IL4 and Alzheimer disease: QRT-PCR analysis of skin tissue lysates showed that AD increased the expression levels of Th1 cytokines (IL-1β, IFN-γ, and TNF-α) and Th2 cytokines (IL-4, IL-5, IL-6, and IL-13), while decreasing the expression of IL-10, an immune suppressive cytokine, in an HDAC6-dependent manner (Supplementary Figure S1C).