APOE4 Copy Number-Dependent Proteomic Changes in the Cerebrospinal Fluid.

Area of Science:

• Neuroscience
• Proteomics
• Genetics

Background:

• The apolipoprotein E4 (APOE4) genotype is a significant risk factor for Alzheimer's disease (AD).
• Neuroinflammation is a proposed mechanism linking APOE4 to increased AD risk, but specific pathways remain unclear.

Purpose of the Study:

• To investigate cerebrospinal fluid (CSF) proteomic alterations associated with APOE4 gene dosage.
• To identify specific neuroinflammatory markers affected by APOE4 in Alzheimer's disease.

Main Methods:

• Targeted proteomic analysis of CSF samples from the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort.
• Linear regression models were used to assess associations between APOE4 copy number and peptide levels, adjusting for covariates like age, sex, and clinical status.

Main Results:

• Increased APOE4 copy number correlated with decreased C-reactive protein (CRP) peptide levels.
• Significant increases in ALDOA, CH3L1 (YKL-40), and FABPH peptide levels were observed with higher APOE4 copy number, particularly when controlling for CSF Aβ levels.
• A potential inverse association between APOE4 and complement pathway proteins was noted, warranting further investigation.

Conclusions:

• APOE4 influences neuroinflammation by modulating CSF protein profiles, including CRP, ALDOA, CH3L1, and FABPH.
• The findings suggest that APOE4 may also impact the complement system, contributing to Alzheimer's disease pathogenesis.
• Further research is needed to elucidate the role of these protein changes in APOE4-associated neuroinflammation and AD risk.