Roles of astrocytes and prions in Alzheimer's disease: insights from mathematical modeling.

We present a mathematical model that explores the progression of Alzheimer's disease, with a particular focus on the involvement of disease-related proteins and astrocytes. Our model consists of a coupled system of differential equations that delineates the dynamics of amyloid beta plaques, amyloid beta protein, tau protein, and astrocytes. Amyloid beta plaques can be considered fibrils that depend on both the plaque size and time. We change our mathematical model to a temporal system by applying an integration operation with respect to the plaque size. Theoretical analysis including existence, uniqueness, positivity, and boundedness is performed in our model. We extend our mathematical model by adding two populations, namely prion protein and amyloid beta-prion complex. We characterize the system dynamics by locating biologically feasible steady states and their local stability analysis for both models. The characterization of the proposed model can help inform in advancing our understanding of the development of Alzheimer's disease as well as its complicated dynamics. We investigate the global stability analysis around the interior equilibrium point by constructing a suitable Lyapunov function. We validate our theoretical analysis with the aid of extensive numerical illustrations.

Fibrillization Process of Human Amyloid-Beta Protein (1-40) under a Molecular Crowding Environment Mimicking the Interior of Living Cells Using Cell Debris.

Molecular crowding environments play a crucial role in understanding the mechanisms of biological reactions. Inside living cells, a diverse array of molecules coexists within a volume fraction ranging from 10% to 30% v/v. However, conventional spectroscopic methods often face difficulties in selectively observing the structures of particular proteins or membranes within such molecularly crowded environments due to the presence of high background signals. Therefore, it is crucial to establish in vitro measurement conditions that closely resemble the intracellular environment. Meanwhile, the neutron scattering method offers a significant advantage in selectively observing target biological components, even within crowded environments. Recently, we have demonstrated a novel scattering method capable of selectively detecting the structures of targeted proteins or membranes in a closely mimicking intracellular milieu achieved utilizing whole-cell contents (deuterated-cell debris). This method relies on the inverse contrast matching technique in neutron scattering. By employing this method, we successfully observed the fibrillization process of human amyloid beta-protein (Aß 1-40) under a molecular crowding environment (13.1% w/v cell debris, Aß/cell debris = ~1/25 w/w) that closely mimics the interior of living cells. Aß protein is well known as a major pathogenic component of Alzheimer's disease. The present results combining model simulation analyses clearly show that the intracellular environment facilitates the potential formation of even more intricate higher-order aggregates of Aß proteins than those previously reported.

LOTUS suppresses amyloid ß-induced dendritic spine elimination through the blockade of amyloid ß binding to PirB.

BACKGROUND: Alzheimer's disease (AD) is the most common neurodegenerative disease worldwide but has no effective treatment. Amyloid beta (Aß) protein, a primary risk factor for AD, accumulates and aggregates in the brain of patients with AD. Paired immunoglobulin-like receptor B (PirB) has been identified as a receptor of Aß and Aß-PirB molecular interactions that cause synapse elimination and synaptic dysfunction. PirB deletion has been shown to suppress Aß-induced synaptic dysfunction and behavioral deficits in AD model mice, implying that PirB mediates Aß-induced AD pathology. Therefore, inhibiting the Aß-PirB molecular interaction could be a successful approach for combating AD pathology. We previously showed that lateral olfactory tract usher substance (LOTUS) is an endogenous antagonist of type1 Nogo receptor and PirB and that LOTUS overexpression promotes neuronal regeneration following damage to the central nervous system, including spinal cord injury and ischemic stroke. Therefore, in this study, we investigated whether LOTUS inhibits Aß-PirB interaction and Aß-induced dendritic spine elimination. METHODS: The inhibitory role of LOTUS against Aß-PirB (or leukocyte immunoglobulin-like receptor subfamily B member 2: LilrB2) binding was assessed using a ligand-receptor binding assay in Cos7 cells overexpressing PirB and/or LOTUS. We assessed whether LOTUS inhibits Aß-induced intracellular alterations and synaptotoxicity using immunoblots and spine imaging in a primary cultured hippocampal neuron. RESULTS: We found that LOTUS inhibits the binding of Aß to PirB overexpressed in Cos7 cells. In addition, we found that Aß-induced dephosphorylation of cofilin and Aß-induced decrease in post-synaptic density-95 expression were suppressed in cultured hippocampal neurons from LOTUS-overexpressing transgenic (LOTUS-tg) mice compared with that in wild-type mice. Moreover, primary cultured hippocampal neurons from LOTUS-tg mice improved the Aß-induced decrease in dendritic spine density. Finally, we studied whether human LOTUS protein inhibits Aß binding to LilrB2, a human homolog of PirB, and found that human LOTUS inhibited the binding of Aß to LilrB2 in a similar manner. CONCLUSIONS: This study implied that LOTUS improved Aß-induced synapse elimination by suppressing Aß-PirB interaction in rodents and inhibited Aß-LilrB2 interaction in humans. Our findings revealed that LOTUS may be a promising therapeutic agent in counteracting Aß-induced AD pathologies.

An ultra-sensitive immunoassay detects and quantifies soluble Aß oligomers in human plasma.

INTRODUCTION: Evidence strongly suggests that soluble oligomers of amyloid beta protein (oAß) help initiate the pathogenic cascade of Alzheimer's disease (AD). To date, there have been no validated assays specific for detecting and quantifying oAß in human blood. METHODS: We developed an ultrasensitive oAß immunoassay using a novel capture antibody (71A1) with N-terminal antibody 3D6 for detection that specifically quantifies soluble oAß in the human brain, cerebrospinal fluid (CSF), and plasma. RESULTS: Two new antibodies (71A1; 1G5) are oAß-selective, label Aß plaques in non-fixed AD brain sections, and potently neutralize the synaptotoxicity of AD brain-derived oAß. The 71A1/3D6 assay showed excellent dilution linearity in CSF and plasma without matrix effects, good spike recovery, and specific immunodepletion. DISCUSSION: We have created a sensitive, high throughput, and inexpensive method to quantify synaptotoxic oAß in human plasma for analyzing large cohorts of aged and AD subjects to assess the dynamics of this key pathogenic species and response to therapy.

Plasma amyloid beta predicts conversion to dementia in subjects with mild cognitive impairment: The BALTAZAR study.

INTRODUCTION: Blood-based biomarkers are the next challenge for Alzheimer's disease (AD) diagnosis and prognosis. METHODS: Mild cognitive impairment (MCI) participants (N = 485) of the BALTAZAR study, a large-scale longitudinal multicenter cohort, were followed-up for 3 years. A total of 165 of them converted to dementia (95% AD). Associations of conversion and plasma amyloid beta (Aß)1-42 , Aß1-40 , Aß1-42 /Aß1-40 ratio were analyzed with logistic and Cox models. RESULTS: Converters to dementia had lower level of plasma Aß1-42 (37.1 pg/mL [12.5] vs. 39.2 [11.1] , P value = .03) and lower Aß1-42 /Aß1-40 ratio than non-converters (0.148 [0.125] vs. 0.154 [0.076], P value = .02). MCI participants in the highest quartile of Aß1-42 /Aß1-40 ratio (>0.169) had a significant lower risk of conversion (hazard ratio adjusted for age, sex, education, apolipoprotein E ε4, hippocampus atrophy = 0.52 (95% confidence interval [0.31-0.86], P value = .01). DISCUSSION: In this large cohort of MCI subjects we identified a threshold for plasma Aß1-42 /Aß1-40 ratio that may detect patients with a low risk of conversion to dementia within 3 years.

Amyloidosis in Alzheimer's Disease: Pathogeny, Etiology, and Related Therapeutic Directions.

The amyloid hypothesis of Alzheimer's disease has long been the predominant theory, suggesting that Alzheimer's disease is caused by the accumulation of amyloid beta protein (Aß) in the brain, leading to neuronal toxicity in the central nervous system (CNS). Because of breakthroughs in molecular medicine, the amyloid pathway is thought to be central to the pathophysiology of Alzheimer's disease (AD). Currently, it is believed that altered biochemistry of the Aß cycle remains a central biological feature of AD and is a promising target for treatment. This review provides an overview of the process of amyloid formation, explaining the transition from amyloid precursor protein to amyloid beta protein. Moreover, we also reveal the relationship between autophagy, cerebral blood flow, ACHE, expression of LRP1, and amyloidosis. In addition, we discuss the detailed pathogenesis of amyloidosis, including oxidative damage, tau protein, NFTs, and neuronal damage. Finally, we list some ways to treat AD in terms of decreasing the accumulation of Aß in the brain.

Liraglutide Has Anti-Inflammatory and Anti-Amyloid Properties in Streptozotocin-Induced and 5xFAD Mouse Models of Alzheimer's Disease.

Recent clinical and epidemiological studies support the contention that diabetes mellitus (DM) is a strong risk factor for the development of Alzheimer's disease (AD). The use of insulin cell toxin, streptozotocin (STZ), when injected into the lateral ventricles, develops an insulin resistant brain state (IRBS) and represents a non-transgenic, or sporadic AD model (SAD), with several AD-like neuropathological features. The present study explored the effects of an anti-diabetic drug, liraglutide (LIR), in reversing major pathological hallmarks in the prodromal disease stage of both the 5xFAD transgenic and SAD mouse models of AD. Three-month-old 5xFAD and age-matched wild type mice were given a single intracerebroventricular (i.c.v) injection of STZ or vehicle (saline) and were subsequently treated with LIR, intraperitoneally (IP), once a day for 30 days. The extent of neurodegeneration, Aß plaque load, and key proteins associated with the insulin signaling pathways were measured using Western blot and neuroinflammation (via immunohistological assays) in the cortical and hippocampal regions of the brain were assessed following a series of behavioral tests used to measure cognitive function after LIR or vehicle treatments. Our results indicated that STZ significantly increased neuroinflammation, Aß plaque deposition and disrupted insulin signaling pathway, while 25 nmol/kg LIR, when injected IP, significantly decreased neuroinflammatory responses in both SAD and 5xFAD mice before significant cognitive changes were observed, suggesting LIR can reduce early neuropathology markers prior to the emergence of overt memory deficits. Our results indicate that LIR has neuroprotective effects and has the potential to serve as an anti-inflammatory and anti-amyloid prophylactic therapy in the prodromal stages of AD.

The effect of sevoflurane on the spatial recall ability and expression of apolipoprotein E and ß amyloid in the hippocampus in rats.

This study aimed to observe the recent spatial recall ability and the changes of expression of hippocampal apolipoprotein E (ApoE) and amyloid ß protein (Aß) in adult rats after inhaling sevoflurane anesthetic drugs, and to analyze the mechanism of action. For this purpose, a total of 54 adult SD clean-grade rats were selected in this study and were randomly divided into the sevoflurane anesthesia group, carrier gas group and control group, 18 rats in each group. The rats in the carrier gas group were inhaled with 1 L/min of oxygen O2+1 L/min air mixed carrier gas for 2 h, and the rats in the sevoflurane anesthesia group were given 3.2%sevoflurane for 2 hours based on the carrier gas group, the control rats were naturally reared. Before the model was copied, the Morris water maze experiment was performed before the material was taken. Some rat brain tissues were extracted on the first day (T1), the third day (T3), and the seventh day (T7) after model replication. The immunohistochemistry was used to measure the mean optical density (MOD) value of APOE and Aß in hippocampal CA1, CA3 and DG regions. The indicators above at different time points of each group were compared and analyzed. Results showed that the number of crossing the original platform at each time point, the residence time of the original platform quadrant, the number of entering the original platform quadrant, and the percentage of the original platform quadrant residence time in the sevoflurane anesthesia group and the carrier gas group were compared, and there were no significant differences between two groups (P>0.05). Compared with the carrier gas group, the MOD values of APOE in the hippocampus at T1 and T3 time points in the sevoflurane anesthesia group were decreased (P<0.05), the MOD values of Aß in the hippocampus at the T7 time point were increased (P<0.05). It concluded that Inhalation of 3.2%sevoflurane has no obvious damage to the recent spatial recall ability of adult rats. Within 7 days after inhalation of 3.2% sevoflurane, it can inhibit hippocampus Aß deposition through down-regulating APOE expression level. The critical time point for hippocampal Aß increasing was 7 days after anesthesia.

Ameliorative Properties of Boronic Compounds in In Vitro and In Vivo Models of Alzheimer's Disease.

Alzheimer's disease (AD) is characterized by amyloid (Aß) aggregation, hyperphosphorylated tau, neuroinflammation, and severe memory deficits. Reports that certain boronic compounds can reduce amyloid accumulation and neuroinflammation prompted us to compare trans-2-phenyl-vinyl-boronic-acid-MIDA-ester (TPVA) and trans-beta-styryl-boronic-acid (TBSA) as treatments of deficits in in vitro and in vivo models of AD. We hypothesized that these compounds would reduce neuropathological deficits in cell-culture and animal models of AD. Using a dot-blot assay and cultured N2a cells, we observed that TBSA inhibited Aß42 aggregation and increased cell survival more effectively than did TPVA. These TBSA-induced benefits were extended to C. elegans expressing Aß42 and to the 5xFAD mouse model of AD. Oral administration of 0.5 mg/kg dose of TBSA or an equivalent amount of methylcellulose vehicle to groups of six- and 12-month-old 5xFAD or wild-type mice over a two-month period prevented recognition- and spatial-memory deficits in the novel-object recognition and Morris-water-maze memory tasks, respectively, and reduced the number of pyknotic and degenerated cells, Aß plaques, and GFAP and Iba-1 immunoreactivity in the hippocampus and cortex of these mice. These findings indicate that TBSA exerts neuroprotective properties by decreasing amyloid plaque burden and neuroinflammation, thereby preventing neuronal death and preserving memory function in the 5xFAD mice.

Understanding the Pathophysiology of Cerebral Amyloid Angiopathy.

Cerebral amyloid angiopathy (CAA), one of the main types of cerebral small vessel disease, is a major cause of spontaneous intracerebral haemorrhage and an important contributor to cognitive decline in elderly patients. Despite the number of experimental in vitro studies and animal models, the pathophysiology of CAA is still largely unknown. Although several pathogenic mechanisms including an unbalance between production and clearance of amyloid beta (Aß) protein as well as 'the prion hypothesis' have been invoked as possible disease triggers, they do not explain completely the disease pathogenesis. This incomplete disease knowledge limits the implementation of treatments able to prevent or halt the clinical progression. The continuous increase of CAA patients makes imperative the development of suitable experimental in vitro or animal models to identify disease biomarkers and new pharmacological treatments that could be administered in the early disease stages to prevent irreversible changes and disease progression.

Characterizing the structural and thermodynamic properties of Aß42 and Aß40.

The self-assembly of amyloid-beta (Aß) proteins in aqueous extracellular environments is implicated in Alzheimer's disease. Among several alloforms of Aß proteins differing in sequence length, the 42- and 40-residue forms (Aß42 and Aß40) are the most abundant ones in the human body. Although the only difference is the additional I41A42 residues in the C-terminus, Aß42 exhibits more aggregation tendency and stronger neurotoxicity than Aß40. Here, we investigate the molecular factors that confer more aggregation potential to Aß42 than to Aß40 based on molecular dynamics simulations combined with solvation thermodynamic analyses. It is observed that the most salient structural feature of Aß42 relative to Aß40 is the more enhanced ß-sheet forming tendency, in particular in the C-terminal region. While such a structural characteristic of Aß42 will certainly serve to facilitate the formation of aggregate species rich in ß-sheet structure, we also detect its interesting thermodynamic consequence. Indeed, we find from the decomposition analysis that the C-terminal region substantially increases the solvation free energy (i.e., overall "hydrophobicity") of Aß42, which is caused by the dehydration of the backbone moieties showing the enhanced tendency of forming the ß-structure. Together with the two additional hydrophobic residues (I41A42), this leads to the higher solvation free energy of Aß42, implying the larger water-mediated attraction toward the self-assembly. Thus, our computational results provide structural and thermodynamic grounds on why Aß42 has more aggregation propensity than Aß40 in aqueous environments.

Effects of silica nanoparticles on endolysosome function in primary cultured neurons 1.

Silica nanoparticles (SiNPs) have been used as vehicles for drug delivery, molecular detection, and cellular manipulations in nanoneuromedicine. SiNPs may cause adverse effects in the brain including neurotoxicity, neuroinflammation, neurodegeneration, and enhancing levels of amyloid beta (Aß) protein-all pathological hallmarks of Alzheimer's disease. Therefore, the extent to which SiNPs influence Aß generation and the underlying mechanisms by which this occurs deserve investigation. Our studies were focused on the effects of SiNPs on endolysosomes which uptake, traffic, and mediate the actions of SiNPs. These organelles are also where amyloidogenesis largely originates. We found that SiNPs, in primary cultured hippocampal neurons, accumulated in endolysosomes and caused a rapid and persistent deacidification of endolysosomes. SiNPs significantly reduced endolysosome calcium stores as indicated by a significant reduction in the ability of the lysosomotropic agent glycyl-l-phenylalanine 2-naphthylamide (GPN) to release calcium from endolysosomes. SiNPs increased Aß1-40 secretion, whereas 2 agents that acidified endolysosomes, ML-SA1 and CGS21680, blocked SiNP-induced deacidification and increased generation of Aß1-40. Our findings suggest that SiNP-induced deacidification of and calcium release from endolysosomes might be mechanistically linked to increased amyloidogenesis. The use of SiNPs might not be the best nanomaterial for therapeutic strategies against Alzheimer's disease and other neurological disorders linked to endolysosome dysfunction.

The Anti-Amyloidogenic Action of Doxycycline: A Molecular Dynamics Study on the Interaction with Aß42.

The pathological aggregation of amyloidogenic proteins is a hallmark of many neurological diseases, including Alzheimer's disease and prion diseases. We have shown both in vitro and in vivo that doxycycline can inhibit the aggregation of Aß42 amyloid fibrils and disassemble mature amyloid fibrils. However, the molecular mechanisms of the drug's anti-amyloidogenic property are not understood. In this study, a series of molecular dynamics simulations were performed to explain the molecular mechanism of the destabilization of Aß42 fibrils by doxycycline and to compare the action of doxycycline with those of iododoxorubicin (a toxic structural homolog of tetracyclines), curcumin (known to have anti-amyloidogenic activity) and gentamicin (an antibiotic with no experimental evidence of anti-amyloidogenic properties). We found that doxycycline tightly binds the exposed hydrophobic amino acids of the Aß42 amyloid fibrils, partly leading to destabilization of the fibrillar structure. Clarifying the molecular determinants of doxycycline binding to Aß42 may help devise further strategies for structure-based drug design for Alzheimer's disease.

Solid lipid curcumin particles provide greater anti-amyloid, anti-inflammatory and neuroprotective effects than curcumin in the 5xFAD mouse model of Alzheimer's disease.

BACKGROUND: Neuroinflammation and the presence of amyloid beta protein (Aß) and neurofibrillary tangles are key pathologies in Alzheimer's disease (AD). As a potent anti-amyloid and anti-inflammatory natural polyphenol, curcumin (Cur) could be potential therapies for AD. Unfortunately, poor solubility, instability in physiological fluids, and low bioavailability limit its clinical utility. Recently, different lipid modifications in the formulae of Cur have been developed that would enhance its therapeutic potential. For example, we have reported greater permeability and neuroprotection with solid lipid curcumin particles (SLCP) than with natural Cur in an in vitro model of AD. In the present study, we compared the Aß aggregation inhibition, anti-amyloid, anti-inflammatory responses of Cur and or SLCP in both in vitro and in vivo models of AD. One-year-old 5xFAD-and age-matched wild-type mice were given intraperitoneal injections of Cur or SLCP (50 mg/kg body weight) for 2- or 5-days. Levels of Aß aggregation, including oligomers and fibril formation, were assessed by dot blot assay, while Aß plaque load and neuronal morphology in the pre-frontal cortex (PFC) and hippocampus were assayed by immunolabeling with Aß-specific antibody and cresyl violet staining, respectively. In addition, neuroinflammation was assessed the immunoreactivity (IR) of activated astrocytes (GFAP) and microglia (Iba-1) in different brain areas. Finally, comparisons of solubility and permeability of Cur and SLCP were made in cultured N2a cells and in primary hippocampal neurons derived from E16 pups of 5xFAD mice. RESULTS: We observed that relative to Cur, SLCP was more permeable, labeled Aß plaques more effectively, and produced a larger decrease in Aß plaque loads in PFC and dentate gyrus (DG) of hippocampus. Similarly, relative to Cur, SLCP produced a larger decrease of pyknotic, or tangle-like, neurons in PFC, CA1, and CA3 areas of hippocampus after 5 days of treatment. Both Cur and or SLCP significantly reduced GFAP-IR and Iba-1-IR in PFC, in the striatum as well as CA1, CA3, DG, subicular complex of hippocampus, and the entorhinal cortex in the 5xFAD mice after 5 days of treatment. CONCLUSIONS: The use of SLCP provides more anti-amyloid, anti-inflammatory, and neuroprotective outcomes than does Cur in the 5xFAD mouse model of AD.

Aß and the dementia syndrome: Simple versus complex perspectives.

BACKGROUND: The amyloid cascade hypothesis (ACH) has dominated strategy in dementia research for decades despite evidence of its limitations including known heterogeneity of the dementia syndrome in the population and the narrow focus on a single molecule - the amyloid beta protein (Aß) as causal for all Alzheimer-type dementia. Other hypotheses relevant to Aß are the presenilin (PS) hypothesis (PSH) relating to the involvement of PS in the generation of Aß, and the amyloid precursor protein (APP) matrix approach (AMA), relating to the complex and dynamic breakdown of APP, from which Aß derives. MATERIALS AND METHODS: In this article we explore perspectives relating to complex disorders occurring mainly in older populations through a detailed case study of the role of Aß in AD. RESULTS: Scrutiny of the evidence generated so far reveals and a lack of understanding of the wider APP proteolytic system and how narrow research into the dementia syndrome has been to date. Confounding factors add significant limitations to the understanding of the current evidence base. CONCLUSIONS: A better characterisation of the entire APP proteolytic system in the human brain is urgently required to place Aß in its complex physiological context. From a molecular perspective, a combination of the alternative hypotheses, the PSH and the AMA may better describe the complexity of the APP proteolytic system leading to new therapeutic approaches. The reductionist approach is widespread throughout biomedical research and this example highlights how neglect of complexity can undermine investigations of complex disorders, particularly those arising in the oldest in our populations.

Neurodegenerative cerebrospinal fluid biomarkers tau and amyloid beta predict functional, quality of life, and neuropsychological outcomes after aneurysmal subarachnoid hemorrhage.

Cerebrospinal fluid (CSF) biomarkers might be useful in predicting outcome after aneurysmal subarachnoid hemorrhage (aSAH). It was the aim to determine whether tau and amyloid beta CSF concentrations predict functional, health-related quality of life (hrQoL), and neuropsychological outcomes after aSAH. Ventricular CSF was obtained from n = 24 aSAH patients at admission (D0), day 2 (D2), and day 6 (D6). CSF total (t)Tau, phosphorylated (p)Tau(181P), and amyloid beta(1-40 and 1-42) (Aß40/Aß42) levels were compared between patients with favorable and unfavorable functional (modified Rankin Scale (mRS)), hrQoL (Euro-Qol (EQ-5D)), and neuropsychological outcomes at 3 (3 m) and 12 months (12 m). Patients with unfavorable functional (mRS 4-6) and hrQoL outcome (EQ-5D z-score ≤ - 1.0) at 3 and 12 m had higher CSF tTau/pTau and lower Aß40/Aß42 at D0, D2, and D6 with varying degrees of statistical significance. In terms of predicting neuropsychological outcome, CSF pTau showed a statistically significant correlation with the z-scores of executive function (r = - 0.7486, p = 0.008), verbal memory (r = - 0.8101, p = 0.002), attention (r = - 0.6498, p = 0.030), and visuospatial functioning (r = - 0.6944, p = 0.017) at 3 m. At 12 m, CSF pTau had statistically significant correlations with the z-scores of verbal memory (r = - 0.7473, p = 0.008) and visuospatial functioning (r = - 0.6678, p = 0.024). In conclusion, higher tTau/pTau and lower Aß40/Aß42 CSF levels predict unfavorable long-term functional and hrQoL outcomes. Neuropsychological deficits correlate with increased CSF tTau and pTau concentrations.

[Protective effect of cyanidin-3-glucoside against injury induced by amyloid ß protein 25-35 in primary cultured hippocampal neurons].

OBJECTIVE: To investigate the neuroprotective effect of cyanidin-3-Oglucoside( Cy-3G). METHODS: Hippocampal neurons were isolated from newborn rat and divided into different groups. ( 1) To estimate the neuroprotective effects, the cells were treated with various concentrations of Cy-3G( 10, 20, 40, 60, 80 and 100 µmol/L) prior to( 3 h) amyloid ß protein( Aß) 25-35 treatment. Neuronal viability in terms of mitochondrial activity was evaluated with the colorimetric tetrazolium salt( MTT) assay. ( 2) To explore the related mechanism, the cells were divided into normal control group, Aß25-35 group, Aß25-35 + Cy-3G co-incubation group and Cy-3G group, then the cell viability was analyzed by Lactate dehydrogenase( LDH) kit. The mitochondrial membrane potential and the intracellular reactive oxygen species( ROS) were respectively detected by Rhodamine 123 and DCFH-DA probe and measured by fluorescence spectrophotometry. RESULTS: ( 1) Relatively, 40 µmol/L Cy-3G and 5 µmol/L Aß25-35 co-incubation for 3 h showed the best protection effect. ( 2) Compared with the control group, the LDH activity in cell media increased significantly in Aß25-35 group( P < 0. 05), while Cy-3G co-incubation was able to reduce LDH activity in cell media significantly( P < 0. 05). Compared with the control group, the mitochondrial membrane potential of the Aß25-35 group decreased significantly( P < 0. 05), Cy-3 G co-incubation could significantly inhibit the decrease of mitochondrial membrane potential of hippocampal neurons induced by Aß25-35( P < 0. 05). Compared with the control group, the levels of intracellular ROS in the Aß25-35 group increased significantly( P < 0. 05), while Cy-3G co-incubation could significantly inhibit the increase of intracellular ROS levels( P < 0. 05). CONCLUSION: The right amount of Cy-3G can protect the primary hippocampal neurons from injury induced by Aß25-35.

Do anti-amyloid beta protein antibody cross reactivities confound Alzheimer disease research?

BACKGROUND: Alzheimer disease (AD) research has focussed mainly on the amyloid beta protein (Aß). However, many Aß-and P3-type peptides derived from the amyloid precursor protein (APP) and peptides thought to derive from Aß catabolism share sequence homology. Additionally, conformations can change dependent on aggregation state and solubility leading to significant uncertainty relating to interpretations of immunoreactivity with antibodies raised against Aß. We review evidence relating to the reactivities of commonly used antibodies including 6F3D, 6E10 and 4G8 and evaluate their reactivity profiles with respect to AD diagnosis and research. RESULTS: Antibody cross-reactivities between Aß-type, P3-type and Aß-catabolic peptides confound interpretations of immunoreactivity. More than one antibody is required to adequately characterise Aß. The relationships between anti-Aß immunoreactivity, neuropathology and proposed APP cleavages are unclear. CONCLUSIONS: We find that the concept of Aß lacks clarity as a specific entity. Anti-Aß antibody cross-reactivities lead to significant uncertainty in our understanding of the APP proteolytic system and its role in AD with profound implications for current research and therapeutic strategies.

Curcumin revitalizes Amyloid beta (25-35)-induced and organophosphate pesticides pestered neurotoxicity in SH-SY5Y and IMR-32 cells via activation of APE1 and Nrf2.

Amyloid beta (Aß) peptide deposition is the primary cause of neurodegeneration in Alzheimer's disease (AD) pathogenesis. Several reports point towards the role of pesticides in the AD pathogenesis, especially organophosphate pesticides (OPPs). Monocrotophos (MCP) and Chlorpyrifos (CP) are the most widely used OPPs. In this study, the role of MCP and CP in augmenting the Aß-induced oxidative stress associated with the neurodegeneration in AD has been assessed in human neuroblastoma IMR-32 and SH-SY5Y cell lines. From the cell survival assay, it was observed that MCP and CP reduced cell survival both dose- and time-dependently. Nitro blue tetrazolium (NBT) based assay for determination of intracellular reactive oxygen species (ROS) demonstrated that Aß(25-35), MCP or CP produce significant oxidative stress alone or synergistically in IMR-32 and SH-SY5Y cells, while pretreatment of curcumin reduced ROS levels significantly in all treatment combinations. In this study, we also demonstrate that treatment of Aß(25-35) and MCP upregulated inducible nitric oxide synthase (iNOS/NOS2) whereas, no change was observed in neuronal nitric oxide synthase (nNOS/NOS1), but down-regulation of the nuclear factor erythroid 2-related factor 2 (Nrf2) level was observed. While curcumin pretreatment resulted in upregulation of iNOS and Nrf2 proteins. Also, the expression of key DNA repair enzymes APE1, DNA polymerase beta (Pol ß), and PARP1 were found to be downregulated upon treatment with MCP, Aß(25-35) and their combinations at 24 h and 48 h time points. In this study, pretreatment of curcumin to the SH-SY5Y cells enhanced the expression of DNA repair enzymes APE1, pol ß, and PARP1 enzymes to counter the oxidative DNA base damage via base excision repair (BER) pathway, and also activated the antioxidant element (ARE) via Nrf2 upregulation. Furthermore, the immunofluorescent confocal imaging studies in SH-SY5Y and IMR-32 cells treated with Aß(25-35) and MCP-mediated oxidative stress and their combinations at different time periods suggesting for cross-talk between the two proteins APE1 and Nrf2. The APE1's association with Nrf2 might be associated with the redox function of APE1 that might be directly regulating the ARE-mediated neuronal survival mechanisms.

Serum Interleukin-10 Levels Correlate with Cerebrospinal Fluid Amyloid Beta Deposition in Alzheimer Disease Patients.

BACKGROUND AND OBJECTIVE: In Alzheimer disease (AD) inflammation becomes evident throughout the course of the disease. However, the association between inflammation, cognitive impairment, and cerebrospinal biomarkers (Aß42, t-tau, p-tau181, and Aß42/p-tau181 ratio) is poorly understood. METHODS: A large panel of inflammatory cytokines (interleukin [IL]-1ß, IL-1ra, IL-2, IL-4, IL-6, IL-10, IL-17, interferon-γ, tumor necrosis factor-α, and vascular endothelial growth factor) was analyzed using a multiplex immunoassay in 27 patients with a diagnosis of AD dementia and in 18 control subjects. In a subgroup with available cerebrospinal fluid (CSF) samples, cytokines in serum were correlated with the levels of neurodegenerative CSF biomarkers (Aß42, t-tau, p-tau181, and Aß42/p-tau181 ratio). RESULTS: Compared to control subjects, AD patients showed a significant upregulation of IL-10, IL-1ß, and IL-17 serum levels. Several cytokines appeared intercorrelated, and IL-10 in particular presented a significant inverse correlation with CFS levels of Aß42 and the Aß42/p-tau ratio. CONCLUSION: Our findings indicate that serum levels of IL-10 may represent a possible peripheral expression of amyloid beta deposition in AD patients.