Effect of the LKEKK Peptide on Human Keratinocytes

The LKEKK peptide (Np5) corresponding to the 16–20 sequence of thymosin-α 1 (TM-α 1 ) and to the 131–135 sequence of interferon-α 2 (IFN-α 2 ) and its [ 3 H]Np5 analog were synthesized. [ 3 H]Np5 was found to bond to human keratinocytes with high affinity and specificity ( K d 2.6 nM). Np5 dose-dependently decreased the inerleukin-17A-induced production of inflammatory cytokines (TNF-α, IL-6, and IL-1α) by keratinocytes in a concentration range from 50 to 1000 nM and increased a production of the anti-inflammatory IL-10 cytokine in vitro. The peptide effect was shown to be mediated through an activation of soluble guanylate cyclase.