Current Alzheimer Research (v.8, #8)

Anti-β -Amyloid Immunotherapy for Alzheimer's Disease: Focus on Bapineuzumab by Francesco Panza, Vincenza Frisardi, Bruno P. Imbimbo, Davide Seripa, Francesco Paris, Andrea Santamato, Grazia D'Onofrio, Giancarlo Logroscino, Alberto Pilotto, Vincenzo Solfrizzi (808-817).
Recent advances in our understanding of the neurobiology of Alzheimer's disease (AD) have led to the developmentof putative disease-modifying treatments. The most revolutionary of these approaches consists in the removal ofbrain β-amyloid (Aβ) via anti-Aβ antibodies. Brain imaging and neuropathological studies have shown the ability of bothactive and passive anti-Aβ immunotherapies of clearing Aβ deposits from the brain of the AD patients. An active anti-Aβvaccine preparation, AN1792, has been used in AD patients with some clues of clinical efficacy but causing meningoencephalitisin about 6% of patients and it has been abandoned. Several second-generation active Aβ vaccines and passiveAβ immunotherapies have been developed and are under clinical investigation with the aim of accelerating Aβ clearancefrom the brain of the AD patients. The most advanced of these immunological approaches is bapineuzumab, composed ofhumanized anti-Aβ monoclonal antibodies, that has been tested in two Phase II trials, demonstrating to reduce Aβ burdenin the brain of AD patients. However, the preliminary cognitive efficacy of bapineuzumab appears uncertain. The occurrenceof vasogenic edema, especially in apolipoprotein E β4 carriers, may limit its clinical use and have led to abandon thehighest dose of the drug (2 mg/kg). The results of four ongoing large Phase III trials on bapineuzumab will tell us if passiveanti-Aβ immunization is able to alter the course if this devastating disease.

Transgenic Mice as a Model for Alzheimer's Disease by Christina Unger Lithner, Monika M. Hedberg, Agneta Nordberg (818-831).
During the last few decades, numerous stable transgenic mouse strains have been developed in order to mimic arange of Alzheimer's disease (AD)-related pathologies. Although none of the models fully replicates the human disease,the models have been a key feature in translational research, providing significant insights into the pathophysiology ofAD. They have also been widely used in the preclinical testing of potential therapies. The choice of transgenic mousemodel, as well as the stage of Aβ pathology, significantly contributes to the outcome of the studies. Therefore, it is importantto combine studies in different transgenic mouse models and detailed in vitro experiments to obtain a complete understandingof the origin of the disease, the actual sequences of early pathological events as well as being able to evaluate theeffects of new drugs in the treatment of AD.

Intrahippocampal Amyloid-β (1-40) Injections Injure Medial Septal Neurons in Rats by Luis V. Colom, Maria T. Castaneda, Sofia Hernandez, George Perry, Saul Jaime, Ahmed Touhami (832-840).
Alzheimer's disease (AD) is a devastating disorder that leads to memory loss and dementia. Neurodegenerationof cholinergic neurons in the septum and other basal forebrain areas is evident in early stages of AD. Glutamatergic neuronsare also affected early in AD. In these stages, amyloid-β-peptide (Aβ) plaques are present in the hippocampus andother cortices but not in the basal forebrain, which includes the septum. We postulate that early deposition of hippocampalAβ damages the axon terminals of cholinergic and glutamatergic septo-hippocampal neurons, leading to their degeneration.To determine the mechanisms underlying septal degeneration, fibrillar Aβ1-40 was injected into the Cornu Ammonis(CA1) hippocampal region of rats. Controls were injected with reverse peptide Aβ40-1. A 16% reduction in NeuN+ cellswas observed around the injection sites when compared to controls (p<0.05) one week after injections. Stereology wasused to estimate the number of choline acetyl transferase (ChAT), glutamate and glutamic acid decarboxylase 67(GAD67) immunoreactive septal neurons. Medial septal ChAT and glutamate immunoreactive neurons were reduced 38%and 26%, respectively by hippocampal injections of Aβ1-40 peptide in relation to controls. In contrast, the number ofGAD67 inmunoreactive neurons was not significantly reduced. Apoptotic cells were detected in the medial septal regionof Aβ1-40 treated animals but not in controls. These results indicate that limited Aβ-induced hippocampal lesions lead toan overall damage of vulnerable septal neuronal populations, most likely by Aβ interaction with septo-hippocampal axonterminals. Thus, axon terminals constitute an important target for novel therapeutics dedicated to control Aβ-induced toxicity.

A..(1-42) Aggregates into Non-Toxic Amyloid Assemblies in the Presence of the Natural Polyphenol Oleuropein Aglycon by Stefania Rigacci, Valentina Guidotti, Monica Bucciantini, Daniela Nichino, Annalisa Relini, Andrea Berti, Massimo Stefani (841-852).
Amyloid aggregation starts with the initial misfolding of peptide/protein precursors, with subsequent structuralrearrangement into oligomers and protofibrils; the latter eventually organize into fibrils with shared basic structural features,found deposited in amyloid diseases. Mounting evidence indicates early oligomers as the most toxic amyloid species;accordingly, the search of inhibitors of their growth is considered a promising target to prevent amyloid toxicity. Werecently showed that oleuropein aglycon, a polyphenol abundant in the extra virgin olive oil, interferes with the aggregationof amylin (involved in type-2 diabetes), eliminating its cytotoxicity. Here we report that oleuropein aglycon also hindersamyloid aggregation of Aβ(1-42) and its cytotoxicity, suggesting a general effect of such polyphenol. In particular,by using a wide panel of different spectroscopic, immunologic, cell viability and imaging techniques we provide a moredetailed description of Aβ(1-42) structural modifications arising in the presence of the inhibitor and the resulting cytotoxicity.We here report that the polyphenol eliminates the appearance of early toxic oligomers favouring the formation ofstable harmless protofibrils, structurally different from the typical Aβ(1-42) fibrils. We also show that oleuropein aglyconis maximally effective when is present at the beginning of the aggregation process; furthermore, when added to preformedfibrils, it does not induce the release of toxic oligomers but, rather, neutralizes any residual toxicity possibly arisingfrom the residual presence of traces of soluble oligomers and other toxic aggregates. The possible use of this polyphenolas anti-aggregation molecule is discussed in the light of these data.

Influence of Lithium Treatment on GDNF Serum and CSF Concentrations in Patients with Early Alzheimer's Disease by Guido Straten, Ralf Saur, Christoph Laske, Thomas Gasser, Peter Annas, Hans Basun, Thomas Leyhe (853-859).
Preclinical and clinical studies gave evidence that lithium could be useful in the treatment of Alzheimer's disease(AD). One possible mechanism of action might be the induction of neurotrophins. Recently, we found a significantincrease of brain-derived neurotrophic factor (BDNF) serum levels in AD patients treated with lithium and a significantdecrease of ADAS Cog sum scores in comparison to placebo-treated patients. In another previous study we have shownthat glial cell line-derived neurotrophic factor (GDNF) levels in CSF of patients with early AD are increased most probablydue to an upregulated expression in CNS as an adaptive process of the impaired brain to enhance neurotrophic supportat least in early stages of disease. Here we assessed the influence of a lithium treatment on GDNF serum and cerebrospinalfluid (CSF) concentrations in a subset of a greater sample recruited for a randomized, single-blinded, placebocontrolled,parallel-group multicenter 10-week study, investigating the efficacy of lithium treatment in AD patients. Wefound a significant negative correlation of lithium concentration in serum with GDNF concentration in CSF at the end oftreatment (r = -0.585, p = 0.036) and with the difference of GDNF concentration in CSF before and after treatment (r = -0.755, p = 0.003). However, we could not show a difference in GDNF concentrations between the patients after the treatmentwith lithium or placebo (serum, mean ± standard deviation: 434.3 ± 117.9 pg/ml versus 543.8 ± 250.0 pg/ml, p =0.178; CSF, 62.3 ± 37.4 pg/ml versus 72.8 ± 43.9 pg/ml, p = 0.511). The findings of the present investigation indicatedthat beneficial effects of the lithium treatment might reduce the necessity of enhanced GDNF expression in the CNS inearly AD.

Evidence from our laboratory suggests that tolfenamic acid has a potential for slowing the progression of Alzheimer'sdisease (AD) through lowering cortical levels of the β-amyloid precursor protein (APP) and its pathogenic amyloidbeta (Aβ) intermediates [1]. In this study, we examined the ability of tolfenamic acid to cross the blood brain barrier(BBB) by predicting its logBB and logPS values, the indexes of BBB permeability, using computational models. We alsodetermined, via in vitro methods, the brain penetration capacity factor [(KIAM/MW4)x1010] using phosphatidylcholine columnchromatography. The obtained logBB, logPS and (KIAM/MW4)x1010 values predicted that tolfenamic acid can passivelytransfer into the central nervous system (CNS). These results were validated in vivo using LC-MS analysis afteradministration of tolfenamic acid intravenously to guinea pigs and mice. The present study provides the first evidence ofthe ability of tolfenamic acid to cross the BBB and offers a comparative analysis of approaches used to predict the abilityof compounds to penetrate into the brain.

Effects of Coenzyme Q and Creatine Supplementation on Brain Energy Metabolism in Rats Exposed to Chronic Cerebral Hypoperfusion by Jaromir Horecky, Anna Gvozdjakova, Jarmila Kucharska, Mark E. Obrenovich, Hector H. Palacios, Yi Li, Olga Vancova, Gjumrakch Aliev (868-875).
It is known that oxidative stress and mitochondrial dysfunction both play an important role in animal models ofbrain ischemia. The present study was undertaken to test whether oral supplementation of coenzyme Q10 (ubiquinone) orcreatine citrate could protect against brain ischemia-induced mitochondrial damage in the rats model. Brain ischemia wasinduced for 50 minutes with three-vessel occlusion (3-VO). Coenzyme Q10 was administered for 30 days before theischemic event and coenzyme Q10 or creatine citrate for 30 days post-ischemia. Moreover, the concentrations of coenzymeQ10 and α-, γ- tocopherols as well as the formation of thiobarbituric acid reactive substances (TBARS) were measuredin brain mitochondria and in plasma. Transient hypoperfusion revealed significant impairment in brain energy metabolismas detected by mitochondrial oxidative phosphorylation as well as decreased concentrations of brain and plasmaendogenous antioxidants and increased formation of TBARS in plasma. When compared with the ischemic group, supplementationof coenzyme Q10 was ineffective as a preventive agent. However, the positive effect of therapeutic coenzymeQ10 supplementation was supported by the oxygen consumption values (p<0.05) and ATP production (p<0.05) inbrain mitochondria, as well as by increased concentration of coenzyme Q9 (p<0.05) and concentration of α-tocopherol(p<0.05) in brain mitochondria and by increased concentration of α-tocopherol (p<0.05) and γ-tocopherol in plasma. Thissuggests that coenzyme Q10 therapy involves resistance to oxidative stress and improved brain bioenergetics, when supplementedduring reperfusion after ischemic brain injury.

Effects of the Putative Cognitive-Enhancing Ampakine, CX717, on Attention and Object Recognition Memory by Yiwen Zheng, Sangeeta Balabhadrapatruni, Chisako Masumura, Cynthia L. Darlington, Paul F. Smith (876-882).
Ampakines are a class of putative nootropic drug designed to positively modulate the AMPA receptor and havebeen investigated as a potential treatment for cognitive disorders such as Alzheimer's Disease. Nonetheless, some ampakinessuch as CX717 have been incompletely characterized in behavioural pharmacological studies. Therefore, in thisstudy, we attempted to further characterize the effects of the ampakine, CX717 (20 mg/kg s.c), on the performance of ratsin a 5 choice serial reaction time (5CSRTT) and object recognition memory task, using rats with cognitive deficits causedby bilateral vestibular deafferentation (BVD) as a model. In the 5CSRTT, when the stimulus duration was varied from 5to 2 sec, the number of incorrect responses was significantly greater for the BVD group compared to sham controls, butsignificantly less for the CX717 groups, with no significant interaction. With changes in inter-trial interval (ITI), there wasa significant effect of surgery/drug and a significant effect of ITI on premature responses, and the BVD group treated withCX717 showed significantly fewer premature responses than the other groups. In the object recognition memory task,CX717 significantly reduced total exploration time and the exploration towards the novel object in both sham and BVDanimals. These results suggest that CX717 can reduce the number of incorrect responses in both sham and BVD rats andenhance inhibitory control specifically in BVD rats, in the 5CSRTT. On the other hand, CX717 produced a detrimental effectin the object recognition memory task.

Cognitive Abilities of Alzheimer's Disease Transgenic Mice are Modulated by Social Context and Circadian Rhythm by Anna Kiryk, Gabriela Mochol, Robert K. Filipkowski, Marcin Wawrzyniak, Victoria Lioudyno, Ewelina Knapska, Tomasz Gorkiewicz, Marcin Balcerzyk, Szymon Leski, Fred Van Leuven, Hans-Peter Lipp, Daniel K. Wojcik, Leszek Kaczmarek (883-892).
In the present study, we used a new training paradigm in the intelliCage automatic behavioral assessment systemto investigate cognitive functions of the transgenic mice harboring London mutation of the human amyloid precursorprotein (APP.V717I). Three groups of animals: 5-, 12- and 18-24-month old were subjected to both Water Maze trainingand the IntelliCage-based appetitive conditioning. The spatial memory deficit was observed in all three groups of transgenicmice in both behavioral paradigms. However, the APP mice were capable to learn normally when co-housed withthe wild-type (WT) littermates, in contrast to clearly impaired learning observed when the transgenic mice were housedalone. Furthermore, in the transgenic mice kept in the Intellicage alone, the cognitive deficit of the young animals wasmodulated by the circadian rhythm, namely was prominent only during the active phase of the day. The novel approach tostudy the transgenic mice cognitive abilities presented in this paper offers new insight into cognitive dysfunctions of theAlzheimer's disease mouse model.

Left Anterior Temporal Lobe Sustains Naming in Alzheimer's Dementia and Mild Cognitive Impairment by Lars Frings, Stefan Kloppel, Stefan Teipel, Oliver Peters, Lutz Frolich, Johannes Pantel, Johannes Schroder, Hermann-Josef Gertz, Sonke Arlt, Isabella Heuser, Johannes Kornhuber, Jens Wiltfang, Wolfgang Maier, Frank Jessen, Harald Hampel, Michael Hull (893-901).
Cognitive decline in degenerative dementia is paralleled by progressive brain atrophy, with the localization ofatrophy reflecting specific cognitive impairment. Confrontation naming deficits are frequently observed in dementiaacross etiologies. In this study we aimed to identify the brain regions underlying this deficit. In patients with clinically diagnoseddementia or mild cognitive impairment (MCI) we investigated the relationship between gray matter volume(GMV) and performance on a standardized confrontation naming test. 268 patients with one of three probable etiologieswere included: Alzheimer's Dementia (AD), AD with signs of cerebrovascular pathology, and frontotemporal dementia.Applying voxel-based morphometry using a diffeomorphic registration algorithm we contrasted GMV of patients performingwithin the normal range with those of patients with pathological performance. Further, differential effects of graymatter atrophy on impaired performance in AD versus MCI of AD type were investigated. Results revealed significantlyreduced GMV in the left anterior temporal lobe (ATL) in pathological performers compared to normal performers. Thesubgroup analysis confined to MCI of AD type and AD patients confirmed this relationship. While left ATL atrophy isknown to be implicated in naming deficits in semantic dementia, our data confirm the same in AD and MCI of AD type.