Cell Senescence, Multiple Organelle Dysfunction and Atherosclerosis

Cellular senescence in cancer: molecular mechanisms and therapeutic targets

Aging exhibits several hallmarks in common with cancer, such as cellular senescence, dysbiosis, inflammation, genomic instability, and epigenetic changes. In recent decades, research into the role of cellular senescence on tumor progression has received widespread attention. While how senescence limits the course of cancer is well established, senescence has also been found to promote certain malignant phenotypes. The tumor-promoting effect of senescence is mainly elicited by a senescence-associated secretory phenotype, which facilitates the interaction of senescent tumor cells with their surroundings. Targeting senescent cells therefore offers a promising technique for cancer therapy. Drugs that pharmacologically restore the normal function of senescent cells or eliminate them would assist in reestablishing homeostasis of cell signaling. Here, we describe cell senescence, its occurrence, phenotype, and impact on tumor biology. A "one-two-punch" therapeutic strategy in which cancer cell senescence is first induced, followed by the use of senotherapeutics for eliminating the senescent cells is introduced. The advances in the application of senotherapeutics for targeting senescent cells to assist cancer treatment are outlined, with an emphasis on drug categories, and the strategies for their screening, design, and efficient targeting. This work will foster a thorough comprehension and encourage additional research within this field.

Understanding the intricacies of cellular senescence in atherosclerosis: Mechanisms and therapeutic implications

Cardiovascular disease is currently the largest cause of mortality and disability globally, surpassing communicable diseases, and atherosclerosis is the main contributor to this epidemic. Aging is intimately linked to atherosclerosis development and progression, however, the mechanism of aging in atherosclerosis is not well known. To emphasize the significant research on the involvement of senescent cells in atherosclerosis, we begin by outlining compelling evidence that indicates various types of senescent cells and SASP factors linked to atherosclerotic phenotypes. We subsequently provide a comprehensive summary of the existing knowledge, shedding light on the intricate mechanisms through which cellular senescence contributes to the pathogenesis of atherosclerosis. Further, we cover that senescence can be identified by both structural changes and several senescence-associated biomarkers. Finally, we discuss that preventing accelerated cellular senescence represents an important therapeutic potential, as permanent changes may occur in advanced atherosclerosis. Together, the review summarizes the relationship between cellular senescence and atherosclerosis, and inspects the molecular knowledge, and potential clinical significance of senescent cells in developing senescent-based therapy, thus providing crucial insights into their biology and potential therapeutic exploration.

PURPL and NEAT1 Long Non-Coding RNAs Are Modulated in Vascular Smooth Muscle Cell Replicative Senescence

Cellular senescence is characterized by proliferation and migration exhaustion, senescence-associated secretory phenotype (SASP), and oxidative stress. Senescent vascular smooth muscle cells (VSMCs) contribute to cardiovascular diseases and atherosclerotic plaque instability. Since there are no unanimously agreed senescence markers in human VSMCs, to improve our knowledge, we looked for new possible senescence markers. To this end, we first established and characterized a model of replicative senescence (RS) in human aortic VSMCs. Old cells displayed several established senescence-associated markers. They stained positive for the senescence-associated β-galactosidase, showed a deranged proliferation rate, a dramatically reduced expression of PCNA, an altered migratory activity, increased levels of TP53 and cell-cycle inhibitors p21/p16, and accumulated in the G1 phase. Old cells showed an altered cellular and nuclear morphology, downregulation of the expression of LMNB1 and HMGB1, and increased expression of SASP molecules (IL1β, IL6, IL8, and MMP3). In these senescent VSMCs, among a set of 12 manually selected long non-coding RNAs (lncRNAs), we detected significant upregulation of PURPL and NEAT1. We observed also, for the first time, increased levels of RRAD mRNA. The detection of modulated levels of RRAD, PURPL, and NEAT1 during VSMC senescence could be helpful for future studies on potential anti-aging factors.

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.

The Protective Effects of Eicosapentaenoic Acid for Stress-induced Accelerated Senescence in Vascular Endothelial Cells

Background: Eicosapentaenoic acid (EPA) is an omega-3 fatty acid that protects against cardiovascular diseases in patients with hypertriglyceridemia and may have pleotropic effects beyond lowering triglycerides. Many degenerative diseases, such as atherosclerosis and diabetes, are related to cellular senescence as a pathophysiological mechanism. We aimed to examine whether EPA could protect vascular endothelial cells under stress conditions against stress-induced accelerated senescence (SIAS). Methods: Cultured human umbilical vein endothelial cells (HUVECs) were exposed to H2O2 as oxidative stress and a high glucose concentration with palmitate as a glucolipotoxic condition. Changes in cell viability, apoptosis, lactate dehydrogenase release, and cell cycle analysis were measured by cell counting kit-8 assay, annexin V/ propidium iodide staining, and enzyme-linked immunosorbent assay, respectively. EPA was applied in stress conditions. The degree of senescence was measured by senescence-associated beta-galactosidase staining and p16 staining using immunofluorescence. Apoptosis and cellular senescence-related proteins were measured by Western blotting. Results: Cultured HUVECs under oxidative and glucolipotoxic stresses revealed accelerated senescence and increased apoptosis. These changes were markedly reversed by EPA administration, and the expressions of apoptosis and cellular senescence-related proteins were reversed by EPA treatment. Conclusion: EPA effectively protects HUVECs against SIAS, which may be one of its pleotrophic effects.

m 6A methylation in cellular senescence of age-associated diseases

Cellular senescence is a state of irreversible cellular growth arrest that occurs in response to various stresses. In addition to exiting the cell cycle, senescent cells undergo many phenotypic alterations, including metabolic reprogramming, chromatin rearrangement, and senescence-associated secretory phenotype (SASP) development. Furthermore, senescent cells can affect most physiological and pathological processes, such as physiological development; tissue homeostasis; tumour regression; and age-associated disease progression, including diabetes, atherosclerosis, Alzheimer's disease, and hypertension. Although corresponding anti-senescence therapies are actively being explored for the treatment of age-associated diseases, the specific regulatory mechanisms of senescence remain unclear. N 6-methyladenosine (m 6A), a chemical modification commonly distributed in eukaryotic RNA, plays an important role in biological processes such as translation, shearing, and RNA transcription. Numerous studies have shown that m 6A plays an important regulatory role in cellular senescence and aging-related disease. In this review, we systematically summarize the role of m 6A modifications in cellular senescence with regard to oxidative stress, DNA damage, telomere alterations, and SASP development. Additionally, diabetes, atherosclerosis, and Alzheimer's disease regulation via m 6A-mediated cellular senescence is discussed. We further discuss the challenges and prospects of m 6A in cellular senescence and age-associated diseases with the aim of providing rational strategies for the treatment of these age-associated diseases.

Exploring the Communication of the SASP: Dynamic, Interactive, and Adaptive Effects on the Microenvironment

Cellular senescence is a complex cell state that can occur during physiological ageing or after exposure to stress signals, regardless of age. It is a dynamic process that continuously evolves in a context-dependent manner. Senescent cells interact with their microenvironment by producing a heterogenous and plastic secretome referred to as the senescence-associated secretory phenotype (SASP). Hence, understanding the cross-talk between SASP and the microenvironment can be challenging due to the complexity of signal exchanges. In this review, we first aim to update the definition of senescence and its associated biomarkers from its discovery to the present day. We detail the regulatory mechanisms involved in the expression of SASP at multiple levels and develop how SASP can orchestrate microenvironment modifications, by focusing on extracellular matrix modifications, neighboring cells' fate, and intercellular communications. We present hypotheses on how these microenvironmental events may affect dynamic changes in SASP composition in return. Finally, we discuss the various existing approaches to targeting SASP and clarify what is currently known about the biological effects of these modified SASPs on the cellular environment.

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.

Cellular senescence in aging: Molecular basis, implications and therapeutic interventions

Cellular senescence is an irreversible proliferation arrest in response to cellular damage and stress. Although cellular senescence is a highly stable cell cycle arrest, it can influence many physiological, pathological, and aging processes. Cellular senescence can be triggered by various intrinsic and extrinsic stimuli such as oxidative stress, mitochondrial dysfunction, genotoxic stress, oncogenic activation, irradiation and chemotherapeutic agents. Senescence is associated with several molecular and phenotypic alterations, such as senescence-associated secretory phenotype (SASP), cell cycle arrest, DNA damage response (DDR), senescence-associated β-galactosidase, morphogenesis, and chromatin remodeling. Cellular senescence is a regular physiological event involved in tissue homeostasis, embryonic development, tissue remodeling, wound healing, and inhibition of tumor progression. Mitochondria are one of the organelles that undergo significant morphological and metabolic changes associated with senescence. Recent evidence unraveled that inter-organelle communication regulates cellular senescence, where mitochondria form a highly complex and dynamic network throughout the cytoplasm with other organelles, like the endoplasmic reticulum. An imbalance in organelle interactions may result in faulty cellular homeostasis, which contributes to cellular senescence and is associated with organ aging. Since mitochondrial dysfunction is a common characteristic of cellular senescence and age-related diseases, mitochondria-targeted senolytic or redox modulator senomorphic strategies help solve the complex problems with the detrimental consequences of cellular senescence. Understanding the regulation of mitochondrial metabolism would provide knowledge on effective therapeutic interventions for aging and age-related pathologies. This chapter focuses on the biochemical and molecular mechanisms of senescence and targeting senescence as a potential strategy to alleviate age-related pathologies and support healthy aging.

Exercise protects vascular function by countering senescent cells in older adults

Blood vessels are key conduits for the transport of blood and circulating factors. Abnormalities in blood vessels promote cardiovascular disease (CVD), which has become the most common disease as human lifespans extend. Aging itself is not pathogenic; however, the decline of physiological and biological function owing to aging has been linked to CVD. Although aging is a complex phenomenon that has not been comprehensively investigated, there is accumulating evidence that cellular senescence aggravates various pathological changes associated with aging. Emerging evidence shows that approaches that suppress or eliminate cellular senescence preserve vascular function in aging-related CVD. However, most pharmacological therapies for treating age-related CVD are inefficient. Therefore, effective approaches to treat CVD are urgently required. The benefits of exercise for the cardiovascular system have been well documented in basic research and clinical studies; however, the mechanisms and optimal frequency of exercise for promoting cardiovascular health remain unknown. Accordingly, in this review, we have discussed the changes in senescent endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) that occur in the progress of CVD and the roles of physical activity in CVD prevention and treatment.

RRP Regulates Autophagy through the AMPK Pathway to Alleviate the Effect of Cell Senescence on Atherosclerosis

Autophagy is closely associated with atherosclerosis and other cardiovascular diseases (CVD). Compound Danshen prescription is widely used as a clinical antiatherosclerotic drug. In our previous studies, we have shown that the combined active component, ginsenoside Rg1-notoginsenoside R1-protocatechualdehyde (RRP), can effectively alleviate endothelial dysfunction and reduce atherosclerotic plaques. However, the association between cellular senescence, caused by reduced autophagy, and atherosclerosis remains unclear. In this study, we investigated whether RRP can enhance autophagy and alleviate cell senescence through the AMPK pathway. Our results showed that RRP reduced the secretion of inflammatory factors in the serum of atherosclerotic mice, enhanced autophagy, and alleviated aortic aging in mice, thus reducing atherosclerotic plaques. In human aortic endothelial cells (HAECs), RRP effectively enhanced autophagy and inhibited senescence by activating the AMPK pathway. When AMPKα was silenced, the effect of RRP was inhibited, thus reversing its antiaging effect. Overall, our results show that RRP regulates autophagy through the AMPK pathway, thereby inhibiting cell senescence and alleviating the progression of atherosclerosis, suggesting that RRP may be a potential candidate drug for the treatment of atherosclerosis.

Recent Advances in Strategies for Imaging Detection and Intervention of Cellular Senescence

Cellular senescence is a stable cell cycle arrest state that can be triggered by a wide range of intrinsic or extrinsic stresses. Increased burden of senescent cells in various tissues is thought to contribute to aging and age-related diseases. Thus, the detection and interventions of senescent cells are critical for longevity and treatment of disease. However, the highly heterogeneous feature of senescence makes it challenging for precise detection and selective clearance of senescent cells in different age-related diseases. To address this issue, considerable efforts have been devoted to developing senescence-targeting molecular theranostic strategies, based on the potential biomarkers of cellular senescence. Herein, we review recent advances in the field of anti-senescence research and highlight the specific visualization and elimination of senescent cells. Additionally, the challenges in this emerging field are outlined.

PPARγ (Peroxisome Proliferator-Activated Receptor γ) Deacetylation Suppresses Aging-Associated Atherosclerosis and Hypercholesterolemia

BACKGROUND

Atherosclerosis is a medical urgency manifesting at the onset of hypercholesterolemia and is associated with aging. Activation of PPARγ (peroxisome proliferator-activated receptor γ) counteracts metabolic dysfunction influenced by aging, and its deacetylation displays an atheroprotective property. Despite the marked increase of PPARγ acetylation during aging, it is unknown whether PPARγ acetylation is a pathogenic contributor to aging-associated atherosclerosis.

METHODS

Mice with constitutive deacetylation-mimetic PPARγ mutations on lysine residues K268 and K293 (2KR) in an LDL (low-density lipoprotein)-receptor knockout (Ldlr-/-) background (2KR:Ldlr-/-) were aged for 18 months on a standard laboratory diet to examine the cardiometabolic phenotype, which was confirmed in Western-type diet-fed 2KR:Ldlr+/- mice. Whole-liver RNA-sequencing and in vitro studies in bone marrow-derived macrophages were conducted to decipher the mechanism.

RESULTS

In contrast to severe atherosclerosis in WT:Ldlr-/- mice, aged 2KR:Ldlr-/- mice developed little to no plaque, which was underlain by a significantly improved plasma lipid profile, with particular reductions in circulating LDL. The protection from hypercholesterolemia was recapitulated in Western-type diet-fed 2KR:Ldlr+/- mice. Liver RNA-sequencing analysis revealed suppression of liver inflammation rather than changes in cholesterol metabolism. This anti-inflammatory effect of 2KR was attributed to polarized M2 activation of macrophages. Additionally, the upregulation of core circadian component Bmal1 (brain and muscle ARNT-like 1), perceived to be involved in anti-inflammatory immunity, was observed in the liver and bone marrow-derived macrophages.

CONCLUSIONS

PPARγ deacetylation in mice prevents the development of aging-associated atherosclerosis and hypercholesterolemia, in association with the anti-inflammatory phenotype of 2KR macrophages.

NF-kB in Signaling Patterns and Its Temporal Dynamics Encode/Decode Human Diseases

Defects in signaling pathways are the root cause of many disorders. These malformations come in a wide variety of types, and their causes are also very diverse. Some of these flaws can be brought on by pathogenic organisms and viruses, many of which can obstruct signaling processes. Other illnesses are linked to malfunctions in the way that cell signaling pathways work. When thinking about how errors in signaling pathways might cause disease, the idea of signalosome remodeling is helpful. The signalosome may be conveniently divided into two types of defects: phenotypic remodeling and genotypic remodeling. The majority of significant illnesses that affect people, including high blood pressure, heart disease, diabetes, and many types of mental illness, appear to be caused by minute phenotypic changes in signaling pathways. Such phenotypic remodeling modifies cell behavior and subverts normal cellular processes, resulting in illness. There has not been much progress in creating efficient therapies since it has been challenging to definitively confirm this connection between signalosome remodeling and illness. The considerable redundancy included into cell signaling systems presents several potential for developing novel treatments for various disease conditions. One of the most important pathways, NF-κB, controls several aspects of innate and adaptive immune responses, is a key modulator of inflammatory reactions, and has been widely studied both from experimental and theoretical perspectives. NF-κB contributes to the control of inflammasomes and stimulates the expression of a number of pro-inflammatory genes, including those that produce cytokines and chemokines. Additionally, NF-κB is essential for controlling innate immune cells and inflammatory T cells' survival, activation, and differentiation. As a result, aberrant NF-κB activation plays a role in the pathogenesis of several inflammatory illnesses. The activation and function of NF-κB in relation to inflammatory illnesses was covered here, and the advancement of treatment approaches based on NF-κB inhibition will be highlighted. This review presents the temporal behavior of NF-κB and its potential relevance in different human diseases which will be helpful not only for theoretical but also for experimental perspectives.

Targeting Immune Senescence in Atherosclerosis

Atherosclerosis is one of the main underlying causes of cardiovascular diseases (CVD). It is associated with chronic inflammation and intimal thickening as well as the involvement of multiple cell types including immune cells. The engagement of innate or adaptive immune response has either athero-protective or atherogenic properties in exacerbating or alleviating atherosclerosis. In atherosclerosis, the mechanism of action of immune cells, particularly monocytes, macrophages, dendritic cells, and B- and T-lymphocytes have been discussed. Immuno-senescence is associated with aging, viral infections, genetic predispositions, and hyperlipidemia, which contribute to atherosclerosis. Immune senescent cells secrete SASP that delays or accelerates atherosclerosis plaque growth and associated pathologies such as aneurysms and coronary artery disease. Senescent cells undergo cell cycle arrest, morphological changes, and phenotypic changes in terms of their abundances and secretome profile including cytokines, chemokines, matrix metalloproteases (MMPs) and Toll-like receptors (TLRs) expressions. The senescence markers are used in therapeutics and currently, senolytics represent one of the emerging treatments where specific targets and clearance of senescent cells are being considered as therapy targets for the prevention or treatment of atherosclerosis.

Oxygen–Glucose Deprivation Promoted Fibroblast Senescence and Collagen Expression via IL11

Cell senescence is one of the most important forms of injury induced by cardiovascular and other ischemic diseases. Fibroblasts are important participants in tissue repair after ischemic injury and the main source of IL11 secretion. However, the roles of oxygen–glucose deprivation (OGD) and IL11 in promoting fibroblast senescence and their regulatory mechanisms remain unclear. This study selected the NIH3T3 and L929 fibroblast cell lines as research objects. We found that OGD could induce the expression of p53, P16, p21, and collagen in fibroblasts. In the condition of OGD, when IL11 intervened, fibroblasts’ senescence and collagen expression were changed. Some studies have found that changes in kynurenine (KYN) metabolism are related to aging diseases, and indoleamine 2,3-dioxygenase 1 (IDO1) is a key rate-limiting enzyme in the KYN metabolic pathway. We found that KYN secretion decreased after OGD increased fibroblast senescence, and inhibition of IL11 promoted IDO1 and increased KYN secretion. These results suggest that OGD may promote fibroblast senescence and collagen expression via IL11 inhibition of the IDO1/KYN metabolic pathway. Therefore, the revealed mechanism of OGD-promoted fibroblast senescence could provide an effective theoretical basis for the clinical treatment of aging-related ischemic diseases.

AT2 Receptor Stimulation Inhibits Vascular Smooth Muscle Cell Senescence Induced by Angiotensin II and Hyperglycemia

BACKGROUND

Hyperglycemia has been widely reported to induce vascular senescence. We have previously demonstrated that angiotensin II (Ang II) could promote brain vascular smooth muscle cell (VSMC) senescence, and its type 2 (AT2) receptor deletion could enhance VSMC senescence. Therefore, we examined the possible cross-talk between Ang II and hyperglycemia on VSMC senescence, and the roles of AT2 receptor agonist, compound 21 (C21) on it.

METHODS

Aortic VSMCs were prepared from adult male mice and stimulated with Ang II and/or high glucose (Glu) and/or C21 and/or an autophagy inhibitor, 3-methyladenine (3-MA), and/or an autophagy agonist, rapamycin (RAP) for the indicated times. Cellular senescence, oxidative stress, and protein expressions were evaluated.

RESULTS

Combination treatment with Ang II and Glu synergistically increased the proportion of VSMC senescent area compared with control group and each treatment alone, which was almost completely attenuated by C21 treatment. Moreover, combination treatment induced significant changes in the levels of superoxide anion, the expressions of p21 and pRb, and the ratio of LC3B II/I expression, which were also significantly attenuated by C21 treatment. The proportion of VSMC senescent area and the levels of superoxide anion by combination treatment were increased after 3-MA treatment, and the proportion of senescent area and the expressions of p21 and pRb were decreased after RAP treatment, both of which were further attenuated by C21 treatment.

CONCLUSIONS

Ang II and hyperglycemia synergistically promoted VSMC senescence, at least partly through the participation by autophagy, oxidative stress, and p21-pRb pathway, which could be inhibited by C21.

Mechanism of Yangxin Tongmai Decoction in the Treatment of Coronary Heart Disease with Blood Stasis Syndrome Based on Network Pharmacology and Molecular Docking

This study aimed to explore the mechanism of Yangxin Tongmai decoction (YXTMD) in the treatment of coronary heart disease (CHD) with blood stasis syndrome (BSS) using network pharmacology and molecular docking, and to verify these results through clinical trials. The active compounds of YXTMD were identified using the Traditional Chinese Medicine Systems Pharmacology database, and the targets of the active compounds were predicted using the SwissTarget Prediction database. The targets of CHD and BSS were predicted using the GeneCards, OMIM, PharmGKB, TTD, and DrugBank databases. The common targets of “herb-disease-phenotype” were obtained using a Venn diagram, then used Cytoscape software 3.8.2 and its plug-in CytoNCA and STRING database to construct the “herb active compounds-common target” and protein–protein interaction networks. R language software and bioconductor plug-in were used for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. AutoDock was used for the molecular docking analysis. Finally, clinical trials were conducted to confirm the results of network pharmacology. Eighty-three active components were obtained, and the core active components were 5,7,4′-trimethoxyflavone, tetramethoxyluteolin, isosinensetin, sinensetin, and 5,7-dihydroxy-2-(3-hydroxy-4-methoxyphenyl)chroman-4-one. A total of 140 common targets were identified, and the core targets were EGFR, VEGFA, AKT1, STAT3, TP53, ERBB2, and PIK3CA. Biological processes identified by the GO analysis primarily involved wound healing, regulation of body fluid levels, and vascular process in circulatory system. The cellular components were primarily located in the membrane raft, membrane microdomain, and plasma membrane raft. The primary molecular functions were activity of transmembrane receptor protein kinase, transmembrane receptor protein tyrosine kinase, and protein tyrosine kinase. KEGG analysis showed that the PI3K-Akt signaling pathway was closely related to the treatment of CHD with BSS by YXTMD. Molecular docking results showed that the core active components had a good binding activity with the core targets. The clinical trial results showed that YXTMD improved the BSS scores and decreased the serum levels of total cholesterol and low-density lipoprotein cholesterol. Moreover, the levels of PI3k and AKt mRNA were upregulated and the levels of GSK-3β mRNA were downregulated. YXTMD has multicomponent, multitarget, and multipathway effects in the treatment of CHD with BSS, and its mechanism of action may involve activation of the PI3K-AKt signaling pathway, downregulation of GSK-3β, and mediation of in vivo lipid metabolism-based metabolic processes.

Theories and Molecular Basis of Vascular Aging: A Review of the Literature from VascAgeNet Group on Pathophysiological Mechanisms of Vascular Aging

Vascular aging, characterized by structural and functional alterations of the vascular wall, is a hallmark of aging and is tightly related to the development of cardiovascular mortality and age-associated vascular pathologies. Over the last years, extensive and ongoing research has highlighted several sophisticated molecular mechanisms that are involved in the pathophysiology of vascular aging. A more thorough understanding of these mechanisms could help to provide a new insight into the complex biology of this non-reversible vascular process and direct future interventions to improve longevity. In this review, we discuss the role of the most important molecular pathways involved in vascular ageing including oxidative stress, vascular inflammation, extracellular matrix metalloproteinases activity, epigenetic regulation, telomere shortening, senescence and autophagy.

ER-Stress and Senescence Coordinately Promote Endothelial Barrier Dysfunction in Diabetes-Induced Atherosclerosis

Diabetes mellitus is hallmarked by accelerated atherosclerosis, a major cause of mortality among patients with diabetes. Efficient therapies for diabetes-associated atherosclerosis are absent. Accelerated atherosclerosis in diabetic patients is associated with reduced endothelial thrombomodulin (TM) expression and impaired activated protein C (aPC) generation. Here, we directly compared the effects of high glucose and oxidized LDL, revealing that high glucose induced more pronounced responses in regard to maladaptive unfolded protein response (UPR), senescence, and vascular endothelial cell barrier disruption. Ex vivo, diabetic ApoE−/− mice displayed increased levels of senescence and UPR markers within atherosclerotic lesions compared with nondiabetic ApoE−/− mice. Activated protein C pretreatment maintained barrier permeability and prevented glucose-induced expression of senescence and UPR markers in vitro. These data suggest that high glucose-induced maladaptive UPR and associated senescence promote vascular endothelial cell dysfunction, which—however—can be reversed by aPC. Taken together, current data suggest that reversal of glucose-induced vascular endothelial cell dysfunction is feasible.

EA.hy926 Cells and HUVECs Share Similar Senescence Phenotypes but Respond Differently to the Senolytic Drug ABT-263

Doxorubicin (DOX) induces endothelial cell (EC) senescence, which contributes to endothelial dysfunction and cardiovascular complications. Senolytic drugs selectively eliminate senescent cells to ameliorate senescence-mediated pathologies. Previous studies have demonstrated differences between immortalized and primary EC models in some characteristics. However, the response of DOX-induced senescent ECs to senolytics has not been determined across these two models. In the present work, we first established a comparative characterization of DOX-induced senescence phenotypes in immortalized EA.hy926 endothelial-derived cells and primary human umbilical vein EC (HUVECs). Thereafter, we evaluated the senolytic activity of four senolytics across both ECs. Following the DOX treatment, both EA.hy926 and HUVECs shared similar senescence phenotypes characterized by upregulated senescence markers, increased SA-β-gal activity, cell cycle arrest, and elevated expression of the senescence-associated secretory phenotype (SASP). The potentially senolytic drugs dasatinib, quercetin, and fisetin demonstrated a lack of selectivity against DOX-induced senescent EA.hy926 cells and HUVECs. However, ABT-263 (Navitoclax) selectively induced the apoptosis of DOX-induced senescent HUVECs but not EA.hy926 cells. Mechanistically, DOX-treated EA.hy926 cells and HUVECs demonstrated differential expression levels of the BCL-2 family proteins. In conclusion, both EA.hy926 cells and HUVECs demonstrate similar DOX-induced senescence phenotypes but they respond differently to ABT-263, presumably due to the different expression levels of BCL-2 family proteins.

The multifaceted role of the SASP in atherosclerosis: from mechanisms to therapeutic opportunities

BACKGROUND

The global population of older individuals is growing, and ageing is a key risk factor for atherosclerotic cardiovascular diseases. Abnormal accumulation of senescent cells can cause potentially deleterious effects on the organism with age. As a vital marker of cellular senescence, the senescence-associated secretory phenotype (SASP) is a novel mechanism to link cellular senescence with atherosclerosis.

MAIN BODY

In this review, we concretely describe the characteristics of the SASP and its regulation mechanisms. Importantly, we provide novel perspectives on how the SASP can promote atherosclerosis. The SASP from different types of senescent cells have vital roles in atherosclerosis progression. As a significant mediator of the harmful effects of senescent cells, it can play a pro-atherogenic role by producing inflammation and immune dysfunction. Furthermore, the SASP can deliver senescence signals to the surrounding vascular cells, gradually contributing to the development of atherosclerosis. Finally, we focus on a variety of novel therapeutic strategies aimed to reduce the burden of atherosclerosis in elderly individuals by targeting senescent cells and inhibiting the regulatory mechanisms of the SASP.

CONCLUSION

This review systematically summarizes the multiple roles of the SASP in atherosclerosis and can contribute to the exploration of new therapeutic opportunities.

Evaluation of aortic biomechanics in patients with aortic disease via imaging: A review

As a bridge between the heart and the arteries, the aorta plays an important role in the cardiovascular system. The morbidity and mortality of aortic disease are extremely high, which is a serious threat to human life. The biomechanical abnormality of the aorta is an important factor of a series of pathological changes in the aortic wall. At present, there are many imaging methods to evaluate the biomechanics of the aorta, which will benefit to the early diagnosis and treatment of aortic disease. In this review, we describe the application of various imaging methods and parameters in aortic disease.

Activating PGC-1α-mediated signaling cascades in the aorta contributes to the amelioration of vascular senescence and atherosclerosis by 2,3,4',5-tetrahydroxystilbene-2-O-β-d-glycoside

BACKGROUND

2,3,4',5-tetrahydroxystilbene-2-O-β-d-glycoside (TSG), the main active polyphenolic component of Polygonum multiflorum, possesses many pharmacological activities. Its anti-aging effect influences a variety of tissues with diverse mechanisms. However, the effectiveness and exact mechanisms of TSG against vascular senescence in atherosclerosis remain unclear. The present study is aimed to investigate the effects of TSG against vascular senescence in atherosclerosis both in vivo and in vitro, and the possible underlying mechanisms focusing on aortic peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α)-mediated signaling cascades which have never been studied.

METHODS

In vivo, 12-mo-old male LDLr-/- mice were randomly separated into control, high-fat diet (HFD), and TSG -treatment groups. At the end of the 12 weeks, the blood samples and aorta tissues of mice were collected for further analysis. In vitro, to mimic the condition of endothelial senescence in hyperlipidemic mice, human aortic endothelial cells (HAECs) were incubated with oxidized low-density lipoprotein (ox-LDL) to induce senescence.

RESULTS

TSG administration improved lipid profiles, ameliorated HFD-exacerbated vascular senescence and atherosclerosis. The protective effect of TSG via inhibiting telomere malfunction, oxidative stress, and mitochondrial damage was found both in vivo and in vitro. Notably, TSG administration increased aortic PGC-1α mRNA and protein expression along with the regulation of its targeted genes TERT, NRF1, TFAM, Mn-SOD, and catalase. Further, by using PGC-1α siRNA in ox-LDL-treated HAECs, it is proved that TSG reduced endothelial senescence, telomere malfunction, oxidative stress, and mitochondrial damage at least partly through activating the PGC-1α pathway.

CONCLUSIONS

These results provide new evidence for TSG in the treatment of atherosclerosis and the activation of aortic PGC-1α is involved in its beneficial effects.

Dendrobine modulates autophagy to alleviate ox-LDL-induced oxidative stress and senescence in HUVECs

Dendrobine has potential advantages in suppressing atherosclerosis (AS). FK506-binding protein 1A (FKBP1A) is implicated in the regulation of autophagy, inflammation, and apoptosis. To reveal the mechanism by which dendrobine inhibits AS by modulating autophagy, oxidative stress, apoptosis, and senescence. An in vitro AS cell model was induced by culturing human umbilical vein endothelial cells (HUVECs) with oxidized low-density lipoprotein (ox-LDL). The cells were treated with dendrobine alone or in combination with short hairpin RNA (shRNA) targeting FKBP1A or together with 3-methyladenine (3MA), an autophagy inhibitor. Inflammatory cytokines levels tumor necrosis factor-α, interleukin-6 (IL-6), and IL-1β were analyzed and oxidative stress levels were detected by the analysis of reactive oxygen species, malondialdehyde, and superoxide dismutase levels, followed by the analysis of apoptosis levels through terminal deoxynucleotidyl transferase dUTP nick end labeling staining. Cell senescence was evaluated by senescence-associated β-galactosidase and light chain 3 (LC3) levels were detected by immunofluorescence (IF) staining. The targeting relationship of dendrobine and FKBP1A was predicted by SwissTarget, PyMol, Autodock, and Open Babel software. Dendrobine reduced the levels of proinflammation factors, oxidative stress levels, apoptosis levels, and senescence phenotype in ox-LDL-induced HUVECs. Besides, cell viability has an opposite change. Furthermore, there was an increase in LC3 IF tensity, and LC3-II/I and Beclin1 expressions, and a decrease in p62 expression. However, these effects of dendrobine could be markedly destroyed by shRNA silencing FKBP1A and 3MA. Dendrobine can suppress inflammatory responses, oxidative stress, apoptosis, and senescence via FKBP1A-involved autophagy ox-LDL-treated HUVECs.

The Role of Peroxisome Proliferator-Activated Receptor Gamma and Atherosclerosis: Post-translational Modification and Selective Modulators

Atherosclerosis is the hallmark of cardiovascular disease (CVD) which is a leading cause of death in type 2 diabetes patients, and glycemic control is not beneficial in reducing the potential risk of CVD. Clinically, it was shown that Thiazolidinediones (TZDs), a class of peroxisome proliferator-activated receptor gamma (PPARγ) agonists, are insulin sensitizers with reducing risk of CVD, while the potential adverse effects, such as weight gain, fluid retention, bone loss, and cardiovascular risk, restricts its use in diabetic treatment. PPARγ, a ligand-activated nuclear receptor, has shown to play a crucial role in anti-atherosclerosis by promoting cholesterol efflux, repressing monocytes infiltrating into the vascular intima under endothelial layer, their transformation into macrophages, and inhibiting vascular smooth muscle cells proliferation as well as migration. The selective activation of subsets of PPARγ targets, such as through PPARγ post-translational modification, is thought to improve the safety profile of PPARγ agonists. Here, this review focuses on the significance of PPARγ activity regulation (selective activation and post-translational modification) in the occurrence, development and treatment of atherosclerosis, and further clarifies the value of PPARγ as a safe therapeutic target for anti-atherosclerosis especially in diabetic treatment.

Advances in relationship between cell senescence and atherosclerosis

Cellular senescence is a biological process associated with the degeneration of cell structure and function, which contribute to age-related diseases. Atherosclerosis is a chronic inflammatory disease that can cause a variety of cardiovascular disorders. In this article, we review the effects of cellular senescence on the development of atherosclerosis through diverse physiopathological changes, focusing on the alterations in senescent organelles and the increased senescence-associated secretory phenotype (SASP), and exploring the relevant therapeutic strategies for atherosclerosis by clearing senescent cells and reducing SASP, to provide new insights for the treatment of atherosclerosis.

Age as a risk factor in vasculitis

Two vasculitides, giant cell arteritis (GCA) and Takayasu arteritis (TAK), are recognized as autoimmune and autoinflammatory diseases that manifest exclusively within the aorta and its large branches. In both entities, the age of the affected host is a critical risk factor. TAK manifests during the 2nd-4th decade of life, occurring while the immune system is at its height of performance. GCA is a disease of older individuals, with infrequent cases during the 6th decade and peak incidence during the 8th decade of life. In both vasculitides, macrophages and T cells infiltrate into the adventitia and media of affected vessels, induce granulomatous inflammation, cause vessel wall destruction, and reprogram vascular cells to drive adventitial and neointimal expansion. In GCA, abnormal immunity originates in an aged immune system and evolves within the aged vascular microenvironment. One hallmark of the aging immune system is the preferential loss of CD8⁺ T cell function. Accordingly, in GCA but not in TAK, CD8⁺ effector T cells play a negligible role and anti-inflammatory CD8⁺ T regulatory cells are selectively impaired. Here, we review current evidence of how the process of immunosenescence impacts the risk for GCA and how fundamental differences in the age of the immune system translate into differences in the granulomatous immunopathology of TAK versus GCA.

Exploring New Kingdoms: The Role of Extracellular Vesicles in Oxi-Inflamm-Aging Related to Cardiorenal Syndrome

The incidence of age associated chronic diseases has increased in recent years. Although several diverse causes produce these phenomena, abundant evidence shows that oxidative stress plays a central role. In recent years, numerous studies have focused on elucidating the role of oxidative stress in the development and progression of both aging and chronic diseases, opening the door to the discovery of new underlying mechanisms and signaling pathways. Among them, senolytics and senomorphics, and extracellular vesicles offer new therapeutic strategies to slow the development of aging and its associated chronic diseases by decreasing oxidative stress. In this review, we aim to discuss the role of extracellular vesicles in human cardiorenal syndrome development and their possible role as biomarkers, targets, or vehicles of drugs to treat this syndrome.

Enhancement of Bone-Forming Ability on Beta-Tricalcium Phosphate by Modulating Cellular Senescence Mechanisms Using Senolytics

Various stresses latently induce cellular senescence that occasionally deteriorates the functioning of surrounding tissues. Nevertheless, little is known about the appearance and function of senescent cells, caused by the implantation of beta-tricalcium phosphate (β-TCP)—used widely in dentistry and orthopedics for treating bone diseases. In this study, two varying sizes of β-TCP granules (<300 μm and 300–500 μm) were implanted, and using histological and immunofluorescent staining, appearances of senescent-like cells in critical-sized bone defects in the calvaria of Sprague Dawley rats were evaluated. Parallelly, bone formation in defects was investigated with or without the oral administration of senolytics (a cocktail of dasatinib and quercetin). A week after the implantation, the number of senescence-associated beta-galactosidase, p21-, p19-, and tartrate-resistant acid phosphatase-positive cells increased and then decreased upon administrating senolytics. This administration of senolytics also attenuated 4-hydroxy-2-nonenal staining, representing reactive oxygen species. Combining senolytic administration with β-TCP implantation significantly enhanced the bone formation in defects as revealed by micro-computed tomography analysis and hematoxylin-eosin staining. This study demonstrates that β-TCP granules latently induce senescent-like cells, and senolytic administration may improve the bone-forming ability of β-TCP by inhibiting senescence-associated mechanisms.

Septic shock as a trigger of arterial stress-induced premature senescence: A new pathway involved in the post sepsis long-term cardiovascular complications

BACKGROUND

Major adverse cardiovascular events among sepsis survivors is an emerging health issue. Because endothelial senescence leads to vascular dysfunction and atherothrombosis, sepsis could be associated to vascular stress-induced premature senescence and thus with long-term cardiovascular events.

MATERIALS & METHODS

Adult Wistar male rats were submitted to cecal ligation and puncture, or a SHAM operation. Markers of inflammation, oxidative stress and endothelial senescence were assessed at 3, 7 and 90 days (D), and vascular reactivity was assessed in conductance and resistance vessels at D90. Expression of proteins involved in senescence and inflammation was assessed by Western blot analysis and confocal microscopy, oxidative stress by dihydroethidium probing.

RESULTS

Pro-inflammatory endothelial ICAM-1 and VCAM-1 were up-regulated by three-fold in CLP vs. SHAM at D7 and remained elevated at D90. Oxidative stress followed a similar pattern but was detected in the whole vascular wall. Sepsis accelerated premature senescence in aorta vascular tissue as shown by the significant up-regulation of p53 and down-stream p21 and p16 senescent markers at D7, values peaking at D90 whereas the absence of significant variation in activated caspase-3 confirmed p53 as a prime inducer of senescence. In addition, p53 was mainly expressed in the endothelium. Sepsis-induced long-term vascular dysfunction was confirmed in aorta and main mesenteric artery, with a major alteration of the endothelial-dependent nitric oxide pathway.

CONCLUSIONS

Septic shock-induced long-term vascular dysfunction is associated with endothelial and vascular senescence. Our model could prove useful for investigating senotherapies aiming at reducing long-term cardiovascular consequences of septic shock.

Association of physical activity and nutrition with telomere length, a marker of cellular aging: A comprehensive review

The aging of the population has great social and economic effects because it is characterized by a gradual loss in physiological integrity, resulting in functional decline, thereby loss of ability to move independently. Telomeres, the hallmarks of biological aging, play a protective role in both cell death and aging. Critically short telomeres give rise to a metabolically active cell that is unable to repair damage or divide, thereby leading to aging. Lifestyle factors such as physical activity (PA) and nutrition could be associated with telomere length (TL). Indeed, regular PA and healthy nutrition as integral parts of our lifestyle can slow down telomere shortening, thereby delaying aging. In this context, the present comprehensive review summarizes the data from recent literature on the association of PA and nutrition with TL.

A Systematic Review and Meta-Analysis of the Impact of Different Intensity of Dietary Counselling on Cardiometabolic Health in Middle-Aged and Older Adults

Dietary counselling has been identified as one of the nutritional strategies to alleviate cardiometabolic health conditions. Its effectiveness however may vary due to factors such as intensity level and provider while this has not been comprehensively studied. This systematic review and meta-analysis aimed to assess the effects of dietary counselling on the cardiometabolic health in middle-aged and older adults and the sub-group analyses with dietary counselling intensity and the provider were also assessed. Four databases including PubMed, CINAHL Plus with Full Text, Cochrane Library and EMBASE were systematically searched. Data from 22 randomised controlled trials (RCTs) were compiled and those from 9 RCTs were utilised for meta-analysis. Dietary counselling lowered total cholesterol (TC) and fasting blood sugar (FBS) but had no impact on triglycerides (TG) and low-density lipoprotein (LDL). Sub-group analysis revealed significant lowering effect of high intensity dietary counselling for TG (weighted mean difference (WMD): −0.24 mmol/L, 95% confidence intervals (CIs): −0.40 to −0.09), TC (WMD: −0.31 mmol/L, 95% CIs: −0.49 to −0.13), LDL (WMD: −0.39 mmol/L, 95% CIs: −0.61 to −0.16) and FBS (WMD: −0.69 mmol/L, 95% CIs: −0.99 to −0.40) while medium or low intensity dietary counselling did not show favouring effects. Counselling provider showed differential responses on cardiometabolic health between dietitian and all other groups. The findings from this systematic review and meta-analysis suggest that dietary counselling is a beneficial dietary strategy to improve cardiometabolic health in middle-aged and older adults with the emphasis on the counselling intensity.

ClC-3: A Novel Promising Therapeutic Target for Atherosclerosis

Chloride channel 3 (ClC-3), a Cl^-/H⁺ antiporter, has been well established as a member of volume-regulated chloride channels (VRCCs). ClC-3 may be a crucial mediator for activating inflammation-associated signaling pathways by regulating protein phosphorylation. A growing number of studies have indicated that ClC-3 overexpression plays a crucial role in mediating increased plasma low-density lipoprotein levels, vascular endothelium dysfunction, pro-inflammatory activation of macrophages, hyper-proliferation and hyper-migration of vascular smooth muscle cells (VSMCs), as well as oxidative stress and foam cell formation, which are the main factors responsible for atherosclerotic plaque formation in the arterial wall. In the present review, we summarize the molecular structures and classical functions of ClC-3. We further discuss its emerging role in the atherosclerotic process. In conclusion, we explore the potential role of ClC-3 as a therapeutic target for atherosclerosis.

Cellular senescence in vascular wall mesenchymal stromal cells, a possible contribution to the development of aortic aneurysm

Cellular senescence is a hallmark of ageing and it plays a key role in the development of age-related diseases. Abdominal aortic aneurysm (AAA) is an age related degenerative vascular disorder, characterized by a progressive dilatation of the vascular wall and high risk of rupture over time. Nowadays, no pharmacological therapies are available and the understanding of the molecular mechanisms that lead to AAA onset and development are poorly defined. In this study we investigated the cellular features of senescence in vascular mesenchymal stromal cells, isolated from pathological (AAA - MSCs) and healthy (h - MSCs) segments of human abdominal aorta and their implication in impairing the vascular repair ability of MSCs. Cell proliferation, ROS production, cell surface area, the expression of cyclin dependent kinase inhibitors p21^CIP1 and p16^INK4a, the activation of the DNA damage response and a dysregulated autophagy showed a senescent state in AAA - MSCs compared to h-MSCs. Moreover, a reduced ability to differentiate toward endothelial cells was observed in AAA - MSCs. All these data suggest that the accumulation of senescent vascular MSCs over time impairs their remodeling ability during ageing. This condition could support the onset and development of AAA.

Effects of anagliptin on the stress induced accelerated senescence of human umbilical vein endothelial cells

Background

Dipeptidyl peptidase 4 (DPP-4) inhibitors have been used to treat type 2 diabetes mellitus (T2DM) via inhibition of the enzymatic activity of DPP-4 in degrading active circulating glucagon-like peptide-1. In addition to their glucose-lowering effect, DPP-4 inhibitors have pleiotropic effects. Cellular senescence regarded as important pathophysiological mechanism underlying many degenerative diseases, including atherosclerosis. This study was performed to examine whether the DPP-4 inhibitor, anagliptin, can directly protect against stress-induced accelerated senescence (SIAS) of vascular endothelial cells, regardless of changes in ambient glucose level.

Methods

Cultured human umbilical vein endothelial cells (HUVECs) were exposed to various concentrations of H₂O₂, and a fixed high concentration of glucose (25 mM) with varying concentrations of palmitate. Changes in cell viability, senescence-associated beta-galactosidase (SA-β-Gal), p16 protein, markers of endoplasmic reticulum (ER) stress, NOX4, NLRP inflammasome, lactate dehydrogenase (LDH) release and interleukin (IL) 1β levels were measured by Cell Counting Kit-8 assay, immunofluorescent staining, Western blotting, and enzyme-linked immunosorbent assay, respectively before and after application of anagliptin.

Results

The application of oxidative and glucolipotoxic stresses markedly increased the degree of SIAS of HUVECs, represented by increased SA-β-Gal immunopositivity and p16 protein expression. Aggravation of ER stress and inflammatory response were also observed through increased levels of ATF4, CHOP, peIF2α, NOX4, NLRP inflammasome, LDH, and IL1β. These changes were markedly reversed by the administration of anagliptin.

Conclusions

The DPP-4 inhibitor anagliptin effectively protects HUVECs against SIAS, suggesting its potential use in the development of new treatment strategies for aging.

Lysosome (Dys)function in Atherosclerosis-A Big Weight on the Shoulders of a Small Organelle

Atherosclerosis is a progressive insidious chronic disease that underlies most of the cardiovascular pathologies, including myocardial infarction and ischemic stroke. The malfunctioning of the lysosomal compartment has a central role in the etiology and pathogenesis of atherosclerosis. Lysosomes are the degradative organelles of mammalian cells and process endogenous and exogenous substrates in a very efficient manner. Dysfunction of these organelles and consequent inefficient degradation of modified low-density lipoproteins (LDL) and apoptotic cells in atherosclerotic lesions have, therefore, numerous deleterious consequences for cellular homeostasis and disease progression. Lysosome dysfunction has been mostly studied in the context of the inherited lysosomal storage disorders (LSDs). However, over the last years it has become increasingly evident that the consequences of this phenomenon are more far-reaching, also influencing the progression of multiple acquired human pathologies, such as neurodegenerative diseases, cancer, and cardiovascular diseases (CVDs). During the formation of atherosclerotic plaques, the lysosomal compartment of the various cells constituting the arterial wall is under severe stress, due to the tremendous amounts of lipoproteins being processed by these cells. The uncontrolled uptake of modified lipoproteins by arterial phagocytic cells, namely macrophages and vascular smooth muscle cells (VSMCs), is the initial step that triggers the pathogenic cascade culminating in the formation of atheroma. These cells become pathogenic "foam cells," which are characterized by dysfunctional lipid-laden lysosomes. Here, we summarize the current knowledge regarding the origin and impact of the malfunctioning of the lysosomal compartment in plaque cells. We further analyze how the field of LSD research may contribute with some insights to the study of CVDs, particularly how therapeutic approaches that target the lysosomes in LSDs could be applied to hamper atherosclerosis progression and associated mortality.

Cellular senescence in the aging retina and developments of senotherapies for age-related macular degeneration

Age-related macular degeneration (AMD), a degenerative disease in the central macula area of the neuroretina and the supporting retinal pigment epithelium, is the most common cause of vision loss in the elderly. Although advances have been made, treatment to prevent the progressive degeneration is lacking. Besides the association of innate immune pathway genes with AMD susceptibility, environmental stress- and cellular senescence-induced alterations in pathways such as metabolic functions and inflammatory responses are also implicated in the pathophysiology of AMD. Cellular senescence is an adaptive cell process in response to noxious stimuli in both mitotic and postmitotic cells, activated by tumor suppressor proteins and prosecuted via an inflammatory secretome. In addition to physiological roles in embryogenesis and tissue regeneration, cellular senescence is augmented with age and contributes to a variety of age-related chronic conditions. Accumulation of senescent cells accompanied by an impairment in the immune-mediated elimination mechanisms results in increased frequency of senescent cells, termed “chronic” senescence. Age-associated senescent cells exhibit abnormal metabolism, increased generation of reactive oxygen species, and a heightened senescence-associated secretory phenotype that nurture a proinflammatory milieu detrimental to neighboring cells. Senescent changes in various retinal and choroidal tissue cells including the retinal pigment epithelium, microglia, neurons, and endothelial cells, contemporaneous with systemic immune aging in both innate and adaptive cells, have emerged as important contributors to the onset and development of AMD. The repertoire of senotherapeutic strategies such as senolytics, senomorphics, cell cycle regulation, and restoring cell homeostasis targeted both at tissue and systemic levels is expanding with the potential to treat a spectrum of age-related diseases, including AMD.

Superoxide Dismutase 2 (SOD2) in Vascular Calcification: A Focus on Vascular Smooth Muscle Cells, Calcification Pathogenesis, and Therapeutic Strategies

Vascular calcification (VC) describes the pathophysiological phenotype of calcium apatite deposition within the vascular wall, leading to vascular stiffening and the loss of compliance. VC is never benign; the presence and severity of VC correlate closely with the risk of myocardial events and cardiovascular mortality in multiple at-risk populations such as patients with diabetes and chronic kidney disease. Mitochondrial dysfunction involving each of vascular wall constituents (endothelia and vascular smooth muscle cells (VSMCs)) aggravates various vascular pathologies, including atherosclerosis and VC. However, few studies address the pathogenic role of mitochondrial dysfunction during the course of VC, and mitochondrial reactive oxygen species (ROS) seem to lie in the pathophysiologic epicenter. Superoxide dismutase 2 (SOD2), through its preferential localization to the mitochondria, stands at the forefront against mitochondrial ROS in VSMCs and thus potentially modifies the probability of VC initiation or progression. In this review, we will provide a literature-based summary regarding the relationship between SOD2 and VC in the context of VSMCs. Apart from the conventional wisdom of attenuating mitochondrial ROS, SOD2 has been found to affect mitophagy and the formation of the autophagosome, suppress JAK/STAT as well as PI₃K/Akt signaling, and retard vascular senescence, all of which underlie the beneficial influences on VC exerted by SOD2. More importantly, we outline the therapeutic potential of a novel SOD2-targeted strategy for the treatment of VC, including an ever-expanding list of pharmaceuticals and natural compounds. It is expected that VSMC SOD2 will become an important druggable target for treating VC in the future.