Cellular senescence: from physiology to pathology

Klotho: molecular mechanisms and emerging therapeutics in central nervous system diseases

Klotho is recognized as an aging-suppressor protein that is implicated in a variety of processes and signaling pathways. The anti-inflammatory, anti-apoptotic, anti-oxidant, and anti-tumor bioactivities of klotho have extended its application in neurosciences and made the protein popular for its lifespan-extending capacity. Furthermore, it has been demonstrated that klotho levels would reduce with aging and numerous pathologies, particularly those related to the central nervous system (CNS). Evidence supports the idea that klotho can be a key therapeutic target in CNS diseases such as amyotrophic lateral sclerosis, Parkinson's disease, stroke, and Alzheimer's disease. Reviewing the literature suggests that the upregulation of klotho expression regulates various signaling pathways related to autophagy, oxidative stress, inflammation, cognition, and ferroptosis in neurological disorders. Therefore, it has been of great interest to develop drugs or agents that boost or restore klotho levels. In this regard, the present review was designed and aimed to gather the delegated documents regarding the therapeutic potential of Klotho in CNS diseases focusing on the molecular and cellular mechanisms.

Quiescence-Origin Senescence: A New Paradigm in Cellular Aging

Cellular senescence, traditionally viewed as a consequence of proliferating and growing cells overwhelmed by extensive stresses and damage, has long been recognized as a critical cellular aging mechanism. Recent research, however, has revealed a novel pathway termed "quiescence-origin senescence", where cells directly transition into senescence from the quiescent state, bypassing cell proliferation and growth. This opinion paper presents a framework conceptualizing a continuum between quiescence and senescence with quiescence deepening as a precursor to senescence entry. We explore the triggers and controllers of this process and discuss its biological implications. Given that the majority of cells in the human body are dormant rather than proliferative, understanding quiescence-origin senescence has significant implications for tissue homeostasis, aging, cancer, and various disease processes. The new paradigm in exploring this previously overlooked senescent cell population may reshape our intervention strategies for age-related diseases and tissue regeneration.

Regulatory Effects of Senescent Mesenchymal Stem Cells: Endotheliocyte Reaction

Currently, there is a growing focus on aging and age-related diseases. The processes of aging are based on cell senescence, which results in changes in intercellular communications and pathological alterations in tissues. In the present study, we investigate the influence of senescent mesenchymal stem cells (MSCs) on endothelial cells (ECs). In order to induce senescence in MSCs, we employed a method of stress-induced senescence utilizing mitomycin C (MmC). Subsequent experiments involved the interaction of ECs with MSCs in a coculture or the treatment of ECs with the secretome of senescent MSCs. After 48 h, we assessed the EC state. Our findings revealed that direct interaction led to a decrease in EC proliferation and migratory activity of the coculture. Furthermore, there was an increase in the activity of the lysosomal compartment, as well as an upregulation of the genes P21, IL6, IL8, ITGA1, and ITGB1. Treatment of ECs with the "senescent" secretome resulted in less pronounced effects, although a decrease in proliferation and an increase in ICAM-1 expression were observed. The maintenance of high levels of typical "senescent" cytokines and growth factors after 48 h suggests that the addition of the "senescent" secretome may have a prolonged effect on the cells. It is noteworthy that in samples treated with the "senescent" secretome, the level of PDGF-AA was higher, which may explain some of the pro-regenerative effects of senescent cells. Therefore, the detected changes may underlie both the negative and positive effects of senescence. The findings provide insight into the effects of cell senescence in vitro, where many of the organism's regulatory mechanisms are absent.

Systematic bioinformatics analysis reveals the role of shikonin in blocking colon cancer progression by identifying senescence-induced genes

Shikonin, a naturally occurring naphthoquinone compound extracted from comfrey plants, has antitumor, anti-inflammatory, and antimicrobial properties. Cell senescence plays a key role in preventing tumor progression. It is unclear whether shikonin has an effect on cell senescence in colon cancer. In the current study, we first determine the IC50 values of shikonin on colon cancer cell lines HT29 and HCT116. Then, we verified the inhibitory effects of shikonin on the proliferation and migration abilities of colon cancer cell lines HT29 and HCT116 using cell counting kit-8, colony formation, and wound healing assays. Next, we identified a series of potential targets using high-throughput mRNA sequencing and identified 210 upregulated and 296 downregulated genes. KEGG profiling revealed eight downregulated genes associated with cell senescence: CCNB3, IL-1α, CXCL8, CDKN2A, MYC, IGFBP3, SQSTM1, and GADD45G. Among them, CXCL8 and CDKN2A were associated with poor prognosis in patients with colon cancer, suggesting that their downregulation by shikonin could improve patient survival. Furthermore, SA-β-galactosidase staining revealed that the percentage of cellular senescence in colon cancer cells was significantly increased after shikonin treatment. Molecular docking revealed that shikonin suppressed colon cancer progression by blocking CXCL8 activity. Based on these findings, we deem that shikonin might induce senescence and exert antitumor activity in colon cancer cells by downregulating CDKN2A and CXCL8. This provides a new molecular mechanism and potential therapeutic target for shikonin to inhibit colon cancer progression.

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.

Medicinal herbal remedies in neurodegenerative diseases: an update on antioxidant potential

It has been widely documented that medicinal herbal remedies are effective, have fewer side effects than conventional medicine, and have a synergistic effect on health collaborations in the fight against complicated diseases. Traditional treatments for neurological problems in ancient times sometimes involved the use of herbal remedies and conventional methods from East Asian countries including India, Japan, China, and Korea. We collected and reviewed studies on plant-derived neuroprotective drugs and tested them in neurotoxic models. Basic research, preclinical and clinical transgene research can benefit from in silico, in vitro, and in vivo investigations. Research, summaries of the extracts, fractions, and herbal ingredients were compiled from popular scientific databases, which were then examined according to origin and bioactivity. Given the complex and varied causes of neurodegeneration, it may be beneficial to focus on multiple mechanisms of action and a neuroprotection approach. This approach aims to prevent cell death and restore function to damaged neurons, offering promising strategies for preventing and treating neurodegenerative diseases. Neurodegenerative illnesses can potentially be treated with natural compounds that have been identified as neuroprotective agents. To gain deeper insights into the neuropharmacological mechanisms underlying the neuroprotective and therapeutic properties of naturally occurring antioxidant phytochemical compounds in diverse neurodegenerative diseases, this study aims to comprehensively review such compounds, focusing on their modulation of apoptotic markers such as caspase, Bax, Bcl-2, and proinflammatory markers. In addition, we delve into a range of efficacies of antioxidant phytochemical compounds as neuroprotective agents in animal models. They reduce the oxidative stress of the brain and have been shown to have anti-apoptotic effects. Many researches have demonstrated that plant extracts or bioactive compounds can fight neurodegenerative disorders. Herbal medications may offer neurodegenerative disease patients' new treatments. This may be a cheaper and more culturally appropriate alternative to standard drugs for millions of people with age-related NDDs.

Quercetin induces senolysis of doxorubicin-induced senescent fibroblasts by reducing autophagy, preventing their pro-tumour effect on osteosarcoma cells

Cellular senescence contributes to ageing and age-related diseases, and multiple therapeutic strategies are being developed to counteract it. Senolytic drugs are being tested in clinical trials to eliminate senescent cells selectively, but their effects and mechanisms are still unclear. Several studies reveal that the upregulation of senescence-associated secretory phenotype (SASP) factors in senescent cells is accompanied by increased autophagic activity to counteract the endoplasmic reticulum (ER) stress. Our study shows that Doxo-induced senescent fibroblasts yield several SASP factors and exhibit increased autophagy. Interestingly, Quercetin, a bioactive flavonoid, reduces autophagy, increases ER stress, and partially triggers senescent fibroblast death. Given the role of senescent cells in cancer progression, we tested the effect of conditioned media from untreated and quercetin-treated senescent fibroblasts on osteosarcoma cells to determine whether senolytic treatment affected tumour cell behaviour. We report that the partial senescent fibroblast clearance, achieved by quercetin, reduced osteosarcoma cell invasiveness, curbing the pro-tumour effects of senescent cells. The reduction of cell autophagic activity and increased ER stress, an undescribed effect of quercetin, emerges as a new vulnerability of Doxo-induced senescent fibroblasts and may provide a potential therapeutic target for cancer treatment, suggesting novel drug combinations as a promising strategy against the tumour.

Egr1 regulates regenerative senescence and cardiac repair

Senescence plays a key role in various physiological and pathological processes. We reported that injury-induced transient senescence correlates with heart regeneration, yet the multi-omics profile and molecular underpinnings of regenerative senescence remain obscure. Using proteomics and single-cell RNA sequencing, here we report the regenerative senescence multi-omic signature in the adult mouse heart and establish its role in neonatal heart regeneration and agrin-mediated cardiac repair in adult mice. We identified early growth response protein 1 (Egr1) as a regulator of regenerative senescence in both models. In the neonatal heart, Egr1 facilitates angiogenesis and cardiomyocyte proliferation. In adult hearts, agrin-induced senescence and repair require Egr1, activated by the integrin-FAK-ERK-Akt1 axis in cardiac fibroblasts. We also identified cathepsins as injury-induced senescence-associated secretory phenotype components that promote extracellular matrix degradation and potentially assist in reducing fibrosis. Altogether, we uncovered the molecular signature and functional benefits of regenerative senescence during heart regeneration, with Egr1 orchestrating the process.

β-Galactosidase-Triggered Photodynamic Elimination of Senescent Cells with a Boron Dipyrromethene-Based Photosensitizer

Senescence is a cellular response having physiological and reparative functions to preserve tissue homeostasis and suppress tumor growth. However, the accumulation of senescent cells would cause deleterious effects that lead to age-related dysfunctions and cancer progression. Hence, selective detection and elimination of senescent cells are crucial yet remain a challenge. A β-galactosidase (β-gal)-activated boron dipyrromethene (BODIPY)-based photosensitizer (compound 1) is reported here that can selectively detect and eradicate senescent cells. It contains a galactose moiety connected to a pyridinium BODIPY via a self-immolative nitrophenylene linker, of which the photoactivity is effectively quenched. Upon interactions with the senescence-associated β-gal, it undergoes enzymatic hydrolysis followed by self-immolation, leading to the release of an activated BODIPY moiety by which the fluorescence emission and singlet oxygen generation are restored. The ability of 1 to detect and eliminate senescent cells is demonstrated in vitro and in vivo, using SK-Mel-103 tumor-bearing mice treated with senescence-inducing therapy. The results demonstrate that 1 can be selectively activated in senescent cells to trigger a robust senolytic effect upon irradiation. This study breaks new ground in the design and application of new senolytic agents based on photodynamic therapy.

Titan mice as a model to test interventions that attenuate frailty and increase longevity

Wild-type murine models for aging research have lifespans of several years, which results in long experimental duration and late output. Here we explore the short-lived non-inbred Titan mouse (DU6) as a mouse model to test longevity interventions. We show that Titan mice exhibit increased frailty and senescence-associated beta-galactosidase activity at an early age. Dietary intervention attenuates the frailty progression of Titan mice. Additionally, cyclic administration of the senolytic drug Navitoclax at an early age increases the lifespan and reduces senescence-associated beta-galactosidase activity. Our data suggests that Titan mice can serve as a cost-effective and timely model for longevity interventions in mammals.

Senescence in the bone marrow microenvironment: A driver in development of therapy-related myeloid neoplasms

Therapy-related myeloid neoplasms (t-MN) are a growing concern due to the continued use of cytotoxic therapies to treat malignancies. Cytotoxic therapies have been shown to drive therapy-induced senescence in normal tissues, including in the bone marrow microenvironment (BMME), which plays a crucial role in supporting normal hematopoiesis. This review examines recent work that focuses on the contribution of BMME senescence to t-MN pathogenesis, as well as offers a perspective on potential opportunities for therapeutic intervention.

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.

Intracellular acidification and glycolysis modulate inflammatory pathway in senescent cells

Senescent cells accumulate in various organs with ageing, and its accumulation induces chronic inflammation and age-related physiological dysfunctions. Several remodelling of intracellular environments have been identified in senescent cells, including enlargement of cell/nuclear size and intracellular acidification. Although these alterations of intracellular environments were reported to be involved in the unique characteristics of senescent cells, the contribution of intracellular acidification to senescence-associated cellular phenotypes is poorly understood. Here, we identified that the upregulation of TXNIP and its paralog ARRDC4 as a hallmark of intracellular acidification in addition to KGA-type GLS1. These genes were also upregulated in response to senescence-associated intracellular acidification. Neutralization of the intracellular acidic environment ameliorated not only senescence-related upregulation of TXNIP, ARRDC4 and KGA but also inflammation-related genes, possibly through suppression of PDK-dependent anaerobic glycolysis. Furthermore, we found that expression of the intracellular acidification-induced genes, TXNIP and ARRDC4, correlated with inflammatory gene expression in heterogeneous senescent cell population in vitro and even in vivo, implying that the contribution of intracellular pH to senescence-associated cellular features, such as SASP.

Investigation of differentially expressed genes related to cellular senescence between high-risk and non-high-risk groups in neuroblastoma

Object

This study aims to identify differentially expressed genes (DEGs) between high-risk and non-high-risk groups in neuroblastoma (NB), construct a prognostic model, and establish a risk score formula.

Materials and methods

The NB dataset GSE49710 (n = 498) from the GEO database served as the training cohort to select DEGs between high-risk and non-high-risk NB groups. Cellular senescence-related genes were obtained from the Aging Atlas database. Intersection genes from both datasets were identified as key genes of cellular senescence-related genes (SRGs). A prognostic model was constructed using Univariate Cox regression analysis and the Lasso algorithm with SRGs. Validation was performed using the E-MTAB-8248 cohort (n = 223). The expression levels of AURKA and CENPA were evaluated via RT-qPCR in two clinical NB sample groups.

Results

Eight SRGs were identified, and a prognostic model comprising five genes related to cellular senescence was constructed. AURKA and CENPA showed significant expression in clinical samples and were closely associated with cellular senescence.

Conclusion

The prognostic model consisted with five cellular senescence related genes effectively predicts the prognosis of NB patients. AURKA and CENPA represent promising targets in NB for predicting cellular senescence, offering potential insights for NB therapy.

Adaptation to an acid microenvironment promotes pancreatic cancer organoid growth and drug resistance

Harsh environments in poorly perfused tumor regions may select for traits driving cancer aggressiveness. Here, we investigated whether tumor acidosis interacts with driver mutations to exacerbate cancer hallmarks. We adapted mouse organoids from normal pancreatic duct (mN10) and early pancreatic cancer (mP4, KRAS-G12D mutation, ± p53 knockout) from extracellular pH 7.4 to 6.7, representing acidic niches. Viability was increased by acid adaptation, a pattern most apparent in wild-type (WT) p53 organoids, and exacerbated upon return to pH 7.4. This led to increased survival of acid-adapted organoids treated with gemcitabine and/or erlotinib, and, in WT p53 organoids, acid-induced attenuation of drug effects. New genetic variants became dominant during adaptation, yet they were unlikely to be its main drivers. Transcriptional changes induced by acid and drug adaptation differed overall, but acid adaptation increased the expression of gemcitabine resistance genes. Thus, adaptation to acidosis increases cancer cell viability after chemotherapy.

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.

Cellular Senescence and Extracellular Vesicles in the Pathogenesis and Treatment of Obesity-A Narrative Review

This narrative review explores the pathophysiology of obesity, cellular senescence, and exosome release. When exposed to excessive nutrients, adipocytes develop mitochondrial dysfunction and generate reactive oxygen species with DNA damage. This triggers adipocyte hypertrophy and hypoxia, inhibition of adiponectin secretion and adipogenesis, increased endoplasmic reticulum stress and maladaptive unfolded protein response, metaflammation, and polarization of macrophages. Such feed-forward cycles are not resolved by antioxidant systems, heat shock response pathways, or DNA repair mechanisms, resulting in transmissible cellular senescence via autocrine, paracrine, and endocrine signaling. Senescence can thus affect preadipocytes, mature adipocytes, tissue macrophages and lymphocytes, hepatocytes, vascular endothelium, pancreatic β cells, myocytes, hypothalamic nuclei, and renal podocytes. The senescence-associated secretory phenotype is closely related to visceral adipose tissue expansion and metaflammation; inhibition of SIRT-1, adiponectin, and autophagy; and increased release of exosomes, exosomal micro-RNAs, pro-inflammatory adipokines, and saturated free fatty acids. The resulting hypernefemia, insulin resistance, and diminished fatty acid β-oxidation lead to lipotoxicity and progressive obesity, metabolic syndrome, and physical and cognitive functional decline. Weight cycling is related to continuing immunosenescence and exposure to palmitate. Cellular senescence, exosome release, and the transmissible senescence-associated secretory phenotype contribute to obesity and metabolic syndrome. Targeted therapies have interrelated and synergistic effects on cellular senescence, obesity, and premature aging.

Dissecting the Natural Patterns of Progression and Senescence in Pediatric Low-Grade Glioma: From Cellular Mechanisms to Clinical Implications

Pediatric low-grade gliomas (PLGGs) comprise a heterogeneous set of low-grade glial and glioneuronal tumors, collectively representing the most frequent CNS tumors of childhood and adolescence. Despite excellent overall survival rates, the chronic nature of the disease bears a high risk of long-term disease- and therapy-related morbidity in affected patients. Recent in-depth molecular profiling and studies of the genetic landscape of PLGGs led to the discovery of the paramount role of frequent upregulation of RAS/MAPK and mTOR signaling in tumorigenesis and progression of these tumors. Beyond, the subsequent unveiling of RAS/MAPK-driven oncogene-induced senescence in these tumors may shape the understanding of the molecular mechanisms determining the versatile progression patterns of PLGGs, potentially providing a promising target for novel therapies. Recent in vitro and in vivo studies moreover indicate a strong dependence of PLGG formation and growth on the tumor microenvironment. In this work, we provide an overview of the current understanding of the multilayered cellular mechanisms and clinical factors determining the natural progression patterns and the characteristic biological behavior of these tumors, aiming to provide a foundation for advanced stratification for the management of these tumors within a multimodal treatment approach.

Exploring the Interplay between Cellular Senescence, Immunity, and Fibrosing Interstitial Lung Diseases: Challenges and Opportunities

Fibrosing interstitial lung diseases (ILDs) are characterized by the gradual and irreversible accumulation of scar tissue in the lung parenchyma. The role of the immune response in the pathogenesis of pulmonary fibrosis remains unclear. In recent years, substantial advancements have been made in our comprehension of the pathobiology driving fibrosing ILDs, particularly concerning various age-related cellular disturbances and immune mechanisms believed to contribute to an inadequate response to stress and increased susceptibility to lung fibrosis. Emerging studies emphasize cellular senescence as a key mechanism implicated in the pathobiology of age-related diseases, including pulmonary fibrosis. Cellular senescence, marked by antagonistic pleiotropy, and the complex interplay with immunity, are pivotal in comprehending many aspects of lung fibrosis. Here, we review progress in novel concepts in cellular senescence, its association with the dysregulation of the immune response, and the evidence underlining its detrimental role in fibrosing ILDs.

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.

Modelling the spatiotemporal dynamics of senescent cells in wound healing, chronic wounds, and fibrosis

Cellular senescence is known to drive age-related pathology through the senescence-associated secretory phenotype (SASP). However, it also plays important physiological roles such as cancer suppression, embryogenesis and wound healing. Wound healing is a tightly regulated process which when disrupted results in conditions such as fibrosis and chronic wounds. Senescent cells appear during the proliferation phase of the healing process where the SASP is involved in maintaining tissue homeostasis after damage. Interestingly, SASP composition and functionality was recently found to be temporally regulated, with distinct SASP profiles involved: a fibrogenic, followed by a fibrolytic SASP, which could have important implications for the role of senescent cells in wound healing. Given the number of factors at play a full understanding requires addressing the multiple levels of complexity, pertaining to the various cell behaviours, individually followed by investigating the interactions and influence each of these elements have on each other and the system as a whole. Here, a systems biology approach was adopted whereby a multi-scale model of wound healing that includes the dynamics of senescent cell behaviour and corresponding SASP composition within the wound microenvironment was developed. The model was built using the software CompuCell3D, which is based on a Cellular Potts modelling framework. We used an existing body of data on healthy wound healing to calibrate the model and validation was done on known disease conditions. The model provides understanding of the spatiotemporal dynamics of different senescent cell phenotypes and the roles they play within the wound healing process. The model also shows how an overall disruption of tissue-level coordination due to age-related changes results in different disease states including fibrosis and chronic wounds. Further specific data to increase model confidence could be used to explore senolytic treatments in wound disorders.

Corneal keratocytes, fibroblasts, and myofibroblasts exhibit distinct transcriptional profiles in vitro

Purpose

After stromal injury to the cornea, the release of growth factors and pro-inflammatory cytokines promotes the activation of quiescent keratocytes into a migratory fibroblast and/or fibrotic myofibroblast phenotype. Persistence of the myofibroblast phenotype can lead to corneal fibrosis and scarring, which are leading causes of blindness worldwide. This study aims to establish comprehensive transcriptional profiles for cultured corneal keratocytes, fibroblasts, and myofibroblasts to gain insights into the mechanisms through which these phenotypic changes occur.

Methods

Primary rabbit corneal keratocytes were cultured in either defined serum-free media (SF), fetal bovine serum (FBS) containing media, or in the presence of TGF-β1 to induce keratocyte, fibroblast, or myofibroblast phenotypes, respectively. Bulk RNA sequencing followed by bioinformatic analyses was performed to identify significant differentially expressed genes (DEGs) and enriched biological pathways for each phenotype.

Results

Genes commonly associated with keratocytes, fibroblasts, or myofibroblasts showed high relative expression in SF, FBS, or TGF-β1 culture conditions, respectively. Differential expression and functional analyses revealed novel DEGs for each cell type, as well as enriched pathways indicative of differences in proliferation, apoptosis, extracellular matrix (ECM) synthesis, cell-ECM interactions, cytokine signaling, and cell mechanics.

Conclusions

Overall, these data demonstrate distinct transcriptional differences among cultured corneal keratocytes, fibroblasts, and myofibroblasts. We have identified genes and signaling pathways that may play important roles in keratocyte differentiation, including many related to mechanotransduction and ECM biology. Our findings have revealed novel molecular markers for each cell type, as well as possible targets for modulating cell behavior and promoting physiological corneal wound healing.

An expedited screening platform for the discovery of anti-ageing compounds in vitro and in vivo

BACKGROUND

Restraining or slowing ageing hallmarks at the cellular level have been proposed as a route to increased organismal lifespan and healthspan. Consequently, there is great interest in anti-ageing drug discovery. However, this currently requires laborious and lengthy longevity analysis. Here, we present a novel screening readout for the expedited discovery of compounds that restrain ageing of cell populations in vitro and enable extension of in vivo lifespan.

METHODS

Using Illumina methylation arrays, we monitored DNA methylation changes accompanying long-term passaging of adult primary human cells in culture. This enabled us to develop, test, and validate the CellPopAge Clock, an epigenetic clock with underlying algorithm, unique among existing epigenetic clocks for its design to detect anti-ageing compounds in vitro. Additionally, we measured markers of senescence and performed longevity experiments in vivo in Drosophila, to further validate our approach to discover novel anti-ageing compounds. Finally, we bench mark our epigenetic clock with other available epigenetic clocks to consolidate its usefulness and specialisation for primary cells in culture.

RESULTS

We developed a novel epigenetic clock, the CellPopAge Clock, to accurately monitor the age of a population of adult human primary cells. We find that the CellPopAge Clock can detect decelerated passage-based ageing of human primary cells treated with rapamycin or trametinib, well-established longevity drugs. We then utilise the CellPopAge Clock as a screening tool for the identification of compounds which decelerate ageing of cell populations, uncovering novel anti-ageing drugs, torin2 and dactolisib (BEZ-235). We demonstrate that delayed epigenetic ageing in human primary cells treated with anti-ageing compounds is accompanied by a reduction in senescence and ageing biomarkers. Finally, we extend our screening platform in vivo by taking advantage of a specially formulated holidic medium for increased drug bioavailability in Drosophila. We show that the novel anti-ageing drugs, torin2 and dactolisib (BEZ-235), increase longevity in vivo.

CONCLUSIONS

Our method expands the scope of CpG methylation profiling to accurately and rapidly detecting anti-ageing potential of drugs using human cells in vitro, and in vivo, providing a novel accelerated discovery platform to test sought after anti-ageing compounds and geroprotectors.

Identification of diagnostic markers related to inflammatory response and cellular senescence in endometriosis using machine learning and in vitro experiment

OBJECTIVE

To understand the association between chronic inflammation, cellular senescence, and immunological infiltration in endometriosis.

METHODS

Datasets from GEO comprising 108 endometriosis and 97 healthy human samples and the human endometrial stromal cell. Differentially expressed genes were identified using Limma and WGCNA. Inflammatory response-related subtypes were constructed using consensus clustering analysis. The CIBERSORT algorithm and correlation analyses assessed immune cell infiltration. LASSO, SVM-RFE, and RF identified diagnostic genes. Functional enrichment analysis and multifactor regulatory networks established functional effects. Nomograms, internal and external validations, and in vitro experiments validated the diagnostic genes.

RESULTS

Inflammatory response subtypes were highly correlated with the immune activities of B and NK cells. Sixteen genes were associated with inflammatory response and cellular senescence and six diagnostic genes (NLK, RAD51, TIMELESS, TBX3, MET, and BTG3) were identified. The six diagnostic gene models had an area under the curve of 0.828 and their expression was significantly downregulated in endometriosis samples. Low expression of NLK and BTG3 promoted the proliferation, migration, and invasion of endometriotic cells.

CONCLUSIONS

Inflammatory response subtypes were successfully constructed for endometriosis. Six diagnostic genes related to inflammatory response and cellular senescence were identified and validated. Our study provides novel insights for inflammatory response in endometriosis and markers for endometriosis diagnosis and treatment.

Cell senescence in liver diseases: pathological mechanism and theranostic opportunity

The liver is not oblivious to the passage of time, as ageing is a major risk factor for the development of acute and chronic liver diseases. Ageing produces alterations in all hepatic cells, affecting their phenotype and function and worsening the prognosis of liver disease. The ageing process also implies the accumulation of a cellular state characterized by a persistent proliferation arrest and a specific secretory phenotype named cellular senescence. Indeed, senescent cells have key roles in many physiological processes; however, their accumulation owing to ageing or pathological conditions contributes to the damage occurring in chronic diseases. The aim of this Review is to provide an updated description of the pathophysiological events in which hepatic senescent cells are involved and their role in liver disease progression. Finally, we discuss novel geroscience therapies that could be applied to prevent or improve liver diseases and age-mediated hepatic deregulations.

Beyond typical histology of BAP1-inactivated melanocytoma

BAP1-inactivated melanocytoma (BIM) is a novel subgroup of melanocytic neoplasm listed in the 5th edition of WHO classification of skin tumor. BIM is characterized by two molecular alterations, including a mitogenic driver mutation (usually BRAF gene) and the loss of function of BAP1, a tumor suppressor gene located on chromosome 3p21, which encodes for BRCA1-associated protein (BAP1). The latter represents a nuclear-localized deubiquitinase involved in several cellular processes including cell cycle regulation, chromatin remodeling, DNA damage response, differentiation, senescence and cell death. BIMs are histologically characterized by a population of large epithelioid melanocytes with well-demarcated cytoplasmic borders and copious eosinophilic cytoplasm, demonstrating loss of BAP1 nuclear expression by immunohistochemistry. Recently, we have published a series of 50 cases, extending the morphological spectrum of the neoplasm and highlighting some new microscopic features. In the current article, we focus on some new histological features, attempting to explain and link them to certain mechanisms of tumor development, including senescence, endoreplication, endocycling, asymmetric cytokinesis, entosis and others. In light of the morphological and molecular findings observed in BIM, we postulated that this entity unmasks a fine mechanism of tumor in which both clonal/stochastic and hierarchical model can be unified.

Combating Atherosclerosis with Chirality/Phase Dual-Engineered Nanozyme Featuring Microenvironment-Programmed Senolytic and Senomorphic Actions

Senescence plays a critical role in the development and progression of various diseases. This study introduces an amorphous, high-entropy alloy (HEA)-based nanozyme designed to combat senescence. By adjusting the nanozyme's composition and surface properties, this work analyzes its catalytic performance under both normal and aging conditions, confirming that peroxide and superoxide dismutase (SOD) activity are crucial for its anti-aging therapeutic function. Subsequently, the chiral-dependent therapeutic effect is validated and the senolytic performance of D-handed PtPd2CuFe across several aging models is confirmed. Through multi-Omics analyses, this work explores the mechanism underlying the senolytic action exerted by nanozyme in depth. It is confirm that exposure to senescent conditions leads to the enrichment of copper and iron atoms in their lower oxidation states, disrupting the iron-thiol cluster in mitochondria and lipoic acid transferase, as well as oxidizing unsaturated fatty acids, triggering a cascade of cuproptosis and ferroptosis. Additionally, the concentration-dependent anti-aging effects of nanozyme is validated. Even an ultralow dose, the therapeutic can still act as a senomorphic, reducing the effects of senescence. Given its broad-spectrum action and concentration-adjustable anti-aging potential, this work confirms the remarkable therapeutic capability of D-handed PtPd2CuFe in managing atherosclerosis, a disease involving various types of senescent cells.

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.

The Role of Aging and Senescence in Immune Checkpoint Inhibitor Response and Toxicity

Cellular senescence accumulates with age and has been shown to impact numerous physiological and pathological processes, including immune function. The role of cellular senescence in cancer is multifaceted, but the impact on immune checkpoint inhibitor response and toxicity has not been fully evaluated. In this review, we evaluate the impact of cellular senescence in various biological compartments, including the tumor, the tumor microenvironment, and the immune system, on immune checkpoint inhibitor efficacy and toxicity. We provide an overview of the impact of cellular senescence in normal and pathological contexts and examine recent studies that have connected aging and cellular senescence to immune checkpoint inhibitor treatment in both the pre-clinical and clinical contexts. Overall, senescence plays a multi-faceted, context-specific role and has been shown to modulate immune-related adverse event incidence as well as immune checkpoint inhibitor response.

Roles of pigment epithelium-derived factor in exercise-induced suppression of senescence and its impact on lung pathology in mice

Senescent cells contribute to tissue aging and underlie the pathology of chronic diseases. The benefits of eliminating senescent cells have been demonstrated in several disease models, and the efficacy of senolytic drugs is currently being tested in humans. Exercise training has been shown to reduce cellular senescence in several tissues; however, the mechanisms responsible remain unclear. We found that myocyte-derived factors significantly extended the replicative lifespan of fibroblasts, suggesting that myokines mediate the anti-senescence effects of exercise. A number of proteins within myocyte-derived factors were identified by mass spectrometry. Among these, pigment epithelium-derived factor (PEDF) exerted inhibitory effects on cellular senescence. Eight weeks of voluntary running increased Pedf levels in skeletal muscles and suppressed senescence markers in the lungs. The administration of PEDF reduced senescence markers in multiple tissues and attenuated the decline in respiratory function in the pulmonary emphysema mouse model. We also showed that blood levels of PEDF inversely correlated with the severity of COPD in patients. Collectively, these results strongly suggest that PEDF contributes to the beneficial effects of exercise, potentially suppressing cellular senescence and its associated pathologies.

FGF receptors mediate cellular senescence in the cystic fibrosis airway epithelium

The number of adults living with cystic fibrosis (CF) has already increased significantly because of drastic improvements in life expectancy attributable to advances in treatment, including the development of highly effective modulator therapy. Chronic airway inflammation in CF contributes to morbidity and mortality, and aging processes like inflammaging and cell senescence influence CF pathology. Our results show that single-cell RNA sequencing data, human primary bronchial epithelial cells from non-CF and CF donors, a CF bronchial epithelial cell line, and Cftr-knockout (Cftr-/-) rats all demonstrated increased cell senescence markers in the CF bronchial epithelium. This was associated with upregulation of fibroblast growth factor receptors (FGFRs) and mitogen-activated protein kinase (MAPK) p38. Inhibition of FGFRs, specifically FGFR4 and to some extent FGFR1, attenuated cell senescence and improved mucociliary clearance, which was associated with MAPK p38 signaling. Mucociliary dysfunction could also be improved using a combination of senolytics in a CF ex vivo model. In summary, FGFR/MAPK p38 signaling contributes to cell senescence in CF airways, which is associated with impaired mucociliary clearance. Therefore, attenuation of cell senescence in the CF airways might be a future therapeutic strategy improving mucociliary dysfunction and lung disease in an aging population with CF.

Non-Canonical STING-PERK Pathway Modulation of Cellular Senescence and Therapeutic Response in Sepsis-Associated Acute Kidney Injury

Abstract-This study explored the role of the non-canonical STING-PERK signaling pathway in sepsis-associated acute kidney injury (SA-AKI). Gene expression data from the GEO database and serum STING protein levels in patients with SA-AKI were analyzed. An LPS-induced mouse model and an in vitro model using HK-2 cells were used to investigate the role of STING in SA-AKI. STING expression was suppressed using shRNA silencing technology and the STING inhibitor C176. Kidney function, inflammatory markers, apoptosis, and senescence were measured. The role of the STING-PERK pathway was investigated by silencing PERK in HK-2 cells and administering the PERK inhibitor GSK2606414. STING mRNA expression and serum STING protein levels were significantly higher in patients with SA-AKI. Suppressing STING expression improved kidney function, reduced inflammation, and inhibited apoptosis and senescence. Silencing PERK or administering GSK2606414 suppressed the inflammatory response, cell apoptosis, and senescence, suggesting that PERK is a downstream effector in the STING signaling pathway. The STING-PERK signaling pathway exacerbates cell senescence and apoptosis in SA-AKI. Inhibiting this pathway could provide potential therapeutic targets for SA-AKI treatment.

Cellular senescence in normal physiology

Long associated with aging, senescent cells can promote health and have physiological roles.

Cellular Senescence in Acute Liver Injury: What Happens to the Young Liver?

Cellular senescence, characterized by irreversible cell cycle arrest, not only exists in age-related physiological states, but has been found to exist in various diseases. It plays a crucial role in both physiological and pathological processes and has become a trending topic in global research in recent years. Acute liver injury (ALI) has a high incidence worldwide, and recent studies have shown that hepatic senescence can be induced following ALI. Therefore, we reviewed the significance of cellular senescence in ALI. To minimize the potential confounding effects of aging on cellular senescence and ALI outcomes, we selected studies involving young individuals to identify the characteristics of senescent cells, the value of cellular senescence in liver repair, its regulation mechanisms in ALI, its potential as a biomarker for ALI, the prospect of treatment, and future research directions.

An Indocyanine Green-Based Nanoprobe for In Vivo Detection of Cellular Senescence

There is an urgent need to improve conventional cancer-treatments by preventing detrimental side effects, cancer recurrence and metastases. Recent studies have shown that presence of senescent cells in tissues treated with chemo- or radiotherapy can be used to predict the effectiveness of cancer treatment. However, although the accumulation of senescent cells is one of the hallmarks of cancer, surprisingly little progress has been made in development of strategies for their detection in vivo. To address a lack of detection tools, we developed a biocompatible, injectable organic nanoprobe (NanoJagg), which is selectively taken up by senescent cells and accumulates in the lysosomes. The NanoJagg probe is obtained by self-assembly of indocyanine green (ICG) dimers using a scalable manufacturing process and characterized by a unique spectral signature suitable for both photoacoustic tomography (PAT) and fluorescence imaging. In vitro, ex vivo and in vivo studies all indicate that NanoJaggs are a clinically translatable probe for detection of senescence and their PAT signal makes them suitable for longitudinal monitoring of the senescence burden in solid tumors after chemotherapy or radiotherapy.

The dual role of sirtuins in cancer: biological functions and implications

Sirtuins are pivotal in orchestrating numerous cellular pathways, critically influencing cell metabolism, DNA repair, aging processes, and oxidative stress. In recent years, the involvement of sirtuins in tumor biology has garnered substantial attention, with a growing body of evidence underscoring their regulatory roles in various aberrant cellular processes within tumor environments. This article delves into the sirtuin family and its biological functions, shedding light on their dual roles-either as promoters or inhibitors-in various cancers including oral, breast, hepatocellular, lung, and gastric cancers. It further explores potential anti-tumor agents targeting sirtuins, unraveling the complex interplay between sirtuins, miRNAs, and chemotherapeutic drugs. The dual roles of sirtuins in cancer biology reflect the complexity of targeting these enzymes but also highlight the immense therapeutic potential. These advancements hold significant promise for enhancing clinical outcomes, marking a pivotal step forward in the ongoing battle against cancer.

Sexual dimorphism association of combined exposure to volatile organic compounds (VOC) with kidney damage

BACKGROUND

Epidemiological evidence emphasizes air pollutants' role in chronic kidney disease (CKD). Volatile organic compounds (VOCs) contribute to air pollution, yet research on VOCs and kidney damage, especially gender disparities, is limited.

METHODS

This study analyzed NHANES data to explore associations between urinary VOC metabolite mixtures (VOCMs) and key kidney-related parameters: estimated glomerular filtration rate (eGFR), albumin-to-creatinine ratio (ACR), chronic kidney disease (CKD), and albuminuria. Mediation analyses assessed the potential mediating roles of biological aging (BA) and serum albumin in VOCM mixtures' effects on kidney damage. Sensitivity analyses were also conducted.

RESULTS

The mixture analysis unveiled a noteworthy positive association between VOCM mixtures and the risk of developing CKD, coupled with a significant negative correlation with eGFR within the overall participant cohort. These findings remained consistent when examining the female subgroup. However, among male participants, no significant link emerged between VOCM mixtures and CKD or eGFR. Furthermore, in both the overall and female participant groups, there was an absence of a significant correlation between VOCM mixtures and either ACR or albuminuria. On the other hand, in male participants, while no significant correlation was detected with albuminuria, a significant positive correlation was observed with ACR. Pollutant analysis identified potential links between kidney damage and 1,3-butadiene, toluene, ethylbenzene, styrene, xylene, acrolein, crotonaldehyde and propylene oxide. Mediation analyses suggested that BA might partially mediate the relationship between VOCM mixtures and kidney damage.

CONCLUSION

The current findings highlight the widespread exposure to VOCs among the general U.S. adult population and indicate a potential correlation between exposure to VOC mixtures and compromised renal function parameters, with notable gender disparities. Females appear to exhibit greater sensitivity to impaired renal function resulting from VOCs exposure. Anti-aging treatments may offer some mitigation against kidney damage due to VOCs exposure.

Primary cilia as a targetable node between biliary injury, senescence and regeneration in liver transplantation

BACKGROUND & AIMS

Biliary complications are a major cause of morbidity and mortality in liver transplantation. Up to 25% of patients that develop biliary complications require additional surgical procedures, re-transplantation or die in the absence of a suitable regraft. Here, we investigate the role of the primary cilium, a highly specialised sensory organelle, in biliary injury leading to post-transplant biliary complications.

METHODS

Human biopsies were used to study the structure and function of primary cilia in liver transplant recipients that develop biliary complications (n = 7) in comparison with recipients without biliary complications (n = 12). To study the biological effects of the primary cilia during transplantation, we generated murine models that recapitulate liver procurement and cold storage, and assessed the elimination of the primary cilia in biliary epithelial cells in the K19CreERTKif3afl/fl mouse model. To explore the molecular mechanisms responsible for the observed phenotypes we used in vitro models of ischemia, cellular senescence and primary cilia ablation. Finally, we used pharmacological and genetic approaches to target cellular senescence and the primary cilia, both in mouse models and discarded human donor livers.

RESULTS

Prolonged ischemic periods before transplantation result in ciliary shortening and cellular senescence, an irreversible cell cycle arrest that blocks regeneration. Our results indicate that primary cilia damage results in biliary injury and a loss of regenerative potential. Senescence negatively impacts primary cilia structure and triggers a negative feedback loop that further impairs regeneration. Finally, we explore how targeted interventions for cellular senescence and/or the stabilisation of the primary cilia improve biliary regeneration following ischemic injury.

CONCLUSIONS

Primary cilia play an essential role in biliary regeneration and we demonstrate that senolytics and cilia-stabilising treatments provide a potential therapeutic opportunity to reduce the rate of biliary complications and improve clinical outcomes in liver transplantation.

IMPACT AND IMPLICATIONS

Up to 25% of liver transplants result in biliary complications, leading to additional surgery, retransplants, or death. We found that the incidence of biliary complications is increased by damage to the primary cilium, an antenna that protrudes from the cell and is key to regeneration. Here, we show that treatments that preserve the primary cilia during the transplant process provide a potential solution to reduce the rates of biliary complications.

Aging and Autophagy: Roles in Musculoskeletal System Injury

Aging is a multifactorial process that ultimately leads to a decline in physiological function and a consequent reduction in the health span, and quality of life in elderly population. In musculoskeletal diseases, aging is often associated with a gradual loss of skeletal muscle mass and strength, resulting in reduced functional capacity and an increased risk of chronic metabolic diseases, leading to impaired function and increased mortality. Autophagy is a highly conserved physiological process by which cells, under the regulation of autophagy-related genes, degrade their own organelles and large molecules by lysosomal degradation. This process is unique to eukaryotic cells and is a strict regulator of homeostasis, the maintenance of energy and substance balance. Autophagy plays an important role in a wide range of physiological and pathological processes such as cell homeostasis, aging, immunity, tumorigenesis and neurodegenerative diseases. On the one hand, under mild stress conditions, autophagy mediates the restoration of homeostasis and proliferation, reduction of the rate of aging and delay of the aging process. On the other hand, under more intense stress conditions, an inadequate suppression of autophagy can lead to cellular aging. Conversely, autophagy activity decreases during aging. Due to the interrelationship between aging and autophagy, limited literature exists on this topic. Therefore, the objective of this review is to summarize the current concepts on aging and autophagy in the musculoskeletal system. The aim is to better understand the mechanisms of age-related changes in bone, joint and muscle, as well as the interaction relationship between autophagy and aging. Its goal is to provide a comprehensive perspective for the improvement of diseases of the musculoskeletal system.

Cellular Aging and Senescence in Cancer: A Holistic Review of Cellular Fate Determinants

This comprehensive review navigates the complex relationship between cellular aging, senescence, and cancer, unraveling the determinants of cellular fate. Beginning with an overview of cellular aging's significance in cancer, the review explores processes, changes, and molecular pathways influencing senescence. The review explores senescence as a dual mechanism in cancer, acting as a suppressor and contributor, focusing on its impact on therapy response. This review highlights opportunities for cancer therapies that target cellular senescence. The review further examines the senescence-associated secretory phenotype and strategies to modulate cellular aging to influence tumor behavior. Additionally, the review highlights the mechanisms of senescence escape in aging and cancer cells, emphasizing their impact on cancer prognosis and resistance to therapy. The article addresses current advances, unexplored aspects, and future perspectives in understanding cellular aging and senescence in cancer.

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.

In the land of not-unhappiness: On the state-of-the-art of targeting aging and age-related diseases by biomedical research

The concept of the Land of Not-Unhappiness refers to the potential achievement of eliminating the pathologies of the aging process. To inform of how close we are to settling in the land, we summarize and review the achievements of research on anti-aging interventions over the last hundred years with a specific focus on strategies that slow down metabolism, compensate for aging-related losses, and target a broad range of age-related diseases. We critically evaluate the existing interventions labeled as "anti-aging," such as calorie restriction, exercise, stem cell administration, and senolytics, to provide a down-to-earth evaluation of their current applicability in counteracting aging. Throughout the text, we have maintained a light tone to make it accessible to non-experts in biogerontology, and provide a broad overview for those considering conducting studies, research, or seeking to understand the scientific basis of anti-aging medicine.

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.

The Impact of Senescent Cells on Limb Regeneration

Cellular senescence is a state in which cells enter cell cycle arrest. However, senescent cells have the ability to secrete signaling molecules such as chemokines, cytokines, and growth factors. This secretory activity is an important feature of senescent cells, since the secreted factors impact the surrounding cellular microenvironment. Indeed, senescent cells and their secretome play a crucial role during limb development. However, whether the process of limb regeneration also relies on senescent cells remains unclear. Creation of a novel targeted depletion strategy that can eliminate senescent cells in the regenerating limb has now demonstrated an important role for senescent cells in limb regeneration. This role is linked to senescent cell-derived Wnt signaling. These findings reveal a previously unknown role for senescent cells during limb regeneration through Wnt signaling.

Cellular senescence in lung cancer: Molecular mechanisms and therapeutic interventions

Lung cancer stands as the primary contributor to cancer-related fatalities worldwide, affecting both genders. Two primary types exist where non-small cell lung cancer (NSCLC), accounts for 80-85% and SCLC accounts for 10-15% of cases. NSCLC subtypes include adenocarcinoma, squamous cell carcinoma, and large cell carcinoma. Smoking, second-hand smoke, radon gas, asbestos, and other pollutants, genetic predisposition, and COPD are lung cancer risk factors. On the other hand, stresses such as DNA damage, telomere shortening, and oncogene activation cause a prolonged cell cycle halt, known as senescence. Despite its initial role as a tumor-suppressing mechanism that slows cell growth, excessive or improper control of this process can cause age-related diseases, including cancer. Cellular senescence has two purposes in lung cancer. Researchers report that senescence slows tumor growth by constraining multiplication of impaired cells. However, senescent cells also demonstrate the pro-inflammatory senescence-associated secretory phenotype (SASP), which is widely reported to promote cancer. This review will look at the role of cellular senescence in lung cancer, describe its diagnostic markers, ask about current treatments to control it, look at case studies and clinical trials that show how senescence-targeting therapies can be used in lung cancer, and talk about problems currently being faced, and possible solutions for the same in the future.

Double-blind, vehicle-controlled clinical investigation of peptide OS-01 for skin rejuvenation

INTRODUCTION

Senescent cells contribute to age-related tissue deterioration, including the skin, which plays important roles in overall health and social interactions. This study aimed to assess the effects of the senotherapeutic peptide, OS-01 (a.k.a. Pep 14), on skin.

METHODS

A 12-week split-face, double-blinded, vehicle-controlled study involving 22 participants was conducted. The OS-01-containing formulation was applied to one side of the face, while the other side received an identical control formulation lacking the peptide. Skin characteristics were assessed using instrumental measurements, expert clinical grading, and subjective questionnaires.

RESULTS

Results showed that the OS-01 formulation significantly improved one aspect of skin barrier function, as evidenced by reduced trans-epidermal water loss compared to both baseline and vehicle control. Expert grading and Antera 3D image analysis revealed a reduction in wrinkle appearance and indentation in the periorbital area, and improved skin texture and radiance on both sides of the face, with the OS-01-containing formulation demonstrating superior results. Participants also perceived improvements in skin hydration, smoothness, radiance, and overall appearance.

CONCLUSION

The findings suggest that the OS-01 formulation promotes skin health by strengthening the skin barrier, protecting against dehydration, reducing the appearance of wrinkles, and improving skin texture and radiance. These effects are likely attributed to the senotherapeutic properties of OS-01 in reducing cellular senescence and its associated detrimental effects.

Tissue fibroblasts are versatile immune regulators: An evaluation of their impact on the aging process

Fibroblasts are abundant stromal cells which not only control the integrity of extracellular matrix (ECM) but also act as immune regulators. It is known that the structural cells within tissues can establish an organ-specific immunity expressing many immune-related genes and closely interact with immune cells. In fact, fibroblasts can modify their immune properties to display both pro-inflammatory and immunosuppressive activities in a context-dependent manner. After acute insults, fibroblasts promote tissue inflammation although they concurrently recruit immunosuppressive cells to enhance the resolution of inflammation. In chronic pathological states, tissue fibroblasts, especially senescent fibroblasts, can display many pro-inflammatory and immunosuppressive properties and stimulate the activities of different immunosuppressive cells. In return, immunosuppressive cells, such as M2 macrophages and myeloid-derived suppressor cells (MDSC), evoke an excessive conversion of fibroblasts into myofibroblasts, thus aggravating the severity of tissue fibrosis. Single-cell transcriptome studies on fibroblasts isolated from aged tissues have confirmed that tissue fibroblasts express many genes coding for cytokines, chemokines, and complement factors, whereas they lose some fibrogenic properties. The versatile immune properties of fibroblasts and their close cooperation with immune cells indicate that tissue fibroblasts have a crucial role in the aging process and age-related diseases.

Targeting cellular senescence as a therapeutic vulnerability in gastric cancer

AIMS

Cellular senescence (CS) represents an intracellular defense mechanism responding to stress signals and can be leveraged as a "vulnerability" in cancer treatment. This study aims to construct a CS atlas for gastric cancer (GC) and uncover potential therapeutics for GC patients.

MATERIALS AND METHODS

38 senescence-associated regulators with prognostic significance in GC were obtained from the CellAge database to construct Gastric cancer-specific Senescence Score (GSS). Using eXtreme Sum algorism, GSS-based drug repositioning was conducted to identify drugs that could antagonize GSS in CMap database. In vitro experiments were conducted to test the effect of combination of palbociclib and exisulind in eliminating GC cells.

KEY FINDINGS

Patients with high GSS exhibited CS-related features, such as CS markers upregulation, adverse clinical outcomes and hypomethylation status. scRNA-seq data showed malignant cells with high GSS exhibited enhanced senescence state and more immunosuppressive signals such as PVR-CD96 compared with malignant cells with low GSS. In addition, the GSS-High cancer associated fibroblasts might secrete cytokines and chemokines such as IL-6, CXCL1, CXCL12, and CCL2 to from an immunosuppressive microenvironment, and GSS could serve as an indicator for immunotherapy resistance. Exisulind exhibited the greatest potential to reverse GSS. In vitro experiments demonstrated that exisulind could induce apoptosis and suppress the proliferation of palbociclib-induced senescent GC cells.

SIGNIFICANCE

Overall, GSS offers a framework for better understanding of correlation between senescence and GC, which might provide new insights into the development of novel therapeutics in GC.

Ageing microenvironment mediates lymphocyte carcinogenesis and lymphoma drug resistance: From mechanisms to clinical therapy (Review)

Cellular senescence has a complex role in lymphocyte carcinogenesis and drug resistance of lymphomas. Senescent lymphoma cells combine with immunocytes to create an ageing environment that can be reprogrammed with a senescence‑associated secretory phenotype, which gradually promotes therapeutic resistance. Certain signalling pathways, such as the NF‑κB, Wnt and PI3K/AKT/mTOR pathways, regulate the tumour ageing microenvironment and induce the proliferation and progression of lymphoma cells. Therefore, targeting senescence‑related enzymes or their signal transduction pathways may overcome radiotherapy or chemotherapy resistance and enhance the efficacy of relapsed/refractory lymphoma treatments. Mechanisms underlying drug resistance in lymphomas are complex. The ageing microenvironment is a novel factor that contributes to drug resistance in lymphomas. In terms of clinical translation, some senolytics have been used in clinical trials on patients with relapsed or refractory lymphoma. Combining immunotherapy with epigenetic drugs may achieve better therapeutic effects; however, senescent cells exhibit considerable heterogeneity and lymphoma has several subtypes. Extensive research is necessary to achieve the practical application of senolytics in relapsed or refractory lymphomas. This review summarises the mechanisms of senescence‑associated drug resistance in lymphoma, as well as emerging strategies using senolytics, to overcome therapeutic resistance in lymphoma.