Dissecting Aging and Senescence-Current Concepts and Open Lessons

Targeting cellular senescence as a therapeutic vulnerability in gastric cancer

AIMS

Cellular senescence (CS) represents an intracellular defense mechanism responding to stress signals and can be leveraged as a "vulnerability" in cancer treatment. This study aims to construct a CS atlas for gastric cancer (GC) and uncover potential therapeutics for GC patients.

MATERIALS AND METHODS

38 senescence-associated regulators with prognostic significance in GC were obtained from the CellAge database to construct Gastric cancer-specific Senescence Score (GSS). Using eXtreme Sum algorism, GSS-based drug repositioning was conducted to identify drugs that could antagonize GSS in CMap database. In vitro experiments were conducted to test the effect of combination of palbociclib and exisulind in eliminating GC cells.

KEY FINDINGS

Patients with high GSS exhibited CS-related features, such as CS markers upregulation, adverse clinical outcomes and hypomethylation status. scRNA-seq data showed malignant cells with high GSS exhibited enhanced senescence state and more immunosuppressive signals such as PVR-CD96 compared with malignant cells with low GSS. In addition, the GSS-High cancer associated fibroblasts might secrete cytokines and chemokines such as IL-6, CXCL1, CXCL12, and CCL2 to from an immunosuppressive microenvironment, and GSS could serve as an indicator for immunotherapy resistance. Exisulind exhibited the greatest potential to reverse GSS. In vitro experiments demonstrated that exisulind could induce apoptosis and suppress the proliferation of palbociclib-induced senescent GC cells.

SIGNIFICANCE

Overall, GSS offers a framework for better understanding of correlation between senescence and GC, which might provide new insights into the development of novel therapeutics in GC.

Molecular mechanisms of aging and anti-aging strategies

Aging is a complex and multifaceted process involving a variety of interrelated molecular mechanisms and cellular systems. Phenotypically, the biological aging process is accompanied by a gradual loss of cellular function and the systemic deterioration of multiple tissues, resulting in susceptibility to aging-related diseases. Emerging evidence suggests that aging is closely associated with telomere attrition, DNA damage, mitochondrial dysfunction, loss of nicotinamide adenine dinucleotide levels, impaired macro-autophagy, stem cell exhaustion, inflammation, loss of protein balance, deregulated nutrient sensing, altered intercellular communication, and dysbiosis. These age-related changes may be alleviated by intervention strategies, such as calorie restriction, improved sleep quality, enhanced physical activity, and targeted longevity genes. In this review, we summarise the key historical progress in the exploration of important causes of aging and anti-aging strategies in recent decades, which provides a basis for further understanding of the reversibility of aging phenotypes, the application prospect of synthetic biotechnology in anti-aging therapy is also prospected.

Focus on senescence: Clinical significance and practical applications

The older population is increasing worldwide, and life expectancy is continuously rising, predominantly thanks to medical and technological progress. Healthspan refers to the number of years an individual can live in good health. From a gerontological viewpoint, the mission is to extend the life spent in good health, promoting well-being and minimizing the impact of aging-related diseases to slow the aging process. Biologically, aging is a malleable process characterized by an intra- and inter-individual heterogeneous and dynamic balance between accumulating damage and repair mechanisms. Cellular senescence is a key component of this process, with senescent cells accumulating in different tissues and organs, leading to aging and age-related disease susceptibility over time. Removing senescent cells from the body or slowing down the burden rate has been proposed as an efficient way to reduce age-dependent deterioration. In animal models, senotherapeutic molecules can extend life expectancy and lifespan by either senolytic or senomorphic activity. Much research shows that dietary and physical activity-driven lifestyle interventions protect against senescence. This narrative review aims to summarize the current knowledge on targeting senescent cells to reduce the risk of age-related disease in animal models and their translational potential for humans. We focused on studies that have examined the potential role of senotherapeutics in slowing the aging process and modifying age-related disease burdens. The review concludes with a general discussion of the mechanisms underlying this unique trajectory and its implications for future research.

Senescence and aging differentially alter key metabolic pathways in murine brain microglia

Microglia, the resident immune cells of the central nervous system, are critically involved in maintaining brain homeostasis. With age, microglia display morphological and functional alterations that have been associated with cognitive decline and neurodegeneration. Although microglia seem to participate in an increasing number of biological processes which require a high energy demand, little is known about their metabolic regulation under physiological and pathophysiological conditions and during aging/senescence. Here, we determined mRNA expression levels of critical rate limiting enzymes in several key metabolic pathways including glycolysis, pentose phosphate pathway, fatty acid oxidation and synthesis in association with oxidative phosphorylation in microglia, both under aging and senescent conditions. We found strong evidence for different metabolic changes occuring in senescent vs. aged microglia cells. While senescent microglia display a hypermetabolic state as indicated by increased expression of key enzymes involved in glycolysis and pentose phosphate pathway, aging microglia are rather in a state of hypometabolism. Our findings indicate that studies involving aging and senescent microglia require a clear differentiation between these microglial states due to profound metabolic differences observed here. Understanding metabolic changes in senescent and aged microglia may lead to novel strategies to decrease over-activation of these cells due to aging, which is associated to the process of inflamm-aging and neurodegeneration.

Rapid and synchronous chemical induction of replicative-like senescence via a small molecule inhibitor

Cellular senescence is acknowledged as a key contributor to organismal ageing and late-life disease. Though popular, the study of senescence in vitro can be complicated by the prolonged and asynchronous timing of cells committing to it and by its paracrine effects. To address these issues, we repurposed a small molecule inhibitor, inflachromene (ICM), to induce senescence to human primary cells. Within 6 days of treatment with ICM, senescence hallmarks, including the nuclear eviction of HMGB1 and -B2, are uniformly induced across IMR90 cell populations. By generating and comparing various high throughput datasets from ICM-induced and replicative senescence, we uncovered a high similarity of the two states. Notably though, ICM suppresses the pro-inflammatory secretome associated with senescence, thus alleviating most paracrine effects. In summary, ICM rapidly and synchronously induces a senescent-like phenotype thereby allowing the study of its core regulatory program without confounding heterogeneity.

Metformin alleviates junctional epithelium senescence via the AMPK/SIRT1/autophagy pathway in periodontitis induced by hyperglycemia

The junctional epithelium (JE) serves a crucial protective role in the periodontium. High glucose-related aging results in accelerated barrier dysfunction of the gingival epithelium, which may be associated with diabetic periodontitis. Metformin, an oral hypoglycemic therapeutic, has been proposed as a anti-aging agent. This study aimed to clarify the effect of metformin on diabetic periodontitis and explore its mechanism in ameliorating senescence of JE during hyperglycemia. The db/db mice was used as a diabetic model mice and alterations in the periodontium were observed by hematoxylin-eosin staining and immunohistochemistry. An ameloblast-like cell line (ALC) was cultured with high glucose to induce senescence. Cellular senescence and oxidative stress were evaluated by SA-β-gal staining and Intracellular reactive oxygen species (ROS) levels. Senescence biomarkers, P21 and P53, and autophagy markers, LC3-II/LC3-I, were measured by western blotting and quantitative real-time PCR. To construct a stable SIRT1 (Sirtuin 1) overexpression cell line, we transfected ALCs with lentiviral vectors overexpressing the mouse SIRT1 gene. Cellular senescence was increased in the JE of db/db mice and the periodontium was destroyed, which could be alleviated by metformin. Moreover, oxidative stress and cellular senescence in a high glucose environment were reduced by metformin in in-vitro assays. The autophagy inhibitor 3-MA and SIRT1 inhibitor EX-527 could dampen the effects of metformin. Overexpression of SIRT1 resulted in increased autophagy and decreased oxidative stress and cellular senescence. Meanwhile, AMPK (AMP-activated protein kinase) inhibition reversed the anti-senescence effects of metformin. Overall, these results suggest that metformin alleviates periodontal damage in db/db mice and cellular senescence in ALCs under high glucose conditions via the AMPK/SIRT1/autophagy pathway.

Immune profiles of pre-frail people living with HIV-1: a prospective longitudinal study

BACKGROUND

People living with HIV (PLWH) are at risk of frailty, which is predictive for death. As an overactivity of the immune system is thought to fuel frailty, we characterized the immune activation profiles linked to frailty.

METHODS

We quantified twenty-seven activation markers in forty-six virological responders (four females and forty-two males; median age, 74 years; median duration of infection, 24 years; median duration of undetectability, 13 years), whose frailty was determined according to the Fried criteria. T cell and NK cell activation was evaluated by flow cytometry, using a panel of cell surface markers. Soluble markers of inflammation, and monocyte activation and endothelial activation were measured by ELISA. The participants' immune activation was profiled by an unsupervised double hierarchical clustering analysis. We used ANOVA p-values to rank immunomarkers most related to Fried score. A Linear Discriminant Analysis (LDA) was performed to link immune activation markers to frailty.

RESULTS

41% of the participants were pre-frail, including 24% with a Fried score of 1, and 17% with a Fried score of 2. ANOVA identified the 14 markers of T cell, monocyte, NK cell, endothelial activation, and inflammation the most linked to Fried 3 classes. The LDA performed with these 14 markers was capable of discriminating volunteers according to their Fried score. Two out of the 5 immune activation profiles revealed by the hierarchical clustering were linked to and predictive of pre-frailty. These two profiles were characterized by a low percentage of CD4 T cells and a high percentage of CD8 T cells, activated CD4 T cells, CD8 T cells, and NK cells, and inflammation.

CONCLUSIONS

We identified a particular immune activation profile associated with pre-frailty in PLWH. Profiling participants at risk of developing frailty might help to tailor the screening and prevention of medical complications fueled by loss of robustness. Further studies will indicate whether this frailty signature is specific or not of HIV infection, and whether it also precedes frailty in the general population.

Dynamic interactions in the tumor niche: how the cross-talk between CAFs and the tumor microenvironment impacts resistance to therapy

The tumor microenvironment (TME) is a complex ecosystem of cells, signaling molecules, and extracellular matrix components that profoundly influence cancer progression. Among the key players in the TME, cancer-associated fibroblasts (CAFs) have gained increasing attention for their diverse and influential roles. CAFs are activated fibroblasts found abundantly within the TME of various cancer types. CAFs contribute significantly to tumor progression by promoting angiogenesis, remodeling the extracellular matrix, and modulating immune cell infiltration. In order to influence the microenvironment, CAFs engage in cross-talk with immune cells, cancer cells, and other stromal components through paracrine signaling and direct cell-cell interactions. This cross-talk can result in immunosuppression, tumor cell proliferation, and epithelial-mesenchymal transition, contributing to disease progression. Emerging evidence suggests that CAFs play a crucial role in therapy resistance, including resistance to chemotherapy and radiotherapy. CAFs can modulate the tumor response to treatment by secreting factors that promote drug efflux, enhance DNA repair mechanisms, and suppress apoptosis pathways. This paper aims to understand the multifaceted functions of CAFs within the TME, discusses cross-talk between CAFs with other TME cells, and sheds light on the contibution of CAFs to therapy resistance. Targeting CAFs or disrupting their cross-talk with other cells holds promise for overcoming drug resistance and improving the treatment efficacy of various cancer types.

Unraveling Histone Loss in Aging and Senescence

As the global population experiences a notable surge in aging demographics, the need to understand the intricate molecular pathways exacerbated by age-related stresses, including epigenetic dysregulation, becomes a priority. Epigenetic mechanisms play a critical role in driving age-related diseases through altered gene expression, genomic instability, and irregular chromatin remodeling. In this review, we focus on histones, a central component of the epigenome, and consolidate the key findings of histone loss and genome-wide redistribution as fundamental processes contributing to aging and senescence. The review provides insights into novel histone expression profiles, nucleosome occupancy, disruptions in higher-order chromatin architecture, and the emergence of noncanonical histone variants in the aging cellular landscape. Furthermore, we explore the current state of our understanding of the molecular mechanisms of histone deficiency in aging cells. Specific emphasis is placed on highlighting histone degradation pathways in the cell and studies that have explored potential strategies to mitigate histone loss or restore histone levels in aging cells. Finally, in addressing future perspectives, the insights gained from this review hold profound implications for advancing strategies that actively intervene in modulating histone expression profiles in the context of cellular aging and identifying potential therapeutic targets for alleviating a multitude of age-related diseases.

Cutaneous Redox Senescence

Our current understanding of skin cell senescence involves the role of environmental stressors (UV, O3, cigarette smoke, particulate matter, etc.), lifestyle (diet, exercise, etc.) as well as genetic factors (metabolic changes, hormonal, etc.). The common mechanism of action of these stressors is the disturbance of cellular redox balance characterized by increased free radicals and reactive oxygen species (ROS), and when these overload the intrinsic antioxidant defense system, it can lead to an oxidative stress cellular condition. The main redox mechanisms that activate cellular senescence in the skin involve (1) the oxidative damage of telomeres causing their shortening; (2) the oxidation of proteomes and DNA damage; (3) an a in lysosomal mass through the increased activity of resident enzymes such as senescence-associated β-galactosidase (SA-β-gal) as well as other proteins that are products of lysosomal activity; (4) and the increased expression of SASP, in particular pro-inflammatory cytokines transcriptionally regulated by NF-κB. However, the main targets of ROS on the skin are the proteome (oxi-proteome), followed by telomeres, nucleic acids (DNAs), lipids, proteins, and cytoplasmic organelles. As a result, cell cycle arrest pathways, lipid peroxidation, increased lysosomal content and dysfunctional mitochondria, and SASP synthesis occur. Furthermore, oxidative stress in skin cells increases the activity of p16INK4A and p53 as inhibitors of Rb and CDks, which are important for maintaining the cell cycle. p53 also promotes the inactivation of mTOR-mediated autophagic and apoptotic pathways, leading to senescence. However, these markers alone cannot establish the state of cellular senescence, and multiple analyses are encouraged for confirmation. An updated and more comprehensive approach to investigating skin senescence should include further assays of ox-inflammatory molecular pathways that can consolidate the understanding of cutaneous redox senescence.

Age-related bone diseases: Role of inflammaging

Bone aging is characterized by an imbalance in the physiological and pathological processes of osteogenesis, osteoclastogenesis, adipogenesis, and chondrogenesis, resulting in exacerbated bone loss and the development of age-related bone diseases, including osteoporosis, osteoarthritis, rheumatoid arthritis, and periodontitis. Inflammaging, a novel concept in the field of aging research, pertains to the persistent and gradual escalation of pro-inflammatory reactions during the aging process. This phenomenon is distinguished by its low intensity, systemic nature, absence of symptoms, and potential for management. The mechanisms by which inflammaging contribute to age-related chronic diseases, particularly in the context of age-related bone diseases, remain unclear. The precise manner in which systemic inflammation induces bone aging and consequently contributes to the development of age-related bone diseases has yet to be fully elucidated. This article primarily examines the mechanisms underlying inflammaging and its association with age-related bone diseases, to elucidate the potential mechanisms of inflammaging in age-related bone diseases and offer insights for developing preventive and therapeutic strategies for such conditions.

Molecular Network Mechanism Analysis of Urine Stem Cells Against Retinal Aging

To investigate the effect and potential mechanism of human-derived urine stem cells (hUSCs) in inhibiting retinal aging by using experimental and bioinformatics. Retinal pigment epithelial cells cultured in vitro, which were randomly divided into normal group, aging group and supernatant of hUSCs group. Cell counting kit-8 detection, senescence-related β-galactosidase, and Annexin V/PI staining were performed to detect cell viability, senescence, and apoptosis. Subsequently, bioinformatics methods were used to explore the underlying mechanisms, in which, targets both hUSCs and aging retina-related targets were obtained from GeneCards. Then, Gene Ontology, Kyoto Encyclopedia of Genes and Genomes enrichment analysis, and protein-protein interaction network were analysis, and the expressional level of hub gene was validated by q-PCR. Supernatant addition of hUSCs promoted markedly cellular proliferation, improved viability and inhibited senescence and apoptosis in vitro. A total of 1476 hUSCs-related targets (Relevance score > 20), 692 retinal disease-related targets, and 732 targets related to disease of aging were selected from GeneCards database, and 289 common targets of hUSCs against aging retina were confirmed through Venn analysis. Enrichment analysis demonstrated that hUSCs might exert its anti-apoptosis efficacy in multiple biological processes, including oxidative stress, inflammation and apoptosis, and core targets were associated with HIF-1, MAPK and PI3K-Akt signal. hUSCs inhibited retinal senescence by regulating multiply targets and signaling pathways, of these, HIF-1, MAPK, and PI3K may be important candidates.

Microgravity triggers ferroptosis and accelerates senescence in the MG-63 cell model of osteoblastic cells

In space, cells sustain strong modifications of their mechanical environment. Mechanosensitive molecules at the cell membrane regulate mechanotransduction pathways that induce adaptive responses through the regulation of gene expression, post-translational modifications, protein interactions or intracellular trafficking, among others. In the current study, human osteoblastic cells were cultured on the ISS in microgravity and at 1 g in a centrifuge, as onboard controls. RNAseq analyses showed that microgravity inhibits cell proliferation and DNA repair, stimulates inflammatory pathways and induces ferroptosis and senescence, two pathways related to ageing. Morphological hallmarks of senescence, such as reduced nuclear size and changes in chromatin architecture, proliferation marker distribution, tubulin acetylation and lysosomal transport were identified by immunofluorescence microscopy, reinforcing the hypothesis of induction of cell senescence in microgravity during space flight. These processes could be attributed, at least in part, to the regulation of YAP1 and its downstream effectors NUPR1 and CKAP2L.

Zebrafish as an Emerging Model for Sarcopenia: Considerations, Current Insights, and Future Directions

Sarcopenia poses a significant challenge to public health and can severely impact the quality of life of aging populations. Despite extensive efforts to study muscle degeneration using traditional animal models, there is still a lack of effective diagnostic tools, precise biomarkers, and treatments for sarcopenia. Zebrafish models have emerged as powerful tools in biomedical research, providing unique insights into age-related muscle disorders like sarcopenia. The advantages of using zebrafish models include their rapid growth outside of the embryo, optical transparency during early developmental stages, high reproductive potential, ease of husbandry, compact size, and genetic tractability. By deepening our understanding of the molecular processes underlying sarcopenia, we may develop novel diagnostic tools and effective treatments that can improve the lives of aging individuals affected by this condition. This review aims to explore the unique advantages of zebrafish as a model for sarcopenia research, highlight recent breakthroughs, outline potential avenues for future investigations, and emphasize the distinctive contributions that zebrafish models offer. Our research endeavors to contribute significantly to address the urgent need for practical solutions to reduce the impact of sarcopenia on aging populations, ultimately striving to enhance the quality of life for individuals affected by this condition.

Health-related quality of life of Korean older adults according to age, sex, and living arrangements: a cross-sectional study

Introduction

The number and proportion of older adults living alone is a significant issue. While the number of the oldest old people is also expected to increase, their health characteristics are poorly understood. This study aims to evaluate the health-related quality of life (HRQoL) of the oldest old people according to age, sex, and living arrangements.

Methods

This study is based on the Korea Community Health Survey 2021. Among the survey's 229,242 observations, 73,617 observations aged 65 or higher were used for the analysis. The study participants were divided into 5-year age intervals (from 65-69 to 90+), sex, and living arrangements. The outcome variables are the EuroQol 5 Dimensions (EQ-5D) index score and the problem reporting rates of the five dimensions of EQ-5D.

Results

The mean EQ-5D index scores were 0.896 at 65-69 and 0.741 at 90+. The mean EQ-5D index score decreased more rapidly as age increased. Women showed consistently lower mean EQ-5D index scores than men in all age intervals. The proportion of older adults living alone increased from 18.1% at 65-69 to 43.6% at 90+. The odds of reporting problems with anxiety/depression among older men living alone were estimated to be significantly higher than older men living with someone (aOR 1.22 95% CI 1.05-1.43). The odds of reporting problems in self-care and usual activity among older women living alone were estimated to be significantly lower than older women living with someone (aOR 0.88 95% CI 0.70-0.83 and aOR 0.88 95% CI 0.82-0.94).

Conclusion

This study showed that older adults' HRQoL deteriorates as their age increases. Moreover, living alone may lead to different effects on older adults' HRQoL according to sex. More comprehensive studies and collaborative attention are needed to identify and provide customized care for older adults.

Anti-Aging Activity and Modes of Action of Compounds from Natural Food Sources

Aging is a natural and inescapable phenomenon characterized by a progressive deterioration of physiological functions, leading to increased vulnerability to chronic diseases and death. With economic and medical development, the elderly population is gradually increasing, which poses a great burden to society, the economy and the medical field. Thus, healthy aging has now become a common aspiration among people over the world. Accumulating evidence indicates that substances that can mediate the deteriorated physiological processes are highly likely to have the potential to prolong lifespan and improve aging-associated diseases. Foods from natural sources are full of bioactive compounds, such as polysaccharides, polyphenols, carotenoids, sterols, terpenoids and vitamins. These bioactive compounds and their derivatives have been shown to be able to delay aging and/or improve aging-associated diseases, thereby prolonging lifespan, via regulation of various physiological processes. Here, we summarize the current understanding of the anti-aging activities of the compounds, polysaccharides, polyphenols, carotenoids, sterols, terpenoids and vitamins from natural food sources, and their modes of action in delaying aging and improving aging-associated diseases. This will certainly provide a reference for further research on the anti-aging effects of bioactive compounds from natural food sources.

Genomic Biomarkers Can Provide a Deeper Understanding of Recurrent Pressure Injuries

OBJECTIVE

To identify genetic biomarkers predisposing individuals with spinal cord injury (SCI) to recurrent pressure injuries (PIs).

METHODS

Repeated measures of the transcriptome profile of veterans with SCI at three Veterans Spinal Cord Injuries and Disorders Centers. Exclusion criteria included having significant active systemic disease at time of enrollment. Researchers obtained comprehensive profiles of clinical and health factors and demographic information relevant to PI history at enrollment and at each follow-up visit by reviewing patients' medical charts. Whole blood samples were collected at 6- to 12-month intervals for 2 to 4 years. In addition to DNA profiling with whole genome sequencing of the patients, RNA sequencing was performed to assess pathways associated with PI risk.

RESULTS

Whole genome sequencing analysis identified 260 genes that showed increased prevalence of single-nucleotide variations in exonic regions with high (>20) combined annotation-dependent depletion scores between persons with high versus low intramuscular adipose tissue levels when cross-referenced with persons who had recurrent PIs. Gene set enrichment analysis using Hallmark and KEGG (Kyoto Encyclopedia of Genes and Genomes) gene sets of these candidate genes revealed enrichment in genes encoding proteins involved in fatty acid metabolism (P < .01). Further, RNA sequencing revealed upregulated activity in biological senescence pathways and downregulated activity in antimicrobial protection pathways.

CONCLUSIONS

Genomic biomarkers may complement electronic health records to support management of complex interactive health issues such as risk of recurrent PIs in people with SCI. These findings may also be leveraged for homogeneous phenotypic grouping of higher-risk individuals.

Spreading Senescent Cells' Burden and Emerging Therapeutic Targets for Frailty

The spreading of senescent cells' burden holds profound implications for frailty, prompting the exploration of novel therapeutic targets. In this perspective review, we delve into the intricate mechanisms underlying senescent cell spreading, its implications for frailty, and its therapeutic development. We have focused our attention on the emerging age-related biological factors, such as microbiome and virome alterations, elucidating their significant contribution to the loss of control over the accumulation rate of senescent cells, particularly affecting key frailty domains, the musculoskeletal system and cerebral functions. We believe that gaining an understanding of these mechanisms could not only aid in elucidating the involvement of cellular senescence in frailty but also offer diverse therapeutic possibilities, potentially advancing the future development of tailored interventions for these highly diverse patients.

Ageing without senescence: A critical absence in social gerontology?

This paper addresses the absence of the term 'senescence' in recent social science literature on ageing. The significance of this omission is considered in light of the emerging standpoint of gero-science, which argues that the central processes defining ageing are concerned with the rising probability of functional decline, development of degenerative disease and death. From this perspective, the separation of ageing and senescence sustains the myth that there exist forms of ageing that are exempt from senescence. The persistence of this myth underlies ageing studies, the sociology of later life and most social gerontology. While there have been undoubted benefits arising from this bracketing out of senescence, the argument of this paper is that the continuing advances associated with this standpoint are outweighed by the need to seriously engage with the consequences of contemporary societal ageing and the centrality of the processes of senescence in establishing an adequate understanding of ageing, its correlates and contingencies and its personal and social consequences.

Exploring the Communication of the SASP: Dynamic, Interactive, and Adaptive Effects on the Microenvironment

Cellular senescence is a complex cell state that can occur during physiological ageing or after exposure to stress signals, regardless of age. It is a dynamic process that continuously evolves in a context-dependent manner. Senescent cells interact with their microenvironment by producing a heterogenous and plastic secretome referred to as the senescence-associated secretory phenotype (SASP). Hence, understanding the cross-talk between SASP and the microenvironment can be challenging due to the complexity of signal exchanges. In this review, we first aim to update the definition of senescence and its associated biomarkers from its discovery to the present day. We detail the regulatory mechanisms involved in the expression of SASP at multiple levels and develop how SASP can orchestrate microenvironment modifications, by focusing on extracellular matrix modifications, neighboring cells' fate, and intercellular communications. We present hypotheses on how these microenvironmental events may affect dynamic changes in SASP composition in return. Finally, we discuss the various existing approaches to targeting SASP and clarify what is currently known about the biological effects of these modified SASPs on the cellular environment.

AFG, an important maillard reaction product in red ginseng, alleviates D-galactose-induced brain aging in mice via correcting mitochondrial dysfunction induced by ROS accumulation

Red ginseng is a classical processed product from Panax ginseng. C.A Meyer with many bioactive components formed through the Maillard reaction called Maillard reaction products. Maillard reaction refers to complex reversible reactions between amino acids or proteins and glycosides, which are used in food processing and storage, as well as in tobacco development, traditional Chinese medicine processing, and wine brewing. Arginyl-fructosyl-glucose (AFG) is a main non-saponin (ginsenoside) component produced in red ginseng processing, with high antioxidant, anti-apoptotic and neuroprotective efficiencies. However, its effects and mechanisms against oxidation stress in on the brain remain elusive. Therefore, this study aimed at exploring the therapeutic effect exerted by AFG on murine subacute brain aging induced by D-galactose (D-gal) and its potential molecular mechanism in the murine model, finding that AFG (40 and 80 mg/kg) significantly ameliorated D-gal-resulted changes in pathology. Besides, according to the transmission electron microscopy (TEM) and Western blot, AFG corrected the mitochondrial dysfunction resulted from ROS, thereby delaying the mice brain aging caused by D-gal.

Dietary cobalt oxide nanoparticles alleviate aging through activation of mitochondrial UPR in Caenorhabditis elegans

Mitochondrial unfolded protein response (UPRmt), which is a mitochondrial proteostasis pathway, orchestrates an adaptive reprogramming for metabolism homeostasis and organismal longevity. Similar to other defense systems, compromised UPRmt is a feature of several age-related diseases. Here we report that dimercapto succinic acid (DMSA)-modified cobalt oxide nanoparticles (Co3O4 NPs), which have received wide-spread attention in biomedical fields, is a promising UPRmt activator and, more importantly, provides a gate for extending healthy lifespan. Methods: UPRmt activation by Co3O4 NPs was tested in transgenetic Caenorhabditis elegans (C. elegans) specifically expressing UPRmt reporter Phsp-6::GFP, and the underlying mechanism was further validated by mitochondrial morphology, mtDNA/nDNA, metabolism-related genes' expression, mitonuclear protein imbalance, oyxgen assumption and ATP level in C. elegans. Then therapeutic response aganist senescence was monitored by lifespan analysis, lipofusin contents, MDA contents, Fe accumulation, pharyngeal locomotion performance as well as athletic ability (head thrashes and body bends) at different developmental stages of C. elegans. RNAi towards ubl-5 or atfs-1 in UPRmt pathway was applied to clarify the role of UPRmt in Co3O4 NPs -mediated anti-aging effects. Finally, the effect of Co3O4 NPs on mitochondrial homeostasis and D-galactose-induced cell viability decline in mammalian cells were studied. Results: Co3O4 NPs was revealed as a bona fide activator of the UPRmt signaling pathway, through fine-tuning mitochondrial dynamics and inducing a stoichiometric imbalance between OXPHOS subunits encoded by mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) at early life stage of C. elegans. Phenotypically, Co3O4 NPs treatment protect C. elegans from external stresses. More importantly, dietary low level of Co3O4 NPs effectively extend lifespan and alleviate aging-related physiological and functional decline of worms, demonstrating its potential roles in delaying aging. While the protective effect exerted by Co3O4 NPs was compromised in line with atfs-1 or ubl-5 RNAi treatment. Further studies verified the conservation of Co3O4 NPs in activating UPRmt and exerting protective effects in mammalian cells. Conclusions: The results reveal beneficial effects of Co3O4 NPs on mitochondrial metabolic control, thus presenting their potential efficacy in anti-aging care.

Changes in the mammary gland during aging and its links with breast diseases

The functional capacity of organisms declines in the process of aging. In the case of breast tissue, abnormal mammary gland development can lead to dysfunction in milk secretion, a primary function, as well as the onset of various diseases, such as breast cancer. In the process of aging, the terminal duct lobular units (TDLUs) within the breast undergo gradual degeneration, while the proportion of adipose tissue in the breast continues to increase and hormonal levels in the breast change accordingly. Here, we review changes in morphology, internal structure, and cellular composition that occur in the mammary gland during aging. We also explore the emerging mechanisms of breast aging and the relationship between changes during aging and breast-related diseases, as well as potential interventions for delaying mammary gland aging and preventing breast disease.

20(S)-protopanaxatriol inhibited D-galactose-induced brain aging in mice via promoting mitochondrial autophagy flow

Previous reports have confirmed that saponins (ginsenosides) derived from Panax ginseng. C. A. Meyer exerted obvious memory-enhancing and antiaging effects, and the simpler the structure of ginsenosides, the better the biological activity. In this work, we aimed to explore the therapeutic effect and underlying molecular mechanism of 20(S)-protopanaxatriol (PPT), the aglycone of panaxatriol-type ginsenosides, by establishing D-galactose (D-gal)-induced subacute brain aging model in mice. The results showed that PPT treatment (10 and 20 mg/kg) for 4 weeks could significantly restore the D-gal (800 mg/kg for 8 weeks)-induced impaired memory function, choline dysfunction, and redox system imbalance in mice. Meanwhile, PPT also significantly reduced the histopathological changes caused by D-gal exposure. Moreover, PPT could increase TFEB/LAMP2 protein expression to promote mitochondrial autophagic flow. Importantly, the results from molecular docking showed that PPT had good binding ability with LAMP2 and TFEB, suggesting that TFEB/LAMP2 might play an important role in PPT to alleviate D-gal-caused brain aging.

Immunology of Aging: the Birth of Inflammaging

The inflammaging concept was introduced in 2000 by Prof. Franceschi. This was an evolutionary or rather a revolutionary conceptualization of the immune changes in response to a lifelong stress. This conceptualization permitted to consider the lifelong proinflammatory process as an adaptation which could eventually lead to either beneficial or detrimental consequences. This dichotomy is influenced by both the genetics and the environment. Depending on which way prevails in an individual, the outcome may be healthy longevity or pathological aging burdened with aging-related diseases. The concept of inflammaging has also revealed the complex, systemic nature of aging. Thus, this conceptualization opens the way to consider age-related processes in their complexity, meaning that not only the process but also all counter-processes should be considered. It has also opened the way to add new concepts to the original one, leading to better understanding of the nature of inflammaging and of aging itself. Finally, it showed the way towards potential multimodal interventions involving a holistic approach to optimize the aging process towards a healthy longevity.

Chronic kidney disease prevention campaign: relationship between proteinuria and elderly people

OBJECTIVE

To verify the relationship between the presence of proteinuria as a renal injury marker in elderly without history of systemic arterial hypertension and cardiovascular diseases. A cross-sectional study was developed from January 2014 to December 2019, through kidney disease prevention campaigns promoted by the Federal University of Ceará in the city of Fortaleza.

METHODS

The sample consisted of 417 elderlies. A questionnaire was used to characterize individuals and assess previous diseases, and urinalysis reagent strips were used to assess proteinuria.

RESULTS

Statistically significant differences (p < 0.05) and moderate effect sizes were found for blood pressure levels (CI 0.53-0.93), systolic blood pressure, and diastolic blood pressure (CI 0.21-0.61). Significant differences in capillary glycemia were also found between groups (p = 0.033), but with a low effect size (0.02-0.42). The group with comorbidities was 2.94 times more likely to have proteinuria than those without comorbidities (OR 2.94, CI 1.55-4.01; p < 0.05). In the group without cardiovascular disease/high blood pressure, a statistically significant association was found for previous diabetes and proteinuria (p = 0.037), presenting 2.68 times higher risk of proteinuria in those with diabetes mellitus (OR 2.68, CI 1.05-6.85). Significant association was also found between age groups, with the older group having 2.69 times higher risk of developing proteinuria (75 to 90 compared to 60 to 74 years) (CI 1.01-7.16; p = 0.045).

CONCLUSION

Even without systemic arterial hypertension or cardiovascular disease, diabetes and older age can be considered high risk factors for proteinuria.

Immunosenescence, Inflammaging, and Frailty: Role of Myeloid Cells in Age-Related Diseases

The immune system is the central regulator of tissue homeostasis, ensuring tissue regeneration and protection against both pathogens and the neoformation of cancer cells. Its proper functioning requires homeostatic properties, which are maintained by an adequate balance of myeloid and lymphoid responses. Aging progressively undermines this ability and compromises the correct activation of immune responses, as well as the resolution of the inflammatory response. A subclinical syndrome of "homeostatic frailty" appears as a distinctive trait of the elderly, which predisposes to immune debilitation and chronic low-grade inflammation (inflammaging), causing the uncontrolled development of chronic and degenerative diseases. The innate immune compartment, in particular, undergoes to a sequela of age-dependent functional alterations, encompassing steps of myeloid progenitor differentiation and altered responses to endogenous and exogenous threats. Here, we will review the age-dependent evolution of myeloid populations, as well as their impact on frailty and diseases of the elderly.

Oxidative stress, inflammation and hormesis: The role of dietary and lifestyle modifications on aging

Oxidative stress (OS) is primarily caused by the formation of free radicals and reactive oxygen species; it is considered as one of the prominent factors in slowing down and degrading cellular machinery of an individual, and it eventually leads to aging and age-related diseases by its continuous higher state. The relation between molecular damage and OS should be particularized to understand the beginning of destruction at the cellular levels, extending outwards to affect tissues, organs, and ultimately to the organism. Several OS biomarkers, which are established at the biomolecular level, are useful in investigating the disease susceptibility during aging. Slowing down the aging process is a matter of reducing the rate of oxidative damage to the cellular machinery over time. The breakdown of homeostasis, the mild overcompensation, the reestablishment of homeostasis, and the adaptive nature of the process are the essential features of hormesis, which incorporates several factors, including calorie restriction, nutrition and lifestyle modifications that play an important role in reducing the OS. In the current review, along with the concept and theories of aging (with emphasis on free radical theory), various manifestations of OS with special attention on mitochondrial dysfunction and age-related diseases have been discussed. To alleviate the OS, hormetic approaches including caloric restriction, exercise, and nutrition have also been discussed.

Fiber-Type Shifting in Sarcopenia of Old Age: Proteomic Profiling of the Contractile Apparatus of Skeletal Muscles

The progressive loss of skeletal muscle mass and concomitant reduction in contractile strength plays a central role in frailty syndrome. Age-related neuronal impairments are closely associated with sarcopenia in the elderly, which is characterized by severe muscular atrophy that can considerably lessen the overall quality of life at old age. Mass-spectrometry-based proteomic surveys of senescent human skeletal muscles, as well as animal models of sarcopenia, have decisively improved our understanding of the molecular and cellular consequences of muscular atrophy and associated fiber-type shifting during aging. This review outlines the mass spectrometric identification of proteome-wide changes in atrophying skeletal muscles, with a focus on contractile proteins as potential markers of changes in fiber-type distribution patterns. The observed trend of fast-to-slow transitions in individual human skeletal muscles during the aging process is most likely linked to a preferential susceptibility of fast-twitching muscle fibers to muscular atrophy. Studies with senescent animal models, including mostly aged rodent skeletal muscles, have confirmed fiber-type shifting. The proteomic analysis of fast versus slow isoforms of key contractile proteins, such as myosin heavy chains, myosin light chains, actins, troponins and tropomyosins, suggests them as suitable bioanalytical tools of fiber-type transitions during aging.

N-acetylcysteine delayed cadmium-induced chronic kidney injury by activating the sirtuin 1-P53 signaling pathway

With the development of modern industrial civilization, cadmium (Cd), a known nephrotoxic metal, has become a growing public safety issue due to its ability to induce various types of kidney disease. Maladaptive proximal tubule repair is a significant cause of Cd-induced chronic kidney disease (CKD), which is characterized by premature senescence and pro-fibrosis. Previously, we demonstrated that cadmium causes DNA damage and cycle arrest in renal tubular epithelial cells, which may be relevant to premature senescence regulated by sirtuin 1 (SIRT1). In this study, in vivo and in vitro studies were conducted to elucidate the role of SIRT1-mediated premature renal senescence in Cd-induced CKD. As oxidative stress is a significant cause of aging, we evaluated whether N-acetylcysteine (NAC) would inhibit Cd-induced premature aging and dysfunction in rat renal tubular epithelial cells. Cadmium induced premature renal senescence and fibrosis, and NAC inhibited premature renal senescence and fibrosis through the SIRT1-P53 pathway and delayed CKD progression. Overall, the results suggested that the SIRT1-P53 pathway mediates oxidative stress, premature renal senescence, and renal fibrosis during cadmium exposure, which may be a potential therapeutic target for Cd-induced CKD.

Two-CyDye-Based 2D-DIGE Analysis of Aged Human Muscle Biopsy Specimens

The gradual loss of skeletal muscle mass during aging and associated decline in contractile strength can result in reduced fitness, frailty, and loss of independence. In order to better understand the molecular and cellular mechanisms that underlie sarcopenia of old age and the frailty syndrome, as well as identify novel therapeutic targets to treat age-related fiber wasting, it is crucial to develop a comprehensive biomarker signature of muscle aging. Fluorescence two-dimensional gel electrophoresis (2D-DIGE) in combination with sensitive mass spectrometry presents an ideal bioanalytical tool for biomarker discovery in biogerontology. This chapter outlines the application of the 2D-DIGE method for the comparative analysis of human biopsy specimens from middle-aged versus senescent individuals using a two-CyDye-based method.

Beyond its Psychiatric Use: The Benefits of Low-dose Lithium Supplementation

Lithium is most well-known for its mood-stabilizing effects in the treatment of bipolar disorder. Due to its narrow therapeutic window (0.5-1.2 mM serum concentration), there is a stigma associated with lithium treatment and the adverse effects that can occur at therapeutic doses. However, several studies have indicated that doses of lithium under the predetermined therapeutic dose used in bipolar disorder treatment may have beneficial effects not only in the brain but across the body. Currently, literature shows that low-dose lithium (≤0.5 mM) may be beneficial for cardiovascular, musculoskeletal, metabolic, and cognitive function, as well as inflammatory and antioxidant processes of the aging body. There is also some evidence of low-dose lithium exerting a similar and sometimes synergistic effect on these systems. This review summarizes these findings with a focus on low-dose lithium's potential benefits on the aging process and age-related diseases of these systems, such as cardiovascular disease, osteoporosis, sarcopenia, obesity and type 2 diabetes, Alzheimer's disease, and the chronic low-grade inflammatory state known as inflammaging. Although lithium's actions have been widely studied in the brain, the study of the potential benefits of lithium, particularly at a low dose, is still relatively novel. Therefore, this review aims to provide possible mechanistic insights for future research in this field.

Acute effect of blueberry intake on vascular function in older subjects: Study protocol for a randomized, controlled, crossover trial

Aging is associated with an increased risk of developing cardiovascular disease which is often accompanied by a decline in vascular health and function. Current evidence suggests that berries may have a potential role in the modulation of vascular function, but dietary interventions are still needed to confirm findings, especially in older subjects. In the context of the MIND FoodS HUB project, this study aims to investigate the effect of a single serving of blueberry (250 g of blueberry versus a control product) in a group of older subjects (≥ 60y) through a randomized, controlled, cross-over dietary intervention trial. Specifically, the study evaluates the absorption kinetics of bioactives following the blueberries intake and the effects on markers related to oxidative stress, inflammation, and vascular function analyzed at different time points. By considering a drop-out rate estimate of 25%, at least 20 subjects will be recruited in the study. The study will provide evidence to support the potential beneficial effects of blueberry and its bioactive compounds on vascular function in a group of population more susceptible to vascular dysfunction and to the development of cardiovascular diseases. Moreover, the study will contribute the analysis of several metabolic and functional markers that can support the biological plausibility of the results obtained. Finally, the trial will provide data on the absorption and metabolism of blueberry bioactives which will be used to study their association with the different markers under study. Trail registration: The trial is registered at ISRCTN (http://isrctn.com/ISRCTN18262533); May 7, 2021.

Combined Training with Aerobic Exercise Performed Outdoors Can Promote Better Blood Pressure and Affective Responses in Individuals with Cardiovascular Risk Factors

The purpose of the study was to compare the effects of two models of combined training (CT) (aerobic and resistance exercise realized in the same training session), with aerobic training performed in different environments (indoor or outdoor), on blood pressure (BP), heart rate (HR), and affective response in individuals with cardiovascular risk factors. Twenty-six participants were allocated, in a non-randomized design, into CT with aerobic exercise performed indoors (ICT) or outdoors (OCT). Both groups were submitted to three weekly CT sessions, with aerobic exercises performed on ergometers or an athletics track. Before and after nine weeks of training, BP and HR at rest were measured. In the last session of the training, the affective response was collected. The individuals were 65.8 ± 7.8 (ICT) and 67.3 ± 8.2 (OCT) years. Lower values of diastolic BP were observed for the OCT group at post-training (p < 0.001). Moreover, in OCT, a significant inverse correlation was identified between the affective response to training and changes in systolic BP (r = −0.60; p = 0.03) and mean BP (r = −0.62; p = 0.02). In conclusion, CT, with aerobic exercise performed outdoors, seems to be more effective in reducing BP with better affective responses to training.

Restoring Age-Related Cognitive Decline through Environmental Enrichment: A Transcriptomic Approach

Cognitive decline is one of the greatest health threats of old age and the maintenance of optimal brain function across a lifespan remains a big challenge. The hippocampus is considered particularly vulnerable but there is cross-species consensus that its functional integrity benefits from the early and continuous exercise of demanding physical, social and mental activities, also referred to as environmental enrichment (EE). Here, we investigated the extent to which late-onset EE can improve the already-impaired cognitive abilities of lifelong deprived C57BL/6 mice and how it affects gene expression in the hippocampus. To this end, 5- and 24-month-old mice housed in standard cages (5mSC and 24mSC) and 24-month-old mice exposed to EE in the last 2 months of their life (24mEE) were subjected to a Barnes maze task followed by next-generation RNA sequencing of the hippocampal tissue. Our analyses showed that late-onset EE was able to restore deficits in spatial learning and short-term memory in 24-month-old mice. These positive cognitive effects were reflected by specific changes in the hippocampal transcriptome, where late-onset EE affected transcription much more than age (24mSC vs. 24mEE: 1311 DEGs, 24mSC vs. 5mSC: 860 DEGs). Remarkably, a small intersection of 72 age-related DEGs was counter-regulated by late-onset EE. Of these, Bcl3, Cttnbp2, Diexf, Esr2, Grb10, Il4ra, Inhba, Rras2, Rps6ka1 and Socs3 appear to be particularly relevant as key regulators involved in dendritic spine plasticity and in age-relevant molecular signaling cascades mediating senescence, insulin resistance, apoptosis and tissue regeneration. In summary, our observations suggest that the brains of aged mice in standard cage housing preserve a considerable degree of plasticity. Switching them to EE proved to be a promising and non-pharmacological intervention against cognitive decline.

Campanha de prevenção de doença renal crônica: relação entre proteinúria e idosos

Resumo Objetivo: Verificar a relação entre a presença de proteinúria como marcador de lesão renal em idosos sem histórico de hipertensão arterial sistêmica e doenças cardiovasculares. Um estudo transversal foi desenvolvido de Janeiro de 2014 a Dezembro de 2019, por meio de campanhas de prevenção a doenças renais promovidas pela Universidade Federal do Ceará, na cidade de Fortaleza. Métodos: A amostra foi composta por 417 idosos. Um questionário foi usado para caracterizar indivíduos e avaliar doenças prévias, e foram utilizadas tiras reagentes de urinálise para avaliar proteinúria. Resultados: Diferenças estatisticamente significativas (p < 0,05) e tamanhos de efeito moderados foram encontrados para níveis de pressão arterial (IC 0,53-0,93), pressão arterial sistólica e pressão arterial diastólica (IC 0,21-0,61). Também foram encontradas diferenças significativas na glicemia capilar entre grupos (p = 0,033), mas com um tamanho de efeito baixo (0,02–0,42). O grupo com comorbidades apresentou 2,94 vezes mais probabilidade de ter proteinúria do que aqueles sem comorbidades (OR 2,94; IC 1,55-4,01; p < 0,05). No grupo sem doença cardiovascular/hipertensão, foi encontrada uma associação estatisticamente significativa para diabetes anterior e proteinúria (p = 0,037), apresentando risco 2,68 vezes maior de proteinúria naqueles com diabetes mellitus (OR 2,68; IC 1,05-6,85). Também foi encontrada uma associação significativa entre faixas etárias, com o grupo mais velho apresentando risco 2,69 vezes maior de desenvolver proteinúria (75 a 90 em comparação com 60 a 74 anos) (IC 1,01-7,16; p = 0,045). Conclusão: Mesmo sem hipertensão arterial sistêmica ou doença cardiovascular, o diabetes e a idade avançada podem ser considerados fatores de alto risco para proteinúria.

Nutritional senolytics and senomorphics: Implications to immune cells metabolism and aging – from theory to practice

Aging is a natural physiological process, but one that poses major challenges in an increasingly aging society prone to greater health risks such as diabetes, cardiovascular disease, cancer, frailty, increased susceptibility to infection, and reduced response to vaccine regimens. The loss of capacity for cell regeneration and the surrounding tissue microenvironment itself is conditioned by genetic, metabolic, and even environmental factors, such as nutrition. The senescence of the immune system (immunosenescence) represents a challenge, especially when associated with the presence of age-related chronic inflammation (inflammaging) and affecting the metabolic programming of immune cells (immunometabolism). These aspects are linked to poorer health outcomes and therefore present an opportunity for host-directed interventions aimed at both eliminating senescent cells and curbing the underlying inflammation. Senotherapeutics are a class of drugs and natural products that delay, prevent, or reverse the senescence process – senolytics; or inhibit senescence-associated secretory phenotype – senomorphics. Natural senotherapeutics from food sources – nutritional senotherapeutics – may constitute an interesting way to achieve better age-associated outcomes through personalized nutrition. In this sense, the authors present herein a framework of nutritional senotherapeutics as an intervention targeting immunosenescence and immunometabolism, identifying research gaps in this area, and gathering information on concluded and ongoing clinical trials on this subject. Also, we present future directions and ideation for future clinical possibilities in this field.

Theories and Molecular Basis of Vascular Aging: A Review of the Literature from VascAgeNet Group on Pathophysiological Mechanisms of Vascular Aging

Vascular aging, characterized by structural and functional alterations of the vascular wall, is a hallmark of aging and is tightly related to the development of cardiovascular mortality and age-associated vascular pathologies. Over the last years, extensive and ongoing research has highlighted several sophisticated molecular mechanisms that are involved in the pathophysiology of vascular aging. A more thorough understanding of these mechanisms could help to provide a new insight into the complex biology of this non-reversible vascular process and direct future interventions to improve longevity. In this review, we discuss the role of the most important molecular pathways involved in vascular ageing including oxidative stress, vascular inflammation, extracellular matrix metalloproteinases activity, epigenetic regulation, telomere shortening, senescence and autophagy.

Administration of krill oil extends lifespan of fish Nothobranchius guentheri via enhancement of antioxidant system and suppression of NF-κB pathway

Krill oil (KO) extracted from Antarctic krill (Euphausia superba) mainly comprises phospholipids and triglycerides. KO has been shown to prolong the median lifespan of the nematode Caenorhabditis elegans, but to shorten the lifespan of long-lived F1 mice; therefore, it remains controversial over the life-extending property of KO. In this study, we clearly demonstrated that dietary intake of KO extended both the mean and maximum lifespans of aged male Nothobranchius guentheri (p < 0.05), reduced the accumulation of lipofuscin (LF) (p < 0.05) in the gills and senescence-associated β-galactosidase (SA-β-Gal) (p < 0.05) in the caudal fins, and lowered the levels of protein oxidation (p < 0.05), lipid peroxidation (p < 0.01), and reactive oxygen species (ROS) (p < 0.01) in the muscles and livers, indicating that KO possesses rejuvenation and anti-aging activity. We also showed that KO enhanced the activities of antioxidant enzymes catalase (CAT) (p < 0.05), superoxide dismutase (SOD) (p < 0.05), and glutathione peroxidase (GPX) (p < 0.05) in aged male N. guentheri. In addition, KO administration effectively reversed histological lesions including inflammatory cell infiltration and structural collapse in the muscles and livers of aged N. guentheri and suppressed the nuclear factor kappa-B (NF-κB) signaling pathway (p < 0.05), a master regulator of inflammation. Altogether, our study indicates that KO has anti-aging and rejuvenation property. It also suggests that KO exerts its anti-aging and rejuvenation effects via enhancement of the antioxidant system and suppression of the NF-κB signaling pathway.

Robust temporal changes of cellular senescence and proliferation after sciatic nerve injury

Cellular senescence and proliferation are essential for wound healing and tissue remodeling. However, senescence-proliferation cell fate after peripheral nerve injury has not been clearly revealed. Here, post-injury gene expression patterns in rat sciatic nerve stumps (SRP113121) and L4-5 dorsal root ganglia (SRP200823) obtained from the National Center for Biotechnology Information were analyzed to decipher cellular senescence and proliferation-associated genetic changes. We first constructed a rat sciatic nerve crush model. Then, β-galactosidase activities were determined to indicate the existence of cellular senescence in the injured sciatic nerve. Ki67 and EdU immunostaining was performed to indicate cellular proliferation in the injured sciatic nerve. Both cellular senescence and proliferation were less vigorous in the dorsal root ganglia than in sciatic nerve stumps. These results reveal the dynamic changes of injury-induced cellular senescence and proliferation from both genetic and morphological aspects, and thus extend our understanding of the biological processes following peripheral nerve injury. The study was approved by the Animal Ethics Committee of Nantong University, China (approval No. 20190226-001) on February 26, 2019.

Generation and characterization of genome-modified chondrocyte-like cells from the zebra finch cell line immortalized by c-MYC expression

BACKGROUND

Due to their cost effectiveness, ease of use, and unlimited supply, immortalized cell lines are used in place of primary cells for a wide range of research purposes, including gene function studies, CRISPR-based gene editing, drug metabolism tests, and vaccine or therapeutic protein production. Although immortalized cell lines have been established for a range of animal species, there is still a need to develop such cell lines for wild species. The zebra finch, which is used widely as a model species to study the neurobiological basis of human speech disorders, has been employed in several functional studies involving gene knockdown or the introduction of exogenous transgenes in vivo; however, the lack of an immortalized zebra finch cell line has hampered precise genome editing studies.

RESULTS

Here, we established an immortalized cell line by a single genetic event, expression of the c-MYC oncogene, in zebra finch embryonic fibroblasts and examined its potential suitability for gene targeting investigations. Retroviral vector-mediated transduction of c-MYC was used to immortalize zebra finch primary fibroblasts; the transformed cells proliferated stably over several passages, resulting in the expression of chondrocyte-specific genes. The transfection efficiency of the immortalized cells was much higher than that of the primary cells. Targeted knockout of the SOX9 gene, which plays a role in the differentiation of mesenchymal progenitor cells into chondrocytes, was conducted in vitro and both apoptosis and decreased expression levels of chondrogenic marker genes were observed in edited cells.

CONCLUSIONS

The c-MYC induced immortalized chondrocyte-like cell line described here broadens the available options for establishing zebra finch cell lines, paves the way for in-depth biological researches, and provides convenient approaches for biotechnology studies, particularly genomic modification research.

LncRNA LYPLAL1-AS1 rejuvenates human adipose-derived mesenchymal stem cell senescence via transcriptional MIRLET7B inactivation

Background

Mesenchymal stem cell (MSC) senescence is a phenotype of aging. Long noncoding RNAs (lncRNAs) are emerging as potential key regulators of senescence. However, the role of lncRNAs in MSC senescence remains largely unknown.

Results

We performed transcriptome analysis in senescent human adipose-derived MSCs (hADSCs) and identified that the lncRNA LYPLAL1 antisense RNA1 (LYPLAL1-AS1) was significantly downregulated in senescent hADSCs. LYPLAL1-AS1 expression in peripheral blood was lower in middle-aged healthy donors than in young adult donors, and correlated negatively with age. Knockdown of LYPLAL1-AS1 accelerated hADSC senescence, while LYPLAL1-AS1 overexpression attenuated it. Chromatin isolation by RNA purification (ChIRP) sequencing indicated that LYPLAL1-AS1 bound to the MIRLET7B promoter region and suppressed its transcription activity, as demonstrated by dual-luciferase assay. miR-let-7b, the transcript of MIRLET7B, was upregulated during hADSC senescence and was regulated by LYPLAL1-AS1. Furthermore, miR-let-7b mimics promoted hADSC senescence, while the inhibitors repressed it. Finally, LYPLAL1-AS1 overexpression reversed miR-let-7b-induced hADSC senescence.

Conclusions

Our data demonstrate that LYPLAL1-AS1 rejuvenates hADSCs through the transcriptional inhibition of MIRLET7B. Our work provides new insights into the mechanism of MSC senescence and indicates lncRNA LYPLAL1-AS1 and miR-let-7b as potential therapeutic targets in aging.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-022-00782-x.

The Role of Systemic Filtrating Organs in Aging and Their Potential in Rejuvenation Strategies

Advances in aging studies brought about by heterochronic parabiosis suggest that aging might be a reversable process that is affected by changes in the systemic milieu of organs and cells. Given the broadness of such a systemic approach, research to date has mainly questioned the involvement of “shared organs” versus “circulating factors”. However, in the absence of a clear understanding of the chronological development of aging and a unified platform to evaluate the successes claimed by specific rejuvenation methods, current literature on this topic remains scattered. Herein, aging is assessed from an engineering standpoint to isolate possible aging potentiators via a juxtaposition between biological and mechanical systems. Such a simplification provides a general framework for future research in the field and examines the involvement of various factors in aging. Based on this simplified overview, the kidney as a filtration organ is clearly implicated, for the first time, with the aging phenomenon, necessitating a re-evaluation of current rejuvenation studies to untangle the extent of its involvement and its possible role as a potentiator in aging. Based on these findings, the review concludes with potential translatable and long-term therapeutics for aging while offering a critical view of rejuvenation methods proposed to date.

The Mechanism of Bone Remodeling After Bone Aging

Senescence mainly manifests as a series of degenerative changes in the morphological structure and function of the body. Osteoporosis is a systemic bone metabolic disease characterized by destruction of bone microstructure, low bone mineral content, decreased bone strength, and increased brittleness and fracture susceptibility. Osteoblasts, osteoclasts and osteocytes are the main cellular components of bones. However, in the process of aging, due to various self or environmental factors, the body’s function and metabolism are disordered, and osteoporosis will appear in the bones. Here, we summarize the mechanism of aging, and focus on the impact of aging on bone remodeling homeostasis, including the mechanism of ion channels on bone remodeling. Finally, we summarized the current clinical medications, targets and defects for the treatment of osteoporosis.

Senolytics: Eliminating Senescent Cells and Alleviating Intervertebral Disc Degeneration

Intervertebral disc degeneration (IVDD) is the main cause of cervical and lumbar spondylosis. Over the past few years, the relevance between cellular senescence and IVDD has been widely studied, and the senescence-associated secretory phenotype (SASP) produced by senescent cells is found to remodel extracellular matrix (ECM) metabolism and destruct homeostasis. Elimination of senescent cells by senolytics and suppression of SASP production by senomorphics/senostatics are effective strategies to alleviate degenerative diseases including IVDD. Here, we review the involvement of senescence in the process of IVDD; we also discuss the potential of senolytics on eliminating senescent disc cells and alleviating IVDD; finally, we provide a table listing senolytic drugs and small molecules, aiming to propose potential drugs for IVDD therapy in the future.