Expression of S100A8 and S100A9 in keratinocytes is closely associated with markers of inflammation in murine and human psoriasis and keratinocytes are essential cellular mediators for the initiation and maintenance of this disease by secreting leukocyte-attracting chemokines like CXCL1, CCL20, and other inflammatory molecules like TNFα or IL-6 (1, 54). Here, S100A9 is linked to psoriasis.