Casuarinin suppresses TARC/CCL17 and MDC/CCL22 production via blockade of NF-κB and STAT1 activation in HaCaT cells.

Casuarinin is a naturally occurring tannin that is isolated from the leaves of Hippophae rhamnoides. It has been shown to have anti-oxidant, anti-cancer, anti-viral, and anti-inflammatory activities. The aim of this study was to investigate the possible mechanism by which casuarinin inhibits TNF-α/IFN-γ-induced Th2 chemokines expression in the human keratinocytes cell line HaCaT. We found that casuarinin suppressed TNF-α/IFN-γ-induced expression of TARC and MDC mRNA and protein in HaCaT cells. Casuarinin significantly inhibited TNF-α/IFN-γ-induced activation of NF-κB, STAT1, and p38 MAPK. Furthermore, we observed that p38 MAPK contributes to inhibition of TNF-α/IFN-γ-induced TARC and MDC production by blocking NF-κB and STAT1 activation in HaCaT cells. Taken together, these results suggest that casuarinin may exert anti-inflammatory responses by suppressing TNF-α/IFN-γ-induced expression of TARC and MDC via blockage of p38 MAPK activation and subsequent activation of NF-κB and STAT1. We propose that it could therefore be used as a therapeutic agent against inflammatory skin diseases.