Fisetin is a senotherapeutic that extends health and lifespan

Flavonoids from Scutellaria baicalensis inhibit senescence-associated secretory phenotype production by interrupting IκBζ/C/EBPβ pathway: Inhibition of age-related inflammation

BACKGROUND

Prolonged exposure to the senescence-associated secretory phenotype (SASP) with age leads to chronic low-grade inflammation in neighboring cells and tissues, causing many chronic degenerative diseases.

PURPOSE

The effects on SASP production of the ethanol extract from Scutellaria radix and 17 isolated flavonoid constituents were examined in vitro and in vivo.

METHODS

Cellular senescence was induced by bleomycin. Expression of the SASP and cell signaling molecules was detected using ELISA, RT-qPCR, Western blotting, and immunofluorescence staining. To investigate the in vivo effects, 21-month-old aged rats were used.

RESULTS

The ethanol extract and 5 compounds including 1 (Oroxylin A; 5,7-dihydroxy-6-methoxyflavone), 5 (2',6',5,7-tetrahydroxy-8-methoxyflavone), 8 (2',5,7-trihydroxyflavone), 10 (2',5,7-trihydroxy-8-methoxyflavone) and 11 (2',5,7-trihydroxy-6-methoxyflavone) potently reduced IL-6 and IL-8 production and gene expression of the SASP, including IL-1α, IL-1β, IL-6, IL-8, GM-CSF, CXCL1, MCP-2, and MMP-3. This finding indicates the important role of the B-ring 2'‑hydroxyl group in flavonoid molecules. Furthermore, compounds 8 and 11, the strongest SASP inhibitors, decreased the expression of IκBζ and C/EBPβ protein without affecting either BrdU uptake or the expression of senescence markers, such as pRb and p21. Finally, the oral administration of compound 8 to aged rats at 2 and 4 mg/kg/day for 10 days significantly inhibited the gene expression of SASP and IκBζ in kidneys. This is the first report of the strong SASP inhibitory action of flavonoids from Scutellaria radix on in vitro and in vivo senescence models. The inhibitory action was shown to be mediated mainly by interfering with the IκBζ/C/EBPβ signaling pathway.

CONCLUSION

Targeting production of the SASP using flavonoids from Scutellaria radix or its extract might help reduce low-grade sterile inflammation and control age-related diseases.

Potential implications of polyphenols on aging considering oxidative stress, inflammation, autophagy, and gut microbiota

Naturally occurring compounds polyphenols are secondary metabolites of plants, comprised several categories, namely, flavonoids, phenolic acids, lignans and stilbenes. The biological aging process is driven by a series of interrelated mechanisms, including oxidative stress, inflammation status, and autophagy function, through diverse signaling pathways. Moreover, the crucial role of gut microbiota in regulating aging and health status was widely demonstrated. In recent years, the potential anti-aging benefits of polyphenols have been gaining increasing scientific interest due to their capability to modulate oxidative damage, inflammation, autophagy, and gut microbiota. This review highlights the influence of polyphenols in preventing aging disorders and augmenting lifespan based on the influence of oxidative stress, inflammation, autophagy, and gut microbiota, and encourages research on novel polyphenol-based strategies and clinical trials to develop a nutrition-oriented holistic anti-aging therapy.

Targeted Reduction of Senescent Cell Burden Alleviates Focal Radiotherapy-Related Bone Loss

Clinical radiotherapy treats life-threatening cancers, but the radiation often affects neighboring normal tissues including bone. Acute effects of ionizing radiation include oxidative stress, DNA damage, and cellular apoptosis. We show in this study that a large proportion of bone marrow cells, osteoblasts, and matrix-embedded osteocytes recover from these insults only to attain a senescent profile. Bone analyses of senescence-associated genes, senescence-associated beta-galactosidase (SA-β-gal) activity, and presence of telomere dysfunction-induced foci (TIF) at 1, 7, 14, 21, and 42 days post-focal radiation treatment (FRT) in C57BL/6 male mice confirmed the development of senescent cells and the senescence-associated secretory phenotype (SASP). Accumulation of senescent cells and SASP markers were correlated with a significant reduction in bone architecture at 42 days post-FRT. To test if senolytic drugs, which clear senescent cells, alleviate FRT-related bone damage, we administered the senolytic agents, dasatinib (D), quercetin (Q), fisetin (F), and a cocktail of D and Q (D+Q). We found moderate alleviation of radiation-induced bone damage with D and Q as stand-alone compounds, but no such improvement was seen with F. However, the senolytic cocktail of D+Q reduced senescent cell burden as assessed by TIF⁺ osteoblasts and osteocytes, markers of senescence (p16 ^Ink4a and p21), and key SASP factors, resulting in significant recovery in the bone architecture of radiated femurs. In summary, this study provides proof of concept that senescent cells play a role in radiotherapy-associated bone damage, and that reduction in senescent cell burden by senolytic agents is a potential therapeutic option for alleviating radiotherapy-related bone deterioration. © 2020 American Society for Bone and Mineral Research.

Tissue engineering to better understand senescence: Organotypics come of age

The recent advent of 'organs in a dish' has revolutionised the research landscape. These 3D culture systems have paved the way for translational, post genomics research by enabling scientists to model diseases in the laboratory, grow patient-derived organoids, and unite this technology with other cutting-edge methodologies such as drug discovery. Fields such as dermatology and neuroscience have revolutionised the development of robust 3D models, which faithfully recapitulate native physiology in vivo to provide important functional and mechanistic insights. These models have underpinned a rapid growth in the number of organs and myriad of human diseases that can be modelled in 3D, which currently includes breast, cerebral cortex, heart, intestine, kidney, liver, lung, neural tube, pancreas, prostate, skin and stomach, as well as patient derived tumours. However, so far, they have not yet been employed extensively in the study of fundamental cellular programmes such as senescence. Thus, tissue engineering and 3D culture offer an exciting opportunity to further understand the bright and dark sides of senescence in a more complex and physiologically relevant environment. Below, we will discuss previous approaches to investigating senescence and ageing using organotypic models, and some potential opportunities for future research.

The role of cellular senescence in ageing and endocrine disease

With the ageing of the global population, interest is growing in the 'geroscience hypothesis', which posits that manipulation of fundamental ageing mechanisms will delay (in parallel) the appearance or severity of multiple chronic, non-communicable diseases, as these diseases share the same underlying risk factor - namely, ageing. In this context, cellular senescence has received considerable attention as a potential target in preventing or treating multiple age-related diseases and increasing healthspan. Here we review mechanisms of cellular senescence and approaches to target this pathway therapeutically using 'senolytic' drugs that kill senescent cells or inhibitors of the senescence-associated secretory phenotype (SASP). Furthermore, we highlight the evidence that cellular senescence has a causative role in multiple diseases associated with ageing. Finally, we focus on the role of cellular senescence in a number of endocrine diseases, including osteoporosis, metabolic syndrome and type 2 diabetes mellitus, as well as other endocrine conditions. Although much remains to be done, considerable preclinical evidence is now leading to the initiation of proof-of-concept clinical trials using senolytics for several endocrine and non-endocrine diseases.

Elimination of senescent cells by β-galactosidase-targeted prodrug attenuates inflammation and restores physical function in aged mice

Cellular senescence, a persistent state of cell cycle arrest, accumulates in aged organisms, contributes to tissue dysfunction, and drives age-related phenotypes. The clearance of senescent cells is expected to decrease chronic, low-grade inflammation and improve tissue repair capacity, thus attenuating the decline of physical function in aged organisms. However, selective and effective clearance of senescent cells of different cell types has proven challenging. Herein, we developed a prodrug strategy to design a new compound based on the increased activity of lysosomal β-galactosidase (β-gal), a primary characteristic of senescent cells. Our prodrug SSK1 is specifically activated by β-gal and eliminates mouse and human senescent cells independently of senescence inducers and cell types. In aged mice, our compound effectively cleared senescent cells in different tissues, decreased the senescence- and age-associated gene signatures, attenuated low-grade local and systemic inflammation, and restored physical function. Our results demonstrate that lysosomal β-gal can be effectively leveraged to selectively eliminate senescent cells, providing a novel strategy to develop anti-aging interventions.

Using proteolysis-targeting chimera technology to reduce navitoclax platelet toxicity and improve its senolytic activity

Small molecules that selectively kill senescent cells (SCs), termed senolytics, have the potential to prevent and treat various age-related diseases and extend healthspan. The use of Bcl-xl inhibitors as senolytics is largely limited by their on-target and dose-limiting platelet toxicity. Here, we report the use of proteolysis-targeting chimera (PROTAC) technology to reduce the platelet toxicity of navitoclax (also known as ABT263), a Bcl-2 and Bcl-xl dual inhibitor, by converting it into PZ15227 (PZ), a Bcl-xl PROTAC, which targets Bcl-xl to the cereblon (CRBN) E3 ligase for degradation. Compared to ABT263, PZ is less toxic to platelets, but equally or slightly more potent against SCs because CRBN is poorly expressed in platelets. PZ effectively clears SCs and rejuvenates tissue stem and progenitor cells in naturally aged mice without causing severe thrombocytopenia. With further improvement, Bcl-xl PROTACs have the potential to become safer and more potent senolytic agents than Bcl-xl inhibitors.

Stability of natural polyphenol fisetin in eye drops Stability of fisetin in eye drops

Fisetin is a polyphenolic compound with anti-inflammatory and antioxidant properties. Inflammation and reactive oxygen species play a major role in the pathophysiology of the dry eye syndrome (DES). Patients with DES undergo symptomatic treatment using eye drops known as artificial tears. Addition of fisetin into the eye drops could result in a better recovery of the eye surface. This experimental study examines the stability of fisetin in selected eye drops (Arufil, Hypromelóza-P, Ocutein, Refresh). Absorption spectra of fisetin were measured in selected eye drops, dimethylsulphoxide (DMSO), deionized water and normal saline solution (NSS) during a period of four weeks. The fisetin absorption maximum was placed at 350 – 390 nm depending on the solvent. Good stability of fisetin solutions were observed in DMSO and deionized water. The highest stability of fisetin in selected eye drops was observed in Hypromelóza-P. Irreversible fisetin structural changes were detected in Arufil, Ocutein, Refresh and NSS. For further clinical evaluation, fisetin solution in Hypromelóza-P could be examined.

Reducing Senescent Cell Burden in Aging and Disease

Cellular senescence is a primary aging process and tumor suppressive mechanism characterized by irreversible growth arrest, apoptosis resistance, production of a senescence-associated secretory phenotype (SASP), mitochondrial dysfunction, and alterations in DNA and chromatin. In preclinical aging models, accumulation of senescent cells is associated with multiple chronic diseases and disorders, geriatric syndromes, multimorbidity, and accelerated aging phenotypes. In animals, genetic and pharmacologic reduction of senescent cell burden results in the prevention, delay, and/or alleviation of a variety of aging-related diseases and sequelae. Early clinical trials have thus far focused on safety and target engagement of senolytic agents that clear senescent cells. We hypothesize that these pharmacologic interventions may have transformative effects on geriatric medicine.

Heterochronic parabiosis regulates the extent of cellular senescence in multiple tissues

An increase in the burden of senescent cells in tissues with age contributes to driving aging and the onset of age-related diseases. Genetic and pharmacologic elimination of senescent cells extends both health span and life span in mouse models. Heterochronic parabiosis in mice has been used to identify bloodborne, circulating pro- and anti-geronic factors able to drive or slow aging, respectively. However, whether factors in the circulation also regulate senescence is unknown. Here, we measured the expression of senescence and senescence-associated secretory phenotype (SASP) markers in multiple tissues from 4- to 18-month-old male mice that were either isochronically or heterochronically paired for 2 months. In heterochronic parabionts, the age-dependent increase in senescence and SASP marker expression was reduced in old mice exposed to a young environment, while senescence markers were concurrently increased in young heterochronic parabionts. These findings were supported by geropathology analysis using the Geropathology Grading Platform that showed a trend toward reduced hepatic lesions in old heterochronic parabionts. In summary, these results demonstrate that senescence is regulated in part by circulating geronic factors and suggest that one of the possible mediators of the rejuvenating effects with heterochronic parabiosis is through the reduction of the senescent cell burden.

An Appraisal on the Value of Using Nutraceutical Based Senolytics and Senostatics in Aging

The average human life expectancy has increased globally, and continues to rise, owing to the substantive progress made in healthcare, medicine, sanitation, housing and education. This ultimately enriches society with a greater proportion of elderly people. Sustaining a healthy aged population is key to diminish the societal and economic impact of age-related infirmities. This is especially challenging because tissue function, and thus wellbeing, naturally progressively decline as humans age. With age increasing the risk of developing diseases, one of the therapeutic options is to interfere with the molecular and cellular pathways involved in age-related tissue dysfunction, which is in part caused by the accumulation of senescent cells. One strategy to prevent this could be using drugs that selectively kill these cells (senolytics). In parallel, some compounds have been identified that prevent or slow down the progression of senescence or some of its features (senostatics). Senolytic and senostatic therapies have been shown to be efficient in vivo, but they also have unwanted dose-dependent side effects, including toxicity. Important advances might be made using bioactive compounds from plants and foods (nutraceuticals) if, as is proposed, they offer similar effectiveness with fewer side effects. The focus of this review is on the use of nutraceuticals in interfering with cellular senescence.

Galacto-conjugation of Navitoclax as an efficient strategy to increase senolytic specificity and reduce platelet toxicity

Pharmacologically active compounds with preferential cytotoxic activity for senescent cells, known as senolytics, can ameliorate or even revert pathological manifestations of senescence in numerous preclinical mouse disease models, including cancer models. However, translation of senolytic therapies to human disease is hampered by their suboptimal specificity for senescent cells and important toxicities that narrow their therapeutic windows. We have previously shown that the high levels of senescence-associated lysosomal β-galactosidase (SA-β-gal) found within senescent cells can be exploited to specifically release tracers and cytotoxic cargoes from galactose-encapsulated nanoparticles within these cells. Here, we show that galacto-conjugation of the BCL-2 family inhibitor Navitoclax results in a potent senolytic prodrug (Nav-Gal), that can be preferentially activated by SA-β-gal activity in a wide range of cell types. Nav-Gal selectively induces senescent cell apoptosis and has a higher senolytic index than Navitoclax (through reduced activation in nonsenescent cells). Nav-Gal enhances the cytotoxicity of standard senescence-inducing chemotherapy (cisplatin) in human A549 lung cancer cells. Concomitant treatment with cisplatin and Nav-Gal in vivo results in the eradication of senescent lung cancer cells and significantly reduces tumour growth. Importantly, galacto-conjugation reduces Navitoclax-induced platelet apoptosis in human and murine blood samples treated ex vivo, and thrombocytopenia at therapeutically effective concentrations in murine lung cancer models. Taken together, we provide a potentially versatile strategy for generating effective senolytic prodrugs with reduced toxicities.

Cellular Senescence as a Therapeutic Target for Age-Related Diseases: A Review

Life expectancy has increased substantially over the last few decades, leading to a worldwide increase in the prevalence and burden of aging-associated diseases. Recent evidence has proven that cellular senescence contributes substantially to the development of these disorders. Cellular senescence is a state of cell cycle arrest with suppressed apoptosis and concomitant secretion of multiple bioactive factors (the senescence-associated secretory phenotype-SASP) that plays a physiological role in embryonic development and healing processes. However, DNA damage and oxidative stress that occur during aging cause the accumulation of senescent cells, which through their SASP bring about deleterious effects on multiple organ and systemic functions. Ablation of senescent cells through genetic or pharmacological means leads to improved life span and health span in animal models, and preliminary evidence suggests it may also have a positive impact on human health. Thus, strategies to reduce or eliminate the burden of senescent cells or their products have the potential to impact multiple clinical outcomes with a single intervention. In this review, we touch upon the basics of cell senescence and summarize the current state of development of therapies against cell senescence for human use.

Therapy-Induced Senescence: An "Old" Friend Becomes the Enemy

For the past two decades, cellular senescence has been recognized as a central component of the tumor cell response to chemotherapy and radiation. Traditionally, this form of senescence, termed Therapy-Induced Senescence (TIS), was linked to extensive nuclear damage precipitated by classical genotoxic chemotherapy. However, a number of other forms of therapy have also been shown to induce senescence in tumor cells independently of direct genomic damage. This review attempts to provide a comprehensive summary of both conventional and targeted anticancer therapeutics that have been shown to induce senescence in vitro and in vivo. Still, the utility of promoting senescence as a therapeutic endpoint remains under debate. Since senescence represents a durable form of growth arrest, it might be argued that senescence is a desirable outcome of cancer therapy. However, accumulating evidence suggesting that cells have the capacity to escape from TIS would support an alternative conclusion, that senescence provides an avenue whereby tumor cells can evade the potentially lethal action of anticancer drugs, allowing the cells to enter a temporary state of dormancy that eventually facilitates disease recurrence, often in a more aggressive state. Furthermore, TIS is now strongly connected to tumor cell remodeling, potentially to tumor dormancy, acquiring more ominous malignant phenotypes and accounts for several untoward adverse effects of cancer therapy. Here, we argue that senescence represents a barrier to effective anticancer treatment, and discuss the emerging efforts to identify and exploit agents with senolytic properties as a strategy for elimination of the persistent residual surviving tumor cell population, with the goal of mitigating the tumor-promoting influence of the senescent cells and to thereby reduce the likelihood of cancer relapse.

Discovery, development, and future application of senolytics: theories and predictions

Senescent cells accumulate with aging and at etiological sites of multiple diseases, including those accounting for most morbidity, mortality, and health costs. Senescent cells do not replicate, can release factors that cause tissue dysfunction, and yet remain viable. The discovery of senolytic drugs, agents that selectively eliminate senescent cells, created a new route for alleviating age‐related dysfunction and diseases. As anticipated for agents targeting fundamental aging mechanisms that are ‘root cause’ contributors to multiple disorders, potential applications of senolytics are protean. We review the discovery of senolytics, strategies for translation into clinical application, and promising early signals from clinical trials.

Immune Clearance of Senescent Cells to Combat Ageing and Chronic Diseases

Senescent cells are generally characterized by permanent cell cycle arrest, metabolic alteration and activation, and apoptotic resistance in multiple organs due to various stressors. Excessive accumulation of senescent cells in numerous tissues leads to multiple chronic diseases, tissue dysfunction, age-related diseases and organ ageing. Immune cells can remove senescent cells. Immunaging or impaired innate and adaptive immune responses by senescent cells result in persistent accumulation of various senescent cells. Although senolytics-drugs that selectively remove senescent cells by inducing their apoptosis-are recent hot topics and are making significant research progress, senescence immunotherapies using immune cell-mediated clearance of senescent cells are emerging and promising strategies to fight ageing and multiple chronic diseases. This short review provides an overview of the research progress to date concerning senescent cell-caused chronic diseases and tissue ageing, as well as the regulation of senescence by small-molecule drugs in clinical trials and different roles and regulation of immune cells in the elimination of senescent cells. Mounting evidence indicates that immunotherapy targeting senescent cells combats ageing and chronic diseases and subsequently extends the healthy lifespan.

The Emerging Role of Senescence in Ocular Disease

Cellular senescence is a state of irreversible cell cycle arrest in response to an array of cellular stresses. An important role for senescence has been shown for a number of pathophysiological conditions that include cardiovascular disease, pulmonary fibrosis, and diseases of the skin. However, whether senescence contributes to the progression of age-related macular degeneration (AMD) has not been studied in detail so far and the present review describes the recent research on this topic. We present an overview of the types of senescence, pathways of senescence, senescence-associated secretory phenotype (SASP), the role of mitochondria, and their functional implications along with antisenescent therapies. As a central mechanism, senescent cells can impact the surrounding tissue microenvironment via the secretion of a pool of bioactive molecules, termed the SASP. An updated summary of a number of new members of the ever-growing SASP family is presented. Further, we introduce the significance of mechanisms by which mitochondria may participate in the development of cellular senescence. Emerging evidence shows that extracellular vesicles (EVs) are important mediators of the effects of senescent cells on their microenvironment. Based on recent studies, there is reasonable evidence that senescence could be a modifiable factor, and hence, it may be possible to delay age-related diseases by modulating basic aging mechanisms using SASP inhibitors/senolytic drugs. Thus, antisenescent therapies in aging and age-related diseases appear to have a promising potential.

Tissue specificity of senescent cell accumulation during physiologic and accelerated aging of mice

Senescent cells accumulate with age in vertebrates and promote aging largely through their senescence‐associated secretory phenotype (SASP). Many types of stress induce senescence, including genotoxic stress. ERCC1‐XPF is a DNA repair endonuclease required for multiple DNA repair mechanisms that protect the nuclear genome. Humans or mice with reduced expression of this enzyme age rapidly due to increased levels of spontaneous, genotoxic stress. Here, we asked whether this corresponds to an increased level of senescent cells. p16^Ink4a and p21^Cip1 mRNA were increased ~15‐fold in peripheral lymphocytes from 4‐ to 5‐month‐old Ercc1^−/∆ and 2.5‐year‐old wild‐type (WT) mice, suggesting that these animals exhibit a similar biological age. p16^Ink4a and p21^Cip1 mRNA were elevated in 10 of 13 tissues analyzed from 4‐ to 5‐month‐old Ercc1^−/∆ mice, indicating where endogenous DNA damage drives senescence in vivo. Aged WT mice had similar increases of p16^Ink4a and p21^Cip1 mRNA in the same 10 tissues as the mutant mice. Senescence‐associated β–galactosidase activity and p21^Cip1 protein also were increased in tissues of the progeroid and aged mice, while Lamin B1 mRNA and protein levels were diminished. In Ercc1^−/Δ mice with a p16^Ink4a luciferase reporter, bioluminescence rose steadily with age, particularly in lung, thymus, and pancreas. These data illustrate where senescence occurs with natural and accelerated aging in mice and the relative extent of senescence among tissues. Interestingly, senescence was greater in male mice until the end of life. The similarities between Ercc1^−/∆ and aged WT mice support the conclusion that the DNA repair‐deficient mice accurately model the age‐related accumulation of senescent cells, albeit six‐times faster.

Fruits

Fruits come in a wide variety of colors, shapes, and flavors. This chapter will cover selected fruits that are known to be healthy and highly nutritious. These fruits were chosen due to their common usage and availability. Since it is not possible to cover all health benefits or essential nutrients and important phytochemicals of the fruit composition, this chapter will focus on the key valuable constituents and their potential health effects.

A toolbox for the longitudinal assessment of healthspan in aging mice

The number of people aged over 65 is expected to double in the next 30 years. For many, living longer will mean spending more years with the burdens of chronic diseases such as Alzheimer's disease, cardiovascular disease, and diabetes. Although researchers have made rapid progress in developing geroprotective interventions that target mechanisms of aging and delay or prevent the onset of multiple concurrent age-related diseases, a lack of standardized techniques to assess healthspan in preclinical murine studies has resulted in reduced reproducibility and slow progress. To overcome this, major centers in Europe and the United States skilled in healthspan analysis came together to agree on a toolbox of techniques that can be used to consistently assess the healthspan of mice. Here, we describe the agreed toolbox, which contains protocols for echocardiography, novel object recognition, grip strength, rotarod, glucose tolerance test (GTT) and insulin tolerance test (ITT), body composition, and energy expenditure. The protocols can be performed longitudinally in the same mouse over a period of 4-6 weeks to test how candidate geroprotectors affect cardiac, cognitive, neuromuscular, and metabolic health.

Can Medicinal Plants and Bioactive Compounds Combat Lipid Peroxidation Product 4-HNE-Induced Deleterious Effects?

The toxic reactive aldehyde 4-hydroxynonenal (4-HNE) belongs to the advanced lipid peroxidation end products. Accumulation of 4-HNE and formation of 4-HNE adducts induced by redox imbalance participate in several cytotoxic processes, which contribute to the pathogenesis and progression of oxidative stress-related human disorders. Medicinal plants and bioactive natural compounds are suggested to be attractive sources of potential agents to mitigate oxidative stress, but little is known about the therapeutic potentials especially on combating 4-HNE-induced deleterious effects. Of note, some investigations clarify the attenuation of medicinal plants and bioactive compounds on 4-HNE-induced disturbances, but strong evidence is needed that these plants and compounds serve as potent agents in the prevention and treatment of disorders driven by 4-HNE. Therefore, this review highlights the pharmacological basis of these medicinal plants and bioactive compounds to combat 4-HNE-induced deleterious effects in oxidative stress-related disorders, such as neurotoxicity and neurological disorder, eye damage, cardiovascular injury, liver injury, and energy metabolism disorder. In addition, this review briefly discusses with special attention to the strategies for developing potential therapies by future applications of these medicinal plants and bioactive compounds, which will help biological and pharmacological scientists to explore the new vistas of medicinal plants in combating 4-HNE-induced deleterious effects.

Berberine ameliorates cellular senescence and extends the lifespan of mice via regulating p16 and cyclin protein expression

Although aging and senescence have been extensively studied in the past few decades, however, there is lack of clinical treatment available for anti‐aging. This study presents the effects of berberine (BBR) on the aging process resulting in a promising extension of lifespan in model organisms. BBR extended the replicative lifespan, improved the morphology, and boosted rejuvenation markers of replicative senescence in human fetal lung diploid fibroblasts (2BS and WI38). BBR also rescued senescent cells with late population doubling (PD). Furthermore, the senescence‐associated β‐galactosidase (SA‐β‐gal)‐positive cell rates of late PD cells grown in the BBR‐containing medium were ~72% lower than those of control cells, and its morphology resembled that of young cells. Mechanistically, BBR improved cell growth and proliferation by promoting entry of cell cycles from the G₀ or G₁ phase to S/G₂‐M phase. Most importantly, BBR extended the lifespan of chemotherapy‐treated mice and naturally aged mice by ~52% and ~16.49%, respectively. The residual lifespan of the naturally aged mice was extended by 80%, from 85.5 days to 154 days. The oral administration of BBR in mice resulted in significantly improved health span, fur density, and behavioral activity. Therefore, BBR may be an ideal candidate for the development of an anti‐aging medicine.

Flavonoid fisetin alleviates kidney inflammation and apoptosis via inhibiting Src-mediated NF-κB p65 and MAPK signaling pathways in septic AKI mice

BACKGROUND

Sepsis is defined as end-organ dysfunction resulting from the host's inflammatory response to infection. One of the most common sepsis-injured organs is the kidneys, resulting in acute kidney injury (AKI) that contributes to the high morbidity and mortality, especially patients in the intensive care unit. Fisetin, a naturally occurring flavonoid, has been reported to protect against the rat of lipopolysaccharide (LPS)-induced acute lung injury. However, the effect of fisetin on septic AKI remains unknown.

PURPOSE

The current study proposed to systematically investigate the renoprotective effects and the underlying mechanisms of fisetin in septic AKI mice.

METHODS

The model of septic AKI was established on male C57BL/6 J mice by a single intraperitoneal injection of LPS (10 mg/kg). Fisetin was administrated by gavage at 100 mg/kg for 3 consecutive days before LPS injection and the mice were sacrificed at 16 h after LPS injection. The serum and kidney samples were evaluated for biochemical analysis, histopathological examinations as well as inflammation and apoptosis related gene/protein expression.

RESULTS

Pretreatment with fisetin significantly alleviated the elevated levels of serum creatinine and blood urea nitrogen in LPS-treated mice. Consistently, LPS induced renal damage as implied by histopathological score and the increased injury markers NGAL and KIM-1, which was attenuated by fisetin. Meanwhile, LPS injection triggered proinflammatory cytokine production and inflammation related proteins in the kidneys. However, fisetin inhibited renal expression of IL-6, IL-1β, TNF-α, HMGB1, iNOS and COX-2 to improve inflammatory response. Furthermore, fisetin effectively reduced the number of TUNEL positive apoptotic cells and suppressed apoptotic protein of Bcl-2, BAX and cleaved caspase-3 in the kidneys of LPS-induced septic AKI. Mechanistically, LPS stimulated the expression of TLR4 and the phosphorylation of NF-κB p65, MAPK (p38, ERK1/2 and JNK), Src and AKT in the injured kidneys, while fisetin notably suppressed the corresponding protein expression.

CONCLUSION

Fisetin alleviated kidney inflammation and apoptosis to protect against LPS-induced septic AKI mice via inhibiting Src-mediated NF-κB p65 and MAPK signaling pathways.

Targeting senescent cells in translational medicine

Organismal ageing is a complex process driving progressive impairment of functionality and regenerative potential of tissues. Cellular senescence is a state of stable cell cycle arrest occurring in response to damage and stress and is considered a hallmark of ageing. Senescent cells accumulate in multiple organs during ageing, contribute to tissue dysfunction and give rise to pathological manifestations. Senescence is therefore a defining feature of a variety of human age-related disorders, including cancer, and targeted elimination of these cells has recently emerged as a promising therapeutic approach to ameliorate tissue damage and promote repair and regeneration. In addition, in vivo identification of senescent cells has significant potential for early diagnosis of multiple pathologies. Here, we review existing senolytics, small molecules and drug delivery tools used in preclinical therapeutic strategies involving cellular senescence, as well as probes to trace senescent cells. We also review the clinical research landscape in senescence and discuss how identifying and targeting cellular senescence might positively affect pathological and ageing processes.

Aging: therapeutics for a healthy future

Increased healthcare and pharmaceutical understanding has led to the eradication of many childhood, infectious and preventable diseases; however, we are now experiencing the impact of aging disorders as the lifespan increases. These disorders have already become a major burden on society and threaten to become a defining challenge of our generation. Indications such as Alzheimer's disease gain headlines and have focused the thinking of many towards dementia and cognitive decline in aging. Indications related to neurological function and related behaviors are thus an extremely important starting point in the consideration of therapeutics.However, the reality is that pathological aging covers a spectrum of significant neurological and peripheral indications. Development of therapeutics to treat aging and age-related disorders is therefore a huge need, but represents a largely unexplored path. Fundamental scientific questions need to be considered as we embark towards a goal of improving health in old age, including how we 1) define aging as a therapeutic target, 2) model aging preclinically and 3) effectively translate from preclinical models to man. Furthermore, the challenges associated with identifying novel therapeutics in a financial, regulatory and clinical sense need to be contemplated carefully to ensure we address the unmet need in our increasingly elderly population. The complexity of the challenge requires different perspectives, cross-functional partnerships and diverse concepts. We seek to raise issues to guide the field, considering the current state of thinking to aid in identifying roadblocks and important challenges early. The need for therapeutics that address aging and age-related disorders is acute, but the promise of effective treatments provides huge opportunities that, as a community, we all seek to enable effectively as soon as possible.

Natural Bioactive Compounds As Protectors Of Mitochondrial Dysfunction In Cardiovascular Diseases And Aging

Diet, particularly the Mediterranean diet, has been considered as a protective factor against the development of cardiovascular diseases, the main cause of death in the world. Aging is one of the major risk factors for cardiovascular diseases, which have an oxidative pathophysiological component, being the mitochondria one of the key organelles in the regulation of oxidative stress. Certain natural bioactive compounds have the ability to regulate oxidative phosphorylation, the production of reactive oxygen species and the expression of mitochondrial proteins; but their efficacy within the mitochondrial physiopathology of cardiovascular diseases has not been clarified yet. The following review has the purpose of evaluating several natural compounds with evidence of mitochondrial effect in cardiovascular disease models, ascertaining the main cellular mechanisms and their potential use as functional foods for prevention of cardiovascular disease and healthy aging.

Mechanisms of aging and potential role of selected polyphenols in extending healthspan

Aging became a priority in medicine due to the rapid increase of elderly population and age-related diseases in the Western countries. Nine hallmarks have been identified based on their alteration during aging and their capacity to increase longevity. The pathways and the molecular mechanisms to improve lifespan and healthspan are controlled by behavioral, pharmacologic and dietary factors, which remain largely unknown. Among them, naturally occurring compounds, such as polyphenols, are considered potential antiaging agents, because of their ability to modulate some of the evolutionarily conserved hallmarks of aging, including oxidative damage, inflammation, cell senescence, and autophagy. Initially, these compounds gained researchers' attention due to their ability to extend the lifespan of simple model organisms. More recently, some of them have been proposed as senolytic agents to protect against age-related disorders, such as cancer, cardiovascular and neurodegenerative diseases. The intent of this review is to present the most validated molecular mechanisms regulating ageing and longevity and critically analyze how selected polyphenols, namely resveratrol, quercetin, curcumin and catechins, can interfere with these mechanisms.

Targeting normal and cancer senescent cells as a strategy of senotherapy

Senotherapy is an antiageing strategy. It refers to selective killing of senescent cells by senolytic agents, strengthening the activity of immune cells that eliminate senescent cells or alleviating the secretory phenotype (SASP) of senescent cells. As senescent cells accumulate with age and are considered to be at the root of age-related disorders, senotherapy seems to be very promising in improving healthspan. Genetic approaches, which allowed to selectively induce death of senescent cells in transgenic mice, provided proof-of-concept evidence that elimination of senescent cells can be a therapeutic approach for treating many age-related diseases. Translating these results into humans is based on searching for synthetic and natural compounds, which are able to exert such beneficial effects. The major challenge in the field is to show efficacy, safety and tolerability of senotherapy in humans. The question is how these therapeutics can influence senescence of non-dividing post-mitotic cells. Another issue concerns senescence of cancer cells induced during therapy as there is a risk of resumption of senescent cell division that could terminate in cancer renewal. Thus, development of an effective senotherapeutic strategy is also an urgent issue in cancer treatment. Different aspects, both beneficial and potentially detrimental, will be discussed in this review.

Cellular Senescence: Defining a Path Forward

Cellular senescence is a cell state implicated in various physiological processes and a wide spectrum of age-related diseases. Recently, interest in therapeutically targeting senescence to improve healthy aging and age-related disease, otherwise known as senotherapy, has been growing rapidly. Thus, the accurate detection of senescent cells, especially in vivo, is essential. Here, we present a consensus from the International Cell Senescence Association (ICSA), defining and discussing key cellular and molecular features of senescence and offering recommendations on how to use them as biomarkers. We also present a resource tool to facilitate the identification of genes linked with senescence, SeneQuest (available at http://Senequest.net). Lastly, we propose an algorithm to accurately assess and quantify senescence, both in cultured cells and in vivo.

New Perspectives for Fisetin

Fisetin is a flavonol that shares distinct antioxidant properties with a plethora of other plant polyphenols. Additionally, it exhibits a specific biological activity of considerable interest as regards the protection of functional macromolecules against stress which results in the sustenance of normal cells cytoprotection. Moreover, it shows potential as an anti-inflammatory, chemopreventive, chemotherapeutic and recently also senotherapeutic agent. In view of its prospective applications in healthcare and likely demand for fisetin, methods for its preparation and their suitability for pharmaceutical use are discussed herein.

Chemotherapy-induced cellular senescence suppresses progression of Notch-driven T-ALL

T cell acute lymphoblastic leukemia (T-ALL) is a serious hematologic malignancy that occurs in children and young adults. Current therapies include intensive chemotherapy and ionizing radiation that preferentially kill malignant cells. Unfortunately, they are frequently accompanied by unintended negative impacts, including the induction of cellular senescence and long-term toxicities in normal host tissues. Whether these senescent cells resulting from therapy increase the susceptibility to relapse or secondary cancers is unknown. Using transgenic and pharmacological approaches to eliminate doxorubicin-induced senescent cells in a Notch-driven T-ALL relapse mouse model, we find that these cells inhibit tumor recurrence, suggesting that senescence in response to treatment suppresses tumorigenesis. This finding, together with extensive evidence from others demonstrating that age-associated health problems develop dramatically earlier among childhood cancer survivors compared to age-matched counterparts, suggests a relationship between therapy-induced senescence and tumorigenesis. Although cancer risk is increased through accelerated premature-aging in the long run, therapy-induced senescence appears to protect survivors from recurrence, at least in the short run.

AMPK-mediated senolytic and senostatic activity of quercetin surface functionalized Fe3O4 nanoparticles during oxidant-induced senescence in human fibroblasts

Cellular senescence may contribute to aging and age-related diseases and senolytic drugs that selectively kill senescent cells may delay aging and promote healthspan. More recently, several categories of senolytics have been established, namely HSP90 inhibitors, Bcl-2 family inhibitors and natural compounds such as quercetin and fisetin. However, senolytic and senostatic potential of nanoparticles and surface-modified nanoparticles has never been addressed. In the present study, quercetin surface functionalized Fe₃O₄ nanoparticles (MNPQ) were synthesized and their senolytic and senostatic activity was evaluated during oxidative stress-induced senescence in human fibroblasts in vitro. MNPQ promoted AMPK activity that was accompanied by non-apoptotic cell death and decreased number of stress-induced senescent cells (senolytic action) and the suppression of senescence-associated proinflammatory response (decreased levels of secreted IL-8 and IFN-β, senostatic action). In summary, we have shown for the first time that MNPQ may be considered as promising candidates for senolytic- and senostatic-based anti-aging therapies.

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Quercetin surface functionalized magnetite nanoparticles (MNPQ) were synthesized.

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MNPQ eliminated hydrogen peroxide-induced senescent human fibroblasts.

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MNPQ limited senescence-associated proinflammatory responses.

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Senotherapeutic action of MNPQ was accompanied by increased activity of AMPK.

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MNPQ may be useful for senolytic- and senostatic-based anti-aging therapies.

Cellular senescence: at the nexus between ageing and diabetes

Ageing and diabetes lead to similar organ dysfunction that is driven by parallel molecular mechanisms, one of which is cellular senescence. The abundance of senescent cells in various tissues increases with age, obesity and diabetes. Senescent cells have been directly implicated in the generation of insulin resistance. Recently, drugs that preferentially target senescent cells, known as senolytics, have been described and recently entered clinical trials. In this review, we explore the biological links between ageing and diabetes, specifically focusing on cellular senescence. We summarise the current data on cellular senescence in key target tissues associated with the development and clinical phenotypes of type 2 diabetes and discuss the therapeutic potential of targeting cellular senescence in diabetes.

Loss of SATB1 Induces p21-Dependent Cellular Senescence in Post-mitotic Dopaminergic Neurons

Cellular senescence is a mechanism used by mitotic cells to prevent uncontrolled cell division. As senescent cells persist in tissues, they cause local inflammation and are harmful to surrounding cells, contributing to aging. Generally, neurodegenerative diseases, such as Parkinson's, are disorders of aging. The contribution of cellular senescence to neurodegeneration is still unclear. SATB1 is a DNA binding protein associated with Parkinson's disease. We report that SATB1 prevents cellular senescence in post-mitotic dopaminergic neurons. Loss of SATB1 causes activation of a cellular senescence transcriptional program in dopamine neurons both in human stem cell-derived dopaminergic neurons and in mice. We observed phenotypes that are central to cellular senescence in SATB1 knockout dopamine neurons in vitro and in vivo. Moreover, we found that SATB1 directly represses expression of the pro-senescence factor p21 in dopaminergic neurons. Our data implicate senescence of dopamine neurons as a contributing factor in the pathology of Parkinson's disease.

Senolytics decrease senescent cells in humans: Preliminary report from a clinical trial of Dasatinib plus Quercetin in individuals with diabetic kidney disease

Background

Senescent cells, which can release factors that cause inflammation and dysfunction, the senescence-associated secretory phenotype (SASP), accumulate with ageing and at etiological sites in multiple chronic diseases. Senolytics, including the combination of Dasatinib and Quercetin (D + Q), selectively eliminate senescent cells by transiently disabling pro-survival networks that defend them against their own apoptotic environment. In the first clinical trial of senolytics, D + Q improved physical function in patients with idiopathic pulmonary fibrosis (IPF), a fatal senescence-associated disease, but to date, no peer-reviewed study has directly demonstrated that senolytics decrease senescent cells in humans.

Methods

In an open label Phase 1 pilot study, we administered 3 days of oral D 100 mg and Q 1000 mg to subjects with diabetic kidney disease (N = 9; 68·7 ± 3·1 years old; 2 female; BMI:33·9 ± 2·3 kg/m²; eGFR:27·0 ± 2·1 mL/min/1·73m²). Adipose tissue, skin biopsies, and blood were collected before and 11 days after completing senolytic treatment. Senescent cell and macrophage/Langerhans cell markers and circulating SASP factors were assayed.

Findings

D + Q reduced adipose tissue senescent cell burden within 11 days, with decreases in p16^INK4A-and p21^CIP1-expressing cells, cells with senescence-associated β-galactosidase activity, and adipocyte progenitors with limited replicative potential. Adipose tissue macrophages, which are attracted, anchored, and activated by senescent cells, and crown-like structures were decreased. Skin epidermal p16^INK4A+ and p21^CIP1+ cells were reduced, as were circulating SASP factors, including IL-1α, IL-6, and MMPs-9 and −12.

Interpretation

“Hit-and-run” treatment with senolytics, which in the case of D + Q have elimination half-lives <11 h, significantly decreases senescent cell burden in humans.

Fund

NIH and Foundations.

ClinicalTrials.gov Identifier: NCT02848131. Senescence, Frailty, and Mesenchymal Stem Cell Functionality in Chronic Kidney Disease: Effect of Senolytic Agents.

Metformin and Aging: A Review

Metformin is sometimes proposed to be an "anti-aging" drug, based on preclinical experiments with lower-order organisms and numerous retrospective data on beneficial health outcomes for type 2 diabetics. Large prospective, placebo-controlled trials are planned, in pilot stage or running, to find a new use (or indication) for an aging population. As one of the metformin trials has "frailty" as its endpoint, similar to a trial with a plant-derived senolytic, the latter class of novel anti-aging drugs is briefly discussed. Concerns exist not only for vitamin B12 and B6 deficiencies, but also about whether there are adverse effects of metformin on individuals who try to remain healthy by maintaining cardiovascular fitness via exercise.

Endoplasmic reticulum stress-induced iRhom2 up-regulation promotes macrophage-regulated cardiac inflammation and lipid deposition in high fat diet (HFD)-challenged mice: Intervention of fisetin and metformin

Endoplasmic reticulum stress (ERS) has been implicated in obesity-associated cardiac remodeling and dysfunction. Inactive rhomboid protein 2 (iRhom2), also known as Rhbdf2, is an inactive member of the rhomboid intramembrane proteinase family, playing an essential role in regulating inflammation. Nevertheless, the role of ERS-meditated iRhom2 pathway in metabolic stress-induced cardiomyopathy remains unknown. In the study, we showed that 4-PBA, as an essential ERS inhibitor, significantly alleviated high fat diet (HFD)-induced metabolic disorder and cardiac dysfunction in mice. Additionally, lipid deposition in heart tissues was prevented by 4-PBA in HFD-challenged mice. Moreover, 4-PBA blunted the expression of iRhom2, TACE, TNFR2 and phosphorylated NF-κB to prevent HFD-induced expression of inflammatory factors. Further, 4-PBA restrained HFD-triggered oxidative stress by promoting Nrf-2 signaling. Importantly, 4-PBA markedly suppressed cardiac ERS in HFD mice. The anti-inflammation, anti-ERS and anti-oxidant effects of 4-PBA were verified in palmitate (PAL)-incubated macrophages and cardiomyocytes. In addition, promoting ERS could obviously enhance iRhom2 signaling in vitro. Intriguingly, our data demonstrated that PAL-induced iRhom2 up-regulation apparently promoted macrophage to generate inflammatory factors that could promote cardiomyocyte inflammation and lipid accumulation. Finally, interventions by adding fisetin or metformin significantly abrogated metabolic stress-induced cardiomyopathy through the mechanisms mentioned above. In conclusion, this study provided a novel mechanism for metabolic stress-induced cardiomyopathy pathogenesis. Therapeutic strategy to restrain ROS/ERS/iRhom2 signaling pathway could be developed to prevent myocardial inflammation and lipid deposition, consequently alleviating obesity-induced cardiomyopathy.

Controlled induction and targeted elimination of p16INK4a-expressing chondrocytes in cartilage explant culture

Cellular senescence is a phenotypic state that contributes to age-related diseases through the secretion of matrix-degrading and inflammatory molecules. An emerging therapeutic strategy for osteoarthritis (OA) is to selectively eliminate senescent cells by initiating apoptosis. This study establishes a cartilage explant model of senescence induction and senolytic clearance using p16^Ink4a expression as a biomarker of senescence. Growth-factor stimulation of explants increased the expression of p16^Ink4a at both the mRNA and protein levels. Applying this culture system to cartilage from p16tdTom reporter mice (a knockin allele with tdTomato fluorescent protein regulated by the endogenous p16Ink4a promoter) demonstrated the emergence of a p16-high population that was quantified using flow cytometry for tdTomato. Cell sorting was used to separate chondrocytes based on tdTomato fluorescence and p16-high cells showed higher senescence-associated β-galactosidase activity and increased gene expression of the senescence-associated secretory phenotype as compared with p16-low cells. The potential for effective senolysis within the cartilage extracellular matrix was assessed using navitoclax (ABT-263). Navitoclax treatment reduced the percentage of p16-high cells from 17.9 to 6.1% (mean of 13 matched pairs; P < 0.001) and increased cleaved caspase-3 confirmed apoptotic activity. Together, these findings establish a physiologically relevant cartilage explant model for testing the induction and elimination of senescent chondrocytes, which will support investigations of senolytic therapy for OA.-Sessions, G. A., Copp, M. E., Liu, J.-Y., Sinkler, M. A., D'Costa, S., Diekman, B. O. Controlled induction and targeted elimination of p16^INK4a-expressing chondrocytes in cartilage explant culture.

Recent advances in understanding the mechanisms determining longevity

The field of aging research has progressed significantly over the past decades. Exogenously and endogenously inflicted molecular damage ranging from genotoxic to organellar damage drives the aging process. Repair mechanisms and compensatory responses counteract the detrimental consequences of the various damage types. Here, we discuss recent progress in understanding cellular mechanisms and interconnections between signaling pathways that control longevity. We summarize cell-autonomous and non-cell-autonomous mechanisms that impact the cellular and organismal aging process

Inflammation in atherosclerotic cardiovascular disease

Atherosclerotic cardiovascular disease is a leading cause of death and morbidity globally. Over the past several years, arterial inflammation has been implicated in the pathophysiology of athero-thrombosis, substantially confirming what pathologist Rudolf Virchow had observed in the 19th century. Lipid lowering, lifestyle changes, and modification of other risk factors have reduced cardiovascular complications of athero-thrombosis, but a substantial residual risk remains. In view of the pathogenic role of inflammation in athero-thrombosis, directly targeting inflammation has emerged as an additional potential therapeutic option; and some early promising results have been suggested by the Canakinumab Anti-inflammatory Thrombosis Outcome Study (CANTOS), in which canakinumab, a fully human monoclonal antibody targeting the pro-inflammatory and pro-atherogenic cytokine interleukin 1 beta, was shown to reduce cardiovascular events.

Murine models of accelerated aging and musculoskeletal disease

The primary risk factor for most musculoskeletal diseases, including osteoarthritis, osteoporosis and sarcopenia, is aging. To treat the diverse types of musculoskeletal diseases and pathologies, targeting their root cause, the aging process itself, has the potential to slow or prevent multiple age-related musculoskeletal conditions simultaneously. However, the development of approaches to delay onset of age related diseases, including musculoskeletal pathologies, has been slowed by the relatively long lifespan of rodent models of aging. Thus, to expedite the development of therapeutic approaches for age-related musculoskeletal disease, the implementation of mouse models of accelerated musculoskeletal aging are of great utility. Currently there are multiple genetically diverse mouse models that mirror certain aspects of normal human and mouse aging. Here, we provide a review of some of the most relevant murine models of accelerated aging that mimic many aspects of natural musculoskeletal aging, highlighting their relative strengths and weaknesses. Importantly, these murine models of accelerated aging recapitulate phenotypes of musculoskeletal age-related decline observed in humans.

Cellular Senescence and the Kidney: Potential Therapeutic Targets and Tools

Chronic kidney disease (CKD) is an increasing health burden (affecting approximately 13.4% of the population). Currently, no curative treatment options are available and treatment is focused on limiting the disease progression. The accumulation of senescent cells has been implicated in the development of kidney fibrosis by limiting tissue rejuvenation and through the secretion of pro-fibrotic and pro-inflammatory mediators termed as the senescence-associated secretory phenotype. The clearance of senescent cells in aging models results in improved kidney function, which shows promise for the options of targeting senescent cells in CKD. There are several approaches for the development of “senotherapies”, the most rigorous of which is the elimination of senescent cells by the so-called senolytic drugs either newly developed or repurposed for off-target effects in terms of selectively inducing apoptosis in senescent cells. Several chemotherapeutics and checkpoint inhibitors currently used in daily oncological practice show senolytic properties. However, the applicability of such senolytic compounds for the treatment of renal diseases has hardly been investigated. A serious concern is that systemic side effects will limit the use of senolytics for kidney fibrosis. Specifically targeting senescent cells and/or targeted drug delivery to the kidney might circumvent these side effects. In this review, we discuss the connection between CKD and senescence, the pharmacological options for targeting senescent cells, and the means to specifically target the kidney.