Ageing, Cellular Senescence and Neurodegenerative Disease

Antioxidant PRDX3 gene therapy protects brain cells and prevents neurodegeneration in an animal model of Parkinson's disease

Neurodegenerative diseases, including Parkinson's Disease (PD), are a significant global health challenge with no effective therapies to counteract neurodegeneration. Genetic and environmental factors lead to mitochondrial dysfunction and increased reactive oxygen species (ROS), resulting in oxidative stress. This stress reduces levels of Peroxiredoxin 3 (PRDX3), a key protein for maintaining ROS balance at the mitochondrial level, increasing the substantia nigra's susceptibility to damage. To investigate the protective role of antioxidant gene therapy in a PD model, we overexpressed the PRDX3 enzyme using a cell-penetrating peptide-based delivery system (mRVG9R-PRDX3 complex). The mRVG9R peptide was combined with a green fluorescent protein (GFP) reporter plasmid expressing PRDX3 to create the complex. Overexpression of the PRDX3 gene in neuronal phenotype cells was confirmed in vitro using dopaminergic SH-SY5Y cells. Following successful in vitro expression, the mRVG9R-PRDX3 complex was stereotaxically injected into the striatum of male C57BL/6 mice. The PD model was induced by administering paraquat (PQ) twice a week for 6 weeks. After the final PQ injection, motor and cognitive functions were evaluated, followed by histological analysis. Animals treated with the mRVG9R-PRDX3 complex showed a clear reduction in PQ-induced PD symptomatology and prevented cellular senescence in the substantia nigra's neuronal population. The mRVG9R-PRDX3 gene therapy improved motor and cognitive functions in the PD animal model and demonstrated potential in protecting substantia nigra dopaminergic neurons from PQ-induced death.

Chronic kidney disease and aging: dissecting the p53/p21 pathway as a therapeutic target

Chronic kidney diseases (CKD) are a group of multi-factorial disorders that markedly impair kidney functions with progressive renal deterioration. Aging contributes to age-specific phenotypes in kidneys, which undergo several structural and functional alterations, such as a decline in regenerative capacity and increased fibrosis, inflammation, and tubular atrophy, all predisposing them to disease and increasing their susceptibility to injury while impeding their recovery. A central feature of these age-related processes is the activation of the p53/p21 pathway signaling. The pathway is a key player in cellular senescence, apoptosis, and cell cycle regulation, which are all key to maintaining the health of the kidney. P53 is a transcription factor and a tumor suppressor protein that responds to cell stress and damage. Persistent activation of cell p53 can lead to the expression of p21, an inhibitor of the cell cycle known as a cyclin-dependent kinase. This causes cells to cease dividing and leads to senescence, where cells can no longer increase. The accumulation of senescent cells in the aging kidney impairs kidney function by altering the microenvironment. As the number of senescent cells increases, the capacity of the kidney to recover from injury decreases, accelerating the progression of end-stage renal disease. This article review extensively explores the relationship between the p53/p21 pathway and cellular senescence within an aging kidney and the emerging therapeutic strategies that target it to overcome the impacts of cellular senescence on CKD.

Genome-Wide Network Analysis of DRG-Sciatic Nerve Network-Inferred Cellular Senescence and Senescence Phenotype in Peripheral Sensory Neurons

Accumulation of senescent neurons in the dorsal root ganglion (DRG) is an important tissue phenotype that causes age-related degeneration of peripheral sensory nerves. Senescent neurons are neurons with arrested cell cycle that have undergone cellular senescence but remain in the tissue and play various biological roles. To understand the accumulation of senescent neurons in the DRG during aging, we aimed to elucidate the mechanism that induces cellular senescence in DRG neurons and the role of senescent DRG neurons. We integrated multiple public transcriptome datasets for DRGs, which include cell bodies in neurons, and the sciatic nerve, which includes axons in neurons, using network medicine-based bioinformatics analysis. We thus inferred the molecular mechanisms involved in cellular senescence of DRG neurons, from molecular responses to senescence, in the DRG-sciatic nerve network. Network medicine-based bioinformatics analysis revealed that age-related Mapk3 decline leads to impaired cholesterol metabolism and biosynthetic function in axons, resulting in compensatory upregulation of Srebf1, a transcription factor involved in lipid and cholesterol metabolism. This in turn leads to CDKN2A-mediated cellular senescence. Furthermore, our analysis revealed that senescent DRG neurons develop a senescence phenotype characterized by activation of antigen-presenting cells via upregulation of Ctss as a hub gene. B cells were inferred as antigen-presenting cells activated by Ctss, and CD8-positive T cells were inferred as cells that receive antigen presentation from B cells.

Cellular senescence as a key contributor to secondary neurodegeneration in traumatic brain injury and stroke

Traumatic brain injury (TBI) and stroke pose major health challenges, impacting millions of individuals globally. Once considered solely acute events, these neurological conditions are now recognized as enduring pathological processes with long-term consequences, including an increased susceptibility to neurodegeneration. However, effective strategies to counteract their devastating consequences are still lacking. Cellular senescence, marked by irreversible cell-cycle arrest, is emerging as a crucial factor in various neurodegenerative diseases. Recent research further reveals that cellular senescence may be a potential driver for secondary neurodegeneration following brain injury. Herein, we synthesize emerging evidence that TBI and stroke drive the accumulation of senescent cells in the brain. The rationale for targeting senescent cells as a therapeutic approach to combat neurodegeneration following TBI/stroke is outlined. From a translational perspective, we emphasize current knowledge and future directions of senolytic therapy for these neurological conditions.

Effects of Probiotics on Neurodegenerative Disease-Related Symptoms and Systemic Inflammation: A Systematic Review

In recent years, probiotics, as a class of biologically active microorganisms, have increasingly attracted attention for their potential in treating neurodegenerative diseases (NDDs). To comprehensively assess the effects of probiotics on clinical symptoms and systemic inflammation regulation in various NDDs, this systematic review conducted a detailed search of the Cochrane Library, Embase, PubMed, and Web of Science databases, ultimately including 22 eligible randomized controlled trials (RCTs), with 4 RCTs for Alzheimer's Disease (AD), 10 RCTs for Parkinson's Disease (PD), 2 RCTs for Multiple Sclerosis (MS), and 2 RCTs for Mild Cognitive Impairment (MCI), and intervention durations ranging from 4 to 16 weeks. The comprehensive analysis indicates that probiotics help improve clinical symptoms related to NDDs, including gastrointestinal function, cognitive function, quality of life, and mental health. Additionally, probiotics generally have a positive effect on reducing systemic inflammation and enhancing antioxidant capacity in patients. In conclusion, existing evidence supports the promising potential of probiotics in treating NDDs. However, further large-scale, high-quality studies are needed to explore specific differences in efficacy among various probiotic strains, dosages, and modes of administration. Moreover, considering that lifestyle and dietary habits may modulate the effects of probiotics, these external factors should also be included in research considerations to gain a more comprehensive understanding of the mechanisms and application strategies of probiotics in NDDs treatment.

Siwu decoction mitigates radiation-induced immune senescence by attenuating hematopoietic damage

BACKGROUND

To investigate the long term effects of ionizing radiation (IR) on hematopoietic stem/progenitor cells (HSPCs), immune tissues and cells, and the effects of Siwu decoction (SWD) on immune senescence mice.

METHODS

C57BL/6 J mice were exposed to 6.0 Gy 60Co γ irradiation. After 8-weeks of IR, SWD (5, 10, 20 g/kg/d) was administered for 30 days. The changes of HSPCs in bone marrow (BM) and T, B type lymphocyte and natural killer (NK) cells in spleen were detected by flow cytometry. The changes of peripheral blood cells were also examined. Hematoxylin-eosin staining were used to detect the pathological lesions of hippocampus, spleen and thymus tissues. Absolute mouse telomere length quantification qPCR assay kit was used to measure the telomere length of BM cells. The expression of factors associated with inflammation and aging such as p16, β-galactosidase in spleen, thymus and BM was determined.

RESULTS

Administration of SWD could increase the proportion of LSK (Lin-, Sca-1 + , c-Kit-), multipotent progenitor cells and multipotent progenitor cells and decrease the proportion of common myeloid progenitors and granulocyte-macrophage progenitors in BM. The proportion of B cells and NK cells in spleen and the content of white blood cells, red blood cells, hemoglobin, lymphocytes and eosinophils in peripheral blood were increased, at the same time, the proportion of neutrophils and monocytes was reduced by SWD. The pathological lesions of hippocampus, spleen and thymus were improved. The expression of p16 and β-galactosidase in spleen, thymus and BM was reduced and shortening of the telomere of BM cells was inhibited after administration. In addition, SWD could reduce the content of Janus activated kinase (JAK) 1, JAK2 and signal transducer and activator of transcription 3 (STAT3) in BM and spleen.

CONCLUSIONS

SWD could slow down IR-induced immune senescence by improving hematopoietic and immunologic injury. SWD might reduce the inflammation level of BM hematopoietic microenvironment by acting on JAK/STAT signaling pathway, while the immune damage of mice was improved by affecting the differentiation of HSPCs. The remission of hematopoietic and immunologic senescence was further demonstrated at the overall level.

Hidden role of microglia during neurodegenerative disorders and neurocritical care: A mitochondrial perspective

The incidence of aging-related neurodegenerative disorders and neurocritical care diseases is increasing worldwide. Microglia, the main inflammatory cells in the brain, could be potential viable therapeutic targets for treating neurological diseases. Interestingly, mitochondrial functions, including energy metabolism, mitophagy and transfer, fission and fusion, and mitochondrial DNA expression, also change in activated microglia. Notably, mitochondria play an active and important role in the pathophysiology of neurodegenerative disorders and neurocritical care diseases. This review briefly summarizes the current knowledge on mitochondrial dysfunction in microglia in neurodegenerative disorders and neurocritical care diseases and comprehensively discusses the prospects of the application of neurological injury prevention and treatment targets by mitochondria.

The role of sirtuin 1 in ageing and neurodegenerative disease: A molecular perspective

Sirtuin 1 (SIRT1), an NAD+-dependent deacetylase, has emerged as a key regulator of cellular processes linked to ageing and neurodegeneration. SIRT1 modulates various signalling pathways, including those involved in autophagy, oxidative stress, and mitochondrial function, which are critical in the pathogenesis of neurodegenerative diseases. This review explores the therapeutic potential of SIRT1 in several neurodegenerative disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and Amyotrophic Lateral Sclerosis (ALS). Preclinical studies have demonstrated that SIRT1 activators, such as resveratrol, SRT1720, and SRT2104, can alleviate disease symptoms by reducing oxidative stress, enhancing autophagic flux, and promoting neuronal survival. Ongoing clinical trials are evaluating the efficacy of these SIRT1 activators, providing hope for future therapeutic strategies targeting SIRT1 in neurodegenerative diseases. This review explores the role of SIRT1 in ageing and neurodegenerative diseases, with a particular focus on its molecular mechanisms, therapeutic potential, and clinical applications.

Photobiomodulation in the aging brain: a systematic review from animal models to humans

Aging is a multifactorial biological process that may be associated with cognitive decline. Photobiomodulation (PBM) is a non-pharmacological therapy that shows promising results in the treatment or prevention of age-related cognitive impairments. The aim of this review is to compile the preclinical and clinical evidence of the effect of PBM during aging in healthy and pathological conditions, including behavioral analysis and neuropsychological assessment, as well as brain-related modifications. 37 studies were identified by searching in PubMed, Scopus, and PsycInfo databases. Most studies use wavelengths of 800, 810, or 1064 nm but intensity and days of application were highly variable. In animal studies, it has been shown improvements in spatial memory, episodic-like memory, social memory, while different results have been found in recognition memory. Locomotor activity improved in Parkinson disease models. In healthy aged humans, it has been outlined improvements in working memory, cognitive inhibition, and lexical/semantic access, while general cognition was mainly enhanced on Alzheimer disease or mild cognitive impairment. Anxiety assessment is scarce and shows mixed results. As for brain activity, results outline promising effects of PBM in reversing metabolic alterations and enhancing mitochondrial function, as evidenced by restored CCO activity and ATP levels. Additionally, PBM demonstrated neuroprotective, anti-inflammatory, immunomodulatory and hemodynamic effects. The findings suggest that PBM holds promise as a non-invasive intervention for enhancing cognitive function, and in the modulation of brain functional reorganization. It is necessary to develop standardized protocols for the correct, beneficial, and homogeneous use of PBM.

Tau proteins and senescent Cells: Targeting aging pathways in Alzheimer's disease

Alzheimer's disease (AD) is a devastating neurodegenerative disease characterized by abnormal accumulation of tau proteins and amyloid-β, leading to neuronal death and cognitive impairment. Recent studies have implicated aging pathways, including dysregulation of tau and cellular senescence in AD pathogenesis. In AD brains, tau protein, which normally stabilizes microtubules, becomes hyperphosphorylated and forms insoluble neurofibrillary tangles. These tau aggregates impair neuronal function and are propagated across the brain's neurocircuitry. Meanwhile, the number of senescent cells accumulating in the aging brain is rising, releasing a pro-inflammatory SASP responsible for neuroinflammation and neurodegeneration. This review explores potential therapeutic interventions for AD targeting tau protein and senescent cells, and tau -directed compounds, senolytics, eliminating senescent cells, and agents that modulate the SASP-senomodulators. Ultimately, a combined approach that incorporates tau-directed medications and targeted senescent cell-based therapies holds promise for reducing the harmful impact of AD's shared aging pathways.

Decoding senescence of aging single cells at the nexus of biomaterials, microfluidics, and spatial omics

Aging has profound effects on the body, most notably an increase in the prevalence of several diseases. An important aging hallmark is the presence of senescent cells that no longer multiply nor die off properly. Another characteristic is an altered immune system that fails to properly self-surveil. In this multi-player aging process, cellular senescence induces a change in the secretory phenotype, known as senescence-associated secretory phenotype (SASP), of many cells with the intention of recruiting immune cells to accelerate the clearance of these damaged senescent cells. However, the SASP phenotype results in inducing secondary senescence of nearby cells, resulting in those cells becoming senescent, and improper immune activation resulting in a state of chronic inflammation, called inflammaging, in many diseases. Senescence in immune cells, termed immunosenescence, results in further dysregulation of the immune system. An interdisciplinary approach is needed to physiologically assess aging changes of the immune system at the cellular and tissue level. Thus, the intersection of biomaterials, microfluidics, and spatial omics has great potential to collectively model aging and immunosenescence. Each of these approaches mimics unique aspects of the body undergoes as a part of aging. This perspective highlights the key aspects of how biomaterials provide non-cellular cues to cell aging, microfluidics recapitulate flow-induced and multi-cellular dynamics, and spatial omics analyses dissect the coordination of several biomarkers of senescence as a function of cell interactions in distinct tissue environments. An overview of how senescence and immune dysregulation play a role in organ aging, cancer, wound healing, Alzheimer's, and osteoporosis is included. To illuminate the societal impact of aging, an increasing trend in anti-senescence and anti-aging interventions, including pharmacological interventions, medical procedures, and lifestyle changes is discussed, including further context of senescence.

Cellular senescence in Alzheimer's disease: from physiology to pathology

Alzheimer's disease (AD) is one of the most common neurodegenerative disorders, characterized by the accumulation of Aβ and abnormal tau hyperphosphorylation. Despite substantial efforts in development of drugs targeting Aβ and tau pathologies, effective therapeutic strategies for AD remain elusive. Recent attention has been paid to the significant role of cellular senescence in AD progression. Mounting evidence suggests that interventions targeting cellular senescence hold promise in improving cognitive function and ameliorating hallmark pathologies in AD. This narrative review provides a comprehensive summary and discussion of the physiological roles, characteristics, biomarkers, and commonly employed in vivo and in vitro models of cellular senescence, with a particular focus on various cell types in the brain, including astrocytes, microglia, oligodendrocyte precursor cells, neurons, and endothelial cells. The review further delves into factors influencing cellular senescence in AD and emphasizes the significance of targeting cellular senescence as a promising approach for AD treatment, which includes the utilization of senolytics and senomorphics.

Deciphering the topological landscape of glioma using a network theory framework

Glioma stem cells have been recognized as key players in glioma recurrence and therapeutic resistance, presenting a promising target for novel treatments. However, the limited understanding of the role glioma stem cells play in the glioma hierarchy has drawn controversy and hindered research translation into therapies. Despite significant advances in our understanding of gene regulatory networks, the dynamics of these networks and their implications for glioma remain elusive. This study employs a systemic theoretical perspective to integrate experimental knowledge into a core endogenous network model for glioma, thereby elucidating its energy landscape through network dynamics computation. The model identifies two stable states corresponding to astrocytic-like and oligodendrocytic-like tumor cells, connected by a transition state with the feature of high stemness, which serves as one of the energy barriers between astrocytic-like and oligodendrocytic-like states, indicating the instability of glioma stem cells in vivo. We also obtained various stable states further supporting glioma's multicellular origins and uncovered a group of transition states that could potentially induce tumor heterogeneity and therapeutic resistance. This research proposes that the transition states linking both glioma stable states are central to glioma heterogeneity and therapy resistance. Our approach may contribute to the advancement of glioma therapy by offering a novel perspective on the complex landscape of glioma biology.

Lipofuscin accumulates in ganglionic neurons in chronic equine dysautonomia

Lipofuscin is a complex mixture of highly oxidized, cross-linked macromolecules that accumulates in neurons with age and some neurodegenerative diseases. Equine dysautonomia (ED) is a polyneuropathy that mainly affects autonomic and enteric nervous systems, resulting in alimentary tract dysfunction. Our main aim was to determine whether neuronal lipofuscin increased with increasing duration of ED. We investigated the prevalence of lipofuscin in cranial cervical ganglia of horses with acute (AED), subacute (SED), and chronic ED (CED), young controls (of similar age to ED cases), and aged controls (n = 8 per group). We used Schmorl stain for histologic detection of lipofuscin and assessed its accumulation in neurons using image analysis software. The percentage of neurons positive for lipofuscin increased with age in individual groups and all groups combined (p < 0.001). There were fewer positive neurons in AED and SED compared to aged controls (p < 0.001) and more in CED than AED cases (p = 0.042) and young controls (p = 0.012). We found a strong positive correlation between percentage positive neurons and percentage positive area of the neuron containing lipofuscin for combined groups (p < 0.001). Although neuronal lipofuscin increased in cranial cervical ganglion in CED cases, it remains to be determined whether this is a cause or consequence of neuronal degeneration.

Queen Bee Larva, an Edible By-Product of Royal Jelly, Alleviate D-Galactose-Induced Aging in Mouse by Regulating Gut Microbiota Structure and Amino Acid Metabolism

Queen bee larva (QBL), as a by-product of royal jelly, is a kind of protein-rich edible insect. However, the development and utilization of QBL have been very limited for an extended period, resulting in considerable economic waste. Notably, QBL has substantial potential for anti-aging treatments; however, systematic studies have been scarce. The present study aimed to analyze the effects of freeze-dried QBL powder (QBLP) treatment in a D-galactose (D-gal)-induced-aging mouse and to explore the mechanisms. A behavioral test indicated that QBLP-treated mice had improved cognitive function and memory decline caused by aging compared to untreated aged mice. Furthermore, QBLP treatment improved organ index in aged mice and prevented pathological damage to the brain tissue. Concomitantly, treatment of D-gal-induced-aging mice with QBLP significantly reduced the oxidative damage of serum and increased the skin moisture content of aging mice. Finally, integrated analyses of the gut microbiota and the serum metabolome showed that QBLP supplementation altered the composition of the gut microbiota, enriched biochemical pathways associated with amino acid metabolism, and adjusted serum concentrations of beneficial free amino acids. Overall, QBLP can improve symptoms related to D-gal-induced aging in mice by regulating gut microbiota structure and amino acid metabolism.

Transcriptomics analyses combined with intestinal microorganism survey suggest Resveratrol (RSV) anti-aging and anti-oxidant effects in silkworm (Bombyx mori)

The growing elderly population presents a significant concern, with the prolongation of life expectancy, aging diseases are becoming increasingly common. Resveratrol (RSV) has emerged as a promising compound for disease prevention. However, the effect of RSV on lifespan extension in different organisms, particularly the model organism silkworm, remains inconsistent. We conducted aging experiments using silkworm (B. mori) and employed transcriptomics to investigate the therapeutic effects of RSV on lifespan extension and healthy lifespan in silkworms. RSV increased the survival rate by 8.57 %-12.12 % and enhanced the antioxidant capacity of silkworms. Transcriptomic analysis demonstrated that genes in signaling pathways such as AMPK and FoxO were significantly upregulated. 16SrRNA sequencing of gut contents showed an increase in beneficial bacterial strains under the action of RSV. This study aims to enhance our understanding of lifespan regulation mechanisms using the silkworm model and provide new targets for anti-aging antioxidants research to delay the onset of age-related diseases.

Bibliometric and visual analysis of single-cell multiomics in neurodegenerative disease arrest studies

Background

Neurodegenerative diseases are progressive disorders that severely diminish the quality of life of patients. However, research on neurodegenerative diseases needs to be refined and deepened. Single-cell polyomics is a technique for obtaining transcriptomic, proteomic, and other information from a single cell. In recent years, the heat of single-cell multiomics as an emerging research tool for brain science has gradually increased. Therefore, the aim of this study was to analyze the current status and trends of studies related to the application of single-cell multiomics in neurodegenerative diseases through bibliometrics.

Result

A total of 596 publications were included in the bibliometric analysis. Between 2015 and 2022, the number of publications increased annually, with the total number of citations increasing significantly, exhibiting the fastest rate of growth between 2019 and 2022. The country/region collaboration map shows that the United States has the most publications and cumulative citations, and that China and the United States have the most collaborations. The institutions that produced the greatest number of articles were Harvard Medical School, Skupin, Alexander, and Wiendl. Among the authors, Heinz had the highest output. Mathys, H accumulated the most citations and was the authoritative author in the field. The journal Nature Communications has published the most literature in this field. A keyword analysis reveals that neurodegenerative diseases and lesions (e.g., Alzheimer's disease, amyloid beta) are the core and foundation of the field. Conversely, single-cell multiomics related research (e.g., single-cell RNA sequencing, bioinformatics) and brain nerve cells (e.g., microglia, astrocytes, neural stem cells) are the hot frontiers of this specialty. Among the references, the article "Single-cell transcriptomic analysis of Alzheimer's disease" is the most frequently cited (1,146 citations), and the article "Cell types in the mouse cortex and hippocampus revealed by single-cell RNA-seq" was the most cited article in the field.

Conclusion

The objective of this study is to employ bibliometric methods to visualize studies related to single-cell multiomics in neurodegenerative diseases. This will enable us to summarize the current state of research and to reveal key trends and emerging hotspots in the field.

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.

The putative contribution of cellular senescence to driving tauopathies

During mammalian aging, senescent cells accumulate in the body. Recent evidence suggests that senescent cells potentially contribute to age-related neurodegenerative diseases in the central nervous system (CNS), including tauopathies such as Alzheimer's disease (AD). Senescent cells undergo irreversible cell cycle arrest and release an inflammatory 'senescence-associated secretory profile' (SASP), which can exert devastating effects on surrounding cells. Senescent markers and SASP factors have been detected in multiple brain cells in tauopathies, including microglia, astrocytes, and perhaps even post-mitotic neurons, possibly contributing to the initiation as well as progression of these diseases. Here, we discuss the implications of presenting a senescent phenotype in tauopathies and highlight a potential role for the NOD-like receptor protein 3 (NLRP3) inflammasome as a newfound mechanism implicated in senescence and SASP formation.

The Azalea Hypothesis of Alzheimer Disease: A Functional Iron Deficiency Promotes Neurodegeneration

Chlorosis in azaleas is characterized by an interveinal yellowing of leaves that is typically caused by a deficiency of iron. This condition is usually due to the inability of cells to properly acquire iron as a consequence of unfavorable conditions, such as an elevated pH, rather than insufficient iron levels. The causes and effects of chlorosis were found to have similarities with those pertaining to a recently presented hypothesis that describes a pathogenic process in Alzheimer disease. This hypothesis states that iron becomes sequestered (e.g., by amyloid β and tau), causing a functional deficiency of iron that disrupts biochemical processes leading to neurodegeneration. Additional mechanisms that contribute to iron becoming unavailable include iron-containing structures not undergoing proper recycling (e.g., disrupted mitophagy and altered ferritinophagy) and failure to successfully translocate iron from one compartment to another (e.g., due to impaired lysosomal acidification). Other contributors to a functional deficiency of iron in patients with Alzheimer disease include altered metabolism of heme or altered production of iron-containing proteins and their partners (e.g., subunits, upstream proteins). A review of the evidence supporting this hypothesis is presented. Also, parallels between the mechanisms underlying a functional iron-deficient state in Alzheimer disease and those occurring for chlorosis in plants are discussed. Finally, a model describing the generation of a functional iron deficiency in Alzheimer disease is put forward.

Mechanisms of Transsynaptic Degeneration in the Aging Brain

A prominent feature in many neurodegenerative diseases involves the spread of the pathology from the initial site of damage to anatomically and functionally connected regions of the central nervous system (CNS), referred to as transsynaptic degeneration (TSD). This review covers the possible mechanisms of both retrograde and anterograde TSD in various age-related neurodegenerative diseases, including synaptically and glial mediated changes contributing to TDS and their potential as therapeutic targets. This phenomenon is well documented in clinical and experimental studies spanning various neurodegenerative diseases and their respective models, with a significant emphasis on the visual pathway, to be explored herein. With the increase in the aging population and subsequent rise in age-related neurodegenerative diseases, it is crucial to understand the underlying mechanisms of.

Inflammaging and Brain Aging

Progress made by the medical community in increasing lifespans comes with the costs of increasing the incidence and prevalence of age-related diseases, neurodegenerative ones included. Aging is associated with a series of morphological changes at the tissue and cellular levels in the brain, as well as impairments in signaling pathways and gene transcription, which lead to synaptic dysfunction and cognitive decline. Although we are not able to pinpoint the exact differences between healthy aging and neurodegeneration, research increasingly highlights the involvement of neuroinflammation and chronic systemic inflammation (inflammaging) in the development of age-associated impairments via a series of pathogenic cascades, triggered by dysfunctions of the circadian clock, gut dysbiosis, immunosenescence, or impaired cholinergic signaling. In addition, gender differences in the susceptibility and course of neurodegeneration that appear to be mediated by glial cells emphasize the need for future research in this area and an individualized therapeutic approach. Although rejuvenation research is still in its very early infancy, accumulated knowledge on the various signaling pathways involved in promoting cellular senescence opens the perspective of interfering with these pathways and preventing or delaying senescence.

Neuroprotective Effect of Codonopsis pilosula Polysaccharide on Aβ25-35-Induced Damage in PC12 Cells via the p38MAPK Signaling Pathways

OBJECTIVES

Plant polysaccharides have attracted increasing attention due to their high efficiency and low toxicity. Codonopsis pilosula polysaccharide (CPP) is an essential substance extracted from Codonopsis pilosula, known for its excellent antioxidant and neuroprotective effects. However, it is still unclear how CPP improves nerve protection and what its underlying molecular mechanisms are. This study aimed to investigate the neuroprotective effect of CPP on Aβ25-35-induced damage in PC12 cells and its underlying molecular mechanisms.

METHODS

The neuroprotective effect of CPP was evaluated using Aβ25-35-induced damage in pheochFfromocytoma (PC12) cells as an in vitro cell model. The cells were treated with CPP alone or in combination with SB203580 (an inhibitor of p38MAPK) in Aβ25-35 culture. The cell viability was assessed using a 3-(4,5-Dimethylthiazol-2-yl)-2,diphenyltetrazolium (MTT) assay. Furthermore, reactive oxygen species (ROS) were detected using flow cytometry. The production levels of intracellular superoxide dismutase (SOD), dismutase (SOD), glutathione (GSH), catalase (CAT), and malondialdehyFde (MDA) were determined using the colorimetric method. Annexin V-FITC and propidium iodide (PI) staining, as well as 33258 were performed using fluorescence microscopy. Moreover, the effect of adding SB203580 was studied to determine the changes in cell apoptosis induced by CPP treatment and Aβ25-35 induction.

RESULTS

The CPP markedly inhibited Aβ25-35-induced reduction in the viability and apoptosis of PC12 cells. CPP also reduced the Aβ25-35-induced increase in the expression of the apoptosis factors and the levels of free radicals (ROS and MDA) and reversed the Aβ25-35-induced suppression of antioxidant activity. Additionally, inhibition of p38MAPK via the addition of their antagonists reversed the observed anti-apoptosis effects of CPP.

CONCLUSIONS

CPP can efficiently provide neuroprotection against Aβ25-35-induced damage in PC12 cells brought about via oxidation and apoptosis reactions, and the underlying mechanisms involve the p38MAPK pathways. Therefore, CPP could potentially be useful as a neuroprotective agent in natural medicine, pharmacy, and the food industry.

Umbilical cord blood-derived exosomes attenuate dopaminergic neuron damage of Parkinson's disease mouse model

BACKGROUND

Umbilical cord blood (UCB) is a rich source of multifunctional stem cells characterized by low immunogenicity. Recent research in the fields of aging and regenerative medicine has revealed the potential of human umbilical cord blood-derived exosomes (UCB-Exos) in promoting wound healing, anti-aging, and regeneration. However, their role in neurodegenerative diseases, specifically Parkinson's disease (PD), remains unexplored. This study investigates the potential therapeutic effects and underlying mechanisms of UCB-Exos on PD.

METHODS

Large extracellular vesicles (LEv), Exos, and soluble fractions (SF) of human UCB plasma were extracted to investigate their effects on motor dysfunction of the MPTP-induced PD mouse model and identify the key components that improve PD symptoms. UCB-Exos were administered by the caudal vein to prevent or treat the PD mouse model. The motor function and pathological markers were detected. Differentially expressed gene and KEGG enrichment pathways were screened by transcriptome sequence. MN9D and SH-SY5Y cells were cultured and evaluated for cell viability, oxidative stress, cell cycle, and aging-related indexes by qRT-PCR, western blot, immunofluorescence, and flow cytometry. The protein expression level of the MAPK p38 and ERK1/2 signaling pathway was detected by western blot.

RESULTS

We observed that LEv, Exos, and SF all exhibited potential in ameliorating motor dysfunction in MPTP-induced PD model mice, with UCB-Exos demonstrating the most significant effect. UCB-Exos showed comparable efficacy in preventing and treating motor dysfunction, cognitive decline, and substantia nigra pathological damage in PD mice. Further investigations revealed that UCB-Exos could potentially alleviate oxidative damage, aging and degeneration, and energy metabolism disorders in neurons. Transcriptome sequencing results corroborated that genes differentially expressed due to UCB-Exos were primarily enriched in the neuroactive ligand-receptor interaction, Dopaminergic synapse, and MAPK signaling pathway. We also observed that UCB-Exos significantly inhibited the hyperphosphorylation of the MAPK p38 and ERK1/2 signaling pathways both in vitro and in vivo.

CONCLUSIONS

Our study provides a comprehensive evaluation of UCB-Exos on the neuroprotective effects and suggests that inhibition of hyperphosphorylation of MAPK p38 and ERK 1/2 signaling pathways by regulating transcription levels of HspB1 and Ppef2 may be the key mechanism for UCB-Exos to improve PD-related pathological features.

Role of hydrogen sulfide in health and disease

In the past, hydrogen sulfide (H2S) was recognized as a toxic and dangerous gas; in recent years, with increased research, we have discovered that H2S can act as an endogenous regulatory transmitter. In mammals, H2S-catalyzing enzymes, such as cystathionine-β-synthase, cystathionine-γ-lyase, and 3-mercaptopyruvate sulfurtransferase, are differentially expressed in a variety of tissues and affect a variety of biological functions, such as transcriptional and posttranslational modification of genes, activation of signaling pathways in the cell, and metabolic processes in tissues, by producing H2S. Various preclinical studies have shown that H2S affects physiological and pathological processes in the body. However, a detailed systematic summary of these roles in health and disease is lacking. Therefore, this review provides a thorough overview of the physiological roles of H2S in different systems and the diseases associated with disorders of H2S metabolism, such as ischemia-reperfusion injury, hypertension, neurodegenerative diseases, inflammatory bowel disease, and cancer. Meanwhile, this paper also introduces H2S donors and novel release modes, as well as the latest preclinical experimental results, aiming to provide researchers with new ideas to discover new diagnostic targets and therapeutic options.

Long-term demyelination and aging-associated changes in mice corpus callosum; evidence for the role of accelerated aging in remyelination failure in a mouse model of multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory and demyelinating disorder affecting the central nervous system. Evidence suggests that age-related neurodegeneration contributes to disability progression during the chronic stages of MS. Aging is characterized by decreased regeneration potential and impaired myelin repair in the brain. It is hypothesized that accelerated cellular aging contributes to the functional decline associated with neurodegenerative diseases. We assessed the impact of aging on myelin content in the corpus callosum (CC) and compared aging with the long-term demyelination (LTD) consequents induced by 12 weeks of feeding with a cuprizone (CPZ) diet. Initially, evaluating myelin content in 2-, 6-, and 18-month-old mice revealed a reduction in myelin content, particularly at 18 months. Myelin thickness was decreased and the g-ratio increased in aged mice. Although a lower myelin content and higher g-ratio were observed in LTD model mice, compared to the normally aged mice, both aging and LTD exhibited relatively similar myelin ultrastructure. Our findings provide evidence that LTD exhibits the hallmarks of aging such as elevated expression of senescence-associated genes, mitochondrial dysfunction, and high level of oxidative stress as observed following normal aging. We also investigated the senescence-associated β-galactosidase activity in O4+ late oligodendrocyte progenitor cells (OPCs). The senescent O4+/β-galactosidase+ cells were elevated in the CPZ diet. Our data showed that the myelin degeneration in CC occurs throughout the lifespan, and LTD induced by CPZ accelerates the aging process which may explain the impairment of myelin repair in patients with progressive MS.

Astragaloside IV confronts amyloid-beta-induced astrocyte senescence via hsp90aa1

Cell senescence is intensively related to aging and neurodegenerative diseases. This study aimed to explore the effect and targets of Astragaloside IV against amyloid-beta-induced astrocyte senescence. Oligomerized amyloid-beta was prepared to culture with human astrocytes. The effects of Astragaloside IV were assessed based on SA-β-gal staining analysis, senescence markers (p53, p16INK4, and p21WAF1), neurotrophic growth factor levels (qRT-PCR), and cell proliferation (CCK-8 kit). The targets for Astragaloside IV were predicted, and hsp90aa1 protein was verified using molecular docking. After hsp90aa1 overexpression, the effects of Astragaloside IV on amyloid-beta-induced astrocytes were assessed. Treatment of human amyloid-beta-induced astrocytes with Astragaloside IV can decrease the percentage of SA-β-gal positive cells, downregulate the p53, p16INK4, and p21WAF1 levels, and increase the levels of neurotrophic growth factors (IGF-1 and NGF mRNA) and cell proliferation. Based on target prediction, hsp90aa1 was found to be a potential target of Astragaloside IV. Moreover, cellular experiments demonstrated that exogenously enhanced expression of hsp90aa1 overexpression suppressed the protective effect of Astragaloside IV on amyloid-beta-induced human astrocytes. The results presented here demonstrate that Astragaloside IV could confront amyloid-beta-induced astrocyte senescence via hsp90aa1, possibly opening new therapeutic avenues.

An in vitro multi-organ microphysiological system (MPS) to investigate the gut-to-brain translocation of neurotoxins

The death of dopamine-producing neurons in the substantia nigra in the base of the brain is a defining pathological feature in the development of Parkinson's disease (PD). PD is, however, a multi-systemic disease, also affecting the peripheral nervous system and gastrointestinal tract (GIT) that interact via the gut-brain axis (GBA). Our dual-flow GIT-brain microphysiological system (MPS) was modified to investigate the gut-to-brain translocation of the neurotoxin trigger of PD, 1-methyl-4-phenylpyridinium (MPP+), and its impact on key GIT and brain cells that contribute to the GBA. The modular GIT-brain MPS in combination with quantitative and morphometric image analysis methods reproduces cell specific neurotoxin-induced dopaminergic cytotoxicity and mitochondria-toxicity with the drug having no detrimental impact on the viability or integrity of cellular membranes of GIT-derived colonic epithelial cells. Our findings demonstrate the utility and capability of the GIT-brain MPS for measuring neuronal responses and its suitability for identifying compounds or molecules produced in the GIT that can exacerbate or protect against neuronal inflammation and cell death.

Transformation of mulberry polyphenols by Lactobacillus plantarum SC-5: Increasing phenolic acids and enhancement of anti-aging effect

Fermentation can transform bioactive compounds in food and improve their biological activity. This study aims to explore the transformation of polyphenols in mulberry juice and the improvement of its anti-aging effect. The results demonstrated that Lactobacillus plantarum SC-5 transformed anthocyanin in mulberry juice into more phenolic acids, especially improved 2-hydroxy-3-(4-hydroxyphenyl) propanoic acid from 4.16 ± 0.06 to 10.07 ± 0.03. In the D-gal-induced mouse model, fermented mulberry juice significantly raised the abundance of Bifidobacteriaceae (303.7 %) and Lactobacillaceae (237.2 %) and Short-chain fatty acids (SCFAs) in intestine, further reducing the level of oxidative stress (12.3 %). Meanwhile, the expression of Sirtuin 1 (SIRT1) and Brain-derived neurotrophic factor (BDNF) increased, which protected the integrity of hippocampal tissue. Morris water maze results approved that fermented mulberry juice improved cognitive ability in aging mice (30.3 %). This study provides theoretical support for the view that fermentation is an effective means of developing functional foods.

Navitoclax safety, tolerability, and effect on biomarkers of senescence and neurodegeneration in aged nonhuman primates

Alzheimer's disease (AD) is the most common global dementia and is universally fatal. Most late-stage AD disease-modifying therapies are intravenous and target amyloid beta (Aβ), with only modest effects on disease progression: there remains a high unmet need for convenient, safe, and effective therapeutics. Senescent cells (SC) and the senescence-associated secretory phenotype (SASP) drive AD pathology and increase with AD severity. Preclinical senolytic studies have shown improvements in neuroinflammation, tau, Aβ, and CNS damage; most were conducted in transgenic rodent models with uncertain human translational relevance. In this study, aged cynomolgus monkeys had significant elevation of biomarkers of senescence, SASP, and neurological damage. Intermittent treatment with the senolytic navitoclax induced modest reversible thrombocytopenia; no serious drug-related toxicity was noted. Navitoclax reduced several senescence and SASP biomarkers, with CSF concentrations sufficient for senolysis. Finally, navitoclax reduced TSPO-PET frontal cortex binding and showed trends of improvement in CSF biomarkers of neuroinflammation, neuronal damage, and synaptic dysfunction. Overall, navitoclax administration was safe and well tolerated in aged monkeys, inducing trends of biomarker changes relevant to human neurodegenerative disease.

Advances in Nanotherapy for Targeting Senescent Cells

Aging is an inevitable process in the human body, and cellular senescence refers to irreversible cell cycle arrest caused by external aging-promoting mechanisms. Moreover, as age increases, the accumulation of senescent cells limits both the health of the body and lifespan and even accelerates the occurrence and progression of age-related diseases. Therefore, it is crucial to delay the periodic irreversible arrest and continuous accumulation of senescent cells to address the issue of aging. The fundamental solution is targeted therapy focused on eliminating senescent cells or reducing the senescence-associated secretory phenotype. Over the past few decades, the remarkable development of nanomaterials has revolutionized clinical drug delivery pathways. Their unique optical, magnetic, and electrical properties effectively compensate for the shortcomings of traditional drugs, such as low stability and short half-life, thereby maximizing the bioavailability and minimizing the toxicity of drug delivery. This article provides an overview of how nanomedicine systems control drug release and achieve effective diagnosis. By presenting and analyzing recent advances in nanotherapy for targeting senescent cells, the underlying mechanisms of nanomedicine for senolytic and senomorphic therapy are clarified, providing great potential for targeting senescent cells.

Proximate Composition, Health Benefits, and Food Applications in Bakery Products of Purple-Fleshed Sweet Potato (Ipomoea batatas L.) and Its By-Products: A Comprehensive Review

Ipomoea batatas (L.) Lam is a dicotyledonous plant originally from tropical regions, with China and Spain acting as the main producers from outside and within the EU, respectively. The root, including only flesh, is the edible part, and the peel, leaves, stems, or shoots are considered by-products, which are generated due to being discarded in the field and during processing. Therefore, this study aimed to perform a comprehensive review of the nutritional value, phytochemical composition, and health-promoting activities of purple-fleshed sweet potato and its by-products, which lead to its potential applications in bakery products for the development of functional foods. The methodology is applied to the selected topic and is used to conduct the search, review abstracts and full texts, and discuss the results using different general databases. The studies suggested that purple-fleshed sweet potato parts are characterized by a high content of essential minerals and bioactive compounds, including anthocyanins belonging to the cyanidin or the peonidin type. The flesh and leaves are also high in phenolic compounds and carotenoids such as lutein and β-carotene. The high content of phenolic compounds and anthocyanins provides the purple-fleshed sweet potato with high antioxidant and anti-inflammatory power due to the modulation effect of the transcription factor Nrf2 and NF-kB translocation, which may lead to protection against hepatic and neurological disorders, among others. Furthermore, purple-fleshed sweet potato and its by-products can play a dual role in food applications due to its attractive color and wide range of biological activities which enhance its nutritional profile. As a result, it is essential to harness the potential of the purple-fleshed sweet potato and its by-products that are generated during its processing through an appropriate agro-industrial valorization system.

Developing transcriptomic signatures as a biomarker of cellular senescence

Cellular senescence is a cell fate driven by different types of stress, where damaged cells exit from the cell cycle and, in many cases, develop an inflammatory senescence-associated secretory phenotype (SASP). Senescence has often been linked to driving aging and the onset of multiple diseases conferred by the harmful SASP, which disrupts tissue homeostasis and impairs the regular function of many tissues. This phenomenon was first observed in vitro when fibroblasts halted replication after approximately 50 population doublings. In addition to replication-induced senescence, factors such as DNA damage and oncogene activation can induce cellular senescence both in culture and in vivo. Despite their contribution to aging and disease, identifying senescent cells in vivo has been challenging due to their heterogeneity. Although senescent cells can express the cell cycle inhibitors p16Ink4a and/or p21Cip1 and exhibit SA-ß-gal activity and evidence of a DNA damage response, there is no universal biomarker for these cells, regardless of inducer or cell type. Recent studies have analyzed the transcriptomic characteristics of these cells, leading to the identification of signature gene sets like CellAge, SeneQuest, and SenMayo. Advancements in single-cell and spatial RNA sequencing now allow for analyzing senescent cell heterogeneity within the same tissue and the development of machine learning algorithms, e.g., SenPred, SenSig, and SenCID, to discover cellular senescence using RNA sequencing data. Such insights not only deepen our understanding of the genetic pathways driving cellular senescence, but also promote the development of its quantifiable biomarkers. This review summarizes the current knowledge of transcriptomic signatures of cellular senescence and their potential as in vivo biomarkers.

Asymptomatic herpes simplex virus brain infection elicits cellular senescence phenotypes in the central nervous system of mice suffering multiple sclerosis-like disease

Experimental autoimmune encephalomyelitis (EAE) is a demyelinating disease affecting the central nervous system (CNS) in animals that parallels several clinical and molecular traits of multiple sclerosis in humans. Herpes simplex virus type 1 (HSV-1) infection mainly causes cold sores and eye diseases, yet eventually, it can also reach the CNS, leading to acute encephalitis. Notably, a significant proportion of healthy individuals are likely to have asymptomatic HSV-1 brain infection with chronic brain inflammation due to persistent latent infection in neurons. Because cellular senescence is suggested as a potential factor contributing to the development of various neurodegenerative disorders, including multiple sclerosis, and viral infections may induce a premature senescence state in the CNS, potentially increasing susceptibility to such disorders, here we examine the presence of senescence-related markers in the brains and spinal cords of mice with asymptomatic HSV-1 brain infection, EAE, and both conditions. Across all scenarios, we find a significant increases of senescence biomarkers in the CNS with some differences depending on the analyzed group. Notably, some senescence biomarkers are exclusively observed in mice with the combined conditions. These results indicate that asymptomatic HSV-1 brain infection and EAE associate with a significant expression of senescence biomarkers in the CNS.

Functional social isolation mediates the association between depression and executive function in older women: findings from the Canadian Longitudinal Study on Aging Comprehensive cohort

Depression and social isolation increase risk for executive function declines and are among the top five modifiable risk factors for dementia. However, the interrelationships between depression, social isolation and executive function are not well established. Further evidence is needed to inform strategies to promote executive function and independence in older age. We examined whether social isolation mediated the association between depression and executive function in community-dwelling middle-aged and older adults and whether this association was modified by age and sex. Adults aged 45 to 85 years from the Canadian Longitudinal Study on Aging (CLSA) Comprehensive cohort were followed over three years (complete case analysis, n = 14,133). Baseline depressive symptoms, a history of clinical depression, and functional social isolation (perceived lack of social support) were self-reported. Executive function at follow-up was a composite measure of five cognitive tests. Conditional process analysis assessed the mediating effects of functional social isolation across age group and sex, adjusted for sociodemographic and health covariates. Functional social isolation significantly mediated the association of depressive symptoms (proportion mediated [PM] = 8.0%) or clinical depression (PM = 17.5%) with executive function only among women aged 75+ years. Functional social isolation explains a proportion of the total effect of depressive symptoms or clinical depression on executive function in women aged 75 and older. Although reverse causation cannot be ruled out, our findings suggest that interventions that reduce functional social isolation or depression in older women may promote executive function.

Combining experiments and bioinformatics to identify transforming growth factor-β1 as a key regulator in angiotensin II-induced trophoblast senescence

INTRODUCTION

Accelerated senescence of trophoblast may cause several diverse pregnancy outcomes; however, the cause of accelerated trophoblast senescence remains unclear. The renin-angiotensin system (RAS) is closely related to organ senescence. Therefore, in the present study, we hypothesized that angiotensin (Ang)II, one of the most important RAS family members, accelerates trophoblast senescence through the transforming growth factor β-1 (TGF-β1) pathway.

METHODS

AngII and Ang1-7 were used to stimulate pregnant rats. AngII and its inhibitor olmesartan were used to stimulate trophoblast. Thereafter, senescence levels were measured. Furthermore, we used AngII to stimulate trophoblast and utilized RNA-sequencing (RNAseq) to analyze the expression of differentially expressed genes (DEGs). After identifying the overlapping genes by comparing the DEGs and senescence-related genes, we employed CytoHubba software to calculate the top five hub genes and selected TGF-β1 as the target gene. We transfected the AngII-stimulated trophoblast with TGF-β1 small interfering RNA (siRNA) and measured the senescence levels.

RESULTS

Senescence markers were upregulated in the AngII group compared with that in the control group. Furthermore, following AngII stimulation and RNAseq measurement, we identified 607 DEGs and 13 overlapping genes. The top five hub genes were as follows: PLAU, PTGS2, PDGF-β, TGF-β1, and FOXO3. Upon knockdown of TGF-β1 expression in AngII-stimulated trophoblast using TGF-β1 siRNA, we observed a downregulation of p53 and p62 mRNA expression.

DISCUSSION

AngII accelerates trophoblast senescence through the TGF-β1 pathway.

Modulation of gut microbiome in the treatment of neurodegenerative diseases: A systematic review

BACKGROUND AND AIMS

Microbiota plays an essential role in maintaining body health, through positive influences on metabolic, defensive, and trophic processes and on intercellular communication. Imbalance in intestinal flora, with the proliferation of harmful bacterial species (dysbiosis) is consistently reported in chronic illnesses, including neurodegenerative diseases (ND). Correcting dysbiosis can have a beneficial impact on the symptoms and evolution of ND. This review examines the effects of microbiota modulation through administration of probiotics, prebiotics, symbiotics, or prebiotics' metabolites (postbiotics) in patients with ND like multiple sclerosis (MS), Alzheimer's disease (AD), Parkinson's disease (PD) and amyotrophic lateral sclerosis (ALS).

METHODS

PubMed, Web of Science, Medline databases and ClinicalTrials.gov registry searches were performed using pre-/pro-/postbiotics and ND-related terms. Further references were obtained by checking relevant articles.

RESULTS

Although few compared to animal studies, the human studies generally show positive effects on disease-specific symptoms, overall health, metabolic parameters, on oxidative stress and immunological markers. Therapy with probiotics in various forms (mixtures of bacterial strains, fecal microbiota transplant, diets rich in fermented foods) exert favorable effects on patients' mental health, cognition, and quality of life, targeting pathogenetic ND mechanisms and inducing reparatory mechanisms at the cellular level. More encouraging results have been observed in prebiotic/postbiotic therapy in some ND.

CONCLUSIONS

The effects of probiotic-related interventions depend on the patients' ND stage and pre-existing allopathic medication. Further studies on larger cohorts and long term comprehensive neuropsychiatric, metabolic, biochemical testing, and neuroimaging monitoring are necessary to optimize therapeutic protocols in ND.

From inflammatory signaling to neuronal damage: Exploring NLR inflammasomes in ageing neurological disorders

The persistence of neuronal degeneration and damage is a major obstacle in ageing medicine. Nucleotide-binding oligomerization domain (NOD)-like receptors detect environmental stressors and trigger the maturation and secretion of pro-inflammatory cytokines that can cause neuronal damage and accelerate cell death. NLR (NOD-like receptors) inflammasomes are protein complexes that contain NOD-like receptors. Studying the role of NLR inflammasomes in ageing-related neurological disorders can provide valuable insights into the mechanisms of neurodegeneration. This includes investigating their activation of inflammasomes, transcription, and capacity to promote or inhibit inflammatory signaling, as well as exploring strategies to regulate NLR inflammasomes levels. This review summarizes the use of NLR inflammasomes in guiding neuronal degeneration and injury during the ageing process, covering several neurological disorders such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, stroke, and peripheral neuropathies. To improve the quality of life and slow the progression of neurological damage, NLR-based treatment strategies, including inhibitor-related therapies and physical therapy, are presented. Additionally, important connections between age-related neurological disorders and NLR inflammasomes are highlighted to guide future research and facilitate the development of new treatment options.

Behaviour Hallmarks in Alzheimer's Disease 5xFAD Mouse Model

The 5xFAD transgenic mouse model widely used in Alzheimer's disease (AD) research recapitulates many AD-related phenotypes with a relatively early onset and aggressive age-dependent progression. Besides developing amyloid peptide deposits alongside neuroinflammation by the age of 2 months, as well as exhibiting neuronal decline by the age of 4 months that intensifies by the age of 9 months, these mice manifest a broad spectrum of behavioural impairments. In this review, we present the extensive repertoire of behavioural dysfunctions in 5xFAD mice, organised into four categories: motor skills, sensory function, learning and memory abilities, and neuropsychiatric-like symptoms. The motor problems, associated with agility and reflex movements, as well as balance and coordination, and skeletal muscle function, typically arise by the time mice reach 9 months of age. The sensory function (such as taste, smell, hearing, and vision) starts to deteriorate when amyloid peptide buildups and neuroinflammation spread into related anatomical structures. The cognitive functions, encompassing learning and memory abilities, such as visual recognition, associative, spatial working, reference learning, and memory show signs of decline from 4 to 6 months of age. Concerning neuropsychiatric-like symptoms, comprising apathy, anxiety and depression, and the willingness for exploratory behaviour, it is believed that motivational changes emerge by approximately 6 months of age. Unfortunately, numerous studies from different laboratories are often contradictory on the conclusions drawn and the identification of onset age, making preclinical studies in rodent models not easily translatable to humans. This variability is likely due to a range of factors associated with animals themselves, housing and husbandry conditions, and experimental settings. In the forthcoming studies, greater clarity in experimental details when conducting behavioural testing in 5xFAD transgenic mice could minimise the inconsistencies and could ensure the reliability and the reproducibility of the results.

Preliminary Analysis of Aging-Related Genes in Intracerebral Hemorrhage by Integration of Bulk and Single-Cell RNA Sequencing Technology

Background

Aging is recognized as the key risk for intracerebral hemorrhage (ICH). The detailed mechanisms of aging in ICH warrant exploration. This study aimed to identify potential aging-related genes associated with ICH.

Methods

ICH-specific aging-related genes were determined by the intersection of differentially expressed genes (DEGs) between perihematomal tissues and corresponding contralateral parts of four patients with ICH (GSE24265) and 349 aging-related genes obtained from the Aging Atlas database. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Set Enrichment Analysis (GSEA) analyses were performed to identify the potential biological functions and pathways in which these ICH-specific aging-related genes may be involved. Then, PPI network was established to identify the hub genes of ICH-specific aging-related genes. Meanwhile, miRNA-mRNA and transcription factor (TF)-mRNA regulatory networks were constructed to further explore the ICH-specific aging-related genes regulation. The relationship between these hub genes and immune infiltration was also further explored. Additional single-cell RNA-seq analysis (scRNA-seq, GSE167593) was used to locate the hub genes in different cell types. Besides, expression levels of the hub genes were validated using clinical samples from our institute and another GEO dataset (GSE206971).

Results

This study identified 24 ICH-specific aging-related genes, including 22 up-regulated and 2 down-regulated genes. The results of GO and KEGG suggested that the ICH-specific aging-related genes mainly enriched in immunity and inflammation-related pathways, suggesting that aging may affect the ich pathogenesis by regulating inflammatory and immune-related pathways.

Conclusion

Our study revealed 24 ICH-specific aging-related genes and their functions highly pertinent to ICH pathogenesis, providing new insights into the impact of aging on ICH.

Dietary diversity score and the acceleration of biological aging: a population-based study of 88,039 participants

OBJECTIVES

Our study aimed to investigate the association of dietary diversity score (DDS), as reflected by five dietary categories, with biological age acceleration.

DESIGN

A cross-sectional study.

SETTING AND PARTICIPANTS

This study included 88,039 individuals from the UK Biobank.

METHODS

Biological age (BA) was assessed using Klemerae-Doubal (KDM) and PhenoAge methods. The difference between BA and chronological age represents the age acceleration (AgeAccel), termed as "KDMAccel" and "PhenoAgeAccel". AgeAccel > 0 indicates faster aging. Generalized linear regression models were performed to assess the associations of DDS with AgeAccel. Similar analyses were performed for the five dietary categories.

RESULTS

After adjusting for multiple variables, DDS was inversely associated with KDMAccel (βHigh vs Low= -0.403, 95%CI: -0.492 to -0.314, P < 0.001) and PhenoAgeAccel (βHigh vs Low= -0.545, 95%CI: -0.641 to -0.450, P < 0.001). Each 1-point increment in the DDS was associated with a 4.4% lower risk of KDMAccel and a 5.6% lower risk of PhenoAgeAccel. The restricted cubic spline plots demonstrated a non-linear dose-response association between DDS and the risk of AgeAccel. The consumption of grains (βKDMAccel = -0.252, βPhenoAgeAccel = -0.197), vegetables (βKDMAccel = -0.044, βPhenoAgeAccel = -0.077) and fruits (βKDMAccel = -0.179, βPhenoAgeAccel = -0.219) was inversely associated with the two AgeAccel, while meat and protein alternatives (βKDMAccel = 0.091, βPhenoAgeAccel = 0.054) had a positive association (All P < 0.001). Stratified analysis revealed stronger accelerated aging effects in males, smokers, and drinkers. A strengthening trend in the association between DDS and AgeAccel as TDI quartiles increased was noted.

CONCLUSIONS

This study suggested that food consumption plays a role in aging process, and adherence to a higher diversity dietary is associated with the slowing down of the aging process.

Senolytic treatment does not mitigate oxidative stress-induced muscle atrophy but improves muscle force generation in CuZn superoxide dismutase knockout mice

Oxidative stress is associated with tissue dysfunctions that can lead to reduced health. Prior work has shown that oxidative stress contributes to both muscle atrophy and cellular senescence, which is a hallmark of aging that may drive in muscle atrophy and muscle contractile dysfunction. The purpose of the study was to test the hypothesis that cellular senescence contributes to muscle atrophy or weakness. To increase potential senescence in skeletal muscle, we used a model of oxidative stress-induced muscle frailty, the CuZn superoxide dismutase knockout (Sod1KO) mouse. We treated 6-month-old wildtype (WT) and Sod1KO mice with either vehicle or a senolytic treatment of combined dasatinib (5 mg/kg) + quercetin (50 mg/kg) (D + Q) for 3 consecutive days every 15 days. We continued treatment for 7 months and sacrificed the mice at 13 months of age. Treatment with D + Q did not preserve muscle mass, reduce NMJ fragmentation, or alter muscle protein synthesis in Sod1KO mice when compared to the vehicle-treated group. However, we observed an improvement in muscle-specific force generation in Sod1KO mice treated with D + Q when compared to Sod1KO-vehicle mice. Overall, these data suggest that reducing cellular senescence via D + Q is not sufficient to mitigate loss of muscle mass in a mouse model of oxidative stress-induced muscle frailty but may mitigate some aspects of oxidative stress-induced muscle dysfunction.

Detection of senescent cells in the mucosal healing process on type 2 diabetic rats after tooth extraction for biomaterial development

The delayed mucosal healing of tooth extraction sockets in diabetes has few known effective treatment strategies, and its underlying mechanism remains unknown. Senescent cells may play a pivotal role in this delay, given the well-established association between diabetes, senescent cells, and wound healing. Here, we demonstrated an increase in p21- or p16-positive senescent cells in the epithelial and connective tissues of extraction sockets in type 2 diabetic rats compared to those in control rats. Between 7 and 14 days after tooth extraction, a decrease in senescent cells and improvement in re-epithelialization failure were observed in the epithelium, while an increase in senescent cells and persistence of inflammation were observed in the connective tissue. These results suggest that cellular senescence may have been induced by diabetes and contributed to delayed mucosal healing by suppressing re-epithelization and persistent inflammation. These findings provide new targets for treatment using biomaterials, cells, and drugs.

Factors influencing gait performance in older adults in a dual-task paradigm

The aim of this study was to determine the effect of cognitive interference through a dual-task (DT) paradigm on gait parameters by sex or other predictive variables, such as physical fitness, health status, and cognition. A total of 125 older adults joined in this study (age, 72.42 ± 5.56 years old; 28 men and 97 women). The DT paradigm was evaluated through Comfortable Linear Gait (CLG) and Complex Gait Test (CGT). The gait parameters between single task (ST) vs. DT condition in men showed a significant reduction in speed (p < 0.001), cadence (p < 0.001), and step length (p = 0.049) and increased time to execute the CGT (p < 0.001), while women showed a decreased speed (p = 0.014), cadence (p < 0.001), and double support coefficient variation (CV) (p = 0.024) and increased single support time (p < 0.001) and CV step length (p < 0.05). In addition, women increased CGT time (p < 0.001). Furthermore, correlations between DT cost (DTC) cadence vs. Physical Activity for Elderly questionnaire (PASE) (r =  - 0.399; p = 0.008), DTC single support vs. 30 s Sit to Stand Test (r = - 0.356; 0.016), DTC single support vs. Rey Auditory Verbal Learning Test-Learning curve (r =  - 0.335; p = 0.023), DTC double support vs. 30 s Sit to Stand Test (r =  - 0.590; p < 0.001), DTC CV step length vs. 30 s Sit to Stand (r =  - 0.545; p = 0.003), and DTC CGT vs. 30 s Sit to Stand Test (r =  - 0.377; p = 0.048) were found. The results of our study indicate that the gait parameters within the DT condition decreased speed and cadence, while increasing CV step length and CGT time, causing slower gait with shortened steps in men and women.

Renal aging and mitochondrial quality control

Mitochondria are dynamic organelles that participate in different cellular process that control metabolism, cell division, and survival, and the kidney is one of the most metabolically active organs that contains abundant mitochondria. Perturbations in mitochondrial homeostasis in the kidney can accelerate kidney aging, and maintaining mitochondrial homeostasis can effectively delay aging in the kidney. Kidney aging is a degenerative process linked to detrimental processes. The significance of aberrant mitochondrial homeostasis in renal aging has received increasing attention. However, the contribution of mitochondrial quality control (MQC) to renal aging has not been reviewed in detail. Here, we generalize the current factors contributing to renal aging, review the alterations in MQC during renal injury and aging, and analyze the relationship between mitochondria and intrinsic renal cells. We also introduce MQC in the context of renal aging, and discuss the study of mitochondria in the intrinsic cells of the kidney, which is the innovation of our paper. In addition, during kidney injury and repair, the specific functions and regulatory mechanisms of MQC systems in resident and circulating cell types remain unclear. Currently, most of the studies we reviewed are based on animal and cellular models, the relationship between renal tissue aging and mitochondria has not been adequately investigated in clinical studies, and there is still a long way to go.

Puerarin Delays Mammary Gland Aging by Regulating Gut Microbiota and Inhibiting the p38MAPK Signaling Pathway

Mammary gland aging is one of the most important problems faced by humans and animals. How to delay mammary gland aging is particularly important. Puerarin is a kind of isoflavone substance extracted from Pueraria lobata, which has anti-inflammatory, antioxidant, and other pharmacological effects. However, the role of puerarin in delaying lipopolysaccharide (LPS)-induced mammary gland aging and its underlying mechanism remains unclear. On the one hand, we found that puerarin could significantly downregulate the expression of senescence-associated secretory phenotype (SASP) and age-related indicators (SA-β-gal, p53, p21, p16) in mammary glands of mice. In addition, puerarin mainly inhibited the p38MAPK signaling pathway to repair mitochondrial damage and delay mammary gland aging. On the other hand, puerarin could also delay the cellular senescence of mice mammary epithelial cells (mMECs) by targeting gut microbiota and promoting the secretion of gut microbiota metabolites. In conclusion, puerarin could not only directly act on the mMECs but also regulate the gut microbiota, thus, playing a role in delaying the aging of the mammary gland. Based on the above findings, we have discovered a new pathway for puerarin to delay mammary gland aging.

Nanocarriers for natural polyphenol senotherapeutics

Senescence is a heterogenous and dynamic process in which various cell types undergo cell-cycle arrest due to cellular stressors. While senescence has been implicated in aging and many human pathologies, therapeutic interventions remain inadequate due to the absence of a comprehensive set of biomarkers in a context-dependent manner. Polyphenols have been investigated as senotherapeutics in both preclinical and clinical settings. However, their use is hindered by limited stability, toxicity, modest bioavailability, and often inadequate concentration at target sites. To address these limitations, nanocarriers such as polymer nanoparticles and lipid vesicles can be utilized to enhance the efficacy of senolytic polyphenols. Focusing on widely studied senolytic agents-specifically fisetin, quercetin, and resveratrol-we provide concise summaries of their physical and chemical properties, along with an overview of preclinical and clinical findings. We also highlight common signaling pathways and potential toxicities associated with these agents. Addressing challenges linked to nanocarriers, we present examples of senotherapeutic delivery to various cell types, both with and without nanocarriers. Finally, continued research and development of senolytic agents and nanocarriers are encouraged to reduce the undesirable effects of senescence on different cell types and organs. This review underscores the need for establishing reliable sets of senescence biomarkers that could assist in evaluating the effectiveness of current and future senotherapeutic candidates and nanocarriers.

Cellular senescence in cancer: molecular mechanisms and therapeutic targets

Aging exhibits several hallmarks in common with cancer, such as cellular senescence, dysbiosis, inflammation, genomic instability, and epigenetic changes. In recent decades, research into the role of cellular senescence on tumor progression has received widespread attention. While how senescence limits the course of cancer is well established, senescence has also been found to promote certain malignant phenotypes. The tumor-promoting effect of senescence is mainly elicited by a senescence-associated secretory phenotype, which facilitates the interaction of senescent tumor cells with their surroundings. Targeting senescent cells therefore offers a promising technique for cancer therapy. Drugs that pharmacologically restore the normal function of senescent cells or eliminate them would assist in reestablishing homeostasis of cell signaling. Here, we describe cell senescence, its occurrence, phenotype, and impact on tumor biology. A "one-two-punch" therapeutic strategy in which cancer cell senescence is first induced, followed by the use of senotherapeutics for eliminating the senescent cells is introduced. The advances in the application of senotherapeutics for targeting senescent cells to assist cancer treatment are outlined, with an emphasis on drug categories, and the strategies for their screening, design, and efficient targeting. This work will foster a thorough comprehension and encourage additional research within this field.

Acute intoxication with diisopropylfluorophosphate promotes cellular senescence in the adult male rat brain

Acute intoxication with high levels of organophosphate (OP) cholinesterase inhibitors can cause cholinergic crisis, which is associated with acute, life-threatening parasympathomimetic symptoms, respiratory depression and seizures that can rapidly progress to status epilepticus (SE). Clinical and experimental data demonstrate that individuals who survive these acute neurotoxic effects often develop significant chronic morbidity, including behavioral deficits. The pathogenic mechanism(s) that link acute OP intoxication to chronic neurological deficits remain speculative. Cellular senescence has been linked to behavioral deficits associated with aging and neurodegenerative disease, but whether acute OP intoxication triggers cellular senescence in the brain has not been investigated. Here, we test this hypothesis in a rat model of acute intoxication with the OP diisopropylfluorophosphate (DFP). Adult male Sprague-Dawley rats were administered DFP (4 mg/kg, s.c.). Control animals were administered an equal volume (300 µL) of sterile phosphate-buffered saline (s.c.). Both groups were subsequently injected with atropine sulfate (2 mg/kg, i.m.) and 2-pralidoxime (25 mg/kg, i.m.). DFP triggered seizure activity within minutes that rapidly progressed to SE, as determined using behavioral seizure criteria. Brains were collected from animals at 1, 3, and 6 months post-exposure for immunohistochemical analyses of p16, a biomarker of cellular senescence. While there was no immunohistochemical evidence of cellular senescence at 1-month post-exposure, at 3- and 6-months post-exposure, p16 immunoreactivity was significantly increased in the CA3 and dentate gyrus of the hippocampus, amygdala, piriform cortex and thalamus, but not the CA1 region of the hippocampus or the somatosensory cortex. Co-localization of p16 immunoreactivity with cell-specific biomarkers, specifically, NeuN, GFAP, S100β, IBA1 and CD31, revealed that p16 expression in the brain of DFP animals is neuron-specific. The spatial distribution of p16-immunopositive cells overlapped with expression of senescence associated β-galactosidase and with degenerating neurons identified by FluoroJade-C (FJC) staining. The co-occurrence of p16 and FJC was positively correlated. This study implicates cellular senescence as a novel pathogenic mechanism underlying the chronic neurological deficits observed in individuals who survive OP-induced cholinergic crisis.