APP and Alzheimer disease: IL-18 synthesis was demonstrated in different brain regions, mainly at the level of activated microglia; moreover, IL-18 was shown to be increased in the brains of AD patients [16], and in addition, IL-18 was shown to increase amyloid-β production by human neuron-like cells [17] affecting amyloid precursor protein (APP) processing and therefore, Aβ production [18].