APOE and Alzheimer disease: Despite human AD brain analysis finding no significant differences between ApoE4 carriers and non-carriers concerning the number of reactive astrocytes [51], studies on ApoE4-TR mice and AD mouse models carrying the human ApoE4 isoform showed increase in reactive astrocytes and microglia [181,185,197], as well as increased levels of pro-inflammatory cytokines and greater synaptic protein loss, after LPS injection [181,197].