IL4 and Alzheimer disease: They also observed that acute canine AD skin lesions exhibited substantial upregulation of genes encoding cytokines related to Th2 cells (e.g., IL-4, IL-5, IL-13, IL-31, and IL-33), Th9 cells (IL-9), and Th22 cells (IL-22) as well as the Th2-promoting chemokines, chemokine ligand (CCL)5 and CCL17 (31).