IL17A and Alzheimer disease: In the pathogenesis of AD, the balance between Th1 cell cytokines (IFN-γ, IL-12, and TNF-α), Th2 cytokines (IL-4, IL-6, IL-10, IL-13, and IgE), and Th17 cytokines (IL-17 and IL-22) is known to regulate inflammatory responses in the skin.