Amiloride inhibits cytokine production in epithelium infected with respiratory syncytial virus

Abstract

Respiratory syncytial virus (RSV) is an important respiratory pathogen in infants and children. RSV preferentially infects airway epithelium and causes local production of inflammatory cytokines. Ribavirin, the only specific agent available for treatment of RSV infection, has limited effectiveness. There are few data regarding the ability of drugs to modulate the inflammatory response of epithelium infected with RSV. This study evaluated the effect of amiloride and ribavirin on cytokine production by RSV-infected epithelium. We observed a dose-dependent reduction in interleukin (IL)-8 protein release with both amiloride and ribavirin in RSV-infected A549 epithelial cells. Peak effects were observed at concentrations of 200 microM amiloride and 60 microM ribavirin. Both amiloride and ribavirin inhibited IL-8 mRNA induction. Pretreatment with either agent was not required to inhibit IL-8 release. Both drugs also inhibited IL-6 release. However, unlike ribavirin, amiloride did not inhibit viral replication or infection. Amiloride also inhibited IL-8 release from A549 cells stimulated with IL-1 or tumor necrosis factor. Amiloride similarly inhibited IL-8 protein release from primary human airway epithelium infected with RSV. These data demonstrate that both amiloride and ribavirin inhibit cytokine production in RSV-infected airway epithelium. These results suggest amiloride, as well as ribavirin, may be useful as a therapeutic agent in RSV infections.