Effect of clarithromycin on rhinovirus-16 infection in A549 cells

Clarithromycin (CM) has been found to inhibit the production of the intercellular adhesion molecule (ICAM)-1 and the secretion of interleukin (IL)-6 and IL-8, which may have beneficial effects on the pathophysiological changes related to rhinovirus (RV) infection. The effect of CM on RV infection in A549 cells was therefore investigated. Cells were pre-treated with 1, 10 or 100 microM CM, either starting 3 days before infection and continuing thereafter, or by addition at the time of infection. RV titre, as measured by culture on Medical Research Council 5 cells, was reduced by CM, with the degree of reduction being greater when CM was added 3 days before infection than when it was added at the time of infection. CM treatment inhibited the RV-induced increase in ICAM-1 mRNA and protein, as well as the RV-induced secretion of IL-1beta, IL-6, and IL-8. These effects were greater in cells treated with 10 microM than in those treated with 100 microM CM, and the maximum effect was observed 3 days after viral infection. In contrast, secretion of IL-8 was not inhibited significantly when CM was added at the time of viral infection. The findings of this study suggest that, in A549 cells, clarithromycin inhibits the induction of intercellular adhesion molecule-1 expression, cytokine elaboration, and viral infection.