TNF and psoriasis: To compare the effects of psoriasis-specific-cytokines with the effects of nucleic acids on IL-23 mRNA expression in keratinocytes, we used psoriasis-relevant cytokines, such as IL-17A, IL-12, TNF-α and IL-23, and synthetic nucleic acid analogues imiquimod (IMQ), poly(dA:dT) and poly(I:C), since these molecules have long been known to have a role in psoriasis pathogenesis.