Aim: The effect of liposomes bi-functionalized with phosphatidic acid and with a synthetic peptide derived from human apolipoprotein E has been evaluated on the aggregation features of different amyloidogenic proteins: human Amyloid β1-40 (Aβ1-40), transthyretin (TTR) variant S52P, human β2microglobulin (β2m) variants ΔN6 and D76N, Serum Amyloid A (SAA).
Methods: The formation of fibrillar aggregates of the proteins was investigated by ThioflavinT fluorescence assay and validated by Atomic Force Microscopy.
Results: The results show that liposomes are preventing the transition of non-aggregated forms to the fibrillar state, with stronger effects on Aβ1-40, β2m ΔN6 and SAA. Liposomes also induce disaggregation of the amyloid aggregates of all the proteins investigated, with stronger effects on Aβ1-40, β2 D76N and TTR.SPR assays show that liposomes bind Aβ1-40 and SAA aggregates with high affinity (KD in the nanomolar range) whereas binding to TTR aggregates showed a lower affinity (KD in the micromolar range). Aggregates of β2m variants showed both high and low affinity binding sites. Computed Structural analysis of protein fibrillar aggregates and considerations on the multidentate features of liposomes allow to speculate a common mechanism of action, based on binding the β-stranded peptide regions responsible for the amyloid formation.
Conclusion: Thus, multifunctional liposomes perform as pharmacological chaperones with anti-amyloidogenic activity, with a promising potential for the treatment of a number of protein-misfolding diseases.Key messageAmyloidosis is a group of diseases, each due to a specific protein misfolding.Anti-amyloidogenic nanoparticles have been gaining the utmost importance as a potential treatment for protein misfolding disorders.Liposomes bi-functionalized with phosphatidic acid and with a synthetic peptide derived from human apolipoprotein E showed anti-amyloidogenic activity.
Keywords: Amyloidosis; Aβ1–40; SAA; TTR; liposomes; β2microglobulin.