Figure 1.

Cytokine signaling pathways in the pathogenesis of psoriasis. Damage to the epidermal lining triggers release of antimicrobial peptides (AMP) such as LL-37, which complexes with self-DNA released from cellular membrane rupture. DNA-LL-37 complexes are autoantigens of psoriasis, which are taken up by melanocytes and dendritic cells, resulting in IL-23 production. The IL-23/IL-17 axis is activated in a feedforward loop that favors keratinocyte proliferation, eventually forming a psoriatic plaque. Schematic of lymph node (bottom left) shows the polarization of naïve T cells into Th1, Th17, and Tc17 cells by cytokine stimulation. (Key: Black arrows, uptake; Blue arrows, cytokine production; Green arrows, stimulation or activation; Red arrows, effect on epidermal keratinocytes).