A mirror-phage display selected D-peptide and its derivative eliminate Abeta oligomers in vitro and decelerate cognitive and motoric impairments of transgenic AD mice in vivo

Several lines of research provide strong evidence for a central role of amyloid-beta (Abeta) oligomers in the pathogenesis of Alzheimer's disease. Investigations on Abeta oligomer interference, however, are impeded by the lack of a quantitative assay to measure substance-induced effects on Abeta oligomers. We have developed a comprehensive, fast and reliable in vitro assay to quantify the removal of Abeta oligomers by any potential drug, for example D3 and its dimeric form, denominated D3D3. This multivalent D3 molecule was expected to have enhanced efficacy due to increased avidity. Therefore we wanted to investigate if there is a correlation between the removal of Abeta oligomers by D3 and D3D3 and positive effects on cognitive and motoric performance in transgenic AD animal models

Comprehensive characterization of the pyroglutamate Aβ induced motor neurodegenerative phenotype of TBA2.1 mice

Alzheimer’s disease (AD) is the most common neurodegenerative disorder and is being intensively investigated using a broad variety of animal models. Many of these models express mutant versions of human amyloid-β protein precursor (AβPP) that are associated with amyloid-β protein (Aβ)-induced early onset familial AD. Most of these models, however, do not develop bold neurodegenerative pathology and the respective phenotypes. Nevertheless, this may well be essential for their suitability to identify therapeutically active compounds that have the potential for a curative or at least disease-modifying therapy in humans. In this study, the new transgenic mouse model TBA2.1 was explored in detail to increase knowledge about the neurodegenerative process induced by the presence of pyroglutamate modified human Aβ3-42 (pEAβ3-42). Analysis of the sensorimotor phenotype, motor coordination, Aβ pathology, neurodegeneration, and gliosis revealed formation and progression of severe pathology and phenotypes including massive neuronal loss in homozygous TBA2.1 mice within a few months. In contrast, the start of a slight phenotype was observed only after 21 months in heterozygous mice. These data highlight the role of pEAβ3-42 in the disease development and progression of AD. Based on the findings of this study, homozygous TBA2.1 mice can be utilized to gain deeper understanding in the underlying mechanisms of pEAβ3-42 and might be suitable as an animal model for treatment studies targeting toxic Aβ species, complementary to the well described transgenic AβPP mouse models

Aβ oligomer eliminating compounds interfere successfully with pEAβ (3–42) induced motor neurodegenerative phenotype in transgenic mice

Currently, there are no causative or disease modifying treatments available for Alzheimer's disease (AD). Previously, it has been shown that D3, a small, fully d-enantiomeric peptide is able to eliminate low molecular weight Aβ oligomers in vitro, enhance cognition and reduce plaque load in AD transgenic mice. To further characterise the therapeutic potential of D3 towards N-terminally truncated and pyroglutamated Aβ (pEAβ(3–42)) we tested D3 and its head-to-tail tandem derivative D3D3 both in vitro and in vivo in the new mouse model TBA2.1. These mice produce human pEAβ(3–42) leading to a strong, early onset motor neurodegenerative phenotype. In the present study, we were able to demonstrate 1) strong binding affinity of both D3 and D3D3 to pEAβ(3–42) in comparison to Aβ(1–42) and 2) increased affinity of the tandem derivative D3D3 in comparison to D3. Subsequently we tested the therapeutic potentials of both peptides in the TBA2.1 animal model. Truly therapeutic, non-preventive treatment with D3 and D3D3 clearly slowed the progression of the neurodegenerative TBA2.1 phenotype, indicating the strong therapeutic potential of both peptides against pEAβ(3–42) induced neurodegeneration

ABC Transporters B1, C1 and G2 Differentially Regulate Neuroregeneration in Mice

Background: ATP-binding cassette (ABC) transporters are essential regulators of organismic homeostasis, and are particularly important in protecting the body from potentially harmful exogenous substances. Recently, an increasing number of in vitro observations have indicated a functional role of ABC transporters in the differentiation and maintenance of stem cells. Therefore, we sought to determine brain-related phenotypic changes in animals lacking the expression of distinct ABC transporters (ABCB1, ABCG2 or ABCC1). Methodology and Principal Findings: Analyzing adult neurogenesis in ABC transporter-deficient animals in vivo and neuronal stem/progenitor cells in vitro resulted in complex findings. In vivo, the differentiation of neuronal progenitors was hindered in ABC transporter-deficient mice (ABCB1 0/0) as evidenced by lowered numbers of doublecortin + (236%) and calretinin + (237%) cells. In vitro, we confirmed that this finding is not connected to the functional loss of single neural stem/ progenitor cells (NSPCs). Furthermore, assessment of activity, exploratory behavior, and anxiety levels revealed behavioral alterations in ABCB1 0/0 and ABCC1 0/0 mice, whereas ABCG2 0/0 mice were mostly unaffected. Conclusion and Significance: Our data show that single ABC transporter-deficiency does not necessarily impair neuronal progenitor homeostasis on the single NSPC level, as suggested by previous studies. However, loss of distinct ABC transporters impacts global brain homeostasis with far ranging consequences, leading to impaired neurogenic functions i

QIAD assay for quantitating a compound’s efficacy in elimination of toxic Aβ oligomers

Strong evidence exists for a central role of amyloid β-protein (Aβ) oligomers in the pathogenesis of Alzheimer’s disease. We have developed a fast, reliable and robust in vitro assay, termed QIAD, to quantify the effect of any compound on the Aβ aggregate size distribution. Applying QIAD, we studied the effect of homotaurine, scyllo-inositol, EGCG, the benzofuran derivative KMS88009, ZAβ3W, the D-enantiomeric peptide D3 and its tandem version D3D3 on Aβ aggregation. The predictive power of the assay for in vivo efficacy is demonstrated by comparing the oligomer elimination efficiency of D3 and D3D3 with their treatment effects in animal models of Alzheimer´s disease

ABC transporters are important for neurogenic functions during disease states as revealed by the CCI paradigm.

<p>The proliferation capacity measured by BrdU incorporation (A) was significantly decreased in the induced hemisphere of all ABC transporter-deficient strains (ABCB1^0/0: −47%; ABCG2^0/0: −31%; ABCC1^0/0: −53%) (right). The number of Sox2⁺ cells was not significantly altered in the induced brain hemisphere (B), but shows a trend toward a decreased number in ABCB1- and ABCC1- deficient mice that resembles the decreases in immature DCX⁺ and calretinin⁺ neurons (C, D). The number of DCX⁺ neuronal progenitors (B) was significantly reduced in the induced hemisphere of ABCB1- (−36%) or ABCC1-deficient (−33%) animals as compared to controls (right). Additionally, the number of early granule cells expressing calretinin (D) was decreased in the induced hemisphere of ABCB1- (29%) and ABCC1-deficient mice (−24%) (right), while there was no change in ABCG2-deficient mice. Error bars: SEM, *p<0.05; **p<0.01; ***p<0.001.</p

Neurogenesis is induced by controlled cortical impact (CCI) trauma.

<p>The photomicrographs show the SGZ of the DG after CCI (LEFT: Control hemispheres; RIGHT: hemispheres after CCI). Shown are the marker combinations Sox2/BrdU (A), DCX/BrdU (B) and calretinin/BrdU (C). Arrowheads indicate double labeled cells. Scale bar: 20 µm.</p

Light/dark box experiments verified altered anxiety and exploratory behavior.

<p>Comparing the running distance of the animals in the open field revealed no significant differences (A). However, the distance traveled by ABCB1-deficient mice (+64%) in the dark compartment (B) was significantly increased compared to the controls. Also, the time in the dark compartment (C) was significantly increased in ABCB1^0/0 mice (+78%) compared to controls. The mean number of transitions between the two compartments (D) was impaired in both ABCB1^0/0 (−59%) and ABCC1^0/0 (−49%) mice. Comparing the rearing frequency in both compartments revealed a significant decrease for ABCC1^0/0 (−67%) mice in the open field (E), while the frequency was increased in the dark compartment (F) for ABCB1^0/0 (+71%) mice. Error bar: SEM, *</p