of Zhengzhou University. The rats were randomly divided into the control and diabetic cardiomyopathy groups. Rat models of diabetic cardiomyopathy were established by a high-sugar and high-fat diet combined with a peritoneal injection of streptozocin. Pathological changes in the heart were visualized using Hematoxylin-eosin (HE) staining and Masson's staining. Moreover, cell apoptosis was detected using terminal deoxyribonucleotidyl transferase (TdT)-mediated biotin-16-dUTP nick-end labeling (TUNEL) staining and Annexin V apoptosis detection kit. Furthermore, H9C2 cells were transfected with lentivirus overexpressing STAT4 and treated with high glucose. The CCK-8 assay was performed to determine cell viability. Finally, Western blotting was used to determine the expression of STAT4, Bax, and Bcl-2.

RESULTS

The myocardial tissue of the diabetic cardiomyopathy models showed hypertrophy, myocardial fibrosis and collagen deposition. Furthermore, TUNEL staining showed increased apoptosis and decreased expression of STAT4 in the myocardial cells. Moreover, the myocardial tissues of the DCM models showed increased expression of Bax/Bcl-2 and a high percentage of Annexin V positive cells. The H9C2 cells showed decreased expression of STAT4 following high glucose treatment. However, the H9C2 cells overexpressing STAT4 showed decreased expression of Bax/Bcl-2 and reduced percentage of Annexin V positive cells.

CONCLUSION

The DCM group had decreased myocardial expression of STAT4. Furthermore, overexpression of STAT4 was shown to reduce high glucose-induced apoptosis.

Preliminary evidence for the presence of multiple forms of cell death in diabetes cardiomyopathy

Diabetic mellitus (DM) is a common degenerative chronic metabolic disease often accompanied by severe cardiovascular complications (DCCs) as major causes of death in diabetic patients with diabetic cardiomyopathy (DCM) as the most common DCC. The metabolic disturbance in DCM generates the conditions/substrates and inducers/triggers and activates the signaling molecules and death executioners leading to cardiomyocyte death which accelerates the development of DCM and the degeneration of DCM to heart failure. Various forms of programmed active cell death including apoptosis, pyroptosis, autophagic cell death, autosis, necroptosis, ferroptosis and entosis have been identified and characterized in many types of cardiac disease. Evidence has also been obtained for the presence of multiple forms of cell death in DCM. Most importantly, published animal experiments have demonstrated that suppression of cardiomyocyte death of any forms yields tremendous protective effects on DCM. Herein, we provide the most updated data on the subject of cell death in DCM, critical analysis of published results focusing on the pathophysiological roles of cell death, and pertinent perspectives of future studies.

Effect of Aspirin on Mitochondrial Dysfunction and Stress in the Pancreas and Heart of Goto-Kakizaki Diabetic Rats

Our previous study in Goto-Kakizaki (GK) type 2 diabetic rats provided significant evidence that aspirin treatment improves pancreatic β-cell function by reducing inflammatory responses and improving glucose tolerance. In the present study, we aimed to elucidate the mechanism of action of aspirin on the pathophysiology and progression of type 2 diabetic complications in the heart and pancreas of insulin-resistant GK rats. Aspirin treatment demonstrated a reduction in mitochondrial reactive oxygen species (ROS) production and lipid peroxidation, accompanied by improved redox homeostasis. Furthermore, the recovery of metabolic and mitochondrial functions, as well as cytochrome P450 enzyme activities, which were altered in the pancreas and heart of GK rats, were observed. Aspirin treatment brought the activity of CYP 2E1 to the control level in both tissues, whereas the CYP 3A4 level decreased only in the pancreas. This suggests the tissue-specific differential metabolism of substrates in these rats. The recovery of redox homeostasis could be the key target in the improvement of oxidative-stress-dependent alterations in mitochondrial functions which, in turn, facilitated improved energy metabolism in these tissues in the aspirin-treated GK rats. These results may have implications in determining the therapeutic use of aspirin, either alone or in combination with other clinically approved therapies, in insulin-resistant type 2 diabetes.

Protective Effects of Huangqi Shengmai Yin on Type 1 Diabetes-Induced Cardiomyopathy by Improving Myocardial Lipid Metabolism

Diabetic cardiomyopathy (DCM) is one of the many complications of diabetes. DCM leads to cardiac insufficiency and myocardial remodeling and is the main cause of death in diabetic patients. Abnormal lipid metabolism plays an important role in the occurrence and development of DCM. Huangqi Shengmai Yin (HSY) has previously been shown to alleviate signs of heart disease. Here, we investigated whether HSY could improve cardiomyopathy caused by type 1 diabetes mellitus (T1DM) and improve abnormal lipid metabolism in the diabetic heart. Streptozotocin (STZ) was used to establish the T1DM mouse model, and T1DM mice were subsequently treated with HSY for eight weeks. The changes in the cardiac conduction system, histopathology, blood myocardial injury indices, and lipid content and expression of proteins related to lipid metabolism were evaluated. Our results showed that HSY could improve electrocardiogram; decrease the serum levels of CK-MB, LDH, and BNP; alleviate histopathological changes in cardiac tissue; and decrease myocardial lipid content in T1DM mice. These results indicate that HSY has a protective effect against T1DM-induced myocardial injury in mice and that this effect may be related to the improvement in myocardial lipid metabolism.

Nanomedicine for the treatment of diabetes-associated cardiovascular diseases and fibrosis

Cardiomyopathy and fibrosis are the main causes of heart failure in diabetes patients. For therapeutic purposes, a delivery system is required to enhance antidiabetic drug efficacy and specifically target profibrotic pathways in cardiomyocytes. Nanoparticles (NPs) have distinct advantages, including biocompatibility, bioavailability, targeting efficiency, and minimal toxicity, which make them ideal for antidiabetic treatment. In this review, we overview the latest information on the pathogenesis of cardiomyopathy and fibrosis in diabetes patients. We summarize how NP applications improve insulin and liraglutide efficacy and their sustained release upon oral administration. We provide a comprehensive review of the results of NP clinical trials in diabetes patients and of animal studies investigating the effects of NP-mediated anti-fibrotic treatments. Collectively, the application of advanced NP delivery systems in the treatment of cardiomyopathy and fibrosis in diabetes patients is a promising and innovative therapeutic strategy.

Glomerular Filtration Dysfunction is Associated with Cardiac Adverse Remodeling in Menopausal Diabetic Chinese Women

Background

Previous studies have showed that nephropathy was associated with cardiac structural changes and dysfunction among diabetic adults. However, information on the association of glomerular filtration dysfunction with the cardiac adverse remodeling is still limited in menopausal diabetic women. Therefore, we investigated whether impaired glomerular filtration function is associated with the cardiac adverse remodeling in menopausal Chinese women with type 2 diabetes mellitus (DM).

Methods

A total of 1231 hospitalized menopausal Chinese women with type 2 DM were collected retrospectively. The cross-sectional data of echocardiography were compared among estimated glomerular filtration rate (eGFR) categorized groups.

Results

In menopausal diabetic women, moderate to severe glomerular filtration dysfunction (eGFR <60 mL/min per 1.73m²) was found to be associated with enlarged left-side atrioventricular chambers, increased ventricular wall thickness, decreased cardiac function and dilated right ventricle (All P < 0.05).

Conclusion

Glomerular filtration dysfunction is associated with cardiac adverse structural remodeling and dysfunction in menopausal Chinese women with type 2 DM.

Melatonin protects the heart and pancreas by improving glucose homeostasis, oxidative stress, inflammation and apoptosis in T2DM-induced rats

Cardiomyopathy and pancreatic injury are health issues associated with type 2 diabetes mellitus (T2DM) and are characterized by elevated oxidative stress, inflammation and apoptosis. Melatonin (MLT) is a hormone with multifunctional antioxidant activity. The protective effects of MLT on the heart and pancreas during the early development of diabetic cardiomyopathy and pancreatic injury were investigated in male Wistar rats with T2DM. MLT (10 mg/kg) was administered daily by gavage for 15 days after diabetic induction. Treatment of diabetic rats with MLT significantly normalized the levels of serum glucose, HbA1-c, and the lipid profile and improved the insulin levels and insulin resistance compared with diabetic rats, affirming its antidiabetic effect. MLT significantly prevented the development of oxidative stress and sustained the levels of glutathione and glutathione peroxidase activity in the heart and pancreas of diabetic animals, indicating its antioxidant capacity. Additionally, MLT prevented the increase in proinflammatory cytokines and expression of Bax, caspase-3 and P53. Furthermore, MLT enhanced the anti-inflammatory cytokine IL-10 and antiapoptotic protein Bcl-2. MLT controlled the levels of troponin T and creatine kinase-MB and lactate dehydrogenase activity, indicating its anti-inflammatory and antiapoptotic effects. Histological examinations confirmed the protective effects of MLT on T2DM-induced injury in the myocardium, pancreas and islets of Langerhans. In conclusion, the protective effects of melatonin on the heart and pancreas during the early development of T2DM are attributed to its antihyperglycemic, antilipidemic and antioxidant influences as well as its remarkable anti-inflammatory and antiapoptotic properties.

Kuwanon G protects HT22 cells from advanced glycation end product-induced damage

The incidence of diabetic encephalopathy is increasing as the population ages. Evidence suggests that formation and accumulation of advanced glycation end products (AGEs) plays a pivotal role in disease progression, but limited research has been carried out in this area. A previous study demonstrated that Kuwanon G (KWG) had significant anti-oxidative stress and anti-inflammatory properties. As AGEs are oxidative products and inflammation is involved in their generation it is hypothesized that KWG may have effects against AGE-induced neuronal damage. In the present study, mouse hippocampal neuronal cell line HT22 was used. KWG was shown to significantly inhibit AGE-induced cell apoptosis in comparison with a control treatment, as determined by both MTT and flow cytometry. Compared with the AGEs group, expression of pro-apoptotic protein Bax was reduced and expression of anti-apoptotic protein Bcl-2 was increased in the AGEs + KWG group. Both intracellular and extracellular levels of acetylcholine and choline acetyltransferase were significantly elevated after KWG administration in comparison with controls whilethe level of acetylcholinesterase decreased. These changes in protein expression were accompanied by increased levels of superoxide dismutase and glutathione peroxidase synthesis and reduced production of malondialdehyde and reactive oxygen species. Intracellular signaling pathway protein levels were determined by western blot and immunocytochemistry. KWG administration was found to prevent AGE-induced changes to the phosphorylation levels of Akt, IκB-α, glycogen synthase kinase 3 (GSK3)-α and β, p38 MAPK and NF-κB p65 suggesting a potential neuroprotective effect of KWG against AGE-induced damage was via the PI3K/Akt/GSK3αβ signaling pathway. The findings of the present study suggest that KWG may be a potential treatment for diabetic encephalopathy.

The Endothelium as a Therapeutic Target in Diabetes: A Narrative Review and Perspective

Diabetes has reached worldwide epidemic proportions, and threatens to be a significant economic burden to both patients and healthcare systems, and an important driver of cardiovascular mortality and morbidity. Improvement in lifestyle interventions (which includes increase in physical activity via exercise) can reduce diabetes and cardiovascular disease mortality and morbidity. Encouraging a population to increase physical activity and exercise is not a simple feat particularly in individuals with co-morbidities (obesity, heart disease, stroke, peripheral vascular disease, and those with cognitive and physical limitations). Translation of the physiological benefits of exercise within that vulnerable population would be an important step for improving physical activity goals and a stopgap measure to exercise. In large part many of the beneficial effects of exercise are due to the introduction of pulsatile shear stress (PSS) to the vascular endothelium. PSS is a well-known stimulus for endothelial homeostasis, and induction of a myriad of pathways which include vasoreactivity, paracrine/endocrine function, fibrinolysis, inflammation, barrier function, and vessel growth and formation. The endothelial cell mediates the balance between vasoconstriction and relaxation via the major vasodilator endothelial derived nitric oxide (eNO). eNO is critical for vasorelaxation, increasing blood flow, and an important signaling molecule that downregulates the inflammatory cascade. A salient feature of diabetes, is endothelial dysfunction which is characterized by a reduction of the bioavailability of vasodilators, particularly nitric oxide (NO). Cellular derangements in diabetes are also related to dysregulation in Ca²⁺ handling with increased intracellular Ca²⁺overload, and oxidative stress. PSS increases eNO bioavailability, reduces inflammatory phenotype, decreases intracellular Ca²⁺ overload, and increases antioxidant capacity. This narrative review and perspective will outline four methods to non-invasively increase PSS; Exercise (the prototype for increasing PSS), Enhanced External Counterpulsation (EECP), Whole Body Vibration (WBV), Passive Simulated Jogging and its predicate device Whole Body Periodic Acceleration, and will discuss current knowledge on their use in diabetes.

The cardiovascular complications of diabetes: a striking link through protein glycation

Diabetes mellitus is a predominant cause of mortality and morbidity worldwide. One of its serious health problems is cardiovascular complications. Advanced glycation end products (AGEs) are a group of heterogeneous toxic oxidant compounds that are formed after a non-enzymatic reaction between monosaccharides and free amino groups of proteins, compound lipids, and nucleic acids. AGE interacts with various types of cells through a receptor for AGE (RAGE). The interaction between AGE and RAGE is responsible for a cascade of inflammation, oxidative stress, and disruption of calcium homeostasis in cardiac cells of diabetic patients. There is striking evidence that the AGE/RAGE axis with its consequences on inflammation and oxidative stress plays a major role in the development of cardiovascular complications. Therefore, considering AGE as a therapeutic target with foreseeable results would be a wise direction for future research. Interestingly, several studies on nutraceutical, pharmaceutical, and natural products have begun to reveal promising therapeutic results, and this could lead to better health outcomes for many diabetic patients worldwide. This article discusses the current literature addressing the connection between protein glycation and diabetes cardiovascular complications and suggests future avenues of research.

The role of CD36 in cardiovascular disease

CD36, also known as the scavenger receptor B2, is a multifunctional receptor widely expressed in various organs. CD36 plays a crucial role in the uptake of long-chain fatty acids, the main metabolic substrate in myocardial tissue. The maturation and transportation of CD36 is regulated by post-translational modifications, including phosphorylation, ubiquitination, glycosylation, and palmitoylation. CD36 is decreased in pathological cardiac hypertrophy caused by ischaemia-reperfusion and pressure overload, and increased in diabetic cardiomyopathy and atherosclerosis. Deficiency of CD36 alleviates diabetic cardiomyopathy and atherosclerosis, while overexpression of CD36 eliminates ischaemia-reperfusion damage, together suggesting that CD36 is closely associated with the progression of cardiovascular diseases and may be a new therapeutic target. This review summarizes the regulation and post-translational modifications of CD36 and evaluates its role in cardiovascular diseases and its potential as a therapeutic target.

25-OH-PPD inhibits hypertrophy on diabetic cardiomyopathy via the PI3k/Akt/GSK-3β signaling pathway

The present study investigated the inhibitory effects and the associated mechanism of the compound 25-OH-PPD (PPD) on cardiac hypertrophy, fibrosis and inflammation. The signaling pathways associated with diabetic mellitus cardiomyopathy (DMCM) were investigated using a rat model. DMCM Sprague-Dawley rats were induced by injection of streptozotocin. The animals were divided into 5 groups as follows: Normal group (NG group), diabetic group, PPD treatment group, PPD/LY294002 group (inhibitor of PI3K/Akt) and PPD/LiCl group [inhibitor of glycogen synthase kinase (GSK) 3β]. The studies were carried out during the 12 weeks following induction of diabetes and the levels of plasma brain natriuretic peptide (BNP), creatine phosphokinase isoenzyme (CK-MB) were measured. In addition, the volume of myocardial collagen fraction (CVF) was tested. The expression levels of the inflammatory cytokines, including transforming growth factor beta 1 (TGF-β1), connective tissue growth factor (CTGF), cell adhesion molecules α-smooth muscle actin (α-SMA) and vascular adhesion molecule 1 (VCAM-1) and associated signaling proteins (Akt, GSK-3β) were measured by biochemical analyses. The levels of BNP and CK-MB, the volume of CVF, the expression levels of TGF-β1, CTGF, α-SMA and VCAM-1 in the diabetic group were higher compared with those of the normal control group (P<0.05). Conversely, the levels of these molecules were significantly decreased in the PPD treatment groups (P<0.05). The aforementioned effects were partially eliminated in the PPD/LY294002 and PPD/LiCl groups. In addition, PPD treatment significantly increased the expression levels of p-Akt and decreased the levels of phosphorylated GSK-3β compared with those of the DMCM group (P<0.05). The data demonstrated that the protective effects of 25-OH-PPD against DMCM may be attributed to the PI3k/Akt/GSK-3β signaling pathway, via the suppression of the α-SMA/VCAM axis and the downregulation of TGF-β1 and CTGF expression.

Ketogenic Diet Ameliorates Cardiac Dysfunction via Balancing Mitochondrial Dynamics and Inhibiting Apoptosis in Type 2 Diabetic Mice

The ketogenic diet (KD) has been widely used in clinical studies and shown to hace an anti-diabetic effect, but the underlying mechanisms have not been fully elaborated. Our aim was to investigate the effects and the underling mechanisms of the KD on cardiac function in db/db mice. In the present study, db/db mice were subjected to a normal diet (ND) or KD. Fasting blood glucose, cardiac function and morphology, mitochondrial dynamics, oxidative stress, and apoptosis were measured 8 weeks post KD treatment. Compared with the ND, the KD improved glycemic control and protected against diabetic cardiomyopathy in db/db mice, and improved mitochondrial function, as well as reduced oxidative stress were observed in hearts. In addition, KD treatment exerted an anti-apoptotic effect in the heart of db/db mice. Further data showed that the PI3K/Akt pathway was involved in this protective effect. Our data demonstrated that KD treatment ameliorates cardiac dysfunction by inhibiting apoptosis via activating the PI3K-Akt pathway in type 2 diabetic mice, suggesting that the KD is a promising lifestyle intervention to protect against diabetic cardiomyopathy.

Distinct Types of Cell Death and the Implication in Diabetic Cardiomyopathy

Diabetic cardiomyopathy (DCM) is a chronic complication of diabetes mellitus, characterized by abnormalities of myocardial structure and function. Researches on the models of type 1 and type 2 diabetes mellitus as well as the application of genetic engineering technology help in understanding the molecular mechanism of DCM. DCM has multiple hallmarks, including hyperglycemia, insulin resistance, increased free radical production, lipid peroxidation, mitochondrial dysfunction, endothelial dysfunction, and cell death. Essentially, cell death is considered to be the terminal pathway of cardiomyocytes during DCM. Morphologically, cell death can be classified into four different forms: apoptosis, autophagy, necrosis, and entosis. Apoptosis, as type I cell death, is the fastest form of cell death and mainly occurs depending on the caspase proteolytic cascade. Autophagy, as type II cell death, is a degradation process to remove damaged proteins, dysfunctional organelles and commences by the formation of autophagosome. Necrosis is type III cell death, which contains a great diversity of cell death processes, such as necroptosis and pyroptosis. Entosis is type IV cell death, displaying “cell-in-cell” cytological features and requires the engulfing cells to execute. There are also some other types of cell death such as ferroptosis, parthanatos, netotic cell death, lysosomal dependent cell death, alkaliptosis or oxeiptosis, which are possibly involved in DCM. Drugs or compounds targeting the signals involved in cell death have been used in clinics or experiments to treat DCM. This review briefly summarizes the mechanisms and implications of cell death in DCM, which is beneficial to improve the understanding of cell death in DCM and may propose novel and ideal strategies in future.

Berberine for prevention of dementia associated with diabetes and its comorbidities: A systematic review

BACKGROUND

A growing number of epidemiological studies indicate that metabolic syndrome (MetS) and its associated features play a key role in the development of certain degenerative brain disorders, including Alzheimer's disease and vascular dementia. Produced by several different medicinal plants, berberine is a bioactive alkaloid with a wide range of pharmacological effects, including antidiabetic effects. However, it is not clear whether berberine could prevent the development of dementia in association with diabetes.

OBJECTIVE

To give an overview of the therapeutic potential of berberine as a treatment for dementia associated with diabetes.

SEARCH STRATEGY

Database searches A and B were conducted using PubMed and ScienceDirect. In search A, studies on berberine's antidementia activities were identified using "berberine" and "dementia" as search terms. In search B, recent studies on berberine's effects on diabetes were surveyed using "berberine" and "diabetes" as search terms.

INCLUSION CRITERIA

Clinical and preclinical studies that investigated berberine's effects associated with MetS and cognitive dysfunction were included.

DATA EXTRACTION AND ANALYSIS

Data from studies were extracted by one author, and checked by a second; quality assessments were performed independently by two authors.

RESULTS

In search A, 61 articles were identified, and 22 original research articles were selected. In search B, 458 articles were identified, of which 101 were deemed relevant and selected. Three duplicates were removed, and a total of 120 articles were reviewed for this study. The results demonstrate that berberine exerts beneficial effects directly in the brain: enhancing cholinergic neurotransmission, improving cerebral blood flow, protecting neurons from inflammation, limiting hyperphosphorylation of tau and facilitating β-amyloid peptide clearance. In addition, evidence is growing that berberine is effective against diabetes and associated disorders, such as atherosclerosis, cardiomyopathy, hypertension, hepatic steatosis, diabetic nephropathy, gut dysbiosis, retinopathy and neuropathy, suggesting indirect benefits for the prevention of dementia.

CONCLUSION

Berberine could impede the development of dementia via multiple mechanisms: preventing brain damages and enhancing cognition directly in the brain, and indirectly through alleviating risk factors such as metabolic dysfunction, and cardiovascular, kidney and liver diseases. This study provided evidence to support the value of berberine in the prevention of dementia associated with MetS.

Exercise as A Potential Therapeutic Target for Diabetic Cardiomyopathy: Insight into the Underlying Mechanisms

Diabetes mellitus is associated with cardiovascular, ophthalmic, and renal comorbidities. Among these, diabetic cardiomyopathy (DCM) causes the most severe symptoms and is considered to be a major health problem worldwide. Exercise is widely known as an effective strategy for the prevention and treatment of many chronic diseases. Importantly, the onset of complications arising due to diabetes can be delayed or even prevented by exercise. Regular exercise is reported to have positive effects on diabetes mellitus and the development of DCM. The protective effects of exercise include prevention of cardiac apoptosis, fibrosis, oxidative stress, and microvascular diseases, as well as improvement in cardiac mitochondrial function and calcium regulation. This review summarizes the recent scientific findings to describe the potential mechanisms by which exercise may prevent DCM and heart failure.

Long-term moderate intensity exercise alleviates myocardial fibrosis in type 2 diabetic rats via inhibitions of oxidative stress and TGF-β1/Smad pathway

Exercise has an effect on the reduction of myocardial fibrosis in diabetic rats as previously reported, in which oxidative stress and the TGF-β1/Smad signaling pathway may play key roles. There is little direct experimental evidence that exercise alleviates myocardial fibrosis in type 2 diabetes mellitus (T2DM). Here we established a type 2 diabetic model by using streptozotocin and a high-fat diet. Rats were divided into groups of normal control (NC), T2DM and T2DM plus exercise (T2DME). The T2DME group received further treadmill training at moderate intensity for 8 weeks. Histological and biochemical methods were used to detect the benefits of exercise to T2DM. Results showed that the weight of rats in the T2DM group dropped dramatically, along with significant increases in blood glucose, myocardial fibrosis and oxidative stress, associated with upregulated expression of factors of myocardial fibrosis, except Smad7. Exercise largely reversed T2DM-induced alterations in factors of myocardial fibrosis, including suppressing expression of MMP-2, CTGF, TGF-β1, p-Smad2 and p-Smad3, and increased expression of TIMP-1 and Smad7. Therefore, exercise might be considered an alternative therapeutic remedy for diabetic cardiomyopathy.

The gut microbiota and diabetic cardiomyopathy in humans

Type 2 diabetes (DT2) increases the risk of cardiovascular events and cardiac insufficiency. This insufficiency is mostly post-ischaemic in nature, but other aetiologies are possible in this high-risk population. In patients with DT2, diabetic cardiomyopathy is a recognized cause of cardiac insufficiency secondary to chronic hyperglycaemia and myocardial lipotoxicity, which promotes cardiomyocyte hypertrophy (and, frequently, apoptosis of these cells), interstitial fibrosis and a decrease in myocardial contractile performance. Several studies have shown that diabetic cardiomyopathy is associated with modifications to the intestinal microbiota, and changes in the synthesis of bacterial metabolites and their diffusion into the host, some of which appear to have direct deleterious effects on cardiac contractility. These findings open up new perspectives for pathophysiological studies by establishing the presence of a 'microbiota-myocardium' axis and raising the possibility of innovative new treatments. Correction of intestinal dysbiosis in patients with cardiac insufficiency could, therefore, constitute an innovative therapeutic approach to cases of this disease with a poor prognosis.

Berberine Ameliorates Spatial Learning Memory Impairment and Modulates Cholinergic Anti-Inflammatory Pathway in Diabetic Rats

Background: Cognitive impairment caused by diabetes has been recognized. Berberine is well known for its resistance to peripheral lesions, but it is rarely used for the treatment of spatial learning and memory caused by diabetes. This study explored the mechanism of berberine to alleviate cognitive impairment via the cholinergic anti-inflammatory and insulin signaling pathways.

Methods: Morris water maze was used to appraise spatial learning and memory. Positron-emission tomography (PET) imaging was adopted to detect the transport of glucose, and blood/cerebrospinal fluid (CSF) glucose was checked using commercial blood glucose meter. Insulin level was measured by ELISA kit and β-Amyloid (Aβ) formation was observed by Congo red staining. Western-blot was performed to appraise protein expression.

Results: We found that berberine rectified some aberrant changes in signal molecules concerning inflammation, and cholinergic and insulin signaling pathways in the hippocampus. Furthermore, CSF/blood glucose, inflammatory response or acetyl cholinesterase enzyme (AChE) activity were reduced by berberine. Additionally, acetylcholine levels were enhanced after berberine treatment in diabetic rats. Finally, Aβ formation in diabetic hippocampus was inhibited and spatial learning memory was ameliorated by berberine.

Discussion: In conclusion, berberine clears Aβ deposit and consequently ameliorates spatial learning memory impairment via the activation of the cholinergic anti-inflammatory and insulin signaling pathways in diabetic rats.

SGLT2 inhibition with empagliflozin attenuates myocardial oxidative stress and fibrosis in diabetic mice heart

Background

Hyperglycaemia associated with myocardial oxidative stress and fibrosis is the main cause of diabetic cardiomyopathy. Empagliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor has recently been reported to improve glycaemic control in patients with type 2 diabetes in an insulin-independent manner. The aim of this study was to investigate the effect of empagliflozin on myocardium injury and the potential mechanism in type 2 diabetic KK-Ay mice.

Methods

Thirty diabetic KK-Ay mice were administered empagliflozin (10 mg/kg/day) by oral gavage daily for 8 weeks. After 8 weeks, heart structure and function were evaluated by echocardiography. Oxidants and antioxidants were measured and cardiac fibrosis was analysed using immunohistochemistry, Masson’s trichrome stain and Western blot.

Results

Results showed that empagliflozin improved diabetic myocardial structure and function, decreased myocardial oxidative stress and ameliorated myocardial fibrosis. Further study indicated that empagliflozin suppressed oxidative stress and fibrosis through inhibition of the transforming growth factor β/Smad pathway and activation of Nrf2/ARE signaling.

Conclusions

Glycaemic control with empagliflozin significantly ameliorated myocardial oxidative stress injury and cardiac fibrosis in diabetic mice. Taken together, these results indicate that the empagliflozin is a promising agent for the prevention and treatment of diabetic cardiomyopathy.

Proarrhythmic Remodeling of Calcium Homeostasis in Cardiac Disease; Implications for Diabetes and Obesity

A rapid growth in the incidence of diabetes and obesity has transpired to a major heath issue and economic burden in the postindustrial world, with more than 29 million patients affected in the United States alone. Cardiovascular defects have been established as the leading cause of mortality and morbidity of diabetic patients. Over the last decade, significant progress has been made in delineating mechanisms responsible for the diminished cardiac contractile function and enhanced propensity for malignant cardiac arrhythmias characteristic of diabetic disease. Rhythmic cardiac contractility relies upon the precise interplay between several cellular Ca²⁺ transport protein complexes including plasmalemmal L-type Ca²⁺ channels (LTCC), Na⁺-Ca²⁺ exchanger (NCX1), Sarco/endoplasmic Reticulum (SR) Ca²⁺-ATPase (SERCa2a) and ryanodine receptors (RyR2s), the SR Ca²⁺ release channels. Here we provide an overview of changes in Ca²⁺ homeostasis in diabetic ventricular myocytes and discuss the therapeutic potential of targeting Ca²⁺ handling proteins in the prevention of diabetes-associated cardiomyopathy and arrhythmogenesis.

Proarrhythmic Remodeling of Calcium Homeostasis in Cardiac Disease; Implications for Diabetes and Obesity

A rapid growth in the incidence of diabetes and obesity has transpired to a major heath issue and economic burden in the postindustrial world, with more than 29 million patients affected in the United States alone. Cardiovascular defects have been established as the leading cause of mortality and morbidity of diabetic patients. Over the last decade, significant progress has been made in delineating mechanisms responsible for the diminished cardiac contractile function and enhanced propensity for malignant cardiac arrhythmias characteristic of diabetic disease. Rhythmic cardiac contractility relies upon the precise interplay between several cellular Ca²⁺ transport protein complexes including plasmalemmal L-type Ca²⁺ channels (LTCC), Na⁺-Ca²⁺ exchanger (NCX1), Sarco/endoplasmic Reticulum (SR) Ca²⁺-ATPase (SERCa2a) and ryanodine receptors (RyR2s), the SR Ca²⁺ release channels. Here we provide an overview of changes in Ca²⁺ homeostasis in diabetic ventricular myocytes and discuss the therapeutic potential of targeting Ca²⁺ handling proteins in the prevention of diabetes-associated cardiomyopathy and arrhythmogenesis.