In this mechanism, stimulated keratinocytes function as the trigger of psoriasis by secreting cytokines, chemokines, and antimicrobial peptides (AMPs) to activate DCs which secret multiple proinflammatory cytokines such as TNF-α, interleukin (IL)-6, IL-12, IL-23 and IL-36. The gene discussed is IL23A; the disease is psoriasis.