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Mapping the Spatial Distribution of Fibrillar Polymorphs in Human Brain Tissue
Abdullah Al Bashit1, Prakash Nepal2, Theresa Connors3
1Department of Electrical and Computer Engineering, Northeastern University, Boston, MA, United States.
Frontiers in Neuroscience
|June 20, 2022
Summary
Scanning X-ray Microdiffraction (XMD) maps fibrillar polymorphs of amyloid-beta and tau in Alzheimer's disease brain tissue. This technique reveals distinct structural differences, offering new insights into disease progression mechanisms.
Area of Science:
- Neuroscience
- Biophysics
- Pathology
Background:
- Alzheimer's disease (AD) involves progressive aggregation of Aβ peptide and tau protein into polymorphic fibrils.
- Different fibril structures correlate with distinct neuropathologies and disease trajectories.
- Understanding aggregate spread mechanisms is crucial for AD research.
Purpose of the Study:
- To develop and demonstrate a method for mapping fibrillar polymorph distribution in situ within human brain tissue.
- To differentiate between Aβ and tau fibril polymorphs using their unique scattering signatures.
Main Methods:
- Utilized scanning X-ray Microdiffraction (XMD) on histological thin sections of human brain tissue.
- Correlated XMD data with immunohistochemistry on serial sections for anatomical context and interpretation.
- Analyzed scattering patterns, specifically the 4.7 Å cross-β peak and intensity distributions.
Main Results:
- XMD successfully mapped the locations of Aβ and tau fibrillar polymorphs in situ.
- Aβ-rich lesions showed characteristic scattering patterns consistent with known high-resolution structures.
- Tau-rich lesions exhibited distinct scattering intensity distributions compared to Aβ, despite a shared 4.7 Å cross-β peak.
Conclusions:
- XMD is a powerful tool for analyzing fibrillar polymorph distribution in diseased brain tissue.
- This technique provides spatially resolved information, overcoming limitations of microscopy and isolated fibril analysis.
- Combined with neuropathology, XMD offers novel insights into AD progression and the role of fibril polymorphism.
