CCL20 and Alzheimer disease: Because AD pathogenesis involves dysregulation of multiple types of Th cells, qPCR was performed to detect the expression of inflammatory cytokines associated with Th2 (IL-13, IL-4, and IL-4R), Th17 (IL-17A, CCL20, and MMP12), and Th1 (TNF-α and IFN-γ) cells.