Uncoupling lifespan and healthspan in Caenorhabditis elegans longevity mutants

Improved resilience and proteostasis mediate longevity upon DAF-2 degradation in old age

Little is known about the possibility of reversing age-related biological changes when they have already occurred. To explore this, we have characterized the effects of reducing insulin/IGF-1 signaling (IIS) during old age. Reduction of IIS throughout life slows age-related decline in diverse species, most strikingly in the nematode Caenorhabditis elegans. Here we show that even at advanced ages, auxin-induced degradation of DAF-2 in single tissues, including neurons and the intestine, is still able to markedly increase C. elegans lifespan. We describe how reversibility varies among senescent changes. While senescent pathologies that develop in mid-life were not reversed, there was a rejuvenation of the proteostasis network, manifesting as a restoration of the capacity to eliminate otherwise intractable protein aggregates that accumulate with age. Moreover, resistance to several stressors was restored. These results support several new conclusions. (1) Loss of resilience is not solely a consequence of pathologies that develop in earlier life. (2) Restoration of proteostasis and resilience by inhibiting IIS is a plausible cause of the increase in lifespan. And (3), most interestingly, some aspects of the age-related transition from resilience to frailty can be reversed to a certain extent. This raises the possibility that the effect of IIS and related pathways on resilience and frailty during aging in higher animals might possess some degree of reversibility.

Consolidating multiple evolutionary theories of ageing suggests a need for new approaches to study genetic contributions to ageing decline

Understanding mechanisms of ageing remains a complex challenge for biogerontologists, but recent adaptations of evolutionary ageing theories offer a compelling lens in which to view both age-related molecular and physiological deterioration. Ageing is commonly associated with progressive declines in biochemical and molecular processes resulting from damage accumulation, yet the role of continued developmental gene activation is less appreciated. Natural selection pressures are at their highest in youthful periods to modify gene expression towards maximising reproductive capacity. After sexual maturation, selective pressure diminishes, subjecting individuals to maladaptive pleiotropic gene functions that were once beneficial for developmental growth but become pathogenic later in life. Due to this selective 'shadowing' in ageing, mechanisms to counter such hyper/hypofunctional genes are unlikely to evolve. Interventions aimed at targeting gene hyper/hypofunction during ageing might, therefore, represent an attractive therapeutic strategy. The nematode Caenorhabditis elegans offers a strong model for post-reproductive mechanistic and therapeutic investigations, yet studies examining the mechanisms of, and countermeasures against, ageing decline largely intervene from larval stages onwards. Importantly, however, lifespan extending conditions frequently impair early-life fitness and fail to correspondingly increase healthspan. Here, we consolidate multiple evolutionary theories of ageing and discuss data supporting hyper/hypofunctional changes at a global molecular and functional level in C. elegans, and how classical lifespan-extension mutations alter these dynamics. The relevance of such mutant models for exploring mechanisms of ageing are discussed, highlighting that post-reproductive gene optimisation represents a more translatable approach for C. elegans research that is not constrained by evolutionary trade-offs. Where some genetic mutations in C. elegans that promote late-life health map accordingly with healthy ageing in humans, other widely used genetic mutations that extend worm lifespan are associated with life-limiting pathologies in people. Lifespan has also become the gold standard for quantifying 'ageing', but we argue that gerospan compression (i.e., 'healthier' ageing) is an appropriate goal for anti-ageing research, the mechanisms of which appear distinct from those regulating lifespan alone. There is, therefore, an evident need to re-evaluate experimental approaches to study the role of hyper/hypofunctional genes in ageing in C. elegans.

Neural ageing and synaptic plasticity: prioritizing brain health in healthy longevity

Ageing is characterized by a gradual decline in the efficiency of physiological functions and increased vulnerability to diseases. Ageing affects the entire body, including physical, mental, and social well-being, but its impact on the brain and cognition can have a particularly significant effect on an individual's overall quality of life. Therefore, enhancing lifespan and physical health in longevity studies will be incomplete if cognitive ageing is over looked. Promoting successful cognitive ageing encompasses the objectives of mitigating cognitive decline, as well as simultaneously enhancing brain function and cognitive reserve. Studies in both humans and animal models indicate that cognitive decline related to normal ageing and age-associated brain disorders are more likely linked to changes in synaptic connections that form the basis of learning and memory. This activity-dependent synaptic plasticity reorganises the structure and function of neurons not only to adapt to new environments, but also to remain robust and stable over time. Therefore, understanding the neural mechanisms that are responsible for age-related cognitive decline becomes increasingly important. In this review, we explore the multifaceted aspects of healthy brain ageing with emphasis on synaptic plasticity, its adaptive mechanisms and the various factors affecting the decline in cognitive functions during ageing. We will also explore the dynamic brain and neuroplasticity, and the role of lifestyle in shaping neuronal plasticity.

Inhibition of IL-11 signalling extends mammalian healthspan and lifespan

For healthspan and lifespan, ERK, AMPK and mTORC1 represent critical pathways and inflammation is a centrally important hallmark1-7. Here we examined whether IL-11, a pro-inflammatory cytokine of the IL-6 family, has a negative effect on age-associated disease and lifespan. As mice age, IL-11 is upregulated across cell types and tissues to regulate an ERK-AMPK-mTORC1 axis to modulate cellular, tissue- and organismal-level ageing pathologies. Deletion of Il11 or Il11ra1 protects against metabolic decline, multi-morbidity and frailty in old age. Administration of anti-IL-11 to 75-week-old mice for 25 weeks improves metabolism and muscle function, and reduces ageing biomarkers and frailty across sexes. In lifespan studies, genetic deletion of Il11 extended the lives of mice of both sexes, by 24.9% on average. Treatment with anti-IL-11 from 75 weeks of age until death extends the median lifespan of male mice by 22.5% and of female mice by 25%. Together, these results demonstrate a role for the pro-inflammatory factor IL-11 in mammalian healthspan and lifespan. We suggest that anti-IL-11 therapy, which is currently in early-stage clinical trials for fibrotic lung disease, may provide a translational opportunity to determine the effects of IL-11 inhibition on ageing pathologies in older people.

Milk Fat Globule Membrane-Containing Protein Powder Promotes Fitness in Caenorhabditis elegans

Milk-derived peptides and milk fat globule membrane (MFGM) have gained interest as health-promoting food ingredients. However, the mechanisms by which these nutraceuticals modulate the function of biological systems often remain unclear. We utilized Caenorhabditis elegans to elucidate how MFGM-containing protein powder (MProPow), previously used in a clinical trial, affect the physiology of this model organism. Our results demonstrate that MProPow does not affect lifespan but promotes the fitness of the animals. Surprisingly, gene expression analysis revealed that MProPow decreases the expression of genes functioning on innate immunity, which also translates into reduced survival on pathogenic bacteria. One of the innate immunity-associated genes showing reduced expression upon MProPow supplementation is cpr-3, the homolog of human cathepsin B. Interestingly, knockdown of cpr-3 enhances fitness, but not in MProPow-treated animals, suggesting that MProPow contributes to fitness by downregulating the expression of this gene. In summary, this research highlights the value of C. elegans in testing the biological activity of food supplements and nutraceuticals. Furthermore, this study should encourage investigations into whether milk-derived peptides and MFGM mediate their beneficial effects through the modulation of cathepsin B expression in humans.

The neuron-specific IIS/FOXO transcriptome in aged animals reveals regulatory mechanisms of cognitive aging

Cognitive decline is a significant health concern in our aging society. Here, we used the model organism C. elegans to investigate the impact of the IIS/FOXO pathway on age-related cognitive decline. The daf-2 Insulin/IGF-1 receptor mutant exhibits a significant extension of learning and memory span with age compared to wild-type worms, an effect that is dependent on the DAF-16 transcription factor. To identify possible mechanisms by which aging daf-2 mutants maintain learning and memory with age while wild-type worms lose neuronal function, we carried out neuron-specific transcriptomic analysis in aged animals. We observed downregulation of neuronal genes and upregulation of transcriptional regulation genes in aging wild-type neurons. By contrast, IIS/FOXO pathway mutants exhibit distinct neuronal transcriptomic alterations in response to cognitive aging, including upregulation of stress response genes and downregulation of specific insulin signaling genes. We tested the roles of significantly transcriptionally-changed genes in regulating cognitive functions, identifying novel regulators of learning and memory. In addition to other mechanistic insights, a comparison of the aged vs young daf-2 neuronal transcriptome revealed that a new set of potentially neuroprotective genes is upregulated; instead of simply mimicking a young state, daf-2 may enhance neuronal resilience to accumulation of harm and take a more active approach to combat aging. These findings suggest a potential mechanism for regulating cognitive function with age and offer insights into novel therapeutic targets for age-related cognitive decline.

Biomarkers for aging in Caenorhabditis elegans high throughput screening

Aging is characterized by a functional decline in organism fitness over time due to a complex combination of genetic and environmental factors [ 1-4]. With an increasing elderly population at risk of age-associated diseases, there is a pressing need for research dedicated to promoting health and longevity through anti-aging interventions. The roundworm Caenorhabditis elegans is an established model organism for aging studies due to its short life cycle, ease of culture, and conserved aging pathways. These benefits also make the worm well-suited for high-throughput screening (HTS) methods to study biomarkers of the molecular changes, cellular dysfunction, and physiological decline associated with aging. Within this review, we offer a summary of recent advances in HTS techniques to study biomarkers of aging in C. elegans.

Jujubae Fructus extract prolongs lifespan and improves stress tolerance in Caenorhabditis elegans dependent on DAF-16/SOD-3

Jujubae Fructus, the fruit of Ziziphus jujuba Mill has been used as one of the medicine food homology species for thousands of years in China. Studies have shown that the active ingredients of Jujubae Fructus have a variety of biological effects, but its role in the aging process still lacks knowledge. Here, we investigated the effect of Jujubae Fructus extract (JE) on Caenorhabditis elegans lifespan and its potential mechanism. The lifespan of C. elegans treated with JE was signifificantly increased in a dose-dependent manner. In addition, JE treatment prolonged the reproductive period and increased normal activity during aging in C. elegans. Similarly, JE supplementation also enhanced the resistance to heat and oxidative stress in C. elegans. Furthermore, the mutant worms' lifespan assays demonstrated that JE requires daf-16 to prolong lifespan. DAF-16::GFP analysis of TJ356 showed that JE treatment translocates DAF-16::GFP to nucleus in transgenic worms. By analyzing the downstream of daf-16, we identify that JE may regulate sod3 downstream of daf-16. Mutant worms' lifespan and transgenic reporter gene expression assays revealed that increasing SOD-3 expression was critical for extending longevity in C. elegans with JE therapy. Collectively, these data indicate that JE may have an important role in C. elegans longevity that is dependent on DAF-16 and SOD-3.

Glucose-fed microbiota alters C. elegans intestinal epithelium and increases susceptibility to multiple bacterial pathogens

Overconsumption of dietary sugar can lead to many negative health effects including the development of Type 2 diabetes, metabolic syndrome, cardiovascular disease, and neurodegenerative disorders. Recently, the human intestinal microbiota, strongly associated with our overall health, has also been known to be affected by diet. However, mechanistic insight into the importance of the human intestinal microbiota and the effects of chronic sugar ingestion has not been possible largely due to the complexity of the human microbiome which contains hundreds of types of organisms. Here, we use an interspecies C. elegans/E. coli system, where E. coli are subjected to high sugar, then consumed by the bacterivore host C. elegans to become the microbiota. This glucose-fed microbiota results in a significant lifespan reduction accompanied by reduced healthspan (locomotion), reduced stress resistance, and changes in behavior and feeding. Lifespan reduction is also accompanied by two potential major contributors: increased intestinal bacterial density and increased concentration of reactive oxygen species. The glucose-fed microbiota accelerated the age-related development of intestinal cell permeability, intestinal distention, and dysregulation of immune effectors. Ultimately, the changes in the intestinal epithelium due to aging with the glucose-fed microbiota results in increased susceptibility to multiple bacterial pathogens. Taken together, our data reveal that chronic ingestion of sugar, such as a Western diet, has profound health effects on the host due to changes in the microbiota and may contribute to the current increased incidence of ailments including inflammatory bowel diseases as well as multiple age-related diseases.

Investigation of anti-aging and anti-infection properties of Jingfang Granules using the Caenorhabditis elegans model

Jingfang Granule (JFG), a traditional Chinese medicine, is frequently employed in clinical settings for the treatment of infectious diseases. Nevertheless, the anti-aging and anti-infection effects of JFG remain uncertain. In the present study, these effects were evaluated using the Caenorhabditis elegans (C. elegans) N2 as a model organism. The results demonstrated that JFG significantly increased the median lifespan of C. elegans by 31.2% at a dosage of 10 mg/mL, without any discernible adverse effects, such as alterations in the pharyngeal pumping rate or nematode motility. Moreover, JFG notably increased oviposition by 11.3%. Subsequent investigations revealed that JFG enhanced oxidative stress resistance in C. elegans by reducing reactive oxygen species levels and significantly improved survival rates in nematodes infected with Pseudomonas aeruginosa ATCC 9027. These findings suggest that JFG delays reproductive senescence in C. elegans and protects them from oxidative stress, thereby extending their lifespan. Additionally, JFG improves the survival of P. aeruginosa-infected nematodes. Consequently, JFG has potential as a candidate for the development of anti-aging and anti-infection functional medicines.

Lactobacillus paracasei subsp. paracasei 2004 improves health and lifespan in Caenorhabditis elegans

Recent research has highlighted the importance of the gut microbiome in regulating aging, and probiotics are interventions that can promote gut health. In this study, we surveyed several novel lactic acid bacteria to examine their beneficial effect on organismal health and lifespan in C. elegans. We found that animals fed some lactic acid bacteria, including L. acidophilus 1244 and L. paracasei subsp. paracasei 2004, grew healthy. Supplementation with the lactic acid bacterial strains L. acidophilus 1244 or L. paracasei subsp. paracasei 2004 significantly improved health, including food consumption, motility, and resistance to oxidative stressor, hydrogen peroxide. Our RNA-seq analysis showed that supplementation with L. paracasei subsp. paracasei 2004 significantly increased the expression of daf-16, a C. elegans FoxO homolog, as well as genes related to the stress response. Furthermore, daf-16 deletion inhibited the longevity effect of L. paracasei subsp. paracasei 2004 supplementation. Our results suggest that L. paracasei subsp. paracasei 2004 improves health and lifespan in a DAF-16-dependent manner.

The coupling between healthspan and lifespan in Caenorhabditis depends on complex interactions between compound intervention and genetic background

Aging is characterized by declining health that results in decreased cellular resilience and neuromuscular function. The relationship between lifespan and health, and the influence of genetic background on that relationship, has important implications in the development of pharmacological anti-aging interventions. Here we assessed swimming performance as well as survival under thermal and oxidative stress across a nematode genetic diversity test panel to evaluate health effects for three compounds previously studied in the Caenorhabditis Intervention Testing Program and thought to promote longevity in different ways - NP1 (nitrophenyl piperazine-containing compound 1), propyl gallate, and resveratrol. Overall, we find the relationships among median lifespan, oxidative stress resistance, thermotolerance, and mobility vigor to be complex. We show that oxidative stress resistance and thermotolerance vary with compound intervention, genetic background, and age. The effects of tested compounds on swimming locomotion, in contrast, are largely species-specific. In this study, thermotolerance, but not oxidative stress or swimming ability, correlates with lifespan. Notably, some compounds exert strong impact on some health measures without an equally strong impact on lifespan. Our results demonstrate the importance of assessing health and lifespan across genetic backgrounds in the effort to identify reproducible anti-aging interventions, with data underscoring how personalized treatments might be required to optimize health benefits.

Dual-Acting Nitric Oxide Donor and Phosphodiesterase Inhibitor TOP-N53 Increases Lifespan and Health Span of Caenorhabditis elegans

The quest for extending lifespan and promoting a healthy aging has been a longstanding pursuit in the field of aging research. The control of aging and age-related diseases by nitric oxide (NO) and cGMP signaling is a broadly conserved process from worms to human. Here we show that TOP-N53, a dual-acting NO donor and PDE5 inhibitor, can increase both lifespan and health span in C. elegans .

Ageing as a two-phase process: theoretical framework

Human ageing, along with the ageing of conventional model organisms, is depicted as a continuous and progressive decline of biological capabilities accompanied by an exponentially increasing mortality risk. However, not all organisms experience ageing identically and our understanding of the phenomenon is coloured by human-centric views. Ageing is multifaceted and influences a diverse range of species in varying ways. Some undergo swift declines post-reproduction, while others exhibit insubstantial changes throughout their existence. This vast array renders defining universally applicable "ageing attributes" a daunting task. It is nonetheless essential to recognize that not all ageing features are organism-specific. These common attributes have paved the way for identifying "hallmarks of ageing," processes that are intertwined with age, amplified during accelerated ageing, and manipulations of which can potentially modulate or even reverse the ageing process. Yet, a glaring observation is that individuals within a single population age at varying rates. To address this, demographers have coined the term 'frailty'. Concurrently, scientific advancements have ushered in the era of molecular clocks. These innovations enable a distinction between an individual's chronological age (time since birth) and biological age (physiological status and mortality risk). In 2011, the "Smurf" phenotype was unveiled in Drosophila, delineating an age-linked escalation in intestinal permeability that presages imminent mortality. It not only acts as a predictor of natural death but identifies individuals exhibiting traits normally described as age-related. Subsequent studies have revealed the phenotype in organisms like nematodes, zebrafish, and mice, invariably acting as a death predictor. Collectively, these findings have steered our conception of ageing towards a framework where ageing is not linear and continuous but marked by two distinct, necessary phases, discernible in vivo, courtesy of the Smurf phenotype. This framework includes a mathematical enunciation of longevity trends based on three experimentally measurable parameters. It facilitates a fresh perspective on the evolution of ageing as a function. In this article, we aim to delineate and explore the foundational principles of this innovative framework, emphasising its potential to reshape our understanding of ageing, challenge its conventional definitions, and recalibrate our comprehension of its evolutionary trajectory.

Rapid measurement of ageing by automated monitoring of movement of C. elegans populations

Finding new interventions that slow ageing and maintain human health is a huge challenge of our time. The nematode Caenorhabditis elegans offers a rapid in vivo method to determine whether a compound extends its 2 to 3-week lifespan. Measuring lifespan is the standard method to monitor ageing, but a compound that extends lifespan will not necessarily maintain health. Here, we describe the automated monitoring of C. elegans movement from early to mid-adulthood as a faster healthspan-based method to measure ageing. Using the WormGazer™ technology, multiple Petri dishes each containing several C. elegans worms are imaged simultaneously and non-invasively by an array of cameras that can be scaled easily. This approach demonstrates that most functional decline in C. elegans occurs during the first week of adulthood. We find 7 days of imaging is sufficient to measure the dose-dependent efficacy of sulfamethoxazole to slow ageing, compared to 40 days required for a parallel lifespan experiment. Understanding any negative consequences of interventions that slow ageing is important. We show that the long-lived mutant age-1(hx546) stays active for longer than the wild type but it moves slower in early adulthood. Thus, continuous analysis of movement can rapidly identify interventions that slow ageing while simultaneously revealing any negative effects on health.

Antioxidants green tea extract and nordihydroguaiaretic acid confer species and strain-specific lifespan and health effects in Caenorhabditis nematodes

The Caenorhabditis Intervention Testing Program (CITP) is an NIH-funded research consortium of investigators who conduct analyses at three independent sites to identify chemical interventions that reproducibly promote health and lifespan in a robust manner. The founding principle of the CITP is that compounds with positive effects across a genetically diverse panel of Caenorhabditis species and strains are likely engaging conserved biochemical pathways to exert their effects. As such, interventions that are broadly efficacious might be considered prominent compounds for translation for pre-clinical research and human clinical applications. Here, we report results generated using a recently streamlined pipeline approach for the evaluation of the effects of chemical compounds on lifespan and health. We studied five compounds previously shown to extend C. elegans lifespan or thought to promote mammalian health: 17α-estradiol, acarbose, green tea extract, nordihydroguaiaretic acid, and rapamycin. We found that green tea extract and nordihydroguaiaretic acid extend Caenorhabditis lifespan in a species-specific manner. Additionally, these two antioxidants conferred assay-specific effects in some studies-for example, decreasing survival for certain genetic backgrounds in manual survival assays in contrast with extended lifespan as assayed using automated C. elegans Lifespan Machines. We also observed that GTE and NDGA impact on older adult mobility capacity is dependent on genetic background, and that GTE reduces oxidative stress resistance in some Caenorhabditis strains. Overall, our analysis of the five compounds supports the general idea that genetic background and assay type can influence lifespan and health effects of compounds, and underscores that lifespan and health can be uncoupled by chemical interventions.

Geroprotective Effect of Levilactobacillus brevis and Weizmannia coagulans in Caenorhabditis elegans

The prophylactic use of lactic acid bacteria (LAB) to maintain human health is one of the most important research areas in recent times. LAB supplementation confers a wide range of health benefits to the host, but few studies have focused on their possible role in delaying the aging process. This study explored the health and life-promoting properties of two LAB, Levilactobacillus brevis and Weizmannia coagulans, using the Caenorhabditis elegans model. We found that L. brevis and W. coagulans enhanced the intestinal integrity and intestinal barrier functions without affecting the overall physiological functions of C. elegans. Wild-type worms preconditioned with LAB strains increased their survival under oxidative and thermal stress conditions by reducing intracellular reactive oxygen levels. Live L. brevis and W. coagulans significantly extended the lifespan of C. elegans under standard laboratory conditions independently of dietary restrictions. Genetic and reporter gene expression analysis revealed that L. brevis and W. coagulans extend lifespan via insulin/insulin-like growth factor-1 signaling and the p38 MAPK signaling axis. Furthermore, sirtuin, JNK MAPK, and mitochondrial respiratory complexes were found to be partially involved in W. coagulans-mediated lifespan extension and stress resilience. Preconditioning with LAB ameliorated age-related functional decline in C. elegans and reduced ectopic fat deposition in an NHR-49-dependent manner. Together, our findings indicated that L. brevis and W. coagulans are worth exploring further as "gerobiotic" candidates to delay aging and improve the healthspan of the host.

Decoding lifespan secrets: the role of the gonad in Caenorhabditis elegans aging

The gonad has become a central organ for understanding aging in C. elegans, as removing the proliferating stem cells in the germline results in significant lifespan extension. Similarly, when starvation in late larval stages leads to the quiescence of germline stem cells the adult nematode enters reproductive diapause, associated with an extended lifespan. This review summarizes recent advancements in identifying the mechanisms behind gonad-mediated lifespan extension, including comparisons with other nematodes and the role of lipid signaling and transcriptional changes. Given that the gonad also mediates lifespan regulation in other invertebrates and vertebrates, elucidating the underlying mechanisms may help to gain new insights into the mechanisms and evolution of aging.

Mitochondrial stress in GABAergic neurons non-cell autonomously regulates organismal health and aging

Mitochondrial stress within the nervous system can trigger non-cell autonomous responses in peripheral tissues. However, the specific neurons involved and their impact on organismal aging and health have remained incompletely understood. Here, we demonstrate that mitochondrial stress in γ-aminobutyric acid-producing (GABAergic) neurons in Caenorhabditis elegans ( C. elegans ) is sufficient to significantly alter organismal lifespan, stress tolerance, and reproductive capabilities. This mitochondrial stress also leads to significant changes in mitochondrial mass, energy production, and levels of reactive oxygen species (ROS). DAF-16/FoxO activity is enhanced by GABAergic neuronal mitochondrial stress and mediates the induction of these non-cell-autonomous effects. Moreover, our findings indicate that GABA signaling operates within the same pathway as mitochondrial stress in GABAergic neurons, resulting in non-cell-autonomous alterations in organismal stress tolerance and longevity. In summary, these data suggest the crucial role of GABAergic neurons in detecting mitochondrial stress and orchestrating non-cell-autonomous changes throughout the organism.

Disrupting the SKN-1 homeostat: mechanistic insights and phenotypic outcomes

The mechanisms that govern maintenance of cellular homeostasis are crucial to the lifespan and healthspan of all living systems. As an organism ages, there is a gradual decline in cellular homeostasis that leads to senescence and death. As an organism lives into advanced age, the cells within will attempt to abate age-related decline by enhancing the activity of cellular stress pathways. The regulation of cellular stress responses by transcription factors SKN-1/Nrf2 is a well characterized pathway in which cellular stress, particularly xenobiotic stress, is abated by SKN-1/Nrf2-mediated transcriptional activation of the Phase II detoxification pathway. However, SKN-1/Nrf2 also regulates a multitude of other processes including development, pathogenic stress responses, proteostasis, and lipid metabolism. While this process is typically tightly regulated, constitutive activation of SKN-1/Nrf2 is detrimental to organismal health, this raises interesting questions surrounding the tradeoff between SKN-1/Nrf2 cryoprotection and cellular health and the ability of cells to deactivate stress response pathways post stress. Recent work has determined that transcriptional programs of SKN-1 can be redirected or suppressed to abate negative health outcomes of constitutive activation. Here we will detail the mechanisms by which SKN-1 is controlled, which are important for our understanding of SKN-1/Nrf2 cytoprotection across the lifespan.

Single-worm quantitative proteomics reveals aging heterogeneity in isogenic Caenorhabditis elegans

The heterogeneity of aging has been investigated at cellular and organic levels in the mouse model and human, but the exploration of aging heterogeneity at whole-organism level is lacking. C. elegans is an ideal model organism for studying this question as they are self-fertilized and cultured in the same chamber. Despite the tremendous progress made in single-cell proteomic analysis, there is few single-worm proteomics studies about aging. Here, we apply single-worm quantitative mass spectrometry to quantify the heterogenous proteomic changes during aging across individuals, a total of 3524 proteins from 157 C. eleagns individuals were quantified. A reconstructed C. elegans aging trajectory and proteomic landscape of fast-aging individuals were used to analyze the heterogeneity of C. elegans aging. We characterized inter-individual proteomic variation during aging and revealed contributing factors that distinguish fast-aging individuals from their siblings.

Effect of Different Edible Trichosanthes Germplasm on Its Seed Oil to Enhance Antioxidant and Anti-Aging Activity in Caenorhabditis elegans

The seeds of various Trichosanthes L. plants have been frequently used as snacks instead of for traditional medicinal purposes in China. However, there is still a need to identify the species based on seeds from Trichosanthes germplasm for the potential biological activities of their seed oil. In this study, 18 edible Trichosanthes germplasm from three species were identified and distinguished at a species level using a combination of seed morphological and microscopic characteristics and nrDNA-ITS sequences. Seed oil from the edible Trichosanthes germplasm significantly enhanced oxidative stress tolerance, extended lifespan, delayed aging, and improved healthspan in Caenorhabditis elegans. The antioxidant activity of the seed oil exhibits a significant positive correlation with its total unsaturated fatty acid content among the 18 edible Trichosanthes germplasm, suggesting a genetic basis for this trait. The biological activities of seed oil varied among species, with T. kirilowii Maxim. and T. rosthornii Harms showing stronger effects than T. laceribractea Hayata.

Considering Caenorhabditis elegans Aging on a Temporal and Tissue Scale: The Case of Insulin/IGF-1 Signaling

The aging process is inherently complex, involving multiple mechanisms that interact at different biological scales. The nematode Caenorhabditis elegans is a simple model organism that has played a pivotal role in aging research following the discovery of mutations extending lifespan. Longevity pathways identified in C. elegans were subsequently found to be conserved and regulate lifespan in multiple species. These pathways intersect with fundamental hallmarks of aging that include nutrient sensing, epigenetic alterations, proteostasis loss, and mitochondrial dysfunction. Here we summarize recent data obtained in C. elegans highlighting the importance of studying aging at both the tissue and temporal scale. We then focus on the neuromuscular system to illustrate the kinetics of changes that take place with age. We describe recently developed tools that enabled the dissection of the contribution of the insulin/IGF-1 receptor ortholog DAF-2 to the regulation of worm mobility in specific tissues and at different ages. We also discuss guidelines and potential pitfalls in the use of these new tools. We further highlight the opportunities that they present, especially when combined with recent transcriptomic data, to address and resolve the inherent complexity of aging. Understanding how different aging processes interact within and between tissues at different life stages could ultimately suggest potential intervention points for age-related diseases.

Moderate dietary restriction delays the onset of age-associated sarcopenia in Caenorhabditis elegans due to reduced myosin UNC-54 degradation

Sarcopenia, a gradual decrease in skeletal muscle mass and strength, is a major component of frailty in the elderly, with age, (lack of) exercise and diet found to be the major risk factors. The nematode Caenorhabditis elegans is an important model of sarcopenia. Although many studies describe loss of muscle function in ageing C. elegans, surprisingly few report on the loss of muscle mass. Here, in order to quantify loss of muscle mass under various dietary restriction (DR) conditions, we used an internal GFP standard to determine levels of the major body wall muscle myosin (UNC-54) in transgenic unc-54::gfp worms over their lifespan. Myosin density linearly increased during the first week of adulthood and there was no significant effect of DR. In contrast, an exponential decrease in myosin density was seen during the second week of adulthood, with reduced rates of myosin loss for mild and medium DR compared to control. UNC-54 turnover rates, previously determined using pulse-labelling methods, correspond well with the t1/2 value found here for UNC-54-GFP using fluorescence (control t1/2 = 12.0 days), independently validating our approach. These data indicate that sarcopenia is delayed in worms under mild and medium DR due to a reduced rate of myosin UNC-54 degradation, thereby maintaining protein homeostasis.

Icariin Improves Stress Resistance and Extends Lifespan in Caenorhabditis elegans through hsf-1 and daf-2-Driven Hormesis

Aging presents an increasingly significant challenge globally, driven by the growing proportion of individuals aged 60 and older. Currently, there is substantial research interest in pro-longevity interventions that target pivotal signaling pathways, aiming not only to extend lifespan but also to enhance healthspan. One particularly promising approach involves inducing a hormetic response through the utilization of natural compounds defined as hormetins. Various studies have introduced the flavonoid icariin as beneficial for age-related diseases such as cardiovascular and neurodegenerative conditions. To validate its potential pro-longevity properties, we employed Caenorhabditis elegans as an experimental platform. The accumulated results suggest that icariin extends the lifespan of C. elegans through modulation of the DAF-2, corresponding to the insulin/IGF-1 signaling pathway in humans. Additionally, we identified increased resistance to heat and oxidative stress, modulation of lipid metabolism, improved late-life healthspan, and an extended lifespan upon icariin treatment. Consequently, a model mechanism of action was provided for icariin that involves the modulation of various players within the stress-response network. Collectively, the obtained data reveal that icariin is a potential hormetic agent with geroprotective properties that merits future developments.

Bisphosphonates attenuate age-related muscle decline in Caenorhabditis elegans

BACKGROUND

Age-related muscle decline (sarcopenia) associates with numerous health risk factors and poor quality of life. Drugs that counter sarcopenia without harmful side effects are lacking, and repurposing existing pharmaceuticals could expedite realistic clinical options. Recent studies suggest bisphosphonates promote muscle health; however, the efficacy of bisphosphonates as an anti-sarcopenic therapy is currently unclear.

METHODS

Using Caenorhabditis elegans as a sarcopenia model, we treated animals with 100 nM, 1, 10, 100 and 500 μM zoledronic acid (ZA) and assessed lifespan and healthspan (movement rates) using a microfluidic chip device. The effects of ZA on sarcopenia were examined using GFP-tagged myofibres or mitochondria at days 0, 4 and 6 post-adulthood. Mechanisms of ZA-mediated healthspan extension were determined using combined ZA and targeted RNAi gene knockdown across the life-course.

RESULTS

We found 100 nM and 1 μM ZA increased lifespan (P < 0.001) and healthspan [954 ± 53 (100 nM) and 963 ± 48 (1 μM) vs. 834 ± 59% (untreated) population activity AUC, P < 0.05]. 10 μM ZA shortened lifespan (P < 0.0001) but not healthspan (758.9 ± 37 vs. 834 ± 59, P > 0.05), whereas 100 and 500 μM ZA were larval lethal. ZA (1 μM) significantly improved myofibrillar structure on days 4 and 6 post-adulthood (83 and 71% well-organized myofibres, respectively, vs. 56 and 34% controls, P < 0.0001) and increased well-networked mitochondria at day 6 (47 vs. 16% in controls, P < 0.01). Genes required for ZA-mediated healthspan extension included fdps-1/FDPS-1 (278 ± 9 vs. 894 ± 17% population activity AUC in knockdown + 1 μM ZA vs. untreated controls, respectively, P < 0.0001), daf-16/FOXO (680 ± 16 vs. 894 ± 17%, P < 0.01) and agxt-2/BAIBA (531 ± 23 vs. 552 ± 8%, P > 0.05). Life/healthspan was extended through knockdown of igdb-1/FNDC5 (635 ± 10 vs. 523 ± 10% population activity AUC in gene knockdown vs. untreated controls, P < 0.01) and sir-2.3/SIRT-4 (586 ± 10 vs. 523 ± 10%, P < 0.05), with no synergistic improvements in ZA co-treatment vs. knockdown alone [651 ± 12 vs. 635 ± 10% (igdb-1/FNDC5) and 583 ± 9 vs. 586 ± 10% (sir-2.3/SIRT-4), both P > 0.05]. Conversely, let-756/FGF21 and sir-2.2/SIRT-4 were dispensable for ZA-induced healthspan [630 ± 6 vs. 523 ± 10% population activity AUC in knockdown + 1 μM ZA vs. untreated controls, P < 0.01 (let-756/FGF21) and 568 ± 9 vs. 523 ± 10%, P < 0.05 (sir-2.2/SIRT-4)].

CONCLUSIONS

Despite lacking an endoskeleton, ZA delays Caenorhabditis elegans sarcopenia, which translates to improved neuromuscular function across the life course. Bisphosphonates might, therefore, be an immediately exploitable anti-sarcopenia therapy.

Fermented cereal-origin gerobiotic cocktails promote healthy longevity in Caenorhabditis elegans

There is growing interest in dietary interventions, particularly gerobiotics, that directly target aging. Several single-strain gerobiotics have proven to be beneficial in alleviating aging and age-related functional declines across species, but multistrain/multispecies gerobiotics have been proven even more advantageous due to the potential synergy and additive effects among individual isolates. However, there is very limited research on how multistrain/multispecies gerobiotic combinations or cocktails extend healthy longevity. This study comprehensively analyzed probiotic bacteria from traditionally fermented Barnyard millet and compared their efficacy in promoting healthy longevity under various combinations using Caenorhabditis elegans. We have shown that dramatic lifespan extension can be achieved by combining gerobiotics, and the effect was found to be strictly strain-specific. Among the 120 combinations tested, we identified two synergistic gerobiotic combinations, cocktail 55 (combination of B. licheniformis PS70, L. delbrueckii subsp. bulgaricus PS77, and L. amylovorus PS60) and cocktail 112 (combination of L. delbrueckii subsp. bulgaricus PS77, L. lactis PS10, and P. pentosaceus PS91), extending the mean lifespan of C. elegans by up to 46.2% and 53.1%, respectively. Our mechanistic study showed that the life-promoting effect of cocktail 55 relied on the p38 MAPK-SKN-1 pathway, while cocktail 112 acted on multiple signaling pathways, including IIS, β-catenin, and TGF-β pathways, to achieve its impact on the host. Moreover, feeding gerobiotic cocktails improved several healthspan markers reported to decline with age. These observations showed that the gerobiotic cocktails target different subsets of the gene regulatory network controlling the aging process in C. elegans, thereby extending healthy longevity.

Polyphenols in Inner Ear Neurobiology, Health and Disease: From Bench to Clinics

There is substantial experimental and clinical interest in providing effective ways to both prevent and slow the onset of hearing loss. Auditory hair cells, which occur along the basilar membrane of the cochlea, often lose functionality due to age-related biological alterations, as well as from exposure to high decibel sounds affecting a diminished/damaged auditory sensitivity. Hearing loss is also seen to take place due to neuronal degeneration before or following hair cell destruction/loss. A strategy is necessary to protect hair cells and XIII cranial/auditory nerve cells prior to injury and throughout aging. Within this context, it was proposed that cochlea neural stem cells may be protected from such aging and environmental/noise insults via the ingestion of protective dietary supplements. Of particular importance is that these studies typically display a hormetic-like biphasic dose-response pattern that prevents the occurrence of auditory cell damage induced by various model chemical toxins, such as cisplatin. Likewise, the hormetic dose-response also enhances the occurrence of cochlear neural cell viability, proliferation, and differentiation. These findings are particularly important since they confirmed a strong dose dependency of the significant beneficial effects (which is biphasic), whilst having a low-dose beneficial response, whereas extensive exposures may become ineffective and/or potentially harmful. According to hormesis, phytochemicals including polyphenols exhibit biphasic dose-response effects activating low-dose antioxidant signaling pathways, resulting in the upregulation of vitagenes, a group of genes involved in preserving cellular homeostasis during stressful conditions. Modulation of the vitagene network through polyphenols increases cellular resilience mechanisms, thus impacting neurological disorder pathophysiology. Here, we aimed to explore polyphenols targeting the NF-E2-related factor 2 (Nrf2) pathway to neuroprotective and therapeutic strategies that can potentially reduce oxidative stress and inflammation, thus preventing auditory hair cell and XIII cranial/auditory nerve cell degeneration. Furthermore, we explored techniques to enhance their bioavailability and efficacy.

Antibiotics that target mitochondria extend lifespan in C. elegans

Aging is a continuous degenerative process caused by a progressive decline of cell and tissue functions in an organism. It is induced by the accumulation of damage that affects normal cellular processes, ultimately leading to cell death. It has been speculated for many years that mitochondria play a key role in the aging process. In the aim of characterizing the implications of mitochondria in aging, here we used Caenorhabditis elegans (C. elegans) as an organismal model treated a panel of mitochondrial inhibitors and assessed for survival. In our study, we assessed survival by evaluating worm lifespan, and we assessed aging markers by evaluating the pharyngeal muscle contraction, the accumulation of lipofuscin pigment and ATP levels. Our results show that treatment of worms with either doxycycline, azithromycin (inhibitors of the small and the large mitochondrial ribosomes, respectively), or a combination of both, significantly extended median lifespan of C. elegans, enhanced their pharyngeal pumping rate, reduced their lipofuscin content and their energy consumption (ATP levels), as compared to control untreated worms, suggesting an aging-abrogating effect for these drugs. Similarly, DPI, an inhibitor of mitochondrial complex I and II, was capable of prolonging the median lifespan of treated worms. On the other hand, subjecting worms to vitamin C, a pro-oxidant, failed to extend C. elegans lifespan and upregulated its energy consumption, revealing an increase in ATP level. Therefore, our longevity study reveals that mitochondrial inhibitors (i.e., mitochondria-targeting antibiotics) could abrogate aging and extend lifespan in C. elegans.

Effect of dietary restriction on health span in Caenorhabditis elegans: A systematic review

Dietary restriction (DR) interventions have demonstrated their efficacy in extending lifespan; however, the association between lifespan extension and health span remains unclear. This article aims to analyze the relationship between DR-induced lifespan and health span in Caenorhabditis elegans (C. elegans), a widely used animal model in lifespan studies. By examining various parameters such as lipofuscin accumulation (an aging marker) and locomotor and feeding capacities (indicators of muscle degradation rate), we have compiled papers that investigate and report on these DR-induced effects.The majority of the papers reviewed consistently demonstrate that DR improves both lifespan and health span in C. elegans. Worms subjected to DR exhibit slower lipofuscin accumulation compared to those fed ad libitum, indicating a reduction in age-related cellular damage. Additionally, DR-treated worms display a higher locomotion capacity, suggesting a slower rate of muscle degradation. However, it is worth noting that there are some discrepancies among the papers regarding feeding capacity. These contradictions can be attributed to the different methods employed to initiate DR. While many approaches slow muscle degeneration and enhance pumping rates through adaptation to limited food sources, other methods, such as using eat-2 mutant worms or interventions that mimic the effects of eat-2, reduce feeding capacity and consequently restrict food intake. In conclusion, the findings suggest a strong correlation between DR-induced longevity and the extension of health span in C. elegans, as evidenced by improvements in various health span parameters. DR interventions not only extend lifespan but also mitigate age-related markers and preserve locomotor capacity. Although conflicting results are observed regarding feeding capacity, the overall evidence supports the notion that DR promotes healthier aging in this animal model.

Effect of starvation on electrotaxis response

Caenorhabditis elegans is an ideal model for investigating the effects of extrinsic and intrinsic conditions on the behavioral changes of animals. Our group previously showed how different conditions influence the behavior of worms following an electric stimulus in a microfluidic channel, known as electrotaxis. In this study we describe the effect of starvation on the electrotaxis movement of animals. We show that acute starvation did not affect the electrotaxis response or dopaminergic neurons but extended the lifespan of animals.

Tubular lysosome induction couples animal starvation to healthy aging

Dietary restriction promotes longevity in several species via autophagy activation. However, changes to lysosomes underlying this effect remain unclear. Here using the nematode Caenorhabditis elegans, we show that the induction of autophagic tubular lysosomes (TLs), which occurs upon dietary restriction or mechanistic target of rapamycin inhibition, is a critical event linking reduced food intake to lifespan extension. We find that starvation induces TLs not only in affected individuals but also in well-fed descendants, and the presence of gut TLs in well-fed progeny is predictive of enhanced lifespan. Furthermore, we demonstrate that expression of Drosophila small VCP-interacting protein, a TL activator in flies, artificially induces TLs in well-fed worms and improves C. elegans health in old age. These findings identify TLs as a new class of lysosomes that couples starvation to healthy aging.

Mitochondrial sulfide promotes life span and health span through distinct mechanisms in developing versus adult treated Caenorhabditis elegans

Living longer without simultaneously extending years spent in good health ("health span") is an increasing societal burden, demanding new therapeutic strategies. Hydrogen sulfide (H2S) can correct disease-related mitochondrial metabolic deficiencies, and supraphysiological H2S concentrations can pro health span. However, the efficacy and mechanisms of mitochondrion-targeted sulfide delivery molecules (mtH2S) administered across the adult life course are unknown. Using a Caenorhabditis elegans aging model, we compared untargeted H2S (NaGYY4137, 100 µM and 100 nM) and mtH2S (AP39, 100 nM) donor effects on life span, neuromuscular health span, and mitochondrial integrity. H2S donors were administered from birth or in young/middle-aged animals (day 0, 2, or 4 postadulthood). RNAi pharmacogenetic interventions and transcriptomics/network analysis explored molecular events governing mtH2S donor-mediated health span. Developmentally administered mtH2S (100 nM) improved life/health span vs. equivalent untargeted H2S doses. mtH2S preserved aging mitochondrial structure, content (citrate synthase activity) and neuromuscular strength. Knockdown of H2S metabolism enzymes and FoxO/daf-16 prevented the positive health span effects of mtH2S, whereas DCAF11/wdr-23 - Nrf2/skn-1 oxidative stress protection pathways were dispensable. Health span, but not life span, increased with all adult-onset mtH2S treatments. Adult mtH2S treatment also rejuvenated aging transcriptomes by minimizing expression declines of mitochondria and cytoskeletal components, and peroxisome metabolism hub components, under mechanistic control by the elt-6/elt-3 transcription factor circuit. H2S health span extension likely acts at the mitochondrial level, the mechanisms of which dissociate from life span across adult vs. developmental treatment timings. The small mtH2S doses required for health span extension, combined with efficacy in adult animals, suggest mtH2S is a potential healthy aging therapeutic.

Structured Docosahexaenoic Acid (DHA) Enhances Motility and Promotes the Antioxidant Capacity of Aged C. elegans

The human lifespan has increased over the past century; however, healthspans have not kept up with this trend, especially cognitive health. Among nutrients for brain function maintenance, long-chain omega-3 polyunsaturated fatty acids (ω-3 LCPUFA): DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid) must be highlighted, particularly structured forms of EPA and DHA which were developed to improve bioavailability and bioactivity in comparison with conventional ω-3 supplements. This study aims to elucidate the effect of a structured triglyceride form of DHA (DHA-TG) on the healthspan of aged C. elegans. Using a thrashing assay, the nematodes were monitored at 4, 8, and 12 days of adulthood, and DHA-TG improved its motility at every age without affecting lifespan. In addition, the treatment promoted antioxidant capacity by enhancing the activity and expression of SOD (superoxide dismutase) in the nematodes. Lastly, as the effect of DHA-TG was lost in the DAF-16 mutant strain, it might be hypothesized that the effects of DHA need DAF-16/FOXO as an intermediary. In brief, DHA-TG exerted a healthspan-promoting effect resulting in both enhanced physical fitness and increased antioxidant defense in aged C. elegans. For the first time, an improvement in locomotive function in aged wild-type nematodes is described following DHA-TG treatment.

Geniposide-Rich Gardenia jasminoides Ellis Fruit Extract Increases Healthspan in Caenorhabditis elegans

The human life span has been markedly extended since the 1900s, but it has not brought healthy aging to everyone. This increase in life expectancy without an increase in healthspan is a major global concern that imposes considerable health care budgets and degrades the quality of life of older adults. Dietary interventions are a promising strategy to increase healthspan. In this study, we evaluated whether a Gardenia jasminoides Ellis fruit ethanol extract (GFE) increases the life span of Caenorhabditis elegans (C. elegans). Treatment with 10 mg/mL GFE increased the life span by 27.1% when compared to the vehicle group. GFE (10 mg/mL) treatment improved healthspan-related markers (pharyngeal pumping, muscle quality, age-pigment, and reactive oxygen species accumulation) and exerted a protective effect against amyloid β 1-42 toxicity. These effects of GFE are related to the inhibition of insulin/IGF-1 signaling and activation of SKN-1/Nrf, thereby promoting the expression of stress resistance-related genes. In addition, treatment with 10 mM geniposide, the most abundant component of GFE, improved healthspan-related markers and increased life span by 18.55% when compared to the vehicle group. Collectively, these findings demonstrate that GFE and its component geniposide increase the life span along with healthspan in C. elegans.

Partial inhibition of class III PI3K VPS-34 ameliorates motor aging and prolongs health span

Global increase of life expectancy is rarely accompanied by increased health span, calling for a greater understanding of age-associated behavioral decline. Motor independence is strongly associated with the quality of life of elderly people, yet the regulators for motor aging have not been systematically explored. Here, we designed a fast and efficient genome-wide screening assay in Caenorhabditis elegans and identified 34 consistent genes as potential regulators of motor aging. Among the top hits, we found VPS-34, the class III phosphatidylinositol 3-kinase that phosphorylates phosphatidylinositol (PI) to phosphatidylinositol 3-phosphate (PI(3)P), regulates motor function in aged but not young worms. It primarily functions in aged motor neurons by inhibiting PI(3)P-PI-PI(4)P conversion to reduce neurotransmission at the neuromuscular junction (NMJ). Genetic and pharmacological inhibition of VPS-34 improve neurotransmission and muscle integrity, ameliorating motor aging in both worms and mice. Thus, our genome-wide screening revealed an evolutionarily conserved, actionable target to delay motor aging and prolong health span.

frpr-18, a neuropeptide receptor, regulates organismal lifespan and stress tolerance in C. elegans

The mechanisms underlying neuropeptide signaling regulation of lifespan in Caenorhabditis elegans ( C. elegans ) remain unclear. FRPR-18 is a mammalian orexin/hypocretin-like receptor and modulates C. elegans arousal behavior by acting as a receptor for FLP-2 neuropeptide signaling, which is also associated with the systemic activation of the mitochondrial unfolded protein response (mitoUPR). Here we report our preliminary findings on the role of the frpr-18 gene in regulating lifespan and healthspan parameters, including stress resistance. Our results showed that frpr-18(ok2698) null mutants had a shorter lifespan and reduced survivability against thermal stress and paraquat treatment. On the other hand, loss of flp-2 function did not affect lifespan or paraquat tolerance but was necessary for normal thermal stress tolerance. These findings suggest that frpr-18 could play a role in regulating lifespan and stress resistance, possibly through flp-2 independent or parallel neuropeptide signaling pathways.

Angelica keiskei Impacts the Lifespan and Healthspan of Drosophila melanogaster in a Sex and Strain-Dependent Manner

Angelica keiskei is a perennial plant, belonging to the Apiaceae family and originating from Japan. This plant has been reported to act as a diuretic, analeptic, antidiabetic, hypertensive, tumor, galactagogue, and laxative. The mechanism of action of A. keiskei is not known, but previous studies have suggested that it may act as an antioxidant. In this work, we used Drosophila melanogaster to evaluate the impact of A. keiskei on lifespan and healthspan and its potential anti-aging mechanism by conducting multiple assays on three fly strains: w¹¹¹⁸, chico, and JIV. We observed that the extract extended lifespan and improved healthspan in a sex- and strain-dependent manner. A. keiskei extended lifespan and improved reproductive fitness in female flies and either had no effect or decreased survival and physical performance in males. The extract protected against the superoxide generator paraquat in both sexes. These sex-specific effects suggest that A. keiskei may act through age-specific pathways such as the insulin and insulin-like growth factor signaling (IIS) pathways. Upon examination, we found that the increased survival of A. keiskei-fed females was dependent on the presence of the insulin receptor substrate chico, supporting the role of IIS in the action of A. keiskei.

The longevity response to warm temperature is neurally controlled via the regulation of collagen genes

Studies in diverse species have associated higher temperatures with shorter lifespan and lower temperatures with longer lifespan. These inverse effects of temperature on longevity are traditionally explained using the rate of living theory, which posits that higher temperatures increase chemical reaction rates, thus speeding up the aging process. Recent studies have identified specific molecules and cells that affect the longevity response to temperature, indicating that this response is regulated, not simply thermodynamic. Here, we demonstrate that in Caenorhabditis elegans, functional loss of NPR-8, a G protein-coupled receptor related to mammalian neuropeptide Y receptors, increases worm lifespan at 25°C but not at 20°C or 15°C, and that the lifespan extension at 25°C is regulated by the NPR-8-expressing AWB and AWC chemosensory neurons as well as AFD thermosensory neurons. Integrative transcriptomic analyses revealed that both warm temperature and old age profoundly alter gene expression and that genes involved in the metabolic and biosynthetic processes increase expression at 25°C relative to 20°C, indicating elevated metabolism at warm temperature. These data demonstrate that the temperature-induced longevity response is neurally regulated and also provide a partial molecular basis for the rate of living theory, suggesting that these two views are not mutually exclusive. Genetic manipulation and functional assays further uncovered that the NPR-8-dependent longevity response to warm temperature is achieved by regulating the expression of a subset of collagen genes. As increased collagen expression is a common feature of many lifespan-extending interventions and enhanced stress resistance, collagen expression could be critical for healthy aging.

Photo-and thermo-regulation by photonic crystals for extended longevity of C. elegans

Methods allowing light energy to be modulated in a controllable fashion are potentially important for finding the correlation between light-related environmental factors and aging-related lifespan. Here, we report photo- and thermo-regulation based on photonic crystals (PCs) for extended longevity of C. elegans. We show that PCs can function as a regulator of visible spectrum to tune photonic energy received by C.elegans. We provide direct evidence that lifespan depends on photonic energy, and the use of PCs reflecting blue light (440-537nm) gives 8.3% increasement in lifespan. We demonstrate that the exposure to modulated light alleviates photo-oxidative stress and unfolded-protein response. We realize reflective passive cooling temperature using PCs, and favorable low temperature could be created for worms to extend lifespan. This work offers a new path based on PCs to resist negative effects light and temperature for longevity, provides an available platform for studying the role of light in aging.

Dauer larva-derived extracellular vesicles extend the life of Caenorhabditis elegans

There is growing evidence that extracellular vesicles (EVs) play a functional role in tissue repair and anti-aging by transferring the contents of donor cells to recipient cells. We hypothesized that Dauer (C. elegans), known as "ageless" nematodes, can also secrete extracellular vesicles and influence the lifespan of C. elegans. Here, we isolated EVs of dauer larvae (dauer EVs). Dauer EVs were characterized using transmission electron microscopy, nanoparticle tracking analysis (NTA), and Western blot analysis. Wild-type C. elegans were fed in the presence or absence of dauer EVs and tested for a range of phenotypes, including longevity, mobility and reproductive capacity. Results showed that dauer EVs increased the average lifespan of nematodes by 15.74%, improved mobility, slowed age-related pigmentation as well as body length, and reduced the accumulation of reactive oxygen species and lipids, while not impairing nematode reproductive capacity. These findings suggest that dauer EVs can extend the lifespan of C. elegans as well as the healthy lifespan by reducing ROS accumulation, with potential anti-aging capacity.

Transient inhibition of mitochondrial function by chrysin and apigenin prolong longevity via mitohormesis in C. elegans

Mild inhibition of mitochondrial function leads to longevity. Genetic disruption of mitochondrial respiratory components either by mutation or RNAi greatly extends the lifespan in yeast, worms, and drosophila. This has given rise to the idea that pharmacologically inhibiting mitochondrial function would be a workable strategy for postponing aging. Toward this end, we used a transgenic worm strain that expresses the firefly luciferase enzyme widely to evaluate compounds by tracking real-time ATP levels. We identified chrysin and apigenin, which reduced ATP production and increased the lifespan of worms. Mechanistically, we discovered that chrysin and apigenin transiently inhibit mitochondrial respiration and induce an early ROS, and the lifespan-extending effect is dependent on transient ROS formation. We also show that AAK-2/AMPK, DAF-16/FOXO, and SKN-1/NRF-2 are required for chrysin or apigenin-mediated lifespan extension. Temporary increases in ROS levels trigger an adaptive response in a mitohormetic way, thereby increasing oxidative stress capacity and cellular metabolic adaptation, finally leading to longevity. Thus, chrysin and apigenin represent a class of compounds isolated from natural products that delay senescence and improve age-related diseases by inhibiting mitochondrial function and shed new light on the function of additional plant-derived polyphenols in enhancing health and delaying aging. Collectively, this work provides an avenue for pharmacological inhibition of mitochondrial function and the mechanism underlining their lifespan-extending properties.

Adult-restricted gene knock-down reveals candidates that affect locomotive healthspan in C. elegans

Understanding how we can age healthily is a challenge at the heart of biogerontological interest. Whereas myriad genes are known to affect the lifespan of model organisms, effects of such interventions on healthspan-the period of life where an animal is considered healthy, rather than merely alive-are less clear. To understand relationships between life- and healthspan, in recent years several platforms were developed with the purpose of assessing both readouts simultaneously. We here relied on one such platform, the WorMotel, to study effects of adulthood-restricted knock-down of 130 Caenorhabditis elegans genes on the locomotive health of the animals along their lifespans. We found that knock-down of six genes affected healthspan while lifespan remained unchanged. For two of these, F26A3.4 and chn-1, knock-down resulted in an improvement of healthspan. In follow-up experiments we showed that knockdown of F26A3.4 indeed improves locomotive health and muscle structure at old age.

Knockdown of phosphatases of regenerating liver-1 prolongs the lifespan of Caenorhabditis elegans via activating DAF-16/FOXO

Phosphatases of regenerating liver (PRLs) are dual-specificity protein phosphatases. The aberrant expression of PRLs threatens human health, but their biological functions and pathogenic mechanisms are unclear yet. Herein, the structure and biological functions of PRLs were investigated using the Caenorhabditis elegans (C. elegans). Structurally, this phosphatase in C. elegans, named PRL-1, consisted of a conserved signature sequence WPD loop and a single C(X)₅ R domain. Besides, by Western blot, immunohistochemistry and immunofluorescence staining, PRL-1 was proved to mainly express in larval stages and express in intestinal tissues. Afterward, by feeding-based RNA-interference method, knockdown of prl-1 prolonged the lifespan of C. elegans but also improved their healthspan, such as locomotion, pharyngeal pumping frequency, and defecation interval time. Furthermore, the above effects of prl-1 appeared to be taken without acting on germline signaling, diet restriction pathway, insulin/insulin-like growth factor 1 signaling pathway, and SIR-2.1 but through a DAF-16-dependent pathway. Moreover, knockdown of prl-1 induced the nuclear translocation of DAF-16, and upregulated the expression of daf-16, sod-3, mtl-1, and ctl-2. Finally, suppression of prl-1 also reduced the ROS. In conclusion, suppression of prl-1 enhanced the lifespan and survival quality of C. elegans, which provides a theoretical basis for the pathogenesis of PRLs in related human diseases.

Compound combinations targeting longevity: Challenges and perspectives

Aging is one of the world's greatest concerns, requiring urgent, effective, large-scale interventions to decrease the number of late-life chronic diseases and improve human healthspan. Anti-aging drug therapy is one of the most promising strategies to combat the effects of aging. However, most geroprotective compounds are known to successfully affect only a few aging-related targets. Given this, there is a great biological rationale for the use of combinations of anti-aging interventions. In this review, we characterize the various types of compound combinations used to modulate lifespan, discuss the existing evidence on their role in life extension, and present some key points about current challenges and future prospects for the development of combination drug anti-aging therapy.

Polygonati Rhizoma Polysaccharide Prolongs Lifespan and Healthspan in Caenorhabditis elegans

Polygonati Rhizoma is the dried rhizome of Polygonatum kingianum coll.et hemsl., Polygonatum sibiricum Red. or Polygonatum cyrtonema Hua, and has a long history of medication. Raw Polygonati Rhizoma (RPR) numbs the tongue and stings the throat, while prepared Polygonati Rhizoma (PPR) can remove the numbness of the tongue, and at the same time enhance its functions of invigorating the spleen, moistening the lungs and tonifying the kidneys. There are many active ingredients in Polygonati Rhizoma (PR), among which polysaccharide is one of the most important active ingredients. Therefore, we studied the effect of Polygonati Rhizoma polysaccharide (PRP) on the lifespan of Caenorhabditis elegans (C. elegans) and found that polysaccharide in PPR (PPRP) was more effective than Polysaccharide in RPR (RPRP) in prolonging the lifespan of C. elegans, reducing the accumulation of lipofuscin, and increasing the frequency of pharyngeal pumping and movement. The further mechanism study found that PRP can improve the anti-oxidative stress ability of C. elegans, reduce the accumulation of reactive oxygen species (ROS) in C. elegans, and improve the activity of antioxidant enzymes. The results of quantitative real-time PCR(q-PCR) experiments suggested that PRP may prolong the lifespan of C. elegans by down-regulating daf-2 and activating daf-16 and sod-3, and the transgenic nematode experiments were consistent with its results, so it was hypothesized that the mechanism of age delaying effect of PRP was related to daf-2, daf-16 and sod-3 of the insulin signaling pathway. In short, our research results provide a new idea for the application and development of PRP.

Endogenous DAF-16 spatiotemporal activity quantitatively predicts lifespan extension induced by dietary restriction

In many organisms, dietary restriction (DR) leads to lifespan extension through the activation of cell protection and pro-longevity gene expression programs. In the nematode C. elegans, the DAF-16 transcription factor is a key aging regulator that governs the Insulin/IGF-1 signaling pathway and undergoes translocation from the cytoplasm to the nucleus of cells when animals are exposed to food limitation. However, how large is the influence of DR on DAF-16 activity, and its subsequent impact on lifespan has not been quantitatively determined. In this work, we assess the endogenous activity of DAF-16 under various DR regimes by coupling CRISPR/Cas9-enabled fluorescent tagging of DAF-16 with quantitative image analysis and machine learning. Our results indicate that DR regimes induce strong endogenous DAF-16 activity, although DAF-16 is less responsive in aged individuals. DAF-16 activity is in turn a robust predictor of mean lifespan in C. elegans, accounting for 78% of its variability under DR. Analysis of tissue-specific expression aided by a machine learning tissue classifier reveals that, under DR, the largest contribution to DAF-16 nuclear intensity originates from the intestine and neurons. DR also drives DAF-16 activity in unexpected locations such as the germline and intestinal nucleoli.

Pharyngeal pumping rate does not reflect lifespan extension in C. elegans transgenerational longevity mutants

Epigenetic modifications must be reprogrammed with each new generation. In Caenorhabditis elegans , defects in histone methylation reprogramming allow for the transgenerational acquisition of longevity. For example, mutations in the putative H3K9 demethylase JHDM-1 extend lifespan after six to ten generations. We noticed that long-lived jhdm-1 mutants appear healthier than wild-type animals from the same generation. To quantify health, we compared the common metric of pharyngeal pumping rate at specific adult ages between early-gen populations with normal lifespans and late-gen populations with long lifespans. Longevity did not affect pumping rate, but long-lived mutants stop pumping at a younger age, suggesting a possible conservation of energy to extend lifespan.

PM2.5 induce lifespan reduction, insulin/IGF-1 signaling pathway disruption and lipid metabolism disorder in Caenorhabditis elegans

Introduction

Exposure to fine particulate matter (PM), especially PM2.5, can induce various adverse health effects in populations, including diseases and premature death, but the mechanism of its toxicity is largely unknown.

Methods

Water-soluble components of PM2.5 (WS-PM2.5) were collected in the north of China in winter, and combined in two groups with the final concentrations of 94 μg/mL (CL group, AQI ≤ 100) and 119 μg/mL (CH group, 100 < AQI ≤ 200), respectively. The acute and long-term toxic effects of WS-PM2.5 samples were evaluated in several aspects such as development, lifespan, healthspan (locomotion behavior, heat stress tolerance, lipofucin). DAF mutants and genes were applied to verify the action of IIS pathway in WS-PM2.5 induced-effects. RNA-Sequencing was performed to elucidate the molecular mechanisms, as well as ROS production and Oil red O staining were also served as means of mechanism exploration.

Results

Body length and lifespan were shortened by exposure to WS-PM2.5. Healthspan of nematodes revealed adverse effects evaluated by head thrash, body bend, pharyngeal pump, as well as intestinal lipofuscin accumulation and survival time under heat stress. The abbreviated lifespan of daf-2(e1370) strain and reduced expression level of daf-16 and hsp-16.2 indicated that IIS pathway might be involved in the mechanism. Thirty-five abnormally expressed genes screened out by RNA-Sequencing techniques, were functionally enriched in lipid/lipid metabolism and transport, and may contribute substantially to the regulation of PM2.5 induced adverse effects in nematodes.

Conclusion

WS-PM2.5 exposure induce varying degrees of toxic effects, such as body development, shorten lifespan and healthspan. The IIS pathway and lipid metabolism/transport were disturbed by WS-PM2.5 during WS-PM2.5 exposure, suggesting their regulatory role in lifespan determination.

Ultrasound-driven exercise training ameliorates degeneration of ultrasonic responses in Caenorhabditis elegans

The inevitability of age-related degeneration makes research on degradation mitigation attractive to humans, while exercise is considered an effective means due to its powerful impact on life and health. Caenorhabditis elegans is a model animal with a short life cycle and is widely used in health and aging studies. In this work, ultrasonic stimuli in the form of surface acoustic waves (SAWs) were used to induce behavioral activities in worms. As the worms grew, ultrasound-elicited behavioral responses started to decrease in the early adulthood stage. However, this situation was significantly ameliorated when ultrasonic training sessions at an effective acoustic pressure of 1.1 MPa were performed four times per day for 5 or 7 days, while ultrasonic responses in trained nematodes were stronger than those in untrained ones. These results suggest that long-term ultrasonic training might positively intervene in aging-related degeneration. Besides, it was found that exercise driven by long-term ultrasonic training had insignificant effects on the lifespan of worms. A preliminary exploration of the neural mechanisms underlying the sensation of SAWs was also conducted. The results show that, apart from touch receptor neurons (TRNs), polymodal nociceptors FLP and PVD neurons may also be involved in the perception of ultrasound in C. elegans. The results of this study may inspire related studies on other animals or humans.