Time-dependent replicative senescence vs. disturbed flow-induced pre-mature aging in atherosclerosis

Endothelial-specific telomerase inactivation causes telomere-independent cell senescence and multi-organ dysfunction characteristic of aging

It has remained unclear how aging of endothelial cells (EC) contributes to pathophysiology of individual organs. Cell senescence results in part from inactivation of telomerase (TERT). Here, we analyzed mice with Tert knockout specifically in EC. Tert loss in EC induced transcriptional changes indicative of senescence and tissue hypoxia in EC and in other cells. We demonstrate that EC-Tert-KO mice have leaky blood vessels. The blood-brain barrier of EC-Tert-KO mice is compromised, and their cognitive function is impaired. EC-Tert-KO mice display reduced muscle endurance and decreased expression of enzymes responsible for oxidative metabolism. Our data indicate that Tert-KO EC have reduced mitochondrial content and function, which results in increased dependence on glycolysis. Consistent with this, EC-Tert-KO mice have metabolism changes indicative of increased glucose utilization. In EC-Tert-KO mice, expedited telomere attrition is observed for EC of adipose tissue (AT), while brain and skeletal muscle EC have normal telomere length but still display features of senescence. Our data indicate that the loss of Tert causes EC senescence in part through a telomere length-independent mechanism undermining mitochondrial function. We conclude that EC-Tert-KO mice is a model of expedited vascular senescence recapitulating the hallmarks aging, which can be useful for developing revitalization therapies.

Role of NLRP3 in Parkinson's disease: Specific activation especially in dopaminergic neurons

Parkinson's disease (PD) is a neurodegenerative disorder with motor symptoms like bradykinesia, tremors, and balance issues. The pathology is recognized by progressively degenerative nigrostriatal dopaminergic neurons (DANs) loss. Its exact pathogenesis is unclear. Numerous studies have shown that nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) contributes to the pathogenesis of PD. Previous studies have demonstrated that the over-activation of NLRP3 inflammasome in microglia indirectly leads to the loss of DANs, which can worsen PD. In recent years, autopsy analyses of PD patients and studies in PD models have revealed upregulation of NLRP3 expression within DANs and demonstrated that activation of NLRP3 inflammasome in neurons is sufficient to drive neuronal loss, whereas microglial activation occurs after neuronal death, and that inhibition of intraneuronal NLRP3 inflammasome prevents degeneration of DANs. In this review, we provide research evidence related to NLRP3 inflammasome in DANs in PD as well as focus on possible mechanisms of NLRP3 inflammasome activation in neurons, aiming to provide a new way of thinking about the pathogenesis and prevention of PD.

Microphysiological systems for human aging research

Recent advances in microphysiological systems (MPS), also known as organs-on-a-chip (OoC), enable the recapitulation of more complex organ and tissue functions on a smaller scale in vitro. MPS therefore provide the potential to better understand human diseases and physiology. To date, numerous MPS platforms have been developed for various tissues and organs, including the heart, liver, kidney, blood vessels, muscle, and adipose tissue. However, only a few studies have explored using MPS platforms to unravel the effects of aging on human physiology and the pathogenesis of age-related diseases. Age is one of the risk factors for many diseases, and enormous interest has been devoted to aging research. As such, a human MPS aging model could provide a more predictive tool to understand the molecular and cellular mechanisms underlying human aging and age-related diseases. These models can also be used to evaluate preclinical drugs for age-related diseases and translate them into clinical settings. Here, we provide a review on the application of MPS in aging research. First, we offer an overview of the molecular, cellular, and physiological changes with age in several tissues or organs. Next, we discuss previous aging models and the current state of MPS for studying human aging and age-related conditions. Lastly, we address the limitations of current MPS and present future directions on the potential of MPS platforms for human aging research.

Cardiovascular events after cancer immunotherapy as oncologic emergencies: Analyses of 610 head and neck cancer patients treated with immune checkpoint inhibitors

BACKGROUND

Cardio-oncology and emergency medicine are closely collaborative, as many cardiac events in cancer patients require evaluation and treatment in the emergency department (ED). Immune checkpoint inhibitors (ICIs) have become a common treatment for patients with head and neck cancer (HNC). However, the immune-related adverse events (irAEs) from ICIs can be clinically significant.

METHODS

We reviewed and analyzed cardiovascular diagnoses among HNC patients who received ICI during the period April 1, 2016-December 31, 2020 in a large tertiary cancer center. Demographics, clinical and cancer-related data were abstracted, and billing databases were queried for cardiovascular disease (CVD)-related diagnosis using International Classification of Disease-version10 (ICD-10) codes. We recorded receipt of care at the ED as one of the outcome variables.

RESULTS

A total of 610 HNC patients with a median follow-up time of 12.3 months (median, interquartile range = 5-30 months) comprised our study cohort. Overall, 25.7% of patients had pre-existing CVD prior to ICI treatment. Of the remaining 453 patients without pre-existing CVD, 31.5% (n = 143) had at least one CVD-related diagnosis after ICI initiation. Tachyarrhythmias (91 new events) was the most frequent CVD-related diagnosis after ICI. The time to diagnosis of myocarditis from initiation of ICI occurred the earliest (median 2.5 months, 1.5-6.8 months), followed by myocardial infarction (3.7, 0.5-9), cardiomyopathy (4.5, 1.6-7.3), and tachyarrhythmias (4.9, 1.2-11.4). Patients with myocarditis and tachyarrhythmias mainly presented to the ED for care.

CONCLUSION

The use of ICI in HNC is still expanding and the spectrum of delayed manifestation of ICI-induced cardiovascular toxicities is yet to be fully defined in HNC survivors.

TNIK regulation of interferon signaling and endothelial cell response to virus infection

Background

Traf2 and Nck-interacting kinase (TNIK) is known for its regulatory role in various processes within cancer cells. However, its role within endothelial cells (ECs) has remained relatively unexplored.

Methods

Leveraging RNA-seq data and Ingenuity Pathway Analysis (IPA), we probed the potential impact of TNIK depletion on ECs.

Results

Examination of RNA-seq data uncovered more than 450 Differentially Expressed Genes (DEGs) in TNIK-depleted ECs, displaying a fold change exceeding 2 with a false discovery rate (FDR) below 0.05. IPA analysis unveiled that TNIK depletion leads to the inhibition of the interferon (IFN) pathway [-log (p-value) >11], downregulation of IFN-related genes, and inhibition of Hypercytokinemia/Hyperchemokinemia [-log (p-value) >8]. The validation process encompassed qRT-PCR to evaluate mRNA expression of crucial IFN-related genes, immunoblotting to gauge STAT1 and STAT2 protein levels, and ELISA for the quantification of IFN and cytokine secretion in siTNIK-depleted ECs. These assessments consistently revealed substantial reductions upon TNIK depletion. When transducing HUVECs with replication incompetent E1-E4 deleted adenovirus expressing green fluorescent protein (Ad-GFP), it was demonstrated that TNIK depletion did not affect the uptake of Ad-GFP. Nonetheless, TNIK depletion induced cytopathic effects (CPE) in ECs transduced with wild-type human adenovirus serotype 5 (Ad-WT).

Summary

Our findings suggest that TNIK plays a crucial role in regulating the EC response to virus infections through modulation of the IFN pathway.

Role of blood flow in endothelial functionality: a review

Endothelial cells, located on the surface of blood vessel walls, are constantly stimulated by mechanical forces from the blood flow. The mechanical forces, i.e., fluid shear stress, induced by the blood flow play a pivotal role in controlling multiple physiological processes at the endothelium and in regulating various pathways that maintain homeostasis and vascular function. In this review, research looking at different blood fluid patterns and fluid shear stress in the circulation system is summarized, together with the interactions between the blood flow and the endothelial cells. This review also highlights the flow profile as a response to the configurational changes of the endothelial glycocalyx, which is less revisited in previous reviews. The role of endothelial glycocalyx in maintaining endothelium health and the strategies for the restoration of damaged endothelial glycocalyx are discussed from the perspective of the fluid shear stress. This review provides a new perspective regarding our understanding of the role that blood flow plays in regulating endothelial functionality.

Clearance of Stress-Induced Premature Senescent Cells Alleviates the Formation of Abdominal Aortic Aneurysms

Abdominal aortic aneurysm (AAA) is a multifactorial disease characterized by various pathophysiological processes, including chronic inflammation, oxidative stress, and proteolytic activity in the aortic wall. Stress-induced premature senescence (SIPS) has been implicated in regulating these pathophysiological processes, but whether SIPS contributes to AAA formation remains unknown. Here, we detected SIPS in AAA from patients and young mice. The senolytic agent ABT263 prevented AAA development by inhibiting SIPS. Additionally, SIPS promoted the transformation of vascular smooth muscle cells (VSMCs) from a contractile phenotype to a synthetic phenotype, whereas inhibition of SIPS by the senolytic drug ABT263 suppressed VSMC phenotypic switching. RNA sequencing and single-cell RNA sequencing analysis revealed that fibroblast growth factor 9 (FGF9), secreted by stress-induced premature senescent VSMCs, was a key regulator of VSMC phenotypic switching and that FGF9 knockdown abolished this effect. We further showed that the FGF9 level was critical for the activation of PDGFRβ/ERK1/2 signaling, facilitating VSMC phenotypic change. Taken together, our findings demonstrated that SIPS is critical for VSMC phenotypic switching through the activation of FGF9/PDGFRβ/ERK1/2 signaling, promoting AAA development and progression. Thus, targeting SIPS with the senolytic agent ABT263 may be a valuable therapeutic strategy for the prevention or treatment of AAA.

Premature senescence and cardiovascular disease following cancer treatments: mechanistic insights

Cardiovascular disease (CVD) is a leading cause of morbidity and mortality, especially among the aging population. The "response-to-injury" model proposed by Dr. Russell Ross in 1999 emphasizes inflammation as a critical factor in atherosclerosis development, with atherosclerotic plaques forming due to endothelial cell (EC) injury, followed by myeloid cell adhesion and invasion into the blood vessel walls. Recent evidence indicates that cancer and its treatments can lead to long-term complications, including CVD. Cellular senescence, a hallmark of aging, is implicated in CVD pathogenesis, particularly in cancer survivors. However, the precise mechanisms linking premature senescence to CVD in cancer survivors remain poorly understood. This article aims to provide mechanistic insights into this association and propose future directions to better comprehend this complex interplay.

Metabolic regulation of endothelial senescence

Endothelial cell (EC) senescence is increasingly recognized as a significant contributor to the development of vascular dysfunction and age-related disorders and diseases, including cancer and cardiovascular diseases (CVD). The regulation of cellular senescence is known to be influenced by cellular metabolism. While extensive research has been conducted on the metabolic regulation of senescence in other cells such as cancer cells and fibroblasts, our understanding of the metabolic regulation of EC senescence remains limited. The specific metabolic changes that drive EC senescence are yet to be fully elucidated. The objective of this review is to provide an overview of the intricate interplay between cellular metabolism and senescence, with a particular emphasis on recent advancements in understanding the metabolic changes preceding cellular senescence. I will summarize the current knowledge on the metabolic regulation of EC senescence, aiming to offer insights into the underlying mechanisms and future research directions.

Role of hypoxia in cellular senescence

Senescent cells persist and continuously secrete proinflammatory and tissue-remodeling molecules that poison surrounding cells, leading to various age-related diseases, including diabetes, atherosclerosis, and Alzheimer's disease. The underlying mechanism of cellular senescence has not yet been fully explored. Emerging evidence indicates that hypoxia is involved in the regulation of cellular senescence. Hypoxia-inducible factor (HIF)- 1α accumulates under hypoxic conditions and regulates cellular senescence by modulating the levels of the senescence markers p16, p53, lamin B1, and cyclin D1. Hypoxia is a critical condition for maintaining tumor immune evasion, which is promoted by driving the expression of genetic factors (such as p53 and CD47) while triggering immunosenescence. Under hypoxic conditions, autophagy is activated by targeting BCL-2/adenovirus E1B 19-kDa interacting protein 3, which subsequently induces p21WAF1/CIP1 as well as p16Ink4a and increases β-galactosidase (β-gal) activity, thereby inducing cellular senescence. Deletion of the p21 gene increases the activity of the hypoxia response regulator poly (ADP-ribose) polymerase-1 (PARP-1) and the level of nonhomologous end joining (NHEJ) proteins, repairs DNA double-strand breaks, and alleviates cellular senescence. Moreover, cellular senescence is associated with intestinal dysbiosis and an accumulation of D-galactose derived from the gut microbiota. Chronic hypoxia leads to a striking reduction in the amount of Lactobacillus and D-galactose-degrading enzymes in the gut, producing excess reactive oxygen species (ROS) and inducing senescence in bone marrow mesenchymal stem cells. Exosomal microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) play important roles in cellular senescence. miR-424-5p levels are decreased under hypoxia, whereas lncRNA-MALAT1 levels are increased, both of which induce cellular senescence. The present review focuses on recent advances in understanding the role of hypoxia in cellular senescence. The effects of HIFs, immune evasion, PARP-1, gut microbiota, and exosomal mRNA in hypoxia-mediated cell senescence are specifically discussed. This review increases our understanding of the mechanism of hypoxia-mediated cellular senescence and provides new clues for anti-aging processes and the treatment of aging-related diseases.

An ERK5-NRF2 Axis Mediates Senescence-Associated Stemness and Atherosclerosis

BACKGROUND

ERK5 (extracellular signal-regulated kinase 5) is a dual kinase transcription factor containing an N-terminal kinase domain and a C-terminal transcriptional activation domain. Many ERK5 kinase inhibitors have been developed and tested to treat cancer and inflammatory diseases. However, recent data have raised questions about the role of the catalytic activity of ERK5 in proliferation and inflammation. We aimed to investigate how ERK5 reprograms myeloid cells to the proinflammatory senescent phenotype, subsequently leading to atherosclerosis.

METHODS

A ERK5 S496A (dephosphorylation mimic) knock in (KI) mouse model was generated using CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/clustered regularly interspaced short palindromic repeat-associated 9), and atherosclerosis was characterized by hypercholesterolemia induction. The plaque phenotyping in homozygous ERK5 S496A KI and wild type (WT) mice was studied using imaging mass cytometry. Bone marrow-derived macrophages were isolated from hypercholesterolemic mice and characterized using RNA sequencing and functional in vitro approaches, including senescence, mitochondria reactive oxygen species, and inflammation assays, as well as by metabolic extracellular flux analysis.

RESULTS

We show that atherosclerosis was inhibited in ERK5 S496A KI mice. Furthermore, ERK5 S496 phosphorylation mediates both senescence-associated secretory phenotype and senescence-associated stemness by upregulating AHR (aryl hydrocarbon receptor) in plaque and bone marrow-derived macrophages isolated from hypercholesterolemic mice. We also discovered that ERK5 S496 phosphorylation could induce NRF2 (NFE2-related factor 2) SUMOylation at a novel K518 site to inhibit NRF2 transcriptional activity without altering ERK5 catalytic activity and mediates oxidized LDL (low-density lipoprotein)-induced senescence-associated secretory phenotype. Specific ERK5 kinase inhibitors (AX15836 and XMD8-92) also inhibited ERK5 S496 phosphorylation, suggesting the involvement of ERK5 S496 phosphorylation in the anti-inflammatory effects of these ERK5 kinase inhibitors.

CONCLUSIONS

We discovered a novel mechanism by which the macrophage ERK5-NRF2 axis develops a unique senescence-associated secretory phenotype/stemness phenotype by upregulating AHR to engender atherogenesis. The finding of senescence-associated stemness phenotype provides a molecular explanation to resolve the paradox of senescence in proliferative plaque by permitting myeloid cells to escape the senescence-induced cell cycle arrest during atherosclerosis formation.

Possible molecular mechanisms underlying the development of atherosclerosis in cancer survivors

Cancer survivors undergone treatment face an increased risk of developing atherosclerotic cardiovascular disease (CVD), yet the underlying mechanisms remain elusive. Recent studies have revealed that chemotherapy can drive senescent cancer cells to acquire a proliferative phenotype known as senescence-associated stemness (SAS). These SAS cells exhibit enhanced growth and resistance to cancer treatment, thereby contributing to disease progression. Endothelial cell (EC) senescence has been implicated in atherosclerosis and cancer, including among cancer survivors. Treatment modalities for cancer can induce EC senescence, leading to the development of SAS phenotype and subsequent atherosclerosis in cancer survivors. Consequently, targeting senescent ECs displaying the SAS phenotype hold promise as a therapeutic approach for managing atherosclerotic CVD in this population. This review aims to provide a mechanistic understanding of SAS induction in ECs and its contribution to atherosclerosis among cancer survivors. We delve into the mechanisms underlying EC senescence in response to disturbed flow and ionizing radiation, which play pivotal role in atherosclerosis and cancer. Key pathways, including p90RSK/TERF2IP, TGFβR1/SMAD, and BH4 signaling are explored as potential targets for cancer treatment. By comprehending the similarities and distinctions between different types of senescence and the associated pathways, we can pave the way for targeted interventions aim at enhancing the cardiovascular health of this vulnerable population. The insights gained from this review may facilitate the development of novel therapeutic strategies for managing atherosclerotic CVD in cancer survivors.

Electrically stimulated gene expression under exogenously applied electric fields

Introduction: Electrical stimulation, the application of an electric field to cells and tissues grown in culture to accelerate growth and tight junction formation among endothelial cells, could be impactful in cardiovascular tissue engineering, allotransplantation, and wound healing. Methods: Using Electrical Cell Stimulation And Recording Apparatus (ECSARA), the exploration of the stimulatory influences of electric fields of different magnitude and frequencies on growth and proliferation, trans endothelial electrical resistance (TEER) and gene expression of human endothelia cells (HUVECs) were explored. Results: Within the range of endogenous electrical pulses studied, frequency was found to be more significant (p = 0.05) than voltage in influencing HUVEC gene expression. Localization of Yes Associated Protein (YAP) and expression of CD-144 are shown to be consistent with temporal manifestations of TEER. Discussion: This work introduces the field of electromics, the study of cellular gene expression profiles and their implications under the influence of exogenously applied electric fields. Homology of electrobiology and mechanobiology suggests use of such exogenous cues in tissue and regenerative engineering.

Paradigms of endothelial stiffening in cardiovascular disease and vascular aging

Endothelial cells, the inner lining of the blood vessels, are well-known to play a critical role in vascular function, while endothelial dysfunction due to different cardiovascular risk factors or accumulation of disruptive mechanisms that arise with aging lead to cardiovascular disease. In this review, we focus on endothelial stiffness, a fundamental biomechanical property that reflects cell resistance to deformation. In the first part of the review, we describe the mechanisms that determine endothelial stiffness, including RhoA-dependent contractile response, actin architecture and crosslinking, as well as the contributions of the intermediate filaments, vimentin and lamin. Then, we review the factors that induce endothelial stiffening, with the emphasis on mechanical signals, such as fluid shear stress, stretch and stiffness of the extracellular matrix, which are well-known to control endothelial biomechanics. We also describe in detail the contribution of lipid factors, particularly oxidized lipids, that were also shown to be crucial in regulation of endothelial stiffness. Furthermore, we discuss the relative contributions of these two mechanisms of endothelial stiffening in vasculature in cardiovascular disease and aging. Finally, we present the current state of knowledge about the role of endothelial stiffening in the disruption of endothelial cell-cell junctions that are responsible for the maintenance of the endothelial barrier.

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.

Advances in immune checkpoint inhibitors induced-cardiotoxicity

Immune checkpoint inhibitors (ICIs) are approved as the first-line drug for treating many cancers and has shown significant survival benefits; however, it also causes immune-related adverse events (irAEs) while activating the immune system, involving multiple organs. Among them, cardiovascular immune-related adverse events (CV-irAE) are rare, but common causes of death in ICIs treated cancer patients, which manifest as myocardial, pericardial, vascular and other cardiovascular toxicities. Therefore, it is important that irAEs, especially CV-irAE should be carefully recognized and monitored during the whole ICIs treatment because early detection and treatment of CV-irAE can significantly reduce the mortality of such patients. Consequently, it is urgent to fully understand the mechanism and management strategies of CV-irAE. The effects of ICIs are multifaceted and the exact mechanism of CV-irAE is still elusive. Generally, T cells identify tumor cell antigens as well as antigen in cardiomyocytes that are the same as or homologous to those on tumor cells, thus causing myocardial damage. In addition, ICIs promote formation of cardiac troponin I (cTnI) that induces cardiac dysfunction and myocardial dilatation; moreover, ICIs also increase the production of cytokines, which promote infiltration of inflammation-linked molecules into off-target tissues. Currently, the management and treatment of cardiovascular toxicity are largely dependent on glucocorticoids, more strategies for prevention and treatment of CV-irAE, such as predictive markers are being explored. This review discusses risk factors, potential pathophysiological mechanisms, clinical manifestations, and management and treatment of CV-irAE, guiding the development of more effective prevention, treatment and management strategies in the future.

Identification of the metabolic state of surviving cardiomyocytes in the human infarcted heart by spatial single-cell transcriptomics

The metabolic status of surviving cardiomyocytes (CM) in the myocardial tissues of patients who sustained myocardial infarction (MI) is largely unknown. Spatial single-cell RNA-sequencing (scRNA-seq) is a novel tool that enables the unbiased analysis of RNA signatures within intact tissues. We employed this tool to assess the metabolic profiles of surviving CM in the myocardial tissues of patients post-MI.

Methods

A spatial scRNA-seq dataset was used to compare the genetic profiles of CM from patients with MI and control patients; we analyzed the metabolic adaptations of surviving CM within the ischemic niche. A standard pipeline in Seurat was used for data analysis, including normalization, feature selection, and identification of highly variable genes using principal component analysis (PCA). Harmony was used to remove batch effects and integrate the CM samples based on annotations. Uniform manifold approximation and projection (UMAP) was used for dimensional reduction. The Seurat "FindMarkers" function was used to identify differentially expressed genes (DEGs), which were analyzed by the Gene Ontology (GO) enrichment pathway. Finally, the scMetabolism R tool pipeline with parameters method = VISION (Vision is a flexible system that utilizes a high-throughput pipeline and an interactive web-based report to annotate and explore scRNA-seq datasets in a dynamic manner) and metabolism.type = Kyoto Encyclopedia of Genes and Genomes (KEGG) was used to quantify the metabolic activity of each CM.

Results

Analysis of spatial scRNA-seq data showed fewer surviving CM in infarcted hearts than in control hearts. GO analysis revealed repressed pathways in oxidative phosphorylation, cardiac cell development, and activated pathways in response to stimuli and macromolecular metabolic processes. Metabolic analysis showed downregulated energy and amino acid pathways and increased purine, pyrimidine, and one-carbon pool by folate pathways in surviving CM.

Conclusions

Surviving CM within the infarcted myocardium exhibited metabolic adaptations, as evidenced by the downregulation of most pathways linked to oxidative phosphorylation, glucose, fatty acid, and amino acid metabolism. In contrast, pathways linked to purine and pyrimidine metabolism, fatty acid biosynthesis, and one-carbon metabolism were upregulated in surviving CM. These novel findings have implications for the development of effective strategies to improve the survival of hibernating CM within the infarcted heart.

Senescence-Associated Secretory Phenotype of Cardiovascular System Cells and Inflammaging: Perspectives of Peptide Regulation

A senescence-associated secretory phenotype (SASP) and a mild inflammatory response characteristic of senescent cells (inflammaging) form the conditions for the development of cardiovascular diseases: atherosclerosis, coronary heart disease, and myocardial infarction. The purpose of the review is to analyze the pool of signaling molecules that form SASP and inflammaging in cells of the cardiovascular system and to search for targets for the action of vasoprotective peptides. The SASP of cells of the cardiovascular system is characterized by a change in the synthesis of anti-proliferative proteins (p16, p19, p21, p38, p53), cytokines characteristic of inflammaging (IL-1α,β, IL-4, IL-6, IL-8, IL-18, TNFα, TGFβ1, NF-κB, MCP), matrix metalloproteinases, adhesion molecules, and sirtuins. It has been established that peptides are physiological regulators of body functions. Vasoprotective polypeptides (liraglutide, atrial natriuretic peptide, mimetics of relaxin, Ucn1, and adropin), KED tripeptide, and AEDR tetrapeptide regulate the synthesis of molecules involved in inflammaging and SASP-forming cells of the cardiovascular system. This indicates the prospects for the development of drugs based on peptides for the treatment of age-associated cardiovascular pathology.

A Unified Model of Age-Related Cardiovascular Disease

Despite progress in biomedical technologies, cardiovascular disease remains the main cause of mortality. This is at least in part because current clinical interventions do not adequately take into account aging as a driver and are hence aimed at suboptimal targets. To achieve progress, consideration needs to be given to the role of cell aging in disease pathogenesis. We propose a model unifying the fundamental processes underlying most age-associated cardiovascular pathologies. According to this model, cell aging, leading to cell senescence, is responsible for tissue changes leading to age-related cardiovascular disease. This process, occurring due to telomerase inactivation and telomere attrition, affects all components of the cardiovascular system, including cardiomyocytes, vascular endothelial cells, smooth muscle cells, cardiac fibroblasts, and immune cells. The unified model offers insights into the relationship between upstream risk factors and downstream clinical outcomes and explains why interventions aimed at either of these components have limited success. Potential therapeutic approaches are considered based on this model. Because telomerase activity can prevent and reverse cell senescence, telomerase gene therapy is discussed as a promising intervention. Telomerase gene therapy and similar systems interventions based on the unified model are expected to be transformational in cardiovascular medicine.

A transient inflammatory response contributes to oxaliplatin neurotoxicity in mice

OBJECTIVES

Peripheral neuropathy is a relevant dose-limiting adverse event that can affect up to 90% of oncologic patients with colorectal cancer receiving oxaliplatin treatment. The severity of neurotoxicity often leads to dose reduction or even premature cessation of chemotherapy. Unfortunately, the limited knowledge about the molecular mechanisms related to oxaliplatin neurotoxicity leads to a lack of effective treatments to prevent the development of this clinical condition. In this context, the present work aimed to determine the exact molecular mechanisms involved in the development of oxaliplatin neurotoxicity in a murine model to try to find new therapeutical targets.

METHODS

By single-cell RNA sequencing (scRNA-seq), we studied the transcriptomic profile of sensory neurons and satellite glial cells (SGC) of the Dorsal Root Ganglia (DRG) from a well-characterized mouse model of oxaliplatin neurotoxicity.

RESULTS

Analysis of scRNA-seq data pointed to modulation of inflammatory processes in response to oxaliplatin treatment. In this line, we observed increased levels of NF-kB p65 protein, pro-inflammatory cytokines, and immune cell infiltration in DRGs and peripheral nerves of oxaliplatin-treated mice, which was accompanied by mechanical allodynia and decrease in sensory nerve amplitudes.

INTERPRETATION

Our data show that, in addition to the well-described DNA damage, oxaliplatin neurotoxicity is related to an exacerbated pro-inflammatory response in DRG and peripheral nerves, and open new insights in the development of anti-inflammatory strategies as a treatment for preventing peripheral neuropathy induced by oxaliplatin.

Factors and Pathways Modulating Endothelial Cell Senescence in Vascular Aging

Aging causes a progressive decline in the structure and function of organs. With advancing age, an accumulation of senescent endothelial cells (ECs) contributes to the risk of developing vascular dysfunction and cardiovascular diseases, including hypertension, diabetes, atherosclerosis, and neurodegeneration. Senescent ECs undergo phenotypic changes that alter the pattern of expressed proteins, as well as their morphologies and functions, and have been linked to vascular impairments, such as aortic stiffness, enhanced inflammation, and dysregulated vascular tone. Numerous molecules and pathways, including sirtuins, Klotho, RAAS, IGFBP, NRF2, and mTOR, have been implicated in promoting EC senescence. This review summarizes the molecular players and signaling pathways driving EC senescence and identifies targets with possible therapeutic value in age-related vascular diseases.

Epigenetic Control of Vascular Smooth Muscle Cell Function in Atherosclerosis: A Role for DNA Methylation

Atherosclerosis is a complex vascular inflammatory disease in which multiple cell types are involved, including vascular smooth muscle cells (VSMCs). In response to vascular injury and inflammatory stimuli, VSMCs undergo a "phenotypic switching" characterized by extracellular matrix secretion, loss of contractility, and abnormal proliferation and migration, which play a key role in the progression of atherosclerosis. DNA methylation modification is an important epigenetic mechanism that plays an important role in atherosclerosis. Studies investigating abnormal DNA methylation in patients with atherosclerosis have determined a specific DNA methylation profile, and proposed multiple pathways and genes involved in the etiopathogenesis of atherosclerosis. Recent studies have also revealed that DNA methylation modification controls VSMC function by regulating gene expression involved in atherosclerosis. In this review, we summarize the recent advances regarding the epigenetic control of VSMC function by DNA methylation in atherosclerosis and provide insights into the development of VSMC-centered therapeutic strategies.

Redox Imbalance and Its Metabolic Consequences in Tick-Borne Diseases

One of the growing global health problems are vector-borne diseases, including tick-borne diseases. The most common tick-borne diseases include Lyme disease, tick-borne encephalitis, human granulocytic anaplasmosis, and babesiosis. Taking into account the metabolic effects in the patient’s body, tick-borne diseases are a significant problem from an epidemiological and clinical point of view. Inflammation and oxidative stress are key elements in the pathogenesis of infectious diseases, including tick-borne diseases. In consequence, this leads to oxidative modifications of the structure and function of phospholipids and proteins and results in qualitative and quantitative changes at the level of lipid mediators arising in both reactive oxygen species (ROS) and ROS enzyme–dependent reactions. These types of metabolic modifications affect the functioning of the cells and the host organism. Therefore, links between the severity of the disease state and redox imbalance and the level of phospholipid metabolites are being searched, hoping to find unambiguous diagnostic biomarkers. Assessment of molecular effects of oxidative stress may also enable the monitoring of the disease process and treatment efficacy.

Metformin mitigates stress-induced premature senescence by upregulating AMPKα at Ser485 phosphorylation induced SIRT3 expression and inactivating mitochondrial oxidants

The senescence of vascular smooth muscle cells (VSMCs) is an important cause of cardiovascular disease such as atherosclerosis and hypertension. These senescence may be triggered by many factors, such as oxidative stress, inflammation, DNA damage, and senescence-associated secretory phenotypes (SASPs). Mitochondrial oxidative stress induces cellular senescence, but the mechanisms by which mitochondrial reactive oxygen species (mtROS) regulates cellular senescence are still largely unknown. Here, we investigated the mechanism responsible for the anti-aging effect of metformin by examining links between VSMC senescence and mtROS in in vitro and in vivo. Metformin was found to increase p-AMPK (Ser485), but to decrease senescence-associated phenotypes and protein levels of senescence markers during ADR-induced VSMC senescence. Importantly, metformin decreased mtROS by inducing the deacetylation of superoxide dismutase 2 (SOD2) by increasing SIRT3 expression. Moreover, AMPK depletion reduced the expression of SIRT3 and increased the expression of acetylated SOD2 despite metformin treatment, suggesting AMPK activation by metformin is required to protect against mitochondrial oxidative stress by SIRT3. This study provides mechanistic evidence that metformin acts as an anti-aging agent and alleviates VSMC senescence by upregulating mitochondrial antioxidant induced p-AMPK (Ser485)-dependent SIRT3 expression, which suggests metformin has therapeutic potential for the treatment of age-associated vascular disease.

Alterungsbedingte Gefäßveränderungen am Beispiel der Arteria carotis

Einer der Hauptrisikofaktoren für das Vorliegen einer Karotisstenose und des karotisbedingten Schlaganfalls ist das Lebensalter. Ziel dieses Übersichtsartikels ist die Darstellung des aktuellen Wissensstands über altersbedingte Veränderungen der Gefäße am Beispiel der Karotisstenose.

Die Gefäßalterung (vaskuläre Seneszenz) als Abnahme struktureller und funktioneller Eigenschaften der Gefäßwand spielt sich auf verschiedenen Ebenen ab. Auf multizellulärer Ebene kommt es mit zunehmendem Alter hauptsächlich aufgrund von atherosklerotischen Veränderungen der Gefäßwand zu einer Zunahme von Gefäßvolumen und -durchmesser sowie der Intima-Media-Dicke. Auf zellulärer und extrazellulärer Ebene kommt es zur Abnahme von Elastinfasern, glatten Muskelzellen und der Gesamtzellularität sowie zur Zunahme der Lipid‑, Cholesterin- und Kalziumphosphatablagerungen und der Neovaskularisierung. Ursachen der Gefäßalterung auf molekularer Ebene sind insbesondere oxidativer Stress, chronische Entzündungsreaktion, mitochondriale Dysfunktion, epigenetische Veränderungen, Dysregulation der Expression nicht kodierender RNAs (ncRNAs) und die Zunahme der Seneszenz. Der altersbedingte Verlust der Heilungs- und Reparaturfähigkeit des Gewebes macht die Plaques vulnerabler und im Falle der A. carotis anfälliger für ischämische Schlaganfälle.

Zunehmende Erkenntnisse über den Einfluss des Alterns auf die Epigenetik und der ncRNAs in atherosklerotischen Plaques kann zukünftig das individuelle Risiko von Patienten genauer quantifizieren und zur Entwicklung zielgerichteter Therapiestrategien beitragen. Weitere Studien sind auf diesem Gebiet jedoch notwendig, um das gesamte Ausmaß der Gefäßalterung und den damit einhergehenden Erkrankungen zu verstehen, damit diesen dann gezielt entgegenwirkt werden kann.

Ageing- and AAA-associated differentially expressed proteins identified by proteomic analysis in mice

Background

Abdominal aortic aneurysm (AAA) is a disease of high prevalence in old age, and its incidence gradually increases with increasing age. There were few studies about differences in the circulatory system in the incidence of AAA, mainly because younger patients with AAA are fewer and more comorbid nonatherosclerotic factors.

Method

We induced AAA in ApoE^-/- male mice of different ages (10 or 24 weeks) and obtained plasma samples. After the top 14 most abundant proteins were detected, the plasma was analyzed by a proteomic study using the data-dependent acquisition (DDA) technique. The proteomic results were compared between different groups to identify age-related differentially expressed proteins (DEPs) in the circulation that contribute to AAA formation. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and protein-protein interaction (PPI) network analyses were performed by R software. The top 10 proteins were determined with the MCC method of Cytoscape, and transcription factor (TF) prediction of the DEPs was performed with iRegulon (Cytoscape).

Results

The aortic diameter fold increase was higher in the aged group than in the youth group (p < 0.01). Overall, 92 DEPs related to age and involved in AAA formation were identified. GO analysis of the DEPs showed enrichment of the terms wounding healing, response to oxidative stress, regulation of body fluid levels, ribose phosphate metabolic process, and blood coagulation. The KEGG pathway analysis showed enrichment of the terms platelet activation, complement and coagulation cascades, glycolysis/gluconeogenesis, carbon metabolism, biosynthesis of amino acids, and ECM-receptor interaction. The top 10 proteins were Tpi1, Eno1, Prdx1, Ppia, Prdx6, Vwf, Prdx2, Fga, Fgg, and Fgb, and the predicted TFs of these proteins were Nfe2, Srf, Epas1, Tbp, and Hoxc8.

Conclusion

The identified proteins related to age and involved in AAA formation were associated with the response to oxidative stress, coagulation and platelet activation, and complement and inflammation pathways, and the TFs of these proteins might be potential targets for AAA treatments. Further experimental and biological studies are needed to elucidate the role of these age-associated and AAA-related proteins in the progression of AAA.

Annexin A Protein Family in Atherosclerosis

Atherosclerosis, a silent chronic vascular pathology, is the cause of the majority of cardiovascular ischaemic events. Atherosclerosis is characterized by a series of deleterious changes in cellularity, including endothelial dysfunction, transmigration of circulating inflammatory cells into the arterial wall, pro-inflammatory cytokines production, lipid accumulation in the intima, vascular local inflammatory response, atherosclerosis-related cells apoptosis and autophagy. Proteins of Annexin A (AnxA) family, the well-known Ca²⁺ phospholipid-binding protein, have many functions in regulating inflammation-related enzymes and cell signaling transduction, thus influencing cell adhesion, migration, differentiation, proliferation and apoptosis. There is now accumulating evidence that some members of the AnxA family, such as AnxA1, AnxA2, AnxA5 and AnxA7, play major roles in the development of atherosclerosis. This article discusses the major roles of AnxA1, AnxA2, AnxA5 and AnxA7, and the multifaceted mechanisms of the main biological process in which they are involved in atherosclerosis. Considering these evidences, it has been proposed that AnxA are drivers- and not merely participator- on the road to atherosclerosis, thus the progression of atherosclerosis may be prevented by targeting the expression or function of the AnxA family proteins.

Senolytics: Eliminating Senescent Cells and Alleviating Intervertebral Disc Degeneration

Intervertebral disc degeneration (IVDD) is the main cause of cervical and lumbar spondylosis. Over the past few years, the relevance between cellular senescence and IVDD has been widely studied, and the senescence-associated secretory phenotype (SASP) produced by senescent cells is found to remodel extracellular matrix (ECM) metabolism and destruct homeostasis. Elimination of senescent cells by senolytics and suppression of SASP production by senomorphics/senostatics are effective strategies to alleviate degenerative diseases including IVDD. Here, we review the involvement of senescence in the process of IVDD; we also discuss the potential of senolytics on eliminating senescent disc cells and alleviating IVDD; finally, we provide a table listing senolytic drugs and small molecules, aiming to propose potential drugs for IVDD therapy in the future.

Endothelial and systemic upregulation of miR-34a-5p fine-tunes senescence in progeria

Endothelial defects significantly contribute to cardiovascular pathology in the premature aging disease Hutchinson-Gilford progeria syndrome (HGPS). Using an endothelium-specific progeria mouse model, we identify a novel, endothelium-specific microRNA (miR) signature linked to the p53-senescence pathway and a senescence-associated secretory phenotype (SASP). Progerin-expressing endothelial cells exert profound cell-non-autonomous effects initiating senescence in non-endothelial cell populations and causing immune cell infiltrates around blood vessels. Comparative miR expression analyses revealed unique upregulation of senescence-associated miR34a-5p in endothelial cells with strong accumulation at atheroprone aortic arch regions but also, in whole cardiac- and lung tissues as well as in the circulation of progeria mice. Mechanistically, miR34a-5p knockdown reduced not only p53 levels but also late-stage senescence regulator p16 with no effect on p21 levels, while p53 knockdown reduced miR34a-5p and partially rescued p21-mediated cell cycle inhibition with a moderate effect on SASP. These data demonstrate that miR34a-5p reinforces two separate senescence regulating branches in progerin-expressing endothelial cells, the p53- and p16-associated pathways, which synergistically maintain a senescence phenotype that contributes to cardiovascular pathology. Thus, the key function of circulatory miR34a-5p in endothelial dysfunction-linked cardiovascular pathology offers novel routes for diagnosis, prognosis and treatment for cardiovascular aging in HGPS and potentially geriatric patients.

Cancer treatment-induced NAD+ depletion in premature senescence and late cardiovascular complications

Numerous studies have revealed the critical role of premature senescence induced by various cancer treatment modalities in the pathogenesis of aging-related diseases. Senescence-associated secretory phenotype (SASP) can be induced by telomere dysfunction. Telomeric DNA damage response induced by some cancer treatments can persist for months, possibly accounting for long-term sequelae of cancer treatments. Telomeric DNA damage-induced mitochondrial dysfunction and increased reactive oxygen species production are hallmarks of premature senescence. Recently, we reported that the nucleus-mitochondria positive feedback loop formed by p90 ribosomal S6 kinase (p90RSK) and phosphorylation of S496 on ERK5 (a unique member of the mitogen-activated protein kinase family that is not only a kinase but also a transcriptional co-activator) were vital signaling events that played crucial roles in linking mitochondrial dysfunction, nuclear telomere dysfunction, persistent SASP induction, and atherosclerosis. In this review, we will discuss the role of NAD⁺ depletion in instigating SASP and its downstream signaling and regulatory mechanisms that lead to the premature onset of atherosclerotic cardiovascular diseases in cancer survivors.

Senescence Alterations in Pulmonary Hypertension

Cellular senescence is the arrest of normal cell division and is commonly associated with aging. The interest in the role of cellular senescence in lung diseases derives from the observation of markers of senescence in chronic obstructive pulmonary disease (COPD), pulmonary fibrosis (IPF), and pulmonary hypertension (PH). Accumulation of senescent cells and the senescence-associated secretory phenotype in the lung of aged patients may lead to mild persistent inflammation, which results in tissue damage. Oxidative stress due to environmental exposures such as cigarette smoke also promotes cellular senescence, together with additional forms of cellular stress such as mitochondrial dysfunction and endoplasmic reticulum stress. Growing recent evidence indicate that senescent cell phenotypes are observed in pulmonary artery smooth muscle cells and endothelial cells of patients with PH, contributing to pulmonary artery remodeling and PH development. In this review, we analyze the role of different senescence cell phenotypes contributing to the pulmonary artery remodeling process in different PH clinical entities. Different molecular pathway activation and cellular functions derived from senescence activation will be analyzed and discussed as promising targets to develop future senotherapies as promising treatments to attenuate pulmonary artery remodeling in PH.

Nucleus-mitochondria positive feedback loop formed by ERK5 S496 phosphorylation-mediated poly (ADP-ribose) polymerase activation provokes persistent pro-inflammatory senescent phenotype and accelerates coronary atherosclerosis after chemo-radiation

The incidence of cardiovascular disease (CVD) is higher in cancer survivors than in the general population. Several cancer treatments are recognized as risk factors for CVD, but specific therapies are unavailable. Many cancer treatments activate shared signaling events, which reprogram myeloid cells (MCs) towards persistent senescence-associated secretory phenotype (SASP) and consequently CVD, but the exact mechanisms remain unclear. This study aimed to provide mechanistic insights and potential treatments by investigating how chemo-radiation can induce persistent SASP. We generated ERK5 S496A knock-in mice and determined SASP in myeloid cells (MCs) by evaluating their efferocytotic ability, antioxidation-related molecule expression, telomere length, and inflammatory gene expression. Candidate SASP inducers were identified by high-throughput screening, using the ERK5 transcriptional activity reporter cell system. Various chemotherapy agents and ionizing radiation (IR) up-regulated p90RSK-mediated ERK5 S496 phosphorylation. Doxorubicin and IR caused metabolic changes with nicotinamide adenine dinucleotide depletion and ensuing mitochondrial stunning (reversible mitochondria dysfunction without showing any cell death under ATP depletion) via p90RSK-ERK5 modulation and poly (ADP-ribose) polymerase (PARP) activation, which formed a nucleus-mitochondria positive feedback loop. This feedback loop reprogramed MCs to induce a sustained SASP state, and ultimately primed MCs to be more sensitive to reactive oxygen species. This priming was also detected in circulating monocytes from cancer patients after IR. When PARP activity was transiently inhibited at the time of IR, mitochondrial stunning, priming, macrophage infiltration, and coronary atherosclerosis were all eradicated. The p90RSK-ERK5 module plays a crucial role in SASP-mediated mitochondrial stunning via regulating PARP activation. Our data show for the first time that the nucleus-mitochondria positive feedback loop formed by p90RSK-ERK5 S496 phosphorylation-mediated PARP activation plays a crucial role of persistent SASP state, and also provide preclinical evidence supporting that transient inhibition of PARP activation only at the time of radiation therapy can prevent future CVD in cancer survivors.

Grape Seed Proanthocyanidin Extract Moderated Retinal Pigment Epithelium Cellular Senescence Through NAMPT/SIRT1/NLRP3 Pathway

Background

Retinal pigment epithelium (RPE) cellular senescence is an important process in degenerative retinal disorders. Grape seed proanthocyanidin extract (GSPE) alleviates senescence-related degenerative disorders; however, the potential effects of GSPE intake on RPE cellular senescence through regulating NAMPT/SIRT1/NLRP3 pathway remain unclear.

Methods

The effects of GSPE on NAMPT expression and NAD+ contents were detected with Western blot and assay kit in both in-vivo and in-vitro AMD models. Senescence-related biomarkers, including p16, p21 expressions and β-gal staining, were conducted in different groups. The protective effects of GSPE treatment on the mitochondrial homeostasis and barrier function of RPE cells were detected using mtDNA lesions analyses, JC-1 staining, ZO1 staining and trans-epithelial cell resistance (TEER) detection. The expression of senescence-associated secretory phenotype (SASP) in different groups would be conducted with qPCR. To demonstrate the potential effects of NAMPT/SIRT1/NLRP3 pathway after GSPE treatment, the protein levels of relevant key regulators after applications of NAMPT inhibitor, Fk866, and SIRT1 inhibitor, EX-527.

Results

GSPE significantly improves the NAMPT expression and NAD+ content in aging mice, and thus alleviates the RPE cellular senescence. In advanced in-vitro studies, GSPE significantly up-regulated NAMPT content and thus relieved H₂O₂ induced NAD+ depression through analyzing the NAD+ contents in different groups. In advanced analyses, it was reported that GSPE could alleviate mitochondrial permeability, mtDNA damage, ZO1 expression and SASP levels in aging RPE cells. Thus, GSPE treatment significantly decreased senescence-related protein p16 and p21, as well as SASP levels in in-vitro aging model, and it was demonstrated that GSPE could illustrate a significant anti-aging effect. The Western blot data in GSPE treatment of aging RPE cells demonstrated that GSPE could significantly improve NAMPT and SIRT1 levels, and thus depressed NLRP3 expression.

Conclusion

This study indicated that GSPE alleviated RPE cellular senescence through NAMPT/SIRT1/NLRP3 pathway. This study highlighted the potential effects of GSPE on degenerative retinopathy through the crosstalk of NAD+ metabolism, SIRT1 function and NLRP3 activation.

Vascular Endothelial Senescence: Pathobiological Insights, Emerging Long Noncoding RNA Targets, Challenges and Therapeutic Opportunities

Cellular senescence is a stable form of cell cycle arrest in response to various stressors. While it serves as an endogenous pro-resolving mechanism, detrimental effects ensue when it is dysregulated. In this review, we introduce recent advances for cellular senescence and inflammaging, the underlying mechanisms for the reduction of nicotinamide adenine dinucleotide in tissues during aging, new knowledge learned from p16 reporter mice, and the development of machine learning algorithms in cellular senescence. We focus on pathobiological insights underlying cellular senescence of the vascular endothelium, a critical interface between blood and all tissues. Common causes and hallmarks of endothelial senescence are highlighted as well as recent advances in endothelial senescence. The regulation of cellular senescence involves multiple mechanistic layers involving chromatin, DNA, RNA, and protein levels. New targets are discussed including the roles of long noncoding RNAs in regulating endothelial cellular senescence. Emerging small molecules are highlighted that have anti-aging or anti-senescence effects in age-related diseases and impact homeostatic control of the vascular endothelium. Lastly, challenges and future directions are discussed including heterogeneity of endothelial cells and endothelial senescence, senescent markers and detection of senescent endothelial cells, evolutionary differences for immune surveillance in mice and humans, and long noncoding RNAs as therapeutic targets in attenuating cellular senescence. Accumulating studies indicate that cellular senescence is reversible. A better understanding of endothelial cellular senescence through lifestyle and pharmacological interventions holds promise to foster a new frontier in the management of cardiovascular disease risk.

Mechanotransduction-on-chip: vessel-chip model of endothelial YAP mechanobiology reveals matrix stiffness impedes shear response

Endothelial mechanobiology is a key consideration in the progression of vascular dysfunction, including atherosclerosis. However mechanistic connections between the clinically associated physical stimuli, vessel stiffness and shear stress, and how they interact to modulate plaque progression remain incompletely characterized. Vessel-chip systems are excellent candidates for modeling vascular mechanobiology as they may be engineered from the ground up, guided by the mechanical parameters present in human arteries and veins, to recapitulate key features of the vasculature. Here, we report extensive validation of a vessel-chip model of endothelial yes-associated protein (YAP) mechanobiology, a protein sensitive to both matrix stiffness and shearing forces and, importantly, implicated in atherosclerotic progression. Our model captures the established endothelial mechanoresponse, with endothelial alignment, elongation, reduction of adhesion molecules, and YAP cytoplasmic retention under high laminar shear. Conversely, we observed disturbed morphology, inflammation, and nuclear partitioning under low, high, and high oscillatory shear. Examining targets of YAP transcriptional co-activation, connective tissue growth factor (CTGF) is strongly downregulated by high laminar shear, whereas it is strongly upregulated by low shear or oscillatory flow. Ankyrin repeat domain 1 (ANKRD1) is only upregulated by high oscillatory shear. Verteporfin inhibition of YAP reduced the expression of CTGF but did not affect ANKRD1. Lastly, substrate stiffness modulated the endothelial shear mechanoresponse. Under high shear, softer substrates showed the lowest nuclear localization of YAP whereas stiffer substrates increased nuclear localization. Low shear strongly increased nuclear localization of YAP across stiffnesses. Together, we have validated a model of endothelial mechanobiology and describe a clinically relevant biological connection between matrix stiffness, shear stress, and endothelial activation via YAP mechanobiology.

SARS-CoV-2 Mediated Endothelial Dysfunction: The Potential Role of Chronic Oxidative Stress

Endothelial cells have emerged as key players in SARS-CoV-2 infection and COVID-19 inflammatory pathologies. Dysfunctional endothelial cells can promote chronic inflammation and disease processes like thrombosis, atherosclerosis, and lung injury. In endothelial cells, mitochondria regulate these inflammatory pathways via redox signaling, which is primarily achieved through mitochondrial reactive oxygen species (mtROS). Excess mtROS causes oxidative stress that can initiate and exacerbate senescence, a state that promotes inflammation and chronic endothelial dysfunction. Oxidative stress can also activate feedback loops that perpetuate mitochondrial dysfunction, mtROS overproduction, and inflammation. In this review, we provide an overview of phenotypes mediated by mtROS in endothelial cells - such as mitochondrial dysfunction, inflammation, and senescence - as well as how these chronic states may be initiated by SARS-CoV-2 infection of endothelial cells. We also propose that SARS-CoV-2 activates mtROS-mediated feedback loops that cause long-term changes in host redox status and endothelial function, promoting cardiovascular disease and lung injury after recovery from COVID-19. Finally, we discuss the implications of these proposed pathways on long-term vascular health and potential treatments to address these chronic conditions.

Mitochondria and chronic effects of cancer therapeutics: The clinical implications

One of the major mechanisms of action of chemo-radiation is to induce cellular senescence, which exerts crucial roles in age-related pathology. The concept of senescence is evolved, and the novel understanding of senescence-associated reprogramming/stemness has emerged. This new concept emphasizes senescence as not only cell cycle arrest but describes that subsets of senescent cells induced by chemotherapy can re-enter cell cycles, proliferate rapidly, and acquire "stemness" status. Cancer therapeutics, including chemo-radiation triggers toxicity effects through damaging mitochondria, primarily through the upregulation of mtROS production leading to subsequent mtDNA and telomeric DNA damage elicitng DNA damage responses (DDR). The ultimate goal of this review is to highlight the new concept of senescence-associated stemness that is induced by cancer treatment and its adverse effects on the vascular system. We will describe how chemo-radiation exerts toxicity effects by simultaneously producing reactive oxygen species in mitochondria and promoting DDR in the nucleus. We discuss the potential of clinical targeting poly (ADP-ribose) polymerase which might prevent downstream mitochondrial dysfunction and confer protection to cancer survivors. Overall we emphasize the importance of recognizing the consequences of cardio-toxic effects of several cancer treatments and therefore developing personalized therapeutic approaches to screen for inflammatory and cardiac testing for better patient survival.