Endothelial Extracellular Vesicles Enriched in microRNA-34a Predict New-Onset Diabetes in Coronavirus Disease 2019 (COVID-19) Patients: Novel Insights for Long COVID Metabolic Sequelae.

Emerging evidence indicates that the relationship between coronavirus disease 2019 (COVID-19) and diabetes is 2-fold: 1) it is known that the presence of diabetes and other metabolic alterations poses a considerably high risk to develop a severe COVID-19; 2) patients who survived a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection have an increased risk of developing new-onset diabetes. However, the mechanisms underlying this association are mostly unknown, and there are no reliable biomarkers to predict the development of new-onset diabetes. In the present study, we demonstrate that a specific microRNA (miR-34a) contained in circulating extracellular vesicles released by endothelial cells reliably predicts the risk of developing new-onset diabetes in COVID-19. This association was independent of age, sex, body mass index (BMI), hypertension, dyslipidemia, smoking status, and D-dimer. SIGNIFICANCE STATEMENT: We demonstrate for the first time that a specific microRNA (miR-34a) contained in circulating extracellular vesicles released by endothelial cells is able to reliably predict the risk of developing diabetes after having contracted coronavirus disease 2019 (COVID-19). This association was independent of age, sex, body mass index (BMI), hypertension, dyslipidemia, smoking status, and D-dimer. Our findings are also relevant when considering the emerging importance of post-acute sequelae of COVID-19, with systemic manifestations observed even months after viral negativization (long COVID).

Exosomal miR-145 and miR-885 Regulate Thrombosis in COVID-19.

We hypothesized that exosomal microRNAs could be implied in the pathogenesis of thromboembolic complications in coronavirus disease 2019 (COVID-19). We isolated circulating exosomes from patients with COVID-19, and then we divided our population in two arms based on the D-dimer level on hospital admission. We observed that exosomal miR-145 and miR-885 significantly correlate with D-dimer levels. Moreover, we demonstrate that human endothelial cells express the main cofactors needed for the internalization of the "Severe acute respiratory syndrome coronavirus 2" (SARS-CoV-2), including angiotensin converting enzyme 2, transmembrane protease serine 2, and CD-147. Interestingly, human endothelial cells treated with serum from COVID-19 patients release significantly less miR-145 and miR-885, exhibit increased apoptosis, and display significantly impaired angiogenetic properties compared with cells treated with non-COVID-19 serum. Taken together, our data indicate that exosomal miR-145 and miR-885 are essential in modulating thromboembolic events in COVID-19. SIGNIFICANCE STATEMENT: This work demonstrates for the first time that two specific microRNAs (namely miR-145 and miR-885) contained in circulating exosomes are functionally involved in thromboembolic events in COVID-19. These findings are especially relevant to the general audience when considering the emerging prominence of post-acute sequelae of COVID-19 systemic manifestations known as Long COVID.

Empagliflozin Improves the MicroRNA Signature of Endothelial Dysfunction in Patients with Heart Failure with Preserved Ejection Fraction and Diabetes.

Endothelial dysfunction represents a key mechanism underlying heart failure with preserved ejection fraction (HFpEF), diabetes mellitus (DM), and frailty. However, reliable biomarkers to monitor endothelial dysfunction in these patients are lacking. In this study, we evaluated the expression of a panel of circulating microRNAs (miRs) involved in the regulation of endothelial function in a population of frail older adults with HFpEF and DM treated for 3 months with empagliflozin, metformin, or insulin. We identified a distinctive pattern of miRs that were significantly regulated in HFpEF patients compared to healthy controls and to HFpEF patients treated with the sodium glucose cotransporter 2 (SGLT2) inhibitor empagliflozin. Three miRs were significantly downregulated (miR-126, miR-342-3p, and miR-638) and two were significantly upregulated (miR-21 and miR-92) in HFpEF patients compared to healthy controls. Strikingly, two of these miRs (miR-21 and miR-92) were significantly reduced in HFpEF patients after the 3-month treatment with empagliflozin, whereas no significant differences in the profile of endothelial miRs were detected in patients treated with metformin or insulin. Taken together, our findings demonstrate for the first time that specific circulating miRs involved in the regulation of endothelial function are significantly regulated in frail HFpEF patients with DM and in response to SGLT2 inhibition. SIGNIFICANCE STATEMENT: We have identified a novel microRNA signature functionally involved in the regulation of endothelial function that is significantly regulated in frail patients with HFpEF and diabetes. Moreover, the treatment with the SGLT2 inhibitor empagliflozin caused a modification of some of these microRNAs in a direction that was opposite to what observed in HFpEF patients, indicating a rescue of endothelial function. Our findings are relevant for clinical practice inasmuch as we were able to establish novel biomarkers of disease and response to therapy.

Sortilin and hypertension.

PURPOSE OF REVIEW: The current review aims to present the latest scientific updates on the role of Sortilin in the pathophysiology of hypertension. RECENT FINDINGS: The main focus of this systematic overview is on the functional contribution of Sortilin to the pathogenesis of hypertension. Sortilin is a glycoprotein mostly known for its actions as a trafficking molecule directing proteins to specific secretory or endocytic compartments of the cell. Emerging evidence indicates that Sortilin is associated with pathological conditions, including inflammation, arteriosclerosis, dyslipidemia, insulin resistance, and vascular calcification. Most recently, Sortilin has been shown to finely control endothelial function and to drive hypertension by modulating sphingolipid/ceramide homeostasis and by triggering oxidative stress. SUMMARY: The latest findings linking Sortilin and hypertension that are herein discussed can inspire novel areas of research which could eventually lead to the discovery of new therapeutic strategies in cardiovascular medicine.

L-Arginine in diabetes: clinical and preclinical evidence.

L-Arginine (L-Arg), is a semi-essential amino acid involved in the formation of nitric oxide. The functional relevance of L-Arg in diabetes mellitus has been evaluated both in animal models and in human subjects. In the literature there are several lines of evidence indicating that L-Arg has beneficial effects in diabetes and numerous studies advocate its administration to attenuate glucose intolerance in diabetic patients. Here we present a comprehensive overview of the main studies exploring the effects of L-Arg in diabetes, including preclinical and clinical reports on this topic.

Molecular Mechanisms Underlying Pluripotency and Self-Renewal of Embryonic Stem Cells.

Embryonic stem cells (ESCs) are derived from the inner cell mass (ICM) of the blastocyst. ESCs have two distinctive properties: ability to proliferate indefinitely, a feature referred as "self-renewal", and to differentiate into different cell types, a peculiar characteristic known as "pluripotency". Self-renewal and pluripotency of ESCs are finely orchestrated by precise external and internal networks including epigenetic modifications, transcription factors, signaling pathways, and histone modifications. In this systematic review, we examine the main molecular mechanisms that sustain self-renewal and pluripotency in both murine and human ESCs. Moreover, we discuss the latest literature on human naïve pluripotency.

Diabetes and restenosis.

Restenosis, defined as the re-narrowing of an arterial lumen after revascularization, represents an increasingly important issue in clinical practice. Indeed, as the number of stent placements has risen to an estimate that exceeds 3 million annually worldwide, revascularization procedures have become much more common. Several investigators have demonstrated that vessels in patients with diabetes mellitus have an increased risk restenosis. Here we present a systematic overview of the effects of diabetes on in-stent restenosis. Current classification and updated epidemiology of restenosis are discussed, alongside the main mechanisms underlying the pathophysiology of this event. Then, we summarize the clinical presentation of restenosis, emphasizing the importance of glycemic control in diabetic patients. Indeed, in diabetic patients who underwent revascularization procedures a proper glycemic control remains imperative.

Tirzepatide: A Systematic Update.

Tirzepatide is a new molecule capable of controlling glucose blood levels by combining the dual agonism of Glucose-Dependent Insulinotropic Polypeptide (GIP) and Glucagon-Like Peptide-1 (GLP-1) receptors. GIP and GLP1 are incretin hormones: they are released in the intestine in response to nutrient intake and stimulate pancreatic beta cell activity secreting insulin. GIP and GLP1 also have other metabolic functions. GLP1, in particular, reduces food intake and delays gastric emptying. Moreover, Tirzepatide has been shown to improve blood pressure and to reduce Low-Density Lipoprotein (LDL) cholesterol and triglycerides. Tirzepatide efficacy and safety were assessed in a phase III SURPASS 1-5 clinical trial program. Recently, the Food and Drug Administration approved Tirzepatide subcutaneous injections as monotherapy or combination therapy, with diet and physical exercise, to achieve better glycemic blood levels in patients with diabetes. Other clinical trials are currently underway to evaluate its use in other diseases. The scientific interest toward this novel, first-in-class medication is rapidly increasing. In this comprehensive and systematic review, we summarize the main results of the clinical trials investigating Tirzepatide and the currently available meta-analyses, emphasizing novel insights into its adoption in clinical practice for diabetes and its future potential applications in cardiovascular medicine.

miR-142 Targets TIM-1 in Human Endothelial Cells: Potential Implications for Stroke, COVID-19, Zika, Ebola, Dengue, and Other Viral Infections.

T-cell immunoglobulin and mucin domain 1 (TIM-1) has been recently identified as one of the factors involved in the internalization of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in human cells, in addition to angiotensin-converting enzyme 2 (ACE2), transmembrane serine protease 2 (TMPRSS2), neuropilin-1, and others. We hypothesized that specific microRNAs could target TIM-1, with potential implications for the management of patients suffering from coronavirus disease 2019 (COVID-19). By combining bioinformatic analyses and functional assays, we identified miR-142 as a specific regulator of TIM-1 transcription. Since TIM-1 has been implicated in the regulation of endothelial function at the level of the blood-brain barrier (BBB) and its levels have been shown to be associated with stroke and cerebral ischemia-reperfusion injury, we validated miR-142 as a functional modulator of TIM-1 in human brain microvascular endothelial cells (hBMECs). Taken together, our results indicate that miR-142 targets TIM-1, representing a novel strategy against cerebrovascular disorders, as well as systemic complications of SARS-CoV-2 and other viral infections.

Mitochondrial membrane potential.

The mitochondrial membrane potential (ΔΨm) generated by proton pumps (Complexes I, III and IV) is an essential component in the process of energy storage during oxidative phosphorylation. Together with the proton gradient (ΔpH), ΔΨm forms the transmembrane potential of hydrogen ions which is harnessed to make ATP. The levels of ΔΨm and ATP in the cell are kept relatively stable although there are limited fluctuations of both these factors that can occur reflecting normal physiological activity. However, sustained changes in both factors may be deleterious. A long-lasting drop or rise of ΔΨm vs normal levels may induce unwanted loss of cell viability and be a cause of various pathologies. Among other factors, ΔΨm plays a key role in mitochondrial homeostasis through selective elimination of dysfunctional mitochondria. It is also a driving force for transport of ions (other than H+) and proteins which are necessary for healthy mitochondrial functioning. We propose additional potential mechanisms for which ΔΨm is essential for maintenance of cellular health and viability and provide recommendations how to accurately measure ΔΨm in a cell and discuss potential sources of artifacts.

A long-linker conjugate of fluorescein and triphenylphosphonium as mitochondria-targeted uncoupler and fluorescent neuro- and nephroprotector.

BACKGROUND: Limited uncoupling of oxidative phosphorylation is known to be beneficial in various laboratory models of diseases. Linking a triphenyl-phosphonium cation to fluorescein through a decyl (C10) spacer yields a fluorescent uncoupler, coined mitoFluo, that selectively accumulates in energized mitochondria (Denisov et al., Chem.Commun. 2014). METHODS: Proton-transport activity of mitoFluo was tested in liposomes reconstituted with bacteriorhodopsin. To examine the uncoupling action on mitochondria, we monitored mitochondrial membrane potential in parallel with oxygen consumption. Neuro- and nephroprotecting activity was detected by a limb-placing test and a kidney ischemia/reperfusion protocol, respectively. RESULTS: We compared mitoFluo properties with those of its newly synthesized analog having a short (butyl) spacer (C4-mitoFluo). MitoFluo, but not C4-mitoFluo, caused collapse of mitochondrial membrane potential resulting in stimulation of mitochondrial respiration. The dramatic difference in the uncoupling activity of mitoFluo and C4-mitoFluo was in line with the difference in their protonophoric activity on a lipid membrane. The accumulation of mitoFluo in mitochondria was more pronounced than that of C4-mitoFluo. MitoFluo decreased the rate of ROS production in mitochondria. MitoFluo was effective in preventing consequences of brain trauma in rats: it suppressed trauma-induced brain swelling and reduced a neurological deficit. Besides, mitoFluo attenuated acute kidney injury after ischemia/reperfusion in rats. CONCLUSIONS: A long alkyl linker was proved mandatory for mitoFluo to be a mitochondria- targeted uncoupler. MitoFluo showed high protective efficacy in certain models of oxidative stress-related diseases. GENERAL SIGNIFICANCE: MitoFluo is a candidate for developing therapeutic and fluorescence imaging agents to treat brain and kidney pathologies.

Intercellular Signalling Cross-Talk: To Kill, To Heal and To Rejuvenate.

Intercellular cross-talk is a fundamental process for spreading cellular signals between neighbouring and distant cells to properly regulate their metabolism, to coordinate homeostasis, adaptation and survival as a functional tissue and organ. In this review, we take a close molecular view of the underpinning molecular mechanisms of such complex intercellular communications. There are several studied forms of cell-to-cell communications considered crucial for the maintenance of multicellular organisms. The most explored is paracrine signalling which is realised through the release of diffusible signalling factors (e.g., hormones or growth factors) from a donor cell and taken up by a recipient cell. More challenging is communication which also does not require the direct contact of cells but is organised through the release of named signalling factors embedded in membranous structures. This mode of cell-to-cell communication is executed through the transfer of extracellular vesicles. Two other types of cellular cross-communication require direct contact of communicating cells. In one type, cells are connected by gap junctions which regulate permeation of chemical signals addressed to a neighbouring cell. Another type of cell communication is organised to provide a cytosolic continuum of adjacent cells joined by different tiny cell membrane extensions coined tunnelling nanotubes. In this review, we consider the various cell communication modes in the heart, and examples of processes in non-cardiac cells which may have mechanistic parallels with cardiovascular cells.

The mitochondrion as a key regulator of ischaemic tolerance and injury.

Vascular pathologies pose a significant health problem because of their wide prevalence and high impact on the rate of mortality. Blockade of blood flow in major blood vessels leads to ischaemia associated with oxidative stress, where mitochondria act as a major source of reactive oxygen species (ROS). While low levels of ROS perform a necessary function in normal cellular signalling and metabolism, elevated levels under pathological conditions are detrimental both at the cell and organ level. While cellular oxygenation is necessary to maintain tissue viability, a key pathological occurrence when restoring blood flow to ischaemic tissues is the subsequent burst of ROS generation following reoxygenation, resulting in a cascade of ROS-induced ROS release. This oxygen 'paradox' is a constraint in clinical practice, that is, the need for rapid and maximal restoration of blood flow while at the same time minimising the harmful impact of reperfusion injury on damaged tissues. Mitochondria play a central role in many signalling pathways, including cardioprotection against ischaemic injury and ROS signalling, thus the main target of any anti-ischaemic protective or post-injury therapeutic strategy should include mitochondria. At present, one of the most effective strategies that provide mitochondrial tolerance to ischaemia is ischaemic preconditioning. In addition, pharmacological preconditioning which mimics intrinsic natural protective mechanisms has proven effective at priming biological mechanisms to confront ischaemic damage. This review will discuss the role of mitochondria in contributing to acute ischaemia-reperfusion (IR) injury, and mechanisms of cardioprotection in respect to mitochondrial signalling pathways.

Prediabetes Increases the Risk of Frailty in Prefrail Older Adults With Hypertension: Beneficial Effects of Metformin.

BACKGROUND: Prediabetes has garnered increasing attention due to its association with cardiovascular conditions, especially hypertension, which heightens the risk of prefrailty and frailty among older individuals. METHODS: We screened elders with prefrail hypertension from March 2021 to January 2023. We assessed the correlation linking cognitive dysfunction (Montreal Cognitive Assessment score), insulin resistance (triglyceride-to-glucose index), and physical impairment (5-meter gait speed). Then, we measured the risk of developing frailty after a 1-year follow-up period, adjusting the outcome using multivariable Cox regression analysis. We also investigated the impact of administering 500 mg of metformin once daily to a subset of frail subjects for an additional 6 months. RESULTS: We assessed the relationship between the triglyceride-to-glucose index and the Montreal Cognitive Assessment score, observing a significant correlation (r, 0.880; P<0.0001). Similarly, we analyzed the association between the triglyceride-to-glucose index and 5-meter gait speed, uncovering a significant link between insulin resistance and physical impairment (r, 0.809; P<0.0001). Prediabetes was found to significantly (P<0.0001) elevate the risk of frailty development compared with individuals without prediabetes by the end of the 1-year follow-up, a finding confirmed via multivariable analysis with Cox regression. Furthermore, among the subgroup of subjects who developed frailty, those who received metformin exhibited a significant decrease in frailty levels (P<0.0001). CONCLUSIONS: Insulin resistance and prediabetes play substantial roles in the development of cognitive and physical impairments, highlighting their importance in managing hypertension, even before the onset of frank diabetes. Metformin, a well-established drug for the treatment of diabetes, has shown favorable effects in mitigating frailty.

Functional Role of Taurine in Aging and Cardiovascular Health: An Updated Overview.

Taurine, a naturally occurring sulfur-containing amino acid, has attracted significant attention in recent years due to its potential health benefits. Found in various foods and often used in energy drinks and supplements, taurine has been studied extensively to understand its impact on human physiology. Determining its exact functional roles represents a complex and multifaceted topic. We provide an overview of the scientific literature and present an analysis of the effects of taurine on various aspects of human health, focusing on aging and cardiovascular pathophysiology, but also including athletic performance, metabolic regulation, and neurological function. Additionally, our report summarizes the current recommendations for taurine intake and addresses potential safety concerns. Evidence from both human and animal studies indicates that taurine may have beneficial cardiovascular effects, including blood pressure regulation, improved cardiac fitness, and enhanced vascular health. Its mechanisms of action and antioxidant properties make it also an intriguing candidate for potential anti-aging strategies.

COVID-19 Causes Ferroptosis and Oxidative Stress in Human Endothelial Cells.

Oxidative stress and endothelial dysfunction have been shown to play crucial roles in the pathophysiology of COVID-19 (coronavirus disease 2019). On these grounds, we sought to investigate the impact of COVID-19 on lipid peroxidation and ferroptosis in human endothelial cells. We hypothesized that oxidative stress and lipid peroxidation induced by COVID-19 in endothelial cells could be linked to the disease outcome. Thus, we collected serum from COVID-19 patients on hospital admission, and we incubated these sera with human endothelial cells, comparing the effects on the generation of reactive oxygen species (ROS) and lipid peroxidation between patients who survived and patients who did not survive. We found that the serum from non-survivors significantly increased lipid peroxidation. Moreover, serum from non-survivors markedly regulated the expression levels of the main markers of ferroptosis, including GPX4, SLC7A11, FTH1, and SAT1, a response that was rescued by silencing TNFR1 on endothelial cells. Taken together, our data indicate that serum from patients who did not survive COVID-19 triggers lipid peroxidation in human endothelial cells.

miR-4432 Targets FGFBP1 in Human Endothelial Cells.

MicroRNAs (miRs) are small non-coding RNAs that modulate the expression of several target genes. Fibroblast growth factor binding protein 1 (FGFBP1) has been associated with endothelial dysfunction at the level of the blood-brain barrier (BBB). However, the underlying mechanisms are mostly unknown and there are no studies investigating the relationship between miRs and FGFBP1. Thus, the overarching aim of the present study was to identify and validate which miR can specifically target FGFBP1 in human brain microvascular endothelial cells, which represent the best in vitro model of the BBB. We were able to identify and validate miR-4432 as a fundamental modulator of FGFBP1 and we demonstrated that miR-4432 significantly reduces mitochondrial oxidative stress, a well-established pathophysiological hallmark of hypertension.