MMP9 and psoriasis: IL-1 promotes T-cell responses with a key role for the differentiation of Th17 cells mediating autoimmune and chronic inflammatory diseases, such as psoriasis.29 Despite no much significant difference in inflammation, the expression of MMP-9, eotaxin-2, IL-4 and IL-13 was reduced in IL-1αβ−/− and IL-1R1−/− mice compared with BL6 after 12 days of MC903 application, which indicated IL-1R1 has minor role in MC903-induced AD.