APOE and neurodegenerative disease: A subsequent study further confirmed that the activation of TREM2-APOE signaling pathways in DAM is essential for the switch of homeostatic microglia to DAMs during the pathogenesis of various neurodegenerative diseases including AD, amyotrophic lateral sclerosis (ALS) and multiple sclerosis (MS) (Krasemann et al., 2017).