Docosahexaenoic acid remodels lipid composition of lipid rafts and mitochondrial function in ApoE4/4 mouse brain: a multi-omic investigation

Alzheimer's disease (AD) is an irreversible neurodegenerative disorder lacking curative therapies, with ApoE4 as the strongest genetic risk factor driving lipid dyshomeostasis and neuronal damage in the central nervous system. Lipid rafts, cholesterol- and sphingolipid-rich membrane microdomains, govern key neuronal signalling, and dysfunction of these microdomains mediates the progression of preclinical pathological lesions in ApoE4 carriers. Dietary docosahexaenoic acid (DHA) is widely reported to mitigate brain lipid disorders, yet how DHA remodels subfractions of lipid raft and non-raft membrane domains to rescue ApoE4-related energy metabolism disorder remains unclear. Most existing studies have only quantified total brain lipids without distinguishing membrane subdomains, and few characterized the liver-brain metabolic axis underlying ApoE4-associated neurodegeneration. We constructed female ApoE3/3 and ApoE4/4 knock-in mice with 6- and 12-month DHA dietary interventions, combining behavioral, histological, lipidomic and proteomic assays to characterize genotype-specific lipid remodelling and downstream mitochondrial changes. Here we show that ApoE4 mice develop severe hepatic steatosis, neuroinflammation and lipid raft rigidification characterized by elevated sulfatides and ceramides levels, DHA upregulates Lpin1, Atgl and nSMase2 while suppressing Acer3 and Sgms2, thereby rebalancing lipids raft and restoring mitochondrial bioenergetics. Our work resolves raft and non-raft lipid profiles in ApoE humanized mice, and links peripheral hepatic metabolic disturbances to cerebral membrane microdomain dysfunction. These multi-omics mechanistic findings advance genotype-specific preventive nutritional strategies for ApoE4 carriers and reveal potential subcellular lipid targets for early AD intervention.