Bafilomycin A₁ inhibits rhinovirus infection in human airway epithelium: Effects on endosome and ICAM-1

To examine the effects of bafilomycin A₁, a blocker of vacuolar H⁺-ATPase, on rhinovirus (RV) infection in the airway epithelium, primary cultures of human tracheal epithelial cells were infected with RV14. Viral infection was confirmed by showing that viral RNA in the infected cells and the viral titers in the supernatants of infected cells increased with time. RV14 infection upregulated the production of cytokines and mRNA of intercellular adhesion molecule (ICAM)-1 in epithelial cells. Bafilomycin A₁ reduced the viral titers of RV14 and inhibited the production of cytokines and ICAM-1 before and after RV14 infection. Bafilomycin A₁ reduced susceptibility of epithelial cells to RV14 infection. RV14 increased activated nuclear factor-κB in the cells, and bafilomycin A₁ reduced the activated nuclear factor-κB. Bafilomycin A₁ decreased the number of acidic endosomes in the epithelial cells. These results suggest that bafilomycin A₁ may inhibit infection by RV14 by not only blocking RV RNA entry into the endosomes but also reducing ICAM-1 expression in the epithelial cells. Bafilomycin A₁ may therefore modulate airway inflammation after RV infection.