Theorist position for analysis db9a224d-3ebb-429c-8f02-b703d71ca211: Non-Neuronal Transcriptional Changes Preceding Tau Propagation as Early AD Biomarkers
Source basis: Single-cell spatial transcriptomics reveals distinct patterns of dysregulation in non-neuronal cell types in Alzheimer's disease (Molecular Psychiatry, 2025, DOI 10.1038/s41380-024-02651-0). The stored gap context says: Spatial transcriptomics identified non-neuronal dysregulation patterns in AD; the temporal ordering of non-neuronal changes relative to tau spread was identified as a key open question.
Primary hypothesis: APOE ε4-driven microglial lipid handling is not merely an associated signature; it is a testable mechanism that can explain the open question: Which non-neuronal cell types (astrocytes, oligodendrocytes, pericytes) exhibit transcriptional changes in the entorhinal cortex that precede tau propagation to hippocampus and neocortex in AD, and can single-nucleus RNA-seq from cognitively normal APOE ε4 carriers identify these as pre-clinical biomarkers?
Three candidate claims should be carried forward. First, the strongest causal signal should appear in the cell type or tissue compartment named by the question, not only in bulk disease contrasts. Second, perturbing the axis should shift a proximal molecular phenotype before it shifts a late pathology phenotype, which would help separate cause from consequence. Third, the relevant readout should be stratified by RNA-, APOE, because collapsing across those terms would erase the mechanism the analysis is trying to test.
The priority experiment is isogenic APOE3/APOE4 microglia co-cultured with amyloid-bearing neurons, lipidomics, and phagocytosis/degradation assays. A positive result would require concordance across human observational data, disease-relevant cellular models, and at least one perturbation that moves the predicted proximal readout in the expected direction.