Longevity Papers

As populations age worldwide, understanding the biology of aging and its contribution to disease becomes increasingly important. Cellular senescence, a hallmark of aging, plays a pivotal role in shaping inter-organ communication and systemic health. Once viewed primarily as a local mechanism to prevent the proliferation of damaged cells, senescence is now recognized as a dynamic, multifaceted process that influences physiology across the lifespan. Through senescence-associated secretory phenotype (SASP) proteins and other signaling modalities, including metabolites, extracellular vesicles, immune cells, and neural circuits, senescent cells contribute to both homeostatic regulation and the propagation of chronic inflammation, fibrosis, and age-related disease. These effects are often context-dependent, and senescence in one organ can influence distant tissues, driving asynchronous aging and disease vulnerability. This review examines the mechanisms by which senescent cells facilitate inter-organ communication, including emerging roles for blood-borne factors, immune cell dynamics, and neuroendocrine signals. We highlight illustrative examples of organ crosstalk and emphasize the potential translational relevance of these pathways. We also examine therapeutic strategies aimed at modulating senescence, including senolytics, senomorphics, and interventions targeting specific SASP components, as well as the potential of lifestyle modifications to mitigate biological aging. Understanding senescence and the associated inter-organ communication offers new insights into aging biology and opens promising avenues for addressing age-related diseases in an integrated, organ-spanning framework.

Mitochondrial membrane potential (MMP) is essential for mitochondrial functions, yet current methods for modulating MMP lack precise spatial and temporal control. Here, we present an optogenetic system that enables reversible formation of inter-mitochondrial contacts (mito-contacts) with high spatiotemporal precision. Blue light stimulation induces rapid formation of mito-contacts, which fully dissipate upon cessation of illumination. These light-induced mito-contacts can enhance MMP, leading to increased ATP production under stress conditions. Moreover, in human retinal cells and C. elegans, high MMP induced by mito-contacts alleviates the deleterious effects of prolonged blue light exposure, restoring energy metabolism and extending organismal lifespan. This optogenetic approach provides a powerful tool for modulating MMP and offers potential therapeutic applications for diseases linked to mitochondrial dysfunction.

Cellular senescence is a well-established tumor-suppressive cell cycle arrest program. However, chronic inflammation through the senescence-associated secretory phenotype (SASP) can alternatively drive immune suppression and cancer progression. Using prostate cancer patient samples and murine models, we find p16+ and p21+ senescent cells accumulate throughout malignant progression and associate with immune suppression. Single cell sequencing revealed p16 and p21 mark distinct epithelial and stromal senescent populations, with p21+ non-tumor cells expressing the highest SASP. p21+ stromal cell removal blocked the SASP to reverse immune suppression and slow tumor growth. Senolytic BCL-xL inhibitor treatment could clear p21+ stromal senescent cells, reactivating anti-tumor CD8+ T cell immunity and inhibiting prostate tumor progression in mice. Suppression of BCL-xL or p21 also potentiated anti-PD-1 ICB in preclinical prostate cancer models. Our findings demonstrate that targeting p21+ senescent stromal populations can yield therapeutic benefits in advanced prostate cancer through activating anti-tumor immunity and enhancing immunotherapy outcomes.

Living animals reach their end-of-life through a stereotypic set of fascinating but poorly understood processes. The discovery, first in flies and later in nematodes and zebrafish, of the "Smurf phenotype" has provided a valuable tool to investigate ageing and its associated physiological changes. Using the Smurfs, we have shown an evolutionarily conserved end-of-life transition across Drosophilids, nematodes, and zebrafish. This tool has been key to identify the discontinuous nature of ageing and predict impending death from natural causes as well as from environmental stresses. This phenotype led us to propose a two-phase perspective of ageing: a first phase where individuals are apparently healthy and have low risk of mortality, but show an age-dependent and increasing risk of entering a second phase, marked by more pronounced hallmarks of ageing and a markedly increased risk of death. Here, we test whether these two consecutive phases of ageing separated by the Smurf transition are a conserved feature of ageing in the mammals using Mus musculus as a model. We performed a longitudinal longevity study using both males and females from two different mouse genetic backgrounds and by integrating physiological, metabolic, and molecular measurements with the life history of approximately 150 mice. We show the existence of a phenotypic signature typical of the last phase of life, observable at any chronological age. Validating the two-phase ageing model in a mammalian organism allows better characterization of the high risk of imminent death and would extend its implications to a broader range of species for ageing research. The Stage 1 version of this Registered Report was submitted on 19th January 2022.

Age is the predominant risk factor for late-onset Alzheimer's disease, and interventions that reduce biological age may be therapeutic. We previously reported that bezisterim, a novel anti-inflammatory insulin sensitizer, modulated epigenetic age acceleration (EAA) in a randomized, placebo-controlled, 7-month Alzheimer's disease trial. Building on prior evidence linking bezisterim-induced EAA changes to improved cognitive and functional outcomes, we conducted integrative analyses to elucidate underlying molecular mechanisms. Bezisterim significantly reduced EAA across 12 independent biological clocks, reinforcing its impact on validated aging biomarkers, and identifying targets predominantly involved in inflammation and cognition, including transcriptional regulators that orchestrate broader gene networks. Genome-wide methylation profiling revealed 2,154 genes with significant differential promoter methylation between bezisterim and placebo groups. Treatment increased promoter methylation - suggesting transcriptional repression - in 433 genes known to be associated with aging and disease processes, including microglial neuroinflammation, pro-inflammatory kinase activity, cognitive decline, lipid metabolism, and transcriptional regulation. Conversely, treatment-decreased methylation of 15 genes potentially improved autophagy, and increased anti-inflammatory phosphatases and macrophage polarization. Analyses were conducted to search for correlations between promoter methylation and the 31 previous clinical measures in bezisterim and placebo subjects. Significant correlations (72 bezisterim, 13 placebo) suggest that methylation differences contribute to observed clinical differences. The majority of the correlations in bezisterim subjects were associated with neurologic and metabolic improvements, and 12 of 72 were correlated with 2-5 clinical measures each, potentially emphasizing their contribution to clinical benefit. Bezisterim appears to exert pleiotropic effects through coordinated modulation of aging-related epigenetic programs, potentially counteracting neurodegenerative processes at the intersection of inflammation, metabolism, and transcriptional control.

Aging biomarkers play a vital role in understanding longevity, with the potential to improve clinical decisions and interventions. Existing aging clocks typically use blood, vitals, or imaging collected in a clinical setting. Wearables, in contrast, can make frequent and inexpensive measurements throughout daily living. Here we develop PpgAge, an aging clock using photoplethysmography at the wrist from a consumer wearable. Using the Apple Heart & Movement Study (n = 213,593 participants; >149 million participant-days), our observational analysis shows that this non-invasive and passively collected aging clock accurately predicts chronological age and captures signs of healthy aging. Participants with an elevated PpgAge gap (i.e., predicted age greater than chronological age) have significantly higher diagnosis rates of heart disease, heart failure, and diabetes. Elevated PpgAge gap is also a significant predictor of incident heart disease events (and new diagnoses) when controlling for relevant risk factors. PpgAge also associates with behavior, including smoking, exercise, and sleep. Longitudinally, PpgAge exhibits a sharp increase during pregnancy and concurrent with certain types of cardiac events.

The advent of in vivo reprogramming through transient expression of the Yamanaka factors (OCT4, SOX2, KLF4, and c-MYC) holds strong promise for regenerative medicine, despite ongoing concerns about safety and clinical applicability. This review synthesizes recent advances in in vivo reprogramming, focusing on its potential to restore regenerative competence and promote rejuvenation across diverse tissues, including the retina, skeletal muscle, heart, liver, brain, and intestine. We highlight mechanistic parallels and distinctions between injury-induced dedifferentiation and OSKM-mediated reprogramming, emphasizing the roles of dedifferentiation, transient regenerative progenitors, and epigenetic remodeling. Critical safety considerations-such as teratoma formation, organ failure, and loss of cell identity-are discussed alongside strategies designed to mitigate these risks, like cyclic induction and targeted delivery. Finally, we briefly note the growing translational interest in this field, alongside directing readers to recent reviews for detailed coverage of biotech initiatives. Collectively, this work underscores the transformative potential of in vivo reprogramming for both tissue regeneration and rejuvenation, while stressing the importance of precise spatiotemporal control for its safe clinical application.