Similarly, elevated expression of TLR2 and TLR4 in peripheral blood mononuclear cells (PBMCs) was found in AD patients compared to healthy control subjects (Zhang et al., 2012), and sustained TLR2 activation has been suggested to positively contribute to the neuroinflammation and Aβ accumulation (McDonald et al., 2016). Here, TLR2 is linked to Alzheimer disease.