(17) discovered that exosomes derived from keratinocytes treated with psoriasis cytokines (IL-17A, IL-22, IFN-γ, TNF-α) can induce the differentiation of CD4-positive T-cells into Th1 and Th17 cells and upregulate the expression of various cytokines including IL-17A, IL-17F, IL-22, IL-23, IL-36, IFN-γ, and TNF-α. The gene discussed is IL17A; the disease is psoriasis.