IL23A and psoriasis: Taken together, type-I IFNs play a critical role in the acute/early phase of psoriasis pathogenesis by (1) activating dermal myeloid DC, (2) inducing their maturation by upregulating co-stimulatory molecules and HLA molecules, and (3) participating in TH/TC17 polarisation of autoimmune T-cells through induction of IL-23 production by myeloid DCs (Figure 1).