Serum Of Alzheimer's Disease Patients Research Articles

Exploring neuron-specific steroid synthesis and DHEAS therapy in Alzheimer's disease

Alzheimer's Disease (AD) is a neurodegenerative disorder characterized by cognitive decline and memory loss. Recent studies have suggested a potential role for steroid synthesis in AD pathology. This study investigated the co-localization of steroidogenic enzymes in neuronal cells, changes in enzyme expression in an AD mouse model, and steroid expressions in human AD samples. Additionally, we conducted a steroidomic metabolomics analysis and evaluated the effects of dehydroepiandrosterone sulfate (DHEAS) treatment in an AD mouse model. Immunofluorescence analysis revealed significant co-localization of cytochrome P450 family 17 subfamily A member 1 (CYP17A1) and steroidogenic acute regulatory protein (StAR) proteins with α-synuclein in presynaptic neurons, suggesting active steroid synthesis in these cells. Conversely, such co-localization was absent in astrocytes. In the AD mouse model, a marked decrease in the expression of steroidogenic enzymes (Cyp11a1, Cyp17a1, Star) was observed, especially in areas with amyloid beta plaque accumulation. Human AD and MS brain tissues showed similar reductions in StAR and CYP17A1 expressions. Steroidomic analysis indicated a downregulation of key steroids in the serum of AD patients. DHEAS treatment in AD mice resulted in improved cognitive function and reduced Aβ accumulation. Our findings indicate a neuron-specific pathway for steroid synthesis, potentially playing a crucial role in AD pathology. The reduction in steroidogenic enzymes and key steroids in AD models and human samples suggests that impaired steroid synthesis is a feature of neurodegenerative diseases. The therapeutic potential of targeting steroid synthesis pathways, as indicated by the positive effects of DHEAS treatment, warrants further investigation.

Fibroblast growth factor 10 ameliorates neurodegeneration in mouse and cellular models of Alzheimer's disease via reducing tau hyperphosphorylation and neuronal apoptosis.

Alzheimer's disease (AD) is characterized with senile plaques formed by Aβ deposition, and neurofibrillary tangles composed of hyperphosphorylated tau protein, which ultimately lead to cognitive impairment. Despite the heavy economic and life burdens faced by the patients with AD, effective treatments are still lacking. Previous studies have reported the neuroprotective effects of FGF10 in CNS diseases, but its role in AD remains unclear. In this study, we demonstrated that FGF10 levels were reduced in the serum of AD patients, as well as in the brains of 3xTg-AD mice and APPswe-transfected HT22 cells, suggesting a close relationship between FGF10 and AD. Further investigations revealed that intranasal delivery of FGF10 improved cognitive functions in 3xTg-AD mice. Additionally, FGF10 treatment reduced tau hyperphosphorylation and neuronal apoptosis, thereby mitigating neuronal cell damage and synaptic deficits in the cortex and hippocampus of 3xTg-AD mice, as well as APPswe-transfected HT22 cells. Furthermore, we evaluated the therapeutic potential of FGF10 gene delivery for treating AD symptoms and pathologies. Tail vein delivery of the FGF10 gene using AAV9 improved cognitive and neuronal functions in 3xTg-AD mice. Similarly, endogenous FGF10 overexpression ameliorated tau hyperphosphorylation and neuronal apoptosis in the cortex and hippocampus of 3xTg-AD mice. Importantly, we confirmed that the FGFR2/PI3K/AKT signaling pathway was activated following intranasal FGF10 delivery and AAV9-mediated FGF10 gene delivery in 3xTg-AD mice and APPswe-transfected HT22 cells. Knockdown of FGFR2 attenuated the protective effect of FGF10. Collectively, these findings suggest that intranasal delivery of FGF10 and AAV9-mediated FGF10 gene delivery could be a promising disease-modifying therapy for AD.

MiR-483-3p improves learning and memory abilities via XPO1 in Alzheimer's disease.

IntroductionAlzheimer's disease (AD), a common form of dementia, has been reported to influence 27 million individuals globally. Several risk factors including oxidative stress, gut microbiota imbalance, and cognitive activity are reported to be closely associated with the initiation or progression of AD. Although miR‐483‐3p was identified to be downregulated in AD patient serum. However, the biological role and mechanism of miR‐483‐3p remained unknown in AD. Here, we explored the role of miR‐483‐3p in AD.MethodsSprague–Dawley rats were injected with homocysteine (Hcy) to establish an AD animal model. The Morris water maze tests and contextual fear tests were conducted to assess the cognitive and memory abilities of rats. TUNEL staining was utilized to determine cell apoptosis. Luciferase reporter assay was used to evaluate the binding relation between miR‐483‐3p and exportin 1 (XPO1).ResultsHomocysteine treatment (400 μg/kg) induced the learning, cognitive and memory defects of rats. miR‐483‐3p was downregulated in Hcy‐treated rat hippocampus. Functionally, miR‐483‐3p alleviated cell apoptosis and impairments of learning and memory abilities in Hcy‐treated rats. In addition, miR‐483‐3p inhibited cell apoptosis and protein level of AD‐associated factors (APP, BACE1, and Aβ1‐42) in PC12 cells. In mechanism, miR‐483‐3p was confirmed to target XPO1 in PC12 cells. XPO1 displayed high level in rat hippocampus and was negatively correlated with miR‐483‐3p levels. Finally, XPO1 overexpression rescued the suppressive effect of miR‐483‐3p on cell apoptosis and protein levels of AD‐associated factors.ConclusionsmiR‐483‐3p alleviates neural cell apoptosis and impairments of learning and memory abilities by targeting XPO1 in AD.

Reduced serum miR-202 may promote the progression of Alzheimer's disease patients via targeting amyloid precursor protein.

The current study investigated whether the expression of miR-202 was abnormal in the serum of patients with Alzheimer's disease (AD) and evaluated the potential clinical significance, thereby shedding light on the diagnosis of AD. Here, our data showed that the level of miR-202 decreased significantly in the serum of AD patients (n=121) compared with that of healthy controls (n=86). Further analysis showed that the level of serum miR-202 was gradually decreased in the mild AD group (n=31), moderate AD group (n=52) and severe AD group (n=38) compared with the healthy control group. Receiver operating characteristic (ROC) curve analysis demonstrated that serum miR-202 could differentiate AD patients from healthy controls, with an AUC of 0.892. Spearman correlation analysis showed that serum miR-202 was positively correlated with the Mini-Mental State Examination (MMSE). Based on TargetScan, a conserved binding site was identified in the 3'UTR of amyloid precursor protein (APP). The dual luciferase assay showed that miR-202 suppressed the relative luciferase activity of pmirGLO-APP-3'UTR. Western blot assays indicated that overexpression of miR-202 suppressed the expression of APP, while the expression of APP was enhanced after inhibition of miR-202 in PC12 cells, indicating that APP was a possible target gene of miR-202. Moreover, the cell apoptosis induced by transfection of miR-202 inhibitor was abolished by silencing APP. In summary, we showed novel data that downregulation of serum miR-202 may be used as a potential biomarker for AD and may promote the development of AD by targeting APP.

Changes in Biothiol Levels Are Closely Associated with Alzheimer's Disease.

Serum homocysteine (Hcy) level is considered to be an important biomarker for Alzheimer's disease (AD); however, the status of Hcy in brain tissue, and the association between brain and serum levels of Hcy in AD patients remain unclear. We aimed to examine whether the changes of three thiols are consistent in serum of AD patients and the brain of APP/PS1 mice, and to verify the effectiveness of Hcy as a biomarker for early AD detection. The levels of Hcy, cysteine (Cys), and glutathione (GSH) in Aβ1-42-treated PC12 cells, the brain and hippocampus of APP/PS1 mouse, and the serum of AD patients were evaluated using ethyl (E)-3-(9-chloro-11-oxo-2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f] pyrido [3,2,1 -ij] quinolin-10-yl)-2-cyanoacrylate (Probe 1) and ELISA assay or LC-MS. Measurement by Probe 1 revealed a significant increase in Hcy level, and a decrease in Cys and GSH levels in Aβ1-42-treated PC12 cells and the serum of AD patients. The hippocampus and whole brain of APP/PS1 mice also showed a significant increase in Hcy level alongside the accumulation of age-related AD symptoms. The upregulation of Hcy and the downregulation of Cys and GSH were reversed in the Aβ1-42-treated PC12 cells and the brain of APP/PS1 mice when supplemented with VB6. Changes in Hcy, Cys, and GSH levels in the brain of APP/PS1 mice and Aβ1-42-treated PC12 cells were observed in situ with a new fluorescent probe, which were consistent with the abnormal changes in Hcy, Cys, and GSH levels in the serum of AD patients. VB6 supplementation was successful in ameliorating abnormal increases in Hcy levels.

Deregulated lncRNA MAGI2-AS3 in Alzheimer's disease attenuates amyloid-β induced neurotoxicity and neuroinflammation by sponging miR-374b-5p.

Alzheimer's disease (AD) is a common neurodegenerative disease, which is characterized by aberrant accumulation of amyloid-β (Aβ) and neuroinflammation. The purpose of this study was to explore the regulatory effects of long non-coding RNA (lncRNA) MAGI2-AS3 and microRNA-374b-5p (miR-374b-5p) on Aβ-induced neurotoxicity and neuroinflammation, as well as the relationship between MAGI2-AS3 and miR-374b-5p in AD patients. A luciferase reporter assay was used to analyze the interaction between MAGI2-AS3 and miR-374b-5p and between miR-374b-5p and beta-site amyloid precursor protein cleaving enzyme 1 (BACE1). SH-SY5Y and BV2 cells treated with Aβ25-35 were used to mimic neuronal injury and neuroinflammation in AD pathogenesis. Cell viability was evaluated using a MTT assay, and pro-inflammatory cytokine levels were measured using ELISA kits. MAGI2-AS3 and miR-374b-5p expression was examined using quantitative real-time PCR. BACE1 served as a target gene of miR-374b-5p, and MAGI2-AS3 could sponge miR-374b-5p. The expression of MAGI2-AS3 was increased, and miR-374b-5p was decreased in both SH-SY5Y and BV2 cells exposed to Aβ25-35. MAGI2-AS3 reduction enhanced neuronal viability and attenuated neuroinflammation in AD cell models, and miR-374b-5p overexpression led to same effects, but miR-374b-5p inhibition reversed these effects. Serum MAGI2-AS3 and miR-374b-5p levels in AD patients were negatively correlated and correlated with disease severity. The findings indicated that the MAGI2-AS3/miR-374b-5p axis regulates Aβ-induced neurotoxicity in SH-SY5Y cells and neuroinflammation in BV2 cells. The MAGI2-AS3/miR-374b-5p axis may provide novel biomarkers and therapeutic targets for AD.

MiR-143-3p inhibition promotes neuronal survival in an Alzheimer's disease cell model by targeting neuregulin-1.

Alzheimer's disease (AD) is still the fifth leading cause of death and most common dementia worldwide. To date, there is no efficient strategy that can slow down the progression of AD owing to delayed diagnosis and limited therapies. MiR-143-3p is up-regulated in serum of AD patients, yet the exact role it plays in AD pathology is still poorly understood. The aim of this study was to investigate the effect of miR-143-3p on neuronal survival. We induced neuronal differentiation in SH-SY5Y cells using all-trans-retinoic acid (RA), and Aβ1-42 was used to establish the in vitro AD cell model. The expression of tubulin β III and neuregulin-1 (NRG1) was evaluated by immunofluorescence. TUNEL assay was performed to assess cell apoptosis. Cell viability was evaluated using the Cell Counting Kit-8 assay. The binding interaction between miR-143-3p and NRG1 was verified using the luciferase reporter assay. Typical neuronal-like axons were observed in RA-induced SH-SY5Y cells, followed by increased tubulin β III. A dramatically increased apoptotic rate and reduced cell viability were observed in the AD cell model. Then we silenced the miR-143-3p expression, and Aβ1-42 induced cell apoptosis was alleviated after miR-143-3p inhibition, accompanied by decreased cleaved caspase-3 and cleaved caspase-9 levels. Additionally, NRG1 was confirmed to be a downstream target of miR-143-3p, increased cell viability and suppressed cell apoptosis after miR-143-3p inhibition was abolished by NRG1 knockdown. Our findings reveal that miR-143-3p inhibition promotes neuronal survival in an in vitro cell model via targeting NRG1, and the miR-143-3p/NRG1 axis is a potential therapeutic target and promising biomarker for AD treatment.

Lower Serum Antibodies Against Tau Protein and Heavy Neurofilament in Alzheimer's Disease.

Unlike antibodies against amyloid-β, little is known about serum antibodies to neuron-specific cytoskeletal proteins in patients with Alzheimer's disease (AD). We aimed to study IgG autoantibodies against tau protein, light (NFL) and heavy subunits (NFH) of neurofilaments in serum of AD patients and elderly controls and to explore the evolution of antineurocytoskeletal antibody levels over time. Antibodies against three targets (tau, NFL, and NFH) were measured using ELISA in 100 serum samples from 51 cognitively normal elderly controls and 49 patients with AD. Our primary cross-sectional design was further extended to monitor fluctuations over 1-2 years in a subset of individuals. The AD patients had lower levels of anti-tau antibodies (p = 0.03) and even lower anti-NFH antibodies (p = 0.005) than those in the control group at baseline. On the contrary, anti-NFL antibodies or total IgG concentrations in serum did not differ. All three antibodies remained stable in both groups except for a selective and significant anti-tau decline in AD patients (p = 0.03). The different responses to these antigens suggest some antibody selectivity in AD. The significant decline was observed for only serum anti-tau antibodies in AD patients over time and it corresponds to lower anti-tau levels in these patients. Our findings indicate a special feature of disease-relevant antigens and humoral autoimmunity in AD.

5-LOX in Alzheimer's Disease: Potential Serum Marker and In Vitro Evidences for Rescue of Neurotoxicity by Its Inhibitor YWCS.

The inflammatory process plays a key role in neurodegenerative disorder. The inflammatory molecule, 5-lipooxygenase (5-LOX), protein is involved in the pathologic phenotype of Alzheimer's disease (AD) which includes Aβ amyloid deposition and tau hyperphosphorylation. This study determined the level of 5-LOX in serum of AD patients, mild cognitive impairment (MCI) patients, and the normal elderly, and the rescue effect by YWCS, a peptide inhibitor of 5-LOX on neurotoxicity by Aβ amyloid25-35 (Aβ25-35) in neuroblastoma cells. The concentration of serum 5-LOX was estimated by surface plasmon resonance and western blot. The neuroprotective effect of 5-LOX peptide inhibitor YWCS in Aβ25-35-induced neurotoxicity was analyzed by MTT assay and western blotting. We found significant upregulated serum 5-LOX in AD patients and also in MCI patients compared to the normal control group. The peptide inhibitor of 5-LOX, YWCS, prevented the neurotoxic effect of Aβ25-35 by reducing the expression of γ-secretase as well as p-Tau181 in SH-SY5Y cells. However, YWCS was nontoxic towards normal HEK cells. The differential expression of serum 5-LOX among the study groups suggests it can be one of potential serum protein marker and a therapeutic regimen for AD and MCI. The negative correlation with neuropsychological parameters, i.e., MoCA and HMSE, increases its importance and makes it useful during the clinical setup which is very needful in developing countries. Peptide YWCS can serve as a new platform as a 5-LOX inhibitor which can prevent neurotoxicity developed in AD.

Interrelationship between Mini-Mental State Examination scores and biochemical parameters in patients with mild cognitive impairment and Alzheimer's disease.

The aim of the present study was to provide first-hand information about the prevalence of mild cognitive impairment (MCI) and Alzheimer's disease (AD) in Tamil Nadu, a southern state in India, and examine if there exists a relationship between cognitive functions and biochemical parameters in these patients. Surveys were collected from adults, older men and women (n=3126) from different regions of Tamil Nadu, which were followed up after 12months for 1337 participants. Mini-Mental State Examination (MMSE) scores, lipid profile, and liver function tests were carried out in the elderly, MCI and AD patients. Based on the MMSE scores, the elderly population was classified into old control (28.97±1.49; n=1868), MCI (19.58±1.17; n=734) and AD (7.18±1.38; n=304) groups. Peripheral blood samples were collected after overnight fast from both male and female volunteers (n=40 per group) who were categorized as young adult control, old control, MCI and AD. AD patients showed lower MMSE scores compared with the young adults, old and MCI groups, and MMSE further decreased at follow-up examination a year later. In the serum of AD patients, high-density lipoprotein, alkaline phosphatase activity and bilirubin levels were lower, whereas low-density lipoprotein, total cholesterol and triglycerides levels were higher. MMSE was positively correlated with high-density lipoprotein, and negatively correlated with other lipid parameters in AD. Hypercholesterolemia is a risk factor for AD that might result in neurotoxicity and cognitive impairment. Dysfunction of lipoprotein and heme metabolism might also provide additional targets for AD diagnosis. Geriatr Gerontol Int 2017; 17: 1737-1745.

Design, synthesis of allosteric peptide activator for human SIRT1 and its biological evaluation in cellular model of Alzheimer's disease

Sirtuin 1 (SIRT1) is one of the member of the mammalian proteins of the Sirtuin family of NAD+ dependent deacetylases, has recently been shown to attenuate amyloidogenic processing of amyloid protein precursor (APP) in in-vitro cell culture studies and transgenic mouse models of Alzheimer's disease (AD). SIRT1 has been shown to have a protective role against (AD). It has been reported earlier that increasing SIRT1 activity can prevent AD in mice model. Tripeptide as an activator of SIRT1 were screened on the basis of structural information by molecular docking and synthesized by solid phase method. The enhancement of biochemical activity of pure recombinant SIRT1 as well as SIRT1 in serum of AD patients in presence of tripeptide was done by Fluorescent Activity Assay. The activity of SIRT1 by peptide was assessed in IMR-32 cell line by measuring acetylated p53 level. Further the protective effect of SIRT1 activator in cellular model of AD was analyzed by MTT assay. We find CWR tripeptide as a SIRT1 activator by molecular docking, enhanced the activity of SIRT1 protein by lowering the Michaelis constant, Km by allosteric mechanism. The activity of serum SIRT1 of AD was also increases by CWR. It also decreased the acetylation of p53 in IMR32 neuroblastoma cells and protected the cell death caused by Aβ amyloid fragments in cell line model of AD. Thus, it can be concluded that CWR may serve as platform to elucidate further small molecule activator as a therapeutic agent for AD targeting SIRT1.

Estimation of Tau and Phosphorylated Tau181 in Serum of Alzheimer's Disease and Mild Cognitive Impairment Patients.

The elevated level of cerebrospinal fluid (CSF) Tau and phosphorylated Tau181 (p-Tau181) proteins are well established hallmarks of Alzheimer’s disease (AD). Elevated level of p-Tau181 can differentiate AD from other neurodegenerative disease. However, the expression level of these proteins in serum of AD patient is not well set up. This study sought to evaluate the level of Tau and p-Tau181 in serum of AD, and mild cognitive impairment (MCI) patients for an alternative approach to establish protein-based markers by convenient way. Blood samples were collected from 39 AD patients, 37 MCI patients and 37 elderly individuals as controls. The levels of Tau and p-Tau181 in the serum of the different groups were measured by label free real time Surface Plasmon Resonance technology by using specific antibodies, and were further confirmed by the conventional western blot method. An appropriate statistical analysis, including Receiver Operating Characteristic (ROC), was performed. The concentrations of serum Tau and p-Tau181 were significantly higher (p<0.00001) in AD (Tau; 47.49±9.00ng/μL, p-Tau181; 0.161±0.04 ng/μL) compared to MCI (Tau; 39.26±7.78 ng/μL, p-Tau181; 0.135±0.02 ng/μL) and were further higher compared to elderly controls (Tau; 34.92±6.58 ng/μL, p-Tau181; 0.122±0.01 ng/ μL). A significant (p<0.0001) downhill correlation was found between Tau as well as p-Tau181 levels with HMSE and MoCA score. This study for the first time reports the concentration of Tau and p-Tau181 in serum of AD and MCI patients. The cutoff values of Tau and p-Tau181 of AD and MCI patients with sensitivity and specificity reveal that serum level of these proteins can be used as a predictive marker for AD and MCI.

The levels of 7,8-dihydrodeoxyguanosine (8-oxoG) and 8-oxoguanine DNA glycosylase 1 (OGG1) – A potential diagnostic biomarkers of Alzheimer's disease

Evidence indicates that oxidative stress contributes to neuronal cell death in Alzheimer's disease (AD). Increased oxidative DNA damage l, as measured with 8-oxoguanine (8-oxoG), and reduced capacity of proteins responsible for removing of DNA damage, including 8-oxoguanine DNA glycosylase 1 (OGG1), were detected in brains of AD patients. In the present study we assessed peripheral blood biomarkers of oxidative DNA damage, i.e. 8- oxoG and OGG1, in AD diagnosis, by comparing their levels between the patients and the controls. Our study was performed on DNA and serum isolated from peripheral blood taken from 100 AD patients and 110 controls. For 8-oxoG ELISA was employed. The OGG1 level was determined using ELISA and Western blot technique. Levels of 8-oxoG were significantly higher in DNA of AD patients. Both ELISA and Western blot showed decreased levels of OGG1 in serum of AD patients. Our results show that oxidative DNA damage biomarkers detected in peripheral tissue could reflect the changes occurring in the brain of patients with AD. These results also suggest that peripheral blood samples may be useful to measure oxidative stress biomarkers in AD.

Gas chromatography-mass spectrometry analysis of the free fatty acids in serum obtained from patients with Alzheimer's disease.

As the worldwide elderly population has grown, the incidence and prevalence of Alzheimer's disease (AD) has steadily increased. The differential lifelong exposure of populations to dietary fatty acids has raised concerns about the potential links between cognitive impairments and nutrition. However, few studies have addressed the levels of free fatty acids (FFAs) in AD patient serum. In this study, gas chromatography-mass spectrometry (GC-MS) was used to determine the levels of 15 serum FFAs in 31 AD patients and 33 healthy controls. The optimized methodology entailed the formation of methyl esters using 10% v/v H2SO4/CH3OH at 62°C for 2 hours. The linear range was 0.55-300 μg/mL, the range of recovery was 85.1-104.3%, and the detection limit was 0.03-0.08 μg/mL. Several FFAs in the AD patient significantly decreased when compared to the control, including three saturated fatty acids (C14:0, C16:0, and C18:0) and six unsaturated fatty acids (C16:1, C18:1, C18:2, γ-C18:3, C20:2, and C22:6). The serum level of C18:3 was significantly higher in the AD patients. The FFA profiles of the AD patients differed significantly from those of controls. The method effectively determined the FFA levels and could facilitate future studies regarding the relationship between AD and the metabolism of FFAs.

Translational study of Alzheimer's disease (AD) biomarkers from brain tissues in AβPP/PS1 mice and serum of AD patients.

The aim of this study was to investigate potential biomarkers of Alzheimer's disease (AD). Changes in protein expression in brain tissues from AβPP/PS1 transgenic mice were evaluated using two-dimensional gel electrophoresis combined with LC-MS/MS. A total of 23 differentially expressed proteins were successfully identified in brain tissues of which 11 were validated by western blot. Then, the levels of these differentially expressed proteins in serum from AD patients and healthy controls were examined. Of these 11 proteins, levels of 5 changed in the same direction in the serum of AD patients as they did in mouse brain: cathepsin B, VDAC1, and cofilin-2 increased, and Alix and ACAP1 decreased. Alix, cofilin-2, and ACAP1 have not been previously associated with AD. More importantly, the serum levels of Alix, cofilin-2, and ACAP1 were significantly different between AD patients and healthy controls. Furthermore, the expressions of cathepsin B, cofilin-2, VDAC1, and ACAP1 strongly correlated with the Mini-Mental State Examination scores of the AD patients. The results indicate that these proteins are putative biomarkers of AD which may be useful in its diagnosis and in the evaluation of new anti-AD drugs both in pre-clinical and clinical studies.

Decreased serum levels of the angiogenic factors VEGF and TGF-β1 in Alzheimer's disease and amnestic mild cognitive impairment

Growing evidence suggests that angiogenesis might represent a new pathogenic mechanism involved in the progression of Alzheimer's disease (AD). Vascular endothelial growth factor (VEGF) and transforming growth factor-β1 (TGF-β1) are two cytokines having a pivotal role in angiogenesis. In the present study, serum VEGF and TGF-β1 levels were measured with ELISA in 31 AD patients, 28 amnestic mild cognitive impairment (aMCI) patients and 29 controls. VEGF concentration in serum of AD patients was significantly lower than that in aMCI patients and controls (p<0.05). Serum VEGF levels in aMCI patients were also significantly decreased compared to controls (p<0.05). Serum TGF-β1 levels in AD patients were significantly lower than those in controls (p<0.05). There was a negative correlation between serum VEGF/TGF-β1 levels and the Clinical Dementia Rating (CDR) scores (p<0.05) and a positive correlation between serum VEGF levels and TGF-β1 levels (p<0.05). These observations suggest that angiogenesis might be involved in the onset process of AD and the decrease of angiogenic factors might be related to the severity of cognitive impairment.

Aβ43 Is the Earliest-Depositing Aβ Species in APP Transgenic Mouse Brain and Is Converted to Aβ41 by Two Active Domains of ACE

Amyloid-β protein (Aβ) varies in length at its carboxyl terminus. The longer Aβ species, Aβ43 and Aβ42, are highly amyloidogenic and deposit more frequently than Aβ40 in the brain of Alzheimer disease (AD) patients. However, the characterization of Aβ43 deposition in the brain and the relationship between Aβ43 and Aβ42 or Aβ40 remain unclear. We provide evidence that Aβ43 deposition appears earlier than Aβ42 and Aβ40 deposition in the brain of mutant amyloid precursor protein transgenic (APPtg) mice, suggesting that Aβ43 is the earliest-depositing species. In addition, we found increased Aβ43 levels and Aβ43/Aβ42 ratios in the serum of AD patients, suggesting their use as diagnostic blood biomarkers for AD. We further show that angiotensin-converting enzyme (ACE) converts Aβ43 to Aβ41. Notably, this Aβ43-to-Aβ41 converting activity requires two active domains of ACE. Inhibition of ACE activity significantly enhanced Aβ43 deposition in APPtg mouse brain. Our results suggest that Aβ43 is the earliest-depositing species in brain parenchyma and that Aβ43 may trigger later Aβ42 and Aβ40 deposition or may be converted to Aβ42 and Aβ40 plaques. Activities of both ACE domains may be important for reducing Aβ43 levels in serum and reducing brain Aβ43 deposition.

Melatonin Attenuates Scopolamine-Induced Memory/Synaptic Disorder by Rescuing EPACs/miR-124/Egr1 Pathway

Alzheimer's disease (AD) is the most prevalent type of dementia in elderly people. There are decreased melatonin levels in the serum of AD patients, and melatonin supplements are able to reverse AD pathology and memory deficits in many animal experiments and clinical trials. However, the underlying mechanism regarding how melatonin rescues the AD-like memory/synaptic disorder remains unknown. Here, we use the Morris water maze, step-down inhibitory avoidance task, in vivo long-term potentiation recording, and Golgi staining and report that intraperitoneal injection of melatonin (1 mg/kg/day) for 14 days in rats effectively reverses the memory and synaptic impairment in scopolamine-induced amnesia, a well-recognized dementia animal model. Using real-time polymerase chain reaction and western blotting experiments, we further determined that melatonin rescues the EPACs/miR-124/Egr1 signal pathway, which is important in learning and memory, as reported recently. Our studies provide a novel underlying epigenetic mechanism for melatonin to attenuate the synaptic disorder and could benefit drug discovery in neurodegenerative diseases.

Levels of Amyloid Beta-42, Interleukin-6 and Tumor Necrosis Factor-Alpha in Alzheimer’s Disease and Vascular Dementia

Amyloid β42 (Aβ42) and proinflammatory cytokines such as interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) have been suggested to contribute to the pathogenesis of Alzheimer's disease (AD) and vascular dementia (VaD). Our aim was to examine whether the changes in these parameters would be able to discriminate the patients with AD from those with VaD and from healthy individuals. We have analyzed the levels of Aβ42, IL-6 and TNF-α in the serum of newly diagnosed 28 AD patients, 16 VaD patients and 26 healthy non-demented controls. We also investigated whether there is an association between Aβ42, IL-6 and TNF-α levels and mini-mental state examination (MMSE) scores and body mass indexes (BMI) of patients. Our data showed a significant decrease in serum Aβ-42 levels in AD patients compared to VaD patients and controls. Levels of IL-6 and TNF-α were not different between AD patients, VaD patients and controls. We observed a correlation between Aβ-42 levels and MMSE scores and BMI levels in both AD and VaD patients. However, Aβ-42 levels were not correlated with IL-6 and TNF-α levels. Significantly lower levels of Aβ42 found in the serum of AD patients than that of VaD patients and controls suggests that it can be a specific biochemical marker for AD.

Environmental Factors Preceding A40 Monomer to Oligomers and the Detection of Oligomers in Alzheimer's Disease Patient Serum

We present here environmental factors including pH shifts, temperature, and metal ions surrounding Aβ40 monomer to precede the oligomers. We also suggest a new idea to detect Aβ40 oligomers with anti-Aβ40 monoclonal antibody using enzyme-linked immunosorbent assay. This method involves the different sensitivity of the thermal shifts between Aβ40 monomer and the oligomers. The idea is useful for the diagnostics of Alzheimer's disease to detect Aβ40 oligomers in the serum from the patients.