Tau oligomer induced HMGB1 release contributes to cellular senescence and neuropathology linked to Alzheimer's disease and frontotemporal dementia

Progressive hippocampal senescence and persistent memory deficits in traumatic brain Injury: A role of delayed testosterone

Cellular senescence is a stable, pro-inflammatory cell cycle arrest that has been recently implicated in the persistent memory deficits experienced with repetitive mild traumatic brain injury (rmTBI). Testosterone (T) treatment immediately following traumatic brain injury (TBI) mitigates cognitive deficits and cellular dysfunction known to induce cellular senescence. However, it has yet to be elucidated whether the therapeutic window for T treatment can be extended to a subacute time post-injury. This study examined the progression of hippocampal cellular senescence after rmTBI and evaluated the effects of subacute T on persistent memory deficits and cellular senescence post-injury. Changes in senescence-associated markers in the hippocampus were quantified at 5- and 9-weeks post-injury (WPI). An age-independent progressive increase in senescence-associated gene expression was observed for Cdkn2a, Cdkn1a, and p53 protein levels, along with a decrease in Sirt1 gene expression. Acute and persistent cognitive deficits were observed in the rmTBI rats as compared to sham rats. Serum T levels were significantly decreased at 4 WPI. Testosterone administration at 5 WPI ameliorated these persistent memory deficits. Moreover, subacute T treatment reduced rmTBI-induced levels of Cdkn2a 4 weeks post-treatment. This study indicates that rmTBI results in a progressive cellular senescence pathology that may contribute to the underlying mechanisms of persistent cognitive symptoms. Therapeutically targeting cellular senescence within this extended temporal window holds implications for patients dealing with the chronic cognitive ramifications of rmTBI.

Inflammasome links traumatic brain injury, chronic traumatic encephalopathy, and Alzheimer's disease

Traumatic brain injury, chronic traumatic encephalopathy, and Alzheimer's disease are three distinct neurological disorders that share common pathophysiological mechanisms involving neuroinflammation. One sequela of neuroinflammation includes the pathologic hyperphosphorylation of tau protein, an endogenous microtubule-associated protein that protects the integrity of neuronal cytoskeletons. Tau hyperphosphorylation results in protein misfolding and subsequent accumulation of tau tangles forming neurotoxic aggregates. These misfolded proteins are characteristic of traumatic brain injury, chronic traumatic encephalopathy, and Alzheimer's disease and can lead to downstream neuroinflammatory processes, including assembly and activation of the inflammasome complex. Inflammasomes refer to a family of multimeric protein units that, upon activation, release a cascade of signaling molecules resulting in caspase-induced cell death and inflammation mediated by the release of interleukin-1β cytokine. One specific inflammasome, the NOD-like receptor protein 3, has been proposed to be a key regulator of tau phosphorylation where it has been shown that prolonged NOD-like receptor protein 3 activation acts as a causal factor in pathological tau accumulation and spreading. This review begins by describing the epidemiology and pathophysiology of traumatic brain injury, chronic traumatic encephalopathy, and Alzheimer's disease. Next, we highlight neuroinflammation as an overriding theme and discuss the role of the NOD-like receptor protein 3 inflammasome in the formation of tau deposits and how such tauopathic entities spread throughout the brain. We then propose a novel framework linking traumatic brain injury, chronic traumatic encephalopathy, and Alzheimer's disease as inflammasome-dependent pathologies that exist along a temporal continuum. Finally, we discuss potential therapeutic targets that may intercept this pathway and ultimately minimize long-term neurological decline.

Co-Assembled Cryptotanshinone Derivative and Glycyrrhizic Acid Carrier-Free Hydrogel: A Synergistic Approach to Acne Treatment

Traditional anti-inflammatory and antimicrobial drugs often fail to address all aspects of acne vulgaris and are prone to causing adverse effects such as skin irritation, dryness, and allergic reactions. Consequently, there is a growing preference for the exploration of natural and safer therapeutic agents from plant sources. In this study, we developed a coassembled CU-GA hydrogel formed by cross-linking small active molecules─glycyrrhizic acid (GA) and a cryptotanshinone-peptide conjugate (CTS-G-GLU, CU). The CU-GA hydrogel exhibits a distinct nanofibrous structure under a microscopic view. Material characterization and molecular dynamics simulations explain that its assembly mechanism may be related to a series of noncovalent interactions. Preliminary acne treatment tests show that the hydrogel has high skin permeability, biocompatibility, and effective antibacterial and anti-inflammatory properties. This efficient formulation, free of external gelling agents, is particularly suitable for sensitive, acne-prone skin and will revolutionize the development of emerging acne treatment hydrogels.

Prolonged loss of nuclear HMGB1 in neurons following modeled TBI and implications for long-term genetic health

Under normal physiological conditions high mobility group box protein 1 (HMGB1) stabilizes chromatin, controls transcription, and contributes to DNA repair. Cellular stress or injury results in HMGB1 release from the nucleus acting as a proinflammatory cytokine. The objective of this study was to characterize the temporal progression of nuclear HMGB1 loss up to one week following modeled TBI in 250 g male rats and correlate these changes with the response of DNA damage proteins. HMGB1 was present in the cytoplasm and absent from the nucleus of neurons within 6 h of injury. Quantitative immunohistochemistry and Western blot analysis showed a significant decrease in nuclear HMGB1 expression at 6 and 24 h post-injury compared to controls. Approximately 20 % of neurons were lacking nuclear HMGB1 expression at 7 days post-injury. Cells which were negative for nuclear HMGB1 expression labelled positive for HIF1α, PARP, and γH2AX, indicators of oxidative stress and DNA damage. Nuclear HIF1α expression was detected at 6 h after injury. Nuclear expression of HIF1α, PARP, and γH2AX was observed at 7 days post-injury, suggesting activation of oxidative stress response mechanisms and DNA damage repair pathways. The temporal changes in HMGB1 translocation in conjunction with expression of DNA damage markers suggest a relationship between injury-induced HMGB1 loss in neurons and subsequent DNA damage. These results highlight a potential injury response mechanism with long-term implications in relation to genetic health of surviving neurons.

p16-expressing microglia and endothelial cells promote tauopathy and neurovascular abnormalities in PS19 mice

Cellular senescence is characterized by irreversible cell-cycle exit, a pro-inflammatory secretory phenotype, macromolecular damage, and deregulated metabolism. Senescent cells are highly associated with age-related diseases. We previously demonstrated that targeted elimination of senescent cells prevents neurodegenerative disease in tau (MAPTP301S;PS19) mutant mice. Here, we show that genetic ablation of the senescence mediator p16Ink4a is sufficient to attenuate senescence signatures in PS19 mice. Disease phenotypes-including neuroinflammation, phosphorylated tau, neurodegeneration, and cognitive impairment-were blunted in the absence of p16Ink4a. Additionally, we found that PS19 mouse brains display p16Ink4-dependent neurovascular alterations such as vessel dilation, increased vessel density, deregulated endothelial cell extracellular matrix, and astrocytic endfoot depolarization. Finally, we show that p16Ink4a deletion in endothelial cells and microglia alone attenuates many of the same phenotypes. Altogether, these results indicate that neurodegenerative disease in PS19 mice is driven, at least in part, by p16Ink4a-expressing endothelial cells and microglia.

Novel strategies for targeting tau oligomers in neurodegenerative diseases

Tau protein is a soluble microtubule-associated protein enriched in neurons, is mainly distributed in the central nervous system, and is responsible for stabilizing neurons. Tau maintains nerve cell morphology and internal transport by binding to normal microtubules. In neurodegenerative diseases, such as Alzheimer's disease (AD), tau proteins undergo aberrant phosphorylation, resulting in their removal from microtubules and the formation of neurofibrillary tangles (NFTs), which are key pathological features. In contrast to the late formation of non-soluble NFTs, early, smaller, soluble tau oligomers (tauO) with disseminated toxicity are considered necessary in neurodegenerative disorders, such as the primary form of tau toxicity in the AD process. Although an increasing number of studies are focusing on tauO, there are still problems to be solved, mainly concerning the molecular and inhibitory mechanisms of tauO toxicity. In this paper, we summarize the new strategies for the molecular mechanisms of tauO toxicity, detection methods, and interventions in the last five years. An outlook on these new strategies and the challenges that may be foreseen is presented to provide new directions for future applications in the clinical treatment of neurodegenerative diseases.

High-affinity, broad-spectrum, "centipede-like" multi-branched drug conjugates, anchored to the S protein, for blocking coronavirus infection

Over the past two decades, various coronaviruses have posed a severe threat to human life and health, with the spike protein (S protein) being a critical protein for infecting host cells. Glycyrrhizic acid (GA), as a natural drug, can inhibit the infection of coronaviruses by binding to the receptor-binding domain (RBD) of the S protein. However, issues like poor water solubility and weak binding affinity with the S protein have hindered its further application. Therefore, drawing inspiration from the biological structure of centipedes, a ROS-responsive multi-branched drug conjugate (ODPAG) was constructed through a "polymer-drug linkage" strategy using dextran as the backbone and GA as the active "claw". ODPAG exhibited drug loading of 22.0 ± 0.2% (OD40kPAG) and 19.7 ± 0.1% (OD450kPAG), showing ROS responsiveness with a half-life 6.4 times that of GA (OD40kPAG) and 5.4 times longer (OD450kPAG). In in vitro antiviral experiments, ODPAG exhibited an enhanced binding affinity to the S protein, with IC50 values of 1.33 μM (OD40kPAG) and 0.89 μM (OD450kPAG) against SARS-CoV-2 pseudovirus, demonstrating exceptional antiviral efficacy. These results collectively indicate that ODPAG can block coronavirus infection by binding to the S protein, exhibiting significant potential in addressing the current challenges posed by the novel coronavirus. Additionally, the "polymer-drug conjugate" strategy employed in this process is efficient, cost-effective, and offers new insights for combating future emergent coronaviruses.

The anti-inflammatory effects of saponins from natural herbs

Inflammation is a protective mechanism that also starts the healing process. However, inflammatory reaction may cause severe tissue damage. The increased influx of phagocytic leukocytes may produce excessive amount of reactive oxygen species, which leads to additional cell injury. Inflammatory response activates the leukocytes and thus induces tissue damage and prolongs inflammation. The inflammation-induced activation of the complement system may also contribute to cell injury. Non-steroidal anti-inflammatory drugs (NSAIDs) and glucocorticoids are chief agents for treating inflammation associated with the diseases. However, the unwanted side effects of NSAIDs (e.g., gastrointestinal disturbances, skin reactions, adverse renal effects, cardiovascular side effects) and glucocorticoids (e.g., suppression of immune system, Cushing's syndrome, osteoporosis, hyperglycemia) limit their use in patients. Natural herbs are important sources of anti-inflammatory drugs. The ingredients extracted from natural herbs display anti-inflammatory effects to work through multiple pathways with lower risk of adverse reaction. At present, the main anti-inflammatory natural agents include saponins, flavonoids, alkaloids, polysaccharides, and so on. The present article will review the anti-inflammatory effects of saponins including escin, ginsenosides, glycyrrhizin, astragaloside, Panax notoginseng saponins, saikosaponin, platycodin, timosaponin, ophiopogonin D, dioscin, senegenin.

Elevated p16Ink4a Expression Enhances Tau Phosphorylation in Neurons Differentiated From Human-Induced Pluripotent Stem Cells

Increased expression of the cyclin-dependent kinase inhibitor p16Ink4a (p16) is detected in neurons of human Alzheimer's disease (AD) brains and during normal aging. Importantly, selective eliminating p16-expressing cells in AD mouse models attenuates tau pathologies and improves cognition. But whether and how p16 contributes to AD pathogenesis remains unclear. To address this question, we tested whether induction of p16 expression in neurons exacerbates AD pathologies. We created a doxycycline-inducible system to trigger p16 up-regulation in human-induced pluripotent stem cells (iPSCs) and neurons differentiated from iPSCs. We demonstrated that up-regulated p16 expression in iPSCs reduces cell proliferation, down-regulates cell cycle genes, and up-regulates genes involved in focal adhesion, interferon α response and PI3K-Akt signaling. Our approach enables temporal control of p16 induction upon differentiation from iPSCs to neurons. In differentiated cortical neurons, we found that up-regulation of p16 increases tau phosphorylation at Ser202/Thr205 and Thr231 in a cell-autonomous manner, while amyloid beta secretion is not affected. These data suggest a critical role of p16 in regulating tau phosphorylation in neurons, and thereby contributing to pathological progression of AD. As pathological tau tangles have been shown to induce p16 expression, our studies suggest a positive feedback loop between p16 and tau to exacerbate tau pathologies.

Targeting CD38 immunometabolic checkpoint improves metabolic fitness and cognition in a mouse model of Alzheimer's disease

Protective immunity, essential for brain maintenance and repair, may be compromised in Alzheimer's disease (AD). Here, using high-dimensional single-cell mass cytometry, we find a unique immunometabolic signature in circulating CD4+ T cells preceding symptom onset in individuals with familial AD, featured by the elevation of CD38 expression. Using female 5xFAD mice, a mouse model of AD, we show that treatment with an antibody directed to CD38 leads to restored metabolic fitness, improved cognitive performance, and attenuated local neuroinflammation. Comprehensive profiling across distinct immunological niches in 5xFAD mice, reveals a high level of disease-associated CD4+ T cells that produce IL-17A in the dural meninges, previously linked to cognitive decline. Targeting CD38 leads to abrogation of meningeal TH17 immunity and cortical IL-1β, breaking the negative feedback loop between these two compartments. Taken together, the present findings suggest CD38 as an immunometabolic checkpoint that could be adopted as a pre-symptomatic biomarker for early diagnosis of AD, and might also be therapeutically targeted alone or in combination with other immunotherapies for disease modification.

Senescent brain cell types in Alzheimer's disease: Pathological mechanisms and therapeutic opportunities

Cellular senescence is a cell state triggered by programmed physiological processes or cellular stress responses. Stress-induced senescent cells often acquire pathogenic traits, including a toxic secretome and resistance to apoptosis. When pathogenic senescent cells form faster than they are cleared by the immune system, they accumulate in tissues throughout the body and contribute to age-related diseases, including neurodegeneration. This review highlights evidence of pathogenic senescent cells in the brain and their role in Alzheimer's disease (AD), the leading cause of dementia in older adults. We also discuss the progress and challenges of senotherapies, pharmacological strategies to clear senescent cells or mitigate their toxic effects, which hold promise as interventions for AD and related dementias (ADRD).

Depletion of senescent cells improves surgery-induced neuroinflammation in aged mice

Aging has been identified as a leading risk factor for many diseases, including neurodegenerative disorders. While cellular senescence has been linked to age-related neurodegenerative conditions, its involvement in peripheral stress-associated brain disorders is just beginning to be explored. In this study, we investigated the impact of senescent cells on peripheral stress-induced neuroinflammation using orthopedic surgery as a model. Our results demonstrate an increased accumulation of senescent cells and neuroinflammation in the aged mouse hippocampus following surgery. Intermittent treatment of the mice with the senolytic drugs dasatinib and quercetin (D/Q) showed a significant reduction in surgery-induced senescent cell burden. This reduction in senescent cell accumulation was correlated with reduced surgery-induced neuroinflammation, as evidenced by decreased glial cell activity. Consistent with these observations, we also observed reduced levels of proinflammatory senescence-associated secretory phenotype factors in circulation, following fracture surgery, in mice treated with D/Q. Overall, our findings underscore the pivotal role of cellular senescence in surgery-induced neuroinflammation and highlight the therapeutic potential of eliminating senescent cells as a potential strategy to manage peripheral stress-induced neuroinflammatory conditions.

Hallmarks of aging and Alzheimer's Disease pathogenesis: Paving the route for new therapeutic targets

Aging is the leading risk factor for Alzheimer's Disease (AD). Understanding the intricate interplay between biological aging and the AD pathophysiology may help to discover innovative treatments. The relationship between aging and core pathways of AD pathogenesis (amyloidopathy and tauopathy) have been extensively studied in preclinical models. However, the potential discordance between preclinical models and human pathology could represent a limitation in the identification of new therapeutic targets. This narrative review aims to gather the evidence currently available on the associations of β-Amyloid and Tau pathology with the hallmarks of aging in human studies. Briefly, our review suggests that while several hallmarks exhibit a robust association with AD pathogenesis (e.g., epigenetic alterations, chronic inflammation, dysbiosis), others (e.g., telomere attrition, cellular senescence, stem cell exhaustion) demonstrate either no relationship or weak associations. This is often due to limitations such as small sample sizes and study designs, being either cross-sectional or with short follow-up intervals, limiting the generalizability of the findings. Distinct hallmarks play varying roles in different stages of AD pathology, emphasizing the need for longitudinal studies with longer follow-up periods. Considering the intricate interconnections across the hallmarks of aging, future research on AD pathology should focus on multiple hallmarks simultaneously.

Stone L, Haglund L. Senolytic treatment for low back pain

Senescent cells (SnCs) accumulate because of aging and external cellular stress throughout the body. They adopt a senescence-associated secretory phenotype (SASP) and release inflammatory and degenerative factors that actively contribute to age-related diseases, such as low back pain (LBP). The senolytics, o-vanillin and RG-7112, remove SnCs in human intervertebral discs (IVDs) and reduce SASP release, but it is unknown whether they can treat LBP. sparc-/- mice, with LBP, were treated orally with o-vanillin and RG-7112 as single or combination treatments. Treatment reduced LBP and SASP factor release and removed SnCs from the IVD and spinal cord. Treatment also lowered degeneration scores in the IVDs, improved vertebral bone quality, and reduced the expression of pain markers in the spinal cord. Together, our data suggest RG-7112 and o-vanillin as potential disease-modifying drugs for LBP and other painful disorders linked to cell senescence.

The role of retinal pigment epithelial senescence and the potential of senotherapeutics in age-related macular degeneration

Age-related macular degeneration (AMD) is a leading cause of visual impairment in the aging population. Evidence showing the presence of cellular senescence in retinal pigment epithelium (RPE) of patients with AMD is growing. Senescent RPE play a pivotal role in its pathogenesis. The senescent RPE suffers from structural and functional alterations and disruption of the surrounding microenvironment due to the development of the senescence-associated secretory phenotype, which contributes to metabolic dysfunctions and inflammatory responses in the retina. Senotherapeutics, including senolytics, senomorphics and others, are novel treatments targeting senescent cells and are promising treatments for AMD. As senotherapeutic targets are being developed, it is promising that the burden of AMD could be decreased.

The relationship mammalian p38 with human health and its homolog Hog1 in response to environmental stresses in Saccharomyces cerevisiae

The mammalian p38 MAPK pathway plays a vital role in transducing extracellular environmental stresses into numerous intracellular biological processes. The p38 MAPK have been linked to a variety of cellular processes including inflammation, cell cycle, apoptosis, development and tumorigenesis in specific cell types. The p38 MAPK pathway has been implicated in the development of many human diseases and become a target for treatment of cancer. Although MAPK p38 pathway has been extensively studied, many questions still await clarification. More comprehensive understanding of the MAPK p38 pathway will provide new possibilities for the treatment of human diseases. Hog1 in S. cerevisiae is the conserved homolog of p38 in mammalian cells and the HOG MAPK signaling pathway in S. cerevisiae has been extensively studied. The deep understanding of HOG MAPK signaling pathway will help provide clues for clarifying the p38 signaling pathway, thereby furthering our understanding of the relationship between p38 and disease. In this review, we elaborate the functions of p38 and the relationship between p38 and human disease. while also analyzing how Hog1 regulates cellular processes in response to environmental stresses. 1, p38 in response to various stresses in mammalian cells.2, The functions of mammalian p38 in human health.3, Hog1 as conserved homolog of p38 in response to environmental stresses in Saccharomyces cerevisiae. 1, p38 in response to various stresses in mammalian cells. 2, The functions of mammalian p38 in human health. 3, Hog1 as conserved homolog of p38 in response to environmental stresses in S. cerevisiae.

The Role of Glial Cell Senescence in Alzheimer's Disease

Glial cell senescence, characterized by the irreversible arrest of cell division and a pro-inflammatory secretory phenotype, has emerged as a critical player in the pathogenesis of Alzheimer's disease (ad). While much attention has been devoted to the role of neurons in ad, growing evidence suggests that glial cells, including astrocytes, microglia, and oligodendrocytes, contribute significantly to disease progression through senescence. In this review, we explore the molecular mechanisms underlying glial cell senescence in ad, focusing on the cellular signaling pathways, including DNA damage response and the accumulation of senescence-associated secretory phenotypes (SASP). We also examine how senescent glial cells exacerbate neuroinflammation, disrupt synaptic function, and promote neuronal death in ad. Moreover, we discuss emerging therapeutic strategies aimed at targeting glial cell senescence to mitigate the neurodegenerative processes in ad. By providing a comprehensive overview of current research on glial cell senescence in Alzheimer's disease, this review highlights its potential as a novel therapeutic target in the fight against ad.

Aging, cellular senescence and Parkinson's disease

Parkinson's disease (PD) is the most common neurodegenerative movement disorder, affecting 1-2% of people over age 65. The risk of developing PD dramatically increases with advanced age, indicating that aging is likely a driving factor in PD neuropathogenesis. Several age-associated biological changes are also hallmarks of PD neuropathology, including mitochondrial dysfunction, oxidative stress, and neuroinflammation. Accumulation of senescent cells is an important feature of aging that contributes to age-related diseases. How age-related cellular senescence affects brain health and whether this phenomenon contributes to neuropathogenesis in PD is not yet fully understood. In this review, we highlight hallmarks of aging, including mitochondrial dysfunction, loss of proteostasis, genomic instability and telomere attrition in relation to well established PD neuropathological pathways. We then discuss the hallmarks of cellular senescence in the context of neuroscience and review studies that directly examine cellular senescence in PD. Studying senescence in PD presents challenges and holds promise for advancing our understanding of disease mechanisms, which could contribute to the development of effective disease-modifying therapeutics. Targeting senescent cells or modulating the senescence-associated secretory phenotype (SASP) in PD requires a comprehensive understanding of the complex relationship between PD pathogenesis and cellular senescence.

The senolytic ABT-263 improves cognitive functions in middle-aged male, but not female, atherosclerotic LDLr-/-;hApoB100+/+ mice

Accumulation of cerebral senescent cells may compromise the continuum between vascular and neuronal function, leading to damage and cognitive decline. Elimination of senescent cells might therefore preserve vascular and neuronal functions. To test this hypothesis, we used male and female atherosclerotic LDLr-/-;hApoB100+/+ mice (ATX-mice), a model of vascular cognitive impairment (VCI), treated with the senolytic ABT-263 for 3 months (3- to 6-month or 9- to 12-month old). In young male ATX mice, prevention with ABT-263 improved spatial retention memory, in association with a higher endothelial sensitivity to shear stress and a higher hippocampal CD31+ endothelial cell density, lower activation of both astrocytes and glial cells. In young females, ABT-263 tended to improve delayed memory; however, atherosclerotic plaque was magnified by ABT-263, endothelial function was unaffected, hippocampal astrocyte activation increased and expression of CD31+ cells decreased. Hence, unlike in males, ABT-263 appears deleterious in young ATX females. In middle-aged males, the curative treatment improved the learning process and memory. Although no change in endothelial function was observed, the benefits of ABT-263 were associated with a decreased expression of several inflammaging markers, a higher density of CD31+ cells and a lower activation of glial cells. In middle-aged females, ABT-263 induced a surge of inflammaging markers, associated with a slower learning process. Altogether, our data demonstrate that ABT-263 differentially affects VCI, improving cognition in male while being deleterious in female ATX mice. More studies are needed to understand the mechanisms at the basis of the sexual dimorphic effects of the senolytic ABT-263.

Electroacupuncture reduces cerebral ischemia-induced neuronal damage in the hippocampal CA1 region in rats by inhibiting HMGB1 and p-JNK overexpression

BACKGROUND

The cornu ammonis 1 (CA1) region of the hippocampus is a sensitive area that is susceptible to injury caused by cerebral ischemia. High-mobility group box 1 (HMGB1) and phosphorylated c-Jun N-terminal kinase (p-JNK) play important roles in mediating cerebral ischemic injury.

OBJECTIVE

To elucidate the mechanism through which electroacupuncture (EA) via the Baihui (GV20) and Zusanli (ST36) acupoints protects neurons.

METHODS

A rat model of permanent middle cerebral artery occlusion (pMCAO) was established. Sprague-Dawley rats were divided into four groups: sham-operated control, pMCAO control, EA, and sham-EA (SEA). In the EA and SEA groups, the GV20 and ST36 acupoints were selected for treatment. However, the SEA group was treated only by superficial pricking of the skin at the two acupoints without the application of electricity. Neurological function was assessed using the neurological deficit function score, and neuronal damage was detected through Nissl staining. HMGB1 and p-JNK expression was evaluated using immunohistochemical staining and western blot assays.

RESULTS

The behavioural experiments showed that the EA treatment improved the neurological deficits in the pMCAO rats. The Nissl staining results revealed that EA reduced neural tissue damage. The immunohistochemical staining and western blot results showed that EA inhibited HMGB1 and p-JNK overexpression. By contrast, none of these EA effects were observed in the SEA group.

CONCLUSION

EA may reduce ischemia-induced neuronal damage in the hippocampal CA1 region by inhibiting the overexpression of both HMGB1 and p-JNK.

Pathophysiological role of high mobility group box-1 signaling in neurodegenerative diseases

Nucleocytoplasmic translocation of HMGB1 (high mobility group box-1) plays a significant role in disease progression. Several methods contribute to the translocation of HMGB1 from the nucleus to the cytoplasm, including inflammasome activation, TNF-α signaling, CRM1-mediated transport, reactive oxygen species (ROS), JAK/STAT pathway, RIP3-mediated p53 involvement, XPO-1-mediated transport, and calcium-dependent mechanisms. Due to its diverse functions at various subcellular locations, HMGB1 has been identified as a crucial factor in several Central Nervous System (CNS) disorders, including Huntington's disease (HD), Parkinson's disease (PD), and Alzheimer's disease (AD). HMGB1 displays a wide array of roles in the extracellular environment as it interacts with several receptors, including CXCR4, TLR2, TLR4, TLR8, and RAGE, by engaging in these connections, HMGB1 can effectively regulate subsequent signaling pathways, hence exerting an impact on the progression of brain disorders through neuroinflammation. Therefore, focusing on treating neuroinflammation could offer a common therapeutic strategy for several disorders. The objective of the current literature is to demonstrate the pathological role of HMGB1 in various neurological disorders. This review also offers insights into numerous therapeutic targets that promise to advance multiple treatments intended to alleviate brain illnesses.

Delta-opioid receptor signaling alleviates neuropathology and cognitive impairment in the mouse model of Alzheimer's disease by regulating microglia homeostasis and inhibiting HMGB1 pathway

BACKGROUND

Recent studies suggest that opioid receptor signaling may differentially affect Alzheimer's disease (AD) pathology and the relevant behavioral dysfunctions. However, the precise roles and mechanisms of opioid receptor subtypes in AD pathologies are still unclear with major controversies.

METHODS

We compared the delta-opioid receptor (DOR)- and mu-opioid receptor (MOR)-mediated effects on AD-associated cognitive deficits, pathologies, neuroinflammations, cell death using transgenic APP/PS1 mouse model and BV2 cell line at behavioral, molecular, and cellular levels. Unpaired t-test and one/two way analysis for variance (ANOVA) were used to analyze statistical significance of the data.

RESULTS

We show a distinct role of DOR and its major difference with MOR in AD injury in an APP/PS1 mouse model. DOR activation by UFP-512, but not MOR activation by DAMGO, attenuated cognitive impairment, reduced beta-amyloid (Aβ) production and aggregation, as well as protected the neurons from apoptosis in APP/PS1 mice. DOR and MOR also differentially modulated microglia in APP/PS1 mice and in vitro AD cell model with a DOR-mediated inhibition on the excessive activation of microglia and the release of pro-inflammatory cytokines in AD pathologies. Gene expression profiling further revealed that the alternations in DOR/MOR are closely associated with microglial homeostatic signatures and high mobility group protein B1 (HMGB1) in AD. DOR activation inhibited HMGB1 secretion and its translocation from nuclear to cytoplasm. Our in-vitro studies further confirmed that DOR overexpression mitigated microglial inflammatory response and rescued neurons from AD injury via HMGB1-NF-κB signaling pathway.

CONCLUSIONS

These novel findings uncover previously unappreciated roles of DOR in neuroprotection against AD injury via modulating microglia-related inflammatory responses.

Targeting secretory autophagy in solid cancers: mechanisms, immune regulation and clinical insights

Secretory autophagy is a classical form of unconventional secretion that integrates autophagy with the secretory process, relying on highly conserved autophagy-related molecules and playing a critical role in tumor progression and treatment resistance. Traditional autophagy is responsible for degrading intracellular substances by fusing autophagosomes with lysosomes. However, secretory autophagy uses autophagy signaling to mediate the secretion of specific substances and regulate the tumor microenvironment (TME). Cytoplasmic substances are preferentially secreted rather than directed toward lysosomal degradation, involving various selective mechanisms. Moreover, substances released by secretory autophagy convey biological signals to the TME, inducing immune dysregulation and contributing to drug resistance. Therefore, elucidating the mechanisms underlying secretory autophagy is essential for improving clinical treatments. This review systematically summarizes current knowledge of secretory autophagy, from initiation to secretion, considering inter-tumor heterogeneity, explores its role across different tumor types. Furthermore, it proposes future research directions and highlights unresolved clinical challenges.

Alzheimer's disease: insights into pathology, molecular mechanisms, and therapy

Alzheimer's disease (AD), the leading cause of dementia, is characterized by the accumulation of amyloid plaques and neurofibrillary tangles in the brain. This condition casts a significant shadow on global health due to its complex and multifactorial nature. In addition to genetic predispositions, the development of AD is influenced by a myriad of risk factors, including aging, systemic inflammation, chronic health conditions, lifestyle, and environmental exposures. Recent advancements in understanding the complex pathophysiology of AD are paving the way for enhanced diagnostic techniques, improved risk assessment, and potentially effective prevention strategies. These discoveries are crucial in the quest to unravel the complexities of AD, offering a beacon of hope for improved management and treatment options for the millions affected by this debilitating disease.

The Biological Intersection Between Chemotherapy-Related Cognitive Impairment and Alzheimer Disease

Alzheimer disease (AD) is the most common type of dementia and one of the leading causes of death in elderly patients. The number of patients with AD in the United States is projected to double by 2060. Thus, understanding modifiable risk factors for AD is an urgent public health priority. In parallel with the number of patients with AD, the number of cancer survivors is estimated to increase significantly, and up to 80% of cancer patients treated with chemotherapy will develop cognitive deficits, termed chemotherapy-related cognitive impairment. This review discusses biologically plausible pathways underlying both disorders, with the goal of understanding why a proportion of chemotherapy patients may be at higher risk of developing AD. Highlighted are the E4 allele of the apolipoprotein E gene, neuroinflammation, oxidative stress, DNA damage, mitochondrial dysfunction, neuronal and synaptic loss, cellular senescence, brain-derived neurotrophic factor signaling, white matter damage, blood-brain barrier/vascular dysfunction, tau pathology, and transposable element reactivation.

Know your brain aging to know your resilience in neurodegenerative diseases

This scientific commentary refers to 'Brain aging rejuvenation factors in adults with genetic and sporadic neurodegenerative disease', by Casaletto et al. (https://doi.org/10.1093/braincomms/fcae432).

A Review of Telomere Attrition in Cancer and Aging: Current Molecular Insights and Future Therapeutic Approaches

BACKGROUND/OBJECTIVES

As cells divide, telomeres shorten through a phenomenon known as telomere attrition, which leads to unavoidable senescence of cells. Unprotected DNA exponentially increases the odds of mutations, which can evolve into premature aging disorders and tumorigenesis. There has been growing academic and clinical interest in exploring this duality and developing optimal therapeutic strategies to combat telomere attrition in aging and cellular immortality in cancer. The purpose of this review is to provide an updated overview of telomere biology and therapeutic tactics to address aging and cancer.

METHODS

We used the Rayyan platform to review the PubMed database and examined the ClinicalTrial.gov registry to gain insight into clinical trials and their results.

RESULTS

Cancer cells activate telomerase or utilize alternative lengthening of telomeres to escape telomere shortening, leading to near immortality. Contrarily, normal cells experience telomeric erosion, contributing to premature aging disorders, such as Werner syndrome and Hutchinson-Gilford Progeria, and (2) aging-related diseases, such as neurodegenerative and cardiovascular diseases.

CONCLUSIONS

The literature presents several promising therapeutic approaches to potentially balance telomere maintenance in aging and shortening in cancer. This review highlights gaps in knowledge and points to the potential of these optimal interventions in preclinical and clinical studies to inform future research in cancer and aging.

Roles of the Receptor for Advanced Glycation End Products and Its Ligands in the Pathogenesis of Alzheimer's Disease

The Receptor for Advanced Glycation End Products (RAGE), part of the immunoglobulin superfamily, plays a significant role in various essential functions under both normal and pathological conditions, especially in the progression of Alzheimer's disease (AD). RAGE engages with several damage-associated molecular patterns (DAMPs), including advanced glycation end products (AGEs), beta-amyloid peptide (Aβ), high mobility group box 1 (HMGB1), and S100 calcium-binding proteins. This interaction impairs the brain's ability to clear Aβ, resulting in increased Aβ accumulation, neuronal injury, and mitochondrial dysfunction. This further promotes inflammatory responses and oxidative stress, ultimately leading to a range of age-related diseases. Given RAGE's significant role in AD, inhibitors that target RAGE and its ligands hold promise as new strategies for treating AD, offering new possibilities for alleviating and treating this serious neurodegenerative disease. This article reviews the various pathogenic mechanisms of AD and summarizes the literature on the interaction between RAGE and its ligands in various AD-related pathological processes, with a particular focus on the evidence and mechanisms by which RAGE interactions with AGEs, HMGB1, Aβ, and S100 proteins induce cognitive impairment in AD. Furthermore, the article discusses the principles of action of RAGE inhibitors and inhibitors targeting RAGE-ligand interactions, along with relevant clinical trials.

High mobility group box 1 in the central nervous system: regeneration hidden beneath inflammation

High-mobility group box 1 was first discovered in the calf thymus as a DNA-binding nuclear protein and has been widely studied in diverse fields, including neurology and neuroscience. High-mobility group box 1 in the extracellular space functions as a pro-inflammatory damage-associated molecular pattern, which has been proven to play an important role in a wide variety of central nervous system disorders such as ischemic stroke, Alzheimer's disease, frontotemporal dementia, Parkinson's disease, multiple sclerosis, epilepsy, and traumatic brain injury. Several drugs that inhibit high-mobility group box 1 as a damage-associated molecular pattern, such as glycyrrhizin, ethyl pyruvate, and neutralizing anti-high-mobility group box 1 antibodies, are commonly used to target high-mobility group box 1 activity in central nervous system disorders. Although it is commonly known for its detrimental inflammatory effect, high-mobility group box 1 has also been shown to have beneficial pro-regenerative roles in central nervous system disorders. In this narrative review, we provide a brief summary of the history of high-mobility group box 1 research and its characterization as a damage-associated molecular pattern, its downstream receptors, and intracellular signaling pathways, how high-mobility group box 1 exerts the repair-favoring roles in general and in the central nervous system, and clues on how to differentiate the pro-regenerative from the pro-inflammatory role. Research targeting high-mobility group box 1 in the central nervous system may benefit from differentiating between the two functions rather than overall suppression of high-mobility group box 1.

Excessive Alcohol Use as a Risk Factor for Alzheimer's Disease: Epidemiological and Preclinical Evidence

Alcohol use has recently emerged as a modifiable risk factor for Alzheimer's disease (AD). However, the neurobiological mechanisms by which alcohol interacts with AD pathogenesis remain poorly understood. In this chapter, we review the epidemiological and preclinical support for the interaction between alcohol use and AD. We hypothesize that alcohol use increases the rate of accumulation of specific AD-relevant pathologies during the prodromal phase and exacerbates dementia onset and progression. We find that alcohol consumption rates are increasing in adolescence, middle age, and aging populations. In tandem, rates of AD are also on the rise, potentially as a result of this increased alcohol use throughout the lifespan. We then review the biological processes in common between alcohol use disorder and AD as a means to uncover potential mechanisms by which they interact; these include oxidative stress, neuroimmune function, metabolism, pathogenic tauopathy development and spread, and neuronal excitatory/inhibitory balance (EIB). Finally, we provide some forward-thinking suggestions we believe this field should consider. In particular, the inclusion of alcohol use assessments in longitudinal studies of AD and more preclinical studies on alcohol's impacts using better animal models of late-onset Alzheimer's disease (LOAD).

The therapeutic potential of glycyrrhizic acid and its metabolites in neurodegenerative diseases: Evidence from animal models

Neurodegenerative diseases, mostly occurring in the elderly population, are the significant cause of disability and death worldwide. The pathogenesis of neurodegenerative diseases is still largely unknown yet, although they have been continuously explored. Thus, there is still a lack of safe, effective, and low side effect drugs in clinical practice for the treatment of neurodegenerative diseases. Pieces of accumulating evidence have demonstrated that licorice played neuroprotective roles in various neurodegenerative diseases. In the past two decades, increasing studies have indicated that glycyrrhizic acid (GL), the main active ingredient from traditional Chinese medicine licorice (widely used in the food industry) and a triterpenoid saponin with multiple pharmacological effects (such as anti-oxidant, anti-inflammatory, and immune regulation), and its metabolites (glycyrrhetinic acid and carbenoxolone) play a neuroprotective role in a range of neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, Huntington's disease and epilepsy. This review will elaborate on the multiple neuroprotective mechanisms of GL and its metabolites in this series of diseases, aiming to provide a basis for further research on these protective drugs for neurodegenerative diseases and their clinical application. In summary, GL may be a promising candidate drug for the therapy of neurodegenerative diseases.

SenNet recommendations for detecting senescent cells in different tissues

Once considered a tissue culture-specific phenomenon, cellular senescence has now been linked to various biological processes with both beneficial and detrimental roles in humans, rodents and other species. Much of our understanding of senescent cell biology still originates from tissue culture studies, where each cell in the culture is driven to an irreversible cell cycle arrest. By contrast, in tissues, these cells are relatively rare and difficult to characterize, and it is now established that fully differentiated, postmitotic cells can also acquire a senescence phenotype. The SenNet Biomarkers Working Group was formed to provide recommendations for the use of cellular senescence markers to identify and characterize senescent cells in tissues. Here, we provide recommendations for detecting senescent cells in different tissues based on a comprehensive analysis of existing literature reporting senescence markers in 14 tissues in mice and humans. We discuss some of the recent advances in detecting and characterizing cellular senescence, including molecular senescence signatures and morphological features, and the use of circulating markers. We aim for this work to be a valuable resource for both seasoned investigators in senescence-related studies and newcomers to the field.

HMGB1, an evolving pleiotropic protein critical for cellular and tissue homeostasis: Role in aging and age-related diseases

Aging is a universal biological process characterized by a progressive, cumulative decline in homeostatic capabilities and physiological functions, which inevitably increases vulnerability to diseases. A number of molecular pathomechanisms and hallmarks of aging have been recognized, yet we miss a thorough understanding of their complex interconnectedness. This review explores the molecular and cellular mechanisms underlying human aging, with a focus on the multiple roles of high mobility group Box 1 protein (HMGB1), the archetypal damage-associated molecular pattern (DAMP) molecule. In the nucleus, this non-histone chromatin-associated protein functions as a DNA chaperone and regulator of gene transcription, influencing DNA structure and gene expression. Moreover, this versatile protein can translocate to the cytoplasm to orchestrate other processes, such as autophagy, or be unconventionally secreted into the extracellular environment, where it acts as a DAMP, combining inflammatory and regenerative properties. Notably, lower expression of HMGB1 within the cell and its heightened extracellular release have been associated with diverse age-associated traits, making it a suitable candidate as a universal biomarker of aging. In this review, we outline the evidence implicating HMGB1 in aging, also in light of an evolutionary perspective on its functional pleiotropy, and propose critical issues that need to be addressed to gauge the value of HMGB1 as a potential biomarker across age-related diseases and therapeutic target to promote healthy longevity.

Defining and characterizing neuronal senescence, 'neurescence', as GX arrested cells

Cellular senescence is a cell state characterized by resistance to apoptosis and stable cell cycle arrest. Senescence was first observed in mitotic cells in vitro. Recent evidence from in vivo studies and human tissue indicates that postmitotic cells, including neurons, may also become senescent. The quiescent cell state of neurons and inconsistent descriptions of neuronal senescence across studies, however, have caused confusion in this burgeoning field. We summarize evidence demonstrating that exit from G0 quiescence may protect neurons against apoptosis and predispose them toward senescence. Additionally, we propose the term 'neurescent' for senescent neurons and introduce the cell state, GX, to describe cell cycle arrest achieved by passing through G0 quiescence. Criteria are provided to identify neurescent cells, distinguish them from G0 quiescent neurons, and compare neurescent phenotypes with classic replicative senescence.

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.

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.

Integrated single-cell and bulk RNA sequencing reveals immune-related SPP1+ macrophages as a potential strategy for predicting the prognosis and treatment of liver fibrosis and hepatocellular carcinoma

Background

Liver fibrosis is a pathological response to liver damage induced by multiple etiologies including NASH and CCl4, which may further lead to cirrhosis and hepatocellular carcinoma (HCC). Despite the increasing understanding of liver fibrosis and HCC, clinical prognosis and targeted therapy remain challenging.

Methods

This study integrated single-cell sequencing analysis, bulk sequencing analysis, and mouse models to identify highly expressed genes, cell subsets, and signaling pathways associated with liver fibrosis and HCC. Clinical prediction models and prognostic genes were established and verified through machine learning, survival analysis, as well as the utilization of clinical data and tissue samples from HCC patients. The expression heterogeneity of the core prognostic gene, along with its correlation with the tumor microenvironment and prognostic outcomes, was analyzed through single-cell analysis and immune infiltration analysis. In addition, the cAMP database and molecular docking techniques were employed to screen potential small molecule drugs for the treatment of liver fibrosis and HCC.

Result

We identified 40 pathogenic genes, 15 critical cell subsets (especially Macrophages), and regulatory signaling pathways related to cell adhesion and the actin cytoskeleton that promote the development of liver fibrosis and HCC. In addition, 7 specific prognostic genes (CCR7, COL3A1, FMNL2, HP, PFN1, SPP1 and TENM4) were identified and evaluated, and expression heterogeneity of core gene SPP1 and its positive correlation with immune infiltration and prognostic development were interpreted. Moreover, 6 potential small molecule drugs for the treatment of liver fibrosis and HCC were provided.

Conclusion

The comprehensive investigation, based on a bioinformatics and mouse model strategy, may identify pathogenic genes, cell subsets, regulatory mechanisms, prognostic genes, and potential small molecule drugs, thereby providing valuable insights into the clinical prognosis and targeted treatment of liver fibrosis and HCC.

The Mechanistic Link Between Tau-Driven Proteotoxic Stress and Cellular Senescence in Alzheimer's Disease

In Alzheimer's disease (AD), tau dissociates from microtubules (MTs) due to hyperphosphorylation and misfolding. It is degraded by various mechanisms, including the 20S proteasome, chaperone-mediated autophagy (CMA), 26S proteasome, macroautophagy, and aggrephagy. Neurofibrillary tangles (NFTs) form upon the impairment of aggrephagy, and eventually, the ubiquitin chaperone valosin-containing protein (VCP) and heat shock 70 kDa protein (HSP70) are recruited to the sites of NFTs for the extraction of tau for the ubiquitin-proteasome system (UPS)-mediated degradation. However, the impairment of tau degradation in neurons allows tau to be secreted into the extracellular space. Secreted tau can be monomers, oligomers, and paired helical filaments (PHFs), which are seeding competent pathological tau that can be endocytosed/phagocytosed by healthy neurons, microglia, astrocytes, oligodendrocyte progenitor cells (OPCs), and oligodendrocytes, often causing proteotoxic stress and eventually triggers senescence. Senescent cells secrete various senescence-associated secretory phenotype (SASP) factors, which trigger cellular atrophy, causing decreased brain volume in human AD. However, the molecular mechanisms of proteotoxic stress and cellular senescence are not entirely understood and are an emerging area of research. Therefore, this comprehensive review summarizes pertinent studies that provided evidence for the sequential tau degradation, failure, and the mechanistic link between tau-driven proteotoxic stress and cellular senescence in AD.

Paeonol and glycyrrhizic acid in combination ameliorate the recurrent nitroglycerin-induced migraine-like phenotype in rats by regulating the GABBR2/TRPM8/PRKACA/TRPV1 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Paeonol (PAE) and glycyrrhizic acid (GLY) are predominate components of 14 blood-entering ones of Piantongtang No. 1, which is a traditional Chinese medicine prescription for chronic migraine with minimal side effects. Both paeonol and glycyrrhizic acid exhibit analgesic, neuroprotective and anti-inflammatory properties individually. Our previous research has highlighted their combined effect (PAE + GLY) in ameliorating migraine symptoms. However, there are not yet any studies exploring the mechanism of action of PAE + GLY in the treatment of migraine.

AIM OF THE STUDY

This research aimed to determine the mechanism of PAE + GLY in ameliorating the recurrent nitroglycerin-induced migraine-like phenotype in rats.

MATERIALS AND METHODS

Using a nitroglycerin-induced migraine model via subcutaneous injection in the neck, we evaluated the effect of PAE + GLY on migraine-like symptoms. Behavioural tests and biomarkers analysis were employed, alongside transcriptome sequencing (RNA-seq). Mechanistic insights were further verified utilising reverse transcription quantitative PCR (RT-qPCR), Western blot (WB), ELISA and immunofluorescence (IF) techniques.

RESULTS

Following treatment with PAE + GLY, hyperalgesia threshold and 5-hydroxytryptamine (5-HT) levels increased, and migraine-like head scratching, histamine and calcitonin gene-related peptide (CGRP) levels were reduced. RNA-Seq experiments revealed that PAE + GLY upregulated the expression of Glutamate decarboxylase 2 (GAD2) and γ-aminobutyric acid type B receptor subunit 2 (GABBR2) genes. This upregulation activated the GABAergic synapse pathway, effectively inhibiting migraine attacks. Further validation demonstrated an increase in γ-aminobutyric acid (GABA) content in cerebrospinal fluid post PAE + GLY treatment, coupled with increased expression of dural GAD2, GABBR2 and transient receptor potential channel M8 (TRPM8). Consequently, this inhibited the expression of dural cAMP-dependent protein kinase catalytic subunit alpha (PRKACA) and transient receptor potential channel type 1 (TRPV1), subsequently downregulating p-ERK1/2, p-AKT1, IL-1β and TNF-α.

CONCLUSIONS

Our findings underscore that PAE + GLY ameliorates inflammatory hyperalgesia migraine by upregulating inhibitory neurotransmitters and modulating the GABBR2/TRPM8/PRKACA/TRPV1 pathway.

Glial fibrillary acidic protein in Alzheimer's disease: a narrative review

Astrocytes are fundamental in neural functioning and homeostasis in the central nervous system. These cells respond to injuries and pathological conditions through astrogliosis, a reactive process associated with neurodegenerative diseases such as Alzheimer's disease. This process is thought to begin in the early stages of these conditions. Glial fibrillary acidic protein (GFAP), a type III intermediate filament protein predominantly expressed in astrocytes, has emerged as a key biomarker for monitoring this response. During astrogliosis, GFAP is released into biofluids, making it a candidate for non-invasive diagnosis and tracking of neurodegenerative diseases. Growing evidence positions GFAP as a biomarker for Alzheimer's disease with specificity and disease-correlation characteristics comparable to established clinical markers, such as Aβ peptides and phosphorylated tau protein. To improve diagnostic accuracy, particularly in the presence of confounders and comorbidities, incorporating a panel of biomarkers may be advantageous. This review will explore the potential of GFAP within such a panel, examining its role in early diagnosis, disease progression monitoring and its integration into clinical practice for Alzheimer's disease management.

Therapeutic targeting of senescent cells in the CNS

Senescent cells accumulate throughout the body with advanced age, diseases and chronic conditions. They negatively impact health and function of multiple systems, including the central nervous system (CNS). Therapies that target senescent cells, broadly referred to as senotherapeutics, recently emerged as potentially important treatment strategies for the CNS. Promising therapeutic approaches involve clearing senescent cells by disarming their pro-survival pathways with 'senolytics'; or dampening their toxic senescence-associated secretory phenotype (SASP) using 'senomorphics'. Following the pioneering discovery of first-generation senolytics dasatinib and quercetin, dozens of additional therapies have been identified, and several promising targets are under investigation. Although potentially transformative, senotherapies are still in early stages and require thorough testing to ensure reliable target engagement, specificity, safety and efficacy. The limited brain penetrance and potential toxic side effects of CNS-acting senotherapeutics pose challenges for drug development and translation to the clinic. This Review assesses the potential impact of senotherapeutics for neurological conditions by summarizing preclinical evidence, innovative methods for target and biomarker identification, academic and industry drug development pipelines and progress in clinical trials.

DAMPs in immunosenescence and cancer

Damage-associated molecular patterns (DAMPs) are endogenous molecules released by cells in response to injury or stress, recognized by host pattern recognition receptors that assess the immunological significance of cellular damage. The interaction between DAMPs and innate immune receptors triggers sterile inflammation, which serves a dual purpose: promoting tissue repair and contributing to pathological conditions, including age-related diseases. Chronic inflammation mediated by DAMPs accelerates immunosenescence and influences both tumor progression and anti-tumor immunity, underscoring the critical role of DAMPs in the nexus between aging and cancer. This review explores the characteristics of immunosenescence and its impact on age-related cancers, investigates the various types of DAMPs, their release mechanisms during cell death, and the immune activation pathways they initiate. Additionally, we examine the therapeutic potential of targeting DAMPs in age-related diseases. A detailed understanding of DAMP-induced signal transduction could provide critical insights into immune regulation and support the development of innovative therapeutic strategies.

Senoinflammation as the underlying mechanism of aging and its modulation by calorie restriction

Senoinflammation is characterized by an unresolved low-grade inflammatory process that affects multiple organs and systemic functions. This review begins with a brief overview of the fundamental concepts and frameworks of senoinflammation. It is widely involved in the aging of various organs and ultimately leads to progressive systemic degeneration. Senoinflammation underlying age-related inflammation, is causally related to metabolic dysregulation and the formation of senescence-associated secretory phenotype (SASP) during aging and age-related diseases. This review discusses the biochemical evidence and molecular biology data supporting the concept of senoinflammation and its regulatory processes, highlighting the anti-aging and anti-inflammatory effects of calorie restriction (CR). Experimental data from CR studies demonstrated effective suppression of various pro-inflammatory cytokines and chemokines, lipid accumulation, and SASP during aging. In conclusion, senoinflammation represents the basic mechanism that creates a microenvironment conducive to aging and age-related diseases. Furthermore, it serves as a potential therapeutic target for mitigating aging and age-related diseases.

Serum HMGB-1 released by ferroptosis and necroptosis as a novel potential biomarker for systemic lupus erythematosus

High mobility group box proterin-1 (HMGB-1) is a multifunctional protein that can be released by various programmed cell deaths (PCDs), such as necroptosis and ferroptosis. PCDs play a critical role in the pathogenesis of systemic lupus erythematosus (SLE). However, the role of HMGB-1 in the process of SLE remains unclear. This study aims to demonstrate the potential diagnosing role of serum HMGB-1 in SLE that released by necroptosis and ferroptosis. We found that the serum levels of HMGB-1, receptor-interacting protein kinase 3 (RIPK3) /mixed lineage kinase domain-like protein (MLKL) related with necroptosis, and metabolites associated with ferroptosis were significantly upregulated in SLE patients compared to HC individuals. These serum levels were positively correlated with SLE disease activity. Additionally, the serum level of HMGB-1 showed a strong positive correlated with the levels of RIPK3/MLKL and ferroptosis metabolites. Moreover, the serum level of HMGB-1 was correlated with renal involvement and high-antinuclear antibodies (ANA) titer. After SLE serum and interferon γ (IFN-γ) treatment in vitro, the level of necroptosis and ferroptosis markers were activated and HMGB1 was released both in HEK293 and HK2 cells. Clinically, HMGB-1 was considered as a significant independent risk factor in SLE serum by binary logistic assay. Notably, HMGB-1 exhibited outstanding diagnostic ability for SLE by the area under the curve (AUC) in receiver operating characteristic (ROC) curve analysis. Taken together, our study indicates that the serum level of HMGB-1 is a promising biomarker for the diagnosis and monitoring of SLE.

The role of high mobility group proteins in cellular senescence mechanisms

Aging is a universal physiological phenomenon, and chronic age-related diseases have become one of the leading causes of human mortality, accounting for nearly half of all deaths. Studies have shown that reducing the incidence of these diseases can not only extend lifespan but also promote healthy aging. In recent years, the potential role of non-histone high-mobility group proteins (HMGs) in the regulation of aging and lifespan has attracted widespread attention. HMGs play critical roles in cellular senescence and associated diseases through various pathways, encompassing multi-layered mechanisms involving protein interactions, molecular regulation, and chromatin dynamics. This review provides a comprehensive analysis of the interactions between HMG family proteins and senescence-associated secretory phenotype (SASP), chromatin structure, and histone modifications, offering a deeper exploration of the pivotal functions and impacts of HMGs in the aging process. Furthermore, we summarize recent findings on the contributions of HMG proteins to aging and age-related diseases. HMG proteins not only regulate senescence-associated inflammation through modulating the SASP but also influence genomic stability and cell fate decisions via interactions with chromatin and histones. Targeting HMG proteins holds great potential in delaying the progression of aging and its associated diseases. This review aims to provide a systematic overview of HMG proteins' roles in aging and to lay a solid foundation for future anti-aging drug development and therapeutic strategies. With the advancing understanding of the mechanisms by which HMGs regulate aging, developing therapeutic interventions targeting HMGs may emerge as a promising approach to extending lifespan and enhancing healthspan.

The impact of neuroinflammation on neuronal integrity

Neuroinflammation, characterized by a complex interplay among innate and adaptive immune responses within the central nervous system (CNS), is crucial in responding to infections, injuries, and disease pathologies. However, the dysregulation of the neuroinflammatory response could significantly affect neurons in terms of function and structure, leading to profound health implications. Although tremendous progress has been made in understanding the relationship between neuroinflammatory processes and alterations in neuronal integrity, the specific implications concerning both structure and function have not been extensively covered, with the exception of perspectives on glial activation and neurodegeneration. Thus, this review aims to provide a comprehensive overview of the multifaceted interactions among neurons and key inflammatory players, exploring mechanisms through which inflammation influences neuronal functionality and structural integrity in the CNS. Further, it will discuss how these inflammatory mechanisms lead to impairment in neuronal functions and architecture and highlight the consequences caused by dysregulated neuronal functions, such as cognitive dysfunction and mood disorders. By integrating insights from recent research findings, this review will enhance our understanding of the neuroinflammatory landscape and set the stage for future interventions that could transform current approaches to preserve neuronal integrity and function in CNS-related inflammatory conditions.

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.

Diverse signaling mechanisms and heterogeneity of astrocyte reactivity in Alzheimer's disease

Alzheimer's disease (AD) affects various brain cell types, including astrocytes, which are the most abundant cell types in the central nervous system (CNS). Astrocytes not only provide homeostatic support to neurons but also actively regulate synaptic signaling and functions and become reactive in response to CNS insults through diverse signaling pathways including the JAK/STAT, NF-κB, and GPCR-elicited pathways. The advent of new technology for transcriptomic profiling at the single-cell level has led to increasing recognition of the highly versatile nature of reactive astrocytes and the context-dependent specificity of astrocyte reactivity. In AD, reactive astrocytes have long been observed in senile plaques and have recently been suggested to play a role in AD pathogenesis and progression. However, the precise contributions of reactive astrocytes to AD remain elusive, and targeting this complex cell population for AD treatment poses significant challenges. In this review, we summarize the current understanding of astrocyte reactivity and its role in AD, with a particular focus on the signaling pathways that promote astrocyte reactivity and the heterogeneity of reactive astrocytes. Furthermore, we explore potential implications for the development of therapeutics for AD. Our objective is to shed light on the complex involvement of astrocytes in AD and offer insights into potential therapeutic targets and strategies for treating and managing this devastating neurodegenerative disorder.

High mobility group box-1 protein promotes astrocytic CCL5 production through the MAPK/NF-κB pathway following spinal cord injury

Astrocytes act as immune cells that can produce a series of chemokines to attract large numbers of leucocytes to the lesion site, where they contribute to excessive inflammation following spinal cord injury (SCI). However, the relevant regulatory mechanism involved in chemokine production by astrocytes has not been fully elucidated. In the present study, we examined the correlation between C-C motif chemokine ligand 5 (CCL5) and high mobility group box-1 protein (HMGB1) in a T8-T10 spinal cord contusion model. Our results revealed that SCI-induced CCL5 protein levels increased synchronously with the increase in HMGB1. Administration of an HMGB1-neutralizing antibody significantly reduced the protein expression of CCL5 in the context of SCI. An in vitro study revealed that HMGB1 binding with TLR2/4 receptors potently facilitates the production of CCL5 by astrocytes by activating the intracellular ERK/JNK-mediated NF-κB pathway. Furthermore, the HMGB1-induced release of CCL5 from astrocytes is involved in promoting microglia/macrophage accumulation and M1 polarization. The inhibition of HMGB1 activity reduces microglia/macrophage infiltration by decreasing the expression of CCL5 and improves motor functional recovery following SCI. Our results provide insights into the new functions of HMGB1-mediated astrocytic CCL5 production, which elicits inflammatory cell recruitment to the site of injury; this recruitment is associated with excessive inflammation activation. These data may provide a new therapeutic strategy for central nervous system (CNS) inflammation.

Antineoplastics for treating Alzheimer's disease and dementia: Evidence from preclinical and observational studies

As the world population ages, there will be an increasing need for effective therapies for aging-associated neurodegenerative disorders, which remain untreatable. Dementia due to Alzheimer's disease (AD) is one of the leading neurological diseases in the aging population. Current therapeutic approaches to treat this disorder are solely symptomatic, making the need for new molecular entities acting on the causes of the disease extremely urgent. One of the potential solutions is to use compounds that are already in the market. The structures have known pharmacokinetics, pharmacodynamics, toxicity profiles, and patient data available in several countries. Several drugs have been used successfully to treat diseases different from their original purposes, such as autoimmunity and peripheral inflammation. Herein, we divulge the repurposing of drugs in the area of neurodegenerative diseases, focusing on the therapeutic potential of antineoplastics to treat dementia due to AD and dementia. We briefly touch upon the shared pathological mechanism between AD and cancer and drug repurposing strategies, with a focus on artificial intelligence. Next, we bring out the current status of research on the development of drugs, provide supporting evidence from retrospective, clinical, and preclinical studies on antineoplastic use, and bring in new areas, such as repurposing drugs for the prion-like spreading of pathologies in treating AD.