Malgorzata Mamcarz

Protection against cognitive deficits and markers of neurodegeneration by long-term oral administration of melatonin in a transgenic model of Alzheimer disease.

Abstract:  The neurohormone melatonin has been reported to exert anti‐β‐amyloid aggregation, antioxidant, and anti‐inflammatory actions in various in vitro and animal models. To comprehensively determine the potential for long‐term melatonin treatment to protect Alzheimer’s transgenic mice against cognitive impairment and development of β‐amyloid (Aβ) neuropathology, we administered melatonin (100 mg/L drinking water) to APP + PS1 double transgenic (Tg) mice from 2–2.5 months of age to their killing at age 7.5 months. A comprehensive behavioral battery administered during the final 6 weeks of treatment revealed that Tg mice given melatonin were protected from cognitive impairment in a variety of tasks of working memory, spatial reference learning/memory, and basic mnemonic function; Tg control mice remained impaired in all of these cognitive tasks/domains. Immunoreactive Aβ deposition was significantly reduced in hippocampus (43%) and entorhinal cortex (37%) of melatonin‐treated Tg mice. Although soluble and oligomeric forms of Aβ1‐40 and 1‐42 were unchanged in the hippocampus and cortex of the same melatonin‐treated Tg mice, their plasma Aβ levels were elevated. These Aβ results, together with our concurrent demonstration that melatonin suppresses Aβ aggregation in brain homogenates, are consistent with a melatonin‐facilitated removal of Aβ from the brain. Inflammatory cytokines such as tumor necrosis factor (TNF)‐α were decreased in hippocampus (but not plasma) of Tg+ melatonin mice. Finally, the cortical mRNA expression of three antioxidant enzymes (SOD‐1, glutathione peroxidase, and catalase) was significantly reduced to non‐Tg levels by long‐term melatonin treatment in Tg mice. Thus, melatonin’s cognitive benefits could involve its anti‐Aβ aggregation, anti‐inflammatory, and/or antioxidant properties. Our findings provide support for long‐term melatonin therapy as a primary or complementary strategy for abating the progression of Alzheimer disease.

Electromagnetic Field Treatment Protects Against and Reverses Cognitive Impairment in Alzheimer's Disease Mice

Despite numerous studies, there is no definitive evidence that high-frequency electromagnetic field (EMF) exposure is a risk to human health. To the contrary, this report presents the first evidence that long-term EMF exposure directly associated with cell phone use (918 MHz; 0.25 w/kg) provides cognitive benefits. Both cognitive-protective and cognitive-enhancing effects of EMF exposure were discovered for both normal mice and transgenic mice destined to develop Alzheimers-like cognitive impairment. The cognitive interference task utilized in this study was designed from, and measure-for-measure analogous to, a human cognitive interference task. In Alzheimers disease mice, long-term EMF exposure reduced brain amyloid-beta (Abeta) deposition through Abeta anti-aggregation actions and increased brain temperature during exposure periods. Several inter-related mechanisms of EMF action are proposed, including increased Abeta clearance from the brains of Alzheimers disease mice, increased neuronal activity, and increased cerebral blood flow. Although caution should be taken in extrapolating these mouse studies to humans, we conclude that EMF exposure may represent a non-invasive, non-pharmacologic therapeutic against Alzheimers disease and an effective memory-enhancing approach in general.

Mitochondrial Amyloid-β Levels are Associated with the Extent of Mitochondrial Dysfunction in Different Brain Regions and the Degree of Cognitive Impairment in Alzheimer's Transgenic Mice

Mitochondrial dysfunction is observed in Alzheimers disease (AD) brain, and the amyloid-beta (Abeta) peptide is known to induce mitochondrial dysfunction. The relative degree of mitochondrial dysfunction in different regions of the brain in AD is not completely understood. Moreover, the relationship between levels of synaptic mitochondrial Abeta and mitochondrial dysfunction has not been clearly established. Therefore synaptic and nonsynaptic mitochondria were isolated from the hippocampus, cortex, striatum, and amygdala of 12 month AbetaPPsw and AbetaPP+PS1 mouse models of AD as well as nontransgenic mice. Mitochondrial respiratory rates, reactive oxygen species production, membrane potential, and cytochrome c oxidase activity were measured. Hippocampal and cortical mitochondria showed the highest levels of mitochondrial dysfunction, while striatal mitochondria were moderately affected, and amygdalar mitochondria were minimally affected. Mitochondria from AbetaPP/PS1 brain regions were more impaired than those from AbetaPP mice. Mitochondrial Abeta levels nearly mirrored the extent of mitochondrial dysfunction. Synaptic mitochondria were more impaired than nonsynaptic mitochondria in the AD mouse models. The AbetaPP/PS1 mice showed more impairment in the cognitive interference task of working memory than the AbetaPP mice. The association between mitochondrial Abeta levels and mitochondrial dysfunction in mouse models of AD supports a primary role for mitochondrial Abeta in AD pathology. Moreover, the degree of cognitive impairment in AD transgenic mice can be linked to the extent of synaptic mitochondrial dysfunction and mitochondrial Abeta levels, suggesting that a mitochondrial Abeta-induced signaling cascade may contribute to cognitive impairment. Therapeutics that target this cascade could be beneficial in the treatment of AD.

Caffeine Suppresses Amyloid-β Levels in Plasma and Brain of Alzheimer's Disease Transgenic Mice

Recent epidemiologic studies suggest that caffeine may be protective against Alzheimers disease (AD). Supportive of this premise, our previous studies have shown that moderate caffeine administration protects/restores cognitive function and suppresses brain amyloid-beta (Abeta) production in AD transgenic mice. In the present study, we report that acute caffeine administration to both young adult and aged AD transgenic mice rapidly reduces Abeta levels in both brain interstitial fluid and plasma without affecting Abeta elimination. Long-term oral caffeine treatment to aged AD mice provided not only sustained reductions in plasma Abeta, but also decreases in both soluble and deposited Abeta in hippocampus and cortex. Irrespective of caffeine treatment, plasma Abeta levels did not correlate with brain Abeta levels or with cognitive performance in individual aged AD mice. Although higher plasma caffeine levels were strongly associated with lower plasma Abeta1-40 levels in aged AD mice, plasma caffeine levels were also not linked to cognitive performance. Plasma caffeine and theophylline levels were tightly correlated, both being associated with reduced inflammatory cytokine levels in hippocampus. Our conclusion is two-fold: first, that both plasma and brain Abeta levels are reduced by acute or chronic caffeine administration in several AD transgenic lines and ages, indicating a therapeutic value of caffeine against AD; and second, that plasma Abeta levels are not an accurate index of brain Abeta levels/deposition or cognitive performance in aged AD mice.

Aβ-specific Th2 cells provide cognitive and pathological benefits to Alzheimer's mice without infiltrating the CNS

We have found that a small number of purified Th2-biased Abeta-specific T cells are sufficient to provide profound cognitive and pathological benefits in an APP+PS1 mouse model for Alzheimers disease. Six weeks after receiving T cell infusions, cognitively-impaired mice performed significantly better in working memory tasks, which correlated with higher plasma levels of soluble Abeta. Pathological analysis of the hippocampus revealed a 30% decrease of plaque-associated microglia and less vascular amyloidosis in T cell treated mice. The infusion of Abeta-specific Th2 cells also reduced plasma levels of IFN-gamma, TNF-alpha, GM-CSF, IL-2 and IL-4, which are elevated in untreated APP+PS1 mice. No significant immune cell infiltration and no anti-Abeta antibody titers occurred in the T cell treated mice. These results demonstrate that Abeta-specific Th2 cells are sufficient to reverse cognitive impairment and provide multiple pathological benefits in an Alzheimers mouse model.

LONG-TERM ELECTROMAGNETIC FIELD TREATMENT ENHANCES BRAIN MITOCHONDRIAL FUNCTION OF BOTH ALZHEIMER'S TRANSGENIC MICE AND NORMAL MICE: A MECHANISM FOR ELECTROMAGNETIC FIELD-INDUCED COGNITIVE BENEFIT?

We have recently reported that long-term exposure to high frequency electromagnetic field (EMF) treatment not only prevents or reverses cognitive impairment in Alzheimers transgenic (Tg) mice, but also improves memory in normal mice. To elucidate the possible mechanism(s) for these EMF-induced cognitive benefits, brain mitochondrial function was evaluated in aged Tg mice and non-transgenic (NT) littermates following 1 month of daily EMF exposure. In Tg mice, EMF treatment enhanced brain mitochondrial function by 50-150% across six established measures, being greatest in cognitively-important brain areas (e.g. cerebral cortex and hippocampus). EMF treatment also increased brain mitochondrial function in normal aged mice, although the enhancement was not as robust and less widespread compared to that of Tg mice. The EMF-induced enhancement of brain mitochondrial function in Tg mice was accompanied by 5-10 fold increases in soluble Aβ1-40 within the same mitochondrial preparations. These increases in mitochondrial soluble amyloid-β peptide (Aβ) were apparently due to the ability of EMF treatment to disaggregate Aβ oligomers, which are believed to be the form of Aβ causative to mitochondrial dysfunction in Alzheimers disease (AD). Finally, the EMF-induced mitochondrial enhancement in both Tg and normal mice occurred through non-thermal effects because brain temperatures were either stable or decreased during/after EMF treatment. These results collectively suggest that brain mitochondrial enhancement may be a primary mechanism through which EMF treatment provides cognitive benefit to both Tg and NT mice. Especially in the context that mitochondrial dysfunction is an early and prominent characteristic of Alzheimers pathogenesis, EMF treatment could have profound value in the diseases prevention and treatment through intervention at the mitochondrial level.

Caffeine Synergizes with Another Coffee Component to Increase Plasma GCSF: Linkage to Cognitive Benefits in Alzheimer's Mice

Retrospective and prospective epidemiologic studies suggest that enhanced coffee/caffeine intake during aging reduces risk of Alzheimers disease (AD). Underscoring this premise, our studies in AD transgenic mice show that long-term caffeine administration protects against cognitive impairment and reduces brain amyloid-β levels/deposition through suppression of both β- and γ-secretase. Because coffee contains many constituents in addition to caffeine that may provide cognitive benefits against AD, we examined effects of caffeinated and decaffeinated coffee on plasma cytokines, comparing their effects to caffeine alone. In both AβPPsw+PS1 transgenic mice and non-transgenic littermates, acute i.p. treatment with caffeinated coffee greatly and specifically increased plasma levels of granulocyte-colony stimulating factor (GCSF), IL-10, and IL-6. Neither caffeine solution alone (which provided high plasma caffeine levels) or decaffeinated coffee provided this effect, indicating that caffeine synergized with some as yet unidentified component of coffee to selectively elevate these three plasma cytokines. The increase in GCSF is particularly important because long-term treatment with coffee (but not decaffeinated coffee) enhanced working memory in a fashion that was associated only with increased plasma GCSF levels among all cytokines. Since we have previously reported that long-term GCSF treatment enhances cognitive performance in AD mice through three possible mechanisms (e.g., recruitment of microglia from bone marrow, synaptogenesis, and neurogenesis), the same mechanisms could be complimentary to caffeines established ability to suppress Aβ production. We conclude that coffee may be the best source of caffeine to protect against AD because of a component in coffee that synergizes with caffeine to enhance plasma GCSF levels, resulting in multiple therapeutic actions against AD.

O1-01-01

Gary W. Arendash, Kavon Rezai-Zadeh, Chuanhai Cao, Malgorzata Mamcarz, Alexander Dickson, William Schleif, Melissa Runfeldt, Xiaoyang Lin, Jennifer Cracchiolo, Daniel Shippy, Ashok Raj, Jun Tan, Huntington Potter, The Byrd Alzheimer’s Institute, Tampa, FL, USA; Dept. of Psychiatry and Behavioral Medicine, University of South Florida College of Medicine, Tampa, FL, USA; Memory and Aging Research Laboratory, University of South Florida, Tampa, FL, USA. Contact e-mail: Gary.Arendash@byrdinstitute.org

O3-05-08: Amyloid-β-responsive Th2 cells reduce microglial activation, reduce serum cytokines, increase plasma amyloid-β, and improve hippocampal-dependent memory in APP+PS1 mice

-amyloid peptide species A 3(pE)-40/42 play a major role in Alzheimer’s disease. Formation of pyroglutamic acid (pGlu) requires cyclization of an N-terminal glutamate residue rendering the modified peptide uncharged, and thus hydrophobic and degradation resistant. Therefore, A 3(pE)-42 exerts a high tendency of aggregation and its occurrence correlates with dementia in AD patients and neuron loss in animal models. Pyroglutamated -amyloid peptides have been identified in plaques of sporadic AD, down syndrome patients in the late 80ies. However, only recently it became evident, that plaques of brains of nondemented elderly mainly consists of full length A 1-40/42 while plaques of AD patients primarily consist of A 3(pE)-42. Visualizing plaque pathology in diverse model animals using PIB also strongly correlate to the AD symptomatic severity of the particular mouse model and to A 3(pE)-42, but not to A 1-40/42,. Additionally, it has been shown in vitro, that A 3(pE)-42 aggregates more than 200fold faster than A 1-40/42.. Moreover, the peptide unfolds profound seeding capacity. However, molecular mechanisms leading to the A 3(pE)-42 species were suspected to occur spontaneously. We discovered that Glutaminyl Cyclase (QC) is co-localized with APP and unfolds a glutamyl cyclization activity in the secretory pathway. Methods: In vitro, in situ and in vivo, QC converts N3Glu-A to the appropriate pGlu-A species. Using newly generated transgenic mice we could dissect the specific toxicity of A 3(pE)-42 resulting in animals developing a dramatic neurodegenerative pathology already within 2 months of age. Several studies applying QCinhibitors have been conducted with mice of two different genetic AD backgrounds. Results: Oral treatment of the transgenic mice and of newly generated transgenic Drosophila flies with QC inhibitors led, in four different studies to significant reduction of A 3(pE)-42 and obviously causally related of total A 1-40/42 and of the plaque burden in the mice. We also found in prevention studies (up to 10 month, startings at age of 4 months), reduction of neuroinflammatory markers as well as memory enhancement during fear conditioning and Morris water maze tests. Conclusions: The inhibition of Glutam(in)yl Cyclase in vivo can be considered as a potentially causative new treatment of neurodegeneration in AD.

IC-P3-174: Plasma Aβ level can be used as marker for AD treatment in PS1/APP Alzheimer's mouse model

(23.5 2.9 yrs.) were recruited and dichotomized into groups based upon e4 allele carrier status. During functional magnetic resonance imaging (fMRI), participants performed a simple object identification and categorization task and 24-hours later were given a surprise recognition test to evaluate their incidental encoding and recollection of the previously presented stimuli. Sustained (block) and phasic (event-related) fMRI signal characteristics associated with simple object categorization and successful incidental episodic memory encoding (i.e., subsequent recognition memory hits vs. misses) were evaluated using a hybrid model methodology. Structural differences in MTL grey matter were interrogated using voxel-based morphometry (VBM). Results: Despite the lack of differences in fMRI categorization task or subsequent memory performances, group-wise comparisons of the fMRI data revealed significant differences in both transient and sustained neural activity within the MTL as a function off APOE e4 allele carrier status. Both groups exhibited successful encoding-related activity in the MTL, though compared to non-carriers, e4 carriers exhibited significantly greater activity in bilateral hippocampus and parahippocampal gyri. Non-carriers exhibited greater sustained MTL activity (right anterior parahippocampal cortex) compared to e4 carriers. Grey matter tissue density differences were observed in bilateral rhinal and right parahippocampus, but these regions did not share spatial overlap with the significant fMRI loci.