Senolytics and the compression of late-life mortality

Compression of morbidity by interventions that steepen the survival curve

Longevity research aims to extend the healthspan while minimizing the duration of disability and morbidity, known as the sickspan. Most longevity interventions in model organisms extend healthspan, but it is not known whether they compress sickspan relative to the lifespan. Here, we present a theory that predicts which interventions compress relative sickspan, based on the shape of the survival curve. Interventions such as caloric restriction that extend mean lifespan while preserving the shape of the survival curve, are predicted to extend the sickspan proportionally, without compressing it. Conversely, a subset of interventions that extend lifespan and steepen the shape of the survival curve are predicted to compress the relative sickspan. We explain this based on the saturating-removal mathematical model of aging, and present evidence from longitudinal health data in mice, Caenorhabditis elegans and Drosophila melanogaster. We apply this theory to identify potential interventions for compressing the sickspan in mice, and to combinations of longevity interventions. This approach offers potential strategies for compressing morbidity and extending healthspan.

Cellular Senescence in Health, Disease, and Lens Aging

Background: Cellular senescence is a state of irreversible cell cycle arrest that serves as a critical regulator of tissue homeostasis, aging, and disease. While transient senescence contributes to development, wound healing, and tumor suppression, chronic senescence drives inflammation, tissue dysfunction, and age-related pathologies, including cataracts. Lens epithelial cells (LECs), essential for maintaining lens transparency, are particularly vulnerable to oxidative stress-induced senescence, which accelerates lens aging and cataract formation. This review examines the dual role of senescence in LEC function and its implications for age-related cataractogenesis, alongside emerging senotherapeutic interventions. Methods: This review synthesizes findings on the molecular mechanisms of senescence, focusing on oxidative stress, mitochondrial dysfunction, and the senescence-associated secretory phenotype (SASP). It explores evidence linking LEC senescence to cataract formation, highlighting key studies on stress responses, DNA damage, and antioxidant defense. Recent advances in senotherapeutics, including senolytics and senomorphics, are analyzed for their potential to mitigate LEC senescence and delay cataract progression. Conclusions: LEC senescence is driven by oxidative damage, mitochondrial dysfunction, and impaired redox homeostasis. These factors activate senescence path-ways, including p53/p21 and p16/Rb, resulting in cell cycle arrest and SASP-mediated inflammation. The accumulation of senescent LECs reduces regenerative capacity, disrupts lens homeostasis, and contributes to cataractogenesis. Emerging senotherapeutics, such as dasatinib, quercetin, and metformin, show promise in reducing the senescent cell burden and modulating the SASP to preserve lens transparency.

Senolytics and cell senescence: historical and evolutionary perspectives

Senolytics are a new class of anti-aging drugs developed to selectively kill 'senescent' cells that are considered harmful in normal aging. More than 20 drug trials are ongoing with diverse 'senolytic cocktails'. This commentary on recent reviews of senolytics gives a historical context of mammalian cell senescence that enabled these new drugs. While cell senescence is considered harmful to aging tissues, many studies show its essential role in some regenerative and developmental processes for which senolytic drugs may interfere. Longer-term studies of side effects are needed before senolytics are considered for general clinical practice. The wide occurrence of cell senescence in eukaryotes, yeast to fish to humans, and suggests an ancient eukaryotic process that evolved multiple phenotypes.

Geroscience and pathology: a new frontier in understanding age-related diseases

Geroscience, a burgeoning discipline at the intersection of aging and disease, aims to unravel the intricate relationship between the aging process and pathogenesis of age-related diseases. This paper explores the pivotal role played by geroscience in reshaping our understanding of pathology, with a particular focus on age-related diseases. These diseases, spanning cardiovascular and cerebrovascular disorders, malignancies, and neurodegenerative conditions, significantly contribute to the morbidity and mortality of older individuals. We delve into the fundamental cellular and molecular mechanisms underpinning aging, including mitochondrial dysfunction and cellular senescence, and elucidate their profound implications for the pathogenesis of various age-related diseases. Emphasis is placed on the importance of assessing key biomarkers of aging and biological age within the realm of pathology. We also scrutinize the interplay between cellular senescence and cancer biology as a central area of focus, underscoring its paramount significance in contemporary pathological research. Moreover, we shed light on the integration of anti-aging interventions that target fundamental aging processes, such as senolytics, mitochondria-targeted treatments, and interventions that influence epigenetic regulation within the domain of pathology research. In conclusion, the integration of geroscience concepts into pathological research heralds a transformative paradigm shift in our understanding of disease pathogenesis and promises breakthroughs in disease prevention and treatment.

The meaning of adaptation in aging: insights from cellular senescence, epigenetic clocks and stem cell alterations

With recent rapid progress in research on aging, there is increasing evidence that many features commonly considered to be mechanisms or drivers of aging in fact represent adaptations. Here, we examine several such features, including cellular senescence, epigenetic aging and stem cell alterations. We draw a distinction between the causes and consequences of aging and define short-term consequences as 'responses' and long-term ones as 'adaptations'. We also discuss 'damaging adaptations', which despite having beneficial effects in the short term, lead to exacerbation of the initial insult and acceleration of aging. Features commonly recognized as 'basic mechanisms of the aging process' are critically examined for the possibility of their adaptation-driven emergence from processes such as cell competition and the wound-like features of the aging body. Finally, we speculate on the meaning of these interactions for the aging process and their relevance for the development of antiaging interventions.

Anti-Aging of the Nervous System and Related Neurodegenerative Diseases With Chinese Herbal Medicine

Human beings have always pursued a prolonged lifespan, while the aging of the nervous system is associated with a large variety of diseases. Pathological aging of the nervous system results in a series of neurodegenerative diseases and can cause disability and death in the elderly. Therefore, there is an urgent need for the prevention and treatment of nervous system aging. Chinese herbal medicines have a long history, featuring rich and safe ingredients, and have great potential for the development of anti-aging treatment. We searched the publications on PubMed with key words "anti-aging of the nervous system" and "Chinese herbal medicine" in recent 10 years, and found sixteen Chinese herbal medicines. Then by comparing their popularity of use as well as active components based on the research articles, five common Chinese herbal medicines namely Ginseng Radix, Lycii Fructus, Astragali Radix, Coptidis Rhizoma and Ginkgo Folium, were confirmed to be the most related to anti-nervous system aging and neural degenerative diseases. At the same time, the active ingredients, research models, action mechanisms and curative effects of these five common Chinese herbal medicines were reviewed. From the five common Chinese herbal medicines reviewed in this paper, many encouraging effects of Chinese herbal medicines on treating nervous system aging and related diseases were revealed and more potent herbs would be explored with the help of the proposed possible mechanisms.

Combining stem cell rejuvenation and senescence targeting to synergistically extend lifespan

Why biological age is a major risk factor for many of the most important human diseases remains mysterious. We know that as organisms age, stem cell pools are exhausted while senescent cells progressively accumulate. Independently, induction of pluripotency via expression of Yamanaka factors (Oct4, Klf4, Sox2, c-Myc; OKSM) and clearance of senescent cells have each been shown to ameliorate cellular and physiological aspects of aging, suggesting that both processes are drivers of organismal aging. But stem cell exhaustion and cellular senescence likely interact in the etiology and progression of age-dependent diseases because both undermine tissue and organ homeostasis in different if not complementary ways. Here, we combine transient cellular reprogramming (stem cell rejuvenation) with targeted removal of senescent cells to test the hypothesis that simultaneously targeting both cell-fate based aging mechanisms will maximize life and health span benefits. We find that OKSM extends lifespan and show that both interventions protect the intestinal stem cell pool, lower inflammation, activate pro-stem cell signaling pathways, and synergistically improve health and lifespan. Our findings suggest that a combination therapy, simultaneously replacing lost stem cells and removing senescent cells, shows synergistic potential for anti-aging treatments. Our finding that transient expression of both is the most effective suggests that drug-based treatments in non-genetically tractable organisms will likely be the most translatable.

New hallmarks of ageing: a 2022 Copenhagen ageing meeting summary

Genomic instability, telomere attrition, epigenetic alterations, mitochondrial dysfunction, loss of proteostasis, deregulated nutrient-sensing, cellular senescence, stem cell exhaustion, and altered intercellular communication were the original nine hallmarks of ageing proposed by López-Otín and colleagues in 2013. The proposal of these hallmarks of ageing has been instrumental in guiding and pushing forward research on the biology of ageing. In the nearly past 10 years, our in-depth exploration on ageing research has enabled us to formulate new hallmarks of ageing which are compromised autophagy, microbiome disturbance, altered mechanical properties, splicing dysregulation, and inflammation, among other emerging ones. Amalgamation of the 'old' and 'new' hallmarks of ageing may provide a more comprehensive explanation of ageing and age-related diseases, shedding light on interventional and therapeutic studies to achieve healthy, happy, and productive lives in the elderly.

The role of senescence in cellular plasticity: Lessons from regeneration and development and implications for age-related diseases

Senescence is a cellular state which involves cell cycle arrest and a proinflammatory phenotype, and it has traditionally been associated with cellular and organismal aging. However, increasing evidence suggests key roles in tissue growth and regrowth, especially during development and regeneration. Conversely, cellular plasticity-the capacity of cells to undergo identity change, including differentiation and dedifferentiation-is associated with development and regeneration but is now being investigated in the context of age-related diseases such as Alzheimer disease. Here, we discuss the paradox of the role for cellular senescence in cellular plasticity: senescence can act as a cell-autonomous barrier and a paracrine driver of plasticity. We provide a conceptual framework for integrating recent data and use the interplay between cellular senescence and plasticity to provide insight into age-related diseases. Finally, we argue that age-related diseases can be better deciphered when senescence is recognized as a core mechanism of regeneration and development.