Apolipoprotein E4‐driven effects on inflammatory and neurotrophic factors in peripheral extracellular vesicles from cognitively impaired not demented participants converted to Alzheimer’s disease

다국어 초록 (Multilingual Abstract)

In brain, extracellular vesicles (EVs) play an essential role in neuron‐glia interface and ensure the crosstalk between the brain and the periphery. Only a few studies have demonstrated the apolipoprotein E4 variant (APOE ε4)‐driven dysfunction of EVs pathway and the risk to develop Alzheimer’s disease (AD). To better understand the role of APOE ε4 in pre‐clinical AD, we determined levels of pathogenic, neurotrophic and inflammatory proteins in peripheral EVs (pEVs) and in plasma from cognitively impaired‐not demented (CIND) participants stratified upon the absence (APOE ε4‐) or the presence (APOE ε4+) of the ε4 allele of APOE.
Levels of 15 neurodegenerative, neurotrophic and neuroinflammatory proteins were quantified in pEVs by the multiplex Luminex assay and compared to their plasma levels from cognitively normal and CIND participants
For the first time, several neurotrophic and inflammatory markers including LCN‐2, S100B, ANGPTL‐4, NPTX‐2 and α‐synuclein were evidenced in pEVs. Some proteins such as α‐Syn, NPTX‐2 and S100B were enriched in pEVs as compared to plasma. APOE ε4+ was associated with differential regulation of 7 markers and compromised the release of pEVs formed by an endosomal route. The pentraxin‐2/α‐synuclein ratio measured in pEVs was able to predict AD 5 years before the onset among APOE ε4+ CIND individuals. Discussion: Our findings suggest an alteration of the endosomal pathway in APOE ε4+ carriers and that pEVs pentraxin‐2/α‐synuclein ratio could serve as a useful early biomarker for AD susceptibility.
The findings reported herein provide a comprehensive insight and enhance our knowledge on the emerging role of ApoE4 in abnormal pEVs cargo proteins processing and the identification of blood‐based biomarkers.