Longevity Papers

Aging is a critical factor in the onset and progression of neurodegenerative diseases and cognitive decline, with aging-related neuroinflammation and cellular senescence being major contributors. In the aging brain, the cerebral vascular endothelium overexpresses vascular cell adhesion molecule 1 (VCAM1), activating microglia and leading to neuroinflammation and cognitive impairment. Quercetin, a natural neuroprotective agent widely used for treating neurodegenerative diseases, their therapeutic efficacy, however, is limited by its poor water solubility and inability to penetrate the blood-brain barrier (BBB). To address these challenges, we developed a multifunctional micellar platform (Anti-VCAM1-GM1@Q) to improve age-related neurodegenerative diseases. The micelles incorporate anti-VCAM1 antibodies to target cerebral vascular endothelial cells and block VCAM1. Additionally, monosialoganglioside (GM1) was utilized to deliver quercetin due to its biparental properties, high BBB permeability, and neuroprotective effects. Anti-VCAM1-GM1@Q micelles demonstrated strong anti-aging properties. They improved quercetin's bioavailability, effectively penetrated the BBB, targeted cerebral vascular endothelial cells, and reduced neuroinflammation. In animal models, these micelles provided effective neuroprotection, improved memory function and age-related cognitive impairment, and mitigated age-related neurodegeneration. Notably, this system exhibited remarkable treatment efficacy and high safety, indicating substantial potential for clinical translational applications.

Cellular senescence has emerged as one of the central hallmarks of aging and drivers of chronic comorbidities, including periodontal diseases. Senescence can also occur in younger tissues and instigate metabolic alterations and dysfunction, culminating in accelerated aging and pathological consequences. Senotherapeutics, such as the combination of dasatinib and quercetin (DQ), are being increasingly used to improve the clinical outcomes of chronic disorders and promote a healthy life span through the reduction of senescent cell burden and senescence-associated secretory phenotype (SASP). Recent evidence suggests that senescent cells and SASP can contribute to the pathogenesis of periodontal diseases as well. In this study, we investigated the effect of DQ interventions on periodontal tissue health using preclinical models of aging. In vitro, DQ ameliorated biological signatures of senescence in human gingival keratinocytes upon persistent exposure to periodontal bacteria,

During the early stage of tissue injury, macrophages play important roles in the activation of stem cells for further regeneration. However, the regulation of macrophages during bone regeneration remains unclear. Here, the extracellular matrix (ECM) tenascin-C (TNC) is found to express in the periosteum and recruit inflammatory macrophages. TNC-deficiency in the periosteum delays bone repair. Transplantation of macrophages derived from injured periosteum is able to rescue the decreased skeletal stem cells and impaired bone regeneration caused by TNC deficiency. The cell communication analysis identifies ITGA7 as a TNC receptor contributing to the recruitment of inflammatory macrophages. TNC expression declines in aged mice and the exogenous delivery of TNC significantly promotes bone regeneration after aging through the recruitment of macrophages. Taken together, this study reveals the regulation of macrophage recruitment and its function in the activation of skeletal stem cells after bone injury, providing a strategy to accelerate bone regeneration by TNC delivery.

Aging is the strongest risk factor for Alzheimer’s disease (AD). Accordingly, identifying biomarkers of accelerated aging is a major focus of AD prevention research. Current MRI‐based “aging clocks” (i.e., brain age) derive from cross‐sectional associations with chronological age. However, chronological age differs fundamentally from biological aging. We introduce a novel brain MRI proxy for biological aging in midlife developed in the Dunedin Study, a population‐representative longitudinal birth cohort, and demonstrate its ability to differentiate and predict AD in the Alzheimer’s Disease Neuroimaging Initiative (ADNI).

Alzheimer’s disease (AD) is associated with complex pathophysiology including synaptic dysregulation, compromised neurotrophic signaling, deficits in autophagic flux and neuroinflammation). Skeletal muscle regulates many brain functions relevant to aging, by activating the muscle‐to‐brain axis through the secretion of skeletal muscle originating factors (myokines) with cellular‐modifying, neuro and geroprotective properties. Our group developed transgenic mice that overexpress the skeletal muscle human Transcription Factor EB (TFEB), a master regulator of lysosomal‐to‐nucleus signaling, resulting in enhanced proteostasis and neuroprotection in a Tau mouse model. However, the precise mechanisms remain unknown. Therefore, we further validated these effects in an AD amyloid β (Aβ) mouse model and investigated the underlying mechanism.

Older individuals experience increased susceptibility and mortality to bacterial infections, but the underlying etiology remains unclear. Herein, it is shown that aging-associated reduction of commensal Parabacteroides goldsteinii (P. goldsteinii) in both aged mice and humans critically contributes to worse outcomes of bacterial infection. The colonization of live P. goldsteinii conferred protection against aging-associated bacterial infections. Metabolomic profiling reveals a protective compound, apigenin, generated by P. goldsteinii, antagonizes bacterial clearance defects in aged mice. AMP-binding protein (ampB) is identified as a key gene involved in apigenin synthesis in P. goldsteinii using homologous recombination in bacteria. Mechanistically, apigenin binds directly to the potential sites on Fgr (M341 and D404), preventing its inhibitory role on Vav1 phosphorylation, and therefore promoting the activation of Cdc42/Rac1, Arp2/3 expression and subsequent actin reorganization, which contributes to the enhanced phagocytosis of macrophages to bacteria. Collectively, the findings suggest that dysbiosis of the gut microbiota may impair host defense mechanisms and increase susceptibility to bacterial infections in older adults and highlight the microbiota-apigenin-Fgr axis as a possible route to ameliorate aging-associated antibacterial defects.

Identifying the clinical implications and modifiable and unmodifiable factors of aging requires the measurement of biological age (BA) and age gap.

It is increasingly clear that delaying the onset of Alzheimer’s disease (AD) dementia by several years can meaningfully lower its prevalence. The goal of the present study is to examine the relationship between lifestyle activities and cognition function as well as cerebrospinal fluid (CSF) biomarkers of AD to determine whether these activities can serve as protective factors for AD resistance and resilience.

To aid development of prevention strategies, we investigated whether a composite measure of late‐midlife lifestyle health was associated with (1) change in brain tau burden, vascular burden and neurodegeneration and (2) cognitive trajectories when accounting for these brain changes.

Levels of inflammatory components gradually rise in tissues and blood as we age. This “inflammageing” process is often debilitating and even fatal. Cognitive impairment is one example of inflammageing’s incapacitating nature. Excessive permeation of inflammatory markers in the brain gradually erodes the blood‐brain barrier (BBB) over time. Consequently, enhanced cerebral inflammatory processes contribute to neurological senescence. Neurological inflammageing may be partly due to a5 integrin, a receptor found primarily in brain endothelial cells during brain development, cerebrovascular injury (e.g. stroke), neuroinflammation and neurodegenerative disease (e.g. ALS). We hypothesize that deletion of a5 integrin in endothelial cells helps maintain BBB integrity and leads to improved cognitive performance with age. In the past we have shown that endothelial cell selective a5 knockout (a5‐EC‐KO) mice are more resilient to ischemic stroke. Enhanced stroke recovery in a5‐EC‐KO mice is due to less a5‐related BBB deterioration and subsequently less brain edema and infiltration of peripheral inflammatory cells. Therefore, we used aged a5‐EC‐KO and wild type (WT) litter mate mice to investigate how a5 integrin influences cognitive performance and survival probability over time.

White matter hyperintensities (WMH) are areas of increased lucency visualized on T2‐weighted magnetic resonance imaging (MRI), including fluid attenuated inversion recovery (FLAIR) sequences. Over the past 15 years we have been examining WMH in studies of cognitive aging among clinical, community‐based, and populations at genetic risk to understand the role of vascular brain injury in Alzheimer’s disease (AD) onset, symptom progression, and pathogenesis. Our findings suggest that regional WMH, particularly when distributed in posterior areas, increase risk for clinical AD and contribute to the clinical course of the disease, even among genetic population with relatively low rates of vascular risk factor, like adults with Down syndrome and with autosomal dominant genetic mutations for AD. While these observations suggest a role of endogenous cerebrovascular disease as a driver or core feature of AD, there has been considerable discussion about the underlying pathophysiology of WMH. Some authors argue that WMH in the context of AD reflect white matter changes secondary to neurodegeneration (so‐called “Wallerian degeneration”). We have argued against this possibility based on four observations. First, experimental data from animal models of vascular brain injury suggest that hypoperfusion injury gives rise white matter injury and downstream tau pathology and neurodegeneration. Second, the anatomical distribution of WMH in AD more closely aligns with the brain’s perfusion patterns and the vulnerability of whatershed regions to changes in blood supply and small vessel injury than with proximity to cortical neuronal injury. Third, the temporal evolution of WMH in the context of AD suggests a contribution of WMH that precedes expected neurodegenerative changes. Finally, we do not view an observed relationship between WMH and risk factors, such as hypertension, as a requirement to establish a cerebrovascular basis of WMH; rather, in total, findings suggest an “endogenous” cerebrovascular component, perhaps mediated by inflammatory changes, genetics, or blood brain barrier breakdown. Understanding the pathophysiological basis of WMH with respect to underlying vasculature may point to novel directions for disease prevention or intervention.

Late‐life exposure to PM

It remains unclear whether the benefits of adhering to a healthy lifestyle outweigh the effects of high genetic risk on cognitive decline. We examined the association of combined lifestyle factors and genetic risk with changes in cognitive function and six specific dimensions of cognition among older adults from the Chinese Longitudinal Healthy Longevity Survey (1998-2018, n = 18,811, a subset of 6301 participants with genetic information). Compared to participants with an unfavorable lifestyle, those with a favorable lifestyle showed a 46.81% slower rate of cognitive decline, with similar results across most cognitive domains. High genetic risk was associated with a 12.5% faster rate of cognitive decline. Individuals with a high genetic risk and a favorable lifestyle have slower cognitive decline than those with a low genetic risk and an unfavorable lifestyle. These data suggest that the benefits of a favorable lifestyle outweigh genetic factors, and therefore that adhering to a favorable lifestyle may offset the genetic risk for accelerated cognitive decline.

Normative models (NM) of brain metrics based on large, diverse populations offer novel strategies to detect individual brain abnormalities. To create an age‐dependent statistical model of brain microstructure over the human lifespan, we built the largest multi‐site NM of white matter (WM) diffusion tensor imaging (DTI) metrics based on 54,591 subjects. We used state‐of‐the‐art tools to adjust for site‐dependent effects.

Adult neural stem cells are

Physical activity (PA) is associated with lower dementia risk; however, underlying molecular pathways are poorly understood. We leveraged large‐scale plasma proteomics to identify biological signatures of objectively‐monitored PA in cognitively unimpaired (CU) older adults and cross‐validated signatures in independent exercise intervention and Alzheimer’s disease (AD) cohorts.

Aging and chronic inflammation are associated with overabundant myeloid-primed multipotent progenitors (MPPs) among hematopoietic stem and progenitor cells (HSPCs). Although hematopoietic stem cell (HSC) differentiation bias has been considered a primary cause of myeloid bias, whether it is sufficient has not been quantitatively evaluated. Here, we analyzed bone marrow data from the IκB- (Nfkbia+/-Nfkbib-/-Nfkbie-/-) mouse model of inflammation with elevated NFκB activity, which reveals increased myeloid-biased MPPs. We interpreted these data with differential equation models of population dynamics to identify alterations of HSPC proliferation and differentiation rates. This analysis revealed that short-term HSC differentiation bias alone is likely insufficient to account for the increase in myeloid-biased MPPs. To explore additional mechanisms, we used single-cell RNA sequencing (scRNA-seq) measurements of IκB- and wild-type HSPCs to track the continuous differentiation trajectories from HSCs to erythrocyte/megakaryocyte, myeloid, and lymphoid primed progenitors. Fitting a partial differential equations model of population dynamics to these data revealed not only less lymphoid-fate specification among HSCs but also increased expansion of early myeloid-primed progenitors. Differentially expressed genes along the differentiation trajectories supported increased proliferation among these progenitors. These findings were conserved when wild-type HSPCs were transplanted into IκB- recipients, indicating that an inflamed bone marrow microenvironment is a sufficient driver. We then applied our analysis pipeline to scRNA-seq measurements of HSPCs isolated from aged mice and human patients with myeloid neoplasms. These analyses identified the same myeloid-primed progenitor expansion as in the IκB- models, suggesting that it is a common feature across different settings of myeloid bias.

The neural basis of memory aging remains elusive. The default mode network (DMN) supports memory encoding and retrieval, and its connectivity decreases in aging. Young adults with larger differences in resting‐state functional connectivity (rsFC) between higher‐order DMN and lower‐order sensory/motor network (SMN) have better cognition and memory. We combined resting‐state and task‐based fMRI during an associative memory task to explore how this cross‐hierarchical contrast of rsFC is linked to memory aging.

Age-related macular degeneration (AMD), characterized by choroidal neovascularization (CNV), is the global leading cause of irreversible blindness. Current first-line therapeutics, vascular endothelial growth factor (VEGF) antagonists, often yield incomplete and suboptimal vision improvement, necessitating the exploration of novel and efficacious therapeutic approaches. Herein, a supramolecular engineering strategy to construct moringin (MOR) loaded α-cyclodextrin (α-CD) coated nanoceria (M@CCNP) is constructed, where the hydroxy and newly formed carbonyl groups of α-CD interact with the nanoceria surface via O─Ce conjunction and the isothiocyanate group of MOR inserts deeply into the α-CD cavity via host-guest interaction. By exploiting the recycling reactive oxygen species (ROS) scavenging capability of nanoceria and the anti-inflammation properties of MOR, the two-level strike during AMD pathogenesis can be precisely blocked by M@CCNP. Remarkably, excellent therapeutic efficacy to CNV is observed in vivo, achieving over 80% reduction in neovascularization and over 60% reduction in leakage area. In summary, the supramolecular engineered nanoceria provides an efficient approach for amelioration of AMD by blocking the two-level strike, and presents significant potential as an exceptional drug delivery platform, particularly for ROS-related diseases.

Studying brain reserve — the brain’s resilience to age‐related changes or damage — is crucial for understanding protective mechanisms against cognitive decline. The cerebellum may be a key region in brain reserve, but it has been historically understudied. This investigation delves into this critical area within the largest aging multi‐cohort to date.

The digital infrastructure has profoundly changed people's daily lives and health outcomes. However, the causal effect of digital infrastructure on cognitive health remains unclear. The study employs the "Broadband China" policy as a reliable proxy for digital infrastructure, using the China Health and Retirement Longitudinal Study (CHARLS) five waves panel data from 2011 to 2020 and a staggered difference-in-differences (DID) method to investigate the causal impact of digital infrastructure construction on the cognitive health in Chinese older adults. We find that digital infrastructure construction has a significant positive effect on the cognitive health of older adults, and the dynamic DID results confirm a persistent effect. Mechanism analysis shows that digital infrastructure improves cognitive health by increasing social interaction, health promotion behaviors (including medical insurance participation and physical exercise), and reducing medical costs. Heterogeneity analysis indicates that the cognitive health-improving effect of digital infrastructure construction is stronger among older adults living in urban areas and high-GDP cities, male, low and middle-aged, and highly educated. Our research findings provide empirical evidence for improving cognitive health and healthy aging among older adults through the development of digital infrastructure.

The African turquoise killifish Nothobranchius furzeri represents an emerging short-lived model for aging research. Captive strains of this species are characterized by large differences in lifespan. To identify the gene expression correlates of this lifespan differences, we analyzed a public transcriptomic dataset consisting of four different tissues in addition to embryos. We focused on the GRZ and the MZM0410 captive strains, which show a near twofold difference in lifespan, but similar growth and maturation and validated the results in a newly-generated dataset from a third longer-lived strain. The two strains show distinct transcriptome expression patterns already as embryos and the genotype has a larger effect than age on gene expression, both in terms of number of differentially expressed genes and magnitude of regulation. Network analysis detected RNA processing and histone modifications as the most prominent categories upregulated in GRZ that also showed idiosyncratic expression patterns such as high expression of DND is somatic tissues. The short-lived GRZ strain shows transcriptional aging signatures already at sexual maturity (anticipated aging) in all four tissues suggesting that short lifespan is the results of events that occur early in life rather than the progressive accumulation of strain-dependent differences. The GRZ strain is the most commonly used N. furzeri strain in intervention studies and our results warrant replication of at least key intervention studies in longer-lived strains.

Epigenetic clocks are a common group of tools used to measure biological aging-the progressive deterioration of cells, tissues, and organs. Epigenetic clocks have been trained almost exclusively using blood-based tissues, but there is growing interest in estimating epigenetic age using less-invasive oral-based tissues (i.e., buccal or saliva) in both research and commercial settings. However, differentiated cell types across body tissues exhibit unique DNA methylation landscapes and age-related alterations to the DNA methylome. Applying epigenetic clocks derived from blood-based tissues to estimate epigenetic age of oral-based tissues may introduce biases. We tested the within-person comparability of common epigenetic clocks across five tissue types: buccal epithelial, saliva, dry blood spots, buffy coat (i.e., leukocytes), and peripheral blood mononuclear cells. We tested 284 distinct tissue samples from 83 individuals aged 9-70 years. Overall, there were significant within-person differences in epigenetic clock estimates from oral-based versus blood-based tissues, with average differences of almost 30 years observed in some age clocks. In addition, most epigenetic clock estimates of blood-based tissues exhibited low correlation with estimates from oral-based tissues despite controlling for cellular proportions and other technical factors. Notably, the Skin and Blood clock exhibited the greatest concordance across all tissue types, indicating its unique ability to estimate chronological age in oral- and blood-based tissues. Our findings indicate that application of blood-derived epigenetic clocks in oral-based tissues may not yield comparable estimates of epigenetic age, highlighting the need for careful consideration of tissue type when estimating epigenetic age.

Ageing underlies functional decline of the brain and is the primary risk factor for several neurodegenerative conditions, including Alzheimer's disease (AD). However, the molecular mechanisms that cause functional decline of the brain during ageing, and how these contribute to AD pathogenesis, are not well understood. The objective of this study was to identify biological processes that are altered during ageing in the hippocampus and that modify Ad risk and lifespan, and then to identify putative gene drivers of these programmes. We integrated common human genetic variation associated with human lifespan or Ad from genome-wide association studies with co-expression transcriptome networks altered with age in the mouse and human hippocampus. Our work confirmed that genetic variation associated with Ad was enriched in gene networks expressed by microglia responding to ageing and revealed that they were also enriched in an oligodendrocytic gene network. Compellingly, longevity-associated genetic variation was enriched in a gene network expressed by homeostatic microglia whose expression declined with age. The genes driving this enrichment include CASP8 and STAT3, highlighting a potential role for these longevity-associated genes in the homeostatic functions of innate immune cells, and these genes might drive 'inflammageing'. Thus, we observed that gene variants contributing to ageing and AD balance different aspects of microglial and oligodendrocytic function. Furthermore, we also highlight putative Ad risk genes, such as LAPTM5, ITGAM and LILRB4, whose association with Ad falls below genome-wide significance but show strong co-expression with known Ad risk genes in these networks. Indeed, five of the putative risk genes highlighted by our analysis, ANKH, GRN, PLEKHA1, SNX1 and UNC5CL, have subsequently been identified as genome-wide significant risk genes in a subsequent genome-wide association study with larger sample size, validating our analysis. This work identifies new genes that influence ageing and AD pathogenesis, and highlights the importance of microglia and oligodendrocytes in the resilience of the brain against ageing and AD pathogenesis. Our findings have implications for developing markers indicating the physiological age of the brain and new targets for therapeutic intervention.

Age-related declines in cardiac function and exercise tolerance interfere with healthy living and decrease healthy life expectancy in older individuals. Tamogi-take mushrooms (Pleurotus cornucopiae) are known to contain high levels of Ergothioneine (EGT), an antioxidant with potential health benefits. In this study, we assessed the possibility that long-term consumption of Tamogi-take mushrooms might attenuate age-related decline in cardiac and vascular endothelial function in mice. We found that long-term intake of Tamogi-take mushrooms significantly maintained cardiac and vascular endothelial function and improved exercise tolerance in mice. Long-term mushroom consumption also increased levels of Nrf2 (Nuclear factor E2-related factor 2) protein in heart tissues and increased translation of HO-1 (Heme Oxygenase 1) proteins, which have antioxidant effects in heart and aortic tissues. Finally, long-term Tamogi-take mushroom consumption inhibited ROS accumulation with aging and reduced expression of inflammatory biomarkers. We conclude that ingestion of Tamogi-take mushrooms could serve as a dietary intervention to promote cardiovascular health, support healthy aging and slow the progression of age-related diseases.

Traditional approaches to studying astrocyte heterogeneity have mostly focused on analyzing static properties, failing to identify whether subtypes represent intermediate or final states of reactive astrocytes. Here we show that previously proposed neuroprotective and neurotoxic astrocytes are transitional states rather than distinct subtypes, as revealed through time-series multiomic sequencing. Neuroprotective astrocytes are an intermediate state of the transition from a nonreactive to a neurotoxic state in response to neuroinflammation, a process regulated by the mTOR signaling pathway. In Alzheimer's disease (AD) and aging, we observed an imbalance in neurotoxic and neuroprotective astrocytes in animal models and human patients. Moreover, targeting mTOR in astrocytes with rapamycin or shRNA mitigated astrocyte neurotoxic effects in neurodegenerative mouse models. Overall, our study uncovers a mechanism through which astrocytes exhibit neuroprotective functions before becoming neurotoxic under neuroinflammatory conditions and highlights mTOR modulation specifically in astrocytes as a potential therapeutic strategy for neurodegenerative diseases.

We previously reported that elevated expression of phospholipid hydroperoxide glutathione peroxidase 4, an enzyme that regulates membrane lipid hydroperoxides, can mitigate sarcopenia in mice. However, it is still unknown whether a pharmacological intervention designed to modulate lipid hydroperoxides might be an effective strategy to reduce sarcopenia in aged mice. Here we asked whether a newly developed compound, CMD-35647 (CMD), can reduce muscle atrophy induced by sciatic nerve transection. We treated mice daily with vehicle or CMD (15 mg/kg, i.p. injection) starting 1 day prior to denervation. CMD treatment reduced hydroperoxide generation and blunted muscle atrophy by over 17% in denervated muscle. To test whether CMD can reduce ageing-induced muscle atrophy and weakness, we treated mice with either vehicle or CMD (15 mg/kg, i.p. injection) 3 days per week for 8 months, starting at 18 months of age until 26 months of age. We measured muscle mass, functional status of neuromuscular junctions, muscle contractile function and mitochondrial function in control and CMD-treated 26-month-old female mice. Treatment with CMD conferred protection against muscle atrophy in both tibialis anterior and extensor digitorum longus that was associated with maintenance of fibre size of MHC 2b and 2x fibres. Mitochondrial respiration was also protected in CMD-treated mice. We also found that muscle force generation was protected with CMD treatment despite denervation in ∼25% of the muscle fibres. Overall, this study shows that pharmacological interventions designed to reduce lipid hydroperoxides might be effective for preventing sarcopenia. KEY POINTS: Sarcopenia in aged mice is associated with muscle loss, contractile dysfunction, denervation, and reduced mitochondrial respiration. CMD-35647 is a pharmocological compound that can neutralize lipid hydroperoxides. 8 month treatment of CMD-35647 mitigated muscle atrophy in tibialis anterior and extensor digitorum longus. 8 month treatment of CMD-35647 improved muscle function in aged mice independent of the neuromuscular junction. Aged mice treated with CMD-35647 had greater respiration in red gastrocnemius muscle when compared to vehicle treated mice.

Nucleotide availability is crucial for DNA replication and repair; however, the coordinating mechanisms in vivo remain unclear. Here, we show that the circadian clock in the liver controls the activity of the pentose phosphate pathway (PPP) to support de novo nucleotide biosynthesis for DNA synthesis demands. We demonstrate that disrupting the hepatic clock by genetic manipulation or mistimed feeding impairs PPP activity in male mice, leading to nucleotide imbalance. Such defects not only elicit DNA replication stress to limit liver regeneration after resection but also allow genotoxin-induced hepatocyte senescence and STING signalling-dependent inflammation. Mechanistically, the molecular clock activator BMAL1 synergizes with hypoxia-inducible factor-1α (HIF-1α) to regulate the transcription of the PPP rate-limiting enzyme glucose-6-phosphate dehydrogenase (G6PD), which is enhanced during liver regeneration. Overexpressing G6PD restores the compromised regenerative capacity of the BMAL1- or HIF-1α-deficient liver. Moreover, boosting G6PD expression genetically or through preoperative intermittent fasting potently facilitates liver repair in normal mice. Hence, our findings highlight the physiological importance of the hepatic clock and suggest a promising pro-regenerative strategy.

With the development of deep learning (DL) techniques, there has been a successful application of this approach to determine biological age from latent information contained in retinal images. Retinal age gap (RAG) defined as the difference between chronological age and predicted retinal age has been established previously to predict the age-related disease. In this study, we performed discovery genome-wide association analysis (GWAS) on the RAG using the 31,271 UK Biobank participants and replicated our findings in 8034 GoDARTS participants. The genetic correlation between RAGs predicted from the two cohorts was 0.67 (P = 0.021). After meta-analysis, we found 13 RAG loci which might be related to retinal vessel density and other aging processes. The SNP-wide heritability (h

Oxidative stress plays a crucial role in organ aging and related diseases, yet the endogenous regulators involved remain largely unknown. This work highlights the importance of metabolic homeostasis in protecting against oxidative stress in the large intestine. By developing a low-input and user-friendly pipeline for the simultaneous profiling of five distinct cysteine (Cys) states, including free SH, total Cys oxidation (Sto), sulfenic acid (SOH), S-nitrosylation (SNO), and S-glutathionylation (SSG), we shed light on Cys redox modification stoichiometries and signaling with regional resolution in the aging gut of monkeys. Notably, the proteins modified by SOH and SSG were associated primarily with cell adhesion. In contrast, SNO-modified proteins were involved in immunity. Interestingly, we observed that the Sto levels ranged from 0.97% to 99.88%, exhibiting two distinct peaks and increasing with age. Crosstalk analysis revealed numerous age-related metabolites potentially involved in modulating oxidative stress and Cys modifications. Notably, we elucidated the role of fumarate in alleviating intestinal oxidative stress in a dextran sulfate sodium (DSS)-induced colitis mouse model. Our findings showed that fumarate treatment promotes the recovery of several cell types, signaling pathways, and genes involved in oxidative stress regulation. Calorie restriction (CR) is a known strategy for alleviating oxidative stress. Two-month CR intervention led to the recovery of many antioxidative metabolites and reshaped the Cys redoxome. This work decodes the complexities of redoxomics during the gut aging of non-human primates and identifies key metabolic regulators of oxidative stress and redox signaling.

Senescent cells are known to contribute to aging and age-related diseases. One key way they influence aging is by secreting senescence-associated secretory phenotype (SASP) factors along with several damage-associated molecular pattern (DAMP) molecules. Consequently, inhibiting SASP and DAMP signaling (senomorphics) has emerged as a therapeutic strategy. Urolithin A (UA), a gut-derived metabolite produced from ellagitannins and ellagic acid found in berries, nuts, and pomegranates, has demonstrated potent anti-inflammatory properties and protective effects against aging and age-related conditions in experimental models. Here we demonstrate that UA lowers the expression and release of pro-inflammatory SASP and DAMP factors at least in part, on the downregulation of cytosolic DNA release and subsequent decrease in cGAS-STING signaling.

The maintenance of cellular redox balance is crucial for cell survival and homeostasis and is disrupted with aging. Selenoproteins, comprising essential antioxidant enzymes, raise intriguing questions about their involvement in hematopoietic aging and potential reversibility. Motivated by our observation of mRNA downregulation of key antioxidant selenoproteins in aged human hematopoietic stem cells (HSCs) and previous findings of increased lipid peroxidation in aged hematopoiesis, we employed tRNASec gene (Trsp) knockout (KO) mouse model to simulate disrupted selenoprotein synthesis. This revealed insights into the protective roles of selenoproteins in preserving HSC stemness and B-lineage maturation, despite negligible effects on myeloid cells. Notably, Trsp KO exhibited B lymphocytopenia and reduced HSCs' self-renewal capacity, recapitulating certain aspects of aged phenotypes, along with the upregulation of aging-related genes in both HSCs and pre-B cells. While Trsp KO activated an antioxidant response transcription factor NRF2, we delineated a lineage-dependent phenotype driven by lipid peroxidation, which was exacerbated with aging yet ameliorated by ferroptosis inhibitors such as vitamin E. Interestingly, the myeloid genes were ectopically expressed in pre-B cells of Trsp KO mice, and KO pro-B/pre-B cells displayed differentiation potential toward functional CD11b+ fraction in the transplant model, suggesting that disrupted selenoprotein synthesis induces the potential of B-to-myeloid switch. Given the similarities between the KO model and aged wild-type mice, including ferroptosis vulnerability, impaired HSC self-renewal and B-lineage maturation, and characteristic lineage switch, our findings underscore the critical role of selenoprotein-mediated redox regulation in maintaining balanced hematopoiesis and suggest the preventive potential of selenoproteins against aging-related alterations.

Ataxia-telangiectasia (A-T) is a pleiotropic genome instability syndrome resulting from the loss of the homeostatic protein kinase ATM. The complex phenotype of A-T includes progressive cerebellar degeneration, immunodeficiency, gonadal atrophy, interstitial lung disease, cancer predisposition, endocrine abnormalities, chromosomal instability, radiosensitivity, and segmental premature aging. Cultured skin fibroblasts from A-T patients exhibit premature senescence, highlighting the association between genome instability, cellular senescence, and aging. We found that lung fibroblasts derived from ATM-deficient mice provide a versatile experimental system to explore the mechanisms driving the premature senescence of primary fibroblasts lacking ATM.

Extracellular vesicles (EVs) are implicated in inter-organ communication, which becomes particularly relevant during aging and exercise. DNA methylation-based aging clocks reflect lifestyle and environmental factors, while regular exercise is known to induce adaptive responses, including epigenetic adaptations. Twenty individuals with High-fitness (aged 57.7 ± 9.8 years) and twenty Medium-Low-fitness (aged 57.5 ± 9.7 years) subjects provided blood samples. EVs were isolated from the samples using a size exclusion chromatography (SEC)-based method, and their protein content was analyzed by mass spectrometry (MS). Acceleration of the biological age estimator DNAmFitAge (AgeAccelFit) was associated with the protein cargo of EVs, whereas PhenoAge and GrimAge acceleration did not show a significant relationship. This finding suggests that the epigenetic aging-modulating role of exercise may involve inter-organ communication via EVs. Set Enrichment Analysis was performed to identify enriched Gene Ontology (GO) terms for sets of proteins that were either correlated with AgeAccelFit or detected exclusively in individuals with high levels of aerobic fitness. The protein cargo of EVs further suggests that inter-organ communication influences inflammation, the immune system, cellular repair, adhesion, metabolism and coagulation. Our findings help to understand the preventive role of exercise, which could be mediated in part by EVs.

The mammalian dentate gyrus (DG) is involved in certain forms of learning and memory, and DG dysfunction has been implicated in age-related diseases. Although neurogenic potential is maintained throughout life in the DG as neural stem cells (NSCs) continue to generate new neurons, neurogenesis decreases with advancing age, with implications for age-related cognitive decline and disease. In this study, we used single-cell RNA sequencing to characterize transcriptomic signatures of neurogenic cells and their surrounding DG niche, identifying molecular changes associated with neurogenic aging from the activation of quiescent NSCs to the maturation of fate-committed progeny. By integrating spatial transcriptomics data, we identified the regional invasion of inflammatory cells into the hippocampus with age and show here that early-onset neuroinflammation decreases neurogenic activity. Our data reveal the lifelong molecular dynamics of NSCs and their surrounding neurogenic DG niche with age and provide a powerful resource to understand age-related molecular alterations in the aging hippocampus.

Within the aging cortex, amyloid beta peptide (Aβ) is a crucial element of the senile plaques, a hallmark feature often observed in cases of Alzheimer's disease (AD). The UPR (unfolded protein response), a cellular mechanism for protein folding, is switched on by Aβ accumulation. Endoplasmic reticulum (ER) stress has been identified as playing a role in aging and the development of neurodegenerative diseases. The exact molecular pathways leading to perishing of cells from Aβ-induced ER stress, as well as the impact of voluntary exercise on these mechanisms, are still subjects awaiting a definitive answer yet. In the current study, 18 male Wistar rats were included: 6 young rats (3 months old; 200-250 g) in the Young Control group, and 12 old rats (18 months old; 400-430 g) randomly allocated to the Old Control and Old Exercise groups. The rat cages had running wheels for them to voluntarily run on for 8 weeks. This was followed by Western blotting, immunohistochemical staining, biochemical as well as morphological analyses. Voluntary exercise reduced Aβ1-42 deposition (P < 0.001) and inhibited the activation of caspase-8 (P < 0.001) and caspase-12 (P < 0.01), and on top of that down-regulated the expression of ATF6 (P < 0.001), CHOP (P < 0.01), and p-PERK (P < 0.05) proteins in the hippocampus of old male rats. Exercise amplified the population of Bcl-2-expressing cells and decreased the population of Bax-expressing cells in the hippocampus of the Old Exercise group (P < 0.001). Voluntary exercise inhibited the apoptotic pathways and suppressed the activation of UPR signaling pathways. Hence, voluntary exercise may be a therapeutic strategy and a promising approach to prevent AD through modulation of Aβ-induced ER stress.

Importance: SuperAgers are oldest-old adults (ages 80+) whose memory performance resembles that of adults in their 50s to mid-60s. Factors underlying their exemplary memory are underexplored in large, racially diverse cohorts. Objective: To determine the frequency of APOE genotypes in non-Hispanic Black and non-Hispanic White SuperAgers compared to middle-aged (ages 50-64), old (ages 65-79), and oldest-old (ages 80+) controls and Alzheimers disease (AD) dementia cases. Design: This multicohort study selected data from eight longitudinal cohort studies of normal aging and AD. Setting: Variable recruitment criteria and follow-up intervals, including both population-based and clinical-based samples. Participants: Inclusion in our analyses required APOE genotype, that participants be age 50+, and are identified as either non-Hispanic Black or non-Hispanic White. In total, 18,080 participants were included in the present study with a total of 78,549 datapoints. Main Outcomes and Measures: Harmonized, longitudinal memory, executive function, and language scores were obtained from the Alzheimers Disease Sequencing Project Phenotype Harmonization Consortium (ADSP-PHC). SuperAgers, controls, and AD dementia cases were identified by cognitive scores using a residual approach and clinical diagnoses across multiple timepoints when available. SuperAgers were compared to AD dementia cases and cognitively normal controls using age-defined bins (middle-aged, old, oldest-old). Results: Across racialized groups, SuperAgers had significantly higher proportions of APOE-{varepsilon}2 alleles and lower proportions of APOE-{varepsilon}4 alleles compared to cases. Similar differences were observed between SuperAgers and middle-aged and old controls. Non-Hispanic White SuperAgers had significantly lower proportions of APOE-{varepsilon}4 alleles and significantly higher proportions of APOE-{varepsilon}2 alleles compared to all cases and controls, including oldest-old controls. In contrast, non-Hispanic Black SuperAgers had significantly lower proportions of APOE-{varepsilon}4 alleles compared to cases and younger controls, and significantly higher proportions of APOE-{varepsilon}2 alleles compared only to cases. Conclusions and Relevance: In the largest study to date, we demonstrated strong evidence that the frequency of APOE-{varepsilon}4 and -{varepsilon}2 alleles differ between non-Hispanic White SuperAgers and AD dementia cases and cognitively normal controls. Differences in the role of APOE in SuperAging by race underlines distinctions in mechanisms conferring resilience across race groups given likely differences in genetic ancestry.

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

Understanding the complex biological process of aging is of great value, especially as it can help develop therapeutics to prolong healthy life. Predicting biological age from gene expression data has shown to be an effective means to quantify aging of a subject, and to identify molecular and cellular biomarkers of aging. A typical approach for estimating biological age, adopted by almost all existing aging clocks, is to train machine learning models only on healthy subjects, but to infer on both healthy and unhealthy subjects. However, the inherent bias in this approach results in inaccurate biological age as shown in this study. Moreover, almost all existing transcriptome-based aging clocks were built around an inefficient procedure of gene selection followed by conventional machine learning models such as elastic nets, linear discriminant analysis etc. To address these limitations, we proposed DeepQA, a unified aging clock based on mixture of experts. Unlike existing methods, DeepQA is equipped with a specially designed Hinge-Mean-Absolute-Error (Hinge-MAE) loss so that it can train on both healthy and unhealthy subjects of multiple cohorts to reduce the bias of inferring biological age of unhealthy subjects. Our experiments showed that DeepQA significantly outperformed existing methods for biological age estimation on both healthy and unhealthy subjects. In addition, our method avoids the inefficient exhaustive search of genes, and provides a novel means to identify genes activated in aging prediction, alternative to such as differential gene expression analysis.

Throughout the animal kingdom, several members of the basic helix-loop-helix (bHLH) family act as proneural genes during early steps of nervous system development. Roles of bHLH genes in specifying terminal differentiation of postmitotic neurons have been less extensively studied. We analyze here the function of 5 Caenorhabditis elegans bHLH genes, falling into 3 phylogenetically conserved subfamilies, which are continuously expressed in a very small number of postmitotic neurons in the central nervous system. We show (a) that 2 orthologs of the vertebrate bHLHe22/e23 genes, called hlh-17 and hlh-32, function redundantly to specify the identity of a single head interneuron class (AUA), as well as an individual motor neuron (VB2); (b) that the PTF1a ortholog hlh-13 acts as a terminal selector to control terminal differentiation and function of the sole octopaminergic neuron class in C. elegans, RIC; and (c) that the NHLH1/2 ortholog hlh-15 controls terminal differentiation and function of the peptidergic AVK head interneuron class, a known neuropeptidergic signaling hub in the animal. Strikingly, through null mutant analysis and cell-specific rescue experiments, we find that loss of hlh-15/NHLH in the peptidergic AVK neurons and the resulting abrogation of neuropeptide secretion from these neurons causes a substantially extended lifespan of the animal, which we propose to be akin to hypothalamic control of lifespan in vertebrates. Our functional analysis reveals themes of bHLH gene function during terminal differentiation that are complementary to the earlier lineage specification roles of other bHLH family members. However, such late functions are much more sparsely employed by members of the bHLH transcription factor family, compared to the function of the much more broadly employed homeodomain transcription factor family.

Background: Here, we assessed the role of the advanced glycation end-product (AGE) precursor methylglyoxal (MGO) and its non-crosslinking AGE MGO-derived hydroimidazolone (MGH-1) in aortic stiffening and explored the potential of a glycation stress-lowering compound (Gly-Low) to mitigate these effects. Methods: Young (3-6 month) C57BL/6 mice were supplemented with MGO (in water) and Gly-Low (in chow). Aortic stiffness was assessed in vivo via pulse wave velocity (PWV) and ex vivo through elastic modulus. Putative mechanisms underlying MGO and MGH-1-induced aortic stiffening were explored using complementary experimental approaches in aortic tissue and cultured human aortic endothelial cells (HAECs). Moreover, aortic stiffness was assessed in old (24 month) mice after consumption of Gly-Low-enriched chow. Results: MGO-induced glycation stress increased PWV in young mice by 21% (P<0.05 vs. control), which was prevented with Gly-Low (P=0.93 vs. control). Ex vivo, MGO increased aortic elastic modulus 2-fold (P<0.05), superoxide production by ~40% (P<0.05), and MGH-1 expression by 50% (P<0.05), which were all mitigated by Gly-Low. Chronic MGO exposure elevated biomarkers of cellular senescence in HAECs, comparable to a known senescence inducer Doxorubicin, an effect partially blocked by Gly-Low. Moreover, elevated aortic elastic modulus induced by Doxorubicin (P<0.05 vs. control) was prevented with Gly-Low (P=0.71 vs. control). Aortic RNA sequencing implicated preservation of endogenous cellular detoxification pathways with Gly-Low following exposure to MGH-1. Old mice supplemented with Gly-Low had lower PWV (P<0.05) relative to old control mice. Conclusions: MGO-induced glycation stress contributes to aortic stiffening and glycation stress lowering compounds hold promise for mitigating these effects.

Chronic kidney disease (CKD) is a major global health issue, projected to become the fifth leading cause of mortality by 2040. Renal tubular cell senescence is a key driver of kidney fibrosis, the final manifestation of CKD. However, current treatment strategies, do not target senescent cells, as the underlying mechanisms driving this dysfunctional phenotype remain poorly described. Here, we identify nicotinamide-N-methyltransferase (NNMT), as a critical mediator of tubular senescence and fibrosis in CKD. Using human RNAseq profiles of CKD, we show that NNMT expression in the renal tubulointerstitium is strongly associated with CKD pathology and transcriptional signatures of cellular senescence. In human diabetic kidney disease biopsies, NNMT levels correlate with the senescence marker p21, kidney function decline, and fibrosis. Spatial transcriptomics further highlights that NNMT-positive tubules are senescent, fibrotic, and surrounded by a pro-inflammatory microenvironment. Preclinical models of early-stage CKD, show upregulation of NNMT and association with senescence. Overexpression of NNMT in TGF-beta-stimulated tubular epithelial cells promotes senescence and partial epithelial-to-mesenchymal transition (EMT), while inhibition of NNMT in kidney cells and organoids is protective. Altogether, we identify NNMT as a novel therapeutic target in the early stages of CKD with the potential to reduce tubular senescence, fibrosis and significantly slow disease progression.

Obesity is linked to limited adipose tissue (AT) remodeling capacity, leading to hypertrophic adipocytes, senescence, and inflammation. We used a mouse model expressing mTert (p21+/Tert) from the Cdkn1a locus to investigate the role of mTERT in obesity-induced metabolic disorders. Conditional expression of mTERT reduces metabolic disorders associated with obesity. In AT, this is accompanied by a decrease in the number of senescent p21-positive cells, very short telomeres, and oxidative DNA damage. Single nucleus RNA-seq data reveal TERT expression attenuates senescence induced by HFD in particular in adipose stem and progenitor cells (ASPC). We show that ASPC expansion and differentiation are promoted in p21+/Tert obese mice, thereby reducing metabolic disorders. We further report that mTERT remodels the landscape of macrophages in AT of obese mice. Strikingly, inactivation of mTERT catalytic activity in p21+/Tert (p21+/TertCi) mice suppresses the promotion of adipocyte formation, but neither affects attenuation of senescence nor macrophage remodeling. These results highlight mTERT\'s canonical and non-canonical functions in reducing obesity-associated metabolic disorders. Conditional expression of TERT thus appears as a potential therapeutic option for obesity.

Aging is characterized by extensive metabolic dysregulation. Redox coenzyme nicotinamide adenine dinucleotide (NAD) can exist in oxidized (NAD+) or reduced (NADH) states, which together form a key NADH/NAD+ redox pair. Total levels of NAD decline with age in a tissue-specific manner, thereby playing a significant role in the aging process. Supplementation with NAD precursors boosts total cellular NAD levels and provides some therapeutic benefits in human clinical trials. However, supplementation studies cannot determine tissue-specific effects of an altered NADH/NAD+ ratio. Here, we created transgenic Drosophila expressing a genetically encoded xenotopic tool LbNOX to directly manipulate the cellular NADH/NAD+ ratio. We found that LbNOX expression in Drosophila impacts both NAD(H) and NADP(H) metabolites in a sex-specific manner. LbNOX rescues neuronal cell death induced by the expression of mutated alpha-B crystallin in the Drosophila eye, a widely used system to study reductive stress. Utilizing LbNOX, we demonstrate that targeting redox NAD metabolism in different tissues may have drastically different outcomes, as the expression of LbNOX solely in the muscle is much more effective for rescuing paraquat-induced oxidative stress compared to whole-body expression. Excitingly, we demonstrate that perturbing NAD(P) metabolism in non-neuronal tissues is sufficient to rejuvenate sleep profiles in aged flies to a youthful state. In summary, we used xenotopic tool LbNOX to identify tissues and metabolic processes which benefited the most from the modulation of the NAD metabolism thereby highlighting important aspects of rebalancing the NAD and NADP pools, all of which can be translated into novel designs of NAD-related human clinical trials.