IL22 and Alzheimer disease: IL-22, a Th22 cytokine, is elevated in both acute and chronic AD, damaging the epidermal barrier by suppressing proteins relevant to the normal differentiation of the epidermis, increasing sensitization to antigens and promoting an exacerbated type 2 immune response, in addition to contributing to the pathogenesis of pruritus, by promoting pruritus-inducing cytokines.72