Spatially resolved mass spectrometry for Amyotrophic Lateral Sclerosis neuropathology

Thesis

Lipids constitute 50% of the brain’s dry weight, with over 75% of all lipid species in the human body predicted to reside in the brain, yet their role in neurodegenerative diseases like Amyotrophic Lateral Sclerosis (ALS) remains poorly understood. Similarly, Betz cells, the largest cell in the human brain, displays selective vulnerability to ALS pathology, yet their lipid profile is entirely unexplored. A combination of Laser Capture Microdissection-Liquid Chromatography Tandem Mass Spectrometry (LCM-LC-MS/MS) and Matrix Assisted Laser Desorption Ionisation (MALDI) Imaging offers a powerful approach to achieve deep lipidomic insights with spatial resolution, mapping cell-type resolved lipid alterations onto the neuropathology of disease. Herein, optimisation and implementation of these methods are applied to a large cohort of human post-mortem brain tissue, revealing unprecedented lipidomic insights into ALS pathology and neuronal function in both health and disease. For the first time, single-cell spatially resolved lipidomic analysis of Betz cells and two additional large projection neurons involved in motor function- Purkinje cells, and Dentate Nuclei Neurons- which are traditionally considered to be relatively spared in ALS pathology, is demonstrated in post-mortem brain tissue from a large ALS cohort. The results highlight complementary strengths of LCM-LC-MS/MS and MALDI Imaging, demonstrate the capability of classifying cell types and disease states solely based on lipid profile, and uncover potential mechanisms of selective vulnerability in ALS. Key findings include the identification of dysregulated sphingolipid metabolism and altered membrane dynamics driven by a shift in lipid classes, lipid characteristics and biophysical properties, as contributors to Betz cell degeneration. These optimised workflows, offering excellent lipid depth and spatial resolution, provide a valuable framework for future large-scale cell-type specific and spatially resolved lipidomic studies of neurodegeneration.

Authors: Reese, J

• DOI: 10.5287/ora-qyqper5e2
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: spatially resolved mass spectrometry; neurodegeneration; single-cell analysis; human post-mortem brain; lipidomics; Motor Neuron Disease; Amyotrophic Lateral Sclerosis; MALDI Imaging; Laser capture microdissection (LCM); LC-MS/MS; selective vulnerability; Betz cells; mass spectrometry
• Subjects: Molecular biology; Neurons; LC-MS/MS; Mass spectrometry; Neuropathology; Lipidomics; Neurosciences; Laser Capture Microdissection; Neurobiology; Motor neurons; Amyotrophic lateral sclerosis; Nervous system--Diseases; Matrix-assisted laser desorption-ionization