Proteomic Analysis of Corpora Amylacea Extracted From Post‐mortem Brain of MAiD‐end‐of‐life Sporadic ALS Patients

PURPOSE: Corpora amylacea (CA) are starch-like inclusions that accumulate in the central nervous system (CNS) with aging and are enriched in neurodegenerative conditions, including amyotrophic lateral sclerosis (ALS). Although often regarded as waste reservoirs, their cellular origins, molecular composition, and pathological significance remain poorly understood. METHODS: Here, we performed an unbiased proteomic analysis of purified CAs isolated from post-mortem brains of sporadic ALS patients and controls. FINDINGS: In-depth mass spectrometry identified 4,470 proteins, of which 658 were quantified, revealing distinct ALS-specific proteomic signatures. Enriched proteins included markers of cytoskeletal remodeling, mitochondrial dysfunction, and proteostasis disruption, as well as known ALS-associated proteins such as TDP-43 and neurofilament proteins. These findings demonstrate that CAs serve as reservoirs of dysfunctional, disease-relevant proteins and capture key pathological processes in ALS. CONCLUSION: By applying an unbiased proteomic approach to purified CAs, this study provides the first comprehensive map of their protein content in ALS, supporting their potential as biomarker sources and as a source of mechanistic insights into neurodegeneration. SIGNIFICANCE: Unbiased analyses of CAs in the context of ALS have yet to be undertaken. This study provides the first proteomic profiling of purified CAs, isolated from ALS patient brains using biochemical methods, revealing that CAs harbor disease-relevant proteins implicated in sporadic ALS. By demonstrating that CAs act as reservoirs of dysfunctional proteins related to metabolism, cytoskeletal organization, and proteostasis, our findings highlight their potential as a novel source of ALS-specific mechanistic insight into disease pathology.