Longevity Papers

Excess cellular senescence contributes to age-related increases in frailty and reductions in skeletal muscle strength. In the present study, we determined the efficacy of oral intermittent treatment (1 week on-2 weeks off-1 week on) with the natural flavonoid senolytic fisetin to improve frailty and grip strength in old mice. Further, the effects of fisetin on physical function were evaluated in young mice. We performed bulk RNA sequencing of quadricep skeletal muscle to determine the cell senescence-related signaling pathways modulated by fisetin. We also assessed the relative effects of fisetin on frailty and grip strength with aging in comparison with two other well-established approaches for the removal of senescent cells: (1) genetic-based clearance of excess senescent cells in old p16-3MR mice, a model that allows for clearance of p16-positive (p16+) senescent cells, and (2) oral intermittent treatment with the synthetic pharmacological senolytic ABT-263 in old mice. We found that fisetin mitigated the adverse changes in frailty and grip strength with aging. Fisetin had no effects in young mice. The improvements in frailty and grip strength in old mice were accompanied by favorable modulation of the skeletal muscle transcriptome, including lower abundance of cellular senescence-related genes (e.g., Cdkn1a and Ddit4). Improvements in frailty and grip strength with fisetin were comparable to those observed with genetic-based clearance of excess p16+ senescent cells and treatment with ABT-263. Taken together, our findings provide proof-of-concept support for fisetin as a senolytic strategy to improve physical function with aging.

Suppression of the insulin-IGF-mTORC1-Ras network ameliorates aging in animals. Many drugs have targets in the network because of its roles in cancer and metabolic disease and are candidates for repurposing as geroprotectors. Rapamycin, an established geroprotective drug, blocks mTORC1 signaling, and trametinib inhibits the Ras-MEK-ERK pathway. In this study, we assessed survival and health of male and female mice treated with trametinib, rapamycin or their combination. We show here that trametinib treatment extended lifespan in both sexes and that its combination with rapamycin was additive. Combination treatment reduced liver tumors in both sexes and spleen tumors in male mice, blocked the age-related increase in brain glucose uptake and strongly reduced inflammation in brain, kidney, spleen and muscle and circulating levels of pro-inflammatory cytokines. We conclude that trametinib is a geroprotector in mice and that its combination with rapamycin is more effective than either drug alone, making the combination a candidate for repurposing as a gerotherapy in humans.

The rising global demographic aging and the subsequent increase in the prevalence of age-related diseases highlight the need to understand aging biology. A key player in organismal aging is the immune system, which has broad systemic effects. On the one hand, immune aging involves the decline of hematopoietic stem cells and significant alterations in the functionality and composition of both innate and adaptive immunity. On the other hand, the aged immune system contributes to chronic inflammation and disrupted tissue homeostasis, thereby driving systemic aging processes. In this review, we examine the close interaction between aging and the immune system and discuss emerging therapeutic strategies aimed at modulating immune function to mitigate age-related pathologies.

Cellular senescence represents a stable cell cycle arrest state that plays critical roles in tissue aging and age-related pathologies. While single-cell RNA sequencing (scRNA-seq) has enabled comprehensive profiling of millions of cells in aged tissues, reliable identification of senescent cells remains challenging due to the weak and non-specific expression of marker genes. Although existing computational methods could be used to detect active cell states through gene set scoring approaches, their performance with senescence genes has not been rigorously assessed. In this study, we showed that senescence genes display weak, non-specific expression patterns across different tissues and are susceptible to dropout events in scRNA-seq. Current scoring approaches suffered intrinsic limitations in single-cell detection using weakly expressed markers. Simply expanding the gene set of weak markers failed to improve detection accuracy. To overcome these limitations, we developed ICE (Iterative-imputation-based Cell Enrichment), a computational framework that combines expression imputation with iterative marker refinement. ICE achieved a remarkable improvement in detection precision when analyzing pancreatic cells with weakly expressed markers, by increasing accuracy from 56% to 98%. Applied to senescence markers (CDKN1A/p21, CDKN2A/p16, ATF3, and MX1), ICE successfully identified marker-specific cell populations, including stressed {beta} cells in aging and type-I interferon-responsive microglia in Alzheimer\'s disease (AD). Together, our study offered a rigorous analytical framework for single cell detection using markers with weak expressions, which will facilitate in-depth exploration of senescence heterogeneity and temporal dynamics in human tissue and disease states.

Necrosis is uncontrolled cell death that marks the irreversible threshold of biological degeneration. Rooted in the Greek nekros (death), it is a pivotal mechanism underlying numerous diseases, including cancer, as well as renal, cardiac, neuronal, and hepatic disorders, and more broadly, the aging process. Despite its profound impact on morbidity and mortality, necrosis remains untreatable and has long been viewed as a chaotic, unavoidable aspect of biology. This review examines the mechanisms of necrosis and outlines its far-reaching impact on health, as revealed by emerging evidence. Furthermore, we explore its potential as a game-changing therapeutic target. Inhibiting necrosis could revolutionize treatments for acute and chronic age-related conditions like cancer, kidney disease, cardiovascular disease (including heart attacks and strokes), and neurodegeneration, while also preserving resilience-and even slowing aging itself. Beyond Earth, where microgravity, cosmic radiation, and oxidative stress accelerate cellular decline, targeting necrosis may also hold the key to preserving astronaut resilience and health on long-duration space missions, offering insights that could reshape human longevity both on and off the planet.

Degeneration of the auditory and vestibular hair cells (HCs) leads to dysfunction of two essential senses: hearing loss and decompensated balance perception. However, the cellular and molecular mechanisms governing inner ear aging and its link to dysfunctions of sensory HCs remain unclear. Here, we constructed an aging-associated cell atlas of cochlear and utricular tissues in C57BL/6J mice through single-nucleus RNA sequencing, revealing transcriptionally distinct hair cell subtypes and spatially restricted molecular markers that delineate specific cellular populations. We uncovered activation of macrophages and shaped inflamed niches in the aged inner ear. Furthermore, we demonstrated the cell type-specific signatures of aging between the two organs, with focused characterization in six HC subtypes uncovering core mechanisms like dysregulated RNA splicing underlying degeneration. Crucially, suppressing RNA splicing factor Rbm25 abolished inflammation-induced HC deterioration. Our study reveals complex, multifactorial mechanisms that underlie inner ear aging and offer potential targets for preventing HC degeneration.

One of the strongest signatures of aging is an accumulation of mutant mitochondrial DNA (mtDNA) heteroplasmy. Here we investigate the mechanism underlying this phenomenon by calling mtDNA sequence, abundance, and heteroplasmic variation in human blood using whole genome sequences from ~750,000 individuals. Our analyses reveal a simple, two-step mechanism: first, individual cells randomly accumulate low levels of \"cryptic\" mtDNA mutations; then, when a cell clone proliferates, the cryptic mtDNA variants are carried as passenger mutations and become detectable in whole blood. Four lines of evidence support this model: (1) the mutational spectrum of age-accumulating mtDNA variants is consistent with a well-established model of mtDNA replication errors, (2) these mutations are found primarily at low levels of heteroplasmy and do not show evidence of positive selection, (3) high mtDNA mutation burden tends to co-occur in samples harboring somatic driver mutations for clonal hematopoiesis (CH), and (4) nuclear GWAS reveals that germline variants predisposing to CH (such as those near TERT, TCL1A, and SMC4) also increase mtDNA mutation burden. We propose that the high copy number and high mutation rate of mtDNA make it a particularly sensitive blood-based marker of CH. Importantly, our work helps to mechanistically unify three prominent signatures of aging: common germline variants in TERT, clonal hematopoiesis, and observed mtDNA mutation accrual.

While memory regulation is predominantly understood as autonomous to neurons, factors outside the brain can also affect neuronal function. In Caenorhabditis elegans, the insulin/IGF-1-like signaling (IIS) pathway regulates longevity, metabolism and memory: long-lived daf-2 insulin/IGF-1 receptor mutants more than double memory duration after a single training session, and it was assumed that memory regulation was strictly neuronal. However, here we show that degradation of DAF-2 in the hypodermis also greatly extends memory, via expression of the diffusible Notch ligand, OSM-11, which in turn activates Notch signaling in neurons. Single-nucleus RNA sequencing of neurons revealed increased expression of CREB and other memory genes. Furthermore, in aged animals, activation of the hypodermal IIS-Notch pathway as well as OSM-11 overexpression rescue both memory and learning via CREB activity. Thus, insulin signaling in the liver-like hypodermis non-autonomously regulates neuronal function, providing a systemic connection between metabolism and memory through IIS-Notch-CREB signaling from the body to the brain.

Polyamines are abundant and evolutionarily conserved metabolites that are essential for life. Dietary polyamine supplementation extends life-span and health-span. Dysregulation of polyamine homeostasis is linked to Parkinson's disease and cancer, driving interest in therapeutically targeting this pathway. However, measuring cellular polyamine levels, which vary across cell types and states, remains challenging. We introduce a genetically encoded polyamine reporter for real-time measurement of polyamine concentrations in single living cells. This reporter utilizes the polyamine-responsive ribosomal frameshift motif from the OAZ1 gene. We demonstrate broad applicability of this approach and reveal dynamic changes in polyamine levels in response to genetic and pharmacological perturbations. Using this reporter, we conduct a genome-wide CRISPR screen and uncover an unexpected link between mitochondrial respiration and polyamine import, which are both risk factors for Parkinson's disease. By offering a lens to examine polyamine biology, this reporter may advance our understanding of these ubiquitous metabolites and accelerate therapy development.

During tissue repair, stress-induced cellular senescence represents a critical factor that impedes the regenerative potential of tissues. While the regulatory effects of matrix viscoelasticity on cellular behavior have been documented, their role and correlated mechanisms underlying cellular senescence remain unclear. In this study, we engineered a viscoelastic gel matrix exhibiting a storage modulus of approximately 3 kPa, with a tunable loss modulus ranging from 0 to 300 Pa by incorporating linear alginate and modulating the compactness of a polyacrylamide-based covalent network. Utilizing a UV-induced senescence model, we observed that increasing the matrix's viscoelasticity from 0 Pa to 300 Pa led to a significant reduction in the proportion of senescent cells, from 90.5% to 22.7%. Furthermore, cells cultured in these matrices exhibited a tendency to form cell aggregation, with the cell populations demonstrating a collective resistance to stresses. This indicated that viscoelastic materials would promote enhanced cellular interactions, thereby strengthening cellular resilience against UV-induced stresses. Furthermore, combined with microarray analysis, it was concluded that the presence of viscoelastic components activated the connexin 43 (Cx43)-modulated gap junction for cluster formation, thereby suppressing the senescence-associated signaling pathways, including Wnt/β-catenin, MAPK, NF-κB, and TGF-β. Additionally, the integrin-cytoskeleton-Yes-associated protein (YAP) signaling axis played an active role in delaying cell aging. These results provide novel insights into the regulatory role of viscoelastic materials in cellular senescence and offer a compelling foundation for the development of advanced biomaterials for tissue repair.

Early life stresses impact reproductive outcomes in many organisms. In response to crowding and starvation, C. elegans nematodes form dauer larvae, in which development arrests until conditions improve. We discovered dramatic differences in gonad size and germ cell number among dauers that form under different conditions. We used live cell imaging of fluorescent markers in otherwise wild-type and mutant animals combined with food-removal, recovery, and brood-size assays to investigate the causes and consequences of this germline difference. Pre-dauer feeding, but not nutrient sensing via the DAF-2/insulin-like signaling receptor or DAF-7/TGF-{beta}, is required for plasticity in gonad size. Gonad differences in dauer have lifelong reproductive consequences; worms with small dauer gonads recover to have smaller broods. Somatic and germline development are decoupled as pre-dauer starvation induces germline quiescence while the soma continues its development until dauer is formed. A rapid return to germline Notch-dependence and an increase in presentation by the germline stem cell niche of the Notch ligand LAG-2--regulated at the protein and not transcript level--are among the earliest events of dauer recovery.

The transcription factors FOXO4 and p53 regulate aging, and their deregulation has been linked to several diseases, including cancer. Under stress conditions, cellular senescence is promoted by p53 sequestration and senescence-associated protein p21 transcriptional upregulation induced by interactions between the FOXO4 Forkhead DNA-binding domain and the p53 transactivation domain. However, the molecular details of these interactions remain unclear. Here, we report that these interactions between p53 and FOXO4 domains are highly heterogeneous. The p53 transactivation domain primarily interacts with the region formed by the N-terminal helical bundle of the FOXO4 Forkhead domain but retains a substantial degree of flexibility in the complex. In addition, NMR data-driven molecular simulations suggest that p53 interacts with FOXO4 through multiple binding modes. Overall, our findings not only provide the structural insights into interactions between FOXO4 and p53 but also highlight their potential as targets for developing senolytic compounds.

We conducted a randomized, placebo-controlled trial to assess the safety and biological age (BA) effects of various therapeutic plasma exchange (TPE) regimens in healthy adults over 50. Participants received bi-weekly TPE with or without intravenous immunoglobulin (IVIG), monthly TPE, or placebo. Randomization was based on entry date, and treatments were blinded to maintain objectivity. Primary objectives were to assess long-term TPE safety and changes in biological clocks. Secondary goals included identifying optimal regimens. Exploratory analyses profiled baseline clinical features and longitudinal changes across the epigenome, proteome, metabolome, glycome, immune cytokines, iAge, and immune cell composition. We demonstrate in 42 individuals randomized to various treatment arms or placebo that long-term TPE was found to be safe, with only two adverse events requiring discontinuation and one related to IVIG. TPE significantly improved biological age markers, with 15 epigenetic clocks showing rejuvenation compared to placebo (FDR < 0.05). Biweekly TPE combined with intravenous immunoglobulin (TPE-IVIG) proved most effective, inducing coordinated cellular and molecular responses, reversing age-related immune decline, and modulating proteins linked to chronic inflammation. Integrative analysis identified baseline biomarkers predictive of positive outcomes, suggesting TPE-IVIG is particularly beneficial for individuals with poorer initial health status. This is the first multi-omics study to examine various TPE modalities to slow epigenetic biologic clocks, which demonstrate biological age rejuvenation and the molecular features associated with this rejuvenation. Trial Registration: Registered trial NCT06534450 on clinicaltrials.gov under the purview of the Diagnostic Investigational Review Board.

Every heartbeat is initiated by a spontaneous electrical signal generated inside the cardiac pacemaker. The generation of this electrical signal depends on the coordinated opening and closing of different ion channels, where voltage-gated L-type calcium channels play a central role. Despite the reliability of the pacemaker, all mammals experience a linear slowdown of the pacemaker rate with age. In humans, this slowing can become pathological and constitutes the main cause for the requirement of the implantation of artificial pacemakers. However, the mechanisms behind the age-associated slowdown of the pacemaker are not well understood. Here, we show that age alters L-type calcium channels in pacemaker cells from mice. The age-associated alterations include: i) a reduction in the density of the channels at the plasma membrane, ii) a reduction in the clustering of the channels, and iii) a decrease in channel open probability. Altogether, these age-associated alterations result in a global reduction of the L-type calcium current density and in a slowdown of the pacemaker diastolic depolarization. Remarkably, increasing the open probability of L-type calcium channels pharmacologically was enough to restore pacemaker rate in old cells to the same levels observed in the young. Overall, our findings provide evidence that proper organization and function of L-type calcium channels is impaired by aging and that this dysfunction contributes to the slowdown of pacemaker cells in old animals.

Rationale: Higher levels of senescence have been demonstrated in COPD patients, including severe early onset (SEO)-COPD. Recently we demonstrated a link between senescence and extracellular matrix (ECM) dysregulation in lung fibroblasts. Whether this in vitro observation also translates in vivo has not been shown yet. Objectives: To determine whether senescence can contribute to COPD-associated ECM-related changes in lung tissue. Methods: Transcriptomics and proteomics analyses were performed on lung tissue from 60 COPD patients (including 18 SEO-COPD patients) and 32 controls. Expression levels of 471 ECM-related genes and proteins were compared between (SEO-)COPD and controls. Differentially expressed ECM-related genes and proteins were then correlated with six major senescence markers. ECM-senescence correlations were validated in primary human lung fibroblasts in vitro. Results: We identified 12 COPD- and 57 SEO-COPD-associated ECM-related genes and 4 COPD- and 9 SEO-COPD-associated ECM-related proteins. More than half (36 out of 68 unique genes) of the (SEO-)COPD-associated ECM-related proteins were significantly correlated with one or more senescence markers at transcript level, with the most and strongest correlations with p21 (26 genes). The correlation of 3 ECM-related genes with p21 was validated in primary lung fibroblasts cultured at baseline and ADAMTS1 was increased in senescence-induced lung fibroblasts. Conclusions: Many of the (SEO-)COPD-associated ECM-related changes in lung tissue were correlated with the senescence marker p21. As many of these ECM-related proteins are involved in ECM organization and include proteases, these results indicate a role for cellular senescence in disturbed ECM organization and protease-antiprotease imbalance in COPD.

Organ-specific aging clocks have shown promise as predictors of disease risk and aging trajectories; however, the underlying biological mechanisms they reflect remain largely unexplored. Here, we use large-scale proteomic and imaging data to investigate the relationships among organ-specific and modality-specific aging clocks and to uncover the biological processes they represent. By estimating paired protein-based and imaging-based aging clocks across 8 major organs, we demonstrate that these omics and structural profiles exhibit distinct phenotypic and genetic signatures, each potentially quantifying different stages and playing complementary roles within a unified biological aging process. Furthermore, context-specific aging clocks from multiple organs often converge and jointly capture established biological and disease pathways. For example, 65.7% of the KEGG Alzheimer's disease pathway is enriched by at least one of 11 protein- and imaging-based aging clocks, with each clock representing different components of the pathway. These results underscore the importance of a pan-organ multi-modal perspective for quantifying the mechanisms underlying age-related diseases. Additionally, we identify modality-specific links between aging clocks and complex diseases and lifestyle factors. In summary, we uncover intricate relationships among molecular and structural aging clocks across human organs, providing novel insights into their context-specific roles in capturing consequences of aging biology and their implications for disease risk.

Klotho, named after the youngest of the three Fates in Greek mythology daughters of Zeus and Nyx, who together spin the thread of life, allot destiny, and determine the time of passing for both mortals and immortals, is an important regulatory factor in aging and cancer dynamics. Initially described as an aging-suppressing protein, Klotho is now recognized for its more diverse role in modulating key signaling pathways like Wnt/β-catenin, IGF-1, PI3K/AKT, and TGF-β. Essentially, its various pro-cellular health functions, such as antioxidant, anti-inflammatory, and tumor-suppressive activities, are, in fact, considered that ensures the maintenance of cellular health and reduce complications related to aging. Klotho deficiency is associated with accelerated aging, chronic kidney disease, cardiovascular disorders, neurodegeneration, and various cancers. This review thus covers the twin roles of Klotho as an antiaging and tumor-suppressor protein, on their therapeutic potential, as well as advances in delivery systems and development of biomarkers and challenges for clinical translation.. Moreover, natural strategies like exercise and dietary interventions are explored that could help overcome Klotho deficiency. Further research with Klotho may offer a paradigm shift in the treatment of aging and cancer and add yet another avenue to increase survival of the patients.

Metformin, a medication primarily used to treat diabetes, has gained attentions for its potential antiaging properties. Although the metabolic and cellular pathways behind its longevity effects have been widely studied, few studies have explored the epigenetic regulatory effects of metformin, which are a crucial factor in aging processes. In this study, we examined the antiaging effects of metformin using the Brachionus rotifer as a model, focusing on the regulation of mRNA N6-methyladenosine (m6A), a key RNA modification involved in mRNA stability, translation, and splicing. We found metformin significantly extended the rotifers' lifespan, mimicking the effects of dietary restriction (DR), a well-established antiaging intervention. Both metformin and DR modulate m6A dynamics, with a notable reduction in the m6A modification of MTR (5-methyltetrahydrofolate-homocysteine methyltransferase). This reduction led to decreased MTR expression and lowered levels of S-adenosylmethionine (SAM), a critical metabolite in the one-carbon cycle. We propose that the downregulation of MTR through m6A modification limits methionine synthesis and imposes methionine restriction, a key factor in promoting longevity. Our findings reveal a novel epitranscriptional regulatory model by which metformin and DR modulate m6A to extend lifespan, highlighting MTR as a central regulator of aging and suggesting potential therapeutic strategies for healthy aging through m6A and methionine metabolism.

Vision decline in the elderly, often due to retinal aging, predisposes individuals to pathologies like age-related macular degeneration. Currently, there are few effective oral treatments for this condition. Our study introduces an oral agent, 8-aminoguanine (8-AG), which targets age-related retinal degeneration using an aged Fischer 344 rat model. When administered in drinking water at a low dose for 8 weeks starting at 22 months of age, 8-AG significantly preserves retinal structure and function, as evidenced by increased retinal thickness, enhanced photoreceptor integrity, and improved electroretinogram responses. 8-AG reduces apoptosis, oxidative damage, and microglial/macrophage activation in aging retinae. 8-AG also mitigates retinal inflammation at transcriptional and cytokine levels. Extending treatment to 17 weeks further amplifies these protective effects. Given its efficacy in various disease models, 8-AG shows great promise as an anti-aging compound with the potential to mitigate common hallmarks of aging.

'Brain age' is a biological clock typically used to describe brain health with one number, but its relationship with established gradients of cortical organization remains unclear. We address this gap by leveraging a data-driven, region-specific brain age approach in 335 neurologically intact adults, using a convolutional neural network (volBrain) to estimate regional brain ages directly from structural MRI without a predefined set of morphometric properties. Six distinct gradients of brain aging are replicated in two independent cohorts. Spatial patterns of accelerated brain aging in older adults quantitatively align with the archetypal sensorimotor-to-association axis of cortical organization. Other brain aging gradients reflect neurobiological hierarchies such as gene expression and externopyramidization. Participant-level correspondences to brain age gradients are associated with cognitive and sensorimotor performance and explained behavioral variance more effectively than global brain age. These results suggest that regional brain age patterns reflect fundamental principles of cortical organization and behavior.

The aging vasculature is characterized by endothelial dysfunction, arterial stiffness, and increased susceptibility to vascular pathologies. Central to these changes is the process of cellular senescence, where endothelial and vascular smooth muscle cells lose their replicative and functional capacity and adopt a pro-inflammatory secretory phenotype. This review provides an overview of the key mechanisms underlying vascular senescence, including the p53/p21 and p16/Rb pathways, the senescence-associated secretory phenotype (SASP), and oxidative stress, examines its contribution to cardiovascular diseases in older adults, and highlights emerging therapeutic strategies aimed at delaying or reversing these age-related vascular changes. In vascular cells, DNA damage, oxidative stress, and chronic inflammation associated with aging converge to amplify senescence. Clinically, vascular senescence is linked with hypertension, atherosclerosis, and increased overall cardiovascular risk. Several interventions, ranging from senolytics to lifestyle factors, show promise in mitigating these changes; however, long-term studies are needed. Given that vascular senescence is a pivotal driver of cardiovascular pathology in aging, targeting senescent cells or their secretory phenotype may potentially offer new avenues for preventing or attenuating age-related vascular diseases. This review presents an updated and integrative overview of vascular senescence, connecting fundamental cellular mechanisms with their clinical manifestations and highlighting the most promising therapeutic interventions.

The mitochondria (mt) and nucleus engage in a dynamic bidirectional communication to maintain cellular homeostasis, regulating energy production, stress response, and cell fate. Anterograde signaling directs mt function, while retrograde signaling conveys metabolic and stress-related changes from mt to the nucleus. Central to this crosstalk is mitochondrial DNA (mtDNA), which encodes key oxidative phosphorylation components. MtDNA integrity is preserved through quality control mechanisms, including fusion and fission dynamics, mitophagy, and nuclear-encoded DNA repair. Disruption in these pathways contributes to mt dysfunction, oxidative stress, and genetic instability-hallmarks of aging and diseases. Additionally, redox signaling and NAD+ homeostasis integrate mt and nuclear responses, modulating transcriptional programs that support mt biogenesis and stress adaptation. This review explores the molecular mechanisms coordinating mito-nuclear interactions, emphasizing their role in maintaining mtDNA integrity and cellular equilibrium. Understanding these processes provides insights into how mt dysfunction drives aging and disease, paving the way for targeted therapeutic strategies.