Role of Apolipoprotein E in Alzheimer's Disease Pathogenesis, Prognosis and Treatment

Alzheimer's disease (AD) is an incurable and progressive neurodegenerative disease with increasing prevalence worldwide. Previous trials of anti-amyloid and anti-tau immunotherapy indicate that additional research needs to be conducted on other mechanisms to find curative or disease-modifying therapy. This review focuses on apolipoprotein E (ApoE), a critical protein in brain lipid metabolism that acts specifically in the clearance and transport of lipids and cholesterol. The ApoE4 allele confers substantial gene dose-dependent risk of developing AD and lowers the age of onset of AD, although the mechanisms of influence remain incompletely understood. The other isoforms bring different levels of AD risk. ApoE2 is protective while ApoE3 is the most common isoform and is considered neutral. An overview is presented of the latest information on the role of ApoE in AD pathogenesis with an emphasis on pathways that are involved in AD development and interactions with crucial processes in different cell types in the brain. Elucidating the key interactions of ApoE with multiple aspects of brain function can be useful for designing novel ApoE-targeted therapeutic approaches.