Fight Aging!

The aging of muscle tissue leading to loss of muscle mass (sarcopenia) and muscle strength (dynapenia) is a microcosm of aging in general, in that many different groups promote many different views of the relative importance of many different mechanisms. All of these mechanisms do in fact exist - muscle aging is a complex interplay of many interacting issues - but it is likely that any given view on the importance of any given specific mechanism will turn out to be wrong. The only practical way to establish the importance of a mechanism of muscle aging is to develop a means of blocking or repairing just that mechanism in isolation of all of the others, and observe the result. This applies as much to the examination of ferroptosis noted here as it does to any of the other mechanisms involved in muscle aging.

Age-related decline in physical function is a hallmark of aging and a major driver of morbidity, disability, and loss of independence in older adults, yet the molecular processes linking muscle aging to functional deterioration remain incompletely defined. Emerging evidence implicates ferroptosis, defined as iron-dependent, lipid peroxidation-driven cell death, as a compelling but underexplored contributor to age-related muscle wasting and weakness. Although ferroptosis signatures appear in aged muscle across cellular, animal, and human studies, their causal role in functional decline has not been clearly established.

Here, we synthesize current evidence to propose a framework in which iron dyshomeostasis, impaired antioxidant defenses, and dysregulated ferritinophagy converge to create a pro-ferroptotic milieu that compromises muscle energetics, structural integrity, and regenerative capacity. We delineate key knowledge gaps, including the absence of ferroptosis-specific biomarkers in human muscle and limited longitudinal data linking ferroptotic stress to mobility outcomes. Finally, we highlight potential therapeutic opportunities targeting iron handling and lipid peroxidation pathways. A better understanding of the contribution of ferroptosis to muscle aging may enable development of mechanistically informed biomarkers and interventions to preserve strength and mobility in older adults.

Link: https://doi.org/10.1111/acel.70367

Researchers here report on an approach to quantifying somatic mosaicism in a tissue sample. Mutational damage to nuclear DNA occurs constantly, but specific mutations only spread through a tissue over time to a sizable degree when they occur in one of the stem cells or progenitor cells that support that tissue by generating a supply of new daughter somatic cells. Somatic mosaicism has been shown to correlate with an increased risk of a few age-related conditions, particularly cancers, but it remains unclear as to how greatly it contributes to the overall progression of aging. Better ways to measure and catalog the extent of somatic mosaicism seem likely to help increase our understanding of its role.

The extensive presence of mutation-containing cells alongside normal cells, typically with no obvious difference between them, is known as somatic mosaicism. Now recognized as a common feature of human aging, it arises when a DNA "driver" mutation occurs in a cell, giving the cell and its progeny a slight but not yet cancerous growth or survival advantage. Researchers developed a technology called single-cell Genotype-to-Phenotype sequencing (scG2P), which allowed them to study somatic mosaicism in solid tissues - prior studies focused mostly on mosaicism in blood cells. Solid tissue samples are stored in ways that make mutational and gene activity information more challenging to access. Moreover, obtaining an accurate picture of solid tissue mosaicism typically requires profiling larger numbers of cells.

The team used scG2P to study esophageal tissue samples from six older adults. They found that more than half of the 10,000+ sampled cells contained clonal driver mutations and most had a single driver mutation in a gene called NOTCH1, which normally controls cell maturation, identity, division, and survival in the lining of the esophagus and other epithelial tissues in the body. The gene-activity readouts suggested that these NOTCH1 driver mutations induce clonal overgrowth by impairing normal cell development. The next most common driver-mutation gene in the samples was TP53, which makes the p53 protein, a crucial tumor suppressor that is inactivated in many cancers. TP53-mutant clones in the samples showed impaired maturation and also more frequent cell division compared to normal cells.

The findings are consistent with one of the central ideas of cancer biology: a single mutation is usually insufficient for malignancy and cancers arise from a series of mutations, which is increasingly common as we age.

Link: https://news.weill.cornell.edu/news/2026/01/scientists-identify-pre-cancerous-states-in-seemingly-normal-aging-tissues

Metabolism is complex, the interactions of countless molecules inside and outside cells. Evolution clearly does not optimize for the metabolism that provides individuals of a species with longer, more comfortable lives. We know this because any number of small tweaks to levels and interactions of specific proteins or metabolites have been shown to improve health and slow aging in multiple species. Success for a species is not necessarily aligned with success for any of the individuals making up that species.

Today's open access review is a guided tour of a handful of metabolites that are present in the body and for which studies have shown that upregulation (or in a few cases downregulation) can modestly slow aging in animal studies. This actually encapsulates quite a large fraction of recent research into aging, given that the list includes methionine restriction, a number of approaches assessed by the NIA Interventions Testing Program, hydrogen sulfide, and NAD+ upregulation. Should we be disappointed that such a large proportion of translational aging research is focused on approaches that cannot even in principle produce effects that improve all that much on the benefits of exercise? Perhaps so.

Lifespan-Extending Endogenous Metabolites

Taurine is a sulfur-containing β-amino acid synthesized endogenously from cysteine or methionine and present at high concentrations in many mammalian tissues. Taurine has been implicated in antioxidant and anti-inflammatory defenses, partly by supporting mitochondrial protein synthesis and function. Taurine supplementation shows protective effects in aging models. Animal studies suggest that supplementation can mitigate age-related deficits in cognition, cellular senescence, and tissue function. Evidence on natural taurine changes during healthy aging is mixed, highlighting species and individual variability.

Betaine, also called trimethylglycine, is a naturally occurring trimethylated amino acid present in plants, animals, and humans. Betaine donates a methyl group to homocysteine via betaine-homocysteine methyltransferase (BHMT) to regenerate methionine and S-adenosylmethionine (SAM), increasing the cellular SAM: SAH (S-adenosylhomocysteine) ratio. Emerging evidence across model organisms indicates that betaine can delay the aspects of aging. In aged mice, dietary betaine improved skeletal muscle mass, strength, and endurance, with preserved mitochondrial structure and respiration.

α-Ketoglutarate (α-KG) is a central tricarboxylic acid (TCA) cycle intermediate. Mechanistically, α-KG reduces cellular ATP levels and oxygen consumption while activating autophagy. Physiologically, endogenous α-KG levels increase during starvation in C. elegans, and its exogenous supplementation cannot augment longevity under dietary restriction, positioning α-KG as a key metabolite mediating the pro-longevity effects of nutrient limitation through ATP synthase inhibition and subsequent TOR pathway modulation.

Oxaloacetate (OAA) is an endogenous four-carbon metabolite of the citric acid cycle. In C. elegans, dietary OAA supplementation extends lifespan, requiring AMPK and the FOXO transcription factor DAF-16. This effect was hypothesized to result from OAA conversion to malate, consuming NADH and raising the NAD+/NADH ratio to mimic dietary restriction. However, translation of findings from invertebrates to mammals has been inconsistent.

Hydrogen sulfide (H2S) is an endogenous gasotransmitter. H2S has been shown to modulate aging in organisms ranging from worms to mammals. In C. elegans, exposure to H2S induces thermotolerance and extends lifespan. H2S levels generally decline with age, correlating with increased oxidative stress and inflammation. While H2S robustly extends lifespan in C. elegans and rodent studies report organ-level protection and improved some age-related dysfunctions with various H2S donors, evidence for H2S directly extending lifespan in mammals is lacking.

Nicotinamide adenine dinucleotide (NAD+) is a ubiquitous redox coenzyme which is central to cellular energy metabolism. It also serves as a substrate or cofactor for sirtuins, PARPs, and other enzymes that regulate DNA repair, chromatin remodeling, and stress responses. NAD+ levels decline with advancing age and lower NAD+ is correlated with a range of chronic age-related disorders.

Methionine is an essential amino acid critical for protein synthesis and serves as a precursor for SAM, a major methyl donor involved in numerous methylation reactions including DNA and protein methylation. Methionine restriction (MetR) extends lifespan across diverse models. In mice, it reduces adiposity and body size, reverses age-induced alterations in physical activity and glucose tolerance, and restores a younger metabolic phenotype. Reducing dietary methionine concentration from 0.86% to 0.17% increased rat lifespan by 30%.

Regular exercise is well established to correlate with improved health and reduced mortality in human epidemiological data, while animal studies demonstrate that exercise in fact causes improved health and reduced mortality. One of the noted benefits of exercise is an improvement in many aspects of immune function. In older people, that includes a reduction in the chronic inflammatory signaling that is characteristic of the aged immune system, as well as increased immune competency in defense against pathogens.

Immunosenescence, characterized by a progressive decline in immune function with age, leads to significant impairments in T-cell and B-cell responses, the reduced efficacy of dendritic cells, and diminished natural killer cell activity, ultimately decreasing the capacity to fight infections and clear tumors. This decline increases susceptibility to autoimmune diseases, chronic inflammation, and cancer, underscoring the urgent need for effective interventions.

Exercise emerges as a transformative strategy to combat immunosenescence by inducing metabolic remodeling that enhances insulin sensitivity, regulates immune cell phenotypes, and reduces chronic inflammation through the mTOR and AMPK signaling pathways. Furthermore, exercise promotes an optimal balance in immune responses by modulating lactate levels and supporting the transition from pro-inflammatory to anti-inflammatory states, effectively sustaining immune function in aging individuals. Exercise-induced lipid and amino acid metabolic changes play crucial roles in improving immune function by reducing visceral fat accumulation and optimizing amino acid metabolism, leading to restored immune cell functionality and healthier immune profiles in older adults.

The comprehensive organ-immune crosstalk facilitated by exercise, particularly through the release of myokines and modulation of the gut microbiota, enhances immune cell activity and contributes to systemic immune regulation, countering age-related immune decline. Notably, exercise effectively remodels both innate and adaptive immune cells by promoting the functionality of neutrophils, macrophages, and T cells while augmenting naive T-cell output from the thymus. These adaptations improve immune surveillance and response, reinforcing the assertion that exercise is vital for delaying the aging-related decline in immune health.

Link: https://doi.org/10.3390/biology15010058

If delving very deep into the structures that support flexibility and elasticity in tissues, one eventually arrives at specific proteins incorporated into cells and the extracellular matrix that act as springs or similar mechanical systems. Researchers here note that one such spring protein in heart muscle, known as titin, exhibits an increased proportion of less elastic isoforms in the context of heart failure. This makes heart muscle stiffer, and the heart less able to pump blood. Adjusting the regulation of isoform proportions to favor the more elastic isoforms can be achieved by inhibiting another specific protein, RBM20. The result is more elastic heart tissue and reduced pathology of heart failure.

Heart failure with preserved ejection fraction (HFpEF) is prevalent, deadly, and difficult to treat. Risk factors such as obesity and hypertension contribute to cardiac inflammation, metabolic defects, and pathological remodelling that impair ventricular filling in diastole. Addressing the mechanical aspects of cardiac dysfunction at the level of myofilaments provides a direct approach to improve diastolic performance across diverse HFpEF phenotypes.

Titin is a giant myofilament protein and functions as a molecular spring, which generates passive force when sarcomeres are stretched, thereby aiding in returning the sarcomere to its resting length. Titin contributes up to ∼70% of left ventricular (LV) physiological passive stiffness. In HFpEF, increased titin stiffness has been identified as a key pathological factor contributing to LV diastolic dysfunction in human and animal models.

In the adult heart, there are two main isoforms of titin: N2B and N2BA, with the N2B isoform being the stiffest. RNA binding motif-20 (RBM20) is a major splicing regulator that determines isoform expression of titin. Complete inhibition of Rbm20 activity leads to the expression of N2BA-G titin, which is very long and highly compliant. Mice expressing N2BA-G titin exhibit reduced LV chamber stiffness and attenuated systolic contractility. Meanwhile, partial inhibition of RBM20 activity results in the expression of N2BA-N titins, which are larger than the N2BA but not as large as the N2BA-G isoform. Mice expressing N2BA-N titins show reduced LV chamber stiffness while maintaining normal baseline systolic function and enhanced exercise tolerance.

Inhibition of RBM20 using antisense oligonucleotides (ASOs) induces expression of compliant titin isoforms. Here, we optimized RBM20-ASO dosing in a HFpEF mouse model that closely mimics human disease, characterized by metabolic syndrome and comorbidities, but without primary defects in titin or RBM20. Partial inhibition of RBM20 (∼50%) selectively increased compliant titin isoforms, improving diastolic function while preserving systolic performance. This intervention reduced left ventricular stiffness, enhanced relaxation, and mitigated cardiac hypertrophy, despite ongoing systemic comorbidities.

Link: https://doi.org/10.1093/cvr/cvaf171

A broad range of mechanisms contribute to a growing stiffening of blood vessels, a loss of ability to contract and dilate in response to environmental cues. Blood flow is vital, and this impairs its regulation. Vascular stiffening contributes to hypertension, atherosclerosis, and downstream issues in the cardiovascular system the tissues it supports. One of the causes of vascular stiffening is progressive inability of the smooth muscle surrounding vessels to sufficiently constrict the vessel. This dysfunction arises from its own grab bag of various mechanisms with various much debated degrees of importance relative to one another.

Today's open access paper is a dive into one specific aspect of the biochemistry of smooth muscle activity. The researchers characterize a particular age-related issue related to regulation of the cytoskeletal structure of vascular smooth muscle cells and its relationship to oxidizing molecules in the context of vessel constriction. The point to all of this is that the researchers demonstrate that age-related loss of the ability of smooth muscle tissue to constrict vessels can be reversed to some degree by overexpression of a specific protein involved in their mechanisms of interest. The best way to justify further investigation of a novel mechanism is by demonstrating its relevance in living tissues.

A mechanism for the disrupted redox regulation of vascular contractility during aging

Aging of vascular cells significantly contributes to the overall organismal aging phenotype and is a major independent risk factor for cardiovascular diseases. While many studies focused on endothelial cells, aging-related processes also affect the vascular smooth muscle cell (VMSC). An aged VSMC associated with disturbed arterial stiffness and, in particular, impaired contractility.

Cytoskeletal deregulation, mainly of the actin network, lies at the core of such changes. Importantly, cytoskeleton-linked mechanobiological processes strongly crosstalk with redox-dependent signaling at several levels, from sensing to tissue remodeling. In particular, an oxidant environment promotes actin polymerization and enhances contractility. It is conceivable, thus, that post-translational redox modifications, including e.g., protein sulfenylation, affect actin organization, but the precise role of such an oxidant environment on vascular contractility during aging is unknown.

We hypothesized that the aging-related impairment of redox and sulfenylation-regulated cytoskeleton dynamics associates with the disruption of chaperone signaling. A particular subgroup of redox chaperones is the protein disulfide isomerases, with prominence of its founding member PDIA1 (or simply PDI). This thioredoxin superfamily protein is mainly located in the endoplasmic reticulum (ER), where it supports oxidative protein folding. Meanwhile, it also exhibits functions out of the ER associated with mechano-regulation, including fine-tuning of cellular force distribution, integrin regulation, and β-actin organization, accounting for vascular remodeling modulation

We first show that protein sulfenylation supports vascular contractility and F-actin assembly during mechanoadaptation or agonist-induced contraction. Meanwhile, PDI supports sulfenylation-dependent actin remodeling. Moreover, aged murine arteries lose the sulfenic acid-related component of contractility, while PDI overexpression overrides this dysfunction and restores aging-related vascular contractility. We further confirm a direct PDI-actin interaction modulated by sulfenic acid. Overall, signaling connections between PDI and sulfenylated proteins behave as an upstream integrative system regulating F-actin assembly, a mechanism that is impaired during aging-induced vascular dysfunction.

Any individual transcription factor influences the expression of many different genes. Researchers have established that some transcription factors can induce radical changes in cell state and behavior, such as the Yamanaka factors used in reprogramming studies. For any specific desirable change in the behavior of aged cells, it is possible that one or more specific transcription factors exist to create that change - the challenge lies in identifying those transcription factors. Researchers are thus working to assess and catalog the many transcription factors present in the human genome. It is a large task. The work noted here covers just one cell type and by no means all of the space of possibilities even there. Nonetheless, that the researchers found potentially useful transcription factors suggests that this can be a fruitful line of research.

Cellular rejuvenation through transcriptional reprogramming has emerged as exciting approach to counter aging. However, to date, only a few of rejuvenating transcription factor (TF) perturbations have been identified. In this work, we developed a discovery platform to systematically identify single TF perturbations that drive cellular and tissue rejuvenation. Using a classical model of human fibroblast aging, we identified more than a dozen candidate TF perturbations and validated four of them (E2F3, EZH2, STAT3, ZFX) through cellular/molecular phenotyping.

Overexpressing E2F3 or EZH2, and repressing STAT3 or ZFX, reversed cellular hallmarks of aging - increasing proliferation, proteostasis, and mitochondrial activity, while decreasing senescence. EZH2 overexpression in vivo rejuvenated livers in aged mice, reversing aging-associated gene expression profiles, decreasing steatosis and fibrosis, and improving glucose tolerance. Mechanistically, single TF perturbations led to convergent downstream transcriptional programs conserved in different aging and rejuvenation models. These results suggest a shared set of molecular requirements for cellular and tissue rejuvenation across species.

Link: https://doi.org/10.1073/pnas.2515183123

Researchers here identify a correlation between grip strength and the functional connectome and blood supply of the caudate nucleus region of the brain in older adults. Many aspects of aging correlate with one another even if they do not interact directly, as any given specific form of age-related damage and dysfunction tends to affect many organs and systems in the body. Think of the effects of chronic inflammatory signaling, for example. It is interesting to consider whether there could be a role for the aging of the caudate nucleus in determining loss of muscle mass and strength, but that would be the subject of further research; it isn't obvious at all from what is presently known of the caudate nucleus as to how this connection could work.

Researchers used functional MRI scans to measure brain activity in older adults as they performed a maximum grip strength test. What the researchers found surprised them. Among the dozens of brain areas monitored, one emerged as the strongest predictor of grip strength: the caudate nucleus. Tucked deep in the brain, the caudate is known for helping manage movement and decision-making. But its role in muscular strength, and its potential to signal frailty, has until now gone largely unnoticed.

The researchers analyzed scans from 60 older adults. The study group comprised half men and half women, and all completed three sessions of functional MRI while undergoing strength testing. To ensure they were isolating brain effects from other factors like body size, the data was normalized to account for differences in sex and muscle mass. The result was a statistically significant correlation between brain network patterns and grip performance. Stronger blood flow and greater connectivity of the functional connectome in the caudate nucleus matched higher grip strength, independent of gender.

Link: https://www.eurekalert.org/news-releases/1112375

The balance of microbial populations making up the gut microbiome changes for the worse with aging. Populations that provoke inflammation increase in size at the expense of populations that manufacture beneficial metabolites. We have some idea of the size of the resulting contribution to degenerative aging as a result of fecal microbiota transplantation studies, from young donor to old recipient, carried out in killifish and mice. Old recipients provided with a young gut microbiome composition exhibit improved health and extended life.

Sustained programs of exercise are known to improve the composition of the gut microbiome, reducing the magnitude of some of the changes known to occur with age. This may be the result of improved immune function, and thus a greater ability of the immune system to remove unwanted, inflammatory microbes. It is thought that some fraction of the well-known reduced risk of age-related disease and mortality resulting from exercise may be due to an improved gut microbiome. The question, as usual, is how large a fraction.

In today's open access paper, researchers report on a study of exercise conducted in aged mice with the aim of obtaining potentially illuminating data on the relationship between exercise, health, and gut microbiome composition. The most interesting result is not the health benefits, which are expected, but rather that exercise becomes progressively less effective in altering the gut microbiome as the animals become older.

Age-dependent effects of exercise on gut microbiota-mitochondria axis and cognitive function in aging mice

Aging is accompanied by progressive impairments in mitochondrial bioenergetics, apoptosis regulation, and gut microbiota homeostasis, all of which contribute to cognitive decline. In this study, we investigated whether the effects of treadmill exercise on the gut microbiota-mitochondrion-neuronal plasticity axis differed between young (15 months) and old (28 months) mice. Male C57BL/6 mice were randomly assigned to the following groups: early sedentary, early exercise, late sedentary, or late exercise groups and completed an 8-week treadmill training protocol.

Cognitive function was assessed using the passive avoidance test and the Morris water maze test. Hippocampal mitochondrial respiration, Ca2+ retention capacity, and Bax/Bcl-2 expression were quantified, and the gut microbiota composition was analyzed using 16S ribosomal RNA sequencing.

Mice that did not exercise in old age exhibited memory impairment, decreased mitochondrial oxidative respiration, reduced Ca2+ retention, increased Bax expression, decreased Bcl-2 levels, and decreased abundance of Lactobacillus, Bifidobacterium, and Akkermansia. Exercise significantly improved behavioral performance, mitochondrial function, and apoptosis balance, while also increasing beneficial gut microbiota.

Notably, these effects were significantly greater in late-aged compared to early-aged mice. These results demonstrate that the efficacy of exercise in modulating the microbiota-mitochondrion-brain axis varies with age. Early-aged appears to represent a more responsive biological period during which exercise is more effective in improving mitochondrial integrity, microbiota composition, and cognitive resilience. These results suggest that initiating exercise early in the aging process may maximize neuroprotective effects and delay age-related functional decline.

The protein α-synuclein can misfold into a pathological form and then spread from cell to cell in the central nervous system. This occurs in everyone to some degree with age, but only some people experience a burden of α-synclein pathology large enough to lead to Parkinson's disease or other synucleinopathies. It is likely that everyone exhibits some loss of function due to α-synuclein, but as ever, it is hard to pin down exactly how much of each aspect of aging is due to any one specific mechanism. The only efficient way to obtain useful data is to fix that one specific problem and observe the outcome, which is what researchers did here in aged rats. A gene therapy produced intracellular antibodies that reduce α-synuclein levels, albeit perhaps not in the expected way, and the result is improved function in treated animals.

Abnormal accumulation of alpha-synuclein (αSyn) in axons and presynaptic terminals plays a critical role in αSyn-mediated dopaminergic neurodegeneration. A strong correlation between aging and elevated αSyn levels in the substantia nigra has been identified in both humans and non-human primates. This study aimed to investigate whether AAV-mediated NAC32 intrabody expression in the substantia nigra could ameliorate αSyn-associated dopaminergic dysfunction and improve age-related motor deficits in aged rats.

We first investigated the mechanism by which NAC32 reduces αSyn levels. Comparisons of αSyn burden, tyrosine hydroxylase (TH) expression, and locomotor activity were made between young and aged rats. In aged rats, we evaluated behavioral performance, dopaminergic markers, and synaptic markers following AAV1-NAC32 gene delivery into the substantia nigra. Our results showed that the NAC32-mediated αSyn reduction was not prevented by inhibition of proteasomal, lysosomal, or autophagic pathways and was associated with reduced αSyn mRNA levels.

Aged rats exhibited decreased locomotor activity, elevated αSyn levels, and reduced TH expression in the substantia nigra. NAC32 intrabody expression in the substantia nigra significantly reduced αSyn accumulation, restored TH expression, increased synaptic markers and striatal dopamine levels, and improved locomotor performance in aged rats. These effects occurred without detectable elevation of pro-inflammatory cytokine levels in bulk striatal tissue. Our findings suggest that AAV-mediated NAC32 intrabody expression in the substantia nigra may serve as a therapeutic strategy to mitigate αSyn-induced dopaminergic dysfunction and motor impairments associated with aging.

Link: https://doi.org/10.1038/s41598-025-34908-1

Researchers here review the evidence for chronic inflammation to contribute to the vascular dysfunction of hypertension, in which blood pressure increases to harmful levels. The particular focus is on the feedback loop in which inflammatory immune dysfunction contributes to dysfunction in the regulation of hematopoiesis, the manufacture of new immune cells by hematopoietic cells resident in bone marrow, which in turn causes greater inflammatory immune dysfunction. Sustained inflammatory signaling is harmful to tissue structure and function throughout the body, including the vasculature and systems that regulate blood pressure.

Hypertension is a highly prevalent chronic disease all around the world, and the pathogenic mechanism is complicated. The early and rapid decline of the function of human vascular system due to the aging of human body are characteristics of hypertension, which is accompanied by progressive pathological remodeling and arterial stiffening.

The pathogenetic action of oxidation and inflammation is the vital function in the process of endothelial dysfunction and arterial injury. Bone marrow is considered as the birthplace of the immune cell, and the role of bone marrow in hematopoiesis and immune response for the onset of hypertension has been confirmed. In turn, inflammatory and oxidative stress also affect the bone marrow and damage bone marrow function, causing a series of complications in hypertension, resulting in a vicious cycle. Recently, increasing evidence has suggested that bone marrow aging plays an important role in the onset and development of hypertension, and that the function of bone marrow in the pathogenesis of hypertension has been seriously overlooked. Bone marrow microvascular ageing is also involved in the progression of bone marrow ageing.

Thus, this review mainly focuses on bone marrow function in aging and hypertension progression, addresses the current studies on the roles of vascular aging, the bone marrow and the immune system in hypertension, and discusses their interaction and function in the pathogenesis of hypertension. Furthermore, some novel molecular pathological mechanisms are surveyed. This can add a new impetus to the mechanism research of hypertension onset.

Link: https://doi.org/10.1038/s41420-025-02851-9

The proteasome is a specialized protein complex that breaks down unwanted proteins into short peptide molecules for reuse in further protein synthesis. Any protein designated as unwanted by the addition of a ubiquitin tag can be broken down in this way. This activity is important, a form of cellular maintenance. When impaired, loss of proteasomal function allows damaged and damaging proteins to build up in the cell, degrading the function of other cellular components and activities. Unfortunately, aging causes loss of proteasomal function just as it degrades the function of all complex systems in the cell.

In today's open access paper, researchers discuss the link between the age-related impairment of proteasomal function and the chronic inflammation that is characteristic of aging. This is a part of the increased attention given to the cGAS-STING pathway and its relevance in aged tissues. The sensor cGAS evolved to detect nucleic acids characteristic of invading pathogens, but is unfortunately also triggered by mislocalized DNA from the cell nucleus or mitochondria that escapes into the cytoplasm of the cell. cGAS in turn activates STING, a central inflammatory regulatory. Diminished proteasomal activity allows the build up of misfolded and other harmful proteins that can disrupt mitochondrial function and structure sufficiently to allow mitochondrial DNA into the cell cytosol.

This sort of connection is why interventions that improve forms of cell maintenance such as proteasomal activity and autophagy tend to reduce age-related inflammation. These forms of intervention range from exercise to sophisticated genetic upregulation or downregulation of specific protein machinery used in cell maintenance processes. Some are more practical than others, and effect sizes vary. What they all have in common is that they help to reduce the level of damage in the form of broken proteins inside cells, thereby improving mitochondrial function, and reducing cGAS-STING activity and consequent inflammatory signaling.

Impaired Proteasome as a Catalyst for cGAS-STING Activation in Alzheimer's Disease

Misfolded proteins and protein degradation systems have contributed significantly to the understanding of Alzheimer's disease (AD). The ubiquitin-proteasome system (UPS), is vital for clearing abnormal proteins that could trigger inflammation if accumulated. Neurons are particularly vulnerable to UPS impairment due to their high reliance on precise protein homeostasis for function and survival. Findings from the studies of the 5×FAD and tau-P301S mice revealed that the synaptic proteasome function is impaired even in the early stages, a phase before overt plaque formation, correlating with early memory deficits. Blocking proteasome function in healthy neurons causes AD-like effects, such as oxidative stress, synaptic loss, and cognitive decline.

Conversely, boosting UPS activity can reverse these effects. Deletion of a 26S proteasome subunit causes neurodegeneration and Lewy-like inclusions, accompanied by abnormal mitochondria, linking proteasome failure to mitochondrial dysfunction and neuronal damage that extends beyond protein aggregation. Increased production of reactive oxygen species (ROS) can damage mitochondrial lipids and proteins, compromise membrane integrity, and ultimately cause membrane rupture. This occurs due to abnormal protein aggregation caused by proteasomal failure, which disrupts redox balance. Although UPS is involved in mitochondrial quality control, its impairment weakens the removal of damaged mitochondrial proteins, leading to oxidative stress that eventually causes mitochondrial membrane collapse. This collapse can then leak mitochondrial DNA into the cytosol. This leaked mtDNA acts as a damage-associated molecular pattern, thereby activating the cyclic GMP-AMP synthase (cGAS) and stimulator of interferon genes (STING) DNA-sensing pathway, to cause neuroinflammation.

It has been shown in a neuron-specific proteasome knockout mouse that the cGAS-STING pathway was activated, as evidenced by increased protein levels of cGAS and STING, and pro-inflammatory factors, such as STAT1, NF-κB, IL-1β, TNF-α, and IL-6, as well as signs of neurodegeneration, including decreased brain weight and necroptosis markers. These results link proteasomal dysfunction to immune responses and cell death in the brain

Researchers here conduct a meta-analysis of clinical trial results for the effects of resistance exercise on cognitive function. As might be expected given what is known of the effects of exercise on health, the amassed data strongly indicates that programs of resistance exercise improve cognitive function in older people. Mechanistically, it is known that exercise reduces inflammation, increases blood flow to the brain, improves immune function, improves mitochondrial function, increases autophagy, and touches on a range of downstream effects of those changes that may positively impact the state of the aging brain.

Resistance exercise has recently gained attention as a promising strategy to promote neuroplasticity and mitigate cognitive deterioration; however, evidence from randomized controlled trials (RCTs) remains inconsistent. This systematic review and meta-analysis aimed to evaluate the effects of resistance exercise on cognitive function in older adults.

17 RCTs (n=739) met the inclusion criteria. Pooled analyses showed that resistance training significantly improved overall cognitive function (standardized mean difference, SMD = 0.40), working memory (SMD = 0.44), verbal learning and memory (mean difference, MD = 3.01), and spatial memory span (SMD = 0.63), whereas effects on processing speed, executive function, and attention were not significant. Heterogeneity and publication bias analyses indicated stable and unbiased results. The magnitude of improvement appears to depend on age and exercise parameters, suggesting a potential dose-response relationship.

Link: https://doi.org/10.3389/fpsyt.2025.1708244

Researchers here provide data to support the claim that if everyone had the most favorable ε2 variant of the APOE gene, Alzheimer's disease incidence would be a tenth of what it is now. APOE is involved in cholesterol trafficking and metabolism, and in recent years it has been suggested that the APOE variants connected with higher risk of Alzheimer's cause dysfunction in microglia in the brain. Independently, that microglia become more inflammatory and dysfunctional with age has become an important line of research in the study of neurodegenerative conditions. Evidence strongly supports an important role for dysfunctional microglia in provoking the pathology associated with these conditions. Therapies focused on microglia have yet to emerge, but a number of approaches demonstrated in the laboratory and animal studies could lead to clinical trials given sufficient motivation and funding.

Variation in the APOE gene strongly affects Alzheimer's disease (AD) risk. However, the proportion of AD burden attributable to this variation requires clarification, which would help to elucidate the scope of strategies targeting apolipoprotein E (APOE) for AD prevention and treatment. We estimated the extents to which clinically diagnosed AD, AD neuropathology and all-cause dementia are attributable to the common APOE alleles in four large studies.

First, we used data on 171,105 and 289,150 participants aged ≥60 years from UK Biobank (UKB) and FinnGen, respectively. AD and all-cause dementia were ascertained from linked electronic health records in these cohorts. Second, we examined amyloid-β positivity from amyloid positron emission tomography scans of 4,415 participants of the A4 Study. Third, we analysed data from the Alzheimer's Disease Genetics Consortium (ADGC), where neuropathologically confirmed AD cases were compared to pathology-negative, cognitively intact controls (N = 5,007).

In each analysis, we estimated outcome risk among carriers of APOE risk alleles ε3 and ε4, relative to individuals with an ε2/ε2 genotype, and calculated attributable fractions to show the proportions of the outcomes due to ε3 and ε4. For AD, fractions ranged from 71.5% in FinnGen to 92.7% in the ADGC. In A4, 85.4% of cerebral amyloidosis was attributable to ε3 and ε4. The proportions of all-cause dementia attributable to ε3 and ε4 in UKB and FinnGen were 44.4% and 45.6%, respectively. Without strong underlying risks from APOE ε3 and ε4, almost all AD and half of all dementia would not occur. Intervening on APOE should be prioritised to facilitate dementia prevention.

Link: https://doi.org/10.1038/s44400-025-00045-9

The thymus is a small inner organ near the heart that is responsible for the maturation of T cells of the adaptive immune system. The supply of new T cells is critical to the maintenance of effective immune function over time. Unfortunately the thymus atrophies over the course of adult life, and in most people is largely made up of inactive fat tissue by as early as 50 years of age. The resulting diminished supply of replacement cells ensures that the T cell population thereafter becomes ever more made up of malfunctioning, exhausted, and senescent cells incapable of mounting an effective response.

Given the pressing need for ways to restore lost immune function in older individuals, it is good to see that a fair number of biotech startup companies are now competing to develop means of regenerating the aged thymus. After something of an abandonment of efforts following 2010s work on FOXN1 as a regulator of thymic growth, the past few years have seen a number of programs make the leap from academia to industry. Hopefully one or more will result in a form of therapy that is both effective and cost-effective.

The primary challenge presented by the thymus is targeted delivery of therapeutics. Quite a few approaches are known to kickstart the thymus into regrowth of the active regions of tissue capable of nurturing new T cells. Unfortunately they all produce serious side-effects in other tissues when delivered at sufficient high systemic doses to ensure that enough of the therapeutic make it to the thymus. For example, delivery of recombinant keratinocyte growth factor (KGF) reliably regrows the thymus in aged mice and non-human primates. There is a human drug based on KGF, used sparingly for some complications of cancer therapy. Dosing with this drug at levels sufficient to regrow the human thymus would result in very unpleasant complications, sufficiently serious to disqualify its use in this context.

There are as yet no robustly demonstrated ways to target therapies to the thymus other than direct injection, a procedure that carries sufficient cost and risk to make it infeasible for widespread use in older individuals. Thus while the new biotech startup noted in today's article is working on a growth factor approach for thymic regeneration, in reality that means that they are working on some combination of delivery system and therapy that can limit the effects of growth factors to the target thymic tissue. That is the core challenge, delivery.

Thymus regeneration startup emerges to 'restore immune function'

Swiss biotech TECregen emerged today with seed financing to develop a pipeline of therapies designed to regenerate the thymus and boost the aging immune system. The company is built around the idea that restoring the thymus can restore immune function at its source. The gradual loss of thymic function is increasingly viewed as a biological bottleneck for healthy aging. A shrinking thymus contributes to weaker responses to vaccines, slower recovery from infections and diminished immune surveillance against emerging cancers.

TECregen is developing a class of biologic drugs it calls thymopoietics, engineered to regenerate thymic epithelial cells and rebuild the microenvironment required for effective T-cell production. Thymic epithelial cells are the structural and functional backbone of the thymus; without them, T cells cannot mature properly. By rejuvenating this cellular niche, TECregen aims to restart the production of healthy, diverse T cells and restore immune resilience across a range of conditions, from immune aging to cancer-related immune suppression.

The basis of TECregen's approach involves applying advanced ligand engineering to growth factor biology. Growth factors are potent signaling molecules that influence inflammation, tissue repair, and regeneration, including processes within the thymus. According to the company, historic attempts to use growth factors therapeutically have been hampered by systemic toxicity and poor tissue selectivity, as these molecules can trigger unwanted effects in multiple organs. TECregen aims to engineer these signals to be functionally selective and tissue-targeted, with the goal of concentrating their activity in the thymus while minimizing off-target effects.