Strategies for Targeting Senescent Cells in Human Disease

Paradoxical cell targeting of calreticulin-empowered, protein-only nanoparticles

Surface-exposed calreticulin (CRT) serves as a crucial cell damage-associated molecular pattern for immunogenic apoptosis, by generating an "eat me" signal to macrophages. Aiming at precision immunotherapies we intended to artificially label tumoral cells in vivo with a recombinant CRT, in a targeted way. For that, we have constructed a CRT fusion protein intended to surface attach CXCR4+ cancer cells, to stimulate their immunological destruction. As a targeting ligand of the CRT construct and to drive its specific cell adhesion, we used the peptide V1, a derivative of the vMIP-II cytokine and an antagonist of CXCR4. The modular protein tends to self-assemble as regular 16 nm nanoparticles, assisted by ionic Zn. Through both in vivo and in vitro experiments, we have determined that CRT itself confers cell targeting capabilities to the construct overcoming those of V1, that are only moderate. In particular, CRT binds HeLa cells in absence of further internalization, by a route fully independent of CXCR4. Furthermore, by cytometry in THP-1 cells, we observed that the binding of the protein is preferential for dead cells over live cells, a fact that cannot be associated to a mere artefactual adsorption. These data are discussed in the context of the oligomerizing properties of CRT and the potential clinical applicability of proteins and protein materials functionalized with this novel cell surface ligand.

Cellular senescence in metastatic prostate cancer: A therapeutic opportunity or challenge (Review)

The treatment of patients with metastatic prostate cancer (PCa) is considered to be a long‑standing challenge. Conventional treatments for metastatic PCa, such as radical prostatectomy, radiotherapy and androgen receptor‑targeted therapy, induce senescence of PCa cells to a certain extent. While senescent cells can impede tumor growth through the restriction of cell proliferation and increasing immune clearance, the senescent microenvironment may concurrently stimulate the secretion of a senescence‑associated secretory phenotype and diminish immune cell function, which promotes PCa recurrence and metastasis. Resistance to established therapies is the primary obstacle in treating metastatic PCa as it can lead to progression towards an incurable state of disease. Therefore, understanding the molecular mechanisms that underly the progression of PCa is crucial for the development of novel therapeutic approaches. The present study reviews the phenomenon of treatment‑induced senescence in PCa, the dual role of senescence in PCa treatments and the mechanisms through which senescence promotes PCa metastasis. Furthermore, the present review discusses potential therapeutic strategies to target the aforementioned processes with the aim of providing insights into the evolving therapeutic landscape for the treatment of metastatic PCa.

Targeting senescent HDF with the USP7 inhibitor P5091 to enhance DFU wound healing through the p53 pathway

OBJECTIVE

The objective of this study was to examine the potential of USP7 as a target for senolytic therapy and to investigate the molecular mechanism by which its inhibitor selectively induced apoptosis in senescent HDF and enhanced DFU wound healing.

METHODS

Clinical samples of DFU were collected to detect the expression of USP7 and aging-related proteins using immunohistochemistry and Western blot. In addition, β-galactosidase staining, qPCR, flow cytometry, ROS and MMP kits, and Western blot were used to analyze the biological functions of P5091 on senescence, cycle, and apoptosis. RNAseq was employed to further analyze the molecular mechanism of P5091. Finally, the DFU rat model was established to evaluate the effect of P5091 on wound healing.

RESULTS

The expression of USP7 and p21 were increased in DFU clinical samples. After treatment with d-glucose (30 mM, 7 days), β-galactosidase staining was deepened, proliferation rate decreased. USP7 inhibitors (P5091) could reduce the release of SASP factors, activate the production of ROS, and reduce MMP. In addition, it induced apoptosis and selectively clears senescent cells through the p53 signaling pathway. Finally, P5091 can improve diabetic wound healing in rats.

CONCLUSION

This study clarified the molecular mechanism of USP7 inhibitor (P5091) selectively inducing apoptosis of high glucose senescent HDF cells. This provides a new senolytics target and experimental basis for promoting DFU wound healing.

Intermittent clearance of p21-highly-expressing cells extends lifespan and confers sustained benefits to health and physical function

A key challenge in aging research is extending lifespan in tandem with slowing down functional decline so that life with good health (healthspan) can be extended. Here, we show that monthly clearance, starting from 20 months, of a small number of cells that highly express p21Cip1 (p21high) improves cardiac and metabolic function and extends both median and maximum lifespans in mice. Importantly, by assessing the health and physical function of these mice monthly until death, we show that clearance of p21high cells improves physical function at all remaining stages of life, suggesting healthspan extension. Mechanistically, p21high cells encompass several cell types with a relatively conserved proinflammatory signature. Clearance of p21high cells reduces inflammation and alleviates age-related transcriptomic signatures of various tissues. These findings demonstrate the feasibility of healthspan extension in mice and indicate p21high cells as a therapeutic target for healthy aging.

Crosstalk between the DNA damage response and cellular senescence drives aging and age-related diseases

Cellular senescence is a crucial process of irreversible cell-cycle arrest, in which cells remain alive, but permanently unable to proliferate in response to distinct types of stressors. Accumulating evidence suggests that DNA damage builds over time and triggers DNA damage response signaling, leading to cellular senescence. Cellular senescence serves as a platform for the perpetuation of inflammatory responses and is central to numerous age-related diseases. Defects in DNA repair genes or senescence can cause premature aging disease. Therapeutic approaches limiting DNA damage or senescence contribute to a rescued phenotype of longevity and neuroprotection, thus suggesting a mechanistic interaction between DNA damage and senescence. Here, we offer a unique perspective on the crosstalk between the DNA damage response pathway and senescence as well as their contribution to age-related diseases. We further summarize recent progress on the mechanisms and therapeutics of senescence, address existing challenges, and offering new insights and future directions in the senescence field.

Dipeptidylpeptidase-4-targeted activatable fluorescent probes visualize senescent cells

Senescent cells promote cancer development and progression through chronic inflammation caused by a senescence-associated secretory phenotype (SASP). Although various senotherapeutic strategies targeting senescent cells have been developed for the prevention and treatment of cancers, technology for the in vivo detection and evaluation of senescent cell accumulation has not yet been established. Here, we identified activatable fluorescent probes targeting dipeptidylpeptidase-4 (DPP4) as an effective probe for detecting senescent cells through an enzymatic activity-based screening of fluorescent probes. We also determined that these probes were highly, selectively, and rapidly activated in senescent cells during live cell imaging. Furthermore, we successfully visualized senescent cells in the organs of mice using DPP4-targeted probes. These results are expected to lead to the development of a diagnostic technology for noninvasively detecting senescent cells in vivo and could play a role in the application of DPP4 prodrugs for senotherapy.

Crosstalk between gut microbiota and cellular senescence: a vicious cycle leading to aging gut

Two phenomena, the accumulation of senescent cells and changes in the gut microbiota, are thought to contribute to the decline of biological functions and the development of diseases associated with aging. However, the relationship between these two phenomena and their effects on aging remains to be clarified. Recently, we have reported that gut bacteria induce cellular senescence in ileal germinal center (GC) B cells, resulting in decreased IgA production and diversity. This, in turn, leads to an imbalance in the gut microbiota. Thus, the crosstalk between the gut microbiota and cellular senescence via the host immune system may establish a vicious cycle and contribute to the disruption of gut homeostasis associated with aging.

Systemic Analyses of Anti-Cell-Senescence Active Compounds in Camellia Sect. Chrysantha Chang and Their Mechanisms

Aging is an irreversible pathophysiological process for all organisms. The accumulation of senescent cells in pathological sites or tissues is recognized as the major cause of diseases and disorders during the aging process. Small molecules that reduce senescent cell burdens have gained increasing attention as promising intervention therapeutics against aging, but effective anti-senescence agents remain rare. Camellia Sect. Chrysantha Chang is documented as a traditional Chinese herbal medicine used by ethnic groups for many medical and health benefits, but its effect on aging is unclear. Here, we investigated the anti-senescence potential of eight C. Sect. Chrysantha Chang species. The results show that ethyl acetate fractions from these C. Sect. Chrysantha Chang species were able to delay the senescence of H9c2 cardiomyocytes except for C. pingguoensis (CPg). N-butanol fractions of C. multipetala (CM), C. petelotii var. grandiflora (CPt), and C. longzhouensis (CL) showed a senescent cell clearance effect by altering the expression levels of senescent-associated marker genes in the DNA-damage response (DDR) pathway and the senescent cell anti-apoptotic pathway (SCAPs). By using UPLC-QTOF-MS-based non-targeted metabolomics analyses, 27 metabolites from Sect. Chrysantha species were putatively identified. Among them, high levels of sanchakasaponin C and D in CM, CPt, and CL were recognized as the key bioactive compounds responsible for senescent cell clearance. This study is the first to disclose and compare the anti-cell-senescence effect of a group of C. Sect. Chrysantha Chang, including some rare species. The combination of senescent markers and metabolomics analyses helped us to reveal the differences in chemical constituents that target senescent cells. Significantly, contrary to the C. chrysantha var. longistyla (CCL), which is widely cultivated and commercialized for tea drinks, CM, CPt, and CL contain unique chemicals for managing aging and aging-related diseases. The results from this study provide a foundation for species selection in developing small-molecule-based drugs to alleviate diseases and age-related dysfunctions and may potentially be useful for advancing geroscience research.

SATB1, senescence and senescence-related diseases

Aging leads to an accumulation of cellular mutations and damage, increasing the risk of senescence, apoptosis, and malignant transformation. Cellular senescence, which is pivotal in aging, acts as both a guard against cellular transformation and as a check against cancer progression. It is marked by stable cell cycle arrest, widespread macromolecular changes, a pro-inflammatory profile, and altered gene expression. However, it remains to be determined whether these differing subsets of senescent cells result from unique intrinsic programs or are influenced by their environmental contexts. Multiple transcription regulators and chromatin modifiers contribute to these alterations. Special AT-rich sequence-binding protein 1 (SATB1) stands out as a crucial regulator in this process, orchestrating gene expression by structuring chromatin into loop domains and anchoring DNA elements. This review provides an overview of cellular senescence and delves into the role of SATB1 in senescence-related diseases. It highlights SATB1's potential in developing antiaging and anticancer strategies, potentially contributing to improved quality of life and addressing aging-related diseases.

A Nanocapsule System Combats Aging by Inhibiting Age-Related Angiogenesis Deficiency and Glucolipid Metabolism Disorders

Insufficient angiogenic stimulation and dysregulated glycolipid metabolism in senescent vascular endothelial cells (VECs) constitute crucial features of vascular aging. Concomitantly, the generation of excess senescence-associated secretory phenotype (SASP) and active immune-inflammatory responses propagates within injured vessels, tissues, and organs. Until now, targeted therapies that efficiently rectify phenotypic abnormalities in senescent VECs have still been lacking. Here, we constructed a Pd/hCeO2-BMS309403@platelet membrane (PCBP) nanoheterostructured capsule system loaded with fatty acid-binding protein 4 (FABP4) inhibitors and modified with platelet membranes and investigated its therapeutic role in aged mice. PCBP showed significant maintenance in aged organs and demonstrated excellent biocompatibility. Through cyclic tail vein administration, PCBP extended the lifespan and steadily ameliorated abnormal phenotypes in aged mice, including SASP production, immune and inflammatory status, and age-related metabolic disorders. In senescent ECs, PCBP mediated the activation of vascular endothelial growth factor (VEGF) signaling and glycolysis and inhibition of FABP4 by inducing the synthesis of hypoxia-inducible factor-1α, thereby reawakening neovascularization and restoring glycolipid metabolic homeostasis. In conclusion, the PCBP nanocapsule system provides a promising avenue for interventions against aging-induced dysfunction.

A Senomorphlytic Three-Drug Combination Discovered in Salsola collina for Delaying Aging Phenotypes and Extending Healthspan

The pursuit of pharmacological interventions in aging aims focuses on maximizing safety and efficacy, prompting an exploration of natural products endowed with inherent medicinal properties. Subsequently, this work establishes a unique library of plant extracts sourced from Yunnan Province, China. Screening of this herbal library herein revealed that Salsola collina (JM10001) notably enhances both lifespan and healthspan in C. elegans. Further analysis via network pharmacology indicates that the p53 signaling pathway plays a crucial role in mediating the anti-aging effects of JM10001. Additionally, this work identifies that a composition, designated as JM10101 and comprising three chemical constituents of JM10001, preserves the original lifespan-extending activity in C. elegans. Both JM10001 and JM10101 mitigate aging symptoms in senescence-accelerated mice treated with doxorubicin and in naturally aged mice. Notably, JM10101 exhibits a more sophisticated senomorphlytic role encompassing both senomorphic and senolytic functions than JM10001 in the modulation of senescent cells, offering a promising strategy for the discovery of combination drugs in the rational development of anti-aging therapies.

Rejuvenation Strategy for Inducing and Enhancing Autoimmune Response to Eliminate Senescent Cells

The process of aging, which involves progressive changes in the body over time, is closely associated with the development of age-related diseases. Cellular senescence is a pivotal hallmark and mechanism of the aging process. The accumulation of senescent cells can significantly contribute to the onset of age-related diseases, thereby compromising overall health. Conversely, the elimination of senescent cells enhances the body's regenerative and reparative capacity, thereby retarding the aging process. Here, we present a brief overview of 12 Hallmarks of aging and subsequently emphasize the potential of immune checkpoint blockade, innate immune cell therapy (including T cells, iNKT cells, macrophages, and NK cells), as well as CAR-T cell therapy for inducing and augmenting immune responses aimed at eliminating senescent cells. In addition to CAR-T cells, we also explore the possibility of engineered immune cells such as CAR-NK and CAR-M cells to eliminate senescent cells. In summary, immunotherapy, as an emerging strategy for the treatment of aging, offers new prospects for age-related research.

Advances in the Synthesis and Physiological Metabolic Regulation of Nicotinamide Mononucleotide

Nicotinamide mononucleotide (NMN), the direct precursor of nicotinamide adenine dinucleotide (NAD+), is involved in the regulation of many physiological and metabolic reactions in the body. NMN can indirectly affect cellular metabolic pathways, DNA repair, and senescence, while also being essential for maintaining tissues and dynamic metabolic equilibria, promoting healthy aging. Therefore, NMN has found many applications in the food, pharmaceutical, and cosmetics industries. At present, NMN synthesis strategies mainly include chemical synthesis and biosynthesis. Despite its potential benefits, the commercial production of NMN by organic chemistry approaches faces environmental and safety problems. With the rapid development of synthetic biology, it has become possible to construct microbial cell factories to produce NMN in a cost-effective way. In this review, we summarize the chemical and biosynthetic strategies of NMN, offering an overview of the recent research progress on host selection, chassis cell optimization, mining of key enzymes, metabolic engineering, and adaptive fermentation strategies. In addition, we also review the advances in the role of NMN in aging, metabolic diseases, and neural function. This review provides comprehensive technical guidance for the efficient biosynthesis of NMN as well as a theoretical basis for its application in the fields of food, medicine, and cosmetics.

Exposure to ambient air pollution mixture and senescence-associated secretory phenotype proteins among middle-aged and older women

Our study aimed to investigate the impact of environmental exposures, such as ambient air pollutants, on systemic inflammation and cellular senescence in middle-aged and older women. We utilized epidemiological data linked with exposure data of six air pollutants (particulate matters [PM10, PM2.5], sulphur dioxide [SO2], nitrogen dioxide [NO2], carbon monoxide [CO], and ozone [O3]) and blood samples of 380 peri- and postmenopausal women participants of the Korean Genome and Epidemiology Study. We measured blood high-sensitivity C-reactive protein (hsCRP) and age-related 27 circulatory senescence-associated secretory phenotypes (SASP) produced by senescent cells. We employed single exposure models to explore the general pattern of association between air pollution exposure and proteomic markers. Using quantile g-computation models, we assessed the association of six air pollutant mixtures with hsCRP and SASP proteins. In single-exposure, single-period models, nine out of the 27 SASP proteins including IFN-γ (β = 0.04, 95% CI: 0.01, 0.07 per interquartile range-increase), IL-8 (0.15, 95% CI: 0.09, 0.20), and MIP1α (0.11, 95% CI: 0.04, 0.18) were positively associated with the average level of O3 over one week. Among the age-related SASP proteins, IFN-γ (0.11, 95% CI: 0.03, 0.20) and IL-8 (0.22, 95% CI: 0.05, 0.39) were positively associated with exposure to air pollutant mixture over one week. The MIP1β was higher with an increasing one-month average concentration of the air pollutant mixture (0.11, 95% CI: 0.00, 0.21). The IL-8 showed consistently positive association with the ambient air pollutant mixture for the exposure periods ranging from one week to one year. O3 predominantly showed positive weights in the associations between air pollutant mixtures and IL-8. These findings underscore the potential of proteomic indicators as markers for biological aging attributed to short-term air pollution exposure.

Increased PTCHD4 expression via m6A modification of PTCHD4 mRNA promotes senescent cell survival

RNA modifications, including N6-methyladenosine (m6A), critically modulate protein expression programs in a range of cellular processes. Although the transcriptomes of cells undergoing senescence are strongly regulated, the landscape and impact of m6A modifications during senescence are poorly understood. Here, we report a robust m6A modification of PTCHD4 mRNA, encoding Patched Domain-Containing Protein 4, in senescent cells. The METTL3/METTL14 complex was found to incorporate the m6A modification on PTCHD4 mRNA; addition of m6A rendered PTCHD4 mRNA more stable and increased PTCHD4 production. MeRIP RT-qPCR and eCLIP analyses were used to map this m6A modification to the last exon of PTCHD4 mRNA. Further investigation identified IGF2BP1, but not other m6A readers, as responsible for the stabilization and increased abundance of m6A-modified PTCHD4 mRNA. Silencing PTCHD4, a transmembrane protein, enhanced growth arrest and DNA damage in pre-senescent cells and sensitized them to senolysis and apoptosis. Our results indicate that m6A modification of PTCHD4 mRNA increases the production of PTCHD4, a protein associated with senescent cell survival, supporting the notion that regulating m6A modification on specific mRNAs could be exploited to eliminate senescent cells for therapeutic benefit.

Establishing evidence for immune surveillance of β-cell senescence

Cellular senescence is a programmed state of cell cycle arrest that involves a complex immunogenic secretome, eliciting immune surveillance and senescent cell clearance. Recent work has shown that a subpopulation of pancreatic β-cells becomes senescent in the context of diabetes; however, it is not known whether these cells are normally subject to immune surveillance. In this opinion article, we advance the hypothesis that immune surveillance of β-cells undergoing a senescence stress response normally limits their accumulation during aging and that the breakdown of these mechanisms is a driver of senescent β-cell accumulation in diabetes. Elucidation and therapeutic activation of immune surveillance mechanisms in the pancreas holds promise for the improvement of approaches to target stressed senescent β-cells in the treatment of diabetes.

Caveolae and caveolin-1 as targets of dietary polyphenols for protection against vascular endothelial dysfunction

Caveolae, consisting of caveolin-1 proteins, are ubiquitously present in endothelial cells and contribute to normal cardiovascular functions by acting as a platform for cellular signaling pathways as well as transcytosis and endocytosis. However, caveolin-1 is thought to have a proatherogenic role by inhibiting endothelial nitric oxide synthase activity and Nrf2 activation, or by promoting inflammation through NF-κB activation. Dietary polyphenols were suggested to exert anti-atherosclerotic effects by a mechanism involving the inhibition of endothelial dysfunction, by which they can regulate redox-sensitive signaling pathways in relation to NF-κB and Nrf2 activation. Some monomeric polyphenols and microbiota-derived catabolites from monomeric polyphenols or polymeric tannins might be responsible for the inhibition, because they can be transferred into the circulation from the digestive tract. Several polyphenols were reported to modulate caveolin-1 expression or its localization in caveolae. Therefore, we hypothesized that circulating polyphenols affect caveolae functions by altering its structure leading to the release of caveolin-1 from caveolae, and attenuating redox-sensitive signaling pathway-dependent caveolin-1 overexpression. Further studies using circulating polyphenols at a physiologically relevant level are necessary to clarify the mechanism of action of dietary polyphenols targeting caveolae and caveolin-1.

Biomarkers of Cellular Senescence and Aging: Current State-of-the-Art, Challenges and Future Perspectives

Population aging has increased the global prevalence of aging-related diseases, including cancer, sarcopenia, neurological disease, arthritis, and heart disease. Understanding aging, a fundamental biological process, has led to breakthroughs in several fields. Cellular senescence, evinced by flattened cell bodies, vacuole formation, and cytoplasmic granules, ubiquitously plays crucial roles in tissue remodeling, embryogenesis, and wound repair as well as in cancer therapy and aging. The lack of universal biomarkers for detecting and quantifying senescent cells, in vitro and in vivo, constitutes a major limitation. The applications and limitations of major senescence biomarkers, including senescence-associated β-galactosidase staining, telomere shortening, cell-cycle arrest, DNA methylation, and senescence-associated secreted phenotypes are discussed. Furthermore, explore senotherapeutic approaches for aging-associated diseases and cancer. In addition to the conventional biomarkers, this review highlighted the in vitro, in vivo, and disease models used for aging studies. Further, technologies from the current decade including multi-omics and computational methods used in the fields of senescence and aging are also discussed in this review. Understanding aging-associated biological processes by using cellular senescence biomarkers can enable therapeutic innovation and interventions to improve the quality of life of older adults.

Senescent cell-derived vaccines: a new concept towards an immune response against cancer and aging?

Two recent seminal works have untangled the intricate role of tumor-associated senescent cells in cancer progression, or regression, by guiding our immune system against cancer cells. The characterization of these unique, yet diverse cell populations, should be considered, particularly when contemplating the use of senolytics, which are drugs that selectively eliminate senescent cells, in a cancer framework. Here, we will describe the current knowledge in this field. In particular, we will discuss how the presence of senescent cells in tumors could be used as a therapeutic target in immunogenic cancers and how we may hypothetically design an adaptive anti-aging vaccine.

Fibronectin and vitronectin alleviate adipose-derived stem cells senescence during long-term culture through the AKT/MDM2/P53 pathway

Cellular senescence plays a role in the development of aging-associated degenerative diseases. Cell therapy is recognized as a candidate treatment for degenerative diseases. To achieve the goal of cell therapy, the quality and good characteristics of cells are concerned. Cell expansion relies on two-dimensional culture, which leads to replicative senescence of expanded cells. This study aimed to investigate the effect of cell culture surface modification using fibronectin (FN) and vitronectin (VN) in adipose-derived stem cells (ADSCs) during long-term expansion. Our results showed that ADSCs cultured in FN and VN coatings significantly enhanced adhesion, proliferation, and slow progression of cellular senescence as indicated by lower SA-β-gal activities and decreased expression levels of genes including p16, p21, and p53. The upregulation of integrin α5 and αv genes influences phosphatidylinositol 4,5-bisphosphate 3-kinase (PI3K), and AKT proteins. FN and VN coatings upregulated AKT and MDM2 leading to p53 degradation. Additionally, MDM2 inhibition by Nutlin-3a markedly elevated p53 and p21 expression, increased cellular senescence, and induced the expression of inflammatory molecules including HMGB1 and IL-6. The understanding of FN and VN coating surface influencing ADSCs, especially senescence characteristics, offers a promising and practical point for the cultivation of ADSCs for future use in cell-based therapies.

The enchanting canvas of CAR technology: Unveiling its wonders in non-neoplastic diseases

Chimeric antigen receptor (CAR) T cells have made a groundbreaking advancement in personalized immunotherapy and achieved widespread success in hematological malignancies. As CAR technology continues to evolve, numerous studies have unveiled its potential far beyond the realm of oncology. This review focuses on the current applications of CAR-based cellular platforms in non-neoplastic indications, such as autoimmune, infectious, fibrotic, and cellular senescence-associated diseases. Furthermore, we delve into the utilization of CARs in non-T cell populations such as natural killer (NK) cells and macrophages, highlighting their therapeutic potential in non-neoplastic conditions and offering the potential for targeted, personalized therapies to improve patient outcomes and enhanced quality of life.

Premature thymic functional senescence is a hallmark of childhood acute lymphoblastic leukemia survivorship

Childhood acute lymphoblastic leukemia (cALL) survivors suffer early-onset chronic diseases classically associated with aging. Normal aging is accompanied by organ dysfunctions, including immunological ones. We hypothesize that thymic immunosenescence occurs in cALL survivors and that its severity may correlate with early-onset chronic diseases. The PETALE study is a cALL survivor cohort with an extensive cardiovascular and metabolic evaluation. The thymic immunosenescence biomarker, signal joint T-cell receptor excision circles (TREC), was evaluated and was highly correlated with age in healthy participants (n = 281) and cALL survivors (n = 248). We observed a systematic thymic immunoage accentuation in each cALL survivor compared to controls ranging from 5.9 to 88.3 years. The immunoage gain was independent of age at diagnosis and treatment modalities and was more severe for females. Thymic aging was associated with several pathophysiological parameters, was greater in survivors suffering from metabolic syndrome, but there was no significant association with global physical condition. The decrease in TREC was independent from blood cell counts, which were normal, suggesting a segmental aging of the thymic compartment. Indeed, increased plasmatic T cell regulatory cytokines IL-6, IL-7 and GM-CSF accompanied high immunoage gain. Our data reveal that cALL or its treatment trigger a rapid immunoage gain followed by further gradual thymic immunosenescence, similar to normal aging. This leads to an enduring shift in accentuated immunoage compared to chronological age. Thus, accentuated thymic immunosenescence is a hallmark of cALL survivorship and TREC levels could be useful immunosenescence biomarkers to help monitoring the health of cancer survivors.

Apoptosis signal-regulating kinase 1 promotes inflammation in senescence and aging

Cellular senescence is a stress-induced, permanent cell cycle arrest involved in tumor suppression and aging. Senescent cells secrete bioactive molecules such as pro-inflammatory cytokines and chemokines. This senescence-associated secretory phenotype (SASP) has been implicated in immune-mediated elimination of senescent cells and age-associated chronic inflammation. However, the mechanisms regulating the SASP are incompletely understood. Here, we show that the stress-responsive kinase apoptosis signal-regulating kinase 1 (ASK1) promotes inflammation in senescence and aging. ASK1 is activated during senescence and increases the expression of pro-inflammatory cytokines and chemokines by activating p38, a kinase critical for the SASP. ASK1-deficient mice show impaired elimination of oncogene-induced senescent cells and an increased rate of tumorigenesis. Furthermore, ASK1 deficiency prevents age-associated p38 activation and inflammation and attenuates glomerulosclerosis. Our results suggest that ASK1 is a driver of the SASP and age-associated chronic inflammation and represents a potential therapeutic target for age-related diseases.

Role of cellular senescence in inflammation and regeneration

Cellular senescence is the state in which cells undergo irreversible cell cycle arrest and acquire diverse phenotypes. It has been linked to chronic inflammation and fibrosis in various organs as well as to individual aging. Therefore, eliminating senescent cells has emerged as a potential target for extending healthy lifespans. Cellular senescence plays a beneficial role in many biological processes, including embryonic development, wound healing, and tissue regeneration, which is mediated by the activation of stem cells. Therefore, a comprehensive understanding of cellular senescence, including both its beneficial and detrimental effects, is critical for developing safe and effective treatment strategies to target senescent cells. This review provides an overview of the biological and pathological roles of cellular senescence, with a particular focus on its beneficial or detrimental functions among its various roles.

SenNet recommendations for detecting senescent cells in different tissues

Once considered a tissue culture-specific phenomenon, cellular senescence has now been linked to various biological processes with both beneficial and detrimental roles in humans, rodents and other species. Much of our understanding of senescent cell biology still originates from tissue culture studies, where each cell in the culture is driven to an irreversible cell cycle arrest. By contrast, in tissues, these cells are relatively rare and difficult to characterize, and it is now established that fully differentiated, postmitotic cells can also acquire a senescence phenotype. The SenNet Biomarkers Working Group was formed to provide recommendations for the use of cellular senescence markers to identify and characterize senescent cells in tissues. Here, we provide recommendations for detecting senescent cells in different tissues based on a comprehensive analysis of existing literature reporting senescence markers in 14 tissues in mice and humans. We discuss some of the recent advances in detecting and characterizing cellular senescence, including molecular senescence signatures and morphological features, and the use of circulating markers. We aim for this work to be a valuable resource for both seasoned investigators in senescence-related studies and newcomers to the field.

Lipids and lipid metabolism in cellular senescence: Emerging targets for age-related diseases

Cellular senescence is a kind of cellular state triggered by endogenous or exogenous stimuli, which is mainly characterized by stable cell cycle arrest and complex senescence-associated secretory phenotype (SASP). Once senescent cells accumulate in tissues, they may eventually accelerate the progression of age-related diseases, such as atherosclerosis, osteoarthritis, chronic lung diseases, cancers, etc. Recent studies have shown that the disorders of lipid metabolism are not only related to age-related diseases, but also regulate the cellular senescence process. Based on existing research evidences, the changes in lipid metabolism in senescent cells are mainly concentrated in the metabolic processes of phospholipids, fatty acids and cholesterol. Obviously, the changes in lipid-metabolizing enzymes and proteins involved in these pathways play a critical role in senescence. However, the link between cellular senescence, changes in lipid metabolism and age-related disease remains to be elucidated. Herein, we summarize the lipid metabolism changes in senescent cells, especially the senescent cells that promote age-related diseases, as well as focusing on the role of lipid-related enzymes or proteins in senescence. Finally, we explore the prospect of lipids in cellular senescence and their potential as drug targets for preventing and delaying age-related diseases.

Targeting pathological cells with senolytic drugs reduces seizures in neurodevelopmental mTOR-related epilepsy

Cortical malformations such as focal cortical dysplasia type II (FCDII) are associated with pediatric drug-resistant epilepsy that necessitates neurosurgery. FCDII results from somatic mosaicism due to post-zygotic mutations in genes of the PI3K-AKT-mTOR pathway, which produce a subset of dysmorphic cells clustered within healthy brain tissue. Here we show a correlation between epileptiform activity in acute cortical slices obtained from human surgical FCDII brain tissues and the density of dysmorphic neurons. We uncovered multiple signatures of cellular senescence in these pathological cells, including p53/p16 expression, SASP expression and senescence-associated β-galactosidase activity. We also show that administration of senolytic drugs (dasatinib/quercetin) decreases the load of senescent cells and reduces seizure frequency in an MtorS2215F FCDII preclinical mouse model, providing proof of concept that senotherapy may be a useful approach to control seizures. These findings pave the way for therapeutic strategies selectively targeting mutated senescent cells in FCDII brain tissue.

p53/MDM2 signaling pathway in aging, senescence and tumorigenesis

A wealth of evidence has emerged that there is an association between aging, senescence and tumorigenesis. Senescence, a biological process by which cells cease to divide and enter a status of permanent cell cycle arrest, contributes to aging and aging-related diseases, including cancer. Aging populations have the higher incidence of cancer due to a lifetime of exposure to cancer-causing agents, reduction of repairing DNA damage, accumulated genetic mutations, and decreased immune system efficiency. Cancer patients undergoing cytotoxic therapies, such as chemotherapy and radiotherapy, accelerate aging. There is growing evidence that p53/MDM2 (murine double minute 2) axis is critically involved in regulation of aging, senescence and oncogenesis. Therefore, in this review, we describe the functions and mechanisms of p53/MDM2-mediated senescence, aging and carcinogenesis. Moreover, we highlight the small molecular inhibitors, natural compounds and PROTACs (proteolysis targeting chimeras) that target p53/MDM2 pathway to influence aging and cancer. Modification of p53/MDM2 could be a potential strategy for treatment of aging, senescence and tumorigenesis.

SSK1-Loaded Neurotransmitter-Derived Nanoparticles for Alzheimer's Disease Therapy via Clearance of Senescent Cells

Age is a significant contributor to the onset of AD. Senolysis has been recently demonstrated to ameliorate aging-associated diseases that showing a great potential in AD therapy. However, due to the presence of BBB, the anti-AD activity of senolytics are significantly diminished. SSK1 is a prodrug that can be activated by β-gal, a lysosomal enzyme commonly upregulated in senescent cells, and thus selectively eliminates senescent cells. Furthermore, the level of β-gal is significantly correlated with conventional AD genes from clinical sequencing data. SSK1-loaded neurotransmitter -derived lipid nanoparticles are herein developed (SSK1-NPs) that revealing good BBB penetration and bioavailability of in the body. At the brain lesion, SSK1-NP treatment significantly reduces the expression of genes associated with senescence, induced senescent cells elimination, decreased amyloid-beta accumulation, and eventually improve cognitive function of aged AD mice. SSK1-NPs, a novel nanomedicine displaying potent anti-AD activity and excellent safety profile, provides a promising strategy for AD therapy.

Cross-species signaling pathways analysis inspire animal model selections for drug screening and target prediction in vascular aging diseases

Age is a significant contributing factor to the occurrence and progression of cardiovascular disease (CVD). Pharmacological treatment can effectively alleviate CVD symptoms caused by aging. However, 90% of the drugs have failed in clinics because of the loss of drug effects or the occurrence of the side effects. One of the reasons is the disparity between animal models used and the actual physiological levels in humans. Therefore, we integrated multiple datasets from single-cell and bulk-seq RNA-sequencing data in rats, monkeys, and humans to identify genes and pathways with consistent/differential expression patterns across these three species. An approach called "Cross-species signaling pathway analysis" was developed to select suitable animal models for drug screening. The effectiveness of this method was validated through the analysis of the pharmacological predictions of four known anti-vascular aging drugs used in animal/clinical experiments. The effectiveness of drugs was consistently observed between the models and clinics when they targeted pathways with the same trend in our analysis. However, drugs might have exhibited adverse effects if they targeted pathways with opposite trends between the models and the clinics. Additionally, through our approach, we discovered four targets for anti-vascular aging drugs, which were consistent with their pharmaceutical effects in literatures, showing the value of this approach. In the end, software was established to facilitate the use of "Cross-species signaling pathway analysis." In sum, our study suggests utilizing bioinformatics analysis based on disease characteristics can help in choosing more appropriate animal models.

Senolytics ameliorate the failure of bone regeneration through the cell senescence-related inflammatory signalling pathway

Stress-induced premature senescent (SIPS) cells induced by various stresses deteriorate cell functions. Dasatinib and quercetin senolytics (DQ) can alleviate several diseases by eliminating senescent cells. α-tricalcium phosphate (α-TCP) is a widely used therapeutic approach for bone restoration but induces bone formation for a comparatively long time. Furthermore, bone infection exacerbates the detrimental prognosis of bone formation during material implant surgery due to oral cavity bacteria and unintentional contamination. It is essential to mitigate the inhibitory effects on bone formation during surgical procedures. Little is known that DQ improves bone formation in Lipopolysaccharide (LPS)-contaminated implants and its intrinsic mechanisms in the study of maxillofacial bone defects. This study aims to investigate whether the administration of DQ ameliorates the impairments on bone repair inflammation and contamination by eliminating SIPS cells. α-TCP and LPS-contaminated α-TCP were implanted into Sprague-Dawley rat calvaria bone defects. Simultaneously, bone formation in the bone defects was investigated with or without the oral administration of DQ. Micro-computed tomography and hematoxylin-eosin staining showed that senolytics significantly enhanced bone formation at the defect site. Histology and immunofluorescence staining revealed that the levels of p21- and p16-positive senescent cells, inflammation, macrophages, reactive oxygen species, and tartrate-resistant acid phosphatase-positive cells declined after administering DQ. DQ could partially alleviate the production of senescent markers and senescence-associated secretory phenotypes in vitro. This study indicates that LPS-contaminated α-TCP-based biomaterials can induce cellular senescence and hamper bone regeneration. Senolytics have significant therapeutic potential in reducing the adverse osteogenic effects of biomaterial-related infections and improving bone formation capacity.

Senolytic Therapy Enabled by Senescent Cell-Sensitive Biomimetic Melanin Nano-Senolytics

Cellular senescence is a significant risk factor for aging and age-related diseases (ARD). The canonical senolytics Dasatinib and Quercetin (DQ) have shown promise in clearing senescent cells (SnCs); however, the lack of selectivity poses a challenge in achieving optimal outcomes. Despite the recent occurrence of nanomaterial-based approaches targeting SnCs, limited therapeutic effects, and potential toxicity still remain a major concern. Herein, a "double locks-like" nanoplatform is developed that integrated Galactan coating and mesoporous polydopamine to encase the senolytic drug DQ. By this way, DQ is only released in SnCs that are featured with higher levels of β-galactosidase (β-gal) and low PH. Additionally, the nanoparticles are equipped with 2,2,6,6-Tetramethylpiperidine-1-oxyl (Tempo) to gain enhanced photothermal converting potential. Consequently, the synthesized nanosenolytics demonstrate remarkable specificity and efficacy in eradicating SnCs, and accordingly reverse pulmonary fibrosis in mice without affecting normal tissues. Upon exposure of near-infrared (NIR) light, the nanoparticles demonstrate to efficiently remove senescent tumor cells inducted by chemotherapy, thereby hindering the outgrowth and metastasis or breast cancer. Collectively, the present study develops an "On/Off" switchable nanoplatform in response to SnCs, and produces a more safe, efficient, and feasible way to delay aging or alleviate age-associated diseases.

Molecular mechanisms of aging and anti-aging strategies

Aging is a complex and multifaceted process involving a variety of interrelated molecular mechanisms and cellular systems. Phenotypically, the biological aging process is accompanied by a gradual loss of cellular function and the systemic deterioration of multiple tissues, resulting in susceptibility to aging-related diseases. Emerging evidence suggests that aging is closely associated with telomere attrition, DNA damage, mitochondrial dysfunction, loss of nicotinamide adenine dinucleotide levels, impaired macro-autophagy, stem cell exhaustion, inflammation, loss of protein balance, deregulated nutrient sensing, altered intercellular communication, and dysbiosis. These age-related changes may be alleviated by intervention strategies, such as calorie restriction, improved sleep quality, enhanced physical activity, and targeted longevity genes. In this review, we summarise the key historical progress in the exploration of important causes of aging and anti-aging strategies in recent decades, which provides a basis for further understanding of the reversibility of aging phenotypes, the application prospect of synthetic biotechnology in anti-aging therapy is also prospected.

Targeted Drug Therapy for Senescent Cells Alleviates Unilateral Ureteral Obstruction-Induced Renal Injury in Rats

Hydronephrosis resulting from unilateral ureteral obstruction (UUO) is a common cause of renal injury, often progressing to late-stage renal fibrosis or even potential renal failure. Renal injury and repair processes are accompanied by changes in cellular senescence phenotypes. However, the mechanism is poorly understood. The purpose of this study is to clarify the changes in senescence phenotype at different time points in renal disease caused by UUO and to further investigate whether eliminating senescent cells using the anti-senescence drug ABT263 could attenuate UUO-induced renal disease. Specifically, renal tissues were collected from established UUO rat models on days 1, 2, 7, and 14. The extent of renal tissue injury and fibrosis in rats was assessed using histological examination, serum creatinine, and blood urea nitrogen levels. The apoptotic and proliferative capacities of renal tissues and phenotypic changes in cellular senescence were evaluated. After the intervention of the anti-senescence drug ABT263, the cellular senescence as well as tissue damage changes were re-assessed. We found that before the drug intervention, the UUO rats showed significantly declined renal function, accompanied by renal tubular injury, increased inflammatory response, and oxidative stress, alongside aggravated cellular senescence. Meanwhile, after the treatment with ABT263, the rats had a significantly lower number of senescent cells, attenuated renal tubular injury and apoptosis, enhanced proliferation, reduced oxidative stress and inflammation, improved renal function, and markedly inhibited fibrosis. This suggests that the use of the anti-senescence drug ABT263 to eliminate senescent cells can effectively attenuate UUO-induced renal injury. This highlights the critical role of cellular senescence in the transformation of acute injury into chronic fibrosis.

A Youthful Touch: Reversal of Aging Hallmarks by Cell Reprogramming

BACKGROUND

With the elderly population projected to double by 2050, there is an urgent need to address the increasing prevalence of age-related debilitating diseases and ultimately minimize discrepancies between the rising lifespan and stagnant health span. Cellular reprogramming by overexpression of Oct3/4, Klf4, Sox2, and cMyc (OKSM) transcription factors is gaining attention in this context thanks to demonstrated rejuvenating effects in human cell cultures and live mice, many of which can be uncoupled from dedifferentiation and loss of cell identity.

SUMMARY

Here, we review current evidence of the impact of cell reprogramming on established aging hallmarks and the underlying mechanisms that mediate these effects. We also provide a critical assessment of the challenges in translating these findings and, overall, cell reprogramming technologies into clinically translatable antiaging interventions.

KEY MESSAGES

Cellular reprogramming has the potential to reverse at least partially some key hallmarks of aging. However, further research is necessary to determine the biological significance and duration of such changes and to ensure the safety of cell reprogramming as a rejuvenation approach. With this review, we hope to stimulate new research directions in the quest to extend health span effectively.

Prototyping an Ontological Framework for Cellular Senescence Mechanisms: A Homeostasis Imbalance Perspective

Although cellular senescence is a key factor in organismal aging, with both positive and negative effects on individuals, its mechanisms remain largely unknown. Thus, integrating knowledge is essential to explain how cellular senescence manifests in tissue damage and age-related diseases. Here, we propose an ontological model that organizes knowledge of cellular senescence in a computer-readable form. We manually annotated and defined cellular senescence processes, molecules, anatomical structures, phenotypes, and other entities based on the Homeostasis Imbalance Process ontology (HOIP). We described the mechanisms as causal relationships of processes and modelled a homeostatic imbalance between stress and stress response in cellular senescence for a unified framework. HOIP was assessed formally, and the relationships between cellular senescence and diseases were inferred for higher-order knowledge processing. We visualized cellular senescence processes to support knowledge utilization. Our study provides a knowledge base to help elucidate mechanisms linking cellular and organismal aging.

Selective Elimination of Senescent Cancer Cells by Galacto-Modified PROTACs

Although the selective and effective clearance of senescent cancer cells can improve cancer treatment, their development is confronted by many challenges. As part of efforts designed to overcome these problems, prodrugs, whose design is based on senescence-associated β-galactosidase (SA-β-gal), have been developed to selectively eliminate senescent cells. However, chemotherapies relying on targeted molecular inhibitors as senolytic drugs can induce drug resistance. In the current investigation, we devised a new strategy for selective degradation of target proteins in senescent cancer cells that utilizes a prodrug composed of the SA-β-gal substrate galactose (galacto) and the proteolysis-targeting chimeras (PROTACs) as senolytic agents. Prodrugs Gal-ARV-771 and Gal-MS99 were found to display senolytic indexes higher than those of ARV-771 and MS99. Significantly, results of in vivo studies utilizing a human lung A549 xenograft mouse model demonstrated that concomitant treatment with etoposide and Gal-ARV-771 leads to a significant inhibition of tumor growth without eliciting significant toxicity.

Single-cell senescence identification reveals senescence heterogeneity, trajectory, and modulators

Cellular senescence underlies many aging-related pathologies, but its heterogeneity poses challenges for studying and targeting senescent cells. We present here a machine learning program senescent cell identification (SenCID), which accurately identifies senescent cells in both bulk and single-cell transcriptome. Trained on 602 samples from 52 senescence transcriptome datasets spanning 30 cell types, SenCID identifies six major senescence identities (SIDs). Different SIDs exhibit different senescence baselines, stemness, gene functions, and responses to senolytics. SenCID enables the reconstruction of senescent trajectories under normal aging, chronic diseases, and COVID-19. Additionally, when applied to single-cell Perturb-seq data, SenCID helps reveal a hierarchy of senescence modulators. Overall, SenCID is an essential tool for precise single-cell analysis of cellular senescence, enabling targeted interventions against senescent cells.

Targeting senescent cells with NKG2D-CAR T cells

This study investigates the efficacy of NKG2D chimeric antigen receptor (CAR) engineered T cells in targeting and eliminating stress-induced senescent cells in vitro. Cellular senescence contributes to age-related tissue decline and is characterized by permanent cell cycle arrest and the senescence-associated secretory phenotype (SASP). Immunotherapy, particularly CAR-T cell therapy, emerges as a promising approach to selectively eliminate senescent cells. Our focus is on the NKG2D receptor, which binds to ligands (NKG2DLs) upregulated in senescent cells, offering a target for CAR-T cells. Using mouse embryonic fibroblasts (MEFs) and astrocytes (AST) as senescence models, we demonstrate the elevated expression of NKG2DLs in response to genotoxic and oxidative stress. NKG2D-CAR T cells displayed potent cytotoxicity against these senescent cells, with minimal effects on non-senescent cells, suggesting their potential as targeted senolytics. In conclusion, our research presents the first evidence of NKG2D-CAR T cells' ability to target senescent brain cells, offering a novel approach to manage senescence-associated diseases. The findings pave the way for future investigations into the therapeutic applicability of NKG2D-targeting CAR-T cells in naturally aged organisms and models of aging-associated brain diseases in vivo.

CAR T treatment beyond cancer: Hope for immunomodulatory therapy of non-cancerous diseases

Engineering a patient's own T cells to accurately identify and eliminate cancer cells has effectively cured individuals afflicted with previously incurable hematologic cancers. These findings have stimulated research into employing chimeric antigen receptor (CAR) T therapy across various areas within the field of oncology. However, evidence from both clinical and preclinical investigations emphasize the broader potential of CAR T therapy, extending beyond oncology to address autoimmune disorders, persistent infections, cardiac fibrosis, age-related ailments and other conditions. Concurrently, the advent of novel technologies and platforms presents additional avenues for utilizing CAR T therapy in non-cancerous contexts. This review provides an overview of the rationale behind CAR T therapy, delineates ongoing challenges in its application to cancer treatment, summarizes recent findings in non-cancerous diseases, and engages in discourse regarding emerging technologies that bear relevance. The review delves into prospective applications of this therapeutic approach across a diverse range of scenarios. Lastly, the review underscores concerns related to precision and safety, while also outlining the envisioned trajectory for extending CAR T therapy beyond cancer treatment.

Osteopontin Rejuvenates Senescent Adipose-Derived Stem Cells and Restores their Bone Tissue Regenerative Function

The regenerative function of stem cells is compromised when the proportion of senescent stem cells increases with ageing advance. Therefore, combating stem cell senescence is of great importance for stem cell-based tissue engineering in the elderly, but remains largely unexplored. Osteopontin (OPN), a glycosylated phosphoprotein, is one of the key extracellular matrix molecules in bone tissue. OPN activates various signalling pathways and modulates cellular activities, including cell senescence. However, the role of OPN in stem cell senescence remains largely unknown. This study aims to investigate if OPN modulates cell senescence and bone regenerative function in human adipose-derived mesenchymal stem cells (ASCs), and to determine the underlying mechanisms. We first developed a senescent ASC model using serial passaging until passage 10 (P10), in which senescent cells were characterised by reduced proliferation and osteogenic differentiation capacity compared to P4 ASCs. The conditioned medium from P10 ASCs exhibited a diminished trophic effect on human osteoblasts (HOBs), compared to that from P4 ASCs. P10 ASCs on OPN-coated surface showed rejuvenated phenotype and enhanced osteogenic differentiation. The conditioned medium from P10 ASCs on OPN-coating improved trophic effects on HOBs. OPN regulated the morphology of senescent ASCs, transforming them from a more rounded and flattened cell shape to an elongated shape with a smaller area. These findings demonstrated the effects of OPN in restoring senescent ASCs functions, possibly through a mechanism that involves the modulation of cell morphology, indicating that OPN might hold a great potential for rejuvenating senescent stem cells and could potentially open a new venue for regenerating bone tissue in age-related diseases.

Biomaterial design for regenerating aged bone: materiobiological advances and paradigmatic shifts

China's aging demographic poses a challenge for treating prevalent bone diseases impacting life quality. As bone regeneration capacity diminishes with age due to cellular dysfunction and inflammation, advanced biomaterials-based approaches offer hope for aged bone regeneration. This review synthesizes materiobiology principles, focusing on biomaterials that target specific biological functions to restore tissue integrity. It covers strategies for stem cell manipulation, regulation of the inflammatory microenvironment, blood vessel regeneration, intervention in bone anabolism and catabolism, and nerve regulation. The review also explores molecular and cellular mechanisms underlying aged bone regeneration and proposes a database-driven design process for future biomaterial development. These insights may also guide therapies for other age-related conditions, contributing to the pursuit of 'healthy aging'.

Cellular senescence in acute kidney injury: Target and opportunity

Acute kidney injury (AKI) is a common clinical disease with a high incidence and mortality rate. It typically arises from hemodynamic alterations, sepsis, contrast agents, and toxic drugs, instigating a series of events that culminate in tissue and renal damage. This sequence of processes often leads to acute renal impairment, prompting the initiation of a repair response. Cellular senescence is an irreversible arrest of the cell cycle. Studies have shown that renal cellular senescence is closely associated with AKI through several mechanisms, including the promotion of oxidative stress and inflammatory response, telomere shortening, and the down-regulation of klotho expression. Exploring the role of cellular senescence in AKI provides innovative therapeutic ideas for both the prevention and treatment of AKI. Furthermore, it has been observed that targeted removal of senescent cells in vivo can efficiently postpone senescence, resulting in an enhanced prognosis for diseases associated with senescence. This article explores the effects of common anti-senescence drugs senolytics and senostatic and lifestyle interventions on renal diseases, and mentions the rapid development of mesenchymal stem cells (MSCs). These studies have taken senescence-related research to a new level. Overall, this article comprehensively summarizes the studies on cellular senescence in AKI, aiming is to elucidate the relationship between cellular senescence and AKI, and explore treatment strategies to improve the prognosis of AKI.

Osteoarthritis: Insights into Diagnosis, Pathophysiology, Therapeutic Avenues, and the Potential of Natural Extracts

Osteoarthritis (OA) stands as a prevalent and progressively debilitating clinical condition globally, impacting joint structures and leading to their gradual deterioration through inflammatory mechanisms. While both non-modifiable and modifiable factors contribute to its onset, numerous aspects of OA pathophysiology remain elusive despite considerable research strides. Presently, diagnosis heavily relies on clinician expertise and meticulous differential diagnosis to exclude other joint-affecting conditions. Therapeutic approaches for OA predominantly focus on patient education for self-management alongside tailored exercise regimens, often complemented by various pharmacological interventions primarily targeting pain alleviation. However, pharmacological treatments typically exhibit short-term efficacy and local and/or systemic side effects, with prosthetic surgery being the ultimate resolution in severe cases. Thus, exploring the potential integration or substitution of conventional drug therapies with natural compounds and extracts emerges as a promising frontier in enhancing OA management. These alternatives offer improved safety profiles and possess the potential to target specific dysregulated pathways implicated in OA pathogenesis, thereby presenting a holistic approach to address the condition's complexities.

Iron retardation in lysosomes protects senescent cells from ferroptosis

Ferroptosis, an iron-triggered modality of cellular death, has been reported to closely relate to human aging progression and aging-related diseases. However, the involvement of ferroptosis in the development and maintenance of senescent cells still remains elusive. Here, we established a doxorubicin-induced senescent HSkM cell model and found that both iron accumulation and lipid peroxidation increase in senescent cells. Moreover, such iron overload in senescent cells has changed the expression panel of the ferroptosis-response proteins. Interestingly, the iron accumulation and lipid peroxidation does not trigger ferroptosis-induced cell death. Oppositely, senescent cells manifest resistance to the ferroptosis inducers, compared to the proliferating cells. To further investigate the mechanism of ferroptosis-resistance for senescent cells, we traced the iron flux in cell and found iron arrested in lysosome. Moreover, disruption of lysosome functions by chloroquine and LLOMe dramatically triggered the senescent cell death. Besides, the ferroitinophagy-related proteins FTH1/FTL and NCOA4 knockdown also increases the senescent cell death. Thus, we speculated that iron retardation in lysosome of senescent cells is the key mechanism for ferroptosis resistance. And the lysosome is a promising target for senolytic drugs to selectively clear senescent cells and alleviate the aging related diseases.

Cellular Senescence as a Targetable Risk Factor for Cardiovascular Diseases: Therapeutic Implications: JACC Family Series

The prevalence of cardiovascular diseases markedly rises with age. Cellular senescence, a hallmark of aging, is characterized by irreversible cell cycle arrest and the manifestation of a senescence-associated secretory phenotype, which has emerged as a significant contributor to aging, mortality, and a spectrum of chronic ailments. An increasing body of preclinical and clinical research has established connections between senescence, senescence-associated secretory phenotype, and age-related cardiac and vascular pathologies. This review comprehensively outlines studies delving into the detrimental impact of senescence on various cardiovascular diseases, encompassing systemic atherosclerosis (including coronary artery disease, stroke, and peripheral arterial disease), as well as conditions such as hypertension, congestive heart failure, arrhythmias, and valvular heart diseases. In addition, we have preclinical studies demonstrating the beneficial effects of senolytics-a class of drugs designed to eliminate senescent cells selectively across diverse cardiovascular disease scenarios. Finally, we address knowledge gaps on the influence of senescence on cardiovascular systems and discuss the future trajectory of strategies targeting senescence for cardiovascular diseases.

Senescence in head and neck squamous cell carcinoma: relationship between senescence-associated secretory phenotype (SASP) mRNA expression level and clinicopathological features

BACKGROUND

Cellular senescence is a state characterized by cell-cycle arrest and apoptotic resistance. Senescence in cancer may be induced by oncogenes or therapy. While cellular senescence might play an important role in protection against cancer development, elevated and uncontrolled senescent cells accumulation may promote carcinogenesis by secreting a collection of pro-inflammatory factors, collectively termed the senescence-associated secretory phenotype (SASP).

MATERIAL AND METHODS

We determined the gene expression at mRNA level of selected cellular senescence markers (p16 and LMNB1) and SASP factors (IL-6, IL-1b, CXCL-1 and TNF-α) in 72 cancerous tissues and 64 normal tissues obtained from patients with head and neck squamous cell carcinoma (HNSCC) and correlated this data with patients' clinical follow-up.

RESULTS

Our results indicate higher levels of selected SASP factors in cancerous compared to normal tissues. We presented the relationship between SASP factors expression at the transcript level and the progression of the disease. Moreover, we proposed CXCL1 as a candidate biomarker differentiating normal tissues from cancerous ones and IL1b expression as a molecular factor related to increased TNM stage.

CONCLUSION

Our primary study indicates that SASP expression may be associated with some clinicopathological features. However, a more detailed study is needed to present specific role of senescence-related mechanism and SASPs especially in tumor therapy response and in relation to the patient's immune system condition.

Targeting aging and age-related diseases with vaccines

Aging is a major risk factor for numerous chronic diseases. Vaccination offers a promising strategy to combat these age-related diseases by targeting specific antigens and inducing immune responses. Here, we provide a comprehensive overview of recent advances in vaccine-based interventions targeting these diseases, including Alzheimer's disease, type II diabetes, hypertension, abdominal aortic aneurysm, atherosclerosis, osteoarthritis, fibrosis and cancer, summarizing current approaches for identifying disease-associated antigens and inducing immune responses against these targets. Further, we reflect on the recent development of vaccines targeting senescent cells, as a strategy for more broadly targeting underlying causes of aging and associated pathologies. In addition to highlighting recent progress in these areas, we discuss important next steps to advance the therapeutic potential of these vaccines, including improving and robustly demonstrating efficacy in human clinical trials, as well as rigorously evaluating the safety and long-term effects of these vaccine strategies.

Radiotherapy-Induced Astrocyte Senescence Promotes an Immunosuppressive Microenvironment in Glioblastoma to Facilitate Tumor Regrowth

Accumulating evidence suggests that changes in the tumor microenvironment caused by radiotherapy are closely related to the recurrence of glioma. However, the mechanisms by which such radiation-induced changes are involved in tumor regrowth have not yet been fully investigated. In the present study, how cranial irradiation-induced senescence in non-neoplastic brain cells contributes to glioma progression is explored. It is observed that senescent brain cells facilitated tumor regrowth by enhancing the peripheral recruitment of myeloid inflammatory cells in glioblastoma. Further, it is identified that astrocytes are one of the most susceptible senescent populations and that they promoted chemokine secretion in glioma cells via the senescence-associated secretory phenotype. By using senolytic agents after radiotherapy to eliminate these senescent cells substantially prolonged survival time in preclinical models. The findings suggest the tumor-promoting role of senescent astrocytes in the irradiated glioma microenvironment and emphasize the translational relevance of senolytic agents for enhancing the efficacy of radiotherapy in gliomas.

Macrophage senescence in health and diseases

Macrophage senescence, manifested by the special form of durable cell cycle arrest and chronic low-grade inflammation like senescence-associated secretory phenotype, has long been considered harmful. Persistent senescence of macrophages may lead to maladaptation, immune dysfunction, and finally the development of age-related diseases, infections, autoimmune diseases, and malignancies. However, it is a ubiquitous, multi-factorial, and dynamic complex phenomenon that also plays roles in remodeled processes, including wound repair and embryogenesis. In this review, we summarize some general molecular changes and several specific biomarkers during macrophage senescence, which may bring new sight to recognize senescent macrophages in different conditions. Also, we take an in-depth look at the functional changes in senescent macrophages, including metabolism, autophagy, polarization, phagocytosis, antigen presentation, and infiltration or recruitment. Furthermore, some degenerations and diseases associated with senescent macrophages as well as the mechanisms or relevant genetic regulations of senescent macrophages are integrated, not only emphasizing the possibility of regulating macrophage senescence to benefit age-associated diseases but also has an implication on the finding of potential targets or drugs clinically.