Macrophages and PBMCs from AD patients treated with TLR2 ligands secrete less IL-6, IL-1β, IFN-γ, IL-12 and IL-22, but more IL-5 [51,52] TLR2 is normally expressed throughout the epidermis but is restricted to basal keratinocytes in AD [14]. Here, TLR2 is linked to Alzheimer disease.