Sera Of Alzheimer's Disease Patients Research Articles

Microglial ApoD-induced NLRC4 inflammasome activation promotes Alzheimer's disease progression.

Alzheimer's disease (AD) is a progressive neurodegenerative disease with no effective therapies. It is well known that chronic neuroinflammation plays a critical role in the onset and progression of AD. Well-balanced neuronal-microglial interactions are essential for brain functions. However, determining the role of microglia-the primary immune cells in the brain-in neuroinflammation in AD and the associated molecular basis has been challenging. Inflammatory factors in the sera of AD patients were detected and their association with microglia activation was analyzed. The mechanism for microglial inflammation was investigated. IL6 and TNF-α were found to be significantly increased in the AD stage. Our analysis revealed that microglia were extensively activated in AD cerebra, releasing sufficient amounts of cytokines to impair the neural stem cells (NSCs) function. Moreover, the ApoD-induced NLRC4 inflammasome was activated in microglia, which gave rise to the proinflammatory phenotype. Targeting the microglial ApoD promoted NSC self-renewal and inhibited neuron apoptosis. These findings demonstrate the critical role of ApoD in microglial inflammasome activation, and for the first time reveal that microglia-induced inflammation suppresses neuronal proliferation. Our studies establish the cellular basis for microglia activation in AD progression and shed light on cellular interactions important for AD treatment.

Circulating Exosomes from Alzheimer's Disease Suppress Vascular Endothelial-Cadherin Expression and Induce Barrier Dysfunction in Recipient Brain Microvascular Endothelial Cell.

Blood-brain barrier (BBB) breakdown is a crucial aspect of Alzheimer's disease (AD) progression. Dysfunction in BBB is primarily caused by impaired tight junction and adherens junction proteins in brain microvascular endothelial cells (BMECs). The role of adherens junctions in AD-related BBB dysfunction remains unclear. Exosomes from senescent cells have unique characteristics and contribute to modulating the phenotype of recipient cells. However, it remains unknown if and how these exosomes cause BMEC dysfunction in AD. This study aimed to investigate the impact of AD circulating exosomes on brain endothelial dysfunction. Exosomes were isolated from sera of AD patients and age- and sex-matched cognitively normal controls using size-exclusion chromatography. The study measured the biomechanical nature of BMECs' endothelial barrier, the lateral binding forces between live BMECs. Paracellular expressions of the key adherens junction protein vascular endothelial (VE)-cadherin were visualized in BMEC cultures and a 3D BBB model using human BMECs and pericytes. VE-cadherin signals were also examined in brain tissues from AD patients and normal controls. Circulating exosomes from AD patients reduced VE-cadherin expression levels and impaired barrier function in recipient BMECs. Immunostaining analysis demonstrated that AD exosomes damaged VE-cadherin integrity in a 3D microvascular tubule formation model. The study found that AD exosomes weakened BBB integrity depending on their RNA content. Additionally, diminished microvascular VE-cadherin expression was observed in AD brains compared to controls. These findings highlight the significant role of circulating exosomes from AD patients in damaging adherens junctions of recipient BMECs, dependent on exosomal RNA.

A Novel Serum-Based Diagnosis of Alzheimer's Disease Using an Advanced Phage-Based Biochip.

55 million people worldwide suffer from Alzheimer's disease (AD). A definitive diagnosis of AD is made postmortem after a neuropathological examination of the brain. There is an urgent need for an innovative, noninvasive methodology that allows for an early and reliable diagnosis. Several engineered phages that recognized Aβ-autoantibodies present in the sera of AD patients are previously identified. Here, novel phages are tested for their ability to accurately discriminate AD sera using immunophage-polymerase chain reaction in a miniatured biochip. It is found that five of the six phages analyzed discriminate between healthy controls and AD patients. Further, by combining the response of two phages, non-AD and severe AD cases are identified with 100% accuracy and mild-to-moderate cases with 90% accuracy. While the number of cases used here are relatively small and can be confirmed in larger cohorts, this first-of-a-kind system represents an innovative methodology with the potential of having a major impact in the AD field: from a clinical perspective, it can aid physicians in making an accurate AD diagnosis; from a research perspective, it can be used as a surrogate for AD clinical trials.

Platelet-derived extracellular vesicles are increased in sera of Alzheimer's disease patients, as revealed by Tim4-based assays.

Alzheimer's disease (AD) is the most common form of dementia, characterized by the accumulation of β‐amyloid plaques and the formation of neurofibrillary tangles. Extracellular vesicles (EVs) are small vesicles surrounded by a lipid bilayer membrane, which may be involved in the progression of AD. Glycans are essential building blocks of EVs, and we hypothesized that EV glycans may reflect pathological conditions of various diseases. Here, we performed glycan profiling of EVs prepared from sera of three AD patients (APs) compared to three healthy donors (HDs) using lectin microarray. Distinct glycan profiles were observed. Mannose‐binding lectins exhibited significantly higher signals for AP‐derived EVs than HD‐derived EVs. Lectin blotting using mannose‐binding lectin (rPALa) showed a single protein band at ~ 80 kDa exclusively in AP‐derived EVs. LC‐MS/MS analysis identified a protein band precipitated by rPALa as CD61, a marker of platelet‐derived exosomes (P‐Exo). Sandwich assays using Tim4 with specificity for phosphatidylserine on EVs and antibodies against P‐Exo markers (CD61, CD41, CD63, and CD9) revealed that P‐Exo is significantly elevated in sera of APs (n = 16) relative to age‐ and sex‐matched HDs (n = 16). Tim4‐αCD63 showed the highest value for the area under the curve (0.957) for discriminating APs from HDs, which should lead to a better understanding of AD pathology and may facilitate the development of a novel diagnostic method for AD.

A gold nanocluster chemical tongue sensor array for Alzheimer's disease diagnosis.

Alzheimer's disease (AD) is a common neurodegenerative disorder in elderly people, and is associated with a heavy financial burden on our society. The use of serologic biomarkers is an attractive method to diagnose AD. Although the determination of blood-based biomarkers for AD has been explored in many studies, few practical diagnosis methods have been used in the clinic. In this work, we constructed a "chemical tongue" sensor array that is easy to use and based on four kinds of fluorescent gold nanoclusters (Au NCs) for discriminating between multiple proteins at nanomolar concentrations. The device utilizes a linear discrimination analysis based on fluorescence intensity response patterns. Using this chemical tongue sensor array, multiple proteins can be confidently identified even in complex biological systems, such as human urine. Most importantly, sera of AD patients could be effectively discriminated from those of osteoarthritis patients, or of healthy people. Also, the results obtained for the AD patients by the chemical tongue sensor array were validated by CSF determination. We conclude that the chemical tongue sensor array manufactured in this work paves the way for designing an auxiliary diagnosis method for AD that is less invasive and more convenient for the large-scale screening of patients.

Poster #S186 COGNITIVE PERFORMANCES OF JUVENILE OFFENDERS WITH SEVERE PSYCHIATRIC DISORDERS

Alzheimer's disease (AD) is a common neurodegenerative disorder in elderly people, and is associated with a heavy financial burden on our society. The use of serologic biomarkers is an attractive method to diagnose AD. Although the determination of blood-based biomarkers for AD has been explored in many studies, few practical diagnosis methods have been used in the clinic. In this work, we constructed a “chemical tongue” sensor array that is easy to use and based on four kinds of fluorescent gold nanoclusters (Au NCs) for discriminating between multiple proteins at nanomolar concentrations. The device utilizes a linear discrimination analysis based on fluorescence intensity response patterns. Using this chemical tongue sensor array, multiple proteins can be confidently identified even in complex biological systems, such as human urine. Most importantly, sera of AD patients could be effectively discriminated from those of osteoarthritis patients, or of healthy people. Also, the results obtained for the AD patients by the chemical tongue sensor array were validated by CSF determination. We conclude that the chemical tongue sensor array manufactured in this work paves the way for designing an auxiliary diagnosis method for AD that is less invasive and more convenient for the large-scale screening of patients.

Analysis of serum of patients with Alzheimer's disease for the level of advanced glycation end products.

Data on the serum level of advanced glycation end products (AGEs) in Alzheimer's disease (AD) patients are scarce, although a specific biochemical marker easy to detect in body fluids is desired for an early diagnosis of disease and to monitor the effects of therapeutic treatment. In the current study, the content of AGEs was examined with an immunochemical assay in the sera of AD patients, in the frame of a search for a biochemical marker of disease. Subjects with AD and vascular dementia (VaD) were included in the study (n = 30; age range, 68-70 years). The results were compared to the healthy control groups. The enzyme-linked immunosorbent assay (ELISA) inhibition test for the determination of AGEs is based on a rabbit anti-AGE, affinity-purified antibody and a model AGE-myoglobin antigen, in which a serum sample treated with proteinase K is used as an inhibitor. For the measurement of immune complexes and anti-AGE antibodies, the corresponding ELISA tests have been applied. The AGE level in the VaD group (49.5 U(AGE)) was higher than in AD patients (46.1 U(AGE)). The level of total AGEs in the sera of AD patients was significantly lower than in the control group (50/51.6 U(AGE)). These relations were not observed with regard to the immune complexes and anti-AGE antibody levels in AD (70.2 U(IC)/0.027 U(IgG)) and VaD (83 U(IC)/0.034 U(IgG)) patients because the levels of these parameters were similar to the controls (76.2 U(IC)/0.042 U(IgG)). The work revealed the lower level of circulating serum AGEs in patients with AD in relation to healthy controls.

Anti-NGF Autoantibodies and NGF in Sera of Alzheimer Patients and in Normal Subjects in Relation to Age

It has been suggested that inflammation may be a possible cause of Alzheimer's disease (AD). Increased anti-NGF autoantibody levels and increased NGF frequency in serum have previously been associated with inflammatory responses. In this study no changes in anti-NGF autoantibody titers or in NGF frequency were detected in sera of AD patients, suggesting that they are not involved in the neuroimmunological mechanisms underlying AD. There were neither age-associated changes in NGF frequency in sera of four groups of normal subjects between 18–91 years of age. In contrast, anti-NGF autoantibodies were significantly increased in sera of the 31–45 yr age group.

Immunoblot detection of antibodies to myelin basic protein in Alzheimer's disease patients

Based on a suspected pathological relationship of autoimmunity in Alzheimer's disease (AD), antibodies to myelin basic protein (MBP) were investigated in the sera of AD patients, healthy controls and disease controls. As detected by the protein-immunoblotting technique at a screening serum dilution of 1:400, sera from 16 of 18 (89%) AD patients were positive for antibodies to MBP. In contrast, sera from only 7 of 90 controls (healthy adults and elderlies, Parkinson's disease patients, mentally-retarded children and Down's syndrome patients) showed a positive reaction. This approximately 11-times higher incidence of antibodies to MBP in AD patients was statistically significant ( P≤0.0001) and may indicate an autoimmune process in the pathophysiology of the disease.

Antibodies from Down's syndrome patients bind to the same cholinergic neurofilament protein recognized by Alzheimer's disease antibodies

Down's syndrome (DS) patients who survive beyond the third decade develop brain lesions characteristic of Alzheimer's disease (AD). Sera of AD patients contain antibodies that bind specifically to the heavy neurofilament protein (NF-H) of Torpedo cholinergic neurons. In the present report, we examined whether the AD-like pathologic changes in DS are associated with the existence of such antibodies. Our findings show that IgG of older DS patients (greater than 30 years) binds to Torpedo cholinergic NF-H more readily than does that of young DS patients (less than 30 years) and age-matched normal controls. In contrast, the extent of binding of IgG from the young and older DS groups to Torpedo and bovine spinal cords NF-H is similar and equal to that of normal controls. These findings suggest that older DS patients, like AD patients, contain anti-NF-H IgG that binds specifically to epitopes highly enriched in Torpedo cholinergic NF-H.

Immunization with cholinergic cell bodies induces histopathological changes in rat brains

We have previously shown that sera from patients with Alzheimer's disease (AD) contain antibodies to the cell bodies (perikarya; PK) of purely cholinergic Torpedo neurons, and that repeated immunization of rats with this neuronal preparation for over a year induces learning and memory impairments. In the present study, we examined the brain morphology of cholinergic PK immunized rats relative to controls. Immunohistochemical studies of the brains of these rats revealed the accumulation of IgG in specific areas, such as, the hippocampus. Parallel histochemical studies demonstrated significant changes in the hippocampus, and in white matter areas. They included large vacuoles and necrotic nuclei in the granular layer of the dentate gyrus, tangle-like appearance in some pyramidal neurons of the hippocampus, and vacuolar degeneration accompanied by oligodendroglia hypertrophy in white matter tracts, such as, the corpus callosum and fimbria. In contrast, immunization with Torpedo cholinergic nerve terminals, that has no cognitive effects on the rat, also did not induce brain morphological changes. These findings suggest that the learning and memory deficits induced by immunizing rats with cholinergic PK are related to the observed brain morphological changes, and support the hypothesis that the antibodies to cholinergic neurons found in the sera of AD patients may play a role in neuronal degeneration in this disease.

Neuron-Binding Antibodies in Alzheimer's Disease and Down's Syndrome

We used an indirect immunoperoxidase technique (Avidin-Biotin system) to study the sera of patients with "clinically probable" Alzheimer's disease (AD) and with Down's Syndrome (DS), compared with age-matched controls. Diluted sera were incubated with paraffin sections of hippocampus, frontal, temporal, and parieto-occipital lobes from normal human brains. Biotinylated anti-human goat gamma-globulins were used as secondary antisera. A significantly greater percentage of neurons were immunostained in all the brain regions (frontal, temporal, and parieto-occipital lobes and hippocampus) incubated with sera of AD patients than with sera of DS patients or of controls. This indicates that AD patients have an excess of circulating neuron-binding antibodies (NBAs), mainly reacting with cytoplasmic structures. NBAs could be either the cause or the result of the cerebral lesion found in AD. This study is not able to answer this question, but some previous data from our own and other laboratories suggest that NBAs have a role in the pathogenesis of AD lesions. Since we found no increase of NBAs in DS patients, the brain lesions in DS appear to have a different pathogenesis.