Higher CSF sTREM2 and microglia activation are associated with slower rates of beta-amyloid accumulation

Author(s): Ewers, M; Biechele, G; Suárez-Calvet, M; Sacher, C; Blume, T; Morenas-Rodriguez, E; Deming, Y; Piccio, L; Cruchaga, C; Kleinberger, G; Shaw, L; Trojanowski, JQ; Herms, J; Dichgans, M; Alzheimer's Disease Neuroimaging Initiative (ADNI); Brendel, M; Haass, C; Franzmeier, N;
Year: 2020;  
Journal: EMBO molecular medicine;  
Volume: 12;  
Issue: 9;  

Microglia activation is the brain’s major immune response to amyloid plaques in Alzheimer’s disease (AD). Both cerebrospinal fluid (CSF) levels of soluble TREM2 (sTREM2), a biomarker of microglia activation, and microglia PET are increased in AD; however, whether an increase in these biomarkers is associated with reduced amyloid-beta (Aβ) accumulation remains unclear. To address this question, we pursued a two-pronged translational approach. Firstly, in non-demented and demented individuals, we tested CSF sTREM2 at baseline to predict (i) amyloid PET changes over ∼2 years and (ii) tau PET cross-sectionally assessed in a subset of patients. We found higher CSF sTREM2 associated with attenuated amyloid PET increase and lower tau PET. Secondly, in the AppNL-G-F mouse model of amyloidosis, we studied baseline 18 F-GE180 microglia PET and longitudinal amyloid PET to test the microglia vs. Aβ association, without any confounding co-pathologies often present in AD patients. Higher microglia PET at age 5 months was associated with a slower amyloid PET increase between ages 5-to-10 months. In conclusion, higher microglia activation as determined by CSF sTREM2 or microglia PET shows protective effects on subsequent amyloid accumulation.