Decreased interleukin-6 level in the cerebrospinal fluid of patients with Alzheimer-type dementia

A domestic strain of Lactobacillus rhamnosus attenuates cognitive deficit and pro-inflammatory cytokine expression in an animal model of Alzheimer's disease

BACKGROUND

Microbiome dysbiosis plays a significant role in neuroinflammation and Alzheimer's disease (AD). Therefore, gut microbiome restoration using appropriate probiotics may be beneficial in alleviating AD features. In this study, we investigated the effects of a domestic strain of Lactobacillus rhamnosus (L. rhamnosus) on spatial memory, and cytokines expression in an inflammation-based AD model.

METHOD

Male Wistar rats were randomly divided into four groups (six animals per group) of control, L. rhamnosus-only, D-galactose (D-gal)-only, and D-gal + L. rhamnosus. Spatial learning and memory were assessed using the Morris water maze test. IL-1β, IL-6, and TNF-α expression levels were measured using Real-Time qPCR. A significance level of 0.05 was used for statistical analysis.

RESULTS

In contrast to the D-gal + L. rhamnosus-treated group, D-gal only treated group showed impaired memory in MWM test compared to the control group. Additionally, D-gal treatment resulted in an increase in IL-1β and TNF-α levels and a decrease in IL-6 levels, which was not statistically significant. However, the TNF-α level was significantly decreased in D-gal + L. rhamnosus-treated group compared to D-gal-only treated group (P < 0.05). Also, IL-6 level was significantly lower in D-gal + L. rhamnosus-treated group compared to control group (P < 0.05).

CONCLUSION

These results suggest that the domestic L. rhamnosus might positively impact cognitive deficit and neuroinflammation. Further studies are suggested to investigate the specific mechanisms mediating the effects of L. rhamnosus on cognitive functions and neuroinflammation in animal models of AD.

Systemic inflammatory markers and their association with Alzheimer's disease: A cross-sectional analysis

Aim

To investigate the possible role of systemic inflammatory markers (interleukin; IL-6, C-reactive protein; CRP, and albumin levels) in the development of Alzheimer's dementia (AD) and also find their association with the severity of disease.

Material and Methods

It was a cross-sectional study. Patients with Alzheimer's dementia (AD) and vascular dementia (VaD) from outpatient settings in tertiary care hospitals and non-demented controls (NDC) were recruited from the community. Individuals aged 50 years and older (n = 110) were included. Serum levels of IL-6, CRP, and albumin levels in patients with AD, VaD, and NDC were measured. The clinical Dementia Rating Scale was used for staging the severity of dementia. Serum levels of IL-6, CRP, and serum albumin were compared in study subjects and also analyzed with the severity of dementia in dementia subgroups.

Results

Our main finding was that serum levels of IL-6 were significantly elevated in patients with AD and VaD (7.79 and 6.60) as compared to NDC (2.98) (P < 0.001). No significant difference in CRP or albumin levels was observed between the three groups. Serum IL-6 and CRP showed a positive correlation with the severity of AD, though the correlation was significant only for IL-6 (r = 0.777). The serum albumin levels showed a statistically significant negative correlation with the severity of AD (r > 0.3 but <0.5).

Conclusion

The study demonstrates a notable association between systemic inflammatory markers, particularly IL-6, and the severity of AD, indicating their potential role in its pathogenesis. These findings suggest that targeting these markers could offer new insights into therapeutic strategies for AD.

IL-6 Enhances the Negative Impact of Cortisol on Cognition among Community-Dwelling Older People without Dementia

There is growing evidence that high basal cortisol levels and systemic inflammation independently contribute to cognitive decline among older people without dementia. The present cross-sectional study examined (a) the potential synergistic effect of cortisol levels and systemic inflammation on executive function and (b) whether this effect is more prominent among older people with mild cognitive impairment (MCI). A sub-sample of 99 patients with MCI and 84 older people without cognitive impairment (CNI) (aged 73.8 ± 7.0 years) were recruited from a large population-based cohort in Crete, Greece, and underwent comprehensive neuropsychiatric and neuropsychological evaluation and a single morning measurement of cortisol and IL-6 plasma levels. Using moderated regression models, we found that the relation between cortisol and executive function in the total sample was moderated by IL-6 levels (b = −0.994, p = 0.044) and diagnostic group separately (b = −0.632, p < 0.001). Moreover, the interaction between cortisol and IL-6 levels was significant only among persons with MCI (b = −0.562, p < 0.001). The synergistic effect of stress hormones and systemic inflammation on cognitive status appears to be stronger among older people who already display signs of cognitive decline. Targeting hypercortisolemia and inflammation may be a promising strategy toward improving the course of cognitive decline.

The role of inflammasomes in vascular cognitive impairment

There is an increasing prevalence of Vascular Cognitive Impairment (VCI) worldwide, and several studies have suggested that Chronic Cerebral Hypoperfusion (CCH) plays a critical role in disease onset and progression. However, there is a limited understanding of the underlying pathophysiology of VCI, especially in relation to CCH. Neuroinflammation is a significant contributor in the progression of VCI as increased systemic levels of the proinflammatory cytokine interleukin-1β (IL-1β) has been extensively reported in VCI patients. Recently it has been established that CCH can activate the inflammasome signaling pathways, involving NLRP3 and AIM2 inflammasomes that critically regulate IL-1β production. Given that neuroinflammation is an early event in VCI, it is important that we understand its molecular and cellular mechanisms to enable development of disease-modifying treatments to reduce the structural brain damage and cognitive deficits that are observed clinically in the elderly. Hence, this review aims to provide a comprehensive insight into the molecular and cellular mechanisms involved in the pathogenesis of CCH-induced inflammasome signaling in VCI.

Role of mtDNA disturbances in the pathogenesis of Alzheimer's and Parkinson's disease

Neurodegenerative diseases (e.g. Alzheimer's and Parkinson's disease) are becoming increasingly problematic to healthcare systems. Therefore, their underlying mechanisms are trending topics of study in medicinal research. Numerous studies have evidenced a strong association between mitochondrial DNA disturbances (e.g. oxidative damage, mutations, and methylation shifts) and the initiation and progression of neurodegenerative diseases. Therefore, this review discusses the risk and development of neurodegenerative diseases in terms of disturbances in mitochondrial DNA and as a part of a complex ecosystem that includes other important mechanisms (e.g. neuroinflammation and the misfolding and aggregation of amyloid-β peptides, α-synuclein, and tau proteins). In addition, the influence of individual mitochondrial DNA haplogroups on the risk and development of neurodegenerative diseases is also described and discussed.

Distinct cytokine profiles in human brains resilient to Alzheimer's pathology

Our group has previously studied the brains of some unique individuals who are able to tolerate robust amounts of Alzheimer's pathological lesions (amyloid plaques and neurofibrillary tangles) without experiencing dementia while alive. These rare resilient cases do not demonstrate the patterns of neuronal/synaptic loss that are normally found in the brains of typical demented Alzheimer's patients. Moreover, they exhibit decreased astrocyte and microglial activation markers GFAP and CD68, suggesting that a suppressed neuroinflammatory response may be implicated in human brain resilience to Alzheimer's pathology. In the present work, we used a multiplexed immunoassay to profile a panel of 27 cytokines in the brains of controls, typical demented Alzheimer's cases, and two groups of resilient cases, which possessed pathology consistent with either high probability (HP, Braak stage V-VI and CERAD 2-3) or intermediate probability (IP, Braak state III-IV and CERAD 1-3) of Alzheimer's disease in the absence of dementia. We used a multivariate partial least squares regression approach to study differences in cytokine expression between resilient cases and both Alzheimer's and control cases. Our analysis identified distinct profiles of cytokines in the entorhinal cortex (one of the earliest and most severely affected brain regions in Alzheimer's disease) that are up-regulated in both HP and IP resilient cases relative to Alzheimer's and control cases. These cytokines, including IL-1β, IL-6, IL-13, and IL-4 in HP resilient cases and IL-6, IL-10, and IP-10 in IP resilient cases, delineate differential inflammatory activity in brains resilient to Alzheimer's pathology compared to Alzheimer's cases. Of note, these cytokines all have been associated with pathogen clearance and/or the resolution of inflammation. Moreover, our analysis in the superior temporal sulcus (a multimodal association cortex that consistently accumulates Alzheimer's pathology at later stages of the disease along with overt symptoms of dementia) revealed increased expression of neurotrophic factors, such as PDGF-bb and basic FGF in resilient compared to AD cases. The same region also had reduced expression of chemokines associated with microglial recruitment, including MCP-1 in HP resilient cases and MIP-1α in IP resilient cases compared to AD. Altogether, our data suggest that different patterns of cytokine expression exist in the brains of resilient and Alzheimer's cases, link these differences to reduced glial activation, increased neuronal survival and preserved cognition in resilient cases, and reveal specific cytokine targets that may prove relevant to the identification of novel mechanisms of brain resiliency to Alzheimer's pathology.

Multiplex analyte assays to characterize different dementias: brain inflammatory cytokines in poststroke and other dementias

Both the inflammatory potential and cognitive function decline during aging. The association between the repertoire of inflammatory biomarkers and cognitive decline is unclear. Inflammatory cytokines have been reported to be increased, decreased, or unchanged in the cerebrospinal fluid and sera of subjects with dementia. We assessed 112 postmortem brains from subjects diagnosed with poststroke dementia (PSD), vascular dementia, mixed dementia, and Alzheimer's disease (AD), comparing those to poststroke nondemented (PSND) subjects and age-matched controls. We analyzed 5 brain regions including the gray and white matter from the frontal and temporal lobes for a panel of cytokine and/or chemokine analytes using multiplex-array assays. Of the 37 analytes, 14 were under or near the detection limits, 7 were close to the lowest detection level, and 16 cytokines were within the linear range of the assay. We observed widely variable concentrations of C-reactive protein (CRP) and serum amyloid A at the high end (1-150 ng/mg protein), whereas several of the interleukins (IL, interferon-gamma and tumor necrosis factor) at the low end (1-10 pg/mg). There were also regional variations; most notable being high concentrations of some cytokines (e.g., CRP and angiogenesis panel) in the frontal white matter. Overall, we found decreased concentrations of several cytokines, including IL-1 beta (p = 0.000), IL-6 (p = 0.000), IL-7 (p = 0.000), IL-8 (p = 0.000), IL-16 (p = 0.001), interferon-inducible protein-10 (0.044), serum amyloid A (p = 0.011), and a trend in IL-1 alpha (p = 0.084) across all dementia groups compared to nondemented controls. IL-6 and IL-8 were significantly lower in dementia subjects than in nondemented subjects in every region. In particular, lower levels of IL-6 and IL-8 were notable in the PSD compared to PSND subjects. Because these 2 stroke groups had comparable degree of vascular pathology, the lower production of IL-6 and IL-8 in PSD reaffirms a possible specific involvement of immunosenescence in dementia pathogenesis. In contrast, CRP was not altered between dementia and nondementia subjects or between PSD and PSND. Our study provides evidence not only for the feasibility of tracking cytokines in postmortem brain tissue but also suggests differentially impaired inflammatory mechanisms underlying dementia including AD. There was a diminished inflammatory response, possibly reflecting immunosenescence and cerebral atrophy, in all dementias. Strategies to enhance anti-inflammatory cytokines and boost the immune system of the brain may be beneficial for preventing cognitive dysfunction, especially after stroke.

Cerebrospinal fluid levels of IL-6 are decreased and correlate with cognitive status in DLB patients

Introduction

Inflammatory processes have previously been shown to influence cognition and progression of dementia. An involvement of interleukin (IL)-6 has in particular been suggested as altered levels of IL-6 in cerebrospinal fluid (CSF) have been found in patients with Alzheimer’s disease (AD). Also, an association between cognitive decline and levels of IL-6 in CSF have been reported. The aim of the present study was to investigate whether patients clinically diagnosed with dementia with Lewy bodies (DLB) display altered CSF IL-6 levels in comparison with patients with AD and control subjects without dementia and whether the IL-6 levels are correlated with cognitive status and biomarkers for AD and synucleinopathy.

Methods

To analyse CSF of patients with AD (n = 45), patients with DLB (n = 29) and control subjects without dementia (n = 36), we used immunoassays to measure levels of IL-6 (multiplex electrochemiluminescence); AD markers phosphorylated tau, total tau and amyloid-β_1–42 (enzyme-linked immunosorbent assay [ELISA]); and α-synuclein (ELISA). Cognitive status was evaluated using the Mini Mental State Examination (MMSE).

Results

Our analysis showed significantly lower levels of IL-6 in CSF from patients with DLB than in CSF from patients with AD and control subjects without dementia. The IL-6 levels were also negatively correlated with MMSE and positively correlated with α-synuclein CSF levels.

Conclusions

Our findings support previous studies by demonstrating a link between inflammatory processes and dementia progression and further strengthen the hypothesis that IL-6 is involved in dementia pathology and cognitive decline.

Role of pro-inflammatory cytokines released from microglia in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder of the brain, which is characterized by the formation of extracellular amyloid plaques (or senile plaques) and intracellular neurofibrillary tangles. However, increasing evidences demonstrated that neuroinflammatory changes, including chronic microgliosis are key pathological components of AD. Microglia, the resident immune cells of the brain, is constantly survey the microenvironment under physiological conditions. In AD, deposition of β-amyliod (Aβ) peptide initiates a spectrum of cerebral neuroinflammation mediated by activating microglia. Activated microglia may play a potentially detrimental role by eliciting the expression of pro-inflammatory cytokines such as interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) influencing the surrounding brain tissue. Emerging studies have demonstrated that up-regulation of pro-inflammatory cytokines play multiple roles in both neurodegeneration and neuroprotection. Understanding the pro-inflammatory cytokines signaling pathways involved in the regulation of AD is crucial to the development of strategies for therapy. This review will discuss the mechanisms and important role of pro-inflammatory cytokines in the pathogenesis of AD, and the ongoing drug targeting pro-inflammatory cytokine for therapeutic modulation.

Cerebrospinal fluid biomarkers of neurovascular dysfunction in mild dementia and Alzheimer's disease

Alzheimer's disease (AD) is the most common form of age-related dementias. In addition to genetics, environment, and lifestyle, growing evidence supports vascular contributions to dementias including dementia because of AD. Alzheimer's disease affects multiple cell types within the neurovascular unit (NVU), including brain vascular cells (endothelial cells, pericytes, and vascular smooth muscle cells), glial cells (astrocytes and microglia), and neurons. Thus, identifying and integrating biomarkers of the NVU cell-specific responses and injury with established AD biomarkers, amyloid-β (Aβ) and tau, has a potential to contribute to better understanding of the disease process in dementias including AD. Here, we discuss the existing literature on cerebrospinal fluid biomarkers of the NVU cell-specific responses during early stages of dementia and AD. We suggest that the clinical usefulness of established AD biomarkers, Aβ and tau, could be further improved by developing an algorithm that will incorporate biomarkers of the NVU cell-specific responses and injury. Such biomarker algorithm could aid in early detection and intervention as well as identify novel treatment targets to delay disease onset, slow progression, and/or prevent AD.

Body fluid cytokine levels in mild cognitive impairment and Alzheimer's disease: a comparative overview

This article gives a comprehensive overview of cytokine and other inflammation associated protein levels in plasma, serum and cerebrospinal fluid (CSF) of patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI). We reviewed 118 research articles published between 1989 and 2013 to compare the reported levels of 66 cytokines and other proteins related to regulation and signaling in inflammation in the blood or CSF obtained from MCI and AD patients. Several cytokines are evidently regulated in (neuro-) inflammatory processes associated with neurodegenerative disorders. Others do not display changes in the blood or CSF during disease progression. However, many reports on cytokine levels in MCI or AD are controversial or inconclusive, particularly those which provide data on frequently investigated cytokines like tumor necrosis factor alpha (TNF-α) or interleukin-6 (IL-6). The levels of several cytokines are possible indicators of neuroinflammation in AD. Some of them might increase steadily during disease progression or temporarily at the time of MCI to AD conversion. Furthermore, elevated body fluid cytokine levels may correlate with an increased risk of conversion from MCI to AD. Yet, research results are conflicting. To overcome interindividual variances and to obtain a more definite description of cytokine regulation and function in neurodegeneration, a high degree of methodical standardization and patients collective characterization, together with longitudinal sampling over years is essential.

A meta-analysis of cytokines in Alzheimer's disease

BACKGROUND

Studies suggest that inflammation is involved in the neurodegenerative cascade leading to Alzheimer's disease (AD) pathology and symptoms. This study sought to quantitatively summarize the clinical cytokine data.

METHODS

Original English language peer-reviewed studies measuring cytokine concentrations in AD and healthy control subjects were included. Mean (± standard deviation) cytokine concentrations for AD and control subjects were extracted.

RESULTS

Forty studies measuring peripheral blood cytokine concentrations and 14 measuring cerebrospinal fluid (CSF) cytokine concentrations were included. In peripheral blood, there were significantly higher concentrations (weighted mean difference [95% confidence interval]) of interleukin (IL)-6 (2.86 [1.68, 4.04] pg/mL, p < .00001, N[AD/control subjects] = 985/680, 14 studies), tumor necrosis factor (TNF)-α (3.25 [.76, 5.74] pg/mL, p = .01, N = 680/447, 14 studies), IL-1β (.55 [.32, .78] pg/mL, p < .00001, N = 574/370, 10 studies), transforming growth factor (TGF)-β (67.23 [28.62, 105.83] pg/mL, p = .0006, N = 190/158, 5 studies), IL-12 (7.60 [5.58, 9.62] pg/mL, p < .00001, N = 148/106, 5 studies), and IL-18 (15.82 [1.98, 29.66] pg/mL, p = .03, N = 131/94, 4 studies) but not of IL-4, IL-8, IL-10, interferon-γ, or C-reactive protein in AD subjects compared with control subjects. There were significantly higher concentrations of TGF-β (7.81 [2.27, 13.35] pg/mL, p =.006, N = 113/114, 5 studies) but not IL-6, TNF-α, and IL-1β in the CSF of AD subjects compared with control subjects.

CONCLUSIONS

These results strengthen the clinical evidence that AD is accompanied by an inflammatory response, particularly higher peripheral concentrations of IL-6, TNF-α, IL-1β, TGF-β, IL-12 and IL-18 and higher CSF concentrations of TGF-β.

CSF Biomarkers for Alzheimer's Disease Diagnosis

Alzheimer's disease (AD) is the most common form of dementia that affects several million people worldwide. The major neuropathological hallmarks of AD are the presence of extracellular amyloid plaques that are composed of Aβ40 and Aβ42 and intracellular neurofibrillary tangles (NFT), which is composed of hyperphosphorylated protein Tau. While the amyloid plaques and NFT could define the disease progression involving neuronal loss and dysfunction, significant cognitive decline occurs before their appearance. Although significant advances in neuroimaging techniques provide the structure and physiology of brain of AD cases, the biomarker studies based on cerebrospinal fluid (CSF) and plasma represent the most direct and convenient means to study the disease progression. Biomarkers are useful in detecting the preclinical as well as symptomatic stages of AD. In this paper, we discuss the recent advancements of various biomarkers with particular emphasis on CSF biomarkers for monitoring the early development of AD before significant cognitive dysfunction.

Cerebrospinal fluid secretory Ca2+-dependent phospholipase A2 activity is increased in Alzheimer disease

BACKGROUND

The phospholipase A(2) (PLA2) family comprises multiple isoenzymes that vary in their physicochemical properties, cellular localizations, calcium sensitivities, and substrate specificities. Despite these differences, PLA2s share the ability to catalyze the synthesis of the precursors of the proinflammatory mediators. To investigate the potential of PLA2 as a biomarker in screening neuroinflammatory disorders in both clinical and research settings, we developed a PLA2 assay and determined the predominant types of PLA2 activity in cerebrospinal fluid (CSF).

METHODS

We used liposomes composed of a fluorescent probe (bis-Bodipy FL C11-PC [1,2-bis-(4,4- difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-undecanoyl)-sn-glycero-3-phosphocholine]) and 1,2-dioleoyl-l-alpha-phosphatidylcholine as a substrate to measure CSF PLA2 activity in a 96-well microtiter plate format. We established the type of CSF PLA2 activity using type-specific inhibitors of PLA2.

RESULTS

Using 5 microL CSF per assay, our PLA2 activity assay was reproducible with CVs <15% in 2 CSF samples and for recombinant secretory Ca(2+)-dependent PLA2 (sPLA2) in concentrations ranging from 0.25 to 1 micromol/L. This PLA2 assay allowed identification of sPLA2 activity in lumbar CSF from healthy individuals 20-77 years old that did not depend on either sex or age. Additionally, CSF sPLA2 activity was found to be increased (P = 0.0008) in patients with Alzheimer disease.

CONCLUSIONS

Adult human CSF has sPLA2 activity that can be measured reliably with the assay described. This enzyme activity in the CSF is independent of both sex and age and might serve as a valuable biomarker of neuroinflammation, as we demonstrated in Alzheimer disease.

Macrophage migration inhibitory factor in mild cognitive impairment and Alzheimer's disease

Inflammatory processes may substantially contribute to the cerebral pathology in Alzheimer's disease (AD) and accelerate the disease progression. The macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine which promotes the production of several inflammatory mediators such as TNF-alpha, IL-6 and IFN-gamma, and plays a central regulatory role in the pathogenesis of several inflammatory and autoimmune diseases. There is now first evidence that MIF may be involved in the neuroinflammation in AD. To determine whether MIF production is up-regulated early in the course of AD, we compared the levels of MIF assessed by ELISA in the cerebrospinal fluid (CSF) of 31 patients with AD, 28 patients with amnestic mild cognitive impairment (MCI), and 19 subjects without cognitive deficits. Additionally, we measured the CSF concentrations of the inflammatory mediators TNF-alpha, IL-6 and IFN-gamma, which are thought to be both up-regulated by MIF and involved in the pathophysiology of AD. CSF MIF concentrations were significantly increased in AD (p=0.003) and MCI patients (p<0.001) compared to controls. The levels of TNF-alpha, IL-6 and IFN-gamma did not differ significantly between the groups. There was a correlation only between the concentrations of MIF and of TNF-alpha in the AD group (r=0.407; p=0.023). These results demonstrate increased MIF production in AD and MCI suggesting that MIF may be involved in the occurring neuroinflammatory process at a clinical pre-dementia disease stage.

Cytokines in Alzheimer's disease and vascular dementia

The levels of interleukin 1beta, interleukin 6, and interleukin 10 were elevated in the serum of patients with dementia. No statistically significant correlation was recorded in the interleukin levels among patients with Alzheimer's disease and vascular dementia. Also, no significant correlation was observed in the interleukin levels in the serum and the severity of dementia. However, a significant correlation was found between IL-6 and tumor necrosis factor-alpha (TNF-alpha) levels and age. The levels of IL-1beta and IL-6 were positively correlated with hypertension, and IL-2 levels were negatively correlated. No correlation was found between depressive symptoms and levels of cytokines in the serum.

Biomarkers of Alzheimer's disease

Although a battery of neuropsychological tests is often used in making a clinical diagnosis of Alzheimer's disease (AD), definitive diagnosis still relies on pathological evaluation at autopsy. The identification of AD biomarkers may allow for a less invasive and more accurate diagnosis as well as serve as a predictor of future disease progression and treatment response. Importantly, biomarkers may also allow for the identification of individuals who are already developing the underlying pathology of AD such as plaques and tangles yet who are not yet demented, i.e. "preclinical" AD. Attempts to identify biomarkers have included fluid and imaging studies, with a number of candidate markers showing significant potential. More recently, better reagent availability and novel methods of assessment have further spurred the search for biomarkers of AD. This review will discuss promising fluid and imaging markers to date.

Zingansikpoongtang modulates beta-amyloid and IL-1beta-induced cytokine production and cyclooxygenase-2 expression in human astrocytoma cells U373MG

Zingansikpoongtang (ZST) is a Korean herbal prescription, which has been successfully applied for the various neurodegenerative diseases. However, its effect remains unknown in the experimental models. In this study, we examined the effect of ZST on production of interleukin (IL)-6 and IL-8, and expression of cyclooxygenase (COX)-2 in IL-1beta and beta-amyloid [25-35] fragment (Abeta)-stimulated human astrocytoma cell line U373MG. We examined the biological effects of ZST in U373MG cells using MTT assay, enzyme-linked immunosorbent assay, and Western blotting. ZST alone had no effect on the cell viability. The production of IL-6 and IL-8 was dose-dependently inhibited by pretreatment with ZST (0.01-1 mg/ml) on IL-1beta and Abeta-stimulated U373MG cells. The expression level of COX-2 protein was up-regulated by IL-1beta and Abeta, but the increased level of COX-2 was partially down-regulated by pretreatment with ZST (1 mg/ml). These data indicate that ZST has a modulatory effect of cytokine production and COX-2 expression on IL-1beta and Abeta-stimulated U373MG cells, which might explain its beneficial effect in the treatment of various neurodegenerative diseases.

Elevated interleukin-6 levels in cerebrospinal fluid of vascular dementia patients

OBJECTIVES

To investigate a possible implication of inflammatory processes in the development of dementia in cerebrovascular disease.

PATIENTS AND METHODS

We examined the levels of interleukin-6 (IL-6) in the cerebrospinal fluid (CSF) of patients with Alzheimer's disease (AD) (n = 26), ischemic cerebrovascular disease without dementia (CVD) (n = 11), vascular dementia (VD) (n = 11), and other neurological disorders (n = 21) using sensitive enzyme-linked immunosorbent assay.

RESULTS

The CSF concentrations of IL-6 were significantly elevated in patients with VD compared with those of patients with AD or CVD.

CONCLUSION

The CSF IL-6 levels are increased in patients with VD, suggesting that inflammatory mechanisms may be involved in the development of cognitive decline in some patients with cerebrovascular disease. CSF IL-6 may be a biological marker for dementia in cerebrovascular disease.

Interleukin-6 gene alleles affect the risk of Alzheimer's disease and levels of the cytokine in blood and brain

Two different polymorphic regions of the interleukin-6 (IL-6) gene were investigated in patients with Alzheimer's disease (AD) and non-demented controls. The -174 C allele in the promoter region of IL-6 gene was over-represented in AD patients compared to controls and significantly increased the risk of AD. Moreover, the -174 CC genotype was associated with a high risk of the disease in women. The D allele of a variable number of tandem repeat (VNTR) was in strong linkage disequilibrium with the -174 C allele and slightly increased AD risk. On the other hand, the frequency of the VNTR C allele was decreased in patients with AD and was negatively associated with the risk of developing AD. Both the -174 CC and VNTR DD genotypes were also associated with increased IL-6 levels in the blood and brain from AD. These findings suggest that IL-6 may play a multifaceted role in AD by affecting the turnover of the cytokine.

Biochemical markers related to Alzheimer's dementia in serum and cerebrospinal fluid

The diagnosis of Alzheimer's disease (AD) is currently based on clinical and neuropsychological examination. To date there is no blood test available that can discriminate dementia patients from healthy individuals. In the present paper, an overview of the current state of knowledge on biologic markers in serum (plasma) and CSF is presented. The combination of characteristic plaque markers tau and amyloid bèta may constitute a specific and sensitive CSF marker for AD. Glial fibrillary acidic protein and antibodies in CSF may be a marker for severe neurodegeneration. CSF concentrations of the oxidative stress markers 3-nitrotyrosine, 8-hydroxy-2'-deoxyguanosine and isoprostanes are increased in AD patients. Serum 24S-OH-cholesterol may be an early whereas glial fibrillary acidic protein autoantibody level may be a late marker for neurodegeneration. To date, serum alpha(1)-Antichymotripsin concentration is the most convincing marker for CNS inflammation. Increased serum homocysteine concentrations have also been consistently reported in AD. In summary, a large overlap in mean concentrations has been observed in studies comparing AD patients with healthy controls for single markers. These studies together support the theory of testing several serum markers in combination for the diagnosis of AD.

Interleukin-6 protects PC12 cells from 4-hydroxynonenal-induced cytotoxicity by increasing intracellular glutathione levels

Oxidative stress plays an important role in neuronal cell death associated with many different neurodegenerative conditions, and it is reported that 4-hydroxynonenal (HNE), an aldehydic product of membrane lipid peroxidation, is a key mediator of neuronal cell death induced by oxidative stress. Previously, we have demonstrated that interleukin-6 (IL-6) protects PC12 cells from serum deprivation and 6-hydroxydopamine-induced toxicity. Therefore, in the present study, we examined the effects of interleukins on HNE toxicity in PC12 cells. Exposure of PC12 cells to HNE resulted in a decrease in levels of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction, which was due to necrotic and apoptotic cell death. Addition of IL-6 24 h before HNE treatment provided a concentration-dependent protection against HNE toxicity, whereas neither IL-1beta nor IL-2 had any effect. Addition of glutathione (GSH)-ethyl ester, but not superoxide dismutase or catalase, before HNE treatment to the culture medium protected PC12 cells from HNE toxicity. We found that IL-6 increases intracellular GSH levels and the activity of gamma-glutamylcysteine synthetase (gamma-GCS) in PC12 cells. Buthionine sulfoximine (BSO), an inhibitor of gamma-GCS, reversed the protective effect of IL-6 against HNE toxicity. These results suggest that IL-6 protects PC12 cells from HNE-induced cytotoxicity by increasing intracellular levels of GSH.

T-helper-1 and T-helper-2 responses in psychiatric disorders

The expanding field of psychoneuroimmunology has markedly increased knowledge about the interference of the central nervous system and the immune system. Immunological abnormalities in psychiatric patients have been repeatedly described in the last century. Modern concepts of immunology and the growing knowledge of psychoneuroimmunology may help in understanding the distinct immunological mechanisms in psychiatric disorders. One of these concepts regarding the adaptive immune system is the discrimination between Th1-like cell-mediated and Th2-like antibody-related immune responses. This article systematically describes alterations of Th1- or Th2-specific parameters in the major psychiatric disorders schizophrenia, major depression, and Alzheimer's disease. There are several hints of associations of these two distinct arms of immune response with subgroups of schizophrenia and major depression. The immunological research in Alzheimer's disease has already led to a preclinical model of immunotherapy. Categorization of immune parameters may also help to identify a possible immune-related pathophysiology in psychotic and affective disorders, resulting in specific treatment strategies.

Early induction of interleukin-6 mRNA in the hippocampus and cortex of APPsw transgenic mice Tg2576

The neuropathological changes in Alzheimer's disease (AD) include the occurrence of activated microglia and astrocytes. Activated microglia expressing interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) immunoreactivity have been observed in close vicinity of the amyloid plaques in post-mortem tissue from AD patients. In order to further analyze the inflammatory process in relation to amyloidosis, we have studied the levels of markers for inflammation in the brain of Tg(HuAPP695K670N/M671L)2576 transgenic mice (Tg2576) that express high levels of human beta-amyloid precursor protein with the Swedish double mutation and develop prominent AD type neuropathology. The mRNA levels for IL-1beta, IL-1beta-converting enzyme (ICE/caspase-1) and IL-6 were analyzed by semi-quantitative reverse transcription-polymerase chain reaction in the cerebral cortex, hippocampus and cerebellum from Tg2576 and wild type (wt) mice. The levels of mRNA for IL-1beta and caspase-1 were not significantly increased in either young (4 months) or aged (18 months) Tg2576 mice as compared to the age-matched wt mice. However, we observed an increase in IL-6 mRNA levels in the hippocampus and cortex of both 4- and 18-month-old transgenic mice as compared to wt mice. The increase in IL-6 mRNA levels in Tg2576 animals thus occurs before amyloid plaques can be detected (9-10 months). This would indicate that IL-6 mRNA induction is an early event in a beta-amyloid-induced immune response cascade or that it may be involved in the amyloidosis.

Intra vitam lumbar and post mortem ventricular cerebrospinal fluid immunoreactive interleukin-6 in Alzheimer's disease patients

OBJECTIVES

In view of contradictory findings in previous studies, to examine the diagnostic value of interleukin-6 measurements in cerebrospinal fluid (CSF) of Alzheimer's disease patients.

MATERIAL AND METHODS

Interleukin-6-immunoreactivity (IL-6-IR) was measured in 169 intra vitam lumbar and 21 post mortem ventricular CSF samples of patients with probable and neuropathologically confirmed Alzheimer's disease (AD), non-AD dementias (NAD), neurological disorders without cognitive impairment (OND) and controls (CON) using a specific sandwich enzyme immunoassay.

RESULTS

Intra vitam lumbar samples had significantly elevated (P < 0.03) IL-6-IR not only in the AD, but also in the NAD and OND group compared with controls. AD patients with late onset (> 65 years) had slightly (P > 0.05) higher values than patients with early onset (< 65 years). In post mortem ventricular fluid, differences among groups did not reach significance (P > 0.05).

CONCLUSION

We conclude that elevations of CSF IL-6-IR can not serve as a diagnostic marker of the disease, but, hypothetically, could reflect presence or activity of IL-6 mediated immunological phenomena in single AD patients.

Clinical significance of neurobiochemical profiles in the lumbar cerebrospinal fluid of Alzheimer's disease patients

Immunoreactivities of total apolipoprotein E (ApoE-IR), amyloid beta peptide(1-42) (Abeta42-IR), interleukin-6 (IL-6-IR), substance P (SPIR) and total tau protein (TTIR) were measured in lumbar cerebrospinal fluid samples of patients with Alzheimer's disease (AD), non-Alzheimer's dementias (NAD), neurological disorders without cognitive impairment (OND) and controls without central nervous system disease using sensitive and specific enzyme immunoassay methods. TTIR was highly significantly increased (P < 0,001) and Abeta42-IR was significantly decreased (P < 0,001 vs. OND/CO, P < 0,03 vs. NAD) in the AD cohort compared with the other diagnostic groups. Significant increases in AD were also found for ApoE-IR (P < 0,001) and IL-6 (P < 0,03), but there was a considerable overlap between groups. In the total AD cohort, SPIR was not significantly changed, but AD patients with late disease onset (>65 years) showed significantly higher values than both early onset patients (<65 years) and controls (P < 0,05). Discriminant function analysis showed that Abeta42-IR (cut-off value 375pg/ml) and TTIR (cut-off value 440 pg/ml) levels contributed most to the group classification of patients. At 85% sensitivity for AD and 100% specificity for controls, the combined evaluation of Abeta42-IR and TTIR in this cross-sectional study resulted in a graph separating AD from non-AD patients with increased specificity of 91% and 75% for AD versus OND and NAD, respectively.

Influence of reduced nicotinamide adenine dinucleotide on the production of interleukin-6 by peripheral human blood leukocytes

OBJECTIVE

Recently, therapy with nicotinamide adenine dinucleotide (NADH) revealed positive effects on neurodegenerative disorders associated with inflammation of the CNS, such as Parkinson's disease or Alzheimer's disease. Pathophysiologically, focal CNS inflammation seems to be accompanied by an unbalanced cytokine production, pointing to an involvement of the immune system. Therefore, the aim of our study was to investigate whether NADH could influence cytokine release of peripheral blood leukocytes (PBLs) with special reference to interleukin-6 (IL-6).

METHODS

PBLs from 18 healthy donors were incubated in vitro with different concentrations of NADH to generate dose-response curves. As a control, mitogen-treated cells and unstimulated cells were included.

RESULTS

In PBLs from the 18 healthy donors, NADH significantly stimulated the dose-dependent release of IL-6, ranging from 6.25 to 400 microg/ml, compared to medium-treated cells (p < 0.001). An amount of 1,000 pg/ml IL-6 was induced by NADH concentrations ranging from 3.1 to >25 microg/ml.

CONCLUSIONS

It is concluded that NADH possesses cytokine-modulating effects on peripheral blood cells. The biological relevance of these data is discussed in the context of the recent use of NADH for the treatment of several neurodegenerative disorders.

Age-associated increased interleukin-6 gene expression, late-life diseases, and frailty

Interleukin-6 (IL-6) is a proinflammatory cytokine that is normally tightly regulated and expressed at low levels, except during infection, trauma, or other stress. Among several factors that down-regulate IL-6 gene expression are estrogen and testosterone. After menopause or andropause, IL-6 levels are elevated, even in the absence of infection, trauma, or stress. IL-6 is a potent mediator of inflammatory processes, and it has been proposed that the age-associated increase in IL-6 accounts for certain of the phenotypic changes of advanced age, particularly those that resemble chronic inflammatory disease [decreased lean body mass, osteopenia, low-grade anemia, decreased serum albumin and cholesterol, and increased inflammatory proteins such as C-reactive protein (CRP) and serum amyloid A]. Furthermore, the age-associated rise in IL-6 has been linked to lymphoproliferative disorders, multiple myeloma, osteoporosis, and Alzheimer's disease. This overview discusses the data relating IL-6 to age-associated diseases and to frailty. Like the syndrome of inappropriate antidiuretic hormone, it is possible that certain clinically important late-life changes are due to an inappropriate presence of IL-6.

Unchanged levels of interleukins, neopterin, interferon-gamma and tumor necrosis factor-alpha in cerebrospinal fluid of patients with dementia of the Alzheimer type

Several histopathological studies suggest that amyloidogenesis in dementia of the Alzheimer type is accompanied by activated glia and glia-derived cytokines, leading to chronic, self-propagating, cytokine-mediated molecular and cellular reactions. As studies regarding inflammatory changes in cerebrospinal fluid of patients with dementia of the Alzheimer type has been inconclusive, we set up a prospective study to assess cerebrospinal fluid levels of interleukin-1beta, interleukin-6, interleukin-10, interleukin-12, soluble interleukin-2 receptor, interferon-gamma, tumor necrosis factor-alpha and neopterin in 20 patients with dementia of the Alzheimer type and 20 age- and sex-matched controls. Comparing both groups, no significant differences in concentrations and specific activities could be revealed. An additional 22 patients were included to enlarge the study population. No statistically significant differences were shown comparing patients (n=42) with the control group (n=20). We conclude that the immune-mediated inflammatory changes found in histopathological studies are not reflected in cerebrospinal fluid of patients with dementia of the Alzheimer type. Probably, cytokine production appears very localized in the central nervous system, not allowing representative detection in cerebrospinal fluid. Further studies assessing cytokine levels in various regions of central nervous system of patients with dementia of the Alzheimer type will be of interest to confirm this hypothesis.

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.

Recent advances in dementia research in Japan: Alzheimer-type dementia

In a previous article, recent reports by Japanese researchers on non-Alzheimer-type degenerative dementias were reviewed. In the present article, recent Japanese reports on Alzheimer-type dementia (ATD) are reviewed. Alzheimer-type dementia has received great attention and has been studied from various viewpoints in Japan as well as in Europe and the Americas. In Japan, although it was believed that vascular dementia was the most frequent dementia in the elderly, ATD has recently been shown to be the most predominant type of dementia. Such a great number of papers on ATD have been reported in Japan that mainly the clinical, neuropathological, biochemical and molecular biological research papers alone are reviewed here.

Interleukin-6 and the soluble IL-6 receptor are decreased in cerebrospinal fluid of geriatric patients with major depression: no alteration of soluble gp130

Interleukin-6 (IL-6) is hypothesized to play an important role in the interaction between immune mechanisms and the central nervous system. We investigated whether cerebrospinal fluid (CSF) concentrations of interleukin-6 (IL-6), the soluble IL-6 receptor (sIL-6R) and the soluble form of the signal transducing and affinity converting receptor gp130 (sgp130) are altered in geriatric patients with major depression (MD). In 20 geriatric patients with MD and 20 age-matched healthy control subjects CSF concentrations of the three components of the sIL-6R complex were analyzed by enzyme-linked immunosorbent assays (ELISA). All patients except one were treated with psychotropic drugs. We found statistically significant decreased CSF concentrations of IL-6 (P<0.001) and of the sIL-6R (P<0.001) of patients with MD. Levels of sgp130 showed no statistically significant difference between patients and controls.

Importance of immunological and inflammatory processes in the pathogenesis and therapy of Alzheimer's disease

The contribution of autoimmune processes or inflammatory components in the etiology and pathogenesis of Alzheimer's disease (AD) has been suspected for many years. The presence of antigen-presenting, HLA-DR-positive and other immunoregulatory cells, components of complement, inflammatory cytokines and acute phase reactants have been established in tissue of AD neuropathology. Although these data do not confirm the immune response as a primary cause of AD, they indicate involvement of immune processes at least as a secondary or tertiary reaction to the preexisting pathogen and point out its driving-force role in AD pathogenesis. These processes may contribute to systemic immune response. Thus, experimental and clinical studies indicate impairments in both humoral and cellular immunity in an animal model of AD as well as in AD patients. On the other hand, anti-inflammatory drugs applied for the treatment of some chronic inflammatory diseases have been shown to reduce risk of AD in these patients. Therefore, it seems that anti-inflammatory drugs and other substances which can control the activity of immunocompetent cells and the level of endogenous immune response can be valuable in the treatment of AD patients.

Biological markers for the diagnosis of Alzheimer's disease

A diagnostic test for Alzheimer's disease (AD) based on biochemical markers in the cerebrospinal fluid can help improve diagnostic accuracy, which currently is approximately 90%, leaving every tenth AD patient undiagnosed or falsely diagnosed as having the disease. From all biochemical abnormalities described in AD patients, those related to the hallmark neuropathologic lesions, deposition of amyloid and formation of paired helical filaments mainly consisting of abnormally phosphorylated tau protein, are the most promising and the best documented, even though other markers bear some potential and remain to be further studied. Determining an increase of tau and a reduction of A beta 42 bears satisfactory, even though not absolute specificity for AD and represents a true aid for clinicians in diagnosing AD during the patients lifetime. It remains open if these markers will be helpful for the most challenging goal, diagnosing AD in the preclinical phase, when, according to morphological data, high amounts of these pathological proteins are already deposited in the brain tissue.

Serum interleukin-6 and interleukin-6 soluble receptor in Alzheimer's disease

Serum levels of interleukin-6 (IL-6) and interleukin-6 soluble receptor (IL-6sR) were measured in 41 patients (23 female and 18 male, mean age 72.5 years) with Alzheimer's disease (AD) and in 32 controls (14 women and 18 men, mean age 69.2 years) using enzyme-linked immunosorbent assays (ELISA). Proportions of individuals with detectable serum IL-6 concentrations did not differ significantly between patients and controls. There was however, a significant decrease in IL-6sR levels in Alzheimer's patients when compared with controls. Our results suggest that there is a dysregulation of IL-6 and its soluble receptor in AD.

Interleukin-6 (IL-6) and soluble forms of IL-6 receptors are not altered in cerebrospinal fluid of Alzheimer's disease patients

We quantitated interleukin-6 (IL-6), soluble IL-6 receptor (sIL-6R) and soluble form of the IL-6 signal-transducing protein gp130 (sgp130) in cerebrospinal fluid (CSF) of patients with Alzheimer's disease (AD) (n = 17) and control subjects (n = 18) using sensitive enzyme-linked immunosorbent assays (ELISA). Our results show that none of the parameters examined was significantly different in CSF of AD patients as compared to control age-matched non-demented patients. We conclude that CSF levels of IL-6 and their soluble receptors do not necessarily reflect local changes of the IL-6 system that has been shown to be involved in neurodegenerative events occurring in AD. Levels of sgp130 are substantially high (approximately 100 ng/ml) in the CSF of all individuals probably representing a high antagonistic potential.

Physiological and pathological roles of interleukin-6 in the central nervous system

The cytokine interleukin-6 (IL-6) is an important mediator of inflammatory and immune responses in the periphery. IL-6 is produced in the periphery and acts systemically to induce growth and differentiation of cells in the immune and hematopoietic systems and to induce and coordinate the different elements of the acute-phase response. In addition to these peripheral actions, recent studies indicate that IL-6 is also produced within the central nervous system (CNS) and may play an important role in a variety of CNS functions such as cell-to-cell signaling, coordination of neuroimmune responses, protection of neurons from insult, as well as neuronal differentiation, growth and survival. IL-6 may also contribute to the etiology of neuropathological disorders. Elevated levels of IL-6 in the CNS are found in several neurological disorders including AIDS dementia complex, Alzheimer's disease, multiple sclerosis, systemic lupus erythematosus, CNS trauma, and viral and bacterial meningitis. Moreover, several studies have shown that chronic overexpression of IL-6 in transgenic mice can lead to significant neuroanatomical and neurophysiological changes in the CNS similar to that commonly observed in various neurological diseases. Thus, it appears that IL-6 may play a role in both physiological and pathophysiological processes in the CNS.

Serum interleukin-6 levels correlate with the severity of dementia in Down syndrome and in Alzheimer's disease

INTRODUCTION

Inflammatory processes are suspected in the pathomechanism of Alzheimer's dementia (AD) but the serum and cerebrospinal fluid (CSF) levels of inflammatory cytokines are not yet determined in the different forms of the disorder.

SUBJECTS AND METHODS

Interleukin-6 (IL-6) levels were examined in the sera and CSF of patients with mild-moderate and severe stage of late onset sporadic type of AD and in the sera of demented Down syndrome (DS) probands with similar stages of AD and compared with data of age-matched healthy controls.

RESULTS

Normal serum IL-6 levels were found in the mild-moderate stage, but significantly increased levels were found in the severe stage of both dementia groups. The CSF concentrations remained within the normal range in all groups. Positive correlations between the serum IL-6 levels and age and the severity of the disease were present.

CONCLUSION

These findings suggest a disease stage dependent general activation of the immune system both in sporadic AD and in DS with AD.

Interleukin-6 is not altered in cerebrospinal fluid of first-degree relatives and patients with Alzheimer's disease

We investigated interleukin-6 (IL-6) levels in cerebrospinal fluid (CSF) of 25 patients with clinically diagnosed sporadic Alzheimer's disease (AD) and 19 healthy control subjects (HC). For comparison 19 clinically healthy subjects with at least one first-degree relative with clinical or autopsy confirmed AD (CF/AD) were examined. CSF levels of IL-6 did not show statistically significant differences between AD patients, CF/AD and HC subjects. There was no correlation between age, gender, age of onset, degree of cognitive impairment, blood-brain barrier dysfunction and IL-6 values. We could not demonstrate altered CSF concentrations of IL-6 that may indicate an inflammatory response or capability to support neuronal survival in the central nervous system (CNS) of first-degree relatives and patients with AD. We suggest that combined measurement of all parameters of the IL-6-receptor complex could yield more insight in a probably altered IL-6 function.

Possible involvement of catalase in the protective effect of interleukin-6 against 6-hydroxydopamine toxicity in PC12 cells

We examined the effects of various neurotrophic factors and cytokines on 6-hydroxydopamine (6-OHDA)-induced toxicity in PC12 cells. Exposure of PC12 cells to 6-OHDA resulted in a concentration- and time-dependent cell death, as evidenced by the release of lactate dehydrogenase into the culture medium. Addition of catalase, but not superoxide dismutase, to the culture medium protected PC12 cells from the 6-OHDA-induced toxicity. Interleukin (IL)-6 provided a dose-dependent protection against the 6-OHDA toxicity, as did nerve growth factor (NGF). In addition, basic fibroblast growth factor and dibutyryl cyclic AMP partially protected PC12 cells from 6-OHDA toxicity. Neither IL-1alpha, IL-2, IL-4, transforming growth factor-beta, nor leukemia inhibitory factor had any effect. The protective effect of IL-6 was attenuated by 3-amino-1,2,4-triazole, an inhibitor of catalase. These results suggest that IL-6 may protect PC12 cells against the 6-OHDA toxicity by activating free radical detoxifying mechanisms, such as catalase activity.

Biological markers for the clinical diagnosis of Alzheimer's disease

There is a compelling need to develop biological marker(s) to confirm a clinical diagnosis of Alzheimer's disease (AD) during life in order to unequivocally identify AD patients for emerging therapeutic interventions. This review describes recent advances in the development of diagnostic marker(s) for AD. They include polymorphism of apolipoprotein E (ApoE) and alpha 1-antichymotrypsin as well as cerebrospinal fluid (CSF) tau and CSF-amyloid beta-protein levels, skin biopsy, and pupil dilatation assay by anti-cholinergic agent. In conclusion, ApoE genotyping should not be used as a sole diagnostic test for AD, and that monitoring of CSF-tau appeared to be most promising and reliable diagnostic aid.

Changes in ciliary neurotrophic factor content in the rat brain after continuous intracerebroventricular infusion of beta-amyloid(1-40) protein

We have previously shown that the continuous intracerebroventricular infusion of beta-amyloid(1-40) protein results in memory impairments in rats, associated with a reduction of choline acetyltransferase activity in the frontal cortex and hippocampus. In the present study, we examined whether the infusion of beta-amyloid(1-40) protein affected the content of ciliary neurotrophic factor (CNTF) in the rat brain. The beta-amyloid(1-40) infusion increased CNTF content in the frontal cortex, hippocampus, and the cerebellum, but decreased its content in the brain stem. These results suggest that accumulation of beta-amyloid(1-40) in the brain may affect CNTF production in vivo.