propose

# Mechanistic Hypotheses: Microglial OxPC Neutralization in MS

## 1. ApoE-Mediated Lipid Sequestration and Efflux

**Mechanism:** Microglia upregulate apolipoprotein E (ApoE) as a lipid shuttle to bind and sequester toxic OxPC species, then utilize ABCA1/ABCG1 transporters to efflux these complexes. ApoE's 2-3 helix domain directly coordinates the oxidized fatty acid tails of OxPCs, preventing them from inserting into neuronal/oligodendrocyte membranes. This creates a microglial "lipid sink" that protects vulnerable myelinating cells.

**Key Evidence:** Microglial ApoE expression is dramatically induced in MS lesions and surrounding white matter (PMID: 33603230), and ApoE directly binds oxidized phospholipids with micromolar affinity. ABCA1-dependent cholesterol efflux is the rate-limiting step for ApoE lipidation and function.

**Testable Prediction:** Conditional deletion of *Apoe* in microglia (CX3CR1-CreER; *Apoe* flox/flox) should cause OxPC accumulation in cerebrospinal fluid, accelerated oligodendrocyte loss, and impaired motor function in cuprizone or MOG-EM demyelination models compared to littermate controls.

**Target:** APOE (protein)

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## 2. Nrf2-ARE Transcriptional Activation of Antioxidant Detoxification Enzymes

**Me