Type-specific induction of interleukin-8 by adenovirus

Infection with adenovirus (Ad) causes acute pneumonia in a type-specific fa shion because type 7 but not type 5 Ad has been isolated as a causative age nt. We postulated that the type specificity of induction of pneumonia may b e related to type-specific cytokine induction in lung cells. To test this h ypothesis, we infected human fetal lung fibroblasts and the lung epithelial cell line A549 with live type 5 and type 7 Ad. Virus inactivated by irradi ation was used as a control. Type 7 but not type 5 Ad induced interleukin ( IL)-8 protein production in both cell types in a dose- and time-dependent m anner. Inactivated virus had no effect on the production of IL-8 protein. T ype 7 but not type 5 virus also stimulated IL-8-specific messenger RNA (mRN A) production in these cells. Because half-life of IL-8 mRNA was prolonged in both type 5 and type 7-infected A549 cells, induction likely involves en hancement of message stability as well as other effects. Virus early gene e xpression did not consistently correlate with IL-8 message induction and fo llowed induction in fibroblasts. These results suggest that there is type-s pecific induction of IL-8 production during infection of lung cells with Ad . Induction involves message stabilization and may not require viral gene e xpression. Because IL-8 is one of the important mediators of lung inflammat ion, type-specific induction of this and other cytokines may account for th e different consequences of lung infection with different types of Ad.