1,6-O,O-Diacetylbritannilactone Inhibits Eotaxin-1 and ALOX15 Expression Through Inactivation of STAT6 in A549 Cells

1,6-O,O-Diacetylbritannilactone (OODBL), a plant sesquiterpene lactone, was previously reported to show multiple pharmacological effects such as anti-cancer and anti-inflammatory activities. In this study, we investigated the anti-inflammatory effect of OODBL on interleukin (IL)-4-induced signal transducer and activator of transcription 6 (STAT6) signaling pathway in human lung A549 cells. We found that OODBL dramatically inhibited IL-4-induced messenger RNA (mRNA) expression of eotaxin-1 and arachidonate 15-lipoxygenase-1 (ALOX15) in a dose-dependent manner. To clarify the action mechanism of OODBL, we examined the effect of OODBL on activation of STAT6. OODBL decreased both STAT6 phosphorylation and reporter gene activity. Furthermore, OODBL suppressed phosphorylation of Janus Kinase 3 (JAK3) without affecting JAK1. Taken together, OODBL abolished IL-4-induced eotaxin-1 and ALOX15 mRNA expressions by repressing the activation of STAT6 and JAK3. These results suggest that OODBL has a potential therapeutic efficacy on inflammatory diseases especially allergic airway disease as a lead compound.