TNFα- and IL-17A-mediated S100A8 expression is regulated by p38 MAPK.

The antimicrobial peptide S100A8 is known to be upregulated in lesional psoriatic skin compared with non-lesional psoriatic skin and is believed to play a role in the pathogenesis of psoriasis. However, little is known about the signalling pathways involved in the regulation of S100A8 expression. Using quantitative real-time RT-PCR analysis, we demonstrated that stimulation with TNFα and IL-17A in combination resulted in a significant and synergistic induction of S100A8 mRNA in human keratinocytes.