Fight Aging!

Nuclear DNA is surrounded by transcriptional machinery, protein structures that will attempt to transcribe any gene sequence they encounter. Where DNA is compacted into regions of heterochromatin by being spooled onto histones, genes are silenced because their sequences are hidden from transcriptional machinery. Whether a given stretch of DNA is compacted or not is determined by epigenetic mechanisms, largely decorations (such as methyl groups) attached to DNA and histones that alter their structural behavior. A general feature of aging is a loss of heterochromatin and increasing expression of genes and other sequences that are usually silenced in youth. This leads to, for example, the expression of transposons that can drive DNA damage and inflammation, but also disruption and change in normal cell function.

Some time ago, researchers established a way to visualize whether or not a given region of DNA is compacted into heterochromatin. Flies can be genetically engineered with suitably placed genes that change the color of some of their features, such as eye segments, depending on whether or not they are expressed. Thus just by looking at the fly, researchers will know whether or not the region of DNA containing the inserted gene is compacted. A number of different fly lineages have been constructed over the years, as researchers needed a solution for one region or another. This approach is called position effect variegation.

Today's open acccess paper is a discussion of position effect variegation as a tool to inspect changes in DNA compaction into heterochromatin that occur with age and their correlation with high level outcomes such as mortality risk and longevity. Since increased loss of heretochromatin appears to correlate with longevity in flies, position effect variegation could be used to build aging clocks (in flies at least) that primarily reflect alterations to DNA structure rather than other mechanisms.

Position effect variegation (PEV) as an aging clock: visualization of age-dependent loss of heterochromatin and longevity associated with enhanced heterochromatin

The heterochromatin loss model of aging suggests there is an age-dependent reduction in epigenetic factors that form and maintain the heterochromatin state of chromosomes. Position Effect Variegation (PEV) can visually report phenotypes of heterochromatin mediated silencing in Drosophila Melanogaster eyes and we use PEV to examine the association between heterochromatin state changes and aging.

Pericentric inserts causing PEV showed suppressed variegation phenotypes in old age compared to young age and were confirmed to be associated with progressively increasing transcription, indicating loss of heterochromatin mediated silencing. Within a single population, animals with enhanced PEV phenotypes live longer than those with more suppressed PEV phenotypes, suggesting that small differences in environmental or genetic factors within this population could be responsible for differences in heterochromatin and lifespan.

Environmental factors could enhance heterochromatin, reduced nutrient diet and lower temperature coincided with enhanced heterochromatin and longer life. Furthermore, genetic variants associated with long life, including chico mutants, lead to increased heterochromatin and enhanced PEV phenotypes. Therefore, aging can be linked to heterochromatin loss and developmental increases in heterochromatin are associated with longevity. Thus, PEV reporters act as aging clocks demonstrating loss of heterochromatin that progresses with age and epigenetic alterations that can promote longevity.

The addition and removal of methyl groups from specific locations on the genome is one of the epigenetic mechanisms used to control the structure of DNA in the cell nucleus, such as which sequences are hidden via compaction into heterochromatin and which remain accessible to allow the expression of genes. That the pattern of DNA methylation changes with age in characteristic ways is what allows the existence of epigenetic clocks, the use of DNA methylation status to assess biological age. That epigenetic control over gene expression changes with age also makes it a potential target for the development of therapies to treat aging, particularly now that partial reprogramming studies have amply demonstrated that reversing age-related epigenetic changes is possible in principle.

As individuals age, the precise regulation of DNA methylation gradually deteriorates, leading to widespread epigenetic drift. This loss of control results in both global hypomethylation and site-specific hypermethylation, disrupting normal gene expression patterns. Global hypomethylation can lead to genomic instability, activation of transposable elements, and oncogene expression, while localized hypermethylation may silence tumor suppressor genes or genes critical for immune regulation and metabolic function. These changes are increasingly recognized as contributors to the development of chronic diseases. For example, aberrant DNA methylation patterns have been implicated in cancer, cardiovascular disease, type 2 diabetes, and neurodegenerative disorders such as Alzheimer's disease.

One of the most promising trends is the integration of DNA methylation data with other layers of biological information, such as transcriptomics, proteomics, metabolomics, and microbiomics. This multi-omics approach offers a holistic view of aging by capturing complex molecular interactions/network that DNA methylation alone cannot fully explain. Combining these datasets can refine biological age estimates, identify novel aging biomarkers, and uncover mechanisms driving age-related functional decline.

Parallel to these analytical advances, there is growing interest in interventions targeting epigenetic aging. Lifestyle modifications, including diet, exercise, and stress management, have demonstrated potential to modulate DNA methylation patterns and slow epigenetic age acceleration. Pharmacological approaches, such as senolytics, epigenetic modulators, and novel small molecules, are under investigation for their ability to reverse or delay methylation-based biological aging. Clinical trials integrating methylation clocks as endpoints are beginning to evaluate the efficacy of these interventions, potentially enabling real-time monitoring of biological age and intervention impact.

Link: https://doi.org/10.3389/fmolb.2025.1734464

Rapamycin is the most well studied of the mTOR inhibitors. It produces immunosuppression at high doses, and has been used in this context in the clinic for more than twenty years. At lower doses it mimics aspects of the beneficial metabolic response to calorie restriction, om particular an increased operation of the cellular maintenance processes of autophagy. In animal studies this has been demonstrated to slow aging and extend healthy life. Human clinical trial data for this lower dose anti-aging usage remains relatively sparse, unfortunately, but the results that do exist are interesting.

Rapamycin is one of the most intensively studied compounds with potential effects on longevity. Available experimental data indicate that inhibition of the mTOR pathway and activation of autophagy lead to improved cellular homeostasis, reduced oxidative stress, and a slowing of aging processes across multiple model organisms.

Current clinical studies in humans, although limited in number and involving small populations, suggest that low doses of rapamycin may enhance immune function, reduce visible signs of skin aging, and positively influence well-being and metabolic parameters.

Despite these promising findings, knowledge regarding the long-term safety, efficacy, and optimal dosing regimens of rapamycin remains limited. Further, multicenter, randomized clinical trials are needed to determine whether modulation of the mTOR pathway can represent an effective and safe strategy to support healthy human aging.

Link: https://doi.org/10.7759/cureus.98514

Rapamycin and other mTOR inhibitors mimic some of the mechanisms making up the response to calorie restriction. Their most interesting effect is to increase the operation of autophagy in cells. Autophagy is a collection of processes responsible for recycling damaged or unwanted proteins and structures in the cell. A large proportion of the approaches shown to modestly slow aging in yeast, worms, flies, and mice are characterized by increased or more efficient autophagy; it is a universal response to stress of any sort placed upon a cell. Too much autophagy can be a bad thing, but a modest increase improves health in the context of the dysfunctional, damaged environment of aged tissues.

Another feature of mTOR inhibitors, and the age-slowing interventions that are characterized by upregulated autophagy, is that the burden of harmful, inflammatory senescent cells that linger in aged tissues is reduced. The present thinking on this topic is that this reduction does not occur because senescent cells are destroyed by the intervention, but rather that the pace at which cells become senescent is reduced. This seems sensible: more autophagy allows cells to better maintain function and resist damage, and thus fewer cells will be tipped over the line into senescence in response to damage.

Here, however, researchers argue that, at least in immune cells, the effects of mTOR inhibition on cellular senescence do not emerge from autophagy. Instead, there is a direct effect on the burden of DNA damage in these cells, and it is that reduced DNA damage that leads to a reduced number of cells becoming senescent. Further work will have to be conducted in order to fully understand how exactly mTOR inhibition produces this outcome.

Rapamycin Exerts Its Geroprotective Effects in the Ageing Human Immune System by Enhancing Resilience Against DNA Damage

mTOR inhibitors such as rapamycin are among the most robust life-extending interventions known, yet the mechanisms underlying their geroprotective effects in humans remain incompletely understood. At non-immunosuppressive doses, these drugs are senomorphic, that is, they mitigate cellular senescence, but whether they protect genome stability itself has been unclear. Given that DNA damage is a major driver of immune ageing, and immune decline accelerates whole-organism ageing, we tested whether mTOR inhibition enhances genome stability.

In human T cells exposed to acute genotoxic stress, we found that rapamycin and other mTOR inhibitors suppressed senescence not by slowing protein synthesis, halting cell division, or stimulating autophagy, but by directly reducing DNA lesional burden and improving cell survival. Ex vivo analysis of aged immune cells from healthy donors revealed a stark enrichment of markers for DNA damage, senescence, and mTORC hyperactivation, suggesting that human immune ageing may be amenable to intervention by low-dose mTOR inhibition.

To test this in vivo, we conducted a placebo-controlled experimental medicine study in older adults administered with low-dose rapamycin. p21, a marker of DNA damage-induced senescence, was significantly reduced in immune cells from the rapamycin compared to placebo group. These findings reveal a previously unrecognised role for mTOR inhibition: direct genoprotection. This mechanism may help explain rapamycin's exceptional geroprotective profile and opens new avenues for its use in contexts where genome instability drives pathology, ranging from healthy ageing, clinical radiation exposure and even the hazards of cosmic radiation in space travel.

Structures of the endoplasmic reticulum are where the folding of newly synthesized proteins takes place in the cell. The endoplasmic reticulum is also involved in a range of other activities relevant to the manufacture of proteins and other molecules, such as quality control and recycling of misfolded proteins. Researchers here describe how the endoplasmic reticulum changes in structure with age, and link this to changes in the recycling of endoplasmic reticulum structures via autophagy. They suggest that these changes are compensatory, but become maladaptive in later life.

The morphological dynamics of the endoplasmic reticulum (ER) have received little attention in the context of ageing. Here we established tools in C. elegans for high-resolution live imaging of ER networks in ageing metazoans, which revealed profound shifts in ER network morphology that are driven by autophagy of ER components (ER-phagy). Across a variety of tissues, we consistently found a decrease in ER protein levels and cellular ER volume, and a structural shift from densely packed sheets to diffuse tubular networks. The ER content also declined in yeast and mammalian systems, and proteomic atlases of the ageing process in worms and mammals showed that age-onset collapse in ER proteostasis function is a broadly conserved aspect of the ageing process

We found that Atg8-dependent ER-phagy is the key mechanism driving turnover and remodelling of the ER network during ageing. A targeted screen for mediators in C. elegans revealed that the physiological triggers of ER-phagy in an ageing metazoan model are cell-type specific. Tissue-specific roles of ER-phagy receptors may help to explain why the ubiquitous macroautophagy machinery seems to be a universal requirement for longevity assurance in metazoan genetic studies, whereas the importance of selective ER-phagy mediators has been slower to emerge. Subsequently, we demonstrate that the two pathways capable of blocking age-associated ER-phagy, TMEM-131 and IRE-1-XBP-1, are required for mTOR-dependent lifespan extension in C. elegans.

Importantly, not all changes that occur during ageing reflect pathogenesis. The earliest remodelling events are likely to be adaptive responses to the cessation of developmental programmes and rising metabolic and cellular damage. We propose a model where age-dependent ER remodelling serves as an adaptive step in the ageing process associated with reprogramming of the proteostasis network. However, although data indicate that the net effect of ER-phagy on lifespan is positive, we speculate that early pronounced remodelling of ER structures is likely to trigger pleiotropic trade-offs later, especially in longer-lived cells and animals.

Link: https://doi.org/10.1038/s41556-025-01860-1

In recent years, researchers have established that a great many proteins can aggregate to some degree in cells of the aging brain, and that this likely contributes to loss of function. This issue is distinct from the few well-known proteins such as amyloid-β that aggregate to a very large degree in the context of neurodegenerative conditions. Here, researchers provide evidence for this generalized aggregation across more than a thousand proteins to contribute to impaired maintenance of synapses in the aging brain.

Neurodegenerative diseases affect 1 in 12 people globally and remain incurable. Central to their pathogenesis is a loss of neuronal protein maintenance and the accumulation of protein aggregates with ageing. Here we engineered tools that enabled us to tag the nascent neuronal proteome and study its turnover with ageing, its propensity to aggregate and its interaction with microglia. We show that neuronal protein half-life approximately doubles on average between 4-month-old and 24-month-old mice, with the stability of individual proteins differing among brain regions. Furthermore, we describe the aged neuronal 'aggregome', which encompasses 1,726 proteins, nearly half of which show reduced degradation with age.

The aggregome includes well-known proteins linked to diseases and numerous proteins previously not associated with neurodegeneration. Notably, we demonstrate that neuronal proteins accumulate in aged microglia, with 54% also displaying reduced degradation and/or aggregation with age. Among these proteins, synaptic proteins are highly enriched, which suggests that there is a cascade of events that emerge from impaired synaptic protein turnover and aggregation to the disposal of these proteins, possibly through microglial engulfment of synapses. These findings reveal the substantial loss of neuronal proteome maintenance with ageing, which could be causal for age-related synapse loss and cognitive decline.

Link: https://doi.org/10.1038/s41586-025-09987-9

Cryonics refers to the low-temperature storage of the body (or at least the brain) at death to offer the chance that a more technologically capable future can restore that individual to life. It is an unknown chance, possibly a small and unknown chance, but cryonics is certainly a better option that the other end of life alternatives facing someone who is going to age to death before rejuvenation biotechnology and the medical control of aging becomes a reality. Cryonics remains a very good idea that should be far more widely used, significantly supported, and undergoing aggressive technological development to improve capabilities. But it is very far from being widely used and suffers from the same situation that afflicted the aging research community thirty years ago: a minority field with too little financial and popular support to generate the desired degree of progress.

Newfound enthusiasm for the development of means to treat aging has led to a vast (if very unevenly distributed) investment in the field, hundreds of companies working on all sorts of approaches. A tiny fraction of that enthusiasm for doing something to address age-related disease and mortality has spilled over into support for cryonics. Even that tiny fraction is proving to be transformative. I pick on Alcor as the example because I am signed up with Alcor, and therefore do pay more attention to what is going on there, but the field as a whole is showing progress. Europe has its own modern cryopreservation organization these days, Tomorrow.bio, their focus on customer service raising the bar for the community. Meanwhile Until Labs is working on making reversible vitrification of organs a commercial possibility, a best foot forward to generate further capital and legitimacy for cryonics.

After years of little visible progress and too little funding to improve on that situation, Alcor has of late acquired what is for a non-profit a sizable influx of capital. Enough to not just establish new research programs with new equipment, but to address look and feel and customer service priorities, such as a modernization of the website and creating a portal and modern relationship management system for their customers - and no doubt more under the hood than that. Alcor comes to the table with the DNA of decades of year to year struggle as a small non-profit serving a small community. Shedding some of those historical habits and culture will be necessary in order for a commercial industry of cryopreservation to emerge.

In a better world, this could have happened decades ago, driven by a broad popularist realization that cryopreservation to travel into a potentially far better future is the best of all options, turning an end into a hiatus. But it didn't. At least the first increments of such a sea change are happening now. A few excepts from a recent Alcor newsletter follow, for those who don't keep tabs on how this industry is modernizing.

Fundraising & Endowment: 2025 closed out as one of the stronger fundraising years in Alcor's history, including a major gift from the Rothblatt family - one of the largest individual donations Alcor has ever received. About 75% of donations came from people who hadn't given at that level before. The goal is to build an operational endowment similar to what exists for the Patient Care Trust, which is very healthy. The operations and administrative side, however, has historically struggled to keep pace. A comparable endowment would allow Alcor to focus on growth rather than making ends meet. Expect a significant fundraising initiative announcement in the near future.

First-Ever In-House Whole Body CT Scan: The team performed Alcor's first-ever in-house whole body CT scan. The scan itself went smoothly: they used the new ceiling trolley and hoist to transfer the patient from the perfusion table directly onto a radiotranslucent scanning tray, completed the scan in just a few minutes, transferred the patient back, and proceeded directly to cooldown. That patient is now in long-term storage. After everything it took to get here, it was well worth the wait. Being able to validate cryoprotectant distribution in-house and in real time opens up a lot of doors for quality assessment and research.

CT Scanning for Vitrification Assessment: we are putting the CT scanner to good use and have already started producing valuable data. Pre- and post-cooling scans show clear differences between frozen kidneys and vitrified kidneys. The next step: quantifying exactly how much ice forms in different regions using a newly purchased differential scanning calorimeter. This will let the team precisely correlate CT images with ice content - a tool that could become standard for assessing cryopreservation quality in organs and patients alike

Organ Cryopreservation: The team continues refining porcine kidney cryopreservation protocols. About 40% of kidneys show excellent vitrification with minimal ice formation. The other 60% show small ice crystals in the inner medulla - the part of the kidney that's hardest to perfuse.

Brain Slice Cultures: we are developing long-term brain slice cultures that can survive 2-3 weeks in a CO2 incubator. Using assays to measure metabolic activity, they've established a baseline comparing fresh tissue versus straight-frozen tissue. The goal: cryopreserve brain slices, rewarm them, and show maintained viability and functionality over time. This would be a significant contribution to the literature - evidence that brain tissue can remain alive and functional after proper cryopreservation. Additional human brain tissue experiments are also in the works, with a neurosurgery partnership nearly finalized.

New Project: Antifreeze Protein Gene Integration: A particularly exciting update is that we are developing a project to integrate antifreeze protein genes directly into cells via gene therapy. The idea is that if cells can produce their own antifreeze proteins internally, they might survive freezing and thawing better without needing external cryoprotectants. This is early-stage - they're still screening candidate proteins from fish, beetles, and other organisms. Potential applications include improving CAR-T cell therapy, which could be relevant for both cryonics and mainstream medicine.

The protein BDNF is known to encourage neuroplasticity in the brain and otherwise assist in protecting the health and function of neurons. Numerous studies have demonstrated upregulation of BDNF to improve cognitive function in the context of aging and neurodegenerative conditions. Much of this work focuses on very indirect paths to the upregulation of BDNF, such as manipulation of the gut microbiome, but here researchers take the direct approach of a viral gene therapy introduced into brain tissue via stereotactic injection. They show that this can improve cognitive function in mouse models of Alzheimer's disease

Brain-derived neurotrophic factor (BDNF) can protect neurons from apoptosis and maintain normal synaptic structures, indicating a significant potential for Alzheimer's disease (AD) treatment. However, the method of in vivo BDNF delivery requires further optimization, and the therapeutic efficacy of BDNF in AD animal models needs to be further evaluated. Here, we demonstrated that a newly engineered adeno-associated virus (AAV) serotype termed AAVT42 showed better tropism for neurons than AAV9 in the central nervous system (CNS).

We analyzed the therapeutic potentials of AAVT42-delivered BDNF in three AD mouse models: amyloid precursor protein/presenilin-1 (APP/PS1), rTg4510, and 3xTg. Long-term BDNF expression in the hippocampus mitigated neuronal degeneration or loss in these AD mice, and alleviated their cognitive impairment, with no discernible effect on amyloid-β deposition or tau phosphorylation. Furthermore, transcriptomic analysis in 3xTg mice revealed that BDNF orchestrated the up-regulation of genes associated with neuronal structural organization and synaptic transmissions, such as Neuropeptide Y (Npy), Corticotropin-releasing hormone (Crh), Tachykinin precursor 1 (Tac1), and the down-regulation of Bone morphogenetic proteins (Bmps).

Our study highlighted the efficacy of AAVT42 in gene delivery to CNS and validated the therapeutic benefits of BDNF in treating AD, which will be useful for future translational research on AD treatment using an AAV delivery system.

Link: https://doi.org/10.1016/j.gendis.2025.101649

Cancer diagnosis and treatment tends to involve the removal of lymph nodes, leading to impaired flow in the lymphatic system and either transient or permanent lymphedema. In aging, lymph nodes become fibrotic and structural disorganized, impairing the ability of immune cells to use the lymphatic system to coordinate a response to infection. One possible approach to these problems is the generation of artificial lymph nodes, or at least suitable arrangements of cells that will form themselves into a functional lymph node and connect to the lymphatic system once implanted into the body. A number of different groups have made progress towards this goal, to the point of demonstrating the creation of partially functional lymph nodes in animal studies; the research program noted here is the most recent.

The increase in cancer incidence has accelerated the need for secondary lymphedema treatments after lymphadenectomy because lymph nodes cannot be regenerated. Recently, many attempts have been made to treat secondary lymphedema by forming lymphatic vessels using three-dimensional cellular structures. Of these, three-dimensional cellular structures composed of lymphatic endothelial cells (LECs) and fibroblasts fabricated using a cell stacking technique by coating functional proteins on the cell surface were reported to form a lymphatic network inside the structures, demonstrating the formation of a lymphatic lumen structure after transplantation in mice. Unfortunately this cellular structure has not been effective for the treatment of secondary lymphedema. Therefore, lymph node regeneration or reconstruction using therapeutic cells has not been achieved, and the development of a better therapeutic method is desired.

This study aims to develop a bioengineered three-dimensional tissue composed of LECs and mesenchymal stem/stromal cells (MSCs), which has immunomodulatory functions and can prolong the survival of transplants for lymph node reconstruction. To fabricate the bioengineered tissue simply, we establish a centrifugal cell stacking technique with no additives. This bioengineered tissue, termed "centrifuge-based bioengineered lymphatic tissue" (CeLyT), forms a lymphatic network inside the tissue during culture for several days. CeLyTs induce the formation of lymph node-like structures, with characteristics similar to lymph nodes, after transplantation into mice, and the formation of this lymph node-like structure suppress edema following lymphadenectomy in mice. Therefore, CeLyTs composed of LECs and MSCs might be a cell-based therapeutic strategy for secondary lymphedema.

Link: https://doi.org/10.1038/s41467-025-65121-3

Transposable elements, or transposons, are DNA sequences capable of directing the protein machinery surrounding nuclear DNA to haphazardly insert copies of the transposon elsewhere in the genome, potentially breaking other necessary sequences. Transposons are thought to be the remnants of ancient viral infections, but given that transposon activities are most likely an important mechanism of evolution, driving functional changes that can then be selected, that may not be universally true.

Transposons are suppressed in youth, the structure of DNA managed by epigenetic mechanisms to package away transposon sequences into heterochromatin structures and thus hide them from transcription machinery in the cell nucleus. With advancing age the epigenetic control of DNA structure changes in a variety of ways, altering the expression of many genes to contribute to loss of function, but also unleashing transposons to an ever greater degree.

Beyond mutational damage, transposon activity generates molecules that the cell has evolved to recognize as foreign and react to with inflammatory signaling. The activity resembles a viral infection, in essence. It may be that the greatest harm done by transposon activation is not in fact the mutational damage to DNA, but rather the contribution to a state of systemic sterile inflammation that is characteristic of aging, disruptive to tissue structure and function.

The interplay of epigenetic remodelling and transposon-mediated genomic instability in ageing and longevity

Ageing and age-related diseases are the result of complex biological processes that progressively cause deterioration of cellular and tissue function. Among the key hallmarks of ageing are epigenetic alterations and genomic instability, both of which are closely interconnected and significantly contribute to the ageing process. The epigenome, encompassing both DNA and histone modifications, regulates gene expression and maintains genomic integrity throughout life. With age, these regulatory systems become dysregulated, leading to genome-wide changes in chromatin structure, histone modifications, and the reactivation of transposable elements (TEs).

TEs, typically silenced in heterochromatic regions, become active in aged cells, contributing to genomic instability, mutagenesis, inflammation, and metabolic disruption. Despite their significant implications, the role of TEs in the ageing process remains underexplored, and the interplay between epigenomic remodelling and TE activity remains poorly understood. In this review, we explore the molecular mechanisms underlying epigenetic alterations and TE reactivation during ageing, the impact of these changes on genomic stability and the potential therapeutic interventions targeting this interplay. By deciphering the role of epigenetic modifications and TE derepression in the ageing process, we aim to highlight novel avenues for anti-ageing and pro-longevity strategies.

Most of the approaches demonstrated to alter metabolism in ways that modestly slow aging and extend life involve an increased efficiency of autophagy. This includes mild stresses resulting from exercise, calorie restriction, heat, cold, and low levels of toxin exposure. The processes of autophagy act to recycle damaged or otherwise unwanted cellular components into amino acids that can be used for further protein synthesis, improving cell function. Thus there is interest in the scientific community in finding drugs that can induce increased autophagy. The best known, most readily available, and most advanced in the clinic are varieties of mTOR inhibitor, rapamycin being the canonical example. But many other classes of small molecule may prove to be interesting enough to develop into drugs.

Macroautophagy, henceforth referred to as autophagy, is a cellular process that, in part, can act to break down damaged, dysfunctional, or otherwise unwanted components. Autophagy is crucial for maintaining proteostasis and is a necessary system for cellular survival under stressful conditions. Autophagic efficiency declines during aging, leading to the buildup of damaged proteins and organelles, as well as other nonviable cellular debris.

The amino acid response (AAR) pathway is a highly conserved mechanism that reacts to low levels of amino acids with the increased translation of Gcn4 (in yeast), ATF-4 (in worms), and ATF4 (in mammals). We have previously shown that activation of this pathway through the chemical inhibition of tRNA synthetases (tRS) can activate autophagy and extend lifespan in both worms (C. elegans) and yeast (S. cerevisiae).

In this study, we identify four additional tRNA synthetase inhibitors, REP8839, REP3123, LysRS-In-2, and halofuginone, that extend both healthspan and lifespan in C. elegans. These compounds also trigger a significant upregulation of autophagy, specifically at their lifespan-extending doses. These phenotypes partially depend on the conserved transcription factor ATF-4. Our findings further establish tRNA synthetase inhibition as a conserved mechanism for promoting increased lifespan and now healthspan, with potential implications for therapeutic interventions targeting age-related decline in humans.

Link: https://doi.org/10.3390/biom16010073

Cell therapies seem the least likely of approaches to make it into the clinic as a treatment to selectively destroy the senescent cells that linger to cause harm in aged tissues. While it is a very plausible goal to take a CAR T cell therapy and target it to senescent cells, or use adoptive transfer of other immune cell types known to attack senescent cells, as these are just variations on strategies already well demonstrated to work in other contexts, the cost and logistical effort is enormous in comparison to other approaches to the selective destruction of senescence cells. It is far more likely that therapies to adjust the operation of native immune cells, such as the approach under development by Deciduous Therapeutics, or forms of senolytic vaccine, will emerge from this line of thinking.

One of the most significant risk factors for diseases is aging. Interestingly, some organisms, such as naked mole-rats and most turtles, do not exhibit typical aging-like symptoms or increased mortality as they become older. These aspects indicate that aging is not necessarily an essential event for animal life and are avoidable. Overcoming aging would free humans from age-associated diseases (AADs) and prolong lifespans.

Recent studies have demonstrated that one of the causes of age-related organ dysfunction is excessive chronic inflammation caused by the accumulation of senescent cells (SNCs) and their senescence-associated secretory phenotypes (SASPs). Therefore, the development of drugs and medication to remove SNCs is ongoing.

Natural killer (NK) cells are integral components of the innate immune system that are critical for clearing SNCs. Beyond this direct function, NK cells also orchestrate innate and adaptive immunity responses to survey and eradicate these compromised cells. Consequently, preserving NK cell function throughout the aging process is paramount for mitigating AADs and promoting robust health in later life.

Simultaneously, NK cell-based senotherapy presents compelling avenues for addressing the multifaceted challenges associated with SNC accumulation and aging. Recent investigations into adoptive NK cell-based senotherapy have demonstrated considerable promise in rejuvenating immunosenescence, facilitating SNC elimination. The accumulating evidence provides a promising proof-of-concept for adoptive NK cell-based senotherapy, indicating its potential as a development in longevity therapeutics.

Link: https://doi.org/10.3389/fimmu.2025.1737572

The degree to which human longevity is inherited is one of a large number of interesting research topics that, while being related to aging, has little to no relevance to the question of how to treat aging as a medical condition. In developing means to repair or resist the cell and tissue damage that causes degenerative aging, the focus must be on the damage, not the differences from individual to individual. How it is that aging progresses somewhat differently from individual to individual will become increasingly irrelevant as therapies to slow and reverse aging emerge.

That said, today's open access paper on the heritability of longevity is quite interesting. The argument put forward by the authors is that previous efforts to quantify the degree to which individual variance in longevity is determined by one's immediate ancestry have produced underestimates because they failed to properly compensate for the effects of premature death resulting from accidents, infectious disease, and the like. If the strategy for assessment used in the paper is employed instead, then human heritability of longevity is higher than past results, and also more in line with the heritability of other physical traits.

At the same time, the big picture on the genetics of aging that has emerged in recent years, with the advent of very large population databases such as the UK Biobank, is that genetics plays only a small role in determining life expectancy. It is far outweighed by lifestyle choice in the vast majority of people. A high heritability but low contribution of genetic variance suggests that heritability largely exists as a result of the cultural transmission of lifestyle choices; parents that take better care of their health tend to have children who take better care of their health, and vice versa.

Heritability of intrinsic human life span is about 50% when confounding factors are addressed

Understanding the heritability of human life span is fundamental to aging research. However, quantifying the genetic contribution to human life span remains challenging. Although specific life span-related alleles have been identified, environmental factors appear to exert a strong effect on life span. Clarifying the heritability of life span could direct research efforts on the genetic determinants of life span and their mechanisms of action.

Previous studies have estimated the heritability of life span in various populations with results ranging from 15 to 33%, with a typical range of 20 to 25%. Recently, studies on large pedigree datasets estimated it at 6 to 16%. These studies contributed to growing skepticism about the role of genetics in aging, casting doubt on the feasibility of identifying genetic determinants of longevity. Current estimates for the heritability of human life span are thus lower than the heritability of life span in crossbred wild mice in laboratory conditions, estimated at 38 to 55%. They are also lower than the heritability of most other human physiological traits, which show a mean heritability of 49%.

Most life-span studies used cohorts born in the 18th and 19th centuries, with appreciable rates of extrinsic mortality. Extrinsic mortality refers to deaths caused by factors originating outside the body, such as accidents, homicides, infectious diseases, and environmental hazards. Another factor that varies between studies is the minimum age at which individuals must be alive to be included, referred to as the cutoff age. To our knowledge, these two factors - extrinsic mortality and cutoff age - have not been systematically investigated for their effect on heritability estimates of life span.

Here, we explored the effects of extrinsic mortality and cutoff age on twin study estimates of heritability. We used model-independent mathematical analysis and simulations of two human mortality models to partition mortality into intrinsic and extrinsic components. We tested our conclusions on data from three different twin studies, including the SATSA (Swedish Adoption/Twin Study of Aging) study, containing data from twins raised apart that have not been previously analyzed for life-span heritability. To test generalizability to non-Scandinavian cohorts, we also analyzed siblings of US centenarians. We found that extrinsic mortality causes systematic underestimates of the heritability of life span and that cutoff age has a mild nonlinear effect on these estimates. When extrinsic mortality is accounted for, estimates of heritability of life span due to intrinsic mortality rise to about 55%, more than doubling previous estimates.

This is an example of the very earliest stages of research leading to drug discovery, the identification of a potential target protein, here CUL5, that can be manipulated to change cell metabolism in a specific way, here meaning a reduction in the amount of tau protein in the cell. Aggregation of altered tau is a feature of late stage Alzheimer's disease, a cause of cell dysfunction and death in the brain. Reducing tau levels is one possible approach to the problem, though given that tau has a normal and necessary function in the brain, it may not be the best possible approach. At this stage, researchers do not know how CUL5 functions to affect tau levels, and thus a good deal of further work stands between the present discovery and the emergence of any practical outcome.

Aggregation of the protein tau defines tauopathies, the most common age-related neurodegenerative diseases, which include Alzheimer's disease and frontotemporal dementia. Specific neuronal subtypes are selectively vulnerable to tau aggregation, dysfunction, and death. However, molecular mechanisms underlying cell-type-selective vulnerability are unknown. To systematically uncover the cellular factors controlling the accumulation of tau aggregates in human neurons, we conducted a genome-wide CRISPR interference screen in induced pluripotent stem cell (iPSC)-derived neurons.

In comparison to other tau screens previously reported in the literature, our data have broadly similar patterns of hit genes. A previous genome-wide screen for modifiers of tau levels performed in SHY5Y cells has several shared classes of genetic modifiers. Surprisingly, this screen identified CUL5 as a negative modifier of tau levels. Since CUL5 regulates hundreds of substrates, it is not surprising that CUL5 knockdown has different phenotypes in different contexts.

We find CUL5 expression to be correlated with resilience in tauopathies along with genes encoding CUL5 interactors, including ARIH2 and SOCS4. However, the molecular mechanisms by which CUL5 affects neuronal vulnerability in AD remains to be identified. A broad distribution of CUL5 expression is seen in different neuronal subtypes in the Seattle Alzheimer's Disease Brain Cell Atlas suggesting that CUL5 may modulate disease vulnerability via multiple mechanisms. For instance, it is possible that CUL5 expression affects vulnerability via tau ubiquitination. But, considering CUL5's known role in immune signaling, another possibility is that CUL5 expression affects vulnerability via the neuro-immune axis.

Link: https://doi.org/10.1016/j.cell.2025.12.038

Parkinson's disease is driven by the spread of misfolded α-synuclein through the brain. The most evident symptoms result from the death and dysfunction of motor neurons, caused by the presence of misfolded α-synuclein. Once α-synuclein misfolds, it is capable of inducing other molecules of α-synuclein to misfold in the same way, and this dysfunction can slowly spread from cell to cell. In recent years, researchers have shown that in a sizable fraction of Parkinson's disease cases misfolded α-synuclein first emerges in the intestines and then spreads to the brain. Here, researchers uncover more of the mechanisms by which this transmission takes place, with an eye to finding ways to intervene in the earliest stages of the condition in order to prevent later consequences.

Emerging evidence suggests that Parkinson's disease (PD) may have its origin in the enteric nervous system (ENS), from where α-synuclein (αS) pathology spreads to the brain. Decades before the onset of motor symptoms, patients with PD suffer from constipation and present with circulating T cells responsive to αS, suggesting that peripheral immune responses initiated in the ENS may be involved in the early stages of PD. However, cellular mechanisms that trigger αS pathology in the ENS and its spread along the gut-brain axis remain elusive.

Here we demonstrate that muscularis macrophages (ME-Macs), housekeepers of ENS integrity and intestinal homeostasis, modulate αS pathology and neurodegeneration in models of PD. ME-Macs contain misfolded αS, adopt a signature reflecting endolysosomal dysfunction and modulate the expansion of T cells that travel from the ENS to the brain through the dura mater as αS pathology progresses. Directed ME-Mac depletion leads to reduced αS pathology in the ENS and central nervous system, prevents T cell expansion and mitigates neurodegeneration and motor dysfunction, suggesting a role for ME-Macs as early cellular initiators of αS pathology along the gut-brain axis. Understanding these mechanisms could pave the way for early-stage biomarkers in PD.

Link: https://doi.org/10.1038/s41586-025-09984-y