Soluble interleukin-1 receptor type II levels are elevated in cerebrospinal fluid in Alzheimer's disease patients

Evidence from epidemiological, clinical and experimental studies favour the hypothesis that inflammatory events are part of the neuropathology in Alzheimer's disease. Proinflammatory cytokines such as interleukin-1 (IL-1), interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-alpha) have been found in activated microglia in the vicinity of amyloid plaques in Alzheimer's disease brain. In the present study, the levels of soluble IL-1 receptor type II (sIL-1R type II), IL-1 receptor antagonist (IL-1ra), IL-1beta, IL-6 and TNF-alpha were analyzed in cerebrospinal fluid (CSF) samples from Alzheimer's disease patients and control subjects. The levels of sIL-1R type II were significantly higher in CSF from Alzheimer's disease patients than in CSF samples from control subjects (38.5+/-8 pg/ml (mean+/-S.E.M.) vs. 7.9+/-4 pg/ml, p<0.05). Measurements of the proinflammatory cytokines IL-6 and TNF-alpha showed no significant difference between the two groups, and the levels of IL-1beta and IL-1ra in the present material were too low to permit detection. The increased levels of sIL-1R type II may reflect a compensatory mechanism to balance an increased release of IL-1 receptor agonists in the Alzheimer's disease brain.     

Decreased cerebrospinal fluid levels of β-endorphin in Japanese patients with Joseph disease

We measured the cerebrospinal fluid (CSF) levels of β-endorphin in 7 Japanese patients with Joseph disease and compared them with control values. The 7 patients included 4 with type I and 3 with type II disease; their mean age was 45.7 ± 12.09 years. Diseased controls were matched in age to the patients studied. In these patients, CSF β-endorphin level was significantly lower than in the controls (40% of normal values). An alteration in CSF β-endorphin level may explain some of the neurological impairment found in Joseph disease.     

Concentrations of amyloid β protein in cerebrospinal fluid of patients with alzheimer's disease

Deposition of fibrillar amyloid β protein (Aβ) is increased in brains of patients with Alzheimer's disease. Concentrations of Aβ were measured in cerebrospinal fluid with an enzyme-linked immunosorbent assay in 10 neurological patients free from neurodegenerative disease, 28 patients with Parkinson's disease, and 18 patients with probable Alzheimer's disease. Levels of Aβ in cerebrospinal fluid were not significantly different among these groups. This observation suggests that concentrations of soluble Aβ in cerebrospinal fluid as measured in this study do not reflect the amount of fibrillar, aggregated Aβ in the brain of patients with Alzheimer's disease.     

Reduction of β-amyloid peptide42 in the cerebrospinal fluid of patients with Alzheimer's disease

In this clinical study, the cerebrospinal fluid (CSF) level of a Novemberel form of the β-amyloid peptide (Aβ) extending to position 42 (Aβ₄₂) was determined in patients with Alzheimer's disease (AD) as well as controls. In addition to measurement of CSF Aβ₄₂ levels, total Aβ peptides, microtubule-associated protein τ, and apolipoprotein E (ApoE) genotype were also assessed. It is interesting that CSF Aβ₄₂ levels were found to be significantly lower in AD patients relative to controls, whereas total Aβ levels were not. Aβ₄₂ has recently been shown to preferentially deposit in the brain tissue of patients with AD, suggesting that diminished clearance may account for its reduction in CSF. As previously reported, τ levels were increased in AD patients; however, neither Aβ₄₂ nor τ levels were apparently influenced by the ApoE genotype.     

Amyloid β protein (Aβ) deposition in chromosome 14–linked Alzheimer's disease: Predominance of Aβ42(43)

Amyloid β protein (Aβ) deposition was investigated in the frontal cortex of 8 cases of (genetically confirmed) chromosome 14–linked Alzheimer's disease (AD) using the end-specific monoclonal antibodies BA27 and BC05 to detect the presnce of Aβ₄₀ and Aβ₄₂₍₄₃₎, respectively. IN all patients, Aβ₄₂₍₄₃₎ was the predominant peptide species present. The total amount of Aβ₄₀ and Aβ₄₂₍₄₃₎ deposited was more than twice the amount deposited in cases of sporadic AD of similar disease duration, although the ratio between the extent of Aβ₄₀ and Aβ₄₂₍₄₃₎ deposition was unaltered, compared with sporadic AD. Therefore, (one of) the effects of the mutations in the presenilin 1:PS-1 (S182) gene may be to cause or at least promote an early and excessive deposition of Aβ₄₂₍₄₃₎ within the brain, a property shared with other inherited forms of AD, such as those due to amyloid precursor protein mutations, and Down's syndrome (trisomy 21).     

Increased cerebrospinal fluid cAMP levels in Alzheimer's disease

Since increasing evidence suggests that upregulation of the cAMP-second messenger system may be implicated in Alzheimer's disease neurodegeneration, we have compared the cAMP and cGMP levels in cerebrospinal fluid (CSF) from patients with dementia of the Alzheimer type (DAT, n=10) with those from nondemented age-matched controls (n=10). Our results show that cAMP levels, but not cGMP, are significantly (p<0.01) elevated in CSF from patients with DAT compared to those from nondemented controls. Moreover, a linear regression analysis demonstrated a significant correlation (r=0.62; p<0.01) between cAMP and tau protein levels in CSF when controls and patients with DAT were studied together. These results suggest that upregulation of cAMP-signaling pathway is implicated in Alzheimer's disease physiopathology.     

Apolipoprotein E ε2 does not increase risk of early-onset sporadic Alzheimer's disease

We examined the association of apolipoprotien E (ApoE) genotype and the risk of early-onset Alzheimer's disease (AD) in 209 white early-onset sporadic cases (43% male) and 303 white controls (48% male) of similar age distribution. The risk of AD was significantly increased, relative to the 3/3 genotype, in people with the 4/4, 3/4, and 2/4 genotypes, controlling for age at time of examination and sex. The 2/3 genotype reduced slightly the risk of AD, although the effect was not statistically significant. We conclude, contrary to some previous reprots, that the ApoE ε2 allele does not increase the risk of early-onset sporadic AD.     

Amyloid precursor protein mRNA levels in Alzheimer's disease brain

Insoluble beta-amyloid deposits in Alzheimer's disease (AD) brain are proteolytically derived from the membrane bound amyloid precursor protein (APP). The APP gene is differentially spliced to produce isoforms that can be classified into those containing a Kunitz-type serine protease inhibitor domain (K(+), APP(751), APP(770), APRP(365) and APRP(563)), and those without (K(-), APP(695) and APP(714)). Given the hypothesis that Abeta is a result of aberrant catabolism of APP, differential expression of mRNA isoforms containing protease inhibitors might play an active role in the pathology of AD. We took 513 cerebral cortex samples from 90 AD and 81 control brains and quantified the mRNA isoforms of APP with TaqMan real-time RT-PCR. After adjustment for age at death, brain pH and gender we found a change in the ratio of KPI(+) to KPI(-) mRNA isoforms of APP. Three separate probes, designed to recognise only KPI(+) mRNA species, gave increases of between 28% and 50% in AD brains relative to controls (p=0.002). There was no change in the mRNA levels of KPI-(APP 695) (p=0.898). Therefore, whilst KPI-mRNA levels remained stable the KPI(+) species increased specifically in the AD brains.     

Amyloid precursor protein gene mutations responsible for early-onset autosomal dominant Alzheimer's disease

According to the "amyloid cascade hypothesis", the accumulation of A beta peptides in the brain is a primary event in the pathogenesis of Alzheimer's disease (AD). Other pathological features (neurofibrillary tangles, neuronal damage and cell death) are regarded as secondary. One of the strong pieces of evidence supporting this hypothesis was the identification of over 20 pathogenic mutations within the APP gene responsible for familial EOAD. The APP mutations are located close to the sites recognised by the alpha-, beta- and gamma-secretases. The mutations affect the APP processing, causing overproduction of A beta42 peptide. The imbalance between A beta production and A beta clearance releases a cascade of subsequent cellular processes leading to AD. In this paper, all APP mutations have been summarised and their molecular effects on the APP metabolism have been discussed.     

Longitudinal study of cerebrospinal fluid levels of tau,Aβ1–40, and Aβ1–42(43) in Alzheimer's disease: A study in Japan

To clarify the alterations of tau, amyloid β protein (Aβ) 1–40 and Aβ1–42(43) in the cerebrospinal fluid (CSF) that accompany normal aging and the progression of Alzheimer's disease (AD), CSF samples of 93 AD patients, 32 longitudinal subjects among these 93 AD patients, 33 patients with non-AD dementia, 56 with other neurological diseases, and 54 normal control subjects from three independent institutes were analyzed by sensitive enzyme-linked immunosorbent assays. Although the tau levels increased with aging, a significant elevation of tau and a correlation between the tau levels and the clinical progression were observed in the AD patients. A significant decrease of the Aβ1–42(43) levels and a significant increase of the ratio of Aβ1–40 to Aβ1–42(43) were observed in the AD patients. The longitudinal AD study showed continuous low Aβ1–42(43) levels and an increase of the ratio of Aβ1–40 to Aβ1–42(43) before the onset of AD. These findings suggest that CSF tau may increase with the clinical progression of dementia and that the alteration of the CSF level of Aβ1–42(43) and the ratio of Aβ1–40 to Aβ1–42(43) may start at early stages in AD. The assays of CSF tau, Aβ1–40, and Aβ1–42(43) provided efficient diagnostic sensitivity (71%) and specificity (83%) by using the production of tau levels and the ratio of Aβ1–40 to Aβ1–42(43), and an improvement in sensitivity (to 91%) was obtained in the longitudinal evaluation.     

Elevated levels of tau in cerebrospinal fluid: implications for the antemortem diagnosis of Alzheimer's disease elevated levels of tau in cerebrospinal fluid: implications for the antemortem diagnosis of Alzheimer's disease

Alzheimer's disease (AD) is a heterogeneous group of dementias characterized by progressive cognitive impairments as well as by the accumulation of abundant extracellular deposits of Ass and intra-neuronal neurofibrillary lesions in selective-ly vulnerable regions of the AD brain. The latter abnormalities (e.g. neurofibrillary tangles, dystrophic neurites, neuropil threads) are aggregates of paired helical filaments (PHFs) formed from altered tau proteins (PHFtau). Although PHF tau and normal central nervous system (CNS) tau are phosphorylated at nearly the same sites, PHFtau is phosphorylated to a greater extent, and alterations in the activity of CNS kinases and phosphatases most likely contribute to the pathogenesis of PHFtau. Since the abundance of neurofibrillary lesions correlates with the dementia in AD, the generation of PHFtau and the formation of neurofibrillary lesions may be part of a cell death pathway leading to massive neuron loss and dementia in AD. Building upon these and other insights into altered tau metabolism in AD, a series of studies suggest that the diagnosis of AD may be supported in living patients by determining the concentration of tau in cerebrospinal fluid (CSF). We review these promising studies here, and discuss them in the context of current understanding of the pathobiology of AD.     

Increased levels of neuronal thread protein in cerebrospinal fluid of patients with Alzheimer's disease

Neuronal thread protein is a recently characterized, ～20-kd protein that accumulates in brains with Alzheimer's disease (AD) lesions. This study examined whether concentrations of neuronal thread protein (NTP) were also increased in the cerebrospinal fluid (CSF) of individuals with probable (clinically diagnosed) and definite (histopathologically proved) AD. Using a highly sensitive three-site monoclonal antibody–based immunoradiometric assay, we measured NTP concentrations in CSF from 84 patients with probable AD and mild dementia (duration, 4.05 ± 0.36 years), 45 with Parkinson's disease and minimal or no dementia (duration, 4.73 ± 0.78 years), 73 with multiple sclerosis, and 73 nondemented control subjects. NTP concentrations were also measured in postmortem ventricular fluid and temporal lobe neocortex extracts from 31 subjects with histopathologically proved AD and 14 age-matched control subjects. The mean concentration of NTP in the CSF was higher in AD (4.15 ± 0.25 ng/ml; 95% confidence interval [CI] limits, 3.65–4.65) than in Parkinson's disease (1.96 ± 0.16 ng/ml; 95% CI, 1.65–2.27), multiple sclerosis (1.6 0.14 ng/ml; 95% CI limits, 1.33–1.88), or control subjects (1.27 ± 0.06 ng/ml; 95% CI limits, 1.15–1.40) (p < 0.001). In addition, 70% of the patients with probable AD had concentrations of NTP in CSF that were higher than 2.5 ng/ml (> upper 99% CI limit in the control group), compared with 23%of Parkinson's disease patients, 11% of multiple sclerosis patients, and 40% of control subjects. The mean concentrations of NTP in the ventricular fluid and brain tissue from individuals with documented AD and end-stage dementia were threefold higher than the levels detected in the CSF from the remaining patients with probable AD and mild dementia. Moreover, of 9 patients with AD, postmortem brain and CSF manifested 5- to 50-fold higher levels of NTP compared with the CSF samples obtained an average of 6 years earlier. These findings demonstrate that NTP levels are elevated in the CSF of individuals with AD and that NTP levels in the CSF increase strikingly with progression of dementia and neuronal degeneration.     

Cerebrospinal fluid F2-isoprostane levels are increased in Alzheimer's disease

Postmortem studies have associated Alzheimer's disease (AD) with regionally increased oxidative damage to brain. Lacking, however, is a specific marker of oxidative damage to brain that may be measured during life. We tested the hypothesis that cerebrospinal fluid (CSF) concentrations of F₂-isoprostanes (F₂-IsoPs), stable products of arachidonate peroxidation, are increased in CSF of AD patients. CSF from lateral ventricles (VF) was analyzed from 11 AD patients and 11 control subjects who participated in a rapid autopsy program. VF F₂-IsoP concentrations were significantly elevated in AD patients compared with control subjects (72 ± 7 vs 46 ± 4 pg/ml) and were significantly linearly correlated with brain weight (–0.3 pg/ml/g, r² = 0.32). These results suggest that quantification of CSF F₂-IsoP concentrations may provide a useful biomarker of central nervous system oxidative damage in AD.     

Motor neurone disease with elevated cerebrospinal fluid protein.

The correlation between age and CSF protein in 38 patients with pathologically proven motor neurone disease was the reverse of that described for normal subjects by Tibbling et al in 1977. Eight had CSF protein ranging from 0.75 g/1 to 1.52 g/L. These patients were younger, but other clinical and gross and light microscopy pathological features were not significantly different from those with lower CSF protein. Transudation from serum may be only one of the mechanisms underlying this elevation in CSF protein.