Developing Topics e67

Background: The major neuropathological hallmarks in the brains of

AD patients are senile plaques formed by beta amyloid (Aß) aggregates

and neurofibrillary tangles, containing hyperphosphorylated tau, both

causing progressive neuronal dysfunction. These pathological alterations

are likely causally involved in eventual neuronal death, particularly in

brain regions related to memory and cognition. The first attempt to de-

velop an active vaccine to Aß, AN1793, failed in clinical trials due to

a Th1 type T cell immune response, attributed to the adjuvant used,

QS21 and polysorbate 80, provoking a meningoencephalitis-like effect

and death in 6% of the patients. To overcome this failure, we designed

a novel Aß1-42 active vaccine incorporated and delivered in a liposomal

adjuvant that evoked aTh2 T cell reaction. Methods: Aß was

incorporated and delivered in a liposomal matrix composed of phospha-

tidylcholine: phosphatidylglycerol: cholesterol:sphingosine-1-phosphate

(EB101) and administered intraperitoneally for seven months to double

transgenic mice (B6C3-Tg (APPswe,PSEN1dE9)), before or after the

AD pathology was developed (In 7-week and 37-week old mice respec-

tively). Aß plaques and neurofibrillary tangles were quantified by ELI-

SAs and brain histology using specific antibodies. Basal

immunological interaction between the T-cells in the affected hippocam-

palarea and other immune activation markers, including glial fibrillary

acidicprotein (GFAP) (astroglia) and CD-45 (B-cells) were also studied

using immunoreactive-specific staining. T-cell reaction type was as-

sessed by cytokine type production. Results: Both preventive and thera-

peutic vaccination with EB101 resulted in a marked inhibition of Aß

deposits (60 to 80%), a reduction of neurofibrillary tangles (70 to

90%) and almost completely suppression of reactive gliosis as measured

by GFAP immunoreactivity and cytokine profile, consistent with

a marked decrease in amyloidosis-induced inflammation. No external

neurological deficits were observed as a result of EB101 immunization

(limb paralysis or brain atrophy). Psychomotor and cognitive tests per-

formed in a rota-rod in these animals also showed a dramatic improve-

ment in learning and psychomotor activity in the EB101-treated group.

Conclusions: The present findings unequivocally indicate that immuniza-

tion with EB101 not only prevents and reverses AD neuropathology and

underlined inflammation, but also improves cognitive symptoms, thus

warranting further studies.

P4-445 EARLYAND CHRONIC TREATMENT WITH

DANTROLENEBLOCKEDLATER LEARNINGAND

MEMORY DEFICITS IN OLDER ALZHEIMER’S

TRIPLE TRANSGENIC MICE

Jun Peng, Ge Liang, Saadet Inan, Zhen Wu, Donald Joseph,

Qingcheng Meng, Yi Peng, Maryellen Eckenhoff, Huafeng Wei, University

of Pennsylvania, Philadelphia, Pennsylvania, United States.

Background: Disruption of intracellular calcium homeostasis via abnor-

mal and excessive activation of ryanodine receptors plays an important

role in the neuropathology of Alzheimer’s disease (AD). We investigated

the effects of dantrolene, a ryanodine receptor antagonist and a clinically

available drug to treat malignant hyperthermia in anesthesia practice, on

the cognitive function and pathology in a triple transgenic mouse model

(3xTgAD) of AD. Methods: 3xTgAD mice were treated with continuous

intracerebraventricular (ICV) injection of dantrolene (100 mM, 2-4 ml

per day) or vehicle control (DMSO, 2-4 ml per day) starting at 2 months

of age using implanted Alzet pumps. The drug or vehicle supplies in the

pumps were changed once a month for 3 months. Thereafter, the mice

were continuously treated with subcutaneous injections of dantrolene

(5 mg/kg) or vehicle control (DMSO) 3 times a week until 13 months

of age. Additional control groups consisted of wild type and 3xTgAD

mice which received no treatment. Learning and memory were tested

in all animals at 2, 6, 10 and 13 months of age using the Morris Water

Maze. All mice were then euthanized and the brains analyzed for amy-

loid plaques, cytosolic cytochrome C, phosphorylated tau and synaptic

proteins (PSD 95) using quantitative immunohistochemistry and western

blot assays. Results: 3xTgAD control mice first displayed learning and

memory impairments at 10 months, which were more pronounced at 13

months of age. Long-term dantrolene treatment nearly abolished these

learning and memory deficits in 3xTgAD mice compared to vehicle and

wild type controls. Dantrolene treatment also significantly decreased the

number of amyloid plaques in the hippocampus and the amount of cyto-

chrome C in the cytosolic space, but had no effect on phosphorylated

tau or synaptic marker levels in AD brains. Finally, neither dantrolene

nor vehicle treatment significantly affected motor function. Conclusions:

Our results suggest that dantrolene, a currently available ryanodine recep-

tor calcium channel antagonist, significantly improves cognition in a mu-

rine model of Alzheimer’s disease and is associated with a reduction in the

amyloid plaque burden and a decrease of a neurodegenerative biomarker in

AD brains, forming the basis of a novel pathway approach to therapy for

AD.

P4-446 TREATMENT OF MICE WITH TYROSINE KINASE

INHIBITORS (TKI) SUCH AS GLEEVEC LOWERS

PLASMA LEVELS OFAMYLOID BETA PEPTIDES

(ABETA) IN MICE

Marc Weksler1, Paul Szabo1, Antonia Coppus2, Marcus Reidenberg1,

Pankaj Mehta3, Richard Silver1, Norman Relkin1, Babette Weksler1, 1Weill

Cornell Medical College, New York, New York, United States; 2Erasmus

University Medical Center, Rotterdam, Netherlands; 3Institute for Basic

Research, Staten Island, New York, United States.

Background:Considerable evidence exists that increased levels of Abeta

peptides (Abeta) augment the risk of Alzheimer’s disease (AD). Imati-

nib, a tyrosine inhibitor (TKI), has been shown in mice to decrease

synthesis of Abeta in vitro and in vivo although it poorly crosses the

blood-brain barrier. Recently, JG Sutcliffe suggested that cerebral levels

of Abeta are regulated in peripheral tissues. If TKI decreased Abeta pro-

duction in humans and lowered its plasma levels it might complement

the therapeutic efficacy of intravenous immunoglobulin (IVIg) now be-

ing studied in AD. Methods: Levels of Abeta40 and Abeta42 were mea-

sured in coded plasma samples from patients with chronic myeloid

leukemia (CML) treated with or without TKI and from healthy age-

matched individuals not receiving TKI. Plasma was frozen at -80C until

assayed using a sensitive ELISA with high avidity rabbit monoclonal an-

tibodies specific for Abeta40 or Abeta42. Results: Plasma Abeta peptide

levels were measured in 10 bcr-abl+ CML patients in cytogenetic remis-

sion and 1 bcr-abl+ ALL patient in remission treated with TKIs for one

to 9 years. Mean plasma Abeta40 in this group was 176 +/- 50 pg/ml

and mean Abeta42 74 +/- 41 pg/ml. These values were significantly lower

(p < 0.011, two-tailed rank-sum test) than in 3 plasmas CML patients not

treated with TKI (mean Abeta40 344 +/- 32; mean Abeta42, 204 +/- 40 pg/

ml). Plasma Abeta peptides in the 11 TKI-treated patients were also signif-

icantly lower (p < 0.048) than in 6 healthy individuals not receiving TKIs

(mean Abeta40, 258 +/- 45 and mean Abeta42, 125 +/- 47 pg/ml).Conclu-

sions: Patients with bcr-abl+ disease treated with TKIs for as long as 9

years had significantly lower plasma levels of Abeta40 and Abeta42

than CML patients not receiving TKI or normal individuals. This is the first

report that TKI therapy in humans is associated with a reduction in plasma

levels in Abeta 40 and Abeta 42. Our data imply that adding TKIs to other

therapies for AD such as IVIg might offer a uniquely effective pairing of

drugs, one clearing Abeta from the brain and another inhibiting Abeta syn-

thesis in AD patients.

P4-447 CONFORMATION DIRECTED

IMMUNOMODULATION TARGETING AMYLOID

PLAQUES, CAA AND NEUROFIBRILLARY

TANGLE PATHOLOGY IN MODEL MICE

Fernando Goni, Henrieta Scholtzova, Kinlung Wong, Yanjie Sun,

Jason Pan, Jialin Li, Yong Ji, Thomas Wisniewski, New York University

School of Medicine, New York, New York, United States.