IL17A and psoriasis: Multiple types of pro-inflammatory cytokines and chemokines have been linked with the pathological development of psoriasis, including Th1 cell-related cytokines IFN-γ and IL-12; Th17 cells associated cytokines IL-17, IL-22, and IL-23; and other pro-inflammatory cytokines such as IL-1β, IL-6, and TNF-α that promote the acute stage of inflammatory responses, or the chemokines that regulate neutrophil chemotaxis, such as IL-8/CXCL8.