Longevity Papers

Chronological age is an imperfect estimate of molecular aging. Epigenetic age, derived from DNA methylation data, provides a more nuanced representation of aging-related biological processes. We examine the bidirectional relationship between epigenetic age and brain health events (stroke, dementia, late-life depression) using data from 4,018 participants. Participants with a prior brain health event are 4% epigenetically older (β = 0.04, SE = 0.01), indicating these conditions are associated with accelerated aging beyond that captured by chronological age. Additionally, a one standard deviation increase in epigenetic age is associated with 70% higher odds of experiencing a brain health event in the next four years (OR = 1.70, 95% CI = 1.16-2.50), suggesting epigenetic age acceleration is not just a consequence but also a predictor of poor brain health. Mendelian Randomization analyses replicate these findings, supporting their causal nature. Our results support using epigenetic age as a biomarker to evaluate interventions aimed at preventing and promoting recovery after brain health events.

Accessible and non-invasive biomarkers that measure human ageing processes and the risk of developing age-related disease are paramount in preventative healthcare. Here, we describe a novel framework to train saliva-based DNA methylation (DNAm) biomarkers that are reproducible and biologically interpretable. By leveraging a reliability dataset with replicates across tissues, we demonstrate that it is possible to transfer knowledge from blood DNAm to saliva DNAm data using DNAm proxies of blood proteins (EpiScores). We apply these methods to create a new saliva-based epigenetic clock (InflammAge) that quantifies systemic chronic inflammation (SCI) in humans. Using a large blood DNAm human cohort with linked electronic health records and over 18,000 individuals (Generation Scotland), we demonstrate that InflammAge significantly associates with all-cause mortality, disease outcomes, lifestyle factors, and immunosenescence; in many cases outperforming the widely used SCI biomarker C-reactive protein (CRP). We propose that our biomarker discovery framework and InflammAge will be useful to improve understanding of the molecular mechanisms underpinning human ageing and to assess the impact of gero-protective interventions.

Immunity declines with age. This results in a higher risk of age-related diseases, diminished ability to respond to new infections and reduced response to vaccines. The causes of this immune dysfunction are cellular senescence, which occurs in both lymphoid and non-lymphoid tissue, and chronic, low-grade inflammation known as 'inflammageing'. In this Review article, we highlight how the processes of inflammation and senescence drive each other, leading to loss of immune function. To break this cycle, therapies are needed that target the interactions between the altered tissue environment and the immune system instead of targeting each component alone. We discuss the relative merits and drawbacks of therapies that are directed at eliminating senescent cells (senolytics) and those that inhibit inflammation (senomorphics) in the context of tissue niches. Furthermore, we discuss therapeutic strategies designed to directly boost immune cell function and improve immune surveillance in tissues.

The bone marrow (BM) microenvironment plays a crucial role in regulating hematopoiesis, yet the molecular and functional changes associated with aging in humans remain poorly understood. Using single-cell RNA sequencing (scRNA-seq), we uncovered transcriptional shifts in BM endothelial cells (EC) and mesenchymal stem cells (MSC) during aging. Our analysis revealed that aged sinusoidal EC adopt a prothrombotic, exhibit mitochondrial dysfunction, and have compromised vascular function. Additionally, we identified a unique arterial EC subset, present only in aged individuals, associated with transcriptional elongation and senescence processes and characterized by RAB13 expression. MSC from aged subjects displayed an impaired matrix remodeling and epithelial-mesenchymal transition, driven partly by a subpopulation of THY1+ profibrotic stromal cells absent in young subjects. Aged MSC were also characterized by an increased ATP-oxidative metabolism and reduced protein folding capacity. Finally, using immunofluorescent imaging and spatial transcriptomics, we confirmed the presence of RAB13+ senescent EC in aged samples and revealed significant age-related changes in cell-cell communication within the BM niche. In summary, this work provides a comprehensive view of the molecular diversity, cellular interactions, and spatial organization of aged EC and MSC, offering novel insights and potential targets that could be exploited for preventing aged-associated changes in humans.

The focus of aging research has shifted from increasing lifespan to enhancing healthspan to reduce the time spent living with disability. Despite significant efforts to develop biomarkers of aging, few studies have focused on biomarkers of healthspan. We developed a proteomics-based signature of healthspan (healthspan proteomic score (HPS)) using proteomic data from the Olink Explorer 3072 assay in the UK Biobank Pharma Proteomics Project (53,018 individuals and 2920 proteins). A lower HPS was associated with higher mortality risk and several age-related conditions, such as COPD, diabetes, heart failure, cancer, myocardial infarction, dementia, and stroke. HPS showed superior predictive accuracy for these outcomes compared to other biological age measures. Proteins associated with HPS were enriched in hallmark pathways such as immune response, inflammation, cellular signaling, and metabolic regulation. The external validity was established using the Essential Hypertension Epigenetics study with proteomic data also from the Olink Explorer 3072 and complementary epigenetic data, making it a valuable tool for assessing healthspan and as a potential surrogate marker to complement existing proteomic and epigenetic biological age measures in geroscience-guided studies.

Autophagy is a housekeeping catabolic process crucial for maintaining cell, tissue and organism functions. Through the years, the study of animal models with tissue-specific inactivation of autophagy essential genes has allowed us to understand its protective roles in the context of multiple human diseases, including cancer and neurodegeneration. However, due to the essential nature of autophagy, the effects of its systemic inhibition in mammals have not been explored in detail. Here, we report the generation of ATG4A-only mice, simultaneously deficient for three of the four mammalian ATG4 proteases (ATG4B, ATG4C and ATG4D). Through extensive characterization of ATG4A-only cells, which show a severe (albeit not complete) deficiency in autophagic activity, we define the specific roles of ATG4A protease towards ATG8 proteins (its physiological substrates), shedding some light into the evolutionarily-acquired complexity of mammalian ATG4-ATG8 system. Moreover, we show that the profound whole-body autophagy deficiency of ATG4A-only mice not only impacts the function of multiple tissues, but also leads to the development of an accelerated aging phenotype, characterized by the accumulation of genetic damage, systemic senescence, and premature death. Thus, through the analysis of ATG4A-only mice and other murine models deficient for ATG4 proteases, we do not only provide new insights on how autophagy maintains cell, tissue, and organismal homeostasis, but also show for the first time that the degree of autophagic competency ultimately emerges as a critical determinant of organismal longevity.