IL17A and psoriasis: Innate immune cells, such as macrophages, neutrophils, and dendritic cells activated by TNF-α and IL-23, modulate functions of adaptive effector cells like Th17 cells in psoriasis secreting IL-17 family of cytokines [4], which in turn induce the activation of keratinocytes and the production of anti-microbial peptides, CXCL10, CCL5, CXCL8, and TNF-α [5].