Alzheimer's disease pathology propagation by exosomes containing toxic amyloid-beta oligomers

Exploring Exosome-Based Approaches for Early Diagnosis and Treatment of Neurodegenerative Diseases

Neurodegenerative diseases (NDs), like Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and Amyotrophic Lateral Sclerosis (ALS), present an increasingly significant global health burden, primarily due to the lack of effective early diagnostic tools and treatments. Exosomes-nano-sized extracellular vesicles secreted by nearly all cell types-have emerged as promising candidates for both biomarkers and therapeutic agents in NDs. This review examines the biogenesis, molecular composition, and diverse functions of exosomes in NDs. Exosomes play a crucial role in mediating intercellular communication. They are capable of reflecting the biochemical state of their parent cells and have the ability to cross the blood-brain barrier (BBB). In doing so, they facilitate the propagation of pathological proteins, such as amyloid-beta (Aβ), tau, and alpha-synuclein (α-syn), while also enabling the targeted delivery of neuroprotective compounds. Recent advancements in exosome isolation and engineering have opened up new possibilities for diagnostic and therapeutic strategies. These range from the discovery of non-invasive biomarkers to innovative approaches in gene therapy and drug delivery systems. However, challenges related to standardization, safety, and long-term effects must be addressed before exosomes can be translated into clinical applications. This review highlights both the promising potential and the obstacles that must be overcome to leverage exosomes in the treatment of NDs and the transformation of personalized medicine.

The Vicious Consequences of Chronic Kidney Disease on Cognitive Impairment and Alzheimer's Disease

Chronic kidney disease (CKD) and Alzheimer's disease (AD) are two prevalent and debilitating conditions that frequently coexist, with CKD contributing to cognitive decline and potentially exacerbating AD pathology. In CKD, irreversible changes in the structure or function of the kidneys are observed, while AD is primarily marked by amyloid deposition and tau pathology. Both conditions involve complex and multifactorial pathophysiology affecting brain functioning, highlighting the need for comprehensive research to understand their potential crosstalk. This review articulates the possible molecular mechanisms underlying both diseases, focusing on key pathways, including oxidative stress, inflammation, vascular dysfunction, hypertension, and uremic toxin accumulation. These interconnected mechanisms suggest a potential bidirectional relationship where kidney dysfunction accelerates cognitive decline and vice versa. Additionally, we examine critical risk factors implicated in both CKD and AD, for instance, vitamin D deficiency, erythropoietin dysregulation, endothelin action, klotho gene expression, and the role of the extracellular vesicle, which may influence disease progression through their effects on the kidney and brain, influencing cognitive function. Further, we emphasized potential biomarkers that could aid in diagnosing and monitoring disease progression in these comorbid conditions, like amyloid beta, tau, homocysteine, cystatin C, creatinine, proteinuria, and estimated glomerular filtration rate. Lastly, the review highlights treatment strategies for managing CKD and AD concurrently, focusing on therapeutic approaches that address common pathophysiological mechanisms. These strategies not only aim to address the underlying causes of both conditions but also offer the potential to slow or even prevent the progression of cognitive impairment. Moreover, we recommend further research to refine these approaches, execute correlational studies on disease progression, and design clinical trials that address both conditions, aiming to establish effective, tailored treatments for this dual burden of disease.

Neuron-Derived Extracellular Vesicles: Emerging Regulators in Central Nervous System Disease Progression

The diagnosis and exploration of central nervous system (CNS) diseases remain challenging due to the blood-brain barrier (BBB), complex signaling pathways, and heterogeneous clinical manifestations. Neurons, as the core functional units of the CNS, play a pivotal role in CNS disease progression. Extracellular vesicles (EVs), capable of crossing the BBB, facilitate intercellular and cell-extracellular matrix (ECM) communication, making neuron-derived extracellular vesicles (NDEVs) a focal point of research. Recent studies reveal that NDEVs, carrying various bioactive substances, can exert either pathogenic or protective effects in numerous CNS diseases. Additionally, NDEVs show significant potential as biomarkers for CNS diseases. This review summarizes the emerging roles of NDEVs in CNS diseases, including Alzheimer's disease, depression, traumatic brain injury, schizophrenia, ischemic stroke, Parkinson's disease, amyotrophic lateral sclerosis, and multiple sclerosis. It aims to provide a novel perspective on developing therapeutic and diagnostic strategies for CNS diseases through the study of NDEVs.

[18F]flutemetamol uptake in the colon of a memory clinic population and its association with brain amyloidosis and the gut microbiota profile: an exploratory study

PURPOSE

Some Alzheimer's disease (AD) patients report gastro-intestinal symptoms and present alterations in the gut microbiota (GM) composition. Elevated colonic amyloid immunoreactivity has been shown in patients and animal models. We evaluated the colonic uptake of the amyloid positron emission tomography (PET) imaging agent [18F]flutemetamol (FMM) in a memory clinic population and investigated its association with brain amyloidosis and GM composition.

METHODS

Forty-five participants underwent (i) abdominal and cerebral FMM PET, acquired at 40 (early phase) and 120 min (late phase) after tracer injection, (ii) abdominal computed tomography, and (iii) cerebral T1-weighted MRI. Colonic standardized uptake value ratio (SUVr) was determined through manual tracing and automatic segmentation (TotalSegmentator), using the aortic blood signal as a reference region. Fecal GM composition was assessed using 16 S rRNA sequencing. Amyloid positive (A+) and negative (A-) participants, based on cortical FMM quantification (PetSurfer), were compared in terms of SUVr and GM features.

RESULTS

Increased colonic early SUVr was reported in A+ than A- (manual, p =.008; automated, p =.035). Altered GM composition was found in A + as shown by lower Pielou's evenness (p =.023), lower abundance of Eubacterium hallii group, and higher abundance of several genera. High UC5-1-2E3 abundance positively correlated with high colonic early SUVr (whole group: manual, p =.012, automated, p =.082; A+: manual, p =.074; automated, p =.016).

CONCLUSION

This exploratory study showed that subjects with cerebral amyloidosis have greater colonic FMM uptake than subjects with normal cerebral amyloid load, correlating with altered GM composition. Further analysis is needed to determine if these changes denote amyloid-related changes or other phenomena.

Monitoring neurodegeneration through brain-derived extracellular vesicles in biofluids

The identification of neurodegenerative disease (ND) biomarkers in easily accessible body fluids is crucial in the fight against this class of disorders. Brain-derived extracellular vesicles (BDEVs) have gained attention as nanoscale carriers of molecular information and bioactive molecules that reflect the status of their source cells. By crossing the blood-brain barrier (BBB), BDEVs can transfer these biomolecular signatures to peripheral biofluids, setting the scene for their use as ND biomarkers. In this review, we explore the role of BDEVs in liquid biopsy as a promising route for early ND diagnosis, as well as patient stratification and follow-up, with a particular focus on their ability to transport misfolded proteins and protein aggregates, major actors in neurodegeneration development. We also discuss the link between the physicochemical properties of BDEVs and the potential insights gained into NDs, highlighting both challenges and opportunities associated with the use of BDEVs for ND diagnostics.

Extracellular vesicles: translational research and applications in neurology

Over the past few decades, extensive basic, translational and clinical research has been devoted to deciphering the physiological and pathogenic roles of extracellular vesicles (EVs) in the nervous system. The presence of brain cell-derived EVs in the blood, carrying diverse cargoes, has enabled the development of predictive, diagnostic, prognostic, disease-monitoring and treatment-response biomarkers for various neurological disorders. In this Review, we consider how EV biomarkers can bring us closer to understanding the complex pathogenesis of neurological disorders such as Alzheimer disease, Parkinson disease, stroke, traumatic brain injury, amyotrophic lateral sclerosis and multiple sclerosis. We describe how translational research on EVs might unfold bidirectionally, proceeding from basic to clinical studies but also in the opposite direction, with biomarker findings in the clinic leading to novel hypotheses that can be tested in the laboratory. We demonstrate the potential value of EVs across all stages of the therapeutic development pipeline, from identifying therapeutic targets to the use of EVs as reporters in model systems and biomarkers in clinical research. Finally, we discuss how the cargo and physicochemical properties of naturally occurring and custom-engineered EVs can be leveraged as novel treatments and vehicles for drug delivery, potentially revolutionizing neurotherapeutics.

Extracellular vesicles as therapeutic modulators of neuroinflammation in Alzheimer's disease: a focus on signaling mechanisms

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by the accumulation of amyloid-beta (Aβ) plaques and tau tangles, which contribute significantly to neuroinflammation, a central driver of disease pathogenesis. The activation of microglia and astrocytes, coupled with the complex interactions between Aβ and tau pathologies and the innate immune response, leads to a cascade of inflammatory events. This process triggers the release of pro-inflammatory cytokines and chemokines, exacerbating neuronal damage and fostering a cycle of chronic inflammation that accelerates neurodegeneration. Key signaling pathways, such as nuclear factor-kappa B (NF-κB), Janus kinase/signal transducer and activator of transcription (JAK/STAT), mitogen-activated protein kinase (MAPK), and phosphoinositide 3-kinase/protein kinase B (PI3K/Akt), are involved in regulating the production of these inflammatory mediators, offering potential therapeutic targets for AD. Recently, extracellular vesicles (EVs) have emerged as a promising tool for AD therapy, due to their ability to cross the blood-brain barrier (BBB) and deliver therapeutic agents. Despite challenges in standardizing EV-based therapies and ensuring their safety, EVs offer a novel approach to modulating neuroinflammation and promoting neuroregeneration. This review aims to highlight the intricate relationship between neuroinflammation, signaling pathways, and the emerging role of EV-based therapeutics in advancing AD treatment strategies.

Nanomaterials in targeting amyloid-β oligomers: current advances and future directions for Alzheimer's disease diagnosis and therapy

The amyloid cascade hypothesis posits that amyloid-β oligomers (AβOs) are the most neurotoxic species in Alzheimer's disease (AD). These oligomers, characterized by their high β-sheet content, have been shown to significantly disrupt cell membranes, induce local inflammation, and impair autophagy processes, which collectively contribute to neuronal loss. As such, targeting AβOs specifically, rather than solely focusing on amyloid-β fibrils (AβFs), may offer a more effective therapeutic approach for AD. Recent advances in detection and diagnosis have emphasized the importance of accurately identifying AβOs in patient samples, enhancing the potential for timely intervention. In recent years, nanomaterials (NMs) have emerged as promising agents for addressing AβOs regarding their multivalent interactions, which can more effectively detect and inhibit AβO formation. This review provides an in-depth analysis of various nanochaperones developed to target AβOs, detailing their mechanisms of action and therapeutic potential via focusing on two main strategies, namely, disruption of AβOs through direct interaction and the inhibition of AβO nucleation by binding to intermediates of the oligomerization process. Evidence from in vivo studies indicate that NMs hold promise for ameliorating AD symptoms. Additionally, the review explores the different interaction mechanisms through which nanoparticles exhibit their inhibitory effects on AβOs, providing insights into their potential for clinical application. This comprehensive overview highlights the current advancements in NM-based therapies for AD and outlines future research directions aimed at optimizing these innovative treatments.

Investigation of the Effects of Acacetin on Autophagy Pathway and Exosome Release in Amyloid Beta Peptide-Induced Toxicity Models

Understanding   the mechanism behind Alzheimer's disease is imperative due to the critical role of the autophagy pathway in protein homeostasis and neuronal survival. Autophagy pathway irregularities in neurons may increase exosome-mediated toxic protein transport, which can spread neurodegenerative diseases. Compelling evidence hints that acacetin (ACA) is a naturally occurring biocomponent exhibiting neuroprotective pharmacological properties. However, further molecular investigations are pressing to uncover the therapeutic potential of ACA. The present investigation endeavors to scrutinize the impact of ACA on the autophagy pathway and exosome release in an amyloid beta (Aβ) peptide-induced toxicity model. Herein, first, molecular modeling was performed between ACA and autophagy-related proteins. Afterward, the Aβ peptide-induced toxicity model cells were treated with ACA, and total and exosomal protein isolation was carried out and analyzed. Considering the findings, our molecular dynamics simulation of the ACA-protein complexes, spanning 100 ns, conclusively demonstrated stable protein-ligand interactions. Additionally, ACA was determined to regulate LC3II, Beclin-1, p62, and Lamp2a protein levels and reduce amyloid-β and Alix protein levels. In conclusion, our study highlights the significant in vitro neuroprotective effect of ACA against Aβ toxicity through autophagy. Moving forward, future studies may seek to elucidate the specific neuroprotective, therapeutic effects and mechanisms of ACA via autophagy in in vivo models. Addressing the identified limitations and capitalizing on the outlined future prospects are essential steps towards harnessing the therapeutic potential of ACA in combating neurodegenerative diseases, offering renewed hope for patients and caregivers alike.

Extracellular vesicle-based point-of-care testing for diagnosis and monitoring of Alzheimer's disease

Extracellular vesicles (EVs) show potential for early diagnosis of Alzheimer's disease (AD) and monitoring of its progression. However, EV-based AD diagnosis faces challenges due to the small size and low abundance of biomarkers. Here, we report a fully integrated organic electrochemical transistor (OECT) sensor for ultrafast, accurate, and convenient point-of-care testing (POCT) of serum EVs from AD patients. By utilizing acoustoelectric enrichment, the EVs can be quickly propelled, significantly enriched, and specifically bound to the OECT detection area, achieving a gain of over 280 times response in 30 s. The integrated POCT sensor can detect serum EVs from AD patients with a limit of detection as low as 500 EV particles/mL and a reduced detection time of just two minutes. Furthermore, the integrated POCT sensors were used to monitor AD progression in an AD mouse model by testing the mouse Aβ EVs at different time courses (up to 18 months) and compared with the Aβ accumulation using high-resolution magnetic resonance imaging (MRI). This innovative technology has the potential for accurate and rapid diagnosis of Alzheimer's and other neurodegenerative diseases, and monitoring of disease progression and treatment response.

Glial and blood-brain barrier cell-derived exosomes: Implications in stroke

Exosomes are small extracellular vesicles released by cells that play a pivotal role in intercellular communication, significantly influencing both the pathophysiology and potential treatment of ischemic stroke (IS). This review examines exosomes derived from key brain cell types, including microglia, astrocytes, oligodendrocytes, oligodendrocyte precursor cells (NG2+ cells), endothelial cells, and pericytes, emphasizing their molecular cargo and functional impact in IS. Microglia-derived exosomes regulate neuroinflammation, with M2-type exosomes exhibiting neuroprotective effects, while astrocyte-derived exosomes modulate pathways involved in pyroptosis and autophagy, influencing neuronal survival. Oligodendrocyte and NG2+ cell-derived exosomes contribute to remyelination, axonal growth, and inflammatory modulation. Endothelial and pericyte-derived exosomes play critical roles in BBB integrity, neurovascular remodeling, and drug transport across the BBB. This synthesis highlights recent advances in understanding how exosome-mediated communication impacts IS recovery and explores their translational potential for biomarker development and targeted therapies. By manipulating exosomal composition and delivery mechanisms, novel therapeutic strategies may emerge, offering hope for improved IS treatment outcomes.

Extracellular Competing Endogenous RNA Networks Reveal Key Regulators of Early Amyloid Pathology Propagation in Alzheimer's Disease

Extracellular vesicles (EVs) are small capsular bodies released by cells, mediating responses in intercellular communication. The role of EVs in Aβ pathology spreading in the Alzheimer's disease (AD) brain has been evidenced, although whether this occurs due to the co-transportation of Aβ peptides or contribution of other factors, such as EV-associated transcripts, remains uncertain. In vitro studies of miRNA cargo in neuron-derived extracellular vesicles (NDEVs) show that Aβ hyperexpression alters the transcriptomic profile; however, it is not clear to what extent this causes changes at the organ level. By utilizing datasets from published studies, we generated competing endogenous RNA (ceRNA) networks for miRNAs co-expressed in NDEVs and the brain in different stages of pathology, using both an APP overexpressing neuronal model (in vitro) and brain cortices from 6- and 9-month-old APP/PSEN1 mice (in vivo). Networks integrating information from mRNAs, lncRNAs, and circRNAs showed two candidate lncRNAs (Kcnq1ot1 and Gm42969) and a circRNA (Pum1), while enrichment analyses detected that NDEVs miRNAs signal to other CNS cells and that this signal can be disrupted by Aβ pathology, contributing to the loss of long-term potentiation seen in early AD.

The role of exosomes in diagnosis, pathophysiology, and management of Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder associated with impaired cognitive function and memory loss. Currently, available therapeutics can effectively alleviate the symptoms of AD, but there is a lack of treatment to halt the progression of the disease. In recent years, exosomes have gained much attention due to their involvement in various neurological disorders. Exosomes are small extracellular vesicles comprising lipids, proteins, DNA, non-coding RNA, and mRNAs, can carry various therapeutic molecules, and are potential drug delivery vehicles. Exosomes are known as a double-edged sword due to their involvement in both the pathogenesis and management of AD. This review explores the function of exosomes in the pathophysiology, treatment, and diagnosis of AD, also emphasizing their potential as a targeted drug delivery carrier to the brain. This review seeks to provide novel perspectives to understand better the onset, targeted treatment, and diagnosis of AD using exosomes.

Mapping Organism-wide Single Cell mRNA Expression Linked to Extracellular Vesicle Biogenesis, Secretion, and Cargo

Extracellular vesicles (EVs) are functional lipid-bound nanoparticles trafficked between cells and found in every biofluid. It is widely claimed that EVs can be secreted by every cell, but the quantity and composition of these EVs can differ greatly among cell types and tissues. Defining this heterogeneity has broad implications for EV-based communication in health and disease. Recent discoveries have linked single-cell EV secretion to the expression of genes encoding EV machinery and cargo. To gain insight at single-cell resolution across an entire organism, we compared the abundance, variance, and co-expression of 67 genes involved in EV biogenesis and secretion, or carried as cargo, across >44 000 cells obtained from 117 cell populations in the Tabula Muris. Our analysis provides both novel holistic and cell population-specific insight into EV biology. The highest overall expression of EV genes occurs in secretory cells of the pancreas and perhaps more surprisingly, multiple non-neuronal cell populations of the brain. We find that the most abundant EV genes encode the most abundant EV cargo proteins (tetraspanins and syndecans), but these genes are highly differentially expressed across functionally distinct cell populations. Expression variance identifies dynamic and constitutively expressed EV genes while co-expression analysis reveals novel insights into cell population-specific coordination of expression. Results of our analysis illustrate the diverse transcriptional regulation of EV genes which could be useful for predicting how individual cell populations might communicate via EVs to influence health and disease.

Extracellular vesicles lay the ground for neuronal plasticity by restoring mitochondrial function, cell metabolism and immune balance

Extracellular vesicles (EVs) convey complex signals between cells that can be used to promote neuronal plasticity and neurological recovery in brain disease models. These EV signals are multimodal and context-dependent, making them unique therapeutic principles. This review analyzes how EVs released from various cell sources control neuronal metabolic function, neuronal survival and plasticity. Preferential sites of EV communication in the brain are interfaces between pre- and postsynaptic neurons at synapses, between astrocytes and neurons at plasma membranes or tripartite synapses, between oligodendrocytes and neurons at axons, between microglial cells/macrophages and neurons, and between cerebral microvascular cells and neurons. At each of these interfaces, EVs support mitochondrial function and cell metabolism under physiological conditions and orchestrate neuronal survival and plasticity in response to brain injury. In the injured brain, the promotion of neuronal survival and plasticity by EVs is tightly linked with EV actions on mitochondrial function, cell metabolism, oxidative stress and immune responses. Via the stabilization of cell metabolism and immune balance, neuronal plasticity responses are activated and functional neurological recovery is induced. As such, EV lay the ground for neuronal plasticity.

Extracellular vesicles: new horizons in neurodegeneration

Extracellular vesicles (EVs) are lipid-enclosed nanovesicles secreted by diverse cell types that orchestrate intercellular communication through cargo delivery. Their pivotal roles span from supporting the development of normal central nervous system (CNS) to contributing to the pathogenesis of neurological diseases. Particularly noteworthy is their involvement in the propagation of pathogenic proteins, such as those involved in neurodegenerative disorders, and nucleic acids, closely linking them to disease onset and progression. Moreover, EVs have emerged as promising diagnostic biomarkers for neurological disorders and as tools for disease staging, owing to their ability to traverse the blood-brain barrier and their specific, stable, and accessible properties. This review comprehensively explores the realm of CNS-derived EVs found in peripheral blood, encompassing their detection methods, transport mechanisms, and diverse roles in various neurodegenerative diseases. Furthermore, we evaluate the potentials and limitations of EVs in clinical applications and highlight prospective research directions in this rapidly evolving field.

Lack of cellular prion protein causes Amyloid β accumulation, increased extracellular vesicle abundance, and changes to exosome biogenesis proteins

Alzheimer's disease (AD) progression is closely linked to the propagation of pathological Amyloid β (Aβ), a process increasingly understood to involve extracellular vesicles (EVs), namely exosomes. The specifics of Aβ packaging into exosomes remain elusive, although evidence suggests an ESCRT (Endosomal Sorting Complex Required for Transport)-independent origin to be responsible in spreading of AD pathogenesis. Intriguingly, PrPC, known to influence exosome abundance and bind oligomeric Aβ (oAβ), can be released in exosomes via both ESCRT-dependent and ESCRT-independent pathways, raising questions about its role in oAβ trafficking. Thus, we quantified Aβ levels within EVs, cell medium, and intracellularly, alongside exosome biogenesis-related proteins, following deletion or overexpression of PrPC. The same parameters were also evaluated in the presence of specific exosome inhibitors, namely Manumycin A and GW4869. Our results revealed that deletion of PrPC increases intracellular Aβ accumulation and amplifies EV abundance, alongside significant changes in cellular levels of exosome biogenesis-related proteins Vps25, Chmp2a, and Rab31. In contrast, cellular expression of PrPC did not alter exosomal Aβ levels. This highlights PrPC's influence on exosome biogenesis, albeit not in direct Aβ packaging. Additionally, our data confirm the ESCRT-independent exosome release of Aβ and we show a direct reduction in Chmp2a levels upon oAβ challenge. Furthermore, inhibition of opposite exosome biogenesis pathway resulted in opposite cellular PrPC levels. In conclusion, our findings highlight the intricate relationship between PrPC, exosome biogenesis, and Aβ release. Specifically, they underscore PrPC's critical role in modulating exosome-associated proteins, EV abundance, and cellular Aβ levels, thereby reinforcing its involvement in AD pathogenesis.

Preclinical Alzheimer's disease shows alterations in circulating neuronal-derived extracellular vesicle microRNAs in a multiethnic cohort

INTRODUCTION

Alzheimer's disease (AD) is the leading cause of dementia, affecting around 50 million individuals worldwide. Brain-derived extracellular vesicles (EVs) can cross the blood-brain barrier carrying neuron-specific molecules, such as microRNAs (miRNAs), which have potential as biomarkers of neurodegeneration.

METHODS

We explored the association between neuronal-derived EV miRNAs from serum and AD clinical status by performing a transcriptome-wide association study involving 46 participants with clinical AD, 14 participants with preclinical AD, and 60 neurologically healthy controls.

RESULTS

We identified 14 miRNAs associated with AD risk, with more pronounced transcriptional alterations in preclinical individuals compared to clinical AD individuals. Functional analysis revealed enrichment of miRNA-target genes in neurodegenerative pathways, highlighting synuclein alpha (SNCA), cytochrome c, somatic (CYCS), and microtubule associated protein tau (MAPT) as key targets.

DISCUSSION

Our results highlight the potential role of neuronal-derived EVs in neurodegeneration and suggest avenues for further research into brain-derived biomarkers.

HIGHLIGHTS

Neuronal-derived extracellular vesicles (NDEVs) carry potential brain biomarkers. We tested the association between NDEV microRNAs (miRNAs) and Alzheimer's disease (AD). Fourteen NDEV miRNAs were associated with AD. Preclinical AD displayed more pronounced transcriptional changes than clinical AD. miRNA-target genes were enriched in pathways associated with neurodegeneration.

A comprehensive view of the molecular features within the serum and serum EV of Alzheimer's disease

Conventional Alzheimer's disease research mainly focuses on cerebrospinal fluid, which requires an invasive sampling procedure. This method carries inherent risks for patients and could potentially lower patient compliance. EVs (Extracellular Vesicles) and blood are two emerging noninvasive mediators reflecting the pathological changes of Alzheimer's disease. Integrating the two serum proteomic information based on DIA (Data Independent Acquisition) is conducive to the comparison of serological research strategies, mining pathological information of AD, and evaluating the potential of EVs and blood in the diagnosis of AD. We generated a combined proteomic data resource of 39 serum samples derived from patients with AD and from age-matched controls (AMC) and identified 639 PGs (protein groups) in serum samples and 714 PGs in serum EV samples. The differentially expressed protein groups identified in both serum and serum EV provide a reflective profile of the pathological characteristics associated with AD. The combined strategy performed well, identifying 40 potential diagnostic markers with AUC values above 0.85, including two molecular diagnostic models that achieved an effectiveness score of 0.991.

Roles, Functions, and Pathological Implications of Exosomes in the Central Nervous System

Exosomes are a subset of extracellular vesicles (EVs) secreted by nearly all cell types and have emerged as a novel mechanism for intercellular communication within the central nervous system (CNS). These vesicles facilitate the transport of proteins, nucleic acids, lipids, and metabolites between neurons and glial cells, playing a pivotal role in CNS development and the maintenance of homeostasis. Current evidence indicates that exosomes from CNS cells may function as either inhibitors or enhancers in the onset and progression of neurological disorders. Furthermore, exosomes have been found to transport disease-related molecules across the blood-brain barrier, enabling their detection in peripheral blood. This distinctive property positions exosomes as promising diagnostic biomarkers for neurological conditions. Additionally, a growing body of research suggests that exosomes derived from mesenchymal stem cells exhibit reparative effects in the context of neurological disorders. This review provides a concise overview of the functions of exosomes in both physiological and pathological states, with particular emphasis on their emerging roles as potential diagnostic biomarkers and therapeutic agents in the treatment of neurological diseases.

Extracellular vesicle-packed microRNAs profiling in Alzheimer's disease: The molecular intermediary between pathology and diagnosis

MicroRNAs (miRNAs), referring to a type of non-coding RNAs functioning in various biological processes, participate in the pathophysiology of Alzheimer's disease (AD) through increasing amyloid-beta (Aβ) production, enhancing Tau phosphorylation, and inducing neuroinflammation. Meanwhile, extracellular vesicles (EVs) have been suggested as promising carriers of AD biomarkers as they possess the ability to transmit information from cerebral tissue to peripheral blood. Inspired by the above findings, we in this review systematically generalized the roles of miRNAs in AD and explored the potential of EV-packed miRNA as biomarkers for early diagnosis of AD. Through the detailed investigation, this review may highlight the promise of EV-packed miRNAs in advancing our understanding of AD, and underscore the imperative needs of further studies on their diagnostic potential.

Recent Insights into the Neurobiology of Alzheimer's Disease and Advanced Treatment Strategies

In recent years, significant advancements have been made in understanding Alzheimer's disease from both neurobiological and clinical perspectives. Exploring the complex systems underlying AD has unveiled insights that could potentially revolutionize therapeutic approaches. Recent investigations have highlighted intricate interactions among genetic, molecular, and environmental factors in AD. Optimism arises from neurobiological advancements and diverse treatment options, potentially slowing or halting disease progression. Amyloid-beta plaques and tau protein tangles crucially influence AD onset and progression. Emerging treatments involve diverse strategies, such as approaches targeting multiple pathways involved in AD pathogenesis, such as inflammation, oxidative stress, and synaptic dysfunction pathways. Clinical trials using humanized monoclonal antibodies, focusing on immunotherapies eliminating amyloid-beta, have shown promise. Nonpharmacological interventions such as light therapy, electrical stimulation, cognitive training, physical activity, and dietary changes have drawn attention for their potential to slow cognitive aging and enhance brain health. Precision medicine, which involves tailoring therapies to individual genetic and molecular profiles, has gained traction. Ongoing research and interdisciplinary collaboration are expected to yield more effective treatments.

Role of dietary and nutritional interventions in ceramide-associated diseases

Ceramides are important intermediates in sphingolipid metabolism and serve as signaling molecules with independent biological significance. Elevated cellular and circulating ceramide levels are consistently associated with pathological conditions including cardiometabolic diseases, neurological diseases, autoimmune diseases, and cancers. Although pharmacological inhibition of ceramide formation often protects against these diseases in animal models, pharmacological modulation of ceramides in humans remains impractical. Dietary interventions including the Mediterranean diet, lacto-ovo-vegetarian diet, calorie-restricted diet, restriction of dairy product consumption, and dietary supplementation with polyunsaturated fatty acids, dietary fibers, and polyphenols, all have beneficial effects on modulating ceramide levels. Mechanistic insights into these interventions are discussed. This article reviews the relationships between ceramides and disease pathogenesis, with a focus on dietary intervention as a viable strategy for lowering the concentration of circulating ceramides.

Mapping the current trends and hotspots of extracellular vesicles in Alzheimer's disease: a bibliometric analysis

Background

Extracellular vesicles (EVs) have garnered significant attention in Alzheimer's disease (AD) research over the past decade, largely due to their potential in diagnostics and therapeutics. Although the investigation of EVs in AD is a relatively recent endeavor, a comprehensive bibliometric analysis of this rapidly growing field has yet to be conducted.

Methods

This study aims to elucidate and synthesize the relationship between EVs and AD, offering critical insights to guide future research and expand therapeutic possibilities. Over the past 10-15 years, substantial progress has been made in this domain. Through bibliometric techniques, this analysis assesses research performance by examining scientific publications and metrics, including productivity indicators, impact measurements, data mining, and visualization tools.

Results

A total of 602 publications were analyzed using various online platforms for bibliometric analysis. Notably, the number of publications began to increase rapidly in 2018, with China and the United States emerging as leaders in this research area. The National Institute on Aging produced the highest number of publications among institutions. The Journal of Molecular Sciences and the Journal of Biological Chemistry were the most prolific and most frequently cited journals, respectively. Among individual contributors, Dimitrios Kapogiannis was identified as the most productive author, while Edward J. Goetzl was the most co-cited. The most prevalent keywords included "neurodegenerative diseases," "exosomes," "blood biomarkers," "amyloid beta," "microglia," and "tau protein." Current research hotspots involve microRNA dysregulation, oxidative stress, carboxyl-terminal fragments, small EVs, and mesenchymal stem cell-derived EVs, indicating key areas for future research.

Conclusion

Research on microRNA dysregulation, oxidative stress, carboxyl-terminal fragments, small EVs, and mesenchymal stem cell-derived EVs represents a critical frontier in the study of Alzheimer's disease. The role of EV-mediated neuroinflammation in AD is a focal point of ongoing investigation and will likely shape future developments in the field.

Mitochondrial dysfunction and Alzheimer's disease: pathogenesis of mitochondrial transfer

In recent years, mitochondrial transfer has emerged as a universal phenomenon intertwined with various systemic physiological and pathological processes. Alzheimer's disease (AD) is a multifactorial disease, with mitochondrial dysfunction at its core. Although numerous studies have found evidence of mitochondrial transfer in AD models, the precise mechanisms remain unclear. Recent studies have revealed the dynamic transfer of mitochondria in Alzheimer's disease, not only between nerve cells and glial cells, but also between nerve cells and glial cells. In this review, we explore the pathways and mechanisms of mitochondrial transfer in Alzheimer's disease and how these transfer activities contribute to disease progression.

Extracellular vesicles: biological mechanisms and emerging therapeutic opportunities in neurodegenerative diseases

Extracellular vesicles (EVs) are membrane vesicles originating from different cells within the brain. The pathophysiological role of EVs in neurodegenerative diseases is progressively acknowledged. This field has advanced from basic biological research to essential clinical significance. The capacity to selectively enrich specific subsets of EVs from biofluids via distinctive surface markers has opened new avenues for molecular understandings across various tissues and organs, notably in the brain. In recent years, brain-derived EVs have been extensively investigated as biomarkers, therapeutic targets, and drug-delivery vehicles for neurodegenerative diseases. This review provides a brief overview of the characteristics and physiological functions of the various classes of EVs, focusing on the biological mechanisms by which various types of brain-derived EVs mediate the occurrence and development of neurodegenerative diseases. Concurrently, novel therapeutic approaches and challenges for the use of EVs as delivery vehicles are delineated.

Role of Redox Homeostasis in the Communication Between Brain and Liver Through Extracellular Vesicles

Extracellular vesicles (EVs) are small, membrane-bound particles secreted by cells into the extracellular environment, playing an increasingly recognized role in inter-organ communication and the regulation of various physiological processes. Regarding the redox homeostasis context, EVs play a pivotal role in propagating and mitigating oxidative stress signals across different organs. Cells under oxidative stress release EVs containing signaling molecules that can influence the redox status of distant cells and tissues. EVs are starting to be recognized as contributors to brain-liver communication. Therefore, in this review, we show how redox imbalance can affect the release of EVs in the brain and liver. We propose EVs as mediators of redox homeostasis in the brain-liver axis.

Shared and distinct changes in the molecular cargo of extracellular vesicles in different neurodegenerative diseases

Neurodegenerative disorders such as Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS) and Parkinson's disease (PD) affect millions of people worldwide. Curative treatment for these neurodegenerative disorders is still lacking and therefore a further understanding of their cause and progression is urgently needed. Extracellular vesicles (EVs) are nanosized vesicles loaded with cargo, such as proteins and miRNAs, that are released by cells and play an important role in intercellular communication. Intercellular communication through EVs can contribute to the spread of pathological proteins, such as amyloid-beta and tau, or cause pathogenesis through other mechanisms. In addition, EVs may serve as potential biomarkers for diagnosis and for monitoring disease progression. In this review, we summarize and discuss recent advances in our understanding of the role of EVs in AD, ALS an PD with an emphasis on dysregulated cargo in each disease. We highlight shared dysregulated cargo between these diseases, discuss underlying pathways, and outline future implications for therapeutic strategies.

Biofluid biomarkers for Alzheimer's disease: past, present, and future

Alzheimer's disease (AD) is a gradually progressive neurodegenerative disease with tremendous social and economic burden. Therefore, early and accurate diagnosis is imperative for effective treatment or prevention of the disease. Cerebrospinal fluid and blood biomarkers emerge as favorable diagnostic tools due to their relative accessibility and potential for widespread clinical use. This review focuses on the AT(N) biomarker system, which includes biomarkers reflecting AD core pathologies, amyloid deposition, and pathological tau, as well as neurodegeneration. Novel biomarkers associated with inflammation/immunity, synaptic dysfunction, vascular pathology, and α-synucleinopathy, which might contribute to either the pathogenesis or the clinical progression of AD, have also been discussed. Other emerging candidates including non-coding RNAs, metabolites, and extracellular vesicle-based markers have also enriched the biofluid biomarker landscape for AD. Moreover, the review discusses the current challenges of biofluid biomarkers in AD diagnosis and offers insights into the prospective future development.

Vesicles: New Advances in the Treatment of Neurodegenerative Diseases

Neurodegenerative diseases are characterized by brain lesions that limit normal daily activities and represent a major challenge to healthcare systems worldwide, with a significant economic impact. Nanotechnology is the science of manipulating matter at the nanoscale, where materials exhibit unique properties that are significantly different from their larger counterparts. These properties can be exploited for a wide range of applications, including medicine. Among the emerging therapeutic approaches for the treatment of neurodegenerative diseases, nanotechnologies are gaining prominence as a promising avenue to explore. Here, we review the state of the art of biological and artificial vesicles and their biological properties in the context of neurodegenerative diseases. Indeed, nanometric structures such as extracellular vesicles and artificial vesicles represent a promising tool for the treatment of such disorders due to their size, biocompatibility, and ability to transport drugs, proteins, and genetic material across the blood-brain barrier to target specific cells and brain areas. In the future, a deeper and broader synergy between materials science, bioengineering, biology, medicine, and the discovery of new, increasingly powerful delivery systems will certainly enable a more applied use of nanotechnology in the treatment of brain disorders.

Regulation of adult neurogenesis: the crucial role of astrocytic mitochondria

Neurogenesis has emerged as a promising therapeutic approach for central nervous system disorders. The role of neuronal mitochondria in neurogenesis is well-studied, however, recent evidence underscores the critical role of astrocytic mitochondrial function in regulating neurogenesis and the underlying mechanisms remain incompletely understood. This review highlights the regulatory effects of astrocyte mitochondria on neurogenesis, focusing on metabolic support, calcium homeostasis, and the secretion of neurotrophic factors. The effect of astrocytic mitochondrial dysfunction in the pathophysiology and treatment strategies of Alzheimer's disease and depression is discussed. Greater attention is needed to investigate the mitochondrial autophagy, dynamics, biogenesis, and energy metabolism in neurogenesis. Targeting astrocyte mitochondria presents a potential therapeutic strategy for enhancing neural regeneration.

The Yin and Yang of Microglia-Derived Extracellular Vesicles in CNS Injury and Diseases

Microglia, the resident immune cells of the central nervous system (CNS), play a crucial role in maintaining neural homeostasis but can also contribute to disease and injury when this state is disrupted or conversely play a pivotal role in neurorepair. One way that microglia exert their effects is through the secretion of small vesicles, microglia-derived exosomes (MGEVs). Exosomes facilitate intercellular communication through transported cargoes of proteins, lipids, RNA, and other bioactive molecules that can alter the behavior of the cells that internalize them. Under normal physiological conditions, MGEVs are essential to homeostasis, whereas the dysregulation of their production and/or alterations in their cargoes have been implicated in the pathogenesis of numerous neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), spinal cord injury (SCI), and traumatic brain injury (TBI). In contrast, MGEVs may also offer therapeutic potential by reversing inflammation or being amenable to engineering for the delivery of beneficial biologics or drugs. The effects of MGEVs are determined by the phenotypic state of the parent microglia. Exosomes from anti-inflammatory or pro-regenerative microglia support neurorepair and cell survival by delivering neurotrophic factors, anti-inflammatory mediators, and molecular chaperones. Further, MGEVs can also deliver components like mitochondrial DNA (mtDNA) and proteins to damaged neurons to enhance cellular metabolism and resilience. MGEVs derived from pro-inflammatory microglia can have detrimental effects on neural health. Their cargo often contains pro-inflammatory cytokines, molecules involved in oxidative stress, and neurotoxic proteins, which can exacerbate neuroinflammation, contribute to neuronal damage, and impair synaptic function, hindering neurorepair processes. The role of MGEVs in neurodegeneration and injury-whether beneficial or harmful-largely depends on how they modulate inflammation through the pro- and anti-inflammatory factors in their cargo, including cytokines and microRNAs. In addition, through the propagation of pathological proteins, such as amyloid-beta and alpha-synuclein, MGEVs can also contribute to disease progression in disorders such as AD and PD, or by the transfer of apoptotic or necrotic factors, they can induce neuron toxicity or trigger glial scarring during neurological injury. In this review, we have provided a comprehensive and up-to-date understanding of the molecular mechanisms underlying the multifaceted role of MGEVs in neurological injury and disease. In particular, the role that specific exosome cargoes play in various pathological conditions, either in disease progression or recovery, will be discussed. The therapeutic potential of MGEVs has been highlighted including potential engineering methodologies that have been employed to alter their cargoes or cell-selective targeting. Understanding the factors that influence the balance between beneficial and detrimental exosome signaling in the CNS is crucial for developing new therapeutic strategies for neurodegenerative diseases and neurotrauma.

HIV-Associated Neurocognitive Disorder (HAND) and Alzheimer's Disease Pathogenesis: Future Directions for Diagnosis and Treatment

HIV-associated neurocognitive disorder (HAND) and Alzheimer's disease (AD) are two neurocognitive disorders with overlapping clinical presentations and pathophysiology. The two have been thought to be two separate entities. However, the introduction and widespread use of antiretroviral therapy (ART) has altered the clinical manifestations of HAND, shifting from a pattern of subcortical dementia to one more akin to cortical dementia, resembling AD. Thus, the line between the two disease entities is not clear-cut. In this review, we discuss the concept of Alzheimer's disease-like dementia (ADLD) in HIV, which describes this phenomenon. While the mechanisms of HIV-associated ADLD remain to be elucidated, potential mechanisms include HIV-specific pathways, including epigenetic imprinting from initial viral infection, persistent and low viral load (which can only be detected by ultra-sensitive PCR), HIV-related inflammation, and putative pathways underlying traditional AD risk factors. Importantly, we have shown that HIV-specific microRNAs (miRs) encapsulated in extracellular vesicles (EV-miRs) play an important role in mediating the detrimental effects in the cardiovascular system. A useful preclinical model to study ADLD would be to expose AD mice to HIV-positive EVs to identify candidate EV-miRs that mediate the HIV-specific effects underlying ADLD. Characterization of the candidate EV-miRs may provide novel therapeutic armamentaria for ADLD.

Brain incoming call from glia during neuroinflammation: Roles of extracellular vesicles

The functionality of the central nervous system (CNS) relies on the connection, integration, and the exchange of information among neural cells. The crosstalk among glial cells and neurons is pivotal for a series of neural functions, such as development of the nervous system, electric conduction, synaptic transmission, neural circuit establishment, and brain homeostasis. Glial cells are crucial players in the maintenance of brain functionality in physiological and disease conditions. Neuroinflammation is a common pathological process in various brain disorders, such as neurodegenerative diseases, and infections. Glial cells, including astrocytes, microglia, and oligodendrocytes, are the main mediators of neuroinflammation, as they can sense and respond to brain insults by releasing pro-inflammatory or anti-inflammatory factors. Recent evidence indicates that extracellular vesicles (EVs) are pivotal players in the intercellular communication that underlies physiological and pathological processes. In particular, glia-derived EVs play relevant roles in modulating neuroinflammation, either by promoting or inhibiting the activation of glial cells and neurons, or by facilitating the clearance or propagation of pathogenic proteins. The involvement of EVs in neurodegenerative diseases such as Alzheimer's Disease (AD), Parkinson's Disease (PD), Huntington's Disease (HD), and Multiple Sclerosis (MS)- which share hallmarks such as neuroinflammation and oxidative stress to DNA damage, alterations in neurotrophin levels, mitochondrial impairment, and altered protein dynamics- will be dissected, showing how EVs act as pivotal cell-cell mediators of toxic stimuli, thereby propagating degeneration and cell death signaling. Thus, this review focuses on the EVs secreted by microglia, astrocytes, oligodendrocytes and in neuroinflammatory conditions, emphasizing on their effects on neurons and on central nervous system functions, considering both their beneficial and detrimental effects.

Targeting exosomal double-stranded RNA-TLR3 signaling pathway attenuates morphine tolerance and hyperalgesia

Long-term morphine use leads to tolerance and hyperalgesia in patients with chronic pain, with neuroinflammation playing a key role, but its underlying mechanisms remain elusive. This study determines that repeated intrathecal morphine injections increase double-stranded RNA (dsRNA) production in spinal neurons, due to downregulated adenosine deaminase RNA specific 1 (ADAR1) expression. Lentivirus-induced ADAR1 elevation decreases the high levels of intracellular dsRNA and attenuates morphine tolerance and hyperalgesia. dsRNA is released into cerebrospinal fluid via exosomes (Exos) after repeated morphine injections and is taken up by microglia for TLR3-TRIF-IL-6 signaling activation. Blocking Exos release with GW4869 or inhibition of TLR3 signaling mitigates neuroinflammation, preventing the development of morphine tolerance and hyperalgesia. Intrathecal injection of TLR3 inhibitor alone shows analgesic effects in neuropathic pain, and co-administration with morphine amplifies the analgesic efficacy of morphine. These findings demonstrate that targeting dsRNA-TLR3 signaling to mitigate neuroinflammation could be a promising treatment for morphine tolerance.

Potential Mechanisms of Tunneling Nanotube Formation and Their Role in Pathology Spread in Alzheimer's Disease and Other Proteinopathies

Alzheimer's disease (AD) is the most common type of dementia worldwide. The etiopathogenesis of this disease remains unknown. Currently, several hypotheses attempt to explain its cause, with the most well-studied being the cholinergic, beta-amyloid (Aβ), and Tau hypotheses. Lately, there has been increasing interest in the role of immunological factors and other proteins such as alpha-synuclein (α-syn) and transactive response DNA-binding protein of 43 kDa (TDP-43). Recent studies emphasize the role of tunneling nanotubes (TNTs) in the spread of pathological proteins within the brains of AD patients. TNTs are small membrane protrusions composed of F-actin that connect non-adjacent cells. Conditions such as pathogen infections, oxidative stress, inflammation, and misfolded protein accumulation lead to the formation of TNTs. These structures have been shown to transport pathological proteins such as Aβ, Tau, α-syn, and TDP-43 between central nervous system (CNS) cells, as confirmed by in vitro studies. Besides their role in spreading pathology, TNTs may also have protective functions. Neurons burdened with α-syn can transfer protein aggregates to glial cells and receive healthy mitochondria, thereby reducing cellular stress associated with α-syn accumulation. Current AD treatments focus on alleviating symptoms, and clinical trials with Aβ-lowering drugs have proven ineffective. Therefore, intensifying research on TNTs could bring scientists closer to a better understanding of AD and the development of effective therapies.

Extracellular Vesicle-Mediated Neuron-Glia Communications in the Central Nervous System

Communication between neurons and glia significantly influences the development maturation, plasticity, and disease progressions of the nervous system. As a new signaling modality, extracellular vesicles display a diverse role for robust functional regulation of neurons through their protein and nucleic acid cargoes. This review highlights recent breakthroughs in the research of signaling mechanisms between glia and neurons mediated by extracellular vesicles that are important for neural development, axonal maintenance, synaptic functions, and disease progression in the mammalian nervous system. We will discuss the biological roles of extracellular vesicles released from neurons, astroglia, microglia, and oligodendroglia in the nervous system and their implications in neurodegenerative disorders.

Exosomes in multiple sclerosis and Alzheimer's disease - Adversary and ally

Neuroinflammation and the resulting neurodegeneration is a big challenge for the healthcare system, especially with the aging population. Neuroinflammation can result from a variety of insults to the central nervous system leading to an interplay between immune and brain cells that sustains chronic inflammation and injures neural cells. One facilitator of this toxic interplay are exosomes. Exosomes are nano-sized, bilayer lipid vesicles secreted by cells containing proteins, nucleic acids and lipids. Because exosomes can be internalized by other cells, their contents can elicit inflammatory responses and trigger toxicities in recipient cells. On the flip side, exosomes can act as therapeutic vehicles carrying protective cargo to maintain homeostasis. This review discusses exosome biogenesis, composition, and its role in neuroinflammation and neurodegeneration in the context of multiple sclerosis and Alzheimer's disease. The emerging roles of exosomes as biomarkers of neurologic diseases and as therapeutic delivery vehicles are also discussed. With all of these varying roles, interest and excitement in exosomes continue to grow exponentially and their promise as brain therapeutics is only beginning to be explored and harnessed.

Amyloid-β oligomer-induced neurotoxicity by exosomal interactions between neuron and microglia

A hallmark of Alzheimer's disease (AD) is amyloid-β (Aβ) plaque deposition in the brain, causing deficits in cognitive function. Amyloid-beta oligomers (AβOs), the soluble precursor peptides producing Aβ plaques, also produce neurotoxicity and microgliosis together with glycolytic reprogramming. Recently, monocarboxylate transporter 1 (MCT1), a key glycolysis regulator, and its ancillary protein, CD147, are found to play an important role in the secretion of exosomes, 30-200 nm vesicles in size, which are considered as toxic molecule carriers in AD. However, the effect of low-concentration AβOs (1 nM) on microglia MCT1 and CD147 expression as well as 1 nM AβOs-treated microglia-derived exosomes on neuronal toxicity remain largely elusive. In this study, 1 nM AβOs induce significant axonopathy and microgliosis. Furthermore, 1 nM AβOs-treated neurons- or microglia-derived exosomes produce axonopathy through their autologous or heterologous uptake by neurons, supporting the role of exosomes as neurotoxicity mediators in AD. Interestingly, MCT1 and CD147 are enhanced in microglia by treatment with 1 nM AβOs or exosomes from 1 nM AβOs-treated- microglia or neurons, suggesting the implication of AβOs-induced enhanced MCT1 and CD147 in microglia with AD neuropathogenesis, which is consistent with the in-silico analysis of the single cell RNA sequencing data from microglia in mouse models of AD and AD patients.

Proteomics of plasma-derived extracellular vesicles reveals S100A8 as a novel biomarker for Alzheimer's disease: A preliminary study

Extracellular vesicles (EVs) act as mediators for intercellular transfer of Aβ and tau proteins, promoting the propagation of these pathological misfolded proteins throughout the brain in Alzheimer's disease (AD). Levels of blood exosomal Aβ42, total Tau (t-Tau) and phosphorylated Tau (p-Tau) had a high correlation with their concentrations in cerebrospinal fluid (CSF), demonstrating that exosomal biomarkers have equal contribution as those in CSF for the diagnosis of AD. We aimed to comprehensively characterize the proteome of plasma-derived EVs to identify differentially expressed proteins (DEPs) and pathways in AD. Tandem mass tag (TMT) labeled quantitative proteomics was applied to analyze plasma-derived EV proteins in 9 AD patients and 9 healthy controls. 335 proteins were quantified, and 12 DEPs were identified including seven upregulated proteins and five down-regulated proteins. Oligomerized Aβ1-42 induced SH-SY5Y cell damage model was built to mimic the pathological changes of AD, and small interfering RNA (siRNA) against S100A8 was used to knock down S100A8 expression. Results displayed S100A8 was down regulated in plasma-derived EVs from AD patients, while enriched in EVs derived from Aβ1-42-induced SH-SY5Y cells. Furthermore, Aβ1-42-induced SH-SY5Y cells treated with S100A8 siRNA showed decreased Aβ levels in cell lysate and EVs, especially in EVs. SIGNIFICANCE: The investigation aimed to comprehensively characterize the proteome of plasma-derived EVs to identify DEPs and potential biomarker of AD. S100A8 was found down regulated in plasma-derived EVs from AD patients using TMT labeled quantitative proteomics. The diagnostic value of S100A8 was also confirmed using receiver operating characteristic curve (ROC) analysis. Furthermore, Aβ1-42-induced SH-SY5Y cells treated with S100A8 siRNA showed decreased Aβ levels in cell lysate and EVs, especially in EVs. The preliminary findings suggest that suppression of S100A8 expression inhibits Aβ aggregation both in cell lysate and EVs from Aβ1-42-induced SH-SY5Y cells, and S100A8 more likely regulates Aβ aggregation via EVs. Therefore, plasma-derived EV S100A8 might be a potential biomarker of AD. Manipulation of S100A8 expression may be a novel therapeutic strategy in the treatment of AD.

Present and future use of exosomes containing proteins and RNAs in neurodegenerative diseases for synaptic function regulation: A comprehensive review

Neurodegenerative diseases (NDDs) are increasingly prevalent with global aging, demanding effective treatments. Exosomes, which contain biological macromolecules such as RNA (including miRNAs) and proteins like α-synuclein, tau, and amyloid-beta, are gaining attention as innovative therapeutics. This comprehensive review systematically explores the potential roles of exosomes in NDDs, with a particular focus on their role in synaptic dysfunction. We present the synaptic pathophysiology of NDDs and discuss the mechanisms of exosome formation, secretion, and action. Subsequently, we review the roles of exosomes in different types of NDDs, such as Alzheimer's disease and Parkinson's disease, with a special focus on their regulation of synaptic function. In addition, we explore the potential use of exosomes as biomarkers, as well as the challenges and opportunities in their clinical application. We provide perspectives on future research directions and development trends to provide a more comprehensive understanding of and guidance for the application of exosomes in the treatment of NDDs. In conclusion, exosomes rich in biological macromolecules, as a novel therapeutic strategy, have opened up new possibilities for the treatment of NDDs and brought new hope to patients.

Multiomic Profiling and Neuroprotective Bioactivity of Salvia Hairy Root-Derived Extracellular Vesicles in a Cellular Model of Parkinson's Disease

Purpose

Extracellular vesicles (EVs) are promising tools for nanomedicine and nanobiotechnology. The purification of mammalian-derived EVs involves intensive processes, and their therapeutic application raises multiple safety and regulatory issues. Plants have the potential to serve as nonconventional sources of therapeutically relevant EVs. In this context, we recently identified hairy roots (HRs) of medicinal plants as a novel biotechnological platform to produce EVs for human health.

Methods

Herein, we report the purification, omics profiling, and bioactivity of EVs isolated from HRs of the medicinal plants S. sclarea and S. dominica. EVs were isolated from conditioned media of HR cultures using differential ultracentrifugation (dUC) and size exclusion chromatography (SEC). The isolated EVs were characterized by nanoparticle tracking analysis (NTA) and electron microscopy. The proteomic and metabolomic profiles of the EVs were determined using mass spectrometry. Uptake studies and bioactivity assays, including confocal microscopy, MTT, flow cytometry, ROS quantification, and untargeted metabolomics analyses, were conducted in SH-SY5Y cells treated with the neurotoxin 6-hydroxydopamine (6-OHDA) to evaluate the therapeutic potential of EVs in an in vitro model of Parkinson's disease.

Results

S. sclarea HRs released nanosized round-shaped EVs with a distinctive molecular signature. HR EVs from S. sclarea and S. dominica revealed conserved cargo of secondary metabolites, predominantly triterpenoids, which are known for their antioxidant properties. We showed that HR EVs are safe, enter the cells, and strongly inhibit apoptosis in a cellular model of Parkinson's disease. Cellular metabolomics revealed that EVs preserved metabolic homeostasis and mitigated cellular oxidative stress when co-administered with 6-OHDA. Mechanistically, HR EVs inhibited 6-OHDA autoxidation and substantially reduced the accumulation of its oxidative products, which are responsible for 6-OHDA-induced toxicity.

Conclusion

Collectively, our findings provide compelling evidence that EVs isolated from the hairy roots of Salvia species are promising, non-mammalian alternative for the design of novel therapies targeting neurological disorders.

Exosomes: A Cellular Communication Medium That Has Multiple Effects On Brain Diseases

Exosomes, as membranous vesicles generated by multiple cell types and secreted to extracellular space, play a crucial role in a range of brain injury-related brain disorders by transporting diverse proteins, RNA, DNA fragments, and other functional substances. The nervous system's pathogenic mechanisms are complicated, involving pathological processes like as inflammation, apoptosis, oxidative stress, and autophagy, all of which result in blood-brain barrier damage, cognitive impairment, and even loss of normal motor function. Exosomes have been linked to the incidence and progression of brain disorders in recent research. As a result, a thorough knowledge of the interaction between exosomes and brain diseases may lead to the development of more effective therapeutic techniques that may be implemented in the clinic. The potential role of exosomes in brain diseases and the crosstalk between exosomes and other pathogenic processes were discussed in this paper. Simultaneously, we noted the delicate events in which exosomes as a media allow the brain to communicate with other tissues and organs in physiology and disease, and compiled a list of natural compounds that modulate exosomes, in order to further improve our understanding of exosomes and propose new ideas for treating brain disorders.

Brain Iron Dysregulation in Iron Deficiency Anemia-Related Restless Leg Syndrome Revealed by Neuron-Derived Extracellular Vesicles: A Case-Control Study

Brain iron deficiency (ID) and, to a degree, systemic ID have been implicated in restless leg syndrome (RLS) pathogenesis. Previously, we found increased ferritin in neuron-derived extracellular vesicles (NDEVs) in RLS, suggesting a mechanism for depleting intracellular iron by secreting ferritin-loaded NDEVs. In this study, we hypothesized that increased NDEV ferritin occurs even in RLS accompanied by systemic ID and that neuronal intracellular iron depletion in RLS also manifests as NDEV abnormalities in other iron regulatory proteins, specifically, decreased transferrin receptor (TfR) and increased ferroportin. To address these hypotheses, we studied 71 women with ID anemia, 36 with RLS, and 35 without RLS. Subjects with RLS again showed higher NDEV ferritin and also decreased TfR, suggesting diminished neuronal capacity for iron uptake. Findings inform a more complete understanding of the pathogenic role of neuronal iron homeostasis and dissociate it from peripheral ID. ANN NEUROL 2024;96:560-564.

Eudesmane-type sesquiterpenoids: Structural diversity and biological activity

Sesquiterpenoids are integral constituents of terpenoid-bearing plants, comprising a diverse and abundant class of natural compounds, among which eudesmane-type sesquiterpenoids have bicyclic structures that feature the fusion of two six-membered carbon rings, thereby attracting considerable attention. They are widespread in nature, with multifaceted biological activities such as anti-inflammatory, anticancer, antimicrobial, antimalarial, and insecticidal activities, thus gaining focus in life science research. The discovery and identification of these active compounds have laid a foundation for unraveling their potential medicinal value. In this review, we comprehensively explore the natural eudesmane-type sesquiterpenoids isolated (totaling 391 compounds) between 2016 and 2022, elucidating their chemical structures, plant distribution patterns, and pertinent biological properties. Accordingly, the study serves not only as a framework for researchers to thoroughly comprehend these compounds but also as a robust reference for future endeavors aimed at exploring the pharmaceutical potential and prospective applications of these molecules.

"Prion-like" seeding and propagation of oligomeric protein assemblies in neurodegenerative disorders

Intra- or extracellular aggregates of proteins are central pathogenic features in most neurodegenerative disorders. The accumulation of such proteins in diseased brains is believed to be the end-stage of a stepwise aggregation of misfolded monomers to insoluble cross-β fibrils via a series of differently sized soluble oligomers/protofibrils. Several studies have shown how α-synuclein, amyloid-β, tau and other amyloidogenic proteins can act as nucleating particles and thereby share properties with misfolded forms, or strains, of the prion protein. Although the roles of different protein assemblies in the respective aggregation cascades remain unclear, oligomers/protofibrils are considered key pathogenic species. Numerous observations have demonstrated their neurotoxic effects and a growing number of studies have indicated that they also possess seeding properties, enabling their propagation within cellular networks in the nervous system. The seeding behavior of oligomers differs between the proteins and is also affected by various factors, such as size, shape and epitope presentation. Here, we are providing an overview of the current state of knowledge with respect to the "prion-like" behavior of soluble oligomers for several of the amyloidogenic proteins involved in neurodegenerative diseases. In addition to providing new insight into pathogenic mechanisms, research in this field is leading to novel diagnostic and therapeutic opportunities for neurodegenerative diseases.

Essential New Complexity-Based Themes for Patient-Centered Diagnosis and Treatment of Dementia and Predementia in Older People: Multimorbidity and Multilevel Phenomenology

Dementia is a highly prevalent condition with devastating clinical and socioeconomic sequela. It is expected to triple in prevalence by 2050. No treatment is currently known to be effective. Symptomatic late-onset dementia and predementia (SLODP) affects 95% of patients with the syndrome. In contrast to trials of pharmacological prevention, no treatment is suggested to remediate or cure these symptomatic patients. SLODP but not young onset dementia is intensely associated with multimorbidity (MUM), including brain-perturbating conditions (BPCs). Recent studies showed that MUM/BPCs have a major role in the pathogenesis of SLODP. Fortunately, most MUM/BPCs are medically treatable, and thus, their treatment may modify and improve SLODP, relieving suffering and reducing its clinical and socioeconomic threats. Regrettably, the complex system features of SLODP impede the diagnosis and treatment of the potentially remediable conditions (PRCs) associated with them, mainly due to failure of pattern recognition and a flawed diagnostic workup. We suggest incorporating two SLODP-specific conceptual themes into the diagnostic workup: MUM/BPC and multilevel phenomenological themes. By doing so, we were able to improve the diagnostic accuracy of SLODP components and optimize detecting and favorably treating PRCs. These revolutionary concepts and their implications for remediability and other parameters are discussed in the paper.

Long Non-Coding RNAs and Alzheimer's Disease: Towards Personalized Diagnosis

Alzheimer's disease (AD), a neurodegenerative disorder characterized by progressive cognitive decline, is the most common form of dementia. Currently, there is no single test that can diagnose AD, especially in understudied populations and developing countries. Instead, diagnosis is based on a combination of medical history, physical examination, cognitive testing, and brain imaging. Exosomes are extracellular nanovesicles, primarily composed of RNA, that participate in physiological processes related to AD pathogenesis such as cell proliferation, immune response, and neuronal and cardiovascular function. However, the identification and understanding of the potential role of long non-coding RNAs (lncRNAs) in AD diagnosis remain largely unexplored. Here, we clinically, cognitively, and genetically characterized a sample of 15 individuals diagnosed with AD (cases) and 15 controls from Barranquilla, Colombia. Advanced bioinformatics, analytics and Machine Learning (ML) techniques were used to identify lncRNAs differentially expressed between cases and controls. The expression of 28,909 lncRNAs was quantified. Of these, 18 were found to be differentially expressed and harbored in pivotal genes related to AD. Two lncRNAs, ENST00000608936 and ENST00000433747, show promise as diagnostic markers for AD, with ML models achieving > 95% sensitivity, specificity, and accuracy in both the training and testing datasets. These findings suggest that the expression profiles of lncRNAs could significantly contribute to advancing personalized AD diagnosis in this community, offering promising avenues for early detection and follow-up.

Thermodynamics of oligomerization and Helix-to-sheet structural transition of amyloid β-protein on anionic phospholipid vesicles

Understanding oligomerization and aggregation of the amyloid-β protein is important to elucidate the pathological mechanisms of Alzheimer's disease, and lipid membranes play critical roles in this process. In addition to studies reported by other groups, our group has also reported that the negatively-charged lipid bilayers with a high positive curvature induced α-helix-to-β-sheet conformational transitions of amyloid-β-(1-40) upon increase in protein density on the membrane surface and promoted amyloid fibril formation of the protein. Herein, we investigated detailed mechanisms of the conformational transition and oligomer formation of the amyloid-β protein on the membrane surface. Changes in the fractions of the three protein conformers (free monomer, membrane-bound α-helix-rich conformation, and β-sheet-rich conformation) were determined from the fluorescent spectral changes of the tryptophan probe in the protein. The helix-to-sheet structural transition on the surface was described by a thermodynamic model of octamer formation driven by entropic forces including hydrophobic interactions. These findings provide useful information for understanding the self-assembly of amyloidogenic proteins on lipid membrane surfaces.

Profiling of microglial-originated microvesicles to unearthing their lurking potential as potent foreseeable biomarkers for the diagnosis of Alzheimer's disease: A systematic review

BACKGROUND

Alzheimer's Disease is a neurodegenerative disease characterized by accumulation of phosphorylated tau and amyloid deposits within the brain tissues in the elderly population. Numerous studies established that amassment of these toxic accretions within the brain tissues initiates neuronal demise and synaptic impairment which becomes the underlying basis for memory loss and cognitive abnormalities in these patients.

HYPOTHESIS

Hypoxia, oxidative stress, and inflammation are commonly encountered perils in the neuronal milieu that derail the neuron-synapse interactions and maneuver them to undergo apoptosis. A spinoff from neuronal desecration is microglial activation which forms a cardinal role in mounting innate immune defenses for warding off and reversing off toxic stimulus encountered.

RESULTS

A potential ramification of microglial activation in this context is assembly, processing and exuding of micro-vesicles into the extracellular space. These micro-vesicles will be packaged with amyloid and tau deposits which accumulate intracellularly within microglial cells secondary to their professional scavenging function. These microglial MVs are prone to seed tau and amyloid beta into the surrounding neuron-synapse framework, thus are implicated in spreading the disease pathology in AD.

CONCLUSIONS

Therefore, these MVs can be considered as an omen for disease initiation, progression, monitoring as well gauging the treatment response in the clinical AD cohorts. We speculate future research studies to unmask the dormant potential of these microglial MVs as reliable markers for diagnosis, evaluating the disease progression as well as treatment in AD. This will open the door for early diagnosis of AD so as to prioritize management and optimize clinical outcomes..