TLR9 and Alzheimer disease: Several studies of postmortem brain tissues from AD patients and transgenic AD-model mice have found augmented expression levels of TLR-2, TLR-4, TLR-5, TLR-7 and TLR-9 as well as of the TLR co-receptor CD14, in microglia localized around senile plaques [190,191,192,193].