Compared with the control mice, the continuous application of IMQ to the dorsal skin of mice for 7 days significantly augmented the expression of interleukins (IL-1β and IL-23a), chemokines (CXCL1, CXCL2, CXCL10, and CCL20), and antimicrobial peptides (S100A8/9), all of which play a crucial role in the pathogenesis of psoriasis. This evidence concerns the gene CCL20 and psoriasis.