Plasma exchange with albumin replacement for Alzheimer's disease treatment induced changes in serum and cerebrospinal fluid inflammatory mediator levels.

Objective: There is extensive literature indicating that inflammatory pathways are affected in Alzheimer's disease (AD). We examined whether plasma exchange with albumin replacement (PE-Alb) can impact the inflammatory status of AD patients and alter the relationship between inflammatory mediators and cognitive measures.

Methods: Serum and cerebrospinal fluid (CSF) samples from 142 AD patients participating in the AMBAR trial (14-month schedule of PE-Alb treatment vs. placebo [sham PE-Alb]) were analyzed for changes from baseline for 19 inflammatory mediators (6 inflammatory cytokines, 9 chemokines, and 4 vascular injury indicators) at representative time points across the AMBAR study (lasting effects) as well as in pre- versus post-PE-Alb procedure (acute effects). Association between mediator changes and clinical outcomes reported in the AMBAR study (cognitive, functional, behavioral function, and global change tests) was assessed.

Results: PE-Alb significantly reduced IFN-γ, eotaxin, MIP-1α and ICAM-1 levels in serum, and eotaxin-3 and MIP-1β levels in CSF, at various time points during treatment (p < 0.05; false discovery rate-corrected). Vascular injury indicators were the mediators mostly affected by post- versus pre-PE-Alb level reduction. Increased serum MIP-1α levels were associated with worsening in ADAS-Cog, CDR-sb, and ADCS-CGIC scores in the placebo group, but not in the PE-Alb-treated group.

Interpretation: Peripheral intervention could affect AD by reducing inflammatory mediators in both peripheral and central compartments. Changes in MIP-1α due to PE-Alb were associated with changes in clinical outcomes.