Ligand Profiling as a Diagnostic Tool to Differentiate Patient-Derived α-Synuclein Polymorphs.

Area of Science:

• Neuroscience
• Biochemistry
• Pathology

Background:

• Amyloid fibrils are hallmarks of neurodegenerative conditions like Alzheimer's and Parkinson's diseases.
• Distinct supramolecular morphologies of amyloid fibrils correlate with specific diseases, even when formed from the same protein.

Purpose of the Study:

• To develop and validate a method for distinguishing morphologically diverse amyloid fibrils based on ligand binding.
• To differentiate specific fibril polymorphs of alpha-synuclein (αSyn), including those derived from patient samples of Parkinson's disease (PD), multiple system atrophy (MSA), and dementia with Lewy bodies (DLB).

Main Methods:

• Investigated eight distinct αSyn fibrillar polymorphs (five de novo, three using protein misfolding cyclic amplification (PMCA) with patient-derived seeds).
• Employed fluorescence binding assays utilizing a panel of six different ligands.
• Classified fibril binding into binary categories (bound/not bound) and used quantitative measurements for unique identification.

Main Results:

• Successfully differentiated all eight αSyn fibrillar polymorphs based on unique ligand binding profiles.
• Unambiguously distinguished PMCA-derived fibrils from PD, MSA, and DLB patient samples.
• Demonstrated that ligand binding patterns can serve as a molecular signature for fibril morphology and disease association.

Conclusions:

• Developed an operationally simple and novel method to differentiate amyloid fibril morphologies.
• The ligand-binding approach enables the identification of disease states through the analysis of PMCA fibrils seeded with patient samples.
• This technique offers a promising tool for understanding the heterogeneity of amyloid diseases and for diagnostic applications.