Age-dependent change in the levels of Abeta40 and Abeta42 in cerebrospinal fluid from control subjects, and a decrease in the ratio of Abeta42 to Abeta40 level in cerebrospinal fluid from Alzheimer's disease patients

In order to address an age-dependent alteration in the concentration of beta-amyloid polypeptides (Abetas) within the central nervous system and its probable predisposition to amyloidgenesis in Alzheimer's disease (AD), we measured two species of soluble Abetas, Abeta40 and Abeta42, in cerebrospinal fluids (CSF) from randomly selected Japanese control subjects at various ages (n = 33) and then compared these data with those of probable Japanese AD patients (n = 23). CSF concentrations of Abeta40 and Abeta42 peptides were age-dependent (ANOVA, Bonferroni's multiple comparison; p < 0.01 and p < 0.05, respectively) and were lower in the infant than in adults. From mid-20, the Abeta40 concentrations were decreasing while Abeta42 were rather stable. Abetas in CSF from AD patients (n = 23), whose epsilon4 allele frequency of the apolipoprotein E gene was higher than in controls (n = 83, p < 0.03), were not statistically different from those of age-matched controls (n = 13). A linear relationship was detected between the Abeta40 concentration and the Mini-Mental State Examination score (p < 0.05). The ratio of the Abeta42 to the Abeta40 level measured in the AD CSF samples was approximately 38% decreased compared to age-matched controls (p < 0. 05). These data suggest that the physiological metabolism of soluble Abetas in the brain is regulated in an age-dependent manner, and that the ratio of Abeta42 to Abeta40 level in the CSF would be a useful marker for monitoring progression of AD.     

The cerebrospinal fluid level of glial fibrillary acidic protein is increased in cerebrospinal fluid from Alzheimer's disease patients and correlates with severity of dementia.

To gain insight of the underlying mechanisms of astroglial response to Alzheimer's disease (AD), the level of glial fibrillary acidic protein (GFAP) in cerebrospinal fluid (CSF) from controls and AD subjects were immunochemically determined, and the correlation between that level and dementia severity of AD patients was evaluated. Means and SD of CSF levels of GFAP for the young control group (from 1 to 25 years, mean +/- SD 14.2 +/- 5.0, n = 13) adult control (from 26 to 55 years, 41.6 +/- 10.1, n = 9) and senescent control (older than 56 years, 65.4 +/- 8.0, n = 8) were 2.96 +/- 1.04, 2.80 +/- 1.46 and 3.99 +/- 1.55 ng/ml, respectively, and the CSF level of GFAP was not dependent on age (ANOVA, p = 0.17). While that of the AD patient group (n = 27, 70.8 +/- 8.0 years) was 8.96 +/- 7.80 ng/ml, significantly higher than that of both the all-control (3.19 +/- 1.39 ng/ml, t test, p < 0.001) and age-matched senescent (3.99 +/- 1.55 ng/ml, t test, p < 0.005) control groups. The receiver-operator characteristic (ROC) curve revealed that the GFAP concentration at 5 ng/ml in CSF could serve as a cutoff value. The CSF level of GFAP in the moderately to severely demented patients (MMSE /= 18, 6.85 +/- 5.76 ng/ml, n = 18; ANOVA, p < 0.05). These findings together with our previous report on an increase in the CSF level of apolipoprotein E suggest that degeneration and stimulation of astrocytes takes place concurrently in the AD brain.     

The neurofilament heavy chain (NfH) in the cerebrospinal fluid diagnosis of Alzheimer's disease

BACKGROUND/AIMS: Attempting to improve the cerebrospinal fluid (CSF) diagnosis of Alzheimer's disease (AD), the neurofilament heavy chain isoform, NfH(SMI35) was compared to other CSF markers [total tau, phospho-tau, amyloid beta 1-42 (Abeta42), the ratio of amyloid beta fragments Abeta42/Abeta40 (Abeta ratio)]. METHODS: CSF levels were determined in patients with AD (n = 109), mild cognitive impairment (MCI, n = 25), frontotemporal dementia (n = 15), vascular dementia (VD, n = 41), and controls (n = 58). RESULTS: CSF NfH(SMI35) was elevated in AD and VD as compared to controls (p < 0.05). Total tau was higher in AD as compared to controls (p < 0.05). CSF phospho-tau was elevated in AD as compared to controls and VD (p < 0.05 each). CSF Abeta42 and Abeta ratios in AD were lower than in MCI and controls (p < 0.05 each). CONCLUSION: The diagnostic potential of NfH(SMI35) is not superior to that of other CSF markers.     

The cerebrospinal fluid levels of tau, growth-associated protein-43 and soluble amyloid precursor protein correlate in Alzheimer's disease, reflecting a common pathophysiological process

Cerebrospinal fluid (CSF) levels of tau (total tau), growth-associated protein-43 (GAP-43), soluble amyloid precursor protein (sAPP; i.e. total sAPP), and beta-amyloid(42) (Abeta(42)) were studied in patients with frontotemporal dementia (FTD; n = 14), Alzheimer's disease (AD; n = 47) and vascular dementia (VAD; n = 16), and in age-matched controls (n = 12). CSF-tau was increased in AD compared to controls and FTD (p < 0.001 for both). CSF-GAP-43 was increased in AD compared to controls (p < 0.05), and both CSF-GAP-43 and CSF-sAPP were increased in AD compared to FTD (p < 0.01). Positive and highly significant correlations were found between CSF-tau and CSF-GAP-43 in all groups and between CSF-tau, CSF-GAP-43 and CSF-sAPP in AD. The correlations found may reflect a common pathophysiologic process such as axonal degeneration.     

Apolipoprotein E phenotypes in healthy normal controls and demented subjects with Alzheimer's disease and vascular dementia in Mie Prefecture of Japan

In order to clarify the association between apolipoprotein E4 (ApoE4) and the pathogenesis of Alzheimer's disease (AD), we analyzed the distribution of the apolipoprotein E (ApoE) phenotypes and the frequency of the apo E alleles epsilon2, epsilon3, and epsilon4 in Japanese healthy controls (n = 1090, an average age of 51.2+/-12.6 years) and demented patients (n=103, mean age of 73.6+/-9.2 years). Demented subjects were divided into three subgroups: early-onset AD group (EOAD; n=25, mean age 63.0+/-6.2 years), late-onset AD group (LOAD; n=33, mean age 79.3+/-5.1 years), and vascular dementia group (VD; n=45, mean age 75.3+/-8.0 years). The apolipoprotein E phenotype was determined by isoelectric focusing and immunoblotting. There were no significant differences in the distribution of the apo E phenotypes by gender or age, and the estimated frequencies of epsilon2, epsilon3 and epsilon4 were 0.05, 0.86 and 0.09, respectively, in the normal controls. There was a significant difference in the distribution of the apo E phenotypes between LOAD and elderly controls aged more than 65 years (P<0.0001). The distribution of the apo E phenotypes in EOAD was the same as that in LOAD. The frequency of the epsilon4 allele was significantly higher in LOAD (0.35, P<0.0001) and EOAD (0.28, P<0.0001) than that in the control subjects (0.07), but not in VD (0.12, P=0.1630). The present findings suggest that ApoE4 is related with both EOAD and LOAD, but not with VD, and support the hypothesis that it is a genetic risk factor of AD.     

Decreased cerebrospinal fluid acetylcholinesterase in patients with subcortical ischemic vascular dementia

The main objective was to investigate the acetylcholinesterase E (AChE) activity in the cerebrospinal fluid (CSF) of patients with three common dementia disorders. We also wanted to investigate the influence of apolipoprotein E (ApoE) epsilon4 allele possession and CSF-tau level on the CSF-AChE activity in these patients. The study included 17 consecutive patients with subcortical vascular dementia (SVD), 39 with Alzheimer's disease (AD), 14 with frontotemporal dementia (FTD) and 12 controls. CSF was obtained by lumbar puncture and CSF-AChE activity was measured by an enzyme antigen immunoassay. CSF-AchE activity was significantly decreased compared to controls only in the SVD group (p = 0.010). The CSF-tau level was increased in the AD group compared to the control (p < 0.01) and FTD groups (p < 0.05). No influence of ApoE epsilon4 allele possession on CSF-AChE activity was found. It is suggested that abnormal CSF-AChE activity in patients with SVD reflects a disturbance in the cholinergic system.     

Normal cerebrospinal fluid glutathione concentrations in Parkinson's disease, Alzheimer's disease and multiple system atrophy.

We measured total glutathione concentrations in the cerebrospinal fluid (CSF) of non-demented Parkinson's disease patients (PD; n=71), demented PD patients (PDD; n=13), multiple system atrophy patients (MSA; n=10), Alzheimer's disease patients (AD; n=17) and age-matched controls (n=21). No statistically significant differences in the mean total CSF glutathione concentrations were found between groups and dopaminomimetic treatment was not found to have any effect on total CSF glutathione levels. Our main conclusion is that total glutathione is not useful as a CSF marker for assumed oxidative stress in patients with PD, MSA or AD.     

Measurement of alpha- and beta-secretase cleaved amyloid precursor protein in cerebrospinal fluid from Alzheimer patients

One of the major histopathological hallmarks of Alzheimer's disease (AD) is redundant senile plaques mainly composed of beta-amyloid (Abeta) aggregates. Alternative cleavage of the amyloid precursor protein (APP), occurring in both normal and AD subjects, results in the generation and secretion of soluble APP (sAPP) and Abeta. We examined the cerebrospinal fluid (CSF) for alpha- and beta-secretase cleaved sAPP (alpha-sAPP and beta-sAPP) in 81 sporadic AD patients, 19 patients with mild cognitive impairment, and 42 healthy controls by using newly developed sandwich enzyme-linked immunosorbent assay methods. We found that neither the level of CSF-alpha-sAPP nor CSF-beta-sAPP differed between sporadic AD patients and healthy controls. These findings further support the conclusion that there is no change in APP expression in sporadic AD. However, the level of CSF-beta-sAPP was significantly increased in patients with mild cognitive impairment compared to controls. We also investigated the relationship between the CSF level of alpha/beta-sAPP and Abeta(42) and the apoE epsilon 4 (apoE4) allele. Significantly lower levels of CSF-alpha-sAPP were found in AD patients possessing one or two apoE4 alleles than in those not possessing the apoE4 allele. Neither the levels of CSF-beta-sAPP nor CSF-Abeta(42) differed when comparing ApoE4 allele-positive with allele-negative individuals.     

Quantitative proteomics of cerebrospinal fluid from patients with Alzheimer disease

Biomarkers to assist in the diagnosis and medical management of Alzheimer disease (AD) are a pressing need. We have employed a proteomic approach, microcapillary liquid chromatography mass spectrometry of proteins labeled with isotope-coded affinity tags (ICAT), to quantify relative changes in the proteome of human cerebrospinal fluid (CSF) obtained from the lumbar cistern. Using CSF from well-characterized AD patients and age-matched controls at 2 different institutions, we quantified protein concentration ratios of 42% of the 390 CSF proteins that we have identified and found differences > or = 20% in over half of them. We confirmed our findings by western blot and validated this approach by quantifying relative levels of amyloid precursor protein and cathepsin B in 17 AD patients and 16 control individuals. Quantitative proteomics of CSF from AD patients compared to age-matched controls, as well as from other neurodegenerative diseases, will allow us to generate a roster of proteins that may serve as specific biomarker panels for AD and other geriatric dementias.     

Reduced CSF PLTP activity in Alzheimer's disease and other neurologic diseases; PLTP induces ApoE secretion in primary human astrocytes in vitro

Phospholipid transfer protein (PLTP) plays a pivotal role in cellular lipid efflux and modulation of lipoprotein metabolism. PLTP is distributed widely in the central nervous system (CNS), is synthesized by glia and neurons, and is active in cerebrospinal fluid (CSF). The aims of this study were to test the hypothesis that patients with Alzheimer's disease (AD) have altered PLTP-mediated phospholipid transfer activity in CSF, and to examine the potential relationship between PLTP activity and apolipoprotein E (apoE) levels in CSF. We assessed PLTP activity and apoE concentration in CSF of patients with probable AD (n = 50), multiple sclerosis (MS; n = 9), other neurologic diseases (n = 21), and neurologically healthy controls (n = 40). PLTP activity in AD was reduced compared to that in controls (P < 0.001), with approximately half of the AD patients with PLTP activity values below all controls. Patients with MS had lower PLTP activity than AD patients (P < 0.001). PLTP activity was highly correlated with PLTP mass, as estimated by Western blot (r = 0.006; P < 0.01). CSF PLTP activity positively correlated with apoE concentration in AD (R = 0.435; P = 0.002) and controls (R = 0.456; P = 0.003). Anti-apoE immunoaffinity chromatography and Western blot analyses indicated that some CSF PLTP is associated with apoE-containing lipoproteins. Exogenous addition of recombinant PLTP to primary human astrocytes significantly increased apoE secretion to the conditioned medium. The findings of reduced PLTP activity in AD CSF, and the observation that PLTP can influence apoE secretion in astrocytes suggest a potential link between alterations in the brain lipid metabolism and AD pathogenesis.     

Hyperconnectivity matters in early-onset Alzheimer's disease: a resting-state EEG connectivity study

ObjectivesThe aim of this study was to differentiate individuals with early-onset Alzheimer's disease (EOAD) and identify differences of functional connectivity in resting-state EEG between individuals with EOAD and late-onset AD (LOAD) in comparison with both healthy young and elderly individuals.MethodsForty EOAD and 56 LOAD patients were included along with 51 demographically matched young, and 54 elderly healthy individuals as controls to the EOAD and LOAD groups. Four minutes of resting-state EEG were recorded during the eyes-closed condition. The absolute value of imaginary coherence (ICoh) was measured for connectivity. The maximum values of ICoh were measured at delta (0.5-3.5 Hz), theta (4-7.5Hz), alpha (8-13 Hz), alpha-1 (8-10 Hz), alpha-2 (10.5-13 Hz), beta (13-30 Hz), beta-1 (13-20 Hz), and beta-2 (20.5-30 Hz) frequency bands.ResultsIndividuals with EOAD showed higher coherence values in all frequency bands than LOAD patients. Compared to young healthy controls (YHC), EOAD had increased ICoh values in theta and beta-2 bands, whereas LOAD had lower ICoh values in the alpha-1 band than elderly healthy controls (EHC). Lastly, patients with EOAD demonstrated negative moderate correlations between language domains and beta-1 ICoh values.ConclusionTo the authors’ knowledge, this is the first study evaluating coherence alterations among early-and late-onset AD patients and the diagnostic value of coherence measures. It was suggested that EOAD patients had more severe pathological changes compared with LOAD.     

Genetic variation in apolipoprotein D and Alzheimer’s disease

Apolipoprotein D (apoD) is a lipoprotein-associated glycoprotein, structurally unrelated to apoE, that transports small hydrophobic ligands including cholesterol and sterols. Levels are increased in the hippocampus and CSF of Alzheimer's disease (AD) patients. We tested whether variation in the APOD gene affects AD risk. Four single nucleotide polymorphisms (SNPs) were investigated (in map order): exon 2, 15T-->C encodes an amino acid substitution Phe-->Ser at codon 15; intron 2, -352G-->A; intron 3, +45C-->T; intron 4, +718C-->T, determined by SNaPshot assay. SNP frequencies for 394 eastern Finnish AD patients were compared with those found for 470 control subjects, dividing subjects also into early-onset AD (EOAD; < or = 65 years) and late-onset AD (LOAD; >65 years) groups. The -352G allele was associated with a significant 3-fold increase in the risk of EOAD (OR: 2.7; 95% CI: 1.1-6.5). The -352G containing haplotypes were more common for EOAD cases (TGCC: 0.48 vs 0.41; TGCT: 0.08 vs 0.01 (p = 0.002). In the Grade-of-membership analysis, APOD genotype frequencies at each SNP site and disease status were used to construct two latent groups: the affected group carried -352 as GG or GA and +45 CC, was often women and enriched in APOE epsilon4. Each method suggested that the -352G allele frequency is higher for EOAD in the eastern Finnish population.     

Decreased CSF-beta-amyloid 42 in Alzheimer's disease and amyotrophic lateral sclerosis may reflect mismetabolism of beta-amyloid induced by disparate mechanisms

Both tau and beta-amyloid 42 (Abeta42) have been implicated in Alzheimer's disease (AD) and tau alone in frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). These proteins can be measured in the cerebrospinal fluid (CSF); differences from normal CSF levels may reflect pathophysiological mechanisms. Using ELISAs, we investigated the levels of total CSF-tau (here referred to as tau), phosphorylated CSF-tau (phosphotau), and Abeta42 in patients with AD (n = 19), FTD (n = 14), ALS (n = 11) and Parkinson's disease (PD; n = 15) and in age-matched controls (n = 17). Both CSF-tau and CSF-phosphotau were increased in AD compared with FTD (p < 0.001), ALS (p < 0.001), PD (p < 0.001) and controls (p < 0.001). CSF-Abeta42 was markedly decreased in AD and ALS (both p < 0.001) and slightly decreased in FTD (p < 0.01) and PD (p < 0.05) compared with controls. Using CSF-phosphotau may improve the differentiation of AD from FTD and ALS in clinical praxis. Furthermore, decreased CSF-Abeta42 levels may be common in neurodegenerative disorders possibly reflecting changes in the metabolism of beta-amyloid or axonal degeneration.     

Inflammatory markers in matched plasma and cerebrospinal fluid from patients with Alzheimer's disease

It has been suggested that a number of molecules associated with inflammation are involved in the pathogenesis of Alzheimer's disease (AD). We measured the levels of alpha(1)-antichymotrypsin (ACT), alpha(1)-antitrypsin (AAT), interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1) and oxidised low-density lipoprotein (oxLDL) in matched cerebrospinal fluid (CSF) and plasma of 141 patients with probable AD. We found a significant relationship between CSF and plasma levels of ACT (r = 0.4, p < 0.001), IL-6 (r = 0.74, p < 0.001), MCP-1 (r = 0.71, p < 0.001), and a borderline relationship between CSF and plasma oxLDL (r = 0.22, p < 0.05). In addition, linear regression analysis revealed a positive correlation between levels of CSF-ACT and oxLDL (p < 0.001), but an inverse relation between levels of CSF ACT, CSF AAT and MCP-1 (p < 0.001). A significant correlation was also found between levels of CSF ACT, oxLDL and the ratio of CSF to serum albumin, which is used as a measure of the blood-brain barrier function. Our data extend previous reports regarding the inflammatory markers in the plasma and CSF of patients with AD and provide good evidence that levels of ACT, IL-6, MCP-1 and oxLDL in plasma and CSF might be candidates as biomarkers for monitoring the inflammatory process in AD.     

The alpha2-macroglobulin gene in AD: a population-based study and meta-analysis

BACKGROUND: Whereas several authors recently reported a positive association between the alpha2-macroglobulin gene (A2M) and late-onset AD (LOAD), others were unable to replicate these findings. Early-onset AD (EOAD) is defined as onset age <65 years. Virtually all patients with LOAD are >65 years of age. OBJECTIVE: To evaluate the role of A2M in AD, the authors conducted a population-based study of EOAD and LOAD as well as a meta-analysis of all studies conducted to date. METHODS: Patients with EOAD (n = 100) were derived from a population-based study in four northern provinces of the Netherlands and the area of metropolitan Rotterdam. Patients with LOAD (n = 344) were drawn from the Rotterdam Study, a population-based prospective study on residents aged 55 years and over of a Rotterdam suburb in the Netherlands. Two polymorphisms were studied, A2M-I/D and A2M-Ile1000Val, in relation to the APOE epsilon4 allele (APOE*4). RESULTS: No genotypic or allelic association was found for either polymorphism in the population-based series of patients with LOAD. In patients with EOAD without APOE*4, a significant increase of carriers of A2M-1000Val was found. The meta-analysis of available published case-control data on these polymorphisms in white and mixed ethnic populations yielded no significant differences between cases and controls. Pooling the Asian studies conducted to date showed a significant decrease in the frequency of A2M-D among patients. CONCLUSIONS: These results suggest that A2M is not genetically associated with LOAD in white patients or mixed populations as found in the United States. In these populations A2M does not have clinical relevance. From a scientific perspective, the findings on EOAD and Asian patients require replication and further research in the A2M region.     

Identification of SPARC-like 1 protein as part of a biomarker panel for Alzheimer's disease in cerebrospinal fluid

We have used proteomic fingerprinting to investigate diagnosis of Alzheimer's disease (AD). Samples of lumbar cerebrospinal fluid (CSF) from clinically-diagnosed AD cases (n = 33), age-matched controls (n = 20), and mild cognitive impairment (MCI) patients (n = 10) were used to obtain proteomic profiles, followed by bioinformatic analysis that generated a set of potential biomarkers in CSF samples that could discriminate AD cases from controls. The identity of the biomarker ions was determined using mass spectroscopy. The panel of seven peptide biomarker ions was able to discriminate AD patients from controls with a median accuracy of 95% (sensitivity 85%, specificity 97%). When this model was applied to an independent blind dataset from MCI patients, the intensity of signals was intermediate between the control and AD patients implying that these markers could potentially predict patients with early neurodegenerative disease. The panel were identified, in order of predictive ability, as SPARC-like 1 protein, fibrinogen alpha chain precursor, amyloid-β, apolipoprotein E precursor, serum albumin precursor, keratin type I cytoskeletal 9, and tetranectin. The 7 ion ANN model was further validated using an independent cohort of samples, where the model was able to classify AD cases from controls with median accuracy of 84.5% (sensitivity 93.3%, specificity 75.7%). Validation by immunoassay was performed on the top three identified markers using the discovery samples and an independent sample cohort which was from postmortem confirmed AD patients (n = 17).     

Decreased plasma and cerebrospinal fluid levels of stem cell factor in patients with early Alzheimer's disease

Alzheimer's disease (AD) is characterized by massive neuronal cell loss in the brain. Stem cell factor (SCF) is a hematopoietic growth factor (HGF) that promotes neuroprotective effects and supports neurogenesis in the brain. In the present study, we found significantly lower SCF plasma levels in 30 early AD patients (908.5 +/- 181.7 pg/ml) in comparison with 30 age-matched healthy controls (1058.3 +/- 221.5 pg/ml; p = 0.006). SCF plasma levels in AD patients showed a significant inverse correlation with dementia severity as measured by ADAS-Cog (r = -0.289; p = 0.037). AD patients showed significantly lower SCF levels in cerebrospinal fluid (CSF) (131.60 +/- 43.03 pg/ml) in comparison with 15 age- and gender-matched patients with other non-inflammatory neurological disease (NIND) (166.03 +/- 42.5 pg/ml; p = 0.017). In addition, we found significant positive correlations between SCF and CXCL12 (also known as SDF-1) plasma levels in healthy controls (r = 0.341; p = 0.008) and between SCF and CXCL12 CSF levels in AD patients (r = 0.487; p < 0.001). In conclusion, decreased SCF plasma and CSF levels in early AD patients may contribute to a deficient hematopoietic brain support with putative pathogenic and clinical relevance. Further studies are needed to examine whether a manipulation of HGFs such as SCF could be a promising new therapeutic strategy for AD.     

Functional connectivity changes differ in early and late‐onset alzheimer's disease

At a similar stage, patients with early onset Alzheimer's disease (EOAD) have greater neocortical but less medial temporal lobe dysfunction and atrophy than the late‐onset form of the disease (LOAD). Whether the organization of neural networks also differs has never been investigated. This study aims at characterizing basal functional connectivity (FC) patterns of EOAD and LOAD in two groups of 14 patients matched for disease duration and severity, relative to age‐matched controls. All subjects underwent an extensive neuropsychological assessment. Magnetic resonance imaging was used to quantify atrophy and resting‐state FC focusing on : the default mode network (DMN), found impaired in earlier studies on AD, and the anterior temporal network (ATN) and dorso‐lateral prefrontal network (DLPFN), respectively involved in declarative memory and executive functions. Patterns of atrophy and cognitive impairment in EOAD and LOAD were in accordance with previous reports. FC within the DMN was similarly decreased in both EOAD and LOAD relative to controls. However, a double‐dissociated pattern of FC changes in ATN and DLPFN was found. EOAD exhibited decreased FC in the DLPFN and increased FC in the ATN relative to controls, while the reverse pattern was found in LOAD. In addition, ATN and DLPFN connectivity correlated respectively with memory and executive performances, suggesting that increased FC is here likely to reflect compensatory mechanisms. Thus, large‐scale neural network changes in EOAD and LOAD endorse both common features and differences, probably related to a distinct distribution of pathological changes. Hum Brain Mapp 35:2978–2994, 2014. © 2013 Wiley Periodicals, Inc.     

Cerebrospinal fluid lipoprotein delivery to human neuronal cells is increased in Alzheimer's disease and is dependent on apoE monomer concentration

Recent studies of cerebrospinal fluid (CSF) have shown increased oxidation of CSF lipoproteins in Alzheimer's disease (AD) patients, and neurotoxicity from oxidized CSF lipoproteins in culture. Since inheritance of different alleles of the apolipoprotein (apo) E gene is a risk factor for AD and apoE is the major lipoprotein trafficking molecule in brain, we hypothesized that apoE may modify the pathogenesis of AD by directing the delivery of oxidized CSF lipoproteins to neurons. To test this hypothesis, we adapted a method previously used with isolated plasma lipoproteins to specifically label lipid particles in situ in native CSF and quantified their delivery to human SK-N-BE(2)C neuroblastoma cells. CSF lipoproteins were delivered to neuronal cells largely through apoE-dependent processes. Importantly, CSF lipoproteins from AD patients were delivered more efficiently than CSF lipoproteins from age-matched controls; this effect was not associated with apoE genotype or degree of CSF lipoprotein oxidation but was associated with apoE monomer concentration that tended to be lower in AD patients. The inverse relationship between apoE monomer concentration and CSF lipoprotein delivery was duplicated in SK-N-BE(2)C cells, but not human astrocytoma cells, using artificial lipid particles and purified human apoE. These results suggest that lipoproteins in CSF from AD patients are delivered more efficiently to neurons than are CSF lipoproteins from controls, and that this abnormality may be explained largely by variations in CSF apoE concentration.     

Remarkable increase in the concentration of 8-hydroxyguanosine in cerebrospinal fluid from patients with Alzheimer's disease

To investigate the possible role of oxidative RNA damage in the pathogenesis of Alzheimer's disease (AD), the concentrations of the oxidative stress marker 8-hydroxyguanosine (8-OHG) were measured in the cerebrospinal fluid (CSF) and the serum of patients with AD and control subjects. The concentration of 8-OHG in CSF in AD patients was approximately fivefold that in controls (P < 0.001). The concentration of 8-OHG in CSF decreased significantly with the duration of illness (r(s) = -0.48, P < 0.05) and the progression of cognitive dysfunctions (r(s) = 0.67, P < 0.01). However, the concentration of 8-OHG in CSF showed no correlation with that in serum in both the controls and AD patients. In addition, the concentration of 8-OHG in serum was not significantly altered in AD patients compared to that in controls, suggesting that the 8-OHG concentrations in the CSF do not reflect those in serum and may be probably reflect those in brain tissue. These in vivo findings suggest a possible role of 8-OHG and increased oxidative RNA damage in the early stage of the development of AD.