Active vaccination with ankyrin G reduces ß-amyloid pathology in APP transgenic mice.

Serum antibodies against amyloid-ß peptide (Aß) in humans with or without diagnosis of Alzheimer's disease (AD) indicate the possibility of immune responses against brain antigens. In an unbiased screening for antibodies directed against brain proteins, we found in AD patients high serum levels of antibodies against the neuronal cytoskeletal protein ankyrin G (ankG); these correlated with slower rates of cognitive decline. Neuronal expression of ankG was higher in AD brains than in nondemented age-matched healthy control subjects. AnkG was present in exosomal vesicles, and it accumulated in ß-amyloid plaques. Active immunization with ankG of arcAß transgenic mice reduced brain ß-amyloid pathology and increased brain levels of soluble Aß(42). AnkG immunization induced a reduction in ß-amyloid pathology, also in Swedish transgenic mice(.) Anti-ankG monoclonal antibodies reduced Aß-induced loss of dendritic spines in hippocampal ArcAß organotypic cultures. Together, these data established a role for ankG in the human adaptive immune response against resident brain proteins, and they show that ankG immunization reduces brain ß-amyloid and its related neuropathology.

Early accumulation of intracellular fibrillar oligomers and late congophilic amyloid angiopathy in mice expressing the Osaka intra-Aß APP mutation.

Pathogenic amyloid-ß peptide precursor (APP) mutations clustered around position 693 of APP-position 22 of the Aß sequence--are commonly associated with congophilic amyloid angiopathy (CAA) and intracerebral hemorrhages. In contrast, the Osaka (E693Δ) intra-Aß APP mutation shows a recessive pattern of inheritance that leads to AD-like dementia despite low brain amyloid on in vivo positron emission tomography imaging. Here, we investigated the effects of the Osaka APP mutation on Aß accumulation and deposition in vivo using a newly generated APP transgenic mouse model (E22ΔAß) expressing the Osaka mutation together with the Swedish (K670N/M671L) double mutation. E22ΔAß mice exhibited reduced α-processing of APP and early accumulation of intraneuronal fibrillar Aß oligomers associated with cognitive deficits. In line with our in vitro findings that recombinant E22Δ-mutated Aß peptides form amyloid fibrils, aged E22ΔAß mice showed extracellular CAA deposits in leptomeningeal cerebellar and cortical vessels. In vitro results from thioflavin T aggregation assays with recombinant Aß peptides revealed a yet unknown antiamyloidogenic property of the E693Δ mutation in the heterozygous state and an inhibitory effect of E22Δ Aß42 on E22Δ Aß40 fibrillogenesis. Moreover, E22Δ Aß42 showed a unique aggregation kinetics lacking exponential fibril growth and poor seeding effects on wild-type Aß aggregation. These results provide a possible explanation for the recessive trait of inheritance of the Osaka APP mutation and the apparent lack of amyloid deposition in E693Δ mutation carriers.

Evidence for a cytokine model of cognitive function.

Aiming at a formulation of a cytokine model of cognitive function under immunologically unchallenged physiological conditions, this article reviews the cytokine biology in the central nervous system (CNS) and recent developments in normal cytokine functions within the CNS that subserve cognitive processes. Currently available evidence shows that the cytokines IL-1beta, IL-6 and TNF-alpha play a role in complex cognitive processes at the molecular level, such as synaptic plasticity, neurogenesis, as well as neuromodulation. Such findings provide evidence for a cytokine model of cognitive function, which shows that cytokines play an intimate role in the molecular and cellular mechanisms subserving learning, memory and cognition under physiological conditions. These cytokine-mediated cognitive processes have implications in the long-term development and pathogenesis of specific neuropsychiatric disorders such as major depression and dementia. The identification of this central role of cytokines in various brain activities during health provides greater insight into normal brain functions, especially synaptic plasticity, memory and cognition, and facilitates the understanding of specific biological mechanisms involved in neuropsychiatric diseases, such as dementia and depression. In order to extend the suggested cytokine model of cognitive function onto other members of the cytokine family, future research is required to investigate the physiological effects of other cytokines such as interferon-gamma (IFNgamma), alpha(1)-antichymotrypsin and IL-2 on cognitive function at the molecular level under immunologically unchallenged conditions.

The effects of TNF deficiency on age-related cognitive performance.

Growing evidence suggests that 'pro-inflammatory' cytokines such as TNF play a role in cognitive processes and in aging. To test the effects of TNF on cognitive function throughout aging, we used transgenic mice which were TNF deficient. We then tested these mice along with wild-type mice, at 3, 6 and 12 months of age, using the Barnes maze. Wild-type controls showed better memory than TNF knock-out mice at 3 months of age, but not at 6 and 12 months of age. Results of our experiment show that endogenous TNF plays an important role in cognitive processes throughout aging processes. The implications of these findings are far-reaching and include a possible role for cytokines in the molecular and cellular mechanisms subserving age-related changes in learning, memory and cognition.

Exploring visual-spatial working memory: a critical review of concepts and models.

The ability to retain and process an object's identity and spatial location is essential for many daily tasks, often referred to as visual-spatial working memory. Research investigating visual-spatial processing has concentrated on three aspects or mechanisms thought to sub-serve this process; perceptual processes, anatomical correlates and working memory functions. An approach integrating all three areas has largely been neglected. Hence, this review sought to (1) outline some of the advances made to the understanding by these three concepts or models of visual-spatial processing, (2) establish the relationship between these processes, and discuss the challenges faced by researchers attempting to dissociate this functions from other visual-spatial processes as well as other working memory functions. It is suggested that a more comprehensive and integrative understanding of visual-spatial working memory has implications for research seeking to investigate visual-spatial memory, and to relate visual-spatial memory to other cognitive functions, such as executive function and attention.

Alpha-lipoic acid as a new treatment option for Alzheimer's disease--a 48 months follow-up analysis.

Oxidative stress and neuronal energy depletion are characteristic biochemical hallmarks of Alzheimer's disease (AD). It is therefore conceivable that pro-energetic and antioxidant drugs such as alpha-lipoic acid might delay the onset or slow down the progression of the disease. In a previous study, 600mg alpha-lipoic acid was given daily to nine patients with AD (receiving a standard treatment with choline-esterase inhibitors) in an open-label study over an observation period of 12 months. The treatment led to a stabilization of cognitive functions in the study group, demonstrated by constant scores in two neuropsychological tests (the mini mental state exam, MMSE and the Alzheimer's disease assessment score cognitive subscale, ADAScog). In this report, we have extended the analysis to 43 patients over an observation period of up to 48 months. In patients with mild dementia (ADAScog < 15), the disease progressed extremely slowly (ADAScog: +1.2 points/year, MMSE: -0.6 points/year), in patients with moderate dementia at approximately twice the rate. However, the progression appears dramatically lower than data reported for untreated patients or patients on choline-esterase inhibitors in the second year of long-term studies. Despite the fact that this study was not double-blinded, placebo-controlled and randomized, our data suggest that treatment with alpha-lipoic acid might be a successful 'neuroprotective' therapy option for AD. However, a state-of-the-art phase II trial is needed urgently.