Anti-inflammatory activity of a water extract of Acorus calamus L. leaves on keratinocyte HaCaT cells

Acorus calamus L., sweet flag, is a well-known medicinal plant that grows worldwide wildly along swamps, rivers, and lakes. The aim of this study was to evaluate the anti-inflammatory activity of Acorus calamus leaf (ACL) extract and to explore its mechanism of action on human keratinocyte HaCaT cells. HaCaT cells treated with polyinosinic:polycytidylic acid (polyI:C) and peptidoglycan (PGN) induced the inflammatory reactions. The anti-inflammatory activities of ACL were investigated using RT-PCR, ELISA assay, immunoblotting, and immunofluorescence staining. HaCaT cells induced the pro-inflammatory cytokines, interleukin-8 (IL-8) and/or interleukin-6 (IL-6) expressions after treatment with polyI:C or PGN. ACL inhibited the expression of IL-8 and IL-6 RNA and protein levels, and attenuated the activation of NF-κB and IRF3 after polyI:C treatment. ACL also inhibited expression of IL-8 and activation of NF-κB following PGN induction. These results suggest that ACL inhibits the production of pro-inflammatory cytokines through multiple mechanisms and may be a novel and effective anti-inflammatory agent for the treatment of skin diseases.