Spatial proximity to AD pathology defines cell-type and genotype-specific characteristics in human AD hippocampus

Abstract

How amyloid-{beta} (A{beta}) plaques and tau phosphorylation spatially relate to cell response and genetic variation in Alzheimer's disease (AD) brain is currently unclear. We established a pipeline to concurrently annotate A{beta} and AT8 ptau pathology and cell-specific MERFISH expression profiles in human control and AD hippocampus. We characterized expression signatures in glia and neurons proximal or distal to A{beta} plaques, AT8 ptau-enriched neurons, or A{beta} and AT8 ptau in combination, and used spatially-defined transcriptional signatures to infer pathology-associated states in large snRNA-seq datasets lacking spatial context. We characterized variants from 120 gene loci associated with AD risk that affect cell-specific gene expression within local pathological contexts. Astrocyte APOE4/E4 expression was specifically suppressed in proximity to A{beta} plaques, whereas other APOE genotypes were unaffected by A{beta} proximity. Together, this analysis pipeline couples expression profiles in proximity to A{beta} and tau pathology, and implicates AD cis-gene variants with spatial sensitivity to AD pathology.