IL17A and Alzheimer disease: PSO is primarily characterized by dysregulation of the IL-17/23 axis and a disordered T helper (Th)1/Th17 cell-mediated immune response, in stark contrast to the inflammatory profile of AD, which is driven by dysregulation of the IL-4/IL-13 axis and a Th2/Th17/Th22 cell-mediated response.