TREM2 function impedes tau seeding in neuritic plaques.

Variants in the triggering receptor expressed on myeloid cells 2 (TREM2) have been associated with increased risk for sporadic, late-onset Alzheimer's disease. Here we show that germline knockout of Trem2 or the TREM2 ^R47H variant reduces microgliosis around amyloid-β plaques and facilitates the seeding and spreading of neuritic plaque tau aggregates. These findings demonstrate a key role for TREM2 and microglia in limiting the development of peri-plaque tau pathologies.