Chemical-Driven Outflow of Dissociated Amyloid Burden from Brain to Blood.

Amyloid-ß (Aß) deposition in the brain is a primary biomarker of Alzheimer's disease (AD) and Aß measurement for AD diagnosis mostly depends on brain imaging and cerebrospinal fluid analyses. Blood Aß can become a reliable surrogate biomarker if issues of low concentration for conventional laboratory instruments and uncertain correlation with brain Aß are solved. Here, brain-to-blood efflux of Aß is stimulated in AD transgenic mice by orally administrating a chemical that dissociates amyloid plaques and observing the subsequent increase of blood Aß concentration. 5XFAD transgenic and wild-type mice of varying ages and genders are prepared, and blood samples of each mouse are collected six times for 12 weeks; three weeks of no treatment and additional nine weeks of daily oral administration, ad libitum, of Aß plaque-dissociating chemical agent. By the dissociation of Aß aggregates, the altered levels of plasma Aß distinguish between transgenic and wild-type mice, displaying potential as an amyloid burden marker of AD brains.

Bicine promotes rapid formation of ß-sheet-rich amyloid-ß fibrils.

Fibrillar aggregates of amyloid-ß (Aß) are the main component of plaques lining the cerebrovasculature in cerebral amyloid angiopathy. As the predominant Aß isoform in vascular deposits, Aß40 is a valuable target in cerebral amyloid angiopathy research. However, the slow process of Aß40 aggregation in vitro is a bottleneck in the search for Aß-targeting molecules. In this study, we sought a method to accelerate the aggregation of Aß40 in vitro, to improve experimental screening procedures. We evaluated the aggregating ability of bicine, a biological buffer, using various in vitro methods. Our data suggest that bicine promotes the aggregation of Aß40 with high speed and reproducibility, yielding a mixture of aggregates with significant ß-sheet-rich fibril formation and toxicity.

Discovery of Chemicals to Either Clear or Indicate Amyloid Aggregates by Targeting Memory-Impairing Anti-Parallel Aß Dimers.

Amyloid-ß (Aß) oligomers are implicated in Alzheimer disease (AD). However, their unstable nature and heterogeneous state disrupts elucidation of their explicit role in AD progression, impeding the development of tools targeting soluble Aß oligomers. Herein parallel and anti-parallel variants of Aß(1-40) dimers were designed and synthesized, and their pathogenic properties in AD models characterized. Anti-parallel dimers induced cognitive impairments with increased amyloidogenesis and cytotoxicity, and this dimer was then used in a screening platform. Through screening, two FDA-approved drugs, Oxytetracycline and Sunitinib, were identified to dissociate Aß oligomers and plaques to monomers in 5XFAD transgenic mice. In addition, fluorescent Astrophloxine was shown to detect aggregated Aß in brain tissue and cerebrospinal fluid samples of AD mice. This screening platform provides a stable and homogeneous environment for observing Aß interactions with dimer-specific molecules.

Rapid and sustained cognitive recovery in APP/PS1 transgenic mice by co-administration of EPPS and donepezil.

Alzheimer's disease (AD) is a neurodegenerative disease characterized by sequential progression of pathological events, such as aggregation of amyloid-ß proteins, followed by outward symptoms of cognitive impairments. Given that a combination of different therapeutic strategies often provides more rapid and effective outcomes in diverse areas of clinical treatment, we hypothesized that administration of anti-amyloid drugs with cognitive enhancers would result in synergistic effects in AD treatment. Here, we co-administered 4-(2-hydroxyethyl)-1-piperazinepropane-sulphonic acid (EPPS), an amyloid-clearing chemical, and donepezil, an acetylcholinesterase inhibitor, to determine whether they could serve complementary roles for each other in regards to AD treatment. We found that oral administration of these two molecules led to a rapid and consistent cognitive improvement in APP/PS1 transgenic mice. Although there was no evidence for synergistic effects, our results indicated that EPPS and donepezil function complementary to each other without altering their individual effects. Thus, the combined use of disease-modifying and symptomatic relief drugs may be a promising approach in the treatment of AD.

Age-dependent inverse correlations in CSF and plasma amyloid-ß(1-42) concentrations prior to amyloid plaque deposition in the brain of 3xTg-AD mice.

Amyloid-ß (Aß) plays a critical role as a biomarker in Alzheimer's disease (AD) diagnosis. In addition to its diagnostic potential in the brain, recent studies have suggested that changes of Aß level in the plasma can possibly indicate AD onset. In this study, we found that plasma Aß(1-42) concentration increases with age, while the concentration of Aß(1-42) in the cerebrospinal fluid (CSF) decreases in APPswe, PS1M146V and TauP301L transgenic (3xTg-AD) mice, if measurements were made before formation of ThS-positive plaques in the brain. Our data suggests that there is an inverse correlations between the plasma and CSF Aß(1-42) levels until plaques form in transgenic mice's brains and that the plasma Aß concentration possesses the diagnostic potential as a biomarker for diagnosis of early AD stages.

EPPS rescues hippocampus-dependent cognitive deficits in APP/PS1 mice by disaggregation of amyloid-ß oligomers and plaques.

Alzheimer's disease (AD) is characterized by the transition of amyloid-ß (Aß) monomers into toxic oligomers and plaques. Given that Aß abnormality typically precedes the development of clinical symptoms, an agent capable of disaggregating existing Aß aggregates may be advantageous. Here we report that a small molecule, 4-(2-hydroxyethyl)-1-piperazinepropanesulphonic acid (EPPS), binds to Aß aggregates and converts them into monomers. The oral administration of EPPS substantially reduces hippocampus-dependent behavioural deficits, brain Aß oligomer and plaque deposits, glial γ-aminobutyric acid (GABA) release and brain inflammation in an Aß-overexpressing, APP/PS1 transgenic mouse model when initiated after the development of severe AD-like phenotypes. The ability of EPPS to rescue Aß aggregation and behavioural deficits provides strong support for the view that the accumulation of Aß is an important mechanism underlying AD.

Correlations of amyloid-ß concentrations between CSF and plasma in acute Alzheimer mouse model.

Amyloid-ß (Aß) is one of the few neuropathological biomarkers associated with transporters of the blood-brain barrier (BBB). Despite the well-characterized clinical indication of decreasing Aß levels in the cerebrospinal fluid (CSF) during the development of Alzheimer's disease (AD), the link between the alternation of Aß level in the blood and the progress of the disorder is still controversial. Here, we report a direct correlation of Aß(1-42) levels between CSF and plasma in AD mouse model. We injected monomeric Aß(1-42) directly into the intracerebroventricular (ICV) region of normal adult mouse brains to induce AD-like phenotypes. Using sandwich enzyme-linked immunosorbent assays, we observed proportional elevation of Aß(1-42) levels in both CSF and plasma in a dose-dependent manner. Our findings that plasma Aß(1-42) reflects the condition of CSF Aß(1-42) warrant further investigation as a biomarker for the blood diagnosis of AD.

Therapeutic and pharmacokinetic characterizations of an anti-amyloidogenic bis-styrylbenzene derivative for Alzheimer's disease treatment.

Alzheimer's disease drug discovery regarding exploration into the molecules and processes has focused on the intrinsic causes of the brain disorder correlated with the accumulation of amyloid-ß. An anti-amyloidogenic bis-styrylbenzene derivative, KMS80013, showed excellent oral bioavailability (F=46.2%), facilitated brain penetration (26%, iv) in mouse and target specific in vivo efficacy in acute AD mouse model attenuating the cognitive deficiency in Y-maze test. Acute toxicity (LD50 >2000 mg/kg) and hERG channel inhibition (14% at 10 µM) results indicated safety of KMS80013.

Amelioration of Alzheimer's disease by neuroprotective effect of sulforaphane in animal model.

Pathophysiological evidences of AD have indicated that aggregation of Aß is one of the principal causes of neuronal dysfunction, largely by way of inducing oxidative stresses such as free radical formation. We hypothesized that the known antioxidative attribute of SFN could be harnessed in Alzheimer's treatment. SFN is an indirect, potent antioxidant derived from broccoli that has previously been found to stimulate the Nrf2-ARE pathway and facilitate several other cytoprotective mechanisms. In this study, administration of SFN ameliorated cognitive function of Aß-induced AD acute mouse models in Y-maze and passive avoidance behavior tests. Interestingly, we found that the therapeutic effect of SFN did not involve inhibition of Aß aggregation. While the exact mechanism of interaction of SFN in AD has not yet been ascertained, our results suggest that SFN can aid in cognitive impairment and may protect the brain from amyloidogenic damages.