The amyloid secreted by E.coli has a similar structure and immunogenicity to that of Aβ42, and can promote the release of pro-inflammatory factors by binding to the Toll-like receptors 2 (TLR2) on the surface of microglia and subsequently exacerbate the inflammatory response in the AD brain (Hill and Lukiw, 2015). This evidence concerns the gene TLR2 and Alzheimer disease.