Potential Exosome Biomarkers for Parkinson's Disease Diagnosis: A Systematic Review and Meta-Analysis.

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide. Given its prevalence, reliable biomarkers for early diagnosis are required. Exosomal proteins within extracellular nanovesicles are promising candidates for diagnostic, screening, prognostic, and disease monitoring purposes in neurological diseases such as PD. This review aims to evaluate the potential of extracellular vesicle proteins or miRNAs as biomarkers for PD. A comprehensive literature search until January 2024 was conducted across multiple databases, including PubMed, EMBASE, Web of Science, and Cochrane Library, to identify relevant studies reporting exosome biomarkers in blood samples from PD patients. Out of 417 articles screened, 47 studies were selected for analysis. Among exosomal protein biomarkers, α-synuclein, tau, Amyloid ß 1-42, and C-X-C motif chemokine ligand 12 (CXCL12) were identified as significant markers for PD. Concerning miRNA biomarkers, miRNA-24, miR-23b-3p, miR-195-3p, miR-29c, and mir-331-5p are promising across studies. α-synuclein exhibited increased levels in PD patients compared to control groups in twenty-one studies, while a decrease was observed in three studies. Our meta-analysis revealed a significant difference in total exosomal α-synuclein levels between PD patients and healthy controls (standardized mean difference [SMD] = 1.369, 95% confidence interval [CI] = 0.893 to 1.846, p < 0.001), although these results are limited by data availability. Furthermore, α-synuclein levels significantly differ between PD patients and healthy controls (SMD = 1.471, 95% CI = 0.941 to 2.002, p < 0.001). In conclusion, certain exosomal proteins and multiple miRNAs could serve as potential biomarkers for diagnosis, prognosis prediction, and assessment of disease progression in PD.

Depressive-like Behaviors Induced by mGluR5 Reduction in 6xTg in Mouse Model of Alzheimer's Disease.

Alzheimer's disease (AD) is one representative dementia characterized by the accumulation of amyloid beta (Aß) plaques and neurofibrillary tangles (NFTs) in the brain, resulting in cognitive decline and memory loss. AD is associated with neuropsychiatric symptoms, including major depressive disorder (MDD). Recent studies showed a reduction in mGluR5 expression in the brains of stress-induced mice models and individuals with MDD compared to controls. In our study, we identified depressive-like behavior and memory impairment in a mouse model of AD, specifically in the 6xTg model with tau and Aß pathologies. In addition, we investigated the expression of mGluR5 in the brains of 6xTg mice using micro-positron emission tomography (micro-PET) imaging, histological analysis, and Western blot analysis, and we observed a decrease in mGluR5 levels in the brains of 6xTg mice compared to wild-type (WT) mice. Additionally, we identified alterations in the ERK/AKT/GSK-3ß signaling pathway in the brains of 6xTg mice. Notably, we identified a significant negative correlation between depressive-like behavior and the protein level of mGluR5 in 6xTg mice. Additionally, we also found a significant positive correlation between depressive-like behavior and AD pathologies, including phosphorylated tau and Aß. These findings suggested that abnormal mGluR5 expression and AD-related pathologies were involved in depressive-like behavior in the 6xTg mouse model. Further research is warranted to elucidate the underlying mechanisms and explore potential therapeutic targets in the intersection of AD and depressive-like symptoms.

Potential Inflammatory Biomarkers for Major Depressive Disorder Related to Suicidal Behaviors: A Systematic Review.

Major depressive disorder (MDD) is a highly prevalent psychiatric condition affecting an estimated 280 million individuals globally. Despite the occurrence of suicidal behaviors across various psychiatric conditions, MDD is distinctly associated with the highest risk of suicide attempts and death within this population. In this study, we focused on MDD to identify potential inflammatory biomarkers associated with suicidal risk, given the relationship between depressive states and suicidal ideation. Articles published before June 2023 were searched in PubMed, Embase, Web of Science, and the Cochrane Library to identify all relevant studies reporting blood inflammatory biomarkers in patients with MDD with suicide-related behaviors. Of 571 articles, 24 were included in this study. Overall, 43 significant biomarkers associated with MDD and suicide-related behaviors were identified. Our study provided compelling evidence of significant alterations in peripheral inflammatory factors in MDD patients with suicide-related behaviors, demonstrating the potential roles of interleukin (IL)-1ß, IL-6, C-reactive protein, C-C motif chemokine ligand 2, and tumor necrosis factor-α as biomarkers. These findings underscore the intricate relationship between the inflammatory processes of these biomarkers and their interactions in MDD with suicidal risk.

Neurodegenerative Changes in the Brains of the 5xFAD Alzheimer's Disease Model Mice Investigated by High-Field and High-Resolution Magnetic Resonance Imaging and Multi-Nuclei Magnetic Resonance Spectroscopy.

This study aimed to investigate morphological and metabolic changes in the brains of 5xFAD mice. Structural magnetic resonance imaging (MRI) and 1H magnetic resonance spectroscopy (MRS) were obtained in 10- and 14-month-old 5xFAD and wild-type (WT) mice, while 31P MRS scans were acquired in 11-month-old mice. Significantly reduced gray matter (GM) was identified by voxel-based morphometry (VBM) in the thalamus, hypothalamus, and periaqueductal gray areas of 5xFAD mice compared to WT mice. Significant reductions in N-acetyl aspartate and elevation of myo-Inositol were revealed by the quantification of MRS in the hippocampus of 5xFAD mice, compared to WT. A significant reduction in NeuN-positive cells and elevation of Iba1- and GFAP-positive cells supported this observation. The reduction in phosphomonoester and elevation of phosphodiester was observed in 11-month-old 5xFAD mice, which might imply a sign of disruption in the membrane synthesis. Commonly reported 1H MRS features were replicated in the hippocampus of 14-month-old 5xFAD mice, and a sign of disruption in the membrane synthesis and elevation of breakdown were revealed in the whole brain of 5xFAD mice by 31P MRS. GM volume reduction was identified in the thalamus, hypothalamus, and periaqueductal gray areas of 5xFAD mice.

Effect of cx-DHED on Abnormal Glucose Transporter Expression Induced by AD Pathologies in the 5xFAD Mouse Model.

Alzheimer's disease (AD) is a form of dementia associated with abnormal glucose metabolism resulting from amyloid-beta (Aß) plaques and intracellular neurofibrillary tau protein tangles. In a previous study, we confirmed that carboxy-dehydroevodiamine∙HCl (cx-DHED), a derivative of DHED, was effective at improving cognitive impairment and reducing phosphorylated tau levels and synaptic loss in an AD mouse model. However, the specific mechanism of action of cx-DHED is unclear. In this study, we investigated how the cx-DHED attenuates AD pathologies in the 5xFAD mouse model, focusing particularly on abnormal glucose metabolism. We analyzed behavioral changes and AD pathologies in mice after intraperitoneal injection of cx-DHED for 2 months. As expected, cx-DHED reversed memory impairment and reduced Aß plaques and astrocyte overexpression in the brains of 5xFAD mice. Interestingly, cx-DHED reversed the abnormal expression of glucose transporters in the brains of 5xFAD mice. In addition, otherwise low O-GlcNac levels increased, and the overactivity of phosphorylated GSK-3ß decreased in the brains of cx-DHED-treated 5xFAD mice. Finally, the reduction in synaptic proteins was found to also improve by treatment with cx-DHED. Therefore, we specifically demonstrated the protective effects of cx-DHED against AD pathologies and suggest that cx-DHED may be a potential therapeutic drug for AD.

MicroPET Imaging Assessment of Brain Tau and Amyloid Deposition in 6 × Tg Alzheimer's Disease Model Mice.

Alzheimer's disease (AD) is characterized by the deposition of extracellular amyloid plaques and intracellular accumulation of neurofibrillary tangles (NFT). Amyloid beta (Aß) and tau imaging are widely used for diagnosing and monitoring AD in clinical settings. We evaluated the pathology of a recently developed 6 × Tg - AD (6 × Tg) mouse model by crossbreeding 5 × FAD mice with mice expressing mutant (P301L) tau protein using micro-positron emission tomography (PET) image analysis. PET studies were performed in these 6 × Tg mice using [18F]Flutemetamol, which is an amyloid PET radiotracer; [18F]THK5351 and [18F]MK6240, which are tau PET radiotracers; moreover, [18F]DPA714, which is a translocator protein (TSPO) radiotracer, and comparisons were made with age-matched mice of their respective parental strains. We compared group differences in standardized uptake value ratio (SUVR), kinetic parameters, biodistribution, and histopathology. [18F]Flutemetamol images showed prominent cortical uptake and matched well with 6E10 staining images from 2-month-old 6 × Tg mice. [18F]Flutemetamol images showed a significant correlation with [18F]DPA714 in the cortex and hippocampus. [18F]THK5351 images revealed prominent hippocampal uptake and matched well with AT8 immunostaining images in 4-month-old 6 × Tg mice. Moreover, [18F]THK5351 images were confirmed using [18F]MK6240, which revealed significant correlations in the cortex and hippocampus. Uptake of [18F]THK5351 or [18F]MK6240 was highly correlated with [18F]Flutemetamol in 4-month-old 6 × Tg mice. In conclusion, PET imaging revealed significant age-related uptake of Aß, tau, and TSPO in 6 × Tg mice, which was highly correlated with age-dependent pathology.

Potential Biomarkers for Post-Stroke Cognitive Impairment: A Systematic Review and Meta-Analysis.

Stroke is a primary debilitating disease in adults, occurring in 15 million individuals each year and causing high mortality and disability rates. The latest estimate revealed that stroke is currently the second leading cause of death worldwide. Post-stroke cognitive impairment (PSCI), one of the major complications after stroke, is frequently underdiagnosed. However, stroke has been reported to increase the risk of cognitive impairment by at least five to eight times. In recent decades, peripheral blood molecular biomarkers for stroke have emerged as diagnostic, prognostic, and therapeutic targets. In this study, we aimed to evaluate some blood-derived proteins for stroke, especially related to brain damage and cognitive impairments, by conducting a systematic review and meta-analysis and discussing the possibility of these proteins as biomarkers for PSCI. Articles published before 26 July 2021 were searched in PubMed, Embase, the Web of Science, and the Cochrane Library to identify all relevant studies reporting blood biomarkers in patients with stroke. Among 1820 articles, 40 were finally identified for this study. We meta-analyzed eight peripheral biomarker candidates: homocysteine (Hcy), high-density lipoprotein cholesterol (HDL-C), C-reactive protein (CRP), low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), triglyceride (TG), uric acid, and glycated hemoglobin (HbA1c). The Hcy, CRP, TC, and LDL-C levels were significantly higher in patients with PSCI than in the non-PSCI group; however, the HDL-C, TG, uric acid, and HbA1c levels were not different between the two groups. Based on our findings, we suggest the Hcy, CRP, TC, and LDL-C as possible biomarkers in patients with post-stroke cognitive impairment. Thus, certain blood proteins could be suggested as effective biomarkers for PSCI.

RAPGEF2 mediates oligomeric Aß-induced synaptic loss and cognitive dysfunction in the 3xTg-AD mouse model of Alzheimer's disease.

AIMS: Amyloid-ß (Aß) oligomers trigger synaptic degeneration that precedes plaque and tangle pathology. However, the signalling molecules that link Aß oligomers to synaptic pathology remain unclear. Here, we addressed the potential role of RAPGEF2 as a novel signalling molecule in Aß oligomer-induced synaptic and cognitive impairments in human-mutant amyloid precursor protein (APP) mouse models of Alzheimer's disease (AD). METHODS: To investigate the role of RAPGEF2 in Aß oligomer-induced synaptic and cognitive impairments, we utilised a combination of approaches including biochemistry, molecular cell biology, light and electron microscopy, behavioural tests with primary neuron cultures, multiple AD mouse models and post-mortem human AD brain tissue. RESULTS: We found significantly elevated RAPGEF2 levels in the post-mortem human AD hippocampus. RAPGEF2 levels also increased in the transgenic AD mouse models, generating high levels of Aß oligomers before exhibiting synaptic and cognitive impairment. RAPGEF2 upregulation activated the downstream effectors Rap2 and JNK. In cultured hippocampal neurons, oligomeric Aß treatment increased the fluorescence intensity of RAPGEF2 and reduced the number of dendritic spines and the intensities of synaptic marker proteins, while silencing RAPGEF2 expression blocked Aß oligomer-induced synapse loss. Additionally, the in vivo knockdown of RAPGEF2 expression in the AD hippocampus prevented cognitive deficits and the loss of excitatory synapses. CONCLUSIONS: These findings demonstrate that the upregulation of RAPGEF2 levels mediates Aß oligomer-induced synaptic and cognitive disturbances in the AD hippocampus. We propose that an early intervention regarding RAPGEF2 expression may have beneficial effects on early synaptic pathology and memory loss in AD.

Therapeutic Potential of Magnetic Nanoparticle-Based Human Adipose-Derived Stem Cells in a Mouse Model of Parkinson's Disease.

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by the loss of dopaminergic neurons in the substantia nigra. Several treatments for PD have focused on the management of physical symptoms using dopaminergic agents. However, these treatments induce various adverse effects, including hallucinations and cognitive impairment, owing to non-targeted brain delivery, while alleviating motor symptoms. Furthermore, these therapies are not considered ultimate cures owing to limited brain self-repair and regeneration abilities. In the present study, we aimed to investigate the therapeutic potential of human adipose-derived stem cells (hASCs) using magnetic nanoparticles in a 6-hydroxydopamine (6-OHDA)-induced PD mouse model. We used the Maestro imaging system and magnetic resonance imaging (MRI) for in vivo tracking after transplantation of magnetic nanoparticle-loaded hASCs to the PD mouse model. The Maestro imaging system revealed strong hASCs signals in the brains of PD model mice. In particular, MRI revealed hASCs distribution in the substantia nigra of hASCs-injected PD mice. Behavioral evaluations, including apomorphine-induced rotation and rotarod performance, were significantly recovered in hASCs-injected 6-OHDA induced PD mice when compared with saline-treated counterparts. Herein, we investigated whether hASCs transplantation using magnetic nanoparticles recovered motor functions through targeted brain distribution in a 6-OHDA induced PD mice. These results indicate that magnetic nanoparticle-based hASCs transplantation could be a potential therapeutic strategy in PD.

Therapeutic Potential of Repeated Intravenous Transplantation of Human Adipose-Derived Stem Cells in Subchronic MPTP-Induced Parkinson's Disease Mouse Model.

Parkinson's disease (PD) is the second most common neurodegenerative disease, which is clinically and pathologically characterized by motor dysfunction and the loss of dopaminergic neurons in the substantia nigra, respectively. PD treatment with stem cells has long been studied by researchers; however, no adequate treatment strategy has been established. The results of studies so far have suggested that stem cell transplantation can be an effective treatment for PD. However, PD is a progressively deteriorating neurodegenerative disease that requires long-term treatment, and this has been insufficiently studied. Thus, we aimed to investigate the therapeutic potential of human adipose-derived stem cells (hASC) for repeated vein transplantation over long-term in an animal model of PD. In 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD model mice, hASCs were administered on the tail vein six times at two-week intervals. After the last injection of hASCs, motor function significantly improved. The number of dopaminergic neurons present in the nigrostriatal pathway was recovered using hASC transplantation. Moreover, the administration of hASC restored altered dopamine transporter expression and increased neurotrophic factors, such as brain-derived neurotrophic factor (BDNF) and glial cell-derived neurotrophic factor (GDNF), in the striatum. Overall, this study suggests that repeated intravenous transplantation of hASC may exert therapeutic effects on PD by restoring BDNF and GDNF expressions, protecting dopaminergic neurons, and maintaining the nigrostriatal pathway.

Serum Tau Proteins as Potential Biomarkers for the Assessment of Alzheimer's Disease Progression.

Total tau (t-tau) and phosphorylated tau (p-tau) protein elevations in cerebrospinal fluid (CFS) are well-established hallmarks of Alzheimer's disease (AD), while the associations of serum t-tau and p-tau levels with AD have been inconsistent across studies. To identify more accessible non-invasive AD biomarkers, we measured serum tau proteins and associations with cognitive function in age-matched controls (AMC, n = 26), mild cognitive impairment group (MCI, n = 30), and mild-AD group (n = 20) according to the Mini-mental State Examination (MMSE), Clinical Dementia Rating (CDR), and Global Deterioration Scale (GDS) scores. Serum t-tau, but not p-tau, was significantly higher in the mild-AD group than AMC subjects (p < 0.05), and there were significant correlations of serum t-tau with MMSE and GDS scores. Receiver operating characteristic (ROC) analysis distinguished mild-AD from AMC subjects with moderate sensitivity and specificity (AUC = 0.675). We speculated that tau proteins in neuronal cell-derived exosomes (NEX) isolated from serum would be more strongly associated with brain tau levels and disease characteristics, as these exosomes can penetrate the blood-brain barrier. Indeed, ELISA and Western blotting indicated that both NEX t-tau and p-tau (S202) were significantly higher in the mild-AD group compared to AMC (p < 0.05) and MCI groups (p < 0.01). In contrast, serum amyloid ß (Aß1-42) was lower in the mild-AD group compared to MCI groups (p < 0.001). During the 4-year follow-up, NEX t-tau and p-tau (S202) levels were correlated with the changes in GDS and MMSE scores. In JNPL3 transgenic (Tg) mice expressing a human tau mutation, t-tau and p-tau expression levels in NEX increased with neuropathological progression, and NEX tau was correlated with tau in brain tissue exosomes (tEX), suggesting that tau proteins reach the circulation via exosomes. Taken together, our data suggest that serum tau proteins, especially NEX tau proteins, are useful biomarkers for monitoring AD progression.

Therapeutic Effects of Human Amniotic Epithelial Stem Cells in a Transgenic Mouse Model of Alzheimer's Disease.

Alzheimer's disease (AD), a progressive neurodegenerative disorder, is characterized clinically by cognitive decline and pathologically by the development of amyloid plaques. AD is the most common cause of dementia among older people. However, there is currently no cure for AD. In this study, we aimed to elucidate the therapeutic effects of human amniotic epithelial stem cells (hAESCs) in a transgenic mouse model of AD. Tg2576 transgenic (Tg) mice underwent behavioral tests, namely the Morris water maze and Y-maze tests, to assess their cognitive function. In the Morris water maze test, hAESC-treated Tg mice exhibited significantly shorter escape latencies than vehicle-treated Tg mice. In the Y-maze test, hAESC-treated Tg mice exhibited significantly higher rate of spontaneous alteration than vehicle-treated Tg mice, while the total number of arm entries did not differ between the groups. Furthermore, Congo red staining revealed that hAESCs injection reduced the number of amyloid plaques present in the brains of Tg mice. Finally, beta-secretase (BACE) activity was significantly decreased in Tg mice at 60 min after hAESCs injection. In this study, we found that intracerebral injection of hAESCs alleviated cognitive impairment in a Tg2576 mouse model of AD. Our results indicate that hAESCs injection reduced amyloid plaques caused by reduced BACE activity. These results indicate that hAESCs may be a useful therapeutic agent for the treatment of AD-related memory impairment.

Synthesis and evaluation of novel potent TSPO PET ligands with 2-phenylpyrazolo[1,5-a]pyrimidin-3-yl acetamide.

Translocator protein (TSPO) expression is closely related with neuroinflammation and neuronal damage which might cause several central nervous system diseases. Herein, a series of TSPO ligands (11a-c and 13a-d) with a 2-phenylpyrazolo[1,5-a]pyrimidin-3-yl acetamide structure were prepared and evaluated via an in vitro binding assay. Most of the novel ligands exhibited a nano-molar affinity for TSPO, which was better than that of DPA-714. Particularly, 11a exhibited a subnano-molar TSPO binding affinity with suitable lipophilicity for in vivo brain studies. After radiolabeling with fluorine-18, [18F]11a was used for a dynamic positron emission tomography (PET) study in a rat LPS-induced neuroinflammation model; the inflammatory lesion was clearly visualized with a superior target-to-background ratio compared to [18F]DPA-714. An immunohistochemical examination of the dissected brains confirmed that the uptake location of [18F]11a in the PET study was consistent with a positively activated microglia region. This study proved that [18F]11a could be employed as a potential PET tracer for detecting neuroinflammation and could give possibility for diagnosis of other diseases, such as cancers related with TSPO expression.

Distinct amyloid precursor protein processing machineries of the olfactory system.

Processing of amyloid precursor protein (APP) occurs through sequential cleavages first by ß-secretase and then by the γ-secretase complex. However, abnormal processing of APP leads to excessive production of ß-amyloid (Aß) in the central nervous system (CNS), an event which is regarded as a primary cause of Alzheimer's disease (AD). In particular, gene mutations of the γ-secretase complex-which contains presenilin 1 or 2 as the catalytic core-could trigger marked Aß accumulation. Olfactory dysfunction usually occurs before the onset of typical AD-related symptoms (eg, memory loss or muscle retardation), suggesting that the olfactory system may be one of the most vulnerable regions to AD. To date however, little is known about why the olfactory system is affected so early by AD prior to other regions. Thus, we examined the distribution of secretases and levels of APP processing in the olfactory system under either healthy or pathological conditions. Here, we show that the olfactory system has distinct APP processing machineries. In particular, we identified higher expressions levels and activity of γ-secretase in the olfactory epithelium (OE) than other regions of the brain. Moreover, APP c-terminal fragments (CTF) are markedly detected. During AD progression, we note increased expression of presenilin2 of γ-secretases in the OE, not in the OB, and show that neurotoxic Aß*56 accumulates more quickly in the OE. Taken together, these results suggest that the olfactory system has distinct APP processing machineries under healthy and pathological conditions. This finding may provide a crucial understanding of the unique APP-processing mechanisms in the olfactory system, and further highlights the correlation between olfactory deficits and AD symptoms.

Involvement of 14-3-3 in tubulin instability and impaired axon development is mediated by Tau.

14-3-3 proteins act as adapters that exert their function by interacting with their various protein partners. 14-3-3 proteins have been implicated in a variety of human diseases including neurodegenerative diseases. 14-3-3 proteins have recently been reported to be abundant in the neurofibrillary tangles (NFTs) observed inside the neurons of brains affected by Alzheimer's disease (AD). These NFTs are mainly constituted of phosphorylated Tau protein, a microtubule-associated protein known to bind 14-3-3. Despite this indication of 14-3-3 protein involvement in the AD pathogenesis, the role of 14-3-3 in the Tauopathy remains to be clarified. In the present study, we shed light on the role of 14-3-3 proteins in the molecular pathways leading to Tauopathies. Overexpression of the 14-3-3σ isoform resulted in a disruption of the tubulin cytoskeleton and prevented neuritic outgrowth in neurons. NMR studies validated the phosphorylated residues pSer214 and pSer324 in Tau as the 2 primary sites for 14-3-3 binding, with the crystal structure of 14-3-3σ in complex with Tau-pSer214 and Tau-pSer324 revealing the molecular details of the interaction. These data suggest a rationale for a possible pharmacologic intervention of the Tau/14-3-3 interaction.

Therapeutic potential of human adipose-derived stem cells in neurological disorders.

Stem cell therapy has been noted as a novel strategy to various diseases including neurological disorders such as Alzheimer's disease, Parkinson's disease, stroke, amyotrophic lateral sclerosis, and Huntington's disease that have no effective treatment available to date. The adipose-derived stem cells (ASCs), mesenchymal stem cells (MSCs) isolated from adipose tissue, are well known for their pluripotency with the ability to differentiate into various types of cells and immuno-modulatory property. These biological features make ASCs a promising source for regenerative cell therapy in neurological disorders. Here we discuss the recent progress of regenerative therapies in various neurological disorders utilizing ASCs.

The therapeutic effects of human adipose-derived stem cells in Alzheimer's disease mouse models.

Alzheimer's disease (AD) is an irreversible neurodegenerative disease, still lacking proper clinical treatment. Therefore, many researchers have focused on the possibility of therapeutic use of stem cells for AD. Adipose-derived stem cells (ASCs), mesenchymal stem cells (MSCs) isolated from adipose tissue, are well known for their pluripotency and their ability to differentiate into multiple tissue types and have immune modulatory properties similar to those of MSCs from other origins. Because of their biological properties, ASCs can be considered for cell therapy and neuroregeneration. Our recent results clearly showed the therapeutic potential of these cells after transplantation into Tg2576 mice (an AD mouse model). Intravenously or intracerebrally transplanted human ASCs (hASCs) greatly improved the memory impairment and the neuropathology, suggesting that hASCs have a high therapeutic potential for AD.

Dehydroevodiamine·HCl Improves Stress-Induced Memory Impairments and Depression Like Behavior in Rats.

Dehydroevodiamine·HCl (DHED) has been reported to prevent memory impairment and neuronal cell loss in a rat model with cognitive disturbance. We investigated the effect of DHED on memory impairment and behavioral abnormality caused by stress. We demonstrated that DHED can improve stress-induced memory impairments and depression-like behaviors by using open-field test, Y-maze test and forced swimming test. DHED treatment significantly recovered the decreases in the levels of neural cell adhesion molecule (NCAM) proteins caused by stress and the decreases in cell viability. Our results suggested that DHED is a potential drug candidate for neuronal death, memory impairment and depression induced by stress.

Amyloid-ß peptide-induced extracellular S100A9 depletion is associated with decrease of antimicrobial peptide activity in human THP-1 monocytes.

BACKGROUND: S100A9 protein (myeloid-related protein MRP14, also referred to as calgranulin B) is a reliable marker of inflammation, an important proinflammatory factor of innate immunity and acts as an additional antimicrobial peptide in the innate immune system. Evidence indicates that S100A9 contributes to Alzheimer's disease (AD) pathology, although the precise mechanisms are not clear. METHODS: We were interested to study the mechanisms of S100A9 release upon Aß1-42 stimulation, the potential roles of extracellular S100A9 depletion in Aß-induced cytotoxicity, and the interaction with innate immune response in THP-1 monocytic cells that have been challenged with mostly Aß1-42 monomers instead of oligomers. We used protein preparation, Ca(2+) influx fluorescence imaging, MTT assay, siRNA knockdown, colony forming units (CFUs) assay and western blotting techniques to perform our study. RESULTS: Aß1-42 monomers elicited a marked decrease of S100A9 release into the cell culture supernatant in a dose-dependent manner in human THP-1 monocytes. This reduction of S100A9 release was accompanied by an increase of intracellular Ca(2+) level. Aß1-42-mediated decrease of S100A9 release was not associated with Aß1-42-induced cytotoxicity as measured by MTT reduction assay. This observation was confirmed with the recombinant S100A9, which had little effect on Aß1-42-induced cytotoxicity. Moreover, depletion of S100A9 with siRNA did not significantly evoke the cell toxicity. On the other hand, Aß1-42-induced extracellular S100A9 depletion resulted in decreased antimicrobial activity of the culture supernatant after Aß1-42 stimulation. Immunodepletion of S100A9 with anti-S100A9 also decreased the antimicrobial peptide activity of the vehicle treated culture supernatant. Consistently, the recombinant S100A9 clearly elicited the antimicrobial peptide activity in vitro, confirming the observed antimicrobial activity of S100A9 in the culture supernatant. CONCLUSION: Collectively, our findings suggest that the mostly monomeric form of Aß1-42 negatively regulates the innate immune system by down-regulating the secretion of S100A9, which is likely a main mediator of antimicrobial activity in the conditioned media of human THP-1 monocytes.

GFAP as a Potential Biomarker for Alzheimer's Disease: A Systematic Review and Meta-Analysis.

Blood biomarkers have been considered tools for the diagnosis, prognosis, and monitoring of Alzheimer's disease (AD). Although amyloid-ß peptide (Aß) and tau are primarily blood biomarkers, recent studies have identified other reliable candidates that can serve as measurable indicators of pathological conditions. One such candidate is the glial fibrillary acidic protein (GFAP), an astrocytic cytoskeletal protein that can be detected in blood samples. Increasing evidence suggests that blood GFAP levels can be used to detect early-stage AD. In this systematic review and meta-analysis, we aimed to evaluate GFAP in peripheral blood as a biomarker for AD and provide an overview of the evidence regarding its utility. Our analysis revealed that the GFAP level in the blood was higher in the Aß-positive group than in the negative groups, and in individuals with AD or mild cognitive impairment (MCI) compared to the healthy controls. Therefore, we believe that the clinical use of blood GFAP measurements has the potential to accelerate the diagnosis and improve the prognosis of AD.