Human iPSC models reveal APOE4-induced microglial remodeling and extracellular vesicle dysregulation in AD pathogenesis
Year: 2026
Type: preprint
Abstract: The apolipoprotein E ε4 ( APOE4 ) allele is the strongest genetic risk factor for late-onset Alzheimer’s disease (AD), yet the mechanistic underpinnings by which it alters human microglial function remain poorly understood. Here, we utilize CRISPR/Cas9-engineered isogenic human induced pluripotent stem cell-derived microglia-like cells (iMGs) expressing APOE3 or APOE4 to systematically interrogate genotype-dependent effects on microglial proteomes and their secreted extracellular vesicles (EVs) under basal and fibrillar amyloid-β (fAβ)-challenged conditions. Quantitative proteomics revealed that APOE4 iMGs exhibit downregulated RNA processing, impaired phagocytosis, and exacerbated pro-inflammatory signaling, particularly upon fAβ exposure. Functionally, APOE4 iMGs demonstrated increased NF-κB activation, enhanced neuronal apoptosis and tau pathology in 2D and 3D co-culture systems. Interestingly, APOE4 iMGs released greater amount of EVs enriched in proteasomal components over APOE3 iMG. Integrated proteomic analyses further highlighted APOE4 -specific selective packaging of EV cargo linked to neuron-glia communication, inflammatory signaling, and proteostasis dysregulation, suggesting a potent, non-cell-autonomous mechanism driving neuronal damage. Consistently, these APOE4 iMGEVs were preferentially internalized by neurons, leading to disrupted neuronal proteostasis, impaired neuronal firing, and increased tau phosphorylation, particularly under pathological stress. Notably, pharmacologic inhibition of NF-κB in APOE4 iMGs reduced EV cargo-loading of proteasomal molecules and mitigated iMGEV-driven neuronal dysfunction and tau pathology. These findings establish a mechanistic link between APOE4 , dysregulated microglial homeostasis, and microglial EV-mediated propagation of proteostatic dysfunction and neurodegeneration, advancing our understanding of how APOE4 contributes to AD pathogenesis.
Source: Research Square
Language: English
Subfield: Physiology
Field: Medicine
Domain: Health Sciences
Open Access status: green
Awards: Role of ITGB1 enriched astrocyte-specific EVs in tau pathology, G4704345230, G6121715552, Targeting emerging P2RX7 signaling pathways in animal models of Alzheimer's disease, Targeting the miR-155 and APOE-TREM2 pathways to restore dysfunctional microglia in Alzheimerâs disease, Molecular characterization of extracellular vesicles for the spread of misfolded tau protein, Assessment of a novel tau propagation pathway from layer II medial entorhinal cortical neurons to CA1 pyramidal neurons as an early Braak stage mouse model, APOE and microglia-mediated progression in tau pathology in AD, Alzheimer's Disease Research Center, Microglia targeted interventions in prodromal Alzheimer's disease stage, Elucidating endolysosomal trafficking dysregulation induced by APOE4 in human astrocytes, Therapeutic evaluation of targeting Tau Tubulin kinase-1 in Alzheimer’s disease, Biology and pathobiology of apoE in aging and Alzheimer's disease
OpenAlex ID: W7212133720