MDK and inflammatory skin disease: We found 12 candidate common extracellular biomarkers for all inflammatory skin diseases as follows: ACR (acrosin), APOE (apolipoprotein E), ASIP (agouti signalling protein), CRISP1 (cysteine rich secretory protein 1), DKK1 (dickkopf WNT signalling pathway inhibitor 1), IL12B (interleukin 12B), IL9 (interleukin 9), MANF (mesencephalic astrocyte derived neurotrophic factor), MDK (midkine), NRTN (neurturin), PCSK5 (proprotein convertase subtilisin/kexin type 5), and VEGFC (vascular endothelial growth factor C) (Table 2).