Likewise, microglia, the brain-resident immunocompetent macrophages, also recognize Aβ oligomers via receptors such as CD36, toll-like receptor 4 (TLR4) and TLR6 and triggering receptor expressed on myeloid cells 2 (TREM2), acquiring specific AD-associated phenotypes [14,15,16]. Here, TLR4 is linked to Alzheimer disease.