Administration of isoferulic acid improved the survival rate of lethal influenza virus pneumonia in mice

BACKGROUND: Isoferulic acid (IFA) is a main active ingredient of the rhizoma of Cimicifuga heracleifolia, which is used frequently in Japanese traditional medicine as an anti-inflammatory drug. It has been revealed that IFA inhibits the production of macrophage inflammatory protein-2 (MIP-2), which is a murine counterpart of the chemokine family that may contribute to the pathogenesis of inflammatory diseases through the chemotactic activity for inflammatory and immune effector cells. Aim of the study: In this study, we investigated the therapeutic effect of IFA on the progression of lethal influenza virus pneumonia in mice by comparison with that of dexamethasone (DX), a potent inhibitor for various inflammatory cytokines including MIP-2. Methods: Mice were infected by intranasal inoculation of influenza virus under ether anesthesia. The IFA or DX was given by oral administration once daily for 4 days after infection. After infection, the survival rate and the change in body weight were daily monitored. Results: IFA administration markedly improved the survival rate and body weight loss of influenza virus-infected mice in a suitable dose range (0.5 mg/day). However, DX administration did not show a beneficial effect at any dose. Conclusion: These data suggested that IFA is a novel tool not only for the intervention therapy, but also for the studies on the pathogenesis of influenza virus-induced pneumonia.