APOE4 Association with TDP-43 Pathology in Alzheimer's Disease Protocol
Phase 1: Patient Cohort Recruitment and Sample Collection (Days 1-30)
Cohort Assembly: Recruit AD patients (n=120, ages 60-85, NINCDS-ADRDA criteria) and age-matched cognitively normal controls (n=60) from memory clinics. Genotype APOE (ε2/ε3/ε4 status) via PCR-RFLP or TaqMan assay. Stratify into APOE4+ (≥1 ε4 allele, n~60) and APOE4- (ε3/ε3, n~60) AD groups plus APOE4- controls (n~40).
CSF Collection: Perform lumbar puncture (LP) at baseline (25G Sprotte needle, 12 mL CSF, slow withdrawal). Centrifuge at 800×g (10 min, 4°C) within 1 hour. Aliquot into 0.5 mL fractions, store at -80°C. Exclude samples with >500 erythrocytes/μL or signs of blood contamination.
...APOE4 Association with TDP-43 Pathology in Alzheimer's Disease Protocol
Phase 1: Patient Cohort Recruitment and Sample Collection (Days 1-30)
Cohort Assembly: Recruit AD patients (n=120, ages 60-85, NINCDS-ADRDA criteria) and age-matched cognitively normal controls (n=60) from memory clinics. Genotype
APOE (ε2/ε3/ε4 status) via PCR-RFLP or TaqMan assay. Stratify into APOE4+ (≥1 ε4 allele, n~60) and APOE4- (ε3/ε3, n~60) AD groups plus APOE4- controls (n~40).
CSF Collection: Perform lumbar puncture (LP) at baseline (25G Sprotte needle, 12 mL CSF, slow withdrawal). Centrifuge at 800×g (10 min, 4°C) within 1 hour. Aliquot into 0.5 mL fractions, store at -80°C. Exclude samples with >500 erythrocytes/μL or signs of blood contamination.
Neuroimaging: Obtain 3T MRI (T1 MPRAGE, T2 FLAIR, GRE) within 2 weeks of CSF collection. Rate medial temporal atrophy (MTA scale 0-4) and global cortical atrophy (GCA). Process via FreeSurfer for hippocampal volume and cortical thickness measures.
Neurodegeneration-biomarker-analysis--days-31-60" style="color:#4fc3f7;margin:1.5rem 0 0.6rem;font-size:1.15rem;font-weight:700;border-bottom:2px solid rgba(79,195,247,0.3);padding-bottom:0.3rem">Phase 2: TDP-43 and Neurodegeneration Biomarker Analysis (Days 31-60)
CSF Biomarker Measurement: Assay TDP-43 species via ELISA (Fujirebio #NR-25341 for total TDP-43, phospho-TDP-43 #NR-25342). Measure tau/Aβ42 ratio (INNOTEST, Fujirebio). Run all samples in duplicate with internal QC standards (low/medium/high pools). Technicians blinded to APOE/genotype.
蛟Fractionation for TDP-43 States: Separate soluble vs. insoluble TDP-43 via high-salt extraction (50 mM Tris, 750 mM NaCl, 1% Triton X-100) followed by urea extraction (7M urea). Probe fractions via western blot with pan-TDP-43 (1:1000, Proteintech #10782-2-AP) and phospho-TDP-43 (1:500, Cosmo Bio #TIP-PTD-P01).
APOE4 Effects on TDP-43 Aggregation: For mechanistic arm, incubate recombinant TDP-43 (0.5 mg/mL) with APOE4 or APOE3 lipoproteins (10 μg/mL) in physiological buffer (37°C, 7 days). Assess aggregate formation via Thioflavin T fluorescence and filter trap assay.
Phase 3: Neuropathological Correlation (Days 61-90)
Autopsy and Tissue Processing: For cases coming to autopsy (target n=30), collect fresh frozen brain tissue (dorsolateral prefrontal cortex, DLPFC; hippocampus) and fixed tissue blocks. Sample Brodmann area 46/9 from DLPFC and hippocampal CA1.
Immunohistochemistry: Stain for phospho-TDP-43 (pS409/410, 1:2000, Cosmo Bio) using standard DAB protocol. Score burden semiquantitatively (0: none, 1: sparse, 2: moderate, 3: frequent, 4: dense). Include TDP-43 inclusion morphology (neuronal cytoplasmic, glial, neuritic).
Co-localization Studies: Double-label TDP-43 with APOE (1:200, Abcam #ab1904) to assess APOE-TDP-43 physical proximity via confocal microscopy. Use proximity ligation assay (PLA) to detect direct APOE-TDP-43 interaction in situ.