Cellular senescence drives age-dependent hepatic steatosis

The role and function of lncRNA in ageing-associated liver diseases

Liver diseases are a significant global health issue, characterized by elevated levels of disorder and death. The substantial impact of ageing on liver diseases and their prognosis is evident. Multiple processes are involved in the ageing process, which ultimately leads to functional deterioration of this organ. The process of liver ageing not only renders the liver more susceptible to diseases but also compromises the integrity of other organs due to the liver's critical function in metabolism regulation. A growing body of research suggests that long non-coding RNAs (lncRNAs) play a significant role in the majority of pathophysiological pathways. They regulate gene expression through a variety of interactions with microRNAs (miRNAs), messenger RNAs (mRNAs), DNA, or proteins. LncRNAs exert a major influence on the progression of age-related liver diseases through the regulation of cell proliferation, necrosis, apoptosis, senescence, and metabolic reprogramming. A concise overview of the current understanding of lncRNAs and their potential impact on the development of age-related liver diseases will be provided in this mini-review.

Imbalanced redox dynamics induce fibroblast senescence leading to impaired stem cell pools and skin aging

Skin function depends on a meticulously regulated dynamic interaction of distinct skin compartments such as the epidermis and dermis. Adaptive responses at the molecular and cellular level are essential for these interactions - and if dysregulated - drive skin aging and other pathologies. After defining the role of redox homeodynamics in physiology and aging pathology, we focus on the redox distress-dependent aging of dermal fibroblasts including their progenitors. We here discuss the prime role of senescent fibroblasts in the control of their own endogenous niche and stem cell niches for epidermal stem cells, hair follicle stem cells, adipocyte precursors and muscle stem cells. We here review that redox imbalance induced reduction in Insulin-like Growth Factor-1 drives skin aging by the depletion of stem cell pools. This IGF-1 reduction is mediated via the redox-sensitive transcription factor JunB and also by the redox-dependent changes in sphingolipid-metabolism, among others. In addition, we will discuss the changes in the extracellular matrix of the skin affecting cellular senescence and the skin integrity and function in aging. The aim is a deeper understanding of the two main redox-dependent hubs such as JunB-induced depletion of IGF-1, and the sphingolipid-mediated remodeling of the cell membrane with its impact on IGF-1, fibroblast heterogeneity, function, senescence and plasticity in skin aging.

Aging at the Crossroads of Organ Interactions: Implications for the Heart

Aging processes underlie common chronic cardiometabolic diseases such as heart failure and diabetes. Cross-organ/tissue interactions can accelerate aging through cellular senescence, tissue wasting, accelerated atherosclerosis, increased vascular stiffness, and reduction in blood flow, leading to organ remodeling and premature failure. This interorgan/tissue crosstalk can accelerate aging-related dysfunction through inflammation, senescence-associated secretome, and metabolic and mitochondrial changes resulting in increased oxidative stress, microvascular dysfunction, cellular reprogramming, and tissue fibrosis. This may also underscore the rising incidence and co-occurrence of multiorgan dysfunction in cardiometabolic aging in the population. Examples include interactions between the heart and the lungs, kidneys, liver, muscles, and brain, among others. However, this phenomenon can also present new translational opportunities for identifying diagnostic biomarkers to define early risks of multiorgan dysfunction, gain mechanistic insights, and help to design precision-directed therapeutic interventions. Indeed, this opens new opportunities for therapeutic development in targeting multiple organs simultaneously to disrupt the crosstalk-driven process of mutual disease acceleration. New therapeutic targets could provide synergistic benefits across multiple organ systems in the same at-risk patient. Ultimately, these approaches may together slow the aging process itself throughout the body. In the future, with patient-centered multisystem coordinated approaches, we can initiate a new paradigm of multiorgan early risk prediction and tailored intervention. With emerging tools including artificial intelligence-assisted risk profiling and novel preventive strategies (eg, RNA-based therapeutics), we may be able to mitigate multiorgan cardiometabolic dysfunction much earlier and, perhaps, even slow the aging process itself.

Anti-senescence therapies: a new concept to address cardiovascular disease

Accumulation of senescent cells is an increasingly recognized factor in the development and progression of cardiovascular (CV) disease (CVD). Senescent cells of different types display a pro-inflammatory and matrix remodelling molecular programme, known as the 'senescence-associated secretory phenotype' (SASP), which has roots in (epi)genetic changes. Multiple therapeutic options (senolytics, anti-SASP senomorphics, and epigenetic reprogramming) that delete or ameliorate cellular senescence have recently emerged. Some drugs routinely used in the clinics also have anti-senescence effects. However, multiple challenges hinder the application of novel anti-senescence therapeutics in the clinical setting. Understanding the biology of cellular senescence, advantages and pitfalls of anti-senescence treatments, and patients who can profit from these interventions is necessary to introduce this novel therapeutic modality into the clinics. We provide a guide through the molecular machinery of senescent cells, systematize anti-senescence treatments, and propose a pathway towards senescence-adapted clinical trial design to aid future efforts.

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.

Targeting the chromatin remodeler BAZ2B mitigates hepatic senescence and MASH fibrosis

With increased age, the liver becomes more vulnerable to metabolic dysfunction-associated steatohepatitis (MASH) with fibrosis. Deciphering the complex interplay between aging, the emergence of senescent cells in the liver and MASH fibrosis is critical for developing treatments. Here we report an epigenetic mechanism that links liver aging to MASH fibrosis. We find that upregulation of the chromatin remodeler BAZ2B in a subpopulation of hepatocytes (HEPs) is linked to MASH pathology in patients. Genetic ablation or hepatocyte-specific knockdown of Baz2b in mice attenuates HEP senescence and MASH fibrosis by preserving peroxisome proliferator-activated receptor α (PPARα)-mediated lipid metabolism, which was impaired in both naturally aged and MASH mouse livers. Mechanistically, Baz2b downregulates the expression of genes related to the PPARα signaling pathway by directly binding their promoter regions and reducing chromatin accessibility. Thus, our study unravels the BAZ2B-PPARα-lipid metabolism axis as a link from liver aging to MASH fibrosis, suggesting that BAZ2B is a potential therapeutic target for HEP senescence and fibrosis.

In vitro senescence and senolytic functional assays

A detailed understanding of aging biology and the development of anti-aging therapeutic strategies remain imperative yet inherently challenging due to the protracted nature of aging. Cellular senescence arises naturally through replicative exhaustion and is accelerated by clinical treatments or environmental stressors. The accumulation of senescent cells-defined by a loss of mitogenic potential, resistance to apoptosis, and acquisition of a pro-inflammatory secretory phenotype-has been implicated as a key driver of chronic disease, tissue degeneration, and organismal aging. Recent studies have highlighted the therapeutic promise of senolytic drugs, which selectively eliminate senescent cells. Compelling results from preclinical animal studies and ongoing clinical trials underscore this potential. However, the clinical translation of senolytics requires further pharmacological validation to refine selectivity, minimize toxicity, and determine optimal dosing. Equally important is the evaluation of senolytics' potential to restore tissue structure and function by reducing the senescent cell burden. In vitro tissue culture models offer a powerful platform to advance these efforts. This review summarizes the current landscape of in vitro systems used for inducing cellular senescence-referred to as "senescence assays"-and for screening senolytic drugs-referred to as "senolytic assays". We conclude by discussing key challenges to improving mechanistic insight, predictive accuracy, and clinical relevance in senolytic drug development, as well as emerging applications of senolytic therapies.

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.

Association of biological aging and the prevalence of nonalcoholic fatty liver disease: a population-based study

PURPOSE

To examine the relationship between biological aging and the prevalence of NAFLD.

METHOD

We used the recommended sampling weights to account for the complex survey design of NHANES. The analysis, utilizing data from 2005 to 2016, aimed to investigate the impact of biological aging on NAFLD prevalence using various statistical methods. A restricted cubic spline (RCS) model was applied to explore the dose-response relationship, while logistic regression examined linear associations. The robustness of the association across different subgroups was also tested.

RESULT

The study included 2786 participants. We found significant associations between NAFLD and the following biological aging metrics: AL score (OR (95%CI) = 1.1932 (1.0597 ~ 1.3435), P = 0.0035), HD (OR (95%CI) = 1.2092 (1.0565 ~ 1.3839), P = 0.0058), and PA (OR (95%CI) = 1.7564 (1.1949 ~ 2.5818), P = 0.0042). All biological aging metrics were identified as independent predictors. PA was most associated with the prevalence of NAFLD. The associations persisted across most subgroups.

CONCLUSION

The prevalence of NAFLD was associated with biological aging, emphasizing the importance of addressing potential health risks related to aging.

Single cell multiomics reveals drivers of metabolic dysfunction-associated steatohepatitis

Metabolic dysfunction-associated steatotic liver disease (MASLD) has limited treatments, and cell type-specific regulatory networks driving MASLD represent therapeutic avenues. We assayed five transcriptomic and epigenomic modalities in 2.4M cells from 86 livers across MASLD stages. Integrating modalities increased annotation of the genome in liver cell types several-fold over previous catalogs. We identified cell type regulatory networks of MASLD progression, including distinct hepatocyte networks driving MASL and mild and severe fibrosis MASH. Our single cell atlas annotated 88% of MASH-associated loci, including a third affecting hepatocyte regulation which we linked to distal target genes. Finally, we characterized hepatocyte heterogeneity, including MASH-enriched populations with altered repression, localization, and signaling. Overall, our results provide high-resolution maps of liver cell types and revealed novel targets for anti-MASH therapy.

Accelerated Biological Aging, Genetic Susceptibility, and Non-Alcoholic Fatty Liver Disease: Two Prospective Cohort Studies

Background: Biological aging is considered a vital risk factor for age-related diseases, but its role in non-alcoholic fatty liver disease (NAFLD) remains uncertain. This study aimed to evaluate the associations of biological aging with NAFLD and the modified effect of genetic susceptibility. Methods: This study included 329,040 participants from the UK Biobank and 6783 participants from the Dongfeng-Tongji Cohort in China. We calculated the chronological age-adjusted biological age as a surrogate measure for biological aging. Accelerated aging was defined as biological age that exceeded chronological age. The association between biological aging and the risk of NAFLD was assessed in the two cohorts. Polygenic risk scores (PRSs) were used to determine genetic susceptibility for NAFLD in the UK Biobank and further analyze the interaction with biological aging. Results: In the UK Biobank, one year older in age-adjusted biological age increased prevalent NAFLD risk by 6%. The hazard ratios (HRs) and 95% confidence intervals (95% CIs) of NAFLD by accelerated aging were 1.35 (1.17, 1.56) and 1.69 (1.54, 1.85) compared to non-aging. In the Dongfeng-Tongji Cohort, biological aging was prospectively associated with NAFLD (accelerated aging: odds ratio (OR) (95% CI) = 1.18 (1.03, 1.36)). In the UK Biobank, high genetic risk was significantly associated with higher NAFLD risk compared to low genetic risk (HRs (95% CIs) = 1.65 (1.40, 1.95)). Analyses of joint effects showed that participants with high PRS and accelerated aging had the highest risk of NAFLD [2.66 (2.98, 3.57) and 2.06 (2.36, 3.96)]. However, biological aging was prospectively associated with NAFLD among participants regardless of genetic risk. There was no significant interaction between genetic risk and biological aging. Conclusions: Accelerated biological aging was associated with a higher risk of NAFLD independent of genetic susceptibility. Identifying populations with accelerated biological aging by the use of surrogate measures and timely intervention may be beneficial for the prevention of NAFLD.

Beacon of Hope for Age-Related Retinopathy: Antioxidative Mechanisms and Pre-Clinical Trials of Quercetin Therapy

Age-related retinopathy is one of the leading causes of visual impairment and irreversible blindness, characterized by progressive neuronal and myelin loss. The damages caused by oxidation contributes to the hallmarks of aging and represents fundamental components in pathological pathways that are thought to drive multiple age-related retinopathies. Quercetin (Que), a natural polyphenol abundant in vegetables, herbs, and fruits, has been extensively studied for its long-term antioxidative effects mediated through diverse mechanisms. Additionally, Que and its derivatives exhibit a broad spectrum of pharmacological characteristics in the cellular responses of age-related retinopathy induced by oxidative stress, including anti-inflammatory, anti-neovascularization, regulatory, and neuroprotective effects in autophagy and apoptosis processes. This review mainly focuses on the antioxidative mechanisms and curative effects of Que treatment for various age-related retinopathies, such as retinitis pigmentosa, diabetic retinopathy, age-related macular degeneration, and glaucoma. Furthermore, we discuss emerging technologies and methods involving Que and its derivatives in the therapeutic strategies for age-related retinopathies, highlighting their promise for clinical translation.

Hepatic sphingomyelin phosphodiesterase 3 promotes steatohepatitis by disrupting membrane sphingolipid metabolism

Metabolic-dysfunction-associated steatohepatitis (MASH) remains a major health challenge. Herein, we identify sphingomyelin phosphodiesterase 3 (SMPD3) as a key driver of hepatic ceramide accumulation through increasing sphingomyelin hydrolysis at the cell membrane. Hepatocyte-specific Smpd3 gene disruption or pharmacological inhibition of SMPD3 alleviates MASH, whereas reintroducing SMPD3 reverses the resolution of MASH. Although healthy livers express low-level SMPD3, lipotoxicity-induced DNA damage suppresses sirtuin 1 (SIRT1), triggering an upregulation of SMPD3 during MASH. This disrupts membrane sphingomyelin-ceramide balance and promotes disease progression by enhancing caveolae-dependent lipid uptake and extracellular vesicle secretion from steatotic hepatocytes to exacerbate inflammation and fibrosis. Consequently, SMPD3 acts as a central hub integrating key MASH hallmarks. Notably, we discovered a bifunctional agent that simultaneously activates SIRT1 and inhibits SMPD3, which shows significant therapeutic potential in MASH treatment. These findings suggest that inhibition of hepatic SMPD3 restores membrane sphingolipid metabolism and holds great promise for developing novel MASH therapies.

Aging and metabolic dysfunction-associated steatotic liver disease: a bidirectional relationship

In recent years, aging and cellular senescence have triggered an increased interest in corresponding research fields. Evidence shows that the complex aging process is involved in the development of many chronic liver diseases, such as metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH). In fact, aging has a tremendous effect on the liver, leading to a gradual decline in the metabolism, detoxification and immune functions of the liver, which in turn increases the risk of liver disease. These changes can be based on the aging of liver cells (hepatocytes, liver sinusoidal endothelial cells, hepatic stellate cells, and Kupffer cells). Similarly, patients with liver diseases exhibit increases in the aging phenotype and aging cells, often manifesting as faster physical functional decline, which is closely related to the promoting effect of liver disease on aging. This review summarizes the interplay between MASLD/MASH development and aging, aiming to reveal the complex relationships that exacerbate one another. Moreover, the corresponding schemes for delaying aging or treating diseases are discussed to provide a basis for the development of effective prevention and treatment strategies in the future.

Assessing Metabolic Ageing via DNA Methylation Surrogate Markers: A Multicohort Study in Britain, Ireland and the USA

Metabolomics and epigenomics have been used to develop 'ageing clocks' that assess biological age and identify 'accelerated ageing'. While metabolites are subject to short-term variation, DNA methylation (DNAm) may capture longer-term metabolic changes. We aimed to develop a hybrid DNAm-metabolic clock using DNAm as metabolite surrogates ('DNAm-metabolites') for age prediction. Within the UK Airwave cohort (n = 820), we developed DNAm metabolites by regressing 594 metabolites on DNAm and selected 177 DNAm metabolites and 193 metabolites to construct 'DNAm-metabolic' and 'metabolic' clocks. We evaluated clocks in their age prediction and association with noncommunicable disease risk factors. We additionally validated the DNAm-metabolic clock for the prediction of age and health outcomes in The Irish Longitudinal Study of Ageing (TILDA, n = 488) and the Health and Retirement Study (HRS, n = 4018). Around 70% of DNAm metabolites showed significant metabolite correlations (Pearson's r: > 0.30, p < 10-4) in the Airwave test set and overall stronger age associations than metabolites. The DNAm-metabolic clock was enriched for metabolic traits and was associated (p < 0.05) with male sex, heavy drinking, anxiety, depression and trauma. In TILDA and HRS, the DNAm-metabolic clock predicted age (r = 0.73 and 0.69), disability and gait speed (p < 0.05). In HRS, it additionally predicted time to death, diabetes, cardiovascular disease, frailty and grip strength. DNAm metabolite surrogates may facilitate metabolic studies using only DNAm data. Clocks built from DNAm metabolites provided a novel approach to assess metabolic ageing, potentially enabling early detection of metabolic-related diseases for personalised medicine.

Quasi-spatial single-cell transcriptome based on physical tissue properties defines early aging associated niche in liver

Aging is associated with the accumulation of senescent cells, which are triggered by tissue injury response and often escape clearance by the immune system. The specific traits and diversity of these cells in aged tissues, along with their effects on the tissue microenvironment, remain largely unexplored. Despite the advances in single-cell and spatial omics technologies to understand complex tissue architecture, senescent cell populations are often neglected in general analysis pipelines due to their scarcity and the technical bias in current omics toolkits. Here we used the physical properties of tissue to enrich the age-associated fibrotic niche and subjected them to single-cell RNA sequencing and single-nuclei ATAC sequencing (ATAC-seq) analysis and named this method fibrotic niche enrichment sequencing (FiNi-seq). Fibrotic niche of the tissue was selectively enriched based on its resistance to enzymatic digestion, enabling quasi-spatial analysis. We profiled young and old livers of male mice using FiNi-seq, discovered Wif1- and Smoc1-producing mesenchymal cell populations showing senescent phenotypes, and investigated the early immune responses within this fibrotic niche. Finally, FiNi-ATAC-seq revealed age-associated epigenetic changes enriched in fibrotic niche cells. Thus, our quasi-spatial, single-cell profiling method allows the detailed analysis of initial aging microenvironments, providing potential therapeutic targets for aging prevention.

The context-dependent effect of cellular senescence: From embryogenesis and wound healing to aging

Aging is characterized by a steady loss of physiological integrity, leading to impaired function and increased vulnerability to death. Cell senescence is a biological process that progresses with aging and is believed to be a key driver of age-related diseases. Senescence, a hallmark of aging, also demonstrates its beneficial physiological aspects as an anti-cancer, pro-regenerative, homeostatic, and developmental mechanism. A transitory response in which the senescent cells are quickly formed and cleared may promote tissue regeneration and organismal fitness. At the same time, senescence-related secretory phenotypes associated with extended senescence can have devastating effects. The fact that the interaction between senescent cells and their surroundings is very context-dependent may also help to explain this seemingly opposing pleiotropic function. Further, mitochondrial dysfunction is an often-unappreciated hallmark of cellular senescence and figures prominently in multiple feedback loops that induce and maintain the senescent phenotype. This review summarizes the mechanism of cellular senescence and the significance of acute senescence. We concisely introduced the context-dependent role of senescent cells and SASP, aspects of mitochondrial biology altered in the senescent cells, and their impact on the senescent phenotype. Finally, we conclude with recent therapeutic advancements targeting cellular senescence, focusing on acute injuries and age-associated diseases. Collectively, these insights provide a future roadmap for the role of senescence in organismal fitness and life span extension.

Niclosamide extends health span and reduces frailty by ameliorating mTORC1 hyperactivation in aging models

INTRODUCTION

Frailty is characterized by an increased vulnerability to disease and physical debilitation due to a decline in the body's capacity to maintain homeostasis during aging. Therefore, effective management of frailty is crucial for promoting health. Although the role of niclosamide (NIC), an autophagy promoter, has been studied for the treatment of cancer, infectious diseases, and metabolic disorders, no research has focused on its effects on aging.

OBJECTIVES

In this study, we aimed to evaluate the effects of NIC on the aging process and assess its potential as a novel anti-aging therapeutic agent.

METHODS

We evaluated the effects of NIC on frailty, physical function, and metabolic function using Caenorhabditis elegans (C. elegans) and aging mouse models. NIC effectiveness was assessed using behavioral experiments, histological analysis, and molecular biological analysis.

RESULTS

We identified NIC as a compound that enhanced exercise capacity and metabolism, thereby alleviating frailty. Briefly, NIC extended the lifespan and improved frailty-related phenotypes in C. elegans, and effectively ameliorated frailty in aging mice, particularly in muscle aging. Additionally, NIC treatment suppressed the muscle atrophy-related ubiquitin-proteasome system induced by mammalian target of rapamycin complex 1 (mTORC1) hyperactivation, while enhancing autophagic flux, another aspect of proteostasis. Furthermore, mRNA-seq analysis revealed that NIC improved metabolism-related functions.

CONCLUSION

Collectively, these findings suggest that NIC is a promising novel candidate for the prevention of frailty.

Fisetin Clears Senescent Cells Through the Pi3k-Akt-Bcl-2/Bcl-xl Pathway to Alleviate Diabetic Aortic Aging

Vascular aging is a major contributor to age-related cardiovascular diseases (CVDs) and type 2 diabetes mellitus (T2DM) induced early arterial aging and excessive senescent cells (SCs) burden in vessels. Inhibiting cellular senescence or eliminating SCs could effectively improve aging-related CVDs. Fisetin, a flavonoid extracted from cotinus coggygria scop, has shown potential in alleviating aging by clearing SCs. This study investigated the unexplored mechanisms and efficacy of fisetin in alleviating T2DM-related aortic aging. The T2DM mouse model was induced using a high-fat diet and low-dose streptozotocin injection. Chronic fisetin treatment's protective effects against aortic aging were assessed via senescence-associated beta-galactosidase (SA-β-Gal) staining, histopathology, and vasomotor function. RNA-sequencing and western blotting identified relevant signaling pathways and protein expression. Fisetin's effects on SCs and senescence-associated secretory phenotype (SASP) factors were evaluated through cell viability, apoptosis, and co-culture assays. Docking simulations suggested fisetin as a potential Phosphoinositide 3-kinase (Pi3k) inhibitor. In vivo, chronic fisetin treatment reduced aortic SCs burden, alleviating T2DM-related and natural aortic aging. In vitro, fisetin selectively induced apoptosis of senescent endothelial cells via regulating the Pi3k-Protein Kinase B (Akt)-B-cell lymphoma (Bcl)-2/Bcl-xl pathway and suppressed SASP and its detrimental effects. Furthermore, fisetin combined with metformin therapy showed superior anti-aging effects on T2DM-related aortic aging compared to metformin monotherapy. In conclusion, chronic fisetin treatment alleviates T2DM-related aortic aging via clearing the SCs burden and abrogating the SASP factors. Fisetin combined with metformin therapy might be a potential therapeutic strategy for T2DM-related CVDs.

Nano-encapsulated senolytic cocktail attenuates germ cell senescence in female mice

Low-quality oocytes directly affect fertilization and embryonic development, contributing to infertility in women, while germ cell senescence leads to reduced germ cell numbers and decreased egg quality. Dasatinib and quercetin (D and Q), as senolytic drugs, have been extensively explored in different age-related diseases. However, their effects on in vitro cultured senescent oocytes and the molecular mechanisms underpinning ovarian aging remain elusive. Here, we report that a nano-encapsulated senolytic D + Q cocktail efficiently improves the quality of post-ovulatory aging oocyte in vitro and follicle quantity in ovaries in a cyclophosphamide (Cy)-induced premature ovarian failure (POF) mouse model. Cocktail supplementation to cultured oocytes potently reduces reactive oxygen species (ROS) levels, maintains spindle integrity, decreases fragmented oocyte frequencies, rescues mislocalized cortical granules (CGs) and mitochondrial membrane potential (MMP), and alleviates DNA damage and apoptosis. Importantly, the cocktail effectively ameliorates fertility deficits in the model. Transcriptome analysis shows cocktail administration to fertility-deficient mice not only up-regulates developmental gene expression but also reduces senescence-associated secretory phenotype (SASP) accumulation. Therefore, our nano-encapsulated D + Q cocktail is a promising reagent for assisted reproductive technology and improving reproductive outcomes in POF.

Hepatic-specific vitamin D receptor downregulation alleviates aging-related metabolic dysfunction-associated steatotic liver disease

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) is defined by the abnormal lipid deposition in hepatocytes. The prevalence of MASLD is significantly increased in the elderly population, suggesting that aging may be related to the occurrence of MASLD. Emerging evidences suggest that vitamin D receptor (VDR) may be implicated in the progression of MASLD. Therefore, additional researches are warranted to elucidate whether VDR plays a role in aging-related MASLD.

AIM

To investigate the relationship between aging and MASLD and explore the role and related mechanisms of VDR in aging-related MASLD.

METHODS

Cellular senescence models were established, and the senescence phenotype of telomerase RNA component knockout mice was validated. These mice were then used as a senescence model for subsequent studies. Changes in VDR expression in the livers of aging mice were examined. VDR knockdown models, including cell knockdown models and hepatic-specific VDR knockout mice, were constructed, and MASLD was established in these models. Additionally, vitamin D (VD)-supplemented models, including senescent liver cell lines and senescent mice, were constructed.

RESULTS

The steatosis in senescent liver cells was more severe than in normal cells (P < 0.05). Moreover, hepatic steatosis was significantly more pronounced in senescence model mice compared to control group when the MASLD model was successfully induced (P < 0.05). Therefore, we concluded that aging aggravated hepatic steatosis. The hepatic expression of VDR increased after aging. VDR knockdown in senescent liver cells and senescent mice alleviated hepatic steatosis (P < 0.05). When senescent liver cells were stimulated with VD, cellular steatosis was aggravated (P < 0.05). However, VD supplementation had no effect on aging mice.

CONCLUSION

Aging can lead to increased hepatic steatosis, and the hepatic-specific knockdown of VDR alleviated aging-related MASLD. VDR could serve as a potential molecular target for aging-related MASLD.

Attenuation of Cellular Senescence and Improvement of Osteogenic Differentiation Capacity of Human Liver Stem Cells Using Specific Senomorphic and Senolytic Agents

Expansion of adult stem cells in culture increases the percent of senescent cells, reduces their differentiation capacity and limits their clinical use. Here, we investigated whether treatment with certain senotherapeutic drugs would reduce the accumulation of senescent cells during expansion of human liver stem cells (HLSCs) while maintaining their differentiation capacity. Our results demonstrate that chronic treatment with the senomorphic XJB-5-131 or the senolytics cocktail D + Q reduced the number of senescent cells and significantly reduced the expression of senescence-associated genes and several inflammatory SASP factors in later passage HLSCs. Additionally, treatment with XJB-5-131 and D + Q improved the capacity of HLSCs to undergo osteogenic differentiation following extensive in vitro expansion. Overall, our data demonstrate that treatment with XJB-5-13 or D + Q results in a reduction in the percentage of replication-induced senescent HLSCs and likely other types of adult stem cells and improve the potential therapeutic use of later passage human stem cells.

Green Tea Mitigates the Hallmarks of Aging and Age-Related Multisystem Deterioration

Aging is characterized by progressive multisystem deterioration driven by molecular and cellular mechanisms encapsulated in the twelve hallmarks of aging. Green tea (GT), derived from Camellia sinensis, has garnered significant scientific interest due to its rich polyphenolic composition, particularly epigallocatechin-3-gallate, and its pleiotropic health benefits. In this narrative review, we explored the multifaceted mechanisms through which GT may mitigate the aging hallmarks. Evidence from in vitro, animal, and human studies has shown that GT polyphenols can enhance DNA repair pathways, preserve telomere length, modulate epigenetic aging markers, improve proteostasis and autophagic flux, regulate nutrient-sensing networks, and rejuvenate mitochondrial function. Additionally, GT exhibits anti-inflammatory properties and may restore a physiological gut microbiota composition. Beyond molecular and cellular effects, GT consumption in humans has been associated with improved cognitive function, cardiovascular health, muscle preservation, and metabolic regulation in aging populations. Collectively, these findings highlight GT's potential as a naturally occurring geroscience intervention capable of addressing the interconnected network of aging processes more comprehensively than single-target pharmaceuticals. Future research should focus on optimizing dosing regimens, exploring synergies with other anti-aging strategies, and investigating personalized responses to GT interventions.

Effects of induced molting on lipid accumulation in liver of aged laying hens

As the age of laying increases, the metabolic capacity of the liver decreases, leading to excessive lipid accumulation, which seriously affects the laying performance of laying hens. Induced molting (IM) can rejuvenate the reproductive system of older laying hens, allowing them to enter a new laying cycle. However, it remains unclear whether induced molting can enhance lipid accumulation in the liver of aged laying hens and what the underlying mechanism might be. In this study, fasting-induced molting was performed on 70-week-old Hy-line brown laying hens, and the resulting metabolic changes were analyzed using non-targeted metabolomics. Serum lipid levels, liver oxidative stress, and inflammation were measured using kits, while autophagy and lipid metabolism-related factors were assessed through immunofluorescence and western blotting. The results showed that IM could promote hepatic lipid deposition in aged laying hens, reduce hepatic steatosis and injury, lower the blood lipid level, improve hepatic antioxidant capacity and increase egg production rate. During the fasting period, the hepatic autophagic system was activated in laying hens and the level of hepatic autophagy increased. Additionally, AMPK phosphorylation levels increased, while the expression of fatty acid synthesis genes SREBP-1C, ACC, and FASN decreased (P < 0.01). The expression of PPARα, PGC 1α and CPT1A, which are associated with fatty acid oxidation, was upregulated (P < 0.01). In conclusion, IM enhanced lipid metabolism, increased liver autophagy, and improved liver function in aged laying hens.

Telomere function and regulation from mouse models to human ageing and disease

Telomeres protect the ends of chromosomes but shorten following cell division in the absence of telomerase activity. When telomeres become critically short or damaged, a DNA damage response is activated. Telomeres then become dysfunctional and trigger cellular senescence or death. Telomere shortening occurs with ageing and may contribute to associated maladies such as infertility, neurodegeneration, cancer, lung dysfunction and haematopoiesis disorders. Telomere dysfunction (sometimes without shortening) is associated with various diseases, known as telomere biology disorders (also known as telomeropathies). Telomere biology disorders include dyskeratosis congenita, Høyeraal-Hreidarsson syndrome, Coats plus syndrome and Revesz syndrome. Although mouse models have been invaluable in advancing telomere research, full recapitulation of human telomere-related diseases in mice has been challenging, owing to key differences between the species. In this Review, we discuss telomere protection, maintenance and damage. We highlight the differences between human and mouse telomere biology that may contribute to discrepancies between human diseases and mouse models. Finally, we discuss recent efforts to generate new 'humanized' mouse models to better model human telomere biology. A better understanding of the limitations of mouse telomere models will pave the road for more human-like models and further our understanding of telomere biology disorders, which will contribute towards the development of new therapies.

Metabolism and metabolomics in senescence, aging, and age-related diseases: a multiscale perspective

The pursuit of healthy aging has long rendered aging and senescence captivating. Age-related ailments, such as cardiovascular diseases, diabetes, and neurodegenerative disorders, pose significant threats to individuals. Recent studies have shed light on the intricate mechanisms encompassing genetics, epigenetics, transcriptomics, and metabolomics in the processes of senescence and aging, as well as the establishment of age-related pathologies. Amidst these underlying mechanisms governing aging and related pathology metabolism assumes a pivotal role that holds promise for intervention and therapeutics. The advancements in metabolomics techniques and analysis methods have significantly propelled the study of senescence and aging, particularly with the aid of multiscale metabolomics which has facilitated the discovery of metabolic markers and therapeutic potentials. This review provides an overview of senescence and aging, emphasizing the crucial role metabolism plays in the aging process as well as age-related diseases.

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 clearly shows how differences in the spatiotemporal dynamics of different senescent cell phenotypes lead to several distinct repair outcomes. These differences in senescent cell dynamics can be attributed to variable SASP composition, duration of senescence and temporal induction of senescence relative to the healing stage. The range of outcomes demonstrated strongly highlight the dynamic and heterogenous role of senescent cells in wound healing, fibrosis and chronic wounds, and their fine-tuned control. Further specific data to increase model confidence could be used to explore senolytic treatments in wound disorders.

Cells of all trades - on the importance of spatial positioning of senescent cells in development, healing and aging

Biological processes are often spatially regulated, ensuring molecular and cellular events occur in their most strategically advantageous locations. Cellular senescence, marked by cell cycle arrest and hypersecretion, is recognized as an important part of physiological processes like development and healing, but it also contributes to aging and disease. However, the spatial distribution of senescent cells and its physiological and pathological impact remain unclear. Here we compile evidence on senescent cell localization in development, healing, and aging. We emphasize the significance of their spatial patterns and speculate on the effects of disrupted spatial positioning of senescence in relation to pathologies. To summarize the specific spatial functions of senescent cells, we propose to refer to them as 'barrier' and 'conductor' functions. The 'barrier' function of senescent cells, due to their altered morphology and apoptosis resistance, separates tissues and builds a border between two environments. The conductor function, with the secretion of signaling factors, influences the surrounding area and stimulates migration, differentiation, or proliferation, among other processes. Overall, this Review explores the spatial patterning of cellular senescence in biological processes, highlighting its dual roles as 'barrier' and 'conductor' functions, and examines the implications of senescent cell distribution in development, healing, aging, and disease.

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.

Longitudinal paired liver biopsies and transcriptome profiling in alcohol-associated hepatitis reveal dynamic changes in cellular senescence

BACKGROUND AND AIMS

Alcohol-associated hepatitis (AH) is an acute form of alcohol-related liver disease (ALD) with high mortality rate. AH is histologically characterised by cellular processes, including steatosis, inflammation and cell death. Apoptosis is the most studied form of cell death in AH; however, the role of cellular senescence, another response to cellular injury, in AH is unknown. Here, we explore the mechanisms of ALD pathophysiology and describe the role of senescence in AH.

METHODS

We performed RNA sequencing and bioinformatics analysis of 0- and 28-day transjugular liver biopsies (n=65) from patients with AH participating in the IL-1 Signal Inhibition In Alcoholic Hepatitis (ISAIAH) clinical trial. Additional bioinformatics reanalysis of existing AH transcriptomic datasets was conducted to confirm our findings. We also performed multiomic analysis of an in vitro model of AH with ethanol-treated hepatocytes overexpressing ethanol-metabolising enzymes.

RESULTS

Our longitudinal analysis revealed that senescence and inflammation were reduced at transcriptomic level following AH resolution; the expression of hepatocyte markers was increased. We identified two senescence-associated protein complexes, cytochrome c oxidase and the proteasome, which may act as senescence-induction mechanisms. We confirmed that senescence markers and pathways were increasingly expressed in hepatocytes as ALD progressed towards AH; this was partially reversed following AH resolution. Our in vitro model revealed that ethanol directly induces senescence and was dependent on ethanol metabolism.

CONCLUSIONS

Our results suggest a possible pathogenic role for senescence in AH and indicate cellular senescence as a potential therapeutic target in early ALD to limit AH severity.

Fisetin as a Blueprint for Senotherapeutic Agents - Elucidating Geroprotective and Senolytic Properties with Molecular Modeling

Targeting senescent cells and the factors that accelerate this pathological state has recently emerged as a novel field in medicinal chemistry. As attention shifts to synthetic substances, studies on natural agents are often overlooked. In this paper, we present a detailed computational modeling study that encompasses quantum mechanics and molecular dynamics to elucidate the senotherapeutic activity of fisetin, a natural flavonoid. The mitochondrial environment, serving as a proxy for senescence, received special attention. Throughout the study, fisetin's outstanding geroprotective properties-exhibiting significant potential against ⋅OOH, O2⋅-, and ⋅OH radicals, surpassing those of Trolox or ascorbate-were identified. Furthermore, fisetin demonstrated a high capacity to restore oxidatively damaged biomolecules to their pristine forms, thereby renewing the functionality of proteins and amino acids. The senolytic properties were examined in terms of Bcl-2 and Bcl-xL inhibition. The results indicated that fisetin not only binds effectively to these proteins but also, with appropriate modifications, may exhibit specific selectivity toward either target. This study highlights fisetin's remarkable activity in these areas and provides a molecular description of the underlying processes, paving the way for future research.

Systemic aging and aging-related diseases

Aging is a biological process along with systemic and multiple organ dysfunction. It is more and more recognized that aging is a systemic disease instead of a single-organ functional disorder. Systemic aging plays a profound role in multiple diseases including neurodegenerative diseases, cardiovascular diseases, and malignant diseases. Aged organs communicate with other organs and accelerate aging. Skeletal muscle, heart, bone marrow, skin, and liver communicate with each other through organ-organ crosstalk. The crosstalk can be mediated by metabolites including lipids, glucose, short-chain fatty acids (SCFA), inflammatory cytokines, and exosomes. Metabolic disorders including hyperglycemia, hyperinsulinemia, and hypercholesterolemia caused by chronic diseases accelerate hallmarks of aging. Systemic aging leads to the destruction of systemic hemostasis, causes the release of inflammatory cytokines, senescence-associated secretory phenotype (SASP), and the imbalance of microbiota composition. Released inflammatory factors further aggregate senescence, which promotes the aging of multiple solid organs. Targeting senescence or delaying aging is emerging as a critical health strategy for solving age-related diseases, especially in the old population. In the current review, we will delineate the mechanisms of organ crosstalk in systemic aging and age-related diseases to provide therapeutic targets for delaying aging.

Trans-ancestral rare variant association study with machine learning-based phenotyping for metabolic dysfunction-associated steatotic liver disease

BACKGROUND

Genome-wide association studies (GWAS) have identified common variants associated with metabolic dysfunction-associated steatotic liver disease (MASLD). However, rare coding variant studies have been limited by phenotyping challenges and small sample sizes. We test associations of rare and ultra-rare coding variants with proton density fat fraction (PDFF) and MASLD case-control status in 736,010 participants of diverse ancestries from the UK Biobank, All of Us, and BioMe and performed a trans-ancestral meta-analysis. We then developed models to accurately predict PDFF and MASLD status in the UK Biobank and tested associations with these predicted phenotypes to increase statistical power.

RESULTS

The trans-ancestral meta-analysis with PDFF and MASLD case-control status identifies two single variants and two gene-level associations in APOB, CDH5, MYCBP2, and XAB2. Association testing with predicted phenotypes, which replicates more known genetic variants from GWAS than true phenotypes, identifies 16 single variants and 11 gene-level associations implicating 23 additional genes. Two variants were polymorphic only among African ancestry participants and several associations showed significant heterogeneity in ancestry and sex-stratified analyses. In total, we identified 27 genes, of which 3 are monogenic causes of steatosis (APOB, G6PC1, PPARG), 4 were previously associated with MASLD (APOB, APOC3, INSR, PPARG), and 23 had supporting clinical, experimental, and/or genetic evidence.

CONCLUSIONS

Our results suggest that trans-ancestral association analyses can identify ancestry-specific rare and ultra-rare coding variants in MASLD pathogenesis. Furthermore, we demonstrate the utility of machine learning in genetic investigations of difficult-to-phenotype diseases in trans-ancestral biobanks.

Citrulline regulates macrophage metabolism and inflammation to counter aging in mice

Metabolic dysregulation and altered metabolite concentrations are widely recognized as key characteristics of aging. Comprehensive exploration of endogenous metabolites that drive aging remains insufficient. Here, we conducted an untargeted metabolomics analysis of aging mice, revealing citrulline as a consistently down-regulated metabolite associated with aging. Systematic investigations demonstrated that citrulline exhibited antiaging effects by reducing cellular senescence, protecting against DNA damage, preventing cell cycle arrest, modulating macrophage metabolism, and mitigating inflammaging. Long-term citrulline supplementation in aged mice yielded beneficial effects and ameliorated age-associated phenotypes. We further elucidated that citrulline acts as an endogenous metabolite antagonist to inflammation, suppressing proinflammatory responses in macrophages. Mechanistically, citrulline served as a potential inhibitor of mammalian target of rapamycin (mTOR) activation in macrophage and regulated the mTOR-hypoxia-inducible factor 1α-glycolysis signaling pathway to counter inflammation and aging. These findings underscore the significance of citrulline deficiency as a driver of aging, highlighting citrulline supplementation as a promising therapeutic intervention to counteract aging-related changes.

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.

Targeting senescent cells for the treatment of age-associated diseases

Cellular senescence, which entails cellular dysfunction and inflammatory factor release-the senescence-associated secretory phenotype (SASP)-is a key contributor to multiple disorders, diseases and the geriatric syndromes. Targeting senescent cells using senolytics has emerged as a promising therapeutic strategy for these conditions. Among senolytics, the combination of dasatinib and quercetin (D + Q) was the earliest and one of the most successful so far. D + Q delays, prevents, alleviates or treats multiple senescence-associated diseases and disorders with improvements in healthspan across various pre-clinical models. While early senolytic therapies have demonstrated promise, ongoing research is crucial to refine them and address such challenges as off-target effects. Recent advances in senolytics include new drugs and therapies that target senescent cells more effectively. The identification of senescence-associated antigens-cell surface molecules on senescent cells-pointed to another promising means for developing novel therapies and identifying biomarkers of senescent cell abundance.

Immune surveillance of senescence: potential application to age-related diseases

Several lines of evidence suggest that the age-dependent accumulation of senescent cells leads to chronic tissue microinflammation, which in turn contributes to age-related pathologies. In general, senescent cells can be eliminated by the host's innate and adaptive immune surveillance system, including macrophages, NK cells, and T cells. Impaired immune surveillance leads to the accumulation of senescent cells and accelerates the aging process. Recently, senescent cells, like cancer cells, have been shown to express certain types of immune checkpoint proteins as well as non-classical immune-tolerant MHC variants, leading to immune escape from surveillance systems. Thus, immune checkpoint blockade (ICB) may be a promising strategy to enhance immune surveillance of senescence, leading to the amelioration of some age-related diseases and tissue dysfunction.

A BCL-xL/BCL-2 PROTAC effectively clears senescent cells in the liver and reduces MASH-driven hepatocellular carcinoma in mice

Accumulation of senescent cells (SnCs) plays a causative role in many age-related diseases and has also been implicated in the pathogenesis and progression of metabolic dysfunction-associated steatotic liver disease (MASLD). Senolytics that can selectively kill SnCs have the potential to be developed as therapeutics for these diseases. Here we report the finding that 753b, a dual BCL-xL/BCL-2 proteolysis-targeting chimera (PROTAC), acts as a potent and liver-tropic senolytic. We found that treatment with 753b selectively reduced SnCs in the liver in aged mice and STAM mice in part due to its sequestration in the liver. Moreover, 753b treatment could effectively reduce the progression of MASLD and the development of hepatocellular carcinoma (HCC) in STAM mice even after the mice developed substantial metabolic dysfunction-associated steatohepatitis (MASH) and hepatic fibrosis. These findings suggest that BCL-xL/BCL-2 PROTACs have the potential to be developed as therapeutics for MASLD to reduce MASH-driven HCC.

Restoration of angiogenic capacity in senescent endothelial cells by a pharmacological reprogramming approach

Senescent endothelial cells (EC) are key players in the pathophysiology of cardiovascular diseases and are characterized by a reduced angiogenic and regenerative potential. Therefore, targeting these cells has been suggested as an effective therapeutic strategy to reduce vascular disease burden and potentially improve health and lifespan of humans. Here, we aimed to establish a pharmacological, partial reprogramming strategy to improve replicative senescent endothelial cell function in the context of angiogenesis. We demonstrate that our treatment improves tube formation and sprouting capacity but also increases proliferation and migration capacity in vitro. Further, inflammation and DNA damage were reduced in the replicative senescent cells. These processes were initiated by a short and timely-restricted overexpression of the Yamanaka-factors induced by our pharmacological strategy. The advantage of these compounds is that they are FDA approved in their respective concentrations which could pave the way for use in a clinical setting.

Risk factor analysis and predictive model construction of lean MAFLD: a cross-sectional study of a health check-up population in China

AIM

Cardiovascular disease morbidity and mortality rates are high in patients with metabolic dysfunction-associated fatty liver disease (MAFLD). The objective of this study was to analyze the risk factors and differences between lean MAFLD and overweight MAFLD, and establish and validate a nomogram model for predicting lean MAFLD.

METHODS

This retrospective cross-sectional study included 4363 participants who underwent annual health checkup at Yuyao from 2019 to 2022. The study population was stratified into three groups: non-MAFLD, lean MAFLD (defined as the presence of fatty liver changes as determined by ultrasound in individuals with a BMI < 25 kg/m2), and overweight MAFLD (BMI ≥ 25.0 kg/m2). Subsequent modeling analysis was conducted in a population that included healthy subjects with < 25 kg/m2 (n = 2104) and subjects with lean MAFLD (n = 849). The study population was randomly split (7:3 ratio) to a training vs. a validation cohort. Risk factors for lean MAFLD was identify by multivariate regression of the training cohort, and used to construct a nomogram to estimate the probability of lean MAFLD. Model performance was examined using the receiver operating characteristic (ROC) curve analysis and k-fold cross-validation (k = 5). Decision curve analysis (DCA) was applied to evaluate the clinical usefulness of the prediction model.

RESULTS

The multivariate regression analysis indicated that the triglycerides and glucose index (TyG) was the most significant risk factor for lean MAFLD (OR: 4.03, 95% CI 2.806-5.786). The restricted cubic spline curves (RCS) regression model demonstrated that the relationships between systolic pressure (SBP), alanine aminotransferase (ALT), serum urate (UA), total cholesterol (TCHO), triglyceride (TG), triglyceride glucose (TyG) index, high density lipoprotein cholesterol (HDLC), and MAFLD were nonlinear and the cutoff values for lean MAFLD and overweight MAFLD were different. The nomogram was constructed based on seven predictors: glycosylated hemoglobin A1c (HbA1c), serum ferritin (SF), ALT, UA, BMI, TyG index, and age. In the validation cohort, the area under the ROC curve was 0.866 (95% CI 0.842-0.891), with 83.8% sensitivity and 76.6% specificity at the optimal cutoff. The PPV and NPV was 63.3% and 90.8%, respectively. Furthermore, we used fivefold cross-validation and the average area under the ROC curve was 0.866 (Figure S3). The calibration curves for the model's predictions and the actual outcomes were in good agreement. The DCA findings demonstrated that the nomogram model was clinically useful throughout a broad threshold probability range.

CONCLUSIONS

Lean and overweight MAFLD exhibit distinct metabolic profiles. The nomogram model developed in this study is designed to assist clinicians in the early identification of high-risk individuals with lean MAFLD, including those with a normal BMI but at metabolic risk, as well as those with abnormal blood lipid, glucose, uric acid or transaminase levels. In addition, this model enhances screening efforts in communities and medical screening centers, ultimately ensuring more timely and effective medical services for patients.

In vivo expansion of gene-targeted hepatocytes through transient inhibition of an essential gene

Homology-directed repair (HDR)-based genome editing is an approach that could permanently correct a broad range of genetic diseases. However, its utility is limited by inefficient and imprecise DNA repair mechanisms in terminally differentiated tissues. Here, we tested Repair Drive, a platform technology for selectively expanding HDR-corrected hepatocytes in adult mice in vivo. Repair Drive involves transient conditioning of the liver by knocking down an essential gene, fumarylacetoacetate hydrolase (Fah), and delivering an untargetable version of the essential gene in cis with a therapeutic transgene. We show that Repair Drive increased the percentage of correctly targeted hepatocytes in healthy wild-type mice up to 25%, which resulted in a fivefold increased expression of a therapeutic transgene, human factor IX (FIX). Repair Drive was well tolerated and did not induce toxicity or tumorigenesis during a 1-year follow-up. This approach may broaden the range of liver diseases that can be treated with somatic genome editing.

Ovarian Aging: The Silent Catalyst of Age-Related Disorders in Female Body

Age-related diseases have emerged as a global concern as the population ages. Consequently, understanding the underlying causes of aging and exploring potential anti-aging interventions is imperative. In females, the ovaries serve as the principal organs responsible for ovulation and the production of female hormones. The aging ovaries are related to infertility, menopause, and associated menopausal syndromes, with menopause representing the culmination of ovarian aging. Current evidence indicates that ovarian aging may contribute to dysfunction across multiple organ systems, including, but not limited to, cognitive impairment, osteoporosis, and cardiovascular disease. Nevertheless, due to the widespread distribution of sex hormone receptors throughout the body, ovarian aging affects not only these specific organs but also influences a broader spectrum of age-related diseases in women. Despite this, the impact of ovarian aging on overall age-related diseases has been largely neglected. This review provides a thorough summary of the impact of ovarian aging on age-related diseases, encompassing the nervous, circulatory, locomotor, urinary, digestive, respiratory, and endocrine systems. Additionally, we have outlined prospective therapeutic approaches for addressing both ovarian aging and age-related diseases, with the aim of mitigating their impacts and preserving women's fertility, physical health, and psychological well-being.

Molecular mechanisms in liver repair and regeneration: from physiology to therapeutics

Liver repair and regeneration are crucial physiological responses to hepatic injury and are orchestrated through intricate cellular and molecular networks. This review systematically delineates advancements in the field, emphasizing the essential roles played by diverse liver cell types. Their coordinated actions, supported by complex crosstalk within the liver microenvironment, are pivotal to enhancing regenerative outcomes. Recent molecular investigations have elucidated key signaling pathways involved in liver injury and regeneration. Viewed through the lens of metabolic reprogramming, these pathways highlight how shifts in glucose, lipid, and amino acid metabolism support the cellular functions essential for liver repair and regeneration. An analysis of regenerative variability across pathological states reveals how disease conditions influence these dynamics, guiding the development of novel therapeutic strategies and advanced techniques to enhance liver repair and regeneration. Bridging laboratory findings with practical applications, recent clinical trials highlight the potential of optimizing liver regeneration strategies. These trials offer valuable insights into the effectiveness of novel therapies and underscore significant progress in translational research. In conclusion, this review intricately links molecular insights to therapeutic frontiers, systematically charting the trajectory from fundamental physiological mechanisms to innovative clinical applications in liver repair and regeneration.

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.

Therapeutic potential of nicotinamide and ABT263 in alcohol-associated liver disease through targeting cellular senescence

Alcohol-associated liver disease (ALD) is a major cause of liver-related morbidity and mortality, yet clinically effective therapies for ALD remain lacking. Here, we demonstrate that alcohol intake and its metabolite, acetaldehyde (ACH), induce senescence in the liver and liver cells, respectively. To assess the therapeutic potential of targeting liver senescence in ALD, we treated ALD-affected mice with the senolytic compound ABT263 and the senomorphic NAD+ precursor, nicotinamide (NAM). The results show that ABT263 effectively clears senescent hepatocytes and stellate cells, and reduces liver triglyceride (TG), but increases plasma alanine aminotransferase and TG levels. Conversely, NAM efficiently suppresses senescence and the senescence-associated secretory phenotype (SASP), protecting the liver from alcohol-induced injury in ALD mice. RNA-sequencing analysis revealed that ABT263 treatment downregulated genes involved in adipogenesis while activating the complement pathway. In contrast, NAM upregulated metabolism-related genes, such as Sirt1, and downregulated DNA damage marker genes, including Rec8 and E2f1, in the liver. These findings suggest that cellular senescence plays a critical role in alcohol-induced liver injury. Compared with senescent cell clearance by ABT263, suppressing senescence and SASP by NAM may provide a safer and more effective therapeutic approach for ALD.

Liver-specific actions of GH and IGF1 that protect against MASLD

Metabolic dysfunction-associated steatotic liver disease (MASLD; also known as nonalcoholic fatty liver disease) is a chronic condition associated with metabolic syndrome, a group of conditions that includes obesity, insulin resistance, hyperlipidaemia and cardiovascular disease. Primary growth hormone (GH) deficiency is associated with MASLD, and the decline in circulating levels of GH with weight gain might contribute to the development of MASLD. Raising endogenous GH secretion or administering GH replacement therapy in the context of MASLD enhances insulin-like growth factor 1 (IGF1) production and reduces steatosis and the severity of liver injury. GH and IGF1 indirectly control MASLD progression by regulating systemic metabolic function. Evidence supports the proposal that GH and IGF1 also have a direct role in regulating liver metabolism and health. This Review focuses on how GH acts on the hepatocyte in a sex-dependent manner to limit lipid accumulation, reduce stress, and promote survival and regeneration. In addition, we discuss how GH and IGF1 might regulate non-parenchymal cells of the liver to control inflammation and fibrosis, which have a major effect on hepatocyte survival and regeneration. Development of a better understanding of how GH and IGF1 coordinate the functions of specific, individual liver cell types might provide insight into the aetiology of MASLD initiation and progression and suggest novel approaches for the treatment of MASLD.

Chronic environmental exposure to polystyrene microplastics increases the risk of nonalcoholic fatty liver disease

Microplastics (MPs), as the crucial environmental pollutants, can be easily transported into the human body and accumulate in the liver. However, current studies mainly focus on acute exposure to MPs, investigations on long-term interactions with MPs alone remain limited. Thereby, we examined noxious properties of MPs and selected the most common polystyrene (PS) MPs as the research object, including unmodified PS MPs (PS-MPs) and positive-charged PS MPs (PS-NH2) at 10 mg/L employing oral drinking water methods in mice for six consecutive months in vivo. In vitro, we treated the human hepatocyte cells with MPs at 25 μg/mL to explore involved mechanisms. The results revealed that six-month MPs exposure led to nonalcoholic fatty liver disease (NAFLD) including impaired liver functions, extensive lipid depositions accompanied by abnormal levels of metabolic genes and PS-NH2 MPs exerted a stronger effect than PS-MPs. Concurrently, mice treated with MPs revealed the accumulation of senescent hepatocytes, leading to increased secretions of senescent phenotypes in the liver. We also discovered that MPs initiated the HO-1/Nrf2 axis consequently inducing ferroptosis in vivo and in vitro, as shown by massive iron deposition, extensive lipid peroxidation along with significant protein expressions in ferroptosis-related markers. Additionally, targeting the HO-1/Nrf2 pathway to further alleviate ferroptosis with corresponding inhibitors could efficiently alleviate cell senescence. Therefore, our study reveals new evidence of the relationship between chronic exposure to MPs and NAFLD and furthers the understanding of how plastic pollution affects human health.

Icariin maintaining TMEM119-positive microglial population improves hippocampus-associated memory in senescent mice in relation to R-3-hydroxybutyric acid metabolism

ETHNOPHARMACOLOGICAL RELEVANCE

Epimedium Tourn. ex L. is a traditional Chinese medicine used for thousands of years in China to treat forgetfulness. Icariin is a principal component of the genus Epimedium.

AIM OF THE STUDY

The metabolic mechanism of icariin treating forgetfulness is explored.

MATERIALS AND METHODS

A D-galactose-induced senescent mouse model was employed. The cognitive performance of mice was assessed in the fear conditioning test. Hippocampal pathology was assessed in the immunohistochemistry assay. Plasma metabolome was analyzed using GC-MS method, and the differential metabolites were further identified by UPLC-MS/MS or GC-MS method. The liver function, including ALT and AST, was assessed by enzyme reaction. Icariin was administered intraperitoneally at 50 and 100 mg/kg. Mice were administered five consecutive days per week for 8 weeks.

RESULTS

Icariin treatment improved hippocampus-related fear memory but not amygdala-related memory, whereas Pexidartinib (PLX3397), a microglial scavenger, did not. Icariin treatment maintained the TMEM119-positive microglial population and decreased the accumulation of the senescent biomarker p16 in the dorsal hippocampus in senescent mouse brains, whereas PLX3397 did not. Notably, p16 in the CA2 subregion significantly decreased in icariin-treated mice than the other hippocampal subregions. The senescent mice exhibited the circulating metabolic characteristics of mild ketoacidosis, active tricarboxylic acid (TCA) cycle, lactic acidosis, hyperglycemia, active detoxification, active cis-oleic acid metabolism, and inhibitory GABA shut. R-3-Hydroxybutyric acid primarily produced in the liver was selectively and robustly decreased by icariin treatment, which was not observed with PLX3397 treatment. The TCA cycle was rescued in senescent mice by icariin treatment. Icariin also protected liver function (plasma ALT) in D-gal-induced senescent mice.

CONCLUSIONS

Icariin may protect mouse hippocampal cognition from D-gal-induced senescence by protecting microglial homeostasis, and facilitating the utilization of R-3-hydroxybutyric acid is one of the underpins.