Elimination Of Senescent Cells Research Articles

8433 Elucidation of the Molecular Basis of Human and Mouse Pancreatic β-Cell Senescence Induced by Hyperglycemia

Abstract Disclosure: K. Iwasaki: None. P. Carapeto: None. C. Aguayo-Mazzucato: None. Background and AIM: Senescent cells accumulate with age and contribute to the development of chronic diseases, including Type 2 Diabetes (T2D). Whereas senescence is an important pathogenic mechanism in diabetes, the role of hyperglycemia as a metabolic driver of pancreatic β-cells has not been clarified. The aim of this study is to elucidate the molecular basis of hyperglycemia-induced pancreatic β-cell senescence using human and rodent islets. Methods: 1) Human islets were cultured for 2 weeks in 20.2 mM high (HG) or 2.8mM low glucose (LG), and analyzed by qPCR and glucose-responsive insulin secretion (GSIS) to explore the molecular basis of senescence in ex vivo. To test the effects of senescent cell removal, senolytics Dasatinib (1μM) and Quercetin (20μM) (DQ) were used. 2) To evaluate the effects of hyperglycemia in vivo, we transplanted mouse and human islets under the kidney capsule of normoglycemic (NG) or streptozocin-induced hyperglycemic (Stz-Db) immunodeficient mice for two weeks. Graft function was evaluated by intraperitoneal glucose tolerance test and cellular identity using qPCR or immunohistochemistry. DQ (5mg/kg/day + 50mg/kg/day) was used to evaluate the effects of removing senescent cells in transplantation (Tx). To investigate the effect of specific removal of p16-positive senescent β-cells in transplanted islets, INK-ATTAC mice islets (p16Ink4a-mediated apoptosis by targeted activation of caspases) were transplanted into Stz-Db and treated with BB homodimer (BB) to remove p16+ cells or vehicle. Results: (1) Human islets from 5 healthy donors cultured in HG had an increased senescence index (mean of senescence markers p16, p21 and HMGB1 mRNA) when compared to LG islets (p<0.05) and lost glucose responsiveness as evaluated by ex vivo GSIS compared to LG (p<0.05). 2) Human islets (1000IEQ) were transplanted to Stz-Db or NG mice. In Stz-Db graft, P21 mRNA significantly increased with decreased expression of β-cell genes when compared to NG. Stz-Db mice treated with DQ (Db-DQ) for 5 days after Tx, significantly decreased expression of senescence index (p<0.05) and increased in β-cell index (mean of β-cell hallmark genes) (p<0.05) at mRNA levels. Stz-Db mice transplanted with INK-ATTAC mice islets had lower fed glucose levels, decreased p16 mRNA, increased expression β-cell hallmark genes and improved insulin secretion ex vivo after removal of p16+ cells. Conclusion: Sustained exposure of human islets to hyperglycemia induced cellular senescence, leading to pancreatic β-cell dysfunction and loss of cellular identity. Furthermore, elimination of senescent cells may protect pancreatic β-cells from hyperglycemia-induced functional decline, which may have potential clinical application in both Type 1 Diabetes and T2D. Presentation: 6/2/2024

Senolytic effect of triterpenoid complex from Ganoderma lucidum on adriamycin-induced senescent human hepatocellular carcinoma cells model in vitro and in vivo.

Ganoderma lucidum (G. lucidum) is a famous medicinal mushroom that has been reported to prevent and treat a variety of diseases. Different extractions from G. lucidum have been used to manage age-related diseases, including cancer. Nevertheless, the senolytic activity of G. lucidum against senescent cancer cells has not been investigated. Although cellular senescence causes tumor growth inhibition, senescent cells promote the growth of the neighboring tumor cells through paracrine effects. Therefore, the elimination of senescent cells is a new strategy for cancer treatment. In this study, senescence was triggered in HCC cells by the chemotherapeutic agent Adriamycin (ADR), and subsequently, cells were treated with TC to assess its senolytic activity. We found for the first time that the triterpenoid complex (TC) from G. lucidum had senolytic effect, which could selectively eliminate adriamycin (ADR)-induced senescent cells (SCs) of hepatocellular carcinoma (HCC) cells via caspase-dependent and mitochondrial pathways-mediated apoptosis and reduce the levels of senescence markers, thereby inhibiting the progression of cancers caused by SCs. TC could block autophagy at the late stage in SCs, resulting in a significant activation of TC-induced apoptosis. Furthermore, TC inhibited the senescence-associated secretory phenotype (SASP) in SCs through the inhibition of NF-κB, TFEB, P38, ERK, and mTOR signaling pathways and reducing the number of SCs. Sequential administration of ADR and TC in vivo significantly reduced tumor growth and reversed the toxicity of ADR. A triterpenoid complex isolated from G. lucidum may serve as a novel senolytic agent against SCs, and its combination with chemotherapeutic agents may enhance their antitumor efficacy.

Resistance training suppresses accumulation of senescent fibro-adipogenic progenitors and senescence-associated secretory phenotype in aging rat skeletal muscle

AbstractAccumulation of senescent cells in tissues contributes to multiple aging-related pathologies. Senescent fibro-adipogenic progenitors (FAPs) contribute to aging-related muscle atrophy. Resistance training can help to maintain skeletal muscle mass, improve mobility, and reduce certain health risks commonly associated with aging. We investigated, using rat model, the impact of resistance training on FAPs in aging skeletal muscle, which remains unclear. Twenty-two-month-old female rats were divided into sedentary and training groups. The training group rodents were trained to climb a ladder while bearing a load for 20 training sessions over 2 months, after which, the flexor hallucis longus muscles were collected and analyzed. Senescent cells were identified using a senescence-associated β-galactosidase stain and p21 immunohistochemistry (IHC), and FAPs were identified using platelet-derived growth factor receptor alpha IHC. The results indicate that resistance training in rats prevented aging-associated skeletal muscle atrophy and suppressed M2 polarization of macrophages. The number of senescent cells was significantly reduced in the 24-month-old training group, with most of them being FAPs. Conversely, the number of senescent FAPs increased significantly in the 24-month-old sedentary group compared with that in the 18-month-old sedentary group. The number of senescent FAPs in the 24-month-old training group decreased significantly. Resistance training also suppressed the senescence-associated secretory phenotype (SASP). The killer T cell-specific marker, CD8α, was elevated in the skeletal muscles of the aging rats following resistance training, indicating upregulation of recognition and elimination of senescent cells. Overall, resistance training suppressed the accumulation of senescent FAPs and acquisition of SASP in aging skeletal muscles.

Defective autophagy of pericytes enhances radiation-induced senescence promoting radiation brain injury.

Radiation-induced brain injury (RBI) represents a major challenge for cancer patients undergoing cranial radiotherapy. However, the molecular mechanisms and therapeutic strategies of RBI remain inconclusive. With the continuous exploration of the mechanisms of RBI, an increasing number of studies have implicated cerebrovascular dysfunction as a key factor in RBI-related cognitive impairment. As pericytes are a component of the neurovascular unit, there is still a lack of understanding in current research about the specific role and function of pericytes in RBI. We constructed a mouse model of RBI-associated cognitive dysfunction in vivo and an in vitro radiation-induced pericyte model to explore the effects of senescent pericytes on the blood-brain barrier and normal CNS cells, even glioma cells. To further clarify the effects of pericyte autophagy on senescence, molecular mechanisms were explored at the animal and cellular levels. Finally, we validated the clearance of pericyte senescence by using senolytic drug and all-trans retinoic acid to investigate the role of radiation-induced pericyte senescence. Our findings indicated that radiation-induced pericyte senescence plays a key role in blood-brain barrier dysfunction, leading to RBI and subsequent cognitive decline. Strikingly, pericyte senescence also contributes to the growth and invasion of glioma cells. We further demonstrate that defective autophagy in pericytes is a vital regulatory mechanism for pericyte senescence. Moreover, autophagy activated by rapamycin can reverse pericyte senescence. Notably, the elimination of senescent cells by senolytic drugs significantly mitigated radiation-induced cognitive dysfunction. Our results demonstrated that pericyte senescence may be a promising therapeutic target for RBI and glioma progression.

Abstract Mo022: Doxorubicin induces cardiomyopathy through Wnt5a-mediated induction of senescence

Doxorubicin (DOX) is a chemotherapeutic agent used to treat cancer, but its clinical use is restricted due to cardiotoxicity. Senescence is defined by resistance to apoptosis and a senescence-associated secretory phenotype (SASP). Elimination of senescent cells can improve cardiac dysfunction, suggesting that senescent cardiomyocytes (CMs) contribute to impaired heart function. Although DOX induces senescence in CMs, little is known about the mechanisms mediating DOX-induced senescence and cardiomyopathy. Wnt5a, a non-canonical Wnt ligand, is an important player in cardiac diseases and is upregulated in induced pluripotent stem cell (iPSC)-derived CMs from patients with heart failure induced by DOX chemotherapy. However, the role of Wnt5a in mediating DOX-induced cardiomyopathy remains elusive. Wnt5a protein expression was increased (4.4-fold, p<0.001) in mouse hearts with DOX-induced cardiomyopathy. Upregulation of Wnt5a following DOX treatment was also observed in neonatal rat CMs (NRCMs), and the degree of upregulation was more prominent in CMs (2.1-fold) than in non-CMs (1.1-fold). In NRCMs, Wnt5a induced senescent phenotypes, including increases in the p16 protein level, the number of γH2AX foci per cell and SA-β-gal activity. Wnt5a knockdown reduced DOX-induced increases in the p16 protein level in NRCMs, suggesting that Wnt5a mediates DOX-induced CM senescence. To assess the role of endogenous CM Wnt5a in mediating DOX-induced cardiomyopathy, we generated Myh6 -cre Wnt5a fl/fl ( Wnt5a cKO ) mice, in which Wnt5a is knocked out in a CM-specific manner. DOX-treated Wnt5a cKO mice showed little difference in ejection fraction (EF) compared to PBS-treated Wnt5a cKO mice (56.64 ± 6.17% and 57.60 ± 5.23%), while DOX-treated Wnt5a fl/fl mice showed a significant decrease in EF (34.63 ± 3.65%, p<0.0001). These results suggest that Wnt5a deletion in CMs impedes the progression of DOX-induced cardiac dysfunction, positioning Wnt5a as a novel therapeutic target for the prevention of DOX-induced cardiomyopathy.

Senolytics and Senomorphics Targeting p38MAPK/NF-κB Pathway Protect Endothelial Cells from Oxidative Stress-Mediated Premature Senescence.

Oxidative stress is a prominent causal factor in the premature senescence of microvascular endothelial cells and the ensuing blood-brain barrier (BBB) dysfunction. Through the exposure of an in vitro model of human BBB, composed of brain microvascular endothelial cells (BMECs), astrocytes, and pericytes to H2O2, this study examined whether a specific targeting of the p38MAPK/NF-κB pathway and/or senescent cells could delay oxidative stress-mediated EC senescence and protect the BBB. Enlarged BMECs, displaying higher β-galactosidase activity, γH2AX staining, p16 expression, and impaired tubulogenic capacity, were regarded as senescent. The BBB established with senescent BMECs had reduced transendothelial electrical resistance and increased paracellular flux, which are markers of BBB integrity and function, respectively. Premature senescence disrupted plasma-membrane localization of the tight junction protein, zonula occludens-1, and elevated basement membrane-degrading matrix metalloproteinase-2 activity and pro-inflammatory cytokine release. Inhibition of p38MAPK by BIRB796 and NF-κB by QNZ and the elimination of senescent cells by a combination of dasatinib and quercetin attenuated the effects of H2O2 on senescence markers; suppressed release of the pro-inflammatory cytokines interleukin-8, monocyte chemoattractant protein-1, and intercellular adhesion molecule-1; restored tight junctional unity; and improved BBB function. In conclusion, therapeutic approaches that mitigate p38MAPK/NF-κB activity and senescent cell accumulation in the cerebrovasculature may successfully protect BBB from oxidative stress-induced BBB dysfunction.

Regulation of intestinal senescence during cholestatic liver disease modulates barrier function and liver disease progression

Background and AimsSenescence in cholangiocytes and hepatic stellate cells (HSC) has been described during human and murine cholestatic disease, having differential functions; detrimental in biliary cells and anti-fibrotic in HSC. Cholestatic liver disease associates with loss of intestinal barrier function and changes in the microbiome, the mechanistic cause of which is undetermined MethodsIntestinal samples were analysed from control and primary sclerosing cholangitis patients (PSC), wildtype (WT) and p16-3MR transgenic mice. Cholestatic liver disease was induced by bile duct ligation (BDL) and feeding with DDC diet. Fexaramine was used as an intestinal-restricted FXR agonist and antibiotics were given to eliminate the intestinal microbiome. Senescent cells were eliminated in p16-3MR mice with Ganciclovir and in WT mice with the senolytic drug ABT-263. In vitro studies were done in intestinal CaCo-2 cells and organoids were generated from intestinal-crypts isolated from mice. ResultsHere we show increased senescence in intestinal epithelial cells (IEC) in PSC patients and in mice after BDL and DDC diet. Intestinal senescence responded to reduced exposure to bile acids and increased presence of LPS in vitro and in vivo during cholestatic liver disease. Intestinal senescence associated with lower proliferation while increased intestinal stem cell (ISC) activation, as supported by increased organoid growth from ISC. Elimination of senescent cells with genetic and pharmacological approaches exacerbated liver injury and fibrosis during cholestatic liver disease that associated with increased IEC apoptosis and permeability. ConclusionsSenescence occurs in IEC during cholestatic disease and the elimination of senescent cells has a detrimental impact on the gut-liver axis. Our results point to cell-specific rather than systemic targeting of senescence as a therapeutic approach to treat cholestatic liver disease.

Topical application of a BCL-2 inhibitor ameliorates imiquimod-induced psoriasiform dermatitis by eliminating senescent cells

BackgroundPsoriasis is an inflammatory skin disease with unclear pathogenesis and unmet therapeutic needs. ObjectiveTo investigate the role of senescent CD4+ T cells in psoriatic lesion formation and explore the application of senolytics in treating psoriasis. MethodsWe explored the expression levels of p16INK4a and p21, classical markers of cellular senescence, in CD4+ T cells from human psoriatic lesions and imiquimod (IMQ)-induced psoriatic lesions. We prepared a senolytic gel using B-cell lymphoma 2 (BCL-2) inhibitor ABT-737 and evaluated its therapeutic efficacy in treating psoriasis. ResultsUsing multispectrum immunohistochemistry (mIHC) staining, we detected increased expression levels of p16INK4a and p21 in CD4+ T cells from psoriatic lesions. After topical application of ABT-737 gel, significant alleviation of IMQ-induced psoriatic lesions was observed, with milder pathological alterations. Mechanistically, ABT-737 gel significantly decreased the percentage of senescent cells, expression of T cell receptor (TCR) α and β chains, and expression of Tet methylcytosine dioxygenase 2 (Tet2) in IMQ-induced psoriatic lesions, as determined by mIHC, high-throughput sequencing of the TCR repertoire, and RT-qPCR, respectively. Furthermore, the severity of psoriatic lesions in CD4creTet2f/f mice was milder than that in Tet2f/f mice in the IMQ-induced psoriasis model. ConclusionWe revealed the roles of senescent CD4+ T cells in developing psoriasis and highlighted the therapeutic potential of topical ABT-737 gel in treating psoriasis through the elimination of senescent cells, modulation of the TCR αβ repertoire, and regulation of the TET2-Th17 cell pathway.

SGLT2 inhibition eliminates senescent cells and alleviates pathological aging

It has been reported that accumulation of senescent cells in various tissues contributes to pathological aging and that elimination of senescent cells (senolysis) improves age-associated pathologies. Here, we demonstrate that inhibition of sodium–glucose co-transporter 2 (SGLT2) enhances clearance of senescent cells, thereby ameliorating age-associated phenotypic changes. In a mouse model of dietary obesity, short-term treatment with the SGLT2 inhibitor canagliflozin reduced the senescence load in visceral adipose tissue and improved adipose tissue inflammation and metabolic dysfunction, but normalization of plasma glucose by insulin treatment had no effect on senescent cells. Canagliflozin extended the lifespan of mice with premature aging even when treatment was started in middle age. Metabolomic analyses revealed that short-term treatment with canagliflozin upregulated 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside, enhancing immune-mediated clearance of senescent cells by downregulating expression of programmed cell death-ligand 1. These findings suggest that inhibition of SGLT2 has an indirect senolytic effect by enhancing endogenous immunosurveillance of senescent cells.

Chemical Strategies for the Detection and Elimination of Senescent Cells.

Cellular senescence can be defined as an irreversible stopping of cell proliferation that arises in response to various stress signals. Cellular senescence is involved in diverse physiological and pathological processes in different tissues, exerting effects on processes as differentiated as embryogenesis, tissue repair and remodeling, cancer, aging, and tissue fibrosis. In addition, the development of some pathologies, aging, cancer, and other age-related diseases has been related to senescent cell accumulation. Due to the complexity of the senescence phenotype, targeting senescent cells is not trivial, is challenging, and is especially relevant for in vivo detection in age-related diseases and tissue samples. Despite the elimination of senescent cells (senolysis) using specific drugs (senolytics) that have been shown to be effective in numerous preclinical disease models, the clinical translation is still limited due to the off-target effects of current senolytics and associated toxicities. Therefore, the development of new chemical strategies aimed at detecting and eliminating senescent cells for the prevention and selective treatment of senescence-associated diseases is of great interest. Such strategies not only will contribute to a deeper understanding of this rapidly evolving field but also will delineate and inspire new possibilities for future research.In this Account, we report our recent research in the development of new chemical approaches for the detection and elimination of senescent cells based on new probes, nanoparticles, and prodrugs. The designed systems take advantage of the over-representation in senescent cells of certain biomarkers such as β-galactosidase and lipofuscin. One- and two-photon probes, for higher tissue penetration, have been developed. Moreover, we also present a renal clearable fluorogenic probe for the in vivo detection of the β-galactosidase activity, allowing for correlation with the senescent burden in living animals. Moreover, as an alternative to molecular-based probes, we also developed nanoparticles for senescence detection. Besides, we describe advances in new therapeutic agents to selectively eradicate senescent cells using β-galactosidase activity-sensitive gated nanoparticles loaded with cytotoxic or senolytic agents or new prodrugs aiming to increase the selectivity and reduction of off-target toxicities of current drugs. Moreover, new advances therapies have been applied in vitro and in vivo. Studies with the probes, nanoparticles, and prodrugs have been applied in several in vitro and in vivo models of cancer, fibrosis, aging, and drug-induced cardiotoxicity in which senescence plays an important role. We discuss the benefits of these chemical strategies toward the development of more specific and sophisticated probes, nanoparticles, and prodrugs targeting senescent cells.

Chemo-Senolytic Therapeutic Potential against Angiosarcoma

Angiosarcoma is an aggressive soft-tissue sarcoma with a poor prognosis. Chemotherapy for this cancer typically employs paclitaxel, a taxane (genotoxic drug), although it has a limited effect owing to chemoresistance to prolonged treatment. Here, we examine an alternative angiosarcoma treatment approach that combines chemotherapeutic and senolytic agents. We find that the chemotherapeutic drugs cisplatin and paclitaxel efficiently induce senescence in angiosarcoma cells. Subsequent treatment with the senolytic agent ABT-263 eliminates senescent cells by activating the apoptotic pathway. In addition, expression analysis indicates that senescence-associated secretory phenotype (SASP) genes are activated in senescent angiosarcoma cells and that ABT-263 treatment down-regulates type I interferon (IFN-I) pathway genes in senescent cells. Moreover, we show that cisplatin treatment alone requires high doses to remove angiosarcoma cells. In contrast, lower doses of cisplatin are sufficient to induce senescence, followed by the elimination of senescent cells by the senolytic treatment. This study sheds light on a potential therapeutic strategy against angiosarcoma by combining a relatively low dose of cisplatin with the ABT-263 senolytic agent, which can help ease the deleterious side effects of chemotherapy.

Cellular senescence in the pathogenesis of ovarian dysfunction.

The follicular microenvironment is crucial for normal ovarian function, and intra-ovarian factors, in coordination with gonadotropins, contribute to its regulation. Recent research has revealed that the accumulation of senescent cells worsens the adverse environment of various tissues and plays critical roles in chronological aging and various pathological conditions. Cellular senescence involves cell-cycle arrest, a senescence-associated secretory phenotype (SASP), macromolecular damage, and dysmetabolism. In this review, I summarize the latest knowledge regarding the role of cellular senescence in pathological conditions in the ovary, in the context of reproduction. Specifically, cellular senescence is known to impair follicular and oocyte health in cisplatin- and cyclophosphamide-induced primary ovarian insufficiency and to contribute to the pathogenesis of polycystic ovary syndrome (PCOS). In addition, cellular senescence is induced during the decline in ovarian reserve that is associated with chronological aging, endometriosis, psychological stress, and obesity, but it remains unclear whether it plays a causative role in these conditions. Finally, I discuss the potential for use of cellular senescence as a novel therapeutic target. The modification of SASP using a senomorphic and/or the elimination of senescent cells using a senolytic represent promising therapeutic strategies. Further elucidation of the role of cellular senescence in the effects of various insults on ovarian reserve, including chronological aging, as well as in pathogenesis of ovarian pathologies, including PCOS, may facilitate a new era of reproductive medicine.

Single cell analysis revealed that two distinct, unique CD4+ T cell subsets were increased in the small intestinal intraepithelial lymphocytes of aged mice.

Recent advances in research suggest that aging has a controllable chronic inflammatory disease aspect. Aging systemic T cells, which secrete pro-inflammatory factors, affect surrounding somatic cells, and accelerate the aging process through chronic inflammation, have attracted attention as potential therapeutic targets in aging. On the other hand, there are few reports on the aging of the intestinal immune system, which differs from the systemic immune system in many ways. In the current study, we investigated the age-related changes in the intestinal immune system, particularly in T cells. The most significant changes were observed in the CD4+ T cells in the small intestinal IEL, with a marked increase in this fraction in old mice and reduced expression of CD27 and CD28, which are characteristic of aging systemic T cells. The proliferative capacity of aging IEL CD4+ T cells was significantly more reduced than that of aging systemic T cells. Transcriptome analysis showed that the expression of inflammatory cytokines was not upregulated, whereas Cd8α, NK receptors, and Granzymes were upregulated in aging IEL CD4+ T cells. Functional analysis showed that aging IEL T cells had a higher cytotoxic function against intestinal tumor organoids in vitro than young IEL T cells. scRNAseq revealed that splenic T cells show a transition from naïve to memory T cells, whereas intestinal T cells show the emergence of a CD8αα+CD4+ T cell fraction in aged mice, which is rarely seen in young cells. Further analysis of the aging IEL CD4+ T cells showed that two unique subsets are increased that are distinct from the systemic CD4+ T cells. Subset 1 has a pro-inflammatory component, with expression of IFNγ and upregulation of NFkB signaling pathways. Subset 2 does not express IFNγ, but upregulates inhibitory molecules and nIEL markers. Expression of granzymes and Cd8a was common to both. These fractions were in opposite positions in the clustering by UMAP and had different TCR repertoires. They may be involved in the suppression of intestinal aging and longevity through anti-tumor immunity, elimination of senescent cells and stressed cells in the aging environment. This finding could be a breakthrough in aging research.

Aging, Cellular Senescence, and Glaucoma.

Aging is one of the most serious risk factors for glaucoma, and according to age-standardized prevalence, glaucoma is the second leading cause of legal blindness worldwide. Cellular senescence is a hallmark of aging that is defined by a stable exit from the cell cycle in response to cellular damage and stress. The potential mechanisms underlying glaucomatous cellular senescence include oxidative stress, DNA damage, mitochondrial dysfunction, defective autophagy/mitophagy, and epigenetic modifications. These phenotypes interact and generate a sufficiently stable network to maintain the cell senescent state. Senescent trabecular meshwork (TM) cells, retinal ganglion cells (RGCs) and vascular endothelial cells reportedly accumulate with age and stress and may contribute to glaucoma pathologies. Therapies targeting the suppression or elimination of senescent cells have been found to ameliorate RGC death and improve vision in glaucoma models, suggesting the pivotal role of cellular senescence in the pathophysiology of glaucoma. In this review, we explore the biological links between aging and glaucoma, specifically delving into cellular senescence. Moreover, we summarize the current data on cellular senescence in key target cells associated with the development and clinical phenotypes of glaucoma. Finally, we discuss the therapeutic potential of targeting cellular senescence for the management of glaucoma.

Detection and Elimination of Senescent Cells with a Self-Assembled Senescence-Associated β-Galactosidase-Activatable Nanophotosensitizer.

Senescent cells have become an important therapeutic target for many age-related dysfunctions and diseases. We report herein a novel nanophotosensitizing system that is responsive to the senescence-associated β-galactosidase (β-gal) for selective detection and elimination of these cells. It involves a dimeric zinc(II) phthalocyanine linked to a β-galactose unit via a self-immolative linker. This compound can self-assemble in aqueous media, forming stable nanoscale particles in which the phthalocyanine units are stacked and self-quenched for fluorescence emission and singlet oxygen production. Upon internalization into senescent HeLa cells, these nanoparticles interact with the overproduced senescence-associated β-gal inside the cells to trigger the disassembly process through enzymatic cleavage of the glycosidic bonds, followed by self-immolation to release the photoactive monomeric phthalocyanine units. These senescent cells can then be lit up with fluorescence and eliminated through the photodynamic action upon light irradiation with a half-maximal inhibitory concentration of 0.06 μM.

Potential role of ergothioneine rich mushroom as anti-aging candidate through elimination of neuronal senescent cells

Oxidative stress can upset the antioxidant balance and cause accelerated aging including neurodegenerative diseases and decline in physiological function. Therefore, an antioxidant-rich diet plays a crucial role in healthy aging. This study aimed to identify and quantify mushrooms with the highest ergothioneine content through HPLC analysis and evaluate their anti-aging potential as a natural antioxidant and antisenescence in HT22 cells. Among the 14 evaluated mushroom species, Lentinula edodes (LE), shiitake mushroom contains the highest ergothioneine content and hence was used for the in-vitro studies. The cells were preincubated with ethanolic extract of ergothioneine-rich mushroom and the equimolar concentration of EGT on t-BHP-induced senescence HT22 cells. The extract was analyzed for its free radical scavenging properties using DPPH and ABTS methods. Then, the neuroprotective effect was conducted by measuring the cell viability using MTT. Senescence-associated markers and ROS staining were also analyzed. Our results revealed that a low dose of t-BHP reduces cell viability and induces senescence in HT22 cells as determined through β-galactosidase staining and expressions of P16INK4a, P21CIPL which are the markers of cellular senescence. However, the pretreatment with ethanolic extract of LE for 8 h significantly improved the cell viability, reversed the t-BHP-induced cellular senescence in the neuronal cells, and reduced the reactive oxygen species visualized through DCFH-DA staining. These results suggest that ergothioneine-rich mushroom is a potential candidate for anti-aging exploration through the elimination of senescent cells.

The role of cellular senescence in metabolic diseases and the potential for senotherapeutic interventions.

Cellular senescence represents an irreversible state of cell cycle arrest induced by various stimuli strongly associated with aging and several chronic ailments. In recent years, studies have increasingly suggested that the accumulation of senescent cells is an important contributor to the decline of organ metabolism, ultimately resulting in metabolic diseases. Conversely, the elimination of senescent cells can alleviate or postpone the onset and progression of metabolic diseases. Thus, a close relationship between senescent cells and metabolic diseases is found, and targeting senescent cells has emerged as an alternative therapy for the treatment of metabolic diseases. In this review, we summarize the role of cellular senescence in metabolic diseases, explore relevant therapeutic strategies for metabolic diseases by removing senescent cells, and provide new insights into the treatment of metabolic diseases.

Cellular senescence in malignant cells promotes tumor progression in mouse and patient Glioblastoma

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults, yet it remains refractory to systemic therapy. Elimination of senescent cells has emerged as a promising new treatment approach against cancer. Here, we investigated the contribution of senescent cells to GBM progression. Senescent cells are identified in patient and mouse GBMs. Partial removal of p16Ink4a-expressing malignant senescent cells, which make up less than 7 % of the tumor, modifies the tumor ecosystem and improves the survival of GBM-bearing female mice. By combining single cell and bulk RNA sequencing, immunohistochemistry and genetic knockdowns, we identify the NRF2 transcription factor as a determinant of the senescent phenotype. Remarkably, our mouse senescent transcriptional signature and underlying mechanisms of senescence are conserved in patient GBMs, in whom higher senescence scores correlate with shorter survival times. These findings suggest that senolytic drug therapy may be a beneficial adjuvant therapy for patients with GBM.

Increased cellular senescence in doxorubicin-induced murine ovarian injury: effect of senolytics

Ovarian injury caused by chemotherapy can lead to early menopause, infertility, and even premature senility in female cancer patients, impairing the quality of life and overall health of the cancer survivors seriously. However, there is still a lack of effective protection strategies against such injury. Cellular senescence can be induced by chemotherapeutic agents in multiple organs and may corrode the structure and function of normal tissues. We hypothesized that the widely used first-line chemotherapy drug, doxorubicin, could increase senescent cell burden in normal ovarian tissue during the therapeutic process and that elimination of senescent cells with senolytics would ameliorate doxorubicin-induced ovarian injury. Here, we demonstrated an accumulation of cellular senescence in doxorubicin-treated ovaries through detecting p16 and p21 expression levels and senescence-associated β-galactosidase (SA-β-gal) activity as well as senescence-associated secretory phenotype (SASP) factors. Short-term intervention with the classic senolytic combination dasatinib and quercetin (DQ) or fisetin significantly reduced the load of senescent cells in ovaries after doxorubicin treatment. However, neither DQ nor fisetin alleviated doxorubicin-related ovarian dysfunction. Further experiments showed that ovarian apoptosis and fibrosis following doxorubicin exposure could not be improved by senolytics. Collectively, our study shows that senolytic treatment can eliminate accumulated senescent cells, but cannot reverse the massive follicle loss and ovarian stromal fibrosis caused by doxorubicin, suggesting that cellular senescence may not be one of the key mechanisms in doxorubicin-induced ovarian injury.

Combined use of dasatinib and quercetin alleviates overtraining-induced deficits in learning and memory through eliminating senescent cells and reducing apoptotic cells in rat hippocampus

Excessive physical exercise (overtraining, OT) charactered by long-term and excessive training results in the damage of multiple vital tissues including hippocampus which plays a critical role in learning and memory. A combination of dasatinib (D) plus quercetin (Q) (D+Q) belongs to senolytic drugs which selectively kill senescent cells in vitro and vivo. In this study, the rats that suffered a five-week excessive swimming training were subjected to the oral administration of D+Q. D+Q alleviated the decline in exercise performance of OT rats during the swimming training, and prevented learning and memory deficits in Morris water maze, Y-maze and novel object recognition tests after excessive swimming training. Analytical results by SA-β-gal staining and western blotting showed that D+Q significantly reduced senescent cells with repressed expression of senescence-related proteins, p53 and p21, in hippocampus. Nissl and immunohistochemical staining showed that D+Q significantly attenuated neuronal loss caused by apoptosis. Interestingly, we observed elevated level of cleaved caspase 3, an apoptosis executor protein, in p21 positive hippocampus cells by D+Q treatment in immunofluorescent staining, suggesting that senescent cells were induced to apoptosis in D+Q-treated rats. The positive control drug, silibinin, showed similar protective effect against OT, but did not induce the apoptosis of senescent cells, suggesting a difference in the protective mechanisms. These results indicated that D+Q alleviates overtraining-induced deficits in learning and memory through elimination of senescent cells and reduction of apoptotic cell number.