Chronic senolytic treatment alleviates established vasomotor dysfunction in aged or atherosclerotic mice

Old blood from heterochronic parabionts accelerates vascular aging in young mice: transcriptomic signature of pathologic smooth muscle remodeling

Vascular aging has a central role in the pathogenesis of cardiovascular diseases contributing to increased mortality of older adults. There is increasing evidence that, in addition to the documented role of cell-autonomous mechanisms of aging, cell-nonautonomous mechanisms also play a critical role in the regulation of vascular aging processes. Our recent transcriptomic studies (Kiss T. et al. Geroscience. 2020;42(2):727-748) demonstrated that circulating anti-geronic factors from young blood promote vascular rejuvenation in aged mice. The present study was designed to expand upon the results of this study by testing the hypothesis that circulating pro-geronic factors also contribute to the genesis of vascular aging phenotypes. To test this hypothesis, through heterochronic parabiosis, we determined the extent to which shifts in the vascular transcriptome (RNA-seq) are modulated by the old systemic environment. We reanalyzed existing RNA-seq data, comparing the transcriptome in the aorta arch samples isolated from isochronic parabiont aged (20-month-old) C57BL/6 mice [A-(A); parabiosis for 8 weeks] and young isochronic parabiont (6-month-old) mice [Y-(Y)] and also assessing transcriptomic changes in the aortic arch in young (6-month-old) parabiont mice [Y-(A); heterochronic parabiosis for 8 weeks] induced by the presence of old blood derived from aged (20-month-old) parabionts. We identified 528 concordant genes whose expression levels differed in the aged phenotype and were shifted towards the aged phenotype by the presence of old blood in young Y-(A) animals. Among them, the expression of 221 concordant genes was unaffected by the presence of young blood in A-(Y) mice. GO enrichment analysis suggests that old blood-regulated genes may contribute to pathologic vascular remodeling. IPA Upstream Regulator analysis (performed to identify upstream transcriptional regulators that may contribute to the observed transcriptomic changes) suggests that the mechanism of action of pro-geronic factors present in old blood may include inhibition of pathways mediated by SRF (serum response factor), insulin-like growth factor-1 (IGF-1) and VEGF-A. In conclusion, relatively short-term exposure to old blood can accelerate vascular aging processes. Our findings provide additional evidence supporting the significant plasticity of vascular aging and the existence of circulating pro-geronic factors mediating pathological remodeling of the vascular smooth muscle cells and the extracellular matrix.

Advancements in nanomedicines for the detection and treatment of diabetic kidney disease

In the diabetic kidneys, morbidities such as accelerated ageing, hypertension and hyperglycaemia create a pro-inflammatory microenvironment characterised by extensive fibrogenesis. Radiological techniques are not yet optimised generating inconsistent and non-reproducible data. The gold standard procedure to assess renal fibrosis is kidney biopsy, followed by histopathological assessment. However, this method is risky, invasive, subjective and examines less than 0.01% of kidney tissue resulting in diagnostic errors. As such, less than 10% of patients undergo kidney biopsy, limiting the accuracy of the current diabetic kidney disease (DKD) staging method. Standard treatments suppress the renin-angiotensin system to control hypertension and use of pharmaceuticals aimed at controlling diabetes have shown promise but can cause hypoglycaemia, diuresis and malnutrition as a result of low caloric intake. New approaches to both diagnosis and treatment are required. Nanoparticles (NPs) are an attractive candidate for managing DKD due to their ability to act as theranostic tools that can carry drugs and enhance image contrast. NP-based point-of-care systems can provide physiological information previously considered unattainable and provide control over the rate and location of drug release. Here we discuss the use of nanotechnology in renal disease, its application to both the treatment and diagnosis of DKD. Finally, we propose a new method of NP-based DKD classification that overcomes the current systems limitations.

Orally-active, clinically-translatable senolytics restore α-Klotho in mice and humans

BACKGROUND

α-Klotho is a geroprotective protein that can attenuate or alleviate deleterious changes with ageing and disease. Declines in α-Klotho play a role in the pathophysiology of multiple diseases and age-related phenotypes. Pre-clinical evidence suggests that boosting α-Klotho holds therapeutic potential. However, readily clinically-translatable, practical strategies for increasing α-Klotho are not at hand. Here, we report that orally-active, clinically-translatable senolytics can increase α-Klotho in mice and humans.

METHODS

We examined α-Klotho expression in three different human primary cell types co-cultured with conditioned medium (CM) from senescent or non-senescent cells with or without neutralizing antibodies. We assessed α-Klotho expression in aged, obese, and senescent cell-transplanted mice treated with vehicle or senolytics. We assayed urinary α-Klotho in patients with idiopathic pulmonary fibrosis (IPF) who were treated with the senolytic drug combination, Dasatinib plus Quercetin (D+Q).

FINDINGS

We found exposure to the senescent cell secretome reduces α-Klotho in multiple nonsenescent human cell types. This was partially prevented by neutralizing antibodies against the senescence-associated secretory phenotype (SASP) factors, activin A and Interleukin 1α (IL-1α). Consistent with senescent cells' being a cause of decreased α-Klotho, transplanting senescent cells into younger mice reduced brain and urine α-Klotho. Selectively removing senescent cells genetically or pharmacologically increased α-Klotho in urine, kidney, and brain of mice with increased senescent cell burden, including naturally-aged, diet-induced obese (DIO), or senescent cell-transplanted mice. D+Q increased α-Klotho in urine of patients with IPF, a disease linked to cellular senescence.

INTERPRETATION

Senescent cells cause reduced α-Klotho, partially due to their production of activin A and IL-1α. Targeting senescent cells boosts α-Klotho in mice and humans. Thus, clearing senescent cells restores α-Klotho, potentially opening a novel, translationally-feasible avenue for developing orally-active small molecule, α-Klotho-enhancing clinical interventions. Furthermore, urinary α-Klotho may prove to be a useful test for following treatments in senolytic clinical trials.

FUNDING

This work was supported by National Institute of Health grants AG013925 (J.L.K.), AG062413 (J.L.K., S.K.), AG044271 (N.M.), AG013319 (N.M.), and the Translational Geroscience Network (AG061456: J.L.K., T.T., N.M., S.B.K., S.K.), Robert and Arlene Kogod (J.L.K.), the Connor Group (J.L.K.), Robert J. and Theresa W. Ryan (J.L.K.), and the Noaber Foundation (J.L.K.). The previous IPF clinical trial was supported by the Claude D. Pepper Older Americans Independence Centers at WFSM (AG021332: J.N.J., S.B.K.), UTHSCA (AG044271: A.M.N.), and the Translational Geroscience Network.

Role of senescence in the chronic health consequences of COVID-19

While the full impact of COVID-19 is not yet clear, early studies have indicated that upwards of 10% of patients experience COVID-19 symptoms longer than 3 weeks, known as Long-Hauler's Syndrome or PACS (postacute sequelae of SARS-CoV-2 infection). There is little known about risk factors or predictors of susceptibility for Long-Hauler's Syndrome, but older adults are at greater risk for severe outcomes and mortality from COVID-19. The pillars of aging (including cellular senescence, telomere dysfunction, impaired proteostasis, mitochondrial dysfunction, deregulated nutrient sensing, genomic instability, progenitor cell exhaustion, altered intercellular communication, and epigenetic alterations) that contribute to age-related dysfunction and chronic diseases (the "Geroscience Hypothesis") may interfere with defenses against viral infection and consequences of these infections. Heightening of the low-grade inflammation that is associated with aging may generate an exaggerated response to an acute COVID-19 infection. Innate immune system dysfunction that leads to decreased senescent cell removal and/or increased senescent cell formation could contribute to accumulation of senescent cells with both aging and viral infections. These processes may contribute to increased risk for long-term COVID-19 sequelae in older or chronically ill patients. Hence, senolytics and other geroscience interventions that may prolong healthspan and alleviate chronic diseases and multimorbidity linked to fundamental aging processes might be an option for delaying, preventing, or alleviating Long-Hauler's Syndrome.

Activatable senoprobes and senolytics: Novel strategies to detect and target senescent cells

Pharmacologically active compounds that manipulate cellular senescence (senotherapies) have recently shown great promise in multiple pre-clinical disease models, and some of them are now being tested in clinical trials. Despite promising proof-of-principle evidence, there are known on- and off-target toxicities associated with these compounds, and therefore more refined and novel strategies to improve their efficacy and specificity for senescent cells are being developed. Preferential release of drugs and macromolecular formulations within senescent cells has been predominantly achieved by exploiting one of the most widely used biomarkers of senescence, the increase in lysosomal senescence-associated β-galactosidase (SA-β-gal) activity, a common feature of most reported senescent cell types. Galacto-conjugation is a versatile therapeutic and detection strategy to facilitate preferential targeting of senescent cells by using a variety of existing formulations, including modular systems, nanocarriers, activatable prodrugs, probes, and small molecules. We discuss the benefits and drawbacks of these specific senescence targeting tools and how the strategy of galacto-conjugation might be utilised to design more specific and sophisticated next-generation senotherapeutics, as well as theranostic agents. Finally, we discuss some innovative strategies and possible future directions for the field.

The role of cellular senescence in female reproductive aging and the potential for senotherapeutic interventions

BACKGROUND

Advanced maternal age is associated with decreased oocyte quantity and quality as well as uterine and placental dysfunctions. These changes lead to infertility, pregnancy complications and birth defects in the offspring. As the mean age of giving birth is increasing worldwide, prevention of age-associated infertility and pregnancy complications, along with the more frequent use of ART, become extremely important. Currently, significant research is being conducted to unravel the mechanisms underlying female reproductive aging. Among the potential mechanisms involved, recent evidence has suggested a contributing role for cellular senescence, a cellular state of irreversible growth arrest characterized by a hypersecretory and pro-inflammatory phenotype. Elucidating the role of senescence in female reproductive aging holds the potential for developing novel and less invasive therapeutic measures to prevent or even reverse female reproductive aging and increase offspring wellbeing.

OBJECTIVE AND RATIONALE

The review will summarize the positive and negative implications of cellular senescence in the pathophysiology of the female reproductive organs during aging and critically explore the use of novel senotherapeutics aiming to reverse and/or eliminate their detrimental effects. The focus will be on major senescence mechanisms of the ovaries, the uterus, and the placenta, as well as the potential and risks of using senotherapies that have been discovered in recent years.

SEARCH METHODS

Data for this review were identified by searches of MEDLINE, PubMed and Google Scholar. References from relevant articles using the search terms 'Cellular Senescence', 'Aging', 'Gestational age', 'Maternal Age', 'Anti-aging', 'Uterus', 'Pregnancy', 'Fertility', 'Infertility', 'Reproduction', 'Implant', 'Senolytic', 'Senostatic', 'Senotherapy' and 'Senotherapeutic' where selected. A total of 182 articles published in English between 2005 and 2020 were included, 27 of which focus on potential senotherapies for reproductive aging. Exclusion criteria were inclusion of the terms 'male' and 'plants'.

OUTCOMES

Aging is a major determinant of reproductive wellbeing. Cellular senescence is a basic aging mechanism, which can be exploited for therapeutic interventions. Within the last decade, several new strategies for the development and repurposing of drugs targeting senescent cells have emerged, such as modulators of the anti-inflammatory response, oxidative stress, DNA damage, and mitochondria and protein dysfunctions. Several studies of female reproductive aging and senotherapies have been discussed that show promising results for future interventions.

WIDER IMPLICATIONS

In most countries of the Organization for Economic Co-operation and Development, the average age at which women give birth is above 30 years. Currently, in countries such as the Netherlands, Australia, Spain, Finland, Germany and the UK, birth rates among 30- to 34-year-olds are now higher than in any other age groups. This review will provide new knowledge and scientific advancement on the senescence mechanisms during female reproductive aging, and benefit fundamental and clinical scientists and professionals in the areas of reproduction, cancer, immunobiology and fibrosis.

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.

Senescence in chronic wounds and potential targeted therapies

Chronic wounds (e.g. diabetic wounds, pressure wounds, vascular ulcers, etc.) do not usually heal in a timely and orderly manner but rather last for years and may lead to irreversible adverse events, resulting in a substantial financial burden for patients and society. Recently, a large amount of evidence has proven that cellular senescence has a crucial influence on chronic nonhealing wounds. As a defensive mechanism, cell senescence is a manner of cell-cycle arrest with increased secretory phenotype to resist death, preventing cells from stress-induced damage in cancer and noncancer diseases. A growing amount of research has advanced the perception of cell senescence in various chronic wounds and focuses on pathological and physiological processes and therapies targeting senescent cells. However, previous reviews have failed to sum up novel understandings of senescence in chronic wounds and emerging strategies targeting senescence. Herein, we discuss the characteristics and mechanisms of cellular senescence and the link between senescence and chronic wounds as well as some novel antisenescence strategies targeting other diseases that may be applied for chronic wounds.

Endothelial Senescence and the Chronic Vascular Diseases: Challenges and Therapeutic Opportunities in Atherosclerosis

Atherosclerosis is probably one of the paradigms of disease linked to aging. Underlying the physiopathology of atherosclerosis are cellular senescence, oxidative stress, and inflammation. These factors are increased in the elderly and from chronic disease patients. Elevated levels of oxidative stress affect cellular function and metabolism, inducing senescence. This senescence modifies the cell phenotype into a senescent secretory phenotype. This phenotype activates immune cells, leading to chronic systemic inflammation. Moreover, due to their secretory phenotype, senescence cells present an increased release of highlighted extracellular vesicles that will change nearby/neighborhood cells and paracrine signaling. For this reason, searching for specific senescent cell biomarkers and therapies against the development/killing of senescent cells has become relevant. Recently, senomorphic and senolityc drugs have become relevant in slowing down or eliminating senescence cells. However, even though they have shown promising results in experimental studies, their clinical use is still yet to be determined.

Cellular Senescence in Cardiovascular Diseases: A Systematic Review

Aging is a prominent risk factor for cardiovascular diseases, which is the leading cause of death around the world. Recently, cellular senescence has received potential attention as a promising target in preventing cardiovascular diseases, including acute myocardial infarction, atherosclerosis, cardiac aging, pressure overload-induced hypertrophy, heart regeneration, hypertension, and abdominal aortic aneurysm. Here, we discuss the mechanisms underlying cellular senescence and describe the involvement of senescent cardiovascular cells (including cardiomyocytes, endothelial cells, vascular smooth muscle cells, fibroblasts/myofibroblasts and T cells) in age-related cardiovascular diseases. Then, we highlight the targets (SIRT1 and mTOR) that regulating cellular senescence in cardiovascular disorders. Furthermore, we review the evidence that senescent cells can exert both beneficial and detrimental implications in cardiovascular diseases on a context-dependent manner. Finally, we summarize the emerging pro-senescent or anti-senescent interventions and discuss their therapeutic potential in preventing cardiovascular diseases.

Therapeutic Potential of Senolytics in Cardiovascular Disease

Ageing is the biggest risk factor for impaired cardiovascular health, with cardiovascular disease being the leading cause of death in 40% of individuals over 65 years old. Ageing is associated with both an increased prevalence of cardiovascular disease including heart failure, coronary artery disease, and myocardial infarction. Furthermore, ageing is associated with a poorer prognosis to these diseases. Genetic models allowing the elimination of senescent cells revealed that an accumulation of senescence contributes to the pathophysiology of cardiovascular ageing and promotes the progression of cardiovascular disease through the expression of a proinflammatory and profibrotic senescence-associated secretory phenotype. These studies have resulted in an effort to identify pharmacological therapeutics that enable the specific elimination of senescent cells through apoptosis induction. These senescent cell apoptosis-inducing compounds are termed senolytics and their potential to ameliorate age-associated cardiovascular disease is the focus of this review.

The mechanotransduction of MLO-Y4 cells is disrupted by the senescence-associated secretory phenotype of neighboring cells

Age-related bone loss is attributed to the accumulation of senescent cells and their increasing production of inflammatory cytokines as part of the senescence-associated secretory phenotype (SASP). In otherwise healthy individuals, osteocytes play a key role in maintaining bone mass through their primary function of responding to skeletal loading. Given that osteocytes' response to loading is known to steadily decline with age, we hypothesized that the increasing presence of senescent cells and their SASP inhibit osteocytes' response to loading. To test this hypothesis, we developed two in vitro models of senescent osteocytes and osteoblasts derived from MLO-Y4 and MC3T3 cell lines, respectively. The senescent phenotype was unique to each cell type based on distinct changes in cell cycle inhibitors and SASP profile. The SASP profile of senescent osteocytes was in part dependent on nuclear factor-κB signaling and presents a new potential mechanism to target the SASP in bone. Nonsenescent MLO-Y4 cells cultured with the SASP of each senescent cell type failed to exhibit changes in gene expression as well as ERK phosphorylation and prostaglandin E2 release. The SASP of senescent osteocytes had the largest effect and neutralizing interleukin-6 (IL-6) as part of the SASP restored osteocytes' response to loading. The loss in mechanotransduction due to IL-6 was attributed to a decrease in P2X7 expression and overall sensitivity to purinergic signaling. Altogether, these findings demonstrate that the SASP of senescent cells have a negative effect on the mechanotransduction of osteocytes and that IL-6 is a key SASP component that contributes to the loss in mechanotransduction.

Telomere dysfunction in ageing and age-related diseases

Ageing organisms accumulate senescent cells that are thought to contribute to body dysfunction. Telomere shortening and damage are recognized causes of cellular senescence and ageing. Several human conditions associated with normal ageing are precipitated by accelerated telomere dysfunction. Here, we systematize a large body of evidence and propose a coherent perspective to recognize the broad contribution of telomeric dysfunction to human pathologies.

Local Elimination of Senescent Cells Promotes Bone Defect Repair during Aging

Due to the declined function of bone marrow mesenchymal stem cells (BMSCs), the repair of bone defects in the elderly is retarded. Elimination of senescent cells emerges as a promising strategy for treating age-related diseases. However, whether the local elimination of senescent BMSCs can promote bone regeneration in the elderly remains elusive. To tackle the above issue, we first screened out the specific senolytics for BMSCs and confirmed their effect of eliminating senescent BMSCs in vitro. Treatment with quercetin, which is determined the best senolytics for senescent BMSCs, efficiently removed senescent cells in the population. Moreover, the self-renewal capacity was restored as well as osteogenic ability of BMSCs after treatment. We then designed a microenvironment-responsive hydrogel based on the MMPs secreted by senescent cells. This quercetin-encapsulated hydrogel exhibited a stable microstructure and responsively released quercetin in the presence of senescence in vitro. In vivo, the quercetin-loaded hydrogel effectively cleared the local senescent cells and reduced the secretion of MMPs in the bone. Due to the removal of local senescent cells, the hydrogel significantly accelerated the repair of bone defects in the femur and skull of old rats. Taken together, our study revealed the role of removing senescent cells in bone regeneration and provided a novel therapeutic approach for bone defects in aged individuals.

An inducible p21-Cre mouse model to monitor and manipulate p21-highly-expressing senescent cells in vivo

The role of senescent cells has been implicated in various tissue dysfunction associated with aging, obesity, and other pathological conditions. Currently, most transgenic mouse models only target p16 ^Ink4a-highly-expressing (p16 ^high) cells. Here, we generated a p21-Cre mouse model, containing a p21 promoter driving inducible Cre, enabling us to examine p21 ^Cip1-highly-expressing (p21 ^high) cells, a previously unexplored cell population exhibiting several characteristics typical of senescent cells. By crossing p21-Cre mice with different floxed mice, we managed to monitor, sort, image, eliminate, or modulate p21 ^high cells in vivo. We showed p21 ^high cells can be induced by various conditions, and percentages of p21 ^high cells varied from 1.5 to 10% across different tissues in 23-month-old mice. Intermittent clearance of p21 ^high cells improved physical function in 23-month-old mice. Our study demonstrates that the p21-Cre mouse model is a valuable and powerful tool for studying p21 ^high cells to further understand the biology of senescent cells.

Induction of Cellular Senescence in Rat Vaginal Fibroblasts and Treatment With Senolytics: An in Vitro Model for the Study of Pelvic Organ Prolapse

OBJECTIVE

The objective of this study was to develop an in vitro model of cellular senescence using rat vaginal fibroblasts and determine the effects of treatment with senolytics.

METHODS

Rat vaginal tissue biopsies were collected. Primary vaginal fibroblasts were isolated and characterized by immunofluorescence. To induce cellular senescence, fibroblasts were treated with etoposide at 3, 10, and 20 mM for 24 hours, followed by treatment with the senolytics dasatinib (1 mM) and/or quercetin (20 mM). After treatment, RNA was extracted and the expression of selected genes was quantified. Immunostaining of senescence markers was also performed.

RESULTS

Fibroblasts were confirmed by positive immunostaining for α-smooth muscle actin and vimentin, and negative immunostaining for pan-cytokeratin. Treatment with etoposide resulted in a dose-dependent increase in expression of the senescence-associated secretory phenotype markers MMP-7, MMP-9, and IL-b1 (P < 0.05) compared with controls. Immunostaining showed increased expression of γ-H2A and p21 after treatment with etoposide. Cells treated with dasatinib and quercetin after etoposide treatment had decreased expression of p21, MMP-7, MMP-9, and IL-1b compared with cells treated only with etoposide (P < 0.05).

CONCLUSIONS

Upregulation of senescence-associated factors provided evidence that senescence can be induced in vaginal fibroblasts in vitro. Furthermore, treatment with the senolytics dasatinib and quercetin abrogated the senescence phenotype induced by etoposide in rat vaginal fibroblasts. Our findings provide a novel model for the study and development of new therapies targeting the disordered extracellular matrix associated with pelvic organ prolapse.

Creation of a collection of different biological sample types from elderly patients to study the relationship of clinical, systemic, tissue and cellular biomarkers of accumulation of senescent cells during aging

With aging, tissue homeostasis and their effective recovery after damage is violated. It has been shown that this may be due to the excessive accumulation of senescent (SC) cells in various tissues, which leads to the activation of chronic sterile inflammation, tissue dysfunction and, as a result, to the development of age-related diseases. To assess the contribution of SC cells to human body aging and pathogenesis of such diseases, relevant biomarkers are studied. For successful translation into clinical practice of approaches aimed at regulating the SC cell content in various tissues, it is necessary to study the relationship between the established clinical biomarkers of aging and age-related diseases, systemic aging parameters, and SC biomarkers at the tissue and cellular levels.

Aim. To develop and describe action algorithms for creating a biobank of samples obtained from patients aged >65 years in order to study biomarkers of SC cell accumulation.

Material and methods. To collect samples, an interaction system was built between several research, clinical and infrastructure departments of a multidisciplinary medical center. At the stage of preanalytical training, regulatory legal acts were developed, including informed consent for patients, as well as protocols for each stage of the study.

Results. A roadmap was formed with action algorithms for all participants in the study, as well as with a convenient and accessible system of annotations and storage of biological samples. To date, the collection includes biological samples of 7 different types (peripheral blood serum, formalin-fixed tissue samples and formalin fixed paraffin embedded tissue specimens, samples of different cells isolated from peripheral blood, skin and adipose tissue, samples of deoxyribonucleic and ribonucleic acids, cell secretome conditioned media) obtained from 82 patients. We accumulated relevant anamnestic, clinical and laboratory data, as well as the results of experimental studies to assess the SC cell biomarkers. Using the collection, the relationship between clinical, tissue and cellular biomarkers of SC cell accumulation was studied.

Conclusion. The creation of a collection of biological samples at the molecular, cellular, tissue and organism levels from one patient provides great opportunities for research in the field of personalized medicine and the study of age-related disease pathogenesis.

Restoration of hippocampal neural precursor function by ablation of senescent cells in the aging stem cell niche

Senescent cells are responsible, in part, for tissue decline during aging. Here, we focused on CNS neural precursor cells (NPCs) to ask if this is because senescent cells in stem cell niches impair precursor-mediated tissue maintenance. We demonstrate an aging-dependent accumulation of senescent cells, largely senescent NPCs, within the hippocampal stem cell niche coincident with declining adult neurogenesis. Pharmacological ablation of senescent cells via acute systemic administration of the senolytic drug ABT-263 (Navitoclax) caused a rapid increase in NPC proliferation and neurogenesis. Genetic ablation of senescent cells similarly activated hippocampal NPCs. This acute burst of neurogenesis had long-term effects in middle-aged mice. One month post-ABT-263, adult-born hippocampal neuron numbers increased and hippocampus-dependent spatial memory was enhanced. These data support a model where senescent niche cells negatively influence neighboring non-senescent NPCs during aging, and ablation of these senescent cells partially restores neurogenesis and hippocampus-dependent cognition.

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Senescent neural precursor cells accumulate in the hippocampus with age

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Senescent precursor accumulation is coincident with declining adult neurogenesis

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Ablating senescent precursors increases precursor proliferation and neurogenesis

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Ablating senescent precursors improves hippocampus-dependent spatial memory

Senolytic Therapy to Modulate the Progression of Alzheimer's Disease (SToMP-AD): A Pilot Clinical Trial

Preclinical studies indicate an age-associated accumulation of senescent cells across multiple organ systems. Emerging evidence suggests that tau protein accumulation, which closely correlates with cognitive decline in Alzheimer's disease and other tauopathies, drives cellular senescence in the brain. Pharmacologically clearing senescent cells in mouse models of tauopathy reduced brain pathogenesis. Compared to vehicle treated mice, intermittent senolytic administration reduced tau accumulation and neuroinflammation, preserved neuronal and synaptic density, restored aberrant cerebral blood flow, and reduced ventricular enlargement. Intermittent dosing of the senolytics, dasatinib plus quercetin, has shown an acceptable safety profile in clinical studies for other senescence-associated conditions. With these data, we proposed and herein describe the objectives and methods for a clinical vanguard study. This initial open-label clinical trial pilots an intermittent senolytic combination therapy of dasatinib plus quercetin in five older adults with early-stage Alzheimer's disease. The primary objective is to evaluate the central nervous system penetration of dasatinib and quercetin through analysis of cerebrospinal fluid collected at baseline and after 12 weeks of treatment. Further, through a series of secondary outcome measures to assess target engagement of the senolytic compounds and Alzheimer's disease-relevant cognitive, functional, and physical outcomes, we will collect preliminary data on safety, feasibility, and efficacy. The results of this study will be used to inform the development of a randomized, double-blind, placebo-controlled multicenter phase II trial to further explore of the safety, feasibility, and efficacy of senolytics for modulating the progression of Alzheimer's disease. Clinicaltrials.gov registration number and date: NCT04063124 (08/21/2019).

The costs and benefits of senotherapeutics for human health

Cellular senescence is a major contributor to age-related diseases in humans; however, it also has a beneficial role in physiological and pathological processes, including wound healing, host immunity, and tumour suppression. Reducing the burden of cell senescence in animal models of cardiometabolic disorders, inflammatory conditions, neurodegenerative diseases, and cancer using pharmaceutical approaches that selectively target senescent cells (ie, senolytics) or that suppress senescence-associated secretory phenotype (ie, senomorphics) holds great promise for the management of chronic age-associated conditions. Although studies have provided evidence that senolytics or senomorphics are effective at decreasing the number of senescent cells in humans, the short-term and long-term side-effects of these therapies are largely unknown. In this Review, we systematically discuss the senolytics and senomorphics that have been investigated in clinical trials or have been used off-label, presenting their various adverse effects. Despite the potential of senotherapeutics to transform anti-ageing medicine, a cautionary approach regarding unwanted dose-dependent side-effects should be adopted.

The Mechanobiology of Vascular Remodeling in the Aging Lung

Aging is accompanied by declining lung function and increasing susceptibility to lung diseases. The role of endothelial dysfunction and vascular remodeling in these changes is supported by growing evidence, but underlying mechanisms remain elusive. In this review we summarize functional, structural, and molecular changes in the aging pulmonary vasculature and explore how interacting aging and mechanobiological cues may drive progressive vascular remodeling in the lungs.

Is it the time of seno-therapeutics application in cardiovascular pathological conditions related to ageing?

It rates that in 2030, the cardiovascular diseases (CVD) will result in 40% of all deaths and rank as the leading cause. Thus, the research of appropriate therapies able to delay or retard their onset and progression is growing. Of particular interest is a new branch of the medical science, called anti-ageing medicine since CVD are the result of cardiovascular ageing. Senescent cells (SC) accumulate in cardiovascular system contributing to the onset of typical age-related cardiovascular conditions (i.e., atherosclerosis, medial aorta degeneration, vascular remodeling, stiffness). Such conditions progress in cardiovascular pathologies (i.e., heart failure, coronary artery disease, myocardial infarction, and aneurysms) by evocating the production of a proinflammatory and profibrotic senescence-associated secretory phenotype (SASP). Consequently, therapies able to specifically eliminate SC are in developing. The senotherapeutics represents an emerging anti-SC treatment, and comprises three therapeutic approaches: (a) molecules to selectively kill SC, defined senolytics; (b) compounds able in reducing evocated SC SASP, acting hence as SASP suppressors, or capable to change the senescent phenotype, called senomorphics; (c) inhibition of increase of the number of SC in the tissues. Here, it describes them and the emerging data about current investigations on their potential clinical application in CVD, stressing benefits and limitations, and suggesting potential solutions for applying them in near future as effective anti-CVD treatments.

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The anti-ageing medicine might be a new via for developing CVD treatments.

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Senotherapeutics represents an emerging treatment.

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It comprises three therapeutic approaches.

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They might have a potential clinical application in CVD.

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Benefits and limitations have been reported.

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.

Potential Therapies to Protect the Aging Heart Against Ischemia/Reperfusion Injury

Despite important advances in the treatment of myocardial infarction that have significantly reduced mortality, there is still an unmet need to limit the infarct size after reperfusion injury in order to prevent the onset and severity of heart failure. Multiple cardioprotective maneuvers, therapeutic targets, peptides and drugs have been developed to effectively protect the myocardium from reperfusion-induced cell death in preclinical studies. Nonetheless, the translation of these therapies from laboratory to clinical contexts has been quite challenging. Comorbidities, comedications or inadequate ischemia/reperfusion experimental models are clearly identified variables that need to be accounted for in order to achieve effective cardioprotection studies. The aging heart is characterized by altered proteostasis, DNA instability, epigenetic changes, among others. A vast number of studies has shown that multiple therapeutic strategies, such as ischemic conditioning phenomena and protective drugs are unable to protect the aged heart from myocardial infarction. In this Mini-Review, we will provide an updated state of the art concerning potential new cardioprotective strategies targeting the aging heart.

Strategies for late phase preclinical and early clinical trials of senolytics

Cellular senescence and the hallmarks of aging contribute to age-related disease and dysfunction. The Unitary Theory of Fundamental Aging Mechanisms highlights the interdependence among the hallmarks of aging and suggests that by intervening in one fundamental aging process, most or all of the other processes could be impacted. Accumulation of senescent cells is associated with frailty, cardiovascular disease, obesity, diabetes, cognitive decline, and other age- and/or chronic disease-related disorders, suggesting that senescent cells are a target for intervention. Early preclinical data using senolytics, agents that target senescent cells, show promising results in several aging and disease models. The first in-human trials using the senolytic combination of Dasatinib and Quercetin indicated reduced senescent cell burden in adipose tissue of diabetic kidney disease patients and improved physical function in patients with idiopathic pulmonary fibrosis. Clinical trials with other senolytics, including the flavonoid Fisetin and BCL-xL inhibitors, are underway. These results from preclinical and early clinical trials illustrate the potential of senolytics to alleviate age-related dysfunction and diseases. However, multiple clinical trials across different aging and disease models are desperately needed. Parallel trials across institutions through the Translational Geroscience Network are facilitating testing to determine whether senolytics can be translated into clinical application.

A geroscience motivated approach to treat Alzheimer's disease: Senolytics move to clinical trials

The pathogenic processes driving Alzheimer's disease (AD) are complex. An incomplete understanding of underlying disease mechanisms has presented insurmountable obstacles for developing effective disease-modifying therapies. Advanced chronological age is the greatest risk factor for developing AD. Intervening on biological aging may alter disease progression and represents a novel, complementary approach to current strategies. Toward this end, cellular senescence has emerged as a promising target. This complex stress response harbors damaged cells in a cell cycle arrested, apoptosis-resistant cell state. Senescent cells accumulate with age where they notoriously secrete molecules that contribute to chronic tissue dysfunction and disease. Thus, benefits of cell survival in a senescent fate are countered by their toxic secretome. The removal of senescent cells improves brain structure and function in rodent models at risk of developing AD, and in those with advanced Aβ and tau pathology. The present review describes the path to translating this promising treatment strategy to AD clinical trials. We review evidence for senescent cell accumulation in the human brain, considerations and strategies for senescence-targeting trials specific to AD, approaches to detect senescent brain cells in biofluids, and summarize the goals of the first senolytic trials for the treatment of AD (NCT04063124 and NCT04685590). This article is part of the Special Issue - Senolytics - Edited by Joao Passos and Diana Jurk.

The potential of Senolytics in transplantation

Older organs provide a substantial unrealized potential with the capacity to close the gap between demand and supply in organ transplantation. The potential of senolytics in improving age-related conditions has been shown in various experimental studies and early clinical trials. Those encouraging data may also be of relevance for transplantation. As age-differences between donor and recipients are not uncommon, aging may be accelerated in recipients when transplanting older organs; young organs may, at least in theory, have the potential to 'rejuvenate' old recipients. Here, we review the relevance of senescent cells and the effects of senolytics on organ quality, alloimmune responses and outcomes in solid organ transplantation. This article is part of the Special Issue - Senolytics - Edited by Joao Passos and Diana Jurk.

Long-term cardiovascular complications following sepsis: is senescence the missing link?

Among the long-term consequences of sepsis (also termed “post-sepsis syndrome”) the increased risk of unexplained cardiovascular complications, such as myocardial infarction, acute heart failure or stroke, is one of the emerging specific health concerns. The vascular accelerated ageing also named premature senescence is a potential mechanism contributing to atherothrombosis, consequently leading to cardiovascular events. Indeed, vascular senescence-associated major adverse cardiovascular events (MACE) are a potential feature in sepsis survivors and of the elderly at cardiovascular risk. In these patients, accelerated vascular senescence could be one of the potential facilitating mechanisms. This review will focus on premature senescence in sepsis regardless of age. It will highlight and refine the potential relationships between sepsis and accelerated vascular senescence. In particular, key cellular mechanisms contributing to cardiovascular events in post-sepsis syndrome will be highlighted, and potential therapeutic strategies to reduce the cardiovascular risk will be further discussed.

With improved management of patients, sepsis survivors are increasing each year.

Early cardiovascular complications, of yet undeciphered mechanisms, are an emerging health issue in post-sepsis syndrome.

Premature senescence of endothelium and vascular tissue is proven an accelerated process of atherogenesis in young septic rats.

An increasing body of clinical evidence point at endothelial senescence in the initiation and development of atherosclerosis.

Prevention of premature senescence by senotherapy and cardiological follow-up could improve long-term septic patients’ outcomes.

Senolytic vaccination improves normal and pathological age-related phenotypes and increases lifespan in progeroid mice

Elimination of senescent cells (senolysis) was recently reported to improve normal and pathological changes associated with aging in mice^1,2. However, most senolytic agents inhibit antiapoptotic pathways³, raising the possibility of off-target effects in normal tissues. Identification of alternative senolytic approaches is therefore warranted. Here we identify glycoprotein nonmetastatic melanoma protein B (GPNMB) as a molecular target for senolytic therapy. Analysis of transcriptome data from senescent vascular endothelial cells revealed that GPNMB was a molecule with a transmembrane domain that was enriched in senescent cells (seno-antigen). GPNMB expression was upregulated in vascular endothelial cells and/or leukocytes of patients and mice with atherosclerosis. Genetic ablation of Gpnmb-positive cells attenuated senescence in adipose tissue and improved systemic metabolic abnormalities in mice fed a high-fat diet, and reduced atherosclerotic burden in apolipoprotein E knockout mice on a high-fat diet. We then immunized mice against Gpnmb and found a reduction in Gpnmb-positive cells. Senolytic vaccination also improved normal and pathological phenotypes associated with aging, and extended the male lifespan of progeroid mice. Our results suggest that vaccination targeting seno-antigens could be a potential strategy for new senolytic therapies.

Cellular Senescence: Mechanisms and Therapeutic Potential

Cellular senescence is a complex and multistep biological process which cells can undergo in response to different stresses. Referring to a highly stable cell cycle arrest, cellular senescence can influence a multitude of biological processes-both physiologically and pathologically. While phenotypically diverse, characteristics of senescence include the expression of the senescence-associated secretory phenotype, cell cycle arrest factors, senescence-associated β-galactosidase, morphogenesis, and chromatin remodelling. Persistent senescence is associated with pathologies such as aging, while transient senescence is associated with beneficial programmes, such as limb patterning. With these implications, senescence-based translational studies, namely senotherapy and pro-senescence therapy, are well underway to find the cure to complicated diseases such as cancer and atherosclerosis. Being a subject of major interest only in the recent decades, much remains to be studied, such as regarding the identification of unique biomarkers of senescent cells. This review attempts to provide a comprehensive understanding of the diverse literature on senescence, and discuss the knowledge we have on senescence thus far.

Epigenetic dysregulation in cardiovascular aging and disease

Cardiovascular disease (CVD) is the leading cause of mortality and morbidity for all sexes, racial and ethnic groups. Age, and its associated physiological and pathological consequences, exacerbate CVD incidence and progression, while modulation of biological age with interventions track with cardiovascular health. Despite the strong link between aging and CVD, surprisingly few studies have directly investigated heart failure and vascular dysfunction in aged models and subjects. Nevertheless, strong correlations have been found between heart disease, atherosclerosis, hypertension, fibrosis, and regeneration efficiency with senescent cell burden and its proinflammatory sequelae. In agreement, senotherapeutics have had success in reducing the detrimental effects in experimental models of cardiovascular aging and disease. Aside from senotherapeutics, cellular reprogramming strategies targeting epigenetic enzymes remain an unexplored yet viable option for reversing or delaying CVD. Epigenetic alterations comprising local and global changes in DNA and histone modifications, transcription factor binding, disorganization of the nuclear lamina, and misfolding of the genome are hallmarks of aging. Limited studies in the aging cardiovascular system of murine models or human patient samples have identified strong correlations between the epigenome, age, and senescence. Here, we compile the findings in published studies linking epigenetic changes to CVD and identify clear themes of epigenetic deregulation during aging. Pending direct investigation of these general mechanisms in aged tissues, this review predicts that future work will establish epigenetic rejuvenation as a potent method to delay CVD.

The aging venous system: from varicosities to vascular cognitive impairment

Aging-induced pathological alterations of the circulatory system play a critical role in morbidity and mortality of older adults. While the importance of cellular and molecular mechanisms of arterial aging for increased cardiovascular risk in older adults is increasingly appreciated, aging processes of veins are much less studied and understood than those of arteries. In this review, age-related cellular and morphological alterations in the venous system are presented. Similarities and dissimilarities between arterial and venous aging are highlighted, and shared molecular mechanisms of arterial and venous aging are considered. The pathogenesis of venous diseases affecting older adults, including varicose veins, chronic venous insufficiency, and deep vein thrombosis, is discussed, and the potential contribution of venous pathologies to the onset of vascular cognitive impairment and neurodegenerative diseases is emphasized. It is our hope that a greater appreciation of the cellular and molecular processes of vascular aging will stimulate further investigation into strategies aimed at preventing or retarding age-related venous pathologies.

Design of a Randomized Placebo-Controlled Trial to Evaluate the Anti-inflammatory and Senolytic Effects of Quercetin in Patients Undergoing Coronary Artery Bypass Graft Surgery

Background: Following an acute coronary syndrome, patients display an elevated inflammatory profile, promoted in part by cellular senescence. For patients requiring a coronary artery bypass (CABG) surgery, exposure to the surgical intervention and cardiopulmonary bypass further exacerbate their residual inflammation. Experimental evidence identified quercetin, a natural senolytic drug, as a cardioprotective agent against inflammatory injuries. The Q-CABG study aims to explore the efficacy of quercetin to reduce inflammation, myocardial injury and senescence in patients undergoing CABG following an acute coronary syndrome.

Methods: Q-CABG is a phase II, prospectively registered, randomized, double-blind and placebo-controlled clinical trial. Recruited patients awaiting CABG surgery at the Montreal Heart Institute (n = 100) will be randomly assigned in a 1:1 ratio to receive either quercetin supplementation (500 mg twice daily) or placebo, starting 2 days before surgery and until the seventh postoperative day. The primary endpoint examines the effects of quercetin on blood inflammatory cytokines and markers of myocardial injury and senescence in this patient population. Blood samples will be taken at four time points: baseline, postoperative day 1, postoperative day 4 and at hospital discharge, or after a maximum of seven postoperative days. The secondary endpoint is the assessment of endothelial (dys) function by looking at ex vivo vascular reactivity and mRNA expression of endothelial cells from the wall of discarded segments of internal mammary artery.

Discussion: The preventive intake of quercetin supplementation may help limit the vigorous inflammatory response triggered by CABG and subsequent postoperative complications in patients suffering from an acute coronary syndrome. In an exploratory way, quercetin supplementation could also improve endothelial function by eliminating senescent vascular endothelial cells. The results of this trial should provide valuable information regarding a novel approach to improve biological, and potentially clinical, outcomes post CABG.

Clinical Trial Registration:ClinicalTrials.gov, Identifier NCT04907253.

Obesity, Senescence, and Senolytics

Obesity is a major risk factor for the development of comorbidities such as type 2 diabetes, neurodegenerative disorders, osteoarthritis, cancer, cardiovascular and renal diseases. The onset of obesity is linked to an increase of senescent cells within adipose tissue and other organs. Cellular senescence is a stress response that has been shown to be causally linked to aging and development of various age-related diseases such as obesity. The senescence-associated-secretory phenotype of senescent cells creates a chronic inflammatory milieu that leads to local and systemic dysfunction. The elimination of senescent cells using pharmacological approaches (i.e., senolytics) has been shown to delay, prevent, or alleviate obesity-related organ dysfunction.

Targeted clearance of senescent cells using an antibody-drug conjugate against a specific membrane marker

A wide range of diseases have been shown to be influenced by the accumulation of senescent cells, from fibrosis to diabetes, cancer, Alzheimer's and other age-related pathologies. Consistent with this, clearance of senescent cells can prolong healthspan and lifespan in in vivo models. This provided a rationale for developing a new class of drugs, called senolytics, designed to selectively eliminate senescent cells in human tissues. The senolytics tested so far lack specificity and have significant off-target effects, suggesting that a targeted approach could be more clinically relevant. Here, we propose to use an extracellular epitope of B2M, a recently identified membrane marker of senescence, as a target for the specific delivery of toxic drugs into senescent cells. We show that an antibody-drug conjugate (ADC) against B2M clears senescent cells by releasing duocarmycin into them, while an isotype control ADC was not toxic for these cells. This effect was dependent on p53 expression and therefore more evident in stress-induced senescence. Non-senescent cells were not affected by either antibody, confirming the specificity of the treatment. Our results provide a proof-of-principle assessment of a novel approach for the specific elimination of senescent cells using a second generation targeted senolytic against proteins of their surfaceome, which could have clinical applications in pathological ageing and associated diseases.

Dysregulated non-coding telomerase RNA component and associated exonuclease XRN1 in leucocytes from women developing preeclampsia-possible link to enhanced senescence

Senescence in placenta/fetal membranes is a normal phenomenon linked to term parturition. However, excessive senescence which may be induced by telomere attrition, has been associated with preeclampsia (PE). We hypothesized that the telomerase complex in peripheral blood mononuclear cells (PBMC) and circulating telomere associated senescence markers would be dysregulated in women with PE. We measured long non-coding (nc) RNA telomerase RNA component (TERC) and RNAs involved in the maturation of TERC in PBMC, and the expression of TERC and 5′–3′ Exoribonuclease 1 (XRN1) in extracellular vesicles at 22–24 weeks, 36–38 weeks and, 5-year follow-up in controls and PE. We also measured telomere length at 22–24 weeks and 5-year follow-up. The circulating senescence markers cathelicidin antimicrobial peptide (CAMP), β-galactosidase, stathmin 1 (STMN1) and chitotriosidase/CHIT1 were measured at 14–16, 22–24, 36–38 weeks and at 5-year follow-up in the STORK study and before delivery and 6 months post-partum in the ACUTE PE study. We found decreased expression of TERC in PBMC early in pregnant women who subsequently developed PE. XRN1 involved in the maturation of TERC was also reduced in pregnancy and 5-year follow-up. Further, we found that the senescence markers CAMP and β-galactosidase were increased in PE pregnancies, and CAMP remained higher at 5-year follow-up. β-galactosidase was associated with atherogenic lipid ratios during pregnancy and at 5-year follow-up, in PE particularly. This study suggests a potential involvement of dysfunctional telomerase biology in the pathophysiology of PE, which is not restricted to the placenta.

Treatment with the BCL-2/BCL-xL inhibitor senolytic drug ABT263/Navitoclax improves functional hyperemia in aged mice

Moment-to-moment adjustment of regional cerebral blood flow to neuronal activity via neurovascular coupling (NVC or "functional hyperemia") has a critical role in maintenance of healthy cognitive function. Aging-induced impairment of NVC responses importantly contributes to age-related cognitive decline. Advanced aging is associated with increased prevalence of senescent cells in the cerebral microcirculation, but their role in impaired NVC responses remains unexplored. The present study was designed to test the hypothesis that a validated senolytic treatment can improve NVC responses and cognitive performance in aged mice. To achieve this goal, aged (24-month-old) C57BL/6 mice were treated with ABT263/Navitoclax, a potent senolytic agent known to eliminate senescent cells in the aged mouse brain. Mice were behaviorally evaluated (radial arms water maze) and NVC was assessed by measuring CBF responses (laser speckle contrast imaging) in the somatosensory whisker barrel cortex evoked by contralateral whisker stimulation. We found that NVC responses were significantly impaired in aged mice. ABT263/Navitoclax treatment improved NVC response, which was associated with significantly improved hippocampal-encoded functions of learning and memory. ABT263/Navitoclax treatment did not significantly affect endothelium-dependent acetylcholine-induced relaxation of aorta rings. Thus, increased presence of senescent cells in the aged brain likely contributes to age-related neurovascular uncoupling, exacerbating cognitive decline. The neurovascular protective effects of ABT263/Navitoclax treatment highlight the preventive and therapeutic potential of senolytic treatments (as monotherapy or as part of combination treatment regimens) as effective interventions in patients at risk for vascular cognitive impairment (VCI).

Frailty, aging, and periodontal disease: Basic biologic considerations

Aging is associated with the development of disease. Periodontal disease is one of the many diseases and conditions that increase in prevalence with age. In addition to the traditional focus on individual age-related conditions, there is now a greater recognition that multisystem conditions such as frailty play an important role in the health of older populations. Frailty is a clinical condition in older adults that increases the risk of adverse health outcomes. Both frailty and periodontal disease are common chronic conditions in older populations and share several risk factors. There is likely a bidirectional relationship between periodontal disease and frailty. Comorbid systemic diseases, poor physical functioning, and limited ability to self-care in frail older people have been implicated as underlying the association between frailty and periodontal disease. In addition, both frailty and periodontal disease also have strong associations with inflammatory dysregulation and other age-related pathophysiologic changes that may similarly underlie their development and progression. Investigating age-related changes in immune cells that regulate inflammation may lead to a better understanding of age-related disease and could lead to therapeutic targets for the improved management of frailty and periodontal disease.

Cellular senescence as a possible link between prostate diseases of the ageing male

Senescent cells accumulate with age in all tissues. Although senescent cells undergo cell-cycle arrest, these cells remain metabolically active and their secretome - known as the senescence-associated secretory phenotype - is responsible for a systemic pro-inflammatory state, which contributes to an inflammatory microenvironment. Senescent cells can be found in the ageing prostate and the senescence-associated secretory phenotype and can be linked to BPH and prostate cancer. Indeed, a number of signalling pathways provide biological plausibility for the role of senescence in both BPH and prostate cancer, although proving causality is difficult. The theory of senescence as a mechanism for prostate disease has a number of clinical implications and could offer opportunities for targeting in the future.

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.

Biological Aspects of Inflamm-Aging in Childhood Cancer Survivors

Anti-cancer treatments improve survival in children with cancer. A total of 80% of children treated for childhood cancer achieve 5-year survival, becoming long-term survivors. However, they undergo several chronic late effects related to treatments. In childhood cancer survivors a chronic low-grade inflammation, known as inflamm-aging, is responsible for frailty, a condition characterized by vital organ failure and by premature aging processes. Inflamm-aging is closely related to chemotherapy and radiotherapy, which induce inflammation, accumulation of senescent cells, DNA mutations, and the production of reactive oxygen species. All these conditions are responsible for the onset of secondary diseases, such as osteoporosis, cardiovascular diseases, obesity, and infertility. Considering that the pathobiology of frailty among childhood cancer survivors is still unknown, investigations are needed to better understand frailty's biological and molecular processes and to identify inflamm-aging key biomarkers in order to facilitate the screening of comorbidities and to clarify whether treatments, normally used to modulate inflamm-aging, may be beneficial. This review offers an overview of the possible biological mechanisms involved in the development of inflamm-aging, focusing our attention on immune system alteration, oxidative stress, cellular senescence, and therapeutic strategies.

Cellular senescence promotes cancer metastasis by enhancing soluble E-cadherin production

Cellular senescence acts as a potent tumor-suppression mechanism in mammals; however, it also promotes tumor progression in a non-cell-autonomous manner. We provided insights into the mechanism underlying senescence-dependent metastatic cancer development. The elimination of senescent cells suppressed the lung metastasis of melanoma cells. Using an antibody array screening of humoral factor(s) that depend on cellular senescence, we identified soluble E-cadherin (seCad) as a potential mediator of the senescence-induced melanoma metastasis. seCad enhanced the invasive activity of melanoma cells both in vitro and in vivo, and gene expression profiling revealed that seCad induced genes associated with poor prognosis in patients with melanoma. An analysis of sera from patients revealed that serum seCad is associated with distant metastasis. Our data suggest that senescent cells promote metastatic lung cancer through seCad, and that seCad may be a potential diagnostic marker as well as a therapeutic target for metastatic lung cancer.

Age and Sex: Impact on adipose tissue metabolism and inflammation

Age associated chronic inflammation is a major contributor to diseases with advancing age. Adipose tissue function is at the nexus of processes contributing to age-related metabolic disease and mediating longevity. Hormonal fluctuations in aging potentially regulate age-associated visceral adiposity and metabolic dysfunction. Visceral adiposity in aging is linked to aberrant adipogenesis, insulin resistance, lipotoxicity and altered adipokine secretion. Age-related inflammatory phenomena depict sex differences in macrophage polarization, changes in T and B cell numbers, and types of dendritic cells. Sex differences are also observed in adipose tissue remodeling and cellular senescence suggesting a role for sex steroid hormones in the regulation of the adipose tissue microenvironment. It is crucial to investigate sex differences in aging clinical outcomes to identify and better understand physiology in at-risk individuals. Early interventions aimed at targets involved in adipose tissue adipogenesis, remodeling and inflammation in aging could facilitate a profound impact on health span and overcome age-related functional decline.

Long-term treatment with senolytic drugs Dasatinib and Quercetin ameliorates age-dependent intervertebral disc degeneration in mice

Intervertebral disc degeneration is highly prevalent within the elderly population and is a leading cause of chronic back pain and disability. Due to the link between disc degeneration and senescence, we explored the ability of the Dasatinib and Quercetin drug combination (D + Q) to prevent an age-dependent progression of disc degeneration in mice. We treated C57BL/6 mice beginning at 6, 14, and 18 months of age, and analyzed them at 23 months of age. Interestingly, 6- and 14-month D + Q cohorts show lower incidences of degeneration, and the treatment results in a significant decrease in senescence markers p16^INK4a, p19^ARF, and SASP molecules IL-6 and MMP13. Treatment also preserves cell viability, phenotype, and matrix content. Although transcriptomic analysis shows disc compartment-specific effects of the treatment, cell death and cytokine response pathways are commonly modulated across tissue types. Results suggest that senolytics may provide an attractive strategy to mitigating age-dependent disc degeneration.

Inflammatory Molecular Mediators and Pathways Involved in Vascular Aging and Stroke: A Comprehensive Review

There is an increase in the incidence of cardiovascular diseases with aging and it is one of the leading causes of death worldwide. The main cardiovascular pathologies include atherosclerosis, stroke, myocardial infarction, hypertension and stroke. Chronic inflammation is one of the significant contributors to the age-related vascular diseases. Therefore, it is important to understand the molecular mechanisms of the persistent inflammatory conditions occurring in the blood vessels as well as the signaling pathways involved. Herein, we performed an extant search of literature involving PubMed, ISI, WoS and Scopus databases for retrieving all relevant articles with the most recent findings illustrating the potential role of various inflammatory mediators along with their proposed activated pathways in the pathogenesis and progression of vascular aging. We also highlight the major pathways contributing to age-related vascular disorders. The outlined molecular mechanisms, pathways and mediators of vascular aging represent potential drug targets that can be utilized to inhibit and/or slow the pathogenesis and progression of vascular aging.

Impact of Senescent Cell Subtypes on Tissue Dysfunction and Repair: Importance and Research Questions

Cellular senescence, first observed and defined through cell culture studies, is a cell fate associated with essentially permanent cell cycle arrest and that can be triggered by a variety of inducers. Emerging evidence suggests senescence is a dynamic process with diverse functional characteristics. Depending on the tissue, type of inducer, and time since induction, senescent cells can promote tissue repair and re-modeling, prevent tumor development, or contribute to age-related disorders and chronic diseases, including cancers. Senescent cell characteristics appear to depend on multiple factors and be influenced by the milieu and other senescent cells locally and at a distance. We review diverse phenotypes of senescent cells originating from different cell types, senescence inducers over time since induction of senescence, and across conditions and diseases. This background is essential to inform further understanding about senescent cell subtypes and will point towards rational senescence-modulating strategies for achieving therapeutic benefit.