Natural Compound from Olive Oil Inhibits S100A9 Amyloid Formation and Cytotoxicity: Implications for Preventing Alzheimer's Disease.

Manuela Leri,Ludmilla A Morozova-Roche,Igor A Iashchishyn,Monica Bucciantini,Himanshu Chaudhary,Željko M Svedružić,Greta Musteikyte,Jonathan Pansieri,Silvia Gómez Alcalde,Massimo Stefani,Vytautas Smirnovas

doi:10.1021/acschemneuro.0c00828

Manuela Leri, Ludmilla A Morozova-Roche + Show 9 more

Open Access

https://doi.org/10.1021/acschemneuro.0c00828

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Abstract

Polyphenolic compounds in the Mediterranean diet have received increasing attention due to their protective properties in amyloid neurodegenerative and many other diseases. Here, we have demonstrated for the first time that polyphenol oleuropein aglycone (OleA), which is the most abundant compound in olive oil, has multiple potencies for the inhibition of amyloid self-assembly of pro-inflammatory protein S100A9 and the mitigation of the damaging effect of its amyloids on neuroblastoma SH-SY5Y cells. OleA directly interacts with both native and fibrillar S100A9 as shown by intrinsic fluorescence and molecular dynamic simulation. OleA prevents S100A9 amyloid oligomerization as shown using amyloid oligomer-specific antibodies and cross-β-sheet formation detected by circular dichroism. It decreases the length of amyloid fibrils measured by atomic force microscopy (AFM) as well as reduces the effective rate of amyloid growth and the overall amyloid load as derived from the kinetic analysis of amyloid formation. OleA disintegrates already preformed fibrils of S100A9, converting them into nonfibrillar and nontoxic aggregates as revealed by amyloid thioflavin-T dye binding, AFM, and cytotoxicity assays. At the cellular level, OleA targets S100A9 amyloids already at the membranes as shown by immunofluorescence and fluorescence resonance energy transfer, significantly reducing the amyloid accumulation in GM1 ganglioside containing membrane rafts. OleA increases overall cell viability when neuroblastoma cells are subjected to the amyloid load and alleviates amyloid-induced intracellular rise of reactive oxidative species and free Ca2+. Since S100A9 is both a pro-inflammatory and amyloidogenic protein, OleA may effectively mitigate the pathological consequences of the S100A9-dependent amyloid-neuroinflammatory cascade as well as provide protection from neurodegeneration, if used within the Mediterranean diet as a potential preventive measure.

Highlights

Alzheimer’s disease (AD) and Parkinson’s disease (PD) as well as other amyloid-related neurodegenerative ailments are agerelated multifaceted pathological conditions in which a broad range of events lead to the impairment of brain activity with cognitive disability as the main clinical hallmark
We have found that S100A9 levels in CSF of AD and mild cognitive impairment match those of Aβ, further confirming its involvement in the amyloidneuroinflammatory cascade even at the disease preclinical and mild stages.[22]
Many papers have reported the effect on signaling pathways by direct binding of amyloids to cell membrane receptors.[52−55] we performed immunofluorescence assay with the GM1 and S100A9 specific fluorescently labeled antibodies using confocal microscopy and sensitized Fluorescence Resonance Energy Transfer (FRET) analysis to evaluate the interactions between the membrane ganglioside GM1 and S100A9 amyloids produced after the 48 h incubation in the absence or presence of oleuropein aglycone (OleA)

Summary

■ INTRODUCTION

Alzheimer’s disease (AD) and Parkinson’s disease (PD) as well as other amyloid-related neurodegenerative ailments are agerelated multifaceted pathological conditions in which a broad range of events lead to the impairment of brain activity with cognitive disability as the main clinical hallmark. The direct binding of amyloids to plasma membranes is a critical step in amyloid cytotoxicity.[46,47] Notably, amyloids can accumulate in membrane rafts, containing monosialotetrahexosylganglioside-1 (GM1).[48] The amyloid binding leads to structural and functional perturbations of the cell membrane, affecting signaling pathways[49−51] and altering intracellular free Ca2+ and ROS levels.[44,52] In addition, many papers have reported the effect on signaling pathways by direct binding of amyloids to cell membrane receptors.[52−55] we performed immunofluorescence assay with the GM1 and S100A9 specific fluorescently labeled antibodies using confocal microscopy and sensitized FRET analysis to evaluate the interactions between the membrane ganglioside GM1 and S100A9 amyloids produced after the 48 h incubation in the absence or presence of OleA. All results signify the roles of the amyloid−membrane interactions in triggering cellular toxicity and the importance of OleA in reducing cytotoxicity and perturbations of intracellular Ca2+ and ROS levels induced by S100A9 amyloids

■ CONCLUDING REMARKS

■ METHODS

■ REFERENCES

■ ACKNOWLEDGMENTS