There is always room to argue about dosing and methodology; there was some of that after the ITP reported that fisetin has no effect on longevity. But one can't argue with the large number of mice used and the efforts to impose rigor on the experimental process. Today's open access paper is the latest ITP publication in which possibly promising ways to modestly slow aging were demonstrated to have no effect once studied more rigorously. Of note, α-ketoglutarate is in the list; this had promising data in mice, considerable interest from a number of research and development groups, and made it all the way to a human clinical trial - which failed. In earlier mouse studies, α-ketoglutarate dosing was lifelong. The ITP tried starting at 18 months of age, which didn't work, and here tried starting at 7 months of aging, which also didn't work. If you'd like to look over the data, it can be found at the Mouse Phenome Database.

At a high level, the ITP results obtained over the years can be taken as support for the idea that attempting to discover bioactive molecules that favorably manipulate metabolism is not a viable path forward. It is very challenging, results vary meaningfully between groups, between species, by dose, by age of onset of treatment, and after all of that the best expected outcome is only a modest slowing of aging. This is not a good approach to the problem of aging. Instead, rational design of therapies that can repair known forms of cell and tissue damage seems far more likely to succeed in producing large enough and robust enough effects to care about.

Astaxanthin, meclizine, mitoglitazone, pioglitazone, alpha-ketoglutarate, mifepristone, methotrexate, and atorvastatin-telmisartan do not increase lifespan in UM-HET3 mice

The Interventions Testing Program (ITP) evaluated eleven compounds in genetically heterogeneous UM-HET3 mice to assess their potential to extend lifespan. These interventions included both novel agents and previously tested compounds administered at novel doses or starting ages. Despite prior evidence suggesting lifespan benefits of these proposed interventions in other models or under different conditions, none of the tested compounds significantly increased lifespan in male or female mice. Notably, astaxanthin, mitoglitazone, and meclizine - previously associated with lifespan extension in the ITP - showed no benefit when administered at different doses or starting at later ages.

In females, astaxanthin, late-start mitoglitazone, and pioglitazone were associated with significantly reduced lifespan when pooling the data from all three sites. However, site-specific analysis revealed unusually long lifespans in control females at The Jackson Laboratory, prompting reanalysis using data from the other two sites and only showed a negative effect for mitoglitazone and pioglitazone. This study underscores the importance of rigorous, multi-site testing and highlights the challenges of translating promising initial findings into consistent lifespan benefits at other doses or with alternate starting ages. These results suggest that timing and dosage are critical variables in aging intervention studies and reinforce the need for cautious interpretation of single-site or single-cohort findings.

There is always room to argue about dosing and methodology; there was some of that after the ITP reported that fisetin has no effect on longevity. But one can't argue with the large number of mice used and the efforts to impose rigor on the experimental process. Today's open access paper is the latest ITP publication in which possibly promising ways to modestly slow aging were demonstrated to have no effect once studied more rigorously. Of note, α-ketoglutarate is in the list; this had promising data in mice, considerable interest from a number of research and development groups, and made it all the way to a human clinical trial - which failed. In earlier mouse studies, α-ketoglutarate dosing was lifelong. The ITP tried starting at 18 months of age, which didn't work, and here tried starting at 7 months of aging, which also didn't work. If you'd like to look over the data, it can be found at the Mouse Phenome Database.

At a high level, the ITP results obtained over the years can be taken as support for the idea that attempting to discover bioactive molecules that favorably manipulate metabolism is not a viable path forward. It is very challenging, results vary meaningfully between groups, between species, by dose, by age of onset of treatment, and after all of that the best expected outcome is only a modest slowing of aging. This is not a good approach to the problem of aging. Instead, rational design of therapies that can repair known forms of cell and tissue damage seems far more likely to succeed in producing large enough and robust enough effects to care about.

Astaxanthin, meclizine, mitoglitazone, pioglitazone, alpha-ketoglutarate, mifepristone, methotrexate, and atorvastatin-telmisartan do not increase lifespan in UM-HET3 mice

The Interventions Testing Program (ITP) evaluated eleven compounds in genetically heterogeneous UM-HET3 mice to assess their potential to extend lifespan. These interventions included both novel agents and previously tested compounds administered at novel doses or starting ages. Despite prior evidence suggesting lifespan benefits of these proposed interventions in other models or under different conditions, none of the tested compounds significantly increased lifespan in male or female mice. Notably, astaxanthin, mitoglitazone, and meclizine - previously associated with lifespan extension in the ITP - showed no benefit when administered at different doses or starting at later ages.

In females, astaxanthin, late-start mitoglitazone, and pioglitazone were associated with significantly reduced lifespan when pooling the data from all three sites. However, site-specific analysis revealed unusually long lifespans in control females at The Jackson Laboratory, prompting reanalysis using data from the other two sites and only showed a negative effect for mitoglitazone and pioglitazone. This study underscores the importance of rigorous, multi-site testing and highlights the challenges of translating promising initial findings into consistent lifespan benefits at other doses or with alternate starting ages. These results suggest that timing and dosage are critical variables in aging intervention studies and reinforce the need for cautious interpretation of single-site or single-cohort findings.

The rare gems

Vaccination works because a small number of B cells, which recognize the vaccine antigen upon encountering it, multiply enormously and mature into plasma cells that can each produce thousands of antibody molecules per second and survive in the bone marrow for years. This is why a childhood measles shot still protects you decades later.

Most antibodies produced during an infection or vaccination recognize only one version of a virus surface protein and stop working if the virus mutates. For instance, the flu virus mutates too fast for the immune system to keep up, so we need a flu shot every year [2]. A similar problem arises with HIV and many other infections.

However, very rarely – usually as a result of prolonged infection that drives extensive antibody mutation – a person’s immune system produces broadly neutralizing antibodies (bNAbs), which target regions of the pathogen that can’t easily mutate, mostly because those regions are essential for the pathogen’s function [3].

If you harvest these antibodies and transfer them to a different person, they protect that person from the disease, but their numbers wane quickly. Scientists have also tried genetically engineering B cells to produce those rare antibodies. While it’s doable in principle, engineered mature B cells don’t reliably generate the specific long-lived memory and plasma cell populations that confer prolonged immunity.

In a new study from the Rockefeller University, published in Science, the researchers attempted to solve this problem by moving one step upstream and genetically altering hematopoietic stem and progenitor cells (HSPC), which give rise to various blood cell types, including B cells.

Long-lasting immunity achieved

After creating an ingenious construct that silences the cell’s original antibody sequence and replaces it with a new one, which produces an anti-HIV bNAb, the researchers made sure that the resulting engineered HSPCs successfully differentiate into B cells in mice. Several weeks later, a small percentage of the recipients’ B cells were indeed producing the coveted bNAbs.

Given those small percentages of edited B cells, would it be enough to actually provide long-lasting immunity? The team immunized the mice with an HIV antigen designed to bind to this specific bNAb and tracked the antibody levels in blood over many months.

Despite the low fraction of edited B cells, vaccination produced high antibody levels in blood. They declined slowly over more than nine months, but a single booster shot amplified them again. Tests confirmed that the antibody could block HIV across multiple viral strains.

The team then wanted to know how few edited HSPCs are needed, since editing HSPCs is technically difficult. As few as about 370 cultured HSPCs, of which only 29 were actually edited, still produced measurable antibody levels.

HSPCs consist of two populations: long-term hematopoietic stem cells (LT-HSCs), which self-renew for life, and progenitors, which can produce blood cells for a while but eventually run out. For a lifelong therapy, the edits need to be in the LT-HSCs. The researchers confirmed that at least some of the edited cells were indeed LT-HSCs.

Protein production and protection

The team then created a construct that expresses an unrelated fluorescent protein alongside the antibody. This allowed them to track the edited B cells in a mouse’s body. The cells behaved exactly like normal antigen-responding B cells: they entered germinal centers in lymph nodes (sites where B cells mature) and expanded there, then they populated the spleen and bone marrow as plasma cells and so-called class-switched memory B cells – a signature of a mature immune response.

Importantly, this also provided a proof of concept for tailored protein production in vivo: theoretically, such cells can be used to produce various proteins the body needs, upon activation by a vaccine shot. Possible cargoes include enzymes, clotting factors for hemophilia, and so on. However, the system’s mechanics (such as rapid expansion) create dosing problems, so not every protein would be a good fit.

For pathogens like HIV, a single antibody isn’t enough, so the team also created a construct with two different anti-HIV bNAbs. Both antibodies were produced simultaneously at high levels, and the researchers were able to boost them selectively.

The team then switched to human HSPCs, which they injected into mice that were engineered to support human immune cell development (humanized mice). Editing efficiency in human cells was actually much higher than in mouse cells: an important translational milestone.

Finally, the researchers tested their platform against two other pathogens. Mice carrying engineered HSPCs with anti-malaria antibodies produced serum that stopped the parasite (Plasmodium falciparum) from crossing into human liver cells in culture, a key early step of malaria infection.

In the second experiment, they engineered HSPCs with a broadly neutralizing anti-influenza antibody. Mice were vaccinated against one flu strain and then challenged with totally different, highly lethal strains that the vaccine wouldn’t protect against on its own. Several-times-lethal doses of the virus killed most mice in the control group but none or few in the study groups.

“Our goal is to permanently impact the genome with a single injection, so that the body can make proteins of interest,” says Harald Hartweger, a research assistant professor in Michel Nussenzweig’s Laboratory of Molecular Immunology. “We want to find a way of making any protein – HIV antibodies, of course, but also solutions that address protein deficiencies and metabolic disease, as well as an antibody to treat inflammatory disease or the flu, or one for cancer. This is a step in that direction – showing the feasibility of making life-saving proteins.”

Literature

[1] Harald Hartweger et al. (2026). B lymphocyte protein factories produced by hematopoietic stem cell gene editing. Science, 392, eadz8994

[2] Treanor, J. (2004). Influenza vaccine—outmaneuvering antigenic shift and drift. New England Journal of Medicine, 350(3), 218-220.

[3] Landais, E., & Moore, P. L. (2018). Development of broadly neutralizing antibodies in HIV-1 infected elite neutralizers Retrovirology, 15(1), 61.

Some animals can regrow lost body parts. Salamanders and frog tadpoles can rebuild entire limbs after amputation. Mammals cannot. For decades, biologists have tried to understand why. Limb regeneration begins with wound healing. After amputation, cells at the injury site must rapidly seal the wound and switch into regenerative cell types. In amphibians, this process runs smoothly. In mammals, it stalls early. Wound closure is slow and scar formation takes over, blocking regeneration. One key difference lies in the environment. Amphibian larvae develop in water, where oxygen levels are lower than in air. Moreover, many regeneration-competent species live in aquatic environments. Meanwhile, mammalian tissues are typically exposed to higher oxygen levels after injury.

Researchers amputated developing limbs from frog tadpoles and mouse embryos and cultured them outside the body under controlled oxygen conditions. Oxygen levels were lowered to match aquatic environments or raised to levels close to air. They tracked how cells responded by measuring wound closure, cell movement, gene activity, metabolism, and epigenetic states, including changes to DNA packaging. The work focused on HIF1A, a protein that acts as a cellular oxygen sensor. When oxygen is low, HIF1A becomes stable and activates programs that set the stage for wound healing and regeneration.

Lowering oxygen levels had a clear effect on the limbs of mouse embryos. Under reduced oxygen, mouse cells closed wounds faster and showed signs of entering a regenerative program. Stabilizing HIF1A produced similar effects, even when oxygen levels remained high. Frog tadpoles behaved differently. Their limbs regenerated efficiently across a wide range of oxygen levels, including levels well above those normally found in air. Molecular analysis showed that their cells maintain stable HIF1A activity even when oxygen increases, due to low expression of genes that normally shut this pathway down.

By comparing frogs, axolotls, mice, and human datasets, the team found a consistent pattern. Regeneration-competent amphibians show reduced oxygen-sensing capacity, allowing regenerative programs to be initiated and sustained. Mammals show the opposite pattern. Their cells respond strongly to oxygen and switch regenerative programs off soon after injury. The results suggest that mammalian limbs retain latent regenerative potential at early stages, depending on how cells respond to environmental signals such as oxygen. This means that adjusting oxygen-sensing pathways might one day improve wound healing or regenerative responses in humans.

Link: https://www.tuebingen.mpg.de/280592/news_publication_26212730_transferred

Statistics show clear differences in the population's immune system according to sex: men are more susceptible to infections and cancers, while women have stronger immune responses, which translate, for example, into better responses to vaccines. Even so, with a more reactive immune system, the probability of the body attacking itself also increases, causing 80% of autoimmune disease development to occur in women. A new study has demonstrate that immunological aging follows different dynamics between men and women, identifying the cells and genes responsible for the process, and providing a molecular explanation for the differences that previously were only observed globally in the population.

The results reveal that women present more pronounced changes in the immune system with age, with an increase in inflammatory immune cells. This finding could help explain why autoimmune diseases are mainly developed by women, especially at advanced ages, as well as the worsening of certain inflammatory pathologies after menopause. On the other hand, the changes associated with immune system aging observed in men are globally less extensive, but an increase in certain blood cells presenting pre-leukemia alterations was observed, a fact that could explain why some blood cancers are more frequent in older men.

Finding these patterns was possible thanks to the analysis of blood samples from nearly 1,000 people of different ages covering the entire adult life, combined with a technology capable of analyzing each cell individually, called single-cell RNA sequencing. In total, the researchers analyzed the activity of 20,000 genes in more than one million blood cells, which allowed them to identify how the immune system changes over the years and detect clear differences between sexes.

Link: https://www.bsc.es/news/bsc-news/new-bsc-study-reveals-the-first-time-the-female-immune-system-changes-much-more-men-age

There is no dramatically powerful rejuvenation therapy hiding in the mechanisms of calorie restriction, heat stress, cold stress, and so forth. Nonetheless, a sizable fraction (and perhaps even the majority) of research programs aimed at treating aging as a medical condition are focused on manipulation of stress responses. Today's open access paper is an example of the type. In this case, the stress takes the form of mild mitochondrial dysfunction, encouraging the cell to take steps to defend itself. The hundreds of mitochondria present in every cell manufacture adenosine triphosphate (ATP), a vital chemical energy store molecule. They also generate stress-inducing reactive oxygen species as a byproduct of this activity. When mitochondrial become dysfunctional, oxidative molecule production increases and ATP production diminishes. Our cells have evolved to treat this as a call to action: they increase efforts to clear out underperforming mitochondria, produce more antioxidants, and increase other maintenance activities. When mitochondrial dysfunction is mild, the result is an overall benefit.

Targeting Mitochondrial Stress Responses: Terbinafine and Miglustat as Novel Lifespan and Healthspan Modulators

Age-related diseases share numerous biological impairments. Among these, mitochondrial dysfunction has emerged as a key driver of aging and disease progression. Mitochondria are essential organelles participating in numerous cellular functions, including energy harvesting, biogenesis, regulation of homeostasis and apoptosis. Changes in mitochondrial integrity not only impact cellular metabolism but also critically influence whole-body metabolism, health, and lifespan. Consequently, mitochondrial-targeted therapies have gained significant attention for treating metabolic and age-related conditions.

One promising approach is the pharmacological induction of the mitochondrial stress response (MSR), an adaptive pathway that restores proteostasis and promotes resilience to stress. While severe mitochondrial dysfunction is detrimental, mild mitochondrial stress can extend lifespan and delay age-related decline, a phenomenon known as mitohormesis. MSR-inducing compounds have shown potential in mitigating age-related decline and improving outcomes in various conditions.

A key component of the MSR is the mitochondrial unfolded protein response (UPRmt), which coordinates cellular responses to mitochondrial stress and maintains mitochondrial proteostasis. In C. elegans, the UPRmt is initiated by misfolded proteins, leading to the activation of the transcription factor associated with stress 1 (ATFS-1), which induces chaperones, proteases, and metabolic regulators to re-establish mitochondrial homeostasis. Similar mechanisms are observed in mammals, where ATF4 and ATF5 mediate mitochondrial stress responses. Notably, mild mitochondrial perturbations, including mitochondrial ribosomal protein knockdown or antibiotic treatment, like doxycycline, can activate the UPRmt and extend lifespan in C. elegans and other species.

Despite progress in aging research, few pharmacological agents robustly activate the MSR without adverse effects. While antibiotics like doxycycline robustly induce the UPRmt, their antibacterial activity disrupts the microbiome and contributes to antibiotic resistance, limiting their therapeutic potential. Thus, identifying mitochondrial stress inducers without antibacterial properties is crucial.

Here, we screened 770 FDA-approved drugs to identify novel MSR activators. Using C. elegans, we identified terbinafine and miglustat as mitochondrial stress modulators that extend lifespan and healthspan without antibacterial activity. Mechanistically, both compounds activate the UPRmt and engage DAF-16-dependent insulin/IGF-1 signaling, distinct from its canonical activation, revealing a coordinated stress adaptation program. Importantly, terbinafine and miglustat also induce mitochondrial stress responses in human cells, supporting their translational relevance and highlighting new opportunities to target mitochondrial dysfunction in aging.