Longevity Papers

Dietary restriction (DR) robustly increases lifespan across taxa. However, in humans, long-term DR is difficult to maintain, leading to the search for compounds that regulate metabolism and increase lifespan without reducing caloric intake. The magnitude of lifespan extension from two such compounds, rapamycin and metformin, remains inconclusive, particularly in vertebrates. Here, we conducted a meta-analysis comparing lifespan extension conferred by rapamycin and metformin to DR-mediated lifespan extension across vertebrates. We assessed whether these effects were sex- and, when considering DR, treatment-specific. In total, we analysed 911 effect sizes from 167 papers covering eight different vertebrate species. We find that DR robustly extends lifespan across log-response means and medians and, importantly, rapamycin-but not metformin-produced a significant lifespan extension. We also observed no consistent effect of sex across all treatments and log-response measures. Furthermore, we found that the effect of DR was robust to differences in the type of DR methodology used. However, high heterogeneity and significant publication bias influenced results across all treatments. Additionally, results were sensitive to how lifespan was reported, although some consistent patterns still emerged. Overall, this study suggests that rapamycin and DR confer comparable lifespan extension across a broad range of vertebrates.

Aging biomarkers that predict age given methylomic data are referred to as epigenetic aging clocks. While the earliest, first-generation clocks were exclusively trained to predict chronological age, more recent next-generation models have been explicitly trained to associate with health, lifestyle, and/or age-related outcomes. Although these next-generation models have been trained using distinct approaches and techniques, existing evidence indicates that they associate with a greater number of health and disease signals than first-generation clocks. Moreover, they are often more predictive of age-related outcomes and appear more responsive to interventions. In this work, we provide definitions for first- versus next-generation clocks and discuss the potential merits of further dividing next-generation clocks into sub-categories. In addition, we summarize existing next-generation epigenetic aging clocks, including how they were trained and how they can be accessed. Given the relative value of interventional data over observational data, we comprehensively tabulate existing literature documenting the ability of an intervention to influence at least one epigenetic aging clock. While we acknowledge that the decision to a use a specific clock is ultimately dependent on the research application and goal, current evidence suggests that next-generation models should be generally prioritized for health-oriented association and interventional studies.

Cellular quiescence is a state of reversible proliferative arrest that plays essential roles in development, resistance to stress, aging, and longevity of organisms. Here we report that rapid depletion of RNase MRP, a deeply conserved RNA-based enzyme required for rRNA biosynthesis, induces a long-term yet reversible proliferative arrest in human cells. Severely compromised biogenesis of rRNAs along with acute transcriptional reprogramming precede a gradual decline of the critical cellular functions. Unexpectedly, many arresting cells show increased levels of histone mRNAs, which accumulate locally in the cytoplasm, and S-phase DNA amount. The ensuing proliferative arrest is entered from multiple stages of the cell cycle and can last for several weeks with uncompromised cell viability. Strikingly, restoring expression of RNase MRP leads to a complete reversal of the arrested state with resumed cell proliferation at the speed of control cells. We suggest that targeting rRNA biogenesis may provide a general strategy for rapid induction of a reversible proliferative arrest, with implications for understanding and manipulating cellular quiescence.

Older adults with established cardiovascular diseases (CVD) are at elevated risk of heart failure (HF). Frailty, a hallmark of multi-system aging, may contribute to HF development through inflammation. However, population-based evidence remains scarce. Leveraging data from 49,530 CVD patients in the UK Biobank, frailty was measured by five components: weight loss, exhaustion, low physical activity, slow walking speed, and low grip strength. We employed Cox regression models to assess the association between frailty and incident HF, and conducted mediation analyses to evaluate mediating roles of 15 inflammatory markers in this association. Furthermore, we constructed a polygenic risk score (PRS) for HF risk based on the Global Biobank Meta-analysis Initiative (N = 1,020,441), and evaluated the joint association and interaction between frailty and PRS in relation to incident HF. During a median follow-up of 13.3 years, 6293 participants developed HF. Compared to robust individuals, pre-frail (hazard ratio (HR) = 1.31 [95% CI: 1.23-1.40]) or frail (HR = 1.80 [1.64-1.98]) participants had a higher risk of HF, and the potential causality was suggested by Mendelian randomization. Such relationship was partially mediated by inflammatory markers, including interleukin-6, tumor necrosis factor-α, and C-reactive protein. Moreover, individuals with both frailty and high PRS had the greatest risk of HF (HR = 4.35 [3.74-5.06]), with a relative excess risk due to interaction of 1.39, accounting for 32% of total risk. Frailty interacts with PRS to enhance risk stratification of HF. Inflammation may mediate the frailty-HF association, suggesting the potential of anti-inflammatory interventions to mitigate HF risk in frail CVD patients.

Measurement of aging is critical to understanding its causes and developing interventions, but little consensus exists on what components such measurements should include or how they perform in predicting mortality. The aim of this study was to identify factors of aging among a comprehensive set of indicators, and to evaluate their relative performance in predicting mortality. Measurements on 34 clinical, survey, and neuroimaging variables, along with epigenetic age markers, were obtained from two waves (2004-2021) of the Midlife in the United States (MIDUS) study. Mortality data was also available on 11875 participants, including 1908 twins. Factor analyses were used to identify aging factors, and these were used to predict mortality as of 2022. Twin data were used to model predictors of mortality within families. Factor analyses identified 9 major dimensions of aging: frailty, cognition, adiposity, glucose, blood pressure, inflammation, lipids, adaptive functioning, and neurological functioning. The strongest predictors of survival among the aging dimensions were cognition, adaptive functioning, and inflammation, and among the epigenetic markers, the decline-predictive markers (GrimAge and DunedinPACE). When entered in joint prediction models, cognition remained a significant predictor of mortality, but the epigenetic markers did not. Cognition, adaptive functioning, and inflammation remained significant predictors of mortality within twin pairs as well. Aging is a multidimensional construct, with cognition, adaptive functioning, and inflammation being the strongest predictors of survival among the aging dimensions examined. Their association with mortality is observed within families, suggesting that early developmental factors cannot entirely account for their association with survival. Interventions and assessments should prioritize cognition in measures of aging quality, along with adaptive functioning and inflammation.

Mutations in mitochondrial complex I can cause severe metabolic disease. Although no treatments are available for complex I deficiencies, chronic hypoxia improves lifespan and function in a mouse model of the severe mitochondrial disease Leigh syndrome caused by mutation of complex I subunit NDUFS4. To understand the molecular mechanism of NDUFS4 mutant pathophysiology and hypoxia rescue, we investigated the structure of complex I in respiratory supercomplexes isolated from NDUFS4 mutant mice. We identified complex I assembly intermediates bound to complex III2, proving the cooperative assembly model. Further, an accumulated complex I intermediate is structurally consistent with pathological oxygen-dependent reverse electron transfer, revealing unanticipated pathophysiology and hypoxia rescue mechanisms. Thus, the build-up of toxic intermediates and not simply decreases in complex I levels underlie mitochondrial disease.

Epigenetic regulatory mechanisms, which include histone modifications and DNA methylation, play a central role in development and aging. Dimethylation of H3K36, deposited mainly by the histone methyltransferase NSD1, occurs predominantly in intergenic regions and recruits the DNA methyltransferase DNMT3A to facilitate DNA methylation. Haploinsufficiency of NSD1 results in the overgrowth disorder Sotos syndrome in vivo, which is associated with aberrant DNA methylation signatures and an enhanced epigenetic age. To understand the mechanisms by which NSD1 may regulate development, differentiation and diseases, we generated human iPSC lines deficient in functional NSD1 (NSD1-KO). NSD1-KO cells exhibit a substrate-specific decrease in proliferation, reduced H3K36me2 levels and extensive DNA hypomethylation. Notably, the loss of functional NSD1 altered the differentiation potential of iPSCs, with aberrant endodermal and mesodermal lineage commitment. Further analysis revealed that NSD1 might drive endodermal differentiation by regulating the expression of an endodermal lncRNA HIDEN by mechanisms independent of the regulation of DNA methylation. Our NSD1-KO iPSC lines partially recapitulate the DNA methylation defects associated with NSD1-related disorders. Additionally, we uncovered a novel mechanism by which NSD1 may regulate endodermal differentiation of human iPSCs.

Accumulating evidence indicates that biological aging can be accelerated by environmental exposures, collectively called the 'exposome'. The skin, as the largest and most exposed organ, can be viewed as a 'window' for the deep exploration of the exposome and its effects on systemic aging. The complex interplay across hallmarks of aging in the skin and systemic biological aging suggests that physiological processes associated with skin aging influence, and are influenced by, systemic hallmarks of aging. This bidirectional relationship provides potential avenues for the prevention of accelerated biological aging and the identification of therapeutic targets. We provide a review of the interactions between skin exposure, aging hallmarks in the skin and associated systemic changes, and their implications in treatment and disease. We also discuss key questions that need to be addressed to maintain skin and overall health, highlighting the need for the development of precise biomarkers and advanced skin models.

The ability of biomolecular condensates to reversibly dissolve and reform is crucial for maintaining cellular stability and functions. In the context of cell physiology and disease, they can serve as a metastable phase mediating the liquid-to-solid transition of disease proteins or rapidly assemble/disassemble as a mechanism for stress response. However, as metabolic rates decline with aging, the protein-rich condensates persist longer, therefore increasing the propensity of undergoing irreversible liquid-to-solid transitions. Temperature, as a physical stimulus, plays a key role in controlling the condensate formation, dissolution, and material properties. In this study, we explore how the reversibility of short peptide biomolecular condensates (z-FF) can be modulated by a temperature change. Our findings reveal that aged condensates exhibit reduced responsiveness to external temperature stimuli. By using thermal cycling experiments to simulate repeated heat stress, we found that the time taken for irreversible fiber formation could be delayed up to 4.7-fold compared to that of condensates without thermal cycles. We also found that the dissolution rate of condensates progressively slows as they age but remains more stable with thermal cycles. Importantly, our results indicate that continuous cycles of liquid-liquid phase separation and dissolution act as a reset mechanism, preserving the biomolecular condensates from further liquid-to-solid transition. These findings provide valuable insights into how aging impacts condensate behavior and highlight potential strategies to preserve cellular function through controlled phase transitions.

Cellular senescence is a stable form of cell cycle arrest that contributes to aging and age-associated diseases through the secretion of inflammatory factors collectively known as the senescence-associated secretory phenotype (SASP). While senescence is driven by transcriptional and epigenetic changes, the contribution of higher-order genome organization remains poorly defined. Here, we present the highest-resolution Hi-C maps (~3 kb) to date of proliferating, quiescent, and replicative senescent (RS) human fibroblasts, enabling a comprehensive analysis of 3D genome architecture during senescence. Our analyses reveal widespread senescence-associated remodeling of chromatin architecture, including extensive compartment and subcompartment switching toward transcriptionally active states, and a dramatic increase in unique chromatin loops. These structural features correlate with local DNA hypomethylation and are largely independent of canonical CTCF binding. The altered 3D genome landscape supports expression of SASP genes, inflammation-related pathways, and neuronal gene signatures consistent with age-associated epigenetic drift. We further demonstrate that architectural changes at multiple levels, including compartments, subcompartments, and loops, facilitate the derepression of LINE-1 retrotransposons, linking 3D chromatin structure to activation of proinflammatory transposable elements. Interestingly, quiescent cells, commonly used as senescence controls, exhibited substantial overlap in inflammatory gene expression with senescent cells, raising important considerations for experimental design. Structural analysis of cell cycle genes showed distinct chromatin configurations in senescence versus quiescence, despite similar transcriptional repression. Together, our results establish a high-resolution framework for understanding how genome architecture contributes to the senescent state.

Alterations in biological rhythms are a common feature of aging, and disruption of circadian rhythms can exacerbate age-associated pathologies. The retina is critical for detecting light for both vision and for transmitting time-of-day information to the brain, synchronizing rhythms throughout the body. Disruption of circadian rhythms by manipulating the molecular clock leads to premature retinal degeneration in flies and mice, and gene expression rhythms are disrupted in models of age-associated ocular disease. Despite this, it is unknown how or why the gene expression rhythms of the retina change with age. Here, we show that ~70% of the Drosophila transcriptome is rhythmically expressed throughout the diurnal cycle, with ~40% of genes showing altered rhythms with age. These transcriptome-wide changes in aging photoreceptors are accompanied by shifts in the rhythmic patterns of RNA Polymerase II (Pol II) occupancy, histone H3 lysine 4 (H3K4) methylation, and chromatin accessibility, without major changes in occupancy of the circadian clock transcription factors Clock (Clk) and Cycle (Cyc). Instead, aging decreases genome-wide levels of several different histone methyl marks including H3K4 methylation, whose relative levels across the day correlate with the phase of rhythmic gene expression. Moreover, individual knockdown of the three H3K4 methyltransferases in young photoreceptors results in massive disruptions to rhythmic gene expression that resemble those observed during aging. We conclude that there are broad epigenetic shifts in the aging retina, including decreased histone methylation, that contribute to changes in biological rhythms even in the presence of a robust molecular circadian clock.

Aging is modulated by nutrient-sensing pathways that integrate metabolic and hormonal cues to regulate growth, stress resilience, and lifespan. Caloric restriction (CR), a well-established intervention, extends longevity in diverse species primarily through inhibition of the TOR signaling pathway. Lysergic acid diethylamide (LSD), a classic serotonergic psychedelic with emerging therapeutic applications, remains largely unexplored in the context of aging. Here, we show that LSD treatment significantly extends lifespan in Caenorhabditis elegans and reduces age-associated lipofuscin accumulation, indicative of delayed cellular aging. LSD reproduces several CR-like phenotypes, including decreased reproductive output and increased nuclear localization of the transcription factor PHA-4/FOXA, without affecting food intake. Moreover, LSD treatment reduces lipid stores and downregulates global protein synthesis, both hallmark signatures of TOR inhibition. These findings establish LSD as a modulator of evolutionarily conserved longevity pathways and suggest that psychedelic signaling can mimic a caloric restriction-like metabolic state, paving the way for the development of novel geroprotective strategies.

Aging is a complex process characterized by a progressive decline in physiological functions driven by both biological and environmental factors, with notable differences between sexes. Immune function is strongly influenced by biological sex, affecting both innate and adaptive immune responses, including macrophage behavior. In this study, we investigated the effects of age and sex on the immune cell composition within the peritoneal cavity niche and identified macrophages as the most affected cell type. Macrophages, as central components of the innate immune system, play critical roles in maintaining tissue homeostasis and responding to infections. Here, we find that aging induces sex-specific remodeling of peritoneal macrophage transcriptomic and epigenomic landscapes. Consistently, peritoneal macrophages undergo sex-specific functional remodeling with aging (i.e. female-specific phagocytic decline and metabolic rewiring). Modulation of gonadal hormone signaling showed that changes in circulating estrogen levels likely contribute to aspects of female-specific macrophage age-related changes. Importantly, multi-omic analysis identified candidate transcription factors whose sex-specific age-regulated expression may drive aspects of sex-specific \'omic\' remodeling with aging. Specifically, Irf2 downregulation in female macrophages recapitulates distinct transcriptomic and metabolic aspects of macrophage female aging phenotypes. These findings suggest that female-specific age-related functional remodeling arises through hormone-dependent and -independent mechanisms in peritoneal macrophages.

Prediabetes, characterized by impaired fasting glucose and/or glucose tolerance, is associated with organ damage, increased mortality, and accelerated aging, even before diabetes onset. Severe short-term energy restriction while maintaining essential nutrient intake is among the most effective strategies for weight loss, metabolic health improvement, and delaying type 2 diabetes progression. Extracellular vesicles contribute to these metabolic benefits; however, the impact of energy-restriction-induced weight loss on the extracellular vesicle proteome remains incompletely understood. This study employed targeted and untargeted proteomics to investigate the effect of an 8-week severely energy-restricted diet on the plasma proteome in adults with prediabetes from Sydney, Australia, as part of the PREVIEW study. Circulating extracellular vesicles were enriched in plasma using an immunoaffinity-based protocol. A total of 44 participants who achieved at least a 12% weight loss and provided informed consent were included in the study. Paired changes in over 2000 proteins between baseline and week 8 were analyzed. Following the intervention, multiple proteins associated with inflammation and senescence were significantly reduced, reversing the increase commonly associated with aging. The decline in inflammatory and senescence markers may have been mediated by extracellular vesicles, as indicated by significantly lower circulating levels of several vesicular markers. Additionally, several markers of protein synthesis downstream of mTORC1 and protein degradation were significantly reduced in vesicle-enriched plasma, suggesting decreased intercellular secretion and/or trafficking. Overall, this study identifies a diet-induced proteomic signature suggestive of reduced inflammation, lower senescence, and enhanced vesicle-associated proteostasis, potentially conferring health benefits beyond glycemic control.

Genomic instability is a hallmark of ageing, driven by the accumulation of DNA lesions and the decline of high-fidelity repair pathways such as homologous recombination (HR) and classical nonhomologous end joining (c-NHEJ). We hypothesised that ageing cells increasingly rely on microhomology-mediated end joining (MMEJ), an inherently error-prone repair pathway, whose role in ageing remains poorly characterised. Here, we present the first systematic, tissue-wide analysis of MMEJ activity across eight rat organs using an in vitro assay with defined 10 to 16 nt microhomology substrates and cell-free extracts from rats of different ages. Our results reveal age-associated and tissue-specific reprogramming of MMEJ: activity increased in the testes and liver, newly emerged in kidneys and lungs, and declined in immune tissues such as the spleen and thymus. Strikingly, aged brain extracts exhibited latent MMEJ activity. Repair efficiency was further modulated by microhomology length in a tissue-dependent manner. These functional shifts correlated with altered expression of key MMEJ effectors, including XRCC1, PARP1, Ligase III, and notably FEN1, whose upregulation in aged lungs mirrored robust MMEJ activation. Together, our findings uncover dynamic remodelling of MMEJ during ageing, implicating it in age-related genomic instability and highlighting potential therapeutic targets to mitigate mutation burden in ageing tissues.

Recent studies reported that anti-angiogenic drugs targeting vascular endothelial growth factor (VEGF) alleviate choroidal neovascularization (CNV) in young but not aged animals. We recently developed a disease-targeted anti-angiogenic therapy against secretogranin III (Scg3), which selectively binds to diseased but not healthy vessels in young mice. Herein, using a unique in vivo ligand binding assay, we predicted and confirmed that Scg3 selectively binds CNV vessels in both young and aged mice. In contrast, VEGF with minimal increased binding to CNV vessels exhibited an age-dependent decline in binding to both CNV and healthy vessels with negligible binding in aged mice. Based on these binding activity patterns, we further predicted and confirmed that a humanized anti-Scg3 antibody effectively alleviated laser-induced CNV in both young and aged mice, whereas the anti-VEGF drug aflibercept was effective only in young mice. These findings suggest that enhanced binding of Scg3 to CNV vessels in both age groups provides a molecular basis for an age-independent anti-Scg3 therapy, offering potential to address anti-VEGF resistance in clinical treatment of wet age-related macular degeneration with CNV.

Rare genetic DNA repair deficiency syndromes can lead to immunodeficiency, neurological disorders, and cancer. In the general population, inter-individual variation in DNA repair capacity (DRC) influences susceptibility to cancer and several age-related diseases. Genome wide association studies and functional analyses show that defects in multiple DNA repair pathways jointly increase disease risk, but previous technologies did not permit comprehensive analyses of DNA repair in populations. To overcome these limitations, we used fluorescence multiplex host cell reactivation (FM-HCR) assays that directly quantify DRC across six major DNA repair pathways. We assessed DRC in phytohemagglutinin-stimulated primary lymphocytes from 56 healthy individuals and validated assay reproducibility in 10 individuals with up to five independent blood draws. We furthermore developed generalized analytical pipelines for systematically adjusting for batch effects and both experimental and biological confounders. Our results reveal significant inter-individual variation in DRC for each of 10 reporter assays that measure the efficiency of distinct repair processes. Our data also demonstrate that correlations between the activities of different DNA repair pathways are relatively weak. This finding suggests that each pathway may independently influence susceptibility to the health effects of DNA damage. We furthermore developed a pipeline for analyzing comet repair kinetics and related our new functional data to previously reported comet assay data for the same individuals. Our pioneering analysis underscores the sensitivity of FM-HCR assays for detecting subtle biological differences between individuals and establishes standardized methodologies for population studies. Our findings and open source analytical tools advance precision medicine by enabling comprehensive exploration of genetic, demographic, clinical, and lifestyle factors and supporting targeted interventions to enhance DNA repair and maintain genomic integrity, thereby promoting personalized healthcare and disease prevention.

HealthAge was devised by a conglomerate of research groups in Toulouse, France, with the combined goal of narrowing the lifespan-healthspan gap through novel translational bench-to-bedside research studies. HealthAge comprises the "INStitute for Prevention" "healthy aging" and "medicine Rejuvenative" (INSPIRE) human translational, outbred SWISS mice and African turquoise killifish (GRZ strain) cohorts in which aging is studied based on the concept of intrinsic capacity (IC). In this narrative review, we describe the three INSPIRE aging models (human cohort, n = 1109, age range 20 -102 years old with mean age ± standard deviation, 62.4 ± 19.0 years and 61.9% female; outbred SWISS mice, n = 1576 and African Turquoise killifish, n = 300) and explain how IC is assessed at the clinical (in humans) and biological level over time. HealthAge strives to elucidate the underlying biology of IC and to identify biomarkers of IC declines and novel gero-therapeutics using the clinical and biological data and biospecimens collected prospectively in the three species. The data sharing policy will foster scientific discovery through new multi-disciplinary collaborations. Thus, HealthAge will promote healthy aging using a unique translational platform based on IC phenotyping with the ultimate goal of preventing loss of human independence and alleviating health costs associated with an aging population.

The enzyme arginase-II has an important role in cardiac aging, and blocking it could help hearts stay young longer.

A decline in tissue renewal and repair due to changes in tissue stem cells is a hallmark of aging. Many stem cell pools are maintained by interaction with morphologically complex local niches. Using the C. elegans hermaphrodite germline stem cell system, we analyzed age-related changes in the morphology of the niche, the distal tip cell (DTC), and identified a molecular mechanism that promotes a subset of these changes. We found that a long-lived daf-2 mutant exhibits a daf-16-dependent decline in number and length of long DTC processes. Surprisingly, the tissue requirement for daf-16(+) is non-autonomous and is independent of the longevity requirement: daf-16(+) in body wall muscle is both necessary and sufficient. We also determined that pre-formed DTC processes deteriorate prematurely when the underlying germline differentiates. We propose a reciprocal DTC-germline interaction model and speculate a mechanism by which reducing daf-2 activity prevents stem cell exhaustion. These studies establish the C. elegans DTC as a powerful in vivo model for understanding age-related changes in cellular morphology and their consequences in stem cell systems.

Remembering familiar versus novel stimuli is fundamental to survival, but it is compromised in several neurodegenerative disorders where aging is a key factor. Although the components of the extracellular matrix (ECM) have been suggested to be implicated in memory maintenance, the mechanistic and behavioral roles of ECM during the aging process remain unclear. Here, we employed an accelerated mouse model of aging to elucidate the causal link between ECM dynamics and recognition memory during aging. Aged mice exhibited impaired social and non-social recognition memory, accompanied by increased intensity of perineuronal nets (PNNs), specialized ECM structures in the hippocampal dorsal CA2 (dCA2). A reduction in the power of theta oscillations (3-7 Hz) in the dCA2 of aged mice was also observed. Notably, selective degradation of PNNs in the dCA2 using chondroitinase ABC (ChABC) rescued recognition memory deficits and restored theta oscillations. Together, our findings identify abnormal PNN in the CA2 as a critical factor for age-related deficits in hippocampal-dependent recognition memory and network rhythmicity. These insights raise the possibility that targeting CA2 PNNs could facilitate the development of diagnostic and therapeutic strategies to address age-associated cognitive frailty.