TREM2 and microglia exosomes: a potential highway for pathological tau.

Tau pathology appears to spread along neuronal networks via the template misfolding of tau by pathological tau conformations. The mechanisms underlying neuron-to-neuron transmission of tau are unclear and recent work demonstrates a role for microglia in the spread of tau pathology. In this Commentary, we discuss a recent study that found that loss of TREM2 expression resulted in exacerbated spread of tau pathology that depended on microglial exosomes. These important findings highlight the role of the microglial endolysosomal system and TREM2 in the spread of tau pathology.