Longevity Papers

Osteoarthritis (OA), a chronic and degenerative joint disease, has become increasingly prevalent due to the aging population, posing a significant societal burden. However, despite progress, effective therapeutic options for osteoarthritis remain limited. In OA, chronic inflammation mediates a hypoxic microenvironment, leading to increased cellular energy demands. Over time, this causes mitochondrial dysfunction, favoring the accumulation of ROS, thereby perpetuating inflammation. Furthermore, reduced autophagy in aging chondrocytes hinder the clearance of damaged mitochondria, exacerbating oxidative stress. Herein, we have developed a simple and environmentally friendly strategy to fabricate hydrogen-releasing nanozymes (Se-HMPB@AB@COS) that spontaneously release hydrogen gas, effectively treating osteoarthritis through antioxidant, anti-inflammatory, and mitochondrial dysfunction reversal mechanisms. During the process of hydrogen therapy, small hydrogen molecules can readily penetrate mitochondria, specifically reducing the levels of •OH thereby protecting mitochondrial function. Our research further unveils that hydrogen therapy can effectively enhance mitophagy and delay chondrocyte senescence. In vivo, Se-HMPB@AB@COS encapsulated with chondroitin sulfate significantly promotes the synthesis of collagen II, inhibits the degradation of extracellular matrix, and reduces inflammatory factors. Overall, this study innovatively synthesized a hydrogen-releasing nanozyme, demonstrating its effectiveness in inhibiting oxidative stress, inflammation, promoting mitophagy and extracellular matrix synthesis, thereby reducing cartilage and mitochondrial damage, and delaying OA progression.

The activity of procyanidin C1 (PCC1) is limited by poor intestinal targeting, while traditional delivery systems typically neglect the adjuvant activity of the wall material. This study aimed to explore the potential of Polygonatum polysaccharides (PSP) as wall materials for delivery systems with synergistic effects. A novel PCC1 yolk-shell nanoparticles delivery system (PCC1-P/L NPs) were fabricated using lysine as a cross-linking agent, achieving a drug loading efficiency of 93.57 %. Molecular docking analysis revealed that PSP interacted with PCC1 and lysine through hydrogen bonds and hydrophobic interactions. We further evaluated the targeted delivery efficiency and synergistic effect of PCC1-P/L NPs. It significantly increased the PCC1 concentrations in the intestine by twofold. Furthermore, PCC1-P/L NPs exerted a synergistic anti-aging effect, extending the maximum lifespan of Drosophila by 30.8 %, which significantly exceeded the effect of PCC1 or PSP alone. Moreover, the delivery system potently suppressed the accumulation of pH 3+ and esg + cells and preserved gut integrity. This study highlights PSP as a multifunctional wall material and offers a new strategy for anti-aging.

Collagen is a prevalent protein in the animalia kingdom, especially in mammals. It is abundant in all connective tissue such as bone or ligaments and thus it is subjected to substantial mechanical forces. Crosslinks play an essential role for the structural and mechanical integrity of collagen, determining its stiffness and rigidity. Until now, studies on collagen including crosslinks have either been confined to fully atomistic simulations, which are computationally intensive and restrict the accessible time and length scales, or to coarse-grained descriptions that do not resolve the force response on a residue-level and therefore do not consider the triple helical structure and the connectivity of crosslinks. To bridge this gap, we report the development and validation of a computational model based on the Martini 3 coarse-grained force field, in which we parametrized the fibrillar collagen structure including crosslinks. We validated the model, through extensive equilibrium and non-equilibrium molecular dynamics simulations, against experimental properties and all-atom simulations. Because the type and distribution of crosslinks vary with aging, we expect that this collagen model can be employed to provide insights into age-related changes in tissue mechanics and guide the development of biomimetic materials.

Menopause affects the aging process in women through significant ovarian hormone production decline in midlife. Women who experience early menopause face an accelerated physiological aging rate, along with impaired memory and increased risks of neurodegenerative diseases. However, it remains elusive how the timing of menopause affects brain activity, which could be crucial for understanding menopause-related acceleration of aging and increased risk of dementia. Recent studies have revealed a highly structured infra-slow (< 0.1 Hz) global brain activity across species and linked it to arousal and memory functions, as well as waste clearance in Alzheimer\'s diseases (AD). In this study, we examined how this global brain activity relates to age of menopause using resting-state fMRI data from the Human Connectome Project-Aging dataset. We found that women who experienced earlier menopause (mean menopausal age 45{+/-}3.5 yr) exhibited weaker global brain activity (p = 5.0x10-4) with reduced coupling to cerebrospinal fluid (CSF) flow (p = 0.017) compared to age-matched later-menopausal women (mean menopausal age 54{+/-}1.2 yr). Differences appeared mainly in higher-order brain regions, where activation levels correlated with memory performance in earlier but not in intermediate or later menopausal women. These findings highlight brain activity changes linked to early menopause, suggesting a potential mechanism underlying memory decline and the increased risk of AD and dementias in early-onset menopausal women.

Aging is accompanied by progressive declines in metabolic and cognitive functions. Growth hormone secretagogue receptor (GHSR), a receptor for the gut hormone ghrelin, is highly expressed in neurons and plays a crucial role in metabolic regulation. We previously reported that aged global GHSR-ablated mice are lean and insulin-sensitive, and that neuronal GHSR-deleted mice (Syn1-cre;Ghsr

Osteoporosis (OP) is a progressive skeletal disorder characterized by reduced bone mass, structural deterioration, and increased fracture risk, particularly in postmenopausal women and the elderly. Oxidative stress and inflammation are key contributors to the disruption of bone remodeling in OP. Nuclear factor erythroid 2-related factor 2 (Nrf2), a master regulator of cellular redox homeostasis, has gained attention for its role in bone metabolism. This review explores Nrf2's regulatory influence on osteoblast (OB) and osteoclast (OC) activity. In OBs, moderate Nrf2 activation protects against reactive oxygen species (ROS)-induced apoptosis, enhances differentiation, and supports bone formation. In contrast, both insufficient and excessive Nrf2 expression may impair OB function. In OCs, Nrf2 suppresses ROS-mediated pathways such as MAPK and NF-κB, thereby inhibiting differentiation and resorptive activity. Nrf2 also attenuates inflammation by downregulating pro-inflammatory mediators and inhibiting NF-κB nuclear translocation. Nrf2 knockout animal models exhibit age-related bone loss, reduced bone mineral density, impaired trabecular structure, and delayed fracture healing. These effects are exacerbated by increased oxidative stress and inflammation. Notably, sex-specific differences have been observed, with female mice showing greater susceptibility to Nrf2 deficiency, potentially due to interactions with estrogen signaling. Nrf2 also regulates osteocyte-specific gene expression, further reinforcing its role in bone maintenance and mechanotransduction. Therapeutic activation of Nrf2 using agents such as bardoxolone methyl, sulforaphane, quercetin, and curcumin shows promise in mitigating bone loss. However, precise modulation is crucial to avoid potential adverse effects. Overall, Nrf2 represents a promising target for the prevention and treatment of OP and related musculoskeletal disorders.

Intervertebral disc degeneration (IDD) is a chronic degenerative disorder marked by nucleus pulposus cells (NPCs) senescence and extracellular matrix (ECM) degradation, which is a key pathological factor leading to low back pain. Current clinical treatments are mainly limited to symptomatic relief without effectively reversing the degenerative process.

Cellular senescence is a fundamental biological process characterized by stable cell cycle arrest, genomic instability, and the acquisition of a proinflammatory secretory phenotype. While senescence is traditionally associated with aging, growing evidence reveals that chronic infections such as viral, bacterial, and protozoan parasites can serve as powerful inducers of senescence, contributing to premature aging and long-term tissue damage. This review explores the diverse mechanisms by which persistent pathogens trigger or sustain senescence in host cells. We highlight how these chronic infections manipulate host DNA repair, mitochondrial dynamics, telomere maintenance, oxidative stress, and immune function to promote senescence and immunosenescence. Emerging findings also reveal how pathogens hijack the host cellular machinery to induce senescence across various tissue types. In many cases, senescence not only enables pathogen persistence but also drives pathological outcomes such as fibrosis, neurodegeneration, cardiomyopathy, and immune exhaustion. Collectively, this emerging evidence highlights a unifying strategy among diverse pathogens: the exploitation of cellular senescence to support chronic infection and promote disease. Understanding how infectious agents drive senescence offers new insights into age-related pathologies and highlights potential therapeutic targets, such as senolytic and senomorphic agents, to mitigate the long-term impacts of chronic infections.

We propose a new theory for aging based on dynamical systems and provide a data-driven computational method to quantify the changes at the cellular level. We use ergodic theory to decompose the dynamics of changes during aging and show that aging is fundamentally a dissipative process within biological systems, akin to dynamical systems where dissipation occurs due to non-conservative forces. To quantify the dissipation dynamics, we employ a transformer-based machine learning algorithm to analyze gene expression data, incorporating age as a token to assess how age-related dissipation is reflected in the embedding space. By evaluating the dynamics of gene and age embeddings, we provide a cellular aging map (CAM) and identify patterns indicative of divergence in gene embedding space, nonlinear transitions, and entropy variations during aging for various tissues and cell types. Our results provide a novel perspective on aging as a dissipative process and introduce a computational framework that enables measuring age-related changes with molecular resolution.

In advancing pathophysiological models to assess renal drug responses, kidney organoids derived from human pluripotent stem cells mark notable progress. However, replicating aging- and senescence-related pathologies remains a challenge. In this study, an alternative model is introduced using "tubuloids"-epithelial-like structures generated from primary human renal proximal tubular epithelial cells (hRPTECs) isolated from resected human kidneys. Bulk RNA-seq deconvolution confirmed that tubuloids are highly differentiated and predominantly composed of proximal tubule-like cells. Exposure to cisplatin increased γH2AX, Kidney Injury Molecule-1, and Cleaved Caspase-3, markers for DNA damage response, epithelial damage, and apoptosis, respectively. Repeated cisplatin administration resulted in the upregulation of senescence markers and secretion of inflammatory cytokines, consistent with a senescence-associated secretory phenotype (SASP). Supernatants from cisplatin-treated tubuloids triggered myofibroblast activation, suggesting early fibrotic changes. A hRPTEC-derived tubuloid model of cisplatin-induced kidney injury is successfully developed that mimics senescence, SASP, and fibrosis-hallmarks of chronic kidney disease. This model offers a promising human-relevant platform for studying renal epithelial responses and drug screening.

Endothelial dysfunction can be regarded as the earliest feature of vascular aging and may occur in individuals without traditional risk factors for cardiovascular disease. Once present, endothelial dysfunction is known to increase the risk for atherosclerosis, cardiovascular diseases and complications such as stroke or death. Identification of individuals with early features of vascular aging remains challenging and has fuelled investigative efforts to associated biologic, imaging, and digital markers with endothelial dysfunction. This review highlights emerging and traditional methods to identify patients with early endothelial dysfunction and summarizes available and experimental therapies aimed at mitigating the vascular aging process.

Developmental conditions, including temperature, diet, and parasite exposure, can shape adult fitness phenotypes across species. While studies often examine the independent effects of early-life and adult conditions on life history traits, fewer have focused on their interactive effects, particularly in genetically diverse populations. Here, we investigate how larval and adult diet interact to influence lifespan and fecundity in a genetically diverse population of Drosophila melanogaster. We manipulated protein availability across larval and adult stages and found significant larval-adult diet interactions affecting both traits, though in different ways. Several key patterns emerged, including age- and sex-specific effects, survival differences in the post-median life phase, shifts in the timing of peak fecundity, and sustained egg production in older stages. Protein reduction increased male maximum lifespan and female lifetime fecundity, while lower adult protein intake delayed egg-laying by approximately two weeks, particularly in flies that also experienced low developmental protein. These findings underscore the importance of assessing life history traits dynamically over time, as interactions between developmental and adult environments may drive complex, non-additive effects that are not apparent in cross-sectional measurements. Considering both additive and interactive effects in diverse genetic backgrounds will be critical for understanding the evolutionary and ecological consequences of nutritional variation.

The biological aging acceleration predicts both morbidity and mortality, while few investigations have examined its utility in evaluating transitions, e.g. development patterns, of atrial fibrillation (AF) and dementia. We aimed to investigate the utility of biological aging acceleration in predicting transitions of AF and dementia. A total of 402,955 participants (mean [SD] age: 56.5 [8.1] years; men: 45.9%) in the UK Biobank were included. Biological age was calculated using the phenotypic age, based on the chronological age and 9 biomarkers. A multi-state survival analysis was conducted to examine transition patterns between AF and dementia. The increased biological aging acceleration was consistently associated with all transition patterns between AF and dementia, including transitions from incident AF or dementia to the comorbidity. Strong linear associations were observed. Our findings highlight the overlooked utility of biological aging acceleration in evaluating the transitions of AF and dementia in the general population.

Cardiovascular diseases remain the leading cause of mortality worldwide, with aging as a major risk factor. Endothelial cell (EC) dysfunction, driven by cellular senescence, is central to age-related cardiomyopathy. Despite its clinical significance, the molecular mechanisms underlying endothelial senescence remain incompletely defined. In this study, we observed that the expression of the endothelial-specific gene heat shock protein family A member 12B (HSPA12B) declines significantly with age. HSPA12B deficiency in mice accelerates age-related EC senescence and cardiac dysfunction, whereas HSPA12B overexpression mitigates EC senescence, highlighting its protective role against vascular aging. Mechanistically, HSPA12B deficiency impairs X-box binding protein 1 (XBP1) transcriptional activity and consequently reduces the expression of its downstream target genes suppressor/enhancer of lin-12-like (SEL1L) and HMG-CoA reductase degradation protein-1 (HRD1). This disruption compromises endoplasmic reticulum-associated degradation (ERAD) of Stimulator of interferon genes (STING), resulting in persistent activation of the cyclic GMP-AMP synthase (cGAS)-STING pathway, a critical driver of EC senescence. In contrast, increased HSPA12B expression enhances XBP1 nuclear translocation and upregulates SEL1L and HRD1, thereby attenuating age-related STING activation. Importantly, pharmacological inhibition of STING reversed the senescent phenotype caused by HSPA12B deficiency. Similarly, enhancing XBP1 activity restored SEL1L and HRD1 expression, reduced STING activation, and alleviated EC senescence. Conversely, SEL1L deficiency or HRD1 inhibition exacerbated STING activation and abolished the protective effects of HSPA12B. Collectively, these findings reveal a previously unrecognized role for HSPA12B in preserving endothelial homeostasis during aging by regulating XBP1-mediated ER-associated degradation of STING and highlight HSPA12B as a potential therapeutic target for age-related cardiovascular dysfunction.

Biological sex is a crucial, but poorly understood variable in age-related susceptibility to infection. Monocytes are important immune cells responsible for initiating and resolving inflammatory responses to infection. While changes in monocyte populations result in increased susceptibility to infection, there is limited research on the impact of age and sex on human monocyte phenotype and function. The aim of this work was to dissect the impact of increasing age and biological sex on human monocyte phenotype and function. Here, we show that older females have increased inflammatory intermediate and non-classical monocytes compared to young. These monocyte subsets were the most inflammatory ex vivo, and their frequency correlated with markers of inflammageing. Proteomic analysis of sorted monocyte populations demonstrated that the three human monocyte subsets have largely distinct phenotypes. Key age-associated protein pathways were identified, including complement cascade and phagocytosis. We confirmed the proteomics findings, showing that circulating C3 concentrations were reduced with age in females but not males. This decrease in complement in older females resulted in reduced monocyte phagocytosis. Crucially, we demonstrate that in peri/menopausal females, hormone replacement therapy (HRT) reversed this expansion in intermediate monocytes and decreased circulating CRP as compared to age-matched controls. Importantly, peri/menopausal females on HRT had increased C3 serum concentrations and significant improvement in monocyte phagocytosis. The data presented here indicate the importance of menopause in aging monocyte phenotype and function. These data highlight the potential use of HRT in restoring monocyte function in females during aging and potentially improving anti-pathogen immunity.

The mouse is a tractable model for human ovarian biology, however its utility is limited by incomplete understanding of how transcription and signaling differ interspecifically and with age. We compared ovaries between species using three-dimensional imaging, single-cell transcriptomics, and functional studies. In mice, we mapped declining follicle numbers and oocyte competence during aging; in human ovaries, we identified cortical follicle pockets and decreases in density. Oocytes had species-specific gene expression patterns during growth that converged toward maturity. Age-related transcriptional changes were greater in oocytes than granulosa cells across species, although mature oocytes change more in humans. We identified ovarian sympathetic nerves and glia; axon density increased in aged ovaries and, when ablated in mice, perturbed folliculogenesis. This comparative atlas defines shared and species-specific hallmarks of ovarian biology.

Alterations in metabolism, stress response, sleep, circadian rhythms, and neuroendocrine processes are key features of aging and neurodegeneration. These fundamental processes are regulated by the hypothalamus, yet how its functionally distinct subregions and cell types change during human aging and Alzheimer\'s Disease (AD) remains largely unexplored. Here, we present HypoAD, a comprehensive atlas of the human hypothalamus in aging and AD, integrating high-resolution MRI from 202 individuals with single-nucleus RNA-seq (snRNA-seq) of 614,403 nuclei from young, AD, and age-matched non-dementia controls. Our analysis reveals that hypothalamic subregions governing metabolism, stress, and circadian rhythms are particularly vulnerable, exhibiting significant changes in both volumes and gene expression during aging and AD. At the molecular level, machine learning models identified the inflammatory response and regulators of circadian rhythms as key cellular predictors of AD. These signatures were reflected in specific cell types: microglia transitioned to a pro-inflammatory state, while inhibitory neurons within sleep- and circadian-regulating hypothalamic subregions showed the most profound transcriptional alterations, including disruptions in ligand-receptor interactions and G-protein-coupled receptor signaling. Together, HypoAD provides a high-resolution volumetric map and a comprehensive transcriptomic atlas of the human hypothalamus in aging and AD, linking lifestyle and behavioral changes to their underlying volumetric and molecular pathways. Additionally, HypoAD provides a framework to investigate hypothalamic dysfunction and establishes a roadmap for targeted interventions aimed at mitigating physiological disruptions to potentially slow disease progression.

Aging is associated with increased susceptibility to bacterial infections, particularly multidrug-resistant (MDR) strains, which often result in antibiotic treatment failure and high mortality rates in the elderly. However, effective preventive and therapeutic strategies remain limited. Herein, we showed that aged mice exhibited higher susceptibility to colistin-resistant Salmonella enterica serotype Typhimurium and methicillin-resistant Staphylococcus aureus compared to young mice. Notably, pre-supplementation with melatonin, a hormone markedly reduced in the aging gut, effectively restricted MDR bacterial infections in aged mice by enhancing microbial colonization resistance. Mechanistically, melatonin-induced alterations in the gut microbiota, particularly the enrichment of butyrate-producing bacteria including Faecalibaculum, Muribaculaceae, and Ruminococcus, played a pivotal role in enhancing resistance to pathogenic bacteria. Elevated gut butyrate levels following melatonin pre-supplementation not only preserved intestinal barrier integrity and mitigated inflammaging, but also directly inhibited pathogenic bacterial growth by disrupting intracellular pH homeostasis, leading to proton motive force dissipation and metabolic disturbances. These findings underscore melatonin and its metabolite, butyrate, as promising candidates for the prevention of MDR bacterial infections in the aging population.

Calcium (Ca2+) homeostasis is fundamental to neuronal physiology, including in the regulation of membrane excitability and synaptic transmission. Disruptions in the ion transporters regulating Ca2+ influx and efflux are clearly linked to seizure disorders and age-related neurodegenerative disease. Yet, the specific contributions of variants in genes encoding these transporters to neurological disease remain to be fully understood. Drosophila melanogaster has proven to be a powerful genetic model for uncovering such mechanisms, particularly through studies of mutants that display temperature-sensitive (TS) behavioral phenotypes. In a forward genetic screen, we identified a mutant line that exhibited TS convulsions along with progressive, age-dependent neurodegeneration. We mapped the mutation to Nckx30c, specifically within the transmembrane ion-binding region of this K+-dependent Na+/Ca2+ exchanger. Characterization of this mutant, together with a second Nckx30c allele, revealed TS convulsions, impaired locomotion, a markedly shortened lifespan, neurodegeneration with age, along with structural defects at larval and adult neuromuscular junctions (NMJs). Gene expression analysis confirmed that Nckx30c levels were reduced in heads of Nckx30c loss-of-function mutants. Tissue-specific manipulation revealed that knockdown of Nckx30c in neurons recapitulated the TS convulsions, locomotor defects, and shortened lifespan phenotypes. Drosophila Nckx30c is highly conserved and shares homology with mammalian SLC24A2, a solute carrier family 24 member whose neurological role is not yet fully elucidated. Our work establishes Nckx30c as an essential regulator of neuronal health and provides an in vivo framework for investigating the contribution of SLC24A2 to neuronal Ca2+ homeostasis, seizures and age-related neurodegeneration.

Falls are one of the leading causes of non-disease death and injury in the elderly, partly due to the loss of muscle mass in a musculoskeletal disorder named sarcopenia. Studying the impact of this muscle weakness on standing balance through direct human experimentation poses ethical dilemmas, involves high costs, and fails to fully capture the internal dynamics of the muscle. To address these limitations, we employ neuromusculoskeletal modeling to explore the impact of sarcopenia on balance. In this study, we introduce a novel full-body MSK model comprising both the torso and lower limbs, with 290 muscle actuators controlling 23 degrees of freedom and supporting varying levels of sarcopenia. Using reinforcement learning coupled with curriculum learning and muscle synergy representations, we trained an agent to perform standing balance on a backward-sliding plate and compared its behavior to human experiments. Our results demonstrate that, without pre-recorded experimental data, both healthy and sarcopenic agents can reproduce ankle and hip balancing strategies consistent with experimental findings. Furthermore, we show that as the degree of sarcopenia increases, the agent adapts its balancing strategy based on the platform's acceleration. The full code is open-sourced and can be found in this repository: https://github.com/cherylwang20/StandingBalance.

The preservation of tissue architecture and morphology in formalin-fixed paraffin-embedded (FFPE) tissues enables spatial resolution at the cellular and sub-cellular levels. Laser capture microdissection (LCM) combined with liquid chromatography tandem mass spectrometry analysis permits collection of tissue areas with spatial context for proteome profiling from FFPE slides. In this study, we performed proteome profiling of non-diseased renal tubulointerstitial tissue in a cohort of young (< 40 years) and old (> 70 years) individuals with the goal of spatially correlating the histomorphology to the proteomic profile. To perform in-depth characterization of renal tubulointerstitium and to identify renal aging-associated proteins, a multiplexing strategy using tandem mass tags (TMT) was employed, resulting in the quantitation of 7,355 proteins. Our approach allowed for identification of proteins with low abundance such as fibrocystin and ninein-like protein. Notably, 162 solute carrier proteins from 47 solute carrier families were identified, which were enriched in proximal and distal tubule cells. Finally, we discovered a proteomic signature associated with renal aging, which includes metalloproteinase inhibitor 3, nicotinamide N-methyltransferase, matrix metallopeptidase 7, phenazine biosynthesis-like domain-containing protein and solute carrier family 23 member 1. Overall, our study demonstrates the power of LCM combined with proteomics to leverage archived FFPE tissue samples for investigating proteomic alterations in the renal tubulointerstitium with age at a high depth of proteome coverage.

Within each cell, metabolite-sensing factors respond to coordinate metabolic homeostasis. How metabolic homeostasis is regulated intercellularly and how this may become dysregulated with age, however, remains underexplored. Here we describe a system regulated by a metabolite sensor, CtBP2. CtBP2 is secreted via exosomes in response to reductive metabolism, which is suppressed by oxidative stress. Exosomal CtBP2 administration extends lifespan in aged mice and improves healthspan in particular by reducing frailty. Mechanistically, we identify activation of CYB5R3 and AMPK downstream of exosomal CtBP2. Consistently, serum CtBP2 levels decrease with age and are negatively associated with cardiovascular disease incidence in humans yet are elevated in individuals from families with a history of longevity. Together our findings define a CtBP2-mediated metabolic system with potential for future clinical applications.

Mitochondrial dysfunction-mediated ribosomal translation suppression is a hallmark of aging and a major driver of degenerative diseases, limiting mRNA therapy efficacy. Here, ionizable coenzyme Q10 (iCoQ10)-engineered lipid/fiber microplexes (iCLNP@SF) are developed that restore the mitochondrial-ribosomal axis to enhance mRNA translation. iCoQ10 replaces conventional ionizable lipids to form prodrugged lipid nanoparticles (iCLNP), stabilized by injectable polydopamine‑modified short fibers for in situ administration. In vitro efficacy assessments showed that iCLNP@SF synergistically enhanced mitochondrial metabolism and mRNA translation in senescent cells. Further mechanistic studies revealed that iCLNP stabilized mitochondrial membrane potential, suppressed cGAS-STING activation, and reduced eIF2α phosphorylation, thereby enhancing translation. In vivo, iCLNP@SF delivery of Gas6 mRNA increased hair follicle density by ≈50% in an androgenetic alopecia mouse model, while Runx2 mRNA delivery raised new bone formation (BV/TV) to ≈40% in defect models, both markedly outperforming conventional LNPs. Together, these findings highlight a strategy that improves mRNA therapy for degenerative diseases.

Phytochemicals represent emerging anti-aging therapeutic candidates, with Marchantia polymorpha L. (liverwort) gaining significant attention due to its broad-spectrum pharmacological properties. This plant exhibits remarkable wound-healing and regenerative capabilities, making it a promising candidate for the development of modern anti-aging drugs. In the presented study, 12-ethoxy-Marchantin A (EMA), a new macrocyclic bis-bibenzyl compound, was isolated and identified from M. polymorpha. Using a Lipopolysaccharide (LPS)-induced mouse macrophage RAW264.7 macrophage model, a Caenorhabditis elegans (C. elegans) aging model, and network pharmacology analysis, we systematically investigated the pharmacological mechanisms underlying its anti-aging effects. Our results demonstrated that EMA significantly reduced inflammatory cytokines and nitric oxide (NO) in LPS-stimulated RAW264.7 cells via the nuclear factor erythroid 2-related factor 2 (Nrf2) / heme oxygenase (HO-1) pathway. Mechanistically, EMA triggered a reactive oxygen species (ROS)-mediated mitogen-activated protein kinase (MAPK)-dependent Nrf2 antioxidant signaling cascade. EMA significantly extended the lifespan and enhanced fecundity in the N2 strain of C. elegans, while reducing lipofuscin deposition and ROS levels. Additionally, EMA enhanced oxidative and heat stress resistance in the N2 strain of C. elegans. Network pharmacology revealed that its anti-aging effects may be mediated by MAPKs/Nrf2/HO-1 pathway regulation. Collectively, these findings highlight EMA as a potent anti-aging with therapeutic potential for aging-related conditions.

The shortage of liver donors for liver transplantation is currently an urgent problem. Elderly donors have become an important source of donor livers, but they are more prone to ischemia reperfusion injury (IRI) in liver transplantation. Therefore, exploring the effects and mechanisms of aging on liver IRI will provide a new theoretical basis for improving the survival rate of liver transplant patients. We constructed a mouse model of liver ischemia for 90 min and reperfusion for 6 or 24 h, and found that compared with young liver, the recovery of liver function in aged liver after IRI was slower. Detection of macrophage pyroptosis revealed that it was an important factor for aging deferring liver function restoration. Mechanistically, we demonstrated that aging triggered mitochondrial permeability transition pore (mPTP) channel opening to promote the release of Oxidized mtDNA (Ox-mtDNA), thereby inducing macrophage pyroptosis. Moreover, the activity of mPTP channel was mainly dependent on calcium uptake by acetylated mitochondrial calcium uniporter (MCU). These results illustrated that cytoplasmic Ox-mtDNA-induced macrophage pyroptosis was a key factor for aging exacerbating liver IRI. Calcium uptake via acetylated MCU triggered mPTP channel opening, which is an important mechanism for Ox-mtDNA release from mitochondria into the cytoplasm.

Chrysin (5,7-dihydroxyflavone), a natural flavonoid present in honey, propolis, and various medicinal plants, has shown promise as a calorie restriction mimetic (CRM) through its glycolysis-inhibiting action. This inhibition promotes a metabolic shift toward oxidative phosphorylation and fatty acid oxidation, potentially activating beneficial pathways like AMPK and SIRT1. The mechanism likely involves the downregulation of Hexokinase-2, leading to suppressed glycolysis and promotion of apoptosis. In this study, we assessed aging biomarkers in erythrocytes, plasma, and serum after administering chrysin (100 mg/kg, orally) and D-galactose (300 mg/kg, subcutaneously) for four weeks to Wistar rats. In the D-galactose-induced aging rat model, the markers of oxidative damage, such as protein carbonyls, malondialdehyde, and advanced oxidation protein products, were found to be elevated. However, chrysin treatment significantly upregulated antioxidant defenses, including catalase, superoxide dismutase, ferric-reducing antioxidant power (FRAP), and glutathione (GSH). Administration of chrysin to aged rats led to a decline in both inflammatory biomarkers and insulin concentrations. These findings suggest that chrysin can alleviate oxidative stress, reduce lipid peroxidation, and influence inflammation and metabolism, highlighting its potential as an anti-aging therapeutic agent. This study underscores the potential of chrysin as a natural calorie restriction mimetic, mainly by maintaining redox balance by impacting longevity pathways and metabolic health.

Sarcopenia, a degenerative condition marked by progressive skeletal muscle atrophy and impaired regeneration, is closely associated with aging, chronic inflammation, and disrupted proteostasis. While macroautophagy has been extensively studied in this context, little of the role of chaperone-mediated autophagy (CMA) has been known. In this study, we identified C1q/TNF-related protein 9 (CTRP9) as a novel autocrine myokine secreted by skeletal muscle that exerts dual protective functions-pro-differentiative and anti-atrophic. By using a replicative senescence model in C2C12 myoblasts, we observed that CTRP9 expression declined with cellular aging, accompanied by reduced levels of lysosome-associated membrane protein type 2A (LAMP2A), increased nucleotide-binding domain, leucine-rich-containing family, and pyrin domain-containing-3 (NLRP3) accumulation, and elevated interleukin-1β (IL-1β) secretion. Similar molecular signatures were detected in skeletal muscle tissues of CTRP9 knockout (KO) mice, further validating its role in vivo. Treatment with the biologically active globular domain of CTRP9 (gCTRP9) restored LAMP2A expression, enhanced CMA activity, and promoted selective degradation of NLRP3, thereby alleviating inflammatory stress and cellular senescence. Functionally, gCTRP9 restored myogenic differentiation markers (e.g., MYOD1) while suppressing atrophy-related genes (e.g., Fbxo32) and improving fusion potential and myotube integrity. In primary human myoblasts isolated from elderly individuals, CTRP9 and LAMP2A were significantly downregulated, and NLRP3 expression was increased-changes that were partially reversed upon gCTRP9 treatment. These findings collectively demonstrate that the CTRP9-LAMP2A-NLRP3 axis plays a pivotal role in regulating both muscle regeneration and maintenance. By targeting CMA-mediated NLRP3 degradation, CTRP9 offers a promising therapeutic strategy for combating sarcopenia through coordinated modulation of differentiation pathways and muscle atrophy.

Clonal haematopoiesis (CH) arises from the expansion of hematopoietic stem cells (HSCs) carrying leukaemia-associated somatic mutations. CH is linked to pathological immune dysregulation and a greater risk of age-related inflammatory diseases. Yet, how CH mutations impact HSC differentiation into immune effector cells remains understudied. Here, we report a single-cell resolution functional and multi-omic investigation of HSC clonal and differentiation dynamics in individuals with DNMT3A-R882 CH. DNMT3A-R882 reshapes the clonal architecture of haematopoiesis towards an aged phylogenetic structure. Functionally, DNMT3A-R882 HSCs produce decreased monocytic output but more abundant and mature neutrophil progeny compared to WT HSCs in the same individual. Whereas DNMT3A-R882 myeloid progenitors display attenuated inflammatory transcriptional programmes, DNMT3A-R882 mature neutrophils acquire proinflammatory and immunomodulatory features typical of maladaptive immunity and CH co-morbidities. Our findings, validated in humanised mice, identify aberrant DNMT3A-R882 HSC-driven neutropoiesis as a key link between CH, immune dysregulation and risk of inflammatory disease.

The cerebellum undergoes significant age-related changes linked to poor balance in older adults. Although multi-session cerebellar iTBS combined with rehabilitation has been used in some clinical populations, its isolated effects in community-dwelling healthy older adults remain unknown, particularly in context of balance control and underlying cerebellar-motor cortex (M1) interactions. We tested whether a single-session, sham-controlled, cerebellar iTBS-only intervention could modulate balance and cerebellar-motor cortex (M1) interactions in community-dwelling older adults without neurological disease. The effects of cerebellar intermittent theta-burst stimulation (iTBS) on balance control and underlying cerebellar-motor cortex (M1) interactions in this population remain unclear. We investigated whether cerebellar iTBS led to [1] improved standing balance, and [2] changes in cerebellar-M1interactions measured using cerebellar brain inhibition (CBI) in older adults. Forty older adults were randomized to receive Active (n = 20) or Sham (n = 20) iTBS to the right lateral cerebellum. We measured postural sway (95% ellipse area of the center of pressure) during standing and CBI before iTBS and at multiple time points up to 30 min post-stimulation. Compared to sham, a single session of active iTBS reduced postural sway, with balance improvements sustained for at least 30 min post-stimulation. Cerebellar iTBS did not significantly alter CBI. Our results support the neuroplastic potential of the cerebellum as a viable target for therapeutic interventions aimed at improving balance in aging, potentially influencing circuits beyond direct cerebellar-M1 motor pathways.

Background: Occupational exposure to exhaust fumes, containing neurotoxic particulate matter and polycyclic aromatic hydrocarbons (PAHs), is associated with cardiopulmonary diseases, but its cognitive effects in aging workers remain insufficiently studied. Given increasing occupational longevity, understanding these risks is critical for dementia prevention. Methods: We analyzed data from 1,110 adults aged 60 years and older in the 2011 to 2012 National Health and Nutrition Examination Survey (NHANES), comparing cognitive performance between exposed (24%) and unexposed groups. Cognitive function was assessed using the Consortium to Establish a Registry for Alzheimers Disease Word List Learning Test (CERAD WL), Animal Fluency Test (AFT), and Digit Symbol Substitution Test (DSST). Distributed lag nonlinear models (DLNMs) evaluated nonlinear and time lagged effects of exposure duration. Results: Exposed workers were predominantly male (81.6% vs. 41.8%), had lower educational attainment (31.2% vs. 24.4% with less than high school education), and exhibited higher rates of smoking (65.0% vs. 48.6%) and excessive alcohol use (15.7% vs. 7.0%). Occupational exposure was associated with significant cognitive impairments in delayed memory (odds ratio [OR] = 2.55, 95% confidence interval [CI]: 1.61 4.05), verbal fluency (OR 2.41, 1.48 3.94), and processing speed (OR 1.95, 1.19 3.18). The DLNM analyses revealed a biphasic response: minimal effects at <20 years of exposure, but major declines after 30 years, with a 15 to 25 years latency period. Conclusion: Prolonged occupational exhaust fume exposure is associated with domain specific cognitive decline, particularly affecting memory and executive function. The dose response relationship underscores cumulative neurotoxicity, emphasizing the need for targeted protections for high-exposure workers.

Mitochondrial networks exhibit remarkable dynamics that are driven in part by fission and fusion events. However, there are other reorganizations of the network that do not involve fission and fusion. One such exception is the elusive, "beads-on-a-string" morphological transition of mitochondria. During such transitions, the cylindrical tubes of the mitochondrial membrane transiently undergo shape changes to a string of "pearls" connected along thin tubes. These dynamics have been observed in many contexts and given disparate explanations. Here we unify these observations by proposing a common underlying mechanism based on the biophysical properties of tubular fluid membranes for which it is known that, under particular regimes of tension and pressure, membranes reach an instability and undergo a shape transition to a string of connected pearls. First, we use high-speed light-sheet microscopy to show that transient, short-lived pearling events occur spontaneously in the mitochondrial network in every cell type we have examined, including during T cell activation, neuronal firing, and replicative senescence. This high-temporal data reveals two distinct classes of spontaneous pearling, triggered either by ionic flux or cytoskeleton tension. We then induce pearling with chemical, genetic, and mechanical perturbations and establish three main physical causes of mitochondrial pearling, i) ionic flux producing internal osmotic pressure, ii) membrane packing lowering bending elasticity, and iii) external mechanical force increasing membrane tension. Pearling dynamics thereby reveal a fundamental biophysical facet of mitochondrial biology. We suggest that pearling should take its place beside fission and fusion as a key process of mitochondrial dynamics, with implications for physiology, disease, and aging.

Organisms must constantly respond to stress to maintain homeostasis, and the successful implementation of cellular stress responses is directly linked to lifespan regulation. In this Review we examine how three age-associated stressors-loss of proteostasis, oxidative damage and dysregulated nutrient sensing-alter protein synthesis. We describe how these stressors inflict cellular damage via their effects on translation and how translational changes can serve as both sensors and responses to the stressor. Finally, we compare stress-induced translational programmes to protein synthesis alterations that occur with age and discuss whether these changes are adaptive or deleterious to longevity and healthy ageing.

Telomeres are essential for maintaining genomic integrity and are associated with cellular aging and disease, yet the factors influencing their inheritance across generations remain poorly understood. Leveraging PacBio HiFi long-read sequencing and 75 parent-offspring trios (n = 225) from the Genomic Answers for Kids program, we analyzed individual telomeres across chromosomes and their inheritance. Telomere length (TL) varied between chromosome arms in a way that was consistent in parents and offsprings, with average values ranging from 5000 to 8000 base pairs. Maternal and paternal TL together were a strong predictor of child TL (R2= 0.59). Notably, using telomeric variant repeats, we developed a tool that enabled allelic tracing for 53.3% of maternally and 49.9% of paternally inherited telomeres. In the child, paternally transmitted alleles were significantly longer than age-matched maternal ones ({Delta}mean = 409 bp, p = 2.6e-05), particularly when from older parents ({Delta}mean = 698 bp, p = 8.9e-05) and at chromosome arms with shorter average TL ({Delta}mean = 752 bp, p = 1.6e-06). These findings reveal parent-of-origin effects and heritable influences on TL, providing novel insights into telomere dynamics and their potential implications in age-related disease susceptibility.

Aged hematopoietic stem cells (HSCs) expand in clusters over time, while reducing their regenerative capacity and their ability to preserve the homeostasis of the hematopoietic system. The expression of Notch ligands in the bone marrow (BM) niche is essential for hematopoiesis. However, the impact of Notch signaling for adult HSC function and its involvement in HSC aging remains controversial. Here we show that Notch activation in young HSCs is not homogeneous, and it is triggered by sinusoidal expression of the Notch ligand Jagged2 (Jag2). Sinusoidal Jag2 deletion in young mice recapitulates the decrease in Notch activity observed in aged HSCs and alters HSC divisional symmetry and fate priming, promoting myeloid-biased HSCs (My-HSCs) expansion. Mechanistically, our data reveals that upon decreasing sinusoidal Jag2 expression, HSCs themselves upregulate Jag2, which cis-inhibits Notch signaling, resulting in the expansion of My-HSCs and in reduced hematopoietic regeneration. Collectively, these findings identify the crosstalk between BM niche-driven and HSC intrinsic features in regulating HSC fate priming and regenerative potential and reveal an extrinsic Notch trans-activation to intrinsic cis-inhibition switch underlying HSC aging.

Methylation-based epigenetic clocks are among the most accurate tools for predicting chronological age. Although DNA methylation (DNAm) at genomic CpG sites is linked to various regulatory mechanisms, the biological interpretability of epigenetic clocks remains surprisingly limited. One primary mechanism by which DNAm is thought to influence gene regulation is by modulating transcription factor binding activity. In this study, we examine established epigenetic clocks to assess the regulatory potential of their predictive CpGs during the aging process. Our analysis reveals that generally most CpG sites used by epigenetic clocks do not overlap known transcription factor binding sites (TFBSs), indicating that changes in TFBS dynamics may not account for prediction accuracy of these models. On the other hand, by identifying age-associated CpGs that overlap TFBSs, we identified transcription factors that may be involved in the aging process. Specifically, the TFBSs of ZBED1, NFE2, CEBPB, FOXP1, EGR1, SP1, PAX5, and MAZ were particularly enriched for age-associated CpGs, while RBPJ, NFIC, RELA, IKZF1, STAT3, and USF2 were significantly protected against methylation changes. By focusing on TFBS-associated CpGs, combined with additional feature selection and engineering steps, we developed an alternative, TFMethyl Clock model, outperforming several existing approaches. Target genes of model-selected, age-predictive CpGs are enriched in the interleukin-1{beta} production and long-chain fatty acid metabolism pathways. In contrast, these CpGs themselves are enriched mainly at binding sites of NR2C2 TF. Furthermore, approximately three-fourths of the target genes downstream of age-predictive CpGs exhibit significant age-related changes, suggesting that our approach captures deeper insights into possible methylation-driven biological aging processes. Our findings demonstrate that incorporating regulatory loci into the design of epigenetic predictors may provide mechanistic insights into the aging process while maintaining or even improving the predictive power.

Variation in the gene for apolipoprotein E (APOE) is one of the few variables that is associated with individual differences in age-related cognitive decline in humans. Therefore, it is important to understand the conditions that affect the strength of its effect. Here we examine how the effect size of APOE variation (possession of one or more e4 alleles) on a test of general cognitive ability changes with age from 11-90 years. The data are from the Lothian Birth Cohorts of 1936 and 1921 who took the same cognitive test (the Moray House Test No. 12) at, respectively, ages 11 (N = 954), 70 (N = 1001), 76 (N = 636), 79 (N = 471), and 11 (N = 483), 79 (N = 533), 87 (N = 198), 90 (N = 120). The standardised absolute effect of APOE e4 on general cognitive ability was about zero at ages 11 (beta < 0.05) and 70 (beta ≤ 0.025) and increased linearly to beta = 0.30 (p < 0.001) at age 90. The effect sizes were minimally affected by adjusting for medical conditions (hypertension, diabetes, cardiovascular disease, stroke). However, the results were less robust to removing those participants who developed dementia; effect sizes were reduced by about a third to a half, and were largely non-significant. The results suggest that the negative effect of APOE e4 on cognitive functioning becomes greater with age; this urges more work to understand the mechanisms by which e4 status renders the older person's brain increasingly vulnerable to cognitive decline and dementia.

Sarcopenia and obesity, two prevalent metabolic disorders in aging populations, often coexist and share overlapping pathophysiological mechanisms, yet the molecular mechanisms underlying their comorbidity remain elusive. This study aimed to identify key gene expression signatures and pathways underlying their comorbidity through integrative transcriptomic and bioinformatics analyses. Gene expression datasets from sarcopenia (GSE111016, skeletal muscle) and obesity (GSE152991, adipose tissue) were downloaded from the GEO database. Differentially expressed genes (DEGs) were identified using the limma package, and 208 common differentially expressed genes (CDEGs) were selected via Venn diagram intersection. Functional enrichment analyses (GO and KEGG) were performed to explore shared biological processes and pathways. A protein-protein interaction (PPI) network was constructed using STRING and Cytoscape, and key CDEGs were identified via ten topological algorithms (e.g., MCC, Degree) in the CycloHubba plugin. Pearson correlation analysis and qPCR were used to validate gene co-expression patterns and expression levels in tissue samples. GO and KEGG analyses revealed that CDEGs were significantly enriched in mitochondrial oxidative phosphorylation, electron transport chain, and thermogenesis pathways, with overlap in neurodegenerative disease pathways. The PPI network and multi-algorithm integration identified four key CDEGs: SDHB, SDHD, ATP5F1A, and ATP5F1B, all of which are components of mitochondrial respiratory chain complexes. These genes exhibited strong positive correlations (r > 0.86, p < 10⁻¹²) in both datasets and were significantly downregulated in sarcopenia and obesity tissues, as validated by qPCR. This study confirms mitochondrial dysfunction, particularly impaired oxidative phosphorylation, as a common pathological mechanism linking sarcopenia and obesity. The key genes SDHB, SDHD, ATP5F1A, and ATP5F1B represent potential therapeutic targets for managing these comorbid metabolic disorders. Future research should explore their functional roles in energy metabolism and cross-tissue crosstalk to develop targeted interventions.

Cardiorespiratory fitness (CRF) is a powerful predictor of cardiovascular events and overall mortality, often surpassing traditional risk factors in prognostic value. However, its clinical use remains limited because current assessments rely on specialized equipment, trained personnel, and lengthy procedures that are often impractical for broad or routine application, especially in at-risk populations. Because CRF is closely tied to vascular health, surrogate measures that capture vascular features may offer a practical alternative for its estimation. Retinal Color Fundus Images (CFIs) provide a non-invasive window into systemic vascular health and have already demonstrated their utility in predicting cardiovascular risk factors and diseases, yet CFIs have yet to be explored for their potential to predict CRF. In this study, we develop RetFit, a novel CRF estimator derived from CFIs by leveraging state-of-the-art vision transformers. RetFit enables a non-invasive, easy-to-acquire CRF proxy, addressing some of the limitations inherent to standard CRF measures and linking retinal imaging to the cardiovascular system. We evaluated RetFit's clinical relevance by analyzing its associations with cardiovascular risk factors, disease outcomes, and exploring its genetic architecture, benchmarking it against a submaximal-exercise-test CRF (SETCRF) estimate. We find that RetFit is prognostic of both cardiovascular events (hazard ratios as low as 0.878, 95%CI 0.856 to 0.901, p<0.001) and overall mortality (hazard ratios as low as 0.780, 95%CI 0.754 to 0.801, p<0.001) and significantly associates with the majority of disease states and risk factors explored within our analysis. Although RetFit and SETCRF shared a moderate phenotypic correlation with each other (r=0.45), their significant genetic associations were disjoint. Interpretability analyses revealed that RetFit's predictions are driven by the retinal vasculature, with the number of arterial bifurcations showing the strongest association with RetFit ({beta}=0.287, 95%CI 0.263 to 0.311, p<0.001). These findings highlight the potential of retinal imaging as a scalable, cost-effective, and accessible alternative for CRF estimation, supporting its use in large-scale screening and risk stratification in both clinical and public health contexts.

The incidence of cardiovascular diseases rises significantly with age, making it one of the leading causes of death and disability worldwide, and cellular senescence plays a crucial role in this process. Cellular senescence constitutes a salient feature of organismal aging and stands as an independent risk factor for a range of cardiovascular diseases, encompassing hypertension, atherosclerosis, myocardial infarction, heart failure, and arrhythmia. This comprehensive review endeavors to comprehensively delineate the intricate regulatory mechanisms underlying cellular senescence and its attendant biological implications, while elucidating the profound implications of this process on the initiation and progression of cardiovascular diseases. Finally, we will delve into a spectrum of targeted interventions aimed at cellular senescence, specifically focusing on eliminating the accumulation of senescent cells during disease progression or inhibiting the inherent cellular senescence processes. Our ultimate goal is to mitigate or postpone the onset of diseases that are intricately linked to cellular senescence. A profound comprehension and rigorous investigation into the regulatory mechanisms of cellular senescence and their intricate interrelationships hold significant potential to furnish invaluable scientific evidence for the prevention and therapeutic strategies against cardiovascular diseases.

Identifying the drivers of cellular senescence that contribute to the decline in tissue function related to aging- and disease is critical for developing restorative interventions. Here, we investigated how increased mechanical stress from extracellular matrix (ECM) stiffening shapes endothelial cell (EC) senescence. We developed a 3D human in vitro model that decouples mechanical stress from inflammatory or biochemical inputs, enabling the study of senescence responses to tissue stiffening alone. We found that matrix stiffening induces an EC senescence phenotype with elevated p16/p21 and an immunomodulatory senescence-associated secretory phenotype (SASP), in the absence of inflammatory signals. This mechano-induced senescence state engaged a Notch-JNK-FOS signaling axis, and pharmacologic inhibition of Notch attenuated stiffness-induced senescence. Supporting the translational relevance of this mechanism, analysis of fibrotic capsule tissue from patients with synthetic breast implants, a model of localized, mechanically driven fibrosis, revealed increased p16+Notch1+ endothelial populations. Complementary single-cell RNA sequencing data confirmed their enrichment in Notch/JNK- and SASP-related gene programs. Together, these findings define vascular senescence as a mechanosensitive process and identify tissue stiffening as an upstream aging signal. Our work offers a human-relevant platform for studying targetable stages of endothelial mechanoaging.

Degenerative skeletal diseases, including osteoporosis, osteoarthritis, and intervertebral disc degeneration, are prevalent age-related conditions characterized by progressive tissue degeneration and functional decline. Histone modifications are covalent modifications of histone residues, catalyzed by specific enzymes, that modulate chromatin architecture and transcriptional activity. Accumulating evidence highlights the critical involvement of histone modifications in orchestrating disease-associated transcriptional programs. In osteoporosis, histone modifications regulate osteoblast and osteoclast differentiation, thereby disrupting bone homeostasis. In osteoarthritis, they drive the expression of matrix-degrading enzymes in chondrocytes, contributing to cartilage degradation. In intervertebral disc degeneration, they are implicated in nucleus pulposus cell senescence, apoptosis, and extracellular matrix degradation. This review summarizes the distinct mechanistic roles of histone modifications across these conditions and explores the therapeutic potential of targeting histone-modifying enzymes, underscoring epigenetic regulation as a promising strategy for precision intervention in degenerative skeletal diseases. The translational potential of this article: This review comprehensively explores the role of histone modifications in degenerative skeletal diseases and evaluates the potential of histone-modifying enzyme inhibitors as therapeutic targets. These insights provide new strategies and directions for the treatment of degenerative skeletal diseases.

The pro-inflammatory cytokine TNF-α plays a crucial role in promoting cellular senescence in chondrocytes, contributing to the pathological progression of osteoarthritis (OA). Relaxin-2, a biologically active peptide hormone with diverse effects, has been investigated for its potential protective role against TNF-α-induced cellular senescence in human primary chondrocytes. In this study, human primary chondrocytes were exposed to TNF-α (10ng/mL) with and without the presence of recombinant human relaxin-2 (rh relaxin-2). SA-β-gal staining indicated that rh relaxin-2 effectively mitigated TNF-α-induced cellular senescence in these cells. Furthermore, rh relaxin-2 enhanced telomerase activity and prevented cell cycle arrest at the G0/G1 phase induced by TNF-α. Additionally, rh relaxin-2 reduced the expression levels of plasminogen activator Inhibitor-1 (PAI-1) and p21, key regulators of cellular senescence. Interestingly, TNF-α increased K382 acetylation of p53 but decreased SIRT1 expression. Notably, knocking down SIRT1 negated the protective effects of rh relaxin-2 on cellular senescence, suggesting that SIRT1 is involved in mediating the protective effects of rh relaxin-2. These findings provide new insights into the potential therapeutic use of rh relaxin-2 for OA treatment through a novel mechanism.

Background & Aims The liver is a vital organ composed of parenchymal, nonparenchymal, and immune cell populations. Single-cell sequencing approaches now provide the opportunity to understand how sex and age influence gene expression and cellular function across cell types within the liver. Methods We analyzed the cellular composition and interactions for the human liver through single-nucleus RNA sequencing (snRNA-seq), incorporating insights from 37 healthy liver samples. The dataset contains cells from female and male donors spanning more than seven decades of life, and analysis was performed to evaluate the impact of sex and age on differential gene expression, pathway enrichment, and predicted ligand-receptor and protein-protein interactions. Results Excluding the X and Y chromosomes, we identified 374 genes uniquely enriched in cells of the female liver and 520 genes enriched in cells of the male liver. Differential expression analysis defined unique circuitries enriched within each cell type between females and males and their impact on cell-cell communication and response to external signals, including enrichment of cholesterol/lipid metabolism, transforming growth factor beta (TGF-beta) signaling, and fibronectin (FN1) production in female cells and bone morphogenic protein (BMP) signaling in male cells. With increased age, we observe a greater diversity in gene expression, including enrichment of genes that regulate neuregulin (NGR) signaling at older ages, while genes regulating insulin growth factor (IGF) signaling are enriched at younger ages. Senescence signatures were also identified for each cell type within the liver. Conclusions These results define the activities of healthy cell types within the liver across sex and age and provide a foundation for studies to examine how ancestry, geography, and disease states influence liver function within these contexts. Impact and Implications Our study analyzes 37 human liver samples at the single-cell level to understand how sex and age influence gene expression, cell interactions, and response to signals across liver cell types and sub-types. These findings are of particular significance for researchers who need to understand how sex and age may influence the response of individual cell types to injury or treatment of injury. This dataset will also provide a healthy reference for future studies to understand how ancestry, geography, and disease states shape liver biology across age and sex.