TREM2 and Alzheimer disease: To further investigate the relationship between microglia and NP tau pathology, we conducted studies in which 5XFAD × TREM2−/−, 5XFAD × TREM2+/− and 5XFAD × TREM2+/+ mice on identical genetic backgrounds (Additional file 1: Fig. S1) received AD-tau injections.