p21 produces a bioactive secretome that places stressed cells under immunosurveillance

Exosomal dynamics: Bridging the gap between cellular senescence and cancer therapy

Cancer remains one of the most devastating diseases, severely affecting public health and contributing to economic instability. Researchers worldwide are dedicated to developing effective therapeutics to target cancer cells. One promising strategy involves inducing cellular senescence, a complex state in which cells exit the cell cycle. Senescence has profound effects on both physiological and pathological processes, influencing cellular systems through secreted factors that affect surrounding and distant cells. Among these factors are exosomes, small extracellular vesicles that play crucial roles in cellular communication, development, and defense, and can contribute to pathological conditions. Recently, there has been increasing interest in engineering exosomes as precise drug delivery vehicles, capable of targeting specific cells or intracellular components. Studies have emphasized the significant role of exosomes from senescent cells in cancer progression and therapy. Notably, chemotherapeutic agents can alter the tumor microenvironment, induce senescence, and trigger immune responses through exosome-mediated cargo transfer. This review explores the intricate relationship between cellular senescence, exosomes, and cancer, examining how different therapeutics can eliminate cancer cells or promote drug resistance. It also investigates the molecular mechanisms and signaling pathways driving these processes, highlighting current challenges and proposing future perspectives to uncover new therapeutic strategies for cancer treatment.

Advancing T-cell immunotherapy for cellular senescence and disease: Mechanisms, challenges, and clinical prospects

Cellular senescence is a complex biological process with a dual role in tissue homeostasis and aging-related pathologies. Accumulation of senescent cells promotes chronic inflammation, tissue dysfunction, age-related diseases, and tumor suppression. Recent advancements in immunotherapy have positioned T cell-based approaches as precision tools for the targeted clearance of senescent cells, offering a novel avenue for anti-aging interventions. This review explores the molecular mechanisms underlying cellular senescence, focusing on its immunogenic features and interactions with T cells, including T-cell activation, antigen recognition, modulation of tumor microenvironment (TME), and immune evasion strategies. Innovations such as chimeric antigen receptor (CAR)-T cells, immune checkpoint therapies, and SASP-neutralizing approaches are highlighted as breakthrough strategies for enhancing senescent cell eradication. The integration of multi-omics and artificial intelligence is further catalyzing the development of personalized therapies to amplify immune surveillance and tissue rejuvenation. Clinically, T cell-based interventions hold promise for mitigating age-related pathologies and extending healthspan, yet challenges remain in optimizing target specificity, countering immunosuppressive niches, and overcoming immune senescence in aging populations. This review synthesizes current advances and challenges, highlighting the potential of T cell immunotherapy as a cornerstone of anti-aging medicine and emphasizing the need for interdisciplinary innovation to translate preclinical findings into transformative therapies for aging and age-related diseases.

Glucosylated cholesterol accumulates in atherosclerotic lesions and impacts macrophage immune response

Atherosclerosis can be described as a local acquired lysosomal storage disorder (LSD), resulting from the build-up of undegraded material in lysosomes. Atherosclerotic foam cells accumulate cholesterol (Chol) and glycosphingolipids (GSLs) within lysosomes. This constitutes the ideal milieu for the formation of a side product of lysosomal storage: glucosylated cholesterol (GlcChol), previously found in several LSDs. Using LC-MS/MS, we demonstrated that GlcChol is abundant in atherosclerotic lesions. Patients suffering from cardiovascular diseases presented unaltered plasma GlcChol levels but slightly elevated GlcChol/Chol ratios. Furthermore, we mimicked GlcChol formation in vitro by exposing macrophages (Mφ) to a pro-atherogenic oxidized cholesteryl ester, an atherosclerosis foam cell model. Additionally, Mφ exposed to GlcChol exhibited an enlarged and multinucleated phenotype. These Mφ present signs of decreased proliferation and reduced pro-inflammatory capacity. Mechanistically the process seems to be associated with the activation of the AMPK signalling pathway and the cyclin-dependent kinase inhibitor 1 (CDKN1A/p21), in response to DNA damage inflicted by reactive oxygen species (ROS). At the organelle level, exposure to GlcChol impacted the lysosomal compartment, resulting in the activation of the mTOR signalling pathway and lysosomal biogenesis mediated by the transcription factor EB (TFEB). This suggests that high concentrations of GlcChol impact cellular homeostasis. In contrast, under this threshold GlcChol formation most likely represents a relatively innocuous compensatory mechanism to cope with Chol and GSL build-up within lesions. Our findings demonstrate that glycosidase-mediated lipid modifications may play a role in the aetiology of genetic and acquired LSDs, warranting further investigation.

A Critical Appraisal of the Utility of Targeting Therapy-Induced Senescence for Cancer Treatment

Cancer chemotherapy and radiotherapy are rarely successful in eliminating the entire tumor population, often leaving behind a subpopulation of senescent cells that can contribute to disease recurrence. These senescent tumor cells also secrete various chemokines and cytokines that may be tumor promoting and immunosuppressive. Recognition of the deleterious impact of therapy-induced senescence has led to the preclinical development of senolytic compounds that eliminate senescent cells, representing a potential strategy to enhance the efficacy of conventional and targeted anticancer therapy. However, it remains uncertain whether this strategy can or will be translated to the clinic. This review provides a summary of the recent preclinical literature supporting the use of senolytics as an adjunct for cancer treatment, discusses the limitations associated with their use in the current preclinical models, and provides perspectives on the clinical development of senolytics in cancer treatment regimens. Overall, preclinical studies support the potential of senolytics to enhance efficacy and prolong the antitumor activity of current standard-of-care cancer therapies that promote senescence. However, further work is needed to develop optimal senolytic agents with the appropriate combination of properties for clinical testing, specifically, activity in the context of therapy-induced senescence with acceptable tolerability.

Melatonin-mediated cGAS-STING signal in senescent macrophages promote TNBC chemotherapy resistance and drive the SASP

The build-up of senescent cells in tissues is a key indicator of aging, associated with negative prognosis and therapy resistance. Despite immune dysfunction related to aging, also known as immunosenescence, is recognized as a factor in this process, the exact mechanisms are still unclear. In this study, we reported that melatonin deficiency accelerated macrophage senescence in triple-negative breast cancer, whereas melatonin could defend macrophages against senescence through the Nfatc1-Trim26-cgas-Sting pathway. Mechanistically, melatonin enhanced the nuclear translocation of Nfatc1 and elevated Trim26 transcription levels. Trim26, functioning as an E3 ligase, ubiquitinates cgas, thereby inhibiting the activation of the cgas-Sing pathway and consequently preventing cell senescence. Conversely, melatonin deficiency induced cgas-Sting pathway activation to promote macrophage aging. Our results show that melatonin inhibited macrophage senescence and improved chemotherapy responsiveness, with further enhancement when combined with the cgas inhibitor (G150). Overall, our findings indicated that melatonin protects macrophages from immunosenescence, suggesting its therapeutic potential for enhancing chemotherapy response.

Saikosaponin A induces cellular senescence in triple-negative breast cancer by inhibiting the PI3K/Akt signalling pathway

Background

Breast cancer has now become the most prevalent cancer worldwide. Existing therapeutic agents are generally accompanied by significant side effects. Here, we highlight Saikosaponin A (SSA), a promising natural metabolite characterized by low toxicity, demonstrating significant efficacy against breast cancer through the induction of cellular senescence.

Methods

The antitumor property of SSA was determined via MTT colorimetric assay, 5-ethynyl-2'-deoxyuridine (EdU) incorporation assay, colony formation, and propidium iodide (PI) staining in vitro, as well as xenograft in vivo model. A network approach was used to predict potential targets of SSA reevant for a potential anti-tumor effect and verified through senescence-associated β-galactosidase (SA-β-gal), flow-cytometry analysis, RT-PCR, Western blotting, and immuno-histochemistry assay.

Results

SSA significantly suppressed proliferation and triggered cell cycle arrest of SUM159PT and MDA-MB-231 cells. Revealed by network analysis, cellular senescence, and phosphatidylinositol-3-kinase (PI3K)/Akt signaling pathway were implemented in the anti-tumor effects of SSA. SSA-stimulated senescence was associated with increased ROS production, distinct senescence-associated secretory phenotype (SASP), and restricted PI3K/Akt signaling, as well as p21 and p53 accumulation. Furthermore, SSA displayed inhibitory effects on tumor growth with minimal toxicity in animal studies, accompanied by activated biomarkers of cellular senescence and decreased expression of p-Akt and p-PI3K.

Conclusion

Taken together, based on the preliminary results of network analysis and further experimental validation, this study revealed that SSA significantly induced cell cycle arrest and senescence, and the inhibition of ROS-mediated PI3K/Akt pathway may be the potential mechanism in this process.

Advancements in immunotherapy for gastric cancer: Unveiling the potential of immune checkpoint inhibitors and emerging strategies

Gastric cancer (GC) is linked to high morbidity and mortality rates. Approximately two-thirds of GC patients are diagnosed at an advanced or metastatic stage. Conventional treatments for GC, including surgery, radiotherapy, and chemotherapy, offer limited prognostic improvement. Recently, immunotherapy has gained attention for its promising therapeutic effects in various tumors. Immunotherapy functions by activating and regulating the patient's immune cells to target and eliminate tumor cells, thereby reducing the tumor burden in the body. Among immunotherapies, immune checkpoint inhibitors (ICIs) are the most advanced. ICIs disrupt the inhibitory protein-small molecule (PD-L1, CTLA4, VISTA, TIM-3 and LAG3) interactions produced by immune cells, reactivating these cells to recognize and attack tumor cells. However, adverse reactions and resistance to ICIs hinder their further clinical and experimental development. Therefore, a comprehensive understanding of the advancements in ICIs for GC is crucial. This article discusses the latest developments in clinical trials of ICIs for GC and examines combination therapies involving ICIs (targeted therapy, chemotherapy, radiotherapy), alongside ongoing clinical trials. Additionally, the review investigates the tumor immune microenvironment and its role in non-responsiveness to ICIs, highlighting the function of tumor immune cells in ICI efficacy. Finally, the article explores the prospects and limitations of new immunotherapy-related technologies, such as tumor vaccines, nanotechnologies, and emerging therapeutic strategies, aiming to advance research into personalized and optimized immunotherapy for patients with locally advanced gastric cancer.

Cellular senescence offers distinct immunological vulnerabilities in cancer

Chronic damage following oncogene induction or cancer therapy can produce cellular senescence. Senescent cells not only exit the cell cycle but communicate damage signals to their environment that can trigger immune responses. Recent work has revealed that senescent tumor cells are highly immunogenic, leading to new ways to activate antitumor immunosurveillance and potentiate T cell-directed immunotherapies. However, other studies have determined that heterogeneous senescent stromal cell populations contribute to immunosuppression and tumor progression, sparking the development of senotherapeutics to target senescent cells that evade immune detection. We review current findings that provide deeper insights into the mechanisms contributing to the dichotomous role of senescence in immune modulation and how that can be leveraged for cancer immunotherapy.

Targeting TM4SF1 promotes tumor senescence enhancing CD8+ T cell cytotoxic function in hepatocellular carcinoma

BACKGROUND/AIMS

Transmembrane 4 L six family member 1 (TM4SF1) is highly expressed and contributes to the progression of various malignancies. However, how it modulates hepatocellular carcinoma (HCC) progression and senescence remains to be elucidated.

METHODS

TM4SF1 expression in HCC samples was evaluated using immunohistochemistry and flow cytometry. Cellular senescence was assessed through SA-β-gal activity assays and Western blot analysis. TM4SF1-related protein interactions were investigated using immunoprecipitation-mass spectrometry, co-immunoprecipitation, bimolecular fluorescence complementation, and immunofluorescence. Tumor-infiltrating immune cells were analyzed by flow cytometry. The HCC mouse model was established via hydrodynamic tail vein injection.

RESULTS

TM4SF1 was highly expressed in human HCC samples and murine models. Knockdown of TM4SF1 suppressed HCC proliferation both in vitro and in vivo, inducing non-secretory senescence through upregulation of p16 and p21. TM4SF1 enhanced the interaction between AKT1 and PDPK1, thereby promoting AKT phosphorylation, which subsequently downregulated p16 and p21. Meanwhile, TM4SF1-mediated AKT phosphorylation enhanced PD-L1 expression while reducing major histocompatibility complex class I level on tumor cells, leading to impaired cytotoxic function of CD8+ T cells and an increased proportion of exhausted CD8+ T cells. In clinical HCC samples, elevated TM4SF1 expression was associated with resistance to anti-PD-1 immunotherapy. Targeting TM4SF1 via adeno-associated virus induced tumor senescence, reduced tumor burden and synergistically enhanced the efficacy of anti-PD-1 therapy.

CONCLUSION

Our results revealed that TM4SF1 regulated tumor cell senescence and immune evasion through the AKT pathway, highlighting its potential as a therapeutic target in HCC, particularly in combination with first-line immunotherapy.

Causes and consequences of DNA double-stranded breaks in cardiovascular disease

The genome, whose stability is essential for survival, is incessantly exposed to internal and external stressors, which introduce an estimated 104 to 105 lesions, such as oxidation, in the nuclear genome of each mammalian cell each day. A delicate homeostatic balance between the generation and repair of DNA lesions maintains genomic stability. To initiate transcription, DNA strands unwind to form a transcription bubble and provide a template for the RNA polymerase II (RNAPII) complex to synthesize nascent RNA. The process generates DNA supercoils and introduces torsional stress. To enable RNAPII processing, the supercoils are released by topoisomerases by introducing strand breaks, including double-stranded breaks (DSBs). Thus, DSBs are intrinsic genomic features of gene expression. The breaks are quickly repaired upon processing of the transcription. DNA lesions and damaged proteins involved in transcription could impede the integrity and efficiency of RNAPII processing. The impediment, which is referred to as transcription stress, not only could lead to the generation of aberrant RNA species but also the accumulation of DSBs. The latter is particularly the case when topoisomerase processing and/or the repair mechanisms are compromised. The DSBs activate the DNA damage response (DDR) pathways to repair the damaged DNA and/or impose cell cycle arrest and cell death. In addition, the release of DSBs into the cytosol activates the cytosolic DNA-sensing proteins (CDSPs), which along with the nuclear DDR pathways induce the expression of senescence-associated secretory phenotype (SASP), cell cycle arrest, senescence, cell death, inflammation, and aging. The primary stimulus in hereditary cardiomyopathies is a mutation(s) in genes encoding the protein constituents of cardiac myocytes; however, the phenotype is the consequence of intertwined complex interactions among numerous stressors and the causal mutation(s). Increased internal DNA stressors, such as oxidation, alkylation, and cross-linking, are expected to be common in pathological conditions, including in hereditary cardiomyopathies. In addition, dysregulation of gene expression also imposes transcriptional stress and collectively with other stressors provokes the generation of DSBs. In addition, the depletion of nicotinamide adenine dinucleotide (NAD), which occurs in pathological conditions, impairs the repair mechanism and further facilitates the accumulation of DSBs. Because DSBs activate the DDR pathways, they are expected to contribute to the pathogenesis of cardiomyopathies. Thus, interventions to reduce the generation of DSBs, enhance their repair, and block the deleterious DDR pathways would be expected to impart salubrious effects not only in pathological states, as in hereditary cardiomyopathies but also aging.

Targeting senescent hepatocytes for treatment of metabolic dysfunction-associated steatotic liver disease and multi-organ dysfunction

Senescent hepatocytes accumulate in metabolic dysfunction-associated steatotic liver disease (MASLD) and are linked to worse clinical outcomes. However, their heterogeneity and lack of specific markers have made them difficult to target therapeutically. Here, we define a senescent hepatocyte gene signature (SHGS) using in vitro and in vivo models and show that it tracks with MASLD progression/regression across mouse models and large human cohorts. Single-nucleus RNA-sequencing and functional studies reveal that SHGS+ hepatocytes originate from p21+ cells, lose key liver functions and release factors that drive disease progression. One such factor, GDF15, increases in circulation alongside SHGS+ burden and disease progression. Through chemical screening, we identify senolytics that selectively eliminate SHGS+ hepatocytes and improve MASLD in male mice. Notably, SHGS enrichment also correlates with dysfunction in other organs. These findings establish SHGS+ hepatocytes as key drivers of MASLD and highlight a potential therapeutic strategy for targeting senescent cells in liver disease and beyond.

Age-dependent cytokine surge in blood precedes cancer diagnosis

Aging is associated with increased variability and dysregulation of the immune system. We performed a system-level analysis of serum cytokines in a longitudinal cohort of 133 healthy individuals over 9 y. We found that cancer incidence is a major contributor to increased cytokine abundance variability. Circulating cytokines increase up to 4 y before a cancer diagnosis in subjects with age over 80 y. We also analyzed cytokine expression in 10 types of early-stage cancers from The Cancer Genome Atlas. We found that a similar set of cytokines is upregulated in tumor tissues, specifically after the age of 80 y. Similarly, cellular senescence activity and CDKN1A/p21 expression increase with age in cancer tissues. Finally, we demonstrated that the cytokine levels in serum can be used to predict cancers among subjects age at 80+ y. Our results suggest that latent senescent cancers contribute to age-related chronic inflammation.

Pharmacological rescue of mutant p53 triggers spontaneous tumor regression via immune responses

Tumor suppressor p53 is the most frequently mutated protein in cancer, possessing untapped immune-modulating capabilities in anticancer treatment. Here, we investigate the efficacy and underlying mechanisms of pharmacological reactivation of mutant p53 in treating spontaneous tumors in mice. In the p53 R279W (equivalent to the human hotspot R282W) mouse model developing spontaneous tumors, arsenic trioxide (ATO) treatment through drinking water significantly prolongs the survival of mice, dependent on p53-R279W reactivation. Transient regressions of spontaneous T-lymphomas are observed in 70% of the ATO-treated mice, accompanied by interferon (IFN) response. In allograft models, the tumor-suppressive effect of reactivated p53-R279W is detectably reduced in both immunodeficient Rag1-/- and CD8+ T cell-depleted mice. ATO also activates the IFN pathway in human cancer cells harboring various p53 mutations, as well as in primary samples derived from the p53-mutant patient treated with ATO. Together, p53 could serve as an alternative therapeutic target for the development of immunotherapies.

p53 enhances DNA repair and suppresses cytoplasmic chromatin fragments and inflammation in senescent cells

Genomic instability and inflammation are distinct hallmarks of aging, but the connection between them is poorly understood. Here we report a mechanism directly linking genomic instability and inflammation in senescent cells through a mitochondria-regulated molecular circuit involving p53 and cytoplasmic chromatin fragments (CCF) that are enriched for DNA damage signaling marker γH2A.X. We show that p53 suppresses CCF accumulation and its downstream inflammatory phenotype. p53 activation suppresses CCF formation linked to enhanced DNA repair and genome integrity. Activation of p53 in aged mice by pharmacological inhibition of MDM2 reverses transcriptomic signatures of aging and age-associated accumulation of monocytes and macrophages in liver. Mitochondrial ablation in senescent cells suppresses CCF formation and activates p53 in an ATM-dependent manner, suggesting that mitochondria-dependent formation of γH2A.X + CCF dampens nuclear DNA damage signaling and p53 activity. These data provide evidence for a mitochondria-regulated p53 signaling circuit in senescent cells that controls DNA repair, genome integrity, and senescence- and age-associated inflammation, with relevance to therapeutic targeting of age-associated disease.

Functional diversity of senescent cells in driving ageing phenotypes and facilitating tissue regeneration

As the global population continues to age, understanding the complex role of cellular senescence and its implications in healthy lifespans has gained increasing prominence. Cellular senescence is defined as the irreversible cessation of cell proliferation, accompanied by the secretion of a range of pro-inflammatory factors, collectively termed the senescence-associated secretory phenotype (SASP), in response to various cellular stresses. While the accumulation of senescent cells has been strongly implicated in the ageing process and the pathogenesis of age-related diseases owing to their pro-inflammatory properties, recent research has also highlighted their essential roles in processes such as tumour suppression, tissue development and repair. This review provides a comprehensive examination of the dual nature of senescent cells, evaluating their deleterious contributions to chronic inflammation, tissue dysfunction and disease, as well as their beneficial roles in maintaining physiological homeostasis. Additionally, we explored the therapeutic potential of senolytic agents designed to selectively eliminate detrimental senescent cells while considering the delicate balance between transient and beneficial senescence and the persistence of pathological senescence. A deeper understanding of these dynamics is critical to develop novel interventions aimed at mitigating age-related dysfunctions and enhancing healthy life expectancies.

Proceedings of the National Cancer Institute Workshop on combining immunotherapy with radiotherapy: challenges and opportunities for clinical translation

Radiotherapy both promotes and antagonises tumour immune recognition. Some clinical studies show improved patient outcomes when immunotherapies are integrated with radiotherapy. Safe, greater than additive, clinical response to the combination is limited to a subset of patients, however, and how radiotherapy can best be combined with immunotherapies remains unclear. The National Cancer Institute-Immuno-Oncology Translational Network-Society for Immunotherapy of Cancer-American Association of Immunology Workshop on Combining Immunotherapy with Radiotherapy was convened to identify and prioritise opportunities and challenges for radiotherapy and immunotherapy combinations. Sessions examined the immune effects of radiation, barriers to anti-tumour immune response, previous clinical trial data, immunological and computational assessment of response, and next-generation radiotherapy-immunotherapy combinations. Panel recommendations included: developing and implementing patient selection and biomarker-guided approaches; applying mechanistic understanding to optimise delivery of radiotherapy and selection of immunotherapies; using rigorous preclinical models including companion animal studies; embracing data sharing and standardisation, advanced modelling, and multidisciplinary cross-institution collaboration; interrogating clinical data, including negative trials; and incorporating novel clinical endpoints and trial designs.

INDUCTION OF EARLY PULMONARY SENESCENCE IN EXPERIMENTAL SEPSIS

ABSTRACT

Background: Sepsis continues to pose a significant threat to human life and represents a substantial financial burden. In addition to replicative stress resulting from telomeric loss, recent studies have identified multiple factors contributing to cell cycle arrest. Furthermore, our understanding of pathways associated with cellular senescence, such as CD47-mediated suppression of efferocytosis, has expanded. However, beyond in vitro experiments, the impact of cell stress during complex systemic illnesses, including sepsis, remains poorly understood. Consequently, we conducted an investigation into molecular alterations related to senescence-associated pulmonary mechanisms during experimental nonpulmonary sepsis. Methods: Male C57BL/6JRj mice were anesthetized and subjected to either control conditions (sham) or cecal ligation and puncture (CLP) to induce sepsis. Twenty-four hours or 7 d after CLP, animals were killed, and blood, bronchoalveolar fluids, and lungs were harvested and analyzed for morphological and biochemical changes. Results: Histological damage in pulmonary tissue, as well as increases in plasma levels of surfactant protein D, indicated development of alveolar-focused acute lung injury after CLP. Additionally, we observed a significant upregulation of the CD47-QPCTL-SHP-1 axis in lungs of septic mice. Whereas the expression of p16, a marker primarily indicating manifested forms of senescence, was decreased after CLP, the early marker of cellular senescence, p21, was increased in the lungs during sepsis. Later, at 7 d after CLP, pulmonary expression of CD47 and QPCTL-1 was decreased, whereas SHP-1 was significantly enhanced. Conclusion: Our findings suggest an activation of senescent-associated pathways during experimental sepsis. However, expanding the experiments to other organ systems and in vivo long-term models are necessary to further evaluate the sustained mechanisms and immunopathophysiological consequences of cellular senescence triggered by septic organ injury.

FOXO4-DRI induces keloid senescent fibroblast apoptosis by promoting nuclear exclusion of upregulated p53-serine 15 phosphorylation

Keloids are pathological scars exhibiting tumour-like aggressiveness and high recurrence rate. Here we find increased proportion of pro-inflammatory and mesenchymal fibroblast subpopulations and senescent fibroblasts, and enhanced expression of senescence-associated secretory phenotype genes using single-cell RNA sequencing analysis, as well as elevated p16 protein and more β-galactosidase-positive cells in keloids. The up-regulated p53-serine15 phosphorylation (p53-pS15) in keloids is identified by phosphospecific protein microarray and western blotting. We further demonstrate that a senolytic FOXO4-D-retro-inverso-isoform peptide (FOXO4-DRI) promotes apoptosis and decreases G0/G1 phase cells in pro-senescence models of keloid organ cultures and fibroblasts, accompanied with p53-pS15 nuclear exclusion. Our study indicates that upregulation of p53-pS15 and p16 maintains a persistent senescent microenvironment to promote cell cycle arrest and apoptosis resistance in keloid fibroblasts. FOXO4-DRI shows potential as a treatment targeting the senescence and apoptosis resistance, and holds promise as an approach to prevent the aggressiveness and relapse of keloids.

An Integration of RNA Sequencing and Network Pharmacology Approaches Predicts the Molecular Mechanisms of the Huo-Xue-Shen Formula in the Treatment of Liver Fibrosis

Background: Liver fibrosis is a prevalent, chronic inflammatory condition characterized by the excessive accumulation of extracellular matrix components and, primarily, collagen in the liver. Huo-xue-shen (HXS) has proven effective for the treatment of liver fibrosis. However, the mechanism is yet to be deciphered. Methods: Network pharmacology, machine learning algorithms and RNA-seq were used to predict the immune-treated targets and mechanisms associated with HXS in liver fibrosis. Molecular docking was employed to screen for effective agents based on the drug-compound-hub gene network in HXS, aiming to identify the most critical bioactive compound in HXS for the treatment of liver fibrosis. Results: A total of 100 immune-treated targets (ITTs) of HXS were found to significantly regulate the PI3K-Akt signaling pathway and the MAPK signaling pathway. Among these, CDKN1A, NR1I3, and TUBB1, which can concurrently interact with quercetin, were associated with the prognosis of liver fibrosis, indicating that HXS may inhibit or reverse HSC activation primarily by suppressing neutrophil extracellular trap formation, stimulating oxidative phosphorylation and promoting thyroid hormone synthesis in the regulation of the liver microenvironment. Conclusions: Our study suggests that HXS may delay the progression of liver fibrosis by targeting multiple pathways, as shown by the network pharmacology and transcriptome profiling used to examine the liver immune environment. Quercetin, its key ingredient, likely plays an important role by mediating the CDKN1A, NR1I3, and TUBB1 signaling pathways. Overall, our findings provide a new perspective on the potential biological mechanisms of this traditional Chinese medicine formula.

IL-23R is a senescence-linked circulating and tissue biomarker of aging

Cellular senescence is an aging mechanism characterized by cell cycle arrest and a senescence-associated secretory phenotype (SASP). Preclinical studies demonstrate that senolytic drugs, which target survival pathways in senescent cells, can counteract age-associated conditions that span several organs. The comparative efficacy of distinct senolytic drugs for modifying aging and senescence biomarkers in vivo has not been demonstrated. Here, we established aging- and senescence-related plasma proteins and tissue transcripts that changed in old versus young female and male mice. We investigated responsivity to acute treatment with venetoclax, navitoclax, fisetin or luteolin versus transgenic senescent cell clearance in aged p16-InkAttac mice. We discovered that age-dependent changes in plasma proteins, including IL-23R, CCL5 and CA13, were reversed by senotherapeutics, which corresponded to expression differences in tissues, particularly in the kidney. In plasma from humans across the lifespan, IL-23R increased with age. Our results reveal circulating factors as candidate mediators of senescence-associated interorgan signal transduction and translationally impactful biomarkers of systemic senescent cell burden.

Immune therapeutic strategies for the senescent tumor microenvironment

Senescent cells can either to promote immunosuppressive tumor microenvironment or facilitate immune surveillance. Despite the revolutionary impact of cancer immunotherapy, durable responses in solid tumors, particularly in advanced stages, remain limited. Recent studies have shed light on the influence of senescent status within the tumor microenvironment (TME) on therapy resistance and major efforts are needed to overcome these challenges. This review summarizes recent advancements in targeting cellular senescence, with a particular focus on immunomodulatory approaches on the hallmarks of cellular senescence.

Mechanical Force-Induced cGAS Activation in Carcinoma Cells Facilitates Splenocytes into Liver to Drive Metastasis

Liver metastasis is the main cause of cancer-related mortality. During the metastasis process, circulating carcinoma cells hardly pass through narrow capillaries, leading to nuclear deformation. However, the effects of nuclear deformation and its underlying mechanisms on metastasis need further study. Here, it is shown that mechanical force-induced nuclear deformation exacerbates liver metastasis by activating the cGAS-STING pathway, which promotes splenocyte infiltration in the liver. Mechanical force results in nuclear deformation and rupture of the nuclear envelope with inevitable DNA leakage. Cytoplasmic DNA triggers the activation of cGAS-STING pathway, enhancing the production of IL6, TNFα, and CCL2. Additionally, splenocyte recruitment by the proinflammatory cytokines support carcinoma cell survival and colonization in the liver. Importantly, both intervening activity of cGAS and blocking of splenocyte migration to the liver efficiently ameliorate liver metastasis. Overall, these findings reveal a mechanism by which mechanical force-induced nuclear deformation exacerbates liver metastasis by regulating splenocyte infiltration into the liver and support targeting cGAS and blocking splenocyte recruitment as candidate therapeutic approaches for liver metastasis.

LIMA1 Is a Prognostic Senescence-Inhibitory Gene in Head and Neck Squamous Carcinoma

BACKGROUND

This study aimed to investigate potential cellular senescence inhibitory genes (CSIGs) and discover novel therapeutic targets in head and neck squamous cell carcinoma.

METHODS

Dysregulated CSIGs were identified based on The Cancer Genome Atlas (TCGA) and the Human Aging Genomic Resources (HAGR) database. Prognostic value and immune infiltration were assessed through bioinformatic analysis. Cell proliferation was evaluated using CCK-8, Edu assay, and colony formation assays in vitro. Western blotting and real-time PCR were used to evaluate LIMA1 expression. Clinical validation of LIMA1 expression was performed in our validated cohort.

RESULTS

In this study, differential analysis and functional enrichment analysis identified 26 differentially expressed senescence inhibitory genes. Among them, LIMA1 was found to be an independent prognostic marker and associated immune infiltration. Knockdown of LIMA1 inhibited HNSCC cell growth and increased the expression of senescence markers. Further experiments revealed that LIMA1 expression was partially regulated by the IL6/STAT3 signaling pathway. Immunohistochemistry further validated the clinical significance of LIMA1 expression and its association with IL6 and CD8+ T cells in our hospital's HNSCC tissues.

CONCLUSION

LIMA1 is a prognostic senescence-inhibitory gene in HNSCC. The IL6/STAT3/LIMA1 axis represents a novel molecular mechanism underlying cellular senescence resistance in HNSCC.

Cellular Senescence Contributes to Colonic Barrier Integrity Impairment Induced by Toxoplasma gondii Infection

Toxoplasma gondii (T. gondii) induces gut barrier integrity impairment, which is crucial to the establishment of long-term infection in hosts. Cellular senescence is an imperative event that drives disease progression. Several studies have indicated that T. gondii induces oxidative stress and cell cycle blockade in the tissues of hosts, suggesting cellular senescence induced by the parasite. Here, we explored whether cell senescence is involved in T. gondii-mediated colonic barrier integrity damage in mice. C57BL/6J mice were infected with 10 cysts of T. gondii. Senolytic therapy (dasatinib and quercetin, DQ, a combination therapy for reducing senescent cells) was given by oral gavage 4 weeks post-infection. Alcian blue staining, immunofluorescence, western blot, quantitative PCR (qPCR), and enzyme-linked immunosorbent assay (ELISA) were employed to evaluate the thickness of the colonic mucus layer, the expression profiles of genes and proteins related to tight junction function and cellular senescence in the colonic tissues, and the levels of serum lipopolysaccharides (LPS), respectively. T. gondii-infected mice exhibited deteriorated secreted mucus, shortened length, decreased expression of zonula occludens-1 (ZO-1) and occludin in the colon, accompanied by elevated levels of serum LPS. Moreover, the infection upregulated cell senescence-related markers (p16INK4A, p21CIP1) while inhibiting Lamin B1 expression. In addition, the expression levels of senescence-associated secretory phenotypes (SASPs), including IL-1β, TNF-α, IL-6, MMP9 and CXCL10, were upregulated post-infection. Notably, reducing cell senescence with DQ administration, significantly ameliorated the colonic pathological alterations induced by T. gondii infection. This study uncovers for the first time that cellular senescence contributes to the colonic barrier integrity damage induced by chronic T. gondii infection. Importantly, we provide evidence that senolytic therapy exerts a therapeutic effect on the intestinal pathological lesions.

Mapping epidermal and dermal cellular senescence in human skin aging

Single-cell RNA sequencing and spatial transcriptomics enable unprecedented insight into cellular and molecular pathways implicated in human skin aging and regeneration. Senescent cells are individual cells that are irreversibly cell cycle arrested and can accumulate across the human lifespan due to cell-intrinsic and -extrinsic stressors. With an atlas of single-cell RNA-sequencing and spatial transcriptomics, epidermal and dermal senescence and its effects were investigated, with a focus on melanocytes and fibroblasts. Photoaging due to ultraviolet light exposure was associated with higher burdens of senescent cells, a sign of biological aging, compared to chronological aging. A skin-specific cellular senescence gene set, termed SenSkin™, was curated and confirmed to be elevated in the context of photoaging, chronological aging, and non-replicating CDKN1A+ (p21) cells. In the epidermis, senescent melanocytes were associated with elevated melanin synthesis, suggesting haphazard pigmentation, while in the dermis, senescent reticular dermal fibroblasts were associated with decreased collagen and elastic fiber synthesis. Spatial analysis revealed the tendency for senescent cells to cluster, particularly in photoaged skin. This work proposes a strategy for characterizing age-related skin dysfunction through the lens of cellular senescence and suggests a role for senescent epidermal cells (i.e., melanocytes) and senescent dermal cells (i.e., reticular dermal fibroblasts) in age-related skin sequelae.

Lipid peroxidation products induce carbonyl stress, mitochondrial dysfunction, and cellular senescence in human and murine cells

Lipid enals are electrophilic products of lipid peroxidation that induce genotoxic and proteotoxic stress by covalent modification of DNA and proteins, respectively. As lipid enals accumulate to substantial amounts in visceral adipose during obesity and aging, we hypothesized that biogenic lipid enals may represent an endogenously generated, and therefore physiologically relevant, senescence inducers. To that end, we identified that 4-hydroxynonenal (4-HNE), 4-hydroxyhexenal (4-HHE) or 4-oxo-2-nonenal (4-ONE) initiate the cellular senescence program of IMR90 fibroblasts and murine adipose stem cells. In such cells, lipid enals induced accumulation of γH2AX foci, increased p53 signaling, enhanced expression of p21Cip1, and upregulated the expression and secretion of numerous cytokines, chemokines, and regulatory factors independently from NF-κB activation. Concomitantly, lipid enal treatment resulted in covalent modification of mitochondrial proteins, reduced mitochondrial spare respiratory capacity, altered nucleotide pools, and increased the phosphorylation of AMP kinase. Lipid-induced senescent cells upregulated BCL2L1 (Bcl-xL) and BCL2L2 (Bcl-w). and were resistant to apoptosis while pharmacologic inhibition of BAX/BAK macropores attenuated lipid-induced senescence. In situ, the 4-HNE scavenger L-carnosine ameliorated the development of the cellular senescence, while in visceral fat of obese C57BL/6J mice, L-carnosine reduced the abundance of 4-HNE-modified proteins and blunted the expression of senescence biomarkers CDKN1A (p21Cip1), PLAUR, BCL2L1, and BCL2L2. Taken together, the results suggest that lipid enals are endogenous regulators of cellular senescence and that biogenic lipid-induced senescence (BLIS) may represent a mechanistic link between oxidative stress and age-dependent pathologies.

The crosstalk between senescence, tumor, and immunity: molecular mechanism and therapeutic opportunities

Cellular senescence is characterized by a stable cell cycle arrest and a hypersecretory, proinflammatory phenotype in response to various stress stimuli. Traditionally, this state has been viewed as a tumor-suppressing mechanism that prevents the proliferation of damaged cells while activating the immune response for their clearance. However, senescence is increasingly recognized as a contributing factor to tumor progression. This dual role necessitates a careful evaluation of the beneficial and detrimental aspects of senescence within the tumor microenvironment (TME). Specifically, senescent cells display a unique senescence-associated secretory phenotype that releases a diverse array of soluble factors affecting the TME. Furthermore, the impact of senescence on tumor-immune interaction is complex and often underappreciated. Senescent immune cells create an immunosuppressive TME favoring tumor progression. In contrast, senescent tumor cells could promote a transition from immune evasion to clearance. Given these intricate dynamics, therapies targeting senescence hold promise for advancing antitumor strategies. This review aims to summarize the dual effects of senescence on tumor progression, explore its influence on tumor-immune interactions, and discuss potential therapeutic strategies, alongside challenges and future directions. Understanding how senescence regulates antitumor immunity, along with new therapeutic interventions, is essential for managing tumor cell senescence and remodeling the immune microenvironment.

Senescence landscape in the liver following sepsis and senolytics as potential therapeutics

Senescence, caused by cell-cycle arrest, is a hallmark of aging. Senescence has also been described in embryogenesis, wound healing, and acute injuries. Sepsis is characterized by a dysregulated host response to infection, leading to organ dysfunction and mortality. Most of the pathophysiology of human sepsis is recapitulated in the mouse model of polymicrobial sepsis, developed by cecal ligation and puncture (CLP). In this report, we demonstrate a rapid onset of cellular senescence in the liver of mice subjected to CLP-induced sepsis, characterized by the upregulation of p21, p53, and other senescence markers, including SA-βgal. Using RNAscope, confocal microscopy, and flow cytometry, we further confirm the emergence of p21-expressing senescence phenotype in the liver 24 h after sepsis induction. Senescence was observed in several cell types in the liver, including hepatocytes, endothelial cells, and macrophages. We determined the landscape of senescence phenotype in murine sepsis by single-cell sequencing, which further ascertained that this cell fate is not confined to any particular cell type but displays a heterogeneous distribution. Furthermore, we observed a significant reduction in mortality following sepsis when mice were treated with senolytics, a combination of dasatinib and quercetin, before the CLP surgery. Our experiments unequivocally demonstrated a rapid development of cellular senescence with sepsis and, for the first time, described the senescence landscape in the sepsis liver and the possible role of senescent cells in the worsening outcome following sepsis.

The Emerging Role of p21 in Diabetes and Related Metabolic Disorders

In the context of cell cycle inhibition, anti-proliferation, and the dysregulation observed in certain cancer pathologies, the protein p21 assumes a pivotal role. p21 links DNA damage responses to cellular processes such as apoptosis, senescence, and cell cycle arrest, primarily functioning as a regulator of the cell cycle. However, accumulating empirical evidence suggests that p21 is both directly and indirectly linked to a number of different metabolic processes. Intriguingly, recent investigations indicate that p21 significantly contributes to the pathogenesis of diabetes. In this review, we present a comprehensive evaluation of the scientific literature regarding the involvement of p21 in metabolic processes, diabetes etiology, pancreatic function, glucose homeostasis, and insulin resistance. Furthermore, we provide an encapsulated overview of therapies that target p21 to alleviate metabolic disorders. A deeper understanding of the complex interrelationship between p21 and diabetes holds promise for informing current and future therapeutic strategies to address this rapidly escalating health crisis.

Siwu decoction mitigates radiation-induced immune senescence by attenuating hematopoietic damage

BACKGROUND

To investigate the long term effects of ionizing radiation (IR) on hematopoietic stem/progenitor cells (HSPCs), immune tissues and cells, and the effects of Siwu decoction (SWD) on immune senescence mice.

METHODS

C57BL/6 J mice were exposed to 6.0 Gy 60Co γ irradiation. After 8-weeks of IR, SWD (5, 10, 20 g/kg/d) was administered for 30 days. The changes of HSPCs in bone marrow (BM) and T, B type lymphocyte and natural killer (NK) cells in spleen were detected by flow cytometry. The changes of peripheral blood cells were also examined. Hematoxylin-eosin staining were used to detect the pathological lesions of hippocampus, spleen and thymus tissues. Absolute mouse telomere length quantification qPCR assay kit was used to measure the telomere length of BM cells. The expression of factors associated with inflammation and aging such as p16, β-galactosidase in spleen, thymus and BM was determined.

RESULTS

Administration of SWD could increase the proportion of LSK (Lin-, Sca-1 + , c-Kit-), multipotent progenitor cells and multipotent progenitor cells and decrease the proportion of common myeloid progenitors and granulocyte-macrophage progenitors in BM. The proportion of B cells and NK cells in spleen and the content of white blood cells, red blood cells, hemoglobin, lymphocytes and eosinophils in peripheral blood were increased, at the same time, the proportion of neutrophils and monocytes was reduced by SWD. The pathological lesions of hippocampus, spleen and thymus were improved. The expression of p16 and β-galactosidase in spleen, thymus and BM was reduced and shortening of the telomere of BM cells was inhibited after administration. In addition, SWD could reduce the content of Janus activated kinase (JAK) 1, JAK2 and signal transducer and activator of transcription 3 (STAT3) in BM and spleen.

CONCLUSIONS

SWD could slow down IR-induced immune senescence by improving hematopoietic and immunologic injury. SWD might reduce the inflammation level of BM hematopoietic microenvironment by acting on JAK/STAT signaling pathway, while the immune damage of mice was improved by affecting the differentiation of HSPCs. The remission of hematopoietic and immunologic senescence was further demonstrated at the overall level.

Cross-talk of inflammation and cellular senescence: a new insight into the occurrence and progression of osteoarthritis

Osteoarthritis (OA) poses a significant challenge in orthopedics. Inflammatory pathways are regarded as central mechanisms in the onset and progression of OA. Growing evidence suggests that senescence acts as a mediator in inflammation-induced OA. Given the lack of effective treatments for OA, there is an urgent need for a clearer understanding of its pathogenesis. In this review, we systematically summarize the cross-talk between cellular senescence and inflammation in OA. We begin by focusing on the mechanisms and hallmarks of cellular senescence, summarizing evidence that supports the relationship between cellular senescence and inflammation. We then discuss the mechanisms of interaction between cellular senescence and inflammation, including senescence-associated secretory phenotypes (SASP) and the effects of pro- and anti-inflammatory interventions on cellular senescence. Additionally, we focus on various types of cellular senescence in OA, including senescence in cartilage, subchondral bone, synovium, infrapatellar fat pad, stem cells, and immune cells, elucidating their mechanisms and impacts on OA. Finally, we highlight the potential of therapies targeting senescent cells in OA as a strategy for promoting cartilage regeneration.

Genetic origins, regulators, and biomarkers of cellular senescence

This review comprehensively examines the molecular biology and genetic origins of cellular senescence. We focus on various cellular stressors and pathways leading to senescence, including recent advances in the understanding of the genetic influences driving senescence, such as telomere attrition, chemotherapy-induced DNA damage, pathogens, oncogene activation, and cellular and metabolic stress. This review also highlights the complex interplay of various signaling and metabolic pathways involved in cellular senescence and provides insights into potential therapeutic targets for aging-related diseases. Furthermore, this review outlines future research directions to deepen our understanding of senescence biology and develop effective interventions targeting senescent cells (SnCs).

The senescence-associated secretory phenotype and its physiological and pathological implications

Cellular senescence is a state of terminal growth arrest associated with the upregulation of different cell cycle inhibitors, mainly p16 and p21, structural and metabolic alterations, chronic DNA damage responses, and a hypersecretory state known as the senescence-associated secretory phenotype (SASP). The SASP is the major mediator of the paracrine effects of senescent cells in their tissue microenvironment and of various local and systemic biological functions. In this Review, we discuss the composition, dynamics and heterogeneity of the SASP as well as the mechanisms underlying its induction and regulation. We describe the various biological properties of the SASP, its beneficial and detrimental effects in different physiological and pathological settings, and its impact on overall health span. Finally, we discuss the use of the SASP as a biomarker and of SASP inhibitors as senomorphic interventions to treat cancer and other age-related conditions.

Differential Effects of Biomimetic Thymine Dimers and Corresponding Photo-Adducts in Primary Human Keratinocytes and Fibroblasts

UVB radiation induces DNA damage generating several thymine photo-adducts (TDPs), which can lead to mutations and cellular transformation. The DNA repair pathways preserve genomic stability by recognizing and removing photodamage. These DNA repair side products may affect cellular processes. We previously synthesized novel thymine biomimetic thymine dimers (BTDs) bearing different alkane spacers between nucleobases. Thus, the present study investigates whether novel BTDs and their TDPs can modulate DNA damage safeguard pathways of primary keratinocytes and fibroblasts using 2D and 3D models. We found that the p53/p21waf1 pathway is activated by BTDs and TDPs in primary cells similar to UVB exposure. Compound 1b can also induce the p53/p21waf1 pathway in a 3D skin model. However, BTDs and TDPs exhibit distinct effects on cell survival. They have a protective action in keratinocytes, which maintain their clonogenic ability following treatments. Conversely, compounds induce pro-apoptotic pathways in fibroblasts that exhibit reduced clonogenicity. Moreover, compounds induce inflammatory cytokines mainly in keratinocytes rather than fibroblasts. Matrix metalloproteinase 1 is up-regulated in both cell types after treatments. Therefore, BTDs and TDPs can act in the short term as safeguard mechanisms helping DNA damage response. Furthermore, they have distinct biological effects depending on photodamage form and cell type.

miR-3606-3p alleviates skin fibrosis by integratively suppressing the integrin/FAK, p-AKT/p-ERK, and TGF-β signaling cascades

INTRODUCTION

Fibroblast abnormalities are crucial causes of skin fibrosis, including systemic sclerosis (SSc) and keloids. However, their mechanisms, including underlying microRNA regulatory mechanisms, remain elusive.

OBJECTIVES

This study aimed to evaluate the roles, mechanisms, and therapeutic potential of miR-3606-3p in regulating multiple fibroblast abnormalities.

METHODS

The miR-3606-3p levels were evaluated in skin tissues and primary fibroblasts. RNA-seq and luciferase assays were employed to identify miR-3606-3p targets. Collagen contraction, western blotting, in vivo imaging, and real-time cellular analysis were used to assess fibroblast abnormalities. The therapeutic potential of miR-3606-3p was evaluated in mice.

RESULTS

MiR-3606-3p decreased in skin tissues (SSc: Fold Change (FC) =  - 2.95, P = 0.0101; keloid: FC =  - 3.42, P < 0.0001) and primary fibroblasts (SSc: FC =  - 12.74, P = 0.0278; keloid: FC =  - 2.08, P = 0.0021) from skin fibrosis patients, and negatively correlated with disease severity. Mechanistically, miR-3606-3p targeted the 3'-untranslated regions (3'-UTRs) of Integrin αV (ITGAV), GRB2-associated binding protein 1 (GAB1), and transforming growth factor beta receptor 2 (TGFBR2), all of these three targets increased in skin fibrosis. Simultaneously, miR-3606-3p inhibited fibroblast's fibrogenesis, migration, inflammation, and proliferation by inhibiting ITGAV/integrin/FAK, GAB1/p-AKT/p-ERK, and TGFBR2/p-SMAD2/3 signaling. ITGAV-mediated integrin/FAK signaling unidirectionally activated the p-AKT/p-ERK and p-SMAD2/3 pathways. Knockdown of GAB1 and TGFRB2 reduced ITGAV-induced p-AKT/p-ERK and p-SMAD2/3 activities. MiR-3606-3p, si-ITGAV, si-GAB1, and si-TGFBR2 exhibited significant inhibition of fibrogenesis and migration. Inflammation was primarily inhibited by si-ITGAV and si-GAB1, while proliferation was primarily inhibited by si-TGFBR2. Moreover, miR-3606-3p significantly attenuates skin fibrosis in keloid-bearing mice.

CONCLUSIONS

MiR-3606-3p is downregulated in skin fibrosis. Moreover, it negatively correlates with disease severity. Functionally, miR-3606-3p inhibits fibrogenesis, migration, inflammation, and proliferation of fibroblasts. Mechanistically, miR-3606-3p inhibits ITGAV, GAB1, and TGFBR2 by targeting their 3'-UTRs. ITGAV-, GAB1-, and TGFBR2-activated integrin/AKT/ERK/SMAD2/3 signaling induced fibroblast abnormalities. In vivo, miR-3606-3p inhibits skin fibrosis in mice. Therefore, the multi-targeting, multi-phenotypic regulatory properties of miR-3606-3p suggest its potential utility in clinical treatment.

A p21 reporter iPSC line for evaluating CRISPR-Cas9 and vector-induced stress responses

CRISPR-Cas9 editing triggers activation of the TP53-p21 pathway, but the impacts of different editing components and delivery methods have not been fully explored. In this study, we introduce a p21-mNeonGreen reporter iPSC line to monitor TP53-p21 pathway activation. This reporter enables dynamic tracking of p21 expression via flow cytometry, revealing a strong correlation between p21 expression and indel frequencies, and highlighting its utility in guide RNA screening. Our findings show that p21 activation is significantly more pronounced with double-stranded oligodeoxynucleotides (ODNs) or adeno-associated viral vectors (AAVs) compared to their single-stranded counterparts. Lentiviral vectors (LVs) and integrase-defective lentiviral vectors induce notably lower p21 expression than AAVs, suggesting their suitability for gene therapy in sensitive cells such as hematopoietic stem cells or immune cells. Additionally, specific viral promoters like SFFV significantly amplify p21 activation, emphasizing the critical role of promoter selection in vector development. Thus, the p21-mNeonGreen reporter iPSC line is a valuable tool for assessing the potential adverse effects of gene editing methodologies and vectors. Highlights Established a p21-mNeonGreen reporter iPSC line to track activation of the TP53-p21 pathway. Found a direct correlation between p21-mNeonGreen expression and indel frequencies, aiding in gRNA screening. Showed that LVs are preferable over AAVs for certain cells due to lower p21 activation, with viral promoter choice impacting p21 response.

p21 regulates expression of ECM components and promotes pulmonary fibrosis via CDK4 and Rb

Fibrosis and accumulation of senescent cells are common tissue changes associated with aging. Here, we show that the CDK inhibitor p21 (CDKN1A), known to regulate the cell cycle and the viability of senescent cells, also controls the expression of extracellular matrix (ECM) components in senescent and proliferating cells of the fibrotic lung, in a manner dependent on CDK4 and Rb phosphorylation. p21 knockout protects mice from the induction of lung fibrosis. Moreover, inducible p21 silencing during fibrosis development alleviates disease pathology, decreasing the inflammatory response and ECM accumulation in the lung, and reducing the amount of senescent cells. Furthermore, p21 silencing limits fibrosis progression even when introduced during disease development. These findings show that one common mechanism regulates both cell cycle progression and expression of ECM components, and suggest that targeting p21 might be a new approach for treating age-related fibrotic pathologies.

Convergent evolution of senescent fibroblasts in fibrosis and cancer with aging

Aging is associated with stereotyped changes in the tissue microenvironment that increase susceptibility to diseases of the elderly, including organ fibrosis and cancer. From a tissue perspective, fibrosis and cancer can both be viewed as non-healing wounds with pathogenic activation of tissue repair pathways in the stroma. If fibrosis and cancer represent an example of the convergent evolution of maladaptive stromal responses in distinct pathologies, what are the analogous cell types that might emerge in both diseases that share similarities in identity and function? In this review, we explore how senescent fibroblasts form a nexus that connects the aging organ with both fibrosis and cancer. The advent of single cell sequencing, coupled with improved detection of cell types with senescent traits in vivo, have allowed us to identify senescent fibroblasts with similar identities in both fibrosis and cancer that share pro-fibrotic programs. In addition to their ability to reorganize the extracellular matrix in diseased states, these pro-fibrotic senescent fibroblasts can also promote epithelial reprogramming and immune rewiring, which drive disease progression in fibrosis and cancer. Finally, the identification of common pathogenic cell types in fibrosis and cancer also presents a therapeutic opportunity to target both diseases with a shared approach.

Cellular senescence, p21, and the path to fibrosis

A recent study shows that p21 (CDKN1A) regulates expression of extracellular matrix components by senescent cells, promoting tissue fibrosis and immune cell infiltration.

Qizhu anticancer prescription enhances immunosurveillance of liver cancer cells by regulating p21-dependent secretory phenotypes

ETHNOPHARMACOLOGICAL RELEVANCE

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide, largely due to the limitations of available therapeutic strategies. The traditional Chinese medicine Qizhu Anticancer Prescription (QZACP) can improve the quality of life and prolong the survival time of patients with HCC. However, the precise mechanisms underlying the anti-cancer properties of QZACP remain unclear.

PURPOSE

This study examined the anti-hepatocarcinogenic properties of QZACP, with a specific focus on its influence on the p21-activated secretory phenotype (PASP)-mediated immune surveillance, to elucidate the underlying molecular pathways involved in HCC.

MATERIALS AND METHODS

Cell proliferation was measured using the Cell Counting Kit-8, 5-ethynyl-2'-deoxyuridine, and clonogenic assays. The cell cycle was evaluated using flow cytometry, and senescence was identified by staining with senescence-associated beta-galactosidase (SA-β-gal). A primary liver cancer model produced by diethylnitrosamine was established in C57 BL/6 mice to assess the tumor-inhibitory effect of QZACP. The liver's pathological characteristics were examined using hematoxylin and eosin staining. PASP screening was performed using GeneCards, DisGeNet, Online Mendelian Inheritance in Man, and The Cancer Genome Atlas databases. Western blot analysis, enzyme-linked immunosorbent assay (ELISA), immunofluorescence staining, and Transwell migration assays were performed.

RESULTS

Serum containing QZACP enhanced p21 expression, triggered cell cycle arrest, accelerated cell senescence, and suppressed cell proliferation in Huh7 and MHCC-97H liver cancer cells. QZACP reduced the quantity and dimensions of liver tumor nodules and enhanced p21 protein expression, SA-β-Gal staining in tumor lesions, and cytotoxic CD8+ T cell infiltration. Bioinformatic analyses indicated that PASP factors, including hepatocyte growth factor, decorin (DCN), dermatopontin, C-X-C motif chemokine ligand 14 (CXCL14), and Wnt family member 2 (WNT2), play an important role in the development of HCC. In addition, these factors are associated with the presence of natural killer cells and CD8+ T cells within tumors. Western blotting and ELISA confirmed that QZACP increased DCN, CXCL14, and WNT2 levels in tumor tissues and peripheral blood.

CONCLUSIONS

QZACP's suppression of HCC progression may involve cell senescence mediated via p21 upregulation, DCN, CXCL14, and WNT2 secretion, and reversal of the immunosuppressive microenvironment. This study provides insights that can be used in the development of new treatment strategies for HCC.

High salt diet accelerates skin aging in wistar rats: an 8-week investigation of cell cycle inhibitors, SASP markers, and oxidative stress

Background

Recent studies have shown that the high salt diet (HSD) is linked to increased dermal pro-inflammatory status and reduced extracellular matrix (ECM) expression in inflamed skin of mice. Decreased ECM content is a known aging phenotype of the skin, and alterations in ECM composition and organization significantly contribute to skin aging. This study aimed to determine whether a high salt diet accelerates skin aging and to identify the time point at which this effect becomes apparent.

Methods

Wistar rats were randomly divided into normal diet and high salt diet groups and fed continuously for 8 weeks. Skin samples were collected at weeks 7 and week 8. Skin pathological sections were evaluated and levels of cell cycle inhibitors, senescence-associated secretory phenotype (SASP), oxidative stress and vascular regulatory factors (VRFs) were examined. Correlation analyses were performed to reveal the effect of a high salt diet as an extrinsic factor on skin aging and to analyse the correlation between a high salt diet and intrinsic aging and blood flow status.

Results

At week 8, HSD rats exhibited thickened epidermis, thinned dermis, and atrophied hair follicles. The expression of cell cycle inhibitors and oxidative stress levels were significantly elevated in the skin of HSD rats at both week 7 and week 8. At week 7, some SASPs, including TGF-β and PAI-1, were elevated, but others (IL-1, IL-6, IL-8, NO) were not significantly changed. By week 8, inflammatory molecules (IL-1, IL-6, TGF-β), chemokines (IL-8), proteases (PAI-1), and non-protein molecules (NO) were significantly increased. Notably, despite elevated PAI-1 levels suggesting possible blood hypercoagulation, the ET-1/NO ratio was reduced in the HSD group at week 8.

Conclusion

The data suggest that a high salt diet causes skin aging by week 8. The effect of a high salt diet on skin aging is related to the level of oxidative stress and the expression of cell cycle inhibitors. Additionally, a potential protective mechanism may be at play, as evidenced by the reduced ET-1/NO ratio, which could help counteract the hypercoagulable state and support nutrient delivery to aging skin.

Linked regulation of genome integrity and senescence-associated inflammation by p53

Genomic instability and inflammation are distinct hallmarks of aging, but the connection between them is poorly understood. Understanding their interrelationship will help unravel new mechanisms and therapeutic targets of aging and age-associated diseases. Here we report a novel mechanism directly linking genomic instability and inflammation in senescent cells through a mitochondria-regulated molecular circuit driven by p53 and cytoplasmic chromatin fragments (CCF). We show, through activation or inactivation of p53 by genetic and pharmacologic approaches, that p53 suppresses CCF accumulation and the downstream inflammatory senescence-associated secretory phenotype (SASP), without affecting cell cycle arrest. p53 activation suppressed CCF formation by promoting DNA repair, and this is reflected in maintenance of genomic integrity, particularly in subtelomeric regions, as shown by single cell genome resequencing. Activation of p53 in aged mice by pharmacological inhibition of MDM2 reversed signatures of aging, including age- and senescence-associated transcriptomic signatures of inflammation and age-associated accumulation of monocytes and macrophages in liver. Remarkably, mitochondria in senescent cells suppressed p53 activity by promoting CCF formation and thereby restricting ATM-dependent nuclear DNA damage signaling. These data provide evidence for a mitochondria-regulated p53 signaling circuit in senescent cells that controls DNA repair, genome integrity, and senescence- and age-associated inflammation. This pathway is immunomodulatory in mice and a potential target for healthy aging interventions by small molecules already shown to activate p53.

Early senescence of pancreatic β cells induced by unfolded protein response deficiency prevents type 1 diabetes

Type 1 diabetes (T1D) is a T lymphocyte-mediated autoimmune disease caused by pancreatic β‍-cell destruction, which eventually leads to reduced insulin level and increased blood glucose level (Syed, 2022). As a multifactorial disease, T1D is characterized by a genetic predisposition associated with various environmental and cellular elements (Syed, 2022). Pancreatic β cells have long been considered the "innocent victims" in T1D pathogenesis since the pancreas is attacked by the immune cells, resulting in a process known as insulitis, in which the immune cells infiltrate pancreatic islets and secrete pro-inflammatory cytokines. However, growing evidence suggests that various β‍-cell stresses, dysfunction, and death contribute to T1D pathogenesis, as it has been observed that β‍-cell dysfunction in autoantibody-positive (Aab+) individuals exists long before T1D diagnosis (Evans-Molina et al., 2018).

IL-4 drives exhaustion of CD8+ CART cells

Durable response to chimeric antigen receptor T (CART) cell therapy remains limited in part due to CART cell exhaustion. Here, we investigate the regulation of CART cell exhaustion with three independent approaches including: a genome-wide CRISPR knockout screen using an in vitro model for exhaustion, RNA and ATAC sequencing on baseline and exhausted CART cells, and RNA and ATAC sequencing on pre-infusion CART cell products from responders and non-responders in the ZUMA-1 clinical trial. Each of these approaches identify interleukin (IL)-4 as a regulator of CART cell dysfunction. Further, IL-4-treated CD8+ CART cells develop signs of exhaustion independently of the presence of CD4+ CART cells. Conversely, IL-4 pathway editing or the combination of CART cells with an IL-4 monoclonal antibody improves antitumor efficacy and reduces signs of CART cell exhaustion in mantle cell lymphoma xenograft mouse models. Therefore, we identify both a role for IL-4 in inducing CART exhaustion and translatable approaches to improve CART cell therapy.

A p21-ATD mouse model for monitoring and eliminating senescent cells and its application in liver regeneration post injury

Cellular senescence associates with pathological aging and tissue dysfunctions. Studies utilizing mouse models for cell lineage tracings have emphasized the importance of senescence heterogeneity in different organs and cell types. Here, we constructed a p21- (Akaluc - tdTomato - Diphtheria Toxin Receptor [DTR]) (ATD) mouse model to specifically study the undefined mechanism for p21-expressing senescent cells in the aged and liver injury animals. The successful expressions of these genes enabled in vitro flow cytometric sorting, in vivo tracing, and elimination of p21-expressing senescent cells. During the natural aging process, p21-expressing cells were found in various tissues of p21-ATD mice. Eliminating p21-expressing cells in the aged p21-ATD mice recovered their multiple biological functions. p21-ATD/Fah-/- mice, bred from p21-ATD mice and fumarylacetoacetate hydrolase (Fah)-/- mice of liver injury, showed that the majority of their senescent hepatocytes were the phenotype of p21+ rather than p16+. Furthermore, eliminating the p21-expressing hepatocytes significantly promoted the engraftment of grafted hepatocytes and facilitated liver repopulation, resulting in significant recovery from liver injury. Our p21-ATD mouse model serves as an optimal model for studying the pattern and function of p21-expressing senescent cells under the physical and pathological conditions during aging.

Research progress on interferon and cellular senescence

Since the 12 major signs of aging were revealed in 2023, people's interpretation of aging will go further, which is of great significance for understanding the occurrence, development, and intervention in the aging process. As one of the 12 major signs of aging, cellular senescence refers to the process in which the proliferation and differentiation ability of cells decrease under stress stimulation or over time, often manifested as changes in cell morphology, cell cycle arrest, and decreased metabolic function. Interferon (IFN), as a secreted ligand for specific cell surface receptors, can trigger the transcription of interferon-stimulated genes (ISGs) and play an important role in cellular senescence. In addition, IFN serves as an important component of SASP, and the activation of the IFN signaling pathway has been shown to contribute to cell apoptosis and senescence. It is expected to delay cellular senescence by linking IFN with cellular senescence and studying the effects of IFN on cellular senescence and its mechanism. This article provides a review of the research on the relationship between IFN and cellular senescence by consulting relevant literature.

Long COVID as a disease of accelerated biological aging: An opportunity to translate geroscience interventions

It has been four years since long COVID-the protracted consequences that survivors of COVID-19 face-was first described. Yet, this entity continues to devastate the quality of life of an increasing number of COVID-19 survivors without any approved therapy and a paucity of clinical trials addressing its biological root causes. Notably, many of the symptoms of long COVID are typically seen with advancing age. Leveraging this similarity, we posit that Geroscience-which aims to target the biological drivers of aging to prevent age-associated conditions as a group-could offer promising therapeutic avenues for long COVID. Bearing this in mind, this review presents a translational framework for studying long COVID as a state of effectively accelerated biological aging, identifying research gaps and offering recommendations for future preclinical and clinical studies.

Anti-angiogenesis and anti-immunosuppression gene therapy through targeting COUP-TFII in an in situ glioblastoma mouse model

Glioblastoma (GBM) is the most common and aggressive primary brain cancer; angiogenesis and immunosuppression exacerbate GBM progression. COUP-TFII demonstrates pro-angiogenesis activity; however, its role in glioma progression remains unclear. This study revealed that COUP-TFII promotes angiogenesis in gliomas by inducing transdifferentiation of glioma cells into endothelial-like cells. Mechanistic investigation suggested that COUP-TFII as a transcription factor exerts its function via binding to the promoter of TXNIP. Interestingly, COUP-TFII knockdown attenuated tumorigenesis and tumor progression in an immunocompetent mouse model but promoted tumor progression in an immuno-deficient mouse model. As an explanation, repression of COUP-TFII induces cellular senescence and activates immune surveillance in glioma cells in vitro and in vivo. In addition, we used heparin-polyethyleneimine (HPEI) nanoparticles to deliver COUP-TFII shRNA, which regulated tumor angiogenesis and immunosuppression in an in situ GBM mouse model. This study provides a novel strategy and potential therapeutic targets to treat GBM.

The chromatin accessibility and transcriptomic landscape of the aging mice cochlea and the identification of potential functional super-enhancers in age-related hearing loss

BACKGROUND

Presbycusis, also referred to as age-related hearing loss (ARHL), is a condition that results from the cumulative effects of aging on an individual's auditory capabilities. Given the limited understanding of epigenetic mechanisms in ARHL, our research focuses on alterations in chromatin-accessible regions.

METHODS

We employed assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) in conjunction with unique identifier (UID) mRNA-seq between young and aging cochleae, and conducted integrated analysis as well as motif/TF-gene prediction. Additionally, the essential role of super-enhancers (SEs) in the development of ARHL was identified by comparative analysis to previous research. Meanwhile, an ARHL mouse model and an aging mimic hair cell (HC) model were established with a comprehensive identification of senescence phenotypes to access the role of SEs in ARHL progression.

RESULTS

The control cochlear tissue exhibited greater chromatin accessibility than cochlear tissue affected by ARHL. Furthermore, the levels of histone 3 lysine 27 acetylation were significantly depressed in both aging cochlea and aging mimic HEI-OC1 cells, highlighting the essential role of SEs in the development of ARHL. The potential senescence-associated super-enhancers (SASEs) of ARHL were identified, most of which exhibited decreased chromatin accessibility. The majority of genes related to the SASEs showed obvious decreases in mRNA expression level in aging HCs and was noticeably altered following treatment with JQ1 (a commonly used SE inhibitor).

CONCLUSION

The chromatin accessibility in control cochlear tissue was higher than that in cochlear tissue affected by ARHL. Potential SEs involved in ARHL were identified, which might provide a basis for future therapeutics targeting SASEs related to ARHL.