P2-299: Oral administration of an apolipoprotein A-I–mimetic peptide improves cognitive function and reduces amyloid burden in a mouse model of Alzheimer disease

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Poster Presentations P2:

vaccinated animals, promote more rapid and potent anti-A␤ antibody production when boosted once with dual vaccine. In other words, we are investigating the role of pre-existing anti-viral memory Th cells in rapid and efficient generation of anti-A␤ antibody responses in APP/Tg mice. As we suggested, these experiments could simulate the situation in people with early pre-clinical stage AD repeatedly vaccinated/infected with flu virus. Conclusions: Importantly, if successful, dual-vaccine can be used in people with AD at a very early stage that can be diagnosed by measuring tau/A␤ and ptau/A␤ ratio in CSF and/or by screening for accumulation of A␤ in the brains using PIB-PET scan. P2-299

ORAL ADMINISTRATION OF AN APOLIPOPROTEIN A-I–MIMETIC PEPTIDE IMPROVES COGNITIVE FUNCTION AND REDUCES AMYLOID BURDEN IN A MOUSE MODEL OF ALZHEIMER DISEASE

Shaila P. Handattu, David W. Garber, Candyce E. Monroe, Thomas van Groen, Inga Kadisha, Palgunachari Mayakonda, Ling Li, G.M. Anantharamaiah, UAB, Birmingham, AL, USA. Contact e-mail: [email protected] Background: Recent evidences indicate that inflammatory mechanisms represent a component that may significantly contribute to the progression of Alzheimer’s disease (AD). Apo A-I mimetic peptide D-4F has been shown to inhibit atherosclerotic lesion formation and in presence of statin, even regresses already existing lesion. Oral administration of D-4F has also been shown to improve cognitive function and decreases brain arteriole inflammation in LDL receptor null mice on Western diet. Since this peptide is in phase II clinical trials for atheroscerosis prevention, we undertook a study to evaluate the efficacy of oral D-4F in presence of pravastatin on the improvement of cognitive performance and inhibition of amyloid ␤ plaque burden in a mouse model of AD. Methods: 3 groups of 4 month old male APPswe-PS1⌬E9 Tg mice were used. The first group received D-4F (200␮g/ml) ⫹ pravastatin (10␮g/ml) in drinking water. The second group received a control peptide scrambled D-4F (Sc-D-4F, 200␮g/ml) and pravastatin (10␮g/ml) and the third group did not receive any drugs. After 3 months of treatment the mice were tested for their ability for spatial learning and retention using Morris Water Maze test. Amyloid burden occupied in the hippocampi was analysed by immunohistochemistry and inflammatory markers in the brain were measured by ELISA. Results: Mice treated with D-4F ⫹statin for 3 months showed a significant improvement in their spatial memory and retention (p⬍ 0.01) compared to the other two groups. In control and Sc-D-4F⫹statin treated mice the hippocampus area occupied by amyloid plaque was 4.2⫾0.5% and 3.8⫾0.6% respectively, whereas in D-4F⫹statin treated mice the amyloid burden in hippocampus decreased significantly (1.6⫾0.2%, p⬍ 0.001 vs control and p⬍ 0.01 vs Sc-D-4F⫹statin group). Brain cytokine levels such as TNF-␣ and IL-1␤ levels were also reduced in D-4F administered group compared to the other two groups. Conclusions: In a mouse model of AD, D-4F⫹statin inhibits amyloid deposition in the hippocampus. Along with inhibition of amyloid plaque, the peptide also improves the hippocampal dependent spatial memory and retention. We also observed lower brain cytokine levels in the D-4F⫹ statin treated group. This can therefore be a potential therapy for AD. P2-300

INHIBITORS OF CATHEPSIN B FOR ALZHEIMER’S DISEASE THERAPEUTICS

Greg Hook1, Mark Kindy2, Vivian Hook3, 1ALSP, Inc., San Diego, CA, USA; 2ANI, Charleston, SC, USA; 3University of California, San Diego, San Diego, CA, USA. Contact e-mail: [email protected] Background: Compounds that inhibit beta-secretase cleavage of amyloid precursor protein (APP) and thereby reduce extracellular brain beta-amyloid (Abeta) accumulation have potential as Alzheimer disease (AD) therapeutics. Neurons secrete most brain Abeta via their regulated secretory pathway and the beta-secretase activity in the vast majority of AD patients

cleaves APP containing the wild-type beta-secretase site. Isolated regulated secretory vesicles (RSV) from neuronal-like bovine chromaffin cells produce Abeta and contain beta-secretase activity, which has been purified and identified as due to cathepsin B. RSV beta-secretase activity and cathepsin B readily and efficiently cleave a wild-type beta-secretase substrate mimic. Methods: The RSV and cathepsin B beta-secretase assays were used to select compounds for evaluation in cell and animal models having APP containing the human wild-type beta-secretase site sequence, primary bovine chromaffin cells, guinea pigs, and transgenic AD mice expressing human APP containing the London mutations. Results: The selective cathepsin B inhibitors CA074 and AC-LVK-CHO, as well as the general cysteine protease inhibitor E64c, were potent inhibitors of RSV and cathepsin B cleavage of the wild-type beta-secretase site mimic, having IC50 values in the low nM range. Treating chromaffin cells with CA074Me, the cell permeable ester of CA074, reduced Abeta secretion and beta-secretase activity in the regulated secretory pathway. Intracerebroventricular (icv) administration of CA074Me, AC-LVK-CHO or E64d, a prodrug ester of E64c, to the guinea pig reduced brain Abeta and beta-secretase activity as well as Abeta in brain synaptosome fractions, which are an in vivo measure of the regulated secretory pathway. Significantly, CA074Me or E64d icv treatment of the transgenic AD mice improved memory deficit and reduced brain plaque, Abeta and beta-secretase activity. Conclusions: The RSV and cathepsin B assays select for compounds that are efficacious in AD animal models representative of most AD patients. These compounds act by inhibiting cathepsin B beta-secretase cleavage of the wild-type betasecretase site in the regulated secretory pathway. As such, cathepsin B inhibitors represent a new potential class of AD therapeutics. P2-301

REDUCED BRAIN ␤-AMYLOID BURDEN, ASSOCIATED MICROGLIA INFLAMMATION AND SPATIAL MEMORY DEFICIT IN HAPP TRANSGENIC MICE TREATED FOR SIX MONTHS WITH CHF5074, A NOVEL GAMMASECRETASE MODULATOR

Bruno P. Imbimbo1, Birgit Hutter-Paier2, Gino Villetti1, Fabrizio Facchinetti1, Manfred Windisch2, 1Chiesi Farmaceutici, Parma, Italy; 2JSW CNS Research, Forschungslabor GmbH, Graz, Austria. Contact e-mail: [email protected] Background: Gamma-secretase is responsible for the intramembraneous cleavage of the amyloid precursor protein (APP), the Notch receptor, and several other substrates. While inhibition of gamma-secretase results in potentially therapeutic reductions in the neurotoxic A␤ peptide, severe side effects might result from inhibiting Notch processing. CHF5074 is a new functional gamma-secretase modulator, devoid of Notch-interfering activities in vitro and in vivo. We evaluated the effects of long-term treatment with CHF5074 on brain A␤ pathology in transgenic mice (hAPP) expressing the Swedish and London mutations of human APP. Methods: Sixty 6-month old hAPP mice were treated for 6 months with CHF5074 (375 ppm in the diet), ibuprofen (375 ppm in the diet) or standard diet. Twentyone age-matched wild type mice received standard diet for 6 months. Plaque load in cortex and hippocampus was evaluated using 6E10 antibodies. Microglia was estimated using monoclonal CD11b antibodies. Spatial memory was assessed with the Morris water maze (MWM). Results: Compared to transgenic controls, CHF5074 treatment significantly reduced the area occupied by plaques in cortex (-34.3⫾6.1%, p⫽0.039) and hippocampus (-44.5⫾4.9%, p⫽0.002). Number of plaques were also significantly reduced by CHF5074 (-32.2⫾4.8%, p⫽0.022 and -39.8⫾4.9%, p⫽0.003, in cortex and hippocampus, respectively). Plaqueassociated microglia in CHF5074-treated animals was significantly lower than in transgenic controls (-42.1⫾5.4% and -44.6⫾8.3% in cortex and hippocampus, respectively). Ibuprofen significantly reduced microglia area in cortex and hippocampus (-40.6⫾7.9% and -37.7⫾5.2%, respectively) but not ␤-amyloid burden (-18.2⫾10.6%, and -25.2⫾10.1%, respectively). On Day 4 of the MWM test, transgenic controls performed significantly worse the non-transgenic animals on both the escape latency (28.0⫾4.3 vs