Hypericum perforatum extract alters cytokine production by influenza A virus infected lung epithelial cells

Hypericum perforatum ethanol extract was shown to possess anti‐inflammatory activity. Influenza infection initiates an inflammatory response, in which cytokine secretion by respiratory tract epithelial cells play an important role. In the current study, we treated influenza‐infected A549 lung epithelial cells with H. perforatum ethanol extract and its previously identified anti‐inflammatory fractions, in order to measure the changes in cytokine production. The extract at 30 ¦Ìg/ml inhibited virus‐induced interferon‐¦Ã‐induced protein 10 kDa (IP‐10) and monocyte chemotactic protein‐1 (MCP‐1) production by over 90% and 70%, respectively, and increased interleukin 6 (IL‐6) by about 25% compared to vehicle control. Select fractions of the extract inhibited IP‐10, MCP‐1, and IL‐6, except that fraction 9 slightly increased MCP‐1. We also found that influenza‐induced suppressor of cytokine signaling 3 (SOCS3) expression, which has been shown to facilitate infection, was further elevated by H. perforatum extract and the combination of four of its constituents. In summary, cytokine secreted by epithelial cells after infection, especially MCP‐1 and IP‐10, were altered drastically by H. perforatum extract and its fractions. Whether these changes, together with potentiating SOCS3, would alleviate influenza‐induced pathogenesis or compromise early immune defense in vivo awaits further study. Grant Funding Source : P50 AT004155 NCAAM/ODS from NIH