Potential Lead for an Alzheimer Drug: A Peptide That Blocks Intermolecular Interaction and Amyloid β Protein-Induced Cytotoxicity

Modulation of fibril formation by a beta-sheet breaker peptide ligand: an electrochemical approach

The development of generic inhibitors in order to control the formation of amyloid fibrils and early oligomers is still an unmet medical need. Here, we demonstrate the applicability of electrochemical analysis for the detection of β-sheet breaker peptide ligands that act as excellent inhibitors of Alzheimer's disease (AD) amyloid-β (Aβ) fibrils and oligomers in vitro. As the case study, a well-defined β-sheet breaker pentapeptide (LPFFD, FibIII) was utilized with Aβ(1-42) peptides. Square wave voltammetry (SWV) measurements were confirmed with simultaneous fluorescence analysis of the same incubated Aβ samples using a well-known fluorescent marker of β-sheet formation, Thioflavin T (ThT). Significant changes in the electrochemical signals were observed for the interaction of the Aβ oligomers with FibIII at the early stages of aggregation. The electrochemical approach, in principle, allowed monitoring β-sheet breaker-Aβ interactions on the time scale of aggregation in a label-free and cost-effective format using screen-printed carbon strip (SPCS) electrodes.

Cholesterol metabolism and transport in the pathogenesis of Alzheimer's disease

Alzheimer's disease (AD) is the most common neurodegenerative disorder, affecting millions of people worldwide. Apart from age, the major risk factor identified so far for the sporadic form of AD is possession of the epsilon4 allele of apolipoprotein E (APOE), which is also a risk factor for coronary artery disease (CAD). Other apolipoproteins known to play an important role in CAD such as apolipoprotein B are now gaining attention for their role in AD as well. AD and CAD share other risk factors, such as altered cholesterol levels, particularly high levels of low density lipoproteins together with low levels of high density lipoproteins. Statins--drugs that have been used to lower cholesterol levels in CAD, have been shown to protect against AD, although the protective mechanism(s) involved are still under debate. Enzymatic production of the beta amyloid peptide, the peptide thought to play a major role in AD pathogenesis, is affected by membrane cholesterol levels. In addition, polymorphisms in several proteins and enzymes involved in cholesterol and lipoprotein transport and metabolism have been linked to risk of AD. Taken together, these findings provide strong evidence that changes in cholesterol metabolism are intimately involved in AD pathogenic processes. This paper reviews cholesterol metabolism and transport, as well as those aspects of cholesterol metabolism that have been linked with AD.