Glucose-induced oxidative stress and accelerated aging in endothelial cells are mediated by the depletion of mitochondrial SIRTs

The potential of flavonoids to mitigate cellular senescence in cardiovascular disease

Aging is one of the most significant factors affecting cardiovascular health, with cellular senescence being a central hallmark. Senescent cells (SCs) secrete a specific set of signaling molecules known as the senescence-associated secretory phenotype (SASP). The SASP has a remarkable impact on age-associated diseases, particularly cardiovascular diseases (CVD). Targeting SCs through anti-aging therapies represents a novel strategy to effectively retard senescence and attenuate disease progression. Accumulating evidence demonstrates that the flavonoids, widely presented in fruits and vegetables worldwide, can delay or treat CVD via selectively eliminating SCs (senolytics) and modulating SASPs (senomorphics). Nevertheless, only sporadic research has illustrated the application of flavonoids in targeting SCs for CVD, which requires further exploration. This review recapitulates the hallmarks and key molecular mechanisms involved in cellular senescence, then summarizes senescence of different types of cardiac cells and describes the mechanisms by which cellular senescence affects CVD development. The discussion culminates with the potential use of flavonoids via exerting their biological effects on cellular senescence to reduce CVD incidence. This summary will provide valuable insights for cardiovascular drug design, development and clinical applications leveraging flavonoids.

Senescent endothelial cells: a potential target for diabetic retinopathy

Diabetic retinopathy (DR) is a diabetic complication that results in visual impairment and relevant retinal diseases. Current therapeutic strategies on DR primarily focus on antiangiogenic therapies, which particularly target vascular endothelial growth factor and its related signaling transduction. However, these therapies still have limitations due to the intricate pathogenesis of DR. Emerging studies have shown that premature senescence of endothelial cells (ECs) in a hyperglycemic environment is involved in the disease process of DR and plays multiple roles at different stages. Moreover, these surprising discoveries have driven the development of senotherapeutics and strategies targeting senescent endothelial cells (SECs), which present challenging but promising prospects in DR treatment. In this review, we focus on the inducers and mechanisms of EC senescence in the pathogenesis of DR and summarize the current research advances in the development of senotherapeutics and strategies that target SECs for DR treatment. Herein, we highlight the role played by key factors at different stages of EC senescence, which will be critical for facilitating the development of future innovative treatment strategies that target the different stages of senescence in DR.

Transcriptomic Profile of Lin-Sca1+c-kit (LSK) cells in db/db mice with long-standing diabetes

BACKGROUND

The Lin-Sca1+c-Kit+ (LSK) fraction of the bone marrow (BM) comprises multipotent hematopoietic stem cells (HSCs), which are vital to tissue homeostasis and vascular repair. While diabetes affects HSC homeostasis overall, the molecular signature of mRNA and miRNA transcriptomic under the conditions of long-standing type 2 diabetes (T2D;>6 months) remains unexplored.

METHODS

In this study, we assessed the transcriptomic signature of HSCs in db/db mice, a well-known and widely used model for T2D. LSK cells of db/db mice enriched using a cell sorter were subjected to paired-end mRNA and single-end miRNA seq library and sequenced on Illumina NovaSeq 6000. The mRNA sequence reads were mapped using STAR (Spliced Transcripts Alignment to a Reference), and the miRNA sequence reads were mapped to the designated reference genome using the Qiagen GeneGlobe RNA-seq Analysis Portal with default parameters for miRNA.

RESULTS

We uncovered 2076 out of 13,708 mRNAs and 35 out of 191 miRNAs that were expressed significantly in db/db animals; strikingly, previously unreported miRNAs (miR-3968 and miR-1971) were found to be downregulated in db/db mice. Furthermore, we observed a molecular shift in the transcriptome of HSCs of diabetes with an increase in pro-inflammatory cytokines (Il4, Tlr4, and Tnf11α) and a decrease in anti-inflammatory cytokine IL10. Pathway mapping demonstrated inflammation mediated by chemokine, cytokine, and angiogenesis as one of the top pathways with a significantly higher number of transcripts in db/db mice. These molecular changes were reflected in an overt defect in LSK mobility in the bone marrow. miRNA downstream target analysis unveils several mRNAs targeting leukocyte migration, microglia activation, phagosome formation, and macrophage activation signaling as their primary pathways, suggesting a shift to an inflammatory phenotype.

CONCLUSION

Our findings highlight that chronic diabetes adversely alters HSCs' homeostasis at the transcriptional level, thus potentially contributing to the inflammatory phenotype of HSCs under long-term diabetes. We also believe that identifying HSCs-based biomarkers in miRNAs or mRNAs could serve as diagnostic markers and potential therapeutic targets for diabetes and associated vascular complications.

NF-κB pathway as a molecular target for curcumin in diabetes mellitus treatment: Focusing on oxidative stress and inflammation

Diabetes mellitus (DM) is a collection of metabolic disorder that is characterized by chronic hyperglycemia. Recent studies have demonstrated the crucial involvement of oxidative stress (OS) and inflammatory reactions in the development of DM. Curcumin (CUR), a natural compound derived from turmeric, exerts beneficial effects on diabetes mellitus through its interaction with the nuclear factor kappa B (NF-κB) pathway. Research indicates that CUR targets inflammatory mediators in diabetes, including tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6), by modulating the NF-κB signaling pathway. By reducing the expression of these inflammatory factors, CUR demonstrates protective effects in DM by improving pancreatic β-cells function, normalizing inflammatory cytokines, reducing OS and enhancing insulin sensitivity. The findings reveal that CUR administration effectively lowered blood glucose elevation, reinstated diminished serum insulin levels, and enhanced body weight in Streptozotocin -induced diabetic rats. CUR exerts its beneficial effects in management of diabetic complications through regulation of signaling pathways, such as calcium-calmodulin (CaM)-dependent protein kinase II (CaMKII), peroxisome proliferator-activated receptor gamma (PPAR-γ), NF-κB, and transforming growth factor β1 (TGFB1). Moreover, CUR reversed the heightened expression of inflammatory cytokines (TNF-α, Interleukin-1 beta (IL-1β), IL-6) and chemokines like MCP-1 in diabetic specimens, vindicating its anti-inflammatory potency in counteracting hyperglycemia-induced alterations. CUR diminishes OS, avert structural kidney damage linked to diabetic nephropathy, and suppress NF-κB activity. Furthermore, CUR exhibited a protective effect against diabetic cardiomyopathy, lung injury, and diabetic gastroparesis. Conclusively, the study posits that CUR could potentially offer therapeutic benefits in relieving diabetic complications through its influence on the NF-κB pathway.

YAP/TAZ Signaling Enhances Angiogenesis of Retinal Microvascular Endothelial Cells in a High-Glucose Environment

PURPOSE

Diabetic retinopathy (DR) is a major cause of irreversible blindness in the working-age population. Neovascularization is an important hallmark of advanced DR. There is evidence that Yes-associated protein (YAP)/transcriptional co-activator with a PDZ binding domain (TAZ) plays an important role in angiogenesis and that its activity is regulated by vascular endothelial growth factor (VEGF). Therefore, the aim of this study was to investigate the effect of YAP/TAZ-VEGF crosstalk on the angiogenic capacity of human retinal microvascular endothelial cells (hRECs) in a high-glucose environment.

METHODS

The expression of YAP and TAZ of hRECs under normal conditions, hypertonic conditions and high glucose were observed. YAP overexpression (OE-YAP), YAP silencing (sh-YAP), VEGF overexpression (OE-VEGF) and VEGF silencing (sh-VEGF) plasmids were constructed. Cell counting kit-8 assay was performed to detect cells proliferation ability, transwell assay to detect cells migration ability, and tube formation assay to detect tube formation ability. The protein expression of YAP, TAZ, VEGF, matrix metalloproteinase (MMP)-8, MMP-13, vessel endothelium (VE)-cadherin and alpha smooth muscle actin (α-SMA) was measured by western blot.

RESULTS

The proliferation of hRECs was significantly higher in the high glucose group compared with the normal group, as well as the protein expression of YAP and TAZ (p < 0.01). YAP and VEGF promoted the proliferation, migration and tube formation of hRECs in the high glucose environment (p < 0.01), and increased the expression of TAZ, VEGF, MMP-8, MMP-13 and α-SMA while reducing the expression of VE-cadherin (p < 0.01). Knockdown of YAP effectively reversed the above promoting effects of OE-VEGF (p < 0.01) and overexpression of YAP significantly reversed the inhibition effects of sh-VEGF on above cell function (p < 0.01).

CONCLUSION

In a high-glucose environment, YAP/TAZ can significantly promote the proliferation, migration and tube formation ability of hRECs, and the mechanism may be related to the regulation of VEGF expression.

Aging in Ocular Blood Vessels: Molecular Insights and the Role of Oxidative Stress

Acknowledged as a significant pathogenetic driver for numerous diseases, aging has become a focal point in addressing the profound changes associated with increasing human life expectancy, posing a critical concern for global public health. Emerging evidence suggests that factors influencing vascular aging extend their impact to choroidal and retinal blood vessels. The objective of this work is to provide a comprehensive overview of the impact of vascular aging on ocular blood vessels and related diseases. Additionally, this study aims to illuminate molecular insights contributing to vascular cell aging, with a particular emphasis on the choroid and retina. Moreover, innovative molecular targets operating within the domain of ocular vascular aging are presented and discussed.

Transcriptomic Profile of Lin - Sca1 + c-kit (LSK) cells in db/db mice with long-standing diabetes

The Lin - Sca1 + c-Kit + (LSK) fraction comprises multipotent hematopoietic stem cells (HSCs), vital to tissue homeostasis and vascular repair. While HSC homeostasis is impaired in diabetes, it is not known how chronic (>6 months) type 2 diabetes (T2D) alters the HSC transcriptome. Herein, we assessed the transcriptomic signature of HSCs in db/db mice employing mRNA and miRNA sequencing. We uncovered 2076 mRNAs and 35 miRNAs differentially expressed in db/db mice, including two novel miRNAs previously unreported in T2D. Further analysis of these transcripts showed a molecular shift with an increase in the pro-inflammatory cytokines and a decrease in anti-inflammatory cytokine expression. Also, pathway mapping unveiled inflammation and angiogenesis as one of the top pathways. These effects were reflected in bone marrow mobilopathy, retinal microglial inflammation, and neurovascular deficits in db/db mice. In conclusion, our study highlights that chronic diabetes alters HSCs' at the transcriptomic level, thus potentially contributing to overall homeostasis and neurovascular deficits of diabetes, such as diabetic retinopathy.

Highlights

Bone marrow mobilopathy with long-standing diabetesSwitch in LSK transcriptomic profile towards inflammation and angiogenesisDiscovered 35 miRNAs, including two novel miRNAs, miR-3968 and miR-1971LSK dysfunction reflected in inflammation and neurovascular deficits of the retina.

Relationship between Biochemical Pathways and Non-Coding RNAs Involved in the Progression of Diabetic Retinopathy

Diabetic retinopathy (DR) is a progressive blinding disease, which affects the vision and quality of life of patients, and it severely impacts the society. This complication, caused by abnormal glucose metabolism, leads to structural, functional, molecular, and biochemical abnormalities in the retina. Oxidative stress and inflammation also play pivotal roles in the pathogenic process of DR, leading to mitochondrial damage and a decrease in mitochondrial function. DR causes retinal degeneration in glial and neural cells, while the disappearance of pericytes in retinal blood vessels leads to alterations in vascular regulation and stability. Clinical changes include dilatation and blood flow changes in response to the decrease in retinal perfusion in retinal blood vessels, leading to vascular leakage, neovascularization, and neurodegeneration. The loss of vascular cells in the retina results in capillary occlusion and ischemia. Thus, DR is a highly complex disease with various biological factors, which contribute to its pathogenesis. The interplay between biochemical pathways and non-coding RNAs (ncRNAs) is essential for understanding the development and progression of DR. Abnormal expression of ncRNAs has been confirmed to promote the development of DR, suggesting that ncRNAs such as miRNAs, lncRNAs, and circRNAs have potential as diagnostic biomarkers and theranostic targets in DR. This review provides an overview of the interactions between abnormal biochemical pathways and dysregulated expression of ncRNAs under the influence of hyperglycemic environment in DR.

Cells in Atherosclerosis: Focus on Cellular Senescence from Basic Science to Clinical Practice

Aging is a major risk factor of atherosclerosis through different complex pathways including replicative cellular senescence and age-related clonal hematopoiesis. In addition to aging, extracellular stress factors, such as mechanical and oxidative stress, can induce cellular senescence, defined as premature cellular senescence. Senescent cells can accumulate within atherosclerotic plaques over time and contribute to plaque instability. This review summarizes the role of cellular senescence in the complex pathophysiology of atherosclerosis and highlights the most important senotherapeutics tested in cardiovascular studies targeting senescence. Continued bench-to-bedside research in cellular senescence might allow the future implementation of new effective anti-atherosclerotic preventive and treatment strategies in clinical practice.

Insights on the role of L-lactate as a signaling molecule in skin aging

L-lactate is a catabolite from the anaerobic metabolism of glucose, which plays a paramount role as a signaling molecule in various steps of the cell survival. Its activity, as a master tuner of many mechanisms underlying the aging process, for example in the skin, is still presumptive, however its crucial position in the complex cross-talk between mitochondria and the process of cell survival, should suggest that L-lactate may be not a simple waste product but a fine regulator of the aging/survival machinery, probably via mito-hormesis. Actually, emerging evidence is highlighting that ROS are crucial in the signaling of skin health, including mechanisms underlying wound repair, renewal and aging. The ROS, including superoxide anion, hydrogen peroxide, and nitric oxide, play both beneficial and detrimental roles depending upon their levels and cellular microenvironment. Physiological ROS levels are essential for cutaneous health and the wound repair process. Aberrant redox signaling activity drives chronic skin disease in elderly. On the contrary, impaired redox modulation, due to enhanced ROS generation and/or reduced levels of antioxidant defense, suppresses wound healing via promoting lymphatic/vascular endothelial cell apoptosis and death. This review tries to elucidate this issue.

Oxidative Stress and Its Regulation in Diabetic Retinopathy

Diabetic retinopathy is the retinal disease associated with hyperglycemia in patients who suffer from type 1 or type 2 diabetes. It includes maculopathy, involving the central retina and characterized by ischemia and/or edema, and peripheral retinopathy that progresses to a proliferative stage with neovascularization. Approximately 10% of the global population is estimated to suffer from diabetes, and around one in 5 of these individuals have diabetic retinopathy. One of the major effects of hyperglycemia is oxidative stress, the pathological state in which elevated production of reactive oxygen species damages tissues, cells, and macromolecules. The retina is relatively prone to oxidative stress due to its high metabolic activity. This review provides a summary of the role of oxidative stress in diabetic retinopathy, including a description of the retinal cell players and the molecular mechanisms. It discusses pathological processes, including the formation and effects of advanced glycation end-products, the impact of metabolic memory, and involvements of non-coding RNA. The opportunities for the therapeutic blockade of oxidative stress in diabetic retinopathy are also considered.

New Insights on Dietary Polyphenols for the Management of Oxidative Stress and Neuroinflammation in Diabetic Retinopathy

Diabetic retinopathy (DR) is a neurodegenerative and vascular pathology that is considered one of the leading causes of blindness worldwide, resulting from complications of advanced diabetes mellitus (DM). Current therapies consist of protocols aiming to alleviate the existing clinical signs associated with microvascular alterations limited to the advanced disease stages. In response to the low resolution and limitations of the DR treatment, there is an urgent need to develop more effective alternative therapies to optimize glycemic, vascular, and neuronal parameters, including the reduction in the cellular damage promoted by inflammation and oxidative stress. Recent evidence has shown that dietary polyphenols reduce oxidative and inflammatory parameters of various diseases by modulating multiple cell signaling pathways and gene expression, contributing to the improvement of several chronic diseases, including metabolic and neurodegenerative diseases. However, despite the growing evidence for the bioactivities of phenolic compounds, there is still a lack of data, especially from human studies, on the therapeutic potential of these substances. This review aims to comprehensively describe and clarify the effects of dietary phenolic compounds on the pathophysiological mechanisms involved in DR, especially those of oxidative and inflammatory nature, through evidence from experimental studies. Finally, the review highlights the potential of dietary phenolic compounds as a prophylactic and therapeutic strategy and the need for further clinical studies approaching the efficacy of these substances in DR management.

Senescent Cells: A Therapeutic Target in Cardiovascular Diseases

Senescent cell accumulation has been observed in age-associated diseases including cardiovascular diseases. Senescent cells lack proliferative capacity and secrete senescence-associated secretory phenotype (SASP) factors that may cause or worsen many cardiovascular diseases. Therapies targeting senescent cells, especially senolytic drugs that selectively induce senescent cell removal, have been shown to delay, prevent, alleviate, or treat multiple age-associated diseases in preclinical models. Some senolytic clinical trials have already been completed or are underway for a number of diseases and geriatric syndromes. Understanding how cellular senescence affects the various cell types in the cardiovascular system, such as endothelial cells, vascular smooth muscle cells, fibroblasts, immune cells, progenitor cells, and cardiomyocytes, is important to facilitate translation of senotherapeutics into clinical interventions. This review highlights: (1) the characteristics of senescent cells and their involvement in cardiovascular diseases, focusing on the aforementioned cardiovascular cell types, (2) evidence about senolytic drugs and other senotherapeutics, and (3) the future path and clinical potential of senotherapeutics for cardiovascular diseases.

Early Detection Is the Best Prevention-Characterization of Oxidative Stress in Diabetes Mellitus and Its Consequences on the Cardiovascular System

Previous studies demonstrated an important role of oxidative stress in the pathogenesis of cardiovascular disease (CVD) in diabetic patients due to hyperglycemia. CVD remains the leading cause of premature death in the western world. Therefore, diabetes mellitus-associated oxidative stress and subsequent inflammation should be recognized at the earliest possible stage to start with the appropriate treatment before the onset of the cardiovascular sequelae such as arterial hypertension or coronary artery disease (CAD). The pathophysiology comprises increased reactive oxygen and nitrogen species (RONS) production by enzymatic and non-enzymatic sources, e.g., mitochondria, an uncoupled nitric oxide synthase, xanthine oxidase, and the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX). Considering that RONS originate from different cellular mechanisms in separate cellular compartments, adequate, sensitive, and compartment-specific methods for their quantification are crucial for early detection. In this review, we provide an overview of these methods with important information for early, appropriate, and effective treatment of these patients and their cardiovascular sequelae.

Antioxidant Phytochemicals as Potential Therapy for Diabetic Complications

The global prevalence of diabetes continues to increase partly due to rapid urbanization and an increase in the aging population. Consequently, this is associated with a parallel increase in the prevalence of diabetic vascular complications which significantly worsen the burden of diabetes. For these diabetic vascular complications, there is still an unmet need for safe and effective alternative/adjuvant therapeutic interventions. There is also an increasing urge for therapeutic options to come from natural products such as plants. Hyperglycemia-induced oxidative stress is central to the development of diabetes and diabetic complications. Furthermore, oxidative stress-induced inflammation and insulin resistance are central to endothelial damage and the progression of diabetic complications. Human and animal studies have shown that polyphenols could reduce oxidative stress, hyperglycemia, and prevent diabetic complications including diabetic retinopathy, diabetic nephropathy, and diabetic peripheral neuropathy. Part of the therapeutic effects of polyphenols is attributed to their modulatory effect on endogenous antioxidant systems. This review attempts to summarize the established effects of polyphenols on endogenous antioxidant systems from the literature. Moreover, potential therapeutic strategies for harnessing the potential benefits of polyphenols for diabetic vascular complications are also discussed.

Mechanisms and consequences of endothelial cell senescence

Endothelial cells are located at the crucial interface between circulating blood and semi-solid tissues and have many important roles in maintaining systemic physiological function. The vascular endothelium is particularly susceptible to pathogenic stimuli that activate tumour suppressor pathways leading to cellular senescence. We now understand that senescent endothelial cells are highly active, secretory and pro-inflammatory, and have an aberrant morphological phenotype. Moreover, endothelial senescence has been identified as an important contributor to various cardiovascular and metabolic diseases. In this Review, we discuss the consequences of endothelial cell exposure to damaging stimuli (haemodynamic forces and circulating and endothelial-derived factors) and the cellular and molecular mechanisms that induce endothelial cell senescence. We also discuss how endothelial cell senescence causes arterial dysfunction and contributes to clinical cardiovascular diseases and metabolic disorders. Finally, we summarize the latest evidence on the effect of eliminating senescent endothelial cells (senolysis) and identify important remaining questions to be addressed in future studies.

Noninvasive Delivery of Self-Regenerating Cerium Oxide Nanoparticles to Modulate Oxidative Stress in the Retina

Diseases affecting the retina, such as age-related macular degeneration (AMD), diabetic retinopathy, macular edema, and retinal vein occlusions, are currently treated by the intravitreal injection of drug formulations. These disease pathologies are driven by oxidative damage due to chronic high concentrations of reactive oxygen species (ROS) in the retina. Intravitreal injections often induce retinal detachment, intraocular hemorrhage, and endophthalmitis. Furthermore, the severe eye pain associated with these injections lead to patient noncompliance and treatment discontinuation. Hence, there is a critical need for the development of a noninvasive therapy that is effective for a prolonged period for treating retinal diseases. In this study, we developed a noninvasive cerium oxide nanoparticle (CNP) delivery wafer (Cerawafer) for the modulation of ROS in the retina. We fabricated Cerawafer loaded with CNP and determined its SOD-like enzyme-mimetic activity and ability to neutralize ROS generated in vitro. We demonstrated Cerawafer's ability to deliver CNP in a noninvasive fashion to the retina in healthy mouse eyes and the CNP retention in the retina for more than a week. Our studies have demonstrated the in vivo efficacy of the Cerawafer to modulate ROS and associated down-regulation of VEGF expression in the retinas of very-low-density lipoprotein receptor knockout (vldlr-/-) mouse model. The development of a Cerawafer nanotherapeutic will fulfill a hitherto unmet need. Currently, there is no such therapeutic available, and the development of a Cerawafer nanotherapeutic will be a major advancement in the treatment of retinal diseases.

Histone modification of endothelial-mesenchymal transition in cardiovascular diseases

Endothelial-mesenchymal transition (EndMT) is a differentiation process in which endothelial cells lose their own characteristics and acquire mesenchymal-like characteristics, which contributes to the formation and development of atherosclerotic plaques. Until now, there is still a lack of effective measures to treat atherosclerosis (AS), so there is an urgent need to understand the underlying mechanisms of AS. In addition, although various studies have shown that EndMT is involved in the pathological stages of cardiovascular diseases, such as myocardial fibrosis, myocardial hypertrophy, and hypertension, the specific molecular mechanisms driving EndMT are still in the exploratory stage. In this review, we review the role of histone modifications (methylation, demethylation and acetylation, deacetylation) on EndMT in cardiovascular disease, aiming to target histone-modifying enzymes to guide cardiovascular disease therapy.

Implications of cancer stem cells in diabetes and pancreatic cancer

This review provides a detailed study of pancreatic cancer (PC) and the implication of different types of cancers concerning diabetes. The combination of anti-diabetic drugs with other anti-cancer drugs and phytochemicals can help prevent and treat this disease. PC cancer stem cells (CSCs) and how they migrate and develop into malignant tumors are discussed. A detailed explanation of the different mechanisms of diabetes development, which can enhance the pancreatic CSCs' proliferation by increasing the IGF factor levels, epigenetic modifications, DNA damage, and the influence of lifestyle factors like obesity, and inflammation, has been discussed. It also explains how cancer due to diabetes is associated with high mortality rates. One of the well-known diabetic drugs, metformin, can be combined with other anti-cancer drugs and prevent the development of PC and has been taken as one of the prime focus in this review. Overall, this paper provides insight into the relationship between diabetes and PC and the methods that can be employed to diagnose this disease at an earlier stage successfully.

Pathological Roles of Oxidative Stress in Cardiac Microvascular Injury

Cardiac microvascular injury can be a fundamental pathological process that causes high incidence cardiovascular diseases such heart failure, diabetic cardiomyopathy, and hypertension. It is also an independent risk factor for cardiovascular disease. Oxidative stress is a significant pathological process in which the body interferes with the balance of the endogenous antioxidant defense system by producing reactive oxygen species, leading to property changes and dysfunction. It has been demonstrated that oxidative stress is one of the major causes of cardiac microvascular disease. Therefore, additional investigation into the relationship between oxidative stress and cardiac microvascular injury will direct clinical management in the future. In order to give suggestions and support for future in-depth studies, we give a basic overview of the cardiac microvasculature in relation to physiopathology in this review. We also summarize the role of oxidative stress of mitochondrial and non-mitochondrial origin in cardiac microvascular injury and related drug studies.

Long term high glucose exposure induces premature senescence in retinal endothelial cells

Purpose: Features of cellular senescence have been described in diabetic retinal vasculature. The aim of this study was to investigate how the high glucose microenvironment impacts on the senescence program of retinal endothelial cells. Methods: Human retinal microvascular endothelial cells were cultured under control and high glucose conditions of 5 mM and 25 mM D-glucose, respectively. Isomeric l-glucose was used as the osmotic control. Cells were counted using CASY technology until they reached their Hayflick limit. Senescence-associated β-Galactosidase was used to identify senescent cells. Endothelial cell functionality was evaluated by the clonogenic, 3D tube formation, and barrier formation assays. Cell metabolism was characterized using the Seahorse Bioanalyzer. Gene expression analysis was performed by bulk RNA sequencing. Retinal tissues from db/db and db/+ mice were evaluated for the presence of senescent cells. Publicly available scRNA-sequencing data for retinas from Akimba and control mice was used for gene set enrichment analysis. Results: Long term exposure to 25 mM D-Glucose accelerated the establishment of cellular senescence in human retinal endothelial cells when compared to 5 mM D-glucose and osmotic controls. This was shown from 4 weeks, by a significant slower growth, higher percentages of cells positive for senescence-associated β-galactosidase, an increase in cell size, and lower expression of pRb and HMGB2. These senescence features were associated with decreased clonogenic capacity, diminished tubulogenicity, and impaired barrier function. Long term high glucose-cultured cells exhibited diminished glycolysis, with lower protein expression of GLUT1, GLUT3, and PFKFB3. Transcriptomic analysis, after 4 weeks of culture, identified downregulation of ALDOC, PFKL, and TPI1, in cells cultured with 25 mM D-glucose when compared to controls. The retina from db/db mice showed a significant increase in acellular capillaries associated with a significant decrease in vascular density in the intermediate and deep retinal plexuses, when compared to db/+ mice. Senescent endothelial cells within the db/db retinal vasculature were identified by senescence-associated β-galactosidase staining. Analysis of single cell transcriptomics data for the Akimba mouse retina highlighted an enrichment of senescence and senescence-associated secretory phenotype gene signatures when compared to control mice. Conclusion: A diabetic-like microenvironment of 25 mM D-glucose was sufficient to accelerate the establishment of cellular senescence in human retinal microvascular endothelial cells.

SIRT3 attenuates coronary atherosclerosis in diabetic patients by regulating endothelial cell function

Background

This study aimed to explore the relationship between the Sirtuin 3 (SIRT3) gene and endothelial cell dysfunction, contributing to the progression of coronary atherosclerosis driven by hyperglycemia.

Methods

We measured serum SIRT3 levels using enzyme‐linked immunosorbent assay in 95 patients with type 2 diabetes mellitus (T2DM) who underwent diagnostic coronary angiography. The patients were divided into two groups according to the presence (n = 45) or absence (n = 50) of coronary artery disease (CAD). Human aortic endothelial cells (HAECs) grown in vitro in a medium with various concentrations of glucose (5.5, 11, 16.5, 22, 27.5, 33, and 38.5 mM) for 24 h were assessed for protein expression of SIRT3, peroxisome proliferator‐activated receptor alpha (PPAR‐α), endothelial nitric oxide (NO) synthase (eNOS), and inducible NO synthase (iNOS) using Western blot analysis. HAECs were subjected to SIRT3 overexpression or inhibition through SIRT3 adenovirus and siRNA transfection.

Results

Serum SIRT3 levels were significantly lower in T2DM patients with CAD than in those without CAD (p = 0.048). The in vitro results showed that HG significantly increased SIRT3, PPAR‐α, and eNOS protein expression in a concentration‐dependent manner. Moreover, iNOS expression was decreased in HAECs in response to HG. Reduced PPAR‐α and eNOS levels and increased iNOS levels were observed in SIRT3 silenced HAECs cells. In contrast, SIRT3 overexpression significantly improved PPAR‐α and eNOS expression and suppressed iNOS expression.

Conclusion

SIRT3 was associated with the progression of atherosclerosis in T2DM patients through upregulation of PPAR‐α and eNOS and downregulation of iNOS, which are involved in endothelial dysfunction under hyperglycemic conditions.

A Comprehensive Overview of the Complex Role of Oxidative Stress in Aging, The Contributing Environmental Stressors and Emerging Antioxidant Therapeutic Interventions

Introduction

Aging is a normal, inevitable, irreversible, and progressive process which is driven by internal and external factors. Oxidative stress, that is the imbalance between prooxidant and antioxidant molecules favoring the first, plays a key role in the pathophysiology of aging and comprises one of the molecular mechanisms underlying age-related diseases. However, the oxidative stress theory of aging has not been successfully proven in all animal models studying lifespan, meaning that altering oxidative stress/antioxidant defense systems did not always lead to a prolonged lifespan, as expected. On the other hand, animal models of age-related pathological phenotypes showed a well-correlated relationship with the levels of prooxidant molecules. Therefore, it seems that oxidative stress plays a more complicated role than the one once believed and this role might be affected by the environment of each organism. Environmental factors such as UV radiation, air pollution, and an unbalanced diet, have also been implicated in the pathophysiology of aging and seem to initiate this process more rapidly and even at younger ages.

Aim

The purpose of this review is to elucidate the role of oxidative stress in the physiology of aging and the effect of certain environmental factors in initiating and sustaining this process. Understanding the pathophysiology of aging will contribute to the development of strategies to postpone this phenomenon. In addition, recent studies investigating ways to alter the antioxidant defense mechanisms in order to prevent aging will be presented.

Conclusions

Careful exposure to harmful environmental factors and the use of antioxidant supplements could potentially affect the biological processes driving aging and slow down the development of age-related diseases. Maybe a prolonged lifespan could not be achieved by this strategy alone, but a longer healthspan could also be a favorable target.

Intermittent Fasting to the Eye: A New Dimension Involved in Physiological and Pathological Changes

Intermittent fasting (IF) is gaining popularity as a therapeutic dietary strategy that regulates metabolism and can alter the development of metabolic disorders. An increasing amount of research has connected ocular diseases to IF and discovered that it has a direct and indirect effect on the eye’s physiological structure and pathological alterations. This article summarizes the progress of research on IF in regulating the physiological structures of the ocular vasculature, the anterior segment of the eye, the retina, and the choroid. We explored the therapeutic potential of IF for various common ocular diseases. In the future, a comprehensive study into the fundamental processes of IF will provide a direct and rigorous approach to eye disease prevention and therapy.

Exogenous melatonin prevents type 1 diabetes mellitus-induced bone loss, probably by inhibiting senescence

Exogenous melatonin inhibited the senescence of preosteoblast cells in type 1 diabetic (T1D) mice and those cultured in high glucose (HG) by multiple regulations. Exogenous melatonin had a protective effect on diabetic osteoporosis, which may depend on the inhibition of senescence.

INTRODUCTION

Senescence is thought to play an important role in the pathophysiological mechanisms underlying diabetic bone loss. Increasing evidence has shown that melatonin exerts anti-senescence effects. In this study, we investigated whether melatonin can inhibit senescence and prevent diabetic bone loss.

METHODS

C57BL/6 mice received a single intraperitoneal injection of 160 mg/kg streptozotocin, followed by the oral administration of melatonin or vehicle for 2 months. Then, tissues were harvested and subsequently examined. MC3T3-E1 cells were cultured under HG conditions for 7 days and then treated with melatonin or not for 24 h. Sirt1-specific siRNAs and MT1- or MT2-specific shRNA plasmids were transfected into MC3T3-E1 cells for mechanistic study.

RESULTS

The total protein extracted from mouse femurs revealed that melatonin prevented senescence in T1D mice. The micro-CT results indicated that melatonin prevented bone loss in T1D mice. Cellular experiments indicated that melatonin administration prevented HG-induced senescence, whereas knockdown of the melatonin receptors MT1 or MT2 abolished these effects. Sirt1 expression was upregulated by melatonin administration but significantly reduced after MT1 or MT2 was knocked down. Knockdown of Sirt1 blocked the anti-senescence effects of melatonin. Additionally, melatonin promoted the expression of CDK2, CDK4, and CyclinD1, while knockdown of MT1 or MT2 abolished these effects. Furthermore, melatonin increased the expression of the polycomb repressive complex (PRC), but knockdown of MT1 or MT2 abolished these effects. Furthermore, melatonin increased the protein levels of Sirt1, PRC1/2 complex-, and cell cycle-related proteins.

CONCLUSION

This work shows that melatonin protects against T1D-induced bone loss, probably by inhibiting senescence. Targeting senescence in the investigation of diabetic osteoporosis may lead to novel discoveries.

Role of Cellular Senescence in Type II Diabetes

Cellular senescence is a cell fate that occurs in response to numerous types of stress and can promote tissue repair or drive inflammation and disruption of tissue homeostasis depending on the context. Aging and obesity lead to an increase in the senescent cell burden in multiple organs. Senescent cells release a myriad of senescence-associated secretory phenotype factors that directly mediate pancreatic β-cell dysfunction, adipose tissue dysfunction, and insulin resistance in peripheral tissues, which promote the onset of type II diabetes mellitus. In addition, hyperglycemia and metabolic changes seen in diabetes promote cellular senescence. Diabetes-induced cellular senescence contributes to various diabetic complications. Thus, type II diabetes is both a cause and consequence of cellular senescence. This review summarizes recent studies on the link between aging, obesity, and diabetes, focusing on the role of cellular senescence in disease processes.

Ultra-processed diet, systemic oxidative stress, and breach of immunologic tolerance

In recent years, consumption of ultra-processed food around the world has been increasing. The nutritional profile of an ultra-processed diet is associated with the development of cellular alterations that lead to oxidative stress. The chronic prooxidative state leads to an environment that influences the proliferation, apoptosis, and signaling pathways of immune cells. Likewise, the decrease in the transcription factor NRF2, owing to exacerbated production of reactive oxygen species, leads to changes in immune function and response to infections. This review aims to analyze the connection between an ultra-processed diet, systemic oxidative stress, and immune tolerance, as a contribution to the scientific evidence on the impact of oxidative stress on health and the possible risk of infections-an important consideration in the association of eating pattern and the immune response.

Sulodexide reduces glucose induced senescence in human retinal endothelial cells

Chronic exposure of retinal endothelium cells to hyperglycemia is the leading cause of diabetic retinopathy. We evaluated the effect of high glucose concentration on senescence in human retinal endothelial cells (HREC) and modulation of that effect by Sulodexide. Experiments were performed on HREC undergoing in vitro replicative senescence in standard medium or medium supplemented with glucose 20 mmol/L (GLU) or mannitol 20 mnol/L (MAN). Effect of Sulodexide 0.5 LRU/mL (SUL) on the process of HREC senescence was studied. Glucose 20 mmol/L accelerates senescence of HREC: population doubling time (+ 58%, p < 0.001) β-galactosidase activity (+ 60%, p < 0.002) intracellular oxidative stress (+ 65%, p < 0.01), expression of p53 gene (+ 118%, p < 0.001). Senescent HREC had also reduced transendothelial electrical resistance (TEER) (- 30%, p < 0.001). Mannitol 20 mmol/L used in the same scenario as glucose did not induce HREC senescence. In HREC exposed to GLU and SUL, the senescent changes were smaller. HREC, which became senescent in the presence of GLU, demonstrated higher expression of genes regulating the synthesis of Il6 and VEGF-A, which was reflected by increased secretion of these cytokines (IL6 + 125%, p < 0.001 vs control and VEGF-A + 124% p < 0.001 vs control). These effects were smaller in the presence of SUL, and additionally, an increase of TEER in the senescent HREC was observed. Chronic exposure of HREC to high glucose concentration in medium accelerates their senescence, and that process is reduced when the cells are simultaneously exposed to Sulodexide. Additionally, Sulodexide decreases the secretion of IL6 and VEGF-A from senescent HREC and increases their TEER.

Chrysin's Impact on Oxidative and Inflammation Damages in the Liver of Aged Male Rats

AIM

The purpose of this research was to investigate the effect of chrysin on one of the natural antioxidants on aging progression in an animal model.

BACKGROUND

Oxidative stress and inflammation increase in hepatic tissue during aging, leading to liver dysfunction.

OBJECTIVE

The current research was conducted to show the effect of chrysin on the activities of antioxidant enzyme (catalase, glutathione peroxidase, and superoxide dismutase), serum nitric oxide (NO), and lipid peroxidation as well as inflammatory cytokines (TNF-α, IL-6, and IL-1β) of aging rats.

METHODS

Male Wistar rats of different ages, 2, 10, and 20 months, were randomly divided into six groups as follows (n=8, per each group): young control rats (C2), young CH-treated rats (CH2), middle- aged control rats (C10), middle-aged CH-treated group (CH10), aged control group (C20), and aged CH-treated group (CH20). Chrysin (20 mg/kg) was administered intraperitoneally once a day for 30 days.

RESULT

Present findings indicated that chrysin treatment ameliorated the increased liver levels of lipid peroxidation, TNF-α, and IL-1β as well as serum levels of NO.

CONCLUSION

The findings suggest that chrysin could be effective against the progression of ageinduced damage by modulation of oxidant-antioxidant system and inflammatory response.

High Glucose Treatment Limits Drosha Protein Expression and Alters AngiomiR Maturation in Microvascular Primary Endothelial Cells via an Mdm2-dependent Mechanism

Diabetes promotes an angiostatic phenotype in the microvascular endothelium of skeletal muscle and skin. Angiogenesis-related microRNAs (angiomiRs) regulate angiogenesis through the translational repression of pro- and anti-angiogenic genes. The maturation of micro-RNA (miRs), including angiomiRs, requires the action of DROSHA and DICER proteins. While hyperglycemia modifies the expression of angiomiRs, it is unknown whether high glucose conditions alter the maturation process of angiomiRs in dermal and skeletal muscle microvascular endothelial cells (MECs). Compared to 5 mM of glucose, high glucose condition (30 mM, 6-24 h) decreased DROSHA protein expression, without changing DROSHA mRNA, DICER mRNA, or DICER protein in primary dermal MECs. Despite DROSHA decreasing, high glucose enhanced the maturation and expression of one angiomiR, miR-15a, and downregulated an miR-15a target: Vascular Endothelial Growth Factor-A (VEGF-A). The high glucose condition increased Murine Double Minute-2 (MDM2) expression and MDM2-binding to DROSHA. Inhibition of MDM2 prevented the effects evoked by high glucose on DROSHA protein and miR-15a maturation in dermal MECs. In db/db mice, blood glucose was negatively correlated with the expression of skeletal muscle DROSHA protein, and high glucose decreased DROSHA protein in skeletal muscle MECs. Altogether, our results suggest that high glucose reduces DROSHA protein and enhances the maturation of the angiostatic miR-15a through a mechanism that requires MDM2 activity.

The Long Non-Coding RNA HOTAIR Is a Critical Epigenetic Mediator of Angiogenesis in Diabetic Retinopathy

Purpose

Diabetic retinopathy (DR) remains a pressing issue worldwide. Abnormal angiogenesis is a distinct vascular lesion in DR, and research has established that vascular endothelial growth factor A (VEGF-A) is a primary mediator of such changes. However, limitations in current anti-VEGF therapies suggest that our understanding of molecular networks underlying ocular angiogenesis remains far from complete. Based on our long non-coding RNA (lncRNA) array analyses, HOX antisense intergenic RNA (HOTAIR) was identified as one of the top upregulated lncRNAs in high glucose-cultured human retinal endothelial cells (HRECs). Given the well-documented roles of HOTAIR in cancer, no studies have examined the epigenetic implications of HOTAIR in DR, and we investigated such relationships herein.

Methods

We used HRECs exposed to various glucose concentrations and epigenetic modulators to examine HOTAIR, angiogenic, and DR-related molecular markers. Oxidative stress, angiogenesis, and mitochondrial dysfunction were assessed. Retinal tissues of diabetic rodents and the vitreous humor and serum of patients with proliferative DR were also investigated.

Results

Hyperglycemia significantly augmented HOTAIR expression in HRECs and promoted angiogenesis, oxidative damage, and mitochondrial aberrations. Similarly, vitreous humor and serum from proliferative DR patients and retinas from diabetic animals demonstrated increased HOTAIR expression compared to non-diabetic controls. HOTAIR knockdown protected against glucose-induced increases of angiogenic and diabetes-associated molecules in the retina. Mechanistically, we showed that HOTAIR exerts its capabilities by preventing oxidative stress and modulating epigenetic pathways involving histone methylation, histone acetylation, DNA methylation, and transcription factors.

Conclusions

Our findings suggest that HOTAIR is a critical lncRNA in the pathogenesis of DR and may potentially be important for diagnostic and therapeutic targeting.

Improving protection effects of eucalyptol via carboxymethyl chitosan-coated lipid nanoparticles on hyperglycaemia-induced vascular endothelial injury in rats

Hyperglycaemia is responsible for the major pathophysiological factor of diabetes-associated vascular endothelial injury, which mainly resulted from the disturbance of equilibrium between ROS generation and elimination. Eucalyptol was verified with exact anti-oxidation effects via stimulating the secretion of endogenous antioxidant enzymes against ROS. However, the volatility, instability and poor water solubility of eucalyptol limited its pharmacological activities in vivo. In this study, we developed carboxymethyl chitosan-coated lipid nanoparticles for eucalyptol (CMC/ELN) to facilitate oral administration. A thin lipid film dispersion method was used to prepare the ELN. After CMC coating, the diameter of ELN increased from 166 nm to 177 nm and charge reversal was observed. The nanocarrier enhanced the protective effects of eucalyptol both in the high level of glucose (HG)-damaged HUVECs and endothelial injury in type I diabetes mellitus (T₁DM) rat model. Furthermore, the mechanism of eucalyptol on the promotion of Nrf2 and HO-1 and reduction on Keap1 expression have been verified both in the in vitro and in vivo model. Besides, the pharmacokinetics data were verified the promotion of the oral eucalyptol absorption by the nanocarrier. Taken together, we established an optimal oral delivery system that promoted oral administration of eucalyptol to exert protective effects on hyperglycaemia-induced vascular endothelial injury.

Ephrin B2 mediates high glucose induced endothelial-to-mesenchymal transition in human aortic endothelial cells

Background

Previous study revealed that high glucose (HG) induced endothelial cell (EC) damage via endothelial-to-mesenchymal transition (EndMT). Recent studies suggested the role of Ephrin B2 in mediate ECs damage. However, the underlying mechanism remains unclear. The aim of the present study was to investigate whether Ephrin B2 mediates HG-induced EndMT in human aortic ECs (HAECs) and to determine the possible downstream signaling effector.

Methods

Primary HAECs were exposed to normal glucose (NG, 5.5 mM), HG (30 mM) and HG+Ephrin B2 small interfering RNA (siRNA), respectively. The pathological changes were investigated by light microscope and confocal microscopy. To study the effects of focal adhesion kinase (FAK) activation on Ephrin B2 in HAECs, cells were incubated with FAK siRNA in HG group. The expression of EndMT-related markers (CD31 and FSP1), Ephrin B2 and FAK were detected by qRT-PCR and western blot.

Results

The results showed that HG significantly inhibited the expression of CD31 and increased FSP1 compared with NG group. Moreover, Ephrin B2 was increased after HG incubation. Ephrin B2 siRNA attenuated HG-induced expression of EndMT-related markers. Furthermore, HG increased the expression of FAK and phosphorylated FAK (pho-FAK) in HAECs. In contrast, blocking Ephrin B2 could partially attenuate HG-induced FAK activation. And FAK siRNA further inhibited the EndMT-related markers in HAECs treated with HG.

Conclusions

HG-induced EndMT in HAECs might be partially mediated by Ephrin B2 and the downstream FAK pathway.

Oxidative Stress and Vascular Dysfunction in the Retina: Therapeutic Strategies

Many retinal diseases, such as diabetic retinopathy, glaucoma, and age-related macular (AMD) degeneration, are associated with elevated reactive oxygen species (ROS) levels. ROS are important intracellular signaling molecules that regulate numerous physiological actions, including vascular reactivity and neuron function. However, excessive ROS formation has been linked to vascular endothelial dysfunction, neuron degeneration, and inflammation in the retina. ROS can directly modify cellular molecules and impair their function. Moreover, ROS can stimulate the production of inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) causing inflammation and cell death. However, there are various compounds with direct or indirect antioxidant activity that have been used to reduce ROS accumulation in animal models and humans. In this review, we report on the physiological and pathophysiological role of ROS in the retina with a special focus on the vascular system. Moreover, we present therapeutic approaches for individual retinal diseases targeting retinal signaling pathways involving ROS.

Genome-Protecting Compounds as Potential Geroprotectors

Throughout life, organisms are exposed to various exogenous and endogenous factors that cause DNA damages and somatic mutations provoking genomic instability. At a young age, compensatory mechanisms of genome protection are activated to prevent phenotypic and functional changes. However, the increasing stress and age-related deterioration in the functioning of these mechanisms result in damage accumulation, overcoming the functional threshold. This leads to aging and the development of age-related diseases. There are several ways to counteract these changes: 1) prevention of DNA damage through stimulation of antioxidant and detoxification systems, as well as transition metal chelation; 2) regulation of DNA methylation, chromatin structure, non-coding RNA activity and prevention of nuclear architecture alterations; 3) improving DNA damage response and repair; 4) selective removal of damaged non-functional and senescent cells. In the article, we have reviewed data about the effects of various trace elements, vitamins, polyphenols, terpenes, and other phytochemicals, as well as a number of synthetic pharmacological substances in these ways. Most of the compounds demonstrate the geroprotective potential and increase the lifespan in model organisms. However, their genome-protecting effects are non-selective and often are conditioned by hormesis. Consequently, the development of selective drugs targeting genome protection is an advanced direction.

Glucose-induced, duration-dependent genome-wide DNA methylation changes in human endothelial cells

DNA methylation, a critical epigenetic mechanism, plays an important role in governing gene expressions during biological processes such as aging, which is well known to be accelerated in hyperglycemia (diabetes). In the present study, we investigated the effects of glucose on whole genome DNA methylation in small [human retinal microvascular endothelial cells (HRECs)] and large [human umbilical vein endothelial cells (HUVECs)] vessel endothelial cell (EC) lines exposed to basal or high glucose-containing media for variable lengths of time. Using the Infinium EPIC array, we obtained 773,133 CpG sites (probes) for analysis. Unsupervised clustering of the top 5% probes identified four distinct clusters within EC groups, with significant methylation differences attributed to EC types and the duration of cell culture rather than glucose stimuli alone. When comparing the ECs incubated for 2 days versus 7 days, hierarchical clustering analyses [methylation change >10% and false discovery rate (FDR) <0.05] identified 17,354 and 128 differentially methylated CpGs for HUVECs and HRECs, respectively. Predominant DNA hypermethylation was associated with the length of culture and was enriched for gene enhancer elements and regions surrounding CpG shores and shelves. We identified 88 differentially methylated regions (DMRs) for HUVECs and 8 DMRs for HRECs (all FDR <0.05). Pathway enrichment analyses of DMRs highlighted involvement of regulators of embryonic development (i.e., HOX genes) and cellular differentiation [transforming growth factor-β (TGF-β) family members]. Collectively, our findings suggest that DNA methylation is a complex process that involves tightly coordinated, cell-specific mechanisms. Such changes in methylation overlap genes critical for cellular differentiation and embryonic development.