Exosomes in Diabetic Cardiomyopathy: The Next-Generation Therapeutic Targets?

Cardiovascular complications of diabetes: role of non-coding RNAs in the crosstalk between immune and cardiovascular systems

Diabetes mellitus, a group of metabolic disorders characterized by high levels of blood glucose caused by insulin defect or impairment, is a major risk factor for cardiovascular diseases and related mortality. Patients with diabetes experience a state of chronic or intermittent hyperglycemia resulting in damage to the vasculature, leading to micro- and macro-vascular diseases. These conditions are associated with low-grade chronic inflammation and accelerated atherosclerosis. Several classes of leukocytes have been implicated in diabetic cardiovascular impairment. Although the molecular pathways through which diabetes elicits an inflammatory response have attracted significant attention, how they contribute to altering cardiovascular homeostasis is still incompletely understood. In this respect, non-coding RNAs (ncRNAs) are a still largely under-investigated class of transcripts that may play a fundamental role. This review article gathers the current knowledge on the function of ncRNAs in the crosstalk between immune and cardiovascular cells in the context of diabetic complications, highlighting the influence of biological sex in such mechanisms and exploring the potential role of ncRNAs as biomarkers and targets for treatments. The discussion closes by offering an overview of the ncRNAs involved in the increased cardiovascular risk suffered by patients with diabetes facing Sars-CoV-2 infection.

Oncogenic Role of Exosomal Circular and Long Noncoding RNAs in Gastrointestinal Cancers

Circular RNAs (circRNAs) and long noncoding RNAs (lncRNAs) are differentially expressed in gastrointestinal cancers. These noncoding RNAs (ncRNAs) regulate a variety of cellular activities by physically interacting with microRNAs and proteins and altering their activity. It has also been suggested that exosomes encapsulate circRNAs and lncRNAs in cancer cells. Exosomes are then discharged into the extracellular environment, where they are taken up by other cells. As a result, exosomal ncRNA cargo is critical for cell-cell communication within the cancer microenvironment. Exosomal ncRNAs can regulate a range of events, such as angiogenesis, metastasis, immune evasion, drug resistance, and epithelial-to-mesenchymal transition. To set the groundwork for developing novel therapeutic strategies against gastrointestinal malignancies, a thorough understanding of circRNAs and lncRNAs is required. In this review, we discuss the function and intrinsic features of oncogenic circRNAs and lncRNAs that are enriched within exosomes.

Emerging roles of exosomal miRNAs in diabetes mellitus

Exosomes are small extracellular vesicles 40-160 nm in diameter that are secreted by almost all cell types. Exosomes can carry diverse cargo including RNA, DNA, lipids, proteins, and metabolites. Exosomes transfer substances and information between cells by circulating in body fluids and are thus involved in diverse physiological and pathological processes in the human body. Recent studies have closely associated exosomal microRNAs (miRNAs) with various human diseases, including diabetes mellitus (DM), which is a complex multifactorial metabolic disorder disease. Exosomal miRNAs are emerging as pivotal regulators in the progression of DM, mainly in terms of pancreatic β-cell injury and insulin resistance. Exosomal miRNAs are closely associated with DM-associated complications, such as diabetic retinopathy (DR), diabetic nephropathy (DN), and diabetic cardiomyopathy (DCM), etc. Further investigations of the mechanisms of action of exosomal miRNAs and their role in DM will be valuable for the thorough understanding of the physiopathological process of DM. Here, we have summarized recent findings regarding exosomal miRNAs associated with DM to provide a new strategy for identifying potential diagnostic biomarkers and drug targets for the early diagnosis and treatment, respectively, of DM.

Extracellular vesicle interplay in cardiovascular pathophysiology

Extracellular vesicles (EVs) are nanosized lipid bilayer-delimited particles released from cells that mediate intercellular communications and play a pivotal role in various physiological and pathological processes. Subtypes of EVs may include plasma membrane ectosomes or microvesicles and endosomal origin exosomes, although functional distinctions remain unclear. EVs carry cargo proteins, nucleic acids (RNA and DNA), lipids, and metabolites. By presenting or transferring this cargo to recipient cells, EVs can trigger cellular responses. We summarize contemporary understanding of EV biogenesis, composition, and function, with an emphasis on the role of EVs in the cardiovascular system. In addition, we outline the functional relevance of EVs in cardiovascular pathophysiology, further highlighting their potential for diagnostic and therapeutic applications.

Exosomes Could Offer New Options to Combat the Long-Term Complications Inflicted by Gestational Diabetes Mellitus

Gestational diabetes Mellitus (GDM) is a complex clinical condition that promotes pelvic floor myopathy, thus predisposing sufferers to urinary incontinence (UI). GDM usually regresses after birth. Nonetheless, a GDM history is associated with higher risk of subsequently developing type 2 diabetes, cardiovascular diseases (CVD) and UI. Some aspects of the pathophysiology of GDM remain unclear and the associated pathologies (outcomes) are poorly addressed, simultaneously raising public health costs and diminishing women's quality of life. Exosomes are small extracellular vesicles produced and actively secreted by cells as part of their intercellular communication system. Exosomes are heterogenous in their cargo and depending on the cell sources and environment, they can mediate both pathogenetic and therapeutic functions. With the advancement in knowledge of exosomes, new perspectives have emerged to support the mechanistic understanding, prediction/diagnosis and ultimately, treatment of the post-GMD outcomes. Here, we will review recent advances in knowledge of the role of exosomes in GDM and related areas and discuss the possibilities for translating exosomes as therapeutic agents in the GDM clinical setting.

The Art of Intercellular Wireless Communications: Exosomes in Heart Disease and Therapy

Exosomes are nanoscale membrane-bound extracellular vesicles secreted by most eukaryotic cells in the body that facilitates intercellular communication. Exosomes carry several signaling biomolecules, including miRNA, proteins, enzymes, cell surface receptors, growth factors, cytokines and lipids that can modulate target cell biology and function. Due to these capabilities, exosomes have emerged as novel intercellular signaling mediators in both homeostasis and pathophysiological conditions. Recent studies document that exosomes (both circulating or released from heart tissue) have been actively involved in cardiac remodeling in response to stressors. Also, exosomes released from progenitor/stem cells have protective effects in heart diseases and shown to have regenerative potential in the heart. In this review we discuss- the critical role played by circulating exosomes released from various tissues and from cells within the heart in cardiac health; the gap in knowledge that needs to be addressed to promote future research; and exploitation of recent advances in exosome engineering to develop novel therapy.

Extracellular vesicles in diagnostics and therapy of the ischaemic heart: Position Paper from the Working Group on Cellular Biology of the Heart of the European Society of Cardiology

Extracellular vesicles (EVs)—particularly exosomes and microvesicles (MVs)—are attracting considerable interest in the cardiovascular field as the wide range of their functions is recognized. These capabilities include transporting regulatory molecules including different RNA species, lipids, and proteins through the extracellular space including blood and delivering these cargos to recipient cells to modify cellular activity. EVs powerfully stimulate angiogenesis, and can protect the heart against myocardial infarction. They also appear to mediate some of the paracrine effects of cells, and have therefore been proposed as a potential alternative to cell-based regenerative therapies. Moreover, EVs of different sources may be useful biomarkers of cardiovascular disease identities. However, the methods used for the detection and isolation of EVs have several limitations and vary widely between studies, leading to uncertainties regarding the exact population of EVs studied and how to interpret the data. The number of publications in the exosome and MV field has been increasing exponentially in recent years and, therefore, in this ESC Working Group Position Paper, the overall objective is to provide a set of recommendations for the analysis and translational application of EVs focussing on the diagnosis and therapy of the ischaemic heart. This should help to ensure that the data from emerging studies are robust and repeatable, and optimize the pathway towards the diagnostic and therapeutic use of EVs in clinical studies for patient benefit.

Epicardial adipose tissue as a metabolic transducer: role in heart failure and coronary artery disease

Obesity and diabetes are strongly associated with metabolic and cardiovascular disorders including dyslipidemia, coronary artery disease, hypertension, and heart failure. Adipose tissue is identified as a complex endocrine organ, which by exerting a wide array of regulatory functions at the cellular, tissue and systemic levels can have profound effects on the cardiovascular system. Different terms including "epicardial," "pericardial," and "paracardial" have been used to describe adipose tissue deposits surrounding the heart. Epicardial adipose tissue (EAT) is a unique and multifaceted fat depot with local and systemic effects. The functional and anatomic proximity of EAT to the myocardium enables endocrine, paracrine, and vasocrine effects on the heart. EAT displays a large secretosome, which regulates physiological and pathophysiological processes in the heart. Perivascular adipose tissue (PVAT) secretes adipose-derived relaxing factor, which is a "cocktail" of cytokines, adipokines, microRNAs, and cellular mediators, with a potent effect on paracrine regulation of vascular tone, vascular smooth muscle cell proliferation, migration, atherosclerosis-susceptibility, and restenosis. Although there are various physiological functions of the EAT and PVAT, a phenotypic transformation can lead to a major pathogenic role in various cardiovascular diseases. The equilibrium between the physiological and pathophysiological properties of EAT is very delicate and susceptible to the influences of intrinsic and extrinsic factors. Various adipokines secreted from EAT and PVAT have a profound effect on the myocardium and coronary arteries; targeting these adipokines could be an important therapeutic approach to counteract cardiovascular disease.

Targeting miRNA for Therapy of Juvenile and Adult Diabetic Cardiomyopathy

Prevalence of diabetes mellitus (DM), a multifactorial disease often diagnosed with high blood glucose levels, is rapidly increasing in the world. Association of DM with multi-organ dysfunction including cardiomyopathy makes it a leading cause of morbidity and mortality. There are two major types of DM: type 1 DM (T1D) and type 2 DM (T2D). T1D is diagnosed by reduced levels of insulin and high levels of glucose in the blood. It is caused due to pancreatic beta cell destruction/loss, and mostly found in juveniles (juvenile DM). T2D is diagnosed by increased levels of insulin and glucose in the blood. It is caused due to insulin receptor dysfunction, and mostly found in the adults (adult DM). Both T1D and T2D impair cardiac muscle function, which is referred to as diabetic cardiomyopathy. We and others have reported that miRNAs, a novel class of tiny non-coding regulatory RNAs, are differentially expressed in the diabetic heart and they contribute to diabetic cardiomyopathy. Here, we elaborated the biogenesis of miRNA, how miRNA regulates a gene, cardioprotective roles of different miRNAs including miRNAs present in exosomes, underlying molecular mechanisms by which miRNA ameliorates diabetic cardiomyopathy, and the role of miRNA as a potential therapeutic target for juvenile and adult diabetic cardiomyopathy.

Inflammageing and metaflammation: The yin and yang of type 2 diabetes

Type 2 diabetes mellitus (T2DM) is characterised by chronic low-grade inflammation, recently referred to as 'metaflammation', a relevant factor contributing to the development of both diabetes and its complications. Nonetheless, 'canonical' anti-inflammatory drugs do not yield satisfactory results in terms of prevention of diabetes progression and of cardiovascular events, suggesting that the causal mechanisms fostering metaflammation deserve further research to identify new druggable targets. Metaflammation resembles ageing-induced low-grade inflammation, previously referred to as inflammageing, in terms of clinical presentation and the molecular profile, pointing to a common aetiology for both conditions. Along with the mechanisms proposed to fuel inflammageing, here we dissect a plethora of pathological cascades triggered by gluco- and lipotoxicity, converging on candidate phenomena possibly explaining the enduring pro-inflammatory program observed in diabetic tissues, i.e. persistent immune-system stimulation, accumulation of senescent cells, epigenetic rearrangements, and alterations in microbiota composition. We discuss the possibility of harnessing these recent discoveries in future therapies for T2DM. Moreover, we review recent evidence regarding the ability of diets and physical exercise to modulate selected inflammatory pathways relevant for the diabetic pathology. Finally, we examine the latest findings showing putative anti-inflammatory mechanisms of anti-hyperglycaemic agents with proven efficacy against T2DM-induced cardiovascular complications, in order to gain insights into quickly translatable therapeutic approaches.

Regulating microRNA expression: at the heart of diabetes mellitus and the mitochondrion

Type 2 diabetes mellitus is a major risk factor for cardiovascular disease and mortality. Uncontrolled type 2 diabetes mellitus results in a systemic milieu of increased circulating glucose and fatty acids. The development of insulin resistance in cardiac tissue decreases cellular glucose import and enhances mitochondrial fatty acid uptake. While triacylglycerol and cytotoxic lipid species begin to accumulate in the cardiomyocyte, the energy substrate utilization ratio of free fatty acids to glucose changes to almost entirely free fatty acids. Accumulating evidence suggests a role of miRNA in mediating this metabolic transition. Energy substrate metabolism, apoptosis, and the production and response to excess reactive oxygen species are regulated by miRNA expression. The current momentum for understanding the dynamics of miRNA expression is limited by a lack of understanding of how miRNA expression is controlled. While miRNAs are important regulators in both normal and pathological states, an additional layer of complexity is added when regulation of miRNA regulators is considered. miRNA expression is known to be regulated through a number of mechanisms, which include, but are not limited to, epigenetics, exosomal transport, processing, and posttranscriptional sequestration. The purpose of this review is to outline how mitochondrial processes are regulated by miRNAs in the diabetic heart. Furthermore, we will highlight the regulatory mechanisms, such as epigenetics, exosomal transport, miRNA processing, and posttranslational sequestration, that participate as regulators of miRNA expression. Additionally, current and future treatment strategies targeting dysfunctional mitochondrial processes in the diseased myocardium, as well as emerging miRNA-based therapies, will be summarized.

Circulating levels and characterization of microparticles in patients with different degrees of glucose tolerance

Background

Microparticles (MPs) are vesicular structures shed from endothelial or circulating blood cells, after activation or apoptosis, and can be considered markers of vascular damage. We aimed to determine the levels of circulating MPs, their content of miRNA-126-3p and 5p, and their relationship with early endothelial activation/damage, in patients with different degree of glucose tolerance.

Methods

CD62E⁺, CD62P⁺, CD142⁺, CD45⁺ circulating MPs, their apoptotic (AnnexinV⁺) fractions, and miRNA-126 expression were determined in 39 prediabetic (PreDM), 68 type 2 diabetic (T2DM), and 53 control (NGT) subjects, along with main anthropometric and biochemical measurements. MPs were analysed by flow cytometry. miRNA-126 was measured by quantitative real-time PCR. Plasma antioxidant capacity was determined by electronic spin resonance; ICAM-1, and VCAM-1 by ELISA.

Results

Activated endothelial cell-derived MPs (CD62E⁺) were significantly increased in PreDM and T2DM in comparison to NGT (p < 0.0001). AnnexinV⁺/CD62E⁺ MPs and Annexin V⁺ MPs were significantly increased in T2DM compared to PreDM and NGT (p < 0.001); other MPs were not significantly different among groups. Plasma antioxidant capacity was significantly decreased in PreDM and T2DM compared to NGT (p = 0.001); VCAM-1 significantly increased in PreDM and T2DM in comparison to NGT (p = 0.001). miR-126-3p expression, but not miR-126-5p, in MPs, decreased significantly and progressively from NGT, to PreDM, and T2DM (p < 0.001). In PreDM and T2DM, CD62E⁺ MPs level was significantly and negatively associated with plasma glucose (p = 0.004).

Conclusion

We show for the first time that circulating CD62E⁺ MPs level and miR-126-3p content in MPs are abnormal in subjects with pre-diabetes; the content of miR-126-3p correlates with markers of endothelial inflammation, such as VCAM-1, plasma antioxidant capacity, and microparticles, well-accepted markers of endothelial dysfunction.

Cardioprotection mediated by exosomes is impaired in the setting of type II diabetes but can be rescued by the use of non-diabetic exosomes in vitro

Many patients with ischaemic heart disease also have diabetes. As myocardial infarction is a major cause of mortality and morbidity in these patients, treatments that increase cell survival in response to ischaemia and reperfusion are needed. Exosomes—nano‐sized, lipid vesicles released from cells—can protect the hearts of non‐diabetic rats. We previously showed that exosomal HSP70 activates a cardioprotective signalling pathway in cardiomyocytes culminating in ERK1/2 and HSP27 phosphorylation. Here, we investigated whether the exosomal cardioprotective pathway remains intact in the setting of type II diabetes. Exosomes were isolated by differential centrifugation from non‐diabetic and type II diabetic patients, from non‐diabetic and Goto Kakizaki type II diabetic rats, and from normoglycaemic and hyperglycaemic endothelial cells. Exosome size and number were not significantly altered by diabetes. CD81 and HSP70 exosome markers were increased in diabetic rat exosomes. However, exosomes from diabetic rats no longer activated the ERK1/2 and HSP27 cardioprotective pathway and were no longer protective in a primary rat cardiomyocytes model of hypoxia and reoxygenation injury. Hyperglycaemic culture conditions were sufficient to impair protection by endothelial exosomes. Importantly, however, exosomes from non‐diabetic rats retained the ability to protect cardiomyocytes from diabetic rats. Exosomes from diabetic plasma have lost the ability to protect cardiomyocytes, but protection can be restored with exosomes from non‐diabetic plasma. These results support the concept that exosomes may be used to protect cardiomyocytes against ischaemia and reperfusion injury, even in the setting of type II diabetes.

Pathological Effects of Exosomes in Mediating Diabetic Cardiomyopathy

Diabetic subjects are at risk of developing cardiovascular disease, which accounts for 60-80% of diabetes-related mortality. Atherosclerosis is still considered as a leading cause of heart failure in diabetic patients, but it could also be an intrinsic and long-term effect of contractile cardiac cells malfunction, known as diabetic cardiomyopathy (DCM). Pathologically, this cardiac dysfunction is manifested by inflammation, apoptosis, fibrosis, hypertrophy and altered cardiomyocytes metabolism. However, the underlying molecular mechanisms of DCM pathophysiology are not clearly understood. Recent and several studies have suggested that exosomes are contributed to the regulation of cell-to-cell communication. Therefore, their in-depth investigation can interpret the complex pathophysiology of DCM. Structurally, exosomes are membrane-bounded vesicles (10-200 nm in diameter), which are actively released from all types of cells and detected in all biological fluids. They carry a wide array of bioactive molecules, including mRNAs, none-coding RNAs (e.g., microRNAs, lncRNAs, circRNAs, etc), proteins and lipids. Importantly, the abundance and nature of loaded molecules inside exosomes fluctuate with cell types and pathological conditions. This chapter summarizes currently available studies on the exosomes' role in the regulation of diabetic cardiomyopathy. Specifically, the advances on the pathological effects of exosomes in diabetic cardiomyopathy as well as the therapeutic potentials and perspectives are also discussed.