Hallmarks of senescence and aging

Role of mesenchymal stromal cell secretome on recovery from cellular senescence: an overview

Cellular senescence is intricately linked with numerous changes observed in the aging process, including the depletion of the stem cell pool and the decline in tissue and organ functions. Over the past three decades, efforts to halt and reverse aging have intensified, bringing rejuvenation closer to reality. Current strategies involve treatments using stem cells or their derivatives, such as the secretome. This article aims to highlight key points and evaluate the utilization of secretome derived from mesenchymal stromal cells (MSCs) as an antisenescent approach. Employing a quasi-systematic research approach, the authors conducted a comprehensive analysis based on a search algorithm targeting the in vitro effects of MSC-derived secretome on rescuing cells from a senescent state. Reviewing 39 articles out of 687 hits retrieved from PubMed and Scopus without a time limit, the authors synthesized information and identified common types of MSC-tissue sources utilized (including bone marrow-MSCs, umbilical cord-MSCs, iPSC-derived MSCs, adipose tissue-MSCs, dental pulp-MSCs, amniotic membrane-MSCs, placenta-MSCs, gingival-MSCs, urine-MSCs, and commercially available MSC lineages) from both human and other species (such as mice and rats). The authors also examined the forms of secretome tested (including conditioned media and extracellular vesicles), the cell types treated (MSCs or other cell types), methods/biomarkers of monitoring senescence/rejuvenation, and the mechanisms involved. Ultimately, this review underscores the proof-of-principle of the beneficial effects of MSC-derived secretome in reversing cellular senescence across various cell types. Such insights might aid the scientific community in designing improved in vitro and in vivo assays for future research and clinical validation of this promising cell-free therapy.

Cellular senescence in tumor immune escape: Mechanisms, implications, and therapeutic potential

Cellular senescence, a hallmark of aging, has emerged as a captivating area of research in tumor immunology with profound implications for cancer prevention and treatment. In the tumor microenvironment, senescent cells exhibit a dual role, simultaneously hindering tumor development through collaboration with immune cells and evading immune cell attacks by upregulating immunoinhibitory proteins. However, the intricate immune escape mechanism of cellular senescence in the tumor microenvironment remains a subject of intense investigation. Chronic inflammation is exacerbated by cellular senescence through the upregulation of pro-inflammatory factors such as interleukin-1β, thereby augmenting the risk of tumorigenesis. Additionally, the interplay between autophagy and cellular senescence adds another layer of complexity. Autophagy, known to slow down the aging process by reducing p53/p21 levels, may be downregulated by cellular senescence. To harness the therapeutic potential of cellular senescence, targeting its immunological aspects has gained significant attention. Strategies such as immune checkpoint inhibitors and T-cell senescence inhibition are being explored in the context of cellular senescence immunotherapy. In this comprehensive review, we provide a compelling overview of the regulation of cellular senescence and delve into the influencing factors, including chronic inflammation, autophagy, and circadian rhythms, associated with senescence in the tumor microenvironment. We specifically focus on unraveling the enigmatic dual role of cellular senescence in tumor immune escape. By deciphering the intricate nature of cellular senescence in the tumor microenvironment, this review aims to advance our understanding and pave the way for leveraging senescence as a promising target for tumor immunotherapy applications.

Rosuvastatin restores liver tissue-resident NK cell activation in aged mice by improving mitochondrial function

BACKGROUND AND AIM

Aging has an impact on Natural Killer (NK) cells surveillance against tumors and infections. Our study aims to assess the aging effects on metabolic and mitochondrial markers influencing NK cell activity.

METHODS

C57BL/6 J mice aged 12, 24, 48, and 72 weeks were used. Liver injury serum and histological markers, pro-inflammatory cytokines [IL-1β, IL-2, IL-6] and chemoattractant markers [CCL2, CXCL8] were assessed. Moreover, cholesterol metabolic markers [HMG-CoA synthetase, HMG-CoA reductase, mevalonate kinase], mitochondrial biogenesis [PGC1α] and functional gene markers [TFAM, HSPA9, Seahorse, apoptosis] in liver trNK cells, were assessed by RT-PCR. Senescence [p16, p21], exhaustion [PD-1, TIGIT, LAG3], activation [CD107a, NKp46], and chemokine receptor [CCR2, CXCR1] markers were assessed in trNK cells using flow cytometry. Liver trNK cells of aged mice were treated with Rosuvastatin [10μM] for 12 h.

RESULTS

Data showed a linear increase in liver injury markers, pro-inflammatory and chemotaxis along aging. These results were associated with reductions in liver trNK cell counts and activations with a noticeable decrease in their chemoattractant receptor expressions. TrNK cells of aged mice exhibited elevated markers of senescence and exhaustion with a gradual increase in cholesterol accumulation. Mitochondrial biogenesis and functional gene markers showed a decrease in their expressions in aged mice while ameliorated following rosuvastatin treatment. Results were correlated with a decrease in cholesterol metabolism and restoring their NK cell activity.

CONCLUSION

Our study demonstrates age-related cholesterol accumulation in trNK cells correlated with senescence and functional impairment. Rosuvastatin is suggested to boost, rejuvenate and recover NK cell functionality.

An unbiased cell-culture selection yields DNA aptamers as novel senescent cell-specific reagents

Cellular senescence is an irreversible form of cell-cycle arrest caused by excessive stress or damage. While various biomarkers of cellular senescence have been proposed, there are currently no universal, stand-alone indicators of this condition. The field largely relies on the combined detection of multiple biomarkers to differentiate senescent cells from non-senescent cells. Here we introduce a new approach: unbiased cell culture selections to identify senescent cell-specific folded DNA aptamers from vast libraries of trillions of random 80-mer DNAs. Senescent mouse adult fibroblasts and their non-senescent counterparts were employed for selection. We demonstrate aptamer specificity for senescent mouse cells in culture, identify a form of fibronectin as the molecular target of two selected aptamers, show increased aptamer staining in naturally aged mouse tissues, and demonstrate decreased aptamer staining when p16 expressing cells are removed in a transgenic INK-ATTAC mouse model. This work demonstrates the value of unbiased cell-based selections to identify new senescence-specific DNA reagents.

PCBP2 as an intrinsic agi ng factor regulates the senescence of hBMSCs through the ROS-FGF2 signaling axis

Background

It has been reported that loss of PCBP2 led to increased reactive oxygen species (ROS) production and accelerated cell aging. Knockdown of PCBP2 in HCT116 cells leads to significant downregulation of fibroblast growth factor 2 (FGF2). Here, we tried to elucidate the intrinsic factors and potential mechanisms of bone marrow mesenchymal stromal cells (BMSCs) aging from the interactions among PCBP2, ROS, and FGF2.

Methods

Unlabeled quantitative proteomics were performed to show differentially expressed proteins in the replicative senescent human bone marrow mesenchymal stromal cells (RS-hBMSCs). ROS and FGF2 were detected in the loss-and-gain cell function experiments of PCBP2. The functional recovery experiments were performed to verify whether PCBP2 regulates cell function through ROS/FGF2-dependent ways.

Results

PCBP2 expression was significantly lower in P10-hBMSCs. Knocking down the expression of PCBP2 inhibited the proliferation while accentuated the apoptosis and cell arrest of RS-hBMSCs. PCBP2 silence could increase the production of ROS. On the contrary, overexpression of PCBP2 increased the viability of both P3-hBMSCs and P10-hBMSCs significantly. Meanwhile, overexpression of PCBP2 led to significantly reduced expression of FGF2. Overexpression of FGF2 significantly offset the effect of PCBP2 overexpression in P10-hBMSCs, leading to decreased cell proliferation, increased apoptosis, and reduced G0/G1 phase ratio of the cells.

Conclusions

This study initially elucidates that PCBP2 as an intrinsic aging factor regulates the replicative senescence of hBMSCs through the ROS-FGF2 signaling axis.

Funding

This study was supported by the National Natural Science Foundation of China (82172474).

Metabolic reprogramming in cancer and senescence

The rising trend in global cancer incidence has caused widespread concern, one of the main reasons being the aging of the global population. Statistical data show that cancer incidence and mortality rates show a clear upward trend with age. Although there is a commonality between dysregulated nutrient sensing, which is one of the main features of aging, and metabolic reprogramming of tumor cells, the specific regulatory relationship is not clear. This manuscript intends to comprehensively analyze the relationship between senescence and tumor metabolic reprogramming; as well as reveal the impact of key factors leading to cellular senescence on tumorigenesis. In addition, this review summarizes the current intervention strategies targeting nutrient sensing pathways, as well as the clinical cases of treating tumors targeting the characteristics of senescence with the existing nanodelivery research strategies. Finally, it also suggests sensible dietary habits for those who wish to combat aging. In conclusion, this review attempts to sort out the link between aging and metabolism and provide new ideas for cancer treatment.

Secretome from HMGB1 Box A-over-expressing Adipose-derived Stem Cells Shows Potential for Skin Rejuvenation by Senescence Reversal in PM2.5-induced Senescence Cells via Stem Cell Induction

BACKGROUND/AIM

Exposure to particulate matter 2.5 (PM2.5) can lead to cellular senescence by generating reactive oxygen species (ROS). Box A, a DNA-binding domain found in HMGB1, is known for its ability to counteract aging characteristics. This study explored whether BoxA-induced adipose-derived stem cells secretome (BoxA-SC) can reverse senescence in DP and HWPc cells.

MATERIALS AND METHODS

The stemness characteristics and reversal of senescence by BoxA-SC in PM2.5-induced DP and HWPc cells were assessed at the mRNA level using RT-qPCR and at the protein level using immunofluorescence analysis.

RESULTS

BoxA-SC (1:20) treatment for 48 h induced stemness and reversed PM2.5-induced cell senescence in DP and HWPc cells. BoxA-SC significantly reduced senescence markers, including SA-β-gal staining, and decreased mRNA levels of senescence-associated secretory phenotype factors (IL1α, IL7, CXCL1) in PM2.5-induced senescent cells. DP and HWPc cells exposed to PM2.5 exhibited an increase in p21 and p16 mRNA and protein levels, which was reversed by BoxA-SC. BoxA-SC reduced p21 and p16 in DP senescent cells approximately 3- and 2-fold, respectively, compared to untreated senescent cells.

CONCLUSION

BoxA-SC can potentially reverse cellular senescence, highlighting the therapeutic potential of stem cells in skin rejuvenation and anti-aging treatments.

Update of cellular senescence in kidney fibrosis: from mechanism to potential interventions

Kidney fibrosis is the final common pathway of virtually all chronic kidney disease (CKD). However, despite great progress in recent years, no targeted antifibrotic therapies have been approved. Epidemiologic, clinical, and molecular evidence suggest that aging is a major contributor to the increasing incidence of CKD. Senescent renal tubular cells, fibroblasts, endothelial cells, and podocytes have been detected in the kidneys of patients with CKD and animal models. Nonetheless, although accumulated evidence supports the essential role of cellular senescence in CKD, the mechanisms that promote cell senescence and how senescent cells contribute to CKD remain largely unknown. In this review, we summarize the features of the cellular senescence of the kidney and discuss the possible functions of senescent cells in the pathogenesis of kidney fibrosis. We also address whether pharmacological approaches targeting senescent cells can be used to retard the the progression of kidney fibrosis.

Comparative analysis of various senescence inducers in proximal renal tubular cells

Senescence in renal cells has attracted wide attention as the critical factor promoting renal fibrosis and chronic kidney disease. Establishing a reliable cellular model is essential to study mechanisms underlying renal cell senescence. Herein, we compared various inducers to define the most suitable senescence inducer for HK-2 proximal tubular cells. These inducers included hydrogen peroxide (H2O2), high-temperature (HT), glucose, mannitol and hydroxyurea (HU). To screen for optimal concentration/level, the highest concentration/level of each inducer that did not increase cell death (to avoid severe toxicity) was selected for senescence induction and comparative analysis using the two most appropriate markers for HK-2 cell senescence as recently established. The data revealed that 0.4 mM, 43 °C, 80 mM, 80 mM and 100 μM were the optimal concentrations/levels of H2O2, HT, glucose, mannitol and HU, respectively. Comparative analysis using optimal concentration/level of each marker revealed that 0.4 mM H2O2, HT at 43 °C, 80 mM glucose and 80 mM mannitol were the weak senescence inducers. The most effective inducer for HK-2 senescence was 100 μM HU, which provided the greatest fold-changes of cell area and granularity when compared with other stimuli in a time-dependent manner. Based on these data comparing H2O2, HT, glucose, mannitol and HU at their optimal concentrations/levels, 100 μM HU seems to be most effective for senescence induction in HK-2 cells for in vitro study of proximal renal tubular cells.

Senile Osteoarthritis Regulated by the Gut Microbiota: From Mechanisms to Treatments

Osteoarthritis (OA) is a chronic, progressive degenerative joint disease that affects the entire synovial joint, leading to the progressive degeneration of articular cartilage. It seriously affects the quality of life and global disability of patients. OA is affected by a variety of factors; the most significant risk factor for OA is age. As individuals age, the risk and severity of OA increase due to the exacerbation of cartilage degeneration and wear and tear. In recent years, research has indicated that the gut microbiota may play a significant role in the aging and OA processes. It is anticipated that regulating the gut microbiota may offer novel approaches to the treatment of OA. The objective of this paper is to examine the relationship between the gut microbiota and senile OA, to investigate the potential mechanisms involved. This review also summarizes the therapeutic strategies related to gut flora in OA management, such as prebiotics and probiotics, diet, exercise, traditional Chinese medicine (TCM) modification, and fecal microbiota transplantation (FMT), highlighting the potential clinical value of gut flora and elucidating the current challenges. The foundation for future research directions is established through the summarization of current research progress.

Molecular mechanisms in liver repair and regeneration: from physiology to therapeutics

Liver repair and regeneration are crucial physiological responses to hepatic injury and are orchestrated through intricate cellular and molecular networks. This review systematically delineates advancements in the field, emphasizing the essential roles played by diverse liver cell types. Their coordinated actions, supported by complex crosstalk within the liver microenvironment, are pivotal to enhancing regenerative outcomes. Recent molecular investigations have elucidated key signaling pathways involved in liver injury and regeneration. Viewed through the lens of metabolic reprogramming, these pathways highlight how shifts in glucose, lipid, and amino acid metabolism support the cellular functions essential for liver repair and regeneration. An analysis of regenerative variability across pathological states reveals how disease conditions influence these dynamics, guiding the development of novel therapeutic strategies and advanced techniques to enhance liver repair and regeneration. Bridging laboratory findings with practical applications, recent clinical trials highlight the potential of optimizing liver regeneration strategies. These trials offer valuable insights into the effectiveness of novel therapies and underscore significant progress in translational research. In conclusion, this review intricately links molecular insights to therapeutic frontiers, systematically charting the trajectory from fundamental physiological mechanisms to innovative clinical applications in liver repair and regeneration.

Avid lysosomal acidification in fibroblasts of the Mediterranean mouse Mus spretus

Failures of the lysosome-autophagy system are a hallmark of aging and many disease states. As a consequence, interventions that enhance lysosome function are of keen interest in the context of drug development. Throughout the biomedical literature, evolutionary biologists have discovered that challenges faced by humans in clinical settings have been resolved by non-model organisms adapting to wild environments. Here, we used a primary cell culture approach to survey lysosomal characteristics in selected species of the genus Mus. We found that cells from M. musculus, mice adapted to human environments, had weak lysosomal acidification and high expression and activity of the lysosomal enzyme β-galactosidase, a classic marker of cellular senescence. Cells of wild relatives, especially the Mediterranean mouse M. spretus, had more robustly performing lysosomes and dampened β-galactosidase levels. We propose that classic laboratory models of lysosome function and senescence may reflect characters that diverge from the phenotypes of wild mice. The M. spretus phenotype may ultimately provide a blueprint for interventions that ameliorate lysosome breakdown in stress and disease.

The Role and Molecular Pathways of SIRT6 in Senescence and Age-related Diseases

SIRT6 is a NAD+-dependent histone deacetylase with crucial roles in controlling DNA damage repair, telomere homeostasis, oxidative stress, autophagy, and other cellular processes, and it has long been recognized as a longevity-associated protein. This review details its anti-aging-related mechanisms. First, SIRT6 facilitates DNA repair pathways and maintains genome stability by deacetylating histone H3 at K56, K9, and K18 residues, in addition to participating in DNA damage repair through mono-ADP-ribosylation and other mechanisms. Second, SIRT6 preserves telomere integrity and mitigates cellular senescence by reducing oxidative stress-induced damage through the regulation of reactive oxygen species (ROS), inhibition of inflammation, and other pathways. Furthermore, SIRT6 promotes autophagy, slowing cellular senescence via the modulation of various signaling pathways, including AMPK, IGF-Akt-mTOR, H133Y, IL-1β, and mitochondrial autophagy-related proteins. Finally, SIRT6 regulates multiple signaling pathways, such asNF-κB, FOXO, and AMPK, to counteract the aging process. This review particularly delves into the interplay between SIRT6 and various diseases, including tumors, cardiovascular diseases (e.g., atherosclerosis, heart failure), metabolic diseases (e.g., type 2 diabetes, dyslipidemia, gluconeogenesis, osteoporosis), and neurodegenerative diseases (e.g., Alzheimer's disease). Moreover, recent advancements in SIRT6-regulated compounds (e.g., C3G, BZBS, Fisetin, FNDC5, Lycorine hydrochloride, and Ergothioneine) are discussed as potential therapeutic agents for these mediated diseases.

The senotherapeutic potential of phytochemicals for age-related intestinal disease

During the last few decades, life expectancy has increased worldwide along with the prevalence of several age-related diseases. Among aging pathways, cellular senescence and chronic inflammation (or "inflammaging") appear to be connected to gut homeostasis and dysbiosis of the microbiome. Cellular senescence is a state of essentially irreversible cell cycle arrest that occurs in response to stress. Although senescent cells (SC) remain metabolically active, they do not proliferate and can secrete inflammatory and other factors comprising the senescence-associated secretory phenotype (SASP). Accumulation of SCs has been linked to onset of several age-related diseases, in the brain, bones, the gastrointestinal tract, and other organs and tissues. The gut microbiome undergoes substantial changes with aging and is tightly interconnected with either successful (healthy) aging or disease. Senotherapeutic drugs are compounds that can clear senescent cells or modulate the release of SASP factors and hence attenuate the impact of the senescence-associated pro-inflammatory state. Phytochemicals, phenolic compounds and terpenes, which have antioxidant and anti-inflammatory activities, could also be senotherapeutic given their ability to act upon senescence-linked cellular pathways. The aim of this review is to dissect links among the gut microbiome, cellular senescence, inflammaging, and disease, as well as to explore phytochemicals as potential senotherapeutics, focusing on their interactions with gut microbiota. Coordinated targeting of these inter-related processes might unveil new strategies for promoting healthy aging.

Cordyceps cicadae Extracts Exert Antiaging Effects by Activating the AMPK/SIRT1 Pathway in d-Galactose-Induced Aging Rats

Cordyceps cicadae, a valuable traditional edible and medicinal resource, is recognized for its potential in slowing aging but has not been effectively exploited. This study aimed to explore antiaging activity and mechanisms of C. cicadae extracts (CCe). We used liquid chromatography-mass spectrometry to identify 23 CCe compounds and focused on quantifying six nucleoside components as quality markers. We also assessed the antiaging influences in d-galactose (d-gal)-induced aging rats. CCe improved learning memory deficits, enhanced organ indices, and mitigated oxidative brain damage caused by d-gal. CCe elevated superoxide dismutase and glutathione peroxidase activities, while downregulating malondialdehyde. Molecular analyses indicated the involvement of adenosine 5'-monophosphate-activated protein kinase/sirtuin 1 (AMPK/SIRT1) pathway in the antiaging mechanism of CCe. This study demonstrates the potential of CCe in mitigating d-gal-induced damage in aging rats, with the AMPK/SIRT1 pathway emerging as a regulatory axis. These findings contribute to the theoretical foundation for developing antiaging pharmaceuticals and functional foods using CCe, offering promising applications in aging-related contexts in succinct manner.

Icariin maintaining TMEM119-positive microglial population improves hippocampus-associated memory in senescent mice in relation to R-3-hydroxybutyric acid metabolism

ETHNOPHARMACOLOGICAL RELEVANCE

Epimedium Tourn. ex L. is a traditional Chinese medicine used for thousands of years in China to treat forgetfulness. Icariin is a principal component of the genus Epimedium.

AIM OF THE STUDY

The metabolic mechanism of icariin treating forgetfulness is explored.

MATERIALS AND METHODS

A D-galactose-induced senescent mouse model was employed. The cognitive performance of mice was assessed in the fear conditioning test. Hippocampal pathology was assessed in the immunohistochemistry assay. Plasma metabolome was analyzed using GC-MS method, and the differential metabolites were further identified by UPLC-MS/MS or GC-MS method. The liver function, including ALT and AST, was assessed by enzyme reaction. Icariin was administered intraperitoneally at 50 and 100 mg/kg. Mice were administered five consecutive days per week for 8 weeks.

RESULTS

Icariin treatment improved hippocampus-related fear memory but not amygdala-related memory, whereas Pexidartinib (PLX3397), a microglial scavenger, did not. Icariin treatment maintained the TMEM119-positive microglial population and decreased the accumulation of the senescent biomarker p16 in the dorsal hippocampus in senescent mouse brains, whereas PLX3397 did not. Notably, p16 in the CA2 subregion significantly decreased in icariin-treated mice than the other hippocampal subregions. The senescent mice exhibited the circulating metabolic characteristics of mild ketoacidosis, active tricarboxylic acid (TCA) cycle, lactic acidosis, hyperglycemia, active detoxification, active cis-oleic acid metabolism, and inhibitory GABA shut. R-3-Hydroxybutyric acid primarily produced in the liver was selectively and robustly decreased by icariin treatment, which was not observed with PLX3397 treatment. The TCA cycle was rescued in senescent mice by icariin treatment. Icariin also protected liver function (plasma ALT) in D-gal-induced senescent mice.

CONCLUSIONS

Icariin may protect mouse hippocampal cognition from D-gal-induced senescence by protecting microglial homeostasis, and facilitating the utilization of R-3-hydroxybutyric acid is one of the underpins.

Involvement of TGF-β, mTOR, and inflammatory mediators in aging alterations during myxomatous mitral valve disease in a canine model

Inflammaging, a state of chronic low-grade inflammation associated with aging, has been linked to the development and progression of various disorders. Cellular senescence, a state of irreversible growth arrest, is another characteristic of aging that contributes to the pathogenesis of cardiovascular pathology. Senescent cells accumulate in tissues over time and secrete many inflammatory mediators, further exacerbating the inflammatory environment. This senescence-associated secretory phenotype can promote tissue dysfunction and remodeling, ultimately leading to the development of age-related cardiovascular pathologies, such as mitral valve myxomatous degeneration. The species-specific form of canine myxomatous mitral valve disease (MMVD) provides a unique opportunity to investigate the early causes of induction of ECM remodeling in mitral valve leaflets in the human form of MMVD. Studies have shown that in both humans and dogs, the microenvironment of the altered leaflets is inflammatory. More recently, the focus has been on the mechanisms leading to the transformation of resting VICs (qVICs) to myofibroblast-like VICs (aVICs). Cells affected by stress fall into a state of cell cycle arrest and become senescent cells. aVICs, under the influence of TGF-β signaling pathways and the mTOR complex, enhance ECM alteration and accumulation of systemic inflammation. This review aims to create a fresh new view of the complex interaction between aging, inflammation, immunosenescence, and MMVD in a canine model, as the domestic dog is a promising model of human aging and age-related diseases.

Cellular senescence in the tumor with a bone niche microenvironment: friend or foe?

Cellular senescence is understood to be a biological process that is defined as irreversible growth arrest and was originally recognized as a tumor-suppressive mechanism that prevents further propagation of damaged cells. More recently, cellular senescence has been shown to have a dual role in prevention and tumor promotion. Senescent cells carry a senescence-associated secretory phenotype (SASP), which is altered by secretory factors including pro-inflammatory cytokines, chemokines, and other proteases, leading to the alteration of the tissue microenvironment. Though senescence would eventually halt the growth of cancerous potential cells, SASP contributes to the tumor environment by promoting inflammation, matrix remodeling, and tumor cell invasion. The paradox of tumor prevention/promotion is particularly relevant to the bone niche tumor microenvironment, where longer-lasting, chronic inflammation promotes tumor formation. Insights into a mechanistic understanding of cellular senescence and SASP provide the basis for targeted therapies, such as senolytics, which aim to eliminate senescent cells, or SASP inhibitors, which would eliminate the tumor-promoting effects of senescence. These therapeutic interventions offer significant clinical implications for treating cancer and healthy aging.

Comparative evaluation of cellular senescence in naturally aged and stress-induced murine macrophages for identifying optimum senescent macrophage study systems

BACKGROUND

The role and relevance of macrophages both as causes and therapeutics of cellular senescence is rapidly emerging. However, current knowledge regarding the extent and depth of senescence in macrophages in vivo is limited and controversial. Further, acute models of stress-induced senescence in transformed/cancerous macrophage cell lines are being used although their efficacy and relevance are not characterized.

METHODS AND RESULTS

The present study sought to address these aspects by first comparing prevalent senescence in naturally aged murine peritoneal macrophages, and then assessing the effects of two different stressors (LPS and H2O2) in inducing premature senescence in young peritoneal macrophages. Next, RAW264.7 cell line was exposed to respective stressors and their efficiency in recapitulating the effects of natural senescence markers was characterized. We observed strong upregulation of primary markers of senescence such as SA-β-gal activity, p53, p21, p16Inka4a, Rb, ATM, and Lamin B1in naturally aged mice along with increased SASP proteins (IL-6/TNF-α/MCP-1) and redox stress (ROS and NO). Aged macrophages also demonstrated severely reduced phagocytosis. Exposure to both LPS and H2O2 in young macrophages invoked the expression of all primary markers of senescence although SASP protein expression was exaggerated in LPS stimulation. Similarly, ROS and NO expression increased while phagocytosis decreased. Stimulation of RAW264.7 cells generally revealed a similar trend although the depth of all measured parameters was ostensibly stronger in young peritoneal macrophages. Among the two stressors, LPS stimulation appeared to be relatively more potent.

CONCLUSION

Overall, this study emphasizes that LPS exposure to young peritoneal macrophages more strongly recapitulates in vivo cellular senescence in macrophages.

Associations between social behaviour and proinflammatory immune activation are modulated by age in a free-ranging primate population

The effect of the social environment on the proinflammatory immune response may mediate the relationship between social environment and fitness but remains understudied outside captive animals and human populations. Age can also influence both immune function and social behaviour, and hence may modulate their relationships. This study investigates the role of social interactions in driving the concentrations of two urinary markers of proinflammatory immune activation, neopterin and soluble urokinase plasminogen activator receptor (suPAR), in a free-ranging population of rhesus macaques, Macaca mulatta. We collected 854 urine samples from 172 adult monkeys and quantified how urinary suPAR and neopterin concentrations were related to affiliative behaviour and agonistic behaviour received over 60 days. In females, but not in males, higher rates of affiliative interactions were associated with lower neopterin concentrations, while conversely, experiencing more agonistic interactions was associated with higher neopterin concentrations. The association between affiliation and neopterin concentration was modulated by age, with older females experiencing a stronger negative association between affiliative behaviour and neopterin concentration. There were no associations between suPAR concentration and social environment for either sex. This study demonstrates that proinflammatory immune activity is a potential mechanism mediating the association between social environment and fitness under naturalistic conditions and that age can be an important modulator of the effect of social environment on the immune system.

Critical review of aging clocks and factors that may influence the pace of aging

Background and objectives

Aging clocks are computational models designed to measure biological age and aging rate based on age-related markers including epigenetic, proteomic, and immunomic changes, gut and skin microbiota, among others. In this narrative review, we aim to discuss the currently available aging clocks, ranging from epigenetic aging clocks to visual skin aging clocks.

Methods

We performed a literature search on PubMed/MEDLINE databases with keywords including: "aging clock," "aging," "biological age," "chronological age," "epigenetic," "proteomic," "microbiome," "telomere," "metabolic," "inflammation," "glycomic," "lifestyle," "nutrition," "diet," "exercise," "psychosocial," and "technology."

Results

Notably, several CpG regions, plasma proteins, inflammatory and immune biomarkers, microbiome shifts, neuroimaging changes, and visual skin aging parameters demonstrated roles in aging and aging clock predictions. Further analysis on the most predictive CpGs and biomarkers is warranted. Limitations of aging clocks include technical noise which may be corrected with additional statistical techniques, and the diversity and applicability of samples utilized.

Conclusion

Aging clocks have significant therapeutic potential to better understand aging and the influence of chronic inflammation and diseases in an expanding older population.

Senolytic Vaccines from the Central and Peripheral Tolerance Perspective

Preventive medicine has proven its long-term effectiveness and economic feasibility. Over the last century, vaccination has saved more lives than any other medical technology. At present, preventative measures against most infectious diseases are successfully used worldwide; in addition, vaccination platforms against oncological and even autoimmune diseases are being actively developed. At the same time, the development of medicine led to an increase in both life expectancy and the proportion of age-associated diseases, which pose a heavy socio-economic burden. In this context, the development of vaccine-based approaches for the prevention or treatment of age-related diseases opens up broad prospects for extending the period of active longevity and has high economic potential. It is well known that the development of age-related diseases is associated with the accumulation of senescent cells in various organs and tissues. It has been demonstrated that the elimination of such cells leads to the restoration of functions, rejuvenation, and extension of the lives of experimental animals. However, the development of vaccines against senescent cells is complicated by their antigenic heterogeneity and the lack of a unique marker. In addition, senescent cells are the body's own cells, which may be the reason for their low immunogenicity. This mini-review discusses the mechanisms of central and peripheral tolerance that may influence the formation of an anti-senescent immune response and be responsible for the accumulation of senescent cells with age.

Apolipoprotein E4 and Alzheimer's disease causality under adverse environments and potential intervention by senolytic nutrients

Apolipoprotein E (apoE) has a pivotal role in Alzheimer's Disease (AD) pathophysiology. APOE4 has been recognized as a risk factor for developing late-onset AD. Recently, APOE4 homozygosity was regarded as a new familial genetic trait of AD. In this opinion paper, we summarized the potential pleiotropic antagonism role of APOE4 in children living under early life adversity and afflicted with enteric infection/malnutrition-related pathogenic exposome. APOE4 was found to be neuroprotective early in life despite its increasing risk for AD with aging. We call for awareness of the potential burden this can bring to the public health system when APOE4 carriers, raised under adverse environmental conditions in early life and then aging with unhealthy lifestyles in later life may be at special risk for cognitive impairments and acquired AD. We postulate the importance of anti-senescence therapies to protect these individuals and remediate aging-related chronic illnesses.

Neurotoxicity of the antineoplastic drugs: "Doxorubicin" as an example

There is an increased prevalence of cancer, and chemotherapy is widely and routinely utilized to manage the majority of cancers; however, administration of chemotherapeutic drugs has faced limitations concerning the "off-target" cytotoxicity. Chemobrain and impairment of neurocognitive functions have been observed in a significant fraction of cancer patients or survivors and reduce their life quality; this could be ascribed to the ability of chemotherapeutic drugs to alter the structure and function of the brain. Doxorubicin (DOX), an FDA-approved chemotherapeutic drug with therapeutic effectiveness, is commonly used to treat several carcinomas clinically. DOX-triggered neurotoxicity is the most serious adverse reaction after DOX-induced cardiotoxicity which greatly limits its clinical application. DOX-induced neurotoxicity is a net of multiple mechanisms that have been verified in pre-clinical and clinical studies, such as oxidative stress, neuroinflammation, mitochondrial disruption, apoptosis, autophagy, disruption of neurotransmitters, and impairment of neurogenesis. There is a massive need for developing novel therapeutics for both cancer and DOX-associated neurotoxicity; therefore investigating the implicated mechanisms of DOX-induced chemobrain will reveal multi-targets for novel curative strategies. Recently, various neuroprotective mechanisms were employed to mitigate DOX-mediated neurotoxicity. For this purpose, therapeutic interventions using pharmacological compounds were developed to protect healthy "off-target" tissues from DOX-induced toxicity. In addition, nanoplatforms were used to enable target delivery of DOX; to prevent its deposition in non-cancerous tissues. The aim of the current review is to provide some reference value for the future management of DOX-induced neurotoxicity and to summarize the underlying mechanisms of DOX-mediated neurotoxicity and the potential therapeutic interventions.

Older mothers produce smaller eggs without compromising offspring quality: a study of a thelytokous mite predator (Acari: Phytoseiidae)

Negative relationships between the parental age and offspring life history traits have been widely observed across diverse animal taxa. However, there is a lack of studies examining the influence of parental age on offspring performance using mites, particularly phytoseiid predators as subjects. This study explored the influence of maternal age on offspring life history traits in Amblyseius herbicolus (Chant) (Acari: Mesostigmata), a phytoseiid predatory mite reproducing through thelytokous parthenogenesis. We hypothesised that increased maternal age negatively impacts offspring traits, including developmental duration, body size, fecundity and lifespan. Amblyseius herbicolus was reared under controlled laboratory conditions, and the life history traits of offspring from mothers of varying ages were analysed using linear mixed-effect models. Our results showed that the increase in maternal age significantly reduced individual egg volume, but did not significantly affect offspring developmental duration, body size, fecundity or lifespan. These findings indicate that while older A. herbicolus females produced smaller eggs, the subsequent performance (i.e. body size, fecundity and lifespan) of offspring remained largely unaffected, suggesting possible compensatory mechanisms in the offspring or alternative maternal provisioning strategies. The results of this study offer useful insights into the reproductive strategies of phytoseiid predators and asexually reproducing species, enhancing our understanding of how maternal age affects offspring fitness. Further studies can examine how offspring of A. herbicolus from mothers of different ages perform under adverse environmental conditions.

Microglia States are Susceptible to Senescence and Cholesterol Dysregulation in Alzheimer's Disease

Cellular senescence is a major contributor to aging-related degenerative diseases, including Alzheimer's disease (AD) but much less is known on the key cell types and pathways driving mechanisms of senescence in the brain. We hypothesized that dysregulated cholesterol metabolism is central to cellular senescence in AD. We analyzed whole transcriptomic data and utilized single-cell RNA seq integration techniques to unveil the convoluted cell-type-specific and sub-cell-type-state-specific senescence pathologies in AD using both ROSMAP and Sea-AD datasets. We identified that microglia are central components to AD associated senescence phenotypes in ROSMAP snRNA-seq data (982,384 nuclei from postmortem prefrontal cortex of 239 AD and 188 non-AD) among non-neuron cell types. We identified that homeostatic, inflammatory, phagocytic, lipid processing and neuronal surveillance microglia states were associated with AD associated senescence in ROSMAP (152,459 microglia nuclei from six regions of brain tissue of 138 early AD, 79 late AD and 226 control subject) and in Sea-AD (82,486 microglia nuclei of 42 dementia, 42 no dementia and 5 reference subjects) via integrative analysis, which preserves the meaningful biological information of microglia cell states across the datasets. We assessed top senescence associated bioprocesses including mitochondrial, apoptosis, oxidative stress, ER stress, endosomes, and lysosomes systems. Specifically, we found that senescent microglia have altered cholesterol related bioprocesses and dysregulated cholesterol. We discovered three gene co-expression modules, which represent the specific cholesterol related senescence transcriptomic signatures in postmortem brains. To validate these findings, the activation of specific cholesterol associated senescence transcriptomic signatures was assessed using integrative analysis of snRNA-seq data from iMGs (microglia induced from iPSCs) exposed to myelin, Abeta, and synaptosomes (56,454 microglia across two replicates of untreated and four treated groups). In vivo cholesterol associated senescence transcriptomic signatures were preserved and altered after treatment with AD pathological substrates in iMGs. This study provides the first evidence that dysregulation of cholesterol metabolism in microglia is a major driver of senescence pathologies in AD. Targeting cholesterol pathways in senescent microglia is an attractive strategy to slow down AD progression.

p16Ink4a-induced senescence in cultured mast cells as a model for ageing reveals significant morphological and functional changes

BACKGROUND

Mast cells (MCs) are tissue resident cells of the immune system, mainly known for their role in allergy. However, mounting evidence indicates their involvement in the pathology of age-related diseases, such as Alzheimer's disease, Parkinson's disease, and cancer. MC numbers increase in aged tissues, but how ageing affects MCs is poorly understood.

RESULTS

We show that MC ageing is associated with the increased expression of the cell cycle inhibitor p16 Ink4a, a marker and inducer of cellular senescence. Relying on this observation and the tight association of ageing with senescence, we developed a model of inducible senescence based on doxycycline-induced expression of p16Ink4a in cultured bone marrow derived MCs (BMMCs). Using this model, we show that senescent MCs upregulate IL-1β, TNF-α and VEGF-A. We also demonstrate that senescence causes marked morphological changes that impact MC function. Senescent MCs are larger, contain a larger number of secretory granules (SGs) and have less membrane protrusions. Particularly striking are the changes in their SGs, reflected in a significant reduction in the number of electron dense SGs with a concomitant increase in lucent SGs containing intraluminal vesicles. The changes in SG morphology are accompanied by changes in MC degranulation, including a significant increase in receptor-triggered release of CD63-positive extracellular vesicles (EVs) and the exteriorisation of proteoglycans, as opposed to a gradual inhibition of the release of β-hexosaminidase.

CONCLUSIONS

The inducible expression of p16Ink4a imposes MC senescence, providing a model for tracking the autonomous changes that occur in MCs during ageing. These changes include both morphological and functional alterations. In particular, the increased release of small EVs by senescent MCs suggests an enhanced ability to modulate neighbouring cells.

Immune Alterations with Aging: Mechanisms and Intervention Strategies

Aging is the result of a complex interplay of physical, environmental, and social factors, leading to an increased prevalence of chronic age-related diseases that burden health and social care systems. As the global population ages, it is crucial to understand the aged immune system, which undergoes declines in both innate and adaptive immunity. This immune decline exacerbates the aging process, creating a feedback loop that accelerates the onset of diseases, including infectious diseases, autoimmune disorders, and cancer. Intervention strategies, including dietary adjustments, pharmacological treatments, and immunomodulatory therapies, represent promising approaches to counteract immunosenescence. These interventions aim to enhance immune function by improving the activity and interactions of aging-affected immune cells, or by modulating inflammatory responses through the suppression of excessive cytokine secretion and inflammatory pathway activation. Such strategies have the potential to restore immune homeostasis and mitigate age-related inflammation, thus reducing the risk of chronic diseases linked to aging. In summary, this review provides insights into the effects and underlying mechanisms of immunosenescence, as well as its potential interventions, with particular emphasis on the relationship between aging, immunity, and nutritional factors.

Anti-oxidative activity of probiotics; focused on cardiovascular disease, cancer, aging, and obesity

By disturbing the prooxidant-antioxidant balance in the cell, a condition called oxidative stress is created, causing severe damage to the nucleic acid, protein, and lipid of the host cell, and as a result, endangers the viability of the host cell. A relationship between oxidative stress and several different diseases such as cardiovascular diseases, cancer, and obesity has been reported. Therefore, maintaining this prooxidant-antioxidant balance is vital for the cell. Probiotics as one of the potent antioxidants have recently received attention. Many health-promoting and beneficial effects of probiotics are known, and it has been found that the consumption of certain strains of probiotics alone or in combination with food exerts antioxidant efficacy and reduces oxidative damage. Studies have reported that certain probiotic strains implement their antioxidant effects by producing metabolites and antioxidant enzymes, increasing the antioxidant capacity, and reducing host oxidant metabolites. Therefore, we aimed to review and summarize the latest anti-oxidative activity of probiotics and its efficacy in aging, cardiovascular diseases, cancer, and obesity.

Topical Platelet Exosomes Reduce Senescence Signaling in Human Skin: An Exploratory Prospective Trial

BACKGROUND

Cellular senescence, an irreversible cell cycle arrest with secretory phenotype, is a hallmark of skin aging. Regenerative exosome-based approaches, such as topical human platelet extract (HPE), are emerging to target age-related skin dysfunction.

OBJECTIVE

To evaluate the cellular and molecular effects of topical HPE for skin rejuvenation after 12 weeks of twice daily use.

METHODS

Skin biopsies were obtained for histological evaluation of senescence markers, p16INK4a and p21CIP1/WAF1. Telomere-associated foci, coassociation of telomeres, and DNA damage marker, γH2AX, were assessed. RNA sequencing evaluated senescence associated secretory phenotype (SASP) and extracellular matrix pathways.

RESULTS

p16INK4a and p21CIP1/WAF1 staining in senescent skin cells revealed low and high expression subgroups that did not correspond to chronological age. Topical HPE significantly reduced high p16INK4a cells in the dermis (p = .02). There was also a decrease in telomere damage after topical HPE (p = .03). In patients with high senescent cells at baseline, there was a 40% reduction in proinflammatory SASP. Extracellular matrix remodeling pathways, including collagen and elastic fibers, were up-regulated.

CONCLUSION

Topical HPE, applied on intact skin, reduced senescence signaling and senescence-associated telomere damage after 12 weeks of twice daily use, targeting a path for skin longevity or healthy skin aging.

Is castration leading to biological aging in dogs? Assessment of lipid peroxidation, inflammation, telomere length, mitochondrial DNA copy number, and expression of telomerase and age-related genes

BACKGROUND

Biological aging is a complex process influenced by various factors, including reproductive status and castration. This study aimed to evaluate the impact of castration on biological aging in dogs.

METHOD

Fifteen male crossbred dogs were randomly divided into a sham-operation control group (n = 5) and a castrated group (n = 10). Blood samples were collected at weeks 0, 4, 8, 12, 16, and 18 post-surgery. Malondialdehyde (MDA as indicator of Lipid peroxidation), C-reactive protein (as an indicator of inflammation), telomere length, mitochondrial DNA (mtDNA) copy number, and the expression of age-related (P16, P21, TBX2) and telomerase-related (TERT) genes were assessed in blood samples.

RESULTS

Plasma MDA levels were higher in the control group at weeks 16 and 18, while CRP levels were higher only at week 18. Telomere length and mtDNA copy number were lower in the control group at week 18. Gene expression analysis showed that P16 was lower in the control group at weeks 8 and 12, P21 and TERT were lower at weeks 16 and 18, and TBX2 was lower at weeks 16 and 18. The TBX2/P16 ratio was lower in the control group at weeks 16 and 18 but higher at week 12, while the TBX2/P21 ratio did not differ between groups.

CONCLUSION

Castration appears to have a protective effect against biological aging in dogs, as evidenced by lower lipid peroxidation, inflammation, and age-related changes in telomere length, mtDNA copy number, and gene expression.

Evolution of Repetitive Elements, Their Roles in Homeostasis and Human Disease, and Potential Therapeutic Applications

Repeating sequences of DNA, or repetitive elements (REs), are common features across both prokaryotic and eukaryotic genomes. Unlike many of their protein-coding counterparts, the functions of REs in host cells remained largely unknown and have often been overlooked. While there is still more to learn about their functions, REs are now recognized to play significant roles in both beneficial and pathological processes in their hosts at the cellular and organismal levels. Therefore, in this review, we discuss the various types of REs and review what is known about their evolution. In addition, we aim to classify general mechanisms by which REs promote processes that are variously beneficial and harmful to host cells/organisms. Finally, we address the emerging role of REs in cancer, aging, and neurological disorders and provide insights into how RE modulation could provide new therapeutic benefits for these specific conditions.

Therapeutic approaches targeting aging and cellular senescence in Huntington's disease

Huntington's disease (HD) is a devastating neurodegenerative disease that is manifested by a gradual loss of physical, cognitive, and mental abilities. As the disease advances, age has a major impact on the pathogenic signature of mutant huntingtin (mHTT) protein aggregation. This review aims to explore the intricate relationship between aging, mHTT toxicity, and cellular senescence in HD. Scientific data on the interplay between aging, mHTT, and cellular senescence in HD were collected from several academic databases, including PubMed, Google Scholar, Google, and ScienceDirect. The search terms employed were "AGING," "HUNTINGTON'S DISEASE," "MUTANT HUNTINGTIN," and "CELLULAR SENESCENCE." Additionally, to gather information on the molecular mechanisms and potential therapeutic targets, the search was extended to include relevant terms such as "DNA DAMAGE," "OXIDATIVE STRESS," and "AUTOPHAGY." According to research, aging leads to worsening HD pathophysiology through some processes. As a result of the mHTT accumulation, cellular senescence is promoted, which causes DNA damage, oxidative stress, decreased autophagy, and increased inflammatory responses. Pro-inflammatory cytokines and other substances are released by senescent cells, which may worsen the neuronal damage and the course of the disease. It has been shown that treatments directed at these pathways reduce some of the HD symptoms and enhance longevity in experimental animals, pointing to a new possibility of treating the condition. Through their amplification of the harmful effects of mHTT, aging and cellular senescence play crucial roles in the development of HD. Comprehending these interplays creates novel opportunities for therapeutic measures targeted at alleviating cellular aging and enhancing HD patients' quality of life.

Prx1/PHB2 axis mediates mitophagy in oral leukoplakia cellular senescence

BACKGROUND

Oral leukoplakia (OLK) is the most common oral potentially malignant disorder (OPMD), which can be malignantly transformed into oral squamous cell carcinoma (OSCC). Peroxiredoxin1(Prx1) has been predicted to bind to Prohibitin2 (PHB2), which confers to affect OLK progression; however, the mechanism of Prx1/PHB2 mediated mitophagy involved in OLK remains unclear.

METHODS

This study aimed to explore the mechanism of the Prx1/PHB2 axis on senescence in OLK through mediating mitophagy. The positive rate of Ki67 and the expression of p21, p16, PHB2, and LC3 in human normal, OLK, and OSCC tissues were detected by immunohistochemical staining. The mitophagy and mitochondrial function changes were then analyzed in Prx1 knockdown and Prx1C52S mutations in dysplastic oral keratinocyte (DOK) cells treated with H2O2. In situ Proximity Ligation Assay combined with co-immunoprecipitation was used to detect the interaction between Prx1 and PHB2.

RESULTS

Clinically, the positive rate of Ki67 progressively increased from normal to OLK, OLK with dysplasia, and OSCC. Higher p21, p16, PHB2, and LC3 expression levels were observed in OLK with dysplasia than in normal and OSCC tissues. In vitro, PHB2 and LC3II expression gradually increased with the degree of DOK cell senescence. Prx1/PHB2 regulated mitophagy and affected senescence in H2O2-induced DOK cells. Furthermore, Prx1C52S mutation specifically reduced interaction between Prx1 and PHB2. Prx1Cys52 is associated with mitochondrial reactive oxygen species (ROS) accumulated and cell cycle arrest.

CONCLUSION

Prx1Cys52 functions as a redox sensor that binds to PHB2 and regulates mitophagy in the senescence of OLK, suggesting its potential as a clinical target.

Selective inhibition of HDAC6 by N-acylhydrazone derivative reduces the proliferation and induces senescence in carcinoma hepatocellular cells

Hepatocellular carcinoma (HCC) is a significant contributor to cancer-related deaths globally. Systemic therapy is the only treatment option for HCC at an advanced stage, with limited therapeutic response. In this study, we evaluated the antitumor potential of four N-acylhydrazone (NAH) derivatives, namely LASSBio-1909, 1911, 1935, and 1936, on HCC cell lines. We have previously demonstrated that the aforementioned NAH derivatives selectively inhibit histone deacetylase 6 (HDAC6) in lung cancer cells, but their effects on HCC cells have not been explored. Thus, the present study aimed to evaluate the effects of NAH derivatives on the proliferative behavior of HCC cells. LASSBio-1911 was the most cytotoxic compound against HCC cells, however its effects were minimal on normal cells. Our results showed that LASSBio-1911 inhibited HDAC6 in HCC cells leading to cell cycle arrest and decreased cell proliferation. There was also an increase in the frequency of cells in mitosis onset, which was associated with disturbing mitotic spindle formation. These events were accompanied by elevated levels of CDKN1A mRNA, accumulation of CCNB1 protein, and sustained ERK1 phosphorylation. Furthermore, LASSBio-1911 induced DNA damage, resulting in senescence and/or apoptosis. Our findings indicate that selective inhibition of HDAC6 may provide an effective therapeutic strategy for the treatment of advanced HCC, including tumor subtypes with integrated viral genome. Further, in vivo studies are required to validate the antitumor effect of LASSBio-1911 on liver cancer.

Epigenetic regulations of cellular senescence in osteoporosis

Osteoporosis (OP) is a prevalent age-related disease that is characterized by a decrease in bone mineral density (BMD) and systemic bone microarchitectural disorders. With age, senescent cells accumulate and exhibit the senescence-associated secretory phenotype (SASP) in bone tissue, leading to the imbalance of bone homeostasis, osteopenia, changes in trabecular bone structure, and increased bone fragility. Cellular senescence in the bone microenvironment involves osteoblasts, osteoclasts, and bone marrow mesenchymal stem cells (BMSCs), whose effects on bone homeostasis are regulated by epigenetics. Therefore, the epigenetic regulatory mechanisms of cellular senescence have received considerable attention as potential targets for preventing and treating osteoporosis. In this paper, we systematically review the mechanisms of aging-associated epigenetic regulation in osteoporosis, emphasizing the impact of epigenetics on cellular senescence, and summarize three current methods of targeting cellular senescence, which is helpful better to understand the pathogenic mechanisms of cellular senescence in osteoporosis and provides strategies for the development of epigenetic drugs for the treatment of osteoporosis.

The oral organ: A new vision of the mouth as a whole for a gerophysiological approach to healthy aging

This article brings a new perspective on oral physiology by presenting the oral organ as an integrated entity within the entire organism and its surrounding environment. Rather than considering the mouth solely as a collection of discrete functions, this novel approach emphasizes its role as a dynamic interphase, supporting interactions between the body and external factors. As a resilient ecosystem, the equilibrium of mouth ecological niches is the result of a large number of interconnected factors including the heterogeneity of different oral structures, diversity of resources, external and internal pressures and biological actors. The manuscript seeks to deepen the understanding of age-related changes within the oral cavity and throughout the organism, aligning with the evolving field of gerophysiology. The strategic position and fundamental function of the mouth make it an invaluable target for early prevention, diagnosis, treatment, and even reversal of aging effects throughout the entire organism. Recognizing the oral cavity capacity for sensory perception, element capture and information processing underscores its vital role in continuous health monitoring. Overall, this integrated understanding of the oral physiology aims at advancing comprehensive approaches to the oral healthcare and promoting broader awareness of its implications on the overall well-being.

Integrating transcriptomics and metabolomics to reveal the protective effect and mechanism of Bushen Kangshuai Granules on the elderly people

Background: Aging is characterized by a decline in the adaptability and resistance of the body. In this study, Bushen Kangshuai Granules (BKG), as a kind of Chinese herbal formula, was developed and shown to alleviate aging-related symptoms. Methods: Self-controlled study combined with RNA-seq and metabonomics were used to expound the efficacy and safety of BKG and revealed the regulation mechanism of BKG treating aging. In vitro experiments were used to confirm the analytical results. The aging cell model of AC16 cells were treated with D-galactose. The RT-qPCR was used to detect the impact of BKG on telomere length. The DCFH-DA staining was used for detecting intracellular ROS. The targeted signaling pathway was selected and verified using Western blot. Results: After 8 weeks of treatment, BKG significantly reduced SOD level (p = 0.046), TCM aging symptoms (p < 0.001) and TNF-α level (p = 0.044) in the elderly participants. High-throughput sequencing showed that BKG reversed the expression of 70 and 79 age-related genes and metabolites, respectively. Further enrichment analysis indicated that BKG downregulated the PI3K-AKT signaling pathway, extracellular matrix (ECM)-receptor interaction, and Rap1 signaling pathway, while up-regulating sphingolipid metabolism. The results of in vitro experiments show that, after D-gal treatment, the viability and telomere length of AC16 cells significantly decreased (p < 0.05), while the expression of ROS increased (p < 0.05), BKG significantly increased the telomere length of AC16 cells and reduced the level of ROS expression (p < 0.05). In addition, BKG decreased the expression of THBS1, PDGFRA, and EPS8L1(p < 0.05), consistent with the RNA-seq results. Our results also showed that BKG affects PI3K-AKT signaling pathway. Conclusion: BKG can significantly improve aging-related symptoms and increase SOD levels, which may be associated with the reversal of the expression of various aging-related genes. The PI3K-AKT signaling pathway and sphingolipid metabolism may be potential mechanisms underlying BKG anti-aging effects.

The Role of Fibroblasts in Skin Homeostasis and Repair

Fibroblasts are typical mesenchymal cells widely distributed throughout the human body where they (1) synthesise and maintain the extracellular matrix, ensuring the structural role of soft connective tissues; (2) secrete cytokines and growth factors; (3) communicate with each other and with other cell types, acting as signalling source for stem cell niches; and (4) are involved in tissue remodelling, wound healing, fibrosis, and cancer. This review focuses on the developmental heterogeneity of dermal fibroblasts, on their ability to sense changes in biomechanical properties of the surrounding extracellular matrix, and on their role in aging, in skin repair, in pathologic conditions and in tumour development. Moreover, we describe the use of fibroblasts in different models (e.g., in vivo animal models and in vitro systems from 2D to 6D cultures) for tissue bioengineering and the informative potential of high-throughput assays for the study of fibroblasts under different disease contexts for personalized healthcare and regenerative medicine applications.

The Gut and Skin Microbiome and Its Association with Aging Clocks

Aging clocks are predictive models of biological age derived from age-related changes, such as epigenetic changes, blood biomarkers, and, more recently, the microbiome. Gut and skin microbiota regulate more than barrier and immune function. Recent studies have shown that human microbiomes may predict aging. In this narrative review, we aim to discuss how the gut and skin microbiomes influence aging clocks as well as clarify the distinction between chronological and biological age. A literature search was performed on PubMed/MEDLINE databases with the following keywords: "skin microbiome" OR "gut microbiome" AND "aging clock" OR "epigenetic". Gut and skin microbiomes may be utilized to create aging clocks based on taxonomy, biodiversity, and functionality. The top contributing microbiota or metabolic pathways in these aging clocks may influence aging clock predictions and biological age. Furthermore, gut and skin microbiota may directly and indirectly influence aging clocks through the regulation of clock genes and the production of metabolites that serve as substrates or enzymatic regulators. Microbiome-based aging clock models may have therapeutic potential. However, more research is needed to advance our understanding of the role of microbiota in aging clocks.

Blood Lead Mediates the Relationship between Biological Aging and Hypertension: Based on the NHANES Database

Hypertension remains a major global public health crisis due to various contributing factors, such as age and environmental exposures. This study delves into exploring the intricate association between biological aging, blood lead levels, and hypertension, along with examining the mediating role of blood lead levels in the relationship between biological aging and hypertension. We analyzed data from two cycles of the NHANES, encompassing 4473 individuals aged 18 years and older. Our findings indicate that biological aging potentially escalates the risk of hypertension and the incidences of systolic blood pressure (SBP) and diastolic blood pressure (DBP) abnormalities. Utilizing weighted quantile sum (WQS) and quantile g-computation (QGC) model analyses, we observed that exposure to heavy metal mixtures, particularly lead, may elevate the likelihood of hypertension, SBP, and DBP abnormalities. Further mediation analysis revealed that lead significantly mediated the relationship between biological aging and hypertension and between biological aging and SBP abnormalities, accounting for 64% (95% CI, 49% to 89%) and 64% (95% CI, 44% to 88%) of the effects, respectively. These outcomes emphasize the criticality of implementing environmental health measures.

Effect of Cellular Senescence in Disease Progression and Transplantation: Immune Cells and Solid Organs

Aging of the world population significantly impacts healthcare globally and specifically, the field of transplantation. Together with end-organ dysfunction and prolonged immunosuppression, age increases the frequency of comorbid chronic diseases in transplant candidates and recipients, contributing to inferior outcomes. Although the frequency of death increases with age, limited use of organs from older deceased donors reflects the concerns about organ durability and inadequate function. Cellular senescence (CS) is a hallmark of aging, which occurs in response to a myriad of cellular stressors, leading to activation of signaling cascades that stably arrest cell cycle progression to prevent tumorigenesis. In aging and chronic conditions, senescent cells accumulate as the immune system's ability to clear them wanes, which is causally implicated in the progression of chronic diseases, immune dysfunction, organ damage, decreased regenerative capacity, and aging itself. The intimate interplay between senescent cells, their proinflammatory secretome, and immune cells results in a positive feedback loop, propagating chronic sterile inflammation and the spread of CS. Hence, senescent cells in organs from older donors trigger the recipient's alloimmune response, resulting in the increased risk of graft loss. Eliminating senescent cells or attenuating their inflammatory phenotype is a novel, potential therapeutic target to improve transplant outcomes and expand utilization of organs from older donors. This review focuses on the current knowledge about the impact of CS on circulating immune cells in the context of organ damage and disease progression, discusses the impact of CS on abdominal solid organs that are commonly transplanted, and reviews emerging therapies that target CS.

Comparison of Older Related versus Younger Unrelated Donors for Older Recipients of Allogeneic Hematopoietic Cell Transplantation with Acute Myeloid Leukemia or Myelodysplastic Syndrome: A Large Single-Center Analysis

For patients undergoing allogeneic hematopoietic cell transplantation (alloHCT), HLA-matched related donors (MRDs) have traditionally been the preferred donor source. However, as the age of recipients increases, their sibling donors are aging as well. In this study, we investigated whether younger matched unrelated donors (MUDs) might be a better donor source than similarly aged sibling donors for patients age >60 years with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). A total of 499 patients age 60 to 70 years with AML or MDS who underwent alloHCT from an older MRD (donor age ≥50 years) or a younger MUD (donor age ≤35 years) between 2010 and 2022 were evaluated. Of these, 360 patients (72%) received an MUD graft and 139 (28%) received an MRD graft. The median recipient age was 64 years in the MRD group and 66 years in the MUD group. With a median follow-up among survivors of 53 months (range, 9 to 147 months ), the 4-year progression-free survival was 40% in the MRD group and 41% in the MUD group (P = .79) and the 4-year overall survival was 50% and 44%, respectively (P = .15), with no between-group differences in nonrelapse mortality, relapse, and acute or chronic graft-versus-host disease. In the MUD group, we also compared the effect of donor age 18 to 24 years and donor age 25 to 35 years and found no differences in outcomes between the groups. We conclude that outcomes are comparable between the use of older MRDs and use of younger MUDs for elderly patients with AML or MDS, that there is no donor age effect among younger MUDs, and that the use of either donor type is reasonable.

Protocol to detect senescence-associated β-galactosidase and immunoperoxidase activity in fresh-frozen murine tissues

Double labeling to identify different markers in the same tissue section represents a useful tool either for in situ diagnosis or characterization of molecular associations. Here, we present a protocol to detect senescence-associated β-galactosidase (SA-βGal) and immunoperoxidase (IPO) activity in fresh-frozen murine tissues. We describe steps for tissue collection, solution preparation, SA-βGal staining, IPO staining, hematoxylin counterstaining, microscopic observation, and signal quantification. This protocol can be used to detect in situ proteins alongside SA-βGal activity. For complete details on the use and execution of this protocol, please refer to Pacheco-Rivera et al.1.

Aging and Autophagy: Roles in Musculoskeletal System Injury

Aging is a multifactorial process that ultimately leads to a decline in physiological function and a consequent reduction in the health span, and quality of life in elderly population. In musculoskeletal diseases, aging is often associated with a gradual loss of skeletal muscle mass and strength, resulting in reduced functional capacity and an increased risk of chronic metabolic diseases, leading to impaired function and increased mortality. Autophagy is a highly conserved physiological process by which cells, under the regulation of autophagy-related genes, degrade their own organelles and large molecules by lysosomal degradation. This process is unique to eukaryotic cells and is a strict regulator of homeostasis, the maintenance of energy and substance balance. Autophagy plays an important role in a wide range of physiological and pathological processes such as cell homeostasis, aging, immunity, tumorigenesis and neurodegenerative diseases. On the one hand, under mild stress conditions, autophagy mediates the restoration of homeostasis and proliferation, reduction of the rate of aging and delay of the aging process. On the other hand, under more intense stress conditions, an inadequate suppression of autophagy can lead to cellular aging. Conversely, autophagy activity decreases during aging. Due to the interrelationship between aging and autophagy, limited literature exists on this topic. Therefore, the objective of this review is to summarize the current concepts on aging and autophagy in the musculoskeletal system. The aim is to better understand the mechanisms of age-related changes in bone, joint and muscle, as well as the interaction relationship between autophagy and aging. Its goal is to provide a comprehensive perspective for the improvement of diseases of the musculoskeletal system.

Activity of DNA Repair Systems in the Cells of Long-Lived Rodents and Bats

Damages of various origin accumulated in the genomic DNA can lead to the breach of genome stability, and are considered to be one of the main factors involved in cellular senescence. DNA repair systems in mammalian cells ensure effective damage removal and repair of the genome structure, therefore, activity of these systems is expected to be correlated with high maximum lifespan observed in the long-lived mammals. This review discusses current results of the studies focused on determination of the DNA repair system activity and investigation of the properties of its key regulatory proteins in the cells of long-lived rodents and bats. Based on the works discussed in the review, it could be concluded that the long-lived rodents and bats in general demonstrate high efficiency in functioning and regulation of DNA repair systems. Nevertheless, a number of questions around the study of DNA repair in the cells of long-lived rodents and bats remain poorly understood, answers to which could open up new avenues for further research.

Identifying the relation between food groups and biological ageing: a data-driven approach

BACKGROUND

Heterogeneity in ageing rates drives the need for research into lifestyle secrets of successful agers. Biological age, predicted by epigenetic clocks, has been shown to be a more reliable measure of ageing than chronological age. Dietary habits are known to affect the ageing process. However, much remains to be learnt about specific dietary habits that may directly affect the biological process of ageing.

OBJECTIVE

To identify food groups that are directly related to biological ageing, using Copula Graphical Models.

METHODS

We performed a preregistered analysis of 3,990 postmenopausal women from the Women's Health Initiative, based in North America. Biological age acceleration was calculated by the epigenetic clock PhenoAge using whole-blood DNA methylation. Copula Graphical Modelling, a powerful data-driven exploratory tool, was used to examine relations between food groups and biological ageing whilst adjusting for an extensive amount of confounders. Two food group-age acceleration networks were established: one based on the MyPyramid food grouping system and another based on item-level food group data.

RESULTS

Intake of eggs, organ meat, sausages, cheese, legumes, starchy vegetables, added sugar and lunch meat was associated with biological age acceleration, whereas intake of peaches/nectarines/plums, poultry, nuts, discretionary oil and solid fat was associated with decelerated ageing.

CONCLUSION

We identified several associations between specific food groups and biological ageing. These findings pave the way for subsequent studies to ascertain causality and magnitude of these relationships, thereby improving the understanding of biological mechanisms underlying the interplay between food groups and biological ageing.

Establishing chronic models of age-related macular degeneration via long-term iron ion overload

Age-related macular degeneration (AMD) is characterized by the degenerative senescence in the retinal pigment epithelium (RPE) and photoreceptors, which is accompanied by the accumulation of iron ions in the aging retina. However, current models of acute oxidative stress are still insufficient to simulate the gradual progression of AMD. To address this, we established chronic injury models by exposing the aRPE-19 cells, 661W cells, and mouse retina to iron ion overload over time. Investigations at the levels of cell biology and molecular biology were performed. It was demonstrated that long-term treatment of excessive iron ions induced senescence-like morphological changes, decreased cell proliferation, and impaired mitochondrial function, contributing to apoptosis. Activation of the mitogen-activated protein kinase (MAPK) pathway and the downstream molecules were confirmed both in the aRPE-19 and 661W cells. Furthermore, iron ion overload resulted in dry AMD-like lesions and decreased visual function in the mouse retina. These findings suggest that chronic exposure to overloading iron ions plays a significant role in the pathogenesis of retinopathy and provide a potential model for future studies on AMD.NEW & NOTEWORTHY To explore the possibility of constructing reliable research carriers on age-related macular degeneration (AMD), iron ion overload was applied to establish models in vitro and in vivo. Subsequent investigations into cellular physiology and molecular biology confirmed the presence of senescence in these models. Through this study, we hope to provide a better option of feasible methods for future researches into AMD.

The impact of the senescent microenvironment on tumorigenesis: Insights for cancer therapy

The growing global burden of cancer, especially among people aged 60 years and over, has become a key public health issue. This trend suggests the need for a deeper understanding of the various cancer types in order to develop universally effective treatments. A prospective area of research involves elucidating the interplay between the senescent microenvironment and tumor genesis. Currently, most oncology research focuses on adulthood and tends to ignore the potential role of senescent individuals on tumor progression. Senescent cells produce a senescence-associated secretory phenotype (SASP) that has a dual role in the tumor microenvironment (TME). While SASP components can remodel the TME and thus hinder tumor cell proliferation, they can also promote tumorigenesis and progression via pro-inflammatory and pro-proliferative mechanisms. To address this gap, our review seeks to investigate the influence of senescent microenvironment changes on tumor development and their potential implications for cancer therapies.

Assessing the relationship between multimorbidity, NCD configurations, frailty phenotypes, and mortality risk in older adults

BACKGROUND

Older adults are increasingly susceptible to prolonged illness, multiple chronic diseases, and disabilities, which can lead to the coexistence of multimorbidity and frailty. Multimorbidity may result in various noncommunicable disease (NCD) patterns or configurations that could be associated with frailty and death. Mortality risk may vary depending on the presence of specific chronic diseases configurations or frailty.

METHODS

The aim was to examine the impact of NCD configurations on mortality risk among older adults with distinct frailty phenotypes. The population was analyzed from the Costa Rican Longevity and Healthy Aging Study Cohort (CRELES). A total of 2,662 adults aged 60 or older were included and followed for 5 years. Exploratory factor analysis and various clustering techniques were utilized to identify NCD configurations. The frequency of NCD accumulation was also assessed for a multimorbidity definition. Frailty phenotypes were set according to Fried et al. criteria. Kaplan‒Meier survival analyses, mortality rates, and Cox proportional hazards models were estimated.

RESULTS

Four different types of patterns were identified: 'Neuro-psychiatric', 'Metabolic', 'Cardiovascular', and 'Mixt' configurations. These configurations showed a higher mortality risk than the mere accumulation of NCDs [Cardiovascular HR:1.65 (1.07-2.57); 'Mixt' HR:1.49 (1.00-2.22); ≥3 NCDs HR:1.31 (1.09-1.58)]. Frailty exhibited a high and constant mortality risk, irrespective of the presence of any NCD configuration or multimorbidity definition. However, HRs decreased and lost statistical significance when phenotypes were considered in the Cox models [frailty + 'Cardiovascular' HR:1.56 (1.00-2.42); frailty + 'Mixt':1.42 (0.95-2.11); and frailty + ≥ 3 NCDs HR:1.23 (1.02-1.49)].

CONCLUSIONS

Frailty accompanying multimorbidity emerges as a more crucial indicator of mortality risk than multimorbidity alone. Therefore, studying NCD configurations is worthwhile as they may offer improved risk profiles for mortality as alternatives to straightforward counts.