Although our results here and from other published studies implicate an active role for microglia activation in aggravating tauopathy, the question remains why microglia depletion in some instances, for example in 5xFAD mouse brain with AD-tau injection, can also aggravate tau pathology [21], while other studies that show reduction in tau pathology in PS19 mouse brain with microglia depletion [2]. Here, MAPT is linked to Alzheimer disease.