Maria Becker

EFRH-phage immunization of Alzheimer's disease animal model improves behavioral performance in Morris water maze trials.

We have developed an immunization procedure for the production of effective anti-β-amyloid (anti-Aβ) antibodies, using filamentous phage displaying only 4 amino acids. The EFRH sequence, encompassing amino acids 3–6 of the 42 residues of Aβ peptide, was found previously to be the main regulatory site for amyloid modulation and the epitope of anti-aggregating antibodies. Engineered filamentous phage enable the display of various numbers of EFRH copies on the phage and serve as potent carriers of antigens. In the present study we have found that phage displaying high EFRH copy number are effective in eliciting humoral response against the EFRH sequence, which in turn relieves the amyloid burden in the brains of amyloid precursor protein Tg mice and improves their ability to perform cognitive tasks.

Stimulation of endogenous neurogenesis by anti-EFRH immunization in a transgenic mouse model of Alzheimer's disease

Neurogenesis is a subject of intense interest and extensive research, but it stands at the center of a bitter debate over ethical and practical problems. Neurodegenerative diseases, such as Alzheimers disease (AD), accompanied by a shifting balance between neurogenesis and neurodegeneration, are suitable for stimulation of neurogenesis for the benefit of diseased patients. We have previously shown that Abs against the EFRH sequence of β-amyloid peptide (AβP) prevent aggregation and disaggregate AβP both in vitro and in vivo. EFRH, located in the soluble tail of the N-terminal region, acts as a regulatory site controlling both solubilization and disaggregation processes in the AβP molecule. Here we show that anti-EFRH immunotherapy of a platelet-derived amyloid precursor protein transgenic mouse model of AD stimulates endogenous neurogenesis, suggested by elevated numbers of BrdU-incorporated cells, most of which are colocalized with a marker of mature neurons, NeuN. These newly born neurons expressed the activity-dependent gene Zif268, indicating their functional integration and participation in response to synaptic input in the brain. These findings suggest that anti-amyloid immunotherapy may promote recovery from AD or other diseases related to AβP overproduction and neurotoxicity by restoring neuronal population, as well as cognitive functions in treated patients.

Beneficial effect of antibodies against β- secretase cleavage site of APP on Alzheimer's-like pathology in triple-transgenic mice.

The toxicity of amyloid β and tau, the two hallmark proteins in Alzheimer’s disease (AD), has been extensively studied individually. Recently new data suggest their possible interactions and synergistic effects in the disease. In this study, we investigate the ability of antibodies against the β secretase cleavage site on APP, named BBS1, to affect tau pathology, besides their well established effect on intracellular Aβ and amyloid load. For this purpose we treated the triple transgenic mice model of AD (3x Tg-AD) with mAb BBS1 intracerebroventricularly, using mini osmotic pumps for one month. The experimental data demonstrated reduction in total and phosphorylated tau levels, explained by significant reduction in GSK3β which phosphorylates tau on sites recognized by antibodies against PHF1 and AT-8. The treatment increased the cognitive capabilities and reduced the brain inflammation levels which accompany AD pathology. The data showing that tau pathology was significantly reduced by BBS1 antibodies suggest a close interaction between tau and Aβ in the development of AD, and may serve as an efficient novel immunotherapy against both hallmarks of this disease.

Changes in the Basal Membrane of Dorsal Root Ganglia Schwann Cells Explain the Biphasic Pattern of the Peripheral Neuropathy in Streptozotocin-Induced Diabetic Rats

Peripheral neuropathy is one of the main complications of diabetes mellitus. The current study demonstrated the bimodal pattern of diabetic peripheral neuropathy found in the behavioral study of pain perception in parallel to the histopathological findings in dorsal root ganglia (DRGs) neurons and satellite Schwann cell basement membranes. A gradual decrease in heparan sulfate content, with a reciprocal increase in deposited laminin in the basement membranes of dorsal root ganglia Schwann cells, was shown in streptozotocin-treated rats. In addition, the characteristic biphasic pain profiles were demonstrated in diabetic rats, as shown by hypersensitivity at the third week and hyposensitivity at the tenth week post-streptozotocin injection, accompanied by a continuous decrease in the sciatic nerve conduction velocity. It appears that these basal membrane abnormalities in content of heparan sulfate and laminin, noticed in diabetic rats, may underline the primary damage in dorsal ganglion sensory neurons, simultaneously with the bimodal painful profile in diabetic peripheral neuropathy, simulating the scenario of filtration rate in diabetic kidney.

Inhibition of Amyloid Precursor Protein Beta-Secretase Cleavage Site Affects Survival and Motor Functions of Amyotrophic Lateral Sclerosis Transgenic Mice

Background: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease defined by motor neuron loss. Recent studies have reported an increase in amyloid precursor protein (APP) levels and in its cleavage products in ALS patients indicating their possible involvement in this disease. APP is a transmembrane protein processed either by β-secretase or α-secretase followed by γ-secretase. The APP cleavage products – soluble APP-β (sAPPβ), amyloidogenic Aβ, and amino-terminal fragment N-APP – mediate a reduction in synaptic transmission, synaptic loss, neurite retraction and, ultimately, programmed cell death. Objective: To elucidate the role of APP cleavage products in the pathology of ALS. Methods: ALS mouse models that express mutant superoxide dismutase 1 were treated intraventricularly with a monoclonal antibody that blocks the β-secretase cleavage site on APP. Levels of the APP cleavage product called sAPPβ, motor functions and survival were assessed. Results: Inhibition of APP cleavage at a presymptomatic stage resulted in a decrease in the levels of sAPPβ, delay of disease onset and deterioration while at the symptomatic stage there was almost no beneficial effect. Conclusion: APP cleavage products might contribute to the degeneration in ALS, and early inhibition of the APP process may ameliorate disease progression.

Immunomodulation of AβPP Processing Alleviates Amyloid-β-Related Pathology in Alzheimer's Disease Transgenic Mice

Among the different paradigms aimed at interfering with amyloid-β (Aβ)-related pathology, the attenuation of amyloid-β protein precursor (AβPP) processing to limit Aβ levels seems to be a promising one. Along with the development of BACE1 inhibitors, and the generation of its knock-out mice, accumulating data raise concerns regarding a total inhibition of the enzyme as it shares the processing of other substrates. We described a novel approach to interfere with the specific interaction between AβPP and BACE1 using monoclonal antibodies directed to the β-secretase cleavage site upon the substrate, AβPP. Such antibodies limit AβPP cleavage in a cellular model of Alzheimers disease (AD) and avoid the total inhibition of BACE1. Here, we demonstrate the ability of AβPP β-site antibodies to interfere with Aβ production in vivo. Systemic antibody treatment diminished Aβ plaques, membrane-associated oligomers, and intracellular Aβ accumulation, all of which have been implicated in cellular death and synaptic loss, suggesting that this approach may be an applicable strategy for AD treatment.