Human recombinant butyrylcholinesterase purified from the milk of transgenic goats interacts with beta-amyloid fibrils and suppresses their formation in vitro.

BACKGROUND

In Alzheimer's disease (AD), brain butyrylcholinesterase (BChE) co-localizes with beta-amyloid (Abeta) fibrils.

AIMS

In vitro testing of the significance of this phenomenon to AD progress.

METHODS

A thioflavine T (ThT) fluorogenic assay, photo-induced cross-linking and quantifiable electron microscopy served to compare the effect on Abeta fibril formation induced by highly purified recombinant human BChE (rBChE) produced in the milk of transgenic goats with that of serum-derived human BChE.

RESULTS

Both proteins at 1:50 and 1:25 ratios to Abeta dose-dependently prolonged the ThT lag time and reduced the apparent rate of Abeta fibril formation compared to Abeta alone. Photo-induced cross-linking tests showed that rBChE prolonged the persistence of amyloid dimers, trimers and tetramers in solution, whereas Abeta alone facilitated precipitation of such multimers from solution. Transmission electron microscopy showed that rBChE at 1:100 to Abeta prevented the formation of larger, over 150-nm-long, Abeta fibrils and reduced fibril branching compared to Abeta alone as quantified by macro programming of Image Pro Plus software.

CONCLUSION

Our findings demonstrate that rBChE interacts with Abeta fibrils and can attenuate their formation, extension and branching, suggesting further tests of rBChE, with unlimited supply and no associated health risks, as a therapeutic agent for delaying the formation of amyloid toxic oligomers in AD patients.